Serum miRNA-122 expression in non-alcoholic fatty liver disease among Egyptian patients and its correlation with interleukin-1A gene polymorphism

The Management of Cardiometabolic Risk in MAFLD: Therapeutic Strategies to Modulate Deranged Metabolism and Cholesterol Levels

Background and Objectives: Fatty Liver Disease is a major health problem worldwide. We can distinguish liver steatosis as non-associated or associated with chronic/acute alcohol consumption. These two entities share similar stages ranging from hepatic fat storage (namely, steatosis) to inflammation, necrosis, and fibrosis until hepatocellular carcinoma (HCC). Over time, "Metabolic Associated Fatty Liver Disease" (MAFLD) has replaced nonalcoholic fatty liver disease (NAFLD) nomenclature and has included cardiometabolic criteria in these patients definition. Thus, obesity, type 2 diabetes mellitus (T2DM), hypertension, and dyslipidemia are MAFLD features and are of the metabolic syndrome. Importantly, there is not a specific treatment for MAFLD, but there are therapeutic strategies that act on metabolic dysfunction related to MAFLD. They can reduce the progression of liver fibrosis and its complications. Materials and Methods: For all these reasons, we conducted a narrative review of the literature, and we focused on metabolic dysfunction related to MAFLD, with a special regard for cholesterol metabolism. Results: MAFLD is a recently redefined condition that better describes the metabolism derangement responsible for fatty liver disease. This distinguishes MAFLD from NAFLD. In fact, the diagnostic criteria for MAFLD require the presence of liver steatosis together with at least one of the following: obesity, T2DM, or evidence of metabolic disorder such as hypertriglyceridemia, low high-density lipoprotein cholesterol, or hypertension. As a result, MAFLD is closely linked to an increased cardiometabolic risk. Current therapeutic approaches can be used to reduce this risk, focusing on lifestyle interventions and pharmacological strategies. Several treatments in patients diagnosed with MAFLD are mainly cholesterol-lowering remedies. Among these, Pro-protein Convertase Subtilisin/Kexin type 9 inhibitors (PCSK9i) show the most promising efficacy profile but data on liver fibrosis are lacking. Agonists of GLP-1 receptor, Sodium-glucose cotransporter-2 inhibitors (SGLT2i) and Dipeptidyl Peptidase-4 inhibitors (DPP-4i) have a " multi-hit " action allowing their use also in diabetic patients with MAFLD. Conclusions: Lifestyle modifications, some nutraceuticals, statins, incretins, and PCSK9i have changed the natural course and significantly improved the cardiometabolic outcomes of MAFLD. Emerging cholesterol-lowering drugs, such as Bempedoic acid, can overcome low compliance to statins' use and their controversial effect on liver fibrosis. Finally, medications targeting insulin resistance allow for strategic interventions of the convoluted pathophysiology of MAFLD in multiple steps, with the potential to reduce liver steatosis, inflammation, and necrosis and, sometimes even to reverse liver fibrosis.

miR-122/PPARβ axis is involved in hypoxic exercise and modulates fatty acid metabolism in skeletal muscle of obese rats

Hypoxic exercise is an effective intervention for obesity, because it promotes weight loss by regulating fatty acid (FA) metabolism. The regulation of peroxisome proliferator-activated receptor β (PPARβ) by miR-122 may be involved in this process, but the detailed mechanisms are unknown. In order to address this issue, we probed how miR-122 affected the expression of factors associated with FA metabolism in skeletal muscle of obese rats undergoing hypoxic training. By injecting adeno-associated virus 9 containing miR-122 overexpression vector or miR-122 inhibitor into skeletal muscles of rats with a 4-week hypoxic exercise regimen, the miR-122 expression level can be regulated. Body composition and blood lipid levels were analyzed, and PPARβ, carnitine palmitoyltransferase 1b (CPT1b), acetylCoA carboxylase 2 (ACC2), and FA synthase (FAS) mRNA and protein levels were evaluated using quantitative reverse transcription quantitative PCR(RT-qPCR) and Western blot analysis. We found that miR-122 overexpression increased low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) levels and decreased PPARβ, ACC2, and FAS expression. Conversely, miR-122 inhibition decreased TG level, increased high-density lipoprotein cholesterol (HDL-C) level, and upregulated PPARβ, ACC2, FAS, and CPT1b. These data indicated that the negative regulation of PPARβ by miR-122 promotes FA metabolism by altering the levels of the factors related to FA metabolism in skeletal muscle of obese rat under hypoxic training, thus providing molecular-level insight into the beneficial effects of this intervention.

Investigating microRNAs to Explain the Link between Cholesterol Metabolism and NAFLD in Humans: A Systematic Review

Non-Alcoholic Fatty Liver Disease (NAFLD) is characterized by hepatic free cholesterol accumulation. In addition, microRNAs (miRNAs) might be involved in NAFLD development. Therefore, we systematically reviewed the literature to examine the link between miRNAs and cholesterol metabolism in NAFLD. Nineteen studies were retrieved by a systematic search in September 2022. From these papers, we evaluated associations between 13 miRNAs with NAFLD and cholesterol metabolism. Additionally, their diagnostic potential was examined. Four miRNAs (miR122, 34a, 132 and 21) were associated with cholesterol metabolism and markers for NAFLD. MiR122 was upregulated in serum of NAFLD patients, increased with disease severity and correlated with HDL-C, TAG, VLDL-C, AST, ALT, ALP, lobular inflammation, hepatocellular ballooning and NAFLD score. Serum and hepatic levels also correlated. Serum and hepatic miR34a levels were increased in NAFLD, and correlated with VLDL-C and TAG. Serum miR379 was also higher in NAFLD, especially in early stages, while miR21 gave ambiguous results. The diagnostic properties of these miRNAs were comparable to those of existing biomarkers. However, serum miR122 levels appeared to be elevated before increases in ALT and AST were evident. In conclusion, miR122, miR34a, miR21 and miR132 may play a role in the development of NAFLD via effects on cholesterol metabolism. Furthermore, it needs to be explored if miRNAs 122, 34a and 379 could be used as part of a panel in addition to established biomarkers in early detection of NAFLD.

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.