The Role of Long Non-Coding RNAs (lncRNAs) in the Development and Progression of Fibrosis Associated with Nonalcoholic Fatty Liver Disease (NAFLD)

Comprehensive review for non-coding RNAs: From mechanisms to therapeutic applications

Non-coding RNAs (ncRNAs) are an assorted collection of transcripts that are not translated into proteins. Since their discovery, ncRNAs have gained prominence as crucial regulators of various biological functions across diverse cell types and tissues, and their abnormal functioning has been implicated in disease. Notably, extensive research has focused on the relationship between microRNAs (miRNAs) and human cancers, although other types of ncRNAs, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), are also emerging as significant contributors to human disease. In this review, we provide a comprehensive summary of our current knowledge regarding the roles of miRNAs, lncRNAs, and circRNAs in cancer and other major human diseases, particularly cancer, cardiovascular, neurological, and infectious diseases. Moreover, we discuss the potential utilization of ncRNAs as disease biomarkers and as targets for therapeutic interventions.

NAFLD Fibrosis Progression and Type 2 Diabetes: The Hepatic-Metabolic Interplay

The bidirectional relationship between type 2 diabetes and (non-alcoholic fatty liver disease) NAFLD is indicated by the higher prevalence and worse disease course of one condition in the presence of the other, but also by apparent beneficial effects observed in one, when the other is improved. This is partly explained by their belonging to a multisystemic disease that includes components of the metabolic syndrome and shared pathogenetic mechanisms. Throughout the progression of NAFLD to more advanced stages, complex systemic and local metabolic derangements are involved. During fibrogenesis, a significant metabolic reprogramming occurs in the hepatic stellate cells, hepatocytes, and immune cells, engaging carbohydrate and lipid pathways to support the high-energy-requiring processes. The natural history of NAFLD evolves in a variable and dynamic manner, probably due to the interaction of a variable number of modifiable (diet, physical exercise, microbiota composition, etc.) and non-modifiable (genetics, age, ethnicity, etc.) risk factors that may intervene concomitantly, or subsequently/intermittently in time. This may influence the risk (and rate) of fibrosis progression/regression. The recognition and control of the factors that determine a rapid progression of fibrosis (or its regression) are critical, as the fibrosis stages are associated with the risk of liver-related and all-cause mortality.

Identification and Evaluation of Hub Long Noncoding RNAs and mRNAs in High Fat Diet Induced Liver Steatosis

Nonalcoholic fatty liver disease (NAFLD) is considered the most prevalent chronic liver disease, but the understanding of the mechanism of NAFLD is still limited. The aim of our study was to explore hub lncRNAs and mRNAs and pathological processes in high-fat diet (HFD)-induced and lycopene-intervened liver steatosis. We analyzed the gene profiles in the GSE146627 dataset from the Gene Expression Omnibus (GEO) database to identify differentially expressed lncRNAs and mRNAs, and we constructed coexpression networks based on weighted gene coexpression network analysis (WGCNA). The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were utilized for functional enrichment analysis. We found that the turquoise, blue, brown, yellow, green, and black modules were significantly correlated with NAFLD. Functional enrichment analysis revealed that some hub lncRNAs (Smarca2, Tacc1, Flywch1, and Mef2c) might be involved in the regulation of the inflammatory and metabolic pathways (such as TNF signaling, metabolic, mTOR signaling, MAPK signaling, and p53 signaling pathways) in NAFLD. The establishment of an NAFLD mouse model confirmed that lycopene supply attenuated hepatic steatosis in HFD-induced NAFLD. Our analysis revealed that the inflammatory and metabolic pathways may be crucially involved in the pathogenesis of NAFLD, and hub lncRNAs provide novel biomarkers, therapeutic ideas, and targets for NAFLD. Moreover, lycopene has the potential to be a phytochemical for the prevention of HFD-induced liver steatosis.

Mitochondrial Peroxiredoxin III Protects against Non-Alcoholic Fatty Liver Disease Caused by a Methionine-Choline Deficient Diet

Non-alcoholic fatty liver disease (NAFLD) is emerging as the most common chronic liver disease worldwide. In addition, NAFLD may increase the risk of cardiovascular and liver-related diseases, and displays features of metabolic syndrome. In NAFLD, oxidative stress is primarily caused by excessive free fatty acids. The oxidation of fatty acids is usually caused by β-oxidation of mitochondria under normal conditions, resulting in the production of energy. However, when the inflow of fatty acids in NAFLD becomes excessive, the β-oxidation of mitochondria becomes saturated and the oxidation process increases at sites including peroxisomes and microsomes, thereby increasing production of reactive oxygen species (ROS). Thus, hepatic mitochondrial ROS play an important role in the pathogenesis of NAFLD. Eliminating mitochondrial ROS may improve NAFLD, but the underlying mechanism remains unclear. We examined the effect of mitochondrial ROS on NAFLD by focusing on peroxiredoxin (Prx), an antioxidant protein that can remove hydrogen peroxide. The protective effect and pathological phenomenon of mitochondrial peroxiredoxin in methionine-choline deficient diet (MCD)-induced liver injury was assessed in a mouse model of NAFLD. In these mice, mitochondrial peroxiredoxin deficiency significantly increased hepatic steatosis and fibrosis. In addition, ablation of Prx III enhances susceptibility to MCD diet-induced oxidative stress and exacerbates NAFLD progression by promoting inflammation. The binding assay results also showed that Prx III-deficient mice had more severe liver damage than Prx III-abundant mice in MCD diet liver injury models. The present data suggest that mitochondrial peroxiredoxin III could be a therapeutic target for preventing and suppressing diet-induced NAFLD.

