Sibelius U, Schulz E C, Rose F, Hattar K, Jacobs T, Weiss S, Chakraborty T, Seeger W, Grimminger F
Department of Internal Medicine, Justus-Liebig-University, Giessen, Germany.
Infect Immun. 1999 Mar;67(3):1125-30. doi: 10.1128/IAI.67.3.1125-1130.1999.
Polymorphonuclear leukocytes (PMN) are essential for resolution of infections with Listeria monocytogenes. The present study investigated the role of the listerial exotoxins listeriolysin (LLO) and phosphatidylinositol-specific phospholipase C (PlcA) in human neutrophil activation. Different Listeria strains, mutated in individual virulence genes, as well as purified LLO were used. Coincubation of human neutrophils with wild-type L. monocytogenes provoked PMN activation, occurring independently of phagocytosis events, with concomitant elastase secretion, leukotriene generation, platelet-activating factor (PAF) synthesis, respiratory burst, and enhanced phosphoinositide hydrolysis. Degranulation and leukotriene formation were noted to be solely dependent on LLO expression, as these features were absent when the LLO-defective mutant EGD- and the avirulent strain L. innocua were used. These effects were fully reproduced by a recombinant L. innocua strain expressing LLO (INN+) and by the purified LLO molecule. LLO secretion was also required for PAF synthesis. However, wild-type L. monocytogenes was more potent in eliciting PAF formation than mutants expressing LLO, suggesting the involvement of additional virulence factors. This was even more obvious for phosphoinositide hydrolysis and respiratory burst: these events were provoked not only by INN+ but also by the LLO-defective mutant EGD- and by a recombinant L. innocua strain producing listerial PlcA. We conclude that human neutrophils react to extracellularly provided listerial exotoxins by rapid cell activation. Listeriolysin is centrally involved in triggering degranulation and lipid mediator generation, and further virulence factors such as PlcA apparently contribute to trigger neutrophil phosphoinositide hydrolysis and respiratory burst. In this way, listerial exotoxins may influence the host defense against infections with L. monocytogenes.
多形核白细胞（PMN）对于清除单核细胞增生李斯特菌感染至关重要。本研究调查了李斯特菌外毒素溶细胞素（LLO）和磷脂酰肌醇特异性磷脂酶C（PlcA）在人类中性粒细胞激活中的作用。使用了在单个毒力基因中发生突变的不同李斯特菌菌株以及纯化的LLO。人类中性粒细胞与野生型单核细胞增生李斯特菌共同孵育可引发PMN激活，这一过程独立于吞噬作用事件，同时伴有弹性蛋白酶分泌、白三烯生成、血小板活化因子（PAF）合成、呼吸爆发以及增强的磷酸肌醇水解。观察到脱颗粒和白三烯形成仅依赖于LLO表达，因为当使用LLO缺陷型突变体EGD - 和无毒菌株无害李斯特菌时，这些特征不存在。表达LLO的重组无害李斯特菌菌株（INN +）和纯化的LLO分子完全重现了这些效应。PAF合成也需要LLO分泌。然而，野生型单核细胞增生李斯特菌在引发PAF形成方面比表达LLO的突变体更有效，这表明还有其他毒力因子参与其中。对于磷酸肌醇水解和呼吸爆发而言，这种情况更为明显：这些事件不仅由INN +引发，还由LLO缺陷型突变体EGD - 和产生李斯特菌PlcA的重组无害李斯特菌菌株引发。我们得出结论，人类中性粒细胞通过快速细胞激活对细胞外提供的李斯特菌外毒素作出反应。溶细胞素在触发脱颗粒和脂质介质生成中起核心作用，而其他毒力因子如PlcA显然有助于触发中性粒细胞磷酸肌醇水解和呼吸爆发。通过这种方式，李斯特菌外毒素可能会影响宿主对单核细胞增生李斯特菌感染的防御。
