Abstract 10917: Dna Damage Promotes Atherosclerosis by Enhancing Inflammatory Responses via the DNA Sensing Cgas-Sting Pathway

Abstract

DNA damage is likely a key contributor to atherosclerosis. However, causative links between DNA damage and atherosclerosis are yet to be established. We investigated the role of DNA damage accumulation in atherosclerosis using the DNA repair protein Ku80-deficient apolipoprotein E knockout mice ( Ku80 +/- ApoE -/- ). Ku80 +/- ApoE -/- mice and ApoE -/- mice were fed on high-fat diet for 4 weeks. Oil red O staining showed that plaque area was significantly increased in Ku80 +/- ApoE -/- aortas. Immunohistochemical analysis of lesions from Ku80 +/- ApoE -/- mice revealed enhanced accumulation of DNA double-strand breaks (DSBs). Similar results were obtained from Ku80 +/- ApoE -/- mice fed on high-fat diet for 2 weeks which was considered as the early stages of atherosclerosis. mRNA levels of inflammatory cytokines such as IL-6, MCP-1 and IFN-β in the aorta were significantly elevated in Ku80 +/- ApoE -/- mice than those of ApoE -/- control mice. To further investigate links between DSB accumulation and enhanced proinflammatory responses, vascular smooth muscle cells were isolated from Ku80 WT (WT) and Ku80 +/- mice. mRNA levels of IL-6, MCP-1 and IFN-β were significantly elevated in Ku80 +/- cells compared to those of WT cells. Immunofluorescent analysis revealed DSB accumulation and persistent activation of the DNA repair kinase ATM in Ku80 +/- cells. In addition, senescent markers such as p16 INK4A and senescence-associated β-gal activity were also upregulated in Ku80 +/- cells. Interestingly, the level of cytosolic DNA was elevated in Ku80 +/- cells. Furthermore, phosphorylation of TANK-binding kinase 1 was significantly increased in Ku80 +/- cells, indicating the activation of the cGAS-STING DNA sensing pathway. Thus, we performed cGAS or STING silencing in Ku80 +/- cells using siRNA to test whether cGAS-STING pathway was associated with enhanced proinflammatory responses. cGAS or STING silencing attenuated mRNA level of IL-6 and protein level of IκBα, the NFκB inhibitory protein. Taken together, these results suggested that the accumulation of DSBs promoted atherosclerosis partly through enhanced inflammatory responses via the cGAS-STING activation. Therefore, cGAS-STING may be a promising target for therapeutic intervention of atherosclerosis.