C3 and endothelial dysfunction: While cross-sectional studies showed positive associations between circulating complements such as plasma C5 [38] and C5b-9 with endothelial dysfunction and subclinical atherosclerosis [39], C1q and C3 deficiencies aggravate atherosclerosis, presumably due to the role of C1q and C3 in promoting apoptotic cell clearance [40].