Intermedilysin is essential for the invasion of hepatoma HepG2 cells by Streptococcus intermedius
Intermedilysin is essential for the invasion of hepatoma HepG2 cells by Streptococcus intermedius
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DOI：
10.1111/j.1348-0421.2005.tb03647.x
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发表时间：
2005-01-01
影响因子：
2.6
通讯作者：
Kourai, H
中科院分区：
文献类型：
--
作者：
Sukeno, A;Nagamune, H;Kourai, H
中间链球菌引起内源性感染，导致脓肿。该物种产生中间溶素（ILY），一种人类特有的细胞溶素。由于中间葡萄球菌的高ILY产量与深部脓肿之间存在显著相关性，我们构建了ILY敲除突变体UNS38 B3和互补菌株UNS38 B3R1，以研究ILY在深部感染中的作用。菌株UNS38在感染后降低人肝细胞株HepG2的活力，而对大鼠肝细胞株BRL3A没有影响。等基因突变株uns38b3对两种细胞系均无细胞毒性。中间葡萄球菌的定量显示，在感染的HepG2细胞中，UNS38而非UNS38 B3在细胞内随细胞损伤的增加而增加。UNS38和UNS38 B3之间的差异在UNS38 B3R1中没有观察到。未观察到BRL3A细胞的侵袭和增殖。用ILY抗体掩盖UNS38或UNS38 B3R1可显著降低HepG2的粘附性和侵袭性。此外，用ILY包被菌株UNS38 B3部分恢复了对HepG2的粘附，但没有随后的细菌生长。感染后第1天，在HepG2受损吞噬体中检测到许多完整的UNS38，再孵育2天后，在死亡HepG2的细胞质中观察到细菌增殖。这些结果表明，中间葡萄球菌表面结合的ILY是该细菌入侵人类细胞的重要因素，宿主细胞内分泌ILY对随后的宿主细胞死亡至关重要。这些数据强烈暗示，在这种链球菌的体内脓肿发病机制中，ILY是一个重要因素。
Streptococcus intermedius causes endogenous infections leading to abscesses. This species produces intermedilysin (ILY), a human-specific cytolysin. Because of the significant correlation between higher ILY production levels by S. intermedius and deep-seated abscesses, we constructed ily knockout mutant UNS38 B3 and complementation strain UNS38 B3R1 in order to investigate the role of ILY in deep-seated infections. Strain UNS38 reduced the viability of human liver cell line HepG2 at infection but not of rat liver cell line BRL3A. Isogenic mutant strain UNS38 B3 was not cytotoxic in either cell line. Quantification of S. intermedius revealed that in infected HepG2 cells UNS38 but not UNS38 B3 increased intracellularly concomitantly with increasing cell damage. This difference between UNS38 and UNS38 B3 was not observed with UNS38 B3R1. Invasion and proliferation in BRL3A cells was not observed. Masking UNS38 or UNS38 B3R1 with ILY antibody drastically decreased adherence and invasion of HepG2. Moreover, coating strain UNS38 B3 with ILY partially restored adherence to HepG2 but without subsequent bacterial growth. At I day post-infection, many intact UNS38 were detected in the damaged phagosomes of HepG2 with bacterial proliferation observed in the cytoplasm of dead HepG2 after an additional 2 day incubation. These results indicate that surface-bound ILY on S. intermedius is an important factor for invasion of human cells by this bacterium and that secretion of ILY within host cells is essential for subsequent host cell death. These data strongly implicate ILY as an important factor in the pathogenesis of abscesses in vivo by this streptococcus.