Natural Products: Experimental Efficient Agents for Inflammatory Bowel Disease Therapy

β-sitosterol alleviates dextran sulfate sodium-induced experimental colitis via inhibition of NLRP3/Caspase-1/GSDMD-mediated pyroptosis

Background: Inflammation-related NLRP3/Caspase-1/GSDMD-mediated pyroptosis is involved in the progression of ulcerative colitis (UC). β-sitosterol (SIT) was reported to have anti-inflammatory effects on experimental colitis, while the regulation of SIT on pyroptosis is unclear. Therefore, the present study aimed to define the protective and healing effects of SIT on dextran sulfate sodium (DSS)-induced experimental UC rats and human epithelial colorectal adenocarcinoma cells (Caco-2) and explore the underlying mechanisms that are responsible for its effects on NLRP3/Caspase-1/GSDMD-mediated pyroptosis in UC. Methods: UC model rats were established by oral 4% DSS. Following colitis injury, the animals received SIT (doses of 50, 100, and 200 mg/kg) treatment for 2 weeks. For in vitro study, we exposed Caco-2-50 mg/mL DSS with or without SIT (concentrations of 8 and 16 μg/mL). Disease activity index (DAI) and histopathological injury were assessed in vivo. Activation proteins of nuclear factor kappa B (NF-κB) signaling axis, and tight junction-related proteins of zonula occludens-1 (ZO-1) and occludin were detected in colon tissues. TNF-α, IL-1β, and IL-18 in serum and cell supernatant were measured by enzyme-linked immunosorbent assay (ELISA). Changes in NLRP3/Caspase-1/GSDMD-mediated pyroptosis signaling pathway activation were analyzed both in tissues and cells. Results: Our findings suggested that SIT treatment attenuated the severity of 4% DSS-induced UC by protecting rats from weight and colon length loss, and macroscopic damage. SIT also reduced proinflammatory factors production (TNF-α, IL-1β, and IL-18) in serum and cell supernatant. Mechanistically, SIT downregulated the expression levels of pyroptosis-related proteins including Caspase-1, cleaved-Caspase-1, NLRP3, GSDMD, and GSDMD-N in colon tissues and Caco-2 cells. Further analysis indicated that SIT maintained the colonic barrier integrity by enhancing the protein expression of ZO-1 and occludin. Conclusion: We confirmed that SIT exerts protective and therapeutic effects on DSS-induced colitis injury by suppressing NLRP3/Caspase-1/GSDMD-mediated pyroptosis and inflammation response. These findings demonstrated that SIT could be a potential medication for UC treatment.

Polyphenols from foxtail millet bran ameliorate DSS-induced colitis by remodeling gut microbiome

INTRODUCTION

Polyphenols from plants possess the anti-inflammatory and gut microbiota modulated properties. Foxtail millet (Setaria italica L., FM) has potential medical and nutritional functions because of rich phenolic and other phytochemical components.

METHODS

Here, the study explored the effects of bound polyphenol of inner shell (BPIS) from FM bran on dextran sodium sulfate (DSS)-induced experimental colitis mice.

RESULTS

Results showed that BPIS administration effectively relieved the weight loss, decreased disease active index (DAI) scores, restrained the secretion of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β, increased anti-inflammatory cytokines IL-10, IL-4, IL-5. BPIS prevented gut barrier damage by enhancing tight junction proteins Claudin1, ZO-1 and Occludin, increasing the number of goblet cells and facilitating the gene expressions of mucin family. In addition, BPIS restored the gut microbiota composition and increased the relative abundance of commensal bacteria such as Lachnospiraceae and Rikenellaceae and restrained the growth of S24-7 and Staphylococcaceae. Concentrations of short-chain-fatty acids (SCFAs) generated by gut microbiota were elevated in BPIS treated colitis mice.

CONCLUSION

These data suggest that BPIS effectively ameliorates DSS-induced colitis by preventing intestinal barrier damage and promoting gut microbiota community.

Pectic polysaccharides ameliorate the pathology of ulcerative colitis in mice by reducing pyroptosis

Background

Ulcerative colitis (UC) is an inflammatory bowel disease which seriously affects the quality of life of patients. There has been an increasing amount of research related to the therapeutic effects and mechanisms of natural plant substances in the treatment of recurrent UC. Rauwolfia verticillata var. Hainanensis is a medicinal plant that is native to Hainan Island, China. Some studies have documented that pectic polysaccharides (PPs) from Rauvolfia inhibited the progression of colon ulcers. However, their mechanisms of action have not been established. Studies have revealed that suppressing pyroptosis can attenuate the damage of experimental colitis. However, it is unclear whether PPs from Rauvolfia verticillata inhibit inflammation through pyroptosis. This study investigated the effects and potential mechanisms of PPs extracted from Rauvolfia verticillata on experimental UC in mice.

