Obeticholic Acid: A New Era in the Treatment of Nonalcoholic Fatty Liver Disease

Current strategies for nonalcoholic fatty liver disease treatment (Review)

Nonalcoholic fatty liver disease (NAFLD), the most common chronic hepatic disease, has become a leading health problem worldwide. The present review summarized the methods and mechanisms to treat NAFLD, including the Mediterranean diet, physical activity and exercise, bariatric surgery and specific therapeutic agents, including statins, peroxisome proliferator‑activated receptor agonists, cenicriviroc and farnesoid X receptor agonists. Biologically active substances, such as peptides, alkaloids, polyphenolic compounds, silymarin, antibiotics, fatty acids, vitamins, probiotics, synbiotics and lamiaceae have also demonstrated actions that combat NAFLD. Considering their different mechanisms of action, combining some of them may prove an efficacious treatment for NAFLD. In this light, the present review describes recent progress and future prospects in treating NAFLD.

Unravelling the therapeutic landscape of bile acid-based therapies in gastrointestinal disorders

ABSTRACT

Bile acids serve as endogenous ligands for nuclear and cell membrane receptors and play a crucial role in bile acid and lipid metabolism. These detergent-like compounds promote bile flow and aid in the absorption of dietary fats and fat-soluble vitamins in the intestine. Synthesized in the liver as end products of cholesterol catabolism, bile acids exhibit a chemical structure comprising a nucleus and a side chain featuring a carboxyl group, with diverse steric arrangements and potential polar substituents. Critical interactions occur between bile acid species and various nuclear and cell membrane receptors, including the farnesoid X receptor and G-protein-coupled bile acid receptor 1. This research aimed to review the literature on bile acids and their roles in treating different diseases. Currently, numerous investigations are concentrating on specific bile acid species that target nuclear receptors in the gastrointestinal system, aiming to improve the treatment of conditions such as nonalcoholic fatty liver disease. Given the global attention this topic has garnered from research groups, it is considered relatively new, thus anticipating some gaps or incomplete data. Bile acid species have a significant therapeutic promise, especially in their ability to activate or inhibit nuclear receptors, such as farnesoid X receptor. This research provides to offer essential information for scientists and medical practitioners interested in discovering new studies that underscore the importance of bile acids in ameliorating and impeding the progression of disorders. Furthermore, it opens avenues for previously overlooked bile acid-based therapies.

Dietary chlorogenic acid alleviates high-fat diet-induced steatotic liver disease by regulating metabolites and gut microbiota

The high-fat diet would lead to excessive fat storage in the liver to form metabolic dysfunction-associated steatotic liver disease (MASLD), and the trend is burgeoning. The aim of the study is to investigate the effects of chlorogenic acid (CGA) on metabolites and gut microorganisms in MASLD mice induced by a high-fat diet. In comparison to the HF group, the TC (total cholesterol), TG (total triglycerides), LDL-C (low-density lipoprotein cholesterol), AST (aspartate aminotransferase) and ALT (alanine transaminase) levels were reduced after CGA supplement. CGA led to an increase in l-phenylalanine, l-tryptophan levels, and promoted fatty acid degradation. CGA increased the abundance of the Muribaculaceae, Bacteroides and Parabacteroides. Changes in these microbes were significantly associated with the liver metabolites level and lipid profile level. These data suggest important roles for CGA regulating the gut microbiota, liver and caecum content metabolites, and TG-, TC- and LDL-C lowering function.

Phytonanotherapy for the Treatment of Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as nonalcoholic fatty liver disease, is a steatotic liver disease associated with metabolic syndrome (MetS), especially obesity, hypertension, diabetes, hyperlipidemia, and hypertriglyceridemia. MASLD in 43-44% of patients can progress to metabolic dysfunction-associated steatohepatitis (MASH), and 7-30% of these cases will progress to liver scarring (cirrhosis). To date, the mechanism of MASLD and its progression is not completely understood and there were no therapeutic strategies specifically tailored for MASLD/MASH until March 2024. The conventional antiobesity and antidiabetic pharmacological approaches used to reduce the progression of MASLD demonstrated favorable peripheral outcomes but insignificant effects on liver histology. Alternatively, phyto-synthesized metal-based nanoparticles (MNPs) are now being explored in the treatment of various liver diseases due to their unique bioactivities and reduced bystander effects. Although phytonanotherapy has not been explored in the clinical treatment of MASLD/MASH, MNPs such as gold NPs (AuNPs) and silver NPs (AgNPs) have been reported to improve metabolic processes by reducing blood glucose levels, body fat, and inflammation. Therefore, these actions suggest that MNPs can potentially be used in the treatment of MASLD/MASH and related metabolic diseases. Further studies are warranted to investigate the feasibility and efficacy of phytonanomedicine before clinical application.

Anthocyanins: Potential phytochemical candidates for the amelioration of non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is described by too much hepatic fat deposition causing steatosis, which further develops into nonalcoholic steatohepatitis (NASH), defined by necroinflammation and fibrosis, progressing further to hepatic cirrhosis, hepatocellular carcinoma, and liver failure. NAFLD is linked to different aspects of the metabolic syndrome like obesity, insulin resistance, hypertension, and dyslipidemia, and its pathogenesis involves several elements including diet, obesity, disruption of lipid homeostasis, and a high buildup of triglycerides and other lipids in liver cells. It is therefore linked to an increase in the susceptibility to developing diabetes mellitus and cardiovascular diseases. Several interventions exist regarding its management, but the availability of natural sources through diet will be a benefit in dealing with the disorder due to the immensely growing dependence of the population worldwide on natural sources owing to their ability to treat the root cause of the disease. Anthocyanins (ACNs) are naturally occurring polyphenolic pigments that exist in the form of glycosides, which are the glucosides of anthocyanidins and are produced from flavonoids via the phenyl propanoid pathway. To understand their mode of action in NAFLD and their therapeutic potential, the literature on in vitro, in vivo, and clinical trials on naturally occurring ACN-rich sources was exhaustively reviewed. It was concluded that ACNs show their potential in the treatment of NAFLD through their antioxidant properties and their efficacy to control lipid metabolism, glucose homeostasis, transcription factors, and inflammation. This led to the conclusion that ACNs possess efficacy in the amelioration of NAFLD and the various features associated with it. However, additional clinical trials are required to justify the potential of ACNs in NAFLD.

Hammerhead-type FXR agonists induce an enhancer RNA Fincor that ameliorates nonalcoholic steatohepatitis in mice

The nuclear receptor, farnesoid X receptor (FXR/NR1H4), is increasingly recognized as a promising drug target for metabolic diseases, including nonalcoholic steatohepatitis (NASH). Protein-coding genes regulated by FXR are well known, but whether FXR also acts through regulation of long non-coding RNAs (lncRNAs), which vastly outnumber protein-coding genes, remains unknown. Utilizing RNA-seq and global run-on sequencing (GRO-seq) analyses in mouse liver, we found that FXR activation affects the expression of many RNA transcripts from chromatin regions bearing enhancer features. Among these we discovered a previously unannotated liver-enriched enhancer-derived lncRNA (eRNA), termed FXR-induced non-coding RNA (Fincor). We show that Fincor is specifically induced by the hammerhead-type FXR agonists, including GW4064 and tropifexor. CRISPR/Cas9-mediated liver-specific knockdown of Fincor in dietary NASH mice reduced the beneficial effects of tropifexor, an FXR agonist currently in clinical trials for NASH and primary biliary cholangitis (PBC), indicating that amelioration of liver fibrosis and inflammation in NASH treatment by tropifexor is mediated in part by Fincor. Overall, our findings highlight that pharmacological activation of FXR by hammerhead-type agonists induces a novel eRNA, Fincor, contributing to the amelioration of NASH in mice. Fincor may represent a new drug target for addressing metabolic disorders, including NASH.

