Regulatory role and mechanism of sRNA24 targeting pqsH in Pseudomonas aeruginosa infection immunity

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen that causes healthcareassociated infections through complex virulence mechanisms and immune evasion strategies. The quorumsensing (QS) system is central to its pathogenesis, whereas small noncoding RNAs (sRNAs) modulate bacterial adaptability and virulence. This study investigates the regulatory function of sRNA24 during infection. This study used a mouse intraperitoneal infection model and RNA sequencing for screening to identify and explore the regulatory function of sRNA24 during infection. Bacterial proliferation, virulencerelated phenotypes, host cell adhesion/invasion, and immunerelated transcriptional levels were subsequently assessed. Mechanistic studies focused on the functional targeting of pqsH, a crucial QS synthase gene. Results:The expression of sRNA24 is dynamically regulated by the host immunological microenvironment. sRNA24 does not influence bacterial proliferation but promotes pyocyanin synthesis, biofilm development, and host cell adhesion/invasion, while inhibiting swimming/swarming motility. Immunologically, sRNA24 suppresses M1 macrophage markers and pro-inflammatory cytokines, promotes M2 markers and antiinflammatory cytokines, and exhibits an anti-inflammatory-biased transcriptional profile. Mechanistically, sRNA24 functionally targets and upregulates pqsH expression. Overexpression of pqsH mimics the phenotypes induced by sRNA24 overexpression. In vivo, the sRNA24-overexpressing strain exhibits enhanced peritoneal colonization. These findings reveal a previously unrecognized sRNAmediated regulatory axis in P. aeruginosa infection, suggesting sRNA24 as a potential target for further investigation in the context of persistent infections.