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Protease-activated receptor-2 (PAR-2) mediates calcitonin gene-related peptide (CGRP) release and collectively plays a crucial role in inflammation-induced visceral hyperalgesia (VH). The present review chapter outlines the substantial advances that elucidated the underlying role of PAR-2 and CGRP in gut inflammation-induced VH and highlights their relevancies in the management of VH. PAR-2 is expressed in a wide range of gastrointestinal cells and its activation on primary afferent nerves by tryptase, trypsin or cathepsin-S is the key mechanism of sensitization during intestinal inflammation. The activated PAR-2 sensitizes transient receptor potential vanilloid subtype-1 receptors and triggers the release of substance-P (SP) and CGRP that are involved both in the transmission and modulation of VH. Approximately, two-thirds of sensory neurons express PAR-2 and 40% of the PAR-2-expressing sensory neurons also express SP and CGRP. Accumulating set of experiments devised that the blockade or antagonism of PAR-2 in inflammatory diseases of the gut depicts double advantages of reducing inflammation and VH. Simultaneously, the uses of CGRP-antagonists inhibit VH and completely suppress PAR-2-agonists-induced intestinal inflammation in animals. However, further study is imperative to improve our understanding of the blockade or antagonism of PAR-2 and CGRP release before its implication as a novel therapeutic for the clinical management of VH in human patients.
Department of Surgery and Pharmacology, Agriculture and Forestry University, Rampur, Nepal
*Address all correspondence to: mkshah@afu.edu.np
1. Introduction
Visceral hyperalgesia (VH) is a pathological state of inflammatory bowel diseases (IBDs) and irritable bowel syndrome (IBS) or other functional bowel disorders, in which sensory threshold for abdominal pain and discomfort decreases due to tissue injury, inflammation, and persistent exposure of tissues/organ to noxious stimuli. In this state, the continuous release of inflammatory mediators results in sensitization of primary afferents and abdominal pain, both during the acute flare of diseases and their remission [1, 2]. Despite several proposed factors including inflammation, psychology and aberrant sensory-motor function of the gut contribute to peripheral and central sensitization [3], the exact underlying mechanism of VH has not been fully elucidated. The cell-membrane protease-activated receptor-2 (PAR-2) mediates calcitonin gene-related peptide (CGRP) release, and their associated roles in neurogenic inflammation-induced sensitization could be of great interest for the researchers to address this persistent nature of VH.
A G-protein coupled receptor PAR-2, distributed throughout the gastrointestinal (GI) tract, is activated particularly by proteases such as tryptase, trypsin, and cathepsin-S [4, 5, 6]. PAR-2 activation on several cells (epithelial cells, endothelial cells, neutrophils, macrophages, monocytes, mast cells, fibroblasts, neurons, dendritic cells, lymphocytes, etc.) could lead to the release of cytokines, chemokines, prostaglandins [7], as well as CGRP and substance-P (SP) in the enteric neurons and afferent neurons [8, 9]. Numerous reports indicated the diverse SP and CGRP expressions within the dorsal root ganglia (DRG) and spinal neurons during colitis and ileitis [10, 11, 12, 13, 14, 15]. The expressions of SP and CGRP within the gut not only excite extrinsic afferents but also perpetuate the central transmission of nociceptive traffic between afferent neurons and higher-order neurons in the spinal cord and brainstem [16]. Thus, it is worthwhile to consider the key role of PAR-2 in the release of CGRP, which subsequently triggers neurogenic inflammation mediated VH.
Currently, the pharmacotherapy for VH is unsatisfactory because of its unknown precise mechanism. Earlier study suggests that the blockade of PAR-2at the periphery and/or the inhibition of luminal protease activity may be of interest for treating the VH [17]. Likewise, the administration of CGRP antagonists inhibits VH in animals [18, 19]. Therefore, the blockade or antagonism of either PAR-2 or CGRP may be a promising therapeutic target for VH. This review chapter explores the important roles of PAR-2 and PAR-2-mediated CGRP during inflammatory gut and their antagonism or blockade for the treatment of VH.
PAR-2 is activated through proteolytic cleavage by specific serine proteases, such as trypsin and mast cell (MC)-tryptase [4] and lysosomal macrophagic cysteine protease cathepsin-S [5, 6]. PAR-2 is generally expressed in the basolateral and apical side of epithelial cells [20], fibroblasts, MCs, smooth muscle cells, endothelial cells of the GI tract [21], enteric sensory neurons, terminals of mesenteric afferent nerves, and immune cells [17]. The higher number of mast cells and mast cell tryptase in biopsied colonic tissues enhanced the PAR-2 activity to regulate CGRP, SP, and VIP expressions resulting in symptoms associated with IBD [22]. Recently, Hassler et al. [23] suggested that PAR2-expressed sensory neurons are a key target for mechanical and spontaneous pain triggered by the release of endogenous proteases from the many immune cells. In-vitro study exhibits the up-regulation of PAR-2 expression in cultured endothelial cells of human umbilical vein treated with TNF-α, IL-1α, and bacterial lipopolysaccharide in a dose-dependent manner [24]. Therefore, it is important to note that PAR-2 activation on intestinal immunocytes induces acute enteritis [9, 25] while its neuronal expression incites neurogenic inflammation [26, 27].
2.1 Role of PAR-2 in inflammation
PAR-2 seems essential in the interplay between nerves, immunocytes, MCs, and epithelial cells within the luminal wall during GI diseases [17]. Histopathologically, PAR-2-agonists (SLIGRL) induced acute colitis has been observed with erythema, granulocyte infiltrations and thickened colonic wall [25, 28], the colonic tissue sampled from the PAR-2 knockout mice that are infused intracolonically with 2,4,6-trinitrobenzene sulfonic acid (TNBS) showed lower myeloperoxidase activities, microscopic- and macroscopic-damage scores [29]. Mediators such as intracellular- and vascular cell adhesion-molecule-1 were decreased while cyclooxygenase-1 was increased in the PAR-2 knockout mice, which clearly confirms the pro-inflammatory role of PAR-2. Notably, PAR-2, inactive during colitis, has been expressed for inducing VH after resolution of colitis [30]. Furthermore, PAR-2 has also been over-expressed in biopsies obtained from ulcerative colitis (UC) and CD patients, which strongly suggests its intricate role in IBDs [31, 32, 33].
