Adipocytokine expression associated with miRNA regulation and diagnosis of NASH in obese patients with NAFLD

The role of interleukin-20 in liver disease: Functions, mechanisms and clinical applications

Liver disease is a severe public health concern worldwide. There is a close relationship between the liver and cytokines, and liver inflammation from a variety of causes leads to the release and activation of cytokines. The functions of cytokines are complex and variable, and are closely related to their cellular origin, target molecules and mode of action. Interleukin (IL)-20 has been studied as a pro-inflammatory cytokine that is expressed and regulated in some diseases. Furthermore, accumulating evidences has shown that IL-20 is highly expressed in clinical samples from patients with liver disease, promoting the production of pro-inflammatory molecules involved in liver disease progression, and antagonists of IL-20 can effectively inhibit liver injury and produce protective effects. This review highlights the potential of targeting IL-20 in liver diseases, elucidates the potential mechanisms of IL-20 inducing liver injury, and suggests multiple viable strategies to mitigate the pro-inflammatory response to IL-20. Genomic CRISPR/Cas9-based screens may be a feasible way to further explore the signaling pathways and regulation of IL-20 in liver diseases. Nanovector systems targeting IL-20 offer new possibilities for the treatment and prevention of liver diseases.

Integration of miRNA-lncRNA-mRNA profiles in liver tissue from EpCAM knockout mice

The epithelial cell adhesion molecule (EpCAM) is highly expressed in the liver during development and diseases. However, its role in the development and pathology of liver remains to be explored. The liver tissues of EpCAM-/- and wildtype (WT) mice at P0 stage were used for RNA sequencing. The differently expressed miRNAs, lncRNAs and mRNAs were selected and confirmed by qPCR. The expression of metabolism-related gene SET domain bifurcated 2 (Setdb2) was significantly increased in the liver of EpCAM-/- mice; the triglyceride (TG) and total cholesterol (TC) levels in the liver were also markedly decreased in EpCAM-/- mice. The microRNA (miRNA)-long noncoding RNA (lncRNA)-mRNA regulatory networks indicated that EpCAM may play important roles in glucose and lipid metabolism of the liver during development and in disease. The comprehensive miRNA, lncRNA and mRNA expression profiles in the developing liver of EpCAM-/- mice established here might help to elucidate functions and mechanisms of EpCAM during development and in diseases of the liver.

A Distinctive NAFLD Signature in Adipose Tissue from Women with Severe Obesity

Development and severity of nonalcoholic fatty liver disease (NAFLD) have been linked to obesity and white adipose tissue (WAT) dysfunction plays a key role in this relation. We compared the main features of subcutaneous (SAT) and visceral WAT (VAT) tissue dysfunction in 48 obese women without (Ob) and with NAFLD (Ob-NAFLD) undergoing bariatric surgery and matched for age, BMI and T2D status. Fat cell area, adipocyte size distribution, the degree of histological fibrosis and the mRNA expression of adipokines and genes implicated in inflammation, adipogenesis, angiogenesis, metabolism and extracellular matrix remodeling were measured by RT-qPCR in both fat depots. Ob-NAFLD group showed higher TG and lower HDL circulating levels, increased VAT fat cell area and similar WAT fibrosis in comparison with Ob group. A sPLS-DA was performed in order to identify the set of genes that better characterize the presence of NAFLD. Finally, we build a multinomial logistic model including seven genes that explained 100% of the variance in NAFLD and correctly predicted 100% of cases. Our data support the existence of distinctive NAFLD signatures in WAT from women with severe obesity. A better understanding of these pathways may help in future strategies for the prevention and treatment of NAFLD.

Correlation analysis of microribonucleic acid-155 and microribonucleic acid-29 with type 2 diabetes mellitus, and the prediction and verification of target genes

AIMS/INTRODUCTION

Microribonucleic acid-155 (microRNA155) and microRNA29 are reported to inhibit glucose metabolism in some cell and animal models, but no evidence from susceptible populations that examines the relationship between microRNA155 or microRNA29 and type 2 diabetes mellitus currently exists. Furthermore, target genes regulated by microRNA155 and microRNA29 that affect glucose and lipid metabolism remain unknown.

