CAPN1 Promotes Pseudomonas aeruginosa-Induced Infection by Interacting with TFEB and Inhibiting Autophagy.

INTRODUCTION: Autophagy-lysosome pathways play a crucial role in the intracellular killing of pathogenic microorganisms. This study aimed to explore the mechanism by which acute lung injury (ALI) of Pseudomonas aeruginosa affects the autophagy-lysosome pathway. METHODS: ALI mouse models were induced by lipopolysaccharide and P. aeruginosa strain K (PAK). Lung tissue sections were stained with hematoxylin-eosin for observation. Flow cytometry was used to analyze bacteria and inflammatory cell infiltration. ELISA was performed to measure inflammatory factor levels. Transmission electron microscopy evaluated autolysosome quantity. Western blot detected levels of related proteins. Immunofluorescence evaluated LC3 expression, and the localization of TFEB in cells was observed. Co-immunoprecipitation and pull-down experiments confirmed the interaction between CAPN1 and TFEB. qRT-PCR measured capn1 and tfeb expression. RESULTS: Mouse experiments revealed that PAK infection led to the suppression of autolysosomes in mouse lung tissue, along with increased CAPN1 expression and decreased TFEB in the lung tissue of PAK-induced pneumonia mice. CAPN1-deficient mice could reverse the impact of PAK infection on autolysosomes in mouse lung tissue. These findings were further verified by cell experiments. At a mechanistic level, CAPN1 can interact with TFEB after PAK infection and prevent its entry into the nucleus, thereby inhibiting the autophagolysosomal pathway. CONCLUSION: CAPN1 promotes PAK-induced ALI by inhibiting the autophagy-lysosome pathway by targeting TFEB. INTRODUCTION: Autophagy-lysosome pathways play a crucial role in the intracellular killing of pathogenic microorganisms. This study aimed to explore the mechanism by which acute lung injury (ALI) of Pseudomonas aeruginosa affects the autophagy-lysosome pathway. METHODS: ALI mouse models were induced by lipopolysaccharide and P. aeruginosa strain K (PAK). Lung tissue sections were stained with hematoxylin-eosin for observation. Flow cytometry was used to analyze bacteria and inflammatory cell infiltration. ELISA was performed to measure inflammatory factor levels. Transmission electron microscopy evaluated autolysosome quantity. Western blot detected levels of related proteins. Immunofluorescence evaluated LC3 expression, and the localization of TFEB in cells was observed. Co-immunoprecipitation and pull-down experiments confirmed the interaction between CAPN1 and TFEB. qRT-PCR measured capn1 and tfeb expression. RESULTS: Mouse experiments revealed that PAK infection led to the suppression of autolysosomes in mouse lung tissue, along with increased CAPN1 expression and decreased TFEB in the lung tissue of PAK-induced pneumonia mice. CAPN1-deficient mice could reverse the impact of PAK infection on autolysosomes in mouse lung tissue. These findings were further verified by cell experiments. At a mechanistic level, CAPN1 can interact with TFEB after PAK infection and prevent its entry into the nucleus, thereby inhibiting the autophagolysosomal pathway. CONCLUSION: CAPN1 promotes PAK-induced ALI by inhibiting the autophagy-lysosome pathway by targeting TFEB.