Protective effect of synbiotic combination of Lactobacillus plantarum SC-5 and olive oil extract tyrosol in a murine model of ulcerative colitis

BACKGROUND

Ulcerative colitisis (UC) classified as a form of inflammatory bowel diseases (IBD) characterized by chronic, nonspecific, and recurrent symptoms with a poor prognosis. Common clinical manifestations of UC include diarrhea, fecal bleeding, and abdominal pain. Even though anti-inflammatory drugs can help alleviate symptoms of IBD, their long-term use is limited due to potential side effects. Therefore, alternative approaches for the treatment and prevention of inflammation in UC are crucial.

METHODS

This study investigated the synergistic mechanism of Lactobacillus plantarum SC-5 (SC-5) and tyrosol (TY) combination (TS) in murine colitis, specifically exploring their regulatory activity on the dextran sulfate sodium (DSS)-induced inflammatory pathways (NF-κB and MAPK) and key molecular targets (tight junction protein). The effectiveness of 1 week of treatment with SC-5, TY, or TS was evaluated in a DSS-induced colitis mice model by assessing colitis morbidity and colonic mucosal injury (n = 9). To validate these findings, fecal microbiota transplantation (FMT) was performed by inoculating DSS-treated mice with the microbiota of TS-administered mice (n = 9).

RESULTS

The results demonstrated that all three treatments effectively reduced colitis morbidity and protected against DSS-induced UC. The combination treatment, TS, exhibited inhibitory effects on the DSS-induced activation of mitogen-activated protein kinase (MAPK) and negatively regulated NF-κB. Furthermore, TS maintained the integrity of the tight junction (TJ) structure by regulating the expression of zona-occludin-1 (ZO-1), Occludin, and Claudin-3 (p < 0.05). Analysis of the intestinal microbiota revealed significant differences, including a decrease in Proteus and an increase in Lactobacillus, Bifidobacterium, and Akkermansia, which supported the protective effect of TS (p < 0.05). An increase in the number of Aspergillus bacteria can cause inflammation in the intestines and lead to the formation of ulcers. Bifidobacterium and Lactobacillus can regulate the micro-ecological balance of the intestinal tract, replenish normal physiological bacteria and inhibit harmful intestinal bacteria, which can alleviate the symptoms of UC. The relative abundance of Akkermansia has been shown to be negatively associated with IBD. The FMT group exhibited alleviated colitis, excellent anti-inflammatory effects, improved colonic barrier integrity, and enrichment of bacteria such as Akkermansia (p < 0.05). These results further supported the gut microbiota-dependent mechanism of TS in ameliorating colonic inflammation.

CONCLUSION

In conclusion, the TS demonstrated a remission of colitis and amelioration of colonic inflammation in a gut microbiota-dependent manner. The findings suggest that TS could be a potential natural medicine for the protection of UC health. The above results suggest that TS can be used as a potential therapeutic agent for the clinical regulation of UC.

Aqueous M. oleifera leaf extract alleviates DSS-induced colitis in mice through suppression of inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Moringa oleifera Lam. (M. oleifera) is a perennial deciduous tree with considerable agricultural and pharmacological value. Nearly all parts of the tree are edible, and nearly all parts are used in traditional medicine. Leaves of M. oleifera have the functions of hypoglycemic (antidiabetic), anti-cancer and anti-oxidant stress, but less research pay attention to the anti-inflammatory effect of M. oleifera leaves.

AIM OF THE STUDY

Inflammatory bowel disease (IBD) is a chronic and relapsing inflammatory disorder of the gut with no ideal medication. Here, we investigated the anti-inflammatory effects of aqueous extract of M. oleifera leaves.

MATERIALS AND METHODS

Intestinal organoids and mice as in vitro and in vivo models to investigate the effects of aqueous extract of M. oleifera leaves on inflammation induced by TNF-α and dextran sulfate sodium (DSS) respectively. The expression of inflammatory cytokines and proliferation-related genes were evaluated by RT-qPCR, respectively. The compounds in the leaf extract were determined by LC/MS, and network pharmacology approach was employed to predict 54 anti-IBD potential targets of quercetin-3-galactoside (QG) and isoquercitrin (IS).

RESULTS

We found that the extract protected against damage to intestinal organoids caused by tumor necrosis factor (TNF-α), and significantly down-regulated the expression of inflammatory cytokines. The extract also suppressed the TNF-α-induced expression of Pcna, c-Myc, and c-Jun. Additionally, oral administration of the extract also ameliorated DSS-induced colon damage (colonic shortening, loss of goblet cells and overall abnormal cellularity), and inhibited the expression of inflammatory cytokines and proliferation-related genes in colitis. By LC/MS we identified nearly 2000 of the compounds in the leaf extract, of the flavonoids identified, QG and IS made up the largest percentage; both have been shown to have anti-inflammatory properties. Moreover, network pharmacology approach was employed to predict 54 anti-IBD potential targets of QG and IS. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the overlapping targets participated in response to oxidative stress and PI3K-Akt signaling pathway respectively.

CONCLUSIONS

The present study demonstrated the anti-inflammatory capability, in vitro and in vivo, of the aqueous extract of M. oleifera leaves and suggests its potential phytotherapeutic treatment for IBD.

Chicoric acid enhances the antioxidative defense system and protects against inflammation and apoptosis associated with the colitis model induced by dextran sulfate sodium in rats

Although several anticolitic drugs are available, their application is associated with numerous side effects. Chicoric acid (CA) is a hydroxycinnamic acid found naturally in chicory (Cichorium intybus), purple coneflower (Echinacea purpurea), and basil with numerous health benefits, such as antioxidative and anti-inflammatory activities. Here, the potential anticolitic efficiency of CA against dextran sulfate sodium (DSS)-induced colitis in rats was examined in rats. Animals were randomly assigned to the following five groups: control, CA (100 mg/kg body weight), DSS [(DSS); 4% w/v], CA + DSS (100 mg/kg), and the 5-aminosalicylic acid (100 mg/kg) + DSS group. The obtained data revealed that CA significantly prevented the shortening of colon length. Meanwhile, the oxidative stress-related enzymes were increased, while malondialdehyde and nitric oxide, were markedly decreased significantly by CA. The results also indicated that CA administration decreased significantly the pro-apoptogenic indices (Bax and caspase-3) and enhanced significantly Bcl-2, the anti-apoptogenic protein. Moreover, DSS caused a significant elevation of pro-inflammatory mediators, including interleukin-1β, tumor necrosis factor-α, myeloperoxidase, cyclooxygenase II, prostaglandin E2, and peroxisome proliferator-activated receptor gamma. Interestingly, these changes were significantly decreased following the CA administration. At the molecular level, CA supplementation has increased significantly the expression level of nuclear factor erythroid 2-related factor-2 (Nrf2) and decreased the expressions of nitric oxide synthase and mitogen-activated protein kinase 14. CA has been determined to significantly lessen DSS-induced colitis by activating Nrf2 and its derived antioxidant molecules and suppressing inflammation and apoptosis cascades associated with the development of colitis; suggesting that CA could be used as an alternative naturally-derived anticolitic agent.

Inhibition of NLRP3 attenuates sodium dextran sulfate-induced inflammatory bowel disease through gut microbiota regulation

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic, life-threatening inflammatory disease of gastrointestinal tissue characterized by inflammation of the gut. Recent studies have shown that gut microbiota is involved in the pathophysiology of IBD. However, it is unknown whether direct inhibition of NLR family pyrin domain containing 3 (NLRP3) inflammasome regulates IBD and alters gut microbiota.

METHODS

Here, the NLRP3 expression was evaluated in the colon of IBD subjects. Then, we investigated the effects of NLRP3 inhibition by MCC950 on the gut microbiota and IBD-like symptoms induced by dextran sulfate sodium (DSS).

RESULTS

Firstly, NLRP3 and IL-1β levels were increased in patients with IBD as compared with healthy individuals. Then, the animal experiment showed that NLRP3 inhibition by MCC950 significantly attenuated IBD-like symptoms such as diarrhea and colonic inflammation in DSS-induced mice. In addition, NLRP3 inhibition inhibited NLRP3/ASC/caspase-1/IL-1β signaling pathway in the colon, which was over-activated by DSS. Furthermore, MCC950 increased the abundance of phylum Firmicutes, decreased the abundance of phylum Bacteroidetes, and increased the Firmicutes/Bacteroidetes ratio, indicating that the inhibition of NLRP3 inflammasome could regulate the abundance of intestinal flora. According to correlation analysis, NLRP3 might produce its functional role in the regulation of oxidation indicators by changing the gut microbiota composition, especially the phylum Bacteroidota, genus Lactobacillus and species Lactobacillus reuteri.

CONCLUSIONS

This study suggests that NLRP3 inflammasome inhibition attenuates IBD-like symptoms by regulating gut microbiota, and provides a basis for the clinical application of NLRP3 as a target for the treatment of IBD.

Effect of ethyl gallate and propyl gallate on dextran sulfate sodium (DSS)-induced ulcerative colitis in C57BL/6 J mice: preventive and protective

OBJECTIVE AND DESIGN

Inflammatory bowel disease (IBD) is an idiopathic inflammatory condition of the digestive system marked by oxidative stress, leukocyte infiltration, and elevation of inflammatory mediators. In this study, we demonstrate the protective effect of ethyl gallate (EG), a phytochemical, and propyl gallate (PG), an anti-oxidant, given through normal drinking water (DW) and copper water (CW) in various combinations, which had a positive effect on the amelioration of DSS-induced ulcerative colitis in C57BL/6 J mice.

MATERIALS AND METHODS

We successfully determined the levels of proinflammatory cytokines and anti-oxidant enzymes by ELISA, tracked oxidative/nitrosative stress (RO/NS) by in vivo imaging (IVIS) using L-012 chemiluminescent probe, disease activity index (DAI), and histopathological and morphometric analysis of colon in DSS-induced colitis in a model.

RESULTS

The results revealed that oral administration of ethyl gallate and propyl gallate at a dose of 50 mg/kg considerably reduced the severity of colitis and improved both macroscopic and microscopic clinical symptoms. The level of proinflammatory cytokines (TNF-α, IL-6, IL-1β, and IFN-γ) in colonic tissue was considerably reduced in the DSS + EG-treated and DSS + PG-treated groups, compared to the DSS alone-treated group. IVIS imaging of animals from the DSS + EG and DSS + PG-treated groups showed a highly significant decrease in RO/NS species relative to the DSS control group, with the exception of the DSS + PG/CW and DSS + EG + PG/CW-treated groups. We also observed lower levels of myeloperoxidase (MPO), nitric oxide (NO), and lipid peroxidation (LPO), and restored levels of GST and superoxide dismutase (SOD) in DSS + EG-DW/CW, DSS + PG/DW, and DSS + EG + PG/DW groups compared to DSS alone-treated group. In addition, we showed that the EG, PG, and EG + PG treatment significantly reduced the DAI score, and counteracted the body weight loss and colon shortening in mice compared to DSS alone-treated group. In this 21-day study, mice were treated daily with test substances and were challenged to DSS from day-8 to 14.

