Mirnome analysis reveals novel molecular determinants in the pathogenesis of diet-induced nonalcoholic fatty liver disease

Dietary Epigenetic Modulators: Unravelling the Still-Controversial Benefits of miRNAs in Nutrition and Disease

In the context of nutrient-driven epigenetic alterations, food-derived miRNAs can be absorbed into the circulatory system and organs of recipients, especially humans, and potentially contribute to modulating health and diseases. Evidence suggests that food uptake, by carrying exogenous miRNAs (xenomiRNAs), regulates the individual miRNA profile, modifying the redox homeostasis and inflammatory conditions underlying pathological processes, such as type 2 diabetes mellitus, insulin resistance, metabolic syndrome, and cancer. The capacity of diet to control miRNA levels and the comprehension of the unique characteristics of dietary miRNAs in terms of gene expression regulation show important perspectives as a strategy to control disease susceptibility via epigenetic modifications and refine the clinical outcomes. However, the absorption, stability, availability, and epigenetic roles of dietary miRNAs are intriguing and currently the subject of intense debate; additionally, there is restricted knowledge of their physiological and potential side effects. Within this framework, we provided up-to-date and comprehensive knowledge on dietary miRNAs' potential, discussing the latest advances and controversial issues related to the role of miRNAs in human health and disease as modulators of chronic syndromes.

A crosstalk between epigenetic modulations and non-alcoholic fatty liver disease progression

Non-alcoholic fatty liver disease (NAFLD) has recently emerged as a major public health concern worldwide due to its rapidly rising prevalence and its potential to progress into end-stage liver disease. While the precise pathophysiology underlying NAFLD remains incompletely understood, it is strongly associated with various environmental triggers and other metabolic disorders. Epigenetics examines changes in gene expression that are not caused by alterations in the DNA sequence itself. There is accumulating evidence that epigenetics plays a key role in linking environmental cues to the onset and progression of NAFLD. Our understanding of how epigenetic mechanisms contribute to NAFLD pathophysiology has expanded considerably in recent years as research on the epigenetics of NAFLD has developed. This review summarizes recent insights into major epigenetic processes that have been implicated in NAFLD pathogenesis including DNA methylation, histone acetylation, and microRNAs that have emerged as promising targets for further investigation. Elucidating epigenetic mechanisms in NAFLD may uncover novel diagnostic biomarkers and therapeutic targets for this disease. However, many questions have remained unanswered regarding how epigenetics promotes NAFLD onset and progression. Additional studies are needed to further characterize the epigenetic landscape of NAFLD and validate the potential of epigenetic markers as clinical tools. Nevertheless, an enhanced understanding of the epigenetic underpinnings of NAFLD promises to provide key insights into disease mechanisms and pave the way for novel prognostic and therapeutic approaches.

Ephrin-Eph receptor tyrosine kinases for potential therapeutics against hepatic pathologies

Hepatic fibrosis is the common pathological change that occurs due to increased synthesis and accumulation of extracellular matrix components. Chronic insult from hepatotoxicants leads to liver cirrhosis, which if not reversed timely using appropriate therapeutics, liver transplantation remains the only effective therapy. Often the disease further progresses into hepatic carcinoma. Although there is an increased advancement in understanding the pathological phenotypes of the disease, additional knowledge of the novel molecular signaling mechanisms involved in the disease progression would enable the development of efficacious therapeutics. Ephrin-Eph molecules belong to the largest family of receptor tyrosine kinases (RTKs) which are identified to play a crucial role in cellular migratory functions, during morphological and developmental stages. Additionally, they contribute to the growth of a multicellular organism as well as in pathological conditions like cancer, and diabetes. A wide spectrum of mechanistic studies has been performed on ephrin-Eph RTKs in various hepatic tissues under both normal and diseased conditions revealing their diverse roles in hepatic pathology. This systematic review summarizes the liver-specific ephrin-Eph RTK signaling mechanisms and recognizes them as druggable targets for mitigating hepatic pathology.

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.

Epigenetic Regulation in Lean Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), the most prominent cause of chronic liver disease worldwide, is a rapidly growing epidemic. It consists of a wide range of liver diseases, from steatosis to nonalcoholic steatohepatitis, and predisposes patients to liver fibrosis, cirrhosis, and even hepatocellular carcinoma. NAFLD is strongly correlated with obesity; however, it has been extensively reported among lean/nonobese individuals in recent years. Although lean patients demonstrate a lower prevalence of diabetes mellitus, central obesity, dyslipidemia, hypertension, and metabolic syndrome, a percentage of these patients may develop steatohepatitis, advanced liver fibrosis, and cardiovascular disease, and have increased all-cause mortality. The pathophysiological mechanisms of lean NAFLD remain vague. Studies have reported that lean NAFLD demonstrates a close association with environmental factors, genetic predisposition, and epigenetic modifications. In this review, we aim to discuss and summarize the epigenetic mechanisms involved in lean NAFLD and to introduce the interaction between epigenetic patterns and genetic or non genetic factors. Several epigenetic mechanisms have been implicated in the regulation of lean NAFLD. These include DNA methylation, histone modifications, and noncoding-RNA-mediated gene regulation. Epigenetics is an area of special interest in the setting of lean NAFLD as it could provide new insights into the therapeutic options and noninvasive biomarkers that target this under-recognized and challenging disorder.

Dietary Supplementation with 20-Hydroxyecdysone Ameliorates Hepatic Steatosis and Reduces White Adipose Tissue Mass in Ovariectomized Rats Fed a High-Fat, High-Fructose Diet

Metabolic dysfunction-associated fatty liver disease (MAFLD) is defined as hepatic steatosis in combination with overweight, diabetes, or other metabolic risk factors. MAFLD affects a significant number of the global population and imposes substantial clinical and economic burdens. With no approved pharmacotherapy, current treatment options are limited to diet and exercise. Therefore, the development of medicines for MAFLD treatment or prevention is necessary. 20-Hydroxyecdysone (20E) is a natural steroid found in edible plants and has been shown to improve metabolism and dyslipidemia. Therefore, it may be useful for MAFLD treatment. Here, we aimed to determine how dietary supplementation with 20E affects fat accumulation and lipogenesis in the liver and adipose tissue of ovariectomized rats fed a high-fat, high-fructose diet (OHFFD). We found that 20E reduced hepatic triglyceride content and visceral fat deposition. 20E increased the phosphorylation of AMP-activated protein kinase and acetyl CoA carboxylase while reducing the expression of fatty acid synthase in the liver and adipose tissue. Additionally, 20E increased hepatic expression of carnitine palmitoyltransferase-1 and reduced adipose expression of sterol regulatory element-binding protein-1. In conclusion, 20E demonstrated beneficial effects in rats with OHFFD-induced MAFLD. These findings suggest that 20E may represent a promising option for MAFLD prevention or treatment.

The association of plasma levels of miR-146a, miR-27a, miR-34a, and miR-149 with coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is considered to be one of the most pivotal causes of death in the world. Over the past two decades, significant changes occurred in the diagnosis, prognosis, and treatment of CAD, which has helped reduce mortality rates. microRNAs (miRs) are a class of more than 5000 non-encoding RNA molecules (21-25 nucleotides across the length) that regulate complex biological processes. Today, miRNAs are used to study cardiovascular diseases. In the present study, the expression of miR-146a،miR-27, miR-149, and miR-34a in plasma suffering from CAD and the control group were investigated.

METHODS AND RESULTS

The present research was performed on 30 men with CAD and 30 healthy men as controls. The expression levels of miR-146a, miR-27a, miR-149, and miR-34a in the plasma of patients with CAD and the control group were measured using real-time PCR. Also, the correlation between the expression of circulating miRs levels and biochemical LDL-C, HDL-C, BMI, and total cholesterol was evaluated. The expression of miR-27a in the plasma of the CAD group was higher than in the control group (p = 0.020). The expression of miR-146a was downregulated in CAD patients compared to normal subjects (p = 0. 026). However, the expression of miR-34a, miR-149 in the plasma of CAD patients was not significantly different with the control group. In addition to, a direct correlation was found between the expression of miR-146a and HDL-c, the expression of miR-27a and LDL-C and the expression of miR-34a and total cholesterol. Also, the negative correlation between expressions of miR-149 with BMI was reported.