MATERIALS AND METHODS

Human participants were divided into normal weight (n = 72), obesity (n = 120) and type 2 diabetes (n = 59) groups. The contents of microRNA155 and microRNA29 abundance in serum were measured, and candidate genes potentially related to glucose and lipid metabolism targeted by either microRNA155 or microRNA29 were screened. Overexpression of microRNA155 and microRNA29 in HepG2 cells was used to verify candidate gene expression, and measure the effects on glucose and lipid metabolism.

RESULTS

Serum levels of microRNA155 and microRNA29 show a significant increase in individuals with obesity and type 2 diabetes compared with normal weight individuals. Identified target genes for microRNA155 were MAPK14, MAP3K10, DUSP14 and PRKAR2B. Identified target genes for microRNA29 were PEX11A and FADS1. Overexpression of microRNA155 or microRNA29 in HepG2 cells was found to downregulate the expression of identified target genes, and result in inhibition of triglyceride synthesis and glucose incorporation.

CONCLUSIONS

MicroRNA155 and microRNA29 were significantly higher in type 2 diabetes patients compared with the control patients, their levels were also positively correlated with fasting plasma glucose levels, and over-expression of microRNA155 or microRNA29 were found to downregulate glucose and lipid metabolism target genes, and reduce lipid synthesis and glucose incorporation in HepG2 cells.

Targeting of miR-96-5p by catalpol ameliorates oxidative stress and hepatic steatosis in LDLr-/- mice via p66shc/cytochrome C cascade

Hepatic steatosis and oxidative stress are considered to be the sequential steps in the development of non-alcoholic fatty liver disease (NAFLD). We previously found that catalpol, an iridoid glucoside extracted from the root of Romania glutinosa L, protected against diabetes-induced hepatic oxidative stress. Here, we found that the increased expression of p66shc was observed in NAFLD models and catalpol could inhibit p66shc expression to ameliorate NAFLD effectively. However, the underlying mechanisms remained unknown. The aim of the present study was to investigate the p66shc-targeting miRNAs in regulating oxidative stress and hepatic steatosis, also the mechanisms of catalpol inhibiting NAFLD. We found that the effects of catalpol inhibiting hepatic oxidative stress and steasis are dependent on inhibiting P66Shc expression. In addition, miR-96-5p was able to suppress p66shc/cytochrome C cascade via targeting p66shc mRNA 3’UTR, and catalpol could lead to suppression of NAFLD via upregulating miR-96-5p level. Thus, catalpol was effective in ameliorating NAFLD, and miR-96-5p/p66shc/cytochrome C cascade might be a potential target.

Dysregulation of microRNA-125a contributes to obesity-associated insulin resistance and dysregulates lipid metabolism in mice

Obesity is associated with an increased risk of developing insulin resistance (IR) and type 2 diabetes (T2D). A diverse group of factors including miRNA has been implicated in the pathogenesis of these two metabolic conditions, although underlying molecular mechanisms involved are not well defined. Here, we provide evidence that hepatic miR-125a levels are diminished in both genetic as well as dietary mouse models of obesity. Overexpression of miR-125a enhanced insulin signaling and attenuated cellular lipid accumulation in HepG2 cells and Hepa1-6 cells. Likewise, treatment of mice with ago-miR-125a increased insulin sensitivity, similar to overexpression of miR-125a, whereas treatment of mice with antago-miR-125a blunted the insulin sensitivity. Furthermore, overexpression of miR-125a in mice previously fed a high-fat diet (HFD), significantly improved insulin sensitivity, and attenuated obesity-linked hepatic steatosis and hepatocyte lipid accumulation. In addition, we show that ELOVL fatty acid elongase 6 (Elovl6) is a direct target of miR-125a, and participates in miR-125a mediated regulation of insulin sensitivity and lipid metabolism. These data led us to conclude that dysregulated miR-125a expression augments the development of obesity-induced IR and that miR-125a might serve as a therapeutic target for the development of new drug(s) in the clinical management of metabolic diseases.

