Medicine » Immunology, Allergology and Rheumatology » "Acute Phase Proteins - Regulation and Functions of Acute Phase Proteins", book edited by Francisco Veas, ISBN 978-953-307-252-4, Published: October 5, 2011 under CC BY 3.0 license

Chapter 2

Acute Phase Proteins: Structure and Function Relationship

By Sabina Janciauskiene, Tobias Welte and Ravi Mahadeva
DOI: 10.5772/18121

Article top

Acute Phase Proteins:Structure and Function Relationship

Sabina Janciauskiene1, Tobias Welte1 and Ravi Mahadeva2

1. Introduction

The acute-phase response is critical to the body's ability to successfully respond to injury. It normally lasts only few days; however, if continued unchecked, the acute phase response may contribute to the development of chronic inflammatory states, tissue damage and disease. The acute phase response is typically characterized by fever and changes in vascular permeability, along with profound changes in the biosynthetic profile of various acute phase proteins (APPs) (Hack et al., 1997, Gabay & Kushner, 1999). APPs are an evolutionarily conserved family of proteins produced mainly in the liver in response to infection and inflammation. In all mammalian species, the synthesis of the APPs is mainly regulated by inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1 (IL-1) and tumor necrosis factor (TNF). For instance, haptoglobin (Hp), C-reactive protein (CRP), serum amyloid A (SAA), alpha-1 acid glycoprotein (AGP) and hemopexin are regulated mainly by IL-1 or combinations of IL-1 and IL-6, whereas fibrinogen, alpha-1 antichymotrypsin (ACT) and alpha-1 antitrypsin (AAT) are regulated by IL-6 (Koj, 1985; Kushner & Mackiewicz, 1993). Exogenous glucocorticoids can also influence APPs by their effect on cytokines. The decreased synthesis of albumin during the inflammatory reaction has also been shown to be the result of monocyte/macrophage-derived products, such as IL-1 (Moshage et al., 1987). The concentration of specific blood APPs varies during inflammatory states; increasing or decreasing by at least 25 percent (Kushner et al., 1982). Indeed, ceruloplasmin concentrations can increase by 50 percent and CRP and serum amyloid A by a 1000-fold (Kushner et al., 1981, Dinarello, 1983, Blackburn, 1994, Gruys et al., 1994, Ingenbleek & Bernstein, 1999).

The rise in the plasma concentration of APPs can assist host defense by aiding recognition of invading microbes, mobilization of leukocytes into the circulation, and increasing blood flow to injured or infected sites. These actions favor the accumulation of effector molecules and leukocytes at locally inflamed sites; in essence, they enhance local inflammation and antimicrobial defense. Concurrently, the APPs also prevent inflammation in uninvolved tissues by neutralizing inflammation-induced molecules (such as cytokines, proteases, and oxidants) that enter the bloodstream, by diminishing the proinflammatory responses of circulating leukocytes, and by forestalling endothelial activation.

A particularly important role for APPs in the establishment of host defense is also suggested by the magnitude and rapidity of changes in concentrations of APPs, together with their short half-life. This is also supported by the known functional capabilities of the APPs, and hence theories as to how they might serve useful purposes in inflammation, healing, or adaptation to a noxious stimulus. The functional activities of APPs as well as the relationship between protein structure and function are discussed in this chapter.

2. Diverse functional activities of acute phase proteins (APPs)

APPs are regarded as both mediators and inhibitors of inflammation operating at multiple possible sites. The classic complement components, many of which are APPs, have central proinflammatory roles in immunity. Complement activation leads to chemotaxis, plasma protein exudation at inflammatory sites, and opsonization of infectious agents and damaged cells. Other APPs such as fibrinogen, plasminogen, tissue plasminogen activator (tPA), urokinase and plasminogen activator inhibitor-I (PAI-1) play an active role in tissue repair and tissue remodelling (Gabay & Kushner, 1999). APPs also have antiinflammatory actions. For example, the antioxidants haptoglobin and hemopexin protect against reactive oxygen species, and AAT and ACT both antagonize the activity of proteolytic enzymes (Janciauskiene, 2001). Some metal chelating proteins, such as ceruloplasmin, that binds copper, and hemopexin, that binds heme, act more directly against pathogens. Other proteins are directly involved in the innate immunity against pathogens. LPS-binding protein (LPS-BP), for example, interacts with bacterial lipopolysaccharide (LPS) transferring it to CD14, a receptor on the surface of macrophages and B-cells. Following the presentation of LPS by LBP, a lipopolysaccharide recognition complex is formed on the membrane via the recruitment of a second receptor, Toll Like Receptor 4. These events drive the TLR signaling pathway that induces the activation of several inflammatory and immune-response genes, including pro-inflammatory cytokines (Gutsmann et al., 2001). Some APPs might act as protectors against cell death by apoptosis. For example, alpha 1-acid glycoprotein (AGP) and AAT have been shown to inhibit the major mediators of apoptosis, namely caspase-3 and caspase-7 (Van Molle et al., 1999). There are many diseases where induction of specific APPs parallels the degree and evolution of the inflammatory processes, hence, elevated APPs can be of diagnostic and prognostic value. The pathogenic role of fibrin in thrombosis is well known. CRP has been demonstrated to enhance ischemia/reperfusion injury by activating the complement system (Lu et al., 2009). Elevated serum values of CRP are known to be associated with an increased risk of human atherosclerosis. Ferritin, another APP, is a primary iron-storage protein and often measured to assess a patient's iron status. Procalcitonin (PCT), was discovered recently as a marker of bacterial infection (Assicot et al., 1993). On the other hand, APPs can be considered as putative drugs for the treatment of various inflammatory diseases. Different experimental studies have demonstrated how the administration of a specific APP prior to or after the initiation of an acute-phase response can switch the pro-inflammatory to the anti-inflammatory pathway necessary for the resolution of inflammation. In this regard, purified plasma AAT is used for the treatment of emphysema and other diseases in patients with inherited AAT deficiency and shows anti-inflammatory and immune modulatory effects.

3. Multifunctional activities of single APP

Despite vast pro- and anti-inflammatory properties ascribed to individual APPs, their role during infections remains incompletely defined as to the functional advantages acquiring from changes in plasma concentrations of the APPs. So far, existing data provide evidence that APPs act on a variety of cells involved in the early and late stages of inflammation and that their effects are time, concentration and molecular conformation-dependent (Figure 1). Many APPs have a duel function; amplifying inflammatory responses when the inciting pathogen is present within the host and down-regulating the response when the pathogen has been eradicated.


Figure 1.

Schematic presentation of factors that may affect activities of APPs.

3.1. C-reactive protein (CRP)

C-reactive protein (CRP) is a member of the pentraxin family of proteins, which are serum opsonins, which bind to damaged membranes and nuclear autoantigens. CRP has an ability to recognize pathogens and to mediate their elimination by recruiting the complement system and phagocytic cells, thus making it an important member of the first line of innate host defense. The normal concentration in healthy human serum is usually lower than 10 mg/L, increasing slightly with age. Current research suggests that subjects with elevated basal levels of CRP are at an increased risk of diabetes (Pradhan et al., 2001, Dehghan et al., 2007), hypertension and cardiovascular disease (Koenig et al., 2006). CRP is an ancient protein whose biological role appears quite complex. Although, originally CRP was suggested to be purely a biomarker, recent studies have pointed that it may in fact be a direct mediator of patho-physiological processes. It is likely that the activity of CRP in humans, either pro- or anti-inflammatory is dependent on the context in which it is acting, and thus CRP may be more versatile than previously thought.

3.1.1. Pro-inflammatory effects of CRP

CRP displays pro-inflammatory effects by activating the complement system and inducing inflammatory cytokines and tissue factor production in monocytes. The binding of phosphocholine and the complement pathway component (C1q) by CRP is part of innate immunity that activates the classical complement pathway (Gabay & Kushner, 1999; Du Clos, 2000). Data on the consumption of complement components and cell lysis have indicated that CRP-initiated complement activation is restricted to the formation of the C3 convertase (Berman et al., 1986). Formation of the alternative pathway amplification convertase and of C5 convertases is inhibited by factor H (Mold et al., 1984), which binds directly to CRP (Mold et al., 1999). The interactions between CRP and its diverse ligands, such as phosphocholine or Fcγ receptors, has the potential to influence a variety of cells and pathways with the potential to affect: apoptotic cells (Gershov et al., 2000), damaged cell membranes (Volanakis & Wirtz, 1979), phagocytic cells (Ballou & Lozanski, 1992), smooth muscle cells (Hattori et al., 2003), and endothelial cells (Pasceri et al., 2000). Experimental evidence for the binding of CRP to apoptotic cells was provided recently (Gershov et al., 2000). The distribution of CRP on the surface of such cells is similar to that of the complement membrane attack complex. In addition to the membrane of intact injured cells, CRP also binds to membranes and nuclear constituents of necrotic cells. Several nuclear constituents, including histones (Du Clos et al., 1988), small nuclear ribonucleoproteins (Du Clos, 1989) and ribonucleoprotein particles (Pepys et al., 1994) have been shown to bind CRP in a calcium-dependent fashion, and CRP deposition to the nuclei of necrotic cells at sites of inflammation has been observed (Gitlin et al., 1977).

To date, experiments with monocytes have shown that CRP induces the production of inflammatory cytokines (IL-1, IL-6, TNFα, IL-8) (Ballou & Lozanski, 1992; Xie et al., 2005), the generation of reactive oxygen species (Zeller & Sullivan, 1992), leads to increased expression of tissue factor (Cermak et al., 1993), and affects cell chemotaxis (Whisler et al., 1986; Kew et al., 1990). Recently, Hanriot et al. (2008), investigating human monocytes exposed to CRP have confirmed the results of earlier studies on CRP-mediated induction of expression of numerous proinflammatory cytokine genes (with the exception of TNFα) and further evidenced increased expression of PAI-2, MCP-1, GRO-α, GRO-β, and the chemokine receptors CCR8 and CXCR4. It has also been demonstrated that isolated from serum and recombinant CRP can stimulate expression of the monocytic surface integrin CD11b and downregulate that of CD31 antigen (Woollard et al., 2002). Numerous reports in the literature document the role of CRP in atherogenesis. Epidemiological evidence reveals an association between elevated plasma CRP and atherosclerosis (Haverkate et al., 1997; Ridker et al., 1997; Koenig et al., 1999). Infusion of recombinant CRP in healthy men results in the activation of inflammation and coagulation (Bisoendial et al., 2005). In vitro, CRP has been shown to exert a direct proinflammatory and proatherosclerotic effect on vascular cells, as exemplified by: (1) induction of an increased expression of adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule- 1 (ICAM-1), and E-selectin (Pasceri et al., 2000); (2) stimulation of secretion of monocyte chemoattractant protein-1 (MCP-1) (Pasceri et al., 2001); and (3) facilitation of macrophage low-density lipoprotein (LDL) uptake (Verma et al., 2002a). Transcription of genes encoding the cell adhesion molecules (VCAM-1, ICAM-1, E-selectin) and chemokines is tightly regulated by the transcription factor NF-κB, which has been implicated as a key mediator of atherosclerosis (Brand et al., 1996; Marumo et al., 1997; Thurberg & Collins, 1998; De Martin et al., 2000). However, with regard to the effects of CRP on endothelial cells, published studies are somewhat controversial. CRP has been shown to promote production of pro-angiogenic molecules such as endothelin-1 and IL-6 in human saphenous vein endothelial cells (Verma et al., 2002), and activate NF-κB signalling through the CD32 receptor (Liang et al., 2006). However, other studies suggested that endothelial cell activation by CRP is due to contamination of the commercially obtained protein with LPS and/or sodium azide (Liu et al., 2005, Taylor et al., 2005).

3.1.2. Anti-inflammatory effects of CRP In vitro

CRP appears to express anti-inflammatory properties. For example, in monocytic cells CRP has been shown to increase the synthesis of interleukin-1-receptor antagonist (IL-1ra), to up-regulate vascular endothelial growth factor A (VEGF-A) expression (Tilg et al, 1993), to increase the release of the anti-inflammatory cytokine IL-10 (Mold et al, 2002; Szalai et al, 2002) and to repress the synthesis of IFN-γ (Szalai et al, 2002). Furthermore, CRP has been reported to display anti-inflammatory effects in monocytes through down-regulation of alpha2-macroglobulin expression and up-regulation of liver X receptor α expression (Hanriot et al., 2008). CRP was found to bind to a ligand on Leishmania donovani and phosphorylcholine-expressing Neisseria meningitides, and hence increase their uptake by human phagocytes (Culley et al., 1996, Casey et al., 2008). Thomas-Rudolph et al (2007) have also reported that innate recognition by CRP enhances effective uptake and presentation of bacterial antigens through Fc-gamma receptors on dendritic cells and stimulates protective adaptive immunity. CRP has been shown to express multiple anti-inflammatory effects on neutrophils. CRP down-regulates the generation of superoxide by activated neutrophils which leads to a significant reduction of intracellular protein phosphorylation. IL-8-, formyl-methionyl-leucyl-phenylalanine (fMLP)-, and the complement component C5a-induced chemotactic responses of neutrophils are also found to be inhibited by CRP (Zhong et al., 1998). Inhibition of neutrophil chemotactic responses by CRP correlates with a reduction of chemotactic peptide-induced p38 kinase activity (Heuertz et al., 1999). In addition, CRP has been reported to induce cleavage and shedding of L-selectin from the surface of neutrophils, and markedly attenuate the attachment of human neutrophils to endothelial cells (Zouki et al., 1997). Finally, CRP has been shown to mediate shedding of the membrane-bound IL-6 receptor from neutrophils (Jones et al., 1999). The combined data on the effects of CRP on neutrophils indicate that this protein can limit the inflammatory response. In vivo

A variety of studies utilizing exogenous or transgenic CRP have probed the effects of CRP in vivo. The ability of CRP to protect mice against bacterial infection by various species has been well established. These species include S. pneumoniae (Mold et al., 1981; Szalai et al., 1995) and Haemophilus influenza (Weiser et al., 1998; Lysenko et al., 2000), which have phosphocholine-rich surfaces, and Salmonella enterica serovar Typhimurium, which has no known surface phosphocholine, although its cell membrane is known to be rich in another CRP ligand, phosphoethanolamine (Szalai et al., 2000). Protection is presumably mediated through CRP binding to phosphocholine or phosphoethanolamine, followed by activation of the classical complement pathway. CRP protection of mice infected with S. pneumoniae has been shown to require an intact complement system, but does not require interaction with FcγRs (Mold et al., 2002; Szalai et al., 2002). CRP`s protective effects are not limited to bacteria. It has been shown to play a protective role in a variety of inflammatory conditions, including endotoxin-mediated shock (Mold et al., 2002; Xia et al., 1997). Transgenic mice expressing human CRP are resistant to experimental allergic encephalomyelitis (Szalai et al, 2002). The study by Heuertz and collaborators has demonstrated that pretreatment of rabbits with purified human CRP intravenously significantly reduces neutrophil infiltration and C5a-induced alveolitis (Heuertz at al., 1993). One of the most commonly studied animal models of human systemic lupus erythematosus (SLE) is the female NZB x NZW F mouse model (B/W). These mice, as with human SLE patients, develop high levels of autoantibodies to nuclear antigens, leading to circulating immune complexes, the renal deposition of immune complexes and renal pathology. In this experimental model a single injection of human CRP not only markedly delayed the development of proteinuria, but also reversed ongoing active nephritis. The half-life of CRP in mice is only 4 hours (Kushner et al, 1978), however, despite the rapid clearance of injected CRP, the downregulation of the inflammatory process in the kidney persisted for more than 2 months. This suggests that CRP is most likely to be a direct regulator of the inflammation induced by immune complex deposition. In support of this B/W mice transgenic for human CRP also show a delayed onset of proteinuria and enhanced survival compared with non-transgenic B/W mice (Rodriguez et al., 2005). A single injection of CRP both prevents and reverses accelerated nephrotoxic nephritis (NTN) in C57BL/6 mice (Rodriguez et al., 2005) indicating that CRP-induced suppression of immune complex-mediated inflammation is not limited to autoimmune nephritis. Protection from NTN by CRP was associated with a decrease in inflammatory and pathologic changes in glomeruli and a marked reduction in renal expression of IL-1β and other macrophage chemoattractants (Rodriguez et al, 2007).