Methods

Male C57 mice (6–8 weeks old) were allocated into the control group, the dextran sulfate sodium (DSS)-induced UC model group (DSS group), or the DSS with pectic polysaccharides treatment group (DSS + PP group). The body weights, rectal bleeding, and stool consistencies in the mice were observed, and the disease activity index (DAI) score was calculated. Colon tissues were collected for pathological analysis by histological hematoxylin and eosin (H&E) staining. The levels of caspase-1 and interleukin (IL)-1β were detected by immunohistochemistry. Pyroptosis was assessed by transmission electron microscopy.

Results

UC in mice induced by DSS resulted in decreased general physical activity and body weight, increased DAI score, significant histological changes, inhibited caspase-1 and IL-1β expression, and promoted pyroptosis. These DSS-induced changes could be partially ameliorated by administration of PP.

Conclusions

PPs exerted an ameliorative effect on DSS-induced UC in mice by reducing pyroptosis.

Ban-Lan-Gen Granule Alleviates Dextran Sulfate Sodium-Induced Chronic Relapsing Colitis in Mice via Regulating Gut Microbiota and Restoring Gut SCFA Derived-GLP-1 Production

Purpose

GLP-1 based therapy represents a new treatment option for inflammatory bowel disease. Ban-Lan-Gen (BLG) granule, a known anti-viral TCM formulation, exhibits potential anti-inflammatory activities in treating various kinds of inflammation. However, its anti-inflammatory effect on colitis and the underlying mechanisms remain unknown.

Methods

Dextran sulfate sodium (DSS)-induced chronic relapsing colitis in mice was established. The disease activity index, histological sign of damage, and levels of proinflammatory cytokines were performed to assess the protective effects of BLG. Serum GLP-1 level and colonic Gcg, GPR41 and GRP43 expression, the community compositions of gut microbiota, the levels of SCFAs in the feces and GLP-1 release from primary murine colon epithelial cells were performed to characterize the effects of BLG on gut microbiota and gut SCFA derived-GLP-1 production.

Results

BLG treatment significantly alleviated body weight loss, DAI, colon shortening, colon tissue damage, and pro-inflammatory cytokine levels of TNF-α, IL-1β and IL-6 in the colon tissues. Moreover, BLG treatment could observably restore colonic Gcg, GPR41 and GRP43 expression and serum GLP-1 level of colitic mice, as well as correct the alteration of gut microbiota in colitic mice by increasing the abundances of SCFA-producing bacteria, eg, Akkermansia and Prevotellaceae_UCG-001, and decreasing the abundances of bacteria, eg, Eubacterium_xylanophilum_group, Ruminococcaceae_UCG-014, Intestinimonas, and Oscillibacter. Furthermore, BLG treatment could markedly increase the levels of SCFAs in feces of colitic mice. In parallel, ex vivo assay also showed that and the extract of feces from BLG-treatment mice could greatly stimulate the secretion of GLP-1 from primary murine colon epithelial cells.

Conclusion

These findings suggest that the anti-colitis effects of BLG are achieved at least partly by regulating gut microbiota and restoring gut SCFA derived-GLP-1 production, and BLG has the potential to be developed as a promising agent for the treatment of chronic relapsing colitis.

Crosstalk Between Intestinal Serotonergic System and Pattern Recognition Receptors on the Microbiota-Gut-Brain Axis

Disruption of the microbiota-gut-brain axis results in a wide range of pathologies that are affected, from the brain to the intestine. Gut hormones released by enteroendocrine cells to the gastrointestinal (GI) tract are important signaling molecules within this axis. In the search for the language that allows microbiota to communicate with the gut and the brain, serotonin seems to be the most important mediator. In recent years, serotonin has emerged as a key neurotransmitter in the gut-brain axis because it largely contributes to both GI and brain physiology. In addition, intestinal microbiota are crucial in serotonin signaling, which gives more relevance to the role of the serotonin as an important mediator in microbiota-host interactions. Despite the numerous investigations focused on the gut-brain axis and the pathologies associated, little is known regarding how serotonin can mediate in the microbiota-gut-brain axis. In this review, we will mainly discuss serotonergic system modulation by microbiota as a pathway of communication between intestinal microbes and the body on the microbiota-gut-brain axis, and we explore novel therapeutic approaches for GI diseases and mental disorders.

