Role of NADPH oxidases in liver fibrosis

A molecular basis for the anti-inflammatory and anti-fibrosis properties of cannabidiol

Cannabidiol (CBD) is considered a non-psychoactive, antioxidant, and anti-inflammatory compound derived from the Cannabis sativa plant. There are various reports on the versatile function of CBD, including ameliorating chronic inflammation and fibrosis formation in several tissue types. However, only a hand full of studies have proposed or provided a molecular justification for the beneficial properties of this Phyto-compound. This review focused on the anti-inflammation and anti-fibrotic effects of CBD based on modulating the associated chemokines/cytokines and receptor-mediated pathways. We also highlighted the regulatory impact of CBD on reactive oxygen species (ROS) producing-NADPH oxidase (Nox), and ROS scavenging-superoxide dismutase (SOD) enzymes. Although CBD has a low affinity to Cannabinoid receptors 1 and 2 (CB₁ and CB₂ ), we reported on the activation of these receptors by other CBD analogs, and CBD on non-CBD receptors. CBD downregulates pro-inflammatory and pro-fibrotic chemokines/cytokines by acting as direct or indirect agonists of Adenosine A_2A /equilibrative nucleoside transporter receptors, Peroxisome proliferator-activated receptor gamma, and Transient receptor potential vanilloid receptors or channels, and as an antagonist of GPR55 receptors. CBD also caused the reduction and enhancement of the ROS producing, Nox and ROS-scavenging, SOD enzyme activities, respectively. This review thus recommends the continued study of CBD's molecular mechanism in treating established and emerging inflammatory and fibrosis-related diseases.

Alamandine attenuates hepatic fibrosis by regulating autophagy induced by NOX4-dependent ROS

Angiotensin II (Ang II) has been reported to aggravate hepatic fibrosis by inducing NADPH oxidase (NOX)-dependent oxidative stress. Alamandine (ALA) protects against fibrosis by counteracting Ang II via the MAS-related G-protein coupled (MrgD) receptor, though the effects of alamandine on hepatic fibrosis remain unknown. Autophagy activated by reactive oxygen species (ROS) is a novel mechanism of hepatic fibrosis. However, whether autophagy is involved in the regulation of Ang II-induced hepatic fibrosis still requires investigation. We explored the effect of alamandine on hepatic fibrosis via regulation of autophagy by redox balance modulation. In vivo, alamandine reduced CCl4-induced hepatic fibrosis, hydrogen peroxide (H2O2) content, protein levels of NOX4 and autophagy impairment. In vitro, Ang II treatment elevated NOX4 protein expression and ROS production along with up-regulation of the angiotensin converting enzyme (ACE)/Ang II/Ang II type 1 receptor (AT1R) axis. These changes resulted in the accumulation of impaired autophagosomes in hepatic stellate cells (HSCs). Treatment with NOX4 inhibitor VAS2870, ROS scavenger N-acetylcysteine (NAC), and NOX4 small interfering RNA (siRNA) inhibited Ang II-induced autophagy and collagen synthesis. Alamandine shifted the balance of renin-angiotensin system (RAS) toward the angiotensin converting enzyme 2 (ACE2)/alamandine/MrgD axis, and inhibited both Ang II-induced ROS and autophagy activation, leading to attenuation of HSCs migration or collagen synthesis. In summary, alamandine attenuated liver fibrosis by regulating autophagy induced by NOX4-dependent ROS.

The Interplay between Oxidative Stress and miRNAs in Obesity-Associated Hepatic and Vascular Complications

Nowadays, the obesity pandemic is one of the most relevant health issues worldwide. This condition is tightly related to comorbidities such as non-alcoholic fatty liver disease (NAFLD) and cardiovascular diseases (CVDs), namely atherosclerosis. Dysregulated lipid metabolism and inflammation link these three diseases, leading to a subsequent increase of oxidative stress (OS) causing severe cellular damage. On the other hand, microRNAs (miRNAs) are short, single-stranded, non-coding RNAs that act as post-transcriptional negative regulators of gene expression, thus being involved in the molecular mechanisms that promote the development of many pathologies including obesity and its comorbidities. The involvement of miRNAs in promoting or opposing OS in disease progression is becoming more evident. Some miRNAs, such as miR-200a and miR.421, seem to play important roles in OS control in NAFLD. On the other hand, miR-92a and miR-133, among others, are important in the development of atherosclerosis. Moreover, since both diseases are linked to obesity, they share common altered miRNAs, being miR-34a and miR-21 related to OS. This review summarizes the latest advances in the knowledge about the mechanisms of oxidative stress (OS) generation in obesity-associated NAFLD and atherosclerosis, as well as the role played by miRNAs in the regulation of such mechanisms.

Liver fibrogenesis: un update on established and emerging basic concepts

Liver fibrogenesis is defined as a dynamic and highly integrated process occurring during chronic injury to liver parenchyma that can result in excess deposition of extracellular matrix (ECM) components (i.e., liver fibrosis). Liver fibrogenesis, together with chronic inflammatory response, is then primarily involved in the progression of chronic liver diseases (CLD) irrespective of the specific etiology. In the present review we will first offer a synthetic and updated overview of major basic concepts in relation to the role of myofibroblasts (MFs), macrophages and other hepatic cell populations involved in CLD to then offer an overview of established and emerging issues and mechanisms that have been proposed to favor and/or promote CLD progression. A special focus will be dedicated to selected issues that include emerging features in the field of cholangiopathies, the emerging role of genetic and epigenetic factors as well as of hypoxia, hypoxia-inducible factors (HIFs) and related mediators.

Ursolic acid reverses liver fibrosis by inhibiting interactive NOX4/ROS and RhoA/ROCK1 signalling pathways

Liver fibrosis is the reversible deposition of extracellular matrix (ECM) and scar formation after liver damage by various stimuli. The interaction between NOX4/ROS and RhoA/ROCK1 in liver fibrosis is not yet clear. Ursolic acid (UA) is a traditional Chinese medicine with anti-fibrotic effects, but the molecular mechanism underlying these effects is still unclear. We investigated the interaction between NOX4/ROS and RhoA/ROCK1 during liver fibrosis and whether these molecules are targets for the anti-fibrotic effects of UA. First, we confirmed that UA reversed CCl4-induced liver fibrosis. In the NOX4 intervention and RhoA intervention groups, related experimental analyses confirmed the decrease in CCl4-induced liver fibrosis. Next, we determined that the expression of NOX4 and RhoA/ROCK1 was decreased in UA-treated liver fibrotic mice. Furthermore, RhoA/ROCK1 expression was decreased in the NOX4 intervention group, but there was no significant change in the expression of NOX4 in the RhoA intervention group. Finally, we found that liver fibrotic mice showed a decline in their microbiota diversity and abundance, a change in their microbiota composition, and a reduction in the number of potential beneficial bacteria. However, in UA-treated liver fibrotic mice, the microbiota dysbiosis was ameliorated. In conclusion, the NOX4/ROS and RhoA/ROCK1 signalling pathways are closely linked to the development of liver fibrosis. UA can reverse liver fibrosis by inhibiting the NOX4/ROS and RhoA/ROCK1 signalling pathways, which may interact with each other.

Exogenous 8-hydroxydeoxyguanosine ameliorates liver fibrosis through the inhibition of Rac1-NADPH oxidase signaling

BACKGROUND AND AIM

Exogenous 8-hydroxydeoxyguanosine (8-OHdG) was suggested as an inhibitor of Rac1 and NADPH oxidase (NOX). The aim of this study was to evaluate the effects of the exogenous 8-OHdG on hepatic fibrogenesis in vitro and in vivo model of liver fibrosis.

METHODS

Adult Sprague-Dawley rats were allocated to sham-operated rats (n = 7), rats that underwent bile duct ligation (BDL) (n = 6), and BDL rats treated with 8-OHdG (60 mg/kg/day by gavage, n = 6). All rats were sacrificed on day 21. Double immunofluorescence staining between either NOX1 or NOX2 and α-smooth muscle actin (SMA) in liver was performed. Hepatic fibrotic contents were assessed by hydroxyproline assay and quantified by Sirius red staining. In vitro, hepatic stellate cell (HSC) line LX-2 and HHSteC cells were stimulated by angiotensin II (10 μM). The reactive oxygen species (ROS) production was measured by confocal microscopy. The expressions of NOX1, NOX2, α-SMA, transforming growth factor (TGF)-β1, and collagen Iα were analyzed by quantitative real-time polymerase chain reaction or immunoblotting.

RESULTS

The 8-OHdG treatment in BDL rats reduced the NOX1 and NOX2 protein expression, which overlapped with α-SMA compared with BDL rats. The 8-OHdG treatment in BDL rats significantly decreased the mRNA expression of NOX1, NOX2, α-SMA, TGF-β1, and collagen Iα, and fibrotic contents. Increases of ROS production, Rac1 activation, NOX1, NOX2, and fibronectin expression induced by angiotensin II in HSCs were attenuated by 8-OHdG.

CONCLUSIONS

Rac1 activation and NOX-derived ROS are implicated to liver fibrosis. The 8-OHdG ameliorates liver fibrosis through the inhibition of Rac1 activation and NOX-derived ROS.