CONCLUSION

Our study highlights the protective effect of ethyl gallate and propyl gallate in various combinations which, in pre-clinical animals, serve as an anti-inflammatory drug against the severe form of colitis, indicating its potential for the treatment of IBD in humans. In addition, propyl gallate was investigated for the first time in this study for its anti-colitogenic effect with normal drinking water and reduced effect with copper water.

AMPK activation alleviated DSS-induced colitis by inhibiting ferroptosis

OBJECTIVE

Ferroptosis is a newly discovered cell death mode that has been confirmed to occur in ulcerative colitis (UC) intestinal epithelial cells. Therefore, it is particularly important to find key targets to block ferroptosis.

METHODS

Human colon samples and animal models were used in this study. The ferroptosis related protein in human colon tissue was detected by immunohistochemistry. The clinical symptoms, iron abundance and lipid peroxidation level of experimental mice were measured to evaluate the role of AMPK activation in reversing ferroptosis.

RESULTS

We verified the expression difference of ferroptosis-related genes and proteins between UC patients and healthy people. Besides, we also confirmed the occurrence of colonic ferroptosis in a DSS-induced mouse model. Activation of AMPK inhibits ferroptosis in the colon, improves symptoms and prolongs lifespan in DSS-induced colitis mice.

CONCLUSION

Collectively, our results illustrated that AMPK may be an important target for the inhibition of ferroptosis, which provides a potential therapeutic strategy for colitis.

Roxadustat protect mice from DSS-induced colitis in vivo by up-regulation of TLR4

BACKGROUND

The incidence of inflammatory bowel disease (IBD) is growing in the population. At present, the etiology of inflammatory bowel disease remains unclear, and there is no effective and low-toxic therapeutic drug. The role of the PHD-HIF pathway in relieving DSS-induced colitis is gradually being explored.

METHODS

Wild-type C57BL/6 mice were used as a model of DSS-induced colitis to explore the important role of Roxadustat in alleviating DSS-induced colitis. High-throughput RNA-Seq and qRT-PCR methods were used to screen and verify the key differential genes in the colon of mice between normal saline (NS) and Roxadustat groups.

RESULTS

Roxadustat could alleviate DSS-induced colitis. Compared with the mice in the NS group, TLR4 were significantly up-regulated in the Roxadustat group. TLR4 KO mice were used to verify the role of TLR4 in the alleviation of DSS-induced colitis by Roxadustat.

CONCLUSION

Roxadustat has a repairing effect on DSS-induced colitis, and may alleviate DSS-induced colitis by targeting the TLR4 pathway and promote intestinal stem cell proliferation.

water extract attenuates dextran sulfate sodium-induced colitis by adjusting gut microbiota

Sonchus arvensisL. (SA) is a traditional Chinese food and medicine termed "Ju Mai Cai". The aim of this study was to investigate the protective effects of an aqueous extract of SA on dextran sulfate sodium (DSS) - induced colitis in mice by adjusting the diversity of gut microbiota. Male C57BL/6 mice were randomly divided into four groups: CL (control group); ML group (DSS only); SA group (SA extract); and MS group (SA extract + DSS). The protective effect of SA on ulcerative disease was estimated by several analyses (i.e., body weight loss, diarrhea, bloody stools, disease activity index scores, and hematoxylin and eosin staining). The effect of SA on gut microbiota was determined by analysis of the 16S ribosomal RNA gene sequences. The results indicated that MS significantly attenuated the body weight loss. The disease activity index scores were markedly lower in the MS group versus in the ML group. Moreover, the length of the colon was significantly improved in the MS groups versus in the ML group. Pathological changes were markedly improved following the administration of SA to mice with DSS-induced ulcerative disease. The results of Beta diversity analysis revealed that the composition of gut microbiota was significantly different between groups. Taken together, the results indicated that SA extract may prevent ulcerative colitis.

Anti-inflammatory effect and signaling mechanism of 8-shogaol and 10-shogaol in a dextran sodium sulfate-induced colitis mouse model

Ethnopharmacological relevance

Ginger (Zingiber officinale Roscoe) has been used for food and applied in Ayurvedic medicine in India for thousands of years. With a reputation for strong anti-inflammatory properties, it has been used for to treat colds, migraines, nausea, arthritis, and high blood pressure in China and Southeast Asia. The physiological activity of ginger is attributed to its functional components, including gingerol and shogaol, and their derivatives.

Aim of the study

We aimed to investigate the effects of 8- and 10-shogaol and their bioactive signaling mechanisms in a dextran sodium sulfate (DSS)-induced colitis mouse model. The anti-colitis efficacy of 6-, 8-, and 10-derivatives of gingerol and shogaol was comparatively analyzed.

Materials and methods

Colitis was induced by providing mice with drinking water containing 5% DSS (w/v) for 8 days. The 6-, 8-, and 10-derivatives of gingerol and shogaol were orally administered for two weeks at a dose of 30 mg/kg. Changes in body weight and disease activity index were measured. The levels of pro-inflammatory cytokines, iNOS and COX-2, as well as the phosphorylation of NF-κB were analyzed using ELISA, PCR, or western blotting. Mucin expression and mRNA levels were measured using alcian blue staining and PCR, respectively. The tight-junction-associated proteins occludin and ZO-1 were assessed using immunohistological staining.

Results

The 6-, 8-, and 10-derivatives of gingerol and shogaol exhibited anti-inflammatory effects by regulating NF-κB signaling. Among the compounds administered, 10-shogaol was the most effective against DSS-induced inflammation. Comparative analysis of the chemical structure showed that shogaol, a dehydrated analog of gingerol, was more effective. 6- and 10-shogaol showed similar effects on DSS-induced morphological changes in the colonic mucus layer, mucin expression, and tight junction proteins.

Conclusions

6-, 8-, and 10-Gingerol and 6-, 8-, and 10-shogaol significantly improved the clinical symptoms and intestinal epithelial barrier damage in DSS-induced colitis in mice. The derivatives effectively inhibited DSS-induced inflammation through the regulation of NF-κB signaling. Moreover, 10-shogaol showed the most potent anti-inflammatory effect among the six compounds used in this study. The results indicate that 8- and 10-shogaol, both main ingredients in ginger, may serve as therapeutic candidates for the treatment of colitis.

Albiflorin alleviates DSS-induced ulcerative colitis in mice by reducing inflammation and oxidative stress

Objectives

To clarify therapeutic potential of albiflorin and its intrinsic mechanisms against dextran sulfate sodium (DSS)-induced Ulcerative colitis (UC) mice.

Materials and Methods

Sixty male C57BL/6 mice were randomly divided into five groups: negative control, positive, albiflorin low-dose group, albiflorin high-dose group and treatment control (Salicylazosulfapyridine "SASP", 100 mg/kg) group. Acute colitis was induced in all groups except NC by administration of 3% DSS for 7 days. Albiflorin and SASP were administered via the intragastric route twice a day for 7 days. The changes of colon tissue were assessed by disease activity index (DAI), HE staining, and ELISA. Adrenodoxin expressions of UC colon tissues were evaluated by immunohistochemistry. Western blotting was performed to investigate related protein of the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways.

Results

It has been found that the albiflorin shares similar influences as the SASP in ameliorating the DSS-induced UC. The reduced DAI and alleviated colon tissue damage were observed in albiflorin intervened groups. Moreover, albiflorin significantly inhibited myeloperoxidase activities and attenuated immuno-inflammatory response and elevated Foxp3 mRNA in colon tissue. Furthermore, investigations revealed that albiflorin could inhibit adrenodoxin isoform and activate activated phosphorylated NF-κB p65 and IκBα, which consequently suppressed phosphorylated p38 MAPK, extracellular regulated protein kinase (ERK), and c-Jun N-terminal kinase (JNK).

Conclusion

These findings showed that albiflorin could alleviate DSS-induced murine colitis by activating inhibiting NF-κB and MAPK signaling pathways. It might be a potential therapeutic reagent for UC treatment.

Differential analysis of intestinal microbiota and metabolites in mice with dextran sulfate sodium-induced colitis

BACKGROUND

Intestinal micro-ecological imbalances impair the intestinal barrier and induce intestinal inflammation, for example, ulcerative colitis (UC). According to the latest research, abnormalities in intestinal microbiota structure and their metabolites play a dominant role in UC progression; in addition, they could affect the mucus barrier based on different factors. Although numerous studies have confirmed the important role of intestinal microbiota in UC pathogenesis, the intricate connection between microbiota and metabolites and mucus barrier in UC occurrence remains unclear, and correlation analyses of differential microbiota and their metabolites under UC are relatively scarce.

AIM

To reveal the differential intestinal microbiota and metabolites in UC pathogenesis and explore more sensitive biomarker compositions.

METHODS

We used the antibiotic combination method to establish intestinal pseudo-aseptic mice; afterward, dextran sulfate sodium (DSS) was applied to establish an acute experimental colitis mice model. Colitis severity, assessed based on disease activity index, colorectal length, colorectal wet weight, and histological lesions, and mucus-related staining (mucopolysaccharide alcian blue and immunofluorescence of mucin), was compared between the pseudo-aseptic and bacterial colitis mice. Finally, differential intestinal microbiota, metabolites, and their association and correlations, were analyzed by 16s rDNA sequencing in combination with non-targeted metabolomics, through gas chromatography-mass spectrometry.

RESULTS

Compared with the pseudo-aseptic mice, intestinal bacteria positive mice were more severely ill and their intestinal mucus loss was more pronounced in DSS-induced colitis (P < 0.05), suggesting that different microbiota and metabolites could cause the different degrees of colitis. Subsequently, we observed that in addition to Klebsiella, and Bacteroides, which were widely associated with colitis, Candidatus Stoquefichus, Anaerobiospirillum, Muribaculum, and Negativibacillus may be involved in protection against colitis. Furthermore, differential metabolites of the microbiota were mainly enriched in the synthesis-related pathways of key structural sequences of mucin. In combination with the mucin-related staining and immunofluorescence results, the findings indicate that the differential microbiota and their metabolites potentially regulate the composition and function of mucus under colitis.

CONCLUSION

Microbiota and their metabolites are major factors regulating the composition and function of mucus, in turn influencing the function and structure of intestinal mucus barrier under colitis. The different microbiota and metabolites identified in the present study could be novel biomarkers for colitis.

