Outer membrane protein A inhibits the degradation of caspase-1 to regulate NLRP3 inflammasome activation and exacerbate the Acinetobacter baumannii pulmonary inflammation. (April 2021)

• Record Type: Journal Article
• Authors: Li, Yumei; Peng, Chunhong; Zhao, Dan; Liu, Laibing; Guo, Bing; Shi, Mingjun; Xiao, Ying; Yu, Zijiang; Yu, Yan; Sun, Baofei; Wang, Wenjuan; Lin, Jieru; Yang, Xiaoyan; Shao, Songjun; Zhang, Xiangyan
• Is Part Of: Microbial pathogenesis. Volume 153(2021)
• Publication Date: 2021-04
• Subjects: Pneumonia -- Acinetobacter baumannii -- Outer membrane protein A (ompA) -- Inflammasome -- Ubiquitin; A. baumannii Acinetobacter baumanii -- ompA outer membrane protein A gene -- PBS phosphate-buffered saline -- LB broth Luria–Bertani broth -- ANOVA analysis of variance -- MOI multiplicity of infection -- qRT-PCR quantitative real-time polymerase chain reaction -- LPS lipopolysaccharide -- PLD phospholipases D -- PBP penicillin-binding protein -- OMV outer membrane vesicle -- NLRP3 nod-like receptor 3 -- ASC apoptosis-associated speck-like protein; Pathogenic microorganisms -- Periodicals; Pathology, Molecular -- Periodicals; Communicable Diseases -- microbiology -- Periodicals; Communicable Diseases -- parasitology -- Periodicals; Micro-organismes pathogènes -- Périodiques; Pathologie moléculaire -- Périodiques; Electronic journals; 616.9041
• DOI: 10.1016/j.micpath.2021.104788
• Languages: English
• ISSNs: 0882-4010

Abstract

Abstract: Acinetobacter baumannii ( A. baumannii ), one of the major pathogens that causes severe nosocomial infections, is characterised by a high prevalence of drug resistance. It has been reported that A. baumannii triggers the NOD-like receptor 3 (NLRP3) inflammasome, but the role of its virulence-related outer membrane protein A ( ompA ) remains unclear. Therefore, this study aimed to explore the effects of ompA on the NLRP3 inflammasome and its underlying molecular mechanisms. Results showed that ompA enhanced inflammatory damage, which was reduced as a result of knockout of the ompA gene. Additionally, ompA -stimulated expression of NLRP3 inflammasome was significantly blocked by silencing caspase-1, but activation of NLRP3 inflammasome was not altered after silencing ASC; this indicated that ompA was dependent on the caspase-1 pathway to activate the inflammatory response. Simultaneously, the wild-type (WT) strains triggered NLRP3 inflammasome after inhibition of caspase-1 degradation by proteasome inhibitor MG-132, aggravating tissue damage. These findings indicated that ompA may be dependent on the caspase-1 pathway to enhance inflammation and exacerbate tissue damage. Taken together, these results confirmed a novel capsase-1−modulated mechanism underpinning ompA activity, which further reveals the NLRP3 inflammasome pathway as a potential immunomodulatory target against A. baumannii infections. Highlights: A.baumannii cause the inflammtion via NLRP3 inflammasome. The ompA promoted NLRP3 inflammasome activation after A. baumannii infection. The ompA may be dependent on the caspase-1 pathway to enhance inflammation and exacerbate tissue damage.