Autoantibody modulation of cartilage turnover in rheumatoid arthritis

摘要 类风湿关节炎(RA)影响着世界人口的0.5%-1%。RA以自身抗体为特征 产生滑膜炎症和肿胀，破坏软骨和骨骼，导致 进行性残疾。目前尚不清楚早期的反应性，如抗瓜氨酸蛋白抗体 (ACPAs)和类风湿因子(RF)，是致病的、调节的或只是继发性现象而不是 与发病机制有关。一种可能的情况是当自身免疫反应切换时发生类风湿关节炎 靶向关节，特别是软骨内或附着在软骨上的蛋白质。II型胶原是人体内的主要蛋白质 关节软骨，也是大多数已知的可引发关节炎的自身抗体的靶标。我们有 已有证据表明，对II型胶原的自身免疫反应通常发生在类风湿关节炎患者中，并可能 是引发这种疾病的主要机制之一。这里描述的研究计划 主要介绍基质金属蛋白酶13(MMP13)对II型胶原蛋白的抗体调控作用， 在关节炎期间导致关节软骨退化的主要胶原酶。我们的假设是 下面是。在正常情况下，基质金属蛋白酶-13首先在Gly775-Leu776键上裂解II型胶原， 随后进一步消化胶原蛋白碎片。在类风湿性关节炎中，抗II型胶原的自身抗体抑制 基质金属蛋白酶-13在不同阶段发挥作用，导致胶原蛋白片段的稳定产生。胶原蛋白 片段可以激活免疫系统，使其更具致病性或调节性，以及修改 软骨细胞的功能，从而在类风湿性关节炎的启动中发挥作用。这代表了一种新的范例 类风湿关节炎的发病和进展。为了探索这一假设，具体目的是检验(1)的影响 精氨酸残基在基质金属蛋白酶-13加工II型胶原中的翻译后修饰，(2)RA 抗基质金属蛋白酶-13的抗体处理II型胶原和随后的片段产生，以及(3)基质金属蛋白酶-13 衍生的II型胶原片段对软骨细胞活性和在体小鼠RA模型中的作用。这些目标 将结合多种策略，包括酶动力学分析三螺旋的水解 结构、II型胶原片段的蛋白质组学分析、增殖、qRT-PCR、FACS和 软骨细胞的蛋白质印迹分析。本研究将为揭示特定的抗-HBs的作用提供新的线索。 胶原抗体在类风湿关节炎进展中的作用

ABSTRACT Rheumatoid arthritis (RA) affects 0.5-1% of the world population. RA is characterized by autoantibody production, synovial inflammation and swelling, and destruction of cartilage and bone resulting in progressive disability. It is not known whether early reactivities, such as anti-citrullinated protein antibodies (ACPAs) and rheumatoid factor (RF), are pathogenic, regulatory, or only a secondary phenomenon not related to the pathogenesis. A possible scenario is that RA occurs when the autoimmune response switches to targeting joints, in particular proteins within or adhering to cartilage. Type II collagen the major protein in joint cartilage and is also the target of most known autoantibodies that can induce arthritis. We have obtained evidence that autoimmune reactivities to type II collagen commonly occur in RA patients and may be one of the major mechanisms whereby the disease is initiated. The research plan described herein focuses on antibody modulation of type II collagen processing by matrix metalloproteinase 13 (MMP-13), the main collagenase responsible for degradation of articular cartilage during arthritis. Our hypothesis is as follows. Under normal circumstances, MMP-13 cleaves type II collagen initially at the Gly775-Leu776 bond, followed by further digestion of collagen fragments. In RA, autoantibodies to type II collagen inhibit the action of MMP-13 at different stages, resulting in the stable production of collagen fragments. The collagen fragments could activate the immune system to be more pathogenic or regulatory as well as modify chondrocyte functions, and thereby play a role in the initiation of RA. This represents a novel paradigm for RA onset and progression. To explore this hypothesis, the specific aims are to examine the effects of (1) posttranslational modification of Arg residues to citrulline on MMP-13 processing of type II collagen, (2) RA antibodies on MMP-13 processing of type II collagen and subsequent fragment production, and (3) MMP-13 derived type II collagen fragments on chondrocyte activity and in in vivo mouse models of RA. These aims will incorporate a variety of strategies, including enzyme kinetic analysis of hydrolysis of triple-helical structures, proteomics analysis of type II collagen fragments, and proliferation, qRT-PCR, FACS, and western blot analysis of chondrocytes. The present study will shed new light on the roles of specific anti- collagen antibodies in RA progression.