Hematopoietic NLRP3 and AIM2 inflammasomes promote diabetes-accelerated atherosclerosis, but increased necrosis is independent of pyroptosis
Serum apolipoprotein C3 (APOC3) predicts incident cardiovascular events in people with type 1 diabetes and silencing of APOC3 prevents both lesion initiation and advanced lesion necrotic core expansion in a mouse model of type 1 diabetes. APOC3 acts by slowing the clearance of triglyceride-rich lipoproteins, but lipid-free APOC3 has recently been reported to activate an inflammasome pathway in monocytes. We therefore investigated the contribution of hematopoietic inflammasome pathways to atherosclerosis in mouse models of type 1 diabetes. LDL receptor-deficient diabetes mouse models were transplanted with bone marrow from donors deficient in NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3), absent in melanoma 2 (AIM2), or gasdermin D (GSDMD), an inflammasome-induced executor of pyroptotic cell death. Mice with diabetes exhibited inflammasome activation, and consistently, increased plasma interleukin-1b (IL-1b) and IL-18. Hematopoietic deletions of NLRP3, AIM2 or GSDMD caused smaller atherosclerotic lesions in diabetic mice. The increased lesion necrotic core size in diabetic mice was independent of macrophage pyroptosis because hematopoietic GSDMD-deficiency failed to prevent necrotic core expansion in advanced lesions. Our findings demonstrate that AIM2 and NLRP3 inflammasomes contribute to atherogenesis in diabetes and suggest that necrotic core expansion is independent of macrophage pyroptosis.