CONCLUSION

The obtained results demonstrated that miRs were closely related to biochemical factors and it points out the fact that miRNAs can be applied as a potential strategy for diagnosis and treatment of CAD.

Hepatocellular Carcinoma: The Role of MicroRNAs

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. HCC is diagnosed in its advanced stage when limited treatment options are available. Substantial morphologic, genetic and epigenetic heterogeneity has been reported in HCC, which poses a challenge for the development of a targeted therapy. In this review, we discuss the role and involvement of several microRNAs (miRs) in the heterogeneity and metastasis of hepatocellular carcinoma with a special emphasis on their possible role as a diagnostic and prognostic tool in the risk prediction, early detection, and treatment of hepatocellular carcinoma.

Circulating Levels of microRNA-122 and Hepatic Fat Change in Response to Weight-Loss Interventions: CENTRAL Trial

PURPOSE

Little is known about the relations between changes in circulating microRNA-122 (miR-122) and liver fat in response to weight-loss interventions. We aimed to investigate the association between miR-122 and changes of hepatic fat content during 18-month diet and physical activity interventions.

METHODS

The CENTRAL trial is an 18-month randomized, controlled trial among adults with abdominal obesity or dyslipidemia. Subjects were randomly assigned to a low-fat diet or a Mediterranean/low-carbohydrate diet. After 6 months of dietary intervention, each diet group was further randomized into added physical activity groups or no added physical activity groups for the following 12 months of intervention. The current study included 220 participants at baseline and 134 participants with repeated measurements on serum miR-122 and hepatic fat content over 18 months.

RESULTS

Serum miR-122 significantly increased from baseline to 18 months, while no difference was observed across the 4 intervention groups. We found a significant association between miR-122 and hepatic fat content at baseline, as per unit increment in log-transformed miR-122 was associated with 3.79 higher hepatic fat content (P < 0.001). Furthermore, we found that higher elevations in miR-122 were associated with less reductions in hepatic fat percentage during 18-month interventions (β = 1.56, P = 0.002). We also found a significant interaction between changes in miR-122 and baseline fasting plasma glucose with hepatic fat content changes in 18 months (P interaction = 0.02).

CONCLUSIONS

Our data indicate that participants with higher elevation in serum miR-122 may benefit less in reduction of hepatic fat content in response to diet and physical activity interventions.

miR-27b inhibition contributes to cytotoxicity in patulin-exposed HEK293 cells

Patulin (PAT) is a mycotoxin produced by Penicillium and other fungi that contaminate fruit. PAT targets the kidney and is associated with nephrotoxicity. Micro-RNAs (miRNA) may offer new insights into PAT-induced nephrotoxicity. Cytochrome P₄₅₀ family 1, subfamily B, polypeptide 1 (CYP1B1), involved in metabolism of dietary toxins is negatively regulated by miR-27b and linked with the nuclear factor kappa B (NF-κB) pathway and peroxisome proliferator activated receptor gamma (PPARɣ) in renal fibrosis. This study investigated the effects of PAT on miR-27b, CYP1B1, PPARɣ and cytotoxicity in human kidney (HEK293) cells. HEK293 cells were exposed to PAT (2.5 μM, 24h). Protein expression of CYP1B1, PPARɣ, NF-κB (p65), pNF-κB (p65) (phospho-Ser563) and cleaved PARP-1 was quantified using western blotting. QPCR evaluated mRNA levels of CYP1B1, IL-6, miR-27b, OGG1, mtDNA, TFAM and UCP2. Mitochondrial membrane potential and phosphatidylserine (PS) externalization was evaluated by flow cytometry while levels of ATP and caspase -9, -8, -3/7 activity was measured using luminometry. PAT significantly decreased miR-27b levels (p = 0.0014) and increased CYP1B1 mRNA (p = 0.0015) and protein (p = 0.0013) levels. PPARɣ protein expression was significantly increased (p = 0.0002) and associated with decreased NF-κB activation (p = 0.0273) and IL-6 mRNA levels (p = 0.0265). Finally, PAT significantly compromised mitochondrial repair mechanisms and increased apoptotic biomarkers. PAT altered miR-27b levels and PPARɣ, with associated changes to NF-κB activation, downstream IL-6 and CYP1B1 expression. These results show that PAT impairs detoxification mechanisms leading to mitochondrial damage and apoptosis. In conclusion, PAT altered the epigenetic environment and impaired detoxification processes, supporting a mechanism for nephrotoxic outcomes.

The Predictive Efficacy of Serum Exosomal microRNA-122 and microRNA-148a for Hepatocellular Carcinoma Based on Smart Healthcare

Objective

Hepatocellular carcinoma (HCC) remains a devastating tumor globally. Serum exosomes are reliable biomarkers for tumors, including HCC. Hence, this study explored the efficacy and mechanism of serum exosomes in HCC.

Methods

microRNA (miR)-122 and miR-148a expressions in serum exosomes from HCC patients and healthy subjects and their predictive efficacy for HCC were detected. Correlation between serum exosomal miR-122/148a expressions with survival rate, clinical stage, lymph node metastasis, and tumor differentiation level and levels of HCC-related serum markers (CA199, FucAFP, ALD-A, and AFu) were detected. PAX2 staining intensity and expression in HCC were measured. PAX2 predictive efficacy for HCC and its correlation with clinical stage, lymph node metastasis, tumor differentiation level, and HCC-related serum marker levels were analyzed. The targeted binding relationship between miR-122 and miR-148a and PAX2 was predicted and verified.

Results

Serum exosomal miR-122 and miR-148a expressions were downregulated in HCC, showing potent predictive efficacy for HCC, which was negatively related to clinical stage and lymph node metastasis and positively related to tumor differentiation level, patient survival rate, and HCC-related serum marker levels. PAX2 showed increased staining intensity and expression in HCC, together with high predictive efficacy for HCC. PAX2 expression showed a positive correlation with clinical stage and lymph node metastasis and a negative correlation with tumor differentiation level and HCC-related serum marker levels. miR-122 and miR-148a conjointly targeted PAX2 in HCC.

Conclusion

We demonstrated that serum exosomal miR-122 and miR-148a played a predictive role and were linked to prognosis in HCC via interactions with PAX2.

Pharmacodynamic Evaluation of the Gexia Zhuyu Decoction in the Treatment of NAFLD and the Molecular Mechanism Underlying the TRPM4 Pathway Regulation

Nonalcoholic fatty liver disease (NAFLD) is a clinicopathological syndrome of abnormal lipid deposition in the liver mediated by nonalcohol intake. The Gexia Zhuyu decoction, a classic traditional Chinese medicine compound, is widely used in the clinical treatment of NAFLD. However, its specific efficacy and underlying mechanisms have not been elucidated yet. This study aimed to quantitatively evaluate the efficacy of the Gexia Zhuyu decoction using pharmacodynamics and to explore its molecular mechanisms in conjunction with proteomics. High-fat diets and methionine choline-deficient diets were used to induce various NAFLD progression stages in mouse models. The effects of oral Gexia Zhuyu decoction administration on NAFLD were evaluated by measuring the serum and liver indicators of the treated mice before and after drug intervention and by comparing the changes in liver tissue. Liver TRPM4 mRNA and protein levels were measured using reverse transcription-polymerase chain reaction and Western blotting, respectively. Experimental data showed that serum ALT, AST, and liver triglyceride (TG) levels in each disease stage group of drug intervention mice decreased, and high-density lipoprotein (HDL) and superoxide dismutase (SOD) levels increased. Liver TG levels decreased after drug intervention in the liver fibrosis mice, but serum TG levels increased. Furthermore, cellular fatty changes, inflammatory changes, and fibrous tissue proliferation were all relieved. The TRPM4 protein and mRNA levels in the liver tissue were decreased, and the microRNA (miRNA)-24 expression was increased. The Gexia Zhuyu decoction has a clear therapeutic effect at each stage of NAFLD. It likely acts by altering miRNA-24 expression and regulating the target TRPM4 protein pathway to achieve NAFLD treatment.

