During the development of rheumatoid arthritis (RA) autoantibodies to IgG-Fc, citrullinated proteins, collagen type II (CII), glucose 6 phosphoisomerase (G6PI) and some other self-antigens appear. Of these, a pathogenic effect of the anti-CII and anti-G6PI antibodies is well demonstrated using animal models. These new antibody mediated arthritis models have proven to be very useful for studies involved in understanding the molecular pathways of the induction of arthritis in joints. Both the complement and FcγR systems have been found to play essential roles. Neutrophils and macrophages are important inflammatory cells and the secretion of tumour necrosis factor-α and IL-1β is pathogenic. The identification of the genetic polymorphisms predisposing to arthritis is important for understanding the complexity of arthritis. Disease mechanisms and gene regions studied using the two antibody-induced arthritis mouse models (collagen antibody-induced arthritis and serum transfer-induced arthritis) are compared and discussed for their relevance in RA pathogenesis.
IntroductionBoth genetic and environmental factors interact and contribute to the development of autoimmune diseases. One such disease debilitating joint architecture is rheumatoid arthritis (RA). Arthritis in the joint involves a multicellular inflammatory process, including infiltration of lymphocytes and granulocytes into the articular cartilage, proliferation of synovial fibroblasts and macrophages and neovascularization of the synovial lining surrounding the joints. This proliferative process not only induces swelling, erythema, and pain in multiple joints but also progresses to joint destruction and causes loss of bone density and architecture. Many cellular components (macrophages, dendritic cells, fibroblast-like synoviocytes, mast cells, eosinophils, neutrophils, T cells and B cells), cell surface molecules (adhesion molecules, integrins), signaling components (ZAP70, PTPN22, JAK, mitogen activated protein kinase and Stat1) and humoral mediators (antibodies, cytokines, chemokines, metalloproteinases, serine proteases and aggrecanases) interact and aid in the disease progression, leading to digestion of extracelluar matrix and destruction of articular structures.The importance of B cells in RA pathogenesis stems not only from the original finding of high titers of rheumatoid factors (RFs), but also from the observation that arthritis is mediated in experimental animals via B cells and anti-collagen type II (anti-CII) antibodies [1][2][3][4][5]. Interest in studying the role of B cells in arthritis has returned as a result of successful anti-CD20 therapy [6][7][8]. In addition, the two widely used mouse models of antibody-initiated arthritis, collagen antibodyinduced arthritis (CAIA; induced with anti-CII antibodies) and the newly developed serum transfer-induced arthritis (STIA; induced with anti-glucose 6 phosphoisomerase (anti-G6PI) anti-sera) have been better characterized. B cells can contribute to the disease pathogenesis as antigen presenti...