Vitamin D improves autoimmune diseases by inhibiting Wnt signaling pathway.

OBJECTIVE

In this study, we investigated the development of the Wnt signaling pathway in vitamin D (VitD) to improve systemic lupus erythematosus in mice to breakthrough clinical treatment approaches.

METHODS

Body weight changes were recorded during rearing. Antinuclear antibodies (ANA), anti-dsDNA, and anti-snRNP were detected in the mouse serum using an enzyme-linked immunosorbent assay. Apoptosis of Th1 and Th2 immune cells in mice was detected using flow cytometry. Reverse transcription polymerase chain reaction was used to detect the expression of T-bet, GATA3, and Wnt3a mRNA in the spleens of each group. Western blot analysis was performed to detect the expression of Wnt1, p-β-catenin, β-catenin, glycogen synthase kinsase3β (GSK-3β), Wnt3a, c-myc, and cyclin D1 protein in mice spleens. β-catenin in mice spleen was visualized using immunohistochemistry.

RESULTS

VitD did not substantial reduce the body weight of MRL/LPR mice, whereas the inhibitor did. VitD notably decreased the concentrations of ANA, anti-double-stranded DNA, and anti-snRNP in the serum of MRL/LPR mice and alleviated apoptosis of Th1 and Th2 cells. VitD markedly increased the expression of T-bet and GATA mRNA in the spleen of MRL/LPR mice and consequently increased the levels of Wnt3a and β-catenin. Western blot analysis revealed that the levels of GSK-3β, p-β-catenin, Wnt1, Wnt3a, c-myc, and cyclin D1 could be reduced by VitD, compared with MRL/LPR. Immunohistochemistry demonstrated that the expression of β-catenin was the most pronounced in the spleen of MRL/LPR mice, and the expression level of β-catenin decreased substantially after VitD intervention.

CONCLUSIONS

VitD can further inhibit the nuclear translocation of β-catenin by downregulating the expression of Wnt ligands (Wnt1 and Wnt3a), which reduces the expression of the downstream target gene cyclin D1. Systemic lupus erythematosus in mice was improved by inhibiting the activation of Wnt/β-catenin signal pathway.