Altered expression of MALAT1 lncRNA in nonalcoholic steatohepatitis fibrosis regulates CXCL5 in hepatic stellate cells

Concomitant NAFLD Facilitates Liver Metastases and PD-1-Refractory by Recruiting MDSCs via CXCL5/CXCR2 in Colorectal Cancer

BACKGROUND & AIMS

Both nonalcoholic fatty liver disease (NAFLD) and colorectal cancer (CRC) are prevalent worldwide. The effects of concomitant NAFLD on the risk of colorectal liver metastasis (CRLM) and its mechanisms have not been definitively elucidated.

METHODS

We observed the effect of concomitant NAFLD on CRLM in the mouse model and explored the underlying mechanisms of specific myeloid-derived suppressor cells (MDSCs) recruitment and then tested the therapeutic application based on the mechanisms. Finally we validated our findings in the clinical samples.

RESULTS

Here we prove that in different mouse models, NAFLD induces F4/80+ Kupffer cells to secret chemokine CXCL5 and then recruits CXCR2+ MDSCs to promote the growth of CRLM. CRLM with NAFLD background is refractory to the anti-PD-1 monoclonal antibody treatment, but when combined with Reparixin, an inhibitor of CXCR1/2, dual therapy cures the established CRLM in mice with NAFLD. Our clinical studies also indicate that fatty liver diseases increase the infiltration of CXCR2+ MDSCs, as well as the hazard of liver metastases in CRC patients.

CONCLUSIONS

Collectively, our findings highlight the significance of selective CXCR2+/CD11b+/Gr-1+ subset myeloid cells in favoring the development of CRLM with NAFLD background and identify a pharmaceutical medicine that is already available for the clinical trials and potential treatment.

Two sides of the same coin: Non-alcoholic fatty liver disease and atherosclerosis

The prevalence of non-alcoholic fatty liver disease (NAFLD) and atherosclerosis remain high, which is primarily due to widespread adoption of a western diet and sedentary lifestyle. NAFLD, together with advanced forms of this disease such as non-alcoholic steatohepatitis (NASH) and cirrhosis, are closely associated with atherosclerotic-cardiovascular disease (ASCVD). In this review, we discussed the association between NAFLD and atherosclerosis and expounded on the common molecular biomarkers underpinning the pathogenesis of both NAFLD and atherosclerosis. Furthermore, we have summarized the mode of function and potential clinical utility of existing drugs in the context of these diseases.

Investigating the Role of Non-Coding RNA in Non-Alcoholic Fatty Liver Disease

Non-coding RNAs (ncRNAs) are RNA molecules that do not code for protein but play key roles in regulating cellular processes. NcRNAs globally affect gene expression in diverse physiological and pathological contexts. Functionally important ncRNAs act in chromatin modifications, in mRNA stabilization and translation, and in regulation of various signaling pathways. Non-alcoholic fatty liver disease (NAFLD) is a set of conditions caused by the accumulation of triacylglycerol in the liver. Studies of ncRNA in NAFLD are limited but have demonstrated that ncRNAs play a critical role in the pathogenesis of NAFLD. In this review, we summarize NAFLD's pathogenesis and clinical features, discuss current treatment options, and review the involvement of ncRNAs as regulatory molecules in NAFLD and its progression to non-alcoholic steatohepatitis (NASH). In addition, we highlight signaling pathways dysregulated in NAFLD and review their crosstalk with ncRNAs. Having a thorough understanding of the disease process's molecular mechanisms will facilitate development of highly effective diagnostic and therapeutic treatments. Such insights can also inform preventive strategies to minimize the disease's future development.

A narrative review: CXC chemokines influence immune surveillance in obesity and obesity-related diseases: Type 2 diabetes and nonalcoholic fatty liver disease

Adipose tissue develops lipids, aberrant adipokines, chemokines, and pro-inflammatory cytokines as a consequence of the low-grade systemic inflammation that characterizes obesity. This low-grade systemic inflammation can lead to insulin resistance (IR) and metabolic complications, such as type 2 diabetes (T2D) and nonalcoholic fatty liver disease (NAFLD). Although the CXC chemokines consists of numerous regulators of inflammation, cellular function, and cellular migration, it is still unknown that how CXC chemokines and chemokine receptors contribute to the development of metabolic diseases (such as T2D and NAFLD) during obesity. In light of recent research, the objective of this review is to provide an update on the linkage between the CXC chemokine, obesity, and obesity-related metabolic diseases (T2D and NAFLD). We explore the differential migratory and immunomodulatory potential of CXC chemokines and their mechanisms of action to better understand their role in clinical and laboratory contexts. Besides that, because CXC chemokine profiling is strongly linked to leukocyte recruitment, macrophage recruitment, and immunomodulatory potential, we hypothesize that it could be used to predict the therapeutic potential for obesity and obesity-related diseases (T2D and NAFLD).

Transcriptional regulation of Glis2 in hepatic fibrosis

The role of Gli-similar 2 (Glis2) in hepatic fibrosis (HF) is controversial. In this study, we focused on the functional and molecular mechanisms involved in the Glis2-mediated activation of hepatic stellate cells (HSCs)-a milestone event leading to HF. The expression levels of Glis2 mRNA and protein were significantly decreased in the liver tissues of patients with severe HF and in mouse fibrotic liver tissues as well as HSCs activated by TGFβ1. Functional studies indicated that upregulated Glis2 significantly inhibited HSC activation and alleviated BDL-induced HF in mice. Downregulation of Glis2 was found to correlate significantly with DNA methylation of the Glis2 promoter mediated by methyltransferase 1 (DNMT1), which restricted the binding of hepatic nuclear factor 1-α (HNF1-α), a liver-specific transcription factor, to Glis2 promoters. In addition, the enrichment of DNMT1 in the Glis2 promoter region was mediated by metastasis-associated lung adenocarcinoma transcriptor-1 (MALAT1) lncRNA, leading to transcriptional silencing of Glis2 and activation of HSCs. In conclusion, our findings reveal that the upregulation of Glis2 can maintain the resting state of HSCs. The decreased expression of Glis2 under pathological conditions may lead to the occurrence and development of HF with the expression silencing of DNA methylation mediated by MALAT1 and DNMT1.

The challenging role of micro-RNAs in non-alcoholic fatty liver disease in children with obesity: is it time for a new era?

INTRODUCTION

As the pediatric obesity epidemic, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in childhood. Pediatric NAFLD pathophysiology is tangled and still unclear, but insulin resistance (IR), genetics, epigenetics, oxidative stress, and inflammation act as key players. Due to the increased cardiometabolic risk of these patients, several biomarkers have been proposed for early NAFLD identification, but their clinical utility is poor. Recently, hepatic dysregulation of microRNAs (miRNAs) has been linked to metabolic dysfunction, which in turn implied in NAFLD development. Evidence on the intriguing role of miRNAs in NAFLD pathogenesis has emerging especially in at-risk children such as those with obesity. However, pediatric evidence supporting their potential use as early noninvasive NAFLD tools is still limited but promising.