Palmitic Acid-Induced miR-429-3p Impairs Myoblast Differentiation by Downregulating CFL2

MicroRNAs are known to play a critical role in skeletal myogenesis and maintenance, and cofilin-2 (CFL2) is necessary for actin cytoskeleton dynamics and myogenic differentiation. Nonetheless, target molecules and the modes of action of miRNAs, especially those responsible for the inhibitory mechanism on the myogenesis by saturated fatty acids (SFA) or obesity, still remain unclear. Here, we reported the role played by miR-429-3p on CFL2 expression, actin filament dynamics, myoblast proliferation, and myogenic differentiation in C2C12 cells. Palmitic acid (PA), the most abundant SFA in diet, inhibited the myogenic differentiation of myoblasts, accompanied by CFL2 reduction and miR-429-3p induction. Interestingly, miR-429-3p suppressed the expression of CFL2 by targeting the 3'UTR of CFL2 mRNA directly. Transfection of miR-429-3p mimic in myoblasts increased F-actin formation and augmented nuclear YAP level, thereby promoting cell cycle progression and myoblast proliferation. Moreover, miR-429-3p mimic drastically suppressed the expressions of myogenic factors, such as MyoD, MyoG, and MyHC, and impaired myogenic differentiation of C2C12 cells. Therefore, this study unveiled the crucial role of miR-429-3p in myogenic differentiation through the suppression of CFL2 and provided implications of SFA-induced miRNA in the regulation of actin dynamics and skeletal myogenesis.

An Overview on the Role of miR-451 in Lung Cancer: Diagnosis, Therapy, and Prognosis

MicroRNAs (miRNAs) are highly conserved non-coding RNAs involved in many physiological processes such as cell proliferation, inhibition, development of apoptosis, differentiation, suppresses tumorigenicity, and regulating cell growth. The description of the alterations of miRNA expression patterns in cancers will be helpful to recognize biomarkers for early detection and possible therapeutic intervention in the treatment of cancers. Recent studies have shown that miR-451 is broadly dysregulated in lung cancer and is a crucial agent in lung tumor progression. This review summarizes recent advances of the potential role of miR-451 in lung cancer diagnosis, prognosis, and treatment and provides an insight into the potential use of miR-451 for the development of advanced therapeutic methods in lung cancer.

Identification and study of differentially expressed miRNAs in aged NAFLD rats based on high-throughput sequencing

INTRODUCTION AND OBJECTIVES

Hepatic microRNA (miR) expression profiles were explored in aged rats with NAFLD, in order to clarify the molecular mechanisms underlying the pathophysiological processes of aging-related NAFLD.

PATIENTS OR MATERIALS AND METHODS

24 aged rats (18-month-old) and 24 young rats (2-month-old) were randomly divided into two subgroups according to diet, control group and NAFLD group. After 8 weeks of administering 45% high-fat diet or normal diet, total hepatic RNA was extracted from liver tissues of the aged rats. Differentially expressed microRNAs (DE-miRs) in aged NAFLD group were detected and screened out using high-throughput sequencing technology. The data were subjected to Gene Ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses using a bioinformatics approach. The sequencing results were further verified by RT-qPCR.

RESULTS

Compared with the aged control liver tissues, 6 significantly upregulated miRs (miR-881-3p, miR-871-3p, miR-335, miR-223-3p, miR-155-5p, miR-146b-5p) and 4 significantly downregulated miRs (miR-182, miR-193-3p, miR-31a-5p and miR-96-5p) were identified in the aged NAFLD liver tissues. These DE-miRs were found to be involved in the regulation of cell signaling transduction and metabolism processes, probably affecting signaling pathways relevant to insulin secretion and some senile diseases. RT-qPCR results corroborated the sequencing results and demonstrated that 6 significantly upregulated miRs were not identified in the young group.

CONCLUSIONS

A total of 10 DE-miRs identified in the aged NAFLD rats were involved in some certain insulin secretion and age-related functional pathways, which may serve as novel candidate targets for the diagnosis and treatment of aging-associated NAFLD.

The Emerging Role of microRNA in Periodontitis: Pathophysiology, Clinical Potential and Future Molecular Perspectives

During the last few decades, it has been established that messenger ribonucleic acid (mRNA) transcription does not inevitably lead to protein translation, but there are numerous processes involved in post-transcriptional regulation, which is a continuously developing field of research. MicroRNAs (miRNAs) are a group of small non-coding RNAs, which negatively regulate protein expression and are implicated in several physiological and pathological mechanisms. Aberrant expression of miRNAs triggers dysregulation of multiple cellular processes involved in innate and adaptive immune responses. For many years, it was thought that miRNAs acted only within the cell in which they were synthesised, but, recently, they have been found outside cells bound to lipids and proteins, or enclosed in extracellular vesicles, namely exosomes. They can circulate throughout the body, transferring information between cells and altering gene expression in the recipient cells, as they can fuse with and be internalised by the recipient cells. Numerous studies on miRNAs have been conducted in order to identify possible biomarkers that can be used in the diagnosis of periodontal disease. However, as therapeutic agents, single miRNAs can target several genes and influence multiple regulatory networks. The aim of this review was to examine the molecular role of miRNAs and exosomes in the pathophysiology of periodontal disease and to evaluate possible clinical and future implications for a personalised therapeutical approach.

Targeting programmed cell death in metabolic dysfunction-associated fatty liver disease (MAFLD): a promising new therapy

Most currently recommended therapies for metabolic dysfunction-associated fatty liver disease (MAFLD) involve diet control and exercise therapy. We searched PubMed and compiled the most recent research into possible forms of programmed cell death in MAFLD, including apoptosis, necroptosis, autophagy, pyroptosis and ferroptosis. Here, we summarize the state of knowledge on the signaling mechanisms for each type and, based on their characteristics, discuss how they might be relevant in MAFLD-related pathological mechanisms. Although significant challenges exist in the translation of fundamental science into clinical therapy, this review should provide a theoretical basis for innovative MAFLD clinical treatment plans that target programmed cell death.

Identification of human glucocorticoid response markers using integrated multi-omic analysis from a randomized crossover trial

Background:

Glucocorticoids are among the most commonly prescribed drugs, but there is no biomarker that can quantify their action. The aim of the study was to identify and validate circulating biomarkers of glucocorticoid action.

Methods:

In a randomized, crossover, single-blind, discovery study, 10 subjects with primary adrenal insufficiency (and no other endocrinopathies) were admitted at the in-patient clinic and studied during physiological glucocorticoid exposure and withdrawal. A randomization plan before the first intervention was used. Besides mild physical and/or mental fatigue and salt craving, no serious adverse events were observed. The transcriptome in peripheral blood mononuclear cells and adipose tissue, plasma miRNAomic, and serum metabolomics were compared between the interventions using integrated multi-omic analysis.

Results:

We identified a transcriptomic profile derived from two tissues and a multi-omic cluster, both predictive of glucocorticoid exposure. A microRNA (miR-122-5p) that was correlated with genes and metabolites regulated by glucocorticoid exposure was identified (p=0.009) and replicated in independent studies with varying glucocorticoid exposure (0.01 ≤ p≤0.05).

Conclusions:

We have generated results that construct the basis for successful discovery of biomarker(s) to measure effects of glucocorticoids, allowing strategies to individualize and optimize glucocorticoid therapy, and shedding light on disease etiology related to unphysiological glucocorticoid exposure, such as in cardiovascular disease and obesity.

Funding:

The Swedish Research Council (Grant 2015-02561 and 2019-01112); The Swedish federal government under the LUA/ALF agreement (Grant ALFGBG-719531); The Swedish Endocrinology Association; The Gothenburg Medical Society; Wellcome Trust; The Medical Research Council, UK; The Chief Scientist Office, UK; The Eva Madura’s Foundation; The Research Foundation of Copenhagen University Hospital; and The Danish Rheumatism Association.