Common Variants in IL-20 Gene are Associated with Subclinical Atherosclerosis, Cardiovascular Risk Factors and IL-20 Levels in the Cohort of the Genetics of Atherosclerotic Disease (GEA) Mexican Study

Inflammation has been involved in the development of atherosclerosis, type 2 diabetes mellitus, insulin resistance, and obesity. Interleukin 20 is a pro-inflammatory cytokine encoded by a polymorphic gene located in chromosome 1. The aim of the study was to evaluate the association of two IL-20 polymorphisms (rs1400986 and rs1518108) with subclinical atherosclerosis (SA), cardiovascular risk factors and IL-20 levels in a cohort of Mexican individuals. The polymorphisms were determined in 274 individuals with SA and 672 controls. Under different models, rs1400986 (OR = 0.51, P_codominant1 = 0.0001; OR = 0.36, P_codominant2 = 0.014; OR = 0.49, P_dominant = 0.0001 and OR = 0.55, P_additive = 0.0001) and rs1518108 (OR = 0.62, P_codominant2 = 0.048 and OR = 0.79, P_additive = 0.048) were associated with a lower risk of SA. These polymorphisms were associated with cardiovascular risk factors in individuals with SA and controls. Controls with the rs1400986 TT genotype presented high levels of IL-20 (p = 0.031). In individuals with the rs1400986 CC genotype, we observed a negative correlation between IL-20 levels and total abdominal tissue (TAT), visceral abdominal tissue (VAT) and subcutaneous abdominal tissue (SAT). Our results indicate that the IL-20 rs1400986 and rs1518108 polymorphisms were associated with decreased risk of developing SA and with some cardiovascular risk factors in individuals with SA and healthy controls. Negative correlation between BMI and VAT/SAT ratio in individuals with rs1400986 CC genotype and among IL-20 levels and TAT, VAT and SAT was observed.

Mapping Research in the Obesity, Adipose Tissue, and MicroRNA Field: A Bibliometric Analysis

Recent studies have investigated the control of adipose tissue expansion and inflammatory process by microRNAs (miRNAs). These two processes are of great interest because both are associated with obesity and metabolic syndrome. However, despite the great relevance of the role of miRNAs in obesity and adipose tissue, no qualitative and quantitative analysis on the subject has been performed. Thus, we aimed to examine global research activity and current trends with respect to the interaction between obesity, adipose tissue and miRNAs through a bibliometric analysis. This research was performed on the Scopus database for publications containing miRNA, obesity, and adipose tissue keyword combinations. In total, 898 articles were analyzed and the most frequently occurring keywords were selected and clustered into three well-defined groups. As a result, first group of keywords pointed to the research area on miRNAs expressed in obesity-associated diseases. The second group demonstrated the regulation of the adipogenesis process by miRNAs, while the third group highlighted brown adipose tissue and thermogenesis as one of the latest global research trends related to the theme. The studies selected in this paper describe the expression and performance of different miRNAs in obesity and comorbidities. Most studies have focused on identifying miRNAs and signaling pathways associated with obesity, type 2 diabetes mellitus, and cardiovascular disease. Thus, the miRNA profile for these diseases may be used as biomarkers and therapeutic targets in the prevention and treatment of obesity-associated diseases.

MicroRNA-29a Disrupts DNMT3b to Ameliorate Diet-Induced Non-Alcoholic Steatohepatitis in Mice

MicroRNA-29 (miR-29) has been found to reduce liver inflammation and fibrosis following a liver injury. Meanwhile, DNA methyltransferase has been reported to participate in the development of non-alcoholic steatohepatitis (NASH). The aim of this study is to investigate the miR-29a regulation of methyltransferase signaling and epigenetic program in NASH progression. Methods: miR-29a transgenic mice (miR-29aTg mice) and wild-type littermates were subjected to the methionine-choline-deficient (MCD) diet-induced animal model of NASH. Primary hepatic stellate cells were transfected with a miR-29a mimic and antisense inhibitor. We then analyzed gene expressions with qRT-PCR, immunohistochemical stain, Western blot, and luciferase reporter assay. The results demonstrated that increased miR-29a alleviated the MCD diet-induced body weight loss and steatosis and decreased aspartate aminotransferase (AST) levels in mice. Furthermore, hepatic tissue in miR-29aTg mice displayed a weak fibrotic matrix, as shown with Sirius Red staining concomitant with low fibrotic α-SMA expression within affected tissues compared to the wild-type mice fed the MCD diet. Forced miR-29a expression reduced the MCD diet exaggeration of reactive oxygen species (ROS) production by immunohistochemically staining 8-OHdG. Increased miR-29a signaling also resulted in the downregulation of DNMT3b, TGF-β, IL-6, heme oxygenase-1 (HO-1), p-SMAD3, PI3K, and L3BII expression within the liver tissue. An in vitro luciferase reporter assay further confirmed that miR-29a mimic transfection reduced DNMT3b expression in primary HSCs. Our data provide new insights that miR-29a improves MCD diet-induced liver inflammation, steatosis and fibrosis, and highlight the potential of miR-29a targeted therapy for treating NASH.

