Disruption of Tumor Necrosis Factor Receptor-Associated Factor 5 Exacerbates Murine Experimental Colitis via Regulating T Helper Cell-Mediated Inflammation.

Tumor necrosis factor (TNF) receptor-associated factor 5 (TRAF5) is a key mediator of TNF receptor superfamily members and is important in both T helper (Th) cell immunity and the regulation of multiple signaling pathways. To clarify TRAF5's influence on inflammatory bowel diseases (IBDs), we investigated TRAF5 deficiency's effect on dextran sulfate sodium- (DSS-) induced colitis. Colitis was induced in TRAF5 knockout (KO) mice and their wild-type (WT) littermates by administering 3% DSS orally for 7 days. The mice were then sacrificed, and their colons were removed. Our data suggested that KO mice were more susceptible to DSS-induced colitis. TRAF5 deficiency significantly enhanced IFN-γ, IL-4, and IL-17a mRNA and protein levels in the colons of DSS-fed mice, and the mRNA expression of T-bet and GATA-3 was also markedly elevated. However, ROR-α and ROR-γt mRNA levels did not differ between DSS-induced KO and WT mice. Flow cytometry showed increased frequencies of Th2 and IFN-γ/IL-17a-coproducing CD4(+) T cells in the colons of DSS-induced KO mice. Additionally, TRAF5 deficiency significantly enhanced the activation of NF-κB in CD4(+) T cells after DSS administration. These results indicated that TRAF5 deficiency significantly aggravated DSS-induced colitis, most likely by regulating Th cell-mediated inflammation.

Cancer-Preventive Role of Bone Marrow-Derived Mesenchymal Stem Cells on Colitis-Associated Colorectal Cancer: Roles of Gut Microbiota Involved.

BACKGROUND: Mesenchymal stem cells (MSCs) treatment showed promising results in inflammatory bowel disease in both rodent models and patients. Nevertheless, previous studies conducted conflicting results on preclinical tumor models treated with MSCs concerning their influence on tumor initiation and progression. This study is designed to demonstrate the role of bone marrow-derived MSCs and the potential mechanism in the colitis-associated colon cancer (CAC) model. METHODS: Bone marrow-derived MSCs were isolated from green fluorescent protein-transgenic mice, cultured, and identified by flow cytometry. Azoxymethane and dextran sulfate sodium were administrated to establish the CAC mouse model, and MSCs were infused intraperitoneally once per week. The mice were weighed weekly, and colon length, tumor number, and average tumor size were assessed after the mice were killed. MSC localization was detected by immunofluorescence staining; tumor cell proliferation and apoptosis were measured by immunohistochemistry staining of Ki-67 and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assay, respectively. The colonic tumor tissues were isolated for RNA-seq, and fecal samples were collected for 16S ribosomal RNA sequencing of the microbiome. RESULTS: After injection intraperitoneally, MSCs migrated to the intestine and inhibited the initiation of colitis-associated colorectal cancer. This inhibition effect was marked by less weight loss, longer colon length, and reduced tumor numbers. Moreover, MSCs reduced tumor cell proliferation and induced tumor cell apoptosis. Furthermore, MSCs could inhibit chronic inflammation assessed by RNA-sequencing and promote gut microbiome normalization detected by 16S ribosomal RNA sequencing. CONCLUSION: The results proved that MSCs could migrate to the colon, inhibit chronic inflammation, and regulate gut microbiome dysbiosis to suppress the development of CAC.

Fucose Ameliorate Intestinal Inflammation Through Modulating the Crosstalk Between Bile Acids and Gut Microbiota in a Chronic Colitis Murine Model.

