Non-alcoholic fatty liver disease and the impact of genetic, epigenetic and environmental factors in the offspring

Exploration of Perturbed Liver Fibrosis-Related Factors and Collagen Type I in Animal Model of Non-Alcoholic Fatty Liver Disease

To determine their involvement in the onset of the disease, we investigated the changing levels of liver fibrosis-related proteins, namely, type-I collagen, α-smooth muscle actin (α-SMA), and transforming growth factor β1 and β3 (TGF-β1, β3). The four groups of Sprague-Dawley (SD) rats were involved in the study, namely, (i) normal control group, (ii) high-fat diet group (HFD), (iii) carbon tetrachloride (CCl4) group, and (iv) NAFLD group (animal model) which were chosen at random. The NAFLD model received HFD combined with subcutaneous injection of small doses of CCl4. Histopathological examination confirmed extent of liver fibrosis, while other immunological and molecular methods were used to evaluate expression and distribution of α-SMA, type I collagen TGF-β1 and TGF-β3, at both m-RNA and protein levels. In contrast to the normal control group, the NAFLD group showed moderately elevated expressions of TGF-β1, α-SMA, and type I collagen, which was proportional on temporal scale of NAFLD persistence in the model (P < 0.05). In the early phage of NAFLD, enhancement in the mRNA transcripts and, henceforth, protein expression of TGF-β3 was observed. However, these were found to be downregulated in case of liver fibrosis (P < 0.05). This NAFLD rat model shows the histopathologic changes of human NAFLD and is suitable for the study of NAFLD pathogenesis. These findings suggest that type I collagen and the liver fibrosis-related factors TGF- β1, TGF- β3, and α-SMA may be significant contributors to NAFLD. Although NAFLD model is previously demonstrated by other researchers, our study is novel in terms of exploration of involvement of fibrosis-related factors and in particular aforementioned proteins at the early stage of NAFLD vis-à-vis dynamics of type-I collagen distribution.

Parental History of Type 2 Diabetes Mellitus and PNPLA3 Polymorphism Increase the Risk of Severe Stages of Nonalcoholic Fatty Liver Disease

BACKGROUND & AIMS

In non-alcoholic fatty liver disease (NAFLD), the influence of parental history of type 2 diabetes (T2D) allied to single nucleotide polymorphisms (SNPs) in the offspring is not known. We aimed to investigate the impact of the parental history of T2D, PNPLA3 and TM6SF2 polymorphisms in liver steatosis and fibrosis.

METHODS

This was a case-control study involving the offspring of T2D patients and controls without a parental history of T2D. Participants underwent clinical and laboratory evaluation, transient elastography (TE) by Fibroscan® (Echosens, Fr) and genotyping for PNPLA3 and TM6SF2. Multivariate logistic regression evaluated the influence of parental history of T2D on liver steatosis and fibrosis, controlled for age, gender, metabolic traits and SNPs.

RESULTS

161 T2D offspring and 78 controls, 10-46 years old, were included. The offspring of T2D had higher prevalences of obesity, T2D, arterial hypertension and sedentarism. Parental history of T2D was associated with fibrosis ≥ F2 (OR 8.89, CI 95% 1.09-72.01, p = 0.041) after adjustment for age, gender, metabolic traits and SNPs. PNPLA3 GG genotype was independently associated with steatosis ≥ S1 (OR 8.15, CI 95% 1.93-34.38, p = 0.004) and fibrosis ≥ F2 (OR 4.31, CI 95% 1.11-16.61, p = 0.034).

CONCLUSIONS

The offspring of T2D patients present a worse metabolic profile and the parental history of T2D confers an increased likelihood of hepatic fibrosis, independent of metabolic factors. PNPLA3 homozygous GG, but not TM6SF2 genotypes, also impacts on this phenotype.

