Fresh bamboo juice regulates the diversity of intestinal microflora in mice by promoting the function of ILC2 cells to mediate intestinal protection.

Background And Aim: Ulcerative colitis (UC) is a growing global health concern, with current treatments facing challenges like drug dependence and side effects. Fresh bamboo juice (FBJ), known for its antimicrobial and potential immune-modulating properties, has shown promise as a natural therapeutic agent. The present study aimed to explore the protective effects of FBJ against colitis and further analyze the changes of gut microbiota composition, metabolite profiles, and underlying immune mechanisms.

Materials And Methods: A colitis model in mice was established using DSS to investigate the effectiveness of FBJ. Intestinal tissue and fecal samples were also collected for 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS) analysis. Additionally, immunofluorescence and flow cytometry were employed to detect the proliferation and function of group 2 innate lymphoid cells (ILC2). Enzyme-linked immunosorbent assay (ELISA) was used to measure the cytokines secreted by immune cells.

Results: FBJ demonstrated significant therapeutic effects against DSS-induced colitis in mice. At the genus level, the abundance of Bacteroides, Akkermansia and unassigned bacteria in the bamboo juice group increased compared with the DSS group. In contrast, the abundance of Alloprevotella, Lactobacillus, Lachnospiraceae_NK4A136_group and Ruminococcaceae_UCG-014 significantly decreased. FBJ partially restored the balance of gut microbiota, as evidenced by the increased levels of beneficial bacteria. Metabolome analysis revealed significant alterations in fecal metabolites, including 3-Hydroxypyridine, Pyridoxine, SM(d18:1/16:0), and DL-Methionine sulfoxide were remarkably altered. Dysregulation of pathways such as Vitamin B6 metabolism, sphingolipid metabolism, and tyrosine metabolism was observed, which may contribute to protection against colitis. Flow cytometry and immunofluorescence showed a significant reduction in the proportion of ILC2 cells following FBJ treatment in the DSS group (1.82 % v.s. 3.18 %, P < 0.05). ELISA showed that the FBJ group had lower levels of IL-5, IL-6, IL-10, IL-13, IL-33, TNF-α, IFN-γ in intestinal tissue.

Conclusions: Our findings demonstrate that FBJ exerts a protective effect against colitis, primarily by modulating the intestinal flora and metabolite profiles in mice with colitis. Furthermore, the observed alterations in bacterial flora and metabolites likely affect ILC2 function and cytokine production, thereby mediating the protective effects against colitis through modulation of the immune system.