3.2. Alpha1-acid glycoprotein (AGP)

AGP is another example of an APP with multiple biological effects. AGP belongs to the lipocalin family, a group of proteins sharing a similar three-dimensional structure capable of binding and carrying hydrophobic molecules. The normal range of AGP concentration in the serum is 0.5-1.0 g/L, which can be increased several-fold in response to inflammation, infection, and systemic tissue injury (Engstrom et al., 2004; Lind et al., 2004). AGP function is still unknown; however, this protein is suggested to have a complex role by differentially regulating inflammatory responses (Logdberg & Wester, 2000; Fournier et al., 2000). So far, the most important function of AGP is linked to its ability to inhibit platelet aggregation (Snyder & Coodley, 1976; Costello et al., 1979).

3.2.1. Pro-inflammatory effects of AGP

Earlier studies have shown that AGP can activate monocytes, induce T cell proliferation (Singh & Fudenberg, 1986) and enhance TNFα, IL-1, and IL-6 secretion (Boutten et al., 1992; Drenth et al., 1996; 205 - media/image3.jpg#14.5;14.5Su & Yeh, 1996). More recently it has been demonstrated that AGP activates human monocytes to secrete TNFα through a tyrosine kinase dependent pathway and this can be enhanced in the presence of serum AGP-binding proteins. Since TNFα can also trigger the synthesis and secretion of AGP, the increase in TNFα secretion by AGP-stimulated monocytes may represent a positive feedback of APPs to amplify the inflammatory signal (Su et al., 1999). A current study evaluated the effects of bovine AGP on neutrophil pro-inflammatory responses, including respiratory burst activity and cytokine production, and found that bovine AGP enhanced neutrophil production of IL-8 in a dose-dependent manner (Rinaldi et al., 2008)3.2.2. Anti-inflammatory effects of AGP In vitro

AGP has been shown to induce macrophage expression of IL-1ra and soluble TNF receptor, which antagonize the activity of IL-1β and TNFα, respectively (Tilg et al., 1993, Hochepied et al., 2003). Sorensson and colleagues (1999) reported that endothelial barrier functions are dependent on the presence of AGP. A number of studies have investigated the effects of AGP on neutrophil function. At physiological concentrations, human AGP has inhibitory effects on neutrophil chemotactic responses after stimulation with fMLP and the complement component C5a (Laine et al., 1990, Vasson et al., 1994). Moreover, it has been shown that low doses of AGP promote neutrophil aggregation, while higher doses inhibit this response (Laine et al., 1990). Neutrophil respiratory burst activity is also reported to be modulated by AGP, and several studies have demonstrated that human AGP can inhibit the extracellular release of superoxide anion after activation with opsonized zymosan or phorbol 12-myristate,13-acetate (PMA) (Costello et al., 1984; Vasson et al., 1994). Bovine AGP inhibited zymosan-induced neutrophil extracellular release of superoxide anion and hydrogen peroxide without affecting the capacity of neutrophils to engulf and kill Staphylococcus aureus. Interestingly, AGP exerted its effect on free radical production regardless of whether neutrophils were exposed to AGP prior to or after activation (Rinaldi et al., 2008). In vivo

Several studies have shown that AGP may function as an immune modulator displaying a protective effect in different models of shock. In a model of bacterial septic shock, using the gram-negative Klebsiella pneumoniae, AGP showed clear protection when given prior to the lethal challenge (Fournier et al., 2000). Furthermore, AGP was found to inhibit apoptosis and inflammation in murine models, and to induce cAMP-dependent signaling in the endothelial cells (Libert et al., 1994; Costello et al., 1979). Using Escherichia coli LPS, an initiator of the acute inflammatory response associated with septic shock, Morre DF and coworkers (1997) demonstrated that AGP-LPS complexes can activate mouse macrophages in vitro and that AGP protects against sepsis. It has also reported that AGP protects mice from lethal shock induced by TNFα or endotoxin. The protection was observed in both normal and in galactosamine-sensitized mice; with optimal desensitization requiring at least 3 mg of AGP administered 2 hours before the lethal challenge. Under these conditions, complete inhibition of all TNF-induced metabolic changes was observed (Libert et al., 1994). In another model, AGP has been found to significantly increase survival rate (48 hours) in rats with septic peritonitis. This effect was seen when AGP (200 mg/kg i.v.) was given 15 min prior to and 24 hours after cecal puncture. In a hemorrhagic/hypovolemic shock model (including a defined trauma) in rats treated with 200 mg/kg AGP resulted in significantly higher values of mean arterial blood pressure, cardiac output and stroke volume when compared to corresponding values obtained after resuscitation with Ringer's solution or- intravenous albumin (Muchitsch et al., 1998). In addition, AGP has been found to be protective against ischemia reperfusion in kidneys (Daemen et al., 2000). According to the results of this study AGP and AAT administered at reperfusion prevented apoptosis at 2 hours and 24 hours and exerted anti-inflammatory effects, as indicated by reduced renal TNF-α expression and neutrophil influx after 24 hours leading to improved renal function. Administration of AGP and AAT 2 hours after reperfusion resulted in a similar trend but without functional improvement. Moreover ischemia reperfusion elicited an acute phase response, as reflected by elevated serum AGP and serum amyloid P (SAP) levels after 24 hours, and increased hepatic acute phase protein mRNA levels after 18 hours of renal reperfusion. Other useful physiological effects of AGP include protection against brain edema formation after experimental stroke (Pichler et al., 1999), and injuries after intestinal ischemia (Williams et al., 1997).

3.3. Alpha1-antitrypsin (AAT)

Alpha1-Antitrypsin (AAT), also referred to as alpha1-proteinase inhibitor or SERPINA1, is the prototypical member of the SERPIN (an acronym for serine proteinase inhibitor) family of protease inhibitors (Carrell, 1986). The normal plasma concentration of AAT ranges from 0.9 to 1.75 g/L. AAT is present in all tissues and biological fluids including cerebrospinal fluid, saliva, tears, breast milk, semen, urine and bile. Over 100 alleles of AAT have been identified to date, of which at least 20 affect either the amount or the function of the AAT molecule in vivo (Gooptu & Lomas, 2009). The genes are inherited as co-dominant alleles (products of both genes can be found in the circulation). Individuals with plasma AAT values below 0.7 g/L are considered to be AAT deficient. In very rare circumstances individuals may inherit AAT null alleles which are characterized by very low levels of serum AAT. AAT deficiency typically results from point mutations causing a perturbation in protein structure and resulting in increased intracellular polymerization and retention in the cell of synthesis. Retained AAT polymers in the endoplasmic reticulum of hepatocytes can promote liver damage with a variable clinical presentation, from neonatal hepatitis to liver cirrhosis and hepatocellular carcinoma in adults. The lack of circulating protein predisposes to the development of early-onset COPD (Carrell & Lomas, 1997). AAT deficiency has also been associated with a number of other inflammatory diseases, although the association is only moderate or weak. These include bronchial asthma, bronchiectasis, systemic vasculitis, rheumatoid arthritis, inflammatory bowel diseases, intracranial and abdominal aneurysms, arterial dissections, psoriasis, chronic urticaria, mesangiocapillary glomerulonephritis, pancreatitis and pancreatic tumors, multiple sclerosis, and other occasionally reported conditions (Janciauskiene et al., 2011).

3.3.1. Anti-inflammatory effects of AAT In vitro

It was previously thought that the primary function of AAT was to inhibit neutrophil elastase and proteinase 3 (Gettings, 2002). However, current studies demonstrate that AAT is an irreversible inhibitor for kallikreins 7 and 14 (Schapira et al., 1982; Luo et al., 2006), and that AAT also inhibits intracellular and cell-surface proteases. Matriptase, a cell surface serine protease involved in the activation of epithelial sodium channels, is one such protease (Tseng et al., 2008; Janciauskiene et al., 2008). AAT also inhibits the activity of caspase-3, an intracellular cysteine protease which plays an essential role in cell apoptosis (Petrache et al., 2006). A recent study provides new evidence that AAT inhibits ADAM-17 activity, also called TACE (tumor necrosis factor-α-converting enzyme) (Bergin et al, 2010). We recently found that AAT inhibits calpain I which is implicated in numerous pathological conditions including Alzheimer’s disease, demyelination events of multiple sclerosis, neuronal damage after spinal cord injury and hypoxic/ischaemic injury to brain, kidney and heart organs, and tumour development and invasion (Al-Omari et al., 2011). The ability of AAT to inhibit neutrophil calpain I was related to intracellular entry of AAT via lipid rafts (Subramaniyam et al., 2010), a transient rise in intracellular calcium, increase in intracellular cholesterol esters, activation of the Rho GTPases, Rac1 and Cdc42, and extracellular signal-regulated kinase (ERK1/2). Furthermore, AAT caused a significant inhibition of non-stimulated as well as formyl-met-leu-phe (fMLP)-stimulated neutrophil adhesion to fibronectin, inhibited lipopolysaccharide (LPS)-induced IL-8 release and slightly delayed neutrophil apoptosis (Al-Omari M et al 2011). Recently, AAT was found to bind to IL-8 and to inhibit IL-8 interaction with its receptor CXCR1 (Bergin et al., 2010). AAT plays an immunoregulatory role, to inhibit neutrophil superoxide production, to enhance insulin-induced mitogenesis in various cell lines, and to induce IL-1ra expression (Bucurenci et al., 1992; She et al., 2000; Tilg et al., 1993). Findings that AAT enhances the synthesis of both transferrin receptor and ferritin revealed a role of AAT in iron metabolism (Graziadei et al, 1997). Interestingly, AAT has been shown to regulatete heme oxygenase-1 activity in Alzheimer´s disease patients (Maes et al., 2006). AAT has also been found to bind to the secreted enteropathogenic Escherichia coli proteins (EspB, EspD), thereby reducing their hemolysis of red blood cells (Knappstein et al., 2004). An interaction between AAT and Cryptosporidium parvum (Forney et al., 1996), a protozoan parasite, has been shown to inhibit Cryptosporidium parvum infection, suggesting a potential role for AAT in cryptosporidiosis. AAT inhibits endotoxin-stimulated TNF, IL-6, IL-1β and enhances IL-10 expression in human monocytes, neutrophils, endothelial cells (Janciauskiene et al., 2007) AAT also expresses a broad anti-inflammatory profile in gene expression studies on primary human lung microvascular endothelial cells, including the suppression of self-induced TNF expression (Subramaniyam et al., 2008). Current studies provide further evidence that AAT therapy prolongs islet graft survival in transplanted allogeneic diabetic mice (Lewis et al., 2008) and show that AAT stimulates insulin secretion and protects β-cells against cytokine-induced apoptosis, and these effects of AAT also seem to be mediated through the cAMP pathway (Kalis et al., 2010). In view of these novel findings, it is suggested that AAT may act as an anti-inflammatory compound to protect β-cells under immunological attack in type 1diabetes, and also raise the possibility of a new therapeutic strategy to potentiate insulin secretion in type 2 diabetes (Koulmanda et al., 2008).

AAT has also been found to express dual, time-dependent effects. Both in vitro and in vivo studies have shown that within a short time (2 to 4 hours) AAT amplifies endotoxin (LPS)-induced pro-inflammatory responses whereas after 18-48 hours AAT significantly inhibits LPS-induced TNFα, IL-1β and IL-8 expression and release, and enhances IL-10 synthesis (Subramaniyam et al., 2010).This finding point to hypothesis that AAT can regulate the progression and resolution of the acute-phase reaction in a time-dependent manner. The overall view that arises from the current data is that short-term enhancement of LPS-induced cell activation may be the key mechanism by which the function of AAT is accomplished. In keeping with this, several in vitro and in vivo studies have been published in which prior initiation of an acute-phase response or administration of a specific APP has been shown to switch the pro-inflammatory to the anti-inflammatory pathways necessary for the resolution of inflammation. In vivo

AAT has been found to significantly protect against the lethality induced by TNFα or endotoxin in mice (Libert et at., 1996). The protection is optimal with a single dose of at least 300 μg i.p. or 100 μg i.v. given 2 hours before a lethal challenge, either with a low dose of TNFα in the presence of galactosamine or a higher dose of murine TNF alone. Under optimal conditions, the drop in body temperature, the release of liver transaminases, and the increase in clotting time are also inhibited. Similarly, Jie and co-workers (2003) have shown that pretreatment with AAT (120 mg/kg) can attenuate acute lung injury in rabbits induced with endotoxin. The pretreatment of AAT attenuated the deterioration of oxygenation, the reduction of compliance and the deterioration of other physiological and biochemical parameters mentioned above. In agreement, we currently found that pre-treatment with AAT protects mice against LPS-induced lung injury, inhibits LPS-induced pro-inflammatory genes and enhances the expression of genes associated with tissue repair and regeneration (unpublished data). In another model, Churg et al, (2001) have demonstrated that at 2 hours after dust administration, AAT completely suppressed silica-induced neutrophil influx into the lung and macrophage inflammatory protein-2 (MIP-2)/monocyte chemotactic protein-1 (MCP-1) (neutrophil/macrophage chemoattractant) gene expression, partially suppressed nuclear transcription factor -kB (NF-kB) translocation, and increased inhibitor of NF-kB (IkB) levels. By 24 hours, PMN influx and connective tissue breakdown measured as lavage desmosine or hydroxyproline were still at, or close to, control levels after AAT treatment. In the recent study by Lewis e al., (2005), diabetic mice were grafted with allogeneic islets and treated with AAT monotherapy. After 14 days of treatment, mice remained normoglycemic and islet allografts were functional for up to 120 treatment-free days. After graft removal and retransplantation, mice accepted same-strain islets but rejected third-strain islets, thus confirming that specific immune tolerance had been induced. Explanted grafts exhibited a population of T regulatory cells in transplant sites. Grafts also contained high levels of mRNA for foxp3, cytotoxic T lymphocyte antigen-4, TGF-β, IL-10, and IL-1 receptor antagonist, but expression of pro-inflammatory mediators was low or absent. After implantation of skin allografts, AAT-treated mice had greater numbers of foxp3-positive cells in draining lymph nodes compared with control treatment mice. Moreover, dendritic cells exhibited an immature phenotype with a decrease in the activation marker CD86. Although the number of CD3 transcripts decreased in the DLNs, AAT did not affect IL-2 activity in vitro. AAT monotherapy provides allografts with anti-inflammatory conditions that favor development of antigen-specific T regulatory cells. AAT treatment in humans is known to be safe, hence its use during human transplantation may be considered. Augmentation therapy with AAT in patients

Based on the protease-antiprotease hypothesis, augmentation therapy was introduced for COPD patients with severe (ZZ) AAT deficiency during the 1980s. The major concept behind augmentation therapy was that raising the levels of blood and tissue AAT would protect the lungs from continuous destruction by proteases, particularly neutrophil elastase. Whether this biochemical normalization of AAT levels influences the pathogenic processes of COPD is still under debate. However, recent results do suggest that augmentation therapy may have beneficial effects including reducing the frequency of lung infections and reducing the rate of decline of lung function. Several non-randomized observational studies and one meta analysis on the clinical effectiveness of AAT augmentation treatment showed a favorable result regarding lung function (FEV1) in AAT-deficient COPD patients with moderate disease undergoing augmentation therapy (Chapman et al, 2009; Stockley et al, 2009).

