Diagnostic modalities for nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, and associated fibrosis

Pnpla3 silencing with antisense oligonucleotides ameliorates nonalcoholic steatohepatitis and fibrosis in Pnpla3 I148M knock-in mice

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) is becoming a leading cause of advanced chronic liver disease. The progression of NAFLD, including nonalcoholic steatohepatitis (NASH), has a strong genetic component, and the most robust contributor is the patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 encoding the 148M protein sequence variant. We hypothesized that suppressing the expression of the PNPLA3 148M mutant protein would exert a beneficial effect on the entire spectrum of NAFLD.

METHODS

We examined the effects of liver-targeted GalNAc3-conjugated antisense oligonucleotide (ASO)-mediated silencing of Pnpla3 in a knock-in mouse model in which we introduced the human PNPLA3 I148M mutation.

RESULTS

ASO-mediated silencing of Pnpla3 reduced liver steatosis (p = 0.038) in homozygous Pnpla3 148M/M knock-in mutant mice but not in wild-type littermates fed a steatogenic high-sucrose diet. In mice fed a NASH-inducing diet, ASO-mediated silencing of Pnpla3 reduced liver steatosis score and NAFLD activity score independent of the Pnpla3 genotype, while reductions in liver inflammation score (p = 0.018) and fibrosis stage (p = 0.031) were observed only in the Pnpla3 knock-in 148M/M mutant mice. These responses were accompanied by reduced liver levels of Mcp1 (p = 0.026) and Timp2 (p = 0.007) specifically in the mutant knock-in mice. This may reduce levels of chemokine attracting inflammatory cells and increase the collagenolytic activity during tissue regeneration.

CONCLUSION

This study provides the first evidence that a Pnpla3 ASO therapy can improve all features of NAFLD, including liver fibrosis, and suppress the expression of a strong innate genetic risk factor, Pnpla3 148M, which may open up a precision medicine approach in NASH.

Noninvasive Assessment of Liver Disease in Patients With Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is estimated to afflict approximately 1 billion individuals worldwide. In a subset of NAFLD patients, who have the progressive form of NAFLD termed nonalcoholic steatohepatitis (NASH), it can progress to advanced fibrosis, cirrhosis, hepatocellular carcinoma, and liver-related morbidity and mortality. NASH is typically characterized by a specific pattern on liver histology, including steatosis, lobular inflammation, and ballooning with or without peri-sinusoidal fibrosis. Thus, key issues in NAFLD patients are the differentiation of NASH from simple steatosis and identification of advanced hepatic fibrosis. Until now, liver biopsy has been the gold standard for identifying these 2 critical end points, but has well-known limitations, including invasiveness; rare but potentially life-threatening complications; poor acceptability; sampling variability; and cost. Furthermore, due to the epidemic proportion of individuals with NAFLD worldwide, liver biopsy evaluation is impractical, and noninvasive assessment for the diagnosis of NASH and fibrosis is needed. Although much of the work remains to be done in establishing cost-effective strategies for screening for NASH, advanced fibrosis, and cirrhosis, in this review, we summarize the current state of the noninvasive assessment of liver disease in NAFLD, and we provide an expert synthesis of how these noninvasive tools could be utilized in clinical practice. Finally, we also list the key areas of research priorities in this area to move forward clinical practice.

Non-invasive assessment of NAFLD as systemic disease-A machine learning perspective

Background & aims

Current non-invasive scores for the assessment of severity of non-alcoholic fatty liver disease (NAFLD) and identification of patients with non-alcoholic steatohepatitis (NASH) have insufficient performance to be included in clinical routine. In the current study, we developed a novel machine learning approach to overcome the caveats of existing approaches.

Methods

Non-invasive parameters were selected by an ensemble feature selection (EFS) from a retrospectively collected training cohort of 164 obese individuals (age: 43.5±10.3y; BMI: 54.1±10.1kg/m²) to develop a model able to predict the histological assessed NAFLD activity score (NAS). The model was evaluated in an independent validation cohort (122 patients, age: 45.2±11.75y, BMI: 50.8±8.61kg/m²).

Results

EFS identified age, γGT, HbA1c, adiponectin, and M30 as being highly associated with NAFLD. The model reached a Spearman correlation coefficient with the NAS of 0.46 in the training cohort and was able to differentiate between NAFL (NAS≤4) and NASH (NAS>4) with an AUC of 0.73. In the independent validation cohort, an AUC of 0.7 was achieved for this separation. We further analyzed the potential of the new model for disease monitoring in an obese cohort of 38 patients under lifestyle intervention for one year. While all patients lost weight under intervention, increasing scores were observed in 15 patients. Increasing scores were associated with significantly lower absolute weight loss, lower reduction of waist circumference and basal metabolic rate.

