RESUMO
To investigate the effects of vitamin D status on cutaneous wound healing, C57BL/6J mice were fed diets with different vitamin D levels or injected intraperitoneally with 1α,25(OH)2D3. Dorsal skin wounds were created and wound edge tissues were collected on days 4, 7, 11, and 14 postwounding. The proliferation and migration of HaCaT cells treated with shVDR or 1α,25(OH)2D3 were assessed. Vitamin D deficiency (VDD) decreased wound closure and might delay inflammatory response, shown by slower inflammatory cell infiltration, decreased IL6 and TNF expression in early phase followed by an increase later. VDD might postpone epithelial-mesenchymal transition (EMT), initially characterized by higher epithelial markers and lower mesenchymal markers, followed by opposite appearance later. Dietary vitamin D supplementation and 1α,25(OH)2D3 intervention tended to accelerate EMT. Regarding extracellular matrix (ECM), VDD appeared to reduce collagen deposition on day 4 and downregulated fibronectin, COL3A1, and MMP9 expression early, followed by an increase later, together with an initial increase and subsequent decrease in Timp1 mRNA expression. Dietary vitamin D intervention promoted fibronectin and MMP9 expression on day 4 and then downregulated their expression on day 14. TGFb1/SMAD2/3 signaling seemed to be downregulated by VDD and upregulated by 1α,25(OH)2D3. In vitro, partial inhibition of VDR by shVDR tended to inhibit HaCaT cell proliferation and migration, EMT, and TGFb1/SMAD2/3 signaling, whereas 1α,25(OH)2D3 appeared to generate opposite effects. In conclusion, VDD hindered cutaneous wound healing, potentially due to impaired inflammatory response, delayed EMT, decreased ECM, and inhibited TGFb1/SMAD2/3 pathway. Vitamin D and 1α,25(OH)2D3 tended to enhance EMT and ECM.
RESUMO
Vitamin D was found to regulate inflammatory response and angiogenesis, which were often impaired in diabetic wound healing. This study aimed to investigate the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on diabetic wound healing both in vivo and in vitro. Diabetes was induced by high-fat diet combined with streptozotocin. After four weeks of establishing diabetic mouse model, full-thickness excisional wounds were created on their dorsal skin. Then 1,25(OH)2D3 was administered via intraperitoneal injection for 14 consecutive days. Human umbilical vein endothelial cells (HUVECs) were cultured with normal glucose, high glucose, high glucose plus 1,25(OH)2D3. Cell proliferation, migration, tube formation, and expression levels of relevant pathway components were measured. Intervention with 1,25(OH)2D3 significantly increased wound closure rates of diabetic mice. During the inflammatory phase, 1,25(OH)2D3 alleviated excessive inflammation and promoted the transition of macrophages from M1 to M2 phenotype. Regarding vascular endothelial function, 1,25(OH)2D3 significantly up-regulated eNOS protein expression and inhibited Vcam-1 mRNA expression in diabetic mice (P < 0.05). As for angiogenesis, 1,25(OH)2D3 markedly increased CD31-positive area, the protein and mRNA expression of VEGF, VEGFR2, PDGF, and PDGFRß, as well as the mRNA expression of Bfgf and Egfr (P < 0.05). In vitro, 1,25(OH)2D3 restored impaired cell proliferation, migration, and tube formation induced by high-glucose, and up-regulated expression of angiogenesis-related factors. These protective effects might be mediated through PI3K/AKT/HIF-1α pathway. These findings suggested that 1,25(OH)2D3 accelerated diabetic wound healing by modulating inflammation, restoring vascular endothelial dysfunction, and promoting angiogenesis.