Clinical studies provide evidence that augmentation therapy with AAT reduces the incidence of lung infections in patients with AAT deficiency-related emphysema and reduces levels of the chemoattractant leukotriene B4. A study by Lieberman and co-workers (2000) showed that augmentation therapy with AAT is associated with a marked reduction in the frequency of lung infections in the majority of patients. Most patients reported a frequency of three to five infections per year before starting AAT therapy, which dropped to zero to one infection per year while receiving AAT. In two patients with a prior history of continuous lung infections, AAT therapy was associated with the complete absence of infection in one patient and with one to two infections per year in the second. It was also reported that aerosolized AAT suppresses bacterial proliferation in a rat model of chronic Pseudomonas aeruginosa lung infection (Kueppers et al., 2011)

Several case reports support the beneficial effects of AAT augmentation therapy in other clinical conditions. Two ZZ AAT Spanish sisters with fibromyalgia experienced a rapid, progressive, and constant control of their fibromyalgia symptoms during AAT augmentation therapy (Blanco et al, 2006). Another report described a 21yr old a ZZ AAT female with septal panniculitis which was poorly responsive to dapsone and doxycycline treatment, who was successfully treated with intravenous infusion of AAT (Gross et al., 2008). Recently Chowdhury and collaborators have described a 33-year-old ZZ AAT woman with rapidly progressing panniculitis and extensive skin necrosis. Augmentation therapy with AAT proved to be life saving (Chrowdhury et al., 2002). Cutaneous vasculitis in a 49-year-old man with AAT deficiency persisted despite treatment with colchicine, prednisone, and antibiotics, but has been effectively controlled with the administration of AAT (Dowd et al., 1995). In addition, Griese et al, 2007 examined the effect of 4 weeks of AAT inhalation on lung function, protease-antiprotease balance and airway inflammation in Cystic Fibrosis (CF) patients. In a prospective, randomised study, 52 CF patients received a daily inhalation of 25 mg AAT for 4 weeks targeting their peripheral or bronchial compartment. Inhalation of AAT increased AAT levels and decreased the levels of elastase activity, neutrophils, pro-inflammatory cytokines and the numbers of P. aeruginosa. However, it had no effect on lung function. No difference was found between the peripheral and bronchial mode of administration. In conclusion, although no effect on lung function was observed, the clear reduction of airway inflammation after AAT treatment may precede pulmonary structural changes.

3.4. Other examples of multifunctional APPs

3.4.1. Haptoglobin (Hp)

Haptoglobin (Hp) is homologous to the serine proteases of the chymotrypsinogen family but has no serine protease activity (Kurosky et al, 1980). Hp exists in two allelic forms in the human population, so-called Hp1 and Hp2, the latter one having arisen due to the partial duplication of the Hp1 gene. Plasma haptoglobin levels change during life, with Hp levels in healthy infants being lower than in healthy adults. In healthy adults, the haptoglobin concentration in plasma is 0.38-2.08 g/L (Javid, 1978). Hp, by binding hemoglobin and removing it from the circulation, prevents iron-stimulated formation of oxygen radicals and has an important role as an antioxidant (Sadrzadek & Bozorgmehr, 2004). Both in vitro and in vivo studies have established that subjects with the Hp1-1 phenotype are more likely to resist cellular oxidative stress than those with the Hp2-2 phenotype, with Hp2-1 being intermediate (222 - Tseng et al., 2004). Hp has been shown to play an antioxidant/anti-inflammatory role, to contribute to neutrophil activation, to maintain reverse cholesterol transport, to modulate the inhibition of cyclooxygenase and lipooxygenase, and to inhibit monocyte and macrophage functions amongst other activities. For instance, Hp inhibited respiratory burst activity in neutrophils stimulated with fMLP, arachidonic acid, and opsonized zymosan (Oh et al, 1990), inhibited phagocytosis and reduced intracellular bactericidal activities of granulocytes (Rossbacher et al, 1999). Moreover, Hp has been found to stimulate the formation of prostaglandin E2 in osteoblast-like cells, and to potentiate the stimulatory effect of bradykinin and thrombin on PGE2 formation (Frohlander et al, 1991, Lerner & Frohlander, 1992). Hp has also been shown to support angiogenesis (Cid et al, 1993). It has been suggested that the increased levels of Hp found in chronic inflammatory conditions may play an important role in tissue repair. In systemic vasculitis, Hp might also compensate for ischemia by promoting the development of collateral vessels. By enhancing the Th1 cellular response, Hp establishes Th1-Th2 balance in vitro (Arredouani et al., 2003). Hp also inhibits epidermal Langerhans cells in the skin and might have a role in preventing T cell–dependent skin disorders (Pagano et al., 1982). In addition, Hp inhibits cathepsin B and L and decreases neutrophil metabolism and antibody production in response to inflammation (Oh et al., 1990, Pagano et al., 1982). Iron is one of the essential elements for bacterial growth. However, once bound to Hp, hemoglobin and iron are no longer available to bacteria that require iron, such as Escherichia coli. Indeed, Eaton and collaborators showed that a fatal consequence of intra-peritoneally injected Escherichia coli and hemoglobin in rats can be prevented by the administration of Hp (Eaton et al, 1982). In the lungs, Hp is synthesized locally and is a major source of antimicrobial activity in the mucous layer and alveolar fluid and also has an important role in protecting against infection (Yang et al., 1995). Hp-hemoglobin complexes in human plasma inhibit endothelium dependent relaxation (Edwards et al, 1986).

3.4.2. Serum amyloid A (SAA)

SAA structurally resembles an apolipoprotein, and is mainly transported in association with lipoprotein particles, particularly high-density lipoprotein (HDL) (Eriksen & Benditt, 1980). The SAA concentration of serum/plasma samples ranges from 1-5 μg/ml. During an acute phase response, SAA becomes the main apolipoprotein on HDL, and the displaced Apo-AI then becomes available to extract cellular free cholesterol upon interacting with cell-surface (Tam et al., 2008). For this reason, and because SAA itself may also extract cholesterol from cells (Stonik et al., 2004), it is thought that SAA plays a role in cholesterol metabolism and atherosclerosis (Jahangiri et al., 2009). Whether SAA is pro- or anti-atherogenic is not yet clear, since putative beneficial effects on cholesterol metabolism may be mitigated by effects on inflammation- a known risk factor for atherosclerosis (Libby et al., 2002). Some of the effects described for SAA seem to be minimized or abolished by its association with HDL (Barter et al, 2004). The very high expression of SAA gives rise to a completely different pathological problem: the continuous high expression of SAA is the prerequisite for the development of secondary amyloidosis, caused by the conformational change of SAA in an insoluble proteolytic peptide, AA, that deposits as insoluble plaque in major organs (Malle & De Beer, 2003). In attempt to understand the biological role of SAA and of its association with HDL, it was demonstrated that SAA is able, for instance, to induce leukocyte migration (Connolly et al, 2010) and collagenase (Brinckerhoff et al., 1989), and to inhibit the TNFα and IL-1β- induced hypothalamic PGE2 synthesis (Tilg et al., 1993). Several other SAA activities have been described including increasing cleavage of triacylglycerols into glycerol and fatty acids on HDL3 by enhancing the activity of secretory phospholipase (Sullivan et al., 2009). SAA also directly acts on the cholesterol molecule by decreasing its esterification, and increases its uptake by hepatocytes (Steinmetz et al., 1989). Recent studies reveal that serum SAA also has a dual role in modulating neutrophil function. SAA induces the differentiation of interleukin 10 (IL-10)-secreting neutrophils via signaling dependent on the G protein–coupled protein FPR2 (formyl peptide receptor 2), but also promotes the interaction of neutrophils with invariant natural killer T cells (iNKT cells), restoring T cell proliferation by abolishing IL-10 secretion. The final process is dependent on the antigen-presenting molecule CD1d and co-stimulatory molecule CD40 and results in less production of IL-10 and enhanced production of IL-12, thus limiting the suppressive activity of neutrophils (De Santo et al., 2010). SAA may affect inflammatory responses by activating its putative receptor on neutrophils (FPRL1), leading to increased production of IL-8 (He et al., 2003). SAA is also thought to be able to activate TLR2- and TLR4- dependent signaling (Cheng et al., 2008). Recent reports suggest that SAA may also play a role in host defense, notably in the clearance of Gram-negative bacteria. Shah et al. demonstrated that SAA binds to the outer membrane protein A of Escherichia coli, which facilitates bacterial clearance by phagocytes (Shah et al., 2006). Such a bactericidal effect of SAA is intriguing in light of the reported expression of SAA in intestinal epithelia of rodents and humans, since these cells are exposed to many gram-negative bacteria (Berg, 1996). Intestinal epithelial expression of SAA protects from colitis by reducing bacterial load (Eckhardt et al., 2010).

3.5. Importance of the co-ordinated expression and biological activity of APPs

APP expression represents one of the most important and highly effective mechanisms of innate immunity. The wide range of defensive and repair functions fulfilled by APPs not only reduces pathologic damage, but also acts as a homeostatic mechanism. On the other hand APPs may also play pro-inflammatory roles and produce detrimental effects. Importantly, changes in different APPs occur at different rates and to different degrees. Ceruloplasmin and the complement components C3 and C4 exhibit relatively modest acute-phase behaviour (typically about a 50% increases). Concentrations of Hp, AGP, AAT, ACT, and fibrinogen ordinarily increase about 2–5-fold. CRP and SAA are normally present in only trace amounts, but may exhibit a dramatic increase (1000-fold or more) in individuals with severe infections. In contrast, plasma concentrations of negative APPs such as albumin, transferrin, transthyretin, alpha-fetoprotein, typically decrease during the acute-phase response. These orchestrated alterations in specific APP production during inflammatory states are not completely understood. However, the known functional capabilities of many of the APPs leads to the logical speculation that specific changes in APP expression serve useful purposes in inflammation, healing or adaptation to infection or injury. Moreover, current knowledge clearly indicates that during the acute phase reaction a single APP can play multiply roles, and that diverse APPs can possess very similar biological activities (Figure 3). The combined action of two or more APPs may produce effects that no single protein would be able to achieve.

For example, diverse APPs like AAT, AGP, Hp, and CRP can have similar anti-inflammatory and immuno- modulatory roles in experimental models in vitro and in vivo. AAT which is an archetypal member of the SERPIN superfamily, a main inhibitor of neutrophil elastase, and AGP a member of the lipocalin family, a group of proteins sharing a similar three-dimensional structure capable of binding and carrying hydrophobic molecules, both inhibit cell apoptosis, inhibit neutrophil chemotaxis and adhesion, inhibit neutrophil activation and induce macrophage-derived interleukin-1 receptor antagonist release, and protects mice from endotoxin-induced septic shock. Similarly, CRP (opsonin) and Hp (hemoglobin binder) inhibit neutrophil activation, including chemotaxis and superoxide production and degranulation. Thus, it seems that all these APPs, specifically in neutrophil models, show very similar effects. It cannot be excluded that these proteins may have more common characteristics and biological effects however the lack of high quality purified endotoxin or contaminant-free proteins limits expanding our current understanding.

A more detailed knowledge of the separate and combined APP functional pathways is essential in order to prevent or control development of various pathological conditions as well as to develop safe and effective anti-inflammatory therapies.


Figure 2.

Diverse APPs express similar anti-inflammatory activities.

4. APPs structure-function relationship

Post-translational modifications of proteins can regulate their function by causing changes in protein activity, their cellular location and dynamic interaction with other proteins. Virtually all proteins function by interacting with other molecules and these interactions can have numerous effects on the physical, structural, biochemical and functional properties of proteins. There are also different types of interactions on a protein-protein and protein-environment level which lead to complex formation, protein degradation, self-assembly or other modifications in protein structures, such as oxidation. The ability to undergo post-translational conformational changes is crucial for the physiological function of many proteins, including APPs. Similarly, such changes could alter both physicochemical and functional properties of the proteins with potential unforeseen physiological or pathological consequences. Conformational modification may lead to an acquired deficiency of specific APP, but also to the generation of new molecular forms with potent biological activities. The altered forms of APPs are detected in tissues and fluids recovered from inflammatory sites, but the important questions of how they are generated, what their biological activities are, and which of them are directly linked to pathological processes and/or may be useful markers to characterise disease states, remain to be answered. Glycosylation is one of the most important post-translational modifications of APPs, and has been widely acknowledged as one of the most important ways to modulate both protein function and lifespan. Glycosylation of APPs which is partially regulated by cytokines may be distinct in disease and provide useful disease markers.

4.1. Glycosylation of APPs

The N-glycan chains of APP glycoproteins differ in their branching, showing bi-, tri-, and tetra-antennary structures. Inflammatory states are usually associated with changes in the glycosylation profile of APPs. It has been demonstrated that there is an increased concentration of the conA-reactive microheterogeneous forms of APPs in patients with acute inflammation, e.g. acute bacterial infections and burns. Conversely, a shift in the population of APPs towards those with a higher content of conA-nonreactive tri- and tetra-antennary carbohydrates has been shown in the sera of patients with chronic inflammatory diseases (e.g. chronic bacterial infections, rheumatoid arthritis, ankylosing spondylitis) (Hrycaj et al., 1996, Stibler et al., 1998). An intriguing question is whether the changes in the glycosylation profile of APPs might affect their biological activity and/or function.