AREAS COVERED

We provided an overview on the emerging role of miRNAs in pediatric NAFLD by addressing some issues regarding their pathophysiological link with the metabolic milieu and their role as reliable NAFLD markers in children with obesity.

EXPERT OPINION

Strong evidence supports a potential role of miRNAs as early biomarkers of NAFLD in children with obesity. They might represent a valid diagnostic and targeted therapeutic tool due to its close pathogenic link with the metabolic milieu.

The impact and role of identified long noncoding RNAs in nonalcoholic fatty liver disease: A narrative review

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide, but its mechanism and pathophysiology remain unclear. Long noncoding RNAs (lncRNAs) may exert a vital influence on regulating various biological functions in NAFLD.

METHODS

The databases such as Google Scholar, PubMed, and Medline were searched using the following keywords: nonalcoholic fatty liver disease, nonalcoholic fatty liver disease, NAFLD, nonalcoholic steatohepatitis, nonalcoholic steatohepatitis, NASH, long noncoding RNAs, and lncRNAs. Considering the titles and abstracts, unrelated studies were excluded. The authors evaluated the full texts of the remaining studies.

RESULTS

We summarized the current knowledge of lncRNAs and the main signaling pathways of lncRNAs involved in NAFLD explored in recent years. As a heterogeneous group of noncoding RNAs (ncRNAs), lncRNAs play crucial roles in biological processes underlying the pathophysiology of NAFLD. The mechanisms, particularly those associated with the regulation of the expression and activities of lncRNAs, play important roles in NAFLD.

CONCLUSION

A better comprehension of the mechanism controlled by lncRNAs in NAFLD is necessary for the identification of novel therapeutic targets for drug development and improved, noninvasive methods for diagnosis.

The role of long non-coding RNAs in the development of adipose cells

In recent times, the rising prevalence of obesity and its associated comorbidities have had a severe impact on human health and social progress. Therefore, scientists are delving deeper into the pathogenesis of obesity, exploring the role of non-coding RNAs. Long non-coding RNAs (lncRNAs), once regarded as mere "noise" during genome transcription, have now been confirmed through numerous studies to regulate gene expression and contribute to the occurrence and progression of several human diseases. LncRNAs can interact with protein, DNA, and RNA, respectively, and participate in regulating gene expression by modulating the levels of visible modification, transcription, post-transcription, and biological environment. Increasingly, researchers have established the involvement of lncRNAs in regulating adipogenesis, development, and energy metabolism of adipose tissue (white and brown fat). In this article, we present a literature review of the role of lncRNAs in the development of adipose cells.

LncRNA and circRNA in Patients with Non-Alcoholic Fatty Liver Disease: A Systematic Review

Non-alcoholic fatty liver disease (NAFLD) is currently the most common cause of chronic liver disease worldwide. Early identification and prompt treatment are critical to optimize patient management and improve long-term prognosis. Long non-coding RNA (lncRNA) and circular RNA (circRNA) are recently emerging non-coding RNAs, and are highly stable and easily detected in the circulation, representing a promising non-invasive approach for predicting NAFLD. A literature search of the Pubmed, Embase, Web of Science, and Cochrane Library databases was performed and 36 eligible studies were retrieved, including 18 on NAFLD, 13 on nonalcoholic steatohepatitis (NASH), and 11 on fibrosis and/or cirrhosis. Dynamic changes in lncRNA expression were associated with the occurrence and progression of NAFLD, among which lncRNA NEAT1, MEG3, and MALAT1 exhibited great potential as biomarkers for NAFLD. Moreover, mitochondria-located circRNA SCAR can drive metaflammation and its inhibition might be a promising therapeutic target for NASH. In this systematic review, we highlight the great potential of lncRNA/circRNA for early diagnosis and progression assessment of NAFLD. To further verify their clinical value, large-cohort studies incorporating lncRNA and circRNA expression both in liver tissue and blood should be conducted. Additionally, detailed studies on the functional mechanisms of NEAT1, MEG3, and MALAT1 will be essential for elucidating their roles in diagnosing and treating NAFLD, NASH, and fibrosis.

Epigenetic regulation in metabolic diseases: mechanisms and advances in clinical study

Epigenetics regulates gene expression and has been confirmed to play a critical role in a variety of metabolic diseases, such as diabetes, obesity, non-alcoholic fatty liver disease (NAFLD), osteoporosis, gout, hyperthyroidism, hypothyroidism and others. The term 'epigenetics' was firstly proposed in 1942 and with the development of technologies, the exploration of epigenetics has made great progresses. There are four main epigenetic mechanisms, including DNA methylation, histone modification, chromatin remodelling, and noncoding RNA (ncRNA), which exert different effects on metabolic diseases. Genetic and non-genetic factors, including ageing, diet, and exercise, interact with epigenetics and jointly affect the formation of a phenotype. Understanding epigenetics could be applied to diagnosing and treating metabolic diseases in the clinic, including epigenetic biomarkers, epigenetic drugs, and epigenetic editing. In this review, we introduce the brief history of epigenetics as well as the milestone events since the proposal of the term 'epigenetics'. Moreover, we summarise the research methods of epigenetics and introduce four main general mechanisms of epigenetic modulation. Furthermore, we summarise epigenetic mechanisms in metabolic diseases and introduce the interaction between epigenetics and genetic or non-genetic factors. Finally, we introduce the clinical trials and applications of epigenetics in metabolic diseases.

Epidemiologic, Genetic, Pathogenic, Metabolic, Epigenetic Aspects Involved in NASH-HCC: Current Therapeutic Strategies

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and is the sixth most frequent cancer in the world, being the third cause of cancer-related deaths. Nonalcoholic steatohepatitis (NASH) is characterized by fatty infiltration, oxidative stress and necroinflammation of the liver, with or without fibrosis, which can progress to advanced liver fibrosis, cirrhosis and HCC. Obesity, metabolic syndrome, insulin resistance, and diabetes exacerbates the course of NASH, which elevate the risk of HCC. The growing prevalence of obesity are related with increasing incidence of NASH, which may play a growing role in HCC epidemiology worldwide. In addition, HCC initiation and progression is driven by reprogramming of metabolism, which indicates growing appreciation of metabolism in the pathogenesis of this disease. Although no specific preventive pharmacological treatments have recommended for NASH, dietary restriction and exercise are recommended. This review focuses on the molecular connections between HCC and NASH, including genetic and risk factors, highlighting the metabolic reprogramming and aberrant epigenetic alterations in the development of HCC in NASH. Current therapeutic aspects of NASH/HCC are also reviewed.

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.

