Inflammation drives the pathogenesis of nonalcoholic steatohepatitis (NASH). The current study examined changes in intestinal inflammation during NASH. In male C57BL/6J mice, feeding a methionine- ...and choline-deficient diet (MCD) resulted in severe hepatic steatosis and inflammation relative to feeding a chow diet (CD). MCD-fed mice exhibited characteristics of mucosal and submucosal inflammatory responses compared with CD-fed mice. Moreover, intestinal phosphorylation states of c-Jun N-terminal protein kinase p46 and mRNA levels of IL-1B, IL-6, tumor necrosis factor alpha, and monocyte chemoattractant protein-1 were significantly higher and intestinal mRNA levels of IL-4 and IL-13 were significantly lower in MCD-fed mice compared with those in CD mice. Surprisingly, upon treatment with MCD-mimicking media, the proinflammatory responses in cultured intestinal epithelial CMT-93 cells did not differ significantly from those in CMT-93 cells treated with control media. In contrast, in RAW264.7 macrophages, MCD-mimicking media significantly increased the phosphorylation states of c-Jun N-terminal protein kinase p46 and mitogen-activated protein kinases p38 and mRNA levels of IL-1B, IL-6, IL-10, and tumor necrosis factor alpha under either basal or lipopolysaccharide-stimulated conditions. Collectively, these results suggest that increased intestinal inflammation is associated with NASH phenotype. Thus, elevated proinflammatory responses in macrophages likely contribute to, in large part, increased intestinal inflammation in NASH.
Adenosine 2A receptor (A2AR) exerts a protective role in obesity-related non-alcoholic fatty liver disease. Here, we examined whether A2AR protects against non-alcoholic steatohepatitis (NASH). In ...C57BL/6J mice, feeding a methionine- and choline-deficient diet (MCD) resulted in significant weight loss, overt hepatic steatosis, and massive aggregation of macrophages in the liver compared with mice fed a chow diet. MCD feeding also significantly increased the numbers of A2AR-positive macrophages/Kupffer cells in liver sections although decreasing A2AR amount in liver lysates compared with chow diet feeding. Next, MCD-induced NASH phenotype was examined in A2AR-disrupted mice and control mice. Upon MCD feeding, A2AR-disruptd mice and control mice displayed comparable decreases in body weight and fat mass. However, MCD-fed A2AR-disrupted mice revealed greater liver weight and increased severity of hepatic steatosis compared with MCD-fed control mice. Moreover, A2AR-disupted mice displayed increased severity of MCD-induced liver inflammation, indicated by massive aggregation of macrophages and increased phosphorylation states of Jun-N terminal kinase (JNK) p46 and nuclear factor kappa B (NFκB) p65 and mRNA levels of tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6. In vitro, incubation with MCD-mimicking media increased lipopolysaccharide (LPS)-induced phosphorylation states of JNK p46 and/or NFκB p65 and cytokine mRNAs in control macrophages and RAW264.7 cells, but not primary hepatocytes. Additionally, MCD-mimicking media significantly increased lipopolysaccharide-induced phosphorylation states of p38 and NFκB p65 in A2AR-deficient macrophages, but insignificantly decreased lipopolysaccharide-induced phosphorylation states of JNK p46 and NFκB p65 in A2AR-deficient hepatocytes. Collectively, these results suggest that A2AR disruption exacerbates MCD-induced NASH, which is attributable to, in large part, increased inflammatory responses in macrophages.
Background and Aims
Indole is a microbiota metabolite that exerts anti‐inflammatory responses. However, the relevance of indole to human non‐alcoholic fatty liver disease (NAFLD) is not clear. It ...also remains largely unknown whether and how indole acts to protect against NAFLD. The present study sought to examine the association between the circulating levels of indole and liver fat content in human subjects and explore the mechanisms underlying indole actions in mice with diet‐induced NAFLD.
Approach and Results
In a cohort of 137 subjects, the circulating levels of indole were reversely correlated with body mass index. In addition, the circulating levels of indole in obese subjects were significantly lower than those in lean subjects and were accompanied with increased liver fat content. At the whole‐animal level, treatment of high‐fat diet (HFD)–fed C57BL/6J mice with indole caused significant decreases in the severity of hepatic steatosis and inflammation. In cultured cells, indole treatment stimulated the expression of 6‐phosphofructo‐2‐kinase/fructose‐2,6‐biphosphatase 3 (PFKFB3), a master regulatory gene of glycolysis, and suppressed macrophage proinflammatory activation in a PFKFB3‐dependent manner. Moreover, myeloid cell–specific PFKFB3 disruption exacerbated the severity of HFD‐induced hepatic steatosis and inflammation and blunted the effect of indole on alleviating diet‐induced NAFLD phenotype.