4.1.1. AGP

AGP purified from human plasma consists of a mixture of AGP with different degrees of sialylation and glycosylation. It has been demonstrated that microheterogeneity variants of AGP differ with regard to their immunomodulatory properties: the conA-nonreactive variant of AGP is more effective in modulating of lymphocyte proliferation than conA-reactive AGP variants. It has also been shown that AGP has an affinity for E-selectin and that this affinity can be changed by in vitro fucosylation of AGP (Mackiewicz et al. 1987). The highly branched and sialylated form of AGP which is the ligand for cell adhesion molecules such as E-selectin and P-selectin, inhibits migration of neutrophils, monocytes and T-cells, and modifies complement activity (Hrycaj et al., 1993).

Marked changes in AGP glycoforms are observed during acute-phase reactions. The changes comprise alterations in branching pattern as revealed by reactivity with concanavalin A and the fucose-binding lectin (Elliott et al., 1997). Thus analysis of sialo- and asialo-oligosaccharides of AGP as well as its glycoforms is important for understanding the biological roles of AGP (Kakehi et al., 2002, Sei et al., 2002). For example, the asialylated carbohydrate-deficient variant of AGP appears mainly in sera of patients after acute inflammation, infection, burns or other severe tissue damage (Fournier et al., 2000).

The expression of a sialyl Lewis x{sLex, NeuAcα2-3Galβ1-4(Fucα1-3)GlcNAc-} portion in the carbohydrate chains of human AGP molecules has been shown to be of importance in inflammation. De Graaf et al. (1993) found a direct relationship between the reactivity of human AGP to the fucose-specific binding lectin (Aleuria auranita) and staining of human AGP by anti-sLex monoclonal antibody under healthy and disease conditions.

In a recent study a recombinant form of sialyl Lewisx(sLex)-bearing (sAGP) was administered intravenously to rats after 50 min of intestinal ischemia just before 4 h of reperfusion. A non-sLex-bearing form of AGP (nsAGP) was used as control. sAGP-treated animals had a 62% reduction in remote lung injury, assessed by 125I-albumin permeability, compared with those treated with nsAGP. There was a reduction in pulmonary myeloperoxidase levels in sAGP-treated rats compared with nsAGP-treated rats. Complement-dependent intestinal injury, assessed by 125I-albumin permeability was reduced by 28% in animals treated with sAGP compared with those treated with nsAGP leading the authors to conclude that sAGP ameliorates both complement- and neutrophil-mediated injury (Williams et al., 1997).

The changes in the glycosylation pattern of AGP has been found in patients with ulcerative colitis (Ryden et al., 1997), and in patients with various liver diseases (alcoholic liver disease, hepatitis B, hepatitis C cirrhosis). For example, hyperfucosylation occurred in all cases of liver disease, although the hepatitis B and C samples showed a more significant increase in comparison with the others. Additionally N-acetylgalactosamine (GalNAc) was detected in the majority of the hepatitis C samples, which was unexpected since this monosaccharide is not a usual component of the N-linked oligosaccharide chains (Anderson et al., 2002).

In the group of Type I diabetic patients with increased urinary albumin excretion, a significant increase in alpha3-fucosylation of AGP could be detected. Therefore, the increased alpha3-fucosylation of AGP can be used as a putative marker for the development of vascular complications in Type I diabetic patients (Poland et al., 2001).

AGP and its derivatives, prepared by sequential enzymatic cleavage of the carbohydrate units, were tested for their nerve-growth-promoting activities with explants of whole dorsal root ganglia from chick embryos. The results showed that the AGP derivatives with terminal galactose, N-acetylglucosamine, or mannose have marked neurite-promoting activities (Liu et al., 1988).

4.1.2. Other APPs

AAT has a molecular weight of Mr 52 000, and is media/image5.gif#6;4.512% carbohydrate by weight. The AAT molecule carries a high negative charge because of sialic acid residues on the three complex glycans attached to asparagine residues 46, 83, and 247. Isoelectric focusing of plasma AAT leads to the detection of eight bands, which are numbered M1 to M8 (anodal-low pH to cathodal-high pH). The bands M4 and M6 are the most abundant of the isoforms, making up 40% and 34% of the total plasma AAT, respectively, whereas M3 and M5 are present in only trace amounts (Mills et al., 2001). Fucosylated AAT was analyzed individually and in combination with the currently used marker, alpha-fetoprotein, for the ability to distinguish between a diagnosis of cirrhosis and hepatocellular carcinoma (HCC). The levels of fucosylated AAT were significantly higher in patients with HCC compared to those with cirrhosis (Wang et al., 2009). Remarkably, non-glycosylated AAT showed shorter half life and no ability to interact with IL-8 than compared to glycosylated form of AAT (Bergin et al., 2010). This suggests an importance of AAT glycosylation for its biological activities.ACT (alpha 1-antichymotrypsin), a serine anti-protease with specificity against neutrophil cathepsin G, is homologous with AAT, plasminogen activator inhibitor and angiotensinogen. ACT is an APP with carbohydrate content 24% of molecular weight. As for other glycoproteins, micro-heterogeneity of ACT may be ascribed to differences in carbohydrate structure, and indeed different patterns of ACT micro-heterogeneity has been shown in different diseases including cancer, heart failure and rheumatoid arthritis (Saldova et al., 2008, Kazmierczak et al.,1995, Havenaar et al., 1998). A low content of terminal GlcNac glycans and sialic acid in peripheral ACT has been suggested as a marker of progression in Alzheimer’s disease (Ianni et al., 2010). The changes in patterns of glycosylation of transferrin (Tf) towards highly branched glycans have been observed in iron deficiency anaemia, rheumatoid arthritis, liver cirrhosis or in physiological state such as pregnancy. Differences in glycosylation of Tf seems to alter the metabolism of iron (Yang et al., 2005, van Pelt J et al., 1996, Dupre et al., 2001). Changes in the glycosylation pattern of major serum APPs such as Hp, AGP, AAT, Tf and alpha-fetoprotein have been recently shown in patients with pancreatic cancer and chronic pancreatitis (Sarrats et al., 2010)

4.2. Cleaved forms of AAPs

The cleaved modifications of APPs may lead to a functional deficiency of the protein, but the cleaved forms of APPs may themselves express new biological activities. For example, antithrombin which functions as an inhibitor of thrombin and other enzymes, has potent antiangiogenic and antitumour activity in its cleaved conformation.

4.2.1. CRP

CRP comprises five identical, non-covalently bound subunits of 206 amino acids (23,017 daltons) arranged in cyclic symmetry (Oliveira et al., 1979). One side of the pentamer participates in binding ligands such as phosphorylcholine, and the other side binds effector molecules such as C1q. When CRP is exposed to denaturing conditions in the presence of a chelating agent, the CRP pentamer is altered to form both individual subunits and aggregates (Gotschlich & Edelman, 1967) designated as modified-CRP (mCRP) (Potempa et al., 1983). The half-life of mCRP in the circulation is <5 min in mice (Motie et al., 1998) . These findings indicate that the transport of mCRP from circulation to various sites in the body most likely to be faster than pentameric CRP. mCRP displays antigenic, electrophoretic, and ligand binding reactivities distinct from pentameric CRP (Potempa et al., 1987). Currently has been reported that mCRP is much more potent than pentameric CRP in binding to modified LDL (Singh & Fudenberg, 2009).

Since extravasation and activation of neutrophil granulocytes are essential in the inflammatory response, the effects of CRP on these cells are of particular importance. Stimulation of neutrophils activates a membrane-associated serine protease which leads to the cleavage of biologically active peptides from CRP. CRP peptides 77–82 and 201–206 have been found to inhibit neutrophil chemotaxis to fMLP in vitro and to diminish neutrophil influx and protein leakage into alveoli after fMLP induced inflammation in mice (Zouki et al., 1997).

Neutrophil extravasation into inflamed or injured areas involves a complex interaction of leukocytes with endothelial cells via regulated expression of surface adhesion molecules. The initial attachment of neutrophils to endothelium is mediated by L-selectin (CD62L) (Díaz-González et al., 1995, Walcheck et al., 1996). L-Selectin is constitutively expressed by neutrophils and is released from neutrophils by proteolytic cleavage within minutes after activation with a concomitant upregulation of Mac-1 (CD11b/CD18). The monomeric CRP (but not nCRP) has been found to up-regulate CD11b/CD18 expression and extracellular signal regulated kinase (ERK) activity, suggesting that mCRP may participate in the promotion of neutrophil adhesion to endothelial cells (Zouki et al., 2001). In contrast to CRP, mCRP induces IL-8 secretion in neutrophils (Khreiss et al, 2005) and human coronary artery endothelial cells (Devaraj S et al., 2004), promotes neutrophil-endothelial cell adhesion (Zouki et al., 2001), and delays apoptosis of human neutrophils (Schwedler et al., 2006).

mCRP binds to a number of different ligands to CRP and also exhibits a different set of biologic activities. More recently, it has been shown that mCRP has profound inhibitory effects on tumor growth and metastatic ability of an adenocarcinoma in mice (Kresl et al., 1999). Cross-reactive epitopes of mCRP have also been detected in the fibrous elements of blood vessels and lymphatic organs suggesting that mCRP may be present in extracellular spaces (Samberg et al., 1988). Since mCRP can self-associate into a matrix-like structure (Motie et al., 1996), the naturally occurring antigen may be self-associated aggregates of mCRP, and thus represent a tissue-based as opposed to a blood based form of CRP. mCRP, but not CRP, binds immune complexes (Khreiss et al., 2004), potentiates the activities of activated leukocytes and platelets (Zouki et al., 2001) and stimulates megakaryocyte differentiation in mice (Potempa et al, 1996).

Additionally, both CRP conformations interact differently with components of the complement cascade. M Mihlan et al., 2009, identified for the first time that mCRP, but not pCRP, has a complement-modulating effect. mCRP recruits the complement inhibitor Factor H to the surface of damaged cells or particles, and enhances local complement inhibition both in the fluid phase and on the cellular surface. Thus, by recruiting C1q to the surface of damaged cells, mCRP triggers complement activation resulting in the formation of C3 convertases and C3b surface deposition. However, by binding inhibitor Factor H and enhancing the inhibitory activity, further complement activation, amplification, cytokine release, C9 deposition and terminal membrane attack assembly are inhibited. Furthermore, the phagocytosis of apoptotic particles is increased. This shows how CRP can contribute to an anti-inflammatory scenario and explains how mCRP contributes to the safe removal of damaged apoptotic particles and necrotic cells which may be relevant for diseases such as atherosclerosis (Zipfel& Skerka, 2009).

Using immunofluorescence microscopy (Eisenhardt et al., 2009) have shown the generation of mCRP from CRP on adherent activated platelets, together with the immunohistological colocalization of mCRP with the CD41 antigen in atherosclerotic plaques. These findings suggest that in atherosclerosis mCRP is generated from circulating CRP, and mCRP is then deposited at the atherosclerotic plaque, exerting strong proinflammatory effects (Agrawal et al., 2010).

Despite the growing interest in mCRP, it remains unclear how mCRP is generated and whether it contributes to inflammatory processes such as atherosclerosis. Thus, it appears that both CRP and altered forms of CRP, including mCRP, may each serve important distinct functions in the acute phase and the host defense response to trauma and infectious agents. Therefore, it is important to ascertain the extent of conversion and reversion of CRP to mCRP and possible intermediate forms to help define and understand the biological function(s) of the CRP molecule.

4.2.2. AAT

AAT is another example of AAP which can be found in vivo in cleaved forms. Cleaved forms of AAT are know to occur when AAT forms an inhibitor complex with serine protease which subsequently dissociates or is degraded, or when it is cleaved by non-target proteases, usually at sites in its reactive loop, without the formation of stable inhibitor complexes. Such cleavage generates a 4 kDa carboxyl-terminal fragment of 36 residues, which remains non-covalently bound to the cleaved AAT. Human cathepsin L, collagenase and stromelysin, and bacterial proteinases from Staphylococcus aureus, Serratia marcescens metalloproteinase and Pseudomonas aeruginosa elastase (Rapala-Kozik et al., 1999) all fall into the latter class and exhibit efficient AAT degrading activity. Recent studies established AAT as a key substrate for gelatinase B (MMP-9) in vivo (Liu et al., 2000). It has long been hypothesized that neutrophil elastase-mediated tissue destruction in certain inflammatory diseases such as emphysema, is caused by an imbalance in the ratio of elastase to AAT (Weiss, 1989). The studies of Liu and collaborators provide in vivo evidence that this mechanism, mediated by the proteolytic inactivation of AAT by gelatinase B, underlies the pathology of the inflammatory skin disorder called bullous pemphigoid which is initiated by deposit formation at the basement membrane (Jordon et al., 1985). Generated cleaved forms of AAT may contribute to the later phase of polymorphonuclear leukocyte infiltration. Indeed, cleaved AAT was shown to form fibrillar structures and to be a potent chemoattractant for monocytes (Janciauskiene et al., 1995, Banda et al., 1988).

Fragments of AAT have been found in human bile, atherosclerotic plaque, urine and plasma, and have been shown to regulate lipid metabolism, inflammatory cell activation and even to inhibit human HIV-1 expression. It has recently been demonstrated that a specific 20-residue fragment of AAT (C-terminal peptide, residues 377–396, referred to as VIRIP) binds to the gp41 fusion peptide of HIV-1 and prevents the virus from entering target cells, thereby inhibiting HIV-1 infection (Münch et al, 2007). These findings suggest that AAT may play a protective role in HIV-1-infected individuals (Forssmann et al., 2010). We found that the C-terminal fragment of AAT, C-36 peptide, corresponding to residues 359-394 suppresses bile acid synthesis in vitro and in vivo. The DNA element involved in the C-36-mediated regulation of 7alpha- and 12alpha-hydroxylase promoters mapped to the alpha1-fetoprotein transcription factor site in both promoters. The C-36 peptide prevented binding of FTF to its target DNA recognition site by direct interaction with FTF (Gerbod-Giannone et al., 2002). Hence, the effects of AAT peptides as potential drugs for systemic lupus erythematosus are being studied (Shapira et al., 2011).

