The role of genetic and epigenetic factors in non alcoholic fatty liver disease (NAFLD) pathogenesis

Mechanism of Paeoniae Radix Alba in the Treatment of Non-alcoholic Fatty Liver Disease Based on Sequential Metabolites Identification Approach, Network Pharmacology, and Binding Affinity Measurement

Screening functional food ingredients (FFI) from medicinal and edible plants (MEP) has still remained a great challenge due to the complexity of MEP and its obscure function mechanisms. Herein, an integrated strategy based on sequential metabolites identification approach, network pharmacology, molecular docking, and surface plasmon resonance (SPR) analysis was proposed for quickly identifying the active constituents in MEP. First, the sequential biotransformation process of MEP, including intestinal absorption and metabolism, and hepatic metabolism, was investigated by oral gavage, and intestinal perfusion with venous sampling method. Then the blood samples were analyzed by UPLC-Q Exactive Orbitrap HRMS. Second, the network pharmacology approach was used to explore the potential targets and possible mechanisms of the in vivo metabolites of MEP. Third, molecular docking and SPR approaches were used to verify the specific interactions between protein targets and representative ingredients. The proposed integrated strategy was successfully used to explore the heptoprotective components and the underlying molecular mechanism of Paeoniae Radix Alba (PRA). A total of 44 compounds were identified in blood samples, including 17 porotypes and 27 metabolites. The associated metabolic pathways were oxidation, methylation, sulfation, and glucuronidation. After further screening, 31 bioactive candidates and 377 related targets were obtained. In addition, the bioactive components contained in PRA may have therapeutic potentials for non-alcoholic fatty liver disease (NAFLD). The above results demonstrated the proposed strategy may provide a feasible tool for screening FFI and elaborating the complex function mechanisms of MEP.

Deciphering the role of epigenetic modifications in fatty liver disease: A systematic review

BACKGROUND

Fatty liver disease (FLD), primarily nonalcoholic fatty liver disease (NAFLD), is the most common liver disorder that affects a quarter of the global population. NAFLD is a spectrum of disease ranging from simple steatosis to nonalcoholic steatohepatitis, which is associated with increased risk of developing liver cancer. Given that the pathogenic mechanisms of fatty liver remain largely elusive, it is important to further investigate potential underlying mechanisms including epigenetic modifications. Here, we performed a systematic review of human epigenetic studies on FLD presence.

METHODS

Five bibliographic databases were screened until 28 August 2020. We included cross-sectional, case-control and cohort studies in humans that examined the association of epigenetic modifications including global, candidate or epigenome-wide methylation of DNA, noncoding RNAs and histone modifications with FLD.

RESULTS

In total 36 articles, based on 33 unique studies, consisting of 12 112 participants met the inclusion criteria. Among these, two recent epigenome-wide association studies conducted among large population-based cohorts have reported the association between cg06690548 (SLC7A11) and FLD. Moreover, several studies have demonstrated the association between microRNAs (miRNAs) and FLD, in which miR-122, miR-34a and miR-192 were recognized as the most relevant miRNAs as biomarkers for FLD. We did not find any studies examining histone modifications in relation to FLD.

CONCLUSIONS

Cumulative evidence suggests a link between epigenetic mechanisms, specifically DNA methylation and miRNAs, and FLD. Further efforts should investigate the molecular pathways by which these epigenetic markers may regulate FLD and also the potential role of histone modifications in FLD.

The effect of PNPLA3 polymorphism as gain in function mutation in the pathogenesis of non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is often associated with metabolic syndrome (type 2 diabetes, hypertension, hypertriglyceridemia, insulin resistance, and obesity). NAFLD is multi-factorial in pathogenesis with some genetic predisposition. The variant patatin-like phospholipase domain-containing protein 3 (PNPLA3) is known to be an independent risk factor for hepatocellular cancer (HCC). The aim of this study was to investigate the role of PNPLA3 polymorphism as the risk factor for NAFLD.

METHODOLOGY

Patients had histological, ultrasonographic, biopsy evidence of NAFLD (n=248) and 81 controls were studied for PNPLA3 polymorphism. PNPLA3 genotyping was done from peripheral blood DNA by real-time polymerase chain reaction (RT-PCR).

RESULTS

PNPLA3 genotyping of the groups NAFLD (CC [n = 76], CG [n = 83], GG [n = 89]) and control (CC [n= 42], CG [n = 22], GG [n = 17]) was determined. In the patient group, the G allele was 261 (52.63%) and the C allele was 235 (47.37%), whereas in the control group, the G allele was 56 (34.54%) and the C allele was 106 (65.43%). In our study, 53 out of 174 women had GG allele and 54 out of 155 men had GG allele.

CONCLUSION

The findings suggest that there is a predominant relationship between men with PNPLA3 I148M variant with NAFLD in women. Patients with NAFLD carrying PNPLA3 rs738409 G>C variant are at higher risk of NAFLD.