Protective effect of Bacillus subtilis peptidoglycan on β-conglycinin-induced intestinal epithelial cells damage of juvenile carp (Cyprinus carpio)

This experiment was conducted to investigate the protective effects of different concentration of Bacillus subtilis peptidoglycan on the β-conglycinin-induced inflammatory lesions in intestinal epithelial cells of juvenile carp (Cyprinus carpio). In 24-cell microplates, the intestinal epithelial cells (IECs) of juvenile carp were primarily cultured for 72 h at 26 °C and 6% CO₂, and then the IECs were randomly divided into 6 groups with 4 replicates per group. One of the 6 groups was set as negative control group, and the other groups were all supplemented with 1.0 mg/mL β-conglycinin in culture medium in order to establish inflammatory lesions. After 24 h further culture in the same conditions, the culture medium was changed into the B. subtilis peptidoglycan culture medium with 0 (positive control group), 0.15, 0.30, 0.45 and 0.60 mg/mL, respectively. The samples were collected to measure the antioxidant and anti-inflammatory indices after 12, 24 and 36 h B. subtilis peptidoglycan culture. The results showed as follows: β-conglycinin exposure significantly decreased the activity of ASA, AHR, SOD, CAT, GPx, and increased the content of PC and the mRNA expression of inflammatory cytokines (IL-1β, IL-8, TNF-α₁, IL-10 and TGF-β). The 12, 24 and 36 hours after the peptidoglycan were given, the activity of ASA, AHR, SOD, CAT, GPx and the content of PC in the cells were decreased in a dose-dependent manner; and the mRNA levels of IL-1β, IL-8 and TNF-α1 were down-regulated and IL-10 and TGF-β were up-regulated. Different concentration of B. subtilis peptidoglycan could significantly improve the anti-oxidative activity, and increase the mRNA levels of anti-inflammation cytokine, and decrease the pro-inflammation cytokine, and inhibit the inflammatory response of the carp IECs induced by β-conglycinin.