Vitamin D mitigates lipopolysaccharide-induced oxidative stress, tight junction damage and intestinal inflammatory response in yellow catfish, Pelteobagrus fulvidraco.

The present study explored the possible mitigative effects of vitamin D (VD) on lipopolysaccharide (LPS)-induced intestinal oxidative stress, inflammatory response and tight junction damage in yellow catfish, Pelteobagrus fulvidraco. Herein, four experimental groups were established by injecting yellow catfish with NaCl, LPS, VD or LPS plus VD. The results showed that LPS induced oxidative stress and that exogenous VD mitigated the adverse effects of LPS. Additionally, LPS suppressed the activity of antioxidant enzymes (Cat, Sod and Gr) and upregulated the mRNA expression of proinflammatory cytokines (Tnf-α, Il-1β, Il-8). Furthermore, the mRNA expression of "fencing" tight junctions (Claudin-1, Claudin-5, Occludin, Zo-1) was downregulated, while that of "pore-forming" tight junctions (Claudin-2, Claudin-12) was upregulated, however no effect on apoptosis genes was observed (p53, Bax, Caspase-3 and Caspase-9). These LPS-induced effects were significantly reversed by pretreatment with VD. Taken together, this study suggests that exogenous VD substantially alleviates LPS-induced intestinal inflammation by upregulating antioxidant activity, suppressing inflammation and promoting fencing tight junctions in the intestine.