Effects of Dextran Sulfate Sodium-Induced Ulcerative Colitis on the Disposition of Tofacitinib in Rats

Tofacitinib, a Janus kinase 1 and 3 inhibitor, is mainly metabolized by CYP3A1/2 and CYP2C11 in the liver. The drug has been approved for the chronic treatment of severe ulcerative colitis, a chronic inflammatory bowel disease. This study investigated the pharmacokinetics of tofacitinib in rats with dextran sulfate sodium (DSS)-induced ulcerative colitis. After 1-min of intravenous infusion of tofacitinib (10 mg/kg), the area under the plasma concentration-time curves from time zero to time infinity (AUC) of tofacitinib significantly increased by 92.3%. The time-averaged total body clearance decreased significantly by 47.7% in DSS rats compared with control rats. After the oral administration of tofacitinib (20 mg/kg), the AUC increased by 85.5% in DSS rats. These results could be due to decreased intrinsic clearance of the drug caused by the reduction of CYP3A1/2 and CYP2C11 in the liver and intestine of DSS rats. In conclusion, ulcerative colitis inhibited CYP3A1/2 and CYP2C11 in the liver and intestines of DSS rats and slowed the metabolism of tofacitinib, resulting in increased plasma concentrations of tofacitinib in DSS rats.

Depression Exacerbates Dextran Sulfate Sodium-Induced Colitis via IRF5-Mediated Macrophage Polarization

BACKGROUND AND AIMS

Patients with inflammatory bowel disease (IBD) and concurrent depression are predisposed to severer disease activity and a worse prognosis. Macrophage polarization toward the M1 phenotype may contribute to the exacerbation of IBD with comorbid depression. Moreover, interferon regulatory factor 5 (IRF5) is involved in the pathogenesis of IBD. The aim of this study was to explore the role of IRF5 in macrophage polarization in the impact of depression upon colitis.

METHODS

Depressive-like behavior was induced by repeated forced swim stress. Colon length, disease activity index (DAI), colon morphology, histology, ultrastructure of epithelial barrier, lamina propria macrophage polarization, and expression of IRF5 were compared between DSS colitis rats with and without depressive-like behavior. IRF5 shRNA was constructed to affect the rat peritoneal macrophages polarization in vitro. After IRF5 shRNA lentivirus was introduced into colon by enema, the colitis severity, lamina propria macrophage polarization, and TNF-α, IL-1β, and IL-10 of colon tissues were measured.

RESULTS

The study found severer colonic inflammation in depressed versus non-depressed DSS-colitis rats. Depressed DSS-colitis rats exhibited smaller subepithelial macrophages size and reduced intracellular granule diversity compared with nondepressed DSS-colitis rats. Increased polarization toward the M1 phenotype, elevated expression of IRF5, and co-expression of IRF5 with CD86 were found in depressed versus nondepressed DSS-colitis rats. Lentivirus-mediated shRNA interference with IRF5 expression switched rat peritoneal macrophage polarization from the M1 to the M2 phenotype, downregulated TNF-α, IL-1β expression to a greater extent in depressed versus nondepressed colitis rats.

CONCLUSIONS

IRF5-mediated macrophage polarization may likely underlie the deterioration of DSS-induced colitis caused by depression.

Pectolinarigenin Suppresses LPS-Induced Inflammatory Response in Macrophages and Attenuates DSS-Induced Colitis by Modulating the NF-κB/Nrf2 Signaling Pathway

Pectolinarigenin (PEC), a natural flavonoid present in cirsium chanroenicum and citrus fruits, has possess the distinct pharmacological activities. However, its molecular mechanisms and pharmacological effects on intestinal illness have not been elucidated. In the present study, we investigated the potential beneficial effects of pectolinarigenin (PEC) on lipopolysaccharide (LPS)-induced macrophage cells and the dextran sulfate sodium (DSS)-induced colitis model. Our findings showed that PEC pretreatment inhibits the LPS-induced nuclear factor-kappa B (NF-κB) activation by interfering with the degradation of IκB-α. Further, increased Nrf2 protein expression was reported on PEC treated RAW 264.7 and THP1 cell lines. In addition, we revealed that PEC mediated the NF-κB/Nrf2 pathway regulation, which in turn inhibits the synthesis of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), interleukin-1beta (IL-1β), and tumor necrosis factor-alpha (TNF-α) on RAW 264.7 and THP1 cells. Furthermore, PEC dose-dependently reduced the DSS-induced inflammation in the colon by regulating NF-κB/Nrf2 signaling pathway and enhancing the myeloperoxidase (MPO) activity and redox regulators such as superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and lipid peroxidation byproduct malondialdehyde (MDA) in DSS-induced inflamed colon. Similarly, we reported the minimal pathological damages in the PEC-treated mice colon, as well as increase goblet cell population and mucin-2 production. In conclusion, our findings demonstrate that PEC reduces the DSS-induced colitis in mice by regulating the NF-κB/Nrf2 pathway. Thus, PEC might be a promising therapeutic agent for the treatment of inflammatory bowel disease.

The ROS-generating enzyme NADPH oxidase 1 modulates the colonic microbiota but offers minor protection against dextran sulfate sodium-induced low-grade colon inflammation in mice

The enzyme NADPH oxidase 1 (NOX1) is a major producer of superoxide which together with other reactive oxygen and nitrogen species (ROS/RNS) are implicated in maintaining a healthy epithelial barrier in the gut. While previous studies have indicated NOX1's involvement in microbial modulation in the small intestine, less is known about the effects of NOX1-dependent ROS/RNS formation in the colon. We investigated the role of NOX1 in the colon of NOX1 knockout (KO) and wild type (WT) mice, under mild and subclinical low-grade colon inflammation induced by 1% dextran sulfate sodium (DSS). Ex vivo imaging of ROS/RNS in the colon revealed that absence of NOX1 strongly decreased ROS/RNS production, particularly during DSS treatment. Furthermore, while absence of NOX1 did not affect disease activity, some markers of inflammation (mRNA: Tnfa, Il6, Ptgs2; protein: lipocalin 2) in the colonic mucosa tended to be higher in NOX1 KO than in WT mice following DSS treatment. Lack of NOX1 also extensively modulated the bacterial community in the colon (16S rRNA gene sequencing), where NOX1 KO mice were characterized mainly by lower α-diversity (richness and evenness), higher abundance of Firmicutes, Akkermansia, and Oscillibacter, and lower abundance of Bacteroidetes and Alistipes. Together, our data suggest that NOX1 is pivotal for colonic ROS/RNS production in mice both during steady-state (i.e., no DSS treatment) and during 1% DSS-induced low-grade inflammation and for modulation of the colonic microbiota, with potential beneficial consequences for intestinal health.

NLRP3 Inflammasome Inhibitor OLT1177 Suppresses Onset of Inflammation in Mice with Dextran Sulfate Sodium-Induced Colitis

BACKGROUND AND AIMS

NLRP3 inflammasomes have been reported to have a key role in the initiation and perpetuation of inflammatory bowel diseases (IBD). Here we investigated the effects of OLT1177, a selective inhibitor of NLRP3 inflammasomes, in mice with dextran sulfate sodium (DSS)-induced colitis.

METHODS

C57BL/6J mice were given drinking water containing 3% DSS for 5 days. OLT1177 was administered for 5 days during the induction phase (simultaneously with DSS treatment) or the recovery phase (after the DSS treatment ended). The body weight and disease activity index were monitored daily. The mice were sacrificed 10 days after the start of the experiment, and the severity of inflammation in the colon was determined based on histological and biochemical analyses.

RESULTS

Administration of OLT1177 during the induction phase effectively suppressed DSS colitis in terms of weight loss, disease activity index, histological score, and expression of inflammatory cytokines compared to the DSS group. In contrast, OLT1177 administration during the recovery phase did not significantly affect the colitis disease course or the results of histological analyses.

CONCLUSIONS

OLT1177 was effective in preventing the onset of DSS colitis in mice. These results could guide the use of OLT1177 as a therapy for human IBD.

Minimally invasive in vivo endoscopic monitoring of dextran sulfate sodium-induced murine colitis

Ulcerative colitis (UC) is a gastrointestinal, autoimmune disease that causes ulceration and inflammation of the colon with an incidence of 10 out of every 100,000 people in North America and Western Europe. Though the specific cause is unknown, several studies have demonstrated that inflammatory cells as well as environmental variables, genetics, and lifestyle behaviors can play a role in the long-term inflammatory response. Researchers have commonly used immunohistochemistry, western blotting and gene sequencing to establish the cellular processes behind UC relapse and remission. However, because these destructive methods necessitate the removal of a sample, they can only be used on non-living tissues. The use of minimally invasive approaches to evaluate the in vivo, longitudinal effects of UC on the mucosa in the colon is gaining popularity among clinicians and researchers. We have created a dextran sulfate sodium-induced model of UC in C57 mice based on the work of Wirtz et al., and a minimally invasive imaging modality to explore the changes in mucosal tissue during "active" and "in remission" UC. Briefly, C57 mice were given dextran sulfate sodium (DSS) dissolved in water in 5-day cycles with a remission/recovery period of 10 days. After 7 days post-DSS treatment and 7 days post-recovery, mice were anesthetized and exploratory endoscopies were performed to assess the mucosal changes that occur during the "active" and "remission" periods of UC. Value of protocol:•Minimally invasive induction of ulcerative colitis in a murine mouse model.•Minimally invasive longitudinal monitoring of "active" and "in remission" ulcerative colitis.•Our endoscopic based imaging modality can be used to validate the induction of ulcerative colitis and the potential treatment response for pre-clinical trials.

Rapid and sensitive detection of dextran sulfate sodium based on supramolecular self-assembly of a perylene diimide derivative in aqueous solution

Dextran sulfate sodium (DSS) is a heparin polysaccharide, whose overuse would cause many adverse effects, such as stiff and painful joints and loss of hair. It is crucial to search after a rapid and accurate approach for the determination of DSS in the clinical treatment and diagnosis. Regrettably, there are few literatures about analytical methods for detecting DSS at present. In this research, a sensitive and selective method for detecting DSS based on the hydrosoluble perylene diimide (PDI) derivative was established in pure aqueous solution. The sensing mechanism and performance of PDI-PdEC were systematically investigated by ultraviolet and fluorescence spectroscopy. Non-covalent interactions between DSS and PDI-PdEC, like π-π stacking, electrostatic and hydrophobic interaction, promote the aggregation of PDI-PdEC and form supramolecular aggregates, which realize the sensitive and rapid detection of DSS in aqueous system. The detection limit for DSS is as low as 5.51 ng/mL and the linear range is 20-500 ng/mL. Furthermore, this probe was triumphantly applied in the detecting of DSS in serum. To the best of our knowledge, this is the first fluorescent probe for detecting DSS in aqueous media. We consider that our study will not only broaden the range of applications of perylene diimide fluorescent sensors, but also provide valuable reference for the design of new sensors for the rapid determination method of DSS.

o-Aminoazotoluene, 7,12-dimethylbenz[a]anthracene, and N-ethyl-N-nitrosourea, which are mutagenic but not carcinogenic in the colon, rapidly induce colonic tumors in mice with dextran sulfate sodium-induced colitis

BACKGROUND

Several rodent models with chemically induced colon cancer have been developed. Among these models, dextran sulfate sodium (DSS), a colitis inducer, combined with azoxymethane as a colon mutagenic carcinogen, is commonly used. We previously reported that although benzo [a] pyrene (BP) is mutagenic but not carcinogenic in the colon, it rapidly develops colon tumors at a high incidence/multiplicity after treatment with DSS. In the present study, we examined whether other colon-mutagenic non-carcinogens (CMNCs) induced colon tumors after treatment with DSS.

