Mortality, malnutrition, and atherosclerosis in ESRD: what is the role of interleukin-6?

There is growing evidence that increased plasma concentrations of CRP strongly predict cardiovascular death in both non-renal and renal patient populations. The interleukin-6 (IL-6) system activity, which is the major mediator of the acute phase response, is often markedly up-regulated in uremic patients and has also been shown to predict outcome. This raises the issue of whether or not IL-6 per se may contribute to increased mortality from malnutrition and atherosclerotic cardiovascular disease in uremic patients. The causes of elevated IL-6 levels in the uremic circulation are not fully understood, although a number of factors prevalent in uremic patients, such as hypertension, adiposity, infections, and chronic heart failure may all contribute. However, factors associated with the dialysis procedure, such as bioincompatibility and non-sterile dialysate, may stimulate IL-6 production. Furthermore, available evidence suggests that genetic factors may also have an impact on circulating plasma IL-6 levels. We advance the hypothesis that IL-6 may play a central role in the genesis of inflammatory-driven malnutrition and that it may be regarded as a significant proatherogenic cytokine. This hypothesis may provide a rationale to test if targeted anti-cytokine therapy may be one way to combat the unacceptable high cardiovascular mortality rate among dialysis patients.