A lychee fermentate with enriched acetate but lowered GABA attenuates DSS-induced colitis by reinforcing gut barrier function and modulating intestinal microbiota

Fermented plant-based foods have been demonstrated to exert anti-inflammatory effects. However, whether probiotic-fermented lychee exerts beneficial effects on gut barrier functions is still unclear. Using a mouse model, this study investigated the alleviative effects on adherent-invasive Escherichia coli (AIEC)-associated colitis of a lychee fermentate (LF), which was prepared by fermenting lychee fruit (LG) with four beneficial microbes. Results showed that both LG and LF alleviated colitis symptoms. Compared with LG, LF showed greater protective effects on colonic histomorphology and had lower serum TNF-alpha levels, which were linked to the increased acetate but reduced gamma-aminobutyric acid contents in LF. Interestingly, lower concentration of LF (LLF) exerted greater protective effects indicated by all parameters assessed. Microbial profiling showed that LLF led to greater community homogeneity, downregulated Escherichia-Shigella abundance, but promoted Parvibacteria that negatively correlated with IL-6 and TNF-alpha. Collectively, lychee fermentate, with desirable concentration, could be a novel functional food to promote gut barrier functions.