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Ulcerative colitis (UC) pathogenesis is largely associated with intestinal epithelial barrier dysfunction. A therapeutic approach to UC involves the repair of damaged intestinal barrier. Our study aimed to investigate whether aryl hydrocarbon receptor (AhR) mediated the intestinal barrier repair effects of quercetin to ameliorate UC. 3% dextran sulfate sodium was used to induce colitic mice, and quercetin (25, 50, and 100 mg/kg) was administered orally for 10 days to assess the therapeutic effects. In vitro, Caco-2 cells were used to explore the effect of quercetin on tight junction protein expression and AhR activation. The results showed that quercetin alleviated colitic mice by restoring tight junctions (TJs) integrity via an AhR-dependent manner (p < 0.05). In vitro, quercetin dose-dependently elevated the expressions of TJs protein ZO-1 and Claudin1, and activated AhR by enhancing the expression of CYP1A1 and facilitating AhR nuclear translocation in Caco-2 cells (p < 0.05). While AhR antagonist CH223191 reversed the therapeutic effects of quercetin (p < 0.05) and blocked quercetin-induced AhR activation and enhancement of TJs protein (p < 0.05). In conclusion, quercetin repaired intestinal barrier dysfunction by activating AhR-mediated enhancement of TJs to alleviate UC. Our research offered new perspectives on how quercetin enhanced intestinal barrier function., (© 2023 John Wiley & Sons Ltd.)

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.)

Ethnopharmacological Relevance: Dahuang Mudan decoction (DMD) is a classic prescription for treating intestinal carbuncle from Zhang Zhongjing's "Essentials of the Golden Chamber" in the Han Dynasty. Recent studies also prove that DMD has a therapeutic effect on ulcerative colitis (UC), but its mechanism is still unclear., Aim of Study: In this study, we aim to assess the therapeutic effect of DMD on DSS-induced chronic colitis in mice and deeply expound its underlying regulative mechanism., Materials and Methods: The efficacy of DMD on mice with 2% DSS-induced chronic colitis was examined by changes in mouse body weight, DAI score, colon length changes, peripheral blood white blood cells (WBC) and red blood cells (RBC) counts, and hemoglobin (HGB) content, using mesalazine as a positive control. A small animal imaging system observed the FITC-Dextran fluorescence distribution in mice, and the contents of IL-22 and IL-17A in colon tissue homogenate supernatant and LPS in peripheral blood were detected by ELISA. Fluorescence in situ molecular hybridization and bacterial culture were used to investigate bacterial infiltration in intestinal mucosa and bacterial translocation in mesenteric lymph nodes and spleen. Mice immune function was further evaluated by analyzing the changes in spleen index, thymus index, and the ratio of peripheral blood granulocytes, monocytes, and lymphocytes. Meanwhile, the proportion of NCR + group 3 innate lymphoid cells (ILC3), NCR - ILC3, and IL-22 + ILC3 in colonic lamina propria lymphocytes of mice was detected by flow cytometry. The contents of effectors IL-22, IL-17A, and GM-CSF were detected by RT-PCR. We use cell scratching to determine the effect of DMD conditioned medium on the migration of Caco-2 cells by establishing an in vitro model of MNK-3 conditioned medium (CM) intervening Caco-2 cells. RT-PCR and WB detect the expression of tight junction ZO-1, Occludin, and Claudin-1., Results: DMD restored the body weight, colon length, peripheral blood RBC numbers, and HGB content of chronic colitis mice and reduced peripheral blood WBC and colon inflammatory cell infiltration. Moreover, DMD decreased LPS content in serum, bacterial infiltration of colonic mucosa, and bacterial translocation in spleen and mesenteric lymph nodes. Simultaneously, DMD intensified the expression of ZO-1, Occludin, and Claudin-1, the ratio of NCR + ILC3 and IL-22 + ILC3, and decreased the proportion of NCR - ILC3. In vitro studies also confirmed that the conditioned medium of DMD promoted the migration of Caco-2 cells and the expression of tight junction proteins., Conclusion: Our results confirm that DMD improves inflammation and restores intestinal epithelial function in mice with chronic colitis, and the mechanism may be related to regulating ILC3 function., 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.)

