The NLRP3 Inflammasome in Alcoholic and Nonalcoholic Steatohepatitis

The role of gut microbiota, exosomes, and their interaction in the pathogenesis of ALD

BACKGROUND

The liver disorders caused by alcohol abuse are termed alcoholic-related liver disease (ALD), including alcoholic steatosis, alcoholic steatohepatitis, alcoholic hepatitis, and alcoholic cirrhosis, posing a significant threat to human health. Currently, ALD pathogenesis has not been completely clarified, which is likely to be related to the direct damage caused by alcohol and its metabolic products, oxidative stress, gut dysbiosis, and exosomes.

AIMS

The existing studies suggest that both the gut microbiota and exosomes contribute to the development of ALD. Moreover, there exists an interaction between the gut microbiota and exosomes. We discuss whether this interaction plays a role in the pathogenesis of ALD and whether it can be a potential therapeutic target for ALD treatment.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Chronic alcohol intake alters the diversity and composition of gut microbiota, which greatly contributes to ALD's progression. Some approaches targeting the gut microbiota, including probiotics, fecal microbiota transplantation, and phage therapy, have been confirmed to effectively ameliorate ALD in many animal experiments and/or several clinical trials. In ALD, the levels of exosomes and the expression profile of microRNA have also changed, which affects the pathogenesis of ALD. Moreover, there is an interplay between exosomes and the gut microbiota, which also putatively acts as a pathogenic factor of ALD.

Inflammation and cancer: molecular mechanisms and clinical consequences

Inflammation, a hallmark of cancer, has been associated with tumor progression, transition into malignant phenotype and efficacy of anticancer treatments in cancer. It affects all stages of cancer, from the initiation of carcinogenesis to metastasis. Chronic inflammation induces immunosup-pression, providing an environment conducive to carcinogenesis, whereas acute inflammation induces an antitumor immune response, leading to tumor suppression. Solid tumors have an inflammatory tumor microenvironment (TME) containing cancer cells, immune cells, stromal cells, and soluble molecules, which plays a key role in tumor progression and therapy response. Both cancer cells and stromal cells in the TME are highly plastic and constantly change their phenotypic and functional properties. Cancer-associated inflammation, the majority of which consists of innate immune cells, plays an important role in cancer cell plasticity, cancer progression and the development of anticancer drug resistance. Today, with the combined used of advanced technologies, such as single-cell RNA sequencing and spatial molecular imaging analysis, the pathways linking chronic inflammation to cancer have been largely elucidated. In this review article, we highlighted the molecular and cellular mechanisms involved in cancer-associated inflammation and its effects on cancer progression and treatment response. We also comprehensively review the mechanisms linking chronic inflammation to cancer in the setting of GI cancers.

Lipid droplet efferocytosis attenuates proinflammatory signaling in macrophages via TREM2- and MS4A7-dependent mechanisms

Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by injury to steatotic hepatocytes that triggers the release of endogenous danger-associated molecular patterns. Recent work demonstrated that exposed lipid droplets (LDs) serve as a pathogenic signal that promotes monocyte infiltration and its maturation into triggering receptor expressed in myeloid cells 2 (TREM2+) macrophages in MASH liver. Here we explore the role of LD exposure in modulating inflammatory signaling in macrophages. We found that LD efferocytosis triggers a global transcriptional response and dampens pro-inflammatory signaling in macrophages. LD treatment attenuated NLRP3 inflammasome activation via mechanisms independent of lysosomal LD hydrolysis. While TREM2 was dispensable for LD efferocytosis by macrophages, it was required for the attenuation of proinflammatory signaling upon LD exposure. Additionally, MS4A7 downregulation contributes to LD efferocytosis-mediated dampening of inflammatory response. These results underscore the dual role of LD exposure in MASH liver by promoting monocyte infiltration and TREM2+ macrophage induction, while restraining proinflammatory response in macrophages.

BRISC inactivation alleviates alcohol-induced liver injury in mice

BRCC3 isopeptidase complex (BRISC) is a JAMM subfamily deubiquitinase that has been revealed to be required for optional activation of NLRP3 inflammasome and TLR4/NF-κB signaling pathway. BRISC plays an important role in lipopolysaccharide (LPS)/D-galactosamine-induced acute liver failure, while its functional contribution to alcoholic liver disease (ALD) is still unclear. In this study, we found that the expression of BRISC components was increased in liver tissues of alcoholic hepatitis (AH) animal models and patients with AH. Mice lacking either the scaffold subunit ABRO1 or the catalytic subunit BRCC3 showed attenuated liver steatosis, inflammation, and liver injury compared to control mice after chronic plus binge ethanol feeding. Moreover, pharmacological inhibition of BRISC activity by a BRISC inhibitor thiolutin potently protected mice from ALD development. Preliminary mechanistical studies showed that BRISC deficiency did not directly affect alcohol-induced hepatocyte injury or the translocation of LPS through the damaged gut mucosa after ethanol feeding, but prevented alcohol-induced NLRP3 inflammasome activation in liver. Collectively, our work revealed a previously unknown role of BRISC in ALD and suggested that BRISC may serve as a promising therapeutic target for ALD treatment.

Endothelial Dysfunction and Liver Cirrhosis: Unraveling of a Complex Relationship

Endothelial dysfunction (ED) is the in the background of multiple metabolic diseases and a key process in liver disease progression and cirrhosis decompensation. ED affects liver sinusoidal endothelial cells (LSECs) in response to different damaging agents, causing their progressive dedifferentiation, unavoidably associated with an increase in intrahepatic resistance that leads to portal hypertension and hyperdynamic circulation with increased cardiac output and low peripheral artery resistance. These changes are driven by a continuous interplay between different hepatic cell types, invariably leading to increased reactive oxygen species (ROS) formation, increased release of pro-inflammatory cytokines and chemokines, and reduced nitric oxide (NO) bioavailability, with a subsequent loss of proper vascular tone regulation and fibrosis development. ED evaluation is often accomplished by serum markers and the flow-mediated dilation (FMD) measurement of the brachial artery to assess its NO-dependent response to shear stress, which usually decreases in ED. In the context of liver cirrhosis, the ED assessment could help understand the complex hemodynamic changes occurring in the early and late stages of the disease. However, the instauration of a hyperdynamic state and the different NO bioavailability in intrahepatic and systemic circulation-often defined as the NO paradox-must be considered confounding factors during FMD analysis. The primary purpose of this review is to describe the main features of ED and highlight the key findings of the dynamic and intriguing relationship between ED and liver disease. We will also focus on the significance of FMD evaluation in this setting, pointing out its key role as a therapeutic target in the never-ending battle against liver cirrhosis progression.

Inflammasomes in chronic liver disease: Hepatic injury, fibrosis progression and systemic inflammation

Chronic liver disease leads to hepatocellular injury that triggers a pro-inflammatory state in several parenchymal and non-parenchymal hepatic cell types, ultimately resulting in liver fibrosis, cirrhosis, portal hypertension and liver failure. Thus, an improved understanding of inflammasomes - as key molecular drivers of liver injury - may result in the development of novel diagnostic or prognostic biomarkers and effective therapeutics. In liver disease, innate immune cells respond to hepatic insults by activating cell-intrinsic inflammasomes via toll-like receptors and NF-κB, and by releasing pro-inflammatory cytokines (such as IL-1β, IL-18, TNF-α and IL-6). Subsequently, cells of the adaptive immune system are recruited to fuel hepatic inflammation and hepatic parenchymal cells may undergo gasdermin D-mediated programmed cell death, termed pyroptosis. With liver disease progression, there is a shift towards a type 2 inflammatory response, which promotes tissue repair but also fibrogenesis. Inflammasome activation may also occur at extrahepatic sites, such as the white adipose tissue in MASH (metabolic dysfunction-associated steatohepatitis). In end-stage liver disease, flares of inflammation (e.g., in severe alcohol-related hepatitis) that spark on a dysfunctional immune system, contribute to inflammasome-mediated liver injury and potentially result in organ dysfunction/failure, as seen in ACLF (acute-on-chronic liver failure). This review provides an overview of current concepts regarding inflammasome activation in liver disease progression, with a focus on related biomarkers and therapeutic approaches that are being developed for patients with liver disease.

Signaling pathways that activate hepatic stellate cells during liver fibrosis

Liver fibrosis is a complex process driven by various factors and is a key feature of chronic liver diseases. Its essence is liver tissue remodeling caused by excessive accumulation of collagen and other extracellular matrix. Activation of hepatic stellate cells (HSCs), which are responsible for collagen production, plays a crucial role in promoting the progression of liver fibrosis. Abnormal expression of signaling pathways, such as the TGF-β/Smads pathway, contributes to HSCs activation. Recent studies have shed light on these pathways, providing valuable insights into the development of liver fibrosis. Here, we will review six signaling pathways such as TGF-β/Smads that have been studied more in recent years.

