Role of MicroRNAs in NAFLD/NASH

miR-21: A therapeutic target for delaying severe liver disease and hepatocellular carcinoma in high-fat-diet-fed mice

Liver disease, including hepatocellular carcinoma (HCC), is a major global health concern, claiming approximately 2 million lives worldwide annually, yet curative treatments remain elusive. In this study, we aimed to investigate the role of microRNA-21-5p (miR-21) in metabolic dysfunction-associated steatotic liver disease (previously NAFLD), metabolic-associated steatohepatitis (previously NASH), and HCC within the context of a Western high-fat diet, without additional choline (HFD) and offering potential therapeutic insights. We found that reduced miR-21 levels correlated with liver disease progression in WT mice fed on HFD, while miR-21 knockout mice showed exacerbated metabolic dysfunction, including obesity, hepatomegaly, hyperglycemia, insulin resistance, steatosis, fibrosis, and HCC. Our study reveals that miR-21 plays a protective role in metabolic syndrome and in the progression of liver disease to cancer. MiR-21 directly targets Transforming growth factor beta-induced (Tgfbi), a gene also known to be significantly upregulated and a potential oncogene in HCC. Further, our study showed that intervention with the administration of a miR-21 mimic in WT livers effectively improves insulin sensitivity, steatosis, fibrosis, Tgfbi expression and tumor burden in HFD conditions. These findings indicate that miR-21 could serve as an effective strategy to delay or prevent liver disease in high-fat-diet environments.

Dietary Pattern's Role in Hepatic Epigenetic and Dietary Recommendations for the Prevention of NAFLD

NAFLD has emerged as a significant public health concern, with its prevalence increasing globally. Emphasizing the complex relationship between dietary patterns and epigenetic modifications such as DNA methylation or miRNA expression can exert a positive impact on preventing and managing metabolic disorders, including NAFLD, within the 2030 Sustainable Development Goals. This review aims to evaluate the influence of dietary patterns on hepatic epigenetic gene modulation and provide dietary recommendations for the prevention and management of NAFLD in the general population.

METHODS

Comprehensive screening and eligibility criteria identified eleven articles focusing on epigenetic changes in NAFLD patients through dietary modifications or nutrient supplementation.

RESULTS AND DISCUSSION

Data were organized based on study types, categorizing them into evaluations of epigenetic changes in NAFLD patients through dietary pattern modifications or specific nutrient intake.

CONCLUSIONS

The study highlights the importance of dietary interventions in managing and preventing NAFLD, emphasizing the potential of dietary patterns to influence hepatic epigenetic gene modulation. This study provides valuable insights and recommendations to mitigate the risk of developing NAFLD: (i) eat a primarily plant-based diet; (ii) increase consumption of high-fiber foods; (iii) consume more polyunsaturated and monounsaturated fatty acids; (iv) limit processed foods, soft drinks, added sugars, and salt; and (v) avoid alcohol.

Nanoformulations for the diagnosis and treatment of metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive phase of metabolic dysfunction-associated steatotic liver disease (MASLD) that develops into irreversible liver cirrhosis and hepatocellular carcinoma, ultimately necessitating liver transplantation as the sole life-saving option. However, given the drawbacks of liver transplantation, including invasiveness, chronic immunosuppression, and a lack of donor livers, prompt diagnosis and effective treatment are indispensable. Due to the limitations of liver biopsy and conventional imaging modalities in diagnosing MASH, as well as the potential hazards associated with liver-protecting medicines, numerous nanoformulations have been created for MASH theranostics. Particularly, there has been significant study interest in artificial nanoparticles, natural biomaterials, and bionic nanoparticles that exhibit exceptional biocompatibility and bioavailability. In this review, we summarized extracellular vesicles (EVs)-based omics analysis and Fe3O4-based functional magnetic nanoparticles as magnetic resonance imaging (MRI) contrast agents for MASH diagnosis. Additionally, artificial nanoparticles such as organic and inorganic nanoparticles, as well as natural biomaterials such as cells and cell-derived EVs and bionic nanoparticles including cell membrane-coated nanoparticles, have also been reported for MASH treatment owing to their specific targeting and superior therapeutic effect. This review has the potential to stimulate advancements in nanoformulation fabrication techniques. By exploring their compatibility with cell biology, it could lead to the creation of innovative material systems for efficient theragnostic uses for MASH. STATEMENT OF SIGNIFICANCE: People with metabolic dysfunction-associated steatohepatitis (MASH) will progress to fibrosis, cirrhosis, or even liver cancer. It is imperative to establish effective theragnostic techniques to stop MASH from progressing into a lethal condition. In our review, we summarize the advancement of artificial, natural, and bionic nanoparticles applied in MASH theragnosis. Furthermore, the issues that need to be resolved for these cutting-edge techniques are summarized to realize a more significant clinical impact. We forecast the key fields that will advance further as nanotechnology and MASH research progress. Generally, our discovery has significant implications for the advancement of nanoformulation fabrication techniques, and their potential to be compatible with cell biology could lead to the creation of innovative materials systems for effective MASH theragnostic.

Post-translational modifications of histone and non-histone proteins in epigenetic regulation and translational applications in alcohol-associated liver disease: Challenges and research opportunities

Epigenetic regulation is a process that takes place through adaptive cellular pathways influenced by environmental factors and metabolic changes to modulate gene activity with heritable phenotypic variations without altering the DNA sequences of many target genes. Epigenetic regulation can be facilitated by diverse mechanisms: many different types of post-translational modifications (PTMs) of histone and non-histone nuclear proteins, DNA methylation, altered levels of noncoding RNAs, incorporation of histone variants, nucleosomal positioning, chromatin remodeling, etc. These factors modulate chromatin structure and stability with or without the involvement of metabolic products, depending on the cellular context of target cells or environmental stimuli, such as intake of alcohol (ethanol) or Western-style high-fat diets. Alterations of epigenetics have been actively studied, since they are frequently associated with multiple disease states. Consequently, explorations of epigenetic regulation have recently shed light on the pathogenesis and progression of alcohol-associated disorders. In this review, we highlight the roles of various types of PTMs, including less-characterized modifications of nuclear histone and non-histone proteins, in the epigenetic regulation of alcohol-associated liver disease (ALD) and other disorders. We also describe challenges in characterizing specific PTMs and suggest future opportunities for basic and translational research to prevent or treat ALD and many other disease states.

MicroRNA regulation of AMPK in nonalcoholic fatty liver disease

Obesity-associated nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is the leading cause of liver failure and death. The function of AMP-activated protein kinase (AMPK), a master energy sensor, is aberrantly reduced in NAFLD, but the underlying mechanisms are not fully understood. Increasing evidence indicates that aberrantly expressed microRNAs (miRs) are associated with impaired AMPK function in obesity and NAFLD. In this review, we discuss the emerging evidence that miRs have a role in reducing AMPK activity in NAFLD and nonalcoholic steatohepatitis (NASH), a severe form of NAFLD. We also discuss the underlying mechanisms of the aberrant expression of miRs that can negatively impact AMPK, as well as the therapeutic potential of targeting the miR-AMPK pathway for NAFLD/NASH.

Role of microRNA in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH): a comprehensive review

Non-alcoholic fatty liver disease (NAFLD) is a prevalent liver condition that affects people who do not overconsume alcohol. Uncertainties exist over how microRNAs (miRNAs) in the blood and liver relate to NAFLD. The aim of this narrative review was to investigate the role of miRNAs in the onset and progression of non-alcoholic steatohepatitis (NASH) from NAFLD, and explore their potential as diagnostic tools and treatment targets for NAFLD patients. Liver miRNA-34a levels were found to accurately represent the degree of liver damage, with lower levels suggesting more damage. In patients with NAFLD and severe liver fibrosis, higher levels of miRNA-193a-5p and miRNA-378d were found. Moreover, miRNA-34a, miRNA-122, and miRNA-192 levels might aid in differentiating NASH from NAFLD. Similar to this, miRNA-21 and miRNA-27 levels in rats were able to distinguish between steatosis and steatohepatitis. High-fat diets enhanced the expression of 15 distinct miRNAs in rats, and there were substantial differences in the miRNA expression patterns between obese and lean people. The results from the present review imply that miRNA microarrays and sequencing may be helpful diagnostic tools, and miRNAs may be a possible treatment target for patients with NAFLD.