Background: Colorectal cancer is associated with ulcerative colitis (UC). The infiltration of neutrophils is the main cause of DNA damage produced by inflammation in the intestinal epithelium. Under the action of peptidyl arginine deaminase 4 (PAD4), neutrophils dissociate chromatin and form neutrophil extracellular traps (NETs), which can aggravate tissue inflammation and encourage tumor development. Although Huang Qin Decoction (HQD) was found to be useful in treating UC and was used to gradually prevent and treat digestive tract cancers, the underlying reasons were unclear., Methods: To demonstrate HQD could inhibits the initiation of colitis associated carcinogenesis by controlling NETs related inflammation, we first performed an AOM/DSS-generated colitis-associated carcinogenesis model to assess the efficacy of HQD in reducing neutrophil infiltration and anti-tumor activity. Then, using network pharmacology research, we investigated the potential mechanisms underlying those medicinal effects, as demonstrated by the detection of NETs aggregation and PAD4 expression changes in the colon., Results: HQD substantially reduced the number of colon cancers and the expression of Ki67, restored the level of intestinal tight junction protein occludin and ZO-1, and relieved the intestinal inflammation caused by TNF-α, IL-1β. At the same time, it inhibited neutrophil infiltration in the colon and improved the immunosurveillance of CD8 + T cells. The potential mechanisms of HQD intervention against UC and UC with neoplasia (UCN) were studied using network pharmacology, and 156 conjunct genes as well as numerous inflammation-related pathways were identified. Protein-protein interaction (PPI) analysis indicated that HQD inhibition of intestinal tumors might be related to the deactivation of PAD4, which was verified by the down-regulation of NETs, MPO-DNA complex levels, and PAD4 expression after HQD treatment., Conclusion: Huang Qin Decoction inhibits the initiation of colitis associated carcinogenesis by controlling PAD4-dependent neutrophil extracellular traps., Competing Interests: Declaration of Competing Interest The authors declared that they had no conflicts of interest to disclose., (Copyright © 2022. Published by Elsevier GmbH.)

Ulcerative colitis (UC) is a multifactorial, refractory chronic inflammatory disease. The primary factor leading to prolonged ulcerative colitis is the imbalance of the group 3 innate lymphoid cells (ILC3) subgroup resulting in the delayed reconstruction of damaged intestinal barrier. Previous studies show that luteolin had efficacy on UC, however, the potency of luteolin on restoring the balance of NCR - ILC3/NCR + ILC3 to repairing impaired intestinal barrier remains unclear. In this study, to investigate the potential mechanism of luteolin on ILC3 subgroup, we first evidenced that luteolin could promote transformation NCR - MNK3 to NCR + MNK3 in vitro. Then, a UC model was established in C57BL/6J mice to assess the efficacy of luteolin in restoring ILC3 subgroup balance and repairing intestinal barrier in chronic UC. Finally, the experiments in vitro validated the potential mechanism of luteolin in regulating ILC3 plasticity. The results showed that luteolin significantly alleviated the symptoms of DSS-induced UC in mice, including preventing body weight loss and decreasing the disease activity index (DAI) and intestinal damages. Additionally, luteolin increased NCR + ILC3 levels, promoted the production of IL-22 and decreased the levels of IL-17a and INF-γ in the intestine, and encourage intestinal barrier function recovery in UC mice by promoting the expression of ZO-1 and Occludin. Experiments in vitro revealed that luteolin facilitated the transformation of NCR - MNK3 to NCR + MNK3 and promoted the secretion of IL-22, which was linked to the Notch pathway. All results revealed that luteolin restored the balance of NCR - ILC3/NCR + ILC3 and contributed to repair of injured intestinal epithelium to alleviate ulcerative colitis., 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.)

The treatment of combination drugs in complex diseases has been spotlighted. Ulcerative colitis (UC) is a chronic inflammatory disease that has made progress in combination therapy. Baicalin, a flavone from Scutellaria baicalensis Georgi. (Lamiaceae), and emodin, an anthraquinone derivative from Rhei Radix et Rhizoma. (Polygonaceae), both have been reported to possess antiinflammatory activities. Our study investigated whether combined treatment with baicalin and emodin had a synergistic effect in inhibiting colitis inflammation. The results showed that baicalin combined with emodin at a lower dose had the same effect as the two drugs alone significantly alleviated the symptoms of dextran sulfate sodium (DSS)-induced colitis mice, involving the prevention of the loss of body weight and colon shortening, the decrease in the disease activity index (DAI), and intestinal damages. The combined treatment decreased the expression of CD14/TLR4/NF-κB pathway proteins and increased the expression of PPAR-γ protein in the colon of colitis mice. Further study in vitro has shown that baicalin decreased the expression of CD14, whereas emodin increased the expression of PPAR-γ, both of which inhibited the activity of NF-κB and exerted antiinflammatory effects. Furthermore, compared to the treatment using the two drugs individually, baicalin combined with emodin had more significant effects on the expression of CD14 and PPAR-γ. Therefore, emodin combined with baicalin had a synergistic effect on DSS-induced colitis., (© 2021 John Wiley & Sons Ltd.)