Clinical trial number:

NCT02152553.

Several diseases, including asthma, arthritis, some skin conditions, and cancer, are treated with medications called glucocorticoids, which are synthetic versions of human hormones. These drugs are also used to treat people with a condition call adrenal insufficiency who do not produce enough of an important hormone called cortisol. Use of glucocorticoids is very common, the proportion of people in a given country taking them can range from 0.5% to 21% of the population depending on the duration of the treatment. But, like any medication, glucocorticoids have both benefits and risks: people who take glucocorticoids for a long time have an increased risk of diabetes, obesity, cardiovascular disease, and death.

Because of the risks associated with taking glucocorticoids, it is very important for physicians to tailor the dose to each patient’s needs. Doing this can be tricky, because the levels of glucocorticoids in a patient’s blood are not a good indicator of the medication’s activity in the body. A test that can accurately measure the glucocorticoid activity could help physicians personalize treatment and reduce harmful side effects.

As a first step towards developing such a test, Chantzichristos et al. identified a potential way to measure glucocorticoid activity in patient’s blood. In the experiments, blood samples were collected from ten patients with adrenal insufficiency both when they were on no medication, and when they were taking a glucocorticoid to replace their missing hormones. Next, the blood samples were analyzed to determine which genes were turned on and off in each patient with and without the medication. They also compared small molecules in the blood called metabolites and tiny pieces of genetic material called microRNAs that turn genes on and off.

The experiments revealed networks of genes, metabolites, and microRNAs that are associated with glucocorticoid activity, and one microRNA called miR-122-5p stood out as a potential way to measure glucocorticoid activity. To verify this microRNA’s usefulness, Chantzichristos et al. looked at levels of miR-122-5p in people participating in three other studies and confirmed that it was a good indicator of the glucocorticoid activity.

More research is needed to confirm Chantzichristos et al.’s findings and to develop a test that can be used by physicians to measure glucocorticoid activity. The microRNA identified, miR-122-5p, has been previously linked to diabetes, so studying it further may also help scientists understand how taking glucocorticoids may increase the risk of developing diabetes and related diseases.

Impact of maternal obesity and prebiotic supplementation on select maternal milk microRNA levels and correlation with offspring outcomes

Breast milk composition varies with maternal factors including diet and confers health benefits to the neonate; however, the mechanisms mediating this protection remain incompletely understood. Our aim was to investigate the effects of supplementing a maternal high-fat/sucrose (HFS) diet with prebiotic oligofructose (OFS) on milk composition in rats and associations with offspring body composition and gut microbiota. Obese Sprague-Dawley dams consumed a control, HFS, HFS + OFS (10 % wt/wt) or HFS diet weight-matched to the HFS + OFS group (HFS-WM) during pregnancy and lactation. Pups were weaned onto a HFS diet on day 21. Milk was collected at weaning and analysed for protein, leptin and microRNA (miRNA) levels. Milk produced by HFS dams contained less protein than milk from lean controls which was normalised by OFS. Six miRNA (miR-222, miR-203a, miR-200a, miR-26a, miR-27a and miR-103) were differentially expressed in milk according to maternal diet. Milk leptin content was positively correlated with maternal body fat and faecal Enterobacteriaceae in male offspring at 24 weeks of age. Milk protein content was inversely associated with maternal body fat and body weight. miR-200a was positively associated with maternal body fat and Enterobacteriaceae in female offspring at 24 weeks of age. Correlations between milk protein and multiple milk miRNA and offspring body composition and gut microbiota differed by sex. Overall, our results suggest that obesogenic diets and prebiotic supplementation can alter the protein and miRNA levels in breast milk in rats and these milk components may explain, in part, the influence of these maternal diets on offspring body composition.

Hepatoprotective effect of silymarin on fructose induced nonalcoholic fatty liver disease in male albino wistar rats

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease in the Western world, and it's likely to parallel the increasing prevalence of type 2 diabetes, obesity, and other components of metabolic syndrome. However, optimal treatment for NAFLD has not been established yet. Therefore, this study investigated the hepatoprotective effect of silymarin on fructose-induced nonalcoholic fatty liver disease in rats.

METHODS

Thirty male Wistar rats were randomly divided into five groups; normal control group that consumed tap water, silymarin control group that consumed tap water and silymarin (400 mg/kg/day), fructose control group that consumed 20% fructose solution, treatment group that consumed 20% fructose solution and silymarin (200 mg/kg/day), and another treatment group that consumed 20% fructose solution and silymarin (400 mg/kg/day). Hepatic triglyceride, serum lipid profile, lipid peroxidation, antioxidant level, morphological features, and histopathological changes were investigated. The data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey multiple comparison test. Statistical significance was determined at p < 0.05.

RESULTS

This study showed that the fructose control group had a significantly high value in the stage of steatosis grade, hepatic triglyceride, serum triglyceride, total cholesterol, low-density lipoprotein cholesterol, alanine aminotransferase, aspartate aminotransferase, and hepatic malondialdehyde concentration as compared to the normal control. However, significantly low values of reduced glutathione and plasma total antioxidant capacity were found. The altered parameters due to fructose drastic effect were ameliorated by silymarin treatment.

CONCLUSIONS

The fructose control group developed dyslipidemia, oxidative stress, and mild steatosis that are the characteristics features of NAFLD. However, silymarin-treated groups showed amelioration in oxidative stress, dyslipidemia, and steatosis.

HFD-induced TRAF6 upregulation promotes liver cholesterol accumulation and fatty liver development via EZH2-mediated miR-429/PPARα axis

Despite the increasing prevalence of fatty liver diseases worldwide, the molecular mechanism underlying their pathogenesis remains poorly defined. This study examines the expression and significance of tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) in the high-fat diet (HFD)-induced mouse obesity model and the oleic acid/palmitic acid (OA/PA)-induced cell model. After developing these models, we measured the expressions of TRAF6, enhancer of the zeste homolog 2 (EZH2), and peroxisome proliferator activated receptor alpha (PPARα). The expression of TRAF6, EZH2, and PPARα was manipulated to investigate their roles in cholesterol accumulation through evaluating the plasma levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). Co-immunoprecipitation (coIP) assay was used to determine the interaction between TRAF6 and EZH2 and chromatin immunoprecipitation (ChIP) assay to detect the enrichment of EZH2 and H3K27me3 in microRNA-429 (miR-429) promoter. We found that HFD resulted in elevated TRAF6 and miR-429 in fatty liver and reduced EZH2 and PPARα. TRAF6 mediated the ubiquitination of EZH2 and increased miR-429 expression, and miR-429 targeted PPARα. TRAF6 increased cholesterol accumulation in liver cells in vitro via the EZH2/miR-429/PPARα axis. Collectively, HFD upregulates TRAF6 and ubiquitinates EZH2 to promote the miR-429-dependent inhibition of PPARα, leading to cholesterol accumulation in liver and the occurrence of fatty liver.

The role of microRNA-33 as a key regulator in hepatic lipogenesis signaling and a potential serological biomarker for NAFLD with excessive dietary fructose consumption in C57BL/6N mice

Limited studies reported mechanisms by which microRNAs (miRNA) are interlinked in the etiology of fructose-induced non-alcoholic fatty liver disease (NAFLD). Here, we aimed to investigate the significance of miRNAs in fructose-induced NAFLD pathogenesis through unbiased approaches. In experiment I, C57BL/6N mice were fed either water or 34% fructose for six weeks ad libitum. In experiment II, time course effects of fructose intervention were monitored using the same conditions; mice were killed at the baseline, fourth, and sixth weeks. Bioinformatic analyses for hepatic proteomics revealed that SREBP1 is the most significant upstream regulator influenced by fructose; miR-33-5p (miR-33) was identified as the key miRNA responsible for SREBP1 regulation upon fructose intake, which was validated by in vitro transfection assay. In experiment II, we confirmed that the longer mice consumed fructose, the more severe liver injury markers (e.g., serum AST) appeared. Moreover, hepatic Srebp1 mRNA expression was increased depending upon the duration of fructose consumption. Hepatic miR-33 was time-dependently decreased by fructose while serum miR-33 expression was increased; these observations indicated that miR-33 from the liver might be released upon cell damage. Finally we observed that fructose-induced ferroptosis might be a cause of liver toxicity, resulting from oxidative damage. Collectively, our findings suggest that fructose-induced oxidative damage induces ferroptosis, and miR-33 could be used as a serological biomarker of fructose-induced NAFLD.

