The role of miR-15b-5p in severe pneumonia and its effect on bronchial epithelial cell injury

MiRNA as a biomarker has multiple advantages, and this study aimed to explore the potential role of miR-15b-5p in severe pneumonia (SP). This study included 65 healthy controls and 140 pneumonia patients, comprising 71 mild pneumonia (MP) and 69 SP. Serum and cellular miR-15b-5p levels were quantified via PCR, with diagnostic utility assessed by ROC analysis. Correlation analysis assessed the clinical associations between miR-15b-5p and severity parameters of SP, while Kaplan-Meier and COX regression analyses evaluated survival outcomes. In vitro, LPS-induced human bronchial epithelial cell (16HBE) injury models were established to examine cell viability (CCK-8), inflammation, and oxidative stress (commercial kits). Dual-luciferase assays confirmed interaction between miR-15b-5p and WNT3A. Elevated miR-15b-5p expression demonstrated diagnostic value in distinguishing SP from MP and MP from healthy controls, with significant correlations to SP-related inflammatory markers (WBC, NEU, LYM, CRP, PCT), severity scores (APACHE II, SOFA), and pulmonary function (respiratory rate and PaO₂/FiO₂). Higher miR-15b-5p levels predicted worse prognosis and emerged as an independent prognostic factor for SP. In vitro LPS exposure increased miR-15b-5p expression in 16HBE cells, reducing cell viability, exacerbating inflammation and oxidative stress, which could be reversed by miR-15b-5p knockdown. WNT3A downregulation in LPS-treated cells was rescued upon miR-15b-5p inhibition, with dual-luciferase assays confirming direct miR-15b-5p-WNT3A interaction. Upregulation of miR-15b-5p correlated with SP severity and showed diagnostic and prognostic potential in SP. MiR-15b-5p might promote SP progression by aggravating bronchial epithelial cell injury, which may be associated with WNT3A downregulation.