BACKGROUND: Recurrent intestinal inflammation is frequently associated with aberrant bile acid profiles and microbial community. Fucose exerts a protective effect on commensal bacteria in the case of intestinal pathogen infection. We speculated that fucose might also have certain impact on the microbial ecosystem under the chronic colitis setting. METHODS: To validate our hypothesis, multi-omics examination was performed in combination with microbiomics and metabonomics in a chronic dextran sulfate sodium (DSS) murine model in the presence or absence of fucose. The 16S RNA sequencing was carried out to determine the ileum and colon microbiota. Primary and secondary bile acids, together with the respective taurine and glycine conjugates, were quantified through ultraperformance liquid chromatography coupled with mass spectrometry (UPLC-MS). Moreover, enzymes involved in regulating bile acid synthesis were also detected. Finally, an experiment was carried out on the antibiotic-treated mice to examine the role of gut microbiota. RESULTS: Administration of exogenous-free fucose markedly alleviated the inflammatory response in colitis mice. In addition, excessive intestinal bile acid accumulated in DSS mice was decreased in the presence of fucose, along with the restoration of the compromised regulation on hepatic bile acid synthesis. Moreover, the shifts in bile acid profiles were linked with the improved gut microbiome dysbiosis. However, the protective effects of fucose were abolished in mice treated with antibiotic cocktail, indicating that microbiota played a pivotal role. CONCLUSIONS: Findings in this study suggest that fucose ameliorates colitis through restoring the crosstalk between bile acid and gut microbiota.

Knock down of BMSC-derived Wnt3a or its antagonist analogs attenuate colorectal carcinogenesis induced by chronic Fusobacterium nucleatum infection.

By establishing the Fusobacterium nucleatum (F. nucleatum) infected-bone mesenchymal stem cells (BMSCs) transplantation model in APCMin/+ mice, we investigated the role of BMSCs in the development of intestinal tumors induced by F. nucleatum. ApcMin/++F. nucleatum + BMSCs mice showed increased susceptibility to intestinal tumors and accelerated tumor growth. BMSCs could also enhance tumor-initiating capability, invasive traits after F. nucleatum infection in vitro, and tumorigenicity in a nude murine model. Mechanistically, BMSCs were recruited to the submucosa, migrated to the mucosal layer, and might activate the canonical Wnt/ß-catenin/TGIF axis signaling. Further mechanistic results illustrated increased production of the Wnt3a protein was found in ApcMin/++F. nucleatum + BMSCs mice, and BMSCs were likely the major source of Wnt3a. Intriguingly, a deletion of Wnt3a via BMSC interference or antagonist analogs led to a significantly attenuated capacity of ApcMin/++F. nucleatum mice to generate intestinal tumors. The findings suggest that BMSCs have the potential to migrate and accelerate F. nucleatum-induced colorectal tumorigenesis by modulating Wnt3a secretion; knockdown of BMSC-derived Wnt3a or antagonist analogs could attenuate carcinogenesis. Thus, Wnt3a might be a potential pharmaceutical target for the prevention and treatment of F. nucleatum-related colorectal cancer.

L-Fucose ameliorates DSS-induced acute colitis via inhibiting macrophage M1 polarization and inhibiting NLRP3 inflammasome and NF-kB activation.

Previous studies reported that L-fucose had anti-inflammatory effects in respiratory and cutaneous system. However, the effect of L-fucose on colitis and the underlying mechanism is poorly understood. We studied the anti-inflammatory effects of L-fucose on Dextran sulfate sodium (DSS)-induced acute colitis in vivo and on LPS/ATP-induced bone marrow derived macrophages (BMDMs) damage in vitro. Our results show that L-fucose significantly alleviated weight loss and disease activity index (DAI) scores in colitis and reduced the infiltration of macrophages and neutrophils. In addition, L-fucose can inhibit macrophage M1 polarization, inactivate the NLRP3 inflammasome and reduce the release of TNFα, IL1ß, IL6 pro-inflammatory cytokines. In vitro studies showed that L-fucose ameliorated cell damage resulting from the administration of LPS with ATP in BMDMs, inhibited NLRP3 inflammasome activation and reduced the release of corresponding pro-inflammatory cytokines. Finally, L-fucose can inhibit the expression of p-NF-kB in vivo and in vitro. Overall, our results show that L-fucose can attenuate colitis by inhibiting macrophage M1 polarization, inhibiting NLRP3 inflammasome and NF-kB activation, and down-regulation of pro-inflammatory cytokines.