Inflammatory signaling on cytochrome P450-mediated drug metabolism in hepatocytes

Cytochrome P450 (CYP450) enzymes are membrane-bound blood proteins that are vital to drug detoxification, cell metabolism, and homeostasis. CYP450s belonging to CYP families 1-3 are responsible for nearly 80% of oxidative metabolism and complete elimination of approximately 50% of all common clinical drugs in humans liver hepatocytes. CYP450s can affect the body's response to drugs by altering the reaction, safety, bioavailability, and toxicity. They can also regulate metabolic organs and the body's local action sites to produce drug resistance through altered drug metabolism. Genetic polymorphisms in the CYP gene alone do not explain ethnic and individual differences in drug efficacy in the context of complex diseases. The purpose of this review is to summarize the impact of new inflammatory-response signaling pathways on the activity and expression of CYP drug-metabolizing enzymes. Included is a summary of recent studies that have identified drugs with the potential to regulate drug-metabolizing enzyme activity. Our goal is to inspire the development of clinical drug treatment processes that consider the impact of the inflammatory environment on drug treatment, as well as provide research targets for those studying drug metabolism.

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

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

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

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

Serum non-coding RNAs for diagnosis and stage of liver fibrosis

Background

All chronic liver diseases could lead to liver fibrosis. Accurate diagnosis and stage of fibrosis were important for the medical determination, management, and therapy. Liver biopsy was considered to be the gold criteria of fibrosis diagnosis. However, liver biopsy was an invasive method with some drawbacks. Non‐invasive tests for liver fibrosis included radiologic method and serum‐based test. Radiologic examination was influenced by obesity, cost, and availability. Serum‐based test was widely used in the screening and diagnostic of liver fibrosis. However, the accuracy was still needed to be improved.

Methods

Recent studies showed serum non‐coding RNAs: microRNA, long non‐coding RNA(lncRNA), and circular RNA(circRNA), which have the potentiality to be non‐invasive markers for liver fibrosis. The recent progress was summarized in this review.

Results

These studies showed serum non‐coding RNAs exerted a good diagnostic performance for liver fibrosis. A panel that included several non‐coding RNAs could increase the accuracy of single marker.

Conclusions

Serum microRNAs, lncRNAs, and circRNAs could be potential non‐invasive markers for diagnosis and stage of liver fibrosis. More high‐quality clinical study is needed for further research.

Long noncoding RNA GAS5 inhibits LX-2 cells activation by suppressing NF-κB signalling through regulation of the miR-433-3p/TLR10 axis

BACKGROUND

Liver fibrosis is a common disease that can lead to hepatic failure.

AIMS

Our aims were to reveal the role of GAS5 in the regulation of liver fibrosis.

METHODS

LX-2 human hepatic satellite cells (HSCs) were cultured and activated using TGF-β1 treatment. A CCK-8 assay was performed to assess cell viability. A luciferase assay was employed to monitor the interactions between miR-433-3p and GAS5 or toll-like receptor 10 (TLR10). Western blotting and real-time quantitative PCR (RT-qPCR) were applied to detect the expression levels of α-SMA, Col. I, PCNA-, MMP2-, MMP9-, TLR10-, and NF-κB-related molecules at the protein and RNA levels.

RESULTS

GAS5 and TLR10 were decreased while miR-433-3p was upregulated in TGF-β1-activated LX-2 cells. Upregulation of GAS5 or downregulation of miR-433-3p suppressed HSC activation, and luciferase assays indicated that miR-433-3p binds with GAS5 and the 3'-UTR of TLR10. MiR-433-3p upregulation and TLR10 downregulation rescued the impacts of GAS5 overexpression or miR-433-3p knockdown on LX-2 cells. Upregulation of GAS5 also suppressed the phosphorylation of NF-κB through the miR-433-3p/TLR10 axis.

CONCLUSION

LncRNA GAS5 exerts an inhibitory effect on HSC activation by suppressing NF-κB signalling through regulation of the miR-433-3p/TLR10 axis.

Long non-coding RNA-EN_181 potentially contributes to the protective effects of N-acetylcysteine against non-alcoholic fatty liver disease in mice

N-acetylcysteine (NAC) possesses a strong capability to ameliorate high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) in mice, but the underlying mechanism is still unknown. Our study aimed to clarify the involvement of long non-coding RNA (lncRNA) in the beneficial effects of NAC on HFD-induced NAFLD. C57BL/6J mice were fed a normal-fat diet (10 % fat), a HFD (45 % fat) or a HFD plus NAC (2 g/l). After 14-week of intervention, NAC rescued the deleterious alterations induced by HFD, including the changes in body and liver weights, hepatic TAG, plasma alanine aminotransferase, plasma aspartate transaminase and liver histomorphology (haematoxylin and eosin and Oil red O staining). Through whole-transcriptome sequencing, 52 167 (50 758 known and 1409 novel) hepatic lncRNA were detected. Our cross-comparison data revealed the expression of 175 lncRNA was changed by HFD but reversed by NAC. Five of those lncRNA, lncRNA-NONMMUT148902·1 (NO_902·1), lncRNA-XR_001781798·1 (XR_798·1), lncRNA-NONMMUT141720·1 (NO_720·1), lncRNA-XR_869907·1 (XR_907·1), and lncRNA-ENSMUST00000132181 (EN_181), were selected based on an absolute log2 fold change value of greater than 4, P-value < 0·01 and P-adjusted value < 0·01. Further qRT-PCR analysis showed the levels of lncRNA-NO_902·1, lncRNA-XR_798·1, and lncRNA-EN_181 were decreased by HFD but restored by NAC, consistent with the RNA sequencing. Finally, we constructed a ceRNA network containing lncRNA-EN_181, 3 miRNA, and 13 mRNA, which was associated with the NAC-ameliorated NAFLD. Overall, lncRNA-EN_181 might be a potential target in NAC-ameliorated NAFLD. This finding enhanced our understanding of the biological mechanisms underlying the beneficial role of NAC.

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.

Long Noncoding RNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 in Extracellular Vesicles Promotes Hepatic Stellate Cell Activation, Liver Fibrosis and β-Catenin Signaling Pathway