Exploring the Regulatory Role of ncRNA in NAFLD: A Particular Focus on PPARs

Liver diseases are responsible for global mortality and morbidity and are a significant cause of death worldwide. Consequently, the advancement of new liver disease targets is of great interest. Non-coding RNA (ncRNA), such as microRNA (miRNA) and long ncRNA (lncRNA), has been proven to play a significant role in the pathogenesis of virtually all acute and chronic liver disorders. Recent studies demonstrated the medical applications of miRNA in various phases of hepatic pathology. PPARs play a major role in regulating many signaling pathways involved in various metabolic disorders. Non-alcoholic fatty liver disease (NAFLD) is the most prevalent form of chronic liver disease in the world, encompassing a spectrum spanning from mild steatosis to severe non-alcoholic steatohepatitis (NASH). PPARs were found to be one of the major regulators in the progression of NAFLD. There is no recognized treatment for NAFLD, even though numerous clinical trials are now underway. NAFLD is a major risk factor for developing hepatocellular carcinoma (HCC), and its frequency increases as obesity and diabetes become more prevalent. Reprogramming anti-diabetic and anti-obesity drugs is an effective therapy option for NAFLD and NASH. Several studies have also focused on the role of ncRNAs in the pathophysiology of NAFLD. The regulatory effects of these ncRNAs make them a primary target for treatments and as early biomarkers. In this study, the main focus will be to understand the regulation of PPARs through ncRNAs and their role in NAFLD.

The Implications of Noncoding RNAs in the Evolution and Progression of Nonalcoholic Fatty Liver Disease (NAFLD)-Related HCC

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver pathology worldwide. Meanwhile, liver cancer represents the sixth most common malignancy, with hepatocellular carcinoma (HCC) as the primary, most prevalent subtype. Due to the rising incidence of metabolic disorders, NAFLD has become one of the main contributing factors to HCC development. However, although NAFLD might account for about a fourth of HCC cases, there is currently a significant gap in HCC surveillance protocols regarding noncirrhotic NAFLD patients, so the majority of NAFLD-related HCC cases were diagnosed in late stages when survival chances are minimal. However, in the past decade, the focus in cancer genomics has shifted towards the noncoding part of the genome, especially on the microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), which have proved to be involved in the regulation of several malignant processes. This review aims to summarize the current knowledge regarding some of the main dysregulated, noncoding RNAs (ncRNAs) and their implications for NAFLD and HCC development. A central focus of the review is on miRNA and lncRNAs that can influence the progression of NAFLD towards HCC and how they can be used as potential screening tools and future therapeutic targets.

Molecular Advances in MAFLD—A Link between Sphingolipids and Extracellular Matrix in Development and Progression to Fibrosis

Metabolic-Associated Fatty Liver Disease (MAFLD) is a major cause of liver diseases globally and its prevalence is expected to grow in the coming decades. The main cause of MAFLD development is changed in the composition of the extracellular matrix (ECM). Increased production of matrix molecules and inflammatory processes lead to progressive fibrosis, cirrhosis, and ultimately liver failure. In addition, increased accumulation of sphingolipids accompanied by increased expression of pro-inflammatory cytokines in the ECM is closely related to lipogenesis, MAFLD development, and its progression to fibrosis. In our work, we will summarize all information regarding the role of sphingolipids e.g., ceramide and S1P in MAFLD development. These sphingolipids seem to have the most significant effect on macrophages and, consequently, HSCs which trigger the entire cascade of overproduction matrix molecules, especially type I and III collagen, proteoglycans, elastin, and also tissue inhibitors of metalloproteinases, which as a result cause the development of liver fibrosis.

Modulation of hepatic stellate cells by Mutaflor® probiotic in non-alcoholic fatty liver disease management

BACKGROUND

NAFLD and NASH are emerging as primary causes of chronic liver disease, indicating a need for an effective treatment. Mutaflor® probiotic, a microbial treatment of interest, was effective in sustaining remission in ulcerative colitis patients.

OBJECTIVE

To construct a genetic-epigenetic network linked to HSC signaling as a modulator of NAFLD/NASH pathogenesis, then assess the effects of Mutaflor^® on this network.

METHODS

First, in silico analysis was used to construct a genetic-epigenetic network linked to HSC signaling. Second, an investigation using rats, including HFHSD induced NASH and Mutaflor^® treated animals, was designed. Experimental procedures included biochemical and histopathologic analysis of rat blood and liver samples. At the molecular level, the expression of genetic (FOXA2, TEAD2, and LATS2 mRNAs) and epigenetic (miR-650, RPARP AS-1 LncRNA) network was measured by real-time PCR. PCR results were validated with immunohistochemistry (α-SMA and LATS2). Target effector proteins, IL-6 and TGF-β, were estimated by ELISA.

