Vitamin A prevents lipopolysaccharide-induced injury on tight junctions in mice.

Vitamin A (VA) is one of the most widely used food supplements, but its molecular mechanisms largely remain elusive. Previously, we have demonstrated that VA inhibits the action of lipopolysaccharide (LPS) on intestinal epithelial barrier function and tight junction proteins using IPEC-J2 cells, one of representative intestinal cell lines as a cellular model. These exciting findings stimulated us continue to determine the effects of VA on LPS-induced damage of intestinal integrity in mice. Our results demonstrated that LPS treatment caused reductions of the mRNA levels of tight junction proteins including Zo-1, Occludin, and Claudin-1, well-known biomarkers of intestinal integrity, and these reductions were reversed by VA pretreatment. Intestinal immunofluorescent results of Claudin-1 revealed that LPS disrupted the structure of tight junction and reduced the expression of Claudin-1 at protein level, which was reversed by VA pretreatment. These results suggest that VA may exert a profound role on preventing intestinal inflammation in vivo.