Dipartimento di Biologia Cellulare e Neuroscienze, Istituto Superiore di Sanità, Roma, Italy.
Clin Exp Immunol. 2013 Sep;173(3):419-29. doi: 10.1111/cei.12135.
Rheumatic heart disease (RHD) is characterized by the presence of anti-streptococcal group A antibodies and anti-endothelial cell antibodies (AECA). Molecular mimicry between streptococcal antigens and self proteins is a hallmark of the pathogenesis of rheumatic fever. We aimed to identify, in RHD patients, autoantibodies specific to endothelial autoantigens cross-reactive with streptococcal proteins and to evaluate their role in inducing endothelial damage. We used an immunoproteomic approach with endothelial cell-surface membrane proteins in order to identify autoantigens recognized by AECA of 140 RHD patients. Cross-reactivity of purified antibodies with streptococcal proteins was analysed. Homologous peptides recognized by serum cross-reactive antibodies were found through comparing the amino acid sequence of streptococcal antigens with human antigens. To investigate interleukin (IL)-1R-associated kinase (IRAK1) and nuclear factor-κB (NF-κB) activation, we performed a Western blot analysis of whole extracts proteins from unstimulated or stimulated human microvascular cardiac endothelial cells (HMVEC-C). Adhesion molecule expression and release of proinflammatory cytokines and growth factors were studied by multiplex bead based immunoassay kits. We observed anti-vimentin antibodies in sera from 49% RHD AECA-positive patients. Cross-reactivity of purified anti-vimentin antibodies with heat shock protein (HSP)70 and streptopain streptococcal proteins was shown. Comparing the amino acid sequence of streptococcal HSP70 and streptopain with human vimentin, we found two homologous peptides recognized by serum cross-reactive antibodies. These antibodies were able to stimulate HMVEC-C inducing IRAK and NF-κB activation, adhesion molecule expression and release of proinflammatory cytokines and growth factors. In conclusion, streptococcal-vimentin cross-reactive antibodies were able to activate microvascular cardiac endothelium by amplifying the inflammatory response in RHD.
风湿性心脏病（Rheumatic heart disease，RHD）的特征是存在抗链球菌 A 群抗体和抗内皮细胞抗体（AECA）。链球菌抗原与自身蛋白之间的分子模拟是风湿热发病机制的标志。我们旨在鉴定 RHD 患者中针对与链球菌蛋白发生交叉反应的内皮自身抗原的自身抗体，并评估其在诱导内皮损伤中的作用。我们使用免疫蛋白质组学方法，用内皮细胞表面膜蛋白鉴定 140 例 RHD 患者的 AECA 特异性自身抗原。分析纯化抗体与链球菌蛋白的交叉反应性。通过比较链球菌抗原与人类抗原的氨基酸序列，发现了与血清交叉反应性抗体反应的同源肽。为了研究白细胞介素（IL）-1 受体相关激酶（IRAK1）和核因子-κB（NF-κB）的激活，我们对未刺激或刺激的人微血管心脏内皮细胞（HMVEC-C）的全细胞提取物蛋白进行了 Western blot 分析。通过多重珠基免疫分析试剂盒研究粘附分子的表达和促炎细胞因子和生长因子的释放。我们观察到 49%的 RHD AECA 阳性患者血清中存在抗波形蛋白抗体。纯化的抗波形蛋白抗体与热休克蛋白（HSP）70 和链球菌蛋白酶的交叉反应性。比较链球菌 HSP70 和链球菌蛋白酶与人类波形蛋白的氨基酸序列，我们发现了两个被血清交叉反应性抗体识别的同源肽。这些抗体能够刺激 HMVEC-C，诱导 IRAK 和 NF-κB 激活、粘附分子表达和促炎细胞因子和生长因子的释放。总之，链球菌-波形蛋白交叉反应性抗体能够通过放大 RHD 中的炎症反应来激活微血管心脏内皮细胞。