RESULTS

Mutaflor^® administration minimized biochemical and histopathologic alterations caused by NAFLD/NASH. HSC activation and expression of profibrogenic IL-6 and TGF-β effector proteins were reduced via inhibition of hedgehog and hippo pathways. Pathways may have been inhibited through upregulation of RPARP AS-1 LncRNA which in turn downregulated the expression of miR-650, FOXA2 mRNA and TEAD2 mRNA and upregulated LATS2 mRNA expression.

CONCLUSION

Mutaflor^® may slow the progression of NAFLD/NASH by modulating a genetic-epigenetic network linked to HSC signaling. The probiotic may be a useful modality for the prevention and treatment of NAFLD/NASH.

Advance of Serum Biomarkers and Combined Diagnostic Panels in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) affects approximately 25-30% population worldwide, which progresses from simple steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma, and has complications such as cardiovascular events. Liver biopsy is still the gold standard for the diagnosis of NAFLD, with some limitations, such as invasive, sampling deviation, and empirical judgment. Therefore, it is urgent to develop noninvasive diagnostic biomarkers. Currently, a large number of NAFLD-related serum biomarkers have been identified, including apoptosis, inflammation, fibrosis, adipokines, hepatokines, and omics biomarkers, which could effectively diagnose NASH and exclude patients with progressive fibrosis. We summarized serum biomarkers and combined diagnostic panels of NAFLD, to provide some guidance for the noninvasive diagnosis and further clinical studies.

Identify Functional lncRNAs in Nonalcoholic Fatty Liver Disease by Constructing a ceRNA Network

Aim: To identify functional long noncoding RNAs (lncRNAs) by constructing a NAFLD-related lncRNA-miRNA-mRNA network (NLMMN) based on the hypothesis that lncRNAs, as competitive endogenous RNAs (ceRNAs), are able to regulate mRNA functions by competitive binding to shared miRNAs. Methods: The "Limma R package" was used to identify differentially expressed lncRNAs and mRNAs (DElncRNAs and DEmRNAs). The "miRcode online tool" was used to predict the potential interactions between DElncRNAs or DEmRNAs using Perl, and "multiMiR R package" was used to predict the potential interactions between DElncRNAs and miRNAs. The NLMMN was viewed by Cytoscape. The DEmRNAs were further analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to identify functional lncRNAs in human liver tissue and FFAs-induced fat-overloading HepG2 cells. The role of functional lncRNA was explored in the HepG2 cell line. Results: A total of 336 DElncRNAs (154 upregulated and 182 downregulated, |log 2 (fold change) |>0.655 and P < 0.05) and 399 DEmRNAs (152 upregulated and 247 downregulated, |log 2 (fold change) |>0.608 and P < 0.05) were identified. A total of 142 DElncRNA-miRNA interaction pairs and 643 miRNA-DEmRNA interaction pairs were retained to construct the NLMMN, which contained 19 lncRNAs, 47 miRNAs, and 228 mRNAs. The results of GO and KEGG enrichment analyses were related to an extracellular matrix (ECM). Two upregulated lncRNAs (LINC00240 and RBMS3-AS3) and one downregulated lncRNA (ALG9-IT1) were identified by qRT-PCR in liver tissues. But only LINC00240 was significantly upregulated in fat-overloading HepG2 cells. Overexpression of LINC00240 did not affect lipid accumulation but increased the reactive oxygen species (ROS) content in HepG2 cells. Conclusion: LINC00240, RBMS3-AS3, and ALG9-IT1 might be novel functional lncRNAs that attenuate liver fibrosis in NAFLD by influencing the ECM through the ceRNA network. Among them, LINC00240 might have a key role.

LncRNA MALAT1 Promotes PPARα/CD36-Mediated Hepatic Lipogenesis in Nonalcoholic Fatty Liver Disease by Modulating miR-206/ARNT Axis

Long non-coding RNAs (lncRNAs) are known to play crucial roles in nonalcoholic fatty liver disease (NAFLD). This research sought to explore mechanisms by which lncRNA MALAT1 regulates the progression of NAFLD. Thus, in order to detect the function of MALAT1 in NAFLD, in vitro and in vivo model of NAFLD were established. Then, fatty acid uptake and triglyceride level were investigated by BODIPY labeled-fatty acid uptake assay and Oil red O staining, respectively. The expressions of MALAT1, miR-206, ARNT, PPARα and CD36 were detected by western blotting and qPCR. Dual luciferase, RIP and ChIP assay were used to validate the relation among MALAT1, miR-206, ARNT and PPARα. The data revealed expression of MALAT1 was up-regulated in vitro and in vivo in NAFLD, and knockdown of MALAT1 suppressed FFA-induced lipid accumulation in hepatocytes. Meanwhile, MALAT1 upregulated the expression of ARNT through binding with miR-206. Moreover, miR-206 inhibitor reversed MALAT1 knockdown effects in decreased lipid accumulation in FFA-treated hepatocytes. Furthermore, ARNT could inhibit the expression of PPARα via binding with PPARα promoter. Knockdown of MALAT1 significantly upregulated the level of PPARα and downregulated the expression of CD36, while PPARα knockdown reversed these phenomena. MALAT1 regulated PPARα/CD36 -mediated hepatic lipid accumulation in NAFLD through regulation of miR-206/ARNT axis. Thus, MALAT1/miR-206/ARNT might serve as a therapeutic target against NAFLD.

