Khmaladze Ia, Saxena Amit, Nandakumar Kutty Selva, Holmdahl Rikard
Medical Inflammation Research, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Unit of Dermatology, Department of Medicine, Karolinska Institutet, Stockholm, Sweden.
Eur J Immunol. 2015 Aug;45(8):2243-51. doi: 10.1002/eji.201545518. Epub 2015 Jun 3.
Autoantibody-mediated inflammation contributes to the development of rheumatoid arthritis (RA), and anti-type II collagen (CII) antibodies are present in the serum, synovial fluid, and cartilage of RA patients. We had previously generated and characterized knock-in mice expressing a germline-encoded, CII-specific IgH (B10Q.ACB), which demonstrated positive selection of self-reactive B cells. Here, we show that despite the spontaneous production of CII-specific autoantibodies, B10Q.ACB mice are protected from collagen-induced arthritis. Introducing a mutation in the Ncf1 gene, leading to ROS deficiency, breaks this strong arthritis resistance. Disease development in Ncf1-mutated B10Q.ACB mice is associated with an enhanced germinal center formation but without somatic mutations of the auto-reactive B cells, increased T-cell responses and intramolecular epitope-spreading. Thus, ROS-mediated B-cell tolerance to a self-antigen could operate by limiting the expansion of the auto-reactive B-cell repertoire, which has important implications for the understanding of epitope spreading phenomena in rheumatoid arthritis and other autoimmune diseases.
自身抗体介导的炎症促进类风湿性关节炎（RA）的发展，RA患者的血清、滑液和软骨中存在抗II型胶原（CII）抗体。我们之前已构建并鉴定了表达种系编码的CII特异性IgH的敲入小鼠（B10Q.ACB），其显示出对自身反应性B细胞的阳性选择。在此，我们表明尽管B10Q.ACB小鼠自发产生CII特异性自身抗体，但它们对胶原诱导的关节炎具有抵抗力。在Ncf1基因中引入导致ROS缺乏的突变会打破这种强大的关节炎抗性。Ncf1突变的B10Q.ACB小鼠的疾病发展与生发中心形成增强有关，但自身反应性B细胞无体细胞突变，T细胞反应增加和分子内表位扩展。因此，ROS介导的B细胞对自身抗原的耐受性可能通过限制自身反应性B细胞库的扩增来发挥作用，这对理解类风湿性关节炎和其他自身免疫性疾病中的表位扩展现象具有重要意义。