Obesity, non-alcoholic fatty liver disease and hepatocellular carcinoma: current status and therapeutic targets

Obesity is a global epidemic and overwhelming evidence indicates that it is a risk factor for numerous cancers, including hepatocellular carcinoma (HCC), the third leading cause of cancer-related deaths worldwide. Obesity-associated hepatic tumorigenesis develops from nonalcoholic fatty liver disease (NAFLD), progressing to nonalcoholic steatohepatitis (NASH), cirrhosis and ultimately to HCC. The rising incidence of obesity is resulting in an increased prevalence of NAFLD and NASH, and subsequently HCC. Obesity represents an increasingly important underlying etiology of HCC, in particular as the other leading causes of HCC such as hepatitis infection, are declining due to effective treatments and vaccines. In this review, we provide a comprehensive overview of the molecular mechanisms and cellular signaling pathways involved in the pathogenesis of obesity-associated HCC. We summarize the preclinical experimental animal models available to study the features of NAFLD/NASH/HCC, and the non-invasive methods to diagnose NAFLD, NASH and early-stage HCC. Finally, since HCC is an aggressive tumor with a 5-year survival of less than 20%, we will also discuss novel therapeutic targets for obesity-associated HCC and ongoing clinical trials.

The phenolic compounds tyrosol and hydroxytyrosol counteract liver fibrogenesis via the transcriptional modulation of NADPH oxidases and oxidative stress-related miRNAs

Liver fibrosis is the result of a chronic pathological condition caused by the activation of hepatic stellate cells (HSCs), which induces the excessive deposition of extracellular matrix. Fibrogenesis is sustained by an exaggerated production of reactive oxidative species (ROS) by NADPH oxidases (NOXs), which are overactivated in hepatic inflammation. In this study, we investigated the antifibrotic properties of two phenolic compounds of natural origin, tyrosol (Tyr) and hydroxytyrosol (HTyr), known for their antioxidant and anti-inflammatory effects. We assessed Tyr and HTyr antifibrotic and antioxidant activity both in vitro, by a co-culture of LX2, HepG2 and THP1-derived Mϕ macrophages, set up to simulate the hepatic microenvironment, and in vivo, in a mouse model of liver fibrosis obtained by carbon tetrachloride treatment. We evaluated the mRNA and protein expression of profibrotic and oxidative markers (α-SMA, COL1A1, NOX1/4) by qPCR and/or immunocytochemistry or immunohistochemistry. The expression of selected miRNAs in mouse livers were measured by qPCR. Tyr and HTyr reduces fibrogenesis in vitro and in vivo, by downregulating all fibrotic markers. Notably, they also modulated oxidative stress by restoring the physiological levels of NOX1 and NOX4. In vivo, this effect was accompanied by a transcriptional regulation of inflammatory genes and of 2 miRNAs involved in the control of oxidative stress damage (miR-181-5p and miR-29b-3p). In conclusion, Tyr and HTyr exert antifibrotic and anti-inflammatory effects in preclinical in vitro and in vivo models of liver fibrosis, by modulating hepatic oxidative stress, representing promising candidates for further development.

Exosomal microRNAs and Progression of Nonalcoholic Steatohepatitis (NASH)

Nonalcoholic fatty liver disease (NAFLD)/metabolic associated fatty liver disease (MAFLD) is becoming a public health problem worldwide. Steatosis as the simple form and nonalcoholic steatohepatitis (NASH) as its progression form are commonly seen in liver biopsy specimens from patients with obesity, diabetes, hyperlipidemia, hypertension, and the use of certain drugs. Patients with NASH and advanced fibrosis were associated with increased risks of liver-related complications, including hepatocellular carcinoma (HCC). However, the mechanisms regarding the progression from simple steatosis to NASH fibrosis remain incompletely understood. Because NASH-caused liver injury is a complex process and multiple cell types are involved, intercellular communication is likely mediated by extracellular vesicles. Exosomes are a type of small extracellular vesicles and contain various cellular molecules, including proteins, messenger RNAs (mRNAs), and microRNAs (miRNAs). MiRNAs are short, non-coding RNA species that are important post-transcriptional regulators of gene expression and may play an important role in the pathogenesis of NALFD/NASH. In this article, we review the articles about NASH and exosomal miRNAs published in the most recent English literature through PubMed search and discuss the most recent criteria for histological diagnosis, pathogenesis from steatosis to NASH, roles of exosomal miRNAs in NASH pathogenesis and progression, as well as their potential in future clinical diagnosis and treatment for patients with NASH.

Noncoding RNAs as additional mediators of epigenetic regulation in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common cause of chronic liver disorder worldwide. It represents a spectrum that includes a continuum of different clinical entities ranging from simple steatosis to nonalcoholic steatohepatitis, which can evolve to cirrhosis and in some cases to hepatocellular carcinoma, ultimately leading to liver failure. The pathogenesis of NAFLD and the mechanisms underlying its progression to more pathological stages are not completely understood. Besides genetic factors, evidence indicates that epigenetic mechanisms occurring in response to environmental stimuli also contribute to the disease risk. Noncoding RNAs (ncRNAs), including microRNAs, long noncoding RNAs, and circular RNAs, are one of the epigenetic factors that play key regulatory roles in the development of NAFLD. As the field of ncRNAs is rapidly evolving, the present review aims to explore the current state of knowledge on the roles of these RNA species in the pathogenesis of NAFLD, highlight relevant mechanisms by which some ncRNAs can modulate regulatory networks implicated in NAFLD, and discuss key challenges and future directions facing current research in the hopes of developing ncRNAs as next-generation non-invasive diagnostics and therapies in NAFLD and subsequent progression to hepatocellular carcinoma.

Noncoding RNAs Associated with PPARs in Etiology of MAFLD as a Novel Approach for Therapeutics Targets

Background. Metabolic associated fatty liver disease (MAFLD) is a complex disease that results from the accumulation of fat in the liver. MAFLD is directly associated with obesity, insulin resistance, diabetes, and metabolic syndrome. PPARγ ligands, including pioglitazone, are also used in the management of this disease. Noncoding RNAs play a critical role in various diseases such as diabetes, obesity, and liver diseases including MAFLD. However, there is no adequate knowledge about the translation of using these ncRNAs to the clinics, particularly in MAFLD conditions. The aim of this study was to identify ncRNAs in the etiology of MAFLD as a novel approach to the therapeutic targets. Methods. We collected human and mouse MAFLD gene expression datasets available in GEO. We performed pathway enrichment analysis of total mRNAs based on KEGG repository data to screen the most potential pathways in the liver of MAFLD human subjects and mice model, and analyzed pathway interconnections via ClueGO. Finally, we screened disease causality of the MAFLD ncRNAs, which were associated with PPARs, and then discussed the role of revealed ncRNAs in PPAR signaling and MAFLD. Results. We found 127 ncRNAs in MAFLD which 25 out of them were strongly validated before for regulation of PPARs. With a polypharmacology approach, we screened 51 ncRNAs which were causal to a subset of diseases related to MAFLD. Conclusion. This study revealed a subset of ncRNAs that could help in more clear and guided designation of preclinical and clinical studies to verify the therapeutic application of the revealed ncRNAs by manipulating the PPARs molecular mechanism in MAFLD.

miR-375 Induced the Formation and Transgenerational Inheritance of Fatty Liver in Poultry by Targeting MAP3K1

The liver of poultry is the primary site of lipid synthesis. The excessive production of lipids accumulates in liver tissues causing lipid metabolism disorders, which result in fatty liver disease and have a transgenerational effect of acquired phenotypes. However, its specific mechanisms have not yet been fully understood. In this study, the differentially expressed miR-375 as well as its target gene MAP3K1 (mitogen-activated protein kinase kinase kinase 1) were screened out by interaction network analysis of microRNA sequencing results and transcriptome profiling in the fatty liver group of the F0-F3 generation (p < 0.05 or p < 0.01). Furthermore, the results showed that the number of lipid droplets and triglyceride content were significantly decreased after upregulation of miR-375 in primary hepatocyte culture in vitro (p < 0.05 or p < 0.01). The MAP3K1 knockdown group exhibited the opposite trends (p < 0.05 or p < 0.01). P53, Bcl-x, PMP22, and CDKN2C related to cell proliferation were significantly upregulated or downregulated after knocking down MAP3K1 (p < 0.05). This research uniquely revealed that silencing miR-375 inhibits lipid biosynthesis and promotes cell proliferation, which may be due to the partial regulation of the expression level of MAP3K1, thereby further participating in the transgenerational inheritance process of regulating liver lipid metabolism. These results reveal the pathogenesis of fatty liver in noncoding RNA and provide good candidate genes for breeding progress of disease resistance in chickens.