Progress on the Anti-Inflammatory Activity and Structure-Efficacy Relationship of Polysaccharides from Medical and Edible Homologous Traditional Chinese Medicines

Medicinal food varieties developed according to the theory of medical and edible homologues are effective at preventing and treating chronic diseases and in health care. As of 2022, 110 types of traditional Chinese medicines from the same source of medicine and food have been published by the National Health Commission. Inflammation is the immune system's first response to injury, infection, and stress. Chronic inflammation is closely related to many diseases such as atherosclerosis and cancer. Therefore, timely intervention for inflammation is the mainstay treatment for other complex diseases. However, some traditional anti-inflammatory drugs on the market are commonly associated with a number of adverse effects, which seriously affect the health and safety of patients. Therefore, the in-depth development of new safe, harmless, and effective anti-inflammatory drugs has become a hot topic of research and an urgent clinical need. Polysaccharides, one of the main active ingredients of medical and edible homologous traditional Chinese medicines (MEHTCMs), have been confirmed by a large number of studies to exert anti-inflammatory effects through multiple targets and are considered potential natural anti-inflammatory drugs. In addition, the structure of medical and edible homologous traditional Chinese medicines' polysaccharides (MEHTCMPs) may be the key factor determining their anti-inflammatory activity, which makes the underlying the anti-inflammatory effects of polysaccharides and their structure-efficacy relationship hot topics of domestic and international research. However, due to the limitations of the current analytical techniques and tools, the structures have not been fully elucidated and the structure-efficacy relationship is relatively ambiguous, which are some of the difficulties in the process of developing and utilizing MEHTCMPs as novel anti-inflammatory drugs in the future. For this reason, this paper summarizes the potential anti-inflammatory mechanisms of MEHTCMPs, such as the regulation of the Toll-like receptor-related signaling pathway, MAPK signaling pathway, JAK-STAT signaling pathway, NLRP3 signaling pathway, PI3K-AKT signaling pathway, PPAR-γ signaling pathway, Nrf2-HO-1 signaling pathway, and the regulation of intestinal flora, and it systematically analyzes and evaluates the relationships between the anti-inflammatory activity of MEHTCMPs and their structures.

Liver Fibrosis: From Basic Science towards Clinical Progress, Focusing on the Central Role of Hepatic Stellate Cells

The burden of chronic liver disease is globally increasing at an alarming rate. Chronic liver injury leads to liver inflammation and fibrosis (LF) as critical determinants of long-term outcomes such as cirrhosis, liver cancer, and mortality. LF is a wound-healing process characterized by excessive deposition of extracellular matrix (ECM) proteins due to the activation of hepatic stellate cells (HSCs). In the healthy liver, quiescent HSCs metabolize and store retinoids. Upon fibrogenic activation, quiescent HSCs transdifferentiate into myofibroblasts; lose their vitamin A; upregulate α-smooth muscle actin; and produce proinflammatory soluble mediators, collagens, and inhibitors of ECM degradation. Activated HSCs are the main effector cells during hepatic fibrogenesis. In addition, the accumulation and activation of profibrogenic macrophages in response to hepatocyte death play a critical role in the initiation of HSC activation and survival. The main source of myofibroblasts is resident HSCs. Activated HSCs migrate to the site of active fibrogenesis to initiate the formation of a fibrous scar. Single-cell technologies revealed that quiescent HSCs are highly homogenous, while activated HSCs/myofibroblasts are much more heterogeneous. The complex process of inflammation results from the response of various hepatic cells to hepatocellular death and inflammatory signals related to intrahepatic injury pathways or extrahepatic mediators. Inflammatory processes modulate fibrogenesis by activating HSCs and, in turn, drive immune mechanisms via cytokines and chemokines. Increasing evidence also suggests that cellular stress responses contribute to fibrogenesis. Recent data demonstrated that LF can revert even at advanced stages of cirrhosis if the underlying cause is eliminated, which inhibits the inflammatory and profibrogenic cells. However, despite numerous clinical studies on plausible drug candidates, an approved antifibrotic therapy still remains elusive. This state-of-the-art review presents cellular and molecular mechanisms involved in hepatic fibrogenesis and its resolution, as well as comprehensively discusses the drivers linking liver injury to chronic liver inflammation and LF.

Human Gut Microbiota in Cardiovascular Disease

The gut ecosystem, termed microbiota, is composed of bacteria, archaea, viruses, protozoa, and fungi and is estimated to outnumber human cells. Microbiota can affect the host by multiple mechanisms, including the synthesis of metabolites and toxins, modulating inflammation and interaction with other organisms. Advances in understanding commensal organisms' effect on human conditions have also elucidated the importance of this community for cardiovascular disease (CVD). This effect is driven by both direct CV effects and conditions known to increase CV risk, such as obesity, diabetes mellitus (DM), hypertension, and renal and liver diseases. Cardioactive metabolites, such as trimethylamine N -oxide (TMAO), short-chain fatty acids (SCFA), lipopolysaccharides, bile acids, and uremic toxins, can affect atherosclerosis, platelet activation, and inflammation, resulting in increased CV incidence. Interestingly, this interaction is bidirectional with microbiota affected by multiple host conditions including diet, bile acid secretion, and multiple diseases affecting the gut barrier. This interdependence makes manipulating microbiota an attractive option to reduce CV risk. Indeed, evolving data suggest that the benefits observed from low red meat and Mediterranean diet consumption can be explained, at least partially, by the changes that these diets may have on the gut microbiota. In this article, we depict the current epidemiological and mechanistic understanding of the role of microbiota and CVD. Finally, we discuss the potential therapeutic approaches aimed at manipulating gut microbiota to improve CV outcomes. © 2024 American Physiological Society. Compr Physiol 14:5449-5490, 2024.

Protective effects of dopamine against non-alcoholic steatohepatitis via inhibiting p65 pathways in vivo and in vitro

Introduction

Currently, the role and mechanism of dopamine in non-alcoholic steatohepatitis (NASH) remains unclear.

Methods

In vitro experiments utilized FFA and LPS to establish NASH cell models, while a fibrotic cell model was created using TGFβ1 to investigate the impact of dopamine on cellular lipid metabolism, inflammation, and fibrosis. In vivo experiments involved the use of MCD and HFD diets to induce NASH in mouse models for observing the effects of dopamine on NASH disease progression.

Results

Our study showed that dopamine significantly downregulated the expression levels of Caspase 1, IL-1β and IL18 in the HepG2 NASH cell model. In addition, dopamine could inhibit the TGF-β1-induced accumulation of collagen I and α-SMA in LX2 cells. In vivo experiments have shown that dopamine attenuation in mice is associated with MCD diet-induced and HFD-induced steatohepatitis. Mechanically, dopamine inhibits the p65 signaling pathway in NASH.

Conclusion

In conclusion, the present study demonstrates the role of dopamine in ameliorating the symptoms of NASH and provides a direction for future research on the application of the dopaminergic system to liver disease.

First-in-human safety, tolerability, and pharmacokinetic results of DFV890, an oral low-molecular-weight NLRP3 inhibitor

This first-in-human study evaluated the safety, tolerability, single- and multiple-dose pharmacokinetic profiles with dietary influence, and pharmacodynamics (PD) of DFV890, an oral NLRP3 inhibitor, in healthy participants. In total, 122 participants were enrolled into a three-part trial including single and 2-week multiple ascending oral doses (SAD and MAD, respectively) of DFV890, and were randomized (3:1) to DFV890 or placebo (SAD [3-600 mg] and MAD [fasted: 10-200 mg, once-daily or fed: 25 and 50 mg, twice-daily]). DFV890 was generally well-tolerated. Neither deaths nor serious adverse events were reported. A less than dose-proportional increase in exposure was observed with the initially used crystalline suspension (3-300 mg); however, an adjusted suspension formulation using spray-dried dispersion (SDD; 100-600 mg) confirmed dose-proportional increase in exposure. Relative bioavailability between crystalline suspension and tablets, and food effect were evaluated at 100 mg. Under fasting conditions, Cmax of the tablet yielded 78% compared with the crystalline suspension, and both formulations showed comparable AUC. The fed condition led to a 2.05- and 1.49-fold increase in Cmax and AUC0-last compared with the fasting condition. The median IC50 and IC90 for ex-vivo lipopolysaccharide-stimulated interleukin IL-1β release inhibition (PD) were 61 (90% CI: 50, 70) and 1340 ng/mL (90% CI: 1190, 1490). Crystalline tablets of 100 mg once-daily or 25 mg twice-daily were sufficient to maintain ~90% of the IL-1β release inhibition over 24 h at steady state. Data support dose and formulation selection for further development in diseases, in which an overactivated NLRP3 represents the underlying pathophysiology.

