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Ethnopharmacological Relevance: Gegen Qinlian decoction (GQD) is a traditional Chinese medicine derived from Treatise on febrile diseases and is clinically used for the treatment of acute ulcerative colitis (UC). However, the potential mechanism of GQD treatment for UC remains elusive., Aim of Study: In this study, we aimed to explore the involvement of gut microbiota-related tryptophan metabolism in mediating protective effects of GQD against intestinal barrier damage., Materials and Methods: Mice with colitis were treated with 3% dextran sulfate sodium (DSS) for 6 days. The therapeutic effects of GQD in UC mice were examined based on body weight, disease activity index (DAI), organ index, length and pathological changes in the colon. The distribution of fluorescein isothiocyanate dextran (FITC-dextran) in the intestinal tract was observed using small animal imaging, while concentration of FITC-dextran in serum was detected using a fluorescein microplate analyser. Bacterial infiltration in colon tissues was observed by fluorescence in situ hybridisation (FISH), and the bacterial load in mesenteric lymph nodes (MLNs) was further examined through bacterial culture. Subsequently, colonic goblet cells were detected using Alcian blue staining. The tight junctions of the colonic epithelium were observed using transmission electron microscopy, and the expression of tight junction proteins was detected by immunofluorescence (IF) and western blot. In addition, flow cytometry was used to analyse the proportion of interleukin-22-positive (IL-22 + ) ILC3 cells in lamina propria lymphocytes, and the content of IL-22 in colon homogenates was determined using an ELISA kit. In addition, targeted tryptophan metabolomics was used to detect the concentration of indole derivatives produced by tryptophan metabolism in faeces, and 16S rDNA was used to investigate the composition and abundance of gut microbiota-related tryptophan metabolism., Results: Administration of GQD significantly alleviated the pathological symptoms, including weight loss, increased DAI score, changes in organ index, colon shortening, and colon pathological injury in UC mice. In addition, GQD reduced the diffusion of FITC-dextran in the intestinal tract, the content of FITC-dextran in serum, and bacterial infiltration in MLNs and colon tissues. Additionally, GQD significantly increased the number of colonic goblet cells, repaired the structure of epithelial tight junctions and increased the expression of tight junction proteins. Furthermore, GQD significantly increased the proportion of IL-22 + ILC3 in the lamina propria, the expression of CYP1A1 protein in colon tissue, and the level of IL-22 in colon homogenates. However, the above protective effects of GQD were inhibited by co-administration of GQD and aryl hydrocarbon receptor (AhR) antagonist. Additionally, GQD restored the content of indole derivatives generated by tryptophan metabolism, regulated the diversity of the gut microbiota, and significantly increased the abundance of genes related to tryptophan metabolism., Conclusion: Our results confirmed that GQD repaired the damaged intestinal barrier in UC mice by regulating gut microbiota-related tryptophan metabolism and restoring the generation of indole derivatives to activate AhR-mediated IL-22 production., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Context: Chinese herb Huangqin decoction (HQD) can regulate intestinal flora in ulcerative colitis (UC) mice., Objective: Our study clarifies the mechanism of HQD in regulating the intestinal flora of UC mice., Materials and Methods: Male C57BL/6 mice were randomly divided into six groups: Control, Model (3% DSS), Sulfasalazine (500 mg/kg), HQD-L (250 mg/kg), HQD-M (500 mg/kg), and HQD-H (1000 mg/kg) groups. Measurement of body weight, colon length, DAI, and haematoxylin-eosin staining were conducted. FISH and 16S rDNA detected colonic bacterial infiltration and intestinal flora changes. The expression of RegIIIγ and PRRs (NOD2, TLR5, TLR4) were detected by FCM and WB, respectively. In addition, WB, qPCR, or IHC were used to detect the expression of NOD2, MyD88, RIP2, and NF-κB p65 in the colon. ELISA was used to determine cytokines., Results: Compared with the model group (DAI score, 2.38 ± 0.05; histological score, 4.08 ± 0.54), HQD treatment significantly reduced the DAI score (L, 2.16 ± 0.09; M, 1.45 ± 0.05; H, 1.18 ± 0.05) and histological score (L, 3.16 ± 0.82; M, 2.50 ± 0.81; H, 1.51 ± 0.76); restored the weight, the colonic length ( p  < 0.05). 16S rDNA identification showed HQD regulated the balance of intestinal flora. Moreover, HQD suppressed the expression of RegIIIγ ( p  < 0.05) and prevented colonic bacterial infiltration. Furthermore, WB results showed NOD2, and TLR4 were inhibited by HQD, especially NOD2 ( p  < 0.01). The data of WB, qPCR, and IHC demonstrated that the NOD2-dependent pathway was inhibited by HQD ( p  < 0.01)., Discussion and Conclusions: HQD (1000 mg/kg) regulates the intestinal flora of colitis mice, mainly characterized as inhibition of the NOD2-dependent pathway. These results indicate that HQD has potential.

Currently, the potential role of the alterations occurring in the liver immune system and intestinal flora in liver injury remains unknown. Our study aimed to explore the impacts of intestinal microbial barrier damage induced by ceftriaxone on liver immunity. We developed the BALB/c mice model by administering ceftriaxone. The intestinal microbial barrier damage was observed by 16S rRNA, and the pathological changes of intestines and livers were detected by H&E or transmission electron microscope. The activation of immunocytes were tested by Flow Cytometry; the expression of LPS, ALT, AST, IL-6 and TNF-α were detected by Limulus Test or ELISA. Compared to the control, the intestinal microbes significantly decreased in ceftriaxone group. Additionally, the weight of cecum contents increased, the intestinal wall became thinner and the villus in the small intestine and cecum were damaged. The expression of LPS and the ratio of liver lymphocytes were significantly increased. H&E results indicated the structures of liver arose the pathologic changes. Meanwhile, the content of serum ALT, AST, IL-6 and TNF-α increased. Collectively, our study indicates that the damages of gut microbial barrier induced by ceftriaxone prompted activation of immunocytes and release of inflammatory cytokines, which may lead to chronic inflammation in liver., (© FEMS 2020.)