Monach Paul A, Hueber Wolfgang, Kessler Benedikt, Tomooka Beren H, BenBarak Maya, Simmons Barry P, Wright John, Thornhill Thomas S, Monestier Marc, Ploegh Hidde, Robinson William H, Mathis Diane, Benoist Christophe
Section on Immunology and Immunogenetics, The Joslin Diabetes Center, Boston, Massachusetts, USA.
Proc Natl Acad Sci U S A. 2009 Sep 15;106(37):15867-72. doi: 10.1073/pnas.0908032106. Epub 2009 Aug 31.
Deposits of Ig and complement are abundant in affected joints of patients with rheumatoid arthritis (RA) and in animal models of RA in which antibodies are demonstrably pathogenic. To identify molecular targets of the Igs deposited in arthritic joints, which may activate local inflammation, we used a combination of mass spectrometry (MS) and protein microarrays. Immune complexes were affinity-purified from surgically removed joint tissues of 26 RA and osteoarthritis (OA) patients. Proteins complexed with IgG were identified by proteomic analysis using tandem MS. A striking diversity of components of the extracellular matrix, and some intracellular components, copurified specifically with IgG from RA and OA tissues. A smaller set of autoantigens was observed only in RA eluates. In complementary experiments, IgG fractions purified from joint immune complexes were tested on protein microarrays against a range of candidate autoantigens. These Igs bound a diverse subset of proteins and peptides from synovium and cartilage, different from that bound by normal serum Ig. One type of intracellular protein detected specifically in RA joints (histones H2A/B) was validated by immunohistology and found to be deposited on the cartilage surface of RA but not OA joints. Thus, autoantibodies to many determinants (whether deposited as "neoantigens" or normal constituents of the extracellular matrix) have the potential to contribute to arthritic inflammation.
免疫球蛋白（Ig）和补体的沉积物在类风湿关节炎（RA）患者的受累关节以及RA动物模型中大量存在，在这些动物模型中抗体具有明显的致病性。为了确定沉积在关节炎关节中的Ig的分子靶点，这些靶点可能激活局部炎症，我们联合使用了质谱（MS）和蛋白质微阵列技术。从26例RA和骨关节炎（OA）患者手术切除的关节组织中亲和纯化免疫复合物。通过串联MS的蛋白质组学分析鉴定与IgG复合的蛋白质。细胞外基质的多种成分以及一些细胞内成分与来自RA和OA组织的IgG特异性共纯化。仅在RA洗脱液中观察到一小部分自身抗原。在补充实验中，从关节免疫复合物中纯化的IgG组分在蛋白质微阵列上针对一系列候选自身抗原进行测试。这些Ig与来自滑膜和软骨的多种蛋白质和肽结合，与正常血清Ig结合的不同。一种在RA关节中特异性检测到的细胞内蛋白质（组蛋白H2A/B）通过免疫组织学得到验证，并且发现其沉积在RA而非OA关节的软骨表面。因此，针对许多决定簇的自身抗体（无论作为“新抗原”沉积还是细胞外基质的正常成分）都有可能导致关节炎炎症。