Natural Products in the Modulation of Farnesoid X Receptor Against Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a global health concern with a high prevalence and increasing economic burden, but official medicine remains unavailable. Farnesoid X receptor (FXR), a nuclear receptor member, is one of the most promising drug targets for NAFLD therapy that plays a crucial role in modulating bile acid, glucose, and lipid homeostasis, as well as inhibits hepatic inflammation and fibrosis. However, the rejection of the FXR agonist, obecholic acid, by the Food and Drug Administration for treating hepatic fibrosis raises a question about the functions of FXR in NAFLD progression and the therapeutic strategy to be used. Natural products, such as FXR modulators, have become the focus of attention for NAFLD therapy with fewer adverse reactions. The anti-NAFLD mechanisms seem to act as FXR agonists and antagonists or are involved in the FXR signaling pathway activation, indicating a promising target of FXR therapeutic prospects using natural products. This review discusses the effective mechanisms of FXR in NAFLD alleviation, and summarizes currently available natural products such as silymarin, glycyrrhizin, cycloastragenol, berberine, and gypenosides, for targeting FXR, which can facilitate development of naturally targeted drug by medicinal specialists for effective treatment of NAFLD.

Hammerhead-type FXR agonists induce an eRNA FincoR that ameliorates nonalcoholic steatohepatitis in mice

The nuclear receptor, Farnesoid X Receptor (FXR/NR1H4), is increasingly recognized as a promising drug target for metabolic diseases, including nonalcoholic steatohepatitis (NASH). Protein coding genes regulated by FXR are well known, but whether FXR also acts through regulation of long non-coding RNAs (lncRNAs), which vastly outnumber protein-coding genes, remains unknown. Utilizing RNA-seq and GRO-seq analyses in mouse liver, we found that FXR activation affects the expression of many RNA transcripts from chromatin regions bearing enhancer features. Among these we discovered a previously unannotated liver-enriched enhancer-derived lncRNA (eRNA), termed FincoR. We show that FincoR is specifically induced by the hammerhead-type FXR agonists, including GW4064 and tropifexor. CRISPR/Cas9-mediated liver-specific knockdown of FincoR in dietary NASH mice reduced the beneficial effects of tropifexor, an FXR agonist currently in clinical trials for NASH and primary biliary cholangitis (PBC), indicating that that amelioration of liver fibrosis and inflammation in NASH treatment by tropifexor is mediated in part by FincoR. Overall, our findings highlight that pharmacological activation of FXR by hammerhead-type agonists induces a novel eRNA, FincoR, contributing to the amelioration of NASH in mice. FincoR may represent a new drug target for addressing metabolic disorders, including NASH.

Obeticholic acid treatment of mice to promote fertilization and reproduction

Obeticholic acid (OCA), a farnesoid X receptor (FXR) agonist, has been demonstrated to ameliorate the histopathological characteristics of liver damage. Nonetheless, the systemic safety profile of OCA with regard to reproduction and development remains poorly understood. In the present study, we conducted a dose-response experiment by administering OCA at doses of 5 mg/kg, 10 mg/kg, or 20 mg/kg through tube feeding to investigate its effect on reproductive development and fertilization rate in both male and female mice. Furthermore, we evaluated the levels of protein and mitochondrial function in the placenta through western blot, qPCR, and scanning electron microscopy. The results showed that 10 mg/kg and 20 mg/kg OCA doses significantly reduced the rate of placental implantation (P < 0.05). Also, OCA increased maternal body weight. In addition, OCA increased levels of FXR and TGR5 and produced changes in oxidative stress levels (P < 0.05). Mitochondrial activity result found that 10 mg/kg and 20 mg/kg of OCA significantly reduced the mitophagy autosomes/nucleus compared with the normal control group (P < 0.05). What is more, there was no significant difference in sperm count after OCA intervention in either C57BL/10 mice or BALB/c mice. Overall, we demonstrated that OCA treatment protected against placental implantation by suppressing placental oxidative stress and mitochondrial activity.

FXR agonists in NASH treatment

The farnesoid X receptor (FXR), a bile acid (BA)-activated nuclear receptor highly expressed in the liver and intestine, regulates the expression of genes involved in cholesterol and bile acid homeostasis, hepatic gluconeogenesis, lipogenesis, inflammation and fibrosis, in addition to controlling intestinal barrier integrity, preventing bacterial translocation and maintaining gut microbiota eubiosis. Non-alcoholic steatohepatitis (NASH), an advanced stage of non-alcoholic fatty liver disease, is characterized by hepatic steatosis, hepatocyte damage (ballooning) and inflammation, leading to fibrosis, cirrhosis and hepatocellular carcinoma. NASH represents a major unmet medical need, but no pharmacological treatments have yet been approved. The pleiotropic mechanisms involved in NASH development offer a range of therapeutic opportunities and among them FXR activation has emerged as an established pharmacological target. Various FXR agonists with different physicochemical properties, which can be broadly classified as BA derivatives, non-BA-derived steroidal FXR agonists, non-steroidal FXR agonists, and partial FXR agonists, are in advanced clinical development. In this review we will summarize key preclinical and clinical features of the most advanced FXR agonists and critically evaluate their potential in NASH treatment.

Role of inflammasomes and cytokines in immune dysfunction of liver cirrhosis

Liver cirrhosis develops as a result of persistent inflammation and liver injury. The prolonged inflammation triggers the buildup of fibrous tissue and regenerative nodules within the liver, leading to the distortion of the hepatic vascular structure and impaired liver function. Cirrhosis disrupts the ability of liver function to maintain homeostasis and hepatic immunosurveillance which causes immunological dysfunction in the body. In pathological conditions, the production of cytokines in the liver is carefully regulated by various cells in response to tissue stimulation. Cytokines and inflammasomes are the key regulators and systematically contribute to the development of cirrhosis which involves an inflammatory response. However, the crosstalk role of different cytokines in the cirrhosis progression is poorly understood. Tumour necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), and interferon-gamma (IFN-γ), among others, are proinflammatory cytokines that contribute to liver cell necrosis, which in turn causes the development of fibrosis. While IL-10 exhibits a potent anti-inflammatory effect on the liver by inhibiting immune cell activation and neutralizing pro-inflammatory cytokine activity. Inflammasomes have also been implicated in the profibrotic processes of liver cirrhosis, as well as the production of chemokines such as CCL2/MCP-1. It is evident that inflammasomes have a role in the proinflammatory response seen in chronic liver illnesses. In conclusion, cirrhosis significantly impacts the immune system, leading to immunological dysfunction and alterations in both innate and acquired immunity. Proinflammatory cytokines like TNF-α, IL-1β, IL-6, and IFNγ are upregulated in cirrhosis, contributing to liver cell necrosis and fibrosis development. Managing cytokine-mediated inflammation and fibrosis is a key therapeutic approach to alleviate portal hypertension and its associated liver complications. This review attempted to focus largely on the role of immune dysfunction mediated by different cytokines and inflammasomes involved in the progression, regulation and development of liver cirrhosis.