4.3. Oxidized and nitrosylated forms of APPs

Under conditions of compromised oxygen supply, such as occurs in injury, infection or malignancy, oxygen species with free unpaired electrons are generated during mitochondrial electron transport. Referred to as highly reactive oxygen species (ROS), their production causes damage to cell membranes and macromolecules (lipids, proteins and DNA) (Valko et al., 2007). Oxidative changes of protein structure can have a wide range of downstream functional consequences, such as inhibition of enzymatic and binding activities, increased susceptibility to aggregation and proteolysis, increased or decreased uptake by cells, and altered immunogenicity. It is now recognized that oxidation of proteins plays an essential role in the pathogenesis of an important number of degenerative diseases. Compared to controls more oxidized proteins are found in tissues from animals and patients suffering from Alzheimer's disease, rheumatoid arthritis, atherosclerosis or amyotrophic lateral sclerosis (Banfi et al., 2008). For example, in plasma from patients with Alzheimer`s disease the most obviously oxidized proteins were identified as isoforms of AAT and fibrinogen γ-chain precursor proteins. Both these proteins have been suggested to be involved in inflammation processes in Alzheimer's disease (Choi et al., 2002).

S-nitrosylation is another important post-transcriptional modification of the APPs and their peptides, which may be involved in NO-dependent signal transductions. For example, a recent study indicates that S-nitrosylation can be effectively catalyzed by the copper ion of ceruloplasmin, a major multicopper-containing plasma protein, under physiological conditions (Mani et al., 2004). It is now also conceivable that nitrosylation of thiols is involved in modulation of various biological events, such as functional regulation of receptors, ion channels and synaptic vesicle fusion (Miyamoto et al., 2000).

4.3.1. AAT

Oxidized AAT has been found in inflammatory exudates at levels of ~5–10% that of total AAT (Wong &Travis, 1988), and AAT recovered from BAL fluid in smokers is 40% less active compared with non-smokers due to oxidation of the P1 methionine (methionine 358 at the active site) to methionine sulfoxide (Carp et al., 1982). The oxidation of AAT by cigarette smoke or free radicals in vivo has been proposed as a mechanism by which elastin and thus alveolar destruction occurs in COPD (Gadek et al., 1979; Beatty et al., 1984). Oxidation of the P1 methionine (methionine 358) or methionine 351 to methionine sulfoxide significantly reduces the ability of AAT to inhibit neutrophil elastase (Taggart et al., 2000). Hydrogen peroxide in cigarette smoke and N-chloroamines and hypochlorous acid in neutrophils can oxidize and inactivate AAT (Ossanna et al., 1986; Scott et al., 1999). Thus the oxidation of AAT by cigarette smoke or free radicals in vivo could lead to a relative deficiency of elastase inhibitors and has been suggested as a mechanism contributing to the development of emphysema and other diseases such as cystic fibrosis, adult respiratory distress syndrome, and bronchiectasis (McGuire et al., 1982; Roum et al., 1993; Izumi-Yoneda et al., 2009). In addition, oxidative inactivation can enhance the susceptibility of AAT to proteolytic attack, particularly by neutrophil elastase and certain bacterial proteases, including thermolysin, aureolysin, serralysin, pseudolysin, Staphylococcus aureus serine proteinase, streptopain and periodontain. Thus, oxidation and proteolytic processes in some cases may work synergistically. Moreover, oxidized AAT by itself amplifies and perpetuates the inflammatory processes by directly affecting the functional activities of structural and inflammatory cells or by interacting with other molecules such as IgA and low-density lipoproteins. It has been shown that oxidized AAT significantly induces the production of IL-8 and MCP-1 from a lung epithelial cell line (A549 cells) and in a time- and dose-dependent manner and attracts macrophages (Li et al., 2009). Release of oxidants by these inflammatory cells could oxidize newly synthesized AT, which has diffused into the airways and would perpetuate the cycle. This process may be amplified by oxidized AAT induction of MCP-1 synthesis from monocytes (Moraga & Janciauskiene, 2000). These pathways may be one explanation as to why inflammation persists after smoking cessation in chronic obstructive pulmonary disease (Retamales et al., 2001). A complex of oxidized AAT and LDL was isolated from human plasma and was detected in human atherosclerotic lesions of the coronary artery (Donners et al., 2005). The product of AAT nitrosylation, S-NO-AAT, has been shown to have multiple biological functions, including potent anti-microbial activity and inhibition of cysteine protease. In a study by Ikebe and co-workers (Ikebe et al., 2000) it was suggested that S-NO-AAT exerted a potent cytoprotective effect in liver ischemia-reperfusion injury by maintaining the tissue blood flow, inducing hemeoxygenase 1, and suppressing neutrophil-induced liver damage and apoptosis. Interestingly, it was verified that S-NO-AAT expressed similar serine protease inhibitory activity towards pancreatic trypsin and pancreatic and neutrophil elastase as native AAT. Thus, S-NO-AAT may function not only as a simple NO (nitroso) donor but also as a protease inhibitor with a broad inhibitory spectrum.

4.4. Complexed and polymerized forms of APPs

Function of some APPs is dependent on their complex formation with other molecules and/or on their polymerization. For example, CRP binds to phosphocholine, as well as phosphoethanolamine, microbial surface proteins, chromatin and other ligands (Thompson et al., 1999; Agrawal et al., 2002, Okemefuna et al, 2010). CRP activates the classical pathway of complement by binding to C1q, but its binding to CFH in the alternative pathway has turned out to be more controversial. CRP–ligand interactions lead to the recognition of damaged or apoptotic cells and bacterial pathogens. Ca2+ and phosphocholine bind to the B (binding) face of the pentameric ring, whereas the other A (α-helix) face binds to macromolecular ligands such as C1q. The complex between Hp and Hemoglobin has been studied for decades and represents one of the strongest non-covalent interactions reported in plasma (Nielsen & Moestrup, 2009). Hp also binds apolipoprotein A-I (ApoA-I), and impairs its stimulation of lecithin: cholesterol acyltransferase (LCAT) which plays a major role in reverse cholesterol transport (Cigliano et al., 2009). Hp binds and protects ApoE from oxidative damage (Salvatore et al., 2009). Some APPs are regulated by co-factors which are needed to expose or maintain the functional conformation of the APP. The best example of this phenomenon is antithrombin, which is activated by heparin through induced and transmitted conformational changes that stabilise the proteinase-sensitive active site (Jodan et al., 1987). Another APP, PAI-1, which normally exists in a latent form, can be maintained in its functional form in the presence of plasma vitronectin (Wiman et al., 1988). As well as stabilising PAI-1 in the active conformation, vitronectin also alters the specificity of PAI-1, making it an efficient inhibitor of thrombin. The finding that active PAI-1 specifically inhibits integrin attachment to vitronectin (Stefansson & Lawrence, 1996) further illustrates the unique functional interdependence that exists between PAI-1 and vitronectin. Complexes between APPs and other proteins are also found to be associated with specific diseases. For example, in sera from patients with myeloma and Bence-Jones proteinuria, complexes between AAT and the kappa light chain of immunoglobulins were detected (Laurell et al., 1974). In plasma from diabetic subjects, complexes between AAT and factor Xia, and AAT and heat shock protein-70 (HSP70), as well as glycosylated forms of AAT were detected (Austin et al., 1987; Scott et al., 1998; Finotti et al., 2004). Moreover, complexes between immunoglobulin A and AAT have been detected in the sera and synovial fluid of patients with rheumatoid arthritis, systemic lupus erythematosus and ankylosing spondylitis (Scott et al., 1998). Human tissue kallikrein 3, a serine proteinase commonly known as a prostate-specific antigen (PSA) which correlates with prostate hypertrophy and malignancy, is also known to bind to AAT in sera of subjects with high PSA concentrations (Zhang et al., 2000). Localization of AAT-low-density-lipoprotein (LDL) complexes in atherosclerotic lesions and enhanced degradation of AAT-LDL by macrophages suggested the involvement of the complex in atherogenesis (Donners et al., 2005). Alpha1-antichymotrypsin/Alzheimer's peptide Abeta (1-42) complexes and ACT polymers have been associated with Alzheimer's disease (Licastro et al., 1997; Sun et al., 2002).Studies of the functional and conformational polymorphism of inhibitory APPs clearly show that some proteins can undergo polymerization due to an inherited mutation, or chemical modification, and obtain new biological activities or reflect undergoing pathological process. A well-characterised example of a mutant APP associated with a disease state is AAT. The most widely studied deficiency variants of AAT are Z and S, which have E342K and E264V mutations respectively (Carrell et al., 1996, Carrell et al., 1982). Polymerisation of these mutants of AAT is known to be involved in AAT deficiency-related diseases such as emphysema, liver cirrhosis, neonatal hepatitis, hepatocellular carcinoma and lung emphysema (Eriksson, 1990) The liver pathology is characterised by the formation of intracellular inclusions of polymerised AAT. Recent studies now indicate that extra-hepatic AAT polymerization may also occur. For example, AAT polymers have been identified in the lungs and circulation of Z AAT deficiency subjects. Importantly, like other modified forms, AAT polymers lack protease inhibitor activity which will exaggerate the severe deficiency, but also exhibit additional biological functions that may be relevant in pathological processes (Mahadeva et al., 2005, Mulgrew et al., 2004) (Figure 5). The susceptibility of Z AAT individuals who smoke to develop chronic obstructive pulmonary disease is in part related to the combination of the severe anti-elastase deficiency arising from an absolute and functional reduction in neutrophil elastase inhibitory capacity (Stoller & Aboussouan, 2005), and the independent multiple effects of cigarette smoke on inflammatory cells and molecules (Barnes et al., 2003). Our current data clearly demonstrate that cigarette smoke promotes polymerization of Z mutant AAT, but not of the normal, M variant of AAT. Thus cigarette smoke directly accelerates polymerization of Z AAT via oxidation of the protein leading to further depletion of the neutrophil protease protection in the lung and enhanced neutrophil influx (Alam et al., 2010). The data uniquely suggests that rather than the major risk factors for chronic obstructive pulmonary disease namely cigarette smoke and Z AAT deficiency having independent additive effects, they directly interact to create an effect greater than the sum of the individual risks.

5. General conclusions

Inflammation is a complex, highly orchestrated process involving many cell types and molecules, some of which initiate, amplify, or sustain the process, some of which attenuate it, and some of which aid resolution. A number of the participating AAPs are multifunctional and contribute to both the enhancement and the inhibition of inflammation at different points in its evolution. The outcome of the acute inflammatory response is most likely to be determined by the orchestrated generation of a specific profile of APPs, their concentrations and molecular forms in the microenvironment. Diseases associated with chronic inflammation may be due to an inadequate acute-phase response driven by APPs, their concentration and molecular form and/or an inability to eliminate invading pathogens and to rapidly to resolve the inflammatory processes. Often, a single APP is regarded as a marker for inflammation to aid in diagnosis and assesses response to treatement, however we believe one needs to see the profile of several APPs in action to understand function in relation to disease which may help in turn to determine prognosis.


RM is supported by the Cambridge NIHR Biomedical Research centre. SJ is supported by Hannover Medical School, Germany.


