Anti-inflammatory Activity of Mollugin on DSS-induced Colitis in Mice

We aimed to explore the anti-infammatory bactivity of mollugin extracted from Rubia cordifolia L,a traditional Chinese medicine,on dextran sulfate sodium(DSS)-induced ulcerative colitis(UC)in mice.Thirty C57BL/6 mice were divided into a control group(n=6),a model group(n=6),and three experimental groups(40,20,10 mg/kg of mollugin,n=6 each).DSS solution(3%)was given to mice in the model group and experimental groups from day 4 to day 10 to induce the mouse UC model.Mice in the experimental groups were intragastrically administrated mollugin from day 1 to day 10.Animals were orally given distilled water in the control group for the whole experiment time and in the model group from day 1 to day 3.The changes in colon pathology were detected by hematoxylin and eosin(HE)staining.Interleukin-1β(IL-1β)in the serum,and tumor necrosis factor-α(TNF-α)and interferon-γ(IFN)in the tissues were measured by enzyme linked immunosorbent assay.Expression levels of Toll-like receptor 4(TLR4)and myeloid differentiation factor 88 in the colon tissues were detected by immunohistochemistry.Results showed that mollugin could significantly reduce weight loss and the disease activity index in the DSS-induced UC mouse model.HE examinations demonstrated that mollugin treatment effectively improved the histological damage(P<0.05).The overproduction of IL-Iβand TNF-α was remarkably inhibited by mollugin treatment at doses of 20 and 40 mg/kg(P<0.05).Additionally,the levels of TLR4 in colon tissues were significantly reduced in mollugin-treated groups compared with the DSS group.Our findings demonstrated that mollugin ameliorates DSS-induced UC by inhibiting the production of pro-inflammatory chemocytokines.

Initial gut microbiota structure affects sensitivity to DSS-induced colitis in a mouse model

The dextran sulfate sodium (DSS)-induced colitis model is a widely applied mouse model, but controversial results have been obtained from experiments using the same mouse strain under the same conditions. Because the gut microbiota play an important role in DSS-induced colitis, it is essential to evaluate the influence of the initial gut microbiota in this model. Here, we identified significant variations in the initial gut microbiota of different batches of mice and found that the initial intestinal microbiota had a profound influence on DSS-induced colitis. We performed three independent trials using the same C57BL/6J mouse model with DSS treatment and used high-throughput 16S rRNA gene sequencing to analyze the gut microbiota. We found that the structure and composition of the gut microbiota in mice with severe colitis, as compared with mice with milder colon damage, had unique features, such as an increase in Akkermansia bacteria and a decrease in Barnesiella spp. Moreover, these varied gut bacteria in the different trials also showed different responses to DSS treatment. Our work suggests that, in studies using mouse models, the gut microbiota must be considered when examining mechanisms of diseases, to ensure that comparable results are obtained.

Evaluation of the effect of pyrrolidine dithiocarbamate in suppressing inflammation in mice with dextran sodium sulfate-induced colitis

AIM: To evaluate the effect of pyrrolidine dithio- carbamate (PDTC; an NF-κB inhibitor) administered at low (50 mg/kg) and high (100 mg/kg) doses in suppressing colitis in mice with dextran sodium sulfate (DSS)-induced colitis. METHODS: Mice were divided into a DSS-untreated group (normal group), DSS-treated control group, DSS+PDTC-treated groupⅠ(low-dose group), and DSS+PDTC-treated groupⅡ (high-dose group). In each group, the disease activity index score (DAI score), intestinal length, histological score, and the levels of activated NF-κB and inflammatory cytokines (IL-1β and TNF-α) in tissue were measured. RESULTS: The DSS+PDTC-treated groupⅡ exhibited suppression of shortening of intestinal length and reduction of DAI score. Activated NF-κB level and IL-1β and TNF-α levels were significantly lower in DSS+PDTC- treated groupⅡ. CONCLUSION: These findings suggest that PDTC is useful for the treatment of ulcerative colitis.

