Betaine attenuates LPS-induced downregulation of Occludin and Claudin-1 and restores intestinal barrier function

Abstract Background: The intestinal epithelial barrier, which works as the first line of defense between the intestinal environment and the parasitifer, once destroyed, it will cause serious inflammation or other intestinal diseases. Tight junctions (TJs) play a vital role to maintain the integrity of the epithelial barrier. Lipopolysaccharide (LPS), one of the most important inflammatory factors will downregulate specific TJ proteins including Occludin and Claudin-1 and impair integrity of the epithelial barrier. Betaine (Bet) has excellent anti-inflammatory activity but whether Bet has any effect on tight junction proteins, particularly on LPS-induced dysfunction of epithelial barriers remains unknown. Intestinal porcine epithelial cells (IPEC-J2) were used as an in vitro model, the purpose of this study is to explore the pharmacological effect of Bet on improving intestinal barrier function represented by TJ proteins.Results: The results demonstrated that Bet enhanced the expression of tight junction proteins while LPS（ 1μg /m L）downregulates the expression of these proteins. Furthermore, Bet attenuates LPS-induced decreases of tight junction proteins both shown by WB and RT-PCR. The immunofluorescent images consistently revealed that LPS induced the disruption of tight junction protein Claudin-1 and reduced its expression while Bet could reverse these alterations. Similar protective role of Bet on intestinal barrier function was observed by transepithelial electrical resistance (TEER) approach. Conclusion: In conclusion, our research demonstrated that Bet attenuated LPS-induced downregulation of Occludin and Claudin-1 and restored the intestinal barrier function.