Department of Microbiology, Adam Mickiewicz University, ul. Umultowska 89, 61-614 Poznan, Poland.
Curr Microbiol. 2012 Sep;65(3):319-29. doi: 10.1007/s00284-012-0159-7. Epub 2012 Jun 9.
We investigated interactions of human isolates of Acinetobacter calcoaceticus-baumannii complex strains with epithelial cells. The results showed that bacterial contact with the cells as well as adhesion and invasion were required for induction of cytotoxicity. The infected cells revealed hallmarks of apoptosis characterized by cell shrinking, condensed chromatin, and internucleosomal fragmentation of nuclear DNA. The highest apoptotic index was observed for 4 of 10 A. calcoaceticus and 4 of 7 A. baumannii strains. Moreover, we observed oncotic changes: cellular swelling and blebbing, noncondensed chromatin, and the absence of DNA fragmentation. The highest oncotic index was observed in cells infected with 6 A. calcoaceticus isolates. Cell-contact cytotoxicity and cell death were not inhibited by the pan-caspase inhibitor z-VAD-fmk. Induction of oncosis was correlated with increased invasive ability of the strains. We demonstrated that the mitochondria of infected cells undergo structural and functional alterations which can lead to cell death. Infected apoptotic and oncotic cells exhibited loss of mitochondrial transmembrane potential (ΔΨ(m)). Bacterial infection caused generation of nitric oxide and reactive oxygen species. This study indicated that Acinetobacter spp. induced strain-dependent distinct types of epithelial cell death that may contribute to the pathogenesis of bacterial infection.
我们研究了鲍曼不动杆菌复合菌株的人类分离株与上皮细胞的相互作用。结果表明，细菌与细胞的接触以及黏附和入侵是诱导细胞毒性所必需的。受感染的细胞表现出凋亡的特征，表现为细胞缩小、染色质浓缩和核 DNA 核小体片段化。在 10 株鲍曼不动杆菌和 7 株醋酸钙不动杆菌中，有 4 株观察到最高的凋亡指数。此外，我们观察到胀亡变化：细胞肿胀和起泡、非浓缩染色质以及没有 DNA 片段化。在感染了 6 株醋酸钙不动杆菌分离株的细胞中，观察到最高的胀亡指数。细胞接触细胞毒性和细胞死亡不受泛半胱天冬酶抑制剂 z-VAD-fmk 的抑制。胀亡的诱导与菌株侵袭能力的增强相关。我们证明，感染细胞的线粒体发生结构和功能改变，可能导致细胞死亡。感染凋亡和胀亡的细胞表现出线粒体跨膜电位 (ΔΨ(m)) 的丧失。细菌感染导致一氧化氮和活性氧的产生。本研究表明，不动杆菌属诱导了依赖于菌株的不同类型的上皮细胞死亡，这可能有助于细菌感染的发病机制。