Protective effect of mirtazapine against acetic acid-induced ulcerative colitis in rats: Role of NLRP3 inflammasome pathway

AIMS

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) that causes long-lasting inflammation on the innermost lining of the colon and rectum. Mirtazapine (MRT) is a well-known antidepressant that was proven to have anti-inflammatory activity; however, to date, its role has not been investigated in UC. The current study aimed to investigate the role and mechanism of MRT in UC.

MAIN METHOD

Acetic acid (AA) was used for UC induction, and sulfasalazine (SLZ) was used as a positive control. Rats were divided into five equal groups; as follows; normal control, AA, SLZ (received SLZ in a dose of 250 mg/kg for 14 days), MRT10 (received MRT in a dose of 10 mg/kg/day for 14 days), and MRT30 (received MRT in a dose of 30 mg/kg/day for 14 days) groups. Macroscopic and microscopic examinations together with oxidative stress parameters evaluation were done. NOD-like receptors-3 (NLRP3), caspase-1, TNF-α, and nuclear factor kappa B (NF-κB) expression together with interleukin (IL)-1β and IL-18 levels were examined.

KEY FINDING

MRT, in a dose-dependent manner, prevented the macroscopic and microscopic colonic damage and corrected the oxidative stress induced by AA. Moreover, MRT decreased the colonic tissue NLRP3 inflammasome, caspase-1, NF-κB, TNF-α expressions, IL-1β, and IL-18 levels that were elevated in colonic tissue by the AA.

SIGNIFICANCE

MRT has a dose-dependent protective effect against UC that was mediated mainly by its anti-inflammatory activity with modulation of NLRP3/caspase-1 inflammatory pathway.

Therapeutic potential of isobavachalcone, a natural flavonoid, in murine experimental colitis by inhibiting NF-κB p65

The incidence of ulcerative colitis (UC), one of the two types of inflammatory bowel disease, is increasing in many countries. Various natural products have been demonstrated with therapeutic potentials for UC. Herein, the therapeutic effects and mechanisms of isobavachalcone (IBC), a natural chalcone, were evaluated in dextran sulfate sodium (DSS)-induced colitis mice and lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The results demonstrated that IBC treatment significantly improved the clinical symptoms, assessed by the disease activity index (DAI) scores and the histological changes of the colon. The levels of myeloperoxidase (MPO), TNF-α, IL-6, IL-1β, and prostaglandin E2 (PGE2) in colon tissues were suppressed by IBC. The upregulation of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and NF-κB p65 in colon tissues were reversed by IBC as well. Furthermore, IBC significantly inhibited LPS-triggered secretion of TNF-α, IL-6, and nitrite, and nuclear translocation of NF-κB p65, in RAW264.7 cells. The luciferase reporter assay indicated that IBC significantly inhibited LPS-triggered transcription of toll-like receptor 4 (TLR4). Molecular docking results showed that the binding pocket of IBC was adjacent to Ser276 of p65-p50 heterodimer and IBC could form H-bond with Thr191. Collectively, these results demonstrated that IBC ameliorated colitis in mice possibly through inhibition of NF-κB p65.

Prevention of dextran sulfate sodium-induced mouse colitis by the fungal protein Ling Zhi-8 via promoting the barrier function of intestinal epithelial cells

The fungal immunomodulatory protein Ling Zhi-8 (LZ-8) isolated from Ganoderma lucidum (GL) regulates immune cells and inhibits tumor growth; however, the role of LZ-8 in protecting intestinal epithelial cells (IECs) is unknown. In this study, we aim to investigate the functional effect of LZ-8 on IECs. LZ-8 effectively rescued the pro-inflammatory cytokine-induced loss of tight junctions (TJs) by enhancing transepithelial electrical resistance (TEER), reducing permeability, and maintaining the distribution of TJ proteins, in Caco-2 cells. Mechanistically, LZ-8 blocked the upregulation of myosin light chain kinase (MLCK) and NF-kB activation by TLR2-mediated suppression of cytokine signaling (SOCS)-1 expression. Furthermore, LZ-8 pre-treatment reduced the pathological scores of dextran sulfate sodium (DSS)-induced colitis in mice. These results indicated that LZ-8 protected the barrier function of IECs against inflammation. Thus, LZ-8 may potentially be a novel candidate for treating inflammatory bowel disease (IBD).

Revealing mechanism of Caulis Sargentodoxae for the treatment of ulcerative colitis based on network pharmacology approach

Objective: The traditional Chinese medicine Caulis Sargentodoxae is widely used in the treatment of ulcerative colitis (UC), but the mechanism remains unknown. The present study aims to reveal its effective components, targets and pathways through network pharmacology and bioinformatics approaches.

