3306Endothelial cell senescence accelerates atherosclerosis by enhancing monocyte recruitment via hyper-reactivity to inflammatory stimuli

Background Ageing is a significant risk factor for atherosclerotic diseases. Vascular senescence has been considered to play an important role in the progression of atherosclerosis; however, it remains unclear whether endothelial cell (EC) senescence is causally involved in the pathogenesis of atherosclerosis. Purpose The purpose of this study is to elucidate a causative role of senescent EC in the progression of atherosclerosis. Methods Telomeric repeat-binding factor 2 (TRF2) plays a central role in telomere maintenance and protection against end-to-end fusion of chromosome. We previously reported that overexpression of TRF2-dominant negative mutant (TRF2DN) induced premature senescence in EC. We recently generated EC-specific progeroid mice by overexpressing TRF2DN specifically in EC (TRF2DN-Tg), and then generated ApoE-KO/TRF2DN-Tg mice to analyze a role of EC senescence in atherosclerosis. These mice were fed with a high cholesterol-diet, and atherosclerosis was assessed by en face analysis of whole aorta and histological analysis of aortic sinus. In vitro studies to analyze the underlying mechanisms were performed using replicative senescent HUVECs. Results En face analysis of aorta revealed that atherosclerotic lesions were significantly increased in ApoE-KO/TRF2DN-Tg mice comparing with that in ApoE-KO mice at as early as 2 weeks after high-cholesterol diet. Histological analysis of aortic sinus also exhibited accelerated atherosclerosis in ApoE-KO/TRF2DN-Tg mice in association with increased macrophage infiltration. Mechanistically, we found that the induction of adhesion molecules such as VCAM-1, ICAM-1, and E-selectin in response to low-grade inflammatory stimuli was substantially augmented in senescent ECs comparing with that in young ECs. As a result, monocyte adhesion was significantly enhanced in senescent ECs. Of note, eNOS inhibition did not affect the hyper-reactivity of senescent EC to inflammation, while antagonizing NF-kB abolished it. Nuclear translocation of NF-kB in response to inflammation was not different between young and senescent ECs, suggesting that NF-kB transcriptional activity might be enhanced in senescent ECs. Conclusion We revealed a causative role of EC senescence in the progression of atherosclerosis in vivo using unique EC-specific progeroid mice. Our findings revealed that EC senescence is a bona fide risk for atherosclerosis, and thus senescent ECs are attracting pharmacotherapeutic targets for the prevention and/or treatment of atherosclerotic disease in elderly population.