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  • 1
    Online Resource
    Online Resource
    American Physiological Society ; 2018
    In:  American Journal of Physiology-Gastrointestinal and Liver Physiology Vol. 315, No. 2 ( 2018-08-01), p. G220-G230
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 315, No. 2 ( 2018-08-01), p. G220-G230
    Abstract: Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory condition that affects millions of people with high morbidity and health care costs. The precise etiology of IBD is unknown, but clear evidence suggests that intestinal inflammation is caused by an excessive immune response to mucosal antigens. Recent studies have shown that activation of the aryl hydrocarbon receptor (AhR) induces regulatory T cells (Tregs) and suppresses autoimmune diseases. In the current study, we investigated if a nontoxic ligand of AhR, 2-(1′ H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), can attenuate dextran sodium sulfate-induced colitis. Our studies demonstrated that in mice that received ITE treatment in vivo, colitis pathogenesis, including a decrease in body weight, was significantly reversed along with the systemic and intestinal inflammatory cytokines. ITE increased the expression of Tregs in spleen, mesenteric lymph nodes (MLNs), and colon lamina propria lymphocytes (cLPL) of mice with colitis when compared with controls. This induction of Tregs was reversed by AhR antagonist treatment in vitro. ITE treatment also increased dendritic cells (CD11c + ) and decreased macrophages (F4/80 + ) from the spleen, MLNs, and cLPL in mice with colitis. ITE also reversed the systemic and intestinal frequency of CD4 + T cells during colitis and suppressed inflammatory cytokines including IFN-γ, TNF-α, IL-17, IL-6, and IL-1 as well as induced IL-10 levels. These findings suggest that ITE attenuates colitis through induction of Tregs and reduction in inflammatory CD4 + T cells and cytokines. Therefore, our work demonstrates that the nontoxic endogenous AhR ligand ITE may serve as a therapeutic modality to treat IBD. NEW & NOTEWORTHY We report the novel finding that activation of the aryl hydrocarbon receptor with the nontoxic ligand 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) induces regulatory T cells (Tregs) and suppresses inflammatory bowel disease (IBD). Our data suggest that ITE diminishes colitis pathology through induction of Tregs; reduces inflammatory cytokines, inflammation score, and macrophage frequency; and induces DCs resulting in amelioration of colitis. Therefore, nontoxic endogenous ITE promotes the induction of Tregs and may be useful for the treatment of IBD.
    Type of Medium: Online Resource
    ISSN: 0193-1857 , 1522-1547
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2018
    detail.hit.zdb_id: 1477329-6
    SSG: 12
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  • 2
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 311, No. 4 ( 2016-10-01), p. G699-G712
    Abstract: Obesity presents a significant public health concern given its association with increased cancer incidence, unfavorable prognosis, and metastasis. However, there is very little literature on the effects of weight loss, following obesity, on risk for colon cancer or liver cancer. Therefore, we sought to study whether intentional weight loss through diet manipulation was capable of mitigating colon and liver cancer in mice. We fed mice with a high-fat diet (HFD) comprised of 47% carbohydrates, 40% fat, and 13% protein for 20 wk to mimic human obesity. Subsequently, azoxymethane (AOM) was used to promote colon and liver carcinogenesis. A subset of obese mice was then switched to a low-fat diet (LFD) containing 67.5% carbohydrate, 12.2% fat, and 20% protein to promote intentional weight loss. Body weight loss and excess fat reduction did not protect mice from colon cancer progression and liver dysplastic lesion in the AOM-chemical-cancer model even though these mice had improved blood glucose and leptin levels. Intentional weight loss in AOM-treated mice actually produced histological changes that resemble dysplastic alterations in the liver and presented a higher percentage of F4/80 + CD206 + macrophages and activated T cells (CD4 + CD69 + ) in the spleen and lymph nodes, respectively. In addition, the liver of AOM-treated mice exposed to a HFD during the entire period of the experiment exhibited a marked increase in proliferation and pNF-κB activation. Altogether, these data suggest that intentional weight loss following chemical-induced carcinogenesis does not affect colon tumorigenesis but may in fact negatively impact liver repair mechanisms.
    Type of Medium: Online Resource
    ISSN: 0193-1857 , 1522-1547
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2016
    detail.hit.zdb_id: 1477329-6
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    American Physiological Society ; 2016
    In:  American Journal of Physiology-Gastrointestinal and Liver Physiology Vol. 310, No. 6 ( 2016-03-15), p. G347-G358
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 310, No. 6 ( 2016-03-15), p. G347-G358
    Abstract: Clinical studies have linked microRNA-155 (miR-155) expression in the tumor microenvironment to poor prognosis. However, whether miR-155 upregulation is predictive of a pro- or antitumorigenic response is unclear, as the limited preclinical data available remain controversial. We examined miR-155 expression in tumor tissue from colon cancer patients. Furthermore, we investigated the role of this microRNA in proliferation and apoptosis, inflammatory processes, immune cell populations, and transforming growth factor-β/SMAD signaling in a chemically induced (azoxymethane-dextran sulfate sodium) mouse model of colitis-associated colon cancer. We found a higher expression of miR-155 in the tumor region than in nontumor colon tissue of patients with colon cancer. Deletion of miR-155 in mice resulted in a greater number of polyps/adenomas, an increased symptom severity score, a higher grade of epithelial dysplasia, and a decrease in survival. Surprisingly, these findings were associated with an increase in apoptosis in the normal mucosa, but there was no change in proliferation. The protumorigenic effects of miR-155 deletion do not appear to be driven solely by dysregulation of inflammation, as both genotypes had relatively similar levels of inflammatory mediators. The enhanced tumorigenic response in miR-155 −/− mice was associated with alterations in macrophages and neutrophils, as markers for these populations were decreased and increased, respectively. Furthermore, we demonstrated a greater activation of the transforming growth factor-β/SMAD pathway in miR-155 −/− mice, which was correlated with the increased tumorigenesis. Given the multiple targets of miR-155, careful evaluation of its role in tumorigenesis is necessary prior to any consideration of its potential as a biomarker and/or therapeutic target in colon cancer.
    Type of Medium: Online Resource
    ISSN: 0193-1857 , 1522-1547
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2016
    detail.hit.zdb_id: 1477329-6
    SSG: 12
    Location Call Number Limitation Availability
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