Conclusions

A newly developed model (http://CHek.heiderlab.de) can predict presence or absence of NASH with reasonable performance. The new score could be used to detect NASH and monitor disease progression or therapy response to weight loss interventions.

Nitro-fatty acids protect against steatosis and fibrosis during development of nonalcoholic fatty liver disease in mice

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) and resulting nonalcoholic steatohepatitis (NASH) are reaching global epidemic proportions. Lack of non-invasive diagnostic tools and effective therapies constitute two of the major hurdles for a bona fide treatment and a reversal of NASH progression and/or regression of the disease. Nitro-oleic acid (OA-NO2) has been proven effective in multiple experimental models of inflammation and fibrosis. Thus, the potential benefit of in vivo administration of OA-NO2 to treat advanced NAFLD was tested herein in a model of long-term NASH diet-induced liver damage.

METHODS

Non-invasive imaging (e.g. photoacustic-ultrasound (PA-US)) was pursued to establish advanced experimental model of NASH in mice in which both steatosis and fibrosis were diagnosed prior experimental therapy with OA-NO2. Experimental controls included equimolar amounts of the non-nitrated oleic acid (OA). CLAMS and NMR-based analysis was used for energy metabolism.

FINDINGS

CLAMS and NMR-based analysis demonstrates that OA-NO2 improves body composition and energy metabolism and inhibits hepatic triglyceride (TG) accumulation. Photoacoustic-ultrasound imaging revealed a robust inhibition of liver steatosis and fibrosis by OA-NO2. RNA-sequencing analysis uncovered inflammation and fibrosis as major pathways suppressed by OA-NO2 administration, as well as regulation of lipogenesis and lipolysis pathways, with a robust inhibition of SREBP1 proteolytic activation and subsequent lipogenesis gene expression by OA-NO2. These results were further supported by histological analysis and quantification of lipid accumulation, lobular inflammation (F4/80 staining) and fibrosis (collagen deposition, αSMA staining) as well as established parameters of liver damage (ALT). In vitro studies indicate that OA-NO2 inhibits TG biosynthesis and accumulation in hepatocytes and inhibits fibrogenesis in human stellate cells.

INTERPRETATION

OA-NO2 improve steatohepatitis and fibrosis and may constitute an effective therapeutic approach against advanced NAFLD that warrants further clinical evaluation.

Noninvasive Evaluation of Liver Function in Morbidly Obese Patients

Background

More than half of the obese patients develop nonalcoholic fatty liver disease (NAFLD), which may further progress to nonalcoholic steatohepatitis (NASH) and cirrhosis. The aim of this study was to assess alterations in liver function in obese patients with a noninvasive liver function test.

Methods

In a prospective cohort study 102 morbidly obese patients undergoing bariatric surgery were evaluated for their liver function. Liver function capacity was determined by the LiMAx® test (enzymatic capacity of cytochrome P450 1A2). Liver biopsy specimens were obtained intraoperatively and classified according to the NAFLD Activity Score (NAS). NASH clinical score was additionally calculated from laboratory and clinical parameters.

Results

Median liver function capacity was 286 (IQR = 141) μg/kg/h. 27% of patients were histologically categorized as definite NASH, 39% as borderline, and 34% as not NASH. A significant correlation was observed between liver function capacity and NAS (r = −0.492; p < 0.001). The sensitivity and specificity of the LiMAx® test to distinguish between definite NASH and not NASH were 85.2% and 82.9% (AUROC 0.859), respectively. According to the NASH clinical scoring system, 14% were classified as low risk, 31% as intermediate, 26% as high, and 29% as very high risk. Liver function capacity is also significantly correlated with the NASH clinical scoring system (r = −0.411; p < 0.001).

Conclusions

Obese patients show a diminished liver function capacity, especially those suffering from type 2 diabetes. The liver function capacity correlates with histological and clinical scoring systems. The LiMAx® test may be a valuable tool for noninvasive screening for NASH in obese patients.

