MicroRNA-135a-5p suppresses the CaSR-NLRP3 inflammasome axis and protects against sepsis-induced acute lung injury

<bold>Rationale:</bold> To investigate the therapeutic potential of microRNA-135a-5p (miR-135a-5p) in sepsis-induced acute lung injury (ALI), a life-threatening condition characterized by excessive inflammation and lung barrier dysfunction. <bold>Methods:</bold> We used a cecal ligation and puncture (CLP) mouse model of sepsis-induced ALI and transfected miR-135a-5p mimic into mice via intraperitoneal injection. We also used MLE12 lung epithelial cells and RAW264.7 macrophages to study miR-135a-5p. We measured the expression of miR-135a-5p, calcium-sensing receptor (CaSR), NLRP3, and IL-1β by real-time PCR and western blotting. We validated CaSR as a direct target of miR-135a-5p by dual luciferase assay. We assessed the lung histology and cytokine levels by HE staining, and ELISA respectively. We evaluated cell apoptosis using flow cytometry. <bold>Results:</bold> MiR-135a-5p mimic transfection effectively increased the miR-135a-5p level and decreased the CaSR, NLRP3, and IL-1β expression in both mice and cells. MiR-135a-5p directly targets CaSR and suppresses its expression. miR-135a-5p mimic treatment also reduced lung inflammation, edema, injury, and bronchoalveolar lavage fluid (BALF) levels of IL-1β in septic mice. Moreover, Our Immunohistochemical (IHC) analysis of NLRP3 and Cleaved Caspase 1 showed reduced expression in mimic tissues compared to CLP-only tissues and cell apoptosis in LPS-stimulated macrophages. <bold>Conclusions:</bold> Our results demonstrate that miR-135a-5p exerts a protective effect against sepsis-induced ALI by targeting the CaSR-NLRP3 inflammasome pathway and lung barrier function. MiR-135a-5p may represent a novel therapeutic strategy for sepsis-induced ALI.