NAFLD: Mechanisms, Treatments, and Biomarkers

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-associated fatty liver disease (MAFLD), is one of the most common causes of liver diseases worldwide. NAFLD is growing in parallel with the obesity epidemic. No pharmacological treatment is available to treat NAFLD, specifically. The reason might be that NAFLD is a multi-factorial disease with an incomplete understanding of the mechanisms involved, an absence of accurate and inexpensive imaging tools, and lack of adequate non-invasive biomarkers. NAFLD consists of the accumulation of excess lipids in the liver, causing lipotoxicity that might progress to metabolic-associated steatohepatitis (NASH), liver fibrosis, and hepatocellular carcinoma. The mechanisms for the pathogenesis of NAFLD, current interventions in the management of the disease, and the role of sirtuins as potential targets for treatment are discussed here. In addition, the current diagnostic tools, and the role of non-coding RNAs as emerging diagnostic biomarkers are summarized. The availability of non-invasive biomarkers, and accurate and inexpensive non-invasive diagnosis tools are crucial in the detection of the early signs in the progression of NAFLD. This will expedite clinical trials and the validation of the emerging therapeutic treatments.

Metformin improves high‑fat diet‑induced insulin resistance in mice by downregulating the expression of long noncoding RNA NONMMUT031874.2

Metformin (MET) is the first-line therapeutic option for patients with type 2 diabetes that has garnered substantial attention over recent years. However, an insufficient number of studies have been performed to assess its effects on insulin resistance and the expression profile of long noncoding RNAs (lncRNAs). The present study divided mice into three groups: Control group, high-fat diet (HFD) group and HFD + MET group. A high-throughput sequencing analysis was conducted to detect lncRNA and mRNA expression levels, and differentially expressed lncRNAs were selected. Subsequently, the differentially expressed lncRNAs were validated both in vivo and in vitro (mouse liver AML12 cells treated with Palmitic acid) models of insulin resistance. After validating randomly selected lncRNAs via reverse transcription-quantitative PCR a novel lncRNA, NONMMUT031874.2, was identified, which was upregulated in the HFD group and reversed with MET treatment. To investigate the downstream mechanism of NONMMUT031874.2, lncRNA-microRNA (miR/miRNA)-mRNA co-expression network was constructed and NONCODE, miRBase and TargetScan databases were used, which indicated that NONMMUT031874.2 may regulate suppressor of cytokine signaling 3 by miR-7054-5p. For the in vitro part of the present study, AML12 cells were transfected with small interfering RNA to knock down NONMMUT031874.2 expression before being treated with palmitic acid (PA) and MET. The results showed that the expression of NONMMUT031874.2 was significantly increased whereas miR-7054-5p expression was significantly decreased by PA treatment. By contrast, after knocking down NONMMUT031874.2 expression or treatment with MET, the aforementioned in vitro observations were reversed. In addition, it was also found that NONMMUT031874.2 knockdown and treatment with MET exerted similar effects in alleviating insulin resistance and whilst decreasing glucose concentration in AML12 cells. These results suggest that MET treatment can ameliorate insulin resistance by downregulating NONMMUT031874.2 expression.

lncRNA MEG3 modulates hepatic stellate cell activation by sponging miR‑145 to regulate PPARγ

It is important to determine the mechanism of liver fibrosis for targeted therapy and the development of targeted therapies for liver fibrosis may offer promise for patients with liver disease. Long non‑coding RNAs (lncRNAs) serve a role in hepatic fibrosis. The lncRNA maternally expressed gene 3 (MEG3) has been confirmed to inhibit liver fibrosis. The present study investigated the role of the MEG3 in healthy patients and patients with liver fibrosis. The expression levels of MEG3 and microRNA (miR)‑145 in the serum of healthy volunteers and patients with liver fibrosis and in LX‑2 cells were detected using reverse transcription‑quantitative PCR. A dual‑luciferase reporter assay was used to determine the targeting relationship between MEG3 and miR‑145, and the targeting relationship between miR‑145 and peroxisome proliferator‑activated receptor γ (PPARγ). The protein expression levels of PPARγ, α‑smooth muscle actin (α‑SMA) and collagen I (COL1A1) were detected using western blotting. The expression levels of α‑SMA and COL1A1 were also determined using immunofluorescence. Finally, a Cell Counting Kit‑8 assay was performed to assess the proliferative ability of LX‑2 cells. A significantly reduced MEG3 expression level was demonstrated in serum from patients with liver fibrosis compared with serum from healthy controls. TGF‑β1 induced a significantly decreased MEG3 expression level in LX‑2 human hepatic stellate cells in vitro. The TGF‑β1‑induced increases in cell proliferation and α‑SMA and COL1A1 protein expression levels were reversed following MEG3 overexpression. The results also demonstrated that MEG3 sponged miR‑145 and competed endogenously with miR‑145 to regulate PPARγ. In summary, the present study identified MEG3 as an anti‑fibrotic lncRNA and provided new information regarding the role of MEG3 in liver fibrosis. MEG3 may therefore be a potential target in the treatment of liver fibrosis.