Hepatoprotective Effects of Pleurotus ostreatus Protein Hydrolysates Yielded by Pepsin Hydrolysis

Pleurotus ostreatus protein extract (POPE) was prepared by the alkali precipitation method with 0.3% (w/v) NaOH. POPEP-III with a MW of 3000–5000 Da was acquired by pepsin enenzymatic hydrolysis. POPEP-III displayed noteworthy effects of 1,1-diphenyl-2-picrylhydrazyl DPPH and H2O2 scavenging activities, Fe2+ chelating ability, lipid peroxidation inhibition capacity, and metal reducing power. The administration of POPEP-III in mice significantly prevented prior CCl4-induced strengthen serum ALT and AST activities, changing from 365.44 ± 36.87 IU/L to 220.23 ± 22.27 IU/L and 352.52 IU/L to 206.75 ± 17.26 IU/L, respectively (p < 0.001), and suppressed hepatic malondialdehyde (MDA) formation from 15.28 ± 3.47 nmol/mg prot to 10.04 ± 2.06 nmol/mg prot (p < 0.001). Mice treated with POPEP-III demonstrated augmented activities of superoxide dismutase (SOD) in the liver, from 187.49 ± 19.81 U/mg prot to 233.35 ± 34.23 U/mg prot, and of glutathione peroxidase (GSH-Px), from 84.01 ± 14.54 U/mg prot to 115.9 ± 16.57 U/mg prot (p < 0.05). POPEP-III also prevented CCl4-induced oxidative liver histological alteration. The results suggest that POPEP-III can protect the liver from CCl4-induced oxidative damage.

CDKN2a/p16 Antagonizes Hepatic Stellate Cell Activation and Liver Fibrosis by Modulating ROS Levels

The lipid-storage hepatic stellate cells (HSC) play as pivotal role in liver fibrosis being able to trans-differentiate into myofibroblasts in response to various pro-fibrogenic stimuli. In the present study we investigated the role of CDKN2a/p16, a negative regulator of cell cycling, in HSC activation and the underlying mechanism. Levels of p16 were significantly down-regulated in activated HSCs isolated from mice induced to develop liver fibrosis compared to quiescent HSCs isolated from the control mice ex vivo. There was a similar decrease in p16 expression in cultured HSCs undergoing spontaneous activation or exposed to TGF-β treatment in vitro. More important, p16 down-regulation was observed to correlate with cirrhosis in humans. In a classic model of carbon tetrachloride (CCl₄) induced liver fibrosis, fibrogenesis was far more extensive in mice with p16 deficiency (KO) than the wild type (WT) littermates. Depletion of p16 in cultured HSCs promoted the synthesis of extracellular matrix (ECM) proteins. Mechanistically, p16 deficiency accelerated reactive oxygen species (ROS) generation in HSCs likely through the p38 MAPK signaling. P38 inhibition or ROS cleansing attenuated ECM production in p16 deficient HSCs. Taken together, our data unveil a previously unappreciated role for p16 in the regulation of HSC activation. Screening for small-molecule compounds that can boost p16 activity may yield novel therapeutic strategies against liver fibrosis.

The mouse HP1 proteins are essential for preventing liver tumorigenesis

Chromatin organization is essential for appropriate interpretation of the genetic information. Here, we demonstrated that the chromatin-associated proteins HP1 are dispensable for hepatocytes survival but are essential within hepatocytes to prevent liver tumor development in mice with HP1β being pivotal in these functions. Yet, we found that the loss of HP1 per se is not sufficient to induce cell transformation but renders cells more resistant to specific stress such as the expression of oncogenes and thus in fine, more prone to cell transformation. Molecular characterization of HP1-Triple KO premalignant livers and BMEL cells revealed that HP1 are essential for the maintenance of heterochromatin organization and for the regulation of specific genes with most of them having well characterized functions in liver functions and homeostasis. We further showed that some specific retrotransposons get reactivated upon loss of HP1, correlating with overexpression of genes in their neighborhood. Interestingly, we found that, although HP1-dependent genes are characterized by enrichment H3K9me3, this mark does not require HP1 for its maintenance and is not sufficient to maintain gene repression in absence of HP1. Finally, we demonstrated that the loss of TRIM28 association with HP1 recapitulated several phenotypes induced by the loss of HP1 including the reactivation of some retrotransposons and the increased incidence of liver cancer development. Altogether, our findings indicate that HP1 proteins act as guardians of liver homeostasis to prevent tumor development by modulating multiple chromatin-associated events within both the heterochromatic and euchromatic compartments, partly through regulation of the corepressor TRIM28 activity.

RNA Profiling Analysis of the Serum Exosomes Derived from Patients with Chronic Hepatitis and Acute-on-chronic Liver Failure Caused By HBV

Hepatitis B virus (HBV) is the main causative viral agent for liver diseases in China. In liver injury, exosomes may impede the interaction with chromatin in the target cell and transmit inflammatory, apoptosis, or regeneration signals through RNAs. Therefore, we attempted to determine the potential functions of exosomal RNAs using bioinformatics technology. We performed RNA sequencing analysis in exosomes derived from clinical specimens of healthy control (HC) individuals and patients with chronic hepatitis B (CHB) and acute-on-chronic liver failure caused by HBV (HBV-ACLF). This analysis resulted in the identification of different types and proportions of RNAs in exosomes from the HC individuals and patients. Exosomes from the CHB and HBV-ACLF patients showed distinct upregulation and downregulation patterns of differentially expressed genes compared with those from the HC subjects. Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes pathway analysis further confirmed different patterns of biological functions and signalling pathways in CHB and HBV-ACLF. Then we chose two upregulated RNAs both in CHB and HBV-ACLF for further qPCR validation. It confirmed the significantly different expression levels in CHB and HBV-ACLF compared with HC. Our findings indicate selective packaging of the RNA cargo into exosomes under different HBV attacks; these may represent potential targets for the diagnosis and treatment of HBV-caused liver injury.

Five Constituents in Psoralea corylifolia L. Attenuate Palmitic Acid-Induced Hepatocyte Injury via Inhibiting the Protein Kinase C-α/Nicotinamide-Adenine Dinucleotide Phosphate Oxidase Pathway

Psoralea corylifolia L. (PC) is a traditional Chinese herb used to treat yang deficiency of the spleen and kidney in pediatric disease. Our previous studies have found that PC can alleviate the liver oxidative stress of juvenile mice with nonalcoholic steatohepatitis (NASH), and its mechanism is related to the inhibition of the protein kinase C-α (PKC-α)/nicotinamide-adenine dinucleotide phosphate oxidase (NOX) signaling pathway. The aim of this study was to confirm the aforementioned drug target in vitro and to conduct preliminary screening for some effective compounds of PC on the treatment of NASH. A primary hepatocyte model of non alcoholic fatty liver disease was established by palmitic acid. The existence of Psoralen, Isopsoralen, Neobavaisoflavone, Isobavachalcone, and Bakuchiol were identified by ultra-performance liquid chromatography. Then, five PC compounds were administered. Intracellular triglyceride and total cholesterol content, the cell supernatant alanine aminotransferase and aspartate aminotransferase, and hepatocellular superoxide anion were examined. The changes of PKC-α/NOX signaling pathways in hepatocytes were also determined. Furthermore, PKC-α activator phorbol 12-myristate 13-acetate was administered for 4 h before Psoralen intervention was conducted again to detect the changes of PKC-α/NOX signaling pathways. Our data demonstrated that Psoralen, Isopsoralen, and Isobavachalcone decreased intracellular content of triglyceride while all five PC compounds improved hepatocellular total cholesterol accumulation and hepatocyte damage in palmitic acid-induced primary hepatocyte model of non alcoholic fatty liver disease. All five PC compounds could also reduce hepatocytic superoxide anion levels, nicotinamide-adenine dinucleotide phosphate/reduced nicotinamide-adenine dinucleotide phosphate ratio, NOX activity as well as p47^phox protein expression and PKCα activation in hepatocytes. Psoralen exhibited the best efficacy but the effectiveness was lost when pre-stimulated by phorbol 12-myristate 13-acetate. The results suggest that Psoralen, Isopsoralen, and Isobavachalcone could improve hepatocyte steatosis; five PC compounds could ameliorate hepatocyte injury, relieve oxidative stress, and downregulate the PKC-α/NOX signaling pathway of hepatocytes. In addition, Psoralen exhibits the best efficacy and a prospective PKC-α inhibitor pharmaceutical activity.

Pathways of hepatic and renal damage through non-classical activation of the renin-angiotensin system in chronic liver disease

In liver cirrhosis, renin-angiotensin system (RAS) activation sustains renal sodium retention and hepatic fibrogenesis. New information has recently enlivened the traditional concept of RAS. For instance, renin and prorenin bind their ubiquitous receptors, resulting in the local production of angiotensin (Ang) II; increased serum calcium and calcimimetic agents, through stimulation of extracellular calcium-sensing receptors (CaSR), blunt renin production and lead to natriuretic effects in human and experimental cirrhosis. Alongside systemic production, there is Ang II tissue production within various organs through RAS enzymes different from angiotensin-converting enzyme (ACE), that is chymase, tissue plasminogen activator and several cathepsins. In experimental cirrhosis, inhibition of chymase leads to natriuretic and hepatic antifibrotic effects, without changes in systemic haemodynamics. In the kidney, local RAS coordinates proximal and distal tubular sodium reabsorption. However, renalase, whose plasma and tissue levels are severely altered in experimental cirrhosis, degrades systemic and renal tubule catecholamines, antagonizing the effects of renal RAS. Angiotensinogen-derived natriuretic and vasodilating peptides (Ang1-9, Ang1-7, Ang3-8) and their receptors have been described. Receptor agonists or antagonists are available to affect portal hypertension and sodium retention in cirrhosis. ACE2-dependent generation of Ang1-7 may inhibit experimental liver fibrosis. inhibition of Ang1-7 clearance by means of neprilysin blockade has portal hypotensive and natriuretic effects. Ang1-12, whose production renin does not regulate, is converted to several different angiotensin peptides via chymase. Finally, Ang II behaves as either an antinatriuretic or a natriuretic agent, based on the tissue content of AT₁ R and AT₂ R receptors, their ratio being prone to pharmacological modulation.