The Role of Cytokines in the Pathogenesis and Treatment of Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a major cause of chronic liver disease. This term covers a broad spectrum of liver lesions, from simple steatosis to alcoholic hepatitis and cirrhosis. The pathogenesis of ALD is multifactorial and not fully elucidated due to complex mechanisms related to direct ethanol toxicity with subsequent hepatic and systemic inflammation. The accumulation of pro-inflammatory cytokines and the reduction of anti-inflammatory cytokines promote the development and progression of ALD. To date, there are no targeted therapies to counter the progression of chronic alcohol-related liver disease and prevent acute liver failure. Corticosteroids reduce mortality by acting on the hepatic-systemic inflammation. On the other hand, several studies analyzed the effect of inhibiting pro-inflammatory cytokines and stimulating anti-inflammatory cytokines as potential therapeutic targets in ALD. This narrative review aims to clarify the role of the main cytokines involved in the pathogenesis and treatment of ALD.

Piperine alleviates nonalcoholic steatohepatitis by inhibiting NF-κB-mediated hepatocyte pyroptosis

PURPOSE

Nonalcoholic steatohepatitis (NASH) is the progressive form of nonalcoholic fatty liver disease (NAFLD), which has a high risk of cirrhosis, liver failure, and hepatocellular carcinoma. Piperine (Pip) is an extract of plants with powerful anti-inflammatory effects, however, the function of Pip in NASH remains elusive. Here, we aim to explore the role of Pip in NASH and to find the possible mechanisms.

METHODS

Methionine and choline-deficient (MCD) diets were used to induce steatohepatitis, methionine- and choline-sufficient (MCS) diets were used as the control. After Pip treatment, H&E staining, Oil Red O staining, hepatic triglyceride (TG) content and F4/80 expression were performed to analysis liver steatosis and inflammation; Masson's staining, COL1A1 and α-SMA were detected liver fibrosis. Lipopolysaccharide (LPS) -treated AML12 cells were used to as the cell model to induce pyroptosis. Then, pyroptosis-related proteins, IL-1β and LDH release were detected in vivo and in vitro. Finally, NF-κB inhibitor, BAY11-7082, was used to further demonstrate the mechanism of Pip in NASH.

RESULTS

The study found that Pip alleviated liver steatosis, inflammation, hepatocyte injury, and fibrosis in mice fed with MCD diets. Moreover, the pyroptosis markers (NLRP3, ASC, caspase-1 p20, and GSDMD), IL-1β and LDH release were decreased by Pip treatment. NF-κB activation was suppressed by Pip treatment and pyroptosis-related proteins were down regulated by BAY11-7082.

CONCLUSION

Pip ameliorates NASH progression, and the therapeutical effect was associated with inhibition of hepatocyte pyroptosis induced by NF-κB.

6,7-Dimethoxycoumarin, Gardenoside and Rhein combination improves non-alcoholic fatty liver disease in rats

ETHNOPHARMACOLOGICAL RELEVANCE

This study explores the potential therapeutic benefits of using a three-component DGR (composed of specific compounds) to target the NLRP3 inflammasome in the context of non-alcoholic fatty liver disease (NAFLD).

AIM OF THE STUDY

To assess the impact of a three-component DGR on NAFLD, specifically examining its effects on liver lipid accumulation, inflammation, and the diversity of intestinal microbial communities.

METHODS

NAFLD was induced in 8-week-old Sprague Dawley rats by feeding them a high-fat emulsion diet every morning for 8 consecutive weeks. Oral administration of DGR or its constituent equivalents in the afternoon. The pharmacological effects of DGR were evaluated using H&E, ORO and ELISA methods to determine the changes in serum and liver tissue indexes of rat-models. Immunohistochemical staining and Western blot were used to assess the interaction between DGR, NLRP3 and IL-1β.

RESULTS

The induction of NAFLD resulted in elevated hepatic triglycerides (TG), total cholesterol (TC), and free fatty acids (FFA). However, these alterations were ameliorated upon administration of DGR. It is noteworthy that DGR exhibited superior efficacy in comparison to its constituent compounds, manifesting augmented antioxidant activity, diminished hepatic damage, and the attenuation of pro-inflammatory factors. Both DGR and its individual monomeric constituents exhibited the capacity to attenuate the activation of the NLRP3 inflammasome in the liver, leading to an amelioration of the pathological characteristics associated with NAFLD. An analysis of the intestinal flora unveiled an elevated abundance of p_Firmicutes (1.1-fold), p_Cyanobacteria (5.76-fold), and p_Verrucomicrobia (5.2-fold), accompanied by a heightened p_Firmicutes to p_Bacteroidetes ratio (5.49-fold).

CONCLUSIONS

In the non-alcoholic fatty liver disease (NAFLD) rat model, the concurrent administration of three-component DGR effectively regulated lipid deposition, suppressed liver inflammation, and restored balance in the intestinal flora, thereby improving NAFLD pathology. These findings propose a promising therapeutic strategy for NAFLD, centered on inhibiting the NLRP3 inflammasome through the use of the three-component DGR.

Hepatic danger signaling triggers TREM2+ macrophage induction and drives steatohepatitis via MS4A7-dependent inflammasome activation

Metabolic dysfunction-associated steatohepatitis (MASH), formerly known as nonalcoholic steatohepatitis (NASH), is an advanced stage of metabolic fatty liver disease. The pathogenic mechanisms of MASH center on hepatocyte injury and the ensuing immune response within the liver microenvironment. Recent work has implicated TREM2+ macrophages in various disease conditions, and substantial induction of TREM2+ NASH-associated macrophages (NAMs) serves as a hallmark of metabolic liver disease. Despite this, the mechanisms through which NAMs contribute to MASH pathogenesis remain poorly understood. Here, we identify membrane-spanning 4-domains a7 (MS4A7) as a NAM-specific pathogenic factor that exacerbates MASH progression in mice. Hepatic MS4A7 expression was strongly induced in mouse and human MASH and associated with the severity of liver injury. Whole-body and myeloid-specific ablation of Ms4a7 alleviated diet-induced MASH pathologies in male mice. We demonstrate that exposure to lipid droplets (LDs), released upon injury of steatotic hepatocytes, triggered NAM induction and exacerbated MASH-associated liver injury in an MS4A7-dependent manner. Mechanistically, MS4A7 drove NLRP3 inflammasome activation via direct physical interaction and shaped disease-associated cell states within the liver microenvironment. This work reveals the LD-MS4A7-NLRP3 inflammasome axis as a pathogenic driver of MASH progression and provides insights into the role of TREM2+ macrophages in disease pathogenesis.

LanGui tea, an herbal medicine formula, protects against binge alcohol-induced acute liver injury by activating AMPK-NLRP3 signaling

BACKGROUND

LanGui tea, a traditional Chinese medicine formulation comprising of Gynostemma pentaphyllum (Thunb.) Makino, Cinnamomum cassia (L.) J. Presl, and Ampelopsis grossedentata (Hand-Mazz) W.T. Wang, has yet to have its potential contributions to alcoholic liver disease (ALD) fully elucidated. Consequently, the objective of this research is to investigate the protective properties of LanGui tea against binge alcohol-induced ALD and the mechanisms underlying its effects.

METHODS

An experimental model of acute alcohol-induced liver disease was performed to assess the protective effects of extract of LanGui tea (ELG) at both 50 and 100 mg.kg-1 dosages on male C57BL/6 mice. Various parameters, including hepatic histological changes, inflammation, lipids content, as well as liver enzymes and interleukin 1β (IL-1β) in the serum were measured. The pharmacological mechanisms of ELG, specifically its effects on adenosine monophosphate-(AMP)-activated protein kinase (AMPK) and NLR family pyrin domain containing 3 (NLRP3) signaling, were investigated through Western blotting, qRT-PCR, ELISA, immunohistochemistry, immunofluorescence analyses, and by blocking the AMPK activity.

RESULTS

ELG demonstrated a mitigating effect on fatty liver, inflammation, and hepatic dysfunction within the mouse model. This effect was achieved by activating AMPK signaling and inhibitingNLRP3 signaling in the liver, causing a reduction in IL-1β generation. In vitro studies further confirmed that ELG inhibited cell damage and IL-1β production in ethanol-induced hepatocytes by enhancing AMPK-NLRP3 signaling. Conversely, the pharmacological inhibition of AMPK activity nearly abrogated such alteration.

