BACKGROUND: Klebsiella pneumoniae (KP)-induced pneumonia has a high incidence rate, and current treatment options remain limited. The efficacy and mechanism of the novel natural compound Ciliatoside A (CA) against KP-induced pneumonia remain unclear.
AIMS: Investigating whether CA improves KP-induced pneumonia through the sirtuin 1 (SIRT1)/PTEN-induced putative kinase 1 (PINK1)/Parkin axis.
METHODS: KP was used to infect A549 cells, and resistance genes expression was detected using qRT-PCR. To evaluate CA's effect on cell viability, the Cell Counting Kit-8 assay was utilised. Different kits were employed to measure mitochondrial membrane potential, mitochondrial reactive oxygen species (mtROS), and ATP production. Transmission electron microscopy was used to observe autophagosome formation, and cellular autophagy was assessed via Western blot and LC3 fluorescence analysis. Flow cytometry, PI/Hoechst staining, and ELISA were employed to investigate the impacts of CA on A549 cell death and cytokine secretion. A KP mouse pneumonia model was established. Pathological staining was used to observe lung tissue damage and inflammatory infiltration, and Western blot was employed to validate protein expression in vivo. To verify whether CA alleviates KP-induced pneumonia through the SIRT1/PINK1/Parkin axis, intervention with SIRT1 agonists/inhibitors was conducted.
RESULTS: CA treatment downregulated drug resistance genes in KP and A549 cells, enhanced the viability of A549 cells following KP infection, and inhibited apoptosis. CA reduced mtROS accumulation, increased mitochondrial membrane potential and ATP production, promoted mitochondrial autophagy, and inhibited NLRP3-mediated inflammasome-mediated cell death. Additionally, CA alleviated pulmonary edema and pathological damage in mice following KP infection, while inhibiting apoptosis and pulmonary inflammation. Following KP infection, the SIRT1/PINK1/Parkin axis was blocked in A549 cells and mouse lung tissue; CA treatment activated this pathway. SIRT1 agonists enhanced the protective impact of CA against KP infection in A549 cells and mouse lung tissue, while SIRT1 inhibitors reduced the protective effect of CA.
CONCLUSION: CA improves KP-induced pneumonia through activating the SIRT1/PINK1/Parkin axis to regulate mitochondrial autophagy.