RESULTS

o-Aminoazotoluene, 7,12-dimethylbenz[a]anthracene, and N-ethyl-N-nitrosourea were selected as CMNCs. Male CD2F1 mice were orally administered CMNC for 5 consecutive days. After a 9-day dose-free period, mice were treated with 4% DSS in drinking water for 1 week. Three months after DSS treatment, colon samples were collected for histopathology and β-catenin immunohistochemistry analyses. All CMNCs in combination with DSS induced colonic adenocarcinomas at a high incidence/multiplicity in the distal and middle parts of the colon, coinciding with the location of colitis. Unlike in normal cells where β-catenin is exclusively located on the cell membrane, in adenocarcinoma cells, it was translocated to both the nucleus and cytoplasm or only to cytoplasm. The translocation of β-catenin is closely associated with colon carcinogenesis in rodents and humans. No colonic tumors or dysplastic lesions were found after exposure to either CMNC or DSS alone.

CONCLUSION

We provided further evidence clearly showing that CMNCs can rapidly induce colonic tumors in mice with DSS-induced colitis, even if they are not colonic carcinogens.

Periplaneta americana extract ameliorates dextran sulfate sodium-induced ulcerative colitis via immunoregulatory and PI3K/AKT/NF-κB signaling pathways

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) with a low cure rate. Periplaneta americana is a traditional American Cockroach and reportedly has potential therapeutic roles for UC treatment; however, its mechanisms remain unclear. To address this, we investigated the therapeutic effects and underlying molecular mechanisms of Ento-A, a Periplaneta americana extract, in a dextran sulfate sodium (DSS)-induced chronic and recurrent UC mouse model. Ento-A treatment decreased pro-inflammatory cytokine secretion, disease activity index (DAI), colon mucosa damage index (CMDI), histopathological scores (HS), and increased colon length. Additionally, Ento-A effectively increased interleukin-4 (IL-4), and forkhead transcription factor protein 3 (Foxp3) expression levels, while it abated interferon-γ (IFN-γ) and IL-17 levels in spleen lymphocytes. Conversely, in mesenteric lymph nodes, IL-4 and Foxp3 expression were decreased, while IFN-γ and IL-17 expression was increased. Furthermore, Ento-A blocked p-PI3K, p-AKT,*and p-NF-κB activation. In conclusion, Ento-A improved UC symptoms and exerted therapeutic effects by regulating immune responses and inhibiting PI3K/AKT/NF-κB signaling.

Metabolomic and transcriptomic responses of mouse testis to the dextran sulfate sodium induced colitis

Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis, are widespread in developed countries and gradually increasing in developing countries. Evidences showed that man with CD has a decrease of serum testosterone, but how IBD take effects on testicular testosterone synthesis is not well elucidated. To investigate the effects of IBD on testis, we analyzed testicular metabolome and transcriptome data of the dextran sulfate sodium (DSS) induced IBD mice. As a result, metabolomic data showed that DSS indeed induced androgen decrease in mouse testis. Correspondingly, androgen synthesis associated genes, especially Lhcgr, were down-regulated in DSS testis. From the metabolomic data, we found vitamin intake associated metabolites vitamin B2 and pyridoxamine were significantly decreased, whereas fatty acid metabolism associated molecules N-lauroylglycine and N-decanoylglycine were increased in DSS testis. In addition, we found 8-hydroxy-deoxyguanosine, a DNA oxidative damage marker, and 8-oxoguanine, a molecule responsible for DNA damage repair, were also changed in DSS testis. Simultaneously, our data also showed that DSS up-regulated the expression of meiosis initiation associated gene Stra8 and oxygen transport associated genes in testis. In summary, these results depicted the complex effects of colitis on testis. These metabolites and transcripts changed in DSS testis could be used as potential targets for IBD treatment or symptom relieve.

Dextran sulfate sodium-induced colitis in C57BL/6J mice increases their susceptibility to chronic unpredictable mild stress that induces depressive-like behavior

AIMS

In patients with colitis, the high comorbidity of depressive disorders is well-known, but the detailed mechanisms remain unresolved. In this study, we examined whether colitis induced by dextran sulfate sodium (DSS) increased the susceptibility to chronic unpredictable mild stress (CUMS) in C57BL/6J mice with resilience to CUMS.

MAIN METHODS

To induce experimental colitis and depressive-like behaviors, male 7-weeks old C57BL/6J mice were administered ad libitum 1% DSS solution for 11 days, and subjected to various mild stressors in a chronic, inevitable and unpredictable way according to a random schedule for 21 days, respectively.

KEY FINDINGS

In naïve mice exposed to CUMS, their immobility times in a forced swim (FS) test were almost equal to those in control mice. The DSS administration to naïve mice induced colitis without depressive-like behavior, and at 18 days after termination of the DSS administration, the colitis had recovered to control levels, while altered diversity and composition of bacterial genera such as Bacteroides spp., Alistipes spp., etc., were found in the gut microbiota. Exposure of mice with DSS-induced colitis to CUMS (DSS + CUMS) significantly increased the immobility times in the FS test. In the gut microbiota of DSS + CUMS mice, the alteration profile of the relative abundance of bacterial genera differed from in the DSS ones.

SIGNIFICANCE

These findings indicate that mice with colitis exhibit increased susceptibility to psychological stress, resulting in induction of depressive-like behavior, and this might be due, at least in part, to altered characteristics of the gut microbiota.

Epithelial Cell-specific Deletion of Microsomal Prostaglandin E Synthase-1 Does Not Influence Colon Tumor Development in Mice

Activation of the COX-2/microsomal prostaglandin E synthase-1 (mPGES-1)/prostaglandin E₂ (PGE₂) signaling axis is a hallmark of many cancers, including colorectal cancer, prompting the implementation of prevention strategies targeting COX-2 activity. We have previously shown that targeting the downstream terminal PGE₂ synthase, mPGES-1 (Ptges), specifically reduces inducible PGE₂ formation without disrupting synthesis of other essential prostanoids, thereby conferring dramatic cancer protection against colon carcinogenesis in multiple mouse models. In order to accelerate its development as a viable drug target, and to better understand the mechanisms by which PGE₂ influences colon carcinogenesis, we recently developed a conditional Ptges knockout mouse model (cKO). To evaluate the functional role of Ptges directly within the colonic epithelia, cKO mice were crossed with carbonic anhydrase 1 (Car1)-Cre mice (cKO.Car1), and colon tumors were induced using the azoxymethane/dextran sodium sulfate protocol. Unexpectedly, epithelial-specific blockade of Ptges failed to protect mice against colon tumor development. Further studies using the cKO mouse model will be necessary to pinpoint the cell type-specific location of mPGES-1 and its control of inducible PGE₂ formation that drives tumor formation in the colon.

Potential Role of Heme Oxygenase-1 in the Resolution of Experimentally Induced Colitis through Regulation of Macrophage Polarization

Background/Aims

Heme oxygenase-1 (HO-1) plays a central role in cellular defense against inflammatory insults, and its induction in macrophages potentiates their efferocytic activity. In this study, we explored the potential role of macrophage HO-1 in the resolution of experimentally induced colitis.

Methods

To induce colitis, male C57BL/6 mice were treated with 2% dextran sulfate sodium (DSS) in the drinking water for 7 days. To investigate efferocytosis, apoptotic colon epithelial CCD 841 CoN cells were coincubated with bone marrow-derived macrophages (BMDMs).

Results

Administration of the HO-1 inhibitor zinc protoporphyrin IX (ZnPP) blunted the resolution of DSS-induced intestinal inflammation and expression of the proresolving M2 macrophage marker CD206. BMDMs treated with apoptotic colonic epithelial cells showed significantly elevated expression of HO-1 and its regulator Nrf2. Under the same experimental conditions, the proportion of CD206-expressing macrophages was also enhanced. ZnPP treatment abrogated the upregulation of CD206 expression in BMDMs engulfing apoptotic colonic epithelial cells. This result was verified with BMDMs isolated from HO-1-knockout mice. BMDMs, when stimulated with lipopolysaccharide, exhibited increased expression of CD86, a marker of M1 macrophages. Coculture of lipopolysaccharide-stimulated BMDMs with apoptotic colonic epithelial cell debris dampened the expression of CD86 as well as the pro-inflammatory cytokines in an HO-1-dependent manner. Genetic ablation as well as pharmacologic inhibition of HO-1 significantly reduced the proportion of efferocytic BMDMs expressing the scavenger receptor CD36.

Conclusions

HO-1 plays a key role in the resolution of experimentally induced colitis by modulating the polarization of macrophages.

Selection strategy of dextran sulfate sodium-induced acute or chronic colitis mouse models based on gut microbial profile

BACKGROUND

Dextran sulfate sodium (DSS) replicates ulcerative colitis (UC)-like colitis in murine models. However, the microbial characteristics of DSS-triggered colitis require further clarification. To analyze the changes in gut microbiota associated with DSS-induced acute and chronic colitis.

METHODS

Acute colitis was induced in mice by administering 3% DSS for 1 week in the drinking water, and chronic colitis was induced by supplementing drinking water with 2.5% DSS every other week for 5 weeks. Control groups received the same drinking water without DSS supplementation. The histopathological score and length of the colons, and disease activity index (DAI) were evaluated to confirm the presence of experimental colitis. Intestinal microbiota was profiled by 16S rDNA sequencing of cecal content.