CONCLUSIONS

Thus, LanGui tea emerges as a promising herbal therapy for ALD management involving AMPK-NLRP3 signaling.

"Other Than NLRP3" Inflammasomes: Multiple Roles in Brain Disease

Human neuroinflammatory and neurodegenerative diseases, whose prevalence keeps rising, are still unsolved pathobiological/therapeutical problems. Among others, recent etiology hypotheses stressed as their main driver a chronic neuroinflammation, which is mediated by innate immunity-related protein oligomers: the inflammasomes. A panoply of exogenous and/or endogenous harmful agents activates inflammasomes' assembly, signaling, and IL-1β/IL-18 production and neural cells' pyroptotic death. The underlying concept is that inflammasomes' chronic activation advances neurodegeneration while their short-lasting operation restores tissue homeostasis. Hence, from a therapeutic standpoint, it is crucial to understand inflammasomes' regulatory mechanisms. About this, a deluge of recent studies focused on the NLRP3 inflammasome with suggestions that its pharmacologic block would hinder neurodegeneration. Yet hitherto no evidence proves this view. Moreover, known inflammasomes are numerous, and the mechanisms regulating their expression and function may vary with the involved animal species and strains, as well as organs and cells, and the harmful factors triggered as a result. Therefore, while presently leaving out some little-studied inflammasomes, this review focuses on the "other than NLRP3" inflammasomes that participate in neuroinflammation's complex mechanisms: NLRP1, NLRP2, NLRC4, and AIM2. Although human-specific data about them are relatively scant, we stress that only a holistic view including several human brain inflammasomes and other potential pathogenetic drivers will lead to successful therapies for neuroinflammatory and neurodegenerative diseases.

Myeloid-specific ablation of Basp1 ameliorates diet-induced NASH in mice by attenuating pro-inflammatory signaling

BACKGROUND AND AIMS

NASH represents a severe stage of fatty liver disease characterized by hepatocyte injury, inflammation, and liver fibrosis. Myeloid-derived innate immune cells, such as macrophages and dendritic cells, play an important role in host defense and disease pathogenesis. Despite this, the nature of transcriptomic reprogramming of myeloid cells in NASH liver and its contribution to disease progression remain incompletely defined.

APPROACH AND RESULTS

In this study, we performed bulk and single-cell RNA sequencing (sc-RNA seq) analysis to delineate the landscape of macrophage and dendritic cell transcriptomes in healthy and NASH livers. Our analysis uncovered cell type-specific patterns of transcriptomic reprogramming on diet-induced NASH. We identified brain-abundant membrane-attached signal protein 1 (Basp1) as a myeloid-enriched gene that is markedly induced in mouse and human NASH liver. Myeloid-specific inactivation of Basp1 attenuates the severity of diet-induced NASH pathologies, as shown by reduced hepatocyte injury and liver fibrosis in mice. Mechanistically, cultured macrophages lacking Basp1 exhibited a diminished response to pro-inflammatory stimuli, impaired NLRP3 inflammasome activation, and reduced cytokine secretion.

CONCLUSIONS

Together, these findings uncover Basp1 as a critical regulator of myeloid inflammatory signaling that underlies NASH pathogenesis.

Maternal betaine supplementation ameliorates fatty liver disease in offspring mice by inhibiting hepatic NLRP3 inflammasome activation

BACKGROUND/OBJECTIVES

Previous research has shown maternal betaine supplementation alleviates fetal-derived hepatic steatosis. Therefore, this study examined the anti-inflammatory effect of maternal betaine intake in offspring mice and its mechanism.

MATERIALS/METHODS

Female C57BL/6J mice and their offspring were randomly divided into 3 groups according to the treatment received during gestation and lactation: control diet (CD), fatty liver disease (FLD), and fatty liver disease + 1% betaine (FLD-BET). The FLD group was given a high-fat diet and streptozotocin (HFD + STZ), and the FLD-BET group was treated with HFD + STZ + 1% betaine. After weaning, the offspring mice were given a normal diet for 5 weeks and then dissected to measure the relevant indexes.

RESULTS

Compared to the CD group, the offspring mice in the FLD group revealed obvious hepatic steatosis and increased serum levels of alanine aminotransferase, interleukin (IL)-6, and tumor necrosis factor (TNF)-α; maternal betaine supplementation reversed these changes. The hepatic mRNA expression levels of IL-6, IL-18, and Caspase-1 were significantly higher in the FLD group than in the CD group. Maternal betaine supplementation reduced the expression of IL-1β, IL-6, IL-18, and apoptosis-associated speck-like protein containing C-terminal caspase recruitment domain (ASC). Maternal betaine supplementation also reversed the increasing protein expressions of nitric oxide dioxygenase-like receptor family pyrin domain containing 3 (NLRP3), ASC, Caspase-1, IL-1β, and IL-18 in offspring mice exposed to HFD + STZ. Maternal betaine supplementation decreased the homocysteine (Hcy) and s-adenosine homocysteine (SAH) levels significantly in the livers. Furthermore, the hepatic Hcy concentrations showed significant inverse relationships with the mRNA expression of TNF-α, NLRP3, ASC, and IL-18. The hepatic SAH concentration was inversely associated with the IL-1β mRNA expression.

CONCLUSIONS

The lipotropic and anti-inflammatory effect of maternal betaine supplementation may be associated with the inhibition of NLRP3 inflammasome in the livers of the offspring mice.

The intersection between alcohol-related liver disease and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) and alcohol-related liver disease (ALD) are the leading causes of chronic liver disease worldwide. NAFLD and ALD share pathophysiological, histological and genetic features and both alcohol and metabolic dysfunction coexist as aetiological factors in many patients with hepatic steatosis. A diagnosis of NAFLD requires the exclusion of significant alcohol consumption and other causes of liver disease. However, data suggest that significant alcohol consumption is often under-reported in patients classified as having NAFLD and that alcohol and metabolic factors interact to exacerbate the progression of liver disease. In this Review, we analyse existing data on the interaction between alcohol consumption and metabolic syndrome as well as the overlapping features and differences in the pathogenesis of ALD and NAFLD. We also discuss the clinical implications of the coexistence of alcohol consumption, of any degree, in patients with evidence of metabolic derangement as well as the use of alcohol biomarkers to detect alcohol intake. Finally, we summarize the evolving nomenclature of fatty liver disease and describe a recent proposal to classify patients at the intersection of NAFLD and ALD. We propose that, regardless of the presumed aetiology, patients with fatty liver disease should be evaluated for both metabolic syndrome and alcohol consumption to enable better prognostication and a personalized medicine approach.

Hepatic Macrophages as Targets for the MSC-Based Cell Therapy in Non-Alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) is a serious public health issue associated with the obesity pandemic. Obesity is the main risk factor for the non-alcoholic fatty liver disease (NAFLD), which progresses to NASH and then to end-stage liver disease. Currently, there are no specific pharmacotherapies of NAFLD/NASH approved by the FDA or other national regulatory bodies and the treatment includes lifestyle adjustment and medicines for improving lipid metabolism, enhancing sensitivity to insulin, balancing oxidation, and counteracting fibrosis. Accordingly, further basic research and development of new therapeutic approaches are greatly needed. Mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles prevent induced hepatocyte death in vitro and attenuate NASH symptoms in animal models of the disease. They interact with hepatocytes directly, but also target other liver cells, including Kupffer cells and macrophages recruited from the blood flow. This review provides an update on the pathogenesis of NAFLD/NASH and the key role of macrophages in the development of the disease. We examine in detail the mechanisms of the cross-talk between the MSCs and the macrophages, which are likely to be among the key targets of MSCs and their derivatives in the course of NAFLD/NASH cell therapy.

