Nox2 mediates high fat high sucrose diet-induced nitric oxide dysfunction and inflammation in aortic smooth muscle cells.

Diet-induced obesity and metabolic syndrome are important contributors to cardiovascular diseases. The decreased nitric oxide (NO) bioactivity in endothelium and the impaired response of smooth muscle cell (SMC) to NO significantly contribute to vascular pathologies, including atherosclerosis and arterial restenosis after angioplasty. Sarco/endoplasmic reticulum Ca(2+) ATPase (SERCA) is an important mediator of NO function in both endothelial cells and SMCs, and its irreversible oxidation impairs its stimulation by NO. We used C57BL/6J mice fed a high fat high sucrose diet (HFHSD) to study the role of SMC SERCA in diet-induced obesity and metabolic syndrome. We found that HFHSD upregulated Nox2 based NADPH oxidase, induced inflammation, increased irreversible SERCA oxidation, and suppressed the response of aortic SERCA to NO. Cultured aortic SMCs from mice fed HFHSD showed increased reactive oxygen species production, Nox2 upregulation, irreversible SERCA oxidation, inflammation, and a decreased ability of NO to inhibit SMC migration. Overexpression of wild type SERCA2b or downregulation of Nox2 restored NO-mediated inhibition of migration in SMCs isolated from HFHSD-fed mice. In addition, tumor necrosis factor alpha (TNFα) increased Nox2 which induced SERCA oxidation and inflammation. Taken together, Nox2 induced by HFHSD plays significant roles in controlling SMC responses to NO and TNFα-mediated inflammation, which may contribute to the development of cardiovascular diseases in diet-induced obesity and metabolic syndrome.