Background: Diabetic kidney disease (DKD) remains one of the main causes of end-stage renal disease (ESRD) and mortality in diabetic patients worldwide. Vitamin D deficiency (VitDD) is one of the main consequences of different chronic kidney disease (CKD) types and is associated with rapid progression to ESRD. Nevertheless, the mechanisms that lead to this process are poorly understood. This study aimed to characterize a model of diabetic nephropathy progression in VitDD and the epithelial-mesenchymal-transition (EMT) role in these processes. Methods: Wistar Hannover rats received a diet with or without VitD before type 1 diabetes (T1D) induction. After this procedure, the rats were accompanied for 12 and 24 weeks after T1D induction and the renal function, structure, cell transdifferentiating markers and zinc finger e-box binding homeobox 1/2 (ZEB1/ZEB2) contribution to kidney damage were evaluated during the DKD progression. Results: The results showed an increase in glomerular tuft, mesangial and interstitial relative areas and renal function impairment in VitD-deficient diabetic rats compared to diabetic rats that received a VitD-containing diet. These alterations can be associated with increased expression of EMT markers, ZEB1 gene expression, ZEB2 protein expression and TGF-β1 urinary excretion. Decreased miR-200b expression, an important post-transcriptional regulator of ZEB1 and ZEB2 was also observed. Conclusion: Our data demonstrated that VitD deficiency contributes to the rapid development and progression of DKD in diabetic rats induced by increase ZEB1/ZEB2 expressions and miR-200b downregulation.

Background: Activation of the mitogen-activated protein kinase (MAPK) pathway induces uncontrolled cell proliferation in response to inflammatory stimuli. Adriamycin (ADR)-induced nephropathy (ADRN) in rats triggers MAPK activation and pro-inflammatory mechanisms by increasing cytokine secretion, similar to chronic kidney disease (CKD). Activation of the vitamin D receptor (VDR) plays a crucial role in suppressing the expression of inflammatory markers in the kidney and may contribute to reducing cellular proliferation. This study evaluated the effect of pre-treatment with paricalcitol on ADRN in renal inflammation mechanisms. Methods: Male Sprague-Dawley rats were implanted with an osmotic minipump containing activated vitamin D (paricalcitol, Zemplar, 6 ng/day) or vehicle (NaCl 0.9%). Two days after implantation, ADR (Fauldoxo, 3.5 mg/kg) or vehicle (NaCl 0.9%) was injected. The rats were divided into four experimental groups: control, n = 6; paricalcitol, n = 6; ADR, n = 7 and, ADR + paricalcitol, n = 7. Results: VDR activation was demonstrated by increased CYP24A1 in renal tissue. Paricalcitol prevented macrophage infiltration in the glomeruli, cortex, and outer medulla, prevented secretion of tumor necrosis factor-α, and interleukin-1β, increased arginase I and decreased arginase II tissue expressions, effects associated with attenuation of MAPK pathways, increased zonula occludens-1, and reduced cell proliferation associated with proliferating cell nuclear antigen expression. Paricalcitol treatment decreased the stromal cell-derived factor 1α/chemokine C-X-C receptor type 4/β-catenin pathway. Conclusions: Paricalcitol plays a renoprotective role by modulating renal inflammation and cell proliferation. These results highlight potential targets for treating CKD.

Background/Objectives: Gentamicin is one of the most effective and widely used antibiotics to treat serious infections. In addition to its bactericidal properties, gentamicin has a nephrotoxic effect that results in acute kidney injury (AKI). AKI may be intensified by hypovitaminosis D. This study evaluated the effect of hypovitaminosis D in the progression of gentamicin-induced renal injury. Methods: Male Wistar Hannover rats received a standard (SD) or a vitamin D-free diet (VitD^—) before gentamicin treatment. After that, we divided the animals into four groups: Ctrl VitD, SD diet, and saline injection; Ctrl VitD^—, VitD^— diet, and saline injection; Genta VitD, SD diet, and gentamicin injection (40 mg/kg; IM); Genta VitD^—, VitD^— diet, and gentamicin injection (40 mg/kg; IM). After the end of gentamicin treatment, we followed the animals for 5 days (protocol 1) and 30 days (protocol 2). Results: The Genta VitD group (protocol 1) presented impaired renal function. Regarding morphological analyses, the Genta VitD group presented necrotic tubules (protocol 1) and atrophied tubules (protocol 2). In the inflammatory scenario, the Genta VitD group presented an increase in the number of CD68+ cells, as well as in the levels of interleukin 1β (protocols 1 and 2). In addition, gentamicin-treated animals (protocols 1 and 2) presented an increased renal expression of vimentin and fibronectin. Despite the notable changes in functional, inflammatory, and structural parameters induced by gentamicin, hypovitaminosis D did not aggravate the renal injury in this experimental model. Conclusion: Hypovitaminosis D did not aggravate the progression of gentamicin-induced renal injury in rats.

Background Diabetic kidney disease (DKD) remains one of the main causes of end-stage renal disease (ESRD) and mortality in diabetic patients worldwide. Vitamin D deficiency (VitDD) is one of the main consequences of different chronic kidney disease (CKD) types and is associated with rapid progression to ESRD. Nevertheless, the mechanisms that lead to this process are poorly understood. The aim of study was to characterize a model of diabetic nephropathy progression in VitDD and the epithelial-mesenchymal-transition (EMT) role in these process. MethodsWistar Hannoverrats received a diet with or without VitD before type 1 diabetes (T1D) induction. After this procedure, the rats were accompanied for 12 and 24 weeks after T1D induction and the renal function, structure, cell transdifferentiation markers and zinc finger e-box binding homeobox 1/2 (ZEB1/ZEB2) contribution to kidney damage were evaluated during the DKD progression. Results The results showed increased in glomerular tuft, mesangial and interstitial relative areas and renal function impairment in VitD-deficient diabetic rats compared to diabetic rats that received VitD-containing diet. These alterations can be associated with increased expression EMT markers, ZEB1 gene expression, ZEB2 protein expression and TGF-β1 urinary excretion. Decreased miR-200b expression, an important post-transcriptional regulator of ZEB1 and ZEB2 was also observed. Conclusion Our data demonstrated that VitD deficiency contributes to rapid development and progression of DKD in diabetic rats induced by increased ZEB1/ZEB2 expressions and miR-200b downregulation.