The alleviating effect of Scutellaria amoena extract on the regulation of gut microbiota and its metabolites in NASH rats by inhibiting the NLRP3/ASC/caspase-1 axis

Background: Scutellaria amoena (SA) is the root of S. amoena C.H. Wright of Labiatae, also known as Scutellaria southwestern. This is mainly distributed in Sichuan, Yunnan, and Guizhou in China. In southwest China, SA is used as an alternative method to genuine medicine for the treatment of allergy, diarrhea, inflammation, hepatitis, and bronchitis. Thus far, studies on the effects of SA on non-alcoholic steatohepatitis (NASH) are lacking. This paper investigated the effect of SA on the regulation of gut microbiota and its metabolites in NASH rats by inhibiting the NOD-like receptor 3 (NLRP3)/apoptosis-associated speck-like protein (ASC)/caspase-1 axis. Methods: A NASH rat model was induced by a high-fat diet (HFD) for 12 weeks, and rats were orally given different doses of SA extracts (150 and 300 mg/kg/d) for 6 weeks. Changes in histological parameters, body weight, organ indexes, cytokines, and biochemical parameters related to NLRP3 in NASH rats were checked. 16S rRNA gene sequencing and UPLC-MS/MS technology were used to analyze the changes in the gut microbiota composition and its metabolites in NASH rats. Results: SA significantly inhibited the HFD-induced increase in body weight, lipid levels, and inflammatory infiltration. SA notably inhibited the HFD-induced increase in the upper and lower factors of NLRP3, such as transforming growth factor (TGF)-β, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-18, pro-IL-18, IL-1β, pro-IL-1β, NLRP3, ASC, and caspase-1. Additionally, mRNA expressions of caspase-1, NLRP3, and ASC were significantly downregulated after SA treatment. The results of the intestinal flora showed that SA could increase the diversity of flora and change its structure and composition in NASH rats by reducing Firmicutes/Bacteroidetes (F/B) ratio, Blautia (genus), Lachospiraceae (family), and Christensenellaceae R-7 group (genus), and increasing Muribaculaceae (family) and Bacteroides (genus). The metabolomics revealed that 24 metabolites were possibly the key metabolites for SA to regulate the metabolic balance of NASH rats, including chenodeoxycholic acid, xanthine, and 9-OxoODE. Nine metabolic pathways were identified, including primary bile acid biosynthesis, bile secretion, purine metabolism, and secondary bile acid biosynthesis. Conclusion: SA can regulate the intestinal microbial balance and metabolic disorder by inhibiting the NLRP3/ASC/caspase-1 axis to relieve NASH.

Therapeutic modulation of the liver immune microenvironment

Inflammation is a hallmark of progressive liver diseases such as chronic viral or immune-mediated hepatitis, alcohol-associated liver disease, and NAFLD. Preclinical and clinical studies have provided robust evidence that cytokines and related cellular stress sensors in innate and adaptive immunity orchestrate hepatic disease processes. Unresolved inflammation and liver injury result in hepatic scarring, fibrosis, and cirrhosis, which may culminate in HCC. Liver diseases are accompanied by gut dysbiosis and a bloom of pathobionts, fueling hepatic inflammation. Anti-inflammatory strategies are extensively used to treat human immune-mediated conditions beyond the liver, while evidence for immunomodulatory therapies and cell therapy-based strategies in liver diseases is only emerging. The development and establishment of novel immunomodulatory therapies for chronic liver diseases has been dampened by several clinical challenges, such as invasive monitoring of therapeutic efficacy with liver biopsy in clinical trials and risk of DILI in several studies. Such aspects prevented advancements of novel medical therapies for chronic inflammatory liver diseases. New concepts modulating the liver immune environment are studied and eagerly awaited to improve the management of chronic liver diseases in the future.

Inflammatory signaling in NASH driven by hepatocyte mitochondrial dysfunctions

Liver steatosis, inflammation, and variable degrees of fibrosis are the pathological manifestations of nonalcoholic steatohepatitis (NASH), an aggressive presentation of the most prevalent chronic liver disease in the Western world known as nonalcoholic fatty liver (NAFL). Mitochondrial hepatocyte dysfunction is a primary event that triggers inflammation, affecting Kupffer and hepatic stellate cell behaviour. Here, we consider the role of impaired mitochondrial function caused by lipotoxicity during oxidative stress in hepatocytes. Dysfunction in oxidative phosphorylation and mitochondrial ROS production cause the release of damage-associated molecular patterns from dying hepatocytes, leading to activation of innate immunity and trans-differentiation of hepatic stellate cells, thereby driving fibrosis in NASH.

The role of neutrophils in alcohol-related hepatitis

Alcohol-related liver disease is a major cause of liver disease-associated mortality, with inpatient care being a major contributor to its clinical and economic burden. Alcohol-related hepatitis (AH) is an acute inflammatory form of alcohol-related liver disease. Severe AH is associated with high short-term mortality, with infection being a common cause of death. The presence of AH is associated with increased numbers of circulating and hepatic neutrophils. We review the literature on the role of neutrophils in AH. In particular, we explain how neutrophils are recruited to the inflamed liver and how their antimicrobial functions (chemotaxis, phagocytosis, oxidative burst, NETosis) may be altered in AH. We highlight evidence for the existence of 'high-density' and 'low-density' neutrophil subsets. We also describe the potentially beneficial roles of neutrophils in the resolution of injury in AH through their effects on macrophage polarisation and hepatic regeneration. Finally, we discuss how manipulation of neutrophil recruitment/function may be used as a therapeutic strategy in AH. For example, correction of gut dysbiosis in AH could help to prevent excess neutrophil activation, or treatments could aim to enhance miR-223 function in AH. The development of markers that can reliably distinguish neutrophil subsets and of animal models that accurately reproduce human disease will be crucial for facilitating translational research in this important field.

Hepatic inflammatory responses in liver fibrosis

Chronic liver diseases such as nonalcoholic fatty liver disease (NAFLD) or viral hepatitis are characterized by persistent inflammation and subsequent liver fibrosis. Liver fibrosis critically determines long-term morbidity (for example, cirrhosis or liver cancer) and mortality in NAFLD and nonalcoholic steatohepatitis (NASH). Inflammation represents the concerted response of various hepatic cell types to hepatocellular death and inflammatory signals, which are related to intrahepatic injury pathways or extrahepatic mediators from the gut-liver axis and the circulation. Single-cell technologies have revealed the heterogeneity of immune cell activation concerning disease states and the spatial organization within the liver, including resident and recruited macrophages, neutrophils as mediators of tissue repair, auto-aggressive features of T cells as well as various innate lymphoid cell and unconventional T cell populations. Inflammatory responses drive the activation of hepatic stellate cells (HSCs), and HSC subsets, in turn, modulate immune mechanisms via chemokines and cytokines or transdifferentiate into matrix-producing myofibroblasts. Current advances in understanding the pathogenesis of inflammation and fibrosis in the liver, mainly focused on NAFLD or NASH owing to the high unmet medical need, have led to the identification of several therapeutic targets. In this Review, we summarize the inflammatory mediators and cells in the diseased liver, fibrogenic pathways and their therapeutic implications.

Ambiguous Pathogenic Roles of Macrophages in Alcohol-Associated Liver Diseases

Alcohol-associated liver disease (ALD) represents a major public health issue worldwide and is a leading etiology of liver cirrhosis. Alcohol-related liver injuries include a range of manifestations including alcoholic hepatitis (AH), simple steatosis, steatohepatitis, hepatic fibrosis, cirrhosis and liver cancer. Liver disease occurs from several pathological disturbances such as the metabolism of ethanol, which generates reactive oxygen species (ROS) in hepatocytes, alterations in the gut microbiota, and the immune response to these changes. A common hallmark of these liver affections is the establishment of an inflammatory environment, and some (broad) anti-inflammatory approaches are used to treat AH (eg, corticosteroids). Macrophages, which represent the main innate immune cells in the liver, respond to a wide variety of (pathogenic) stimuli and adopt a large spectrum of phenotypes. This translates to a diversity of functions including pathogen and debris clearance, recruitment of other immune cells, activation of fibroblasts, or tissue repair. Thus, macrophage populations play a crucial role in the course of ALD, but the underlying mechanisms driving macrophage polarization and their functionality in ALD are complex. In this review, we explore the various populations of hepatic macrophages in alcohol-associated liver disease and the underlying mechanisms driving their polarization. Additionally, we summarize the crosstalk between hepatic macrophages and other hepatic cell types in ALD, in order to support the exploration of targeted therapeutics by modulating macrophage polarization.

A novel role of RNase L in the development of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and affects about 25% of the population globally. NAFLD has the potential to cause significant liver damage in many patients because it can progress to nonalcoholic steatohepatitis (NASH) and cirrhosis, which substantially increases disease morbidity and mortality. Despite the key role of innate immunity in the disease progression, the underlying molecular and pathogenic mechanisms remain to be elucidated. RNase L is a key enzyme in interferon action against viral infection and displays pleiotropic biological functions such as control of cell proliferation, apoptosis, and autophagy. Recent studies have demonstrated that RNase L is involved in innate immunity. In this study, we revealed that RNase L contributed to the development of NAFLD, which further progressed to NASH in a time-dependent fashion after RNase L wild-type (WT) and knockout mice were fed with a high-fat and high-cholesterol diet. RNase L WT mice showed significantly more severe NASH, evidenced by widespread macro-vesicular steatosis, hepatocyte ballooning degeneration, inflammation, and fibrosis, although physiological and biochemical data indicated that both types of mice developed obesity, hyperglycemia, hypercholesterolemia, dysfunction of the liver, and systemic inflammation at different extents. Further investigation demonstrated that RNase L was responsible for the expression of some key genes in lipid metabolism, inflammation, and fibrosis signaling. Taken together, our results suggest that a novel therapeutic intervention for NAFLD may be developed based on regulating the expression and activity of RNase L.