Conclusions
Taken together, our results demonstrate that indole is relevant to human NAFLD and capable of alleviating diet‐induced NAFLD phenotypes in mice in a myeloid cell PFKFB3‐dependent manner. Therefore, indole mimetic and/or macrophage‐specific PFKFB3 activation may be the viable preventive and/or therapeutic approaches for inflammation‐associated diseases including NAFLD.
Indole is a microbiota metabolite that exerts anti-inflammatory responses. However, the relevance of indole to human non-alcoholic fatty liver disease (NAFLD) is not clear. It also remains largely ...unknown whether and how indole acts to protect against NAFLD. The present study sought to examine the association between the circulating levels of indole and liver fat content in human subjects and explore the mechanisms underlying indole actions in mice with diet-induced NAFLD. In a cohort of 137 subjects, the circulating levels of indole were reversely correlated with body mass index. In addition, the circulating levels of indole in obese subjects were significantly lower than those in lean subjects and were accompanied with increased liver fat content. At the whole animal level, treatment of high-fat diet (HFD)-fed C57BL/6J with indole caused significant decreases in the severity of hepatic steatosis and inflammation. In cultured cells, indole treatment stimulated the expression of PFKFB3, a master regulatory gene of glycolysis, and suppressed macrophage proinflammatory activation in a PFKFB3-dependent manner. Moreover, myeloid cell-specific PFKFB3 disruption exacerbated the severity of HFD-induced hepatic steatosis and inflammation, and blunted the effect of indole on alleviating diet-induced NAFLD phenotype.
CONCLUSIONS:
Taken together, our results demonstrate that indole is relevant to human NAFLD, and is capable of alleviating diet-induced NAFLD phenotypes in mice in a myeloid cell PFKFB3-dependnet manner. Therefore, indole mimetic and/or macrophage-specific PFKFB3 activation may be the viable preventive and/or therapeutic approaches for inflammation-associated diseases including NAFLD.
Colorectal cancer is one of the most common solid malignancies in western developed countries. Epidemiological evidence suggests that a diet rich in fruits and vegetables (including garlic), and low ...in saturated fat and red meat, may be protective against colorectal cancer. Organosulfur compounds (OSCs) present in garlic have been studied for the ability to inhibit experimental cancer in various animal models, primarily through modification of carcinogen detoxification enzymes, such as cytochrome P450 (CYP) enzymes. OSCs vary in structural and physical properties, and a detailed analysis of these properties has not been performed with respect to their ability of inhibit chemically-induced or genetically-induced colon cancer development. Diallyl sulfide (DAS) inhibits hepatic CYP2E1 protein levels in a time- and dose-dependent manner. Treatment of rats with 200 mg/kg DAS and allyl methyl sulfide (AMS) significantly decreased hepatic CYP2E1 protein by 62 and 48%, respectively, and this inhibition was sustained with chronic treatment by these compounds. Diallyl disulfide (DADS), dipropyl sulfide (DPS), dipropyl disulfide (DPDS), propyl methyl sulfide (PMS) and S-allylcysteine (SAC) did not inhibit CYP2E1, indicating that the presence of an allylic side chain and a single sulfur atom in a lipophilic compound is necessary for CYP2E1 inhibition. None of the OSCs affected CYP2E1 mRNA levels. Acute dosing with 200 mg/kg DAS and AMS significantly increased hepatic CYP1A2 protein (but not mRNA) levels by 280 and 73%, respectively, and DAS significantly increased CYP1A1 levels by 685%. These effects were not observed after 1 week of treatment with DAS and AMS. However, chronic treatment with these compounds caused further induction of CYP1A1 after 4 weeks of treatment (DAS: 251% at 4 weeks, 620% at 8 weeks; AMS: 1633% at 8 weeks), and CYP1A2 after 8 weeks of treatment (DAS, 48%; AMS, 240%). Acute dosing with 200 mg/kg DAS, DADS, DPS and PMS significantly increased hepatic CYP3A2 protein levels. AMS, DPDS and SAC also increased CYP3A2, but the results were not significant. Chronic dosing with DAS and AMS increased hepatic, but not intestinal, CYP3A2. Chronic dosing with 200 mg/kg DAS, but not AMS or lower doses of DAS, induced bile duct obstruction and focal areas of necrosis. SAC significantly reduced small intestinal tumor formation, and DADS caused a non-significant decrease in colon tumor number and size in APCmin +/− mice. These results indicate that OSCs present in garlic, particularly DAS and AMS, may be beneficial in inhibiting colon cancer development.
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