2.2 Effects of PAR-2 on gastrointestinal functions
PAR-2 modulates GI functions, such as motility, ionic exchange, paracellular permeability, sensory functions, and inflammation [34]. The excitatory, as well as inhibitory actions of PAR-2-agonists on isolated smooth muscles, have been devised earlier [35, 36]. In-vitro, PAR-2 activation shows a region-specific role because it enhances the contractibility of gastric smooth muscles and reduces the contractility of circular and longitudinal colonic smooth muscles in mice [35, 37]. However, the intraperitoneal administration of PAR-2-agonists accelerated GI transit in mice [38]. Moreover, Mall et al. (2002) reported that PAR-2 activation on the enterocytes triggers intestinal water secretion through a direct cellular mechanism, while Kong et al. [20] described the same by a prostaglandin E2-dependent mechanism. Additionally, activated PAR-2 stimulates mucus secretion by a nerve-mediated mechanism [39]. It weakens the intestinal barrier, resulting in an increased passage of fluids or even microorganisms across the gut mucosa. The intracolonic administration of PAR-2-agonist in mice increases colonic permeability and results in a general inflammatory response [25, 34].
CGRP-receptor is a heterotrimeric complex, composed of calcitonin receptor-like receptor (CLR), receptor activity-modifying protein-1, and a small intracellular protein component and receptor component protein. CLR, a classical G-protein linked receptor, couples through adenylyl cyclase [40]. CGRP is expressed throughout the peripheral and central nervous systems (CNS). Of the two forms, α-CGRP is mainly expressed in the CNS, especially in striatum, amygdalae, hypothalamus, colliculi, brainstem, cerebellum, and trigeminal complex [41, 42, 43], while β-CGRP is primarily expressed in the enteric neurons and vascular smooth muscle cells [44, 45]. Interestingly, α-CGRP is also found to be expressed in primary spinal afferent C- and Aδ-fibers [46].
The majority of spinal afferents innervated into the GI tract express CGRP and SP [47]. CGRP has been reported to be expressed markedly higher in the lumbosacral DRG and spinal cord dorsal horn (SCDH) during visceral inflammation [11, 48]. Zhang et al. [49] confirmed the absence of secondary hyperalgesia in the mice missing α-CGRP expression in the CNS. The SP and CGRP released from afferent terminals lead to neurogenic inflammation at the peripheral sites, resulting in MCs degranulation, plasma extravasation, and arteriolar vasodilation [50]. CGRP causes vasodilatation via its receptors on the smooth muscle cells at peripheral synapses. However, at central synapses, it acts postsynaptically on the second-order neurons to transmit pain via the brainstem and midbrain to higher cortical pain regions [51].
3.1 CGRP modulates mast cell functions
CGRP is secreted from non-myelinated C-fibers and thinly myelinated Aδ-fibers originating from DRG neurons [52]. Sun et al. [53] showed peak CGRP levels in the colonic tissues, spinal cord, and hypothalamus of rats with IBS, and its correlation with VH. Our earlier studies also demonstrated the remarkably higher CGRP expression in DRG and spinal cord that was correlated with VH in the TNBS-induced ileitis rats and goats, respectively [13, 15]. Therefore, CGRP and CGRP-receptors are found to be involved in the transmission and modulation of pain in the periphery and CNS [54, 55].
MCs that reside near the nerve fibers are true candidates for modulating neural activity and nociception [56]. The mediators such as SP, CGRP, vasoactive intestinal protein (VIP), dopamine, and arachidonic acid are able to influence MCs activation. The aforementioned mediators act on nociceptors, send signals to the CNS, and cause the simultaneous central release of SP and CGRP [57], which further activate MCs, and create a bidirectional positive feedback-loop for resultant neurogenic inflammation [58].
3.2 CGRP-release mediated by PAR-2
Activated PAR-2 sensitizes Transient Receptor Potential Vanilloid subtype-1 receptors (TRPV-1) and triggers the release of sensory CGRP and SP [59]. CGRP and SP released from intestinal afferent terminals cause vascular dilatation, plasma extravasation, granulocyte infiltrations, and neurogenic inflammation [8, 9, 60]. An earlier study [8] reported that PAR-2-agonists-induced edema was entirely mediated by the release of SP and CGRP from sensory neurons and further activation of neurokinin-1 (NK-1)- and CGRP-receptors on endothelial cells. In DRG, PAR-2 co-expresses with TRPV-1, TRPV-4, TRPA-1 (Transient Receptor Potential Cation Channel, Subfamily-A, Member-1), SP and CGRP [8, 61, 62]. It is also reported that 63% of sensory neurons express PAR-2 and up to 40% of them express both SP and CGRP [8]. Activated PAR-2 transmits C-fiber afferent input to the SCDH for the release of excitatory amino acids and neuropeptides from the central terminals [63].
3.3 Role of CGRP in sensitization
Afferent fibers innervating the gut vessels have cell bodies in the DRG. These fibers are peptidergic, containing both CGRP and SP, and have collaterals in enteric ganglia, mucosa, muscularis externa, and sympathetic prevertebral ganglia [64]. SP, CGRP, VIP, and somatostatin act as mediators of neurogenic inflammation in IBDs [65, 66, 67]. After stimulation, TRPV-1 depolarizes sensory neurons either directly or indirectly to initiate the release of these neuropeptides from the afferent terminals [68]. TRPV-1-positive nerve fibers co-express with SP, NK-1, and CGRP in mucosa, submucosal layer, deep muscular plexus, circular muscle, myenteric plexus, and longitudinal muscle layer in the rectum and colon of mice [69]. CGRP which is expressed largely in splanchnic afferents and CGRP-immunoreactivities from the GI tract disappears with capsaicin treatment [70]. Interestingly, about 50% of CGRP-immunoreactive extrinsic afferent neurons express SP- or NK-1-immunoreactivities [71] and their expressions fluctuate during colitis [72]. The earlier decrease of the above neuropeptides may be due to their depletion from the peripheral nerve terminals or the damaged nerves at the initial inflammatory stage. CGRP and SP increase during inflammation or afferent nerve stimulation. TNBS-induced colitis/ileitis and or colorectal distension (CRD) results in higher expression of neural activation markers (such as c-Fos, pERK) as well as releases of SP and CGRP in the SCDH that are commonly linked with pain signaling [15, 73, 74].
