Department of Microbiology, New York University School of Medicine, New York, NY, USA.
Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY, USA.
Nature. 2020 Mar;579(7798):260-264. doi: 10.1038/s41586-020-2066-6. Epub 2020 Mar 4.
The production of pore-forming toxins that disrupt the plasma membrane of host cells is a common virulence strategy for bacterial pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). It is unclear, however, whether host species possess innate immune mechanisms that can neutralize pore-forming toxins during infection. We previously showed that the autophagy protein ATG16L1 is necessary for protection against MRSA strains encoding α-toxin-a pore-forming toxin that binds the metalloprotease ADAM10 on the surface of a broad range of target cells and tissues. Autophagy typically involves the targeting of cytosolic material to the lysosome for degradation. Here we demonstrate that ATG16L1 and other ATG proteins mediate protection against α-toxin through the release of ADAM10 on exosomes-extracellular vesicles of endosomal origin. Bacterial DNA and CpG DNA induce the secretion of ADAM10-bearing exosomes from human cells as well as in mice. Transferred exosomes protect host cells in vitro by serving as scavengers that can bind multiple toxins, and improve the survival of mice infected with MRSA in vivo. These findings indicate that ATG proteins mediate a previously unknown form of defence in response to infection, facilitating the release of exosomes that serve as decoys for bacterially produced toxins.
形成孔的毒素破坏宿主细胞的质膜是耐甲氧西林金黄色葡萄球菌(MRSA)等细菌病原体的常见毒力策略。然而,目前尚不清楚宿主物种是否具有先天免疫机制,可以在感染过程中中和形成孔的毒素。我们之前曾表明,自噬蛋白 ATG16L1 是针对编码α-毒素的 MRSA 菌株的保护所必需的,α-毒素是一种形成孔的毒素,可结合广泛的靶细胞和组织表面的金属蛋白酶 ADAM10。自噬通常涉及将细胞质物质靶向溶酶体进行降解。在这里,我们证明 ATG16L1 和其他 ATG 蛋白通过外泌体(源自内体的细胞外囊泡)释放 ADAM10 来介导对α-毒素的保护。细菌 DNA 和 CpG DNA 诱导人细胞以及小鼠中携带 ADAM10 的外泌体的分泌。转移的外泌体通过充当可以结合多种毒素的清除剂来保护体外宿主细胞,并改善体内感染 MRSA 的小鼠的存活率。这些发现表明,ATG 蛋白介导了一种以前未知的防御形式,以响应感染,促进了作为细菌产生的毒素诱饵的外泌体的释放。