Genomic and proteomic analyses reveal a relationship between WNT pathway, genes, oxidative stress metabolism and vascular calcification

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Vitamin D treatment prevents uremia-induced reductions in aortic microRNA-145 attenuating osteogenic differentiation despite hyperphosphatemia

In chronic kidney disease, systemic inflammation and high serum phosphate (P) promote the de-differentiation of vascular smooth muscle cells (VSMC) to osteoblast-like cells, increasing the propensity for medial calcification and cardiovascular mortality. Vascular microRNA-145 (miR-145) content is essential to maintain VSMC contractile phenotype. Because vitamin D induces aortic miR-145, uremia and high serum P reduce it and miR-145 directly targets osteogenic osterix in osteoblasts, this study evaluated a potential causal link between vascular miR-145 reductions and osterix-driven osteogenic differentiation and its counter-regulation by vitamin D. Studies in aortic rings from normal rats and in the rat aortic VSMC line A7r5 exposed to calcifying conditions corroborated that miR-145 reductions were associated with decreases in contractile markers and increases in osteogenic differentiation and calcium (Ca) deposition. Furthermore, miR-145 silencing enhanced Ca deposition in A7r5 cells exposed to calcifying conditions, while miR-145 overexpression attenuated it, partly through increasing α-actin levels and reducing osterix-driven osteogenic differentiation. In mice, 14 weeks after the induction of renal mass reduction, both aortic miR-145 and α-actin mRNA decreased by 80% without significant elevations in osterix or Ca deposition. Vitamin D treatment from week 8 to 14 fully prevented the reductions in aortic miR-145 and attenuated by 50% the decreases in α-actin, despite uremia-induced hyperphosphatemia. In conclusion, vitamin D was able to prevent the reductions in aortic miR-145 and α-actin content induced by uremia, reducing the alterations in vascular contractility and osteogenic differentiation despite hyperphosphatemia

Mineral and Bone Metabolism Markers and Mortality in Diabetic Patients on Haemodialysis

© The Author(s) 2023. Published by Oxford University Press on behalf of the ERA.BACKGROUND: Diabetic patients on haemodialysis have a higher risk of mortality than non-diabetic patients. The aim of this COSMOS analysis was to assess whether bone and mineral laboratory values (calcium, phosphorus, and PTH) contribute to such risk. METHODS: COSMOS is a multicentre, open-cohort, 3-year prospective study, which includes 6797 patients from 227 randomly selected dialysis centres from 20 European countries. The association between mortality and calcium, phosphate or PTH was assessed using Cox proportional hazard regression models using both penalized splines smoothing and categorization according to KDIGO guidelines. The effect modification of the association between the relative risk of mortality and serum calcium, phosphate or PTH by diabetes was assessed. RESULTS: There was a statistically significant effect modification of the association between the relative risk of mortality and serum PTH by diabetes (p = 0.011). The slope of the curve of the association between increasing values of PTH and relative risk of mortality was steeper for diabetic compared with non-diabetic patients, mainly for high levels of PTH. In addition, high serum PTH (> 9 times the normal values) was significantly associated with a higher relative risk of mortality in diabetic patients but not in non-diabetic patients (1.53[95%CI:1.07-2.19] and 1.17[95%CI:0.91-1.52]). No significant effect modification of the association between the relative risk of mortality and serum calcium or phosphate by diabetes was found (p = 0.2 and p = 0.059, respectively). CONCLUSION: The results show a different association of PTH with the relative risk of mortality in diabetic and non-diabetic patients. These findings could have relevant implications for the diagnosis and treatment of CKD-MBD.publishersversionpublishe