Plourde et al. [75] confirmed the role of CGRP in pain modulation because intravenously administered CGRP-1-receptor-antagonists (h-CGRP8-37) reversed the sensitization provoked by infusion of intracolonic acetic acid. SP and CGRP may either increase the peripheral sensory gain of extrinsic afferents within the gut or contribute to primary afferent transmission within the CNS [16, 76]. Despite irritation, immune challenge and inflammation cause the release of CGRP and SP from extrinsic afferents and intrinsic neurons within the gut [45, 77], the precise site at which CGRP-receptor and NK-1 mediate visceral pain is not known.
PAR-2 activation in GI resident cells such as MCs, macrophages, or neutrophils induces the release of tiny amounts of inflammatory mediators that sensitizes primary afferents. It regulates vascular tone and causes immense pro- or anti-inflammatory as well as pro-nociceptive effects in somatic or visceral pain [78]. PAR-2 expressed at the peripheral afferent neurons is more importantly involved in inflammation-induced VH [29, 30]. The glial cells of the enteric nervous system play pivotal roles in neuroimmune interactions and modulate enteric neurotransmission, inflammation, and intestinal barrier functions as they express receptors for purines and contain precursors for neurotransmitters such as GABA and NO. They can produce cytokines (TNF-α, IL-1β, IL-6), NGF, and neuropeptides (NK-1, SP, CGRP) after their activation. Both PAR-2 and proinflammatory cytokines impair the epithelial barrier by decreasing tight junction protein expression and consequently facilitate the entry of luminal aggressors perpetuating inflammation and pain [9].
PAR-2 expressed in enterocytes increases permeability, which is linked with the immune activation and generation of VH [25, 79]. It is found that PAR-2-agonists evoke the transient depolarization of submucosal enteric neurons with long-lasting hyperexcitability in guinea pigs [80]. Similarly, intracolonically administered PAR-2 agonist (SLIGRL-NH2, 100 μg/mouse) increased intestinal permeability and VH in mice [81]. The intracolonic administration of sub-inflammatory doses of PAR-2-agonist led to prolonging the VH in response to CRD in rats [78]. PAR-2 activation on enteric neurons is also directly responsible for the development of VH as it conveys nociceptive signals for the excitability of submucosal neurons, colonic projections of DRG, and jejunal afferent neurons [7]. Shi et al. [82] reported PAR-2 activation and higher CGRP levels in the serum and colonic tissue during VH in a rat model of IBS. Accumulating set of evidence suggests that protease activity is remarkably prominent in diarrheic-IBS and UC patients. The fecal supernatant or colonic biopsies from these patients when infused intracolonally into rodents resulted in higher intestinal permeability, mucosal inflammation, and subsequent VH through a PAR-2 activation mechanism [83, 84, 85, 86], while the same treatment failed to cause the VH in the PAR-2 knockout mice [83]. Table 1 summarizes the findings of preclinical studies that intervened in the effects of PAR-2 on underlying VH.
TNBS- and dextran sodium sulfate-induced colitis in mice
KO
Endogenous PAR-2 activation controls leukocyte recruitment in the colon and thus possesses a new potential therapeutic target for the treatment of IBD.
Currently, the role of cathepsin-S is considered insightful because it activates spinal nociceptive neurons through a PAR-2-dependent mechanism and amplifies VH. Over the years, studies reported that cathepsin-S released from spinal microglial cells during nerve injury or colitis secretes fractalkine, thereby intensifying and maintaining the chronic pain [91, 92].
Proteases directly activate PAR-2 as well as assist other pronociceptive mediators for the subsequent sensitization of afferent fibers [83]. Figure 1 illustrates the important role of PAR-2 in pain transmission during GI disorders. PAR-2 activation on afferent neurons leads to specific calcium signals that could participate in conveying pain messages [93]. Elmariah et al. [6] reported that cathepsin-S played a role in molecular signaling either alone or together with activated PAR-2. Activation of PAR-2 on DRG by its agonists enhances potassium chloride ions and the capsaicin (TRPV-1 agonist)-evoked release of CGRP [8, 94]. Protease-activated receptor-1 and PAR-2 on enteric afferent fibers facilitate nociceptive input to the CNS, while spinal PAR-2 activation aggravates pain behaviors [21]. These findings strongly suggest that visceral activation of PAR-2 has an important role in sensitizing the second-order neurons at spinal level.
Figure 1.
Role of PAR-2 in pain transmission. (a) Peripheral sensitization. PAR-2 is activated by proteases released from inflammatory and immune cells as well as from mediators of the intestinal lumen. Proteases sensitize neurons to innocuous stimuli. After stimulation, TRPV-1 depolarizes sensory neurons either directly or indirectly to initiate the release of SP and CGRP from the afferent terminals. PAR-2 activation on afferent neurons leads to specific calcium signals. (b) Primary afferent fiber. Pain signal is transmitted along primary afferent fibers to the spinal dorsal horn and subsequently to the brain. (c) Central sensitization. Persistent small-afferent input leads to a central sensitization associated with local release of SP and CGRP. PAR-2, protease-activated receptor-2;TRP, Transient Receptor Potential; Ca2+, calcium ion; SP, substance-P; CGRP, calcitonin gene-related peptide;TRPV-1, Transient Receptor Potential Vanilloid subtype-1.