An Update in Epigenetics in Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD) is characterized by hepatic steatosis accompanied by one of three features: overweight or obesity, T2DM, or lean or normal weight with evidence of metabolic dysregulation. It is distinguished by excessive fat accumulation in hepatocytes, and a decrease in the liver's ability to oxidize fats, the accumulation of ectopic fat, and the activation of proinflammatory pathways. Chronic damage will keep this pathophysiologic cycle active causing progression from hepatic steatosis to cirrhosis and eventually, hepatocarcinoma. Epigenetics affecting gene expression without altering DNA sequence allows us to study MAFLD pathophysiology from a different perspective, in which DNA methylation processes, histone modifications, and miRNAs expression have been closely associated with MAFLD progression. However, these considerations also faced us with the circumstance that modifying those epigenetics patterns might lead to MAFLD regression. Currently, epigenetics is an area of great interest because it could provide new insights in therapeutic targets and non-invasive biomarkers. This review comprises an update on the role of epigenetic patterns, as well as innovative therapeutic targets and biomarkers in MAFLD.

Steatosis, inflammasome upregulation, and fibrosis are attenuated in miR-155 deficient mice in a high fat-cholesterol-sugar diet-induced model of NASH

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease globally. miRNAs (miRs) regulate various cellular events that lead to NAFLD. In this study we tested the hypothesis that miR-155 is an important regulator of steatohepatitis and fibrosis pathways. Wild type (WT) or miR-155 deficient (KO) mice received a high fat-high cholesterol-high sugar-diet (HF-HC-HS) for 34 weeks and liver tissues were analyzed. In patients with nonalcoholic steatohepatitis and in the mouse model of HF-HC-HS diet we found increased miR-155 levels in the liver compared to normal livers. Upon HF-HC-HS diet feeding, miR-155 KO mice displayed less liver injury, decreased steatosis, and attenuation in fibrosis compared to WT mice. ALT, triglyceride levels, and genes involved in fatty acid metabolic pathway were increased in WT mice whereas miR-155 KO mice showed attenuation in these parameters. HF-HC-HS diet-induced significant increase in the expression of NLRP3 inflammasome components in the livers of WT mice compared to chow fed diet. Compared to WT mice, miR-155 KO showed attenuated induction in the NLRP3, ASC, and caspase1 inflammasome expression on HF-HC-HS diet. Fibrosis markers such as collagen content and deposition, αSMA, Zeb2, and vimentin were all increased in WT mice and miR-155 KO mice showed attenuated fibrosis marker expression. Overall, our findings highlight a role for miR-155 in HF-HC-HS diet-induced steatosis and liver fibrosis.

Ability of a Combined FIB4/miRNA181a Score to Predict Significant Liver Fibrosis in NAFLD Patients

Liver biopsy is the gold standard for assessing fibrosis, but there is a need to seek non-invasive biomarkers for this purpose. The aim of this study was to evaluate the correlation between the serum levels of the microRNAs miR-21, miR-29a, miR-122, miR-155 and miR-181a and the phenotypic expression of NAFLD. A cross-sectional study was carried out on 108 NAFLD patients diagnosed by liver biopsy. FIB-4 and NAFLD fibrosis scores were calculated. The comparison between the distributions of microRNA values according to the presence or absence of histological fibrosis (F2–F4) was performed. A multivariate logistic regression analysis was performed to build a score for predicting fibrosis using FIB-4 and Ln (miR-181a) as independent variables. Only miR-181a showed a statistical difference between patients with significant liver fibrosis (>F2) and those without (F0–F1) (p = 0.017). FIB-4 revealed an AUC on the ROC curve of 0.667 to predict clinically significant fibrosis (F2–F4). When assessed using the score in association with Ln (miR-181a), there was an improvement in the ROC curve, with an AUC of 0.71. miR-181a can be used as a non-invasive method of predicting fibrosis in NAFLD, and an association with FIB-4 has the potential to increase the accuracy of each method alone.

MicroRNAs as Diagnostic Tools in Hepatocellular Carcinoma

Liver cancer is the fourth leading cause of cancer-related deaths worldwide, with hepatocellular carcinoma (HCC) accounting for approximately 80% of all liver cancers. The serum concentration of alpha-fetoprotein (AFP) is the only validated biomarker for HCC diagnosis. MicroRNAs (miRNAs) are small non-coding RNAs of 21–30 nucleotides playing a critical role in human carcinogenesis, with types of miRNAs with oncogenic (oncomiRs) or tumor suppressor features. The altered expression of miRNAs in HCC is associated with many pathological processes, such as cancer initiation, tumor growth, apoptosis escape, promotion of migration and invasion. Moreover, circulating miRNAs have been increasingly investigated as non-invasive biomarkers for HCC diagnosis. MiRNAs’ expression patterns are altered in HCC and several single miRNAs or miRNAs panels have been found significantly up or downregulated in HCC with respect to healthy controls or non-oncological patients (cirrhotic or with viral hepatitis). However, any of the investigated miRNAs or miRNAs panels has entered clinical practice so far. This has mostly to do with lack of protocols standardization, small sample size and discrepancies in the measurement techniques. This review summarizes the major findings regarding the diagnostic role of miRNAs in HCC and their possible use together with standard biomarkers in order to obtain an early diagnosis and easier differential diagnosis from non-cancerous liver disease.

Biosensors, microfluidics systems and lateral flow assays for circulating microRNA detection: A review

MicroRNAs (miRNAs) are short RNA sequences found in eukaryotic cells and they are involved in several diseases pathogenesis including different types of cancers, metabolic and cardiovascular disorders. Thus, miRNAs circulating in serum, plasma, and other body fluids are employed as biomarkers for diagnostic and prognostic purposes and in assessment of drug response. Thus, various methods have been developed for detection of miRNAs including northern blotting, reverse transcriptase polymerase chain reaction (RT-PCR), next-generation sequencing, microarray, and isothermal amplification that are recognized as traditional methods. Considering the importance of early diagnosis and treatment of miRNAs-related diseases, development of simple, one-step, sensitive methods is of great interest. Nowadays developing technologies including lateral flow assay, biosensors (optical and electrochemical) and microfluidic systems which are simple fast responding, user-friendly, and are enabled with visible detection have gained considerable attention. This review briefly discusses miRNAs detection' methods, with a particular focus on lateral flow assay, biosensors, and microfluidic systems as novel and practical procedures.

Exogenous Drug Disposition as a Diagnostic Biomarker Strategy for Non-Alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) is the progressive form of non-alcoholic fatty liver disease (NAFLD) and is diagnosed by a liver biopsy. Due to the invasiveness of a biopsy, the majority of patients with NASH are undiagnosed. Additionally, the prevalence of NAFLD and NASH creates the need for a simple screening method to differentiate patients with NAFLD versus NASH. Non-invasive strategies for diagnosing NAFLD versus NASH have been developed, typically relying on imaging techniques and endogenous biomarker panels. However, each technique has limitations, and none can accurately predict the associated functional impairment of drug metabolism and disposition. The function of several drug metabolizing enzymes and drug transporters have been described in NASH that impacts drug pharmacokinetics. The aim of this review is to give an overview of the existing non-invasive strategies to diagnose NASH, and to propose a novel strategy based on altered pharmacokinetics using an exogenous biomarker whose disposition and elimination pathways are directly impacted by disease progression. Altered disposition of safe and relatively inert exogenous compounds may provide the sensitivity and specificity needed to differentiate patients with NAFLD and NASH to facilitate a direct indication of hepatic impairment on drug metabolism and prevent subsequent adverse drug reactions. Significance Statement This review provides an overview of the main non-invasive techniques (imaging and panels of biomarkers) used to diagnose non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) along with a biopsy. Pharmacokinetic changes have been identified in NASH and this review proposes a new approach to predict NASH and the related risk of adverse drug reactions, based on the assessment of drug elimination disruption using exogenous biomarkers.