Understanding NAFLD: From Case Identification to Interventions, Outcomes, and Future Perspectives

While non-alcoholic fatty liver disease (NAFLD) is a prevalent and frequent cause of liver-related morbidity and mortality, it is also strongly associated with cardiovascular disease-related morbidity and mortality, likely driven by its associations with insulin resistance and other manifestations of metabolic dysregulation. However, few satisfactory pharmacological treatments are available for NAFLD due in part to its complex pathophysiology, and challenges remain in stratifying individual patient's risk for liver and cardiovascular disease related outcomes. In this review, we describe the development and progression of NAFLD, including its pathophysiology and outcomes. We also describe different tools for identifying patients with NAFLD who are most at risk of liver-related and cardiovascular-related complications, as well as current and emerging treatment options, and future directions for research.

ALS-L1023 from Melissa officinalis Alleviates Liver Fibrosis in a Non-Alcoholic Fatty Liver Disease Model

ALS-L1023 is an ingredient extracted from Melissa officinalis L. (Labiatae; lemon balm), which is known as a natural medicine that suppresses angiogenesis. Herein, we aimed to determine whether ALS-L1023 could alleviate liver fibrosis in the non-alcoholic fatty liver disease (NAFLD) model. C57BL/6 wild-type male mice (age, 6 weeks old) were fed a choline-deficient high-fat diet (CDHFD) for 10 weeks to induce NAFLD. For the next 10 weeks, two groups of mice received the test drug along with CDHFD. Two doses (a low dose, 800 mg/kg/day; and a high dose, 1200 mg/kg/day) of ALS-L1023 were selected and mixed with feed for administration. Obeticholic acid (OCA; 10 mg/kg/day) was used as the positive control. Biochemical analysis revealed that the ALS-L1023 low-dose group had significantly decreased alanine transaminase and aspartate transaminase. The area of fibrosis significantly decreased due to the administration of ALS-L1023, and the anti-fibrotic effect of ALS-L1023 was greater than that of OCA. RNA sequencing revealed that the responder group had lower expression of genes related to the hedgehog-signaling pathway than the non-responder group. ALS-L1023 may exert anti-fibrotic effects in the NAFLD model, suggesting that it may provide potential benefits for the treatment of liver fibrosis.

Design and synthesis of ERα agonists: Effectively reduce lipid accumulation

In recent years, the incidence of non-alcoholic fatty liver disease (NAFLD) has been increasing worldwide. Hepatic lipid deposition is a major feature of NAFLD, and insulin resistance is one of the most important causes of lipid deposition. Insulin resistance results in the disruption of lipid metabolism homeostasis characterized by increased lipogenesis and decreased lipolysis. Estrogen receptor α (ERα) has been widely reported to be closely related to lipid metabolism. Activating ERa may be a promising strategy to improve lipid metabolism. Here, we used computer-aided drug design technology to discover a highly active compound, YRL-03, which can effectively reduce lipid accumulation. Cellular experimental results showed that YRL-03 could effectively reduce lipid accumulation by targeting ERα, thereby achieving alleviation of insulin resistance. We believe this study provides meaningful guidance for future molecular development of drugs to prevent and treat NAFLD.

Obesity-induced miR-802 directly targets AMPK and promotes nonalcoholic steatohepatitis in mice

OBJECTIVE

Obesity-associated nonalcoholic fatty liver disease (NAFLD) is a leading cause of liver failure and death. However, the pathogenesis of NAFLD and its severe form, nonalcoholic steatohepatitis (NASH), is poorly understood. The energy sensor, AMP-activated protein kinase (AMPK), has decreased activity in obesity and NAFLD, but the mechanisms are unclear. Here, we examined whether obesity-induced miR-802 has a role in promoting NASH by targeting AMPK. We also investigated whether miR-802 and AMPK have roles in modulating beneficial therapeutic effects mediated by obeticholic acid (OCA), a promising clinical agent for NASH.

METHODS

Immunoblotting, luciferase assays, and RNA-protein interaction studies were performed to test whether miR-802 directly targets AMPK. The roles of miR-802 and AMPK in NASH were examined in mice fed a NASH-promoting diet.

RESULTS

Hepatic miR-802 and AMPK levels were inversely correlated in both NAFLD patients and obese mice. MicroRNA in silico analysis, together with biochemical studies in hepatic cells, suggested that miR-802 inhibits hepatic expression of AMPK by binding to the 3' untranslated regions of both human AMPKα1 and mouse Ampkβ1. In diet-induced NASH mice, OCA treatment reduced hepatic miR-802 levels and improved AMPK activity, ameliorating steatosis, inflammation, and apoptosis, but these OCA-mediated beneficial effects on NASH pathologies, particularly reducing apoptosis, were reversed by overexpression of miR-802 or downregulation of AMPK.

CONCLUSIONS

These results indicate that miR-802 inhibits AMPK by directly targeting Ampkβ1, promoting NAFLD/NASH in mice. The miR-802-AMPK axis that modulates OCA-mediated beneficial effects on NASH may represent a new therapeutic target.

Berberine in Non-Alcoholic Fatty Liver Disease—A Review

The incidence of Non-Alcoholic Fatty Liver Disease (NAFLD) has been rapidly increasing during the last decade. It is a relevant health problem that affects 25% of the general population. NAFLD involves an extensive array of clinical conditions. So far, no approved pharmacological therapy for NAFLD has been developed. Multiple bioactive compounds have been proposed to treat NAFLD. One of the most promising is Berberine (BBR). Its pleiotropic effect positively impacts various cardiometabolic aspects. In this review, we summarize NAFLD, its metabolic and cardiovascular complications, the hepatoprotective effects of BBR due to its broad spectrum of pharmacological effects, and the potential role of BBR in NAFLD therapy. BBR ameliorates NAFLD by affecting numerous abnormalities. It inhibits lipogenesis and gluconeogenesis, improves insulin resistance and lipid profile, and modulates gut microbiota. The exact mechanism underlying these effects is not yet entirely explained. A growing amount of evidence confirming the positive effects of BBR on multiple metabolic pathways, such as lipids and glucose metabolism, energy homeostasis, or gut microbiota modulation, allows us to speculate about the importance of this natural bioactive substance for NAFLD therapy.

Comparing the Efficacy and Safety of Obeticholic Acid and Semaglutide in Patients With Non-Alcoholic Fatty Liver Disease: A Systematic Review

Patients with non-alcoholic fatty liver disease (NAFLD) have an increased risk of developing progressive fibrosis, cirrhosis, and hepatocellular carcinoma. As of now, there are no FDA-approved treatments for NAFLD/non-alcoholic steatohepatitis (NASH) or its associated fibrosis. Although many drugs are under clinical trial, both obeticholic acid (OCA) and semaglutide are among the few that have reached phase III clinical trials, but they were never compared. We decided to conduct a systematic review of randomized controlled trials and meta-analyses. A total of 6,589 articles were found after searching PubMed, OVID Embase, OVID Medline, PubMed Central, and clinicaltrials.gov. Only full-text peer-reviewed articles published in the past six years were put through the Cochrane bias assessment tool or the Assessment of Multiple Systematic Reviews (AMSTAR) tool to screen for bias. After strict quality assessment, data from five randomized controlled trials (n=2,694) and three systematic reviews/meta-analysis (n=8,898) was extracted and included. The data extraction from these studies showed that semaglutide and OCA cause histological improvement, but NASH resolution is exclusive to semaglutide. Although high doses of OCA can cause dyslipidemia and severe pruritus, it is the only therapeutic that causes improvement in NASH-associated hepatic fibrosis. Semaglutide is the safest option among the two and leads to significant weight loss compared to OCA; thus, a better outcome on hepatic steatosis follows. The indications of each of these drugs should be based on the NAFLD activity score and NASH fibrosis stage. OCA should be used with caution among patients with hyperlipidemia and ischemic heart disease as it may make these conditions worst.