Long non‑coding RNA MBI‑52 inhibits the development of liver fibrosis by regulating the microRNA‑466g/SMAD4 signaling pathway

Liver fibrosis is a wound healing response triggered by liver injury. In severe cases, it may develop into liver cirrhosis, liver cancer and liver failure. Long non-coding RNAs (lncRNAs) play key roles in the development of liver fibrosis. The present study aimed to investigate the role of lncRNA-MBI-52 (lnc-MBI-52) in the progression of liver fibrosis. Carbon tetrachloride (CCl₄)-induced injury was performed to establish a mouse liver fibrosis model, and exogenous transforming growth factor-β1 was used to establish a hepatic stellate cell (HSC) activation model. Reverse transcription-quantitative PCR and western blot analyses were performed to detect mRNA and protein expression, respectively. RNA pull-down assay was performed to assess the interaction between microRNA (miR)-466g and lnc-MBI-52 or SMAD4. Dual-luciferase reporter assay was performed to verify the target of miR-466g. lnc-MBI-52 was overexpressed in CCl₄-induced mouse liver fibrosis models and activated HSCs. lnc-MBI-52 knockdown suppressed liver fibrosis in vitro. Moreover, knockdown of lnc-MBI-52 downregulated α-smooth muscle actin and collagen type I expression. In addition, lnc-MBI-52 and SMAD4 were identified as targets of miR-466g. The effects of lnc-MBI-52 on HSC activation were reversed following transfection with miR-466g mimics or SMAD4 knockdown. lnc-MBI-52 miR-466g significantly decreased lnc-MBI-52 expression, while overexpression of lnc-MBI-52 suppressed miR-466g expression. The results of the RNA pull-down assay confirmed the interaction between miR-466g and lnc-MBI-52. Taken together, lnc-MBI-52 induced liver fibrosis by regulating the miR-466g/SMAD4 axis, which may provide a new possible strategy for liver fibrosis.

Long noncoding RNAs associated with nonalcoholic fatty liver disease in a high cholesterol diet adult zebrafish model

The mechanism of nonalcoholic fatty liver disease (NAFLD) has not been completely revealed. In this study, we investigated the association of liver histological changes and long noncoding RNAs (lncRNAs) in the NAFLD zebrafish model. Forty zebrafish were fed a high-cholesterol diet (1.5 g per day) for 8 weeks. We measured fatty liver changes in the zebrafish liver using oil red O staining and divided them into two groups based on high and low scores. We pooled each group of zebrafish livers and identified lncRNAs, miRNAs, and mRNAs using Next-generation sequencing. Human homologs of lncRNAs were identified using ZFLNC, Ensembl, and NONCODE. We found several significant genes, including 32 lncRNAs, 5 miRNA genes, and 8 protein-coding genes, that were associated with liver metabolism and NAFLD-related functions in zebrafish. In particular, eight conserved human homologs of lncRNAs were found. We discovered the human homologs of eight lncRNA candidates from fatty liver zebrafish for the first time. The spectrum of biological mechanisms by which lncRNAs mediate their functional roles in NAFLD in a high cholesterol diet adult zebrafish model remains to be uncovered.

Association between telomere length and hepatic fibrosis in non-alcoholic fatty liver disease

Telomere length has been linked to the prevalence and progression of metabolic disease. However, clinical implications of telomere length in biopsy-proven non-alcoholic fatty liver disease (NAFLD) patients remain unclear. Therefore, this study aimed to investigate the association of telomere length with the histological severity of NAFLD. The cross-sectional data derived from the prospectively enrolled Boramae NAFLD registry (n = 91) were analyzed. The liver tissues and clinical information were obtained from both NAFLD patients and non-NAFLD subjects. Binary logistic regression was performed to identify the independent association between telomere length and the histological severity of NAFLD. A total of 83 subjects with or without biopsy-proven NAFLD were included for analysis: non-NAFLD in 23 (27.7%), non-alcoholic fatty liver in 15 (18.1%), and non-alcoholic steatohepatitis (NASH) in 45 (54.2%). Telomere length measured from liver tissues showed a strong negative correlation (p < 0.001) with age, regardless of NAFLD status. Therefore, telomere length was corrected for age. Age-adjusted telomere length than decreased gradually with an increasing severity of fibrosis in patients with NAFLD (p < 0.028). In multivariate analysis, age-adjusted telomere length (odds ratio [OR] 0.59; 95% CI 0.37–0.92; p = 0.019) and high-density lipoprotein cholesterol (OR 0.94; 95% CI 0.80–0.99; p = 0.039) were independently associated with significant fibrosis. The age-adjusted telomere length tends to decrease along with the fibrosis stage of NAFLD. In particular, among the histological components of NAFLD, fibrosis severity seems to be related to telomere length in the liver.