Nonalcoholic Fatty Liver Disease in Diabetes. Part I: Epidemiology and Diagnosis

Nonalcoholic fatty liver disease (NAFLD) and diabetes are common metabolic disorders whose prevalence rates are expected to rise worldwide, corresponding to aging and increasingly obese populations. Compared to the general population (around 25%), 50% to 70% of people with diabetes have NAFLD, and NAFLD severity (including fibrosis) tends to be worsened by the presence of diabetes. NAFLD is considered an emerging risk factor for type 2 diabetes mellitus and a contributor to the development of chronic diabetes-related complications. This reciprocal relationship demonstrates the importance of confirming suspected NAFLD in patients with diabetes. Due to the invasive nature of liver biopsy to assess NAFLD status, various alternative non-invasive modalities have been developed and validated. Here, we summarized the epidemiology of NAFLD in patients with diabetes and reviewed currently available imaging modalities and biomarker-based prediction models for their ability to detect liver steatosis and/or fibrosis.

Does nonalcoholic fatty liver disease cause cardiovascular disease? Current knowledge and gaps

Non-alcoholic fatty liver disease (NAFLD) is highly prevalent and includes a spectrum of abnormalities ranging from steatosis to cirrhosis. In this review, we address recent evidence and limitations of studies that evaluated the association of NAFLD with atherosclerotic cardiovascular disease. NAFLD is considered an ectopic fat deposit associated with metabolic (insulin resistance, hyperglycemia and dyslipidemia), inflammatory, coagulation and blood pressure disturbances. Prospective studies have associated NAFLD presence and severity, particularly steatohepatitis and fibrosis, with an increased risk of cardiovascular disease. However, these studies are limited by heterogeneity concerning NAFLD diagnostic criteria and disease severity stratification, as well as by the presence of confounding factors. In addition, genetic variants predisposing to NAFLD, such as the PNPLA3 I148M mutation, were not consistently associated with an increased risk of cardiovascular events. Therefore, currently, it is not possible to prove a causal relation between NAFLD and cardiovascular disease. Furthermore, there is presently no evidence that NAFLD diagnosis can be used as a tool to improve cardiovascular risk stratification and modify treatment. Specific treatments for NAFLD are being developed and must be tested prospectively in adequately designed trials to determine the potential of reducing both hepatic and cardiovascular diseases and to prove whether NAFLD is indeed a cause of atherosclerosis.

Patients With Lean Nonalcoholic Fatty Liver Disease Are Metabolically Abnormal and Have a Higher Risk for Mortality

IN BRIEF Nonalcoholic fatty liver disease (NAFLD) is an increasingly recognized and common cause of chronic liver disease worldwide. Although most patients with NAFLD are obese, a smaller group of NAFLD patients are lean. This study explored the long-term outcomes of lean patients with NAFLD in the United States. Compared to lean individuals without NAFLD, lean people with NAFLD were significantly more likely to be older and male and had higher comorbidities (i.e., diabetes, hyperlipidemia, hypertension, metabolic syndrome, chronic kidney disease, and cardiovascular disease). The presence of NAFLD in lean individuals was independently associated with increased risk of all-cause and cardiovascular mortality.

Extracellular Vesicles from Amnion-Derived Mesenchymal Stem Cells Ameliorate Hepatic Inflammation and Fibrosis in Rats

Background

There are no approved drug treatments for liver fibrosis and nonalcoholic steatohepatitis (NASH), an advanced stage of fibrosis which has rapidly become a major cause of cirrhosis. Therefore, development of anti-inflammatory and antifibrotic therapies is desired. Mesenchymal stem cell- (MSC-) based therapy, which has been extensively investigated in regenerative medicine for various organs, can reportedly achieve therapeutic effect in NASH via paracrine action. Extracellular vesicles (EVs) encompass a variety of vesicles released by cells that fulfill functions similar to those of MSCs. We herein investigated the therapeutic effects of EVs from amnion-derived MSCs (AMSCs) in rats with NASH and liver fibrosis.

Methods

NASH was induced by a 4-week high-fat diet (HFD), and liver fibrosis was induced by intraperitoneal injection of 2 mL/kg 50% carbon tetrachloride (CCl₄) twice a week for six weeks. AMSC-EVs were intravenously injected at weeks 3 and 4 in rats with NASH (15 μg/kg) and at week 3 in rats with liver fibrosis (20 μg/kg). The extent of inflammation and fibrosis was evaluated with quantitative reverse transcription polymerase chain reaction and immunohistochemistry. The effect of AMSC-EVs on inflammatory and fibrogenic response was investigated in vitro.