RESULTS

Mice with both acute and chronic DSS-triggered colitis had significantly higher DAI and colon histopathological scores in contrast to the control groups (P < 0.0001, P < 0.0001), and the colon was remarkably shortened (P < 0.0001, P < 0.0001). The gut microbiota α-diversity was partly downregulated in both acute and chronic colitis groups in contrast to their respective control groups (Pielou index P = 0.0022, P = 0.0649; Shannon index P = 0.0022, P = 0.0931). The reduction in the Pielou and Shannon indices were more obvious in mice with acute colitis (P = 0.0022, P = 0.0043). The relative abundance of Bacteroides and Turicibacter was increased (all P < 0.05), while that of Lachnospiraceae, Ruminococcaceae, Ruminiclostridium, Rikenella, Alistipes, Alloprevotella, and Butyricicoccus was significantly decreased after acute DSS induction (all P < 0.05). The relative abundance of Bacteroides, Akkermansia, Helicobacter, Parabacteroides, Erysipelatoclostridium, Turicibacter and Romboutsia was also markedly increased (all P < 0.05), and that of Lachnospiraceae_NK4A136_group, Alistipes, Enterorhabdus, Prevotellaceae_UCG-001, Butyricicoccus, Ruminiclostridium_6, Muribaculum, Ruminococcaceae_NK4A214_group, Family_XIII_UCG-001 and Flavonifractor was significantly decreased after chronic DSS induction (all P < 0.05).

CONCLUSION

DSS-induced acute and chronic colitis demonstrated similar symptoms and histopathological changes. The changes in the gut microbiota of the acute colitis model were closer to that observed in UC. The acute colitis model had greater abundance of SCFAs-producing bacteria and lower α-diversity compared to the chronic colitis model.

Severe steatosis and mild colitis are important for the early occurrence of hepatocellular carcinoma

The number of patients with non-alcoholic steatohepatitis (NASH) and inflammatory bowel disease (IBD) is increasing. This study elucidates the effect of both NASH and IBD on hepatocellular carcinoma (HCC) using a mouse model combining NASH and IBD. The melanocortin 4 receptor-deficient (Mc4r-KO) mice were divided into four groups with or without a high-fat diet (HFD) and with or without dextran sulfate sodium (DSS) to induce colitis, and the differences in liver damage and occurrence of HCC were analyzed. In the HFD + DSS group, the body weight, liver weight/body weight ratio, and serum levels of albumin and alanine aminotransferase were significantly lower than those in the HFD group. We further found that steatosis was significantly lower and lobular inflammation was significantly higher in the HFD + DSS group than those in the HFD group, and that individual steatosis and lobular inflammation state in the HFD + DSS mice varied. We detected HCC only in the HFD + DSS group, and mice with severe steatosis and mild colitis were found to be at high risk of HCC. Presently, the prediction of HCC is very difficult. In some cases, severe colitis reverses the fat accumulation due to appetite loss. Our findings clearly showed that severe steatohepatitis and mild colitis are simultaneously essential for the occurrence of HCC in patients with NASH and IBD.

Lactobacillus paracasei R3 protects against dextran sulfate sodium (DSS)-induced colitis in mice via regulating Th17/Treg cell balance

Inflammatory bowel diseases (IBD), mainly comprising ulcerative colitis (UC) and Crohn's Disease, are most often a polygenic disorder with contributions from the intestinal microbiome, defects in barrier function, and dysregulated host responses to microbial stimulation. Strategies that target the microbiota have emerged as potential therapies and, of these, probiotics have gained the greatest attention. Herein, we isolated a strain of Lactobacillus paracasei R3 (L.p R3) with strong biofilm formation ability from infant feces. Interestingly, we also found L.p R3 strain can ameliorate the general symptoms of murine colitis, alleviate inflammatory cell infiltration and inhibit Th17 while promote Treg function in murine dextran sulfate sodium (DSS)-induced colitis. Overall, this study suggested that L.p R3 strain significantly improves the symptoms and the pathological damage of mice with colitis and influences the immune function by regulating Th17/Treg cell balance in DSS-induced colitis in mice.

Lactobacillus paracasei R3 protects against dextran sulfate sodium (DSS)-induced colitis in mice via regulating Th17/Treg cell balance

Inflammatory bowel diseases (IBD), mainly comprising ulcerative colitis (UC) and Crohn's Disease, are most often a polygenic disorder with contributions from the intestinal microbiome, defects in barrier function, and dysregulated host responses to microbial stimulation. Strategies that target the microbiota have emerged as potential therapies and, of these, probiotics have gained the greatest attention. Herein, we isolated a strain of Lactobacillus paracasei R3 (L.p R3) with strong biofilm formation ability from infant feces. Interestingly, we also found L.p R3 strain can ameliorate the general symptoms of murine colitis, alleviate inflammatory cell infiltration and inhibit Th17 while promote Treg function in murine dextran sulfate sodium (DSS)-induced colitis. Overall, this study suggested that L.p R3 strain significantly improves the symptoms and the pathological damage of mice with colitis and influences the immune function by regulating Th17/Treg cell balance in DSS-induced colitis in mice.

Lactobacillus paracasei R3 protects against dextran sulfate sodium (DSS)-induced colitis in mice via regulating Th17/Treg cell balance

Inflammatory bowel diseases (IBD), mainly comprising ulcerative colitis (UC) and Crohn's Disease, are most often a polygenic disorder with contributions from the intestinal microbiome, defects in barrier function, and dysregulated host responses to microbial stimulation. Strategies that target the microbiota have emerged as potential therapies and, of these, probiotics have gained the greatest attention. Herein, we isolated a strain of Lactobacillus paracasei R3 (L.p R3) with strong biofilm formation ability from infant feces. Interestingly, we also found L.p R3 strain can ameliorate the general symptoms of murine colitis, alleviate inflammatory cell infiltration and inhibit Th17 while promote Treg function in murine dextran sulfate sodium (DSS)-induced colitis. Overall, this study suggested that L.p R3 strain significantly improves the symptoms and the pathological damage of mice with colitis and influences the immune function by regulating Th17/Treg cell balance in DSS-induced colitis in mice.

Induction of colorectal carcinogenesis in the C57BL/6J and A/J mouse strains with a reduced DSS dose in the AOM/DSS model

Background

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide and thus mouse models of CRC are of significant value to study the pathogenesis. The Azoxymethane/Dextran sulfate sodium (AOM/DSS) model is a widely used, robust initiation-promotion model for chemical induction of colitis-associated CRC in rodents. However, the dosage of chemicals, treatment regimens and outcome measures vary greatly among studies employing this model. Thus, the aim of this study was to examine an AOM/DSS model involving a reduced (1%) dose of DSS for induction of carcinogenesis in A/J and C57BL/6J (B6) mice.

Results

We show that colonic preneoplastic lesions can be reliably detected in A/J and B6 mice by use of a AOM/DSS model involving a single injection of 10 mg/kg AOM followed by three 7-day cycles of a low-dose (1%) DSS administration. Supporting existing evidence of A/J mice exhibiting higher susceptibility to AOM than B6 mice, our AOM/DSS-treated A/J mice developed the highest number of large colonic lesions. Clinical symptoms in both strains subjected to the AOM/DSS treatment did not persist in-between treatment cycles, demonstrating that the animals tolerated the treatment well.

Conclusions

Our findings suggest that a reduced dose of DSS in the AOM/DSS model can be considered in future studies of early phase colorectal carcinogenesis in the A/J and B6 mouse strains using preneoplastic lesions as an outcome measure, and that such regimen may reduce the risk of early trial terminations to accommodate human endpoints. Overall, our data emphasize the importance of devoting attention towards choice of protocol, outcome measures and mouse strain in studies of CRC in mice according to the study purpose.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42826-021-00096-y.

A New Rat Model of Pouchitis After Proctocolectomy and Ileal Pouch-Anal Anastomosis Using 2,4,6-Trinitrobenzene Sulfonic Acid

BACKGROUND

Pouchitis is a common complication after ileal pouch-anal anastomosis (IPAA) in patients with ulcerative colitis. However, an ideal model remains lacking. Therefore, we aimed to establish an appropriate model resembling human pouchitis.

METHODS

Sprague-Dawley rats were randomly assigned to five groups: TNBS group, DSS group, NS group (following IPAA procedure, administrated with TNBS enema, DSS orally, normal saline enema, respectively), NI group (underwent IPAA), and sham group (underwent switch abdominal surgery). General status, weight change, hematochezia, and fecal scores were recorded. Fecal microbiota were counted under a microscope and analyzed by 16S rRNA gene high-throughput sequencing. Specimens of ileal pouch and small intestine (proximal, mid, distal) were collected to evaluate myeloperoxidase and occludin expression by immunohistochemistry and mRNA expression of pro-inflammatory markers by PCR.

RESULTS

General status, hematochezia, fecal score, and increased mRNA expression of interleukin-6 and TNF-α in the TNBS group were similar to those in the DSS group, whereas the TNBS-induced model displayed a more stable weight change and more serious dysbacteriosis, not only was fecal bacterial diversity reduced, the dominant microbiota was altered. Histopathology scores of the distal small intestine in the TNBS group were lower compared with those in the DSS group (P < 0.05). A significant difference in myeloperoxidase and occludin expression in the small intestine was also detected between the TNBS and DSS groups.

CONCLUSIONS

Our model mimicked the characteristics of human pouchitis and avoided potential side effects in the small intestine, and thus could be employed for further research.

Synbiotics administration leads to attenuated mucosal inflammatory neutrophil infiltration and increased hematocrit in experimental ulcerative colitis

Objective

The objective of the study was to estimate the effects of synbiotics on laboratory, macroscopic, and histopathologic features in dextran sulfate sodium (DSS) experimental colitis.

Materials and methods

A total of 40 Wistar rats received 5% of DSS in their drinking water for 8 days to induce ulcerative colitis (UC). Eight rats were sacrificed to confirm the presence of UC. The remaining rats were randomly assigned to two groups: the synbiotics group, which received synbiotics once per day and the control group, which received tap water for another 8 days.

Results

On the 8^th day of DSS administration animals developed UC with bloody diarrhea. In the majority of the hematologic variables studied (hemoglobin [HB], red blood cells, platelets, mean corpuscular volume, and mean corpuscular HB), in bodyweight and histopathologic colitis score there was no significant difference between groups. However, the synbiotics group, compared to control, presented a significantly greater colon length on the 4^th day, significantly increased hematocrit (HT) on the 8^th day, and a significantly decreased number of myeloperoxidase positive cells on the 8^th day. Furthermore, there was a trend toward histopathological and clinical improvement.

Conclusions

Administration of synbiotics in the experimental UC results in an attenuation of mucosal inflammatory neutrophil infiltration and an increase in HT.

Ethanol extract of Centella asiatica alleviated dextran sulfate sodium-induced colitis: Restoration on mucosa barrier and gut microbiota homeostasis

ETHNOPHARMACOLOGICAL RELEVANCE

Ulcerative colitis (UC) is a relapsing inflammatory disease that still demands for effective remedies due to various adverse effects of the current principal treatments. Centella asiatica is a traditional medical herb with long application history in anti-inflammation.