Dietary cholesterol promotes steatohepatitis related hepatocellular carcinoma through dysregulated metabolism and calcium signaling

The underlining mechanisms of dietary cholesterol and nonalcoholic steatohepatitis (NASH) in contributing to hepatocellular carcinoma (HCC) remain undefined. Here we demonstrated that high-fat-non-cholesterol-fed mice developed simple steatosis, whilst high-fat-high-cholesterol-fed mice developed NASH. Moreover, dietary cholesterol induced larger and more numerous NASH-HCCs than non-cholesterol-induced steatosis-HCCs in diethylnitrosamine-treated mice. NASH-HCCs displayed significantly more aberrant gene expression-enriched signaling pathways and more non-synonymous somatic mutations than steatosis-HCCs (335 ± 84/sample vs 43 ± 13/sample). Integrated genetic and expressional alterations in NASH-HCCs affected distinct genes pertinent to five pathways: calcium, insulin, cell adhesion, axon guidance and metabolism. Some of the novel aberrant gene expression, mutations and core oncogenic pathways identified in cholesterol-associated NASH-HCCs in mice were confirmed in human NASH-HCCs, which included metabolism-related genes (ALDH18A1, CAD, CHKA, POLD4, PSPH and SQLE) and recurrently mutated genes (RYR1, MTOR, SDK1, CACNA1H and RYR2). These findings add insights into the link of cholesterol to NASH and NASH-HCC and provide potential therapeutic targets.

Adipocytokine Regulation and Antiangiogenic Activity Underlie the Molecular Mechanisms of Therapeutic Effects of Phyllanthus niruri against Non-Alcoholic Fatty Liver Disease

The growth of adipose tissues is considered angiogenesis-dependent during non-alcoholic fatty liver disease (NAFLD). We have recently reported that our standardized 50% methanolic extract (ME) of Phyllanthus niruri (50% ME of P. niruri) has alleviated NAFLD in Sprague⁻Dawley rats. This study aimed to assess the molecular mechanisms of action, and to further evaluate the antiangiogenic effect of this extract. NAFLD was induced by eight weeks of high-fat diet, and treatment was applied for four weeks. Antiangiogenic activity was assessed by aortic ring assay and by in vitro tests. Our findings demonstrated that the therapeutic effects of 50% ME among NAFLD rats, were associated with a significant increase in serum adiponectin, reduction in the serum levels of RBP4, vaspin, progranulin, TNF-α, IL-6, and significant downregulation of the hepatic gene expression of PPARγ, SLC10A2, and Collα1. Concomitantly, 50% ME of P. niruri has exhibited a potent antiangiogenic activity on ring assay, cell migration, vascular endothelial growth factor (VEGF), and tube formation, without any cytotoxic effect. Together, our findings revealed that the protective effects of P. niruri against NAFLD might be attributed to its antiangiogenic effect, as well as to the regulation of adipocytokines and reducing the expression of adipogenic genes.

The Interleukin-20 Cytokine Family in Liver Disease

The three main causes of inflammation and chronic injury in the liver are viral hepatitis, alcohol consumption, and non-alcoholic steatohepatitis, all of which can lead to liver fibrosis, cirrhosis, and hepatocellular carcinoma, which in turn may prompt the need for liver transplant. The interleukin (IL)-20 is a subfamily part of the IL-10 family of cytokines that helps the liver respond to damage and disease, they participate in the control of tissue homeostasis, and in the immunological responses developed in this organ. The best-studied member of the family in inflammatory balance of the liver is the IL-22 cytokine, which on the one hand may have a protective role in fibrosis progression but on the other may induce liver tissue susceptibility in hepatocellular carcinoma development. Other members of the family might also carry out this dual function, as some of them share IL receptor subunits and signal through common intracellular pathways. Investigators are starting to consider the potential for targeting IL-20 subfamily members in liver disease. The recently explored role of miRNA in the transcriptional regulation of IL-22 and IL-24 opens the door to promising new approaches for controlling the local immune response and limiting organ injury. The IL-20RA cytokine receptor has also been classified as being under miRNA control in non-alcoholic steatohepatitis. Moreover, researchers have proposed combining anti-inflammatory drugs with IL-22 as a hepatoprotective IL for alcoholic liver disease (ALD) treatment, and clinical trials of ILs for managing severe alcoholic-derived liver degeneration are ongoing. In this review, we focus on exploring the role of the IL-20 subfamily of cytokines in viral hepatitis, ALD, non-alcoholic steatohepatitis, and hepatocellular carcinoma, as well as delineating the main strategies explored so far in terms of therapeutic possibilities of the IL-20 subfamily of cytokines in liver disease.

