修饰型Ⅱ型胶原肽对HLA-DRβ1介导的自身免疫病调控作用的研究

It has been demonstrated that formation of HLA-DR-antigen peptide-T cell receptor (TCR) trimolecular complex plays an important role in T cell activation. Altered peptides with substitution of TCR recognizing residues might be of non-T cell stimulating feature, so that it may act as an agonist to antigen peptide for competitive binding with HLA-DR molecule. The non-T cell binding peptide might be a new therapeutic strategy of rheumatoid arthritis by inhibition of T cell activation. The objective of the study was to evaluate the inhibitory effect of HLA-DR1/DR4 -restricted non-TCR recognizing peptides on T cell activation and collagen-induced arthritis. .The study includes four aspects: 1. Computer modeling of contact between HLA-DR1/DR4 molecule with CII 263-272 and the altered CII 263-272 peptides. 2. Determination of effect of the altered peptides on T cell activation both in HLA-DR1 or DR4-restricted system. 3. Evaluation of the inhibitory effect of non-T cell binding peptides on collagen-induced arthritis (CIA). 4. Evaluation of the effect of non-T cell binding peptides on T cell activation of RA patient.Computer modeling showed that the side chains of F263 and E266 contact with corresponding points molecule on a1and b1 chains of HLA-DR1 or DR4 by hydrogen bonds; The side chains of Q267 and K270 protrude out of the cleft and play an important role in TCR recognizition. The altered peptides with substitution of Q267, G268, P269 and K270 individually and consecutively substitution of G268, P269 and K270 by alanine (A) or glycine (G) was found hyporesponsive in T cell activation. Altered peptides 270A, sub268-270 dramatically suppressed T cell activation induced by wild type CII263-272. Subcutaneously injection of non-T cell binding peptide 268A showed inhibitory effect on CIA. TNFa and CII antibody were suppressed by the treatment. CII specific T cell activation plays an important role in early stage of pathogenesis of RA. Non-TCR binding peptide yielded hyporesponsive in CII specific T cell activation.The CII 263-272 derived altered peptides with substitution of TCR binding residues are low or non-T cell binding, and are which were able to inhibit CII specific T cell activation. It suggested a new strategy of immunosuppresive therapy in RA.

Ⅱ型胶原(CⅡ)多肽通过其不同氨基酸的侧链，既能HLA-DRβ1分子形成复合物，又可与TCR岷希碳ぶ虏⌒訲细胞的活化，导致自身免疫反应的发生。以丙氨酸(ALa)及肝氨酸(GLy)替换CⅡ中与TCR结合的氨基酸，保留有HLA-DRβ1结合特性的氨基酸，则可形成HLA-DRβ1结合能力，但不被TCR识别的非CⅡ多肽。本课题将研究这种修饰型非CⅡ多肽结合HLA-DRβ1、抑制T细胞激活及自身免疫反应的作用。为抑制T细胞免疫异常介导的自身免疫病探索新的途径

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