Department of Biology, Shahed University, Tehran, Iran.
Department of Pathology, School of Medicine, Shahed University, Tehran, Iran; Molecular Microbiology Research Center and Department of Biology, Shahed University, Tehran, Iran.
Microb Pathog. 2024 Jan;186:106473. doi: 10.1016/j.micpath.2023.106473. Epub 2023 Dec 3.
Outer membrane protein A (OmpA) is a critical virulence factor in Acinetobacter baumannii, influencing adhesion, biofilm formation, host immune response, and host cell apoptosis. We investigated the invasion of A549 alveolar epithelial cells by A. baumannii and examined how anti-OmpA antibodies impact these interactions. OmpA was expressed and purified, inducing anti-OmpA antibodies in BALB/c mice. The potential toxicity of OmpA was evaluated in mice by analyzing histology from six organs. A549 cells were exposed to A. baumannii strains 19606 and a clinical isolate. Using cell culture and light microscopy, we scrutinized the effects of anti-OmpA sera on serum resistance, adherence, internalization, and proliferation of A. baumannii in A549 cells. The viability of A549 cells was assessed upon exposure to live A. baumannii and anti-OmpA sera. OmpA-induced antibody demonstrated potent bactericidal effects on both strains of A. baumannii. Both strains formed biofilms, which were reduced by anti-OmpA serum, along with decreased bacterial adherence, internalization, and proliferation in A549 cells. Anti-OmpA serum improved the survival of A549 cells post-infection. Pre-treatment with cytochalasin D hindered bacterial internalization, highlighting the role of actin polymerization in invasion. Microscopic examination revealed varied interactions encompassing adherence, apoptosis, membrane alterations, vacuolization, and damage. A549 cells treated with anti-OmpA serum exhibited improved structures and reduced damage. The findings indicate that A. baumannii can adhere to and proliferate within epithelial cells with OmpA playing a pivotal role in these interactions, and the complex nature of these interactions shapes the intricate course of A. baumannii infection in host cells.
外膜蛋白 A（OmpA）是鲍曼不动杆菌的关键毒力因子，影响其黏附、生物膜形成、宿主免疫反应和宿主细胞凋亡。我们研究了鲍曼不动杆菌对 A549 肺泡上皮细胞的侵袭，并探讨了抗-OmpA 抗体如何影响这些相互作用。我们表达和纯化了 OmpA，诱导 BALB/c 小鼠产生抗-OmpA 抗体。通过分析来自六个器官的组织学切片，评估了 OmpA 在小鼠中的潜在毒性。A549 细胞暴露于鲍曼不动杆菌 19606 株和临床分离株。通过细胞培养和荧光显微镜，我们研究了抗-OmpA 血清对 A549 细胞中鲍曼不动杆菌血清抗性、黏附、内化和增殖的影响。暴露于活鲍曼不动杆菌和抗-OmpA 血清后，评估了 A549 细胞的活力。OmpA 诱导的抗体对两种鲍曼不动杆菌菌株均具有强大的杀菌作用。两种菌株都形成了生物膜，抗-OmpA 血清可减少生物膜的形成，同时减少细菌在 A549 细胞中的黏附、内化和增殖。抗-OmpA 血清可提高感染后 A549 细胞的存活率。细胞松弛素 D 的预处理阻碍了细菌的内化，这突出了肌动蛋白聚合在入侵中的作用。显微镜检查显示了各种相互作用，包括黏附、凋亡、膜改变、空泡化和损伤。用抗-OmpA 血清处理的 A549 细胞表现出改善的结构和减少的损伤。这些发现表明，鲍曼不动杆菌可以黏附并在上皮细胞内增殖，其中 OmpA 在这些相互作用中起着关键作用，这些相互作用的复杂性塑造了鲍曼不动杆菌在宿主细胞中感染的复杂过程。
