Merih Birlik

By Selim Nalbant and Ahmet Merih Birlik

Cytokines are cell molecules that are secreted by immune cells and aid cell to cell communication in immune responses and stimulate the movement of cells towards sites of inflammation, infection and trauma. So, the cytokines are the main part of the immune network to provide the communication in rheumatoid arthritis (RA) too. In RA, cytokines may be classified into four groups: pro-inflammatory cytokines, inflammatory cytokines in joints, anti-inflammatory cytokines and natural cytokine antagonists. After the initial stimuli have occurred, cytokines play a role in communication between the parts of immune system in every step of the pathophysiology process of RA. The differentiation of narve T cells into Th17 cells results in inflammation (synovitis) in joints. B cells further the pathogenic process through antigen presentation and autoantibody and cytokine production. The release of cytokines, especially tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1, causes synovial inflammation. In addition to their articular effects, pro-inflammatory cytokines promote the development of systemic effects (anemia, cardiovascular disease, fatigue and depression). So, cytokines are the main molecules contributing to all facets of the disease.

Part of the book: New Developments in the Pathogenesis of Rheumatoid Arthritis

By Merih Birlik, Ayşe Koçak and Duygu Harmancı

Rheumatoid arthritis (RA) is a common autoimmune disease. The hallmarks of RA are synovial inflammation and hyperplasia, autoantibody production, systemic features, and deformity. A lot of researchers have paid attention to the possibility that microRNAs (miRNAs) play a role in the pathogenesis of RA. miRNAs are a class of small noncoding RNAs, which have 18–25 nucleotides. These small RNAs modify gene expression by binding to target messenger RNA (mRNA), and they block the translation or induce the degradation of target mRNA. Biological relevance of miRNAs has been investigated in physiological and pathological conditions. A growing body of evidence suggests that miRNAs participate in the inflammatory disorders including RA. In this chapter, an overview of biogenesis and function of miRNAs has been presented to introduce researchers to the changes and functional regulation of the key miRNAs in RA and to provide current knowledge in miRNA and RA. It is important to understand the relationship between the key miRNAs and RA pathology as modulation of specific miRNA alterations could be of great pharmaceutical interest in the future.

Part of the book: New Developments in the Pathogenesis of Rheumatoid Arthritis