Sakurai Yoshihiko, Brand David D, Tang Bo, Rosloniec Edward F, Stuart John M, Kang Andrew H, Myers Linda K
Department of Medicine, University of Tennessee, 956 Court Avenue, Memphis, TN 38163, USA.
Arthritis Res Ther. 2006;8(5):R150. doi: 10.1186/ar2043.
Rheumatoid arthritis (RA) is an autoimmune disease associated with the recognition of self proteins secluded in diarthrodial joints. We have previously established that mice transgenic for the human DR genes associated with RA are susceptible to collagen-induced arthritis (CIA) and we have identified a determinant of type II collagen (CII(263-270)) that triggers T-cell immune responses in these mice. We have also determined that an analog of CII(263-270) would suppress disease in DR1 transgenic mice. Because the immunodominant determinant is the same for both DR1 transgenic and DR4 transgenic mice, we attempted to determine whether the analog peptide that was suppressive in DR1 transgenic mice would also be effective in suppressing CIA in DR4 transgenic mice. We treated DR4 transgenic mice with two analog peptides of CII that contained substitutions in the core of the immunodominant determinant: CII(256-276) (F263N, E266D) and CII(256-270) (F263N, E266A). Mice were observed for CIA, and T-cell proliferative responses were determined. Either peptide administered at the time of immunization with CII significantly downregulated arthritis. Binding studies demonstrated that replacement of the phenylalanine residue in position 263 of the CII peptide with asparagine significantly decreased the affinity of the peptide for the DR4 molecule. In contrast, replacement of the glutamic acid residue in position 266 with aspartic acid or with alanine had differing results. Aspartic acid reduced the affinity (35-fold) whereas alanine did not. Both peptides were capable of suppressing CIA. With the use of either peptide, CII(256-276) (F263N, E266D) or CII(256-270) (F263N, E266A), the modulation of CIA was associated with an increase in T-cell secretion of IL-4 together with a decrease in IFN-gamma. We have identified two analog peptides that are potent suppressors of CIA in DR4 transgenic mice. These experiments represent the first description of an analog peptide of CII recognized by T cells in the context of HLA-DR4 that can suppress autoimmune arthritis.
类风湿性关节炎（RA）是一种自身免疫性疾病，与识别存在于滑膜关节中的自身蛋白有关。我们之前已经证实，携带与RA相关的人类DR基因的转基因小鼠易患胶原诱导的关节炎（CIA），并且我们已经鉴定出一种II型胶原蛋白（CII(263 - 270)）的决定簇，它能在这些小鼠中触发T细胞免疫反应。我们还确定，CII(263 - 270)的类似物能抑制DR1转基因小鼠的疾病。由于DR1转基因小鼠和DR4转基因小鼠的免疫显性决定簇相同，我们试图确定在DR1转基因小鼠中具有抑制作用的类似肽在DR4转基因小鼠中是否也能有效抑制CIA。我们用两种CII类似肽处理DR4转基因小鼠，这两种肽在免疫显性决定簇的核心区域有替换：CII(256 - 276)（F263N，E266D）和CII(256 - 270)（F263N，E266A）。观察小鼠的CIA情况，并测定T细胞增殖反应。在注射CII时给予任何一种肽都能显著下调关节炎。结合研究表明，将CII肽第263位的苯丙氨酸残基替换为天冬酰胺会显著降低该肽与DR4分子的亲和力。相比之下，将第266位的谷氨酸残基替换为天冬氨酸或丙氨酸会有不同结果。天冬氨酸降低了亲和力（35倍），而丙氨酸则没有。两种肽都能够抑制CIA。使用CII(256 - 276)（F263N，E266D）或CII(256 - 270)（F263N，E266A）这两种肽中的任何一种，CIA的调节都与T细胞分泌IL - 4增加以及IFN - γ减少有关。我们已经鉴定出两种类似肽，它们是DR4转基因小鼠中CIA的有效抑制剂。这些实验首次描述了在HLA - DR4背景下被T细胞识别的CII类似肽，它能够抑制自身免疫性关节炎。