Role of Mitochondria in the Redox Signaling Network and Its Outcomes in High Impact Inflammatory Syndromes

Inflammation is associated with the release of soluble mediators that drive cellular activation and migration of inflammatory leukocytes to the site of injury, together with endothelial expression of adhesion molecules, and increased vascular permeability. It is a stepwise tightly regulated process that has been evolved to cope with a wide range of different inflammatory stimuli. However, under certain physiopathological conditions, the inflammatory response overwhelms local regulatory mechanisms and leads to systemic inflammation that, in turn, might affect metabolism in distant tissues and organs. In this sense, as mitochondria are able to perceive signals of inflammation is one of the first organelles to be affected by a dysregulation in the systemic inflammatory response, it has been associated with the progression of the physiopathological mechanisms. Mitochondria are also an important source of ROS (reactive oxygen species) within most mammalian cells and are therefore highly involved in oxidative stress. ROS production might contribute to mitochondrial damage in a range of pathologies and is also important in a complex redox signaling network from the organelle to the rest of the cell. Therefore, a role for ROS generated by mitochondria in regulating inflammatory signaling was postulated and mitochondria have been implicated in multiple aspects of the inflammatory response. An inflammatory condition that affects mitochondrial function in different organs is the exposure to air particulate matter (PM). Both after acute and chronic pollutants exposure, PM uptake by alveolar macrophages have been described to induce local cell activation and recruitment, cytokine release, and pulmonary inflammation. Afterwards, inflammatory mediators have been shown to be able to reach the bloodstream and induce a systemic response that affects metabolism in distant organs different from the lung. In this proinflammatory environment, impaired mitochondrial function that leads to bioenergetic dysfunction and enhanced production of oxidants have been shown to affect tissue homeostasis and organ function. In the present review, we aim to discuss the latest insights into the cellular and molecular mechanisms that link systemic inflammation and mitochondrial dysfunction in different organs, taking the exposure to air pollutants as a case model.

Mechanisms of liver fibrosis and its role in liver cancer

Hepatic fibrogenesis is a pathophysiological outcome of chronic liver injury hallmarked by excessive accumulation of extracellular matrix proteins. Fibrosis is a dynamic process that involves cross-talk between parenchymal cells (hepatocytes), hepatic stellate cells, sinusoidal endothelial cells and both resident and infiltrating immune cells. In this review, we focus on key cell-types that contribute to liver fibrosis, cytokines, and chemokines influencing this process and what it takes for fibrosis to regress. We discuss how mitochondria and metabolic changes in hepatic stellate cells modulate the fibrogenic process. We also briefly review how the presence of fibrosis affects development of hepatocellular carcinoma.

Hepatic deficiency of Poldip2 in type 2 diabetes dampens lipid and glucose homeostasis

Moderate or low level hydrogen peroxides has been shown to play an important role in vascular smooth muscle cell (VSMC) function, in which the polymerase DNA-directed interacting protein 2 (Poldip2), functioned as a key regulator of NOX4 activity. In current study, we unexpectedly found that type 2 diabetes mellitus (T2DM) substantially suppresses the hepatic Poldip2 expression, and that the hepatic deficiency of Poldip2 may be correlated with dysregulation of hepatic cholesterol and plasma triglycerides. In cultured hepatocytes, we found that both insulin and leptin may inhibit hepatic expression of Poldip2 under high glucose concentration, but these suppressions were totally abolished under normoglycemic condition. POLDIP2 siRNA knockdown significantly impaired the H₂O₂ induction by insulin or leptin under normoglycemic condition, contributing the accumulation of cholesterol in cultured liver cells. The in vivo restoration of hepatic Poldip2 expression in T2DM mice remarkably rescued the moderate H₂O₂ generation in livers versus control mice, resulting in significant amelioration of hepatic cholesterol accumulation and plasma triglyceride levels. Importantly, the moderate induction of H₂O₂ in livers dramatically improved the hepatic PI3K-C₁/AKT signaling or dampened PI3K-C₂γ/AKT signaling through suppression of PTEN and PTP1B activities, thereby inhibiting the hepatic expression of HMGCR and SREBP2 for cholesterol synthesis. Moreover, the restitution of hepatic Poldip2 expression in diabetic mice significantly lowered the VLDL-cholesterol production rate, and substantially suppressed PEPCK and G6Pase expressions for gluconeogenesis, thus significantly improving the plasma insulin and glucose levels, and ITT and GTT outcomes in diabetic mice. Our findings suggest that hepatic dysregulation of Poldip2 may contribute to diabetic dyslipidemia and hyperglycemia.

Digoxin improves steatohepatitis with differential involvement of liver cell subsets in mice through inhibition of PKM2 transactivation

The cardiac glycoside digoxin was identified as a potent suppressor of pyruvate kinase isoform 2-hypoxia-inducible factor-α (PKM2-HIF-1α) pathway activation in liver injury mouse models via intraperitoneal injection. We have assessed the therapeutic effects of digoxin to reduce nonalcoholic steatohepatitis (NASH) by the clinically relevant oral route in mice and analyzed the cellular basis for this effect with differential involvement of liver cell subsets. C57BL/6J male mice were placed on a high-fat diet (HFD) for 10 wk and started concurrently with the gavage of digoxin (2.5, 0.5, 0.125 mg/kg twice a week) for 5 wk. Digoxin significantly reduced HFD-induced hepatic damage, steatosis, and liver inflammation across a wide dosage range. The lowest dose of digoxin (0.125 mg/kg) showed significant protective effects against liver injury and sterile inflammation. Consistently, digoxin attenuated HIF-1α sustained NLRP3 inflammasome activation in macrophages. We have reported for the first time that PKM2 is upregulated in hepatocytes with hepatic steatosis, and digoxin directly improved hepatocyte mitochondrial dysfunction and steatosis. Mechanistically, digoxin directly bound to PKM2 and inhibited PKM2 targeting HIF-1α transactivation without affecting PKM2 enzyme activation. Thus, oral digoxin showed potential to therapeutically inhibit liver injury in NASH through the regulation of PKM2-HIF-1α pathway activation with involvement of multiple cell types. Because of the large clinical experience with oral digoxin, this may have significant clinical applicability in human NASH.NEW & NOTEWORTHY This study is the first to assess the therapeutic efficacy of oral digoxin on nonalcoholic steatohepatitis (NASH) in a high-fat diet (HFD) mouse model and to determine the divergent of cell type-specific effects. Oral digoxin reduced liver damage, steatosis, and inflammation in HFD mice. Digoxin attenuated hypoxia-inducible factor (HIF)-1α axis-sustained inflammasome activity in macrophages and hepatic oxidative stress response in hepatocytes via the regulation of PKM2-HIF-1α axis pathway activation. Oral digoxin may have significant clinical applicability in human NASH.

Protective role of melatonin in early-stage and end-stage liver cirrhosis

The liver is composed of hepatocytes, cholangiocytes, Kupffer cells, sinusoidal endothelial cells, hepatic stellate cells (HSCs) and dendritic cells; all these functional and interstitial cells contribute to the synthesis and secretion functions of liver tissue. However, various hepatotoxic factors including infection, chemicals, high‐fat diet consumption, surgical procedures and genetic mutations, as well as biliary tract diseases such as sclerosing cholangitis and bile duct ligation, ultimately progress into liver cirrhosis after activation of fibrogenesis. Melatonin (MT), a special hormone isolated from the pineal gland, participates in regulating multiple physiological functions including sleep promotion, circadian rhythms and neuroendocrine processes. Current evidence shows that MT protects against liver injury by inhibiting oxidation, inflammation, HSC proliferation and hepatocyte apoptosis, thereby inhibiting the progression of liver cirrhosis. In this review, we summarize the circadian rhythm of liver cirrhosis and its potential mechanisms as well as the therapeutic effects of MT on liver cirrhosis and earlier‐stage liver diseases including liver steatosis, nonalcoholic fatty liver disease and liver fibrosis. Given that MT is an antioxidative and anti‐inflammatory agent that is effective in eliminating liver injury, it is a potential agent with which to reverse liver cirrhosis in its early stage.

High nuclear NADPH oxidase 4 expression levels are correlated with cancer development and poor prognosis in hepatocellular carcinoma

NADPH oxidase (NOX) is a key source of reactive oxygen species (ROS). This study aimed to verify NOX2 and NOX4 expression levels in hepatocellular carcinoma (HCC). A total of 134 matched pairs of HCC cells and non-tumour hepatocytes from 134 patients were examined by immunohistochemical staining, and the association of NOX2 and NOX4 expression with clinicopathological parameters was analysed. Western blotting in four HCC cell lines and reverse transcription digital droplet polymerase chain reaction (RT-ddPCR) in 20 pairs of HCC and non-tumour tissue samples were also performed to detect NOX4. Cytoplasmic NOX2 and nuclear NOX4 expression levels were shown by immunohistochemistry to be higher in HCC cells than in non-tumour hepatocytes (p<0.001 each). The western blotting results for NOX4 in four HCC cell lines were consistent with the immunohistochemical results. Increased cytoplasmic expression of NOX2 and NOX4 in HCC cells was significantly correlated with liver cirrhosis (p<0.001 and p<0.031, respectively). However, decreased cytoplasmic expression of NOX2 and NOX4 was significantly correlated with advanced pathological TNM stage (p<0.029 and p<0.007, respectively). Multivariate analysis with clinicopathological parameters showed that high nuclear and low cytoplasmic NOX4 expression levels are correlated with short overall survival (p=0 .021). Our findings imply that cytoplasmic NOX2 and nuclear NOX4 expression is upregulated during HCC development. In particular, NOX4 translocation into the nucleus may affect the development and progression of HCC. NOX2 and NOX4 could be diagnostic markers and have therapeutic implications in HCC.