Results

AMSC-EVs significantly decreased the number of Kupffer cells (KCs) in the liver of rats with NASH and the mRNA expression levels of inflammatory cytokines such as tumor necrosis factor- (Tnf-) α, interleukin- (Il-) 1β and Il-6, and transforming growth factor- (Tgf-) β. Furthermore, AMSC-EVs significantly decreased fiber accumulation, KC number, and hepatic stellate cell (HSC) activation in rats with liver fibrosis. In vitro, AMSC-EVs significantly inhibited KC and HSC activation and suppressed the lipopolysaccharide (LPS)/toll-like receptor 4 (TLR4) signaling pathway.

Conclusions

AMSC-EVs ameliorated inflammation and fibrogenesis in a rat model of NASH and liver fibrosis, potentially by attenuating HSC and KC activation. AMSC-EV administration should be considered as a new therapeutic strategy for chronic liver disease.

The Chinese medicine Chai Hu Li Zhong Tang protects against non-alcoholic fatty liver disease by activating AMPKα

An effective treatment for non-alcoholic fatty liver disease (NAFLD) is urgently needed. In the present study, we investigated whether the Chinese medicine Chai Hu Li Zhong Tang (CHLZT) could protect against the development of NAFLD. Rats in an animal model of NAFLD were treated with CHLZT, and their serum levels of cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were detected with an automatic biochemical analyzer. A cellular model of NAFLD was also established by culturing HepG2 cells in a medium that contained a long chain fat emulsion. Those cells were treated with CHLZT that contained serum from rats. After treatment, the levels of adenylate-activated protein kinase (AMPK) α (AMPKα), p-AMPKα, acetyl coenzyme A carboxylase (ACC) α (ACCα), pACCα, PPARγ, and SREBP-2 were detected. The AMPK agonist, acadesine (AICAR), was used as a positive control compound. Our results showed that CHLZT or AICAR significantly decreased the serum levels of TG, TC, LDL-C, AST, ALT, and insulin in NAFLD rats, and significantly increased their serum HDL-C levels. Treatments with CHLZT or AICAR significantly decreased the numbers of lipid droplets in NAFLD liver tissues and HepG2 cells. CHLZT and AICAR increased the levels of p-AMPKα and PPARγ in the NAFLD liver tissues and HepG2 cells, but decreased the levels of ACC-α, p-ACC-α, SREBP-2, and 3-hydroxyl-3-methylglutaryl-coenzyme A reductase (HMGR). CHLZT protects against NAFLD by activating AMPKα, and also by inhibiting ACC activity, down-regulating SREBP2 and HMGR, and up-regulating PPAR-γ. Our results suggest that CHLZT might be useful for treating NAFLD in the clinic.

Predictors of advanced fibrosis in non-cirrhotic non-alcoholic fatty liver disease in Germany

BACKGROUND

Advanced fibrosis has been established as the most important predictor of overall mortality in patients with non-alcoholic fatty liver disease (NAFLD). In contrast to cirrhosis, advanced, non-cirrhotic NAFLD is difficult to identify and data from Germany are lacking.

AIM

To identify clinical factors associated with advanced, non-cirrhotic fibrosis.

METHODS

Patients were recruited in the prospectively enrolling European NAFLD Registry. Clinical characteristics and the performance of non-invasive surrogate scores compared with vibration-controlled transient elastography are reported.

RESULTS

Two hundred and sixty-one patients with non-cirrhotic NAFLD on liver biopsy (mean age 51 years, equal sex distribution) were included. The prevalence of stage 3 fibrosis on liver biopsy was 15.7%. These patients were significantly older (57 vs 50 years, P < 0.01), had a higher body mass index (32.3 vs 30.5, P < 0.05), and more frequent arterial hypertension (78% vs 50%, P = 0.001) and type 2 diabetes (61% vs 24.1%, P < 0.001). On multivariate logistic regression, diabetes (OR = 4.68, 95% CI 2.17-10.10) and hypertension (OR = 2.91, 95% CI 1.12-7.18) were independent predictors of advanced fibrosis. Comedication included metformin in 50% and insulin in 33% of patients with diabetes. Despite the presence of cardiovascular risk factors, the use of statins was low. Liver stiffness measurement identified advanced fibrosis with an AUROC of 0.81 (95% CI 0.72-0.91). The performance of NAFLD fibrosis score, Fibrosis-4, and AST to platelet ratio index were lower with AUCs of 0.74, 0.71, and 0.67, respectively.

CONCLUSIONS

The prevalence of metabolic comorbidities in a German population with non-cirrhotic biopsy-proven NAFLD is high. While the examined scores exhibit an acceptable specificity, liver stiffness measurement appeared to be superior to blood-based non-invasive surrogate scores in ruling out advanced fibrosis.

