Although, exploring the immunomodulatory role of vitamin D in the process of atherosclerosis which is a common co-morbidity associated with chronic inflammation as seen in various ARDs is beyond the scope of this review, it is worth mentioning the protective effects of vitamin D on endothelial activation and dysfunction, through inhibition of cyclooxygenase 2 and cellular/platelets adhesion molecules expression, as well as pro-inflammatory cytokines synthesis, therefore minimizing the inflammatory processes contributing to atherosclerosis plaque formation (17, 18). This evidence concerns the gene PTGS2 and atherosclerosis.