Laboratorio de Fisiología de los Procesos Inflamatorios, Instituto de Medicina Experimental (IMEX)-CONICET/Academia Nacional de Medicina, CABA, Argentina.
Servicio de Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, ANLIS 'Dr Carlos G. Malbrán', CABA, Argentina.
J Leukoc Biol. 2021 Jan;109(1):245-256. doi: 10.1002/JLB.4MA0620-099R. Epub 2020 Jul 8.
One of the main bactericidal mechanisms of polymorphonuclear neutrophils (PMN) is the release of neutrophil extracellular traps (NETs), which capture and destroy pathogens. Klebsiella pneumoniae (Kpn) producer of carbapenemase (KPC) and belonging to the sequence type 258 (ST258), is a hyper epidemic clone that causes a large number of infections worldwide associated with high persistence and mortality. It is necessary to investigate the interaction of Kpn KPC with the immune system to improve prevention and treatment of infections mediated by this bacterium. Based on the hypothesis that Kpn is able to subvert PMN-mediated death, the aim was to assess whether Kpn KPC ST258 could modulate the bactericidal response of PMN, focusing on NETs formation, compared to another opportunistic pathogen, as Escherichia coli (Eco). The results showed that the release of NETs was absent when PMN were challenged with Kpn KPC, while Eco was a strong inducer of NETosis. Moreover, Kpn KPC was able to inhibit NETosis induced by Eco. The inhibition of Kpn KPC-mediated NETs formation still occurred in spite of exogenous addition of hydrogen peroxide (H O ), did not involve bacterial-released soluble factors or cell wall components, and was dependent on bacterial viability. Moreover, when degranulation was investigated, we found that Kpn KPC affected only the mobilization of primary granules, which harbor the proteins with more potent bactericidal properties and those related to NETosis. In conclusion, Kpn KPC ST258 effectively managed to evade the PMN response by inhibiting the release of NETs, and primary granule mobilization.
中性粒细胞（PMN）的主要杀菌机制之一是释放中性粒细胞胞外陷阱（NETs），它可以捕获和破坏病原体。产碳青霉烯酶（KPC）的肺炎克雷伯菌（Kpn）属于序列型 258（ST258），是一种超级流行克隆，导致全球大量感染，具有高持久性和高死亡率。有必要研究 Kpn 与免疫系统的相互作用，以改善由这种细菌引起的感染的预防和治疗。基于 Kpn 能够颠覆 PMN 介导的死亡的假设，目的是评估产碳青霉烯酶的肺炎克雷伯菌 ST258 是否能够调节 PMN 的杀菌反应，重点是与另一种机会性病原体——大肠杆菌（Eco）相比，形成 NETs。结果表明，当 PMN 受到 Kpn KPC 挑战时，NETs 的释放不存在，而 Eco 是 NETosis 的强烈诱导剂。此外，Kpn KPC 能够抑制 Eco 诱导的 NETosis。尽管外源性添加过氧化氢（H₂O₂），Kpn KPC 介导的 NETs 形成的抑制仍然发生，这并不涉及细菌释放的可溶性因子或细胞壁成分，并且依赖于细菌的活力。此外，当研究脱颗粒时，我们发现 Kpn KPC 仅影响初级颗粒的动员，初级颗粒包含具有更强杀菌特性的蛋白质以及与 NETosis 相关的蛋白质。总之，产碳青霉烯酶的肺炎克雷伯菌 ST258 通过抑制 NETs 的释放和初级颗粒的动员，有效地逃避了 PMN 的反应。