Identification of plasma lncRNA-ATB levels in hepatitis B virus-related cirrhosis and non-cirrhotic chronic hepatitis B patients

Long non-coding RNA-ATB (LncRNA-ATB) which is activated by transforming growth factor-β (TGF-β), is a key regulator of TGF-β signaling pathway. TGF-β plays an important role in various pathogenic processes, from inflammation and fibrosis to cirrhosis and cancer. In this study, we evaluated the plasma levels of lncRNA-ATB in patients with hepatitis B virus (HBV)-related cirrhosis and non-cirrhotic patients with chronic hepatitis B (CHB) and investigated the clinical values. Plasma samples were collected from 44 HBV-related cirrhosis patients, 45 non-cirrhotic CHB and 75 healthy controls. Briefly, after total RNA extraction and cDNA synthesis, quantitative real-time PCR (qPCR) was performed to detect plasma lncRNA-ATB levels. Results show the plasma levels of lncRNA-ATB in HBV-related cirrhosis patients were significantly higher in comparison to healthy controls (Fold change=2.60, p value=0.04). Also, we determined plasma levels of lncRNA-ATB as a specific biomarker of HBV-related cirrhosis (AUC=0.65, p value=0.03, Sensitivity 61.36%; Specificity 70.00%). In addition to, we investigated the plasma levels of lncRNA-ATB in non-cirrhotic CHB patients were significantly lower than healthy controls (Fold change= 0.33, p value=0.01). We also indicated plasma lncRNA-ATB levels were as a sensitive biomarker for diagnosis of non-cirrhotic CHB patients compared with healthy (AUC=0.66, p value=0.00, Sensitivity 71.11%; Specificity 57.78%). According to our results, circulating lncRNA-ATB has good specificity for diagnosing hepatitis B virus (HBV)-related cirrhosis and good sensitivity for diagnosis of non-cirrhotic chronic hepatitis B (CHB) patients.

Non-Coding RNAs: Novel Players in Insulin Resistance and Related Diseases

The rising prevalence of metabolic diseases related to insulin resistance (IR) have stressed the urgent need of accurate and applicable tools for early diagnosis and treatment. In the last decade, non-coding RNAs (ncRNAs) have gained growing interest because of their potential role in IR modulation. NcRNAs are variable-length transcripts which are not translated into proteins but are involved in gene expression regulation. Thanks to their stability and easy detection in biological fluids, ncRNAs have been investigated as promising diagnostic and therapeutic markers in metabolic diseases, such as type 2 diabetes mellitus (T2D), obesity and non-alcoholic fatty liver disease (NAFLD). Here we review the emerging role of ncRNAs in the development of IR and related diseases such as obesity, T2D and NAFLD, and summarize current evidence concerning their potential clinical application.

Role of long non-coding RNAs in adipogenesis: State of the art and implications in obesity and obesity-associated diseases

Obesity is an evolutionary, chronic, and relapsing disease that consists of a pathological accumulation of adipose tissue able to increase morbidity for high blood pressure, type 2 diabetes, metabolic syndrome, and obstructive sleep apnea in adults, children, and adolescents. Despite intense research over the last 20 years, obesity remains today a disease with a complex and multifactorial etiology. Recently, long non-coding RNAs (lncRNAs) are emerging as interesting new regulators as different lncRNAs have been found to play a role in early and late phases of adipogenesis and to be implicated in obesity-associated complications onset. In this review, we discuss the most recent advances on the role of lncRNAs in adipocyte biology and in obesity-associated complications. Indeed, more and more researchers are focusing on investigating the underlying roles that these molecular modulators could play. Even if a significant number of evidence is correlation-based, with lncRNAs being differentially expressed in a specific disease, recent works are now focused on deeply analyzing how lncRNAs can effectively modulate the disease pathogenesis onset and progression. LncRNAs possibly represent new molecular markers useful in the future for both the early diagnosis and a prompt clinical management of patients with obesity.

Review on Biological Characteristics of Kv1.3 and Its Role in Liver Diseases

The liver accounts for the largest proportion of macrophages in all solid organs of the human body. Liver macrophages are mainly composed of cytolytic cells inherent in the liver and mononuclear macrophages recruited from the blood. Monocytes recruitment occurs mainly in the context of liver injury and inflammation and can be recruited into the liver and achieve a KC-like phenotype. During the immune response of the liver, macrophages/KC cells release inflammatory cytokines and infiltrate into the liver, which are considered to be the common mechanism of various liver diseases in the early stage. Meanwhile, macrophages/KC cells form an interaction network with other liver cells, which can affect the occurrence and progression of liver diseases. From the perspective of liver disease treatment, knowing the full spectrum of macrophage activation, the underlying molecular mechanisms, and their implication in either promoting liver disease progression or repairing injured liver tissue is highly relevant from a therapeutic point of view. Kv1.3 is a subtype of the voltage-dependent potassium channel, whose function is closely related to the regulation of immune cell function. At present, there are few studies on the relationship between Kv1.3 and liver diseases, and the application of its blockers as a potential treatment for liver diseases has not been reported. This manuscript reviewed the physiological characteristics of Kv1.3, the relationship between Kv1.3 and cell proliferation and apoptosis, and the role of Kv1.3 in a variety of liver diseases, so as to provide new ideas and strategies for the prevention and treatment of liver diseases. In short, by understanding the role of Kv1.3 in regulating the functions of immune cells such as macrophages, selective blockers of Kv1.3 or compounds with similar functions can be applied to alleviate the progression of liver diseases and provide new ideas for the prevention and treatment of liver diseases.