Untargeted serum metabolites profiling in high-fat diet mice supplemented with enhanced palm tocotrienol-rich fraction using UHPLC-MS

Excessive high fat dietary intake promotes risk of developing non-alcoholic fatty liver disease (NAFLD) and predisposed with oxidative stress. Palm based tocotrienol-rich fraction (TRF) has been reported able to ameliorate oxidative stress but exhibited poor bioavailability. Thus, we investigated whether an enhanced formulation of TRF in combination with palm kernel oil (medium-chain triglycerides) (ETRF) could ameliorate the effect of high-fat diet (HFD) on leptin-deficient male mice. All the animals were divided into HFD only (HFD group), HFD supplemented with ETRF (ETRF group) and HFD supplemented with TRF (TRF group) and HFD supplemented with PKO (PKO group). After 6 weeks, sera were collected for untargeted metabolite profiling using UHPLC-Orbitrap MS. Univariate analysis unveiled alternation in metabolites for bile acids, amino acids, fatty acids, sphingolipids, and alkaloids. Bile acids, lysine, arachidonic acid, and sphingolipids were downregulated while xanthine and hypoxanthine were upregulated in TRF and ETRF group. The regulation of these metabolites suggests that ETRF may promote better fatty acid oxidation, reduce oxidative stress and pro-inflammatory metabolites and acts as anti-inflammatory in fatty liver compared to TRF. Metabolites regulated by ETRF also provide insight of its role in fatty liver. However, further investigation is warranted to identify the mechanisms involved.

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.

Conformational Characterization of the Co-Activator Binding Site Revealed the Mechanism to Achieve the Bioactive State of FXR

FXR bioactive states are responsible for the regulation of metabolic pathways, which are modulated by agonists and co-activators. The synergy between agonist binding and ‘co-activator’ recruitment is highly conformationally driven. The characterization of conformational dynamics is essential for mechanistic and therapeutic understanding. To shed light on the conformational ensembles, dynamics, and structural determinants that govern the activation process of FXR, molecular dynamic (MD) simulation is employed. Atomic insights into the ligand binding domain (LBD) of FXR revealed significant differences in inter/intra molecular bonding patterns, leading to structural anomalies in different systems of FXR. The sole presence of an agonist or ‘co-activator’ fails to achieve the essential bioactive conformation of FXR. However, the presence of both establishes the bioactive conformation of FXR as they modulate the internal wiring of key residues that coordinate allosteric structural transitions and their activity. We provide a precise description of critical residue positioning during conformational changes that elucidate the synergy between its binding partners to achieve an FXR activation state. Our study offers insights into the associated modulation occurring in FXR at bound and unbound forms. Thereafter, we also identified hot-spots that are critical to arrest the activation mechanism of FXR that would be helpful for the rational design of its agonists.

Effect of soybean insoluble dietary fiber on prevention of obesity in high-fat diet fed mice via regulation of the gut microbiota

Increasing evidence has shown that the gut microbiota plays an important role in preventing obesity; however, the mechanism by which insoluble dietary fiber (IDF) prevents high-fat diet (HFD)-induced obesity remains unclear. This study aimed to investigate the effect of SIDF on obesity in HFD mice and determine the mechanism by which it prevents obesity through regulating the gut microbiota. Soybean insoluble dietary fiber (SIDF) was used as an intervention in HFD mice for 20 weeks. The results showed that SIDF significantly reduced the body weight (BW), fat index, total cholesterol, triglyceride, and low-density lipoprotein cholesterol while increasing the content of high-density lipoprotein cholesterol in HFD mice. SIDF intervention was also beneficial for the reduction of liver lipid content and fatty droplets in mice. Furthermore, SIDF intervention improved the gut microbiota composition by increasing the relative abundance of potentially beneficial bacteria (such as Lactobacillales [order], Lactobacillus [genus], Lachnospirace_Nk4A136_group [genus]), and reduced the relative abundance of potentially harmful bacteria (such as Lachnospiraceae [family] and Bacteroides_acidifaciens [species]), which correlated with obesity (at least p < 0.05 in all instances). Finally, SIDF was fermented by related beneficial bacteria, which increased the content of the short-chain fatty acids (SCFAs), and promoted the secretion of satiety hormones. In conclusion, SIDF intervention could prevent obesity in HFD mice by modulating the gut microbiota composition. Hence, SIDF may be used as a potential ingredient in functional foods.

A Sensitive HPLC-MS/MS Method for Determination of Obeticholic Acid in Human Plasma: Application to a Pharmacokinetic Study in Healthy Volunteers

A rapid and sensitive LC-MS/MS method was developed and fully validated for the determination of obeticholic acid in human plasma. Glimepiride was used as internal standard. For this method, liquid-liquid extraction was performed to extract analyte from the plasma samples. Chromatographic separation was performed on a C18 (2.1 × 50 mm, 2.7 μm, Agilent) column with isocratic elution using water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid at a flow rate of 0.4 mL/min. The mass detection was performed in negative mode. The precursor-product ion pairs for MRM were m/z 465.3 → 419.3 for obeticholic acid and m/z 489.3 → 224.8 for the IS. The method exhibited great linearity over the concentration range of 0.150-100 ng/mL for obeticholic acid. The sensitivity, linearity, accuracy, precision, recovery, matrix effect and stability of this method were all within the acceptable limits. The method was successfully validated and applied to the pharmacokinetic studies in healthy Chinese volunteers after a single oral dose administration of obeticholic acid tablets of 10 mg, and the pharmacokinetic characteristics of obeticholic acid in human were reported for the first time.

Identification of hepatic fibrosis inhibitors through morphometry analysis of a hepatic multicellular spheroids model

A chronic, local inflammatory milieu can cause tissue fibrosis that results in epithelial-to-mesenchymal transition (EMT), endothelial-to-mesenchymal transition (EndMT), increased abundance of fibroblasts, and further acceleration of fibrosis. In this study, we aimed to identify potential mechanisms and inhibitors of fibrosis using 3D model-based phenotypic screening. We established liver fibrosis models using multicellular tumor spheroids (MCTSs) composed of hepatocellular carcinoma (HCC) and stromal cells such as fibroblasts (WI38), hepatic stellate cells (LX2), and endothelial cells (HUVEC) seeded at constant ratios. Through high-throughput screening of FDA-approved drugs, we identified retinoic acid and forskolin as candidates to attenuate the compactness of MCTSs as well as inhibit the expression of ECM-related proteins. Additionally, retinoic acid and forskolin induced reprogramming of fibroblast and cancer stem cells in the HCC microenvironment. Of interest, retinoic acid and forskolin had anti-fibrosis effects by decreasing expression of α-SMA and F-actin in LX2 cells and HUVEC cells. Moreover, when sorafenib was added along with retinoic acid and forskolin, apoptosis was increased, suggesting that anti-fibrosis drugs may improve tissue penetration to support the efficacy of anti-cancer drugs. Collectively, these findings support the potential utility of morphometric analyses of hepatic multicellular spheroid models in the development of new drugs with novel mechanisms for the treatment of hepatic fibrosis and HCCs.

Altered Microbiota Diversity and Bile Acid Signaling in Cirrhotic and Noncirrhotic NASH-HCC

The precipitous increase in nonalcoholic steatohepatitis (NASH) is accompanied by a dramatic increase in the incidence of NASH-related hepatocellular carcinoma (HCC). HCC in NASH has a higher propensity to arise without pre-existing cirrhosis compared with other chronic liver diseases.