Pirfenidone modifies hepatic miRNAs expression in a model of MAFLD/NASH

miRNAs are involved in the development of metabolic associated fatty liver disease (MAFLD) and nonalcoholic steatohepatitis (NASH). We aimed to evaluate modifications by prolonged-release pirfenidone (PR-PFD) on key hepatic miRNAs expression in a MAFLD/NASH model. First, male C57BL/6J mice were randomly assigned into groups and fed with conventional diet (CVD) or high fat and carbohydrate diet (HFD) for 16 weeks. At the end of the eighth week, HFD mice were divided in two and only one half was treated with 300 mg/kg/day of PR-PFD mixed with food. Hepatic expression of miRNAs and target genes that participate in inflammation and lipid metabolism was determined by qRT-PCR and transcriptome by microarrays. Increased hepatic expression of miR-21a-5p, miR-34a-5p, miR-122-5p and miR-103-3p in MAFLD/NASH animals was reduced with PR-PFD. Transcriptome analysis showed that 52 genes involved in lipid and collagen biosynthesis and inflammatory response were downregulated in PR-PFD group. The expression of Il1b, Tnfa, Il6, Tgfb1, Col1a1, and Srebf1 were decreased in PR-PFD treated animals. MAFLD/NASH animals compared to CVD group showed modifications in gene metabolic pathways implicated in lipid metabolic process, inflammatory response and insulin resistance; PR-PFD reversed these modifications.

miR-375 induces adipogenesis through targeting Erk1 in pancreatic duct cells under the influence of sodium palmitate

The goal of this study was to research long-term saturated fatty acid overexposure that can induce differentiation of pancreatic duct cells into adipocytes and also into β-cells. The important findings can be summarized as follows: (i) adipogenesis and early stage β-cell differentiation were stimulated in duct cells under lipotoxicity and glucolipotoxicity conditions, (ii) miR-375 expression was upregulated while its target Erk1 was downregulated and miR-375 inhibitor upregulated Erk1 while expression of adipogenesis markers was downregulated in duct cells under both conditions, (iii) apoptosis was induced in β and duct cells under both conditions, (iv) lipotoxicity induced proliferation of co-cultured β-cells. These findings suggest that long-term saturated fatty acid overexposure may cause intrapancreatic fat accumulation by inducing differentiation of duct cells into adipocytes and it may contributes to β-cell compensation by stimulating the early stage of β-cell differentiation in duct cells. In addition, miR-375 may have the potential to be a new target in the treatment of Type 2 diabetes, and NAFPD due to its role in the adipogenesis of duct cells.

NAFLD: a multi-faceted morbid spectrum with uncertain diagnosis and complicated management. Where do we stand? Review of the literature

NASH can be considered the "contemporary era pandemic", because of its global widespread in parallel with obesity, diabetes and metabolic dysfunction. It is a disease that often poses many difficulties, since making a early diagnosis is often impossible since specific diagnostic tests and criteria are missing: so, it needs a high degree of suspicion. Most of the times the evolution to its more severe and terminal step, NASH cirrhosis, is unavoidable and so are the social pressure on health sistem and economic consequences it brings back. In this work we aim to review the literature about both NAFLD and NASH, thus structuring a wide, comprehensive, 360 degree work with a focus on all major aspects of NAFLD, spanning from diagnosis, physiopathology and its repercussions on liver transplantation. Moreover we also focused on patients related issues both in pre- and post-transplant management (when these patients are listed for liver transplant). NAFLD and NASH are a contemporary plague, and an exaustive knowledge of the problem throughout all its aspects is necessary in order to lower economic weight that metabolic issues bring back and to have a open view to possible solutions to all management issues that NASH patients have and that are oten prohibitive to a definitive cure (for example cardiovascular risk in patients otherwise eligible to liver transplantation). We aim to offer a complete view on the actual knowledge about NAFLD and NASH, by an extensive review of the literature.

Xylo-Oligosaccharides in Prevention of Hepatic Steatosis and Adipose Tissue Inflammation: Associating Taxonomic and Metabolomic Patterns in Fecal Microbiomes with Biclustering

We have shown that prebiotic xylo-oligosaccharides (XOS) increased beneficial gut microbiota (GM) and prevented high fat diet-induced hepatic steatosis, but the mechanisms associated with these effects are not clear. We studied whether XOS affects adipose tissue inflammation and insulin signaling, and whether the GM and fecal metabolome explain associated patterns. XOS was supplemented or not with high (HFD) or low (LFD) fat diet for 12 weeks in male Wistar rats (n = 10/group). Previously analyzed GM and fecal metabolites were biclustered to reduce data dimensionality and identify interpretable groups of co-occurring genera and metabolites. Based on our findings, biclustering provides a useful algorithmic method for capturing such joint signatures. On the HFD, XOS-supplemented rats showed lower number of adipose tissue crown-like structures, increased phosphorylation of AKT in liver and adipose tissue as well as lower expression of hepatic miRNAs. XOS-supplemented rats had more fecal glycine and less hypoxanthine, isovalerate, branched chain amino acids and aromatic amino acids. Several bacterial genera were associated with the metabolic signatures. In conclusion, the beneficial effects of XOS on hepatic steatosis involved decreased adipose tissue inflammation and likely improved insulin signaling, which were further associated with fecal metabolites and GM.

Replication study reveals miR-483-5p as an important target in prevention of cardiometabolic disease

Background

Alterations in levels of circulating micro-RNAs might reflect within organ signaling or subclinical tissue injury that is linked to risk of diabetes and cardiovascular risk. We previously found that serum levels of miR-483-5p is correlated with cardiometabolic risk factors and incidence of cardiometabolic disease in a case–control sample from the populations-based Malmö Diet and Cancer Study Cardiovascular Cohort (MDC-CC). We here aimed at replicating these findings and to test for association with carotid atherosclerosis.

Methods

We measured miR-483-5p in fasting serum of 1223 healthy subjects from the baseline examination of the population-based, prospective cohort study Malmö Offspring Study (MOS) and correlated miR-483-5p to cardiometabolic risk factors and to incidence of diabetes mellitus and coronary artery disease (CAD) during 3.7 (± 1.3) years of follow-up using logistic regression. In both MOS and MDC-CC we related mir-483-5p to carotid atherosclerosis measured with ultrasound.

Results

In cross-sectional analysis miR-483-5p was correlated with BMI, waist circumference, HDL, and sex. After adjustment for age and sex, the association remained significant for all risk factors except for HDL. Logistic regression analysis showed significant associations between miR-483-5p and new-onset diabetes (OR = 1.94, 95% CI 1.06–3.56, p = 0.032) and cardiovascular disease (OR = 1.99, 95% CI 1.06–3.75, p = 0.033) during 3.7 (± 1.3) years of follow-up. Furthermore, miR-483-5p was significantly related with maximum intima-media thickness of the carotid bulb in MDC-CC (p = 0.001), but not in MOS, whereas it was associated with increasing number of plaques in MOS (p = 0.007).

Conclusion

miR-483-5p is related to an unfavorable cardiometabolic risk factor profile and predicts diabetes and CAD, possibly through an effect on atherosclerosis. Our results encourage further studies of possible underlying mechanisms and means of modifying miR-483-5p as a possible interventional target in prevention of cardiometabolic disease.

A perspective on RNA interference-based therapeutics for metabolic liver diseases

Introduction: Therapeutic oligonucleotides have emerged as a promising new class of drug that could silence undruggable targets; they can potentially treat metabolic liver diseases such as nonalcoholic fatty liver disease (NAFLD), hereditary hemochromatosis and alpha 1 antitrypsin deficiency.Areas covered: This article illuminates the mechanism of action of, and drug delivery approaches for therapeutic oligonucleotides such as antisense oligonucleotides (ASOs), short interfering RNAs (siRNAs), and MicroRNAs (miRs). We reveal why the liver is the ideal organ for therapeutic oligonucleotides, discuss its unique architecture, and shed light on those susceptible molecular targets that can be modulated. We also examine preclinical and clinical data on the utility of oligonucleotides in silencing the expression of genes responsible for metabolic liver diseases.Expert opinion: The liver has numerous susceptible molecular therapeutic targets; hence, metabolic liver diseases can be treated effectively by modulating these targets via novel therapeutic oligonucleotides. Undoubtedly, these exciting developments integrate well with precision medicine progress. Specific therapeutic oligonucleotides can be designed based on the exact underlying molecular mechanism of the disease. So, there is a justification for furthering the development of therapeutic oligonucleotides for metabolic liver diseases. Safety concerns such as immunogenicity and off-target effects will however require careful monitoring.