Exosomal miRNAs as Potential Biomarkers to Monitor Phosphodiesterase 5 Inhibitor Induced Anti-Fibrotic Effects on CCl4 Treated Rats

MicroRNAs (miRNAs) are short, non-coding RNA species that are important post-transcriptional regulators of gene expression and play an important role in the pathogenesis of non-alcoholic fatty liver disease. Here, we investigated the phosphodiesterase 5 (PDE5) inhibitor induced effects on hepatic and plasma exosomal miRNA expression in CCl₄-treated rats. In the present study, hepatic miRNA profiling was conducted using the Nanostring nCounter technology and mRNA profiling using RNA sequencing from PDE5 treated rats in the model of CCl₄-induced liver fibrosis. To evaluate if the PDE5 inhibitor affected differentially expressed miRNAs in the liver can be detected in plasma exosomes, qRT-PCR specific assays were used. In livers from CCl₄-treated rats, the expression of 22 miRNAs was significantly increased (>1.5-fold, adj. p < 0.05), whereas the expression of 16 miRNAs was significantly decreased (>1.5-fold, adj. p < 0.05). The majority of the deregulated miRNA species are implicated in fibrotic and inflammatory processes. The PDE5 inhibitor suppressed the induction of pro-fibrotic miRNAs, such as miR-99b miR-100 and miR-199a-5p, and restored levels of anti-fibrotic miR-122 and miR-192 in the liver. In plasma exosomes, we observed elevated levels of miR-99b, miR-100 and miR-142-3p after treatment with the PDE5-inhibitor compared to CCl₄/Vehicle-treated. Our study demonstrated for the first time that during the development of hepatic fibrosis in the preclinical model of CCl₄-induced liver fibrosis, defined aspects of miRNA regulated liver pathogenesis are influenced by PDE5 treatment. In conclusion, miRNA profiling of plasma exosomes might be used as a biomarker for NASH progression and monitoring of treatment effects.

Zucker Lean Rats With Hepatic Steatosis Recapitulate Asymptomatic Metabolic Syndrome and Exhibit Greater Sensitivity to Drug-Induced Liver Injury Compared With Standard Nonclinical Sprague-Dawley Rat Model

Fatty liver disease is a potential risk factor for drug-induced liver injury (DILI). Despite advances in nonclinical in vitro and in vivo models to assess liver injury during drug development, the pharmaceutical industry is still plagued by idiosyncratic DILI. Here, we tested the hypothesis that certain features of asymptomatic metabolic syndrome (namely hepatic steatosis) increase the risk for DILI in certain phenotypes of the human population. Comparison of the Zucker Lean (ZL) and Zucker Fatty rats fed a high fat diet (HFD) revealed that HFD-fed ZL rats developed mild hepatic steatosis with compensatory hyperinsulinemia without increases in liver enzymes. We then challenged steatotic HFD-fed ZL rats and Sprague-Dawley (SD) rats fed normal chow, a nonclinical model widely used in the pharmaceutical industry, with acetaminophen overdose to induce liver injury. Observations in HFD-fed ZL rats included increased liver injury enzymes and greater incidence and severity of hepatic necrosis compared with similarly treated SD rats. The HFD-fed ZL rats also had disproportionately higher hepatic drug accumulation, which was linked with abnormal hepatocellular efflux transporter distribution. Here, we identify ZL rats with HFD-induced hepatic steatosis as a more sensitive nonclinical in vivo test system for modeling DILI compared with SD rats fed normal chow.

Genetic and epigenetic factors determining NAFLD risk

BACKGROUND

Hepatic steatosis is a common chronic liver disease that can progress into more severe stages of NAFLD or promote the development of life-threatening secondary diseases for some of those affected. These include the liver itself (nonalcoholic steatohepatitis or NASH; fibrosis and cirrhosis, and hepatocellular carcinoma) or other organs such as the vessels and the heart (cardiovascular disease) or the islets of Langerhans (type 2 diabetes). In addition to elevated caloric intake and a sedentary lifestyle, genetic and epigenetic predisposition contribute to the development of NAFLD and the secondary diseases.

SCOPE OF REVIEW

We present data from genome-wide association studies (GWAS) and functional studies in rodents which describe polymorphisms identified in genes relevant for the disease as well as changes caused by altered DNA methylation and gene regulation via specific miRNAs. The review also provides information on the current status of the use of genetic and epigenetic factors as risk markers.

MAJOR CONCLUSION

With our overview we provide an insight into the genetic and epigenetic landscape of NAFLD and argue about the applicability of currently defined risk scores for risk stratification and conclude that further efforts are needed to make the scores more usable and meaningful.

Pediatric Non-Alcoholic Fatty Liver Disease: Nutritional Origins and Potential Molecular Mechanisms

Non-alcoholic fatty liver disease (NAFLD) is the number one chronic liver disease worldwide and is estimated to affect nearly 40% of obese youth and up to 10% of the general pediatric population without any obvious signs or symptoms. Although the early stages of NAFLD are reversible with diet and lifestyle modifications, detecting such stages is hindered by a lack of non-invasive methods of risk assessment and diagnosis. This absence of non-invasive means of diagnosis is directly related to the scarcity of long-term prospective studies of pediatric NAFLD in children and adolescents. In the majority of pediatric NAFLD cases, the mechanisms driving the origin and rapid progression of NAFLD remain unknown. The progression from NAFLD to non-alcoholic steatohepatitis (NASH) in youth is associated with unique histological features and possible immune processes and metabolic pathways that may reflect different mechanisms compared with adults. Recent data suggest that circulating microRNAs (miRNAs) are important new biomarkers underlying pathways of liver injury. Several factors may contribute to pediatric NAFLD development, including high-sugar diets, in utero exposures via epigenetic alterations, changes in the neonatal microbiome, and altered immune system development and mitochondrial function. This review focuses on the unique aspects of pediatric NAFLD and how nutritional exposures impact the immune system, mitochondria, and liver/gastrointestinal metabolic health. These factors highlight the need for answers to how NAFLD develops in children and for early stage-specific interventions.

A comprehensive review on miR-146a molecular mechanisms in a wide spectrum of immune and non-immune inflammatory diseases

MicroRNAs (miRNAs) are single-strand endogenous and non-coding RNA molecules with a length of about 22 nucleotides, which regulate genes expression, through modulating the translation and stability of their target mRNAs. miR-146a is one of the most studied miRNAs, due to its central role in immune system homeostasis and control of the innate and acquired immune responses. Accordingly, abnormal expression or function of miR-146a results in the incidence and progression of immune and non-immune inflammatory diseases. Its deregulated expression pattern and inefficient function have been reported in a wide spectrum of these illnesses. Based on the existing evidence, this miRNA qualifies as an ideal biomarker for diagnosis, prognosis, and activity evaluation of immune and non-immune inflammatory disorders. Moreover, much attention has recently been paid to therapeutic potential of miR-146a and several researchers have assessed the effects of different drugs on expression and function of this miRNA at diverse experimental, animal, besides human levels, reporting motivating results in the treatment of the diseases. Here, in this comprehensive review, we provide an overview of miR-146a role in the pathogenesis and progression of several immune and non-immune inflammatory diseases such as Rheumatoid arthritis, Systemic lupus erythematosus, Inflammatory bowel disease, Multiple sclerosis, Psoriasis, Graves' disease, Atherosclerosis, Hepatitis, Chronic obstructive pulmonary disease, etc., discuss about its eligibility for being a desirable biomarker for these disorders, and also highlight its therapeutic potential. Understanding these mechanisms underlies the selecting and designing the proper therapeutic targets and medications, which eventually facilitate the treatment process.

