Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, The Netherlands.
Ann Rheum Dis. 2017 Aug;76(8):1449-1457. doi: 10.1136/annrheumdis-2016-210772. Epub 2017 Apr 25.
Over 50% of patients with rheumatoid arthritis (RA) harbour a variety of anti-modified protein antibodies (AMPA) against different post-translationally modified (PTM) proteins, including anti-carbamylated protein (anti-CarP) antibodies. At present, it is unknown how AMPA are generated and how autoreactive B cell responses against PTM proteins are induced. Here we studied whether PTM foreign antigens can breach B cell tolerance towards PTM self-proteins.
Serum reactivity towards five carbamylated proteins was determined for 160 patients with RA and 40 healthy individuals. Antibody cross-reactivity was studied by inhibition experiments. Mass spectrometry was performed to identify carbamylated self-proteins in human rheumatic joint tissue. Mice were immunised with carbamylated or non-modified (auto)antigens and analysed for autoantibody responses.
We show that anti-CarP antibodies in RA are highly cross-reactive towards multiple carbamylated proteins, including modified self-proteins and modified non-self-proteins. Studies in mice show that anti-CarP antibody responses recognising carbamylated self-proteins are induced by immunisation with carbamylated self-proteins and by immunisation with carbamylated proteins of non-self-origin. Similar to the data observed with sera from patients with RA, the murine anti-CarP antibody response was, both at the monoclonal level and the polyclonal level, highly cross-reactive towards multiple carbamylated proteins, including carbamylated self-proteins.
Self-reactive AMPA responses can be induced by exposure to foreign proteins containing PTM. These data show how autoreactive B cell responses against PTM self-proteins can be induced by exposure to PTM foreign proteins and provide new insights on the breach of autoreactive B cell tolerance.
超过50%的类风湿关节炎（RA）患者体内存在多种针对不同翻译后修饰（PTM）蛋白的抗修饰蛋白抗体（AMPA），包括抗氨甲酰化蛋白（抗CarP）抗体。目前，尚不清楚AMPA是如何产生的，以及针对PTM蛋白的自身反应性B细胞应答是如何被诱导的。在此，我们研究了PTM外来抗原是否会破坏B细胞对PTM自身蛋白的耐受性。
测定了160例RA患者和40名健康个体对五种氨甲酰化蛋白的血清反应性。通过抑制实验研究抗体交叉反应性。进行质谱分析以鉴定人类风湿性关节组织中的氨甲酰化自身蛋白。用氨甲酰化或未修饰的（自身）抗原免疫小鼠，并分析其自身抗体应答。
我们发现，RA患者体内的抗CarP抗体对多种氨甲酰化蛋白具有高度交叉反应性，包括修饰的自身蛋白和修饰的非自身蛋白。小鼠研究表明，识别氨甲酰化自身蛋白的抗CarP抗体应答可通过用氨甲酰化自身蛋白免疫以及用非自身来源的氨甲酰化蛋白免疫诱导产生。与RA患者血清中观察到的数据相似，小鼠抗CarP抗体应答在单克隆水平和多克隆水平上对多种氨甲酰化蛋白，包括氨甲酰化自身蛋白，都具有高度交叉反应性。
暴露于含有PTM的外来蛋白可诱导自身反应性AMPA应答。这些数据表明，暴露于PTM外来蛋白可如何诱导针对PTM自身蛋白的自身反应性B细胞应答，并为自身反应性B细胞耐受性的破坏提供了新的见解。