Researchers have come a long way in terms of understanding and controlling the inflammation-induced VH in experimental animals. An overview of the studies described in the following paragraph is shown in Table 2. It is worth mentioning that the oral administration of PAR-2-antagonists (GB88) ameliorates acute and chronic colitis induced by PAR-2-agonists and TNBS, respectively, in rats [28]. Several studies have demonstrated that protease inhibitors and PAR-2-antagonists relieve the inflammation and resultant VH in animals [78, 83, 86, 87, 95, 96, 102]. In chronic inflammation and pain syndromes, the blockade of PAR-2 inhibits both pain signals and inflammatory responses [7]. The intraperitoneal administration of PAR-2 antagonist (FSLLRY-NH2, 3 mg/kg daily for 5 days) reversed intestinal permeability and also attenuated VH in PI-IBS mice which confirms the therapeutic potential of PAR-2antagonist in VH [81].
Increased intestinal permeability and the activation of NK1 receptors.SLIGRL-NH2 induced hyperalgesia was inhibited by a NK1 receptor antagonist (SR 140333).
Supernatants from colonic biopsies of IBS patients showed VH. Serine protease inhibitors and a PAR-2 antagonist inhibited VH. However, VH was absent in PAR-2 knockout mice.
Serene protease inhibitor and PAR-2 antagonist Knockout
Fecal supernatant from IBS-D patients infused into the colon of mice
In-vivo
Increased VH in mice infused with fecal supernatant while VH was suppressed in mice infused with intracolonic serene protease inhibitor and PAR-2 antagonist.
α-CGRP and β-CGRP play a protective role in the generation of spontaneous colitis, supporting a role for both extrinsic and intrinsic CGRP-containing neurons.
Preclinical studies targeting the antagonism or blockade of PAR-2 and CGRP as a therapeutic strategy for the management of inflammation and visceral hyperalgesia.
Studies utilizing both CGRP knockout mice and antagonist hCGRP8-37 have confirmed the protective role of CGRP in colitis and devised its insightful roles in hyperalgesia [18, 97, 98, 103]. Intravenously administered hCGRP8-37 attenuated distension-evoked pain responses and completely reversed the sensitization effects in acetic acid-induced acute colitis rats [18]. Julia and Bueno [99] reported that hCGRP8-37 also suppressed the pain in rats provoked by intraperitoneal injection of acetic acid. Furthermore, its intrathecal administration reversed the CGRP expressions and alleviated the VH in both acetic acid-induced acute and TNBS-induced chronic colitis rats [18, 19]. Recently, Noor-Mohammadi et al. [101] reported that the single dose of intraperitoneally administered anti-CGRP, i.e., F(ab’)2 fragment antibody attenuated the stress-induced colonic hypersensitivity in rats which confirms the prevailing role of CGRP in persistent visceral pain.
Nowadays, alternative therapies have been attracting attention due to their potential in the treatment of VH. Sun et al. [53] described that electroacupuncture (EA) attenuates VH in rats with diarrheic-IBS by suppressing spinal CGRP. EA therapy also alleviated the VH symptoms through downregulation of the PAR2, SP, and CGRP levels in colon tissues in post-inflammation-IBS rats [90]. Likewise, Deng et al. [100] exhibited that the EA at ST-37 and ST-25 relieved the VH in IBS rats by decreasing the number of MCs and suppressing the expression of PAR-2, TRPV1, CGRP, SP and Try proteins in the colonic tissues. Our recent study also reported the effectiveness of repetitive EA for treating both acute and chronic pain because it down-regulated the PAR-2-mediated CGRP release in the spinal cord [15]. Shi et al. [82] administered Shugan decoction (herbal extracts) intragastrically in rats in IBS model and found that it abolished VH by attenuating the release of PAR-2-mediated CGRP.
GI tract is the organ that is exposed frequently to proteases both during physiological and pathophysiological conditions. Besides degradative enzymatic roles, the proteases also act as signaling molecules in various gut diseases. Understanding the exact mechanism of VH is pivotal to identifying the novel efficacious therapy for IBDs. PAR-2 activation by tryptase, trypsin, and cathepsin-S causes the release of CGRP and SP in extrinsic primary afferent fibers and intrinsic enteric neurons [45, 77]. Both CGRP and SP facilitate the excitation of extrinsic afferents as well as participate in the central transmission of nociceptive traffic between afferent neurons and higher-order neurons in the spinal cord and brainstem. The blockade and/or antagonism of PAR-2 and CGRP release can effectively relieve VH in IBDs, IBS, or other functional bowel disorders. Further research is required to deepen our understanding of the blockade or antagonism of PAR-2 or CGRP before these potential therapies can be clinically translated for the management of VH in humans.
