Gender and gut microbiota composition determine hepatic bile acid, metabolic and inflammatory response to a single fast-food meal in healthy adults.

BACKGROUND & AIMS: Regular consumption of fast-food (FF) as a form of typical Western style diet is associated with obesity and the metabolic syndrome, including its hepatic manifestation nonalcoholic fatty liver disease. Currently, it remains unclear how intermittent excess FF consumption may influence liver metabolism. The study aimed to characterize the effects of a single FF binge on hepatic steatosis, inflammation, bile acid (BA), glucose and lipid metabolism. METHODS: Twenty-five healthy individuals received a FF meal and were asked to continue eating either for a two-hour period or until fully saturated. Serum levels of transaminases, fasting BA, lipid profile, glucose and cytokine levels as well as transient elastography and controlled attenuation parameter (CAP; to assess hepatic steatosis) were analyzed before (day 0) and the day after FF binge (day 1). Feces was collected prior and after the FF challenge for microbiota analysis. RESULTS: The FF meal induced a modest increase in CAP, which was accompanied by a robust increase of fasting serum BA levels. Surprisingly, levels of cholesterol and bilirubin were significantly lower after the FF meal. Differentiating individuals with a relevant delta BA (>1 µmol/l) increase vs. individuals without (delta BA ≤1 µmol/l), identified several gut microbiota, as well as gender to be associated with the BA increase and the observed alterations in liver function, metabolism and inflammation. CONCLUSION: A single binge FF meal leads to a robust increase in serum BA levels and alterations in parameters of liver injury and metabolism, indicating a novel metabolic aspect of the gut-liver axis.

Partial hepatectomy in mice.

The surgical procedure of two-thirds partial hepatectomy (PH) in rodents was first described more than 80 years ago by Higgins and Anderson. Nevertheless, this technique is still a state-of-the-art method for the community of liver researchers as it allows the in-depth analysis of signalling pathways involved in liver regeneration and hepatocarcinogenesis. The importance of PH as a key method in experimental hepatology has even increased in the last decade due to the increasing availability of genetically-modified mouse strains. Here, we propose a standard operating procedure (SOP) for the implementation of PH in mice, which is based on our experience of more than 10 years. In particular, the SOP offers all relevant background information on the PH model and provides comprehensive guidelines for planning and performing PH experiments. We provide established recommendations regarding optimal age and gender of animals, use of appropriate anaesthesia and biometric calculation of the experiments. We finally present an easy-to-follow step-by-step description of the complete surgical procedure including required materials, critical steps and postoperative management. This SOP especially takes into account the latest changes in animal welfare rules in the European Union but is still in agreement with current international regulations. In summary, this article provides comprehensive information for the legal application, design and implementation of PH experiments.

Lack of gp130 expression in hepatocytes attenuates tumor progression in the DEN model.

Chronic liver inflammation is a crucial event in the development and growth of hepatocellular carcinoma (HCC). Compelling evidence has shown that interleukin-6 (IL-6)/gp130-dependent signaling has a fundamental role in liver carcinogenesis. Thus, in the present study we aimed to investigate the role of gp130 in hepatocytes for the initiation and progression of HCC. Hepatocyte-specific gp130 knockout mice (gp130(Δhepa)) and control animals (gp130(f/f)) were treated with diethylnitrosamine (DEN). The role of gp130 for acute injury (0-144 h post treatment), tumor initiation (24 weeks) and progression (40 weeks) was analyzed. After acute DEN-induced liver injury we observed a reduction in the inflammatory response in gp130(Δhepa) animals as reflected by decreased levels of IL-6 and oncostatin M. The loss of gp130 slightly attenuated the initiation of HCC 24 weeks after DEN treatment. In contrast, 40 weeks after DEN treatment, male and female gp130(Δhepa) mice showed smaller tumors and reduced tumor burden, indicating a role for hepatocyte-specific gp130 expression during HCC progression. Oxidative stress and DNA damage were substantially and similarly increased by DEN in both gp130(f/f) and gp130(Δhepa) animals. However, gp130(Δhepa) livers revealed aberrant STAT5 activation and decreased levels of transforming growth factor-ß (TGFß), pSMAD2/3 and SMAD2, whereas phosphorylation of STAT3 at Tyr705 and Ser727 was absent. Our results indicate that gp130 deletion in hepatocytes reduces progression, but not HCC initiation in the DEN model. Gp130 deletion resulted in STAT3 inhibition but increased STAT5 activation and diminished TGF-dependent signaling. Hence, blocking gp130 in hepatocytes might be an interesting therapeutic target to inhibit the growth of HCC.

TNFR1 determines progression of chronic liver injury in the IKKγ/Nemo genetic model.

Death receptor-mediated hepatocyte apoptosis is implicated in a wide range of liver diseases including viral and alcoholic hepatitis, ischemia/reperfusion injury, fulminant hepatic failure, cholestatic liver injury, as well as cancer. Deletion of NF-κB essential modulator in hepatocytes (IKKγ/Nemo) causes spontaneous progression of TNF-mediated chronic hepatitis to hepatocellular carcinoma (HCC). Thus, we analyzed the role of death receptors including TNFR1 and TRAIL in the regulation of cell death and the progression of liver injury in IKKγ/Nemo-deleted livers. We crossed hepatocyte-specific IKKγ/Nemo knockout mice (Nemo(Δhepa)) with constitutive TNFR1(-/-) and TRAIL(-/-) mice. Deletion of TNFR1, but not TRAIL, decreased apoptotic cell death, compensatory proliferation, liver fibrogenesis, infiltration of immune cells as well as pro-inflammatory cytokines, and indicators of tumor growth during the progression of chronic liver injury. These events were associated with diminished JNK activation. In contrast, deletion of TNFR1 in bone-marrow-derived cells promoted chronic liver injury. Our data demonstrate that TNF- and not TRAIL signaling determines the progression of IKKγ/Nemo-dependent chronic hepatitis. Additionally, we show that TNFR1 in hepatocytes and immune cells have different roles in chronic liver injury-a finding that has direct implications for treating chronic liver disease.