Objective To investigate the therapeutic effect and mechanism of paeoniflorin on dextran sulphate sodium (DSS)-induced ulcerative colitis (UC) mice. Methods C57BL/6 male mice were randomly divided into control group, model group, 600 mg/(kg.d) mesalazine treatment group, (12.5, 25, 50) mg/(kg.d) paeoniflorin treatment group, with 10 mice in each. All mice were treated with 30 g/L DSS for 5 days except the control group. Meanwhile, the mice in the other groups were orally administrated corresponding drugs for 10 days, while the mice in the control and model groups were given equivalent volumes of distilled water. Body mass, fecal characteristics and hematochezia of the mice were observed and recorded daily, and then disease activity index (DAI) was evaluated and calculated. Pathological changes in the colon were observed by HE staining. The levels of anti-flagellin antibody, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in the serum were measured by ELISA. The expression levels of Toll-like receptor 5 (TLR5), myeloid differentiation factor 88 (MyD88) and nuclear factor kappa-Bp65 (NF-κBp65) in the colon tissues were evaluated by Western blot analysis and the activation of lymphocytes in mesenteric lymph node (MLN) was detected by flow cytometry. Results Compared with the control group, DAI scores in the model group were significantly raised, the colon length was significantly shortened, and the epithelium and intestinal gland disappeared. In addition, the serum levels of anti-flagellin antibody, IL-6, TNF-α and the protein levels of TLR5, MyD88, NF-κBp65 in the colon significantly increased, and the activation of T lymphocytes in MLN went up in the model group. All symptoms above were alleviated in the mesalazine and paeoniflorin groups compared with the model group. Conclusion Paeoniflorin can attenuate UC in mice by inhibiting the expression of flagellin and TLR5, and the activation of T cells.

Ethnopharmacology Relevance: Rhubarb Peony Decoction (RPD) is a formula of traditional Chinese medicine chronicled in Jin Gui Yao Lve, commonly used to treat ulcerative colitis (UC). However, the underlying mechanism of RPD treating UC remains elusive. In our study, we investigated the therapeutic efficacy of RPD and potential mechanism involved in inhibiting dextran sulfate sodium (DSS)-induced ulcerative colitis in mice., Methods: The colitis was induced by DSS in mice for 5 days and estimated body weight loss, disease activity index (DAI) and colon length. Histological changes were observed by H&E staining. The number and abundance of gut mircrobiota were measured with 16 S rDNA sequencing. GC-MS was used to detect the concentration of short chain fatty acids (SCFAs) in cecum. Flow cytometry analyzed the proportion of Th17 and Treg cells in mesenteric lymph nodes (MLNs). IL-17A and Foxp3 in colon were determined by immunohistochemical analyses. The level of cytokine was determined by Multi-Analyte Flow Assay Kit., Results: Administration of RPD significantly alleviated the pathological changes of UC mice, involving rescued the inflammation-related reduction of colon length, ameliorated body weight loss and damaged tissue. In addition, RPD altered the gut microbiota, involving restored α diversity, increased significantly the abundance of Firmicutes and Actinobacteria, decreased the Proteobacteria and Bacteroidetes. Furthermore, the number of Butyricicoccus pullicaecorum, a butyrate-producing bacterium, were augmented obviously by RPD. Besides, RPD restored the content of SCFA in intestinal tract. Additionally, the proportion of Th17 cells and Treg cells in mesenteric lymph nodes, likewise, the expression of IL-17A and Foxp3 in colon were regulated by RPD, contributing to the restoration of Th17/Treg balance. Moreover, RPD significantly decreased the level of IL-6, TNF-α, IFNγ, IL-10, IL-17A, IL-21, IL-22 in colon, simultaneously increased Treg-related cytokine TGF-β at dose-dependently., Conclusions: These results demonstrated that RPD had effect on ulcerative colitis, which was related to regulating gut microbiota, especially Butyricicoccus pullicaecorum, and SCFAs to restore the gut Th17/Treg homeostasis., (Copyright © 2018. Published by Elsevier B.V.)