AIM OF THE STUDY

To explore the anti-inflammatory effect and possible mechanism of C. asiatica ethanol extract (CA) in a murine colitis model induced by dextran sulfate sodium (DSS).

MATERIALS AND METHODS

CA was analyzed by high performance liquid chromatograph (HPLC). The colitis model was induced by free access to 3% DSS in distilled water for 7 days. CA (100, 200, and 400 mg/kg) and 5-aminosalicylic acid (5-ASA, 400 mg/kg) were administrated by gavage during the 7-day DSS challenge. At the end of experiment, mice were sacrificed and the brain, colon and cecum contents were harvested for analysis. Colitis was evaluated by disease activity index (DAI), colon length and colon lesion macroscopic score with hematoxylin-eosin staining. Myeloperoxidase (MPO) activity in colon and 5-hydroxytryptamine (5-HT) in brain were determined by ELISA. Tight junction protein expressions (ZO-1, E-Cadherin, Claudin-1) and c-Kit in colon were assessed by western blot and immunohistochemistry, respectively. Microbiota of cecum content was analyzed by 16S rRNA sequencing.

RESULTS

Data showed that with recovery on the colon length and histological structure, CA prominently decreased DAI and macroscopic score for lesion in the suffering mice. CA relieved the colitis by suppressing inflammatory cell infiltration with decreased MPO activity in the colon, and up-regulated the expression of tight junction protein (ZO-1, E-cadherin) to enhance the permeability of intestinal mucosa. Moreover, CA restored intestinal motility by promoting c-Kit expression in the colon and 5-HT in the brain. Moreover, CA was able to reshape the gut microbiota in the suffering mice. It increased the α-diversity and shifted the community by depleting the colitis-associated genera, Helicobacter, Jeotgalicoccus and Staphylococcus, with impact on several metabolism signaling pathways, which possibly contributes to the renovation on the impaired intestinal mucosal barrier.

CONCLUSIONS

CA displayed the anti-inflammatory activity against the DSS-induced colitis, which would possibly rely on the restoration on mucosa barrier and gut microbiota homeostasis, highlights a promising application of C. asiatica in the clinical treatment of UC.

Baitouweng decoction alleviates dextran sulfate sodium-induced ulcerative colitis by regulating intestinal microbiota and the IL-6/STAT3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Baitouweng (BTW) decoction, a Chinese traditional medicine prescription, has been used to treat ulcerative colitis (UC) over hundreds of years. In this study, we investigated the anti-inflammatory effects of BTW and intestinal flora of dextran sulfate sodium (DSS)-induced UC mice, and we investigated the mechanism of BTW in the preliminary treatment of UC.

AIM OF STUDY

The aim of this study was to elucidate the mechanism of BTW in treating UC through molecular biology and high-throughput sequencing.

METHODS

DSS-induced UC mice were established and randomly divided into the following four groups: control group, DSS group, BTW group and sulfasalazine (SASP) group. Except for the control group, 3% DSS drinking water was given to each group for 7 days, and the other two groups were intragastrically administered with BTW and SASP. Mice were sacrificed after gavage for 10 days. Body weight loss, disease activity index (DAI), colon length, colon histopathology and the expression of inflammatory cytokines were measured. Intestinal content samples were collected, and intestinal flora differences were analyzed by 16 S rDNA sequencing.

RESULTS

BTW effectively reduced the symptoms and histopathological score of UC mice, and it reduced the production of IL-6, IL-1β and TNF-α. Activation of the IL-6/STAT3 pathway was also suppressed by BTW treatment. Moreover, 16 S rDNA sequencing showed that the intestinal flora of mice in the DSS group was disordered compared to the control group. After treatment with BTW, the diversity of intestinal flora was significantly improved. At the phylum level, the proportion of Firmicutes to Bacteroidetes was decreased, and the ratio of Proteobacteria was decreased. At the genus level, the relative abundance of Escherichia-Shigella was decreased, but that of Lactobacillus and Akkermansia were increased.

CONCLUSION

BTW significantly improved the inflammatory symptoms of mice with acute colitis, and the latent mechanism of BTW may be related to various signaling pathways, including the modulation of intestinal microflora and inflammatory signaling pathways, such as IL-6/STAT3.

Inflammatory responses of C57BL/6NKorl mice to dextran sulfate sodium-induced colitis: comparison between three C57BL/6 N sub-strains

Background

Inflammatory bowel disease (IBD), including both Crohn’s disease and ulcerative colitis, are chronic human diseases that are challenging to cure and are often unable to be resolved. The inbred mouse strain C57BL/6 N has been used in investigations of IBD as an experimental animal model. The purpose of the current study was to compare the inflammatory responsiveness of C57BL/6NKorl mice, a sub-strain recently established by the National Institute of Food and Drug Safety Evaluation (NIFDS), with those of C57BL/6 N mice from two different sources using a dextran sulfate sodium (DSS)-induced colitis model.

Results

Male mice (8 weeks old) were administered DSS (0, 1, 2, or 3%) in drinking water for 7 days. DSS significantly decreased body weight and colon length and increased the colon weight-to-length ratio. Moreover, severe colitis-related clinical signs including diarrhea and rectal bleeding were observed beginning on day 4 in mice administered DSS at a concentration of 3%. DSS led to edema, epithelial layer disruption, inflammatory cell infiltration, and cytokine induction (tumor necrosis factor-α, interleukin-6, and interleukin-1β) in the colon tissues. However, no significant differences in DSS-promoted abnormal symptoms or their severity were found between the three sub-strains.

Conclusions

These results indicate that C57BL/6NKorl mice responded to DSS-induced colitis similar to the generally used C57BL6/N mice, thus this newly developed mouse sub-strain provides a useful animal model of IBD.

Intestinal anti-inflammatory effects of fuzi-ganjiang herb pair against DSS-induced ulcerative colitis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Fuzi and ganjiang are widely used as traditional Chinese medicines (TCM) in China, Korea, Japan, and many other southeast Asian countries for treating ulcerative colitis (UC), emesis and heart failure for more than 1800 years. However, the underlying mechanism of fuzi, ganjiang and fuzi-ganjiang herb pair is still unclear. In our study, we explored the therapeutic effects of fuzi, ganjiang and fuzi-ganjiang herb pair against dextran sulfate sodium (DSS)-induced UC in mice model, along with the relevant mechanism.

MATERIALS AND METHODS

The contents of each marker compound in fuzi decoction (FD), ganjiang decoction (GD) and fuzi-ganjiang decoction (FGD) were determined using LC-MS/MS. During the experiment, bodyweight changes in each group were monitored every 5 days. On the day of sacrifice, colonic length, disease activity index (DAI) and spleen weight were also evaluated and histopathological examination was performed through hematoxylin & eosin (H&E) staining. The levels of myeloperoxidase (MPO) and inflammatory cytokines in colon tissues were determined by enzyme-linked immunosorbent assay (ELISA), and then the relative mRNA productions of inflammatory mediators, such as MPO, inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 were measured by real-time polymerase chain reaction (PCR). Involvement of MAPK, STAT3 and NF-κB signaling pathways in the pathogenesis of UC was determined in each group using Western Blot (WB) analysis.

RESULTS

Compared with fuzi and ganjiang single decoction, the content of the alkaloids derived from fuzi (especially the diester alkaloid with strong toxicity, hypaconitine) in fuzi-ganjiang herb pair decoction was reduced. Additionally, the 6-gingerol, which was not found in ganjiang single decoction, was retained in fuzi-ganjiang herb pair decoction. FD, GD, and FGD significantly restored the bodyweight reduction, colon shortening, DAI elevation, splenomegaly and histological score in DSS-induced UC mice. Furthermore, except for the failure of low dosage of ganjiang decoction (GD-L) on IL-17A, all FD, GD and FGD significantly inhibited the production of MPO and inflammatory cytokines, such as IFN-γ, TNF-α, IL-1β, IL-6, IL-10 and IL-17A, and suppressed the relative expression of inflammatory mediators, such as MPO, iNOS and COX-2 mRNA in colon tissues of DSS-induced mice. According to WB analysis, fuzi, ganjiang and fuzi-ganjiang combination inhibited the activation of MAPK, NF-κB and STAT3 signaling pathways.

CONCLUSIONS

Our study demonstrated that fuzi, ganjiang and fuzi-ganjiang combination possess prominent anti-inflammatory activities against DSS-induced UC mice; the involved mechanism may be related to inhibition the activation of MAPK, NF-κB, and STAT3 signaling pathways.

Synergistic therapeutic effect of mesenchymal stem cells and tolerogenic dendritic cells in an acute colitis mouse model

Cell-based therapy with tolerizing cells has been applied for the treatment of inflammatory bowel disease (IBD) in previous experimental and clinical studies with promising results. In the current study, we utilized the dextran sulfate sodium (DSS)-induced colitis model, to investigate if tolerogenic dendritic cell-mesenchymal stem cell (tDC-MSC) combination therapy can augment the therapeutic effects of single transplantation of each cell type. The effect of MSC and tDC co-transplantation on the severity of colitis was assessed by daily monitoring of body weight, stool consistency, and rectal bleeding, and compared with control groups. Moreover, the colon length, colon weight, myeloperoxidase (MPO) activity were measured and evaluated with histological analysis of colon tissues. The Treg cell percentage and cytokine levels in spleens and mesenteric lymph nodes (MLNs) were measured by flow cytometry and ELISA, respectively. The results showed co-transplantation of MSCs and tDCs was more effective in alleviating the clinical and histological manifestations of colitis than monotherapy, especially when compared with MSC alone. The protective effects of tDC-MSC were accompanied by the induction of Treg cells and increased the production of anti-inflammatory cytokines in spleens and mesenteric lymph nodes. Together, co-transplantation of MSCs and tDCs could be a promising and effective therapeutic approach in the treatment of IBD.

New approach of medicinal herbs and sulfasalazine mixture on ulcerative colitis induced by dextran sodium sulfate

BACKGROUND

Sulfasalazine has been used as a standard-of-care in ulcerative colitis for decades, however, it results in severe adverse symptoms, such as hepatotoxicity, blood disorders, male infertility, and hypospermia. Accordingly, the new treatment strategy has to enhance pharmacological efficacy and stimultaneously minimize side effects.

AIM

To compare the anti-inflammatory action of sulfasalazine alone or in combination with herbal medicine for ulcerative colitis in a dextran sodium sulfate (DSS)-induced colitis mouse model.