1.Minderhoud IM, Oldenburg B, Wismeijer JA, Van Berge Henegouwen GP, Smout AJPM. IBS-like symptoms in patients with inflammatory bowel disease in remission; relationships with quality of life and coping behavior. Digestive Diseases and Sciences. 2004;49(3):469-474
2.Bielefeldt K, Davis B, Binion DG. Pain and inflammatory bowel disease. Inflammatory Bowel Diseases. 2009;15:778-788
3.Azpiroz F, Bouin M, Camilleri M, Mayer EA, Poitras P, Serra J, et al. Mechanisms of hypersensitivity in IBS and functional disorders. Neurogastroenterology and Motility. 2007;19(Suppl. 1):62-88
4.Ossovskaya VS, Bunnett NW. Protease-activated receptors: Contribution to physiology and disease. Physiological Reviews. 2004;84(2):579-621
5.Reiser J, Adair B, Reinheckel T. Specialized roles for cysteine cathepsins in health and disease. Journal of Clinical Investigation. 2010;120:3421-3431
6.Elmariah SB, Reddy VB, Lerner EA. Cathepsin S signals via PAR2 and generates a novel tethered ligand receptor agonist. PLoS One. 2014;9(6):e99702
7.Vergnolle N. Protease-activated receptors as drug targets in inflammation and pain. Pharmacology & Therapeutics. 2009;123(3):292-309
8.Steinhoff M, Vergnolle N, Young SH, Tognetto M, Amadesi S, Ennes HS, et al. Agonists of proteinase-activated receptor-2 induce inflammation by a neurogenic mechanism. Nature Medicine. 2000;6(2):151-158
9.Cenac N, Garcia-Villar R, Ferrier L, Larauche M, Vergnolle N, Bunnett NW, et al. Proteinase-activated receptor-2-induced colonic inflammation in mice: Possible involvement of afferent neurons, nitric oxide, and paracellular permeability. Journal of Immunology. 2003;170(8):4296-4300
10.Miampamba M, Sharkey KA. Distribution of calcitonin gene-related peptide, somatostatin, substance P and vasoactive intestinal polypeptide in experimental colitis in rats. Neurogastroenterology and Motility. 1998;10(4):315-329
11.Traub RJ, Hutchcroft K, Gebhart GF. The peptide content of colonic afferents decreases following colonic inflammation. Peptides. 1999;20(2):267-273
12.Honore P, Kamp EH, Rogers SD, Gebhart GF, Mantyh PW. Activation of lamina I spinal cord neurons that express the substance P receptor in visceral nociception and hyperalgesia. The Journal of Pain. 2002;3(1):3-11
13.Shah MK, Wan J, Janyaro H, Tahir AH, Cui L, Ding MX. Visceral hypersensitivity is provoked by 2,4,6-trinitrobenzene sulfonic acid-induced ileitis in rats. Frontiers in Pharmacology. 2016;7(July):1-13
14.Wan J, Ding Y, Tahir AH, Shah MK, Janyaro H, Li X, et al. Electroacupuncture attenuates visceral hypersensitivity by inhibiting JAK2/STAT3 signaling pathway in the descending pain modulation system. Frontiers in Pharmacology. 2017;11(Nov):1-15
15.Shah MK, Ding Y, Wan J, Janyaro H, Tahir AH, Vodyanoy V, et al. Electroacupuncture intervention of visceral hypersensitivity is involved in PAR-2-activation and CGRP-release in the spinal cord. Science Reports. 2020;10:11188
16.Maggi CA. Tachykinins as peripheral modulators of primary afferent nerves and visceral sensitivity. Pharmacological Research. 1997;36(2):153-169
17.Bueno L. Protease-activated receptor-2: A new target for IBS treatment. European Review for Medical and Pharmacological Sciences. 2008;12(Suppl. 1):95-102
18.Plourde V, St-Pierre S, Quirion R. Calcitonin gene-related peptide in viscerosensitive response to colorectal distension in rats. The American Journal of Physiology. 1997;273(1 Pt 1):G191-G196
19.Gschossmann JM, Coutinho SV, Miller JC, Huebel K, Naliboff B, Wong HC, et al. Involvement of spinal calcitonin gene-related peptide in the development of acute visceral hyperalgesia in the rat. Neurogastroenterology and Motility. 2001;13(3):229-236
20.Kong W, McConalogue K, Khitin LM, Hollenberg MD, Payan DG, Böhm SK, et al. Luminal trypsin may regulate enterocytes through proteinase-activated receptor 2. Proceedings of the National Academy of Sciences of the United States of America. 1997;94(16):8884-8889
21.Vergnolle N. Modulation of visceral pain and inflammation by protease-activated receptors. British Journal of Pharmacology. 2004;141(8):1264-1274
22.Liang WJ, Zhang G, Luo HS, Liang LX, Huang D, Zhang FC. Tryptase and protease-activated receptor 2 expression levels in irritable bowel syndrome. Gut Liver. 2016;10(3):382-390
23.Hassler SN, Kume M, Mwirigi JM, Ahmad A, Shiers S, Wangzhou A, et al. The cellular basis of protease activated receptor type 2 (PAR2) evoked mechanical and affective pain. bioRxiv. 2020;5(11):1-17
24.Nystedt S, Ramakrishnan V, Sundelin J. The proteinase-activated receptor 2 is induced by inflammatory mediators in human endothelial cells. Comparison with the thrombin receptor. The Journal of Biological Chemistry. 1996;271(25):14910-14915
25.Cenac N, Coelho AM, Nguyen C, Compton S, Andrade-Gordon P, MacNaughton WK, et al. Induction of intestinal inflammation in mouse by activation of proteinase-activated receptor-2. The American Journal of Pathology. 2002;161(5):1903-1915
26.Nguyen C, Coelho AM, Grady E, Compton SJ, Wallace JL, Hollenberg MD, et al. Colitis induced by proteinase-activated receptor-2 agonists is mediated by a neurogenic mechanism. Canadian Journal of Physiology and Pharmacology. 2003;81(9):920-927
27.Vergnolle N, Ferazzini M, Dandrea MR, Buddenkotte J, Steinhoff M. Proteinase-activated receptors: Novel signals for peripheral nerves. Trends in Neurosciences. 2003;26(9):496-500
