Bulut Yonca, Faure Emmanuelle, Thomas Lisa, Karahashi Hisae, Michelsen Kathrin S, Equils Ozlem, Morrison Sandra G, Morrison Richard P, Arditi Moshe
Division of Pediatric Critical Care, Steven Spielberg Pediatric Research Center Cedars-Sinai Medical Center, University of California-Los Angeles School of Medicine, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA.
J Immunol. 2002 Feb 1;168(3):1435-40. doi: 10.4049/jimmunol.168.3.1435.
Active inflammation and NF-kappaB activation contribute fundamentally to atherogenesis and plaque disruption. Accumulating evidence has implicated specific infectious agents including Chlamydia pneumoniae in the progression of atherogenesis. Chlamydial heat shock protein 60 (cHSP60) has been implicated in the induction of deleterious immune responses in human chlamydial infections and has been found to colocalize with infiltrating macrophages in atheroma lesions. cHSP60 might stimulate, enhance, and maintain innate immune and inflammatory responses and contribute to atherogenesis. In this study, we investigated the signaling mechanism of cHSP60. Recombinant cHSP60 rapidly activated NF-kappaB in human microvascular endothelial cells (EC) and in mouse macrophages, and induced human IL-8 promoter activity in EC. The inflammatory effect of cHSP60 was heat labile, thus excluding a role of contaminating LPS, and was blocked by specific anti-chlamydial HSP60 mAb. In human vascular EC which express Toll-like receptor 4 (TLR4) mRNA and protein, nonsignaling TLR4 constructs that act as dominant negative blocked cHSP60-mediated NF-kappaB activation. Furthermore, an anti-TLR4 Ab abolished cHSP60-induced cellular activation, whereas a control Ab had no effect. In 293 cells, cHSP60-mediated NF-kappaB activation required both TLR4 and MD2. A dominant-negative MyD88 construct also inhibited cHSP60-induced NF-kappaB activation. Collectively, our results indicate that cHSP60 is a potent inducer of vascular EC and macrophage inflammatory responses, which are very relevant to atherogenesis. The inflammatory effects are mediated through the innate immune receptor complex TLR4-MD2 and proceeds via the MyD88-dependent signaling pathway. These findings may help elucidate the mechanisms by which chronic asymptomatic chlamydial infection contribute to atherogenesis.
活动性炎症和核因子κB（NF-κB）激活在动脉粥样硬化形成和斑块破裂过程中起着根本性作用。越来越多的证据表明，包括肺炎衣原体在内的特定感染因子与动脉粥样硬化的进展有关。衣原体热休克蛋白60（cHSP60）与人类衣原体感染中有害免疫反应的诱导有关，并且已发现其与动脉粥样硬化病变中浸润的巨噬细胞共定位。cHSP60可能刺激、增强和维持先天性免疫和炎症反应，并促进动脉粥样硬化的发生。在本研究中，我们调查了cHSP60的信号传导机制。重组cHSP60可在人微血管内皮细胞（EC）和小鼠巨噬细胞中快速激活NF-κB，并诱导EC中人类白细胞介素8（IL-8）启动子活性。cHSP60的炎症作用对热不稳定，因此排除了污染脂多糖（LPS）的作用，并且被特异性抗衣原体HSP60单克隆抗体（mAb）阻断。在表达Toll样受体4（TLR4）mRNA和蛋白的人血管EC中，作为显性阴性的无信号TLR4构建体可阻断cHSP60介导的NF-κB激活。此外，抗TLR4抗体消除了cHSP60诱导的细胞激活，而对照抗体则无此作用。在293细胞中，cHSP60介导的NF-κB激活需要TLR4和髓样分化蛋白2（MD2）两者。显性阴性髓样分化因子88（MyD88）构建体也抑制cHSP60诱导的NF-κB激活。总体而言，我们的结果表明，cHSP60是血管EC和巨噬细胞炎症反应的有效诱导剂，这与动脉粥样硬化的发生密切相关。炎症作用是通过先天性免疫受体复合物TLR4-MD2介导的，并通过MyD88依赖性信号通路进行。这些发现可能有助于阐明慢性无症状衣原体感染促进动脉粥样硬化发生的机制。
