Mulberry leaf benefits the intestinal epithelial barrier via direct anti-oxidation and indirect modulation of microbiota in pigs.

Background: Diarrhea and intestinal dysfunction commonly occur in young mammals, causing malnutrition and growth retardation in both human and livestock. As the traditional Chinese herb, mulberry leaf contains various bioactive compounds and showed several health benefits, such as regulating glucose and lipid metabolism, and modulating gut microbiota. Mulberry leaf exhibits the potential to modulate redox homeostasis and improve gut health, but the function and underlying mechanisms remains elucidative.

Purpose: To investigate the benefit of mulberry leaf on intestinal barrier in weanling pigs, illustrate the possible involvement of Keap1-Nrf2 mediated anti-oxidation and gut microbiota.

Methods: Chemical compositions of mulberry leaf powder (MLP) and mulberry leaf extract (MLE) were determined. The effects of MLP on growth performance, intestinal barrier integrity, anti-oxidative capacity, immune function and gut microbiota were evaluated in weaned pigs. The regulation of redox homeostasis by MLE and the involvement of Keap1-Nrf2 signaling were further determined in H₂O₂ induced oxidative stress (OS) model in IPEC-J2 cells via determining reactive oxygen species (ROS) production by flow cytometry and related protein abundance by western blot analysis.

Results: In weanling pigs, MLP reduced diarrhea incidence, and increased villus height, intestinal integrity and expression of tight junctions in intestinal mucosa. The improvement of intestinal barrier by MLP was associated with the enhancement in anti-oxidative capacity and the changes in gut microbiota and related short chain fatty acids production. Our study further revealed the direct regulation of MLE on tight junction expressions and ROS production to alleviate H₂O₂ induced OS in IPEC-J2 cells via the activating Keap1-Nrf2 signaling pathway.

Conclusions: Mulberry leaf in diet improved epithelial barrier via the direct anti-oxidation through the activation of Keap1-Nrf2 signaling pathway and the indirect modulation of gut microbiota in weaned pigs.