Regulation of uridine diphosphate-glucuronosyltransferase 1A expression by miRNA-214-5p and miRNA-486-3p

Aim: This study aimed to identify novel miRNAs (miRs) as regulators of UGT1A gene expression and to evaluate them as potential risk factors for the development of liver fibrosis/cirrhosis. Materials & methods: miRNA target sites in UDP-glucuronosyltransferase 1A (UGT1A) 3'-UTR were predicted and confirmed by luciferase assays, quantitative real-time PCR and western blot using HEK293, HepG2 and Huh7 cells. UGT1A and miRNA expression were analyzed in cirrhotic patients and a mouse model of alcoholic liver fibrosis. Results: miR-214-5p and miR-486-3p overexpression reduced UGT1A mRNA, protein levels and enzyme activity in HepG2 and Huh7 cells. miR-486-3p was upregulated in cirrhotic patients and fibrotic mice livers, whereas UGT1A mRNA levels were reduced. Conclusion: In conclusion, we identified two novel miRNAs capable to repress UGT1A expression in vitro and in vivo. Furthermore, miR-486-3p may represent a potential risk factor for the development or progression of liver fibrosis/cirrhosis by means of a reduced UGT1A-mediated detoxification activity.

Nonalcoholic steatohepatitis: the role of peroxisome proliferator-activated receptors

The increasing epidemic of obesity worldwide is linked to serious health effects, including increased prevalence of type 2 diabetes mellitus, cardiovascular disease and nonalcoholic fatty liver disease (NAFLD). NAFLD is the liver manifestation of the metabolic syndrome and includes the spectrum of liver steatosis (known as nonalcoholic fatty liver) and steatohepatitis (known as nonalcoholic steatohepatitis), which can evolve into progressive liver fibrosis and eventually cause cirrhosis. Although NAFLD is becoming the number one cause of chronic liver diseases, it is part of a systemic disease that affects many other parts of the body, including adipose tissue, pancreatic β-cells and the cardiovascular system. The pathomechanism of NAFLD is multifactorial across a spectrum of metabolic derangements and changes in the host microbiome that trigger low-grade inflammation in the liver and other organs. Peroxisome proliferator-activated receptors (PPARs) are a group of nuclear regulatory factors that provide fine tuning for key elements of glucose and fat metabolism and regulate inflammatory cell activation and fibrotic processes. This Review summarizes and discusses the current literature on NAFLD as the liver manifestation of the systemic metabolic syndrome and focuses on the role of PPARs in the pathomechanisms as well as in the potential targeting of disease.

The diagnostic conundrum in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has become the most common liver alteration worldwide. It encompasses a spectrum of disorders that range from simple steatosis to a progressive form, defined non-alcoholic steatohepatitis (NASH), that can lead to advanced fibrosis and eventually cirrhosis and hepatocellular carcinoma. On liver histology, NASH is characterized by the concomitant presence of significant fat accumulation and inflammatory reaction with hepatocellular injury. Until now, liver biopsy is still required to differentiate simple steatosis from NASH and evaluate the degree of liver fibrosis. Unfortunately, this technique has well-known limitations, including invasiveness and expensiveness. Moreover, it may be biased by sampling error and intra- or inter-observed variability. Furthermore, due to the increasing prevalence of NAFLD worldwide, to program a systematic screening with liver biopsy is not imaginable. In recent years, different techniques were developed and validated with the aim of non-invasively identifying NASH and assess liver fibrosis degrees. The non-invasive tests range from simple blood-tests analyses to composite scores and complex imaging techniques. Nevertheless, even if they could represent cost-effective strategies for diagnosing NASH, advanced fibrosis and cirrhosis, their accuracy and consequent usefulness are to be discussed. With this aim, in this review the authors summarize the current state of non-invasive assessment of NAFLD. In particular, in addition to the well-established tests, the authors describe the future perspectives in this field, reporting the latest tests based on OMICS, gut-miocrobioma and micro-RNAs. Finally, the authors provide an accurate assessment of how these non-invasive tools perform in clinical practice depending on the clinical context, with the aim of giving the clinicians a useful tool to try to resolve the diagnostic conundrum of NAFLD.

Predicting Nonalcoholic Fatty Liver Disease through a Panel of Plasma Biomarkers and MicroRNAs in Female West Virginia Population

(1) Background: Nonalcoholic fatty liver disease (NAFLD) is primarily characterized by the presence of fatty liver, hepatic inflammation and fibrogenesis eventually leading to nonalcoholic steatohepatitis (NASH) or cirrhosis. Obesity and diabetes are common risk factors associated with the development and progression of NAFLD, with one of the highest prevalence of these diseased conditions in the West Virginia population. Currently, the diagnosis of NAFLD is limited to radiologic studies and biopsies, which are not cost-effective and highly invasive. Hence, this study aimed to develop a panel and assess the progressive levels of circulatory biomarkers and miRNA expression in patients at risk for progression to NASH to allow early intervention strategies. (2) Methods: In total, 62 female patients were enrolled and blood samples were collected after 8–10 h of fasting. Computed tomography was performed on abdomen/pelvis following IV contrast administration. The patients were divided into the following groups: Healthy subjects with normal BMI and normal fasting blood glucose (Control, n = 20), Obese with high BMI and normal fasting blood glucose (Obese, n = 20) and Obese with high fasting blood glucose (Obese + DM, n = 22). Based on findings from CT, another subset was created from Obese + DM group with patients who showed signs of fatty liver infiltration (Obese + DM(FI), n = 10). ELISA was performed for measurement of plasma biomarkers and RT-PCR was performed for circulating miRNA expression. (3) Results: Our results show significantly increased levels of plasma IL-6, Leptin and FABP-1, while significantly decreased level of adiponectin in Obese, Obese + DM and Obese + DM(FI) group, as compared to healthy controls. The level of CK-18 was significantly increased in Obese + DM(FI) group as compared to control. Subsequently, the expression of miR-122, miR-34a, miR-375, miR-16 and miR-21 was significantly increased in Obese + DM and Obese + DM(FI) group as compared to healthy control. Our results also show distinct correlation of IL-6, FABP-1 and adiponectin levels with the expression of miRNAs in relation to the extent of NAFLD progression. (4) Conclusion: Our results support the clinical application of these biomarkers and miRNAs in monitoring the progression of NAFLD, suggesting a more advanced diagnostic potential of this panel than conventional methods. This panel may provide an appropriate method for early prognosis and management of NAFLD and subsequent adverse hepatic pathophysiology, potentially reducing the disease burden on the West Virginia population.

Noncoding RNAs in Nonalcoholic Fatty Liver Disease: Potential Diagnosis and Prognosis Biomarkers

Nonalcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease worldwide in part due to the concomitant obesity pandemic and insulin resistance (IR). It is increasingly becoming evident that NAFLD is a disease affecting numerous extrahepatic vital organs and regulatory pathways. The molecular mechanisms underlying the nonalcoholic steatosis formation are poorly understood, and little information is available on the pathways that are responsible for the progressive hepatocellular damage that follows lipid accumulation. Recently, much research has focused on the identification of the epigenetic modifications that contribute to NAFLD pathogenesis. Noncoding RNAs (ncRNAs) are one of such epigenetic factors that could be implicated in the NAFLD development and progression. In this review, we summarize the current knowledge of the genetic and epigenetic factors potentially underlying the disease. Particular emphasis will be put on the contribution of microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs) to the pathophysiology of NAFLD as well as their potential use as therapeutic targets or as markers for the prediction and the progression of the disease.

A blood-based biomarker panel (NIS4) for non-invasive diagnosis of non-alcoholic steatohepatitis and liver fibrosis: a prospective derivation and global validation study

BACKGROUND

Non-invasive tests that can identify patients with non-alcoholic steatohepatitis (NASH) at higher risk of disease progression are lacking. We report the development and validation of a blood-based diagnostic test to non-invasively rule in and rule out at-risk NASH (defined as non-alcoholic fatty liver disease [NAFLD] activity score [NAS] ≥4 and fibrosis stage ≥2).