Clinical and Economic Burden of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease with an increasing global prevalence associated with tremendous clinical, economic, and health-related quality-of-life burden. Clinically, NAFLD is considered the liver manifestation of metabolic syndrome. However, diagnosing NAFLD presents significant challenges due to the limited noninvasive and accurate diagnostic tools available to not only accurately diagnose nonalcoholic steatohepatitis but also to stage hepatic fibrosis, the major predictor of long-term outcomes, including mortality.

Identification and characterization of long non-coding RNAs in subcutaneous adipose tissue from castrated and intact full-sib pair Huainan male pigs

Background

Long non-coding RNAs (lncRNAs) regulate adipose tissue metabolism, however, their function on testosterone deficiency related obesity in humans is less understood. For this research, intact and castrated male pigs are the best model animal because of their similar proportional organ sizes, cardiovascular systems and metabolic features.

Results

We identified lncRNAs in subcutaneous adipose tissue by deep RNA-sequencing using the intact and castrated Huainan male pigs. The results showed that castration reduced serum testosterone but increased body fatness-related traits (serum triglyceride levels, backfat thickness, intramuscular fat content, and adipocyte size). Meanwhile, 343 lncRNAs from subcutaneous adipose tissue were identified, including 223 intergenic lncRNAs (lincRNAs), 68 anti-sense lncRNAs, and 52 intronic lncRNAs. It was predicted that there were 416 recognition sites for C/EBPα in the 303 lncRNA promoter region, and 13 adipogenesis-promoting miRNAs and five adipogenesis-depressing miRNAs target these lncRNAs. Eighteen lncRNAs, including nine up- and nine down-regulated had more than 2-fold differential expression between the castrated and intact male pigs (q-value < 0.05). Functional analysis indicated that these 18 lncRNAs and their target genes were involved in fatty acid, insulin, and the adipocytokine signaling pathway. We further analyzed the features of a conserved mouse lncRNA gene ENSMUST00000189966 and found it mainly expressed in the cell nucleus and target the Nuclear Receptor Subfamily 2 Group F Member 2 (NR2F2) gene. In 3 T3-L1 cells, differentiation down-regulated their expression, but dihydrotestosterone (DHT) significantly up-regulated their expression in a concentration-dependent manner (P < 0.05).

Conclusions

These results suggested that lncRNAs and their target genes might participated in the castration-induced fat deposition and provide a new therapeutic target for combatting testosterone deficiency-related obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3907-z) contains supplementary material, which is available to authorized users.

Current Concepts in Pediatric Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of disease. Its increasing prevalence is a direct result of historically high rates of obesity. Hepatocyte lipid accumulation is the first step in a cascade of metabolic and inflammatory events thought to precipitate NAFLD. Histologic findings provide insight into these events. Lifestyle modification remains the primary therapy in children. Current recommendations include vitamin E treatment in those with biopsy-proven NASH. Trials of novel drugs are ongoing in adults. As efficacy/safety are established, these therapies may be tenable for use in children. At the current time, biopsy-driven histology endpoints are necessary to establish whether future therapies can improve pediatric or adult-type NASH in children.

Ezetimibe alleviates non-alcoholic fatty liver disease through the miR-16 inhibiting mTOR/p70S6K1 pathway

Emerging studies have indicated the role of ezetimibe, miR-16 and mTOR signaling in non-alcoholic fatty liver disease (NAFLD).