Protective Effect of Ursolic Acid on the Intestinal Mucosal Barrier in a Rat Model of Liver Fibrosis

Oxidative stress mediated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) plays an important role in intestinal mucosal barrier damage in various disease states. Recent evidence suggests that intestinal mucosal barrier damage and intestinal dysbiosis occur in mice with hepatic fibrosis induced by CCl4 or bile duct ligation. Another study showed that ursolic acid (UA) attenuates experimental colitis via its anti-inflammatory and antioxidant activities. The goal of this study was to investigate the effects of UA on the intestinal mucosal barrier in CCl4-induced hepatic fibrosis in rats and identify its associated mechanisms. Male Sprague-Dawley rats were randomly divided into the following 3 groups (n = 10/group): the control, CCl4 model and UA treatment groups. Rats were sacrificed at 72 h after the hepatic fibrosis model was established and assessed for liver fibrosis, intestinal injury, enterocyte apoptosis, bacterial translocation, system inflammation, intestinal oxidative stress, and tight junction protein and NOX protein expression. The results demonstrated that UA attenuated the following: (i) liver and intestinal pathological injury; (ii) cleaved caspase-3 expression in the ileal epithelial cells; (iii) serum lipopolysaccharide and procalcitonin levels; (iv) intestinal malondialdehyde levels; and (v) the expression of the NOX protein components NOX2 and P67phox in ileal tissues. Furthermore, our results suggested that UA improved intestinal dysbiosis and the expression of the tight junction proteins Claudin 1 and Occludin in the ileum of rats. These results indicate that UA has protective effects on the intestinal mucosal barrier in rats with CCl4-induced liver fibrosis by inhibiting intestinal NOX-mediated oxidative stress. Our findings may provide a basis for further clinical studies of UA as a novel and adjuvant treatment to cure liver fibrosis.

Inhibitory Effect of Sestrin 2 on Hepatic Stellate Cell Activation and Liver Fibrosis

Aims: Hepatic fibrosis results from chronic liver injury and inflammatory responses. Sestrin 2 (Sesn2), an evolutionarily conserved antioxidant enzyme, reduces the severities of acute hepatitis and metabolic liver diseases. However, the role of Sesn2 in the pathogenesis of liver fibrosis remains obscure. Here, we used cultured hepatic stellate cells (HSCs) and chronic carbon tetrachloride (CCl₄) and bile duct ligation (BDL) murine models to investigate the effects of Sesn2 on fibrogenesis. Results: Sesn2 protein and mRNA levels were upregulated in activated primary HSCs, and by increasing transcription, transforming growth factor-β (TGF-β) also increased Sesn2 expression in HSCs. Furthermore, Smad activation was primarily initiated by TGF-β signaling, and Smad3 activation increased Sesn2 luciferase activity. In silico analysis of the 5' upstream region of the Sesn2 gene revealed a putative Smad-binding element (SBE), and its deletion demonstrated that the SBE between -964 and -956 bp within human Sesn2 promoter was critically required for TGF-β-mediated response. Moreover, ectopic expression of Sesn2 reduced gene expressions associated with HSC activation, and this was accompanied by marked decreases in SBE luciferase activity and Smad phosphorylation. Infection of recombinant adenovirus Sesn2 reduced hepatic injury severity, as evidenced by reductions in CCl₄- or BDL-induced alanine aminotransferase and aspartate aminotransferase, and inhibited collagen accumulation. Furthermore, HSC-specific lentiviral delivery of Sesn2 prevented CCl₄-induced liver fibrosis. Finally, Sesn2 expression was downregulated in the livers of patients with liver cirrhosis and in mouse models of hepatic fibrosis. Innovation and Conclusion: Our findings suggest that Sesn2 has the potential to inhibit HSC activation and hepatic fibrosis.

Xian-Ling-Gu-Bao induced inflammatory stress rat liver injury: Inflammatory and oxidative stress playing important roles

ETHNOPHARMACOLOGICAL RELEVANCE

Xian-Ling-Gu-Bao (XLGB) Fufang is an herbal formula that has been used in clinical settings to treat osteoporosis, osteoarthritis, aseptic bone necrosis, and climacteric syndrome. Despite its uses, XLGB treatment has been linked to potential liver injury. To date, there is a lack of clear demonstration of such toxicity in animal models.

AIM OF THE STUDY

As animal models fail to reproduce the XLGB hepatotoxicity reported in humans, because human hepatocytes are clearly more sensitive to XLGB, this study was designed to investigate a more reliable animal model of such toxicity.

MATERIALS AND METHODS

We randomized rats into five groups, as follows: CON (control), XLGB, lipopolysaccharide (LPS), L-XLGB/LPS (XLGB, 0.125 g/kg; LPS, 0.1 mg/kg), and XLGB/LPS (XLGB, 1.25 g/kg; LPS, 0.1 mg/kg). These groups were treated with 0.5% sodium carboxymethyl cellulose (CMC-Na), XLGB suspension, normal saline, or LPS. The first administration of XLGB [0.125 g/kg or 1.25 g/kg, by mouth (PO)] or its solvent (0.5% CMC-Na) was delivered, and then food was removed. Twelve hours after the first administration of XLGB, rats received LPS [0.1 mg/kg, intravenously (IV)] or saline control. After 30 min, a second administration of XLGB (0.125 g/kg or 1.25 g/kg, PO) or solvent was administered. The rats were anesthetized at 12 h or 24 h following the second administration of XLGB. Liver function was evaluated by measuring liver weight, liver microscopy, serum biochemistry and plasma microRNA-122 (miR-122). The plasma levels of 27 cytokines were measured to evaluate inflammation. Moreover, the expression of cytochrome P450 2E1 (CYP2E1), nicotinic adenine dinucleotide phosphate (NADPH) oxidase and inducible nitric oxide synthase (iNOS) at protein levels were observed; immunofluorescence and immunohistochemistry were used to confirmed the hepatotoxicity of XLGB.

RESULTS

Hepatotoxicity in male rats with moderate inflammation induced by XLGB was indicated by liver histopathology, serum biochemical analysis, serum miR-122 levels, and immunofluorescent assessments. We observed significant increases in liver weight and liver indexes in male rats with moderate inflammation in response to XLGB. Histopathological assessment further showed that extensive hepatocellular necrosis and inflammatory infiltration were evident in rats co-treated with XLGB/LPS. The levels of serum transaminases [alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT)], total bilirubin (TBIL) and triglyceride (TG), which are markers of liver function, were also significantly increased by XLGB/LPS treatment. Similarly, miR-122 was significantly elevated in XLGB/LPS treated rats relative to other groups. An immunofluorescent assessment showed extensive apoptosis in hepatocytes from these co-treated rats. What is more, XLGB can dose-dependently induce liver injury in male rats with moderate inflammation. Hepatic CYP2E1, neutrophil chemotactic factor (NCF-1), iNOS, and NOX-2 (an NADPH oxidase subunit) levels were increased in response to XLGB treatment, and staining for DMPO nitrone adducts further showed elevated oxidative stress level in XLGB/LPS-treated rats relative to the other experimental groups.

CONCLUSION

LPS and XLGB co-treatment in rats led to marked hepatotoxicity. This toxicity was associated with disrupted lipid metabolism, extensive liver necrosis and inflammatory infiltration, apoptosis, and expression of oxidative stress-related proteins. These results demonstrate a valuable model for the study of iDILI in the context of XLGB treatment, and further provide insights into the potential mechanisms by which XLGB may induce hepatotoxicity in humans.

Protein tyrosine phosphatase 1b deficiency protects against hepatic fibrosis by modulating nadph oxidases

Inflammation is typically associated with the development of fibrosis, cirrhosis and hepatocellular carcinoma. The key role of protein tyrosine phosphatase 1B (PTP1B) in inflammatory responses has focused this study in understanding its implication in liver fibrosis. Here we show that hepatic PTP1B mRNA expression increased after bile duct ligation (BDL), while BDL-induced liver fibrosis was markedly reduced in mice lacking Ptpn1 (PTP1B^−/−) as assessed by decreased collagen deposition and α-smooth muscle actin (α-SMA) expression. PTP1B^−/− mice also showed a significant increase in mRNA levels of key markers of monocytes recruitment (Cd68, Adgre1 and Ccl2) compared to their wild-type (PTP1B^+/+) littermates at early stages of injury after BDL. Interestingly, the lack of PTP1B strongly increased the NADPH oxidase (NOX) subunits Nox1/Nox4 ratio and downregulated Cybb expression after BDL, revealing a pro-survival pattern of NADPH oxidase induction in response to liver injury. Chimeric mice generated by transplantation of PTP1B^−/− bone marrow (BM) into irradiated PTP1B^+/+ mice revealed similar hepatic expression profile of NOX subunits than PTP1B^−/− mice while these animals did not show differences in infiltration of myeloid cells at 7 days post-BDL, suggesting that PTP1B deletion in other liver cells is necessary for boosting the early inflammatory response to the BDL. PTP1B^−/− BM transplantation into PTP1B^+/+ mice also led to a blockade of TGF-β and α-SMA induction after BDL. In vitro experiments demonstrated that deficiency of PTP1B in hepatocytes protects against bile acid-induced apoptosis and abrogates hepatic stellate cells (HSC) activation, an effect ameliorated by NOX1 inhibition. In conclusion, our results have revealed that the lack of PTP1B switches NOX expression pattern in response to liver injury after BDL and reduces HSC activation and liver fibrosis.