The role of pyroptosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the main histologic type of liver cancer. It accounts for the majority of all diagnoses and deaths due to liver cancer. The induction of tumor cell death is an effective strategy to control tumor development. Pyroptosis is an inflammatory programmed cell death caused by microbial infection, accompanied by activation of inflammasomes and release of pro-inflammatory cytokines, interleukin-1β (IL-1β), and interleukin-18 (IL-18). The cleavage of gasdermins (GSDMs) promotes the occurrence of pyroptosis leading to cell swelling, lysis, and death. Accumulating evidence has indicated that pyroptosis influences the progression of HCC by regulating immune-mediated tumor cell death. Currently, some researchers hold the view that inhibition of pyroptosis-related components may prevent the incidence of HCC, but more researchers have the view that activation of pyroptosis exerts a tumor-inhibitory effect. Growing evidence indicates that pyroptosis can prevent or promote tumor development depending on the type of tumor. In this review, pyroptosis pathways and pyroptosis-related components were discussed. Next, the role of pyroptosis and its components in HCC was described. Finally, the therapeutic significance of pyroptosis in HCC was discussed.

An integrated view of anti-inflammatory and antifibrotic targets for the treatment of NASH

Successful development of treatments for non-alcoholic fatty liver disease (NAFLD) and its progressive form, non-alcoholic steatohepatitis (NASH) has been challenging. Because NASH and fibrosis lead to NAFLD progression towards cirrhosis and to clinical outcomes, approaches have either sought to attenuate metabolic dysregulation and cell injury, or directly target the inflammation and fibrosis that ensue. Targets for reducing the activation of inflammatory cascades include nuclear receptor agonists (thyroid hormone receptor-beta, e.g. resmetirom, peroxisome proliferator-activated receptor [PPAR], e.g. lanifibranor, farnesoid X receptor [FXR], e.g. obeticholic acid), modulators of lipotoxicity (e.g. aramchol, acetyl-CoA carboxylase inhibitors) or modification of genetic variants (e.g. PNPLA3 gene silencing). Extrahepatic inflammatory signals from circulation, adipose tissue or gut are targets of hormonal agonists (e.g. glucagon-like peptide-1 [GLP-1] like semaglutide, fibroblast growth factor [FGF]-19 or FGF21), microbiota or lifestyle (weight loss, diet, exercise) interventions. Stress signals and hepatocyte death activate immune responses engaging innate (macrophages, lymphocytes) and adaptive (auto-aggressive T-cells) mechanisms. Therapies seek to blunt immune cell activation, recruitment (chemokine receptor inhibitors) and responses (e.g. galectin 3 inhibition, anti-platelet drugs). The disease-driving pathways of NASH converge to elicit fibrosis, which is reversible. The activation of hepatic stellate cells (HSC) into matrix-producing myofibroblasts can be inhibited by antagonizing soluble factors (e.g. integrins, cytokines), cellular crosstalk (e.g. with macrophages), and agonizing nuclear receptor signaling (e.g. FXR or PPAR agonists). In advanced fibrosis, cell therapy with restorative macrophages or reprogrammed T-cells (e.g., CAR T) may accelerate repair through HSC deactivation or killing, or by enhancing matrix degradation. Heterogeneity of disease - either due to genetics or divergent disease drivers - is an obstacle to defining effective drugs for all patients with NASH that will be incrementally overcome.

Liver Lipidomics Analysis Revealed the Novel Ameliorative Mechanisms of L-Carnitine on High-Fat Diet-Induced NAFLD Mice

The beneficial effects of L-carnitine on non-alcoholic fatty liver disease (NAFLD) were revealed in previous reports. However, the underlying mechanisms remain unclear. In this study, we established a high fat diet (HFD)-induced NAFLD mice model and systematically explored the effects and mechanisms of dietary L-carnitine supplementation (0.2% to 4%) on NAFLD. A lipidomics approach was conducted to identify specific lipid species involved in the ameliorative roles of L-carnitine in NAFLD. Compared with a normal control group, the body weight, liver weight, concentrations of TG in the liver and serum AST and ALT levels were dramatically increased by HFD feeding (p < 0.05), accompanied with obvious liver damage and the activation of the hepatic TLR4/NF-κB/NLRP3 inflammatory pathway. L-carnitine treatment significantly improved these phenomena and exhibited a clear dose–response relationship. The results of a liver lipidomics analysis showed that a total of 12 classes and 145 lipid species were identified in the livers. Serious disorders in lipid profiles were noticed in the livers of the HFD-fed mice, such as an increased relative abundance of TG and a decreased relative abundance of PC, PE, PI, LPC, LPE, Cer and SM (p < 0.05). The relative contents of PC and PI were significantly increased and that of DG were decreased after the 4% L-carnitine intervention (p < 0.05). Moreover, we identified 47 important differential lipid species that notably separated the experimental groups based on VIP ≥ 1 and p < 0.05. The results of a pathway analysis showed that L-carnitine inhibited the glycerolipid metabolism pathway and activated the pathways of alpha-linolenic acid metabolism, glycerophospholipid metabolism, sphingolipid metabolism and Glycosylphosphatidylinositol (GPI)-anchor biosynthesis. This study provides novel insights into the mechanisms of L-carnitine in attenuating NAFLD.

Role of immune responses for development of NAFLD-associated liver cancer and prospects for therapeutic modulation

The liver is the central metabolic organ of the body regulating energy and lipid metabolism and at the same time has potent immunological functions. Overwhelming the metabolic capacity of the liver by obesity and sedentary lifestyle leads to hepatic lipid accumulation, chronic necro-inflammation, enhanced mitochondrial/ER-stress and development of non-alcoholic fatty liver disease (NAFLD), with its pathologic form nonalcoholic steatohepatitis (NASH). Based on knowledge on pathophysiological mechanisms, specifically targeting metabolic diseases to prevent or slow down progression of NAFLD to liver cancer will become possible. Genetic/environmental factors contribute to development of NASH and liver cancer progression. The complex pathophysiology of NAFLD-NASH is reflected by environmental factors, particularly the gut microbiome and its metabolic products. NAFLD-associated HCC occurs in most of the cases in the context of a chronically inflamed liver and cirrhosis. Recognition of environmental alarmins or metabolites derived from the gut microbiota and the metabolically injured liver create a strong inflammatory milieu supported by innate and adaptive immunity. Several recent studies indicate that the chronic hepatic microenvironment of steatosis induces auto-aggressive CD8+CXCR6+PD1+ T cells secreting TNF and upregulating FasL to eliminate parenchymal and non-parenchymal cells in an antigen independent manner. This promotes chronic liver damage and a pro-tumorigenic environment. CD8+CXCR6+PD1+ T cells possess an exhausted, hyperactivated, resident phenotype and trigger NASH to HCC transition, and might be responsible for a less efficient treatment response to immune-check-point inhibitors - in particular atezolizumab/bevacizumab. Here, we provide an overview of NASH-related inflammation/pathogenesis focusing on new discoveries on the role of T cells in NASH-immunopathology and therapy response. This review discusses preventive measures to halt disease progression to liver cancer and therapeutic strategies to manage NASH-HCC patients.

Current and emerging therapies for alcohol-associated hepatitis

Alcohol-related liver disease (ALD) encompasses a spectrum of diseases caused by excessive alcohol consumption. ALD includes hepatic steatosis, steatohepatitis, variable degrees of fibrosis, cirrhosis, and alcohol-associated hepatitis (AH), the latter being the most severe acute form of the disease. Severe AH is associated with high mortality (reaching up to 30%-50%) at 90 days. The cornerstone of ALD, and particularly AH, treatment continues to be abstinence, accompanied by support measures such as nutritional supplementation and management of alcohol withdrawal syndrome (AWS). In severe AH with model for end-stage liver disease (MELD) score ≥21, corticosteroids can be used, especially MELD score between 25 and 39, where the highest benefit is achieved. Other key aspects of treatment include the early identification of infections and their associated management and the proper identification of potential candidates for liver transplantation. The development of new therapies based on the pathophysiology and mechanisms of liver injury are underway. This includes the modulation and management of the innate immune response, gut dysbiosis, bacterial translocation, and bacteria-derived products from the intestine. These hold promise for the future of AH treatment.