1 - A. Agrawal, G. Elhanan, M. Halper, 2010 Dissimilarities in the Logical Modeling of Apparently Similar Concepts in SNOMED CT. AMIA Annu Symp Proc 2010 212 216 .
2 - S. Alam, Z. Li, S. Janciauskiene, R. Mahadeva, 2010 Oxidation of Z {alpha}1 -antitrypsin by Cigarette Smoke Induces Polymerization: A Novel Mechanism of Early-onset Emphysema. Am J Respir Cell Mol Biol Epub ahead of print.
3 - M. Al-Omari, et al. 2011 The acute phase protein, alpha1 -antitrypsin, inhibits neutrophil calpain I and induces random migration. Mol Med Apr 11 [Epub ahead of print].
4 - N. Anderson, et al. 2002 A preliminary evaluation of the differences in the glycosylation of alpha-1-acid glycoprotein between individual liver diseases. Biomed Chromatogr 16 365 372 .
5 - M. Arredouani, et al. 2003 Haptoglobin directly affects T cells and suppresses T helper cell type 2 cytokine release. Immunology 108 144 151 .
6 - M. Assicot, et al. 1993 High serum procalcitonin concentrations in patients with sepsis and infection. Lancet 341 515 518 .
7 - G. E. Austin, R. H. Mullins, L. G. Morin, 1987 Non-enzymic glycation of individual plasma proteins in normoglycemic and hyperglycemic patients. Clin Chem 33 2220 2224 .
8 - S. P. Ballou, G. Lozanski, 1992 Induction of inflammatory cytokine release from cultured human monocytes by C-reactive protein. Cytokine 4 361 368
9 - M. J. Banda, A. G. Rice, G. L. Griffin, R. M. Senior, 1988 Alpha 1-proteinase inhibitor is a neutrophil chemoattractant after proteolytic inactivation by macrophage elastase. J Biol Chem 263 4481 4484 .
10 - C. Banfi, et al. 2008 Oxidized proteins in plasma of patients with heart failure: role in endothelial damage. Eur J Heart Fail 10 244 251 .
11 - P. J. Barnes, 2003 New treatments for chronic obstructive pulmonary disease. Ann Ist Super Sanita 39 573 582 .
12 - P. J. Barter, et al. 2004 Antiinflammatory properties of HDL. Circ Res 95 764 772 .
13 - K. Beatty, N. Matheson, J. Travis, 1984 Kinetic and chemical evidence for the inability of oxidized alpha 1-proteinase inhibitor to protect lung elastin from elastolytic degradation. Hoppe Seylers Z Physiol Chem 365 731 736 .
14 - R. D. Berg, 1996 The indigenous gastrointestinal microflora.Trends Microbiol 4 430 435 .
15 - D.A. Bergin, et al. (2010). α-1 Antitrypsin regulates human neutrophil chemotaxis induced by soluble immune complexes and IL-8. J Clin Invest 120, 4236-4250.
16 - S. Berman, H. Gewurz, C. Mold, 1986 Binding of C-reactive protein to nucleated cells leads to complement activation without cytolysis. J Immunol 136 1354 1359 .
17 - R. Bisoendial, et al. 2005 In vivo effects of C-reactive protein (CRP)-infusion into humans. Circ Res 97, e115 116 .
18 - W. D. Blackburn, 1994 Validity of acute phase proteins as markers of disease activity. J Rheumatol 42 9 13 .
19 - I. Blanco, et al. 2006 Estimated numbers and prevalence of PI*S and PI*Z alleles of alpha1-antitrypsin deficiency in European countries. Eur Respir J 27 77 84 .
20 - A. Boutten, et al. 1992 Alpha 1-acid glycoprotein potentiates lipopolysaccharide-induced secretion of interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha by human monocytes and alveolar and peritoneal macrophages. Eur J Immunol 22 2687 2695 .
21 - K. Brand, et al. 1996 Activated transcription factor nuclear factor-kappa B is present in the atherosclerotic lesion. J Clin Invest 97 1715 1722 .
22 - C. E. Brinckerhoff, et al. 1989 Autocrine induction of collagenase by serum amyloid A-like and beta 2-microglobulin-like proteins. Science 243 655 7 .
23 - N. Bucurenci, et al. 1992 Inhibition of neutrophil superoxide production by human plasma alpha 1-antitrypsin. FEBS Lett 300 21 24 .
24 - H. Carp, et al. 1982 Potential mechanism of emphysema: alpha 1-proteinase inhibitor recovered from lungs of cigarette smokers contains oxidized methionine and has decreased elastase inhibitory capacity. Proc Natl Acad Sci U S A 79 2041 2045 .
25 - R. Carrell, 1986 alpha 1-Antitrypsin: molecular pathology, leukocytes, and tissue damage. J Clin Invest 78 1427 1431 .
26 - R. W. Carrell, D. A. Lomas, 1997 Conformational disease. Lancet 350 134 138 .
27 - R. W. Carrell, et al. 1996 Alpha 1 -antitrypsin deficiency. A conformational disease. Chest 110, 243S-247S.
28 - R. Casey, et al. 2008 The acute-phase reactant C-reactive protein binds to phosphorylcholine-expressing Neisseria meningitidis and increases uptake by human phagocytes. Infect Immun 76 1298 1304 .
29 - J. Cermak, et al. 1993 Cell heme uptake induces ferritin synthesis resulting in altered oxidant sensitivity: possible role in chemotherapy efficacy. Tumor Cancer Res 53 5308 5313 .
30 - K. R. Chapman, R. A. Stockley, C. Dawkins, M. M. Wilkes, R. J. Navickis, 2009 Augmentation therapy for alpha1 antitrypsin deficiency: a meta-analysis. COPD 6 177 184 .
31 - N. Cheng, et al. 2008 Cutting edge: TLR2 is a functional receptor for acute-phase serum amyloid A. J Immunol. 181 22 26 .
32 - J. Choi, et al. 2002 Identification of oxidized plasma proteins in Alzheimer’s disease. Biochem Biophys Res Commun 293 1566 1570 .
33 - M. M. Chowdhury, et al. 2002 Severe panniculitis caused by homozygous ZZ alpha1-antitrypsin deficiency treated successfully with human purified enzyme (Prolastin). Br J Dermatol 147 1258 1261 .
34 - A. Churg, et al. 2001 Alpha-1-antitrypsin and a broad spectrum metalloprotease inhibitor, RS113456, have similar acute anti-inflammatory effects. Lab Inves 81 1119 1131 .
35 - M. C. Cid, et al. 1993 Identification of haptoglobin as an angiogenic factor in sera from patients with systemic vasculitis. J Clin Invest 91 977 985 .
36 - L. Cigliano, et al. 2009 Haptoglobin binds the antiatherogenic protein apolipoprotein E-impairment of apolipoprotein E stimulation of both lecithin:cholesterol acyltransferase activity and cholesterol uptake by hepatocytes. FEBS J 276 6158 6171 .
37 - M. Connolly, et al. 2010 Acute serum amyloid A induces migration, angiogenesis, and inflammation in synovial cells in vitro and in a human rheumatoid arthritis/SCID mouse chimera model . J Immunol 184 6427 6437 .
38 - M. Costello, B. A. Fiedel, H. Gewurz, 1979 Inhibition of platelet aggregation by native and desialised alpha-1 acid glycoprotein. Nature 281 677 678 .
39 - M. J. Costello, H. Gewurz, J. N. Siegel, 1984 Inhibition of neutrophil activation by alpha1-acid glycoprotein. Clin Exp Immunol 55 465 472 .
40 - F. J. Culley, et al. 1996 C-reactive protein binds to a novel ligand on Leishmania donovani and increases uptake into human macrophages. J Immunol 156 4691 4696 .
41 - M. A. Daemen, et al. 2000 Functional protection by acute phase proteins alpha(1)-acid glycoprotein and alpha(1)-antitrypsin against ischemia/reperfusion injury by preventing apoptosis and inflammation. Circulation 102 1420 1426 .
42 - T. W. De Graaf, et al. 1993 Inflammation-induced expression of sialyl Lewis X-containing glycan structures on alpha 1-acid glycoprotein (orosomucoid) in human sera. J Exp Med 177 657 666 .
43 - A. Dehghan, et al. 2007 Risk of type 2 diabetes attributable to C-reactive protein and other risk factors. Diabetes Care 30 2695 2699 .
44 - R. De Martin, et al. 2000 The transcription factor NF-kappa B and the regulation of vascular cell function. Arterioscler Thromb Vasc Biol 20, E83 88 .
45 - S. Devaraj, P. R. Kumaresan, I. Jialal, 2004 Effect of C-reactive protein on chemokine expression in human aortic endothelial cells. J Mol Cell Cardiol 36 405 410 .
46 - C. De Santo, et al. 2010 Invariant NKT cells modulate the suppressive activity of IL-10-secreting neutrophils differentiated with serum amyloid A. Nat Immunol 11 1039 1046 .
47 - F. Díaz-González, et al. 1995 Prevention of in vitro neutrophil-endothelial attachment through shedding of L-selectin by nonsteroidal antiinflammatory drugs. J Clin Invest 95 1756 1765 .
48 - C. A. Dinarello, 1983 Pathogenesis of fever during hemodialysis. Contrib Nephrol 36 90 99 .
49 - M. M. Donners, et al. 2005 Proteomic analysis of differential protein expression in human atherosclerotic plaque progression. J Pathol 206 39 45 .
50 - S. K. Dowd, G. C. Rodgers, J. P. Callen, 1995 Effective treatment with alpha 1-protease inhibitor of chronic cutaneous vasculitis associated with alpha 1-antitrypsin deficiency. J Am Acad Dermatol 33 913 916 .
51 - J. P. Drenth, J. W. van der Meer, I. Kushner, 1996 Unstimulated peripheral blood mononuclear cells from patients with the hyper-IgD syndrome produce cytokines capable of potent induction of C-reactive protein and serum amyloid A in Hep3B cells. J Immunol 157 400 404 .
52 - Clos. T. W. Du, 1989 C-reactive protein reacts with the U1 small nuclear ribonucleoprotein. J Immunol 143 2553 2559 .
53 - Clos. T. W. Du, 2000 Function of C-reactive protein. Ann Med 32 274 278 .
54 - Clos. T. W. Du, L. T. Zlock, R. L. Rubin, 1988 Analysis of the binding of C-reactive protein to histones and chromatin. J Immunol 141 4266 4270 .
55 - T. Dupre, et al. 2001 Congenital disorder of glycosylation Ia with deficient phosphomannomutase activity but normal plasma glycoprotein pattern. Clin Chem 47 132 134 .
56 - J. W. Eaton, et al. 1982 Haptoglobin: a natural bacteriostat. Science 215 691 693 .
57 - E. R. Eckhardt, et al. 2010 Intestinal epithelial serum amyloid A modulates bacterial growth in vitro and pro inflammatory responses in mouse experimental colitis. BMC Gastroenterol 10, 133 EOF EOF .
58 - D. H. Edwards, et al. 1986 Haptoglobin-haemoglobin complex in human plasma inhibits endothelium dependent relaxation: evidence that endothelium derived relaxing factor acts as a local autocoid. Cardiovasc Res 20 549 556 .
59 - S. U. Eisenhardt, J. Habersberger, K. Peter, 2009 Monomeric C-reactive protein generation on activated platelets: the missing link between inflammation and atherothrombotic risk. Trends Cardiovasc Med 19 232 237 .
60 - M. A. Elliott, et al. 1997 Investigation into the concanavalin A reactivity, fucosylation and oligosaccharide microheterogeneity of alpha 1-acid glycoprotein expressed in the sera of patients with rheumatoidarthritis. J Chromatogr B Biomed Sci Appl 688 229 237 .
61 - G. Engström, et al. 2004 Incidence of fatal or repaired abdominal aortic aneurysm in relation to inflammation-sensitive plasma proteins. Arterioscler Thromb Vasc Biol 24 337 341
62 - N. Eriksen, E. P. Benditt, 1980 Isolation and characterization of the amyloid-related apoprotein (SAA) from human high density lipoprotein. Proc Natl Acad Sci U S A 77 6860 6864 .
63 - P. Finotti, A. Pagetta, 2004 A heat shock protein70 fusion protein with alpha1-antitrypsin in plasma of type 1 diabetic subjects. Biochem Biophys Res Commun 315 297 305 .
64 - T. Fournier, N. Medjoubi-N, D. Porquet, 2000 Alpha-1-acid glycoprotein. Biochim Biophys Acta 1482 157 171 .
65 - J. R. Forney, S. Yang, M. C. Healey, 1996 Interaction of the human serine protease inhibitor alpha-1-antitrypsin with Cryptosporidium parvum. J Parasitol 82 496 502 .
66 - N. Fröhlander, O. Ljunggren, U. H. Lerner, 1991 Haptoglobin synergistically potentiates bradykinin and thrombin induced prostaglandin biosynthesis in isolated osteoblasts. Biochem Biophys Res Commun 178 343 351 .
67 - C. Gabay, I. Kushner, 1999 Acute-phase proteins and other systemic responses to inflammation. N Engl J Med 340 448 454 .
68 - J. E. Gadek, G. A. Fells, R. G. Crystal, 1979 Cigarette smoking induces functional antiprotease deficiency in the lower respiratory tract of humans. Science 206 1315 1316 .
69 - M. C. Gerbod-Giannone, et al. 2002 Suppression of cholesterol 7alpha-hydroxylase transcription and bile acid synthesis by an alpha1-antitrypsin peptide via interaction with alpha1-fetoprotein transcription factor. J Biol Chem 277 42973 42980 .
70 - D. Gershov, et al. 2000 C-Reactive protein binds to apoptotic cells, protects the cells from assembly of the terminal complement components, and sustains an antiinflammatory innate immune response: implications for systemic autoimmunity. J Exp Med 192 1353 1364 .
71 - P. G. Gettins, 2002 Serpin structure, mechanism, and function. Chem Rev 102 4751 4804 .
72 - I. Graziadei, et al. 1997 Unidirectional upregulation of the synthesis of the major iron proteins, transferrin-receptor and ferritin, in HepG2 cells by the acute-phase protein alpha1-antitrypsin. J Hepatol 27 716 725 .
73 - J. D. Gitlin, J. I. Gitlin, D. Gitlin, 1977 Localizing of C-reactive protein in synovium of patients with rheumatoid arthritis. Arthritis Rheum 20 1491 1499 .
74 - M. Griese, et al. 2007 alpha1-Antitrypsin inhalation reduces airway inflammation in cystic fibrosis patients. J Eur Respir 29 240 250 .
75 - B. Gooptu, D. A. Lomas, 2009 Conformational pathology of the serpins: themes, variations, and therapeutic strategies. Annu Rev Biochem 78 147 176 .
76 - B. Gross, et al. 2009 New Findings in PiZZ alpha1-antitrypsin deficiency-related panniculitis.Demonstration of skin polymers and high dosing requirements of intravenous augmentation therapy. Dermatology 218 370 375 .
77 - E. Gruys, M.J. Obwolo, M.J. Toussaint, 1994 Diagnostic significance of the major acute phase proteins in veterinary clinical chemistry: a review. Vet Bull 64 1009 1018 .
78 - E. C. Gotschlich, G. M. Edelman, 1967 Binding properties and specificity of C-reactive protein. Proc Natl Acad Sci U S A 57 706 712 .
79 - T. Gutsmann, et al. 2001 Dual role of lipopolysaccharide (LPS)-binding protein in neutralization of LPS and enhancement of LPS-induced activation of mononuclear cells. Infect Immun 69 6942 6950 .
80 - C. E. Hack, et al. 1997 Role for secretory phospholipase A2 and C-reactive protein in the removal of injured cells. Immunol Today 18 111 115 .
81 - D. Hanriot, et al. 2008 C-reactive protein induces pro- and anti-inflammatory effects, including activation of the liver X receptor alpha, on human monocytes. T hromb Haemost. 99 558 569 .
82 - Y. Hattori, M. Matsumura, K. Kasai, 2003 Vascular smooth muscle cell activation by C-reactive protein. Cardiovasc Res 58 186 195 .
83 - E. C. Havenaar, et al. 1998 Severe rheumatoid arthritis prohibits the pregnancy-induced decrease in alpha3-fucosylation of alpha1-acid glycoprotein. Gl ycoconj J 15 723 729 .
