1,25-Dihydroxyvitamin D3 Negatively Regulates the Inflammatory Response to Porcine Epidemic Diarrhea Virus Infection by Inhibiting NF-κB and JAK/STAT Signaling Pathway in IPEC-J2 Porcine Epithelial Cells

Porcine epidemic diarrhea virus (PEDV) infection causes watery diarrhea and vomiting in piglets. The pathogenesis of PEDV infection is related to intestinal inflammation. It is known that 1,25-dihydroxyvitamin D3 (1,25(OH)(2)D-3) has potent anti-inflammatory activity, but it is unknown whether 1,25(OH)(2)D-3 can inhibit the PEDV-induced inflammatory response and the underlying mechanism. We used transcriptome analysis, gene and protein expression, RNA interference and overexpression, and other techniques to study the anti-inflammatory effects of 1,25(OH)(2)D-3 on PEDV infection in IPEC-J2 cells. The results showed that interleukin 19 (IL-19) and C-C motif chemokine ligand 20 (CCL20) gene expression were enhanced with the increase in PEDV infection time in IPEC-J2 cells. Interestingly, 1,25(OH)(2)D-3 supplementation obviously inhibited IL-19 and CCL20 expression induced by PEDV. Meanwhile, we also found that 1,25(OH)(2)D-3 reduced p-NF-kappa B, p-STAT1, and p-STAT3 protein levels induced by PEDV at 24 h post-infection. I kappa B alpha and SOCS3, NF-kappa B, and STAT inhibitor respectively, were increased by 1,25(OH)(2)D-3 supplementation upon PEDV infection. In addition, 1,25(OH)(2)D-3 supplementation inhibited ISG15 and MxA expression induced by PEDV. Although 1,25(OH)(2)D-3 suppressed the JAK/STAT signal pathway and antiviral gene expression, it had no significant effects on PEDV replication and IFN-alpha-induced antiviral effects. In addition, when the vitamin D receptor (VDR) was silenced by siRNA, the anti-inflammatory effect of 1,25(OH)(2)D-3 was inhibited. Meanwhile, the overexpression of VDR significantly downregulated IL-19 and CCL20 expression induced by PEDV infection. Together, our results provide powerful evidence that 1,25(OH)(2)D-3 could alleviate PEDV-induced inflammation by regulating the NF-kappa B and JAK/STAT signaling pathways through VDR. These results suggest that vitamin D could contribute to inhibiting intestinal inflammation and alleviating intestinal damage in PEDV-infected piglets, which offers new approaches for the development of nutritional strategies to prevent PEDV infection in piglets.