Serum 25-hydroxyvitamin D is associated with renal fi brosis (experimental study)

Abstract

INTRODUCTION. Vitamin D deficiency is commonly observed in patients with chronic kidney disease (CKD) due to decreased biosynthesis of 1,25(OH)2D3 in damaged renal tubules and increased catabolism of 1,25(OH)2D3 and 25OHD3. There is a growing evidence that vitamin D deficiency may contribute to impaired kidney function. Interventional studies have shown that vitamin D and its analogs attenuate the progression of renal fibrosis in experiment, and reduce proteinuria in patients with CKD. The renoprotective effects of vitamin D go far beyond its classical role in maintaining bone and mineral metabolism, which is a result of its pleiotropic action. THE AIM: to investigate the association between 25OH-hydroxyvitamin D (25OHD) level and renal fibrosis in spontaneously hypertensive rats (SHR) with early stages of experimental CKD.MATERIAL AND METHODS. Systolic blood pressure (BP), proteinuria, albuminuria, creatinine (Cr), urea (Ur), inorganic phosphate (Pi), 25OHD in serum were measured in nephrectomized (NE) and sham operated (SO) spontaneously hypertensive rats SHR (follow-up period 2, 4 and 6 months) and SO Wistar Kyoto rats (follow-up period 2 months), morphological light-optical study of kidney tissue was performed.RESULTS. The experimental model corresponded to the initial stages of CKD (Ur: 6.64 – 13.36 mmol/L). A significant increase in the area of renal fibrosis in animals with NE correlated with an increase in blood pressure (r = 0.51, p <0.001), serum Cr (r = 0.76, p <0.001), and albuminuria (r = 0.64, p <0.001) and proteinuria (r = 0.78, p <0.001) and a decrease in the concentration of 25OHD in serum (r = -0.67, p <0.001). In multiple regression analyzes, a reliable association of fibrosis with 25OHD was maintained (β = -0.28, p = 0.012). In addition, in ROC-analysis the largest value of the area under the curve was obtained for 25OHD (AUC = 0.95) to detect interstitial fibrosis more than 10 %.CONCLUSION. 25OHD depression at the initial stages of experimental CKD and hypertension is independently associated with the development of renal fibrosis.