Evidence shows that the long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (Lnc-MALAT1) is associated with activation of hepatic stellate cells (HSCs) and liver fibrosis in animal and in vitro studies. However, its roles in human liver fibrosis and the underlying mechanism in HSC activation are not yet defined. In our current study, the expression of Lnc-MALAT1 in the fibrotic liver tissues and in the plasma extracelllar vesicles (EVs) of liver fibrosis patients was detected by FISH and qRT-PCR. The results revealed that enhanced expression of Lnc-MALAT1 was co-localized with increased expression of the fibrotic markers (collagen I and α-SMA) and the Wnt/β-catenin signaling proteins (β-catenin, cyclinD1 and c-myc) in the fibrotic liver tissues. The level of Lnc-MALAT1 in the plasma EVs isolated from 60 liver fibrosis patients was significantly increased compared with that of the 46 control patients, and area under receiver operating curve (AUROC) analysis showed that plasma EVs-Lnc-MALAT1 was a potential diagnostic marker for liver fibrosis, especially for high liver fibrosis. Plasma EVs with highly expressed Lnc-MALAT1 derived from high liver fibrosis patients up-regulated the expression of the fibrotic markers and enhanced the Wnt/β-catenin signaling in human hepatic stellate cells LX-2, and the fibrogenic effects in LX-2 were inhibited by Lnc-MALAT1 knock-down. Interestingly, TGF-β1, a potent pro-fibrotic cytokine, promoted the expression of Lnc-MALAT1 in LX-2 and its pro-fibrotic effects were also abolished by siRNA for Lnc-MALAT1, suggesting that Lnc-MALAT1 probably functions as a common mediator in the activation and fibrogenesis of HSCs. Our results indicate that enhanced expression of Lnc-MALAT1 in the fibrotic liver stimulate the activation of HSCs and thus promote their fibrogenic activity. These results also provide evidences that Lnc-MALAT1 is a potential therapeutic target and plasma EVs-Lnc-MALAT1 is a potential diagnostic biomarker for liver fibrosis.

Long Non-coding RNA MALAT1: A Key Player in Liver Diseases

Long non-coding RNAs (lncRNAs) exceed 200 nucleotides in length are considered to be involved in both developmental processes and various diseases. Here, we focus on lncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1), which was one of the most important lncRNAs in proliferation, apoptosis, and migration. MALAT1 plays a regulatory role in liver diseases, including hepatic fibrosis, liver regeneration, liver cancer, and fatty liver diseases. In the current review, we summarize the latest literature about the function roles of MALAT1 in liver disorders. Probing the regulatory mechanism and cross talk of MALAT1 with other signaling pathways of pathological processes would improve the prognosis, diagnosis of liver diseases, and offer a promising candidate target for therapeutic interventions.

Update on genetics and epigenetics in metabolic associated fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is becoming the most frequent chronic liver disease worldwide. Metabolic (dysfunction) associated fatty liver disease (MAFLD) is suggested to replace the nomenclature of NAFLD. For individuals with metabolic dysfunction, multiple NAFLD-related factors also contribute to the development and progression of MAFLD including genetics and epigenetics. The application of genome-wide association study (GWAS) and exome-wide association study (EWAS) uncovers single-nucleotide polymorphisms (SNPs) in MAFLD. In addition to the classic SNPs in PNPLA3, TM6SF2, and GCKR, some new SNPs have been found recently to contribute to the pathogenesis of liver steatosis. Epigenetic factors involving DNA methylation, histone modifications, non-coding RNAs regulations, and RNA methylation also play a critical role in MAFLD. DNA methylation is the most reported epigenetic modification. Developing a non-invasion biomarker to distinguish metabolic steatohepatitis (MASH) or liver fibrosis is ongoing. In this review, we summarized and discussed the latest progress in genetic and epigenetic factors of NAFLD/MAFLD, in order to provide potential clues for MAFLD treatment.

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.

Bioinformatics-Based Analysis of lncRNA-mRNA Interaction Network of Mild Hepatic Encephalopathy in Cirrhosis

Backgrounds

Serum long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) interaction network was discovered to exert an important role in liver cirrhosis while little is known in mild hepatic encephalopathy (MHE). Therefore, we aim to systematically evaluate the serum lncRNA-mRNA network and its regulatory mechanism in MHE.

Methods

The data of serum mRNAs and lncRNAs were derived from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were calculated between 11 cirrhotic patients with and without MHE. Next, the biological functions and underlined pathways of DEGs were determined through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Finally, an interactive network between lncRNAs and mRNAs was built, and hub genes were identified, respectively.

Results

A total of 64 differentially expressed lncRNAs (dif-lncRNAs) were found between patients with and without MHE, including 30 up- and 34 downregulated genes. 187 differentially expressed mRNAs (dif-mRNAs) were identified, including 84 up- and 103 downregulated genes. Functional enrichment analysis suggested that the regulatory pathways involved in MHE mainly consisted of a series of immune and inflammatory responses. Several hub mRNAs involved in regulatory network were identified, including CCL5, CCR5, CXCR3, CD274, STAT1, CXCR6, and EOMES. In addition, lnc-FAM84B-8 and lnc-SAMD3-1 were found to regulate these above hub genes through building a lncRNA-mRNA network.

Conclusion

This is the first study to construct the serum lncRNA-mRNA network in MHE, demonstrating the critical role of lncRNAs in regulating inflammatory and immunological profiles in the developing of MHE, suggesting a latent mechanism in this pathophysiological process.

The Roles and Mechanisms of lncRNAs in Liver Fibrosis

Long non-coding RNAs (lncRNAs) can potentially regulate all aspects of cellular activity including differentiation and development, metabolism, proliferation, apoptosis, and activation, and benefited from advances in transcriptomic and genomic research techniques and database management technologies, its functions and mechanisms in physiological and pathological states have been widely reported. Liver fibrosis is typically characterized by a reversible wound healing response, often accompanied by an excessive accumulation of extracellular matrix. In recent years, a range of lncRNAs have been investigated and found to be involved in several cellular-level regulatory processes as competing endogenous RNAs (ceRNAs) that play an important role in the development of liver fibrosis. A variety of lncRNAs have also been shown to contribute to the altered cell cycle, proliferation profile associated with the accelerated development of liver fibrosis. This review aims to discuss the functions and mechanisms of lncRNAs in the development and regression of liver fibrosis, to explore the major lncRNAs involved in the signaling pathways regulating liver fibrosis, to elucidate the mechanisms mediated by lncRNA dysregulation and to provide new diagnostic and therapeutic strategies for liver fibrosis.

The METTL3/MALAT1/PTBP1/USP8/TAK1 axis promotes pyroptosis and M1 polarization of macrophages and contributes to liver fibrosis

