Non-alcoholic fatty liver DISEASE (NAFLD) is the most common chronic liver disease in Western countries and affects approximately 25% of the adult population. Since NAFLD is frequently associated with further metabolic comorbidities such as obesity, type 2 diabetes mellitus, or dyslipidemia, it is generally considered as the hepatic manifestation of the metabolic syndrome. In addition to its potential to cause liver-related morbidity and mortality, NAFLD is also associated with subclinical and clinical cardiovascular disease (CVD). Growing evidence indicates that patients with NAFLD are at substantial risk for the development of hypertension, coronary heart disease, cardiomyopathy, and cardiac arrhythmias, which clinically result in increased cardiovascular morbidity and mortality. The natural history of NAFLD is variable and the vast majority of patients will not progress from simple steatosis to fibrosis and end stage liver disease. However, patients with progressive forms of NAFLD, including non-alcoholic steatohepatitis (NASH) and/or advanced fibrosis, as well as NAFLD patients with concomitant types 2 diabetes are at highest risk for CVD. This review describes the underlying pathophysiological mechanisms linking NAFLD and CVD, discusses the role of NAFLD as a metabolic dysfunction associated cardiovascular risk factor, and focuses on common cardiovascular manifestations in NAFLD patients.
Preclinical studies support a critical role of 5-HT receptors (5-HTRs) in depression and anxiety, but their influence in depression- and anxiety-like behaviours and the effects of antidepressants remain partly unknown. We evaluated 5-HTR knockout (KO) mice in different anxiety and depression paradigms and mRNA expression of some neuroplasticity markers (BDNF, trkB and Arc) and the functionality of 5-HTR. Moreover, the implication of 5-HTRs in the behavioural and molecular effects of chronically administered fluoxetine was assessed in naïve and olfactory bulbectomized mice (OBX) of both genotypes. 5-HTR KO mice displayed few specific behavioural impairments including reduced central activity in the open-field (anxiety), and decreased sucrose consumption and nesting behaviour (anhedonia). In these mice, we measured increased levels of BDNF and Arc mRNA and reduced levels of trkB mRNA in the hippocampus, and a desensitization of 5-HT autoreceptors. Chronic administration of fluoxetine elicited similar behavioural effects in WT and 5-HTR KO mice on anxiety-and depression-related tests. Following OBX, locomotor hyperactivity and anxiety were similar in both genotypes. Interestingly, chronic fluoxetine failed to reverse this OBX-induced syndrome in 5-HTR KO mice, a response associated with differential effects in hippocampal neuroplasticity biomarkers. Fluoxetine reduced hippocampal Arc and BDNF mRNA expressions in WT but not 5-HTR KO mice subjected to OBX. These results demonstrate that the absence of 5-HTRs triggers adaptive changes that could maintain emotional states, and that the behavioural and molecular effects of fluoxetine under pathological depression appear to be critically dependent on 5-HTRs.
Background and Aim
Several studies observed alterations in the gut microbiota in patients with non‐alcoholic fatty liver disease (NAFLD). However, analyzed patient populations and methods strongly differ among these studies. The aim of this study was to prove the reproducibility of published results and to provide a detailed overview of all findings in our NAFLD cohort using next generation sequencing methods.
Methods
The individual taxonomic microbiota composition of fecal samples from 90 NAFLD patients and 21 healthy controls was analyzed using 16S rRNA gene sequencing. Study participants were grouped according to their disease stage and compared regarding their gut microbiota composition. Studies were identified from PubMed listed publications, and the results were compared with the findings in our cohort.
Results
Results from 13 identified studies were compared with our data. A decreased abundance of the Bacteroidetes and Ruminococcaceae as well as an increased abundance of Lactobacillaceae and Veillonellaceae and Dorea were the most frequently reported changes among NAFLD patients in 4/13, 5/13, 4/13, 2/13, and 3/13 studies, respectively. Even though these alterations in the gut microbiota composition were also observed in our patient cohort, the majority of published differences could not be reproduced, neither in our own nor in other NAFLD cohort studies.
Conclusion
Despite repeatedly reproduced abundance patterns of specific bacteria, the heterogeneous study results did not reveal a consistent disease specific gut microbiota signature. Further prospective studies with homogenous patient cohorts and standardized methods are necessary to phenotype NAFLD by the gut microbiota.
Overconsumption of carbohydrates and lipids are well known to cause nonalcoholic fatty liver disease (NAFLD), while the role of nutritional protein intake is less clear. In Western diet, meat and other animal products are the main protein source, with varying concentrations of specific amino acids. Whether the amount or composition of protein intake is associated with a higher risk for disease severity has not yet been examined. In this study, we investigated associations of dietary components with histological disease activity by analyzing detailed 14-day food records in a cohort of 61 patients with biopsy-proven NAFLD. Furthermore, we used 16S ribosomal RNA gene sequencing to detect associations with different abundances of the gut microbiota with dietary patterns. Patients with definite nonalcoholic steatohepatitis (NAFLD activity score of 5-8 on liver biopsy) had a significantly higher daily relative intake of protein compared with patients with a NAFLD activity score of 0-4 (18.0% vs. 15.8% of daily protein-based calories, P = 0.018). After adjustment for several potentially confounding factors, a higher protein intake (≥17.3% of daily protein-based calories) remained associated with definite nonalcoholic steatohepatitis, with an odds ratio of 5.09 (95% confidence interval 1.22-21.25, P = 0.026). This association was driven primarily by serine, glycine, arginine, proline, phenylalanine, and methionine. A higher protein intake correlated with a lower Bacteroides abundance and an altered abundance of several other bacterial taxa. Conclusion: A high protein intake was independently associated with more active and severe histological disease activity in patients with NAFLD. Further studies are needed to investigate the potential harmful role of dietary amino acids on NAFLD, with special attention to meat as their major source. (Hepatology Communications 2020;4:681-695).
Several studies show associations between gut bacterial dysbiosis and chronic liver diseases, but causative mechanisms are largely unclear. We recently identified cytolysin, a bacterial exotoxin expressed and secreted by Enterococcus faecalis to cause liver damage in the setting of alcohol‐related liver disease. Cytolysin was increased and highly correlated with liver disease severity and mortality in alcoholic hepatitis patients. In this study, we investigated if faecal cytolysin‐positivity can be linked to non‐alcoholic fatty liver disease, a highly prevalent disease where new biomarkers and treatment targets are urgently needed. In contrast to what we observed in alcoholic hepatitis, only seven out of 96 non‐alcoholic fatty liver disease patients were cytolysin‐positive, and these patients did not have increased liver disease activity compared with cytolysin‐negative patients. These results indicate that the association of cytolysin carriage with worse clinical outcome might be specific for alcoholic hepatitis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.