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PTP1B deficiency in mice ameliorates liver damage induced by cholestasis.

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The increased NOX1/NOX4 ratio in livers from PTP1B^-/- mice was associated with protection against BDL-induced fibrosis.

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The lack of PTP1B exacerbates macrophage recruitment upon BDL which is dispensable for ameliorating cholestatic liver damage.

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Resistance of PTP1B^-/- hepatocytes against bile acid-induced apoptosis protects from HSC activation in a NOX1-dependent manner.

ERK Pathway in Activated, Myofibroblast-Like, Hepatic Stellate Cells: A Critical Signaling Crossroad Sustaining Liver Fibrosis. Int J Mol Sci. 2019;20. [PMID: 31159366 PMCID: PMC6600376 DOI: 10.3390/ijms20112700]

Fibrogenic progression of chronic liver disease, whatever the etiology, is characterized by persistent chronic parenchymal injury, chronic activation of inflammatory response, and sustained activation of liver fibrogenesis, and of pathological wound healing response. A critical role in liver fibrogenesis is played by hepatic myofibroblasts (MFs), a heterogeneous population of α smooth-muscle actin—positive cells that originate from various precursor cells through a process of activation and transdifferentiation. In this review, we focus the attention on the role of extracellular signal-regulated kinase (ERK) signaling pathway as a critical one in modulating selected profibrogenic phenotypic responses operated by liver MFs. We will also analyze major therapeutic antifibrotic strategies developed in the last two decades in preclinical studies, some translated to clinical conditions, designed to interfere directly or indirectly with the Ras/Raf/MEK/ERK signaling pathway in activated hepatic MFs, but that also significantly increased our knowledge on the biology and pathobiology of these fascinating profibrogenic cells.

Interaction Mechanisms Between the NOX4/ROS and RhoA/ROCK1 Signaling Pathways as New Anti- fibrosis Targets of Ursolic Acid in Hepatic Stellate Cells

Background

Studies have shown that both NOX4 and RhoA play essential roles in fibrosis and that they regulate each other. In lung fibrosis, NOX4/ROS is located upstream of the RhoA/ROCK1 signaling pathway, and the two molecules are oppositely located in renal fibrosis. Currently, no reports have indicated whether the above mechanisms or other regulatory mechanisms exist in liver fibrosis.

Objectives

To investigate the effects of the NOX4/ROS and RhoA/ROCK1 signaling pathways on hepatic stellate cell (HSC)-T6 cells, the interaction mechanisms of the two pathways, and the impact of UA on the two pathways to elucidate the role of UA in the reduction of hepatic fibrosis and potential mechanisms of HSC-T6 cell proliferation, migration, and activation.

Methods

Stable cell lines were constructed using the lentiviral transduction technique. Cell proliferation, apoptosis, migration, and invasion were examined using the MTS, TdT-mediated dUTP nick-end labeling, cell scratch, and Transwell invasion assays, respectively. The DCFH-DA method was used to investigate the ROS levels in each group. RT-qPCR and western blotting techniques were utilized to assess the mRNA and protein expression in each group. CoIP and the Biacore protein interaction analysis systems were used to evaluate protein interactions.

Results

The NOX4/ROS and RhoA/ROCK1 signaling pathways promoted the proliferation, migration, and activation of HSCs. UA inhibited cell proliferation, migration, and activation by inhibiting the activation of the two signaling pathways, but the mechanism of apoptosis was independent of these two pathways. The NOX4/ROS pathway was upstream of and positively regulated the RhoA/ROCK1 pathway in HSCs. No direct interaction between the NOX4 and RhoA proteins was detected.

Conclusion

The NOX4/ROS and RhoA/ROCK1 signaling pathways are two critical signaling pathways in a series of behavioral processes in HSCs, and NOX4/ROS regulates RhoA/ROCK1 through an indirect pathway to control the activation of HSCs. Additionally, NOX4/ROS and RhoA/ROCK1 constitute a new target for UA antifibrosis treatment.

Spirulina platensis and silicon-enriched spirulina equally improve glucose tolerance and decrease the enzymatic activity of hepatic NADPH oxidase in obesogenic diet-fed rats

The prevalence of metabolic syndrome components, such as obesity, glucose intolerance and hepatic steatosis, is rapidly increasing and becoming a major issue of public health. The present work was designed to determine the effects of Spirulina platensis (Sp) algae and silicon-enriched Sp on major metabolic syndrome components in obesogenic diet-fed rats. Forty male Wistar rats were divided into 4 groups. Ten rats were fed a control diet and 30 rats were fed a high fat (HF) diet. The HF groups were divided into three groups and supplemented with placebo or Sp or Si-enriched Sp for 12 weeks. Dietary intake and body weight were recorded. Oral glucose tolerance test and surrogate metabolic syndrome (insulin, leptin, adiponectin and lipids), mitochondrial function (enzymatic activity of respiratory chain complexes and β-hydroxyacyl-CoA dehydrogenase), NADPH oxidase activity and several long-established oxidative stress markers were measured in the blood and liver. The HF diet induced obesity, glucose intolerance, hepatic steatosis and huge metabolic alterations, associated with higher NADPH oxidase activity and lower hepatic sulfhydryl group and glutathione contents. Otherwise, the Sp and Sp + Si supplements showed some interesting effects on rat characteristics and particularly on blood and hepatic metabolic parameters. Indeed, the intake of Sp or Sp + Si mainly improved glucose tolerance and decreased the enzymatic activity of hepatic NADPH oxidase. Overall, Si supplementation of spirulina does not appear to have more beneficial effects than spirulina alone. Other experiments with different species of rats/mice, different diets or different durations of diet intake should be undertaken to confirm or invalidate these results.

NADPH Oxidase 1 in Liver Macrophages Promotes Inflammation and Tumor Development in Mice

BACKGROUND & AIMS

Although there are associations among oxidative stress, reduced nicotinamide adenine dinucleotide phosphate oxidase (NOX) activation, and hepatocellular carcinoma (HCC) development, it is not clear how NOX contributes to hepatocarcinogenesis. We studied the functions of different NOX proteins in mice after administration of a liver carcinogen.

METHODS

Fourteen-day-old Nox1^-/- mice, Nox4^-/- mice, Nox1^-/-Nox4^-/- (double-knockout) mice, and wild-type (WT) C57BL/6 mice were given a single intraperitoneal injection of diethylnitrosamine (DEN) and liver tumors were examined at 9 months. We also studied the effects of DEN in mice with disruption of Nox1 specifically in hepatocytes (Nox1^ΔHep), hepatic stellate cells (Nox1^ΔHep), or macrophages (Nox1^ΔMac). Some mice were also given injections of the NOX1-specific inhibitor ML171. To study the acute effects of DEN, 8-12-week-old mice were given a single intraperitoneal injection, and liver and serum were collected at 72 hours. Liver tissues were analyzed by histologic examination, quantitative polymerase chain reaction, and immunoblots. Hepatocytes and macrophages were isolated from WT and knockout mice and analyzed by immunoblots.

RESULTS

Nox4^-/- mice and WT mice developed liver tumors within 9 months after administration of DEN, whereas Nox1^-/- mice developed 80% fewer tumors, which were 50% smaller than those of WT mice. Nox1^ΔHep and Nox1^ΔHSC mice developed liver tumors of the same number and size as WT mice, whereas Nox1^ΔMac developed fewer and smaller tumors, similar to Nox1^-/- mice. After DEN injection, levels of tumor necrosis factor, interleukin 6 (IL6), and phosphorylated signal transducer and activator of transcription 3 were increased in livers from WT, but not Nox1^-/- or Nox1^ΔMac, mice. Conditioned medium from necrotic hepatocytes induced expression of NOX1 in cultured macrophages, followed by expression of tumor necrosis factor, IL6, and other inflammatory cytokines; this medium did not induce expression of IL6 or cytokines in Nox1^ΔMac macrophages. WT mice given DEN followed by ML171 developed fewer and smaller liver tumors than mice given DEN followed by vehicle.

CONCLUSIONS

In mice given injections of a liver carcinogen (DEN), expression of NOX1 by macrophages promotes hepatic tumorigenesis by inducing the production of inflammatory cytokines. We propose that upon liver injury, damage-associated molecular patterns released from dying hepatocytes activate liver macrophages to produce cytokines that promote tumor development. Strategies to block NOX1 or these cytokines might be developed to slow hepatocellular carcinoma progression.

Unmet needs in pediatric NAFLD research: what do we need to prioritize for the future?