Pro-inflammatory M1 macrophages, via activating hepatic stellate cells, contribute to liver fibrosis. In this study, we examined the mechanism and the significance of a signaling axis, METTL3/MALAT1/PTBP1/USP8/TAK1, in regulating pyroptosis and M1 polarization of hepatic macrophages. Liver fibrosis model was established in vivo by CCl₄ treatment; M1 polarization was induced in vitro by treating macrophages with lipopolysaccharide or interferon γ. Expressions of METTL3, MALAT1, PTBP1, USP8, and TAK1 were measured by RT-PCR and/or Western blot in Kupffer cells (KCs) isolated from in vivo model or in vitro activated macrophages. Macrophage phenotypes including inflammation (RT-qPCR analysis of a panel of proinflammatory cytokines and ELISA on productions of interleukin (IL)−1β and IL-18) and pyroptosis (Western blot of NLRP3, Caspase-1, and GSDMD) were investigated. The impact of METTL3 on m⁶A methylation of MALAT1 was examined by methylated RNA immunoprecipitation (RIP), the interaction between PTBP1 and MALAT1 or USP8 mRNA by combining RNA pull-down, RIP, and RNA stability assays, and the crosstalk between USP8 and TAK1 by co-immunoprecipitation and protein degradation assays. Functional significance of individual component of METTL3/MALAT1/PTBP1/USP8/TAK1 axis was assessed by combining gain-of-function and loss-of-function approaches. In KCs isolated from in vivo liver fibrosis model or in vitro M1-polarized macrophages, METTL3 was up-regulated, and sequentially, it increased MALAT1 level via m⁶A methylation, which promoted USP8 mRNA degradation through the interaction with PTBP1. Reduced USP8 expression regulated the ubiquitination and protein stability of TAK1, which promoted pyroptosis and inflammation of macrophages. The signaling cascade METTL3/MALAT1/PTBP1/USP8/TAK1, by essentially stimulating pyroptosis and inflammation of macrophages, aggravates liver fibrosis. Therefore, targeting individual components of this axis may benefit the treatment of liver fibrosis.

Novel Insights Into MALAT1 Function as a MicroRNA Sponge in NSCLC

The long non-coding RNA metastasis-associated lung adenocarcinoma transcript-1 (MALAT1) was initially found to be overexpressed in early non-small cell lung cancer (NSCLC). Accumulating studies have shown that MALAT1 is overexpressed in the tissue or serum of NSCLC and plays a key role in its occurrence and development. In addition, the expression level of MALAT1 is significantly related to the tumor size, stage, metastasis, and distant invasion of NSCLC. Therefore, MALAT1 could be used as a biomarker for the early diagnosis, severity assessment, or prognosis evaluation of NSCLC patients. This review describes the basic properties and biological functions of MALAT1, focuses on the specific molecular mechanism of MALAT1 as a microRNA sponge in the occurrence and development of NSCLC in recent years, and emphasizes the application and potential prospect of MALAT1 in molecular biological markers and targeted therapy of NSCLC.

Acetylation of H3K27 activated lncRNA NEAT1 and promoted hepatic lipid accumulation in non-alcoholic fatty liver disease via regulating miR-212-5p/GRIA3

Non-alcoholic fatty liver disease (NAFLD) was a world-wide health burden. H3K27 acetylation, long non-coding RNA (lncRNA), and miRNA were all implicated in NAFLD regulation, yet the detailed regulatory mechanism was not well understood. LncRNA NEAT1, miR-212-5p, and GRIA3 expression were detected both in high fatty acid-treated hepatocytes cells and NAFLD patients. Lipid droplets were stained and analyzed by oil red O staining. Expression of fatty acid synthase (FASN), acetyl-CoA carboxylase (ACC), and GRIA3 was detected by qRT-PCR and western blot. RNA level of lncRNA NEAT1 and miR-212-5p was analyzed by qRT-PCR. The binding sequences of lncRNA NEAT1/miR-212-5p and miR-212-5p/GRIA3 were predicted bioinformatically and validated through luciferase assay. ChIP was performed to analyze H3K27 acetylation on the promoter of lncRNA NEAT1. LncRNA NEAT1 and GRIA3 was upregulated, while miR-212-5p was downregulated in NAFLD patients. FFA promoted lncRNA NEAT1 and GRIA3 expression while suppressing miR-212-5p and promoted lipid accumulation as indicated by increased oil red O staining and FAS and ACC expression. ChIP indicated enrichment of H3K27 on NEAT1 promoter. Inhibition of H3K27 acetylation suppressed lncRNA NEAT1 level. Luciferase results indicated direct interaction of NEAT1/miR-212-5p (which was confirmed by RIP) and miR-212-5p/GRIA3. LncRNA NEAT1 knockdown upregulated miR-212-5p level and inhibited FFA-induced lipid accumulation while suppressing GRIA3 expression. Such function was antagonized by miR-212-5p inhibition and GRIA3 knockdown counteracted with miR-212-5p inhibition. H3K27 acetylation was enriched within the promoter of lncRNA NEAT1 and promoted lncRNA NEAT1 transcription. LncRNA NEAT1 could then interact with miR-212-5p and suppress its cellular concentration.

Long non-coding RNAs in metabolic disorders: pathogenetic relevance and potential biomarkers and therapeutic targets

BACKGROUND

It has been suggested that dysregulation of long non-coding RNAs (lncRNAs) could be associated with the incidence and development of metabolic disorders.

AIM

Accordingly, this narrative review described the molecular mechanisms of lncRNAs in the development of metabolic diseases including insulin resistance, diabetes, obesity, non-alcoholic fatty liver disease (NAFLD), cirrhosis, and coronary artery diseases (CAD). Furthermore, we investigated the up-to-date findings on the association of deregulated lncRNAs in the metabolic disorders, and potential use of lncRNAs as biomarkers and therapeutic targets.

CONCLUSION

LncRNAs/miRNA/regulatory proteins axis plays a crucial role in progression of metabolic disorders and may be used in development of therapeutic and diagnostic approaches.

Identification of differentially expressed long noncoding RNAs and pathways in liver tissues from rats with hepatic fibrosis

To identify long non-coding RNAs (lncRNAs) and their potential roles in hepatic fibrosis in rat liver issues induced by CCl4, lncRNAs and genes were analyzed in fibrotic rat liver tissues by RNA sequencing and verified by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Differentially expressed (DE) lncRNAs (DE-lncRNAs) and genes were subjected to bioinformatics analysis and used to construct a co-expression network. We identified 10 novel DE-lncRNAs that were downregulated during the hepatic fibrosis process. The cis target gene of DE-lncRNA, XLOC118358, was Met, and the cis target gene of the other nine DE-lncRNAs, XLOC004600, XLOC004605, XLOC004610, XLOC004611, XLOC004568, XLOC004580 XLOC004598, XLOC004601, and XLOC004602 was Nox4. The results of construction of a pathway-DEG co-expression network show that lncRNA-Met and lncRNAs-Nox4 were involved in oxidation-reduction processes and PI3K/Akt signaling pathway. Our results identified 10 DE-lncRNAs related to hepatic fibrosis, and the potential roles of DE-lncRNAs and target genes in hepatic fibrosis might provide new therapeutic strategies for hepatic fibrosis.

Non-alcoholic Steatohepatitis Pathogenesis, Diagnosis, and Treatment

There has been a rise in the prevalence of non-alcohol fatty liver disease (NAFLD) due to the popularity of western diets and sedentary lifestyles. One quarter of NAFLD patients is diagnosed with non-alcoholic steatohepatitis (NASH), with histological evidence not only of fat accumulation in hepatocytes but also of liver cell injury and death due to long-term inflammation. Severe NASH patients have increased risks of cirrhosis and liver cancer. In this review, we discuss the pathogenesis and current methods of diagnosis for NASH, and current status of drug development for this life-threatening liver disease.

