Intestinal barrier, immunity and gut microbiota-based protective effects of Lactococcus lactis HF08 and its postbiotic derivative on aging and aging colitis mice

The prevalence and severity of gastrointestinal diseases were increased with age. In this study, the intestinal protective effects of Lactococcus lactis HF08 (HF08) and its derived postbiotic (P-HF08) on D-gal-induced aging mice and D-gal/DSS-induced aging colitis mice were investigated. In D-gal-induced aging mice, both HF08 and P-HF08 alleviated aging-related intestinal barrier dysfunction, inflammatory status, and gut microbiota disorder. The effects of probiotic HF08 were superior to those of postbiotic P-HF08, attributed to ability of HF08 to regulate the gut microbiota. However, in D-gal/DSS-induced aging colitis mice, the effects of P-HF08 on colitis surpassed that of HF08. Specifically, both HF08 and P-HF08 could reduce symptoms of age-related colitis, including reduction of lose weight, the DAI score, colonic shortening, and colon tissue damage. The inhibitory effects of P-HF08 on intestinal inflammation surpassed those of HF08, as evidenced by the levels of colon IL-6, IL-1β, and IL-10. Western blot results demonstrated that the anti-inflammatory effects of P-HF08 were attributed to the downregulation of key proteins in the TLR4/NF-κB pathway. And four potential TLR4 inhibitors were identified from HF08 metabolites (eplerenone, genistein, indoleacrylic acid, and turanose) by molecular docking. Nevertheless, HF08 could better regulate gut microbiota and metabolite in aging-related colitis than P-HF08, which was consistent with the results on aging mice. Overall, our finding revealed that when the intestinal barrier was intact (aging), probiotics showed superior regulation of intestinal microbiota, while postbiotics offered greater safety in case of intestinal barrier damage (aging colitis). This study offered a novel perspective into the applications of probiotics and their derivatives in the aging related gastrointestinal diseases adjuvant therapy.