28.Lohman RJ, Cotterell AJ, Suen J, Liu L, Do AT, Vesey DA, et al. Antagonism of protease-activated receptor 2 protects against experimental colitis. The Journal of Pharmacology and Experimental Therapeutics. 2012;340(2):256-265
29.Hyun E, Andrade-Gordon P, Steinhoff M, Vergnolle N. Protease-activated receptor-2 activation: A major actor in intestinal inflammation. Gut. 2008;57(9):1222-1229
30.Suckow SK, Caudle RM. NMDA receptor subunit expression and PAR-2 receptor activation in colospinal afferent neurons (CANs) during inflammation induced visceral hypersensitivity. Molecular Pain. 2009;5:54
31.Kim JA, Choi SC, Yun KJ, Kim DK, Han MK, Seo GS, et al. Expression of protease-activated receptor 2 in ulcerative colitis. Inflammatory Bowel Diseases. 2003;9(4):224-229
32.Christerson U, Keita V, Söderholm JD, Gustafson-Svärd C. Increased expression of protease-activated receptor-2 in mucosal mast cells in Crohn’s ileitis. Journal of Crohn’s & Colitis. 2009;3(2):100-108
33.Christerson U, Keita ÅV, Söderholm JD, Gustafson-Svärd C. Potential role of protease-activated receptor-2-stimulated activation of cytosolic phospholipase A2 in intestinal myofibroblast proliferation: Implications for stricture formation in Crohn’s disease. Journal of Crohn’s & Colitis. 2009;3(1):15-24
34.Vergnolle N. Clinical relevance of proteinase-activated receptors (PARs) in the gut. Gut. 2005;54(6):867-874
35.Saifeddine M, Al-Ani B, Cheng CH, Wang L, Hollenberg MD. Rat proteinase-activated receptor-2 (PAR-2): cDNA sequence and activity of receptor-derived peptides in gastric and vascular tissue. British Journal of Pharmacology. 1996;118(3):521-530
36.Kawabata A, Kuroda R, Nishikawa H, Kawai K. Modulation by protease-activated receptors of the rat duodenal motility in vitro: Possible mechanisms underlying the evoked contraction and relaxation. British Journal of Pharmacology. 1999;128(4):865-872
37.Corvera CU, Dery O, McConalogue K, Bohm SK, Khitin LM, Caughey GH, et al. Mast cell tryptase regulates rat colonic myocytes through proteinase-activated receptor-2. The Journal of Clinical Investigation. 1997;100(6):1383-1393
38.Kawabata A, Kinoshita M, Nishikawa H, Kuroda R, Nishida M, Araki H, et al. The protease-activated receptor-2 agonist induces gastric mucus secretion and mucosal cytoprotection. The Journal of Clinical Investigation. 2001;107(11):1443-1450
39.Kawabata A, Kawao N, Kuroda R, Tanaka A, Itoh H, Nishikawa H. Peripheral PAR-2 triggers thermal hyperalgesia and nociceptive responses in rats. Neuroreport. 2001;12(4):715-719
40.Bhatt DK, Gupta S, Ploug KB, Jansen-Olesen I, Olesen J. mRNA distribution of CGRP and its receptor components in the trigeminovascular system and other pain related structures in rat brain, and effect of intracerebroventricular administration of CGRP on Fos expression in the TNC. Neuroscience Letters. 2014;559:99-104
41.Hokfelt T, Arvidsson U, Ceccatelli S, Cortes R, Cullheim S, Dagerlind A, et al. Calcitonin gene-related peptide in the brain, spinal cord, and some peripheral systems. Annals of the New York Academy of Sciences. 1992;657(1):119-134
42.Eftekhari S, Salvatore CA, Calamari A, Kane SA, Tajti J, Edvinsson L. Differential distribution of calcitonin gene-related peptide and its receptor components in the human trigeminal ganglion. Neuroscience. 2010;169(2):683-696
43.Edvinsson L, Eftekhari S, Salvatore CA, Warfvinge K. Cerebellar distribution of calcitonin gene-related peptide (CGRP) and its receptor components calcitonin receptor-like receptor (CLR) and receptor activity modifying protein-1 (RAMP-1) in rat. Molecular and Cellular Neurosciences. 2011;46(1):333-339
44.Sternini C, Anderson K. Calcitonin gene-related peptide-containing neurons supplying the rat digestive system: Differential distribution and expression pattern. SomatosensMotRes. 1992;9(1):45-59
45.Muddhrry PK, Ghatki MA, Spokks RA, Jonhs PM, Pierson AM, Hamid QA, et al. Differential expression of ??-CGRP and ??-CGRP by primary sensory neurons and enteric autonomic neurons of the rat. Neuroscience. 1988;25(1):195-205
46.Eftekhari S, Edvinsson L. Calcitonin gene-related peptide (CGRP) and its receptor components in human and rat spinal trigeminal nucleus and spinal cord at C1-level. BMC Neuroscience. 2011;12(1):112-129
47.Perry MJ, Lawson SN. Differences in expression of oligosaccharides, neuropeptides, carbonic anhydrase and neurofilament in rat primary afferent neurons retrogradely labelled via skin, muscle or visceral nerves. Neuroscience. 1998;85(1):293-310
48.Galeazza M, Garry M, Yost H, Strait K, Hargreaves K, Seybold V. Plasticity in the synthesis and storage of substance-P and calcitonin gene-related peptide in primary afferent neurons during peripheral inflammation. Neuroscience. 1995;66(2):443-458
50.Wesselmann U. Neurogenic inflammation and chronic pelvic pain. World Journal of Urology. 2001;19(3):180-185
51.Goadsby PJ. Recent advances in understanding migraine mechanisms, molecules and therapeutics. Trends in Molecular Medicine. 2007;13(1):39-44
52.van Rossum D, Hanisch UK, Quirion R. Neuroanatomical localization, pharmacological characterization and functions of CGRP, related peptides and their receptors. Neuroscience and Biobehavioral Reviews. 1997;21(5):649-678
53.Sun J, Wu X, Meng Y, Cheng J, Ning H, Peng Y, et al. Electro-acupuncture decreases 5-HT, CGRP and increases NPY in the brain-gut axis in two rat models of Diarrhea-predominant irritable bowel syndrome(D-IBS). BMC Complementary and Alternative Medicine. 2015;15(1):340