LncRNAs as Therapeutic Targets and Potential Biomarkers for Lipid-Related Diseases

Lipid metabolism is an essential biological process involved in nutrient adjustment, hormone regulation, and lipid homeostasis. An irregular lifestyle and long-term nutrient overload can cause lipid-related diseases, including atherosclerosis, myocardial infarction (MI), obesity, and fatty liver diseases. Thus, novel tools for efficient diagnosis and treatment of dysfunctional lipid metabolism are urgently required. Furthermore, it is known that lncRNAs based regulation like sponging microRNAs (miRNAs) or serving as a reservoir for microRNAs play an essential role in the progression of lipid-related diseases. Accordingly, a better understanding of the regulatory roles of lncRNAs in lipid-related diseases would provide the basis for identifying potential biomarkers and therapeutic targets for lipid-related diseases. This review highlighted the latest advances on the potential biomarkers of lncRNAs in lipid-related diseases and summarised current knowledge on dysregulated lncRNAs and their potential molecular mechanisms. We have also provided novel insights into the underlying mechanisms of lncRNAs which might serve as potential biomarkers and therapeutic targets for lipid-related diseases. The information presented here may be useful for designing future studies and advancing investigations of lncRNAs as biomarkers for diagnosis, prognosis, and therapy of lipid-related diseases.

Long Noncoding RNAs and Human Liver Disease

Long noncoding RNAs (lncRNAs) are pervasively transcribed in the genome, exhibit a diverse range of biological functions, and exert effects through a variety of mechanisms. The sheer number of lncRNAs in the human genome has raised important questions about their potential biological significance and roles in human health and disease. Technological and computational advances have enabled functional annotation of a large number of lncRNAs. Though the number of publications related to lncRNAs has escalated in recent years, relatively few have focused on those involved in hepatic physiology and pathology. We provide an overview of evolving lncRNA classification systems and characteristics and highlight important advances in our understanding of the contribution of lncRNAs to liver disease, with a focus on nonalcoholic steatohepatitis, hepatocellular carcinoma, and cholestatic liver disease. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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.

Long non‑coding RNA HOTTIP enhances the fibrosis of lung tissues by regulating the miR‑744‑5p/PTBP1 signaling axis

Fibrosis of lung tissue can induce the occurrence and development of numerous types of lung disease. The expression levels of the long non-coding RNA (lncRNA) HOXA distal transcript antisense RNA (HOTTIP) have been reported to be upregulated during the development of fibrosis in liver tissues, which subsequently activated hepatic stellate cells. However, whether the lncRNA HOTTIP participates in the occurrence and development of lung fibrosis remains unknown. The present study aimed to investigate the role of lncRNA HOTTIP in lung fibrosis and its potential mechanism. In the present study, A549 cells were stimulated with TGF-β1 to induce lung fibrosis in vitro. A549 was transfected with short hairpin RNA-HOTTP, overexpression-polypyrimidine tract binding protein 1 (PTBP1), microRNA (miR)-744-5p mimic or miR-744-5p to regulate gene expression. Cell proliferation and migration were determined using 5′-ethynl-2′-deoxyuridine and wound healing assays, respectively. The expression levels of α-smooth muscle actin, collagen I, collagen III and fibronectin 1 were analyzed using western blotting. starBase was used to identify molecules that may interact with the lncRNA HOTTIP and dual luciferase reporter assays were used to validate the findings. Moreover, an in vivo lung fibrosis model was established by bleomycin induction in mice. Histological injury was observed using hematoxylin and eosin and masson staining. The results of the present study revealed that the proliferation and migration of A549 cells were both suppressed following the knockdown of HOTTIP. The lncRNA HOTTIP was found to target and downregulate the expression levels of miR-744-5p. The overexpression of miR-744-5p inhibited the proliferation and migration of A549 cells. Furthermore, miR-744-5p targeted and downregulated the expression levels of PTBP1. It was subsequently demonstrated that the overexpression of PTBP1 rescued miR-744-5p-induced suppression of the proliferation and migration of A549 cells. The knockdown of lncRNA HOTTIP expression also relieved the fibrosis of the lung tissues of mice. In conclusion, the results of the present study suggested that the lncRNA HOTTIP may promote the fibrosis of lung tissues by downregulating the expression levels of miR-744-5p and upregulating the expression levels of PTBP1.

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.

Roles of long noncoding RNAs on tumor immune escape by regulating immune cells differentiation and function

A long noncoding RNA (lncRNA) transcript is generally more than 200 nucleotides in length and rarely codes for any protein. Currently, many lncRNAs have been identified among mammalian genomes, and their known functions are associated with various physiological activities or pathological processes. Some lncRNAs are dysregulated in a variety of malignant tumors, while increasing evidence indicates that abnormal expression can contribute to the regulation of immune cells in tumors and to shaping the immune response. More specifically, lncRNAs participate in regulating the differentiation of immune cells, also known as myeloid and lymphoid cells, as well as recruiting various immunosuppressive factors to influence the tumor microenvironment, thereby promoting tumor cell immune escape. However, we still know very little about the specific mechanism of lncRNAs in immune escape of cancer. Nonetheless, although unprecedented achievements have allowed the development of a new generation of anti-tumor immune therapies to be applied in clinical trials, the drug resistance caused by immune escape has become a major clinical challenge. The focus of this review is to describe the relationship among lncRNAs, immune cells, and tumor immune escape, in order to identify novel diagnostic and therapeutic targets in human cancers.

Long noncoding RNA H19 - a new player in the pathogenesis of liver diseases

The liver is a vital organ that controls glucose and lipid metabolism, hormone regulation, and bile secretion. Liver injury can occur from various insults such as viruses, metabolic diseases, and alcohol, which lead to acute and chronic liver diseases. Recent studies have demonstrated the implications of long noncoding RNAs (lncRNAs) in the pathogenesis of liver diseases. These newly discovered lncRNAs have various functions attributing to many cellular biological processes via distinct and diverse mechanisms. LncRNA H19, one of the first lncRNAs being identified, is highly expressed in fetal liver but not in adult normal liver. Its expression, however, is increased in liver diseases with various etiologies. In this review, we focused on the roles of H19 in the pathogenesis of liver diseases. This comprehensive review is aimed to provide useful perspectives and translational applications of H19 as a potential therapeutic target of liver diseases.

The identify role and molecular mechanism of the MALAT1/hsa-mir-20b-5p/TXNIP axis in liver inflammation caused by CHB in patients with chronic HBV infection complicated with NAFLD

BACKGROUND/AIMS

To identify the inflammatory damage caused by chronic hepatitis B (CHB) in patients of chronic hepatitis B virus (HBV) infection complicated with non-alcoholic fatty liver disease (NAFLD), then guiding clinicians to carry out antiviral treatment.