Neglected features of lifestyle: Their relevance in non-alcoholic fatty liver disease

AIM

To investigated in non-alcoholic-fatty-liver-disease (NAFLD), with ultrasound (US)-detected fatty liver, and in a group of non-alcoholic and otherwise healthy subjects, relationship of neglected features of lifestyle with NAFLD and obesity.

METHODS

Five hundred and thirty-two NAFLD and 667 non-NAFLD healthy subjects, age 21-60 years were studied. Severity of liver steatosis was assessed by US bright liver score. The adherence to mediterranean diet score (AMDS) was assessed on the basis of a 1-wk recall computerized questionnaire which included a detailed physical activity reports (Baecke questionnaire). The western dietary profile score, as a simplified paradigm of unhealthy diet, a questionnaire quantifying sun exposure score and a sleep habits questionnaires provided a further comprehensive lifestyle assessment.

RESULTS

Body mass index (BMI), insulin resistance (HOMA), and triglycerides, poorer adherence to a mediterranean diet profile, sedentary habits, minor sun exposure and use of “western diet” foods are greater in NAFLD. Multiple linear regression analysis, weighted by years of age, displays BMI, HOMA and AMDS as the most powerful independent predictors of fatty liver severity; however, also the physical activity score, the western diet habit and the sun exposure score are acting inside the model with significant independent effects.

CONCLUSION

Articulated clinical intervention, according to our results, are justified in NAFLD and can be pursued addressing by focused intervention nutritional profile, physical exercise mainly in open-air subsets for enhancing sun exposure and healthier sleep duration and rhythm.

Association of serum microRNA-21 levels with Visfatin, inflammation, and acute coronary syndromes

MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression. It seems that microRNA-21 (miR-21) and Visfatin, a novel adipocytokine, play roles in inflammation and atherosclerosis. The aim of this study was to investigate the association of miR-21 with Visfatin, inflammation, atherosclerosis and acute coronary syndrome (ACS). Based on coronary angiography and electrocardiogram (ECG), 53 patients with ACS and 52 patients with stable CAD were enrolled in this study. We assayed serum miR-21, Visfatin, and routine chemistries using quantitative reverse transcriptase polymerase chain reaction (QRT-PCR), enzyme-linked immunosorbent assay (ELISA) and automated analyzer, respectively. We used a regression analysis to describe the relationship between the variables. Serum miR-21 level in 2^-ΔCt value was significantly higher in ACS patients (10.52 ± 1.01-fold) than the stable CAD patients (4.4 ± 0.79-fold) (F = 4.59, p < 0.001). In addition, serum Visfatin was significantly higher in ACS patients (17.5 ± 0.61 ng/ml) than the stable CAD patients (12.7 ± 0.49 ng/ml) (F = 2.62, p < 0.001). Furthermore, the serum miR-21 level correlated positively with serum Visfatin level (r = 0.26, p = 0.008), hs-CRP (r = 0.29, p = 0.003), age (r = 0.21, p = 0.034) and negatively with HDL-cholesterol (r = -0.28, p = 0.004). We concluded that the increased serum miR-21 and Visfatin may be involved in the pathogenesis of ACS through promoting inflammation or may result from inflammatory responses to ACS. Furthermore, the potential role of miR-21 and Visfatin in plaque instability and inflammation warrants further investigations.

Altered microRNA-9 Expression Level is Directly Correlated with Pathogenesis of Nonalcoholic Fatty Liver Disease by Targeting Onecut2 and SIRT1

Background

MicroRNA-9 (miR-9) was detected in nonalcoholic fatty liver disease (NAFLD) patients to understand the role of miR-9 in NAFLD development.

Material/Methods

Between February 2014 and February 2015, 105 cases of NAFLD were recruited and confirmed by liver biopsy pathology, including patients with mild NAFLD (n=58) and moderate-severe NAFLD (n=47); nonalcoholic steatohepatitis (NASH) (n=53) and non-NASH (n=52); and 50 healthy participants were regarded as the healthy control group. MiR-9 expression was measured by qRT-PCR. For in vitro experiments, L-02 normal liver cells were divided into normal control group (cultured with original culture medium), dimethyl sulfoxide (DMSO) group (cultured with DMSO) and oleic acid group (cultured with oleic acid to induce fatty change), and MTT assay was used to measure the effect of different oleic acid concentrations on cell proliferation. Nile red staining was used to detect intracellular accumulation of lipid droplets. Further, synthetic miR-9 mimic and its control and miR-9 inhibitors and its control were independently transfected into L-02 cells.

