WenTongGanPi decoction alleviates diarrhea-predominant irritable bowel syndrome by improving intestinal barrier

Ethnopharmacological relevance: WenTongGanPi Decoction (WTGPD) is a representative medical practice of the Fuyang School of Traditional Chinese Medicine (TCM), which originated from the classical Lu's Guizhi method. WTGPD places emphasis on the balance and functionality of yang qi, and is effective in treating TCM symptoms related to liver qi stagnation and spleen yang deficiency. In TCM, diarrhea-predominant irritable bowel syndrome (IBS-D) is often diagnosed as liver depression and spleen deficiency, and the use of WTGPD has shown significant therapeutic effect. However, the underlying mechanism of WTGPD treating IBS-D remains unclear. Aim of the study: To explore the effect and mechanism of WTGPD in the treatment of IBS-D. Materials and methods: An IBS-D model with liver depression and spleen deficiency was constructed by chronic immobilization stress stimulation and sennae folium aqueous gavage. The impact of WTGPD on IBS-D rats was evaluated through measurements of body weight, fecal water content, and abdominal withdrawal reflex (AWR). Intestinal permeability was assessed using hematoxylin-eosin (HE), alcian blue-periodic acid schiff (AB-PAS), immunofluorescence (IF) staining, and quantitative real-time PCR (qRT-PCR). The components of WTGPD were analyzed using UPLC-Q-TOF-MS. The underlying mechanisms were investigated through network pharmacology, transcriptomics sequencing, western blot (WB), molecular docking, and 16S rRNA sequencing. Results: WTGPD treatment effectively alleviated diarrhea and abnormal pain in IBS-D rats (P P < 0.05). It enhanced the intestinal barrier function by improving colonic structure and increasing the expression of tight junction proteins (P P < 0.05). A total of 155 components were identified in WTGPD. Both network pharmacology and transcriptomics sequencing analysis highlighted MAPK as the key signaling pathway in WTGPD's anti-IBS-D effect. The WB results showed a significant decrease in p-p38, p-ERK and p-JNK expression after WTGPD treatment (P P < 0.0001). Guanosine, adenosine and hesperetin in WTGPD may be involved in regulating the phosphorylation of p38, ERK and JNK. Additionally, WTGPD significantly enhanced microbial diversity and increased the production of colonic valeric acid in IBS-D rats (P P < 0.01). Conclusion: In conclusion, our findings suggest that WTGPD can effectively alleviate IBS-D and improve intestinal barrier likely via inhibiting MAPK signal pathway and improving micobial dysbiosis.