Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho, United States of America.
PLoS One. 2010 Feb 18;5(2):e9279. doi: 10.1371/journal.pone.0009279.
The human innate immune system relies on the coordinated activity of macrophages and polymorphonuclear leukocytes (neutrophils or PMNs) for defense against bacterial pathogens. Yersinia spp. subvert the innate immune response to cause disease in humans. In particular, the Yersinia outer protein YopJ (Y. pestis and Y. pseudotuberculosis) and YopP (Y. enterocolitica) rapidly induce apoptosis in murine macrophages and dendritic cells. However, the effects of Yersinia Yop J/P on neutrophil fate are not clearly defined.
METHODOLOGY/PRINCIPAL FINDINGS: In this study, we utilized wild-type and mutant strains of Yersinia to test the contribution of YopJ and YopP on induction of apoptosis in human monocyte-derived macrophages (HMDM) and neutrophils. Whereas YopJ and YopP similarly induced apoptosis in HMDMs, interaction of human neutrophils with virulence plasmid-containing Yersinia did not result in PMN caspase activation, release of LDH, or loss of membrane integrity greater than PMN controls. In contrast, interaction of human PMNs with the virulence plasmid-deficient Y. pestis strain KIM6 resulted in increased surface exposure of phosphatidylserine (PS) and cell death. PMN reactive oxygen species (ROS) production was inhibited in a virulence plasmid-dependent but YopJ/YopP-independent manner. Following phagocytic interaction with Y. pestis strain KIM6, inhibition of PMN ROS production with diphenyleneiodonium chloride resulted in a reduction of PMN cell death similar to that induced by the virulence plasmid-containing strain Y. pestis KIM5.
Our findings showed that Yersinia YopJ and/or YopP did not induce pronounced apoptosis in human neutrophils. Furthermore, robust PMN ROS production in response to virulence plasmid-deficient Yersinia was associated with increased PMN cell death, suggesting that Yersinia inhibition of PMN ROS production plays a role in evasion of the human innate immune response in part by limiting PMN apoptosis.
人体先天免疫系统依赖于巨噬细胞和多形核白细胞（中性粒细胞或 PMN）的协调活动来抵御细菌病原体。耶尔森氏菌属会颠覆先天免疫反应，导致人类患病。具体来说，耶尔森氏菌外蛋白 YopJ（鼠疫耶尔森氏菌和假结核耶尔森氏菌）和 YopP（肠耶尔森氏菌）可迅速诱导鼠巨噬细胞和树突状细胞凋亡。然而，耶尔森氏菌 YopJ/P 对中性粒细胞命运的影响尚不清楚。
方法/主要发现：在这项研究中，我们利用野生型和突变型耶尔森氏菌菌株来测试 YopJ 和 YopP 对人单核细胞衍生巨噬细胞（HMDM）和中性粒细胞凋亡的诱导作用。尽管 YopJ 和 YopP 对 HMDM 具有相似的诱导凋亡作用，但与人中性粒细胞的相互作用不会导致 PMN 半胱天冬酶激活、LDH 释放或膜完整性丧失超过 PMN 对照。相比之下，与人中性粒细胞的相互作用缺乏毒力质粒的鼠疫耶尔森氏菌 KIM6 株导致 PS 表面暴露增加和细胞死亡。PMN 活性氧（ROS）的产生以依赖毒力质粒但不依赖 YopJ/YopP 的方式受到抑制。在与鼠疫耶尔森氏菌 KIM6 菌株吞噬相互作用后，用二苯基碘氯化物抑制 PMN ROS 产生可使 PMN 细胞死亡减少类似于含毒力质粒的鼠疫耶尔森氏菌 KIM5 菌株诱导的细胞死亡。
我们的研究结果表明，耶尔森氏菌 YopJ 和/或 YopP 不会在人中性粒细胞中诱导明显的凋亡。此外，对毒力质粒缺失的耶尔森氏菌产生强烈的 PMN ROS 产生与 PMN 细胞死亡增加有关，这表明耶尔森氏菌抑制 PMN ROS 产生在一定程度上通过限制 PMN 凋亡来逃避人体先天免疫反应中发挥作用。
