Osteoarthritis (OA), one of the most common rheumatic disorders, is characterized by cartilage breakdown and by synovial inflammation that is directly linked to clinical symptoms such as joint swelling, synovitis and inflammatory pain The gold-standard method for detecting synovitis is histological analysis of samples obtained by biopsy, but the noninvasive imaging techniques MRI and ultrasonography might also perform well The inflammation of the synovial membrane that occurs in both the early and late phases of OA is associated with alterations in the adjacent cartilage that are similar to those seen in rheumatoid arthritis Catabolic and proinflammatory mediators such as cytokines, nitric oxide, prostaglandin E(2) and neuropeptides are produced by the inflamed synovium and alter the balance of cartilage matrix degradation and repair, leading to excess production of the proteolytic enzymes responsible for cartilage breakdown Cartilage alteration in turn amplifies synovial inflammation, creating a vicious circle As synovitis is associated with clinical symptoms and also reflects joint degradation in OA, synovium-targeted therapy could help alleviate the symptoms of the disease and perhaps also prevent structural progression

The role of synovitis in pathophysiology and clinical symptoms of osteoarthritis

The collagen-induced arthritis (CIA) mouse model is the most commonly studied autoimmune model of rheumatoid arthritis. Autoimmune arthritis is induced in this model by immunization with an emulsion of complete Freund's adjuvant and type II collagen (CII). This protocol describes the steps necessary for acquisition, handling and preparation of CII, as well as selection of mouse strains, proper immunization technique and evaluation of the arthritis incidence and severity. Typically, the first signs of arthritis appear in this model 21–28 days after immunization, and identification of the arthritic limbs is not difficult. Using the protocol described, the investigator should be able to reproducibly induce a high incidence of CIA in various strains of genetically susceptible mice as well as learn how to critically evaluate the pathology of the disease. The total time for the preparation of reagents and the immunization of ten mice is about 1.5 h.

/pdf/collagen-induced-arthritis-2nlqbopcsg.pdf

Collagen-induced arthritis

Collagen-induced arthritis (CIA) is an animal model of autoimmunity that has been studied extensively because of its similarities to rheumatoid arthritis (RA). CIA is induced in genetically susceptible strains of mice by immunization with type II collagen (CII), and both T cell and B cell immunity to CII are required for disease manifestation. Like RA, CIA is primarily an autoimmune disease of articular joints and susceptibility to CIA is linked to specific class II molecules of the major histocompatibility complex (H-2(r) and H-2(q)). Recently, it was demonstrated that transgenic expression of HLA-DR1 (*0101) or DR4 (*0401) molecules associated with susceptibility to RA also conferred susceptibility to CIA in the mouse model. The T cell response to CII has been extensively characterized in both the DR transgenic and naturally susceptible mouse strains, including the antigenic determinants recognized, the role of post transcriptional modifications of these determinants in the pathogenic T cell response, and the cytokines produced. Like most class II-mediated autoimmune diseases, the cytokine production of CII-specific T cells reflects a Th1 phenotype of the autoimmune response. While the direct role of T cells in the pathogenesis of CIA is unclear, the B cell response in terms of anti-CII immunoglobulin is critical to the development of the disease. This response, predominated by the IgG2 isotype, requires the activation of the complement cascade for the development of CIA. In recent years, the pathogenesis of this model has been studied extensively and the CIA model is proving to be a valuable asset for the design of new immunotherapeutics for the potential treatment of RA and other autoimmune diseases.

Immunopathogenesis of collagen arthritis.

Rheumatoid arthritis (RA) is associated with certain MHC class II alleles and is characterized by a chronic autoimmune response in the joints. Using transgenic mice expressing human DR4 (DRB1*0401) and human CD4, but lacking endogenous MHC class II, we show that posttranslational glycosylation of type II collagen (CII) influences the level of T cell tolerance to this candidate cartilage-specific autoantigen. In such mice, the expression of human CII resulted in a tolerized murine T cell response to human CII. However, tolerance induction remained incomplete, preferentially deleting responses to the nonmodified CII 263-270 epitope, whereas T cell recognition of a glycosylated variant of this epitope was affected to a lesser degree. A similar dominance of T cell responses to CII-glycopeptides was recorded in a cohort of severely affected RA-patients (n = 14). Thus, RA T cells predominantly recognize the immunodominant CII peptide in its glycosylated form and may explain why previously it has been difficult to detect T cell responses to CII in RA patients.

https://www.pnas.org/content/pnas/99/15/9960.full.pdf

Predominant selection of T cells specific for the glycosylated collagen type II epitope (263–270) in humanized transgenic mice and in rheumatoid arthritis

Type II collagen autoimmunity in a mouse model of human rheumatoid arthritis.

Objective

To determine the presence of specific immune recognition of type II collagen (CII) and its immunodominant epitope CII (255–274) in patients with rheumatoid arthritis (RA).



Methods

T cell proliferative responses to bovine CII and a synthetic peptide encompassing CII (255–274) in peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cells (SFMC) from RA patients, and in PBMC from osteoarthritis (OA) patients and healthy controls were assayed by mixed lymphocyte culture.



Results

The stimulation index (SI) and the number of positive (SI ≥2) T cell responses to CII were higher in RA patients (n = 106) than in OA patients (n = 26) and healthy controls (n = 34). T cell responses to CII (255–274) were also enhanced in RA patients and correlated well with those to CII. In SFMC, positive responses to CII or CII (255–274) were detected in 61.9% of 42 RA patients. T cell responses to CII in SFMC were stronger and more prevalent than peripheral responses. The SI and positive responses to CII were higher in early RA than in late RA. Levels of IgG antibodies to CII in synovial fluid inversely correlated with T cell responses to CII.



Conclusion

T cell responses to CII or CII (255–274) were enhanced in RA, especially in early disease. Synthetic peptide CII (255–274), as well as native CII, could be recognized as immunogenic antigens by T cells, particularly in the synovial fluid. These observations suggest that CII-reactive T cells play an important role in the pathogenesis of RA. Peripheral tolerance induction using CII (255–274) might be useful in the treatment of RA.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/1529-0131%28199910%2942%3A10%3C2085%3A%3AAID-ANR8%3E3.0.CO%3B2-Z

Jae-Ho Park

Papers

Enhanced T cell proliferative response to type II collagen and synthetic peptide CII (255-274) in patients with rheumatoid arthritis.