High-intensity interval training (HIIT) alleviated NAFLD feature via miR-122 induction in liver of high-fat high-fructose diet induced diabetic rats

Background: Exercise intervention is strongly recommended to manage metabolic diseases. In this study, we investigate, whether HIIT and CET can induce hepatic miR-122 expression, NAFLD rats with diabetes.Methods: 40 Wistar rats divided into 2 groups, non-diabetic (NDC) and diabetic .Type 2 diabetes was induced by high-fat high-fructose diet (HFHFD). Then diabetic rats were subdivided into three groups: diabetic control (HFHFD + DC), CET (HFHFD + CET), and HIIT (HFHFD + HIIT). After eight weeks of exercise on a rodent treadmill, we measured miR-122 and its target genes expression in the liver of rats.Results: HIIT decreased the expression of FAS, ACC, SREBP-1c compared with HFHFD + DC (p = .004, p = .032, p = .043, respectively), and could partially increase miR-122 expression as compared with HFHFD + DC (26.8%, p = .68).Conclusions: Exercise training could be a non-pharmacological intervention for improvement of NAFLD of diabetic rats by induction of miR-122. HIIT had a greater effect on NAFLD amelioration than CET.

Fructose-mediated effects on gene expression and epigenetic mechanisms associated with NAFLD pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is a chronic, frequently progressive condition that develops in response to excessive hepatocyte fat accumulation (i.e., steatosis) in the absence of significant alcohol consumption. Liver steatosis develops as a result of imbalanced lipid metabolism, driven largely by increased rates of de novo lipogenesis and hepatic fatty acid uptake and reduced fatty acid oxidation and/or disposal to the circulation. Fructose is a naturally occurring simple sugar, which is most commonly consumed in modern diets in the form of sucrose, a disaccharide comprised of one molecule of fructose covalently bonded with one molecule of glucose. A number of observational and experimental studies have demonstrated detrimental effects of dietary fructose consumption not only on diverse metabolic outcomes such as insulin resistance and obesity, but also on hepatic steatosis and NAFLD-related fibrosis. Despite the compelling evidence that excessive fructose consumption is associated with the presence of NAFLD and may even promote the development and progression of NAFLD to more clinically severe phenotypes, the molecular mechanisms by which fructose elicits effects on dysregulated liver metabolism remain unclear. Emerging data suggest that dietary fructose may directly alter the expression of genes involved in lipid metabolism, including those that increase hepatic fat accumulation or reduce hepatic fat removal. The aim of this review is to summarize the current research supporting a role for dietary fructose intake in the modulation of transcriptomic and epigenetic mechanisms underlying the pathogenesis of NAFLD.

Synergistic antifibrotic effects of miR-451 with miR-185 partly by co-targeting EphB2 on hepatic stellate cells

Liver fibrosis is a global health problem currently without clinically approved drugs. It is characterized by the excessive accumulation of extracellular matrix (ECM) mainly produced by activated hepatic stellate cells (HSCs). Uncovering the mechanisms underlying the fibrogenic responses in HSCs may have profound translational implications. Erythropoietin-producing hepatocellular receptor B2 (EphB2) is a receptor tyrosine kinase that has been indicated to be a novel profibrotic factor involved in liver fibrogenesis. In the present study, we investigated the effects of miR-451 and miR-185 on the expression of EphB2 and their roles in liver fibrogenesis both in vitro and in vivo. We found that EphB2 upregulation is a direct downstream molecular event of decreased expression of miR-451 and miR-185 in the process of liver fibrosis. Moreover, miR-451 was unexpectedly found to upregulate miR-185 expression at the post-transcriptional level by directly targeting the nuclear export receptor exportin 1 (XPO-1) and synergistically suppress HSCs activation with miR-185. To investigate the clinical potential of these miRNAs, miR-451/miR-185 agomirs were injected individually or jointly into CCl4-treated mice. The results showed that coadministration of these agomirs synergistically alleviated liver fibrosis in vivo. These findings indicate that miR-451 and miR-451/XPO-1/miR-185 axis play important and synergistic regulatory roles in hepatic fibrosis partly through co-targeting EphB2, which provides a novel therapeutic strategy for the treatment of hepatic fibrosis.

Low Circulating Levels of miR-451a in Girls with Polycystic Ovary Syndrome: Different Effects of Randomized Treatments

CONTEXT

Polycystic ovary syndrome (PCOS) is a prevalent disorder in adolescent girls, purportedly driven by hepato-visceral fat excess, and often followed by subfertility and type 2 diabetes.

OBJECTIVE

We studied the baseline microRNA (miRNA) profile of girls with PCOS, and the effects of a randomized treatment with an oral contraceptive (OC) or with spironolactone-pioglitazone-metformin (SPIOMET, aiming at loss of hepato-visceral fat excess) for 1 year.

DESIGN & PATIENTS

The miRNA profile was assessed by RNA sequencing in girls with PCOS who had participated in a randomized, open-label, single-center, pilot study (n = 31; age 15.7 years, body mass index (BMI) 23.1 kg/m2). Healthy age- and BMI-matched girls (n = 13) served as controls. Differentially expressed miRNAs were validated by RT-qPCR in the entire study population. Post-treatment ovulation rates were assessed by salivary progesterone in PCOS girls.

SETTING

Endocrinology Department, University Hospital.

RESULTS

Girls with PCOS, compared with controls, had markedly reduced concentrations of circulating miR-451a, miR-652-3p, miR-106b-5p, and miR-206; pathway enrichment analysis showed that these miRNAs target genes involved in energy homeostasis and cell cycle control. In the present study, miR-451a could diagnose PCOS with 100% sensitivity and 100% specificity. SPIOMET (but not OC) was accompanied by on-treatment normalization of the miRNA profile in girls with PCOS; miR-451a concentrations after 1 year on OC or SPIOMET treatment associated closely (r = 0.66; P < .0001) with post-treatment ovulation rates.

CONCLUSION

SPIOMET treatment for 1 year normalizes the miRNA profile of girls with PCOS. Circulating miR-451a may become a biomarker to guide the diagnosis and treatment of PCOS in adolescence.

Serum miR-379 expression is related to the development and progression of hypercholesterolemia in non-alcoholic fatty liver disease

Introduction

Non-alcoholic fatty liver disease (NAFLD) has a wide spectrum, eventually leading to cirrhosis and hepatic carcinogenesis. We previously reported that a series of microRNAs (miRNAs) mapped in the 14q32.2 maternally imprinted gene region (Dlk1-Dio3 mat) are related to NAFLD development and progression in a mouse model. We examined the suitability of miR-379, a circulating Dlk1-Dio3 mat miRNA, as a human NAFLD biomarker.

Methods

Eighty NAFLD patients were recruited for this study. miR-379 was selected from the putative Dlk1-Dio3 mat miRNA cluster because it exhibited the greatest expression difference between NAFLD and non-alcoholic steatohepatitis in our preliminary study. Real-time PCR was used to examine the expression levels of miR-379 and miR-16 as an internal control. One patient was excluded due to low RT-PCR signal.

Results

Compared to normal controls, serum miR-379 expression was significantly up-regulated in NAFLD patients. Receiver operating characteristic curve analysis suggested that miR-379 is a suitable marker for discriminating NAFLD patients from controls, with an area under the curve value of 0.72. Serum miR-379 exhibited positive correlations with alkaline phosphatase, total cholesterol, low-density-lipoprotein cholesterol and non-high-density-lipoprotein cholesterol levels in patients with early stage NAFLD (Brunt fibrosis stage 0 to 1). The correlation between serum miR-379 and cholesterol levels was lost in early stage NAFLD patients treated with statins. Software-based predictions indicated that various energy metabolism–related genes, including insulin-like growth factor-1 (IGF-1) and IGF-1 receptor, are potential targets of miR-379.

