Aeromonas veronii Infection Induces Pyroptosis in Largemouth Bass (Micropterus salmoides)

Aeromonas veronii , a prevalent Gram‐negative bacterium in aquaculture, poses significant health risks to economically important freshwater fish species such as largemouth bass ( Micropterus salmoides ). This study investigates the role of pyroptosis, a highly inflammatory programmed cell death, in the immune response of largemouth bass to A. veronii infection. We characterised key pyroptosis‐associated proteins, MsGSDMEa and MsGSDMEb, which harbour two conserved Gasdermin domains and are crucial in mediating pyroptosis. Following A. veronii infection, largemouth bass exhibited a robust upregulation of inflammatory cytokines (IL‐1β, IL‐8, TNF‐α) and increased lactate dehydrogenase (LDH) activity in serum, indicating extensive cellular damage and inflammation. Quantitative real‐time PCR analysis revealed a significant upregulation of pyroptosis‐related genes, including NLRP3, ASC, and caspases (Caspase‐1/−3/−7), in both spleen tissue and GF‐1 cell line post‐infection. Western blot analysis confirmed the cleavage of GSDME, a critical step in pyroptosis execution. These findings underscore the role of pyroptosis in the immune response of largemouth bass to A. veronii infection and suggest that modulating pyroptosis could be a potential strategy for disease management in freshwater fish species.