METHODS

In this prospective derivation and global validation study, blood samples, clinical data, and liver biopsy results from three independent cohorts with suspected NAFLD were used to develop and validate a non-invasive blood-based diagnostic test, called NIS4. Derivation was done in the discovery cohort, which comprised 239 prospectively recruited patients with biopsy-confirmed NASH (NAFLD NAS ≥3; fibrosis stage 0-3) from the international GOLDEN-505 phase 2b clinical trial. A complete matrix based on 23 variables selected for univariate association with the presence of at-risk NASH and avoiding high multi-collinearity was used to derive the model in a bootstrap-based process that minimised the Akaike information criterion. The overall diagnostic performance of NIS4 was externally validated in two independent cohorts: RESOLVE-IT diag and Angers. The RESOLVE-IT diag cohort comprised the first 475 patients screened for potential inclusion into the RESOLVE-IT phase 3 clinical trial. Angers was a retrospective cohort of 227 prospectively recruited patients with suspected NAFLD and clinical risk factors for NASH or fibrosis stage 2 or more according to abnormal elastography results or abnormal liver biochemistry. Both external validation cohorts were independently analysed and were combined into a pooled validation cohort (n=702) to assess clinical performance of NIS4 and other non-invasive tests.

FINDINGS

The derived NIS4 algorithm comprised four independent NASH-associated biomarkers (miR-34a-5p, alpha-2 macroglobulin, YKL-40, and glycated haemoglobin; area under the receiver operating characteristics curve [AUROC] 0·80, 95% CI 0·73-0·85), and did not require adjustment for age, sex, body-mass index (BMI), or aminotransferase concentrations. Clinical cutoffs were established within the discovery cohort to optimise both rule out and rule in clinical performance while minimising indeterminate results. NIS4 was validated in the RESOLVE-IT diag cohort (AUROC 0·83, 95% CI 0·79-0·86) and the Angers cohort (0·76, 0·69-0·82). In the pooled validation cohort, patients with a NIS4 value less than 0·36 were classified as not having at-risk NASH (ruled out) with 81·5% (95% CI 76·9-85·3) sensitivity, 63·0% (57·8-68·0) specificity, and a negative predictive value of 77·9% (72·5-82·4), whereas those with a NIS4 value of more than 0·63 were classified as having at-risk NASH (ruled in) with 87·1% (83·1-90·3) specificity, 50·7% (45·3-56·1) sensitivity, and a positive predictive value of 79·2% (73·1-84·2). The diagnostic performance of NIS4 within the external validation cohorts was not influenced by age, sex, BMI, or aminotransferase concentrations.

INTERPRETATION

NIS4 is a novel blood-based diagnostic that provides an effective way to non-invasively rule in or rule out at-risk NASH in patients with metabolic risk factors and suspected disease. Use of NIS4 in clinical trials or in the clinic has the potential to greatly reduce unnecessary liver biopsies in patients with lower risk of disease progression.

FUNDING

Genfit.

Processes exacerbating apoptosis in non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is a significant public health concern, owing to its high prevalence, progressive nature and lack of effective medical therapies. NAFLD is a complex and multifactorial disease involving the progressive and concerted action of factors that contribute to the development of liver inflammation and eventually fibrosis. Here, we summarize fundamental molecular mechanisms underlying the pathogenesis of non-alcoholic steatohepatitis (NASH), how they are interrelated and possible translation to clinical applications. We focus on processes triggering and exacerbating apoptotic signalling in the liver of NAFLD patients and their metabolic and pathological implications. Indeed, liver injury and inflammation are cardinal histopathological features of NASH, a duo in which derailment of apoptosis is of paramount importance. In turn, the liver houses a very high number of mitochondria, crucial metabolic unifiers of both extrinsic and intrinsic signals that converge in apoptosis activation. The role of lifestyle options is also dissected, highlighting the management of modifiable risk factors, such as obesity and harmful alcohol consumption, influencing apoptosis signalling in the liver and ultimately NAFLD progression. Integrating NAFLD-associated pathologic mechanisms in the cell death context could provide clues for a more profound understating of the disease and pave the way for novel rational therapies.

Suppression of miR-30a-3p Attenuates Hepatic Steatosis in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) have a high prevalence in humans in the past two decades. Here, we elucidated the functions of miR-30a-3p in the development of NAFLD and identified its potential targets. HepG-2 cells and NAFLD patients' blood samples were used in our study. Bioinformatics analysis as well as luciferase reporter assays were employed to distinguish peroxisome proliferator-activated receptor alpha (PPAR-α) as a target gene. Western blotting showed the expressions of lipid metabolic proteins and the target gene PPAR-α. Oil red O staining and triglyceride activity tested the fatty deposits after treatment with miR-30a-3p. miR-30a-3p was substantially up-regulated in NAFLD. Bioinformatics analyses showed that PPAR-α was a possible target of miR-30a-3p, linked with signaling pathways in NAFLD. PPAR-α as a novel target of miR-30a-3p, and suppression of its levels. The lipid metabolic-related proteins ACC, p-GSK-3β and FASN were up-regulated after transfecting with miR-30a-3p mimic, but the proteins CPT1, p-AMPK and UCP2 were down-regulated. miR-30a-3p inhibitor could diminish the protein manifestation of ACC, p-GSK-3β and FASN; and augment the protein manifestation of CPT1, p-AMPK and UCP2. On the contrary, overexpression of miR-30a-3p had adverse impacts on the performance of hepatocellular lipid accumulation and Triglyceride (TG) activity. Co-treatment with miR-30a-3p mimic and overexpression PPAR-α could revise the hepatic steatosis and the TG level induced by fat milk. Our findings suggest that miR-30a-3p/PPAR-α may be developed as a potential agent in NAFLD, which is enough to attenuate triglyceride accumulation and hepatic steatosis.

Noninvasive Diagnosis of NAFLD and NASH

The aim of this review is to outline emerging biomarkers that can serve as early diagnostic tools to identify patients with nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) and, among them, the subgroup of best candidates for clinical trials on emerging compounds. Regarding possible predictors of NAFLD, a number of studies evaluated a combination of serum biomarkers either available in routine practice (or investigational) or proprietary and expensive. So far, magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF) appears to be the most accurate for fatty liver diagnosis. In clinical practice, the main question is how to diagnose NASH early. There are new promising biomarkers that can help in diagnosing early stages of NASH, yet they include variables not routinely tested. In the setting of NASH, most studies confirm that, in spite of several well-known limitations, transient elastography or point shear wave elastography can help in enriching the pool of patients that should be screened for investigational treatments. Newer multiomics biomarkers including those focusing on microbiota can be useful but require methods to be standardized and implemented. To date, one biomarker alone is not able to non- or minimally invasively identify patients with NASH and mild to moderate fibrosis.

The lncRNA Gm15622 stimulates SREBP-1c expression and hepatic lipid accumulation by sponging the miR-742-3p in mice

Excessive lipid deposition is a hallmark of NAFLD. Although much has been learned about the enzymes and metabolites involved in NAFLD, few studies have focused on the role of long noncoding RNAs (lncRNAs) in hepatic lipid accumulation. Here, using in vitro and in vivo models of NAFLD, we found that the lncRNA Gm15622 is highly expressed in the liver of obese mice fed a HFD and in murine liver (AML-12) cells treated with free fatty acids. Investigating the molecular mechanism in the liver-enriched expression of Gm15622 and its effects on lipid accumulation in hepatocytes and on NAFLD pathogenesis, we found that Gm15622 acts as a sponge for the microRNA miR-742-3p. This sponging activity increased the expression of the transcriptional regulator SREBP-1c and promoted lipid accumulation in the liver of the HFD mice and AML-12 cells. Moreover, further results indicated that metformin suppresses Gm15622 and alleviates NAFLD-associated lipid deposition in mice. In conclusion, we have identified an lncRNA Gm15622/miR-742-3p/SREBP-1c regulatory circuit associated with NAFLD in mice, a finding that significantly advances our insight into how lipid metabolism and accumulation are altered in this metabolic disorder. Our results also suggest that Gm15622 may be a potential therapeutic target for managing NAFLD.

