Myers L K, Stuart J M, Seyer J M, Kang A H
Department of Pediatrics, University of Tennessee, Memphis.
J Exp Med. 1989 Dec 1;170(6):1999-2010. doi: 10.1084/jem.170.6.1999.
We have previously reported that collagen-induced arthritis can be suppressed by intravenous injection of native type II (CII) but not type I collagen. We have now identified denatured fragments of CII capable of suppressing collagen-induced arthritis and inducing tolerance. Purified CII was cleaved with cyanogen bromide (CB), and the major resulting peptides were isolated. Female DBA/1 mice were administered OVA, native CII, or one of the CB peptides, intravenously, before immunization with native CII, 6 wk after immunization, mice tolerized with CII and CB11 had a markedly lower incidence of arthritis compared with controls. There was a correlation between the overall antibody response and the incidence of arthritis. In addition, animals tolerized with either CII or CB11 had a decreased antibody response not only to CII, but also to each of the other CB peptides tested. To identify the epitope involved in suppression of arthritis, five synthetic peptides, 21-26 amino acids in length, corresponding to selected regions of CB11, were generated. Each of the peptides was injected intravenously into mice before immunization. Only one of these, CB11 122-147, was capable of suppressing arthritis. In addition, mice given the synthetic peptide CB11 122-147 neonatally were suppressed for arthritis and antibody responsiveness when immunized with CII at 8 wk of age. Thus, we have identified CB11 122-147 as an epitope of CII important in induction of tolerance and suppression of disease. Further experiments narrowing down the pivotal amino acids for the immunogenicity of this epitope and the role this epitope plays in induction and regulation of disease will enhance our understanding of how the immune response to collagen affects autoimmune arthritis.
我们之前曾报道，静脉注射天然II型胶原蛋白（CII）可抑制胶原诱导的关节炎，但I型胶原蛋白则无此作用。我们现已鉴定出能够抑制胶原诱导的关节炎并诱导耐受的CII变性片段。用溴化氰（CB）切割纯化的CII，并分离出主要产生的肽段。在以天然CII免疫前，给雌性DBA/1小鼠静脉注射卵清蛋白（OVA）、天然CII或其中一种CB肽段。免疫6周后，用CII和CB11诱导耐受的小鼠与对照组相比，关节炎发病率明显更低。总体抗体反应与关节炎发病率之间存在相关性。此外，用CII或CB11诱导耐受的动物不仅对CII的抗体反应降低，对所测试的其他每种CB肽段的抗体反应也降低。为了鉴定参与抑制关节炎的表位，合成了5种长度为21 - 26个氨基酸的合成肽段，它们对应于CB11的选定区域。在免疫前将每种肽段静脉注射到小鼠体内。其中只有一种，即CB11 122 - 147，能够抑制关节炎。此外，新生期给予合成肽CB11 122 - 147的小鼠在8周龄时用CII免疫后，关节炎和抗体反应性受到抑制。因此，我们已将CB11 122 - 147鉴定为CII的一个表位，它在诱导耐受和抑制疾病方面很重要。进一步的实验将缩小该表位免疫原性关键氨基酸的范围，以及该表位在疾病诱导和调节中所起的作用，这将增进我们对胶原免疫反应如何影响自身免疫性关节炎的理解。
