Inflammasome Activation Promotes Deep Vein Thrombosis through Pyroptosis

Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep vein thrombosis (DVT), is one of the most common causes of cardiovascular death worldwide. Monocytic cells (including monocytes/macrophages) and their derived tissue factor have been reported to play important roles in the development of DVT. However, the mechanism by which monocytes contribute to the development DVT is not well elucidated. In this study, we reported a critical role of inflammasome activation and pyroptosis in the development of DVT. Using a flow restriction-induced mouse DVT model in the inferior vena cava, we show that deficiency of caspase-1 protected against flow restriction-induced DVT. Inflammasome activation leads to interleukin (IL)-1b and IL-18 maturation/release and pyroptosis. Recent studies show that caspases-1 cleaves Gasdermin D (GSDMD) and triggers pyroptosis-a form of programmed cell death with similar morphology to necrosis. We tested the hypothesis that GSDMD-dependent pyroptosis drives inflammasome-induced coagulation and DVT using Gsdmd^-/- mice. Indeed, flow restriction-induced DVT was inhibited by GSDMD deficiency. After induction of DVT, fibrin was deposited in the vein as detected by Western blot with a monoclonal antibody that specifically recognizes mouse fibrin, which were inhibited in the caspase-1 deficient mice and GSDMD deficient mice. IL-1b was also increased in tissue of vein following induction of DVT, which was inhibited by caspase-1 or GSDMD deficiency. Following inflammasome activation, pyroptotic macrophages release tissue factor (TF), an essential initiator of coagulation cascades. Consistently, flow restriction-induced DVT was flow restriction-induced DVT inhibited in inducible TF deficient mice. Our data reveal a critical role of inflammasome activation and pyroptosis in the development of DVT.