84 - F. Haverkate, et al. 1997 Production of C-reactive protein and risk of coronary events in stable and unstable angina. European Concerted Action on Thrombosis and Disabilities Angina Pectoris Study Group. Lancet 349 462 466 .
85 - R. He, H. Sang, R. D. Ye, 2003 Serum amyloid A induces IL-8 secretion through a G protein-coupled receptor, FPRL1/LXA4R. Blood 101 1572 1581 .
86 - R. M. Heuertz, et al. 1999 C-reactive protein inhibits chemotactic peptide-induced 38 mitogen-activated protein kinase activity and human neutrophil movement. J Biol Chem 274, 17968-17974.
87 - T. Hochepied, et al. 2003 Alpha(1)-acid glycoprotein: an acute phase protein with inflammatory and immunomodulating properties. Cytokine Growth Factor Rev 14 25 34 .
88 - P. Hrycaj, et al. 1996 Microheterogeneity of acute-phase glycoproteins in patients with pulmonary sarcoidosis. Eur Respir J 9 313 318
89 - M. Ianni, et al. 2010 Altered glycosylation profile of purified plasma ACT from Alzheimer’s disease. Immun Ageing 7 Suppl, S6.
90 - N. Ikebe, et al. 2000 Protective effect of S-nitrosylated alpha(1)-protease inhibitor on hepatic ischemia-reperfusion injury. J Pharmacol Exp Ther 295 904 911 .
91 - Y. Ingenbleek, L. Bernstein, 1999 The stressful condition as a nutritionally dependent adaptive dichotomy. Nutrition 15 305 320 .
92 - N. Izumi-Yoneda, et al. 2009 Alpha-1 antitrypsin activity is decreased in human amnion in premature rupture of the fetal membranes. Mol Hum Reprod 15 49 57 .
93 - A. Jahangiri, et al. 2009 HDL remodeling during the acute phase response. Arterioscler Thromb Vasc Biol 29 261 267 .
94 - S. Janciauskiene, 2001 Conformational properties of serine proteinase inhibitors (serpins) confer multiple pathophysiological roles. Biochim Biophys Acta 1535 221 235 .
95 - S. Janciauskiene, E. Carlemalm, S. Eriksson, 1995 In vitro fibril formation from alpha1-antitrypsin-derived C-terminal peptides. Biol Chem Hoppe Seyler 376 415 423 .
96 - S. M. Janciauskiene, I. M. Nita, T. Stevens, 2007 Alpha1-antitrypsin, old dog, new tricks. Alpha1-antitrypsin exerts in vitro anti-inflammatory activity in human monocytes by elevating cAMP. J Biol Chem 282 8573 8582 .
97 - S. Janciauskiene, et al. 2008 Alpha1-antitrypsin inhibits the activity of the matriptase catalytic domain in vitro. Am J Respir Cell Mol Biol 39 631 637 .
98 - S. M. Janciauskiene, et al. 2011 The discovery of α1 -antitrypsin and its role in health and disease. Respir Med. [Epub ahead of print].
99 - J. Javid, 1978 Human haptoglobins. Curr Top Hematol 1 151 192 .
100 - Z. Jie, et al. 2003 Protective effects of alpha 1-antitrypsin on acute lung injury in rabbits induced by endotoxin. Chin Med J (Engl) 116 1678 1682 .
101 - S. A. Jones, et al. 1999 C-reactive protein: a physiological activator of interleukin 6 receptor shedding. J Exp Med 189 599 604 .
102 - R. E. Jordon, S. Kawana, K. A. Fritz, 1985 Immunopathologic mechanisms in pemphigus and bullous pemphigoid. J Invest Dermatol 85, 72s 78s .
103 - M. Kalis, et al. 2010 α 1-antitrypsin enhances insulin secretion and prevents cytokine-mediated apoptosis in pancreatic β-cells. Islets 2 185 189 .
104 - K. Kakehi, M. Kinoshita, M. Nakano, 2002 Analysis of glycoproteins and the oligosaccharides thereof by high-performance capillary electrophoresis-significance in regulatory studies on biopharmaceutical products. Biomed Chromatogr 16 103 115 .
105 - M. Kaźmierczak, et al. 1995 Changes of acute phase proteins glycosylation profile as a possible prognostic marker in myocardial infarction. Int J Cardiol 49 201 207 .
106 - R. R. Kew, T. M. Hyers, R. O. Webster, 1990 Human C-reactive protein inhibits neutrophil chemotaxis in vitro: possible implications for the adult respiratory distress syndrome. J Lab Clin Med 115 339 345 .
107 - T. Khreiss, et al. 2004 Opposing effects of C-reactive protein isoforms on shear-induced neutrophil-platelet adhesion and neutrophil aggregation in whole blood. Circulation 110 2713 2720 .
108 - T. Khreiss, et al. 2005 Loss of pentameric symmetry inC-reactive protein induces interleukin-8 secretion through peroxynitrite signaling in human neutrophils. Circ Res 97 690 697 .
109 - S. Knappstein, et al. 2004 Alpha 1-antitrypsin binds to and interferes with functionality of EspB from atypical and typical enteropathogenic Escherichia coli strains. Infect Immun 72 4344 4350 .
110 - W. Koenig, et al. 1999 C-Reactive protein, a sensitive marker of inflammation, predicts future risk of coronary heart disease in initially healthy middle-aged men: results from the MONICA (Monitoring Trends and Determinants in Cardiovascular Disease) Augsburg Cohort Study, 1984 to 1992. Circulation 99 237 242 .
111 - W. Koenig, et al. 2006 Increased concentrations of C-reactive protein and IL-6 but not IL-18 are independently associated with incident coronary events in middle-aged men and women: results from the MONICA/KORA Augsburg case-cohort study, 1984-2002. Arterioscler Thromb Vasc Biol 26 2745 2751 .
112 - M. Koulmanda, et al. 2008 Curative and beta cell regenerative effects of alpha1-antitrypsin treatment in autoimmune diabetic NOD mice. Proc Natl Acad Sci U S A 105 16242 16247 .
113 - A. Koj, 1985 Cytokines regulating acute inflammation and synthesis of acute phase proteins. Blut 51 267 274 .
114 - J. J. Kresl, L. A. Potempa, B. Anderson, J. A. Radosevich, 1999 Inhibition of mouse mammary adenocarcinoma (EMT6) growth and metastases in mice by a modified form of C-reactive protein. Tumour Biol 20 72 87 .
115 - F. Kueppers, 2011 The role of augmentation therapy in alpha-1 antitrypsin deficiency. Curr Med Res Opin 27 579 588 .
116 - A. Kurosky, et al. 1980 Covalent structure of human haptoglobin: a serine protease homolog. Proc Natl Acad Sci U S A 77 3388 3392 .
117 - I. Kushner, 1982 The phenomenon of the acute phase response. Ann N Y Acad Sci 389 39 48 .
118 - I. Kushner, G. Feldmann, 1978 Control of the acute phase response. Demonstration of C-reactive protein synthesis and secretion by hepatocytes during acute inflammation in the rabbit. J Exp Med 148 466 77 .
119 - I. Kushner, H. Gewurz, M. D. Benson, 1981 C-reactive protein and the acute-phase response. J Lab Clin Med 97 739 749 .
120 - I. Kushner, A. Mackiewicz, 1993 The acute-phase response: an overview. In: Acute Phase Proteins Molecular Biology, Biochemistry and Clinical Applications 3 19 . CRC Press, Boca Raton, FL.
121 - A. Laine, et al. 1990 Comparison of the effects of purified human alpha 1-antichymotrypsin and alpha 1-proteinase inhibitor on NK cytotoxicity: only alpha 1-proteinase inhibitor inhibits natural killing. Clin Chim Acta 190 163 173 .
122 - C. B. Laurell, E. Thulin, 1974 Complexes in plasma between light chain kappa immunoglobulins and alpha 1-antitrypsin respectively prealbumin. Immunochemistry 11 703 709 .
123 - U. H. Lerner, N. Fröhlander, 1992 Haptoglobin-stimulated bone resorption in neonatal mouse calvarial bones in vitro. Arthritis Rheum 35 587 591 .
124 - E. C. Lewis, et al. 2008 Alpha1-Antitrypsin monotherapy induces immune tolerance during islet allograft transplantation in mice. Proc Natl Acad Sci U S A 105 16236 16241 .
125 - Y. J. Liang, et al. 2006 C-reactive protein activates the nuclear factor-kappaB pathway and induces vascular cell adhesion molecule-1 expression through CD32 in human umbilical vein endothelial cells and aortic endothelial cells. J Mol Cell Cardiol 40 412 420 .
126 - P. Libby, 2002 Inflammation in atherosclerosis. Nature 420 868 874 .
127 - C. Libert, P. Brouckaert, W. Fiers, 1994 Protection by alpha 1-acid glycoprotein against tumor necrosis factor-induced lethality. J Exp Med 180 1571 1575 .
128 - C. Libert, et al. 1996 alpha1-Antitrypsin inhibits the lethal response to TNF in mice. J Immunol 157 5126 5129 .
129 - Z. Li, et al. 2009 Oxidized{alpha}1 -antitrypsin stimulates the release of monocyte chemotactic protein-1 from lung epithelial cells: potential role in emphysema. Am J Physiol Lung Cell Mol Physiol 297, L388-400.
130 - F. Licastro, et al. 1997 Monomeric and polymeric forms of alpha-1 antichymotrypsin in sera from patients with probable late onset Alzheimer’s disease . Dement Geriatr Cogn Disord 8 337 342 .
131 - J. Lieberman, 2000 Augmentation therapy reduces frequency of lung infections in antitrypsin deficiency: a new hypothesis with supporting data. Chest 118 1480 1485 .
132 - P. Lind, et al. 2004 Risk of myocardial infarction and stroke in smokers is related to plasma levels of inflammation-sensitive proteins. Arterioscler Thromb Vasc Biol 24 577 582 .
133 - H. M. Liu, K. Takagaki, K. Schmid, 1988 In vitro nerve-growth-promoting activity of human plasma alpha 1-acid glycoprotein. J Neurosci Res 20 64 72 .
134 - Z. Liu, et al. 2000 The serpin alpha1-proteinase inhibitor is a critical substrate for gelatinase B/MMP-9 in vivo. Cell 102 647 655 .
135 - C. Liu, et al. 2005 Proapoptotic, antimigratory, antiproliferative, and antiangiogenic effects of commercial C-reactive protein on various human endothelial cell types in vitro: implications of contaminating presence of sodium azide in commercial preparation. Circ Res 97 135 143 .
136 - X. L. Y. Lu, et al. 2009 Decay-Accelerating Factor Attenuates C-Reactive Protein-Potentiated Tissue Injury After Mesenteric Ischemia/Reperfusion. J Surg Res [Epub ahead of print].
137 - L. Y. Luo, et al. 2006 Characterization of human kallikreins 6 and 10 in ascites fluid from ovarian cancer patients. Tumour Biol 27 227 234 .
138 - E. Lysenko, et al. 2000 The position of phosphorylcholine on the lipopolysaccharide of Haemophilus influenzae affects binding and sensitivity to C-reactive protein-mediated killing. Mol Microbiol 35 234 245 .
139 - L. Lögdberg, L. Wester, 2000 Immunocalins: a lipocalin subfamily that modulates immune and inflammatory responses. Biochim Biophys Acta 1482 284 297 .
140 - A. Mackiewicz, et al. 1987 Monokines regulate glycosylation of acute-phase proteins. J Exp Med 166 253 258 .
141 - O. C. Maes, et al. 2006 Characterization of alpha1-antitrypsin as a heme oxygenase-1 suppressor in Alzheimer plasma. Neurobiol Dis 24 89 100 .
142 - R. Mahadeva, et al. 2005 Polymers of Z alpha1-antitrypsin co-localize with neutrophils in emphysematous alveoli and are chemotactic in vivo. Am J Pathol 166 377 386
143 - E. Malle, F. C. De Beer, 1996 Human serum amyloid A (SAA) protein: a prominent acute-phase reactant for clinical practice. Eur J Clin Invest 26 427 435 .
144 - K. Mani, et al. 2004 Involvement of glycosylphosphatidylinositol-linked ceruloplasmin in the copper/zinc-nitric oxide-dependent degradation of glypican-1 heparan sulfate in rat C6 glioma cells. J Biol Chem 279 12918 12923
145 - T. Marumo, et al. 1997 Platelet-derived growthfactor-stimulated superoxide anion production modulates activation of transcription factor NF-kappaB and expression of monocyte chemoattractant protein1 in human aortic smooth muscle cells. Circulation 96 2361 2367 .
146 - W. W. Mc Guire, et al. 1982 Studies on the pathogenesis of the adult respiratory distress syndrome . J Clin Invest 69 543 553 .
147 - K. Mills, et al. 2001 Identification of alpha(1)-antitrypsin variants in plasma with the use of proteomic technology. Clin Chem 47 2012 22 .
148 - Y. Miyamoto, T. Akaike, H. Maeda, 2000 S-nitrosylated human alpha(1)-protease inhibitor. Biochim Biophys Acta 1477 90 97 .
149 - C. Mold, H. Gewurz, Clos. T. W. Du, 1999 Regulation of complement activation by C-reactive protein. Immunopharmacology 42 23 30 .
150 - C. Mold, M. Kingzette, H. Gewurz, 1984 C-reactive protein inhibits pneumococcal activation of the alternative pathway by increasing the interaction between factor H and C3b. J Immunol 133 882 885 .
151 - C. Mold, et al. 1981 C-reactive protein is protective against Streptococcus pneumoniae infection in mice. J Exp Med 54 1703 8 .
152 - C. Mold, et al. 2002 C-reactive protein mediates protection from lipopolysaccharide through interactions with Fc gamma R. J Immunol Today 169 7019 7025 .
153 - D. F. Moore, et al. 1997 Alpha-1-acid (AAG,orosomucoid) glycoprotein: interaction with bacterial lipopolysaccharide and protection from sepsis. Inflammation 21 69 82 .
154 - F. Moraga, S. Janciauskiene, 2000 Activation of primary human monocytes by the oxidized form of alpha1-antitrypsin. J Biol Chem 275 7693 7700 .
155 - H. J. Moshage, et al. 1987 Study of the molecular mechanism of decreased liver synthesis of albumin in inflammation. J Clin Invest 79 1635 1641 .
156 - M. Motie, K. W. Schaul, L. A. Potempa, 1998 Biodistribution and clearance of 125I-labeled C-reactive protein and 125I-labeled modified C-reactive protein in CD-1 mice. Drug Metab Dispos 26 977 981 .
157 - E. M. Muchitsch, W. Auer, L. Pichler, 1998 Effects of alpha 1-acid glycoprotein in different rodent models of shock. Fundam Clin Pharmacol. 12 173 181 .
158 - A. T. Mulgrew, et al. 2004 Z alpha1-antitrypsin polymers in the lung and acts as a neutrophil chemoattractant. Chest, 125 1952 1957 .
159 - M. J. Nielsen, S. K. Moestrup, 2009 Receptor targeting of hemoglobin mediated by the haptoglobins: roles beyond heme scavenging. Blood 114 764 771 .
160 - S. K. Oh, N. Pavlotsky, A. I. Tauber, 1990 Specific binding of haptoglobin to human neutrophils and its functional consequences. J Leukoc Biol 47 142 148 .
161 - E. B. Oliveira, C. Gotschlich, T. Y. Liu, 1979 Primary structure of human C-reactive protein. J Biol Chem 254 489 502 .
162 - A. I. Okemefuna, et al. 2010 C-reactive protein exists in an NaCl concentration-dependent pentamer-decamer equilibrium in physiological buffer. J Biol Chem 285 1041 1052 .
163 - P. J. Ossanna, et al. 1986 Oxidative regulation of neutrophil elastase-alpha-1-proteinase inhibitor interactions. J Clin Invest 77 1939 1951 .
164 - M. Pagano, M. A. Nicola, R. Engler, 1982 Inhibition of cathepsin L and B by haptoglobin, the haptoglobin-hemoglobin complex, and asialohaptoglobin. "In vitro" studies in the rat. Can J Biochem 60 631 637 .
165 - V. Pasceri, et al. 2001 Modulation of C-reactive protein-mediated monocyte chemoattractant protein-1 induction in human endothelial cells by anti-atherosclerosis drugs. Circulation 103 2531 2534 .
166 - A. D. Pradhan, et al. 2001 C-reactive protein, interleukin 6, and risk of developing type 2 diabetes mellitus. JAMA 286 327 334 .
