Immunomodulating effects of vitamin D analogs in hemodialysis patients.

Apart from its well-known functions in calcium homeostasis and parathyroid hormone regulation, 1,25-(OH)2D3 and its synthetic analogs are being increasingly recognized for their potent antiproliferative, pro-differentiative and immunomodulating activities. The effects of these drugs are exerted either via vitamin D receptor-dependent genomic, or cell-surface receptor-mediated, non-genomic pathways. Several vitamin D analogs with fewer hypercalcemic side effects have been developed for use in secondary hyperparathyroidism. These analogs may potentially improve treatment of autoimmune disorders and graft rejection, and in dialysis patients may open a new opportunity for amelioration of the chronic inflammatory status. It has recently been shown that hemodialysis (HD) patients treated with paricalcitol have lower total and cardiovascular mortality and morbidity rates and experience improved hospitalization outcomes compared with HD patients treated with calcitriol, suggesting a potential beneficial effect in chronic inflammation and the development of cardiovascular disease. Specific studies on the immunomodulating effects of vitamin D are needed in the HD population.