54.Sun RQ , Tu YJ, Lawand NB, Yan JY, Lin Q , Willis WD. Calcitonin gene-related peptide receptor activation produces PKA- and PKC-dependent mechanical hyperalgesia and central sensitization. Journal of Neurophysiology. 2004;92(5):2859-2866
55.Bird GC, Han JS, Fu Y, Adwanikar H, Willis WD, Neugebauer V. Pain-related synaptic plasticity in spinal dorsal horn neurons: Role of CGRP. Molecular Pain. 2006;2(1):31
56.Aich A, Afrin LB, Gupta K. Mast cell-mediated mechanisms of nociception. International Journal of Molecular Sciences. 2015;16:29069
57.Diest SA V, Stanisor OI, Boeckxstaens GE, Jonge WJ De, Wijngaard RMVD. Relevance of mast cell-nerve interactions in intestinal nociception. Biochimica et Biophysica Acta. 2012;1822(1):74-84
58.Kowalski ML, Kaliner MA. Neurogenic inflammation, vascular permeability, and mast cells. Journal of Immunology. 1988;140(11):3905-3911
59.Adam B, Liebregts T, Gschossmann JM, Krippner C, Scholl F, Ruwe M, et al. Severity of mucosal inflammation as a predictor for alterations of visceral sensory function in a rat model. Pain. 2006;123(1-2):179-186
60.Geppetti P, Trevisani M. Activation and sensitisation of the vanilloid receptor: Role in gastrointestinal inflammation and function. British Journal of Pharmacology. 2004;141(8):1313-1320
61.Amadesi S, Nie J, Vergnolle N, Cottrell GS, Grady EF, Trevisani M, et al. Protease-activated receptor-2 sensitizes the capsaicin receptor transient receptor potential vanilloid receptor-1 to induce hyperalgesia. The Journal of Neuroscience. 2004;24(18):4300-4312
62.Grant AD, Cottrell GS, Amadesi S, Trevisani M, Nicoletti P, Materazzi S, et al. Protease-activated receptor-2 sensitizes the transient receptor potential vanilloid-4 ion channel to cause mechanical hyperalgesia in mice. The Journal of Physiology. 2007;578(Pt 3):715-733
63.Murase K, Ryu PD, Randic M. Excitatory and inhibitory amino acids and peptide-induced responses in acutely isolated rat spinal dorsal horn neurons. Neuroscience Letters. 1989;103(1):56-63
64.Humenick AG, Chen BN, Brookes SJH. Gut mechano-nociceptors can be activated by intra-arterial pressure in the physiological range. In: 1st Annual Meeting : Australasian Neuro Gastroenterology & Motility Association Inc (ANGMA). 2014. p. 8
65.Calam J, Ghatei MA, Domin J, Adrian TE, Myszor M, Gupta S, et al. Regional differences in concentrations of regulatory peptides in human colon mucosal biopsy. Digestive Diseases and Sciences. 1989;34(8):1193-1198
66.Surrenti C, Renzi D, Garcea MR, Surrenti E, Salvadori G. Colonic vasoactive intestinal polypeptide in ulcerative colitis. Journal of Physiology Paris. 1993;87(5):307-311
67.Yamamoto H, Morise K, Kusugami K. Furusawa a, Konagaya T, Nishio Y, et al. Abnormal neuropeptide concentration in rectal mucosa of patients with inflammatory bowel disease. Journal of Gastroenterology. 1996;31(4):525-532
68.Szallasi A, Blumberg PM. Vanilloid (Capsaicin) receptors and mechanisms. Pharmacological Reviews. 1999;51(2):159-212
69.Matsumoto K, Hosoya T, Tashima K, Namiki T, Murayama T, Horie S. Distribution of transient receptor potential vanilloid 1 channel-expressing nerve fibers in mouse rectal and colonic enteric nervous system: Relationship to peptidergic and nitrergic neurons. Neuroscience. 2011;172:518-534
70.Sternini C. Enteric and visceral afferent CGRP neurons. Annals of the New York Academy of Sciences. 1992;657(1):170-186
71.Bueno L, Fioramonti J. Visceral perception: Inflammatory and non-inflammatory mediators. Gut. 2002;51(Suppl. 1):i19-i23
72.Eysselein E, Nast C, Snape J. Calcitonin gene-related peptide and Substance P Decrease in the Rabbit Colon During Colitis A Time Study. Gastroenterology. 1991;101(5):1211-1219
73.Sun YN, Luo JY. Effects of tegaserod on Fos, substance P and calcitonin gene-related peptide expression induced by colon inflammation in lumbarsacral spinal cord. World Journal of Gastroenterology. 2004;10(12):1830-1833
74.Harrington AM, Brierley SM, Isaacs N, Hughes PA, Castro J, Blackshaw LA. Sprouting of colonic afferent central terminals and increased spinal mitogen-activated protein kinase expression in a mouse model of chronic visceral hypersensitivity. The Journal of Comparative Neurology. 2012;520(10):2241-2255
75.Plourde V, Boivin M, St-Pierre S, McDuff J. CGRP plays a role in mediating visceral nociception induced by rectocolonic distension in the rat. Gastroenterology. 1995;108(4):A669
76.Bueno L, Fioramonti J, Delvaux M, Frexinos J. Mediators and pharmacology of visceral sensitivity: From basic to clinical investigations. Gastroenterology. 1997;112(5):1714-1743
77.Chiocchetti R, Grandis A, Bombardi C, Lucchi ML, Dal Lago DT, Bortolami R, et al. Extrinsic and intrinsic sources of calcitonin gene-related peptide immunoreactivity in the lamb ileum: A morphometric and neurochemical investigation. Cell and Tissue Research. 2006;323(2):183-196
78.Coelho AM, Vergnolle N, Guiard B, Fioramonti J, Bueno L. Proteinases and proteinase-activated receptor-2: A possible role to promote visceral hyperalgesia in rats. Gastroenterology. 2002;122(4):1035-1047
79.Cenac N, Chin AC, Garcia-Villar R, Salvador-Cartier C, Ferrier L, Vergnolle N, et al. PAR-2 activation alters colonic paracellular permeability in mice via IFN-gamma-dependent and -independent pathways. The Journal of Physiology. 2004;558(Pt 3):913-925