METHODS

According to the pathological features of liver biopsy, treatment-naïve obese patients of chronic HBV infection complicated with NAFLD who had elevated alanine transaminase (ALT) were divided into CHB group and NASH group. Transcriptome chips were used to analyze the expression profiles of long non-coding RNA (lncRNA) and mRNA in liver puncture tissues from the two groups. The chip data of CHB and NASH groups were analyzed for differential expression analysis, gene function analysis, signal pathway analysis, target gene prediction and competing endogenous RNAs (ceRNA) network analysis.

RESULTS

By comparing CHB group with NASH group, a total of 44 differentially expressed lncRNAs and 567 differentially expressed mRNAs were screened. GO analysis predicted that the differentially expressed mRNAs may affect monooxygenase activity and oxidoreductase activity. KEGG analysis predicted that the differentially expressed mRNAs may be related to signaling pathways involved in oxidative phosphorylation, phagosomes, and NAFLD. Differential analysis of lncRNA shown that the expression of metastasis associated in lung adenocarcinoma transcript 1 (MALAT1) in CHB group was significantly upregulated. Subsequently, through target gene prediction and ceRNA network analysis, we found thioredoxin interacting protein (TXNIP), which was significantly upregulated in the CHB group and had a ceRNA relationship with MALAT1. It is predicted that there may be a ceRNA regulation relationship of MALAT1/hsa-miR- 20b-5p/TXNIP.

CONCLUSION

The MALAT1/hsa-miR-20b-5p/TXNIP axis may mediate CHB-induced inflammatory damage in chronic HBV infection complicated with NAFLD, and the mechanism may be related to the activation of NLRP3 inflammatory bodies and downstream inflammatory responses.

LncRNA-Gm9795 promotes inflammation in non-alcoholic steatohepatitis via NF-[Formula: see text]B/JNK pathway by endoplasmic reticulum stress

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is a key stage in leading development of non-alcoholic simple fatty liver (NAFL) into cirrhosis and even liver cancer. This study aimed at exploring the lncRNAs expression profile in NASH and the biological function of a novel LncRNA-gm9795.

METHODS

Microarray analysis was performed to compare the expression profiles of lncRNAs in the liver of NASH, NAFLD and normal mice (5 mice for each group). Methionine-choline-deficient Medium (MCD) with Lipopolysaccharide (LPS) or palmitic acid (PA)were used to built NASH cell models. The role and mechanism of LncRNA-gm9795 in NASH were explored by knocking down or over-expressing its expression.

RESULTS

A total of 381 lncRNAs were found to be not only highly expressed in NAFLD, but also is going to go even higher in NASH. A novel LncRNA-gm9795 was significantly highly expressed in liver tissues of NASH animal models and NASH cell models. By staining with Nile red, we found that gm9795 did not affect the fat accumulation of NASH. However, gm9795 in NASH cell models significantly promoted the expression of TNF [Formula: see text], IL-6, IL-1[Formula: see text], the important inflammatory mediators in NASH. At the same time, we found that gm9795 upregulated the key molecules in endoplasmic reticulum stress (ERS), while NF-[Formula: see text]B/JNK pathways were also activated. When ERS activator Thapsigargin (TG) was introduced in cells with Ggm9757 si-RNA, NF-[Formula: see text]B and JNK pathways were activated. Conversely, ERS inhibitor Tauroursodeoxycholic acid (TUDCA) inhibited NF-kB and JNK pathways in cells with gm9795 overexpression plasmid.

CONCLUSION

LncRNA-gm9795 promotes inflammatory response in NASH through NF-kB and JNK pathways by ERS, which might provide theoretical basis for revealing the pathogenesis of NASH and discovering new therapeutic targets.

A comprehensive review of long non-coding RNAs in the pathogenesis and development of non-alcoholic fatty liver disease

One of the most prevalent diseases worldwide without a fully-known mechanism is non-alcoholic fatty liver disease (NAFLD). Recently, long non-coding RNAs (lncRNAs) have emerged as significant regulatory molecules. These RNAs have been claimed by bioinformatic research that is involved in biologic processes, including cell cycle, transcription factor regulation, fatty acids metabolism, and-so-forth. There is a body of evidence that lncRNAs have a pivotal role in triglyceride, cholesterol, and lipoprotein metabolism. Moreover, lncRNAs by up- or down-regulation of the downstream molecules in fatty acid metabolism may determine the fatty acid deposition in the liver. Therefore, lncRNAs have attracted considerable interest in NAFLD pathology and research. In this review, we provide all of the lncRNAs and their possible mechanisms which have been introduced up to now. It is hoped that this study would provide deep insight into the role of lncRNAs in NAFLD to recognize the better molecular targets for therapy.

Epigenetic Regulation of Kupffer Cell Function in Health and Disease

Kupffer cells, the resident macrophages of the liver, comprise the largest pool of tissue macrophages in the body. Within the liver sinusoids Kupffer cells perform functions common across many tissue macrophages including response to tissue damage and antigen presentation. They also engage in specialized activities including iron scavenging and the uptake of opsonized particles from the portal blood. Here, we review recent studies of the epigenetic pathways that establish Kupffer cell identity and function. We describe a model by which liver-environment specific signals induce lineage determining transcription factors necessary for differentiation of Kupffer cells from bone-marrow derived monocytes. We conclude by discussing how these lineage determining transcription factors (LDTFs) drive Kupffer cell behavior during both homeostasis and disease, with particular focus on the relevance of Kupffer cell LDTF pathways in the setting of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis.

Role of long non‑coding RNAs and related epigenetic mechanisms in liver fibrosis (Review)

Liver fibrosis is one of the major liver pathologies affecting patients worldwide. It results from an improper tissue repair process following liver injury or inflammation. If left untreated, it ultimately leads to liver cirrhosis and liver failure. Long non‑coding RNAs (lncRNAs) have been implicated in a wide variety of diseases. They can regulate gene expression and modulate signaling. Some of the lncRNAs promote, while others inhibit liver fibrosis. Similarly, other epigenetic processes, such as methylation and acetylation regulate gene transcription and can modulate gene expression. Notably, there are several regulatory associations of lncRNAs with other epigenetic processes. A major mechanism of action of long non‑coding RNAs is to competitively bind to their target microRNAs (miRNAs or miRs), which in turn affects miRNA availability and bioactivity. In the present review, the role of lncRNAs and related epigenetic processes contributing to liver fibrosis is discussed. Finally, various potential therapeutic approaches targeting lncRNAs and related epigenetic processes, which are being considered as possible future treatment targets for liver fibrosis are identified.

