Vitamin D modulates yellow catfish (Pelteobagrus fulvidraco) immune function in vivo and in vitro and this involves the vitamin D/VDR-type I interferon axis.

Vitamin D (VD) has been shown to regulate immune function in mammals. 1,25-dihydroxyvitamin (1,25(OH)D) is the active form of vitamin D, which is also known as calcitriol. The current study investigated the immunomodulatory effects of 1,25(OH)D on the innate immune response of yellow catfish (Pelteobagrus fulvidraco) after in vivo and in vitro immune challenge. The in vivo results showed that increasing dietary vitamin D decreased mortality, enhanced the immune protective rate, and increased serum lysozyme, catalase and SOD activities in yellow catfish infected with Edwardsiella Ictaluri (p < 0.05). The in vitro results showed that 1,25(OH)D (0, 1, 10, 100, 200 pM) dose-dependently attenuated the rate of apoptosis and production or reactive oxygen species and increased the phagocytic activity of head kidney macrophages stimulated with 10 mg/L lipopolysaccharide (LPS) and 100 mg/L of Poly(I:C) (p < 0.05). Real-time quantitative PCR results showed that increasing dietary vitamin D content in vivo and increasing the level of 1,25(OH)Din vitro partially regulated the expression of VD/VDR-type I interferon axis genes (vdr, irf-3, ifn-a, jak1, stat1, ifi56 and ifp35) after immune challenge. These results indicated that vitamin D content helped yellow catfish to resist oxidative stress and inflammation caused by immune challenge, and immunomodulation involved the VD/VDR-type I interferon action axis.