The contradictory roles of macrophages in non-alcoholic fatty liver disease and primary liver cancer-Challenges and opportunities

Chronic liver diseases from varying etiologies generally lead to liver fibrosis and cirrhosis. Among them, non-alcoholic fatty liver disease (NAFLD) affects roughly one-quarter of the world population, thus representing a major and increasing public health burden. Chronic hepatocyte injury, inflammation (non-alcoholic steatohepatitis, NASH) and liver fibrosis are recognized soils for primary liver cancer, particularly hepatocellular carcinoma (HCC), being the third most common cause for cancer-related deaths worldwide. Despite recent advances in liver disease understanding, therapeutic options on pre-malignant and malignant stages remain limited. Thus, there is an urgent need to identify targetable liver disease-driving mechanisms for the development of novel therapeutics. Monocytes and macrophages comprise a central, yet versatile component of the inflammatory response, fueling chronic liver disease initiation and progression. Recent proteomic and transcriptomic studies performed at singular cell levels revealed a previously overlooked diversity of macrophage subpopulations and functions. Indeed, liver macrophages that encompass liver resident macrophages (also named Kupffer cells) and monocyte-derived macrophages, can acquire a variety of phenotypes depending on microenvironmental cues, and thus exert manifold and sometimes contradictory functions. Those functions range from modulating and exacerbating tissue inflammation to promoting and exaggerating tissue repair mechanisms (i.e., parenchymal regeneration, cancer cell proliferation, angiogenesis, fibrosis). Due to these central functions, liver macrophages represent an attractive target for the treatment of liver diseases. In this review, we discuss the multifaceted and contrary roles of macrophages in chronic liver diseases, with a particular focus on NAFLD/NASH and HCC. Moreover, we discuss potential therapeutic approaches targeting liver macrophages.

Chronic high-fat diet induces galectin-3 and TLR4 to activate NLRP3 inflammasome in NASH

NOD-like receptor protein 3 (NLRP3) inflammasome activation triggers inflammation progression in some metabolism disorders, frequently accompanying the up-regulation of galectin-3 (Gal-3). However, the precise mechanisms of Gal-3 activating NLRP3 inflammasome remain unclear in nonalcoholic steatohepatitis (NASH). Here, male C57BL/6J mice were fed by high-fat diet (HFD) for 32 weeks to induce NASH and then the hepatic damage, cytokines, Gal-3 and TLR4 expression, and NLRP3 inflammasome activation were examined. Such indicators were similarly determined when HepG2 cells were co-incubated with palmitic acid (PA, 200 μM), β-lactose, and TAK-242, or pre-transfected with TLR4. Immunofluorescence, immunohistochemistry, and co-immunoprecipitation were conducted to confirm the potential interaction between Gal-3 and TLR4. To further identify the inflammatory regulation roles of Gal-3 and its terminals in TLR4/NLRP3, HepG2 cells were transfected with Gal-3 and its variants. Chronic HFD induced sustained hepatic steatosis and inflammatory injury, with increased inflammatory cytokines, Gal-3 and TLR4 expression, and NLRP3 inflammasome activation. Similar changes were found in PA-dosed HepG2 cells, which were rescued by β-lactose but deteriorated with TLR4 overexpression. However, TAK-242 treatment decreased AST, ALT, cytokines, and normalized NLRP3, caspase-1, and ASC expression. Furthermore, TLR4 was pulled down when Gal-3 was enriched. Only full-length Gal-3 and its carbohydrate recognition domain (CRD) promoted cytokines, TLR4 expression, and NLRP3 inflammasome activation. Thus, gal-3 may induce chronic HFD-derived NASH progression by activating TLR4-mediating NLRP3 inflammasome via its CRD, which sheds new light on candidate target for the treatment and prevention of NASH inflammation despite further research for its precise roles in the future.

Quercetin potentiates the hepatoprotective effect of sildenafil and/or pentoxifylline against intrahepatic cholestasis: Role of Nrf2/ARE, TLR4/NF-κB, and NLRP3/IL-1β signaling pathways

AIM

Intrahepatic cholestasis is a common pathological condition of several types of liver disorders. In this study, we aimed to investigate the regulatory effects of quercetin (QU) on selected phosphodiesterase inhibitors against alpha-naphthyl isothiocyanate (ANIT)-induced acute intrahepatic cholestasis.

METHODS

Cholestasis was induced in Wistar albino rats by ANIT as a single dose (60 mg/kg; P·O.). QU (50 mg/kg, daily, P·O.), sildenafil (Sild; 10 mg/kg, twice daily, P·O.), and pentoxifylline (PTX; 50 mg/kg, daily, P.O.) were evaluated either alone or in combinations for 10 days for their antioxidant, anti-inflammatory, and anti-pyroptotic effects.

RESULTS

ANIT produced a prominent intrahepatic cholestasis as evidenced by a significant alteration in liver functions, histological structure, inflammatory response, and oxidative stress biomarkers. Furthermore, up-regulation of NF-κB-p65, TLR4, NLRP3, cleaved caspase-1, IKK-β, and IL-1β concurrently with down-regulation of Nrf-2, HO-1, and PPAR-γ expressions were observed after ANIT. QU, Sild, or PTX treatment significantly alleviated the disturbance induced by ANIT. These findings were further supported by the improvement in histopathological features. Additionally, co-administration of QU with Sild or PTX significantly improved liver defects due to ANIT as compared to the individual drugs.

SIGNIFICANCE

Combined QU with Sild or PTX exhibited promising hepatoprotective effects and anti-cholestatic properties through modulation of Nrf2/ARE, TLR4/NF- κB, and NLRP3/IL-1β signaling pathways.

Activation of the NLRP3 inflammasome by CCl4 exacerbates hepatopathogenic diet-induced experimental NASH

INTRODUCTION AND OBJECTIVES

Administration of carbon tetrachloride (CCl₄), along with an hepatopathogenic diet, is widely employed as a chemical inducer to replicate human nonalcoholic steatohepatitis (NASH) in rodents; however, the role of the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome in this model remains unclear. We aimed to determine the relevance of NLRP3 inflammasome activation in the development of NASH induced by CCl₄ along with an hepatopathogenic diet in male Wistar rats.

MATERIALS AND METHODS

Animals were fed either a high fat, sucrose, and cholesterol diet (HFSCD) or a HFSCD plus intraperitoneal injections of low doses of CCl₄ (400 mg/kg) once a week for 15 weeks. Liver steatosis, inflammation, fibrosis, and NLRP3 inflammasome activation were evaluated using biochemical, histological, ultrastructural, and immunofluorescence analyses, western blotting, and immunohistochemistry.

RESULTS

Our experimental model reproduced several aspects of the human NASH pathophysiology. NLRP3 inflammasome activation was induced by the combined effect of HFSCD plus CCl₄ and significantly increased levels of both proinflammatory and profibrogenic cytokines and collagen deposition in the liver; thus, NASH severity was higher in the HFSCD+CCl₄ group than that in the HFSCD group, to which CCl₄ was not administered. Hepatic stellate cells, the most profibrogenic cells, were activated by HFSCD plus CCl₄, as indicated by elevated levels of α-smooth muscle actin. Thus, activation of the NLRP3 inflammasome, triggered by low doses of CCl₄, exacerbates the severity of NASH.

CONCLUSIONS

Our results indicate that NLRP3 inflammasome activation plays a key role and may be an important therapeutic target for NASH treatment.

Emerging Role of NLRP3 Inflammasome and Pyroptosis in Liver Transplantation

The nucleotide-binding domain leucine-rich repeat-receptor, pyrin domain-containing-3 (NLRP3) inflammasome contributes to the inflammatory response by activating caspase-1, which in turn participates in the maturation of interleukin (IL)-1β and IL-18, which are mainly secreted via pyroptosis. Pyroptosis is a lytic type of cell death that is controlled by caspase-1 processing gasdermin D. The amino-terminal fragment of gasdermin D inserts into the plasma membrane, creating stable pores and enabling the release of several proinflammatory factors. The activation of NLRP3 inflammasome and pyroptosis has been involved in the progression of liver fibrosis and its end-stage cirrhosis, which is among the main etiologies for liver transplantation (LT). Moreover, the NLRP3 inflammasome is involved in ischemia-reperfusion injury and early inflammation and rejection after LT. In this review, we summarize the recent literature addressing the role of the NLRP3 inflammasome and pyroptosis in all stages involved in LT and argue the potential targeting of this pathway as a future therapeutic strategy to improve LT outcomes. Likewise, we also discuss the impact of graft quality influenced by donation after circulatory death and the expected role of machine perfusion technology to modify the injury response related to inflammasome activation.

