Flufenamic acid protects against intestinal fluid secretion and barrier leakage in a mouse model ofVibrio choleraeinfection through NF-κB inhibition and AMPK activation
Nuclear factor kappa B (NF-κB)-mediated inflammatory responses play crucial roles in the pathogenesis of diarrhea caused by the Vibrio cholerae El Tor variant (EL), which is a major bacterial strain causing recent cholera outbreaks. Flufenamic acid (FFA) has previously been demonstrated to be a potent activator of AMP-activated protein kinase (AMPK), which is a negative regulator of NF-κB signaling. This study aimed to investigate the anti-diarrheal efficacy of FFA in a mouse model of EL infection and to investigate the mechanisms by which FFA activates AMPK in intestinal epithelial cells (IEC). In a mouse closed loop model of EL infection, FFA treatment (20 mg/kg) significantly abrogated EL-induced intestinal fluid secretion and barrier disruption. In addition, FFA suppressed NF-κB nuclear translocation and expression of proinflammatory mediators and promoted AMPK phosphorylation in the EL-infected mouse intestine. In T84 cells, FFA induced AMPK activation. Furthermore, FFA promoted tight junction assembly and prevented interferon gamma (IFN-γ)-induced barrier disruption in an AMPK-dependent manner. Biochemical and molecular docking analyses indicated that FFA activates AMPK via a direct stimulation of calcium/calmodulin-dependent protein kinase kinase beta (CaMKKβ) activity. Collectively, our data indicate that FFA represents a class of existing drugs that may be of potential utility in the treatment of cholera caused by EL infection via AMPK-mediated suppression of NF-κB signaling in IEC.