Chinese Herbal Medicine Formula Shenling Baizhu San Ameliorates High-Fat Diet-Induced NAFLD in Rats by Modulating Hepatic MicroRNA Expression Profiles

Objective

The purpose of present study was to investigate the potential mechanism underlying the protective effect of Shenling Baizhu San (SLBZS) on nonalcoholic fatty liver disease (NAFLD) by microRNA (miRNA) sequencing.

Methods

Thirty male Wistar rats were randomly divided into a normal control (NC) group, a high-fat diet (HFD) group, and an SLBZS group. After 12 weeks, the biochemical parameters and liver histologies of the rats were assessed. The Illumina HiSeq 2500 sequencing platform was used to analyse the hepatic miRNA expression profiles. Representative differentially expressed miRNAs were further validated by qRT-PCR. The functions of the differentially expressed miRNAs were analysed by bioinformatics.

Results

Our results identified 102 miRNAs that were differentially expressed in the HFD group compared with the NC group. Among those differentially expressed miRNAs, the expression levels of 28 miRNAs were reversed by SLBZS administration, suggesting the modulation effect of SLBZS on hepatic miRNA expression profiles. The qRT-PCR results confirmed that the expression levels of miR-155-5p, miR-146b-5p, miR-132-3p, and miR-34a-5p were consistent with those detected by sequencing. Bioinformatics analyses indicated that the target genes of the differentially expressed miRNAs reversed by SLBZS were mainly related to metabolic pathways.

Conclusion

This study provides novel insights into the mechanism of SLBZS in protecting against NAFLD; this mechanism may be partly related to the modulation of hepatic miRNA expression and their target pathways.

Green Tea Prevents NAFLD by Modulation of miR-34a and miR-194 Expression in a High-Fat Diet Mouse Model

Background/Aims

Nonalcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome. It is currently the most common chronic liver disease with complex pathogenesis and challenging treatment. Here, we investigated the hepatoprotective role of green tea (GT) and determined the involvement of miRNAs and its mechanism of action.

Methods

Male C57Bl/6 mice were fed with a high-fat diet for 4 weeks. After this period, the animals received gavage with GT (500 mg/kg body weight) over 12 weeks (5 days/week). HepG2 cell lines were transfected with miR-34a or miR-194 mimetics and inhibitors to validate the in vivo results or were treated with TNF-α to evaluate miRNA regulation.

Results

GT supplementation protects against NAFLD development by altering lipid metabolism, increasing gene expression involved in triglycerides and fatty acid catabolism, and decreasing uptake and lipid accumulation. This phenotype was accompanied by miR-34a downregulation and an increase in their mRNA targets Sirt1, Pparα, and Insig2. GT upregulated hepatic miR-194 by inhibiting TNF-α action leading to a decrease in miR-194 target genes Hmgcs/Apoa5.

Conclusion

Our study identified for the first time that the beneficial effects of GT in the liver can be due to the modulation of miRNAs, opening new perspectives for the treatment of NAFLD focusing on epigenetic regulation of miR-34a and miR-194 as green tea targets.

High-fructose drinks affect microRNAs expression differently in lean and obese mice

High fructose intake from soft drinks and sweets is assumed to have a negative impact on human health. Yet in spite of intensive research, the molecular mechanisms of these effects have not been fully elucidated yet, for example, the effect of high fructose intake could be different in normal and obese individuals. Four groups of mice were used in this study: control groups of lean mice and mice with obesity induced by a high-fat diet, then both of these groups with or without fructose administration in drinks. In plasma of each group, triacylglycerol, cholesterol, free fatty acids, alanine aminotransferase, insulin and adiponectin were measured. The expression levels of selected microRNAs (miRNAs) in plasma, the liver, white adipose tissue, brown adipose tissue and subcutaneous adipose tissue were quantified. In both lean and obese mice, high fructose intake increased cholesterol amount in the liver, up-regulated hepatic miR-27a, down-regulated miR-33a in white adipose tissue and increased plasmatic level of miR-21. The effect of high fructose intake on other miRNAs in the liver, plasma and adipose tissues differed in normal and obese mice. Fructose intake led to hepatic hypercholesterolemia and aberrant expression of several miRNAs participating in lipid metabolism, adipocytes differentiation and nonalcoholic fatty liver disease promotion. The effect of fructose on miRNAs expression differed in normal and obese mice. Nevertheless, plasmatic miR-21, which was induced by fructose in both lean and obese mice, may be considered as a potential biomarker of excessive fructose intake.

Role of Noncoding RNA in Development of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is increasing in prevalence globally, but little is known about its specific molecular mechanisms. During the past decade, noncoding RNAs (ncRNAs) have been linked to NAFLD initiation and progression. They are a class of RNAs that play an important role in regulating gene expression despite not encoding proteins. This review summarizes recent research on the relationship between ncRNAs and NAFLD. We discussed the potential applicability of ncRNAs as a biomarker for early NAFLD diagnosis and assessment of disease severity. With further study, ncRNAs should prove to be valuable new targets for NAFLD treatment and benefit the development of noninvasive diagnostic methods.

Mapping the molecular signatures of diet-induced NASH and its regulation by the hepatokine Tsukushi

OBJECTIVE

Nonalcoholic steatohepatitis (NASH) is closely associated with metabolic syndrome and increases the risk for end-stage liver disease, such as cirrhosis and hepatocellular carcinoma. Despite this, the molecular events that influence NASH pathogenesis remain poorly understood. The objectives of the current study are to delineate the transcriptomic and proteomic signatures of NASH liver, to identify potential pathogenic pathways and factors, and to critically assess their role in NASH pathogenesis.

METHODS

We performed RNA sequencing and quantitative proteomic analyses on the livers from healthy and diet-induced NASH mice. We examined the association between plasma levels of TSK, a newly discovered hepatokine, and NASH pathologies and reversal in response to dietary switch in mice. Using TSK knockout mouse model, we determined how TSK deficiency modulates key aspects of NASH pathogenesis.

RESULTS

RNA sequencing and quantitative proteomic analyses revealed that diet-induced NASH triggers concordant reprogramming of the liver transcriptome and proteome in mice. NASH pathogenesis is linked to elevated plasma levels of the hepatokine TSK, whereas dietary switch reverses NASH pathologies and reduces circulating TSK concentrations. Finally, TSK inactivation protects mice from diet-induced NASH and liver transcriptome remodeling.

CONCLUSIONS

Global transcriptomic and proteomic profiling of healthy and NASH livers revealed the molecular signatures of diet-induced NASH and dysregulation of the liver secretome. Our study illustrates a novel pathogenic mechanism through which elevated TSK in circulation promotes NASH pathologies, thereby revealing a potential target for therapeutic intervention.

Blackcurrant (Ribes nigrum) Prevents Obesity-Induced Nonalcoholic Steatohepatitis in Mice

OBJECTIVE

With increasing prevalence of nonalcoholic steatohepatitis (NASH), effective strategies to prevent NASH are needed. This study investigated whether the consumption of blackcurrant (Ribes nigrum) can prevent the development of obesity-induced NASH in vivo.

METHODS

Male C57BL/6J mice were fed a low-fat control diet, a low-fat diet with 6% whole blackcurrant powder, an obesogenic high-fat/high-sucrose control diet (HF), or a high-fat/high-sucrose diet containing 6% whole blackcurrant powder (HF-B) for 24 weeks.

RESULTS

HF significantly increased, whereas HF-B markedly decreased, liver weights and triglyceride. Furthermore, blackcurrant attenuated obesity-induced infiltration of macrophages in the liver, in particular, the M1 type, and also suppressed the hepatic expression of fibrogenic genes and fibrosis. Flow cytometric analysis showed that HF significantly increased the percentages of monocytes of total splenocytes, which was markedly attenuated by blackcurrant. HF-B decreased lipopolysaccharide-stimulated mRNA expression of interleukin 1β and tumor necrosis factor α in splenocytes, compared with those from HF controls. Moreover, the levels of circulating and hepatic miR-122-5p and miR-192-5p, known markers for nonalcoholic fatty liver disease, were significantly increased by HF but decreased by HF-B.

CONCLUSIONS

The study's findings indicate that blackcurrant consumption prevents obesity-induced steatosis, inflammation, and fibrosis in the liver.