Assessment of Nonalcoholic Fatty Liver Disease Progression in Children Using Magnetic Resonance Imaging

OBJECTIVE

To assess liver disease progression using paired magnetic resonance imaging (MRI) measurements of liver fat fraction (FF) and stiffness.

STUDY DESIGN

Retrospective cohort study including patients with nonalcoholic fatty liver disease who had undergone repeat MRI studies. Descriptive statistics were used, as well as Pearson or Spearman correlation when appropriate. Mixed model analyses were used to determine relationships between liver FF/stiffness and predictor variables.

RESULTS

Sixty-five patients (80% non-Hispanic, mean age 14 ± 3 years) were included. Time from first to last MRI was 27 ± 14 months. Over time, body mass index z score remained stable, and there were no significant differences in mean serum aminotransferases, insulin, glucose, triglycerides, low-density lipoprotein, and high-density lipoprotein (HDL) levels. However, the proportion of patients with alanine aminotransferase (ALT) < 50 U/L increased. MRI FF and stiffness decreased in 29% and 20% of patients, respectively, and increased in 25% and 22% of patients, respectively. There was a weak positive correlation between FF change and ALT change (r = 0.41, P = .053) and a moderate negative correlation between change in FF and change in serum HDL levels (r = -0.58, P = .004). After adjusting for HDL, increase in serum insulin was the only variable predictive of increase in FF (P = .061). There was no correlation between change in liver stiffness and change in ALT (r = .02, P = .910).

CONCLUSIONS

MRI-determined hepatic FF and stiffness improved in a minority of patients overtime. ALT levels were not reflective of the change in FF or stiffness. MRI-based imaging is complementary in the assessment of NAFLD progression.

Gd-EOB-DTPA DCE-MRI biomarkers in a rabbit model of liver fibrosis

The purpose of this study was to investigate the correlations between Gd-EOB-DTPA DCE-MRI biomarkers and histopathologic biomarkers of liver fibrosis progression in a rabbit model of liver fibrosis. Thirty-Six New Zealand white rabbits were randomly divided into control (n = 6) and liver fibrosis group (n = 30). Each rabbit in the liver fibrosis group received a weekly subcutaneous injection in the back comprising 50% carbon tetrachloride (CCl₄) in oily solution. Control rabbits received subcutaneous injections with the same amount of normal saline solution instead. MR imaging was performed in control and fibrotic rabbits were conducted by MRI at week 0 (n = 36). The fibrotic rabbits were performed MR imaging on 6 weeks, 9 weeks, and 12 weeks after modeling of fibrosis. Before each MRI, peripheral blood was collected, and several biochemical testes are performed. The thirty-four rabbits completed this study. They were then divided into three subgroups according to fibrotic stage: no fibrosis (F0, n = 12), mild fibrosis (F1+F2, n = 14), and advanced fibrosis (F3+F4, n = 8). DCE-MRI measurements show increasing K^trans and V_e while decreasing iACU90 with increasing fibrosis stage. The significant correlations were observed between mean K^trans, V_e, iACU90 and percentage of the animal with mild liver fibrosis. For blood biomarkers, there were significant differences between F0 and F1+F2, and between F0 and F3+F4 in the serum levels of ALT (all P < 0.05), and TB (F0 vs. F1+F2, P = 0.004), while no differences were found between F1+F2 group and F3+F4 group (all P > 0.05). There were significant differences between F0 and F1+F2 (P = 0.02). Gd-EOB-DTPA DCE-MRI is a promising method for the noninvasive diagnosis and staging of liver fibrosis. Future studies to evaluate the effectiveness of these techniques in patients with liver fibrosis are warranted.

An Evaluation of the Collagen Fragments Related to Fibrogenesis and Fibrolysis in Nonalcoholic Steatohepatitis

Fibrosis, resulted from the imbalance of fibrogenesis and fibrolysis, is a key readout of disease progression in nonalcoholic steatohepatitis (NASH) and reflects mortality risk. Non-invasive biomarkers capable of diagnosing fibrosis stages and monitoring fibrosis changes in NASH patients are urgently needed. This study is to evaluate collagen formation and degradation biomarkers, reflective of fibrogenesis or fibrolysis, in patients with biopsy proven NASH. Collagen formation biomarker PRO-C3 and PRO-C6 levels were significantly higher in patients with advanced fibrosis stage 3–4 than those with fibrosis stage 0–2. Elevated PRO-C3 levels were also associated with severe lobular inflammation and ballooning, but not with steatosis. Multivariate logistic regression analysis identified PRO-C3 and PRO-C6 to be independently related to fibrosis stage. PRO-C3 showed similar performance to identify patients with advanced fibrosis in discovery and validation cohorts. Furthermore, in a longitudinal study cohort with paired biopsies, mean PRO-C3 increased with worsening of fibrosis and decreased with fibrosis improvement. The results suggest that PRO-C3 may be a potentially useful biomarker in identifying patients with advanced fibrosis and active fibrogenesis, as well as in assessing changes in fibrosis over time. It is worthy of further evaluation to confirm its diagnostic value and clinical utility.

