Bupi Yishen formula against chronic kidney injury via Akkermansia muciniphila mediated group 3 innate lymphoid cells activation to repair intestinal barrier funciton

BACKGROUND: Previous clinical studies have confirmed that Bupi Yishen formula (BYF) can delay the progression of chronic kidney disease (CKD), and experimental studies have demonstrated that BYF exerts renoprotective effects in CKD models through anti-inflammatory and anti-fibrotic mechanisms. However, the fundamental pathways by which BYF produces these effects remain to be fully elucidated. PURPOSE: This study aims to investigate the potential of BYF to enhance intestinal barrier function through the modulation of gut microbiota and group 3 innate lymphoid cells (ILC3s), and to explore its effects on reducing systemic inflammation and alleviating renal fibrosis in CKD. METHODS: Mice with adenine-induced CKD were treated with oral BYF extract at two doses (15 or 30 g/kg/day). Irbesartan was used as a positive control. We examined the relationship between the renoprotective effects of BYF and changes in gut microbiota, ILC3s, retinoic acid levels, intestinal barrier function, and systemic inflammation. In addition, we conducted an antibiotic-induced gut microbiota depletion experiment to assess the dependence of BYF's effects on microbial presence. RESULTS: Oral BYF treatment reduced serum creatinine, blood urea nitrogen and urine protein levels in mice with adenine-induced CKD and alleviated renal tubular interstitial injury and fibrosis. 16S rRNA sequencing revealed that BYF modulated the gut microbiota composition, significantly enriching Akkermansia muciniphila and Barnesiella intestinihominis while suppressing Flavonifractor plautii and Turicibacter sanguinis. BYF also increased colonic ILC3 numbers, elevated retinoic acid levels, and upregulated interleukin22 (IL-22) expression, thereby improving intestinal barrier integrity and reducing serum levels of lipopolysaccharide (LPS), indoxyl sulfate, IL-1β, interferon gamma (IFN-γ), and tumor necrosis factor-α (TNF-α). However, in gut microbiota-depleted mice, BYF failed to improve kidney injury, fibrosis, ILC3s, retinoic acid, IL-22 expression, or intestinal barrier function. CONCLUSION: BYF may enhance intestinal barrier function by upregulating Akkermansia muciniphila and the ILC3s-IL-22 axis, thereby reducing toxin translocation, suppressing inflammation, alleviating renal fibrosis, and slowing CKD progression. These effects may involve activation of Akkermansia muciniphila-mediated retinoic acid synthesis, which modulates ILC3s-IL-22 signalling in mice with CKD. The breakthrough in our study lies in demonstrating that BYF, through its regulation of gut microbiota and immune cells, significantly impacts the gut-kidney axis to alleviate CKD progression.