A multicentre prospective double blinded randomised controlled trial of intravenous iron (ferric Derisomaltose (FDI)) in Iron deficient but not anaemic patients with chronic kidney disease on functional status

BACKGROUND

Iron deficiency (ID) is common in patients with chronic kidney disease (CKD). Intravenous (IV) iron in heart failure leads to improvement in exercise capacity and improvement in quality-of-life measurements; however, data in patients with CKD are lacking.

METHODS

The Iron and the Heart Study was a prospective double blinded randomised study in non-anaemic CKD stages 3b-5 patients with ID which investigated whether 1000 mg of IV iron (ferric derisomaltose (FDI)) could improve exercise capacity in comparison to placebo measured at 1 and 3 months post infusion. Secondary objectives included effects on haematinic profiles and haemoglobin, safety analysis and quality of life questionnaires (QoL).

RESULTS

We randomly assigned 54 patients mean (SD) age for FDI (n = 26) 61.6 (10.1) years vs placebo (n = 28; 57.8 (12.9) years) and mean eGFR (33.2 (9.3) vs. 29.1 (9.6) ml/min/1.73m2) at baseline, respectively. Adjusting for baseline measurements, six-minute walk test (6MWT) showed no statistically significant difference between arms at 1 month (p = 0.736), or 3 months (p = 0.741). There were non-significant increases in 6MWT from baseline to 1 and 3 months in the FDI arm. Haemoglobin (Hb) at 1 and 3 months remained stable. There were statistically significant increases in ferritin (SF) and transferrin saturation (TSAT) at 1 and 3 months (p < 0.001). There was a modest numerical improvement in QoL parameters. There were no adverse events attributable to IV iron.

CONCLUSION

This study demonstrated a short-term beneficial effect of FDI on exercise capacity, but it was not significant despite improvements in parameters of iron status, maintenance of Hb concentration, and numerical increases in functional capacity and quality of life scores. A larger study will be required to confirm if intravenous iron is beneficial in iron deficient non-anaemic non-dialysis CKD patients without heart failure to improve the 6MWT.

TRIAL REGISTRATION

European Clinical Trials Database (EudraCT) No: 2014-004133-16 REC no: 14/YH/1209 Date First Registered: 2015-02-17 and date of end of trail 2015-05-23 Sponsor ref R1766 and Protocol No: IHI 141.

A novel LC-MS/MS method for simultaneous estimation of obeticholic acid, glyco-obeticholic acid, tauro-obeticholic acid in human plasma and its application to a pharmacokinetic study

A rapid, robust, simple, selective, and sensitive liquid chromatography-tandem mass spectrometry method was developed for the simultaneous estimation of obeticholic acid and its two pharmacologically active metabolites, glyco-obeticholic acid, and tauro-obeticholic acid in human plasma. The analytes and their heavy stable isotope-labeled internal standards were extracted from 250 μL human plasma by a solid-phase extraction technique. The method linearity was established over a concentration range of 0.410 to 120.466 ng/mL for obeticholic acid, 0.414 to 121.708 ng/mL for glyco-obeticholic acid, and 0.255 to 75.101 ng/mL for tauro-obeticholic acid. The method was fully validated as per current guidelines on bioanalytical method validation of "United States of Food and Drug Administration" and "European Medicines Agency." The method was successfully applied to study the pharmacokinetics of obeticholic acid, glyco-obeticholic acid, and tauro-obeticholic acid following oral administration of obeticholic acid tablets to healthy male volunteers. All the measured concentrations were within calibration curve ranges.

Comparison of the Pharmacokinetics of Generic Versus Branded Obeticholic Acid in a Chinese Population: Effects of Food and Sex

The present study assessed the pharmacokinetics and bioequivalence of a single 10-mg dose of a generic and the branded formulation (Ocaliva) of obeticholic acid (OCA) in healthy Chinese subjects under fasting and fed conditions. The possible effects of food and sex on the pharmacokinetics of OCA and its 2 active metabolites (glyco-OCA and tauro-OCA) were evaluated. Plasma concentrations of OCA and its 2 active metabolites were measured by liquid chromatography-tandem mass spectrometry. The 90%CIs of the ratios of the test and reference formulations for C_max , AUC_0-t , and AUC_0-∞ of OCA, glyco-OCA, and tauro-OCA were contained entirely within the 80% to 125% range required for bioequivalence under fasting and fed conditions. Plasma exposure of OCA was 30% to 36% higher under fed compared with fasting conditions. Plasma exposure of OCA, glyco-OCA, and tauro-OCA was 39% to 66%, 22% to 58%, and 37% to 84% higher, respectively, in women compared with men under fasting and fed conditions. In conclusion, OCA was well tolerated in healthy Chinese subjects under fasting and fed conditions. The single 10-mg dose of a generic OCA formulation was bioequivalent to Ocaliva. Food and sex impacted the pharmacokinetics of OCA and/or its 2 active metabolites. Further studies are required to determine if these effects are clinically relevant.

Saffron offers hepatoprotection via up-regulation of hepatic farnesoid-X-activated receptors in a rat model of acetaminophen-induced hepatotoxicity

OBJECTIVES

The most important toxicity of acetaminophen is hepatotoxicity. Farnesoid X-activated receptors (FXR) are one of the nuclear receptor superfamily members which have a pivotal role in the bile acid regulation. The objective of the present study was to examine the role of FXR in mediating the hepatoprotective effects of saffron.

METHODS

Male Wister rats were randomly allocated into five groups including a control, vehicle, acetaminophen and two saffron extract groups of 150 and 300 mg/kg/day. The liver function and hepatic FXR expression were evaluated using biochemical assay and real time RT-PCR, respectively. Data analysis was performed using the one-way ANOVA followed by Duncan's multiple range test.

RESULTS

Levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) of the acetaminophen group were significantly higher than the control group whereas those of the extract-treated groups were significantly lower than those of the acetaminophen group. The real time RT-PCR findings showed a non-significant down-regulation of FXR mRNA expression, however, a dose-dependent FXR up-regulation was seen in the groups treated with 150 and 300 mg/kg of the extract for 2.67 (p=0.002) and 10.22 (p=0.0001) fold, respectively.

CONCLUSION

The main finding of the present study was that the hepatic FXR up-regulation had an important role in saffron hepatoprotective activity.

Liver Fibrosis in Non-alcoholic Fatty Liver Disease: From Liver Biopsy to Non-invasive Biomarkers in Diagnosis and Treatment

An increasing percentage of people have or are at risk to develop non-alcoholic fatty liver disease (NAFLD) worldwide. NAFLD comprises different stadia going from isolated steatosis to non-alcoholic steatohepatitis (NASH). NASH is a chronic state of liver inflammation that leads to the transformation of hepatic stellate cells to myofibroblasts. These cells produce extra-cellular matrix that results in liver fibrosis. In a normal situation, fibrogenesis is a wound healing process that preserves tissue integrity. However, sustained and progressive fibrosis can become pathogenic. This process takes many years and is often asymptomatic. Therefore, patients usually present themselves with end-stage liver disease e.g., liver cirrhosis, decompensated liver disease or even hepatocellular carcinoma. Fibrosis has also been identified as the most important predictor of prognosis in patients with NAFLD. Currently, only a minority of patients with liver fibrosis are identified to be at risk and hence referred for treatment. This is not only because the disease is largely asymptomatic, but also due to the fact that currently liver biopsy is still the golden standard for accurate detection of liver fibrosis. However, performing a liver biopsy harbors some risks and requires resources and expertise, hence is not applicable in every clinical setting and is unsuitable for screening. Consequently, different non-invasive diagnostic tools, mainly based on analysis of blood or other specimens or based on imaging have been developed or are in development. In this review, we will first give an overview of the pathogenic mechanisms of the evolution from isolated steatosis to fibrosis. This serves as the basis for the subsequent discussion of the current and future diagnostic biomarkers and anti-fibrotic drugs.