METHODS

To induce ulcerative colitis, mice received 5% DSS in drinking water for 7 d. Animals were divided into five groups (n = 9 each) for use as normal (non-DSS), DSS controls, DSS + sulfasalazine (30 mg/kg)-treatment experimentals, DSS + sulfasalazine (60 mg/kg)-treatment experimentals, DSS + sulfasalazine (30 mg/kg) + Citrus unshiu peel and Bupleuri radix mixture (30 mg/kg) (SCPB)-treatment experimentals.

RESULTS

The SCPB treatment showed an outstanding effectiveness in counteracting the ulcerative colitis, as evidenced by reduction in body weight, improvement in crypt morphology, increase in antioxidant defenses, down-regulation of proinflammatory proteins and cytokines, and inhibition of proteins related to apoptosis.

CONCLUSION

SCPB may represent a promising alternative therapeutic against ulcerative colitis, without inducing adverse effects.

Protective effects of L-theanine on rats with dextran sulfate sodium-induced inflammatory bowel disease

The aim of this study is to evaluate the anti-inflammatory and protective effects of L-theanine in inflammatory bowel disease (IBD) and to identify the underlying molecular mechanisms. Rats were pre-treated with L-theanine at 0, 50, 200, or 800 mg/kg/day. IBD was induced in rats using dextran sulfate sodium (DSS). Histopathological analysis suggests that L-theanine can suppress DSS-induced IBD with significant inhibition of inflammation in large and small intestinal tissues. Moreover, the 200 mg/kg/day L-theanine-treated DSS group had higher body and small intestine weights, a lower disease activity index and expression of inflammatory factors than the DSS group without pre-treatment. In RNA sequencing and tandem mass tag labeling analyses, large number of mRNAs and proteins expression level differed when compared with the DSS-induced rats with and without 200 mg/kg/day L-theanine pre-treatment. Moreover, Kyoto Encyclopedia of Genes and Genomes pathway analysis indicates the anti-inflammatory activities of L-theanine in DSS-induced IBD, with a high representation of genes in "Cholesterol metabolism" and "Retinol metabolism" pathways. Analysis of protein-protein interaction networks further indicates the involvement of these two pathways. These studies suggest that medium-dose L-theanine pre-treatment could ameliorate DSS-induced IBD through molecular mechanisms involving cholesterol and retinol metabolism.

Ping weisan alleviates chronic colitis in mice by regulating intestinal microbiota composition

ETHNOPHARMACOLOGICAL RELEVANCE

Ping weisan (PWS), a complex formulation used in traditional Chinese medicine, is first described in 1107 AD and published in the Prescriptions of Taiping Benevolent Dispensary. We have previously confirmed that PWS has the effect of alleviating DSS-induced chronic ulcerative colitis (UC) in mice.

AIM OF THE STUDY

We aimed to examine whether PWS protects mice from chronic UC by regulating intestinal microbiota composition.

MATERIALS AND METHODS

Chronic colitis was induced in C57BL/6 mice with 2.5% DSS in drinking water. PWS (8 g/kg) was orally administered throughout the experiment. Body weight changes, stool consistency and myeloperoxidase (MPO) activity were measured in these mice. Interleukin-17A (IL-17A) and interferon gamma (IFN-γ) mRNA levels were detected by qRT-PCR. The alterations of fecal microflora were investigated by 16S rRNA sequencing. Furthermore, intestinal tight junction protein including occludin, and serum lipopolysaccharide (LPS) level were also detected.

RESULTS

PWS relieved DSS-induced loss of body weight, and improved stool consistency and MPO activity in mice. The levels of IL-17A and IFN-γ mRNA were also reduced after treatment with PWS. PWS not only regulated occludin level but also decreased serum LPS. We further showed DSS-induced changes in intestinal microbial composition and richness are significantly regulated by PWS. PWS treatment significantly decreased the abundance of Bacteroidetes, but increased the abundance of Firmicutes in chronic UC mice induced by DSS.

CONCLUSIONS

Combining with our previous results, we found that PWS could exert anti-UC role by rebalancing intestinal bacteria.

Dihydroartemisinin ameliorates dextran sulfate sodium induced inflammatory bowel diseases in mice

In the present study, the effects of dihydroartemisinin (DHA) on inflammatory bowel diseases (IBD) mice model induced by dextran sulfate sodium (DSS) were determined. Hematoxylin and eosin staining was used to assess the intestines of mice treated with DSS and DHA. The expression of inflammatory factors and cell junction-associated genes was measured using reverse transcription-quantitative PCR (RT-qPCR) and Western blot. The effects of DSS and DHA on the gut microbiome were measured using 16S recombinant (r) DNA gene analysis. DHA could improve the diarrhea and bloody stool induced by DSS, and decrease the serum levels of TNF-α, IL-1β and IL-23 of the DSS group. DHA could notably reduce the infiltration of the inflammatory cells and significantly decrease the expression of TNF-α and IL-1β in the intestines of the DSS treated mice. The expression of cell junction-associated genes such as EpCAM and Claudins, were down-regulated in the DSS group, and DHA could recover the expression of these cell junction-associated genes. The 16S rDNA gene analysis demonstrated that Bacteroidetes and Verrucomicrobia decreased, while Firmicutes and Proteobacteria increased in the DSS group, and DHA could recover the abundance of these gut bacteria altered by DSS. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that DHA could partly recover the pathways altered by DSS. DHA could obviously ameliorate the symptoms of IBD induced by DSS by regulation of the expression of inflammation and cell junction-associated genes and gut microbiota, suggesting its potential for the treatment of IBD.

A glycolipid adjuvant, 7DW8-5, provides a protective effect against colonic inflammation in mice by the recruitment of CD1d-restricted natural killer T cells

Background/Aims

The modulation of CD1d-restricted natural killer T (NKT) cells by glycolipids has been considered as a potential therapy against immunologic diseases, including inflammatory bowel disease. A recently identified a glycolipid analog, 7DW8-5, which is derived from α-galactosylceramide (α-GalCer), is as much as 100-fold more active at stimulating both human and mice NKT cells when compared to α-GalCer. We explored the effects of 7DW8-5 in mouse models of acute and chronic colitis.

Methods

We investigated the effects of 7DW8-5 on intestinal inflammation by assessing the effects of 7dW8-5 on a murine dextran sulfate sodium (DSS)-induced acute colitis model and a chronic colitis-associated tumor model.

Results

The acute DSS-induced colitis model showed a dose-dependent response to 7DW8-5, as mice administered 7DW8-5 showed a significant improvement in DSS-induced colitis based on their disease activity index, histologic analysis, and serum C-reactive protein levels, when compared to mice administered vehicle alone. However, DSS-induced colitis in CD1d-KO mice showed no response to 7DW8-5. A fluorescence-activating cell sorting analysis revealed an increase in NKT cells in colonic tissues of 7DW8-5-treated mice. RNA-seq and real-time quantitative polymerase chain reaction showed a significant increase in the expression of interleukin (IL)-4, IL-13, and interferon-gamma in 7DW8-5-treated mice. In addition, 7DW8-5 treatment reduced colitis-associated tumor development in an azoxymethane/DSS mouse model.

Conclusions

7DW8-5 activates NKT cells through CD1d and provides a protective effect against intestinal inflammation in mice. Therefore, 7DW8-5 may be a promising therapeutic agent for treatment of inflammatory bowel disease.

Aqueous extract of Bruguiera gymnorrhiza leaves protects against dextran sulfate sodium induced ulcerative colitis in mice via suppressing NF-κB activation and modulating intestinal microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

Ulcerative colitis (UC) is tightly associated with inflammation response and oxidative stress. As a folk medicine applied in treatment of diarrhea, Bruguiera gymnorrhiza also possesses anti-inflammatory and anti-oxidative activities, which indicated that B. gymnorrhiza may exert anti-colitis effect.

AIM OF THE STUDY

To investigate effect and mechanism of B. gymnorrhiza on experimental UC.

MATERIALS AND METHODS

Aqueous extract of B. gymnorrhiza leaves (ABL) was used for investigation in the present study. Murine UC was established through access to 3% dextran sulfate sodium (DSS) for 7 days. Meanwhile, mice accepted treatment with ABL (25, 50, 100 mg/kg) or sulfasalazine (200 mg/kg) once daily. On the last day, disease activity index (DAI) including body weight loss, fecal character and degree of bloody diarrhea was evaluated, colon segments were obtained for length measurement and further analysis and feces were collected for intestinal microbiota analysis.

RESULTS

ABL ameliorated DAI scores, colon length shortening and histopathological damage in DSS-induced colitis mice obviously. SOD activity, levels of MDA and GSH altered by colitis were restored remarkably after ABL treatment. ABL inhibited increases in levels of colonic COX-2, iNOS, TNF-α, IL-6, IL-1β, IL-4, IL-10 and IL-11 in colitis mice. Moreover, ABL prominently suppressed NF-κB p65 and IκB phosphorylation and down-regulated mRNA levels of COX-2, iNOS, TNF-α, IL-6 and IL-1β elevated by colitis. As shown in microbiota analysis, ABL modulated composition of intestinal microbiota of colitis mice.

CONCLUSION

ABL exhibited protective effect against DSS-induced ulcerative colitis through suppressing NF-κB activation and modulating intestinal microbiota.

Stachyose modulates gut microbiota and alleviates dextran sulfate sodium-induced acute colitis in mice

BACKGROUND/AIM

Ulcerative colitis (UC) has been implicated to imbalanced enteric flora and reduced microbial diversity. Stachyose is a kind of natural prebiotic which favorably modulate the composition of the gut microbiota. The present study aims to investigate the effects of stachyose on inflammatory levels and gut microbiota of acute colitis mice.

MATERIALS AND METHODS

In this study, the mice were randomly divided into four groups: (1) control group; (2) stachyose group; (3) dextran sulfate sodium (DSS) group; (4) stachyose + DSS group. Hemotoxylin and Eosin (H and E) staining was performed for the distal colon to examine the inflammation and tissue damage. The inflammatory cytokines including IL-6, IL-10, IL-17a, and TNF-α in serum were determined by ELISA assay. The differences in the gut microbiota were analyzed by 16S rDNA gene sequencing.

RESULTS

Histological assay showed that the stachyose treatment significantly reduced the lesions of the colon in DSS-induced colitis. And the upregulated inflammatory cytokines induced by DSS were significantly inhibited by stachyose treatment. Additionally, the sequencing analysis showed that the stachyose changed the gut microbiota composition with a higher level of Akkermansia, as well as selectively increasing some probiotics, including Lactobacillus.

CONCLUSIONS

Our results suggested that stachyose increased beneficial microbiota and bacterial diversity to alleviate acute colitis in mice, which might be a new promising option to UC patients.