MSDC-0602K, a metabolic modulator directed at the core pathology of non-alcoholic steatohepatitis

INTRODUCTION

Non-alcoholic steatohepatitis (NASH) is a serious form of non-alcoholic fatty liver disease (NAFLD) for which there is no marketed treatments. NAFLD is initiated by excess intake of nutrients and recent evidence has pinpointed the mitochondrial pyruvate carrier (MPC) as a mediator of the nutritional overload signals. Areas covered: An overview is given of MSDC-0602K, a new agent in development that modulates the MPC and as such treats the symptoms of fatty liver including dysfunctional lipid metabolism, inflammation, and insulin resistance as well as the key liver pathology including fibrosis.

METHODOLOGY

The current evaluation is written from the direct experience of the authors and review of published literature using standard search techniques. Expert Opinion: The mechanism of action of MSDC-0602K appears to be suited for treatment of the NASH pathophysiology. An ongoing phase 2b dose-ranging trial should demonstrate whether or not MSDC-0602K has the potential to be a cornerstone metabolic therapy for the treatment of NASH.

Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: Implications for liver transplantation

Nonalcoholic fatty liver disease (NAFLD), a common cause of chronic liver disease (CLD), has a global prevalence of 25%. Its progressive form, nonalcoholic steatohepatitis (NASH), is a leading indication for liver transplantation (LT) in the United States. As a result, specialty societies, including the American Association for the Study of Liver Diseases (AASLD) and the European Association for the Study of the Liver, have developed guidance on the epidemiology, diagnosis, and treatment of NAFLD and NASH. Therefore, the transplant team must be well versed in the state of current knowledge about NAFLD and transplant-specific issues for this increasingly important indication for LT. Liver Transplantation 24 166-170 2018 AASLD.

Role of inflammatory response in liver diseases: Therapeutic strategies

Inflammation and tumorigenesis are tightly linked pathways impacting cancer development. Inflammasomes are key signalling platforms that detect pathogenic microorganisms, including hepatitis C virus (HCV) infection, and sterile stressors (oxidative stress, insulin resistance, lipotoxicity) able to activate pro-inflammatory cytokines interleukin-1β and IL-18. Most of the inflammasome complexes that have been described to date contain a NOD-like receptor sensor molecule. Redox state and autophagy can regulate inflammasome complex and, depending on the conditions, can be either pro- or anti-apoptotic. Acute and chronic liver diseases are cytokine-driven diseases as several proinflammatory cytokines (IL-1α, IL-1β, tumor necrosis factor-alpha, and IL-6) are critically involved in inflammation, steatosis, fibrosis, and cancer development. NLRP3 inflammasome gain of function aggravates liver disease, resulting in severe liver fibrosis and highlighting this pathway in the pathogenesis of non-alcoholic fatty liver disease. On the other hand, HCV infection is the primary catalyst for progressive liver disease and development of liver cancer. It is well established that HCV-induced IL-1β production by hepatic macrophages plays a critical and central process that promotes liver inflammation and disease. In this review, we aim to clarify the role of the inflammasome in the aggravation of liver disease, and how selective blockade of this main pathway may be a useful strategy to delay fibrosis progression in liver diseases.

Circular RNA in Liver: Health and Diseases

Circular RNA (circRNA) is an important class of noncoding RNA characterized by covalently closed continuous loop structures. In recent years, the various functions of circRNAs have been continuously documented, including effects on cell proliferation and apoptosis and nutrient metabolism. The liver is the largest solid organ in mammals, and it also performs many functions in the body, which is considered to be the busiest organ in the body. At the same time, the liver is vulnerable to multiple pathogenic factors, causing various acute and chronic liver diseases. The pathogenesis of liver disease is still not fully understood. As a rising star for the past few years, circRNAs have been proven involved in the regulation of liver homeostasis and disease. This chapter will explain the role of circRNAs in liver health and diseases and sort out the confusion in the present study.