80.Reed DE, Barajas-Lopez C, Cottrell G, Velazquez-Rocha S, Dery O, Grady EF, et al. Mast cell tryptase and proteinase-activated receptor 2 induce hyperexcitability of guinea-pig submucosal neurons. The Journal of Physiology. 2003;547(Pt 2):531-542
81.Du L, Long Y, Kim JJ, Chen B, Zhu Y, Dai N. Protease activated Receptor-2 induces immune activation and visceral hypersensitivity in post-infectious irritable bowel syndrome mice. Digestive Diseases and Sciences. 2018;64(3):729-739
82.Shi HL, Liu CH, Ding LL, Zheng Y, Fei XY, Lu L, et al. Alterations in serotonin, transient receptor potential channels and protease-activated receptors in rats with irritable bowel syndrome attenuated by Shugan decoction. World Journal of Gastroenterology. 2015;21(16):4852-4863
83.Cenac N, Andrews CN, Holzhausen M, Chapman K, Cottrell G, Andrade-Gordon P, et al. Role for protease activity in visceral pain in irritable bowel syndrome. The Journal of Clinical Investigation. 2007;117(3):636-647
84.Gecse K, Róka R, Ferrier L, Leveque M, Eutamene H, Cartier C, et al. Increased faecal serine protease activity in diarrhoeic IBS patients: A colonic lumenal factor impairing colonic permeability and sensitivity. Gut. 2008;57(5):591-599
85.Annahazi A, Gecse K, Dabek M, Ait-Belgnaoui A, Rosztoczy A, Roka R, et al. Fecal proteases from diarrheic-IBS and ulcerative colitis patients exert opposite effect on visceral sensitivity in mice. Pain. 2009;144(1-2):209-217
86.Tooth D, Garsed K, Singh G, Marciani L, Lam C, Fordham I, et al. Characterisation of faecal protease activity in irritable bowel syndrome with diarrhoea: Origin and effect of gut transit. Gut. 2014;63(5):753-760
87.Vergnolle N, Wallace JL, Bunnett NW, Hollenberg MD. Protease-activated receptors in inflammation, neuronal signaling and pain. Trends in Pharmacological Sciences. 2001;22(3):146-152
88.Kawabata A, Kawao N, Kitano T, Matsunami M, Satoh R, Ishiki T, et al. Colonic hyperalgesia triggered by proteinase-activated receptor-2 in mice: Involvement of endogenous bradykinin. Neuroscience Letters. 2006;402(1-2):167-172
89.Valdez-Morales EE, Overington J, Guerrero-Alba R, Ochoa-Cortes F, Ibeakanma CO, Spreadbury I, et al. Sensitization of peripheral sensory nerves by mediators from colonic biopsies of diarrhea-predominant irritable bowel syndrome patients: A role for PAR2. The American Journal of Gastroenterology. 2013;108(10):1634-1643
90.Xu W, Yuan M, Wu X, Geng H, Chen L, Zhou J, et al. Electroacupuncture relieves visceral hypersensitivity by inactivating protease-activated receptor 2 in a rat model of postinfectious irritable bowel syndrome. Evidence-based Complementary and Alternative Medicine. 2018:7048584
91.Clark AK, Yip PK, Malcangio M. The liberation of fractalkine in the dorsal horn requires microglial cathepsin S. The Journal of Neuroscience. 2009;29(21):6945-6954
92.Cattaruzza F, Lyo V, Jones E, Pham D, Hawkins J, Kirkwood K, et al. Cathepsin S is activated during colitis and causes visceral hyperalgesia by a PAR 2-dependent mechanism in mice. Gastroenterology. 2011;141(5):1864-1874
93.Fiorucci S, Distrutti E. Role of PAR2 in pain and inflammation. Trends in Pharmacological Sciences. 2002;23(4):153-155
94.Hoogerwerf WA, Zou L, Shenoy M, Sun D, Micci MA, Lee-Hellmich H, et al. The proteinase-activated receptor 2 is involved in nociception. The Journal of Neuroscience. 2001;21(22):9036-9042
95.Hoogerwerf WA, Shenoy M, Winston JH, Xiao SY, He Z, Pasricha PJ. Trypsin mediates nociception via the proteinase-activated receptor 2: A potentially novel role in pancreatic pain. Gastroenterology. 2004;127(3):883-891
96.Wang P, Chen FX, Du C, Li CQ , Yu YB, Zuo XL, et al. Increased production of BDNF in colonic epithelial cells induced by fecal supernatants from diarrheic IBS patients. Scientific Reports. 2015;5:10121
97.Delafoy L, Gelot A, Ardid D, Eschalier A, Bertrand C, Doherty AM, et al. Interactive involvement of brain derived neurotrophic factor, nerve growth factor, and calcitonin gene related peptide in colonic hypersensitivity in the rat. Gut. 2006;55(7):940-945
98.Thompson BJ, Washington MK, Kurre U, Singh M, Rula EY, Emeson RB. Protective roles of alpha-calcitonin and beta-calcitonin gene-related peptide in spontaneous and experimentally induced colitis. Digestive Diseases and Sciences. 2008;53(1):229-241
99.Julia V, Bueno L. Tachykininergic mediation of viscerosensitive responses to acute inflammation in rats: Role of CGRP. The American Journal of Physiology. 1997;272(1 Pt 1):G141-G146
100.Deng D-X, Tan J, Zhang H, Huang G-L, Li S, Guo K-K, et al. Electroacupuncture relieves visceral hypersensitivity by down-regulating mast cell number PAR-2/TRPV 1 signaling, etc. in colonic tissue of rats with irritable bowel syndrome. Acupuncture Research. 2018;43(8):485-491
101.Noor-Mohammadi E, Ligon CO, Mackenzie K, Stratton J, Shnider S, Greenwood-Van MB. A Monoclonal Anti–Calcitonin gene-related peptide antibody decreases stress-induced colonic hypersensitivity. The Journal of Pharmacology and Experimental Therapeutics. 2021;379(3):270-279
102.Zhang L, Song J, Hou X. Mast cells and irritable bowel syndrome: From the bench to the bedside. Journal of Neurogastroenterology and Motility. 2016;22(2):181-192
103.Qiao LY, Grider JR. Colitis induces calcitonin gene-related peptide expression and Akt activation in rat primary afferent pathways. Experimental Neurology. 2009;219(1):93-103
Written By
Manoj Shah
Submitted: 14 July 2022Reviewed: 28 July 2022Published: 19 January 2023
Open access peer-reviewed chapter