Pediatric nonalcoholic fatty liver disease (NAFLD) is common disorder that has complex pathophysiology and unquantified clinical significance. Though there have been major advances in the field, there is much yet to be understood. Areas covered: PubMed/MEDLINE and Embase were searched for articles related to pediatric NAFLD and nonalcoholic steatohepatitis (NASH) between January 1998 and January 2018. The areas considered to be 'unmet needs' were the relationship between the intestinal microbiome and perinatal events, clinical event risk stratification, and mechanisms underlying portal inflammation. Expert commentary: In utero and ex utero factors have been associated with NAFLD and also with the intestinal microbiome, but it is not yet known how intestinal dysbiosis can be reversed and whether intervention in high-risk neonates could alter their propensity for the metabolic syndrome. Children with NAFLD are at increased risk of cardiovascular, diabetic, and hepatic diseases, but it is unclear how best to stratify children into appropriate risk groups for targeted interventions. Finally, the immune processes underlying pediatric NASH are thought to differ to those in adult NASH, yet the events surrounding activation of periportal lymphocytes are poorly understood. Deepening our understanding of these topics may lead to novel therapeutic targets.

Ursolic acid ameliorates CCl4-induced liver fibrosis through the NOXs/ROS pathway

Liver fibrosis is a reversible wound-healing response that occurs after liver injury. NADPH oxidases (NOXs) and reactive oxygen species (ROS) which are expressed in hepatocytes (HCs), hepatic stellate cells (HSCs), and Kupffer cells (KCs) play an important role in the development of hepatic fibrosis. In in vitro studies, we had shown that ursolic acid (UA) could reverse liver fibrosis by inhibiting the activation of NOX-mediated fibrotic signaling networks in HSCs. In this study, we verified that UA could alleviate CCl4-induced liver fibrosis by reducing the expression of NOXs/ROS in HCs, HSCs, KCs. Meanwhile, the phagocytic index α and clearance index K which represent phagocytosis of KCs were unchanged. Together, all our data demonstrated that UA induced the proliferation of HCs, promoted apoptosis in HSCs, and prevented activation of KCs in vivo by reducing the expression of NOXs/ROS in HCs, HSCs, KCs. Besides, UA had no effect on the host defense function.

Angiotensin (1-7) inhibits arecoline-induced migration and collagen synthesis in human oral myofibroblasts via inhibiting NLRP3 inflammasome activation

Arecoline induces oral submucous fibrosis (OSF) via promoting the reactive oxygen species (ROS). Angiotensin (1-7) (Ang-(1-7)) protects against fibrosis by counteracting angiotensin II (Ang-II) via the Mas receptor. However, the effects of Ang-(1-7) on OSF remain unknown. NOD-like receptors (NLRs) family pyrin domain containing 3 (NLRP3) inflammasome is identified as the novel mechanism of fibrosis. Whereas the effects of arecoline on NLRP3 inflammasome remain unclear. We aimed to explore the effect of Ang-(1-7) on NLRP3 inflammasome in human oral myofibroblasts. In vivo, activation of NLRP3 inflammasomes with an increase of Ang-II type 1 receptor (AT1R) protein level and ROS production in human oral fibrosis tissues. Ang-(1-7) improved arecoline-induced rats OSF, reduced protein levels of NADPH oxidase 4 (NOX4) and the NLRP3 inflammasome. In vitro, arecoline increased ROS along with upregulation of the angiotensin-converting enzyme (ACE)/Ang-II/AT1R axis and NLRP3 inflammasome/interleukin-1β axis in human oral myofibroblasts, which were reduced by NOX4 inhibitor VAS2870, ROS scavenger N-acetylcysteine, and NOX4 small interfering RNA (siRNA). Furthermore, arecoline induced collagen synthesis or migration via the Smad or RhoA-ROCK pathway respectively, which could be inhibited by NLRP3 siRNA or caspase-1 blocker VX-765. Ang-(1-7) shifted the balance of RAS toward the ACE2/Ang-(1-7)/Mas axis, inhibited arecoline-induced ROS and NLRP3 inflammasome activation, leading to attenuation of migration or collagen synthesis. In summary, Ang-(1-7) attenuates arecoline-induced migration and collagen synthesis via inhibiting NLRP3 inflammasome in human oral myofibroblasts.

Transforming Growth Factor-β-Induced Cell Plasticity in Liver Fibrosis and Hepatocarcinogenesis

The Transforming Growth Factor-beta (TGF-β) family plays relevant roles in the regulation of different cellular processes that are essential for tissue and organ homeostasis. In the case of the liver, TGF-β signaling participates in different stages of disease progression, from initial liver injury toward fibrosis, cirrhosis and cancer. When a chronic injury takes place, mobilization of lymphocytes and other inflammatory cells occur, thus setting the stage for persistence of an inflammatory response. Macrophages produce profibrotic mediators, among them, TGF-β, which is responsible for activation -transdifferentiation- of quiescent hepatic stellate cells (HSC) to a myofibroblast (MFB) phenotype. MFBs are the principal source of extracellular matrix protein (ECM) accumulation and prominent mediators of fibrogenesis. TGF-β also mediates an epithelial-mesenchymal transition (EMT) process in hepatocytes that may contribute, directly or indirectly, to increase the MFB population. In hepatocarcinogenesis, TGF-β plays a dual role, behaving as a suppressor factor at early stages, but contributing to later tumor progression, once cells escape from its cytostatic effects. As part of its potential pro-tumorigenic actions, TGF-β induces EMT in liver tumor cells, which increases its pro-migratory and invasive potential. In parallel, TGF-β also induces changes in tumor cell plasticity, conferring properties of a migratory tumor initiating cell (TIC). The main aim of this review is to shed light about the pleiotropic actions of TGF-β that explain its effects on the different liver cell populations. The cross-talk with other signaling pathways that contribute to TGF-β effects, in particular the Epidermal Growth Factor Receptor (EGFR), will be presented. Finally, we will discuss the rationale for targeting the TGF-β pathway in liver pathologies.

NADPH oxidase, oxidative stress and fibrosis in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by damage of small vessels, immune abnormalities and exaggerated production of extracellular matrix. The etiology of the disease is unknown and the pathogenesis ill defined. However, there is consistent evidence that oxidative stress contributes to the establishment and progression of the disease. This review examines the most relevant research regarding the involvement of free radicals and of nicotinamide adenine dinucleotide phosphate oxidases (NADPH oxidases; NOX) in the pathogenesis of systemic sclerosis.

Establishment and Comparison of Juvenile Female Mouse Models of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis

Experimental research has successfully established an adult offspring animal model of nonalcoholic fatty liver disease (NAFLD), but the female offspring model of NAFLD in young age has not been well characterized yet. The aim of this study was to present a direct comparison of the maternal versus postweaning female juvenile NAFLD and nonalcoholic steatohepatitis (NASH) animal models. Four different female mouse models were established and compared using different high-fat diet feeding (HF) strategies in maternal mice and their offspring. The models were non-HF maternal mice and HF offspring with high-high fat (C/HHF), non-HF maternal mice and HF offspring with low-high fat (C/LHF), HF maternal mice and offspring both with high-high fat (HHF/HHF), and HF maternal mice and offspring both with low-high fat (LHF/LHF). A female control group (C/C) was also established. The offspring mice were raised to the age of 8 weeks and then euthanized. Blood glucose levels, lipid profiles, liver function, and triglycerides/total cholesterol contents were examined. Hepatic morphology and superoxide anion levels were evaluated. The nicotinamide-adenine dinucleotide phosphate activity and related regulatory subunits protein expression in the liver tissue were also determined. Our data demonstrated that offspring fat intake contributed to the successful establishment of NAFLD and maternal-offspring fat intake contributed to the successful establishment of NASH in juvenile female mice. Offspring high-fat exposure might be associated with the development of NAFLD and maternal high-fat exposure might be associated with the development of NASH in juvenile female offspring. Higher calories from a fat diet program (both in maternal and offspring) are more prone to inducing liver injury in offspring. In addition, the combination of the aforementioned two factors could aggravate this process. Moreover, oxidative stress was prominent in the juvenile female mouse model of NAFLD/NASH, and the mechanism might be related to the activation of liver NADPH oxidase.

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) and liver fibrosis: A review

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are key producer of reactive oxygen species in liver cells. Hepatic stellate cells (HSCs) and Kupffer cells (KCs) are the two key cells for expression of NOX in liver. KCs produce only NOX2, while HSCs produce NOX1, 2, and 4, all of which play essential roles in the process of fibrogenesis within liver. These NOX subtypes are contributed to induction of liver fibrosis by acting through multiple pathways including induction of HSC activation, proliferation, survival and migration, stimulation of hepatocyte apoptosis, enhancement of fibrogenic mediators, and mediation of an inflammatory cascade in both KCs and HSCs.

SIGNIFICANCE

KCs and HSCs are two key cells for production of NOX in liver in relation to the pathology of liver fibrosis. NOX subtypes 1, 2, and 4 are inducers of fibrogenesis in liver. NOX activation favors hepatocyte apoptosis, HSC activation, and KC-mediated inflammatory cascade in liver, all of which are responsible for generation of liver fibrosis.