Role of 2‑series prostaglandins in the pathogenesis of type 2 diabetes mellitus and non‑alcoholic fatty liver disease (Review)

Nowadays, metabolic syndromes are emerging as global epidemics, whose incidence are increasing annually. However, the efficacy of therapy does not increase proportionately with the increased morbidity. Type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD) are two common metabolic syndromes that are closely associated. The pathogenic mechanisms of T2DM and NAFLD have been studied, and it was revealed that insulin resistance, hyperglycemia, hepatic lipid accumulation and inflammation markedly contribute to the development of these two diseases. The 2-series prostaglandins (PGs), a subgroup of eicosanoids, including PGD₂, PGE₂, PGF_2α and PGI₂, are converted from arachidonic acid catalyzed by the rate-limiting enzymes cyclooxygenases (COXs). Considering their wide distribution in almost every tissue, 2-series PG pathways exert complex and interlinked effects in mediating pancreatic β-cell function and proliferation, insulin sensitivity, fat accumulation and lipolysis, as well as inflammatory processes. Previous studies have revealed that metabolic disturbances, such as hyperglycemia and hyperlipidemia, can be improved by treatment with COX inhibitors. At present, an accumulating number of studies have focused on the roles of 2-series PGs and their metabolites in the pathogenesis of metabolic syndromes, particularly T2DM and NAFLD. In the present review, the role of 2-series PGs in the highly intertwined pathogenic mechanisms of T2DM and NAFLD was discussed, and important therapeutic strategies based on targeting 2-series PG pathways in T2DM and NAFLD treatment were provided.

Cell-free DNA and RNA-measurement and applications in clinical diagnostics with focus on metabolic disorders

Circulating cell-free DNA (cfDNA) and RNA (cfRNA) hold enormous potential as a new class of biomarkers for the development of noninvasive liquid biopsies in many diseases and conditions. In recent years, cfDNA and cfRNA have been studied intensely as tools for noninvasive prenatal testing, solid organ transplantation, cancer screening, and monitoring of tumors. In obesity, higher cfDNA concentration indicates accelerated cellular turnover of adipocytes during expansion of adipose mass and may be directly involved in the development of adipose tissue insulin resistance by inducing inflammation. Furthermore, cfDNA and cfRNA have promising diagnostic value in a range of obesity-related metabolic disorders, such as nonalcoholic fatty liver disease, type 2 diabetes, and diabetic complications. Here, we review the current and future applications of cfDNA and cfRNA within clinical diagnostics, discuss technical and analytical challenges in the field, and summarize the opportunities of using cfDNA and cfRNA in the diagnostics and prognostics of obesity-related metabolic disorders.

Evolutionary conservation of long non-coding RNAs in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of conditions ranging from hepatic steatosis to steatohepatitis (NASH) to fibrosis in the absence of alcohol consumption. Its pathogenesis involves both genetic and environmental factors with a multitude of underlying molecular mechanisms and mediators at each stage. Recent transcriptomic-based studies have led to the identification and association of long non-coding RNAs (lncRNAs) with disease pathology in NAFLD patients and in vivo rodent models. However, the knowledge of function of most of the lncRNAs in NAFLD pathology remains obscure. In the current review, we give a comprehensive catalogue of well reported lncRNAs in NAFLD and classify them using sequence and synteny-based evolutionary conservation across rodents, nonhuman primate and human species. The conserved lncRNAs across all the three species may be dissected in larger clinical studies of NAFLD and can be explored as biomarkers and therapeutic targets. In addition, we also review and analyse single nucleotide polymorphisms (SNPs) in these lncRNAs. It adds another facet to the regulatory role of NAFLD-associated lncRNAs and underscores the significance of a novel genetic landscape of non-coding genome in determining the genetic susceptibility of NAFLD.

Non-coding RNA Associated Competitive Endogenous RNA Regulatory Network: Novel Therapeutic Approach in Liver Fibrosis

Liver fibrosis or scarring is the most common pathological feature caused by chronic liver injury, and is widely considered one of the primary causes of morbidity and mortality. It is primarily characterised by hepatic stellate cells (HSC) activation and excessive extracellular matrix (ECM) protein deposition. Overwhelming evidence suggests that the dysregulation of several noncoding RNAs (ncRNAs), mainly long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) contributes to the activation of HSC and progression of liver fibrosis. These ncRNAs not only bind to their target genes for the development and regression of liver fibrosis but also act as competing endogenous RNAs (ceRNAs) by sponging with miRNAs to form signaling cascades. Among these signaling cascades, lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA are critical modulators for the initiation, progression, and regression of liver fibrosis. Thus, targeting these interacting ncRNA cascades can serve as a novel and potential therapeutic target for inhibition of HSC activation and prevention and regression of liver fibrosis.