Circular RNAs as Potential Biomarkers and Therapeutic Targets for Metabolic Diseases

Epidemiological studies provide evidence of a continuous rise in metabolic diseases throughout industrialized countries. Metabolic diseases are commonly associated with different abnormalities that hold a key role in the emergence and progression of frequent disorders including diabetes mellitus (DM), non-alcoholic fatty liver disease (NAFLD), obesity, metabolic syndrome and cardiovascular diseases. The burden of metabolic diseases is believed to arise through complex interaction between genetic and epigenetic factors, lifestyle changes and environmental exposure to triggering stimuli. The diagnosis and treatment of metabolic disorders continue to be an overwhelming challenge. Thus, the development of novel biomarkers may enhance the accuracy of the diagnosis at an early stage of the disease and allow effective intervention. Over the past decade, progress has been made in exploring the potential role of noncoding RNAs (ncRNAs) in the regulation of gene networks involved in metabolic diseases. A growing body of evidence now suggests that aberrant expression of circular RNAs (circRNAs) is relevant to the occurrence and development of metabolic diseases. Accordingly, circRNAs are proposed as predictive biomarkers and potential therapeutic targets for these diseases. As the field of circRNAs is rapidly evolving and knowledge is increasing, the present paper provides current understanding of the regulatory roles of these RNA species mainly in the pathogenesis of DM, NAFLD and obesity. Furthermore, some of the limitations to the promise of circRNAs and perspectives on their future research are discussed.

Upregulation of miR-181a impairs lipid metabolism by targeting PPARα expression in nonalcoholic fatty liver disease

Recent studies have reported elevated expression of miR-181a in patients with non-alcoholic fatty liver disease (NAFLD), suggesting that it may play an important role in liver lipid metabolism and insulin resistance. We aimed to investigate the effect of miR-181a in lipid metabolism and find new treatments for NAFLD. The expression level of miR-181a in NAFLD patient serum and a palmitic acid (PA)-induced NAFLD cell model was examined by Q-PCR. Oil red O staining and triglyceride assays were used to assess lipid accumulation in hepatocytes. Western blotting was used to detect the protein expression levels of peroxisome proliferator-activated receptor-α (PPARα) and the fatty acid β-oxidation-related genes. Direct interactions were validated by dual-luciferase reporter gene assays. MiR-181a expression was significantly upregulated in the serum of NAFLD patients and PA-induced hepatocytes. Inhibition of miR-181a expression resulted in the increased expression of PPARα and its downstream genes, and PA-induced lipid accumulation in hepatocytes was also inhibited. Upregulation of miR-181a resulted in the downregulation of its direct target PPARα and downstream gene expression of PPARα as well as aggravated lipid accumulation in hepatocytes. At the same time, the increased expression of PPARα can offset lipid accumulation in hepatocytes induced by miR-181a mimics. This study demonstrates that reducing the expression of miR-181a may improve lipid metabolism in NAFLD. The downregulation of miR-181a expression can be a therapeutic strategy for NAFLD by modulating its target PPARα.

Pathogenesis of NASH: The Impact of Multiple Pathways

Purpose of review

Advancing our understanding of the mechanisms that underlie NASH pathogenesis.

Recent findings

Recent findings on NASH pathogenesis have expanded our understanding of its complexity including: (1) there are multiple parallel hits that lead to NASH; (2) the microbiota play an important role in pathogenesis, with bacterial species recently shown to accurately differentiate between NAFL and NASH patients; (3) the main drivers of liver cell injury are lipotoxicity caused by free fatty acids (FFAs) and their derivatives combined with mitochondrial dysfunction; (4) decreased endoplasmic reticulum (ER) efficiency with increased demand for protein synthesis/folding/repair results in ER stress, protracted unfolded protein response, and apoptosis; (5) upregulated proteins involved in multiple pathways including JNK, CHOP, PERK, BH3-only proteins, and caspases result in mitochondrial dysfunction and apoptosis; and (6) subtypes of NASH in which these pathophysiological pathways vary may require patient subtype identification to choose effective therapy.

Summary

Recent pathogenesis studies may lead to important therapeutic advances, already seen in patients treated with ACC, ASK1 and SCD1 inhibitors and FXR agonists. Further advancing our understanding of mechanisms underlying NASH pathogenesis and the complex interplay between them will be crucial for developing effective therapies.

Role of microRNAs in alcohol-induced liver disorders and non-alcoholic fatty liver disease

MicroRNAs (miRNAs) are small non-coding RNAs that regulate multiple physiological and pathological functions through the modulation of gene expression at the post-transcriptional level. Accumulating evidence has established a role for miRNAs in the development and pathogenesis of liver disease. Specifically, a large number of studies have assessed the role of miRNAs in alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD), two diseases that share common underlying mechanisms and pathological characteristics. The purpose of the current review is to summarize and update the body of literature investigating the role of miRNAs in liver disease. In addition, the potential use of miRNAs as biomarkers and/or therapeutic targets is discussed. Among all miRNAs analyzed, miR-34a, miR-122 and miR-155 are most involved in the pathogenesis of NAFLD. Of note, these three miRNAs have also been implicated in ALD, reinforcing a common disease mechanism between these two entities and the pleiotropic effects of specific miRNAs. Currently, no single miRNA or panel of miRNAs has been identified for the detection of, or staging of ALD or NAFLD. While promising results have been shown in murine models, no therapeutic based-miRNA agents have been developed for use in humans with liver disease.

A General Overview on Non-coding RNA-Based Diagnostic and Therapeutic Approaches for Liver Diseases

Liver diseases contribute to the global mortality and morbidity and still represent a major health problem leading to the death of people worldwide. Although there are several treatment options available for Hepatitis C infections, for most liver disease the pharmacological options are still limited. Therefore, the development of new targets against liver diseases is of high interest. Non-coding RNA (ncRNA) such as microRNA (miRNA) or long ncRNA (lncRNA) have been shown to be deeply involved in the pathophysiology of almost all acute and chronic liver diseases. The emerging evidence showed the potential therapeutic use of miRNA associated with different steps of hepatic pathophysiology. In the present review, we summarize emerging insights of ncRNA in liver diseases. We also highlight example of ncRNAs participating in the pathogenesis of different forms of liver disease and how they can be used as potential therapeutic targets for novel treatment paradigms. Furthermore, we describe an overview of up-to-date clinical trials and discuss about its future in clinical applications. Finally, we highlight the role of circulating ncRNAs in diagnosis of liver diseases and discuss the challenges and drawbacks of the usage of ncRNAs in clinical setting.

Nonalcoholic Fatty Liver Disease and Diabetes Are Associated with Decreased CYP3A4 Protein Expression and Activity in Human Liver

Nonalcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease in the Western population. We investigated the association of nonalcoholic fatty liver disease (NAFLD) and diabetes mellitus on CYP3A4 activity in human liver tissue from brain dead donors ( n = 74). Histopathologically graded livers were grouped into normal ( n = 24), nonalcoholic fatty liver (NAFL, n = 26), and nonalcoholic steatohepatitis (NASH, n = 24) categories. The rate of conversion of midazolam to its 1-hydroxy metabolite was used to assess in vitro CYP3A4 activity in human liver microsomes (HLM). A proteomics approach was utilized to quantify the protein expression of CYP3A4 and related enzymes. Moreover, a physiologically based pharmacokinetic (PBPK) model was developed to allow prediction of midazolam concentration in NAFL and NASH livers. CYP3A4 activity in NAFL and NASH was 1.9- and 3.1-fold ( p < 0.05) lower than normal donors, respectively. Intrinsic clearance (CLint) was 2.7- ( p < 0.05) and 4.1-fold ( p < 0.01) lower in donors with NAFL and NASH, respectively. CYP3A4 protein expression was significantly lower in NAFL and NASH donors ( p < 0.05) and accounted for significant midazolam hydroxylation variability in a multiple linear regression analysis (β = 0.869, r² = 0.762, P < 0.01). Diabetes was also associated with decreased CYP3A4 activity and protein expression. Both midazolam CLint and CYP3A4 protein abundance decreased significantly with increase in hepatic fat accumulation. Age and gender did not exhibit any significant association with the observed alterations. Predicted midazolam exposure was 1.7- and 2.3-fold higher for NAFL and NASH, respectively, which may result in a longer period of sedation in these disease-states. Data suggests that NAFLD and diabetes are associated with the decreased hepatic CYP3A4 activity. Thus, further evaluation of clinical consequences of these findings on the efficacy and safety of CYP3A4 substrates is warranted.