Conclusions

Serum miR-379 exhibits high potential as a biomarker for NAFLD. miR-379 appears to increase cholesterol lipotoxicity, leading to the development and progression of NAFLD, via interference with the expression of target genes, including those related to the IGF-1 signaling pathway. Our results could facilitate future research into the pathogenesis, diagnosis, and treatment of NAFLD.

NonInvasive Biomarkers in Nonalcoholic Fatty Liver Disease: Are We There Yet?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. NAFLD encompasses a spectrum of disease ranging from simple steatosis (NAFL) to nonalcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma. However, despite the growing recognition of this important disease burden, there are significant challenges to accurately and noninvasively diagnose the various forms of NAFLD, especially to differentiate benign steatosis from the progressive NASH. This is of utmost importance because although liver biopsy is considered the current imperfect 'gold' standard for diagnosing NASH and staging fibrosis, it is an invasive procedure with significant limitations. Although, a number of noninvasive markers have been or are currently undergoing investigation, until date, no highly sensitive and specific tests are available to differentiate NASH from simple steatosis. At the moment, further investigations are needed before prediction models or blood-based biomarkers become available and acceptable for routine clinical care. There is a great need for developing inexpensive, easily accessible, highly sensitive and specific biomarkers that permit not only the identification of patients at high risk of adverse outcomes, but also the monitoring of disease progression and response after therapeutic interventions.

Physical exercise and liver "fitness": Role of mitochondrial function and epigenetics-related mechanisms in non-alcoholic fatty liver disease

BACKGROUND

Modern lifestyles, especially high-caloric intake and physical inactivity, contribute to the increased prevalence of non-alcoholic fatty liver disease (NAFLD), which becomes a significant health problem worldwide. Lifestyle changes, however, affect not only parental generation, but also their offspring, reinforcing the need for efficient preventive approaches to deal with this disease. This transgenerational influence of phenotypes dependent on parents (particularly maternal) behaviours may open additional research avenues. Despite persistent attempts to design an effective pharmacological therapy against NAFLD, physical activity, as a non-pharmacological approach, emerges as an exciting strategy.

SCOPE OF REVIEW

Here we briefly review the effect of physical exercise on liver mitochondria adaptations in NAFLD, highlighting the importance of mitochondrial metabolism and transgenerational and epigenetic mechanisms in liver diseases.

MAJOR CONCLUSIONS

A deeper look into cellular mechanisms sheds a light on possible effects of physical activity in the prevention and treatment of NAFLD through modulation of function and structure of particular organelles, namely mitochondria. Additionally, despite of increasing evidence regarding the contribution of epigenetic mechanisms in the pathogenesis of different diseases, the role of microRNAs, DNA methylation, and histone modification in NAFLD pathogenesis still needs to be elucidated.

Early life high-fat diet exposure maintains glucose tolerance and insulin sensitivity with a fatty liver and small brain size in the adult offspring

Diet during pregnancy has long lasting consequences on the offspring, warranting a study on the impact of early exposure to a high fat diet on the adult offspring. We hypothesized that a prenatal n-6 enriched diet will have adverse metabolic outcomes on the adult offspring that may be reversed with a postnatal n-3 enriched diet. To test this hypothesis, we examined the adult offspring from three groups: (1) n-6 group: during gestation and lactation, dams consumed an n-6 polyunsaturated fatty acid enriched diet, (2) n-3 group: gestational n-6 diet was followed by an n-3 enriched diet during lactation, and (3) a control (CD) group that received standard diet throughout gestation and lactation. Offspring from all groups weaned to a control diet ad libitum. Beginning at postnatal day 2 (P < .03) and persisting at 360 days in males (P < .04), an increase in hypothalamic AgRP expression occurred in the n-6 and n-3 groups, with an increase in food intake (P = .01), and the n-3 group displaying lower body (P < .03) and brain (P < .05) weights. At 360 days, the n-6 and n-3 groups remained glucose tolerant and insulin sensitive, with increased phosphorylated-AMP-activated protein kinase (P < .05). n-6 group developed hepatic steatosis with reduced hepatic reflected as higher plasma microRNA-122 (P < .04) that targets pAMPK. We conclude that early life exposure to n-6 and n-3 led to hypothalamic AgRP-related higher food intake, with n-6 culminating in a fatty liver partially mitigated by postnatal n-3. While both diets preserved glucose tolerance and insulin sensitivity, postnatal n-3 displayed detrimental effects on the brain.

Molecular Insight into the Interaction between Epigenetics and Leptin in Metabolic Disorders

Nowadays, it is well-known that the deregulation of epigenetic machinery is a common biological event leading to the development and progression of metabolic disorders. Moreover, the expression level and actions of leptin, a vast adipocytokine regulating energy metabolism, appear to be strongly associated with epigenetics. Therefore, the aim of this review was to summarize the current knowledge of the epigenetic regulation of leptin as well as the leptin-induced epigenetic modifications in metabolic disorders and associated phenomena. The collected data indicated that the deregulation of leptin expression and secretion that occurs during the course of metabolic diseases is underlain by a variation in the level of promoter methylation, the occurrence of histone modifications, along with miRNA interference. Furthermore, leptin was proven to epigenetically regulate several miRNAs and affect the activity of the histone deacetylases. These epigenetic modifications were observed in obesity, gestational diabetes, metabolic syndrome and concerned various molecular processes like glucose metabolism, insulin sensitivity, liver fibrosis, obesity-related carcinogenesis, adipogenesis or fetal/early postnatal programming. Moreover, the circulating miRNA profiles were associated with the plasma leptin level in metabolic syndrome, and miRNAs were found to be involved in hypothalamic leptin sensitivity. In summary, the evidence suggests that leptin is both a target and a mediator of epigenetic changes that develop in numerous tissues during metabolic disorders.

Oleic acid-induced perilipin 5 expression and lipid droplets formation are regulated by the PI3K/PPARα pathway in HepG2 cells

Perilipin 5 (Plin5), a member of the PAT (Perilipin, ADRP, and Tip47) protein family, has been implicated in the regulation of cellular neutral lipid accumulation in nonalcoholic fatty liver diseases. However, the underlying regulatory mechanisms of Plin5 are not clear. The goal of the present study was to explore the mechanism of oleic acid (OA)-induced Plin5 expression in HepG2 cells. We found that the expression of Plin5 was increased during OA-induced lipid droplets formation in a dose- and time-dependent manner. During this process of OA-stimulated lipid droplets formation, peroxisome proliferator-activated receptor alpha (PPARα) was also upregulated. When PPARα activation was blocked by GW6471, OA-induced Plin5 expression and lipid droplets formation were effectively ablated. We further found that the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 was able to downregulate both PPARα and Plin5 expression and lipid droplets formation. Thus, we concluded that PI3K may, at least in part, act upstream of PPARα to regulate Plin5 expression and lipid droplets formation in HepG2 cells.

High Fructose Intake and Adipogenesis

In modern societies, high fructose intake from sugar-sweetened beverages has contributed to obesity development. In the diet, sucrose and high fructose corn syrup are the main sources of fructose and can be metabolized in the intestine and transported into the systemic circulation. The liver can metabolize around 70% of fructose intake, while the remaining is metabolized by other tissues. Several tissues including adipose tissue express the main fructose transporter GLUT5. In vivo, chronic fructose intake promotes white adipose tissue accumulation through activating adipogenesis. In vitro experiments have also demonstrated that fructose alone induces adipogenesis by several mechanisms, including (1) triglycerides and very-low-density lipoprotein (VLDL) production by fructose metabolism, (2) the stimulation of glucocorticoid activation by increasing 11β-HSD1 activity, and (3) the promotion of reactive oxygen species (ROS) production through uric acid, NOX and XOR expression, mTORC1 signaling and Ang II induction. Moreover, it has been observed that fructose induces adipogenesis through increased ACE2 expression, which promotes high Ang-(1-7) levels, and through the inhibition of the thermogenic program by regulating Sirt1 and UCP1. Finally, microRNAs may also be involved in regulating adipogenesis in high fructose intake conditions. In this paper, we propose further directions for research in fructose participation in adipogenesis.