Downregulated microRNA-129-5p by Long Non-coding RNA NEAT1 Upregulates PEG3 Expression to Aggravate Non-alcoholic Steatohepatitis

Long non-coding RNAs (lncRNAs) have recently emerged as inflammation-associated biological molecules with a specific role in the progression of liver fibrosis conditions including non-alcoholic steatohepatitis (NASH). The aim of this study was to elucidate the effects of lncRNA nuclear enriched abundant transcript 1 (NEAT1), microRNA-129-5p (miR-129-5p), and paternally expressed gene 3 (PEG3) on the biological activities of hepatic stellate cells (HSCs) subjected to NASH. First, microarray-based analysis revealed upregulated PEG3 in NASH. Liver tissues from mice fed a methionine–choline-deficient (MCD) diet exhibited increased expression of NEAT1 and PEG3 along with lower miR-129-5p expression. A series of in vitro and in vivo assays were then performed on HSCs after transfection with shPEG3, miR-129-5p mimic, or treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of the nuclear factor-kappa B (NF-κB) signaling pathway. Results confirmed the alleviated fibrosis by restoring miR-129-5p, while depleting PEG3 or NEAT1, as evidenced by the inactivation of HSCs. To sum up, NEAT1 can bind specifically to miR-129-5p and consequently regulate miR-129-5p and PEG3 expression in relation to the HSC activation occurring in NASH. Thus, NEAT1-targeted inhibition against miR-129-5p presents a promising therapeutic strategy for the treatment of NASH.

Oscillating lncRNA Platr4 regulates NLRP3 inflammasome to ameliorate nonalcoholic steatohepatitis in mice

Background: Understanding the molecular events and mechanisms underlying development and progression of nonalcoholic steatohepatitis is essential in an attempt to formulating a specific treatment. Here, we uncover Platr4 as an oscillating and NF-κB driven lncRNA that is critical to the pathological conditions in experimental steatohepatitis Methods: RNA-sequencing of liver samples was used to identify differentially expressed lncRNAs. RNA levels were analyzed by qPCR and FISH assays. Proteins were detected by immunoblotting and ELISA. Luciferase reporter, ChIP-sequencing and ChIP assays were used to investigate transcriptional gene regulation. Protein interactions were evaluated by Co-IP experiments. The protein-RNA interactions were studied using FISH, RNA pull-down and RNA immunoprecipitation analyses Results: Cyclic expression of Platr4 is generated by the core clock component Rev-erbα via two RevRE elements (i.e., -1354/-1345 and -462/-453 bp). NF-κB transcriptionally drives Platr4 through direct binding to two κB sites (i.e., -1066/-1056 and -526/-516 bp), potentially accounting for up-regulation of Platr4 in experimental steatohepatitis. Intriguingly, Platr4 serves as a circadian repressor of Nlrp3 inflammasome pathway by inhibiting NF-κB-dependent transcription of the inflammasome components Nlrp3 and Asc. Loss of Platr4 down-regulates Nlrp3 inflammasome activity in the liver, blunts its diurnal rhythm, and sensitizes mice to experimental steatohepatitis, whereas overexpression of Platr4 ameliorates the pathological conditions in an Nlrp3-dependent manner. Mechanistically, Platr4 prevents binding of the NF-κB/Rxrα complex to the κB sites via a physical interaction, thereby inhibiting the transactivation of Nlrp3 and Asc by NF-κB. Conclusions:Platr4 functions to inactivate Nlrp3 inflammasome via intercepting NF-κB signaling. This lncRNA might be an attractive target that can be modulated to ameliorate the pathological conditions of steatohepatitis.

Noncoding RNAs as Promising Diagnostic Biomarkers and Therapeutic Targets in Intestinal Fibrosis of Crohn's Disease: The Path From Bench to Bedside

Fibrosis is a major pathway to organ injury and failure, accounting for more than one-third of deaths worldwide. Intestinal fibrosis causes irreversible and serious clinical complications, such as strictures and obstruction, secondary to a complex pathogenesis. Under the stimulation of profibrotic soluble factors, excessive activation of mesenchymal cells causes extracellular matrix deposition via canonical transforming growth factor-β/Smads signaling or other pathways (eg, epithelial-to-mesenchymal transition and endothelial-to-mesenchymal transition) in intestinal fibrogenesis. In recent studies, the importance of noncoding RNAs (ncRNAs) stands out in fibrotic diseases in that ncRNAs exhibit a remarkable variety of biological functions in modulating the aforementioned fibrogenic responses. In this review, we summarize the role of ncRNAs, including the emerging long ncRNAs and circular RNAs, in intestinal fibrogenesis. Notably, the translational potential of ncRNAs as diagnostic biomarkers and therapeutic targets in the management of intestinal fibrosis is discussed based on clinical trials from fibrotic diseases in other organs. The main points of this review include the following: • Characteristics of ncRNAs and mechanisms of intestinal fibrogenesis • Wide participation of ncRNAs (especially the emerging long ncRNAs and circular RNAs) in intestinal fibrosis, including transforming growth factor-β signaling, epithelial-to-mesenchymal transition/endothelial-to-mesenchymal transition, and extracellular matrix remodeling • Translational potential of ncRNAs in the diagnosis and treatment of intestinal fibrosis based on clinical trials from fibrotic diseases in other organs.

A study on the pathogenesis of blood-heat psoriasis with transcriptome analysis

Background

Most existing studies on psoriasis' pathogenesis have focused on collecting epithelial cell gene sequences from psoriasis patients and normal subjects. In this paper, for the first time, high-throughput microarray was used to study the differential expression of genes in venous blood between patients with blood-heat psoriasis and normal subjects, providing theoretical support for studying the pathogenesis of blood-heat psoriasis.

Methods

Peripheral venous blood was collected from ten patients with blood-heat psoriasis and ten healthy volunteers for high-throughput microarray. The mRNAs, lncRNAs, and circRNAs related to blood-heat psoriasis were selected by analyzing the transcriptome microarray results. Then gene ontology (GO) analysis and KEGG signaling pathway analysis were used to explore further the biological functions of these mRNAs, lncRNAs, and circRNAs in blood-heat pathogenesis psoriasis. Network pharmacology was used to analyze the protein-protein interaction (PPI) network of the genes with differential expression, and the core genes to transmit information were obtained.

Results

A total of 205 circRNAs, 393 lncRNAs, and 157 mRNAs with differential expression associated with psoriasis were selected using high-throughput microarray. GO analysis showed these mRNAs, lncRNAs, and circRNAs were mainly enriched in cellular processes, biological regulation, ribosome formation, and negative regulation of protein binding. However, KEGG enrichment analysis suggested they were mainly enriched in autoimmunity pathways, lipid metabolism, translation, and signal transduction. PPI network analysis of mRNAs with significant difference revealed 11 core genes that transmitted information in psoriasis primarily.

Conclusions

The mRNAs, lncRNAs, and circRNAs with differential expression related to the pathogenesis of blood-heat psoriasis were found using high-throughput microarray for the first time. And the mRNAs, lncRNAs, and circRNAs with potential regulatory functions related to blood-heat psoriasis were then screened by bioinformatics analysis, effectively providing a new research entry point to the pathogenesis of blood-heat psoriasis.

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.