Immunomodulation in non-alcoholic fatty liver disease: exploring mechanisms and applications

Non-alcoholic fatty liver disease (NAFLD) exhibits increased lipid enrichment in hepatocytes. The spectrum of this disease includes stages such as nonalcoholic simple fatty liver (NAFL), nonalcoholic steatohepatitis (NASH), and liver fibrosis. Changes in lifestyle behaviors have been a major factor contributing to the increased cases of NAFLD patients globally. Therefore, it is imperative to explore the pathogenesis of NAFLD, identify therapeutic targets, and develop new strategies to improve the clinical management of the disease. Immunoregulation is a strategy through which the organism recognizes and eliminates antigenic foreign bodies to maintain physiological homeostasis. In this process, multiple factors, including immune cells, signaling molecules, and cytokines, play a role in governing the evolution of NAFLD. This review seeks to encapsulate the advancements in research regarding immune regulation in NAFLD, spanning from underlying mechanisms to practical applications.

Identification and validation of key biomarkers associated with macrophages in nonalcoholic fatty liver disease based on hdWGCNA and machine learning

BACKGROUND

NAFLD has attracted increasing attention because of its high prevalence and risk of progression to cirrhosis or even hepatocellular carcinoma. Therefore, research into the root causes and molecular indicators of NAFLD is crucial.

METHODS

We analyzed scRNA-seq data and RNA-seq data from normal and NAFLD liver samples. We utilized hdWGCNA to find module-related genes associated with the phenotype. Multiple machine learning algorithms were used to validate the model diagnostics and further screen for genes that are characteristic of NAFLD. The NAFLD mouse model was constructed using the MCD diet to validate the diagnostic effect of the genes.

RESULTS

We identified a specific macrophage population called NASH-macrophages by single-cell sequencing analysis. Cell communication analysis and Pseudo-time trajectory analysis revealed the specific role and temporal distribution of NASH-macrophages in NAFLD. The hdWGCNA screening yielded 30 genes associated with NASH-macrophages, and machine learning algorithms screened and obtained two genes characterizing NAFLD. The immune infiltration indicated that these genes were highly associated with macrophages. Notably, we verified by RT-qPCR, IHC, and WB that MAFB and CX3CR1 are highly expressed in the MCD mouse model and may play important roles.

CONCLUSIONS

Our study revealed a macrophage population that is closely associated with NAFLD. Using hdWGCNA analysis and multiple machine learning algorithms, we identified two NAFLD signature genes that are highly correlated with macrophages. Our findings may provide potential feature markers and therapeutic targets for NAFLD.

MicroRNAs as Biomarkers and Therapeutic Targets for Nonalcoholic Fatty Liver Disease: A Narrative Review

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world. However, biomarkers for NAFLD diagnosis and liver-specific drugs for treatment are lacking. This article reviews the possibility of circulating miRNAs in the diagnosis and treatment of NAFLD diseases and focuses on several well-studied miRNAs to provide preclinical data for subsequent related studies.

METHODS

Related articles were identified through searches of the PubMed database for literature published from 2010 to December 2022. Search terms included NAFLD, microRNA, biomarker, diagnosis, and therapy.

FINDINGS

Current research data indicate that some key circulating miRNAs may be used as diagnostic biomarkers of NAFLD and the combination of several miRNAs improves diagnostic performance. In addition, some preclinical trials using cell and mouse models provide a basis for some miRNAs as potential therapeutic targets.

IMPLICATIONS

Current evidence suggests that circulating miRNAs are potential noninvasive biomarkers for clinical diagnosis of NAFLD, which needs to be validated in more heterogeneous and larger cohorts. In addition, several miRNAs regulate multiple downstream pathways related to the pathophysiology of NAFLD in a cell- and tissue-specific manner, making them attractive drug therapeutic targets for NAFLD. However, more preclinical and clinical trials are needed for these miRNAs to become therapeutic targets of NAFLD.

Genetic Polymorphisms and Diversity in Nonalcoholic Fatty Liver Disease (NAFLD): A Mini Review

Nonalcoholic fatty liver disease (NAFLD) is a common liver disease with a wide spectrum of liver conditions ranging from hepatic steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The prevalence of NAFLD varies across populations, and different ethnicities have specific risks for the disease. NAFLD is a multi-factorial disease where the genetics, metabolic, and environmental factors interplay and modulate the disease's development and progression. Several genetic polymorphisms have been identified and are associated with the disease risk. This mini-review discussed the NAFLD's genetic polymorphisms and focusing on the differences in the findings between the populations (diversity), including of those reports that did not show any significant association. The challenges of genetic diversity are also summarized. Understanding the genetic contribution of NAFLD will allow for better diagnosis and management explicitly tailored for the various populations.