Methyl ferulic acid exerts anti-apoptotic effects on L-02 cells via the ROS-mediated signaling pathway

The present study aimed to investigate the anti-apoptotic effects of methyl ferulic acid (MFA) on L-02 cell apoptosis induced by ethanol, and to elucidate the possible underlying mechanisms. L-02 cells were examined after being soaked in ethanol (400 mM) to allow the ethanol to permeate into the cells for 24 h. Cell survival was measured by MTT assay. Cell apoptosis was assessed by both flow cytometry and single-stranded DNA assays. Intracellular reactive oxygen species (ROS) production was determined using the 2',7'-dichlorofluorescein-diacetate dye. The protein expression levels of p38, p-p38, JNK, p-JNK, NADPH oxidase 4 (NOX4), p22, Bax and Bcl-2 were measured by western blot analysis. The mRNA expression levels of NOX4 and p22 were measured by RT-PCR. It was identified that MFA markedly suppressed the ethanol-induced apoptosis and necrosis of L-02 cells. In addition, MFA decreased the expression levels of superoxide dismutase, catalase and phospholipid hydroperoxide gluthione peroxidase, and downregulated the levels of Bax/Bcl-2 and the cleaved forms of caspase-3 in a dose- and time-dependent manner. This indicated that MFA attenuated the apoptosis of L-02 cells. MFA also decreased the elevated mRNA and protein expression levels of Nox4 and p22phox, and the production of intracellular ROS triggered by ethanol. Further analysis demonstrated that MFA significantly attenuated the phosphorylation of JNK and p38, which are major components of the mitogen-activated protein kinase (MAPK) pathways. On the whole, the findings of this study demonstrated that MFA attenuated the apoptotic cell death of L-02 cells by reducing the generation of ROS and inactivating the MAPK pathways.

Three variants in the nicotinamide adenine dinucleotide phosphate oxidase complex are associated with HCV-related liver damage

Approximately 71 million people are chronically infected with the hepatitis C virus (HCV), a potentially lethal pathogen. HCV generates oxidative stress correlating with disease severity. HCV proteins increase reactive oxygen species production by stimulating nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity. Reactive oxygen species are necessary for host defense and cell signaling; however, elevated NOX activity contributes to cancer, and NOX overexpression is associated with hepatic fibrosis. Our aim was to investigate whether single nucleotide polymorphisms (SNPs) in NOX family members are associated with HCV-related liver damage. Three hundred and thirty-one individuals of European ancestry and 90 individuals of African ancestry, all diagnosed with HCV, were genotyped for 243 tagSNPs in NOX enzymes and their regulatory factors. Pathology scores were available for 288 Caucasians and 71 Africans, and mortality status was determined for all subjects. SNPs were tested for association with pathology scores and as predictors of mortality. In Africans, homozygosity for the A allele of rs12753665 (neutrophil cytosolic factor 2) and homozygosity for the T allele of rs760519 (neutrophil cytosolic factor 4) were associated with and predictive of higher rates of advanced fibrosis and cirrhosis compared to other genotypes after controlling for age and sex. In Caucasians, homozygosity for the T allele of rs2292464 (dual oxidase 1) was associated with and predictive of decreased periportal inflammation after controlling for age and sex. No SNPs were significant predictors of mortality. Conclusion: In this exploratory study, three NOX-related polymorphisms in two ethnic groups were significantly associated with hepatic inflammation and fibrosis. Future studies investigating these SNPs in larger cohorts of patients with HCV are warranted. (Hepatology Communications 2017;1:973-982).

Digoxin Suppresses Pyruvate Kinase M2-Promoted HIF-1α Transactivation in Steatohepatitis

Sterile inflammation after tissue damage is a ubiquitous response, yet it has the highest amplitude in the liver. This has major clinical consequences, for alcoholic and non-alcoholic steatohepatitis (ASH and NASH) account for the majority of liver disease in industrialized countries and both lack therapy. Requirements for sustained sterile inflammation include increased oxidative stress and activation of the HIF-1α signaling pathway. We demonstrate the ability of digoxin, a cardiac glycoside, to protect from liver inflammation and damage in ASH and NASH. Digoxin was effective in maintaining cellular redox homeostasis and suppressing HIF-1α pathway activation. A proteomic screen revealed that digoxin binds pyruvate kinase M2 (PKM2), and independently of PKM2 kinase activity results in chromatin remodeling and downregulation of HIF-1α transactivation. These data identify PKM2 as a mediator and therapeutic target for regulating liver sterile inflammation, and demonstrate a novel role for digoxin that can effectively protect the liver from ASH and NASH.

Increased Interleukin-23 in Hashimoto's Thyroiditis Disease Induces Autophagy Suppression and Reactive Oxygen Species Accumulation

Hashimoto’s thyroiditis (HT) represents the most common organ-specific autoimmune disease. Inflammatory factors and reactive oxygen species (ROS) play detrimental roles during the pathogenesis of HT. In this study, we found that thyroid follicular cells (TFCs) from HT patients expressed an elevated level of interleukin-23 (IL-23), which contributed to autophagy suppression and ROS accumulation. Additionally, IL-23-induced autophagy suppression and ROS accumulation in human TFCs was attributed to AKT/mTOR/NF-κB signaling pathway activation. Inhibition of either IL-23 by a specific neutralization antibody, or mTOR by rapamycin, or NF-κB by IKK-16, significantly reversed the autophagy suppression and ROS accumulation. These results demonstrate a key role for IL-23 in HT pathogenesis and provide a potential therapeutic strategy against IL-23 or its signaling pathway in HT.

NOX4/ROS mediate ethanol‑induced apoptosis via MAPK signal pathway in L‑02 cells

The aim of the present study was to assess the molecular mechanism of ethanol‑induced oxidative stress‑mediated apoptosis in L‑02 liver cells in order to elucidate novel pathways associated with alcoholic liver disease. L‑02 cells were treated with 400 mM ethanol with or without inhibitors. The cell viability was measured by an MTT assay. Cell apoptosis was assessed by flow cytometry and a single‑stranded DNA (ssDNA) assay. Intracellular reactive oxygen species (ROS) production of L‑02 cells was determined using the 2',7'‑dichlorofluorescein‑diacetate dye. The protein expression of c‑Jun N‑terminal kinase (JNK), phosphorylated (p)‑JNK, P38, p‑P38, NADPH oxidase (NOX)1, NOX4, p22phox, B‑cell lymphoma 2 (Bcl‑2) and Bcl‑2‑associated X protein were measured by western blot analysis. The mRNA expression of NOX1, NOX4 and p22phox was measured by reverse transcription polymerase chain reaction analysis. The results indicated that after treatment with various concentrations of ethanol for the indicated durations, L‑02 cells were displayed a significant decrease in cell viability in a dose‑and time‑dependent manner. Ethanol‑induced apoptosis and cell death of L‑02 cells was accompanied by the generation of ROS, elevated expression of NOX, as well as phosphorylation of JNK and P‑38. In addition, increased expression of Bcl‑2 was induced by 400 mM ethanol. Furthermore, treatment with NOX inhibitor attenuated the ethanol‑induced a decrease in cell viability, and an increase in apoptosis and Bcl‑2 expression. In conclusion, ethanol induced apoptosis in the L‑02 hepatocyte cell line via generation of ROS and elevated expression of NOX4. This indicated that activation of JNK and p38 in the mitogen‑activated protein kinase pathway promotes apoptosis in L‑02 cells.

Balancing Effect of Biejiajian Oral Liquid () on ACE-Ang II-AT1R Axis and ACE2-Ang-(1-7)-Mas Axis in Rats with CCl4-Induced Hepatic Fibrosis

OBJECTIVE

To explore the effect of Biejiajian Oral Liquid (, BOL) on CCl₄-induced hepatic fibrosis in rats by detecting the changes in the levels of angiotensin II (Ang II), angiotensin-(1-7) [Ang-(1-7)], angiotensin-converting enzyme (ACE), ACE2, angiotensin II type 1 receptor (AT1R), Mas, etc. METHODS: A total of 180 Wistar rats were randomly divided into two groups by random digital table method: prevention experiment and treatment experiment. Each group was further subdivided into the following 6 subgroups: normal control group, model group, vitamin E [100 mg/(kg·d), VE] group, enalapril [10 mg/(kg·g), Ena] group, high-dosage [20 g/(kg·d)] BOL group, and low-dosage [10 g/(kg·d)] BOL group. The hepatic fibrosis rat model was established by subcutaneous injection of CCl₄ for 6 weeks. Prevention experiment and treatment experiment were administered with specific drugs at different times. At the end of treatment experiment, the pathological changes of liver were observed after hematoxylin-eosin staining. The expressions of ingredients in renin-angiotensin-aldosterone system (RAAS) such as AngII, Ang-(1-7), ACE, ACE2, AT1R, Mas, renin, CYP11B2 and angen in liver were detected by enzyme linked immunosorbent assay, immunohistochemistry method or reverse transcription-polymerase chain reaction, respectively.

RESULTS

The levels of AngII and Ang-(1-7) at the 6th week increased by 496.10% and 73.64%, respectively, compared with those at the 2nd week in the model group (P<0.01). With prevention or treatment with high-dosage BOL, there was an evident reduction of AngII level but an improvement of Ang-(1-7) level. Specifically, AngII level of high-dosage group decreased by 77.50% in prevention experiment (P=0.000) and by 76.93% in treatment experiment (P=0.002) compared with that in the model group. Ang-(1-7) level increased by 91.69% in prevention experiment (P=0.006) and by 70.77% in the treatment experiment (P=0.010) compared with that in the model group. The expression levels of mRNA of renin, ACE, CYP11B2, angen and AT1R decreased by 58.15%, 99.90%, 99.84%, 99.99% and 99.99% (all P<0.01), respectively.

CONCLUSIONS

BOL could help resist liver fibrosis in rats by enhancing the level of each ingredient in ACE2-Ang-(1-7)-Mas axis, while decreasing the level of each ingredient in ACE-AngII-AT1R axis. To some extent, BOL could enhance the regulation of RAAS in rats with CCl₄-induced hepatic fibrosis.