Materials and methods: Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) was used to identify effective components. The ligand-based targets prediction was achieved through SwissTargetPrediction and TargetNet. UC-related targets were identified using Gene Expression Omnibus (GEO) data and DisGeNET. The common targets of disease and components were constructed and analyzed by PPI network. Lastly, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses are used to explain the functions of these common targets. Components-Targets-Pathways network was visualized and analyzed to further reveal the connection between the components and targets.

Results: Eight active components and 102 key targets were identified to play an important role in UC. These targets were related to regulation of protein serine/threonine kinase activity, positive regulation of cell motility, response to molecule of bacterial origin, response to toxic substance, ERK1 and ERK2 cascade, peptidyl-tyrosine modification, inositol lipid-mediated signaling, cellular response to drug, regulation of inflammatory response and leukocyte migration. Moreover, HIF-1 signaling pathway and PI3K-Akt signaling pathway were the key targets involved in UC-related signaling pathways.

Conclusion: The eight active components of Caulis Sargentodoxae mainly play a therapeutic role for UC through synergistic regulation of HIF-1 signaling pathway and PI3K-Akt signaling pathway.

Intestinal Anti-Inflammatory Activity of Terpenes in Experimental Models (2010-2020): A Review

Inflammatory bowel diseases (IBDs) refer to a group of disorders characterized by inflammation in the mucosa of the gastrointestinal tract, which mainly comprises Crohn’s disease (CD) and ulcerative colitis (UC). IBDs are characterized by inflammation of the intestinal mucosa, are highly debilitating, and are without a definitive cure. Their pathogenesis has not yet been fully elucidated; however, it is assumed that genetic, immunological, and environmental factors are involved. People affected by IBDs have relapses, and therapeutic regimens are not always able to keep symptoms in remission over the long term. Natural products emerge as an alternative for the development of new drugs; bioactive compounds are promising in the treatment of several disorders, among them those that affect the gastrointestinal tract, due to their wide structural diversity and biological activities. This review compiles 12 terpenes with intestinal anti-inflammatory activity evaluated in animal models and in vitro studies. The therapeutic approach to IBDs using terpenes acts basically to prevent oxidative stress, combat dysbiosis, restore intestinal permeability, and improve the inflammation process in different signaling pathways.

The role of medicinal products in the treatment of inflammatory bowel diseases (IBD) through inhibition of TLR4/NF-kappaB pathway

Inflammatory bowel disease (IBD) is a lifelong and recurrent disease of the gastrointestinal tract that afflicts many people in the world. Growing evidence has currently indicated that dysfunction of immune system, particularly toll-like receptors 4 (TLR4) signaling pathway dysfunction plays a pivotal part in the pathogenesis of IBD. TLR4 signaling is involved both in the pathogenesis and in the efficacy of treatment of IBD. There are some medicinal products and herbal medicines, which their role in the treatment of IBD through modulation of TLR4 signaling has been implicated. The purpose of this review article is to summarize those medicinal products and herbal medicines.

A comparison of the efficacy and safety of complementary and alternative therapies for ulcerative colitis: A protocol for systematic review and meta-analysis

BACKGROUND

The incidence of ulcerative colitis (UC) is increasing year by year worldwide, and it is listed as one of the refractory diseases by World Health Organization. In addition to typical intestinal manifestations such as abdominal pain, diarrhea, mucus, pus, and bloody stool, it can also accompany multiorgan and multisystem extraintestinal manifestations, seriously affecting the life and work of patients. Furthermore, UC patients with a tremendous psychological pressure and affects their physical and mental health. In recent years, many complementary and alternative therapies have been used for treatment of UC, but only pair-wised drugs have been evaluated in the traditional meta-analyses and some results are inconsistent. Consequently, it is essential to propose a protocol for systematic review and meta-analysis to discuss the efficacy and safety of complementary and alternative therapies in the treatment of UC.

METHODS

We will search Chinese and English databases comprehensively and systematically from the establishment of databases to May 2020, free of language or publication restrictions. All randomized controlled trials on complementary and alternative therapies for UC will be included. Two researchers will independently screen titles, abstracts, full texts, and extract data, then assess the bias risk of each study. We will conduct pairwise meta-analyses and Bayesian network meta-analyses to the relative outcomes of the efficacy and safety. Data analysis will use STATA and WinBUGs 1.4.3 software in this meta-analysis.

RESULTS

This study will evaluate the efficacy and safety of complementary and alternative therapies for UC based on changes in symptoms, clinical efficacy, quality of life and adverse events.

CONCLUSION

This study will provide evidence for whether complementary and alternative therapies are beneficial to the treatment of UC. In order to provide reliable evidence-based medicine for clinical practice.

INPLASY REGISTRATION NUMBER

INPLASY202060015.