Genetics and epigenetics purpose in nonalcoholic fatty liver disease

INTRODUCTION

nonalcoholic fatty liver disease (NAFLD) comprises a broad spectrum of diseases, which can progress from benign steatosis to nonalcoholic steatohepatitis, liver cirrhosis and hepatocellular carcinoma. NAFLD is the most common chronic liver disease in developed countries, affecting approximately 25% of the general population. Insulin resistance, adipose tissue dysfunction, mitochondrial and endoplasmic reticulum stress, chronic inflammation, genetic and epigenetic factors are NAFLD triggers that control the disease susceptibility and progression.

AREAS COVERED

In recent years a large number of investigations have been carried out to elucidate genetic and epigenetic factors in the disease pathogenesis, as well as the search for diagnostic markers and therapeutic targets. This paper objective is to report the most studied genetic and epigenetic variants around NAFLD.

EXPERT OPINION

NAFLD lead to various comorbidities, which have a considerable impact on the patient wellness and life quality, as well as on the costs they generate for the country's health services. It is essential to continue with molecular research, since it could be used as a clinical tool for prognosis and disease severity. Specifically, in the field of hepatology, plasma miRNAs could provide a novel tool in liver diseases diagnosis and monitoring, representing an alternative to invasive diagnostic procedures.

Differentially expressed mRNAs and lncRNAs shared between activated human hepatic stellate cells and nash fibrosis

We previously reported dysregulated expression of liver-derived messenger RNA (mRNA) and long noncoding RNA (lncRNA) in patients with advanced fibrosis resulting from nonalcoholic fatty liver disease (NAFLD). Here we sought to identify changes in mRNA and lncRNA levels associated with activation of hepatic stellate cells (HSCs), the predominant source of extracellular matrix production in the liver and key to NAFLD-related fibrogenesis. We performed expression profiling of mRNA and lncRNA from LX-2 cells, an immortalized human HSC cell line, treated to induce phenotypes resembling quiescent and myofibroblastic states. We identified 1964 mRNAs (1377 upregulated and 587 downregulated) and 1460 lncRNAs (665 upregulated and 795 downregulated) showing statistically significant evidence (FDR ≤0.05) for differential expression (fold change ≥|2|) between quiescent and activated states. Pathway analysis of differentially expressed genes showed enrichment for hepatic fibrosis (FDR = 1.35E-16), osteoarthritis (FDR = 1.47E-14), and axonal guidance signaling (FDR = 1.09E-09). We observed 127 lncRNAs/nearby mRNA pairs showing differential expression, the majority of which were dysregulated in the same direction. A comparison of differentially expressed transcripts in LX-2 cells with RNA-sequencing results from NAFLD patients with or without liver fibrosis revealed 1047 mRNAs and 91 lncRNAs shared between the two datasets, suggesting that some of the expression changes occurring during HSC activation can be observed in biopsied human tissue. These results identify lncRNA and mRNA expression patterns associated with activated human HSCs that appear to recapitulate human NAFLD fibrosis.

Identification of long non-coding RNA SCARNA9L as a novel molecular target for colorectal cancer

The aim of the present study was to analyze the microarray data of human colorectal cancer (CRC) tissues and identify novel therapeutic targets for CRC. Microarray analysis from the GSE73360 and GSE84984 datasets was performed to identify novel long non-coding RNAs (lncRNAs) that were differentially expressed in human CRC tissues. Additionally, small interfering RNAs were used to deplete the expression of the indicated lncRNAs in cells. Colony-formation, wound-closure, and transwell assays were performed on CRC cells to assess their proliferation and migration capacities. Through microarray analysis, SCARNA9L, SLMO2-ATP5E and LOC100132062 were identified as differentially expressed lncRNAs in CRC tissues. The present study demonstrated that the ablation of SCARNA9L inhibited cell proliferation and arrested the cell cycle of SW480 and SW620 CRC cells. Additionally, depletion of SCARNA9L restrained the migration of CRC cells in vitro. Overall, the present study investigated the potential involvement of SCARNA9L in CRC and suggests SCARNA9L as a potential biomarker.

LncRNAs Act as a Link between Chronic Liver Disease and Hepatocellular Carcinoma

Long non-coding RNAs (lncRNAs) are emerging as important contributors to the biological processes underlying the pathophysiology of various human diseases, including hepatocellular carcinoma (HCC). However, the involvement of these molecules in chronic liver diseases, such as nonalcoholic fatty liver disease (NAFLD) and viral hepatitis, has only recently been considered in scientific research. While extensive studies on the pathogenesis of the development of HCC from hepatic fibrosis have been conducted, their regulatory molecular mechanisms are still only partially understood. The underlying mechanisms related to lncRNAs leading to HCC from chronic liver diseases and cirrhosis have not yet been entirely elucidated. Therefore, elucidating the functional roles of lncRNAs in chronic liver disease and HCC can contribute to a better understanding of the molecular mechanisms, and may help in developing novel diagnostic biomarkers and therapeutic targets for HCC, as well as in preventing the progression of chronic liver disease to HCC. Here, we comprehensively review and briefly summarize some lncRNAs that participate in both hepatic fibrosis and HCC.

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.