Expanding the utility of the dextran sulfate sodium (DSS) mouse model to induce a clinically relevant loss of intestinal barrier function

Background

Inflammatory bowel disease (IBD) is a family of debilitating disorders that affects more than 1 million people in the United States. Many animal studies of IBD use a dextran sulfate sodium (DSS) mouse model of colitis that induces rapid and severe colitis symptoms. Although the typical seven-day DSS model is appropriate for many studies, it destroys intestinal barrier function and results in intestinal permeability that is substantially higher than what is typically observed in patients. As such, therapies that enhance or restore barrier integrity are difficult or impossible to evaluate.

Methods

We identify administration conditions that result in more physiologically relevant intestinal damage by systematically varying the duration of DSS administration. We administered 3.0% DSS for four to seven days and assessed disease metrics including weight, fecal consistency, intestinal permeability, spleen weight, and colon length. Histology was performed to assess the structural integrity of the intestinal epithelium.

Results

Extended exposure (seven days) to DSS resulted in substantial, unrecoverable loss of intestinal structure and intestinal permeability increases of greater than 600-fold. Attenuated DSS administration durations (four days) produced less severe symptoms by all metrics. Intestinal permeability increased only 8-fold compared to healthy mice, better recapitulating the 2–18 fold increases in permeability observed in patients. The attenuated model retains the hallmark properties of colitis against which to compare therapeutic candidates. Our results demonstrate that an attenuated DSS colitis model obtains clinically relevant increases in intestinal permeability, enabling the effective evaluation of therapeutic candidates that promote barrier function.

Protective effects of panax notoginseng saponin on dextran sulfate sodium-induced colitis in rats through phosphoinositide-3-kinase protein kinase B signaling pathway inhibition

BACKGROUND

Intestinal inflammation is a common digestive tract disease, which is usually treated with hormone medicines. Hormone medicines are effective to some extent, but long-term use of them may bring about many complications.

AIM

To explore the protective effects of panax notoginseng saponin (PNS) against dextran sulfate sodium (DSS)-induced intestinal inflammatory injury through phosphoinositide-3-kinase protein kinase B (PI3K/AKT) signaling pathway inhibition in rats.

METHODS

Colitis rat models were generated via DSS induction, and rats were divided into control (no modeling), DSS, DSS + PNS 50 mg/k, and DSS + PNS 100 mg/kg groups. Then, the intestinal injury, oxidative stress parameters, inflammatory indices, tight junction proteins, apoptosis, macrophage polarization, and TLR4/AKT signaling pathway in colon tissues from rats in each of the groups were detected. The PI3K/AKT signaling pathway in the colon tissue of rats was blocked using the PI3K/AKT signaling pathway inhibitor, LY294002.

RESULTS

Compared with rats in the control group, rats in the DSS group showed significantly shortened colon lengths, and significantly increased disease activity indices, oxidative stress reactions and inflammatory indices, as well as significantly decreased expression of tight junction-associated proteins. In addition, the DSS group showed significantly increased apoptotic cell numbers, and showed significantly increased M1 macrophages in spleen and colon tissues. They also showed significantly decreased M2 macrophages in colon tissues, as well as activation of the PI3K/AKT signaling pathway (all P < 0.05). Compared with rats in the DSS group, rats in the DSS + PNS group showed significantly lengthened colon lengths, decreased disease activity indices, and significantly alleviated oxidative stress reactions and inflammatory responses. In addition, this group showed significantly increased expression of tight junction-associated proteins, significantly decreased apoptotic cell numbers, and significantly decreased M1 macrophages in spleen and colon tissues. This group further showed significantly increased M2 macrophages in colon tissues, and significantly suppressed activation of the PI3K/AKT signaling pathway, as well as a dose dependency (all P < 0.05). When the PI3K/AKT signaling pathway was inhibited, the apoptosis rate of colon tissue cells in the DSS + LY294002 group was significantly lower than that of the DSS group (P < 0.05).

CONCLUSION

PNS can protect rats against DSS-induced intestinal inflammatory injury by inhibiting the PI3K/AKT signaling pathway, and therefore may be potentially used in the future as a drug for colitis.

Rutaecarpine inhibits KEAP1-NRF2 interaction to activate NRF2 and ameliorate dextran sulfate sodium-induced colitis

Inflammatory bowel disease (IBD) represents a group of chronic relapsing intestinal disorders. Rutaecarpine (RUT), isolated from the Traditional Chinese Medicine (TCM) of Evodia rutaecarpa, was reported to suppress IBD. However, the mechanism by which RUT ameliorates dextran sulfate sodium (DSS)-induced IBD is largely unknown. By use of nuclear factor-erythroid 2-related factor 2 (NRF2) knockout mice, cell-based studies, surface plasmon resonance (SPR), western blotting analysis, and molecular docking studies, the mechanism by which RUT affects DSS-induced colitis was explored. In DSS-treated wild-type mice but not in Nrf2-null mice, RUT significantly improved colitis as revealed by rescued body weight loss, improved histology and inflammation, and induced expression of NRF2 target genes in colon and ileum. Cell-based studies showed that RUT significantly increased the LD₅₀ for hydrogen peroxide (H₂O₂)-induced cell damage, activated NRF2 nuclear translocation, and suppressed the production of reactive oxygen species in H₂O₂-treated HCT116 cells, activated NRF2 luciferase reporter activities in HCT116 cells and HepG2 cells, and induced expression of NRF2 target genes in primary intestinal epithelial cells. Molecular docking in silico and SPR assays indicated that RUT interacted with kelch-like ECH-associated protein 1 (KEAP1), and extracellular incubation studies revealed that RUT bound to the KEAP1 kelch domain with a calculated equilibrium dissociation constant K_d of 19.6 μM. In conclusion, these results demonstrate that RUT ameliorates DSS-induced colitis, dependent on NRF2, and could be a potential therapeutic option for IBD patients. Mechanistically, RUT potentiates NRF2 nuclear translocation to upregulate NRF2-mediated antioxidant response by directly inhibiting KEAP1-NRF2 interaction.

Regenerating islet-derived protein (Reg)3β plays a crucial role in attenuation of ileitis and colitis in mice

Regenerating islet-derived protein (Reg)3β belongs to a member of the Reg family of proteins and has pleiotropic functions, including antimicrobial activity and tissue repair. However, whether Reg3β plays a protective role in the development of colitis and ileitis has not been fully investigated. We generated transgenic mice expressing a short form of cellular FLICE-inhibitory protein (cFLIPs) that promotes necroptosis, a regulated form of cell death. cFLIPs transgenic (CFLARs Tg) mice develop severe ileitis in utero. Although Reg3β is undetectable in the small intestine of wild-type embryos, its expression is aberrantly elevated in the small intestine of CFLARs Tg embryos. To test whether elevated Reg3β attenuates or exacerbates ileitis in CFLARs Tg mice, we generated a Reg3b^−/− strain. Reg3b^−/− mice grew to adulthood without apparent abnormalities. Deletion of Reg3b in CFLARs Tg mice exacerbated the embryonic lethality of CFLARs Tg mice. Dextran sulfate sodium-induced colitis, characterized by body weight loss and infiltration of neutrophils, was exacerbated in Reg3b^−/− compared to wild-type mice. Moreover, the expression of Interleukin 6, an inflammatory cytokine and Chitinase-like 3, a marker for tissue repair macrophages was elevated in the colon of Reg3b^−/− mice compared to wild-type mice after DSS treatment. Together, these results suggest that attenuation of colitis and ileitis is a result of Reg3β′s real function.

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The expression of Reg3β is elevated in the embryonic small intestine of CFLARs Tg mice.

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Reg3b^−/− mice grow to adulthood without apparent abnormalities.

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Dextran sulfate sodium-induced colitis is exacerbated in Reg3b^−/− mice.

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Deletion of Reg3b exacerbates ileitis in CFLARs Tg mice.

Dietary exposure to chlorpyrifos inhibits the polarization of regulatory T cells in C57BL/6 mice with dextran sulfate sodium-induced colitis

Inflammatory bowel disease (IBD) is associated with loss of immune tolerance to antigens originating from the diet and from the gut microflora. T cells play crucial roles in the pathogenesis of IBD. Chlorpyrifos (CPF) is one of the most ubiquitous organophosphate pesticides in the world. The aim of the study was to investigate the effects of dietary exposure to CPF on T-cell populations in C57BL/6 mice with dextran sulfate sodium (DSS)-induced colitis. Mice received distilled water containing 3% DSS for 6 days to induce acute colitis, which was then replaced with distilled water for 21 days, allowing progression to chronic inflammation. During the experimental period, mice were given either an AIN-93-based control diet or a CPF diet-containing 7, 17.5, or 35 ppm of CPF. Results showed that dietary exposure to CPF significantly increased circulating neutrophils in colitic mice. CPF-exposed groups had lower percentages of blood and spleen T cells without altering the proportions of CD4⁺ and CD8⁺ T-cell subsets. The percentage of blood regulatory T (Treg) cells, as well as splenic expressions of Treg-related genes, were suppressed in CPF-exposed mice. CPF upregulated the colonic gene expression of tumor necrosis factor-α. Meanwhile, plasma haptoglobin, colon weights, and luminal immunoglobulin G levels were higher in CPF-exposed groups. Histopathological analyses also observed that colon injury was more severe in all CPF-exposed mice. These results suggest that dietary exposure to CPF aggravated tissue injuries in mice with DSS-induced chronic colitis by suppressing T-cell populations and Treg polarization.

Galectin-1 exhibits a protective effect against hepatotoxicity induced by dextran sulfate sodium in mice

Galectin-1 is an important mediator that regulates the T-cell-mediated immune response. It has many other biological functions such as cell growth, immunomodulation, and wound healing. The aim of this study was to reveal the role of galectin-1 on liver morphology, cell proliferation, apoptosis, inflammatory and anti-inflammatory mediators, oxidative stress, and antioxidant system in colitis-mediated hepatotoxicity induced by dextran sulfate sodium (DSS). In the present study, adult mice were divided into four groups: The control group intraperitoneally injected with phosphate buffer saline (I), the group which was orally administered with DSS (II), the control group which was injected with galectin-1 (III), and the group which was given DSS and galectin-1 (IV). DSS administration caused degenerative changes and diffuse necrotic damage, an increase in caspase-3 and cyclooxygenase-2 expression, the levels of lipid peroxidation and tumor necrosis factor-alpha, lactate dehydrogenase, and myeloperoxidase activities, and a decrease in cell proliferation, interleukin-10 levels, and antioxidant system parameters in liver tissues. Treatment of DSS group with galectin-1 reversed these effects and prevented liver damage. This study showed that galectin-1 has proliferative, antiapoptotic, anti-inflammatory, and antioxidant effects against DSS-induced liver injury in mice. It is expected considering all results of this study that galectin-1 may be useful as a protective agent against liver toxicity.