167 - V. Pasceri, J. T. Willerson, E. T. Yeh, 2000 Direct proinflammatory effect of C-reactive protein on human endothelial cells. Circulation 102 2165 2168 .
168 - M. B. Pepys, et al. 1994 Binding of pentraxins to different nuclear structures: C-reactive protein binds to small nuclear ribonucleoprotein particles, serum amyloid P component binds to chromatin and nucleoli. Clin Exp Immunol 97 152 157 .
169 - I. Petrache, et al. 2006 alpha-1 antitrypsin inhibits caspase-3 activity, preventing lung endothelial cell apoptosis. Am J Pathol 169 1155 1166 .
170 - L. Pichler, E. M. Muchitsch, H. P. Schwarz, 1999 [Preclinical investigation of alpha 1-acid glycoprotein (orosomucoid)]. Wien Klin Wochenschr 111 192 198 .
171 - D. C. Poland, et al. 2001 Increased alpha3-fucosylation of alpha1-acid glycoprotein in Type I diabetic patients is related to vascular function. Glycoconj J 18 261 268 .
172 - L. A. Potempa, et al. 1983 Antigenic,electrophoretic and binding alterations of human C-reactive protein modified selectively in the absence of calcium. Mol Immunol 20 1165 1175 .
173 - L. A. Potempa, et al. 1996 Stimulation of megakaryocytopoiesis in mice by human modified C-reactive protein (mCRP). Exp Hematol 24 258 264 .
174 - L. A. Potempa, et al. 1987 Expression, detection and assay of a neoantigen (Neo-CRP) associated with a free, human C-reactive protein subunit. Mol Immunol 24 531 541 .
175 - A. V. Potthoff, et al. 2007 HIV infection in a patient with alpha-1 antitrypsin deficiency: a detrimental combination? AIDS 21 2115 2116 .
176 - M. Rapala-Kozik, et al. 1999 Comparative cleavage sites within the reactive-site loop of native and oxidized alpha1-proteinase inhibitor by selected bacterial proteinases. Biol Chem 380 1211 1216 .
177 - I. Retamales, et al. 2001 Amplification of inflammation in emphysema and its association with latent adenoviral infection. Am J Respir Crit Care Med 164 469 473 .
178 - P. M. Ridker, et al. 1997 Alu-repeat polymorphism in the gene coding for tissue-type plasminogen activator (t-PA) and risks of myocardial infarction among middle-aged men. Arterioscler Thromb Vasc Biol 17 1687 1690 .
179 - M. Rinaldi, et al. 2008 Differential effects of alpha1-acid glycoprotein on bovine neutrophil respiratory burst activity and IL-8 production. Vet Immunol Immunopathol 126 199 210 .
180 - W. Rodriguez, et al. 2005 Reversal of ongoing proteinuria in autoimmune mice by treatment with C-reactive protein. Arthritis Rheum 52 642 650 .
181 - W. Rodriguez, et al. 2007 C-reactive protein-mediated suppression of nephrotoxic nephritis: role of macrophages, complement, and Fcgamma receptors. J Immunol 178 530 538 .
182 - J. Rossbacher, L. Wagner, M. S. Pasternack, 1999 Inhibitory effect of haptoglobin on granulocyte chemotaxis, phagocytosis and bactericidal activity. Scand J Immunol 50 399 404 .
183 - J. H. Roum, et al. 1993 Systemic deficiency of glutathione in cystic fibrosis. J Appl Physiol 75 2419 2424 .
184 - I. Rydén, et al. 1997 Glycosylation of alpha1-acid glycoprotein in inflammatory disease: analysis by high-pH anion-exchange chromatography and concanavalin A crossed affinity immunoelectrophoresis. Glycoconj J 14 481 488 .
185 - S. M. Sadrzadeh, J. Bozorgmeh, 2004 Haptoglobin phenotypes in health and disorders. Am J Clin Pathol 121 Suppl.
186 - A. Salvatore, et al. 2009 Haptoglobin binds apolipoprotein E and influences cholesterol esterification in the cerebrospinal fluid.J Neurochem. 110 255 263 .
187 - R. Saldova, et al. 2008 Glycosylation changes on serum glycoproteins in ovarian cancer may contribute to disease pathogenesis. Dis Markers 25 219 232 .
188 - N. L. Samberg, et al. 1988 Preferential expression of neo-CRP epitopes on the surface of human peripheral blood lymphocytes. Cell Immunol 116 86 98 .
189 - A. Sarrats, et al. 2010 Glycosylation of liver acute-phase proteins in pancreatic cancer and chronic pancreatitis. Proteomics Clin Appl 4 432 448 .
190 - L. J. Scott, et al. 1998 Comparison of IgA-alpha1-antitrypsin levels in rheumatoid arthritis and seronegative oligoarthritis: complex formation is not associated with inflammation per se. Br J Rheumatol 37 398 404 .
191 - K. Sei, et al. 2002 Collection of alpha1-acid glycoprotein molecular species by capillary electrophoresis and the analysis of their molecular masses and carbohydrate chains. Basic studies on the analysis of glycoprotein glycoforms. J Chromatogr A 958 273 281 .
192 - C. Shah, R. Hari-Dass, J. G. Raynes, 2006 Serum amyloid A is an innate immune opsonin for Gram-negative bacteria. Blood 108 1751 1757 .
193 - I. Shapira, et al. 2011 Novel peptides as potential treatment of systemic lupus erythematosus. Lupus [Epub ahead of print].
194 - M. Schapira, et al. 1982 Purified human plasma kallikrein aggregates human blood neutrophils. J Clin Invest 69 1199 1202 .
195 - Q. B. She, et al. 2000 alpha(1)-antitrypsin can increase insulin-induced mitogenesis in various fibroblast and epithelial cell lines. FEBS Lett 473 33 36 .
196 - S. B. Schwedler, et al. 2006 C-reactive protein: a family of proteins to regulate cardiovascular function. Am J Kidney Dis 47 212 222 .
197 - V. K. Singh, H. H. Fudenberg, 1986 Lymphocyte stimulation in vitro by orosomucoid glycoprotein. Immunol Lett 14 9 13 .
198 - S. Snyder, E. L. Coodley, 1976 Inhibition of platelet aggregation by alpha1-acid glycoprotein. Arch Intern Med 136 778 781 .
199 - S. Stefansson, D. A. Lawrence, 1996 The serpin PAI-1 inhibits cell migration by blocking integrin alpha V beta 3 binding to vitronectin. Nature 383 441 443 .
200 - A. Steinmetz, et al. 1989 Influence of serum amyloid A on cholesterol esterification in human plasma. Biochim Biophys Acta 1006 173 178 .
201 - H. Stibler, U. Holzbach, B. Kristiansson, 1998 Isoforms and levels of transferrin, antithrombin, alpha(1)-antitrypsin and thyroxine-binding globulin in 48 patients with carbohydrate-deficient glycoprotein syndrome type I. Scand J Clin Lab Invest 58 55 61 .
202 - J. K. Stoller, et al. 2007 Primary care diagnosis of alpha-1 antitrypsin deficiency: issues and opportunities. Cleve Clin J Med 74 869 874 .
203 - J. A. Stonik, et al. 2004 Serum amyloid A promotes ABCA1-dependent and ABCA1-independent lipid efflux from cells. Biochem Biophys Res Commun 32 936 941 .
204 - S. J. Su, et al. 1999 Alpha 1-acid glycoprotein-induced tumor necrosis factor-alpha secretion of human monocytes is enhanced by serum binding proteins and depends on protein tyrosine kinase activation. Immunopharmacology. 41 21 29 .
205 - S. J. Su, T. M. Yeh, 1996 Effects of alpha 1-acid glycoprotein on tissue factor expression and tumor necrosis factor secretion in human monocytes. Immunopharmacology 34 139 145 .
206 - Y. X. Sun, H. T. Wright, S. Janciauskiene, 2002 Alpha1-antichymotrypsin/Alzheimer’s peptide Abeta(1-42) complex perturbs lipid metabolism and activates transcription factors PPARgamma and NFkappaB in human neuroblastoma (Kelly) cells. J Neurosci Respir Med 67 511 522 .
207 - D. Subramaniyam, et al. 2010 Cholesterol rich lipid raft microdomains are gateway for acute phase protein, SERPINA1 . Int J Biochem Cell Biol 42 1562 1570 .
208 - D. Subramaniyam, et al. (2008). TNF-alpha-induced self expression in human lung endothelial cells is inhibited by native and oxidized alpha1-antitrypsin. Int J Biochem Cell Biol 40, 258-271.
209 - D. Subramaniyam, et al. 2010 Effects of alpha 1-antitrypsin on endotoxin-induced lung inflammation in vivo . Inflamm Res 59 571 578 .
210 - C. P. Sullivan, et al. 2010 Secretory phospholipase A2, group IIA is a novel serum amyloid A target gene: activation of smooth muscle cell expression by an interleukin-1 receptor-independent mechanism. J Biol Chem 285 565 575 .
211 - A. J. Szalai, D. E. Briles, J. E. Volanakis, 1995 Human C-reactive protein is protective against fatal Streptococcus pneumoniae infection in transgenic mice. J Immunol 155 2557 2563 .
212 - A. J. Szalai, et al. 2002 Experimental allergic encephalomyelitis is inhibited in transgenic mice expressing human C-reactive protein. J Immunol 168 5792 5797 .
213 - A. J. Szalai, et al. 2000 Human C-reactive protein is protective against fatal Salmonella enterica serovar typhimurium infection in transgenic mice. Infect Immun 68 5652 5656 .
214 - J. Sörensson, et al. 1999 Human endothelial cells produce orosomucoid, an important component of the capillary barrier. Am J Physiol 276, H530 534 .
215 - S. P. Tam, R. Kisilevsky, J. B. Ancsin, 2008 Acute-phase-HDL remodeling by heparan sulfate generates a novel lipoprotein with exceptional cholesterol efflux activity from macrophages. PLoS One 3, e3867 .
216 - C. Taggart, et al. 2000 Oxidation of either methionine 351 or methionine 358 in alpha 1-antitrypsin causes loss of anti-neutrophil elastase activity. J Biol Chem 275 27258 27265 .
217 - K. E. Taylor, J. C. Giddings, Berg. C. W. van den, 2005 C-reactive protein-induced in vitro endothelial cell activation is an artefact caused by azide and lipopolysaccharide. Arterioscler Thromb Vasc Biol 25 1225 1230 .
218 - D. Thompson, M. B. Pepys, S. P. Wood, 1999 The physiological structure of human C-reactive protein and its complex with phosphocholine. Structure 7 169 177 .
219 - D. Thomas-Rudolph, et al. 2007 C-reactive protein enhances immunity to Streptococcus pneumoniae by targeting uptake to Fc gamma R on dendritic cells. J Immunol 178 7283 7291 .
220 - B. L. Thurberg, T. Collins, 1998 The nuclear factor-kappa B/inhibitor of kappa B autoregulatory system and atherosclerosis. Curr Opin Lipidol 9 387 396 .
221 - H. Tilg, et al. 1993 Antiinflammatory properties of hepatic acute phase proteins: preferential induction of interleukin 1 (IL-1) receptor antagonist over IL-1 beta synthesis by human peripheral blood mononuclear cells. J Exp Med 178 1629 1636 .
222 - C. F. Tseng, et al. 2004 Antioxidant role of human haptoglobin. Proteomics 4 2221 2228 .
223 - I. C. Tseng, et al. 2008 Purification from human milk of matriptase complexes with secreted serpins: mechanism for inhibition of matriptase other than HAI-1. Am J Physiol Cell Physiol 295, C423 -C431.
224 - M. Valko, et al. 2007 Free radicals and antioxidants in normal physiological functions and human disease. Int J Biochem Cell Biol. 39 44 84 .
225 - W. Van Molle, et al. 1999 Activation of caspases in lethal experimental hepatitis and prevention by acute phase proteins. J Immunol 163 5235 5241 .
226 - J. van Pelt, et al. 1996 Carbohydrate-deficient transferrin values in neonatal and umbilical cord blood. J Inherit Metab Dis 19 253 266 .
227 - S. Verma, et al. 2002 Endothelin antagonism and interleukin-6 inhibition attenuate the proatherogenic effects of C-reactive protein. Circulation 105 1890 1896 .
228 - J. E. Volanakis, K. W. Wirtz, 1979 Interaction of C-reactive protein with artificial phosphatidylcholine bilayers. Nature 281 155 157 .
229 - B. Walcheck, et al. 1996 Neutrophil-neutrophil interactions under hydrodynamic shear stress involve L-selectin and PSGL-1. A mechanism that amplifies initial leukocyte accumulation of P-selectin in vitro. J Clin Invest 98 1081 1087 .
230 - M. Wang, et al. 2009 Novel fucosylated biomarkers for the early detection of hepatocellular carcinoma. Cancer Epidemiol Biomarkers Prev 18 1914 1921 .
231 - J. N. Weiser, et al. 1998 Phosphorylcholine on the lipopolysaccharide of Haemophilus influenzae contributes to persistence in the respiratory tract and sensitivity to serum killing mediated by C-reactive protein. J Exp Med 187 631 640 .
232 - S. J. Weiss, 1989 Tissue destruction by neutrophils N Engl J Med 320 365 376 .
233 - R. L. Whisler, Y. G. Newhouse, R. F. Mortensen, 1986 C-reactive protein reduces the promotion of human B-cell colony formation by autoreactive T4 cells and T-cell proliferation during the autologous mixed-lymphocyte reaction. Cell Immunol 102 287 298 .
234 - B. Wiman, et al. 1988 Plasminogen activator inhibitor 1 (PAI) is bound to vitronectin in plasma. FEBS Lett 242 125 128 .
235 - J. P. Williams, et al. 1997 Alpha1 -Acid glycoprotein reduces local and remote injuries after intestinal ischemia in the rat. Am J Physiol 273, G1031-10335.
236 - K. J. Woollard, D. C. Phillips, H. R. Griffiths, 2002 Direct modulatory effect of C-reactive protein on primary human monocyte adhesion to human endothelial cells. Clin Exp Immunol Today 130 256 262 .
237 - P. S. Wong, J. Travis, 1980 Isolation and properties of oxidized alpha-1-proteinase inhibitor from human rheumatoid synovial fluid. Biochem Biophys Res Commun 96 1449 1454 .
238 - D. Xia, D. Samols, 1997 Transgenic mice expressing rabbit C-reactive protein are resistant to endotoxemia. Proc Natl Acad Sci U S A 94 2575 2580 .
239 - L. Xie, et al. 2005 C-reactive protein augments interleukin-8 secretion in human peripheral blood monocytes. J Cardiovasc Pharmacol 46 690 696 .
240 - F. Yang, et al. 1995 Cell type-specific and inflammatory-induced expression of haptoglobin gene in lung. Lab Invest. 73 433 440 .
241 - Z. Yang, W. S. Hancock, 2005 Monitoring glycosylation pattern changes of glycoproteins using multi-lectin affinity chromatography. J Chromatogr A 1070 57 64 .
242 - J. M. Zeller, B. L. Sullivan, 1992 C-reactive protein selectively enhances the intracellular generation of reactive oxygen products by IgG-stimulated monocytes and neutrophils. J Leukoc Biol 52 449 455 .
243 - W. M. Zhang, et al. 2000 Characterization and determination of the complex between prostate-specific antigen and alpha 1-protease inhibitor in benign and malignant prostatic diseases. Scand J Clin Lab Invest Suppl 233 51 58 .
244 - W. Zhong, et al. 1998 Effect of human C-reactive protein on chemokine and chemotactic factor-induced neutrophil chemotaxis and signaling. J Immunol 161 2533 2540 .
245 - P. F. Zipfel, C. Skerka, 2009 Complement regulators and inhibitory proteins. Nat Rev Immunol 9 729 740 .
246 - C. Zouki, et al. 1997 Prevention of In vitro neutrophil adhesion to endothelial cells through shedding of L-selectin by C-reactive protein and peptides derived from C-reactive protein. J Clin Invest 100 522 529 .
247 - C. Zouki, et al. 2001 Loss of pentameric symmetry of C-reactive protein is associated with promotion of neutrophil-endothelial cell adhesion. J Immunol 167 5355 5361 .