October 5, 2006; doi:10.1152/ajpgi.00024.2006.-A small percentage of pathologically obese subjects with fatty livers develop histological signs of necroinflammation and fibrosis, suggesting a variety of cofactors in the pathogenesis of obesity-related liver diseases including nonalcoholic steatohepatitis. Since several observations have linked bacterial endotoxins to liver damage, the aim of this study was to determine the effect of obesity on intestinal mucosal integrity and portal blood endotoxemia in two strains of obese mice: leptin-deficient (ob/ob) and hyperleptinemic (db/db) mice. Murine intestinal mucosal barrier function was assessed using a Ussing chamber, whereas ileum tight junction proteins were analyzed by immunocytochemistry and Western blot analysis. Circulating proinflammatory cytokines and portal blood endotoxin levels were measured by ELISA and the limulus test, respectively. The inflammatory and fibrogenic phenotype of murine hepatic stellate cells (HSCs) was determined by ELISA and quantitative RT-PCR. Ob/ob and db/db mice showed lower intestinal resistance, profoundly modified distribution of occludin and zonula occludens-1 in the intestinal mucosa, and higher circulating levels of inflammatory cytokines and portal endotoxemia compared with lean control mice. Moreover, HSCs isolated from ob/ob and db/db mice showed higher membrane CD14 mRNA levels and more pronounced lipopolysaccharide-induced proinflammatory and fibrogenic responses than HSCs from lean animals. In conclusion, genetically obese mice display enhanced intestinal permeability leading to increased portal endotoxemia that makes HSCs more sensitive to bacterial endotoxins. We suggest that in metabolic syndrome, patients may likewise have a greater intestinal mucosa permeability and increased lipopolysaccharide levels in portal blood that can contribute to the liver inflammatory damage.

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Brun, Paola, Ignazio Castagliuolo, Massimo Pinzani, Giorgio Palù , and Diego Martines. Exposure to bacterial cell wall products triggers an inflammatory phenotype in hepatic stellate cells. Activated hepatic stellate cells (HSCs) secrete extracellular matrix components during hepatic fibrosis, but recent studies have shown that HSCs can also release a variety of proinflammatory cytokines. Moreover, bacterial endotoxemia is not only associated with systemic complications in the late stages of liver failure but is also a direct cause of liver damage, activating resident inflammatory cells. In this study, we investigated whether HSCs can respond directly to bacterial cell wall products acquiring a new phenotype. RT-PCR and immunocytochemistry assays were used to show that murine HSCs expressed specific mRNA transcripts and proteins for LPS and lipoteichoic acid (LTA) receptor systems and peptidoglycan recognition proteins. Exposing HSCs to bacterial endotoxins led to phosphorylation of mitogenactivated protein kinase ERK1 and the development of a proinflammatory phenotype. After exposure to LPS, LTA, or N-acetyl muramyl peptide, transforming growth factor-␤1, IL-6, and monocyte chemoattractant protein-1 (MCP-1) mRNA specific transcripts and proteins increased significantly in HSCs, as assayed by quantitative real-time RT-PCR and ELISA. These LPS-mediated effects in HSCs were receptor dependent, because LPS-induced ERK1 phosphorylation, IL-6, and MCP-1 mRNA and protein level upregulation were significantly less pronounced in HSCs isolated from C3H/HeJ mice lacking Toll-like receptor 4. In conclusion, our results show that murine HSCs express functional receptors for bacterial endotoxins, and HSCs exposed to bacterial products develop a strong proinflammatory phenotype. We speculate that high levels of bacterial endotoxins in the portal vein may directly induce a proinflammatory phenotype in HSCs that contributes to liver damage.

Fecal calprotectin and lactoferrin appear to be equally recommendable as inflammatory disease markers in patients with lower gastrointestinal symptoms. Both tests are needed to accurately discriminate activity in inflammatory bowel disease patients.

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Oxidative DNA damage accumulates with the duration of the disease in ulcerative colitis reaching maximal increase if dysplastic lesions are found with possible implications for mutagenic and carcinogenic progression.

Hepatocellular carcinoma (HCC) and liver cirrhosis (LC) are not well-established vinyl chloride monomer (VCM)–induced diseases. Our aim was to appraise the role of VCM, alcohol intake, and viral hepatitis infection, and their interactions, in the etiology of HCC and LC. Thirteen cases of HCC and 40 cases of LC were separately compared with 139 referents without chronic liver diseases or cancer in a case–referent study nested in a cohort of 1,658 VCM workers. The odds ratios (ORs) and the 95% confidence intervals (CIs) were estimated by common methods and by fitting models of logistic regression. We used Rothman’s synergy index (S) to evaluate interactions. By holding the confounding factors constant at logistic regression analysis, each extra increase of 1,000 ppm × years of VCM cumulative exposure was found to increase the risk of HCC by 71% (OR = 1.71; 95% CI, 1.28–2.44) and the risk of LC by 37% (OR = 1.37; 95% CI, 1.13–1.69). The joint effect of VCM exposure above 2,500 ppm × years and alcohol intake above 60 g/day resulted in ORs of 409 (95% CI, 19.6–8,553) for HCC and 752 (95% CI, 55.3–10,248) for LC; both S indexes suggested a synergistic effect. The joint effect of VCM exposure above 2,500 ppm × years and viral hepatitis infection was 210 (95% CI, 7.13–6,203) for HCC and 80.5 (95% CI, 3.67–1,763) for LC; both S indexes suggested an additive effect. In conclusion, according to our findings, VCM exposure appears to be an independent risk factor for HCC and LC interacting synergistically with alcohol consumption and additively with viral hepatitis infection.