Atopic Dermatitis Deteriorates Dextran Sodium Sulfate-Induced Ulcerative Colitis via Thymic Stromal Lymphopoietin in Mice

It has been reported that atopic dermatitis (AD) and ulcerative colitis are related. However, the mechanism underlying this association has not been clarified. We therefore explored how AD induces ulcerative colitis. We developed an AD mouse model (NC/Nga mice) with ulcerative colitis by administering dextran sodium sulfate (DSS) for five days. DSS-induced ulcerative colitis was deteriorated in our conventional AD mouse model compared with specific-pathogen-free (SPF) mice. The plasma levels of thymic stromal lymphopoietin (TSLP) and tumor necrosis factor-α increased the most in DSS-treated conventional mice. Furthermore, the expression of dendritic cells (DC), retinoid-related orphan receptor (ROR)γt (marker of T helper 17 cells [Th17]), interleukin (IL)-17, GATA binding protein 3 (GATA3) (marker of Th2), and IL-4 increased the most in the colon of the DSS-treated conventional mice compared with DSS-treated SPF mice. In addition, TSLP inhibitor (TSLP neutralizing antibody) did not exacerbate ulcerative colitis in DSS-treated conventional mice. These results indicate that TSLP/DC/Th2 and Th17 play major roles in the exacerbation of ulcerative colitis by AD.

Repurposing disulfiram with CuET nanocrystals:Enhancing anti-pyroptotic effect through NLRP3 inflammasome inhibition for treating inflammatory bowel diseases

Drug repurposing offers a valuable strategy for identifying new therapeutic applications for existing drugs.Recently,disulfiram(DSF),a drug primarily used for alcohol addiction treatment,has emerged as a potential treatment for inflammatory diseases by inhibiting pyroptosis,a form of programmed cell death.The therapeutic activity of DSF can be further enhanced by the presence of Cu^(2+),although the underlying mechanism of this enhancement remains unclear.In this study,we investigated the mechanistic basis of Cu^(2+)-induced enhancement and discovered that it is attributed to the formation of a novel copper ethylthiocarbamate(CuET)complex.CuET exhibited significantly stronger anti-pyroptotic activity compared to DSF and employed a distinct mechanism of action.However,despite its potent activity,CuET suffered from poor solubility and limited permeability,as revealed by our druggability studies.To overcome these intrinsic limitations,we developed a scalable method to prepare CuET nanocrystals(CuET NCs)using a metal coordination-driven self-assembly approach.Pharmacokinetic studies demonstrated that CuET NCs exhibited a 6-fold improvement in bioavailability.Notably,CuET NCs exhibited high biodistribution in the intestine,suggesting their potential application for the treatment of inflammatory bowel diseases(IBDs).To evaluate their therapeutic efficacy in vivo,we employed a murine model of DSS-induced colitis and observed that CuET NCs effectively attenuated inflammation and ameliorated colitis symptoms.Our findings highlight the discovery of CuET as a potent anti-pyroptotic agent,and the development of CuET NCs represents a novel approach to enhance the druggability of CuET.

Loss of T-cell protein tyrosine phosphatase in the intestinal epithelium promotes local inflammation by increasing colonic stem cell proliferation

T-cell protein tyrosine phosphatase(TC-PTP)has a critical role in the development of the immune system and has been identified as a negative regulator of inflammation.Single-nucleotide polymorphisms in the TC-PTP locus have been associated with increased susceptibility to inflammatory bowel diseases(IBDs)in patients.To further understand how TC-PTP is related to IBDs,we investigated the role of TC-PTP in maintaining the intestinal epithelial barrier using an in vivo genetic approach.Intestinal epithelial cell(IEC)-specific deletion of TC-PTP was achieved in a mouse model at steady state and in the context of dextran sulphate sodium(DSS)-induced colitis.Knockout(KO)of TC-PTP in IECs did not result in an altered intestinal barrier.However,upon DSS treatment,IECspecific TC-PTP KO mice displayed a more severe colitis phenotype with a corresponding increase in the immune response and inflammatory cytokine profile.The absence of TC-PTP caused an altered turnover of IECs,which is further explained by the role of the tyrosine phosphatase in colonic stem cell(CoSC)proliferation.Our results suggest a novel role for TC-PTP in regulating the homeostasis of CoSC proliferation.This supports the protective function of TC-PTP against IBDs,independently of its previously demonstrated role in intestinal immunity.