Hypertension and nephrology

[The role of vitamin D receptor and the risk reducing effect of vitamin D receptor agonists in chronic kidney disease]

KISS István, KULCSÁR Imre, BARABÁS Noémi, KERKOVITS Lóránt

OCTOBER 20, 2010

Hypertension and nephrology - 2010;14(05)

[Vitamin D3 is produced in the skin and is modified in the liver and kidney to the active metabolite form, 1,25-dyhydroxyvitamin D3 (calcitriol). Calcitriol binds to a nuclear receptor, the vitamin D receptor (VDR), and activates processes that bind to vitamin D. The classical effects of vitamin D receptor activator or agonist (VDRA) therapy for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease primarily involves suppressive effects on the parathyroid gland, and regulation of calcium and phosphorus absorption in the intestine an mobilization in bone. Several VDR agonists have been developed for the treatment of osteoporosis, hyperparathyroidism secondary to chronic kidney disease (CKD), and psoriasis. Secondary hyperparathyroidism (SHPT) is a common and serious consequence of CKD. SHPT is a complex condition characterized by a decline in 1,25-dihidroxi vitamin D and consequent VDR activation, abnormalities in serum calcium and phosphorus levels, parathyroid gland hyperplasia, elevated parathyroid hormone (PTH) secretion, and systemic mineral and bone abnormalities. There are three classes of drug used for treatment of SHPT (non-selective and selective VDR activators, and calcimimetics). Observational studies in hemodialysis patients report improved cardiovascular and allcause survival among those received VDRA therapy compared with those not on VDRA therapy. The survival benefits of selective VDRA paricalcitol appear to be linked to "non classical" action of VDRA, possibly through VDRA-mediated modulation of gene expression. VRDAs are reported to have beneficial effects such as anti-inflammatory and antithrombotic effects, inhibition of vascular calcification and stiffening, inhibition of vascular smooth muscle cell proliferation, and regression of left ventricular hypertrophy. VDRA are also reported to negatively regulate the renin-angiotensin system, which plays a key role in hypertension, myocardial infarction and stroke. Data from epidemiological, preclinical and clinical studies have shown that vitamin D and/or 25(OH) vitamin D deficiency is associated with increased risk for cardiovascular disease (CVD). The selective VDR agonists are associated direct protective effects on glomerular architecture and antiproteinuric effects in response to renal damage. Emerging evidence suggest that VDR plays important roles in modulating cardiovascular, immunological, metabolic and other function. Paricalcitol may prove to have a substantial beneficial effect on cardiac disease and its outcome in patients with CKD.]

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