Gliptins Suppress Inflammatory Macrophage Activation to Mitigate Inflammation, Fibrosis, Oxidative Stress, and Vascular Dysfunction in Models of Nonalcoholic Steatohepatitis and Liver Fibrosis

AIMS

Nonalcoholic steatohepatitis (NASH) is characterized by steatosis, panlobular inflammation, liver fibrosis, and increased cardiovascular mortality. Dipeptidyl peptidase-4 inhibitors (gliptins) are indirect glucagon-like peptide 1 agonists with antidiabetic and anti-inflammatory activity, used for the treatment of type 2 diabetes. Their potential and underlying mechanisms to treat metabolic liver inflammation and fibrosis as well as the associated vascular dysfunction remain to be explored.

RESULTS

In the methionine/choline-deficient (MCD) diet and Mdr2^-/- models of NASH and liver fibrosis, treatment with sitagliptin and linagliptin significantly decreased parameters of steatosis and inflammation, which was accompanied by suppression of hepatic transcript levels reflecting metabolic inflammation and fibrosis, including SREBP-1c, FAS, TNFα, iNOS, α-SMA, Col1α1, and MMP-12. Moreover, gliptins reduced the number of liver infiltrating CD11b⁺Ly6C^hi proinflammatory monocytes/macrophages and liver-resident F4/80⁺ macrophages, with an increase of Ym1⁺ alternative macrophages and (anti-inflammatory) macrophage markers Arg1 and IL-10. This was paralleled by decreased hepatic and aortic reactive oxygen species (ROS) production and NOX-2 mRNA expression, a normalization of endothelial dysfunction, cardiac NADPH oxidase activity, mitochondrial ROS formation, and whole blood oxidative burst in the MCD model. Innovation and Conclusions: Gliptins via suppression of inflammation decrease steatosis, apoptosis, oxidative stress, and vascular dysfunction in murine models of NASH and liver fibrosis, with mild direct antifibrotic properties. They reduce the numbers of liver and vascular inflammatory monocytes/macrophages and induce their alternative polarization, with beneficial effect on NASH-associated hepatic and cardiovascular complications. Therefore, gliptins qualify as drugs for treatment of NASH and associated liver fibrosis and cardiovascular complications. Antioxid. Redox Signal. 28, 87-109.

Psoralea corylifolia L. Attenuates Nonalcoholic Steatohepatitis in Juvenile Mouse

Psoralea corylifolia L. (PC) is a traditional Chinese herb used to treat yang deficiency of the spleen and kidney in pediatric disease. Recent studies have shown its liver protection and anti-oxidative effects. The aim of this study was to explore the effect and mechanism of PC on nonalcoholic steatohepatitis in juvenile mice. The juvenile mouse model of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH) was established by being fed a high-fat diet in maternal-offspring manner. PC granules were prepared and the quality was assessed. The main components were identified by high performance liquid chromatography. Then, different dosages of PC were administered for 6 weeks. Homeostatic model assessment of insulin resistance, plasma liver enzymes, hepatic morphology, hepatic superoxide anion, and triglyceride/total cholesterol levels were examined. The changes of nuclear factor-κB (NF-κB) activity phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) and protein kinase C-α (PKC-α)/nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase signaling pathways in hepatic tissues were also determined. Our data demonstrated that PC significantly improved liver dysfunction, liver triglyceride/total cholesterol accumulation and insulin resistance in juvenile NAFLD/NASH mice. PC also alleviated hepatic steatosis, inflammatory cell infiltration, and fibroplasia in the portal area. Additionally, PC inhibited the activation of NF-κB and the mRNA expression of inflammatory factors while enhancing PI3K/Akt signaling in hepatic tissues. PC could also reduce hepatic superoxide anion levels, and NADPH oxidase activity as well as p47^phox protein expression and PKCα activation in hepatic tissues. The results suggest that PC is effective in the treatment of NASH in juvenile mice. The mechanism may be related to the attenuation of hepatic oxidative stress through the PKC-α/NADPH oxidase signaling pathway.

Thermodynamic Aspects and Reprogramming Cellular Energy Metabolism during the Fibrosis Process

Fibrosis is characterized by fibroblast proliferation and fibroblast differentiation into myofibroblasts, which generate a relaxation-free contraction mechanism associated with excessive collagen synthesis in the extracellular matrix, which promotes irreversible tissue retraction evolving towards fibrosis. From a thermodynamic point of view, the mechanisms leading to fibrosis are irreversible processes that can occur through changing the entropy production rate. The thermodynamic behaviors of metabolic enzymes involved in fibrosis are modified by the dysregulation of both transforming growth factor β (TGF-β) signaling and the canonical WNT/β-catenin pathway, leading to aerobic glycolysis, called the Warburg effect. Molecular signaling pathways leading to fibrosis are considered dissipative structures that exchange energy or matter with their environment far from the thermodynamic equilibrium. The myofibroblastic cells arise from exergonic processes by switching the core metabolism from oxidative phosphorylation to glycolysis, which generates energy and reprograms cellular energy metabolism to induce the process of myofibroblast differentiation. Circadian rhythms are far-from-equilibrium thermodynamic processes. They directly participate in regulating the TGF-β and WNT/β-catenin pathways involved in energetic dysregulation and enabling fibrosis. The present review focusses on the thermodynamic implications of the reprogramming of cellular energy metabolism, leading to fibroblast differentiation into myofibroblasts through the positive interplay between TGF-β and WNT/β-catenin pathways underlying in fibrosis.

PNPLA3 variant and portal/periportal histological pattern in patients with biopsy-proven non-alcoholic fatty liver disease: a possible role for oxidative stress

Pathogenesis of non-alcoholic fatty liver disease (NAFLD) is influenced by predisposing genetic variations, dysmetabolism, systemic oxidative stress, and local cellular and molecular cross-talks. Patatin-like phospholipase domain containing 3 (PNPLA3) gene I148M variant is a known determinant of NAFLD. Aims were to evaluate whether PNPLA3 I148M variant was associated with a specific histological pattern, hepatic stem/progenitor cell (HpSC) niche activation and serum oxidative stress markers. Liver biopsies were obtained from 54 NAFLD patients. The activation of HpSC compartment was evaluated by the extension of ductular reaction (DR); hepatic stellate cells, myofibroblasts (MFs), and macrophages were evaluated by immunohistochemistry. Systemic oxidative stress was assessed measuring serum levels of soluble NOX2-derived peptide (sNOX2-dp) and 8-isoprostaglandin F_2α (8-iso-PGF_2α). PNPLA3 carriers showed higher steatosis, portal inflammation and HpSC niche activation compared to wild-type patients. DR was correlated with NAFLD activity score (NAS) and fibrosis score. Serum 8-iso-PGF_2α were significantly higher in I148M carriers compared to non-carriers and were correlated with DR and portal inflammation. sNox2-dp was correlated with NAS and with HpSC niche activation. In conclusion, NAFLD patients carrying PNPLA3 I148M are characterized by a prominent activation of HpSC niche which is associated with a more aggressive histological pattern (portal fibrogenesis) and increased oxidative stress.

Therapeutic pro-fibrogenic signaling pathways in fibroblasts

Myofibroblasts (MFs) play a critical role in the progression of chronic inflammatory and fibroproliferative diseases in different tissues/organs, whatever the etiology. Fibrosis is preceded and sustained by persistent injury and inflammatory response in a profibrogenic scenario involving mutual interactions, operated by several mediators and pathways, of MFs and related precursor cells with innate immunity cells and virtually any cell type in a defined tissue. These interactions, mediators and related signaling pathways are critical in initiating and perpetuating the differentiation of precursor cells into MFs that in different tissues share peculiar traits and phenotypic responses, including the ability to proliferate, produce ECM components, migrate and contribute to the modulation of inflammatory response and tissue angiogenesis. Literature studies related to liver, lung and kidney fibrosis have outlined a number of MF-related core regulatory fibrogenic signaling pathways conserved across these different organs and potentially targetable in order to develop effective antifibrotic therapeutic strategies.

Review article: next-generation transformative advances in the pathogenesis and management of autoimmune hepatitis

BACKGROUND

Advances in autoimmune hepatitis that transform current concepts of pathogenesis and management can be anticipated as products of ongoing investigations driven by unmet clinical needs and an evolving biotechnology.

AIM

To describe the advances that are likely to become transformative in autoimmune hepatitis, based on the direction of current investigations.

METHODS

Pertinent abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and a secondary bibliography was developed. The discovery process was repeated, and a tertiary bibliography was identified. The number of abstracts reviewed was 2830, and the number of full-length articles reviewed exceeded 150.

RESULTS

Risk-laden allelic variants outside the major histocompatibility complex (rs3184504, r36000782) are being identified by genome-wide association studies, and their gene products are potential therapeutic targets. Epigenetic changes associated with environmental cues can enhance the transcriptional activity of genes, and chromatin re-structuring and antagonists of noncoding molecules of ribonucleic acid are feasible interventions. The intestinal microbiome is a discovery field for microbial products and activated immune cells that may translocate to the periphery and respond to manipulation. Epidemiological studies and controlled interview-based surveys may implicate environmental and xenobiotic factors that warrant evidence-based changes in lifestyle, and site-directed molecular and cellular interventions promise to change the paradigm of treatment from one of blanket immunosuppression.

CONCLUSIONS

Advances in genetics, epigenetics, pathophysiology, epidemiology, and site-directed molecular and cellular interventions constitute the next generation of transformative advances in autoimmune hepatitis.