Results

MiR-9 levels in the mild NAFLD group and moderate-severe NAFLD group were significantly higher than in the healthy control group (both P<0.05). Mean fluorescence intensity of lipid droplets increased with the duration of induction, and were dramatically higher in oleate-treated L-02 cells; intracellular triglyceride (TG) content was also higher. miR-9 levels significantly increased following oleate induction. Importantly, miR-9 levels were significantly elevated upon miR-9 mimic transfection. Conversely, miR-9 level was lowered with miR-9 inhibitors transfection. Additionally, Onecut2 and SIRT1 were identified as miR-9 targets.

Conclusions

A positive relationship between miR-9 and steatosis was established with our results that miR-9 mimic transfection decreased intracellular lipid content. Finally, we identified 2 miR-9 targets, Onecut2 and SIRT1, which may be crucial players in NAFLD development.

MicroRNA-192* impairs adipocyte triglyceride storage

We investigated the expression of miR-192* (miR-192-3p) in the visceral adipose tissue (VAT) of obese subjects and its function in cultured human adipocytes. This miRNA is a 3' arm derived from the same pre-miRNA as miR-192 (miR-192-5p) implicated in type 2 diabetes, liver disease and cancers, and is predicted to target key genes in lipid metabolism. In morbidly obese subjects undergoing bariatric surgery preceded by a very low calorie diet, miR-192* in VAT correlated negatively (r=-0.387; p=0.046) with serum triglyceride (TG) and positively with high-density lipoprotein (HDL) concentration (r=0.396; p=0.041). In a less obese patient cohort, the miRNA correlated negatively with the body mass index (r=-0.537; p=0.026). To characterize the function of miR-192*, we overexpressed it in cultured adipocytes and analyzed the expression of adipogenic differentiation markers as well as cellular TG content. Reduced TG and expression of the adipocyte marker proteins aP2 (adipocyte protein 2) and perilipin 1 were observed. The function of miR-192* was further investigated by transcriptomic profiling of adipocytes expressing this miRNA, revealing impacts on key lipogenic genes. A number of the mRNA alterations were validated by qPCR. Western analysis confirmed a marked reduction of the lipogenic enzyme SCD (stearoyl coenzyme A desaturase-1), the fatty aldehyde dehydrogenase ALDH3A2 (aldehyde dehydrogenase 3 family member A2) and the high-density lipoprotein receptor SCARB1 (scavenger receptor B, type I). SCD and ALDH3A2 were demonstrated to be direct targets of miR-192*. To conclude, the present data identify miR-192* as a novel controller of adipocyte differentiation and lipid homeostasis.

Pathobiology of liver fibrosis: a translational success story

Reversibility of hepatic fibrosis and cirrhosis following antiviral therapy for hepatitis B or C has advanced the prospect of developing antifibrotic therapies for patients with chronic liver diseases, especially non-alcoholic steatohepatitis. Mechanisms of fibrosis have focused on hepatic stellate cells, which become fibrogenic myofibroblasts during injury through 'activation', and are at the nexus of efforts to define novel drug targets. Recent studies have clarified pathways of stellate cell gene regulation and epigenetics, emerging pathways of fibrosis regression through the recruitment and amplification of fibrolytic macrophages, nuanced responses of discrete inflammatory cell subsets and the identification of the 'ductular reaction' as a marker of severe injury and repair. Based on our expanded knowledge of fibrosis pathogenesis, attention is now directed towards strategies for antifibrotic therapies and regulatory challenges for conducting clinical trials with these agents. New therapies are attempting to: 1) Control or cure the primary disease or reduce tissue injury; 2) Target receptor-ligand interactions and intracellular signaling; 3) Inhibit fibrogenesis; and 4) Promote resolution of fibrosis. Progress is urgently needed in validating non-invasive markers of fibrosis progression and regression that can supplant biopsy and shorten the duration of clinical trials. Both scientific and clinical challenges remain, however the past three decades of steady progress in understanding liver fibrosis have contributed to an emerging translational success story, with realistic hopes for antifibrotic therapies to treat patients with chronic liver disease in the near future.