Cholecalciferol Supplementation Does Not Protect Against Renal Allograft Structural and Functional Deterioration: A Retrospective Study

Background. Apart from their important role in mediating calcium homeostasis, vitamin D derivatives regulate numerous vitamin D receptor-mediated renoprotective cellular functions including cell differentiation, negative regulation of inflammation, and fibrosis. Renal models of chronic kidney injury and clinical observational studies have suggested that vitamin D analogues may protect against the epithelial-to-mesenchymal transition (EMT), interstitial inflammation, and fibrosis. Methods. The aim of this retrospective study is to test whether oral supplementation with cholecalciferol (vitamin D3) between 3 and 12 months posttransplantation confers a structural and functional nephroprotection in a population of 64 renal transplant patients, using historical controls. We analyzed glomerular filtration rates using iohexol clearance, urinary procollagen III aminoterminal propeptide excretion, and epithelial phenotypic changes as markers of the EMT and Banff scores at 3 and 12 months after transplantation in 64 renal transplant recipients with or without cholecalciferol supplementation between months 3 and 12. Results. Cholecalciferol supplementation in stable renal transplant recipients did not prevent EMT, interstitial fibrosis, tubular atrophy, or renal function deterioration. Conclusion. Our results challenge the experimental data, suggesting that vitamin D-analog supplementation confers nephroprotection. These findings should be confirmed by randomized prospective studies.