Division of Infectious Diseases, Department of Medicine, New York University School of Medicine, New York, NY 10016.
Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110.
Proc Natl Acad Sci U S A. 2017 Oct 10;114(41):E8711-E8720. doi: 10.1073/pnas.1707792114. Epub 2017 Sep 27.
' success as a pathogen comes from its ability to evade degradation by macrophages. Normally macrophages clear microorganisms that activate pathogen-recognition receptors (PRRs) through a lysosomal-trafficking pathway called "LC3-associated phagocytosis" (LAP). Although activates numerous PRRs, for reasons that are poorly understood LAP does not substantially contribute to control. LAP depends upon reactive oxygen species (ROS) generated by NADPH oxidase, but fails to generate a robust oxidative response. Here, we show that CpsA, a LytR-CpsA-Psr (LCP) domain-containing protein, is required for to evade killing by NADPH oxidase and LAP. Unlike phagosomes containing wild-type bacilli, phagosomes containing the Δ mutant recruited NADPH oxidase, produced ROS, associated with LC3, and matured into antibacterial lysosomes. Moreover, CpsA was sufficient to impair NADPH oxidase recruitment to fungal particles that are normally cleared by LAP. Intracellular survival of the Δ mutant was largely restored in macrophages missing LAP components (, , , , , or ) but not in macrophages defective in a related, canonical autophagy pathway (, , or ). The Δ mutant was highly impaired in vivo, and its growth was partially restored in mice deficient in NADPH oxidase, , or , demonstrating that CpsA makes a significant contribution to the resistance of to NADPH oxidase and LC3 trafficking in vivo. Overall, our findings reveal an essential role of CpsA in innate immune evasion and suggest that LCP proteins have functions beyond their previously known role in cell-wall metabolism.
作为病原体的成功来自于其逃避巨噬细胞降解的能力。通常情况下,巨噬细胞通过一种称为“LC3 相关吞噬作用”(LAP)的溶酶体运输途径清除激活病原体识别受体(PRRs)的微生物。尽管 激活了许多 PRRs,但由于原因尚不清楚,LAP 并没有对 控制做出实质性贡献。LAP 依赖于 NADPH 氧化酶产生的活性氧(ROS),但 未能产生强烈的氧化反应。在这里,我们表明,LytR-CpsA-Psr(LCP)结构域蛋白 CpsA 是 逃避 NADPH 氧化酶和 LAP 杀伤所必需的。与含有野生型杆菌的吞噬体不同,含有 Δ突变体的吞噬体招募 NADPH 氧化酶,产生 ROS,与 LC3 结合,并成熟为具有抗菌作用的溶酶体。此外,CpsA 足以损害 NADPH 氧化酶向通常通过 LAP 清除的真菌颗粒的募集。在缺失 LAP 成分(、、、、或)的巨噬细胞中,Δ突变体的细胞内存活能力在很大程度上得到恢复,但在与相关的经典自噬途径(、或)缺陷的巨噬细胞中则不然。Δ突变体在体内的生长受到严重抑制,在缺乏 NADPH 氧化酶、、或的小鼠中其生长部分得到恢复,这表明 CpsA 为 抵抗 NADPH 氧化酶和 LC3 在体内的运输做出了重要贡献。总的来说,我们的研究结果揭示了 CpsA 在先天免疫逃避中的重要作用,并表明 LCP 蛋白除了其在细胞壁代谢中已知的作用之外,还有其他功能。
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