Plasma-derived exosomes contribute to pancreatitis-associated lung injury by triggering NLRP3-dependent pyroptosis in alveolar macrophages.

Progression of acute pancreatitis (AP) into a severe form usually results in a life-threatening condition with multiple organ dysfunction, and in particular acute lung injury (ALI), often contributes to the majority of AP-associated deaths. Increasing evidence has shown that uncontrolled activation of the immune system with rapid production of inflammatory cytokines play a dominant role in this process. As an intracellular inflammatory signaling platform, the NOD-like receptor protein 3 (NLRP3) inflammasome, is recently reported to be involved in the pathogenesis of AP progression, however, the relationship between NLRP3 inflammasome activation and AP-associated lung injury remains unclear yet. Here, we show that NLRP3 inflammasome activation and subsequent pyroptosis in alveolar macrophages (AMs) is responsible for the lung injury secondary to AP. In addition, plasma-derived exosomes from AP mice is capable of triggering NLRP3-dependent pyroptosis in AMs. Inhibition of exosome release or uptake in vivo by inhibitors substantially suppresses AMs pyroptosis and thereby alleviates AP-induced pulmonary lesion. Collectively, the current work reveals for the first time the involvement of NLRP3-dependent pyroptosis induced by plasma exosomes in the pathogenesis of AP-induced ALI, suggesting that the exosome-mediated NLRP3 inflammatory pathway is a potential therapeutic target for the treatment of lung injury during AP.