Vitamin D3 affects innate immune status of European sea bass (Dicentrarchus labrax L.)

The effects of vitamin D-3 dietary administration on certain innate immune parameters on the expression of immune-related genes in head-kidney (HK) and gut were investigated in European sea bass Dicentrarchus labrax. Vitamin D-3 (vD(3)) was orally administered to fish in a commercial pellet food supplemented with 0 (control); 3750; 18,750; or 37,500 U kg(-1). Furthermore, gut histology was considered. This study showed a modulation in the activities examined in fish fed with the addition of vD(3). After just 2 weeks of administration, diet supplementation with the vitamin resulted in increased phagocytic ability, while serum peroxidase content was increased in fish fed with all experimental diets after 4 weeks, no significant differences were observed in protease, anti-protease, natural haemolytic complement activities and total IgM level. At gene level, fbl and rbl transcripts were up-regulated in HK in fish fed with the highest concentration of vD(3)-supplemented diets after 4 weeks, while in the gut, an up-regulation of hep gene was observed in fish fed with the different doses of vD(3). These results suggest that vD(3) may be of great interest for immunostimulatory purposes in fish farms.