Vibrio vulnificus hemolysin drives NLRP3 inflammasome activation in platelets via TRPC6-mediated calcium signaling.

Vibrio vulnificus, an opportunistic pathogenic species, predominantly induces sepsis in patients with liver disease rather than in healthy individuals, although its opportunistic pathogenic mechanisms are unclear. The role and mechanisms behind the NLRP3 inflammasome activation induced by V. vulnificus infection in normal mice or healthy humans, serving as a core sensor and signal amplifier of the innate immune system in platelets, have not been elucidated. Here we discovered that V. vulnificus hemolysin (VVH), a member of Cholesterol-dependent cytolysins (CDCs), rather than multifunctional auto processing Repeats-in-Toxins (MARTX), is the specific effector of V. vulnificus, activating the NLRP3 inflammasome, platelet pyroptosis, necroptosis, and increasing IL-1β expression. Mechanistically, rather than ROS production, VVH-induced the intracellular Ca2+ increasing is essential for triggering NLRP3 inflammasome activation in platelet, which are mediated by the classical transient receptor potential channel 6 (TRPC6)-triggering Ca2+ influx and calcium-induced calcium release (CICR). The pharmacological inhibition of TRPC (SKF-96365) partially alleviated inflammation and increased mortality in murine infection models. Furthermore, activating VVH toxin-NLRP3 inflammasome axis in platelets contributes to bacterial clearance in host. This study provides a novel perspective on opportunistic pathogen-host interactions, in which CDC acts as danger signals sensed by the host to activate NLRP3 inflammasome to trigger host immune defense.