A comprehensive review on miR-451: A promising cancer biomarker with therapeutic potential

MicroRNAs (miRNAs) are proposed as a family of short noncoding molecules able to manage and control the expression of the gene targets at the posttranscriptional level. They contribute in several fundamental physiological mechanisms as well as a verity of human and animal diseases such as cancer progression. Among these tiny RNAs, miR-451 placed on chromosome 17 at 17q11.2 presents an essential role in many biological processes in health condition and also in pathogenesis of different diseases. Besides, it has been recently considered as a valuable biomarker for cancer detection, prognosis and treatment. Therefore, this review will provide the critical functions of miR-451 on biological mechanisms including cell cycle and proliferation, cell survival and apoptosis, differentiation and development as well as disease initiation and progression such as tumor formation, migration, invasion, and metastasis.

Transcriptional Repression of CYP3A4 by Increased miR-200a-3p and miR-150-5p Promotes Steatosis in vitro

Hepatic cytochrome P450 enzyme activities correlate with non-alcoholic fatty liver disease (NAFLD) and hepatic steatosis. The decreased activity of CYP3A4, an important drug-metabolizing enzyme, is associated with the progression of NAFLD. CYP3A4 is predicted as a target gene of miR-200a-3p and miR-150-5p by MicroInspector and TargetScan algorithms analyses. Here, we found decreased CYP3A4 and increased miR-200a-3p and miR-150-5p in LO2 cells with free fatty acid (FFA)-induced steatosis. Dual-luciferase assay confirmed that both miR-200a-3p and miR-150-5p targeted the 3'-untranslated region (3'-UTR) of CYP3A4 and that such interaction was abolished by miRNA binding site mutations in 3'-UTR of CYP3A4. Using miR-200a-3p and miR-150-5p mimics and inhibitors, we further confirmed that endogenous CYP3A4 was regulated posttranscriptionally by miR-200a-3p or miR-150-5p. Moreover, miR-200a-3p and miR-150-5p inhibitors attenuated FFA-induced steatosis in LO2 cells, and such effect was dependent on CYP3Y4 expression. These results suggest that miR-200a-3p and miR-150-5p, through directly targeting 3'-UTR of CYP3A4, contribute to the development of FFA-induced steatosis.

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.

Regulatory Non-coding RNAs Network in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) spectrum comprises simple steatosis and non-alcoholic steatohepatitis (NASH) that can lead to fibrosis and cirrhosis. The patients usually have no history of excessive alcohol consumption and other etiologies that can cause fatty liver. Understanding of the pathophysiology of NAFLD has revealed that non-coding RNAs (ncRNAs) play significant roles in modulating the disease susceptibility, pathogenesis and progression. Currently, the ncRNAs are grouped according to their sizes and their regulatory or housekeeping functions. Each of these ncRNAs has a wide range of involvement in the regulation of the genes and biological pathways. Here, we briefly review the current literature the regulatory ncRNAs in NAFLD pathogenesis and progression, mainly the microRNAs, long non-coding RNAs and circular RNAs. We also discuss the co-regulatory functions and interactions between these ncRNAs in modulating the disease pathogenesis. Elucidation of ncRNAs in NAFLD may facilitate the identification of early diagnostic biomarkers and development of therapeutic strategies for NAFLD.

Down-Regulation of SIRT1 Expression by mir-23b Contributes to Lipid Accumulation in HepG2 Cells

Non-alcoholic fatty liver disease is one of the main causes of chronic liver disease and therefore is currently considered a major public health problem. Sirtuin 1 (SIRT1) is an NAD-dependent deacetylase enzyme that contributes in the regulation of metabolic processes and protects against lipid accumulation in hepatocytes. Its expression is potentially regulated by microRNAs which attach to the 3' untranslated region (3'-UTR) of their target mRNA. HepG2 cells were incubated by glucose to induce lipid accumulation and were subsequently transfected with mir-23b mimic and inhibitor. Real-time PCR was used for measuring the expression of mir-23b and SIRT1 mRNA. Cell survival assay and intracellular triglyceride measurement were performed using colorimetric methods. Determination of SIRT1 protein level and activity were done by western blot and fluorometric analysis, respectively. The interaction of miR-23b with 3'-UTR of SIRT1 mRNA was confirmed by dual luciferase. miR-23b mimic inhibited gene and protein expression of SIRT1, while the inhibitor of miR-23b significantly elevated the expression levels of SIRT1 mRNA and protein. The results showed that the 3'-UTR of SIRT1 mRNA is a direct target for miR-23b. The intracellular triglyceride level was increased following the inhibition of SIRT1 in transfected HepG2 cell by miR-23b mimic. Cell viability was decreased in response to miR-23b upregulation compared to control cells. miR-23b reduces the expression and activity of SIRT1 and therefore may be a causative factor in the enhancement of lipid accumulation in HepG2 cells.

An updated view on the origin and use of angiogenic biomarkers for preeclampsia

Introduction: The last decade has seen massive efforts towards the identification and the potential use of predictive biomarkers for the pregnancy pathology preeclampsia. The angiogenic factors sFlt-1 and placental growth factor (PGF) have been in focus and have been massively supported. Areas covered: This review describes preeclampsia and intra-uterine growth restriction (IUGR), focusing on sFlt-1 and PGF, their sources during and outside pregnancy and the application of these markers in diseases outside pregnancy. Finally, the specificity of the angiogenic markers for preeclampsia is discussed. Expert commentary: The admixture of the two independent syndromes preeclampsia and IUGR has not helped in identifying the etiologies of either. Rather, it has made the search for new markers and pathways much more complicated as has the constriction on the angiogenic markers. The current markers sFlt-1 and PGF have a clear value once an adverse outcome is diagnosed but are not specific for preeclampsia. Also, they are mostly derived from the maternal vascular system rather than the placenta and are already in use as markers outside pregnancy. A new holistic approach using disease maps and interoperable workflows based on topic-related big data will help in broadening our understanding of the etiology of preeclampsia and hence, develop new markers and 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.

trans-Chalcone prevents insulin resistance and hepatic inflammation and also promotes hepatic cholesterol efflux in high-fat diet-fed rats: modulation of miR-34a-, miR-451-, and miR-33a-related pathways

Insulin resistance and inflammation are strongly linked to non-alcoholic fatty liver disease (NAFLD) as a feature of the metabolic syndrome. Furthermore, the role of dysregulation of miR-34a, miR-451, and miR-33a in pathogenesis and progression of NAFLD has been identified. trans-Chalcone is a simple chalcone with anti-diabetic and anti-inflammatory activities. However, to the best of our knowledge, miRNA-dependent mechanisms of these protective effects under pathologic conditions are not understood. Thus, this study, for the first time, aimed to evaluate the effects of trans-Chalcone on miR-34a, miR-451, and miR-33a signaling pathways in the liver of high-fat (HF) emulsion-fed rats. To this aim, twenty-one rats were randomly and equally divided into three groups: control, which was gavaged with 10% tween 80; HF, which was gavaged with HF emulsion and 10% tween 80; and HF + trans-Chalcone (HF + TC), which was gavaged with HF emulsion and trans-Chalcone. Then, circulating levels of glucose and insulin were measured and used for the calculation of HOMA-IR. Hepatic expression levels of miR-34a, miR-451, miR-33a, SIRT1, and ABCA1 and also protein levels of ABCA1 and IL-8 were assayed. In this study, trans-chalcone increased hepatic cholesterol efflux and prevented insulin resistance and liver inflammation in HF emulsion-fed rats. These protective effects were modulated through the down-regulation of miR-34a and its associated elevation of SIRT1, the up-regulation of miR-451 which was associated with a reduction in IL-8, and the inhibition of miR-33a which was related to the elevation of ABCA1 in the liver of HF emulsion-fed rats. Therefore, trans-Chalcone exerts its beneficial effects by targeting hepatic miR-34a-, miR-451-, and miR-33a-related pathways.

DLREFD: a database providing associations of long non-coding RNAs, environmental factors and phenotypes

Database URL

http://chengroup.cumt.edu.cn/DLREFD.