| Objective: Type II collagen, which is the major component of articular cartilage, appears to be a relevant putative autoantigen in patients with rheumatoid arthritis (RA). Although oral administration of antigen (such as type II collagen) before disease induction can prevent disease symptoms in animal models of RA, oral administration of antigen after disease onset or in human disease has been less successful. 1, 25- (OH) 2 D3, the activated form of vitamin D, has , in addition to its central function in calcium and bone metabolism, pronounced immunoregulatory properties, can induce in vivo DSc with a tolerogenic phenotype, enhance the frequency of CD4+CD25+regulatory T cells that able to inhibit CD4+CD25" pathogenic T cells. The enhancement of CD4+CD25+ regulatory T cells able to mediate transplantation tolerance and to arrest autoimmune diseasedevelopment, suggests possible clinical applications of this approach. We induced oral tolerance by combination of chicken type II collagen (CCII) and la-hydroxyvitamin D3 to evaluate their prevention of rat adjuvant-induced arthritis (ALA), and explore its potential mechanism.Methods: AIA was induced in Wistar rats by immunization with Mycobacterium in Freund's incomplete adjuvant (CFA). Oral feeding of CC II 30ug in the absence (as OT1 group) or presence (as OT2 group) of la-hydroxyvitamin D3 50ng every day for 14 consecutive days was stared after CFA immunization. Rats that were administered vehicle alone for 14 consecutive days after induction by CFA or normal saline were observed as AIA control group or normal control group, respectively. Rats were then scored for signs of arthritis, and histologic sections of ankle joint were examined for pathologic changes using an established 4-point scoring system. 14 days after CFA immunization, splenocytes were examined in vitro by MTT method to determine the effects of oral tolerance on proliferation specific to CC II. 28 days after CFA immunization, bloods were taken to measure the amounts of CC II -specific antibody by ELISA method. 28 days after CFA immunization, histologic sections of intestine Peyer's patch, inguinal lymph nodes and synovial membranes of ankle joint were examined for lymphocytes expression of CD25 and TGF-61 by immunohistochemical assay.Results: AIA model was established successfully. Oral feeding CCII 30ug in the presence of la-hydroxyvitamin D3 50ng every day for 14 consecutive days after CFA immunization reduced incidence, symptoms, pathologic scoring for histologic sections of ankle joint, and also CC II-specific lymphocytes proliferation. CC II-specific antibody titers decreased by CCII /la-hydroxyvitamin D3, and also by CCII alone. Lymphocytes expression CD25 and TGF-61 in intestine Peyer's patch or inguinal lymph nodes were significant enhanced respectively by CCII /1a-hydroxyvitamin D3, and also by CCII alone, however, CCII /1a-hydroxyvitamin D3 appeared more effective than CCII alone. Lymphocytes expressions CD25 were well positive line-correlation with that of TGF-61. None of lymphocyte in synovial membrance of ankle joint expressed CD25 or TGF-61.Conclusions: Oral feeding CCII 30ug in the presence of la-hydroxyvitamin D3 50ng every day for 14 consecutive days after CFA immunization induces tolerance successfully and significant arrests progression of AIA. CC II /la-hydroxyvitamin D3 enhanced the frequency of CD4+CD25+ regulatory T cells in intestine Peyer's patch and inguinal lymph nodes, increased expression of membrance surface TGF-61, might suppress pathogenic CD4+CD25" T cells through direct cell-to-cell contact suppression via surface TGF-61 and TGF-61 receptor II, which arrests theprogression of arthritis in animal model of RA. Although CCII alone enhance the frequency of CD4+CD25+ regulatory T cells in intestine Peyer's patch and inguinal lymph nodes, it might be not enough to arrest the progression of arthritis. The enhancement of CD4+CD25+ regulatory T cells, such as a combination of CCII and la-hydroxyvitamin D3 induce immune tolerance, may provide... |
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