Enterohepatic circulation of bile acids and their emerging roles on glucolipid metabolism

Bile acids (BAs) are amphiphilic molecules with a nonpolar steroid carbon skeleton and a polar carboxylate side chain. Recently, BAs have aroused the attention of scholars due to their potential roles on metabolic diseases. As important endogenous ligands, BAs are wildly active in the enterohepatic circulation, during which microbiota play a significant role in promoting the hydrolysis and dehydroxylation of BAs. Besides, many pathways initiated by BAs including glucolipid metabolism and inflammation signaling pathways have been reported to regulate the host metabolism and maintain immune homeostasis. Herein, the characteristics on the enterohepatic circulation and metabolism of BAs are systematically summarized. Moreover, the regulation mechanism of the glucolipid metabolism by BAs is intensively discussed. Worthily, FXR and TGR5, which are involved in glucolipid metabolism, are the prime candidates for targeted therapies of chronic metabolic diseases such as diabetes and hypercholesterolemia.

A Review of Liver Fibrosis and Emerging Therapies

With the increasing burden of liver cirrhosis, the most advanced stage of hepatic fibrosis, there is a need to better understand the pathological processes and mechanisms to target specific treatments to reverse or cease fibrosis progression. Antiviral therapy for hepatitis B and C has effectively treated underlying causes of chronic liver disease and has induced fibrosis reversal in some; however, this has not been targeted for the majority of aetiologies for cirrhosis including alcohol or nonalcoholic steatohepatitis. Fibrosis, characterised by the accumulation of extracellular matrix proteins, is caused by chronic injury from toxic, infectious, or metabolic causes. The primary event of fibrogenesis is increased matrix production and scar formation mediated by the hepatic stellate cell, which is the principal cell type involved. Experimental models using rodent and human cell lines of liver injury have assisted in better understanding of fibrogenesis, especially in recognising the role of procoagulant factors. This has led to interventional studies using anticoagulants in animal models with reversal of fibrosis as the primary endpoint. Though these trials have been encouraging, no antifibrotic therapies are currently licenced for human use. This literature review discusses current knowledge in the pathophysiology of hepatic fibrosis, including characteristics of the extracellular matrix, signalling pathways, and hepatic stellate cells. Current types of experimental models used to induce fibrosis, as well as up-to-date anticoagulant therapies and agents targeting the hepatic stellate cell that have been trialled in animal and human studies with antifibrotic properties, are also reviewed.

Gut Dysbiosis and Increased Intestinal Permeability Drive microRNAs, NLRP-3 Inflammasome and Liver Fibrosis in a Nutritional Model of Non-Alcoholic Steatohepatitis in Adult Male Sprague Dawley Rats

Background/Aim

The interactions between the gut and liver have been described in the progression of non-alcoholic steatohepatitis (NASH). The aim of this study was to develop an experimental nutritional model of NASH simulating metabolic changes occurring in humans.

Materials and Methods

Adult male Sprague Dawley rats were randomized into two groups: controls (standard diet) and intervention (high-fat and choline-deficient diet) for 16 weeks, each experimental group with 10 animals. Biochemical analysis, hepatic lipid content, microRNAs, inflammatory, gut permeability markers and gut microbiota were measured.

Results

Animals in the intervention group showed significantly higher delta Lee index (p=0.017), abdominal circumference (p<0.001), abdominal adipose tissue (p<0.001) and fresh liver weight (p<0.001), as well as higher serum levels of alanine aminotransferase (p=0.010), glucose (p=0.013), total cholesterol (p=0.033), LDL cholesterol (p=0.011), and triglycerides (p=0.011), and lower HDL cholesterol (p=0.006) compared to the control group. Higher TLR4 (p=0.041), TLR9 (p=0.033), MyD88 (p=0.001), Casp1 (p<0.001), NLPR3 (p=0.019), liver inflammation index interleukin (IL)-1β/IL10 (p<0.001), IL6/IL10 (p=0.002) and TNFα/IL10 (p=0.001) were observed in the intervention group, and also lower permeability markers Ocln (p=0.003) and F11r (p=0.041). Gene expression of miR-122 increased (p=0.041) and miR-145 (p=0.010) decreased in the intervention group. Liver steatosis, inflammation and fibrosis, along with collagen fiber deposition increment (p<0.001), were seen in the intervention group. Regarding gut microbiota, Bray-Curtis dissimilarity index and number of operational taxonomic units were significantly different (p<0.001) between the groups. Composition of the gut microbiota showed a significant correlation with histopathological score of NAFLD (r=0.694) and index IL-1β/IL-10 (r=0.522).

Conclusion

This experimental model mimicking human NASH demonstrated gut and liver interaction, with gut microbiota and intestinal permeability changes occurring in parallel with systemic and liver inflammation, miRNAs regulation and liver tissue damage.

Human microbial metabolite mimicry as a strategy to expand the chemical space of potential drugs

The concept of small-molecule mimicry even of weak microbial metabolites present in rodents and humans, as a means to expand drug repertoires, is new. Hitherto, there are few proof-of-concept papers demonstrating utility of this concept. More recently, papers demonstrating mimicry of intestinal microbial metabolites could expand the drug repertoire for diseases such as inflammatory bowel disease (IBD). We opine that, as more functional metabolite-receptor pairings are discovered, small-molecule metabolite mimicry could be a significant effort in drug discovery.

Non-alcoholic fatty liver disease increases the risk of incident chronic kidney disease

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent chronic liver disease. Its role in the development of extrahepatic co-morbidities is under investigation. The impact of NAFLD on the development of chronic kidney disease (CKD) is incompletely understood. The aim of this study was to explore the potential contribution of NAFLD on CKD in Germany.

METHODS

The Disease Analyzer Database covering 7.49 million cases in Germany was explored for patients diagnosed with NAFLD between 2000 and 2015 and was matched 1:1 to a cohort without NAFLD. Matching criteria included age, sex, physician, index year and co-diagnoses associated with CKD. The primary outcomes of this study were incidences of CKD and end-stage renal disease.

RESULTS

A total of 48,057 patients with NAFLD were matched to 48,057 patients without NAFLD. Within 10 years of the index date, 17.1% of patients with NAFLD and 11.6% of patients without NAFLD were diagnosed with CKD (p < 0.001). On Cox regression analysis, NAFLD was significantly associated with the incidence of CKD (hazard ratio (HR) = 1.58, p < 0.001). This association remained significant across different age groups and subgroups such as patients with diabetes mellitus or arterial hypertension. There was no association between NAFLD and emerging dialysis therapy (HR = 1.25, p = 0.245).

CONCLUSIONS

In this large database analysis in Germany, NAFLD constitutes an independent risk factor for CKD. Patients living with NAFLD should be monitored for a change in kidney function, facilitating therapeutic measures for kidney disease at an early stage.

Nutrition and Gastrointestinal Microbiota, Microbial-Derived Secondary Bile Acids, and Cardiovascular Disease

PURPOSE OF REVIEW

The goal is to review the connection between gut microbiota and cardiovascular disease, with specific emphasis on bile acids, and the influence of diet in modulating this relationship.

RECENT FINDINGS

Bile acids exert a much broader range of biological functions than initially recognized, including regulation of cardiovascular function through direct and indirect mechanisms. There is a bi-directional relationship between gut microbiota modulation of bile acid-signaling properties, and their effects on gut microbiota composition. Evidence, primarily from rodent models and limited human trials, suggest that dietary modulation of the gut microbiome significantly impacts bile acid metabolism and subsequently host physiological response(s). Available evidence suggests that the link between diet, gut microbiota, and CVD risk is potentially mediated via bile acid effects on diverse metabolic pathways. However, further studies are needed to confirm/expand and translate these findings in a clinical setting.

