Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
PLoS One. 2010 Jan 15;5(1):e8734. doi: 10.1371/journal.pone.0008734.
The complex pathology of B. pertussis infection is due to multiple virulence factors having disparate effects on different cell types. We focused our investigation on the ability of B. pertussis to modulate host immunity, in particular on the role played by adenylate cyclase toxin (CyaA), an important virulence factor of B. pertussis. As a tool, we used human monocyte derived dendritic cells (MDDC), an ex vivo model useful for the evaluation of the regulatory potential of DC on T cell immune responses. The work compared MDDC functions after encounter with wild-type B. pertussis (BpWT) or a mutant lacking CyaA (BpCyaA-), or the BpCyaA- strain supplemented with either the fully functional CyaA or a derivative, CyaA*, lacking adenylate cyclase activity. As a first step, MDDC maturation, cytokine production, and modulation of T helper cell polarization were evaluated. As a second step, engagement of Toll-like receptors (TLR) 2 and TLR4 by B. pertussis and the signaling events connected to this were analyzed. These approaches allowed us to demonstrate that CyaA expressed by B. pertussis strongly interferes with DC functions, by reducing the expression of phenotypic markers and immunomodulatory cytokines, and blocking IL-12p70 production. B. pertussis-treated MDDC promoted a mixed Th1/Th17 polarization, and the activity of CyaA altered the Th1/Th17 balance, enhancing Th17 and limiting Th1 expansion. We also demonstrated that Th1 effectors are induced by B. pertussis-MDDC in the absence of IL-12p70 through an ERK1/2 dependent mechanism, and that p38 MAPK is essential for MDDC-driven Th17 expansion. The data suggest that CyaA mediates an escape strategy for the bacterium, since it reduces Th1 immunity and increases Th17 responses thought to be responsible, when the response is exacerbated, for enhanced lung inflammation and injury.
百日咳博德特氏菌感染的复杂病理学是由于多种毒力因子对不同细胞类型产生不同的影响。我们将研究重点放在百日咳博德特氏菌对宿主免疫的调节能力上，特别是在腺苷酸环化酶毒素（CyaA）的作用上，CyaA 是百日咳博德特氏菌的一个重要毒力因子。我们使用人类单核细胞来源的树突状细胞（MDDC）作为工具，MDDC 是一种体外模型，可用于评估 DC 对 T 细胞免疫反应的调节潜力。这项工作比较了野生型百日咳博德特氏菌（BpWT）或缺乏 CyaA 的突变体（BpCyaA-）或补充了完全功能的 CyaA 或缺乏腺苷酸环化酶活性的衍生物 CyaA*的 BpCyaA-菌株与 MDDC 相互作用后的功能。作为第一步，评估了 MDDC 的成熟、细胞因子产生和 T 辅助细胞极化的调节。作为第二步，分析了百日咳博德特氏菌对 Toll 样受体（TLR）2 和 TLR4 的作用以及与此相关的信号事件。这些方法使我们能够证明百日咳博德特氏菌表达的 CyaA 强烈干扰了 DC 的功能，降低了表型标志物和免疫调节细胞因子的表达，并阻断了 IL-12p70 的产生。百日咳博德特氏菌处理的 MDDC 促进了混合 Th1/Th17 极化，而 CyaA 的活性改变了 Th1/Th17 的平衡，增强了 Th17 并限制了 Th1 的扩增。我们还证明了在缺乏 IL-12p70 的情况下，B. pertussis-MDDC 通过 ERK1/2 依赖性机制诱导 Th1 效应物，而 p38 MAPK 对 MDDC 驱动的 Th17 扩增是必不可少的。数据表明，CyaA 介导了细菌的逃避策略，因为它降低了 Th1 免疫，增加了 Th17 反应，当反应加剧时，被认为是增强肺部炎症和损伤的原因。
