The role of oxidative stress-altered lipoprotein structure and function and microinflammation on cardiovascular risk in patients with minor renal dysfunction

Cardiovascular disease is common in patients with chronic kidney disease (CKD). As renal function fails, many patients become progressively malnourished, as evidenced by reduced levels of albumin, prealbumin, and transferrin. Malnourished patients have increased levels of C reactive protein (CRP), interleukin-6 (IL-6), and concomitant cardiovascular disease when they reach end stage. Many diseases that cause CKD, diabetes, and hypertension are also associated with cardiovascular disease. Thus the direct effect of renal failure per se directly contributing to the inflammation-malnutrition-atherosclerosis paradigm is not completely established in early stages of CKD. Some aspects of progressive renal failure. however, cause changes in plasma composition and endothelial structure and function that favor vascular injury. As renal function fails, hepatic apo A-1 synthesis decreases and HDL levels fall. HDL is an important antioxidant and defends the endothelium from the effects of cytokines. Inflammation causes further structural and functional abnormalities in HDL. Apolipoprotem C III (apo C 111), a competitive inhibitor of lipoprotein lipase is increased in CKD. Serum triglyceride levels increase as a result of accumulation of intermediate-density lipoprotein (IDL) comprising VLDL and chylomicron remnants. These impede vascular relaxation and are associated with cardiovascular disease. Activation of the renin angiotensin axis is a component of many renal diseases and adaptation to loss of renal mass. Angiotensin 11 (AngII) activates NADPH oxidases, leading to production of the superoxide anion and decreased availability of nitric oxide (NO), further impairing vascular function. H2O2, produced as a consequence of superoxide dismutation, stimulates vascular cell proliferation and hypertrophy. Leukocyte-derived myeloperoxidase functions as an NO Oxidase in the inflamed vasculature and contributes to decreased NO bioavailability and compromised vascular reactivity. The changes in lipoprotein composition and structure as well as AngII-mediated alterations in endothelial function amplify the effect of subsequent inflammatory events.