Nygaard Tyler K, Borgogna Timothy R, Pallister Kyler B, Predtechenskaya Maria, Burroughs Owen S, Gao Annika, Lubick Evan G, Voyich Jovanka M
Department of Microbiology Cell Biology, Montana State University, Bozeman, MT 59718, USA.
Microorganisms. 2024 Aug 28;12(9):1782. doi: 10.3390/microorganisms12091782.
() is a prominent Gram-positive bacterial pathogen that expresses numerous cytotoxins known to target human polymorphonuclear leukocytes (PMNs or neutrophils). These include leukocidin G/H (LukGH, also known as LukAB), the Panton-Valentine leukocidin (PVL), γ-hemolysin A/B (HlgAB), γ-hemolysin B/C (HlgBC), leukocidin E/D (LukED), α-hemolysin (Hla), and the phenol-soluble modulin-α peptides (PSMα). However, the relative contribution of each of these cytotoxins in causing human PMN lysis is not clear. In this study, we used a library of cytotoxin deletion mutants in the clinically relevant methicillin-resistant (MRSA) isolate LAC (strain ST8:USA300) to determine the relative importance of each for causing human PMN lysis upon exposure to extracellular components as well as following phagocytosis. Using flow cytometry to examine plasma membrane permeability and assays quantifying lactose dehydrogenase release, we found that PVL was the dominant extracellular factor causing human PMN lysis produced by USA300. In contrast, LukGH was the most important cytotoxin causing human PMN lysis immediately following phagocytosis with contributions from the other bicomponent leukocidins only observed at later time points. These results not only clarify the relative importance of different USA300 cytotoxins for causing human PMN destruction but also demonstrate how two apparently redundant virulence factors play distinctive roles in promoting pathogenesis.
（某细菌）是一种著名的革兰氏阳性菌病原体，它表达多种已知靶向人类多形核白细胞（PMN或中性粒细胞）的细胞毒素。这些毒素包括杀白细胞素G/H（LukGH，也称为LukAB）、潘顿-瓦伦丁杀白细胞素（PVL）、γ-溶血素A/B（HlgAB）、γ-溶血素B/C（HlgBC）、杀白细胞素E/D（LukED）、α-溶血素（Hla）以及酚溶性调节素-α肽（PSMα）。然而，这些细胞毒素在导致人类PMN裂解中各自的相对作用尚不清楚。在本研究中，我们使用了临床相关的耐甲氧西林金黄色葡萄球菌（MRSA）分离株LAC（菌株ST8:USA300）中的细胞毒素缺失突变体文库，以确定每种毒素在暴露于细胞外成分以及吞噬后导致人类PMN裂解的相对重要性。通过流式细胞术检测质膜通透性以及定量检测乳糖脱氢酶释放的实验，我们发现PVL是USA300产生的导致人类PMN裂解的主要细胞外因子。相比之下，LukGH是吞噬后立即导致人类PMN裂解的最重要细胞毒素，其他双组分杀白细胞素的作用仅在较晚时间点才观察到。这些结果不仅阐明了不同USA300细胞毒素在导致人类PMN破坏中的相对重要性，还证明了两种明显冗余的毒力因子在促进发病机制中如何发挥独特作用。