Non-alcoholic fatty liver disease and steatohepatitis: State of the art on effective therapeutics based on the gold standard method for diagnosis

Objective

The prevalence of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis (NAFLD/NASH) is increasing. NAFLD/NASH may progress to cirrhosis and hepatocellular carcinoma. However, most patients with NAFLD/NASH will die from a vascular cause. There are no approved pharmacological treatments for NASH/NAFLD. Many clinical trials have been, or are being, undertaken; however, the challenge is the assessment of the clinical endpoint. The main objective of this narrative review was to evaluate the efficacy of drugs used in clinical trials for the treatment of NAFLD/NASH that included a liver biopsy as the gold standard.

Methods

A literature search was conducted using 3 databases (PubMed, Scopus, and Google Scholar) to identify the clinical trials that included liver biopsy assessment before and after treatment.

Results

Interventional clinical trials (n = 33) involving 18 different agents, alone and in combination, were identified. Pioglitazone is the only agent that has shown consistent benefit and efficacy in clinical trials. Pentoxifylline, rosiglitazone, and ursodeoxycholic acid had both positive and negative results from clinical trials. There is also evidence for vitamin E and metformin. Other drugs, including bicyclol, cysteamine bitartrate, l-carnitine, liraglutide, obeticholic acid, oligofructose, selonsertib, silymarin, and statins, each had a single clinical study.

Conclusions

In summary, the available molecules demonstrated a significant improvement in NASH and/or liver fibrosis in a minority of patients; thus, other drugs should be identified, possibly those acting on alternative pathophysiological pathways, and tested for their safety and efficacy.

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There are no currently approved pharmacological treatments for NASH/NAFLD.

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Confirmation of effective therapies for NAFLD/NASH is challenging due to the limitations of non-biopsy methods.

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We reviewed the efficacy of drugs used in NAFLD/NASH trials that included a liver biopsy as the gold standard.

Primary Biliary Cholangitis and Bile Acid Farnesoid X Receptor Agonists

Primary biliary cholangitis (PBC) is a chronic autoimmune liver disease characterized by the progressive destruction of the intrahepatic bile ducts. Currently, the first line drug for PBC is ursodeoxycholic acid (UDCA) characterized by anti-apoptotic, anti-inflammatory and protective actions on cholangiocytes. Despite its recognized therapeutic action, 30–40% of PBC patients only partially benefit from UDCA therapy. This has led to the identification of the role of the farnesoid x receptor (FXR) in cholestatic liver diseases and, consequently, to the development of obeticholic acid (OCA), a steroid FXR agonist that has been recently approved for the treatment of PBC. OCA though is not effective in all patients and can cause itch, which eventually induces treatment drop out. Therefore, the search for new therapeutic strategies for PBC has begun. This review, in addition to summarizing the current treatments for PBC, provides overview of the chemical characteristics of new steroid FXR agonist candidates that could represent a future perspective for the treatment of PBC.

Molecular mechanisms of hepatic insulin resistance in nonalcoholic fatty liver disease and potential treatment strategies

The prevalence of nonalcoholic fatty liver disease (NAFLD) in the general population is estimated at 25 %, and there is currently no effective treatment of NAFLD. Although insulin resistance (IR) is not the only factor causing the pathogenesis of NAFLD, hepatic IR has a cause-effective relationship with NAFLD. Improving hepatic IR is a potential therapeutic strategy to treat NAFLD. This review highlights the molecular mechanisms of hepatic IR in the development of NAFLD. Available data on potential drugs including glucagon-like peptide 1 receptor (GLP-1) agonists, peroxisome proliferator-activated receptor (PPAR-γ/α/δ) agonists, farnesoid X receptor (FXR) agonists, etc. are carefully discussed.

Bile acid-based therapies for non-alcoholic steatohepatitis and alcoholic liver disease

Bile acids are synthesized from cholesterol only in hepatocytes. Bile acids circulating in the enterohepatic system act as physiological detergent molecules to help solubilize biliary cholesterol and emulsify dietary lipids and fat-soluble vitamins in small intestine. Bile acids are signaling molecules that activate nuclear receptor farnesoid X receptor (FXR) and cell surface G protein-coupled receptor TGR5. FXR critically regulates bile acid homeostasis by mediating bile acid feedback inhibition of hepatic bile acid synthesis. In addition, bile acid-activated cellular signaling pathways regulate metabolic homeostasis, immunity, and cell proliferation in various metabolically active organs. In the small and large intestine, gut bacterial enzymes modify primary bile acids to generate secondary bile acids to help shape the bile acid pool composition and subsequent biological effects. In turn, bile acids exhibit anti-microbial properties and modulate gut microbiota to influence host metabolism and immunity. Currently, bile acid-based therapies including systemic and intestine-restricted FXR agonists, TGR5 agonists, fibroblast growth factor 19 analogue, intestine FXR antagonists, and intestine apical sodium-bile acid transporter (ASBT) inhibitors have been developed as promising treatments for non-alcoholic steatohepatitis (NASH). These pharmacological agents improved metabolic and inflammatory disorders via distinct mechanisms of action that are subjects of extensive research interest. More recently, human and experimental alcoholic liver disease (ALD) has been associated with disrupted bile acid homeostasis. In additional, new findings showed that targeting bile acid metabolism and signaling may be promising therapeutic approaches for treating ALD.

Adaptation of Mitochondrial Substrate Flux in a Mouse Model of Nonalcoholic Fatty Liver Disease

Maladaptation of mitochondrial oxidative flux seems to be a considerable feature of nonalcoholic fatty liver disease (NAFLD). The aim of this work was to induce NAFLD in mice fed a Western-style diet (WD) and to evaluate liver mitochondrial functions. Experiments were performed on male C57BL/6J mice fed with a control diet or a WD for 24 weeks. Histological changes in liver and adipose tissue as well as hepatic expression of fibrotic and inflammatory genes and proteins were evaluated. The mitochondrial respiration was assessed by high-resolution respirometry. Oxidative stress was evaluated by measuring lipoperoxidation, glutathione, and reactive oxygen species level. Feeding mice a WD induced adipose tissue inflammation and massive liver steatosis accompanied by mild inflammation and fibrosis. We found decreased succinate-activated mitochondrial respiration and decreased succinate dehydrogenase (SDH) activity in the mice fed a WD. The oxidative flux with other substrates was not affected. We observed increased ketogenic capacity, but no impact on the capacity for fatty acid oxidation. We did not confirm the presence of oxidative stress. Mitochondria in this stage of the disease are adapted to increased substrate flux. However, inhibition of SDH can lead to the accumulation of succinate, an important signaling molecule associated with inflammation, fibrosis, and carcinogenesis.

Transaminases: oldies but goldies. A narrative review

Worldwide, patients are tested for acute and chronic diseases using a series of basic blood assays. The most common liver tests are serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), also called transaminases. These tests are indicators of hepatocellular injury and their increase requires further investigations. The aim of this descriptive review is to highlight and remind the importance of liver transaminases in daily practice. A systematic literature search of the main international databases was performed. We looked for papers that involved transaminases, either in the normal range or in case of increased level and focused on their use in clinical practice. A narrative review of this topic was written. Multiple studies have demonstrated that the presence of an elevated ALT was associated with increased liver-related mortality. The normal ALT level ranges from 29 to 33 IU/L in males and 19 to 25 IU/L in females. The investigations imposed by a high level of transaminases includes testing for viral hepatitis A, B, C and E, assessment for nonalcoholic fatty liver disease and alcoholic liver disease, screening for autoimmune hepatitis, hemochromatosis, Wilson's disease and alpha-1 antitrypsin deficiency. Hepatotoxic drugs consumption also should be excluded. Furthermore, the utility of transaminases is evident in the assessment of the outcome after treatment of each specific liver disease. Beside the role in the first diagnostic step of liver injuries, the utility of liver transaminases is also maintained during the follow-up of liver diseases and in their prognostic assessment.

