The effects of dietary fermented wheat bran polysaccharides on mucosal and serum immune parameters,hepatopancreas antioxidant indicators,and immune-related gene expression of common carp (Cyprinus carpio) juveniles

Aquaculture research has focused on polysaccharides as they are among the most promising new-generation immunostimulant used to control aquatic diseases. The aim of this study was to investigate the immunomodulatory effects of fermented wheat bran polysaccharides (FWBPs) on juvenile common carp (Cyprinus carpio). Carps were fed different FWBP amounts (0%, 0.1%, 0.2%, and 0.4%) for 8 weeks and then their skin mucus and serum immune parameters, hepatopancreas antioxidant indicators, and immune-related gene expression in the intestines, kidneys, and spleen were measured. The skin mucus IgM levels significantly increased in 0.1% FWBP group, but decreased in 0.4% FWBP group. The skin mucus protease and the serum alkaline phosphatase activities increased significantly in the 0.2%, 0.1%, and 0.4% FWBP groups, respectively. The serum total Ig levels increased noticeably in the 0.1% and 0.2% FWBP groups. The highest and lowest serum lysozyme activities were observed in the 0.1% and 0.4% FWBP groups, respectively. The hepatopancreatic total superoxide dismutase activity was higher in the 0.1% FWBP group than in the control. The malondialdehyde levels decreased significantly in the 0.2% and 0.4% groups. The intestinal mRNA levels of the LZM-C and IL-10 genes were significantly higher in the 0.2% than in the 0.4% FWBP group; TNF-α was significantly upregulated in the 0.1% group. The gene expression in the kidneys did not differ significantly among the treatments, except for a significant increase in the IL-10 expression in the 0.1% treatment. Significantly elevated expression of LZM-C in 0.2% group and IL-10 in 0.1% group was observed in the spleens. TNF-α and IL-1β were significantly downregulated in the 0.4% group. These results suggest that FWBPs could be used as immunostimulant feed additives in common carp cultures.