Characterization of Human Induced Pluripotent Stem Cell-Derived Hepatocytes with Mature Features and Potential for Modeling Metabolic Diseases

There is a strong anticipated future for human induced pluripotent stem cell-derived hepatocytes (hiPS-HEP), but so far, their use has been limited due to insufficient functionality. We investigated the potential of hiPS-HEP as an in vitro model for metabolic diseases by combining transcriptomics with multiple functional assays. The transcriptomics analysis revealed that 86% of the genes were expressed at similar levels in hiPS-HEP as in human primary hepatocytes (hphep). Adult characteristics of the hiPS-HEP were confirmed by the presence of important hepatocyte features, e.g., Albumin secretion and expression of major drug metabolizing genes. Normal energy metabolism is crucial for modeling metabolic diseases, and both transcriptomics data and functional assays showed that hiPS-HEP were similar to hphep regarding uptake of glucose, low-density lipoproteins (LDL), and fatty acids. Importantly, the inflammatory state of the hiPS-HEP was low under standard conditions, but in response to lipid accumulation and ER stress the inflammation marker tumor necrosis factor α (TNFα) was upregulated. Furthermore, hiPS-HEP could be co-cultured with primary hepatic stellate cells both in 2D and in 3D spheroids, paving the way for using these co-cultures for modeling non-alcoholic steatohepatitis (NASH). Taken together, hiPS-HEP have the potential to serve as an in vitro model for metabolic diseases. Furthermore, differently expressed genes identified in this study can serve as targets for future improvements of the hiPS-HEP.

New therapeutic strategies in nonalcoholic fatty liver disease: a focus on promising drugs for nonalcoholic steatohepatitis

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. Globally, it is currently the most common liver disease and is estimated to affect up to 25% of the population. In the first stage, NAFLD is characterized by simple hepatic steatosis (NAFL, nonalcoholic fatty liver) that might progress to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis or hepatocellular carcinoma. In this review, we discuss the global burden of NAFLD, together with future perspectives on how this epidemic could be restrained. There is also an urgent need for the development of new medical strategies for NAFLD patients. We aim to present the beneficial effects of life-style modifications that should be advised to both non-obese and obese NAFLD patients. Since there are currently no medications directly used for the treatment of more advanced NAFLD stages, the central part of this review summarizes ongoing and recently completed clinical trials testing promising drugs for NASH resolution. The marketing of new therapeutic agents would greatly increase the odds of reducing the global burden of NAFLD.

Interaction of the microbiota with the human body in health and diseases

The human body contains many microorganisms, including a large number of bacteria, viruses, fungi, and protozoa, which are referred to as the microbiota. Compared with the number of cells comprising the human body, that of the microbiota has been found to be much larger. The microbiome is defined as microorganisms and their genomes have been shown to contain about 100 times more genes than the human genome. The microbiota affects many vital functions in the human body. It contributes to regulation of the immune system, digestion of food, production of vitamins such as B12 and K, metabolization of xenobiotic materials, and many other tasks. Many factors affect the microbiota biodiversity, such as diet, medicines including antibiotics, relationships with the environment, pregnancy, and age. Studies have shown that the lack of microbiota diversity leads to many diseases like autoimmune diseases such as diabetes type I, rheumatism, muscular dystrophy, problems in blood coagulation due to lack of vitamin K, and disturbances in the transfer of nerve cells due to lack of vitamin B12, in addition to its involvement in a number of conditions such as cancer, memory disorders, depression, stress, autism, and Alzheimer's disease. The aim of this review is to summarize the latest studies discussing the relationship between the microbiota and the human body in health and diseases.

Pharmacologic therapy for nonalcoholic steatohepatitis focusing on pathophysiology

The paradigm of chronic liver diseases has been shifting. Although hepatitis B and C viral infections are still the main causes of liver cirrhosis and hepatocellular carcinoma (HCC), the introduction of effective antiviral drugs may control or cure them in the near future. In contrast, the burden of nonalcoholic fatty liver disease (NAFLD) has been increasing for decades, and 25 to 30% of the general population in Korea is estimated to have NAFLD. Over 10% of NAFLD patients may have nonalcoholic steatohepatitis (NASH), a severe form of NAFLD. NASH can progress to cirrhosis and HCC. NASH is currently the second leading cause to be placed on the liver transplantation list in the United States. NAFLD is associated with obesity, type 2 diabetes, dyslipidemia, and metabolic syndrome. The pathophysiology is complex and associated with lipotoxicity, inflammatory cytokines, apoptosis, and insulin resistance. The only proven effective treatment is weight reduction by diet and exercise. However, this may not be effective for advanced fibrosis or cirrhosis. Therefore, effective drugs are urgently needed for treating these conditions. Unfortunately, no drugs have been approved for the treatment of NASH. Many pharmaceutical companies are trying to develop new drugs for the treatment of NASH. Some of them are in phase 2 or 3 clinical trials. Here, pharmacologic therapies in clinical trials, as well as the basic principles of drug therapy, will be reviewed, focusing on pathophysiology.

Role of the intestinal microbiome in liver fibrosis development and new treatment strategies

Liver cirrhosis is a major cause of morbidity and mortality worldwide. The most common chronic liver diseases in western countries are alcohol-associated liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD). Although these diseases have different causes, liver fibrosis develops via shared mechanisms. The liver and intestinal microbiome are linked by the portal vein and have bidirectional interactions. Changes in the intestinal microbiome contribute to the pathogenesis and progression of liver diseases including ALD, NAFLD, viral hepatitis and cholestatic disorders, based on studies in patients and animal models. Intestinal microbial dysbiosis has been associated with liver cirrhosis and its complications. We review the mechanisms by which alterations in the microbiome contribute to liver fibrosis and discuss microbiome-based treatment approaches.

Dietary and Pharmacological Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the developed world. Simple hepatic steatosis is mild, but the coexistence of steatohepatitis (NASH) and fibrosis increases the risk of hepatocellular carcinoma. Proper dietary and pharmacological treatment is essential for preventing NAFLD progression. The first-line treatment should include dietary intervention and increased physical activity. The diet should be based on the food pyramid, with a choice of products with low glycemic index, complex carbohydrates in the form of low-processed cereal products, vegetables, and protein-rich products. Usage of insulin-sensitizing substances, pro- and prebiotics, and vitamins should also be considered. Such a therapeutic process is intended to support both liver disease and obesity-related pathologies, including insulin resistance, diabetes, dyslipidemia, and blood hypertension. In the pharmacological treatment of NAFLD, apart from pioglitazone, there are new classes of antidiabetic drugs that are of value, such as glucagon-like peptide 1 analogs and sodium/glucose cotransporter 2 antagonists, while several other compounds that target different pathogenic pathways are currently being tested in clinical trials. Liver biopsies should only be considered when there is a lack of decline in liver enzymes after 6 months of the abovementioned treatment. Dietary intervention is recommended in all patients with NAFLD, while pharmacological treatment is recommended especially for those with NASH and showing significant fibrosis in a biopsy.