NLRP3 activation in neutrophils induces lethal autoinflammation, liver inflammation, and fibrosis

Sterile inflammation is a central element in liver diseases. The immune response following injurious stimuli involves hepatic infiltration of neutrophils and monocytes. Neutrophils are major effectors of liver inflammation, rapidly recruited to sites of inflammation, and can augment the recruitment of other leukocytes. The NLRP3 inflammasome has been increasingly implicated in severe liver inflammation, fibrosis, and cell death. In this study, the role of NLRP3 activation in neutrophils during liver inflammation and fibrosis was investigated. Mouse models with neutrophil-specific expression of mutant NLRP3 were developed. Mutant mice develop severe liver inflammation and lethal autoinflammation phenocopying mice with a systemic expression of mutant NLRP3. NLRP3 activation in neutrophils leads to a pro-inflammatory cytokine and chemokine profile in the liver, infiltration by neutrophils and macrophages, and an increase in cell death. Furthermore, mutant mice develop liver fibrosis associated with increased expression of pro-fibrogenic genes. Taken together, the present work demonstrates how neutrophils, driven by the NLRP3 inflammasome, coordinate other inflammatory myeloid cells in the liver, and propagate the inflammatory response in the context of inflammation-driven fibrosis.

NOX as a Therapeutic Target in Liver Disease

The nicotinamide adenine dinucleotide phosphate hydrogen oxidase (NADPH oxidase or NOX) plays a critical role in the inflammatory response and fibrosis in several organs such as the lungs, pancreas, kidney, liver, and heart. In the liver, NOXs contribute, through the generation of reactive oxygen species (ROS), to hepatic fibrosis by acting through multiple pathways, including hepatic stellate cell activation, proliferation, survival, and migration of hepatic stellate cells; hepatocyte apoptosis, enhancement of fibrogenic mediators, and mediation of an inflammatory cascade in both Kupffer cells and hepatic stellate cells. ROS are overwhelmingly produced during malignant transformation and hepatic carcinogenesis (HCC), creating an oxidative microenvironment that can cause different and various types of cellular stress, including DNA damage, ER stress, cell death of damaged hepatocytes, and oxidative stress. NOX1, NOX2, and NOX4, members of the NADPH oxidase family, have been linked to the production of ROS in the liver. This review will analyze some diseases related to an increase in oxidative stress and its relationship with the NOX family, as well as discuss some therapies proposed to slow down or control the disease's progression.

Role of Oxidative Stress in Liver Disorders

Oxygen is vital for life as it is required for many different enzymatic reactions involved in intermediate metabolism and xenobiotic biotransformation. Moreover, oxygen consumption in the electron transport chain of mitochondria is used to drive the synthesis of ATP to meet the energetic demands of cells. However, toxic free radicals are generated as byproducts of molecular oxygen consumption. Oxidative stress ensues not only when the production of reactive oxygen species (ROS) exceeds the endogenous antioxidant defense mechanism of cells, but it can also occur as a consequence of an unbalance between antioxidant strategies. Given the important role of hepatocytes in the biotransformation and metabolism of xenobiotics, ROS production represents a critical event in liver physiology, and increasing evidence suggests that oxidative stress contributes to the development of many liver diseases. The present review, which is part of the special issue “Oxidant stress in Liver Diseases”, aims to provide an overview of the sources and targets of ROS in different liver diseases and highlights the pivotal role of oxidative stress in cell death. In addition, current antioxidant therapies as treatment options for such disorders and their limitations for future trial design are discussed.

DFV890: a new oral NLRP3 inhibitor—tested in an early phase 2a randomised clinical trial in patients with COVID-19 pneumonia and impaired respiratory function

Background

Coronavirus-associated acute respiratory distress syndrome (CARDS) has limited effective therapy to date. NLRP3 inflammasome activation induced by SARS-CoV-2 in COVID-19 contributes to cytokine storm.

Methods

This randomised, multinational study enrolled hospitalised patients (18–80 years) with COVID-19-associated pneumonia and impaired respiratory function. Eligible patients were randomised (1:1) via Interactive Response Technology to DFV890 + standard-of-care (SoC) or SoC alone for 14 days. Primary endpoint was APACHE II score at Day 14 or on day-of-discharge (whichever-came-first) with worst-case imputation for death. Other key assessments included clinical status, CRP levels, SARS-CoV-2 detection, other inflammatory markers, in-hospital outcomes, and safety.

Findings

Between May 27, 2020 and December 24, 2020, 143 patients (31 clinical sites, 12 countries) were randomly assigned to DFV890 + SoC (n = 71) or SoC alone (n = 72). Primary endpoint to establish clinical efficacy of DFV890 vs. SoC, based on combined APACHE II score, was not met; LSM (SE), 8·7 (1.06) vs. 8·6 (1.05); p = 0.467. More patients treated with DFV890 vs. SoC showed ≥ 1-level improvement in clinical status (84.3% vs. 73.6% at Day 14), earlier clearance of SARS-CoV-2 (76.4% vs. 57.4% at Day 7), and mechanical ventilation-free survival (85.7% vs. 80.6% through Day 28), and there were fewer fatal events in DFV890 group (8.6% vs. 11.1% through Day 28). DFV890 was well tolerated with no unexpected safety signals.

Interpretation

DFV890 did not meet statistical significance for superiority vs. SoC in primary endpoint of combined APACHE II score at Day 14. However, early SARS-CoV-2 clearance, improved clinical status and in-hospital outcomes, and fewer fatal events occurred with DFV890 vs. SoC, and it may be considered as a protective therapy for CARDS.

Trial registration

ClinicalTrials.gov, NCT04382053.

Supplementary Information

The online version contains supplementary material available at 10.1007/s15010-022-01904-w.

Pharmacological effects of Chinese medicine modulating NLRP3 inflammasomes in fatty liver treatment

Inflammation is a key contributing factor in the pathogenesis of fatty liver diseases (FLD), such as nonalcoholic fatty liver disease (NAFLD) and alcohol-associated liver diseases (ALDs). The NLRP3 inflammasome is widely present in the hepatic parenchymal and non-parenchymal cells, which are assembled and activated by sensing intracellular and extracellular danger signals resulting in the matures of IL-1β/IL-18 and pyroptosis. Moreover, the aberrant activation of the NLRP3 inflammasome is considered the main factor to drives immune outbreaks in relation to hepatic injury, inflammation, steatosis, and fibrosis. Therefore, inhibition of NLRP3 inflammasome may be a promising therapeutic target for FLD. Currently, accumulating evidence has revealed that a number of traditional Chinese medicines (TCM) exert beneficial effects on liver injury via inhibiting the NLRP3 inflammasome activation. Here, we summarized the mechanism of NLRP3 inflammasomes in the progression of FLD, and TCM exerts beneficial effects on FLD via positive modulation of inflammation. We describe that TCM is a promising valuable resource for the prevention and treatment agents against FLD and has the potential to be developed into clinical drugs.

Neutrophil extracellular traps enriched with IL-1β and IL-17A participate in the hepatic inflammatory process of patients with non-alcoholic steatohepatitis

Neutrophil extracellular traps (NETs) are implicated in the pathogenesis of various non-infectious inflammatory and thrombotic diseases. We investigated the presence and possible associations of NETs with various histopathologic parameters in patients with non-alcoholic steatohepatitis (NASH). We retrospectively assessed 20 liver biopsy specimens from patients with non-alcoholic fatty liver disease (NAFLD), including 17 specimens with NASH, and 14 control specimens. NETs were identified with confocal microscopy as extracellular structures with co-localization of neutrophil elastase (NE) and citrullinated histone-3. Interleukin-1β (IL-1β) and IL-17A were assessed with the same methodology. Histologic features of NAFLD were semi-quantitatively evaluated, and correlated with presence of NETs, neutrophil density, and platelet density/aggregates (assessed by immunohistochemistry for NE and CD42b, respectively). NETs were identified in 94.1% (16/17) of the NASH biopsy specimens; they were absent from all other NAFLD and control specimens. The presence of NETs was strongly correlated with steatosis (p = 0.003), ballooning degeneration (p < 0.001), lobular inflammation (p < 0.001), portal inflammation (p < 0.001), NAS score (p = 0.001), stage (p = 0.001), and diagnosis of NASH (p < 0.001). NETs were decorated with IL-1β and IL-17A. Platelet aggregates were much larger in NASH specimens, as compared to controls. In conclusion, NETs are implicated in the pathogenesis of NASH. Their associations with inflammation, ballooning degeneration (a hallmark of NASH), and stage emphasize their role in the disease process. In this setting, NETs provide a vehicle for IL-1β and IL-17A. In addition, platelet aggregation in hepatic sinusoids implies a role for thromboinflammation in NASH, and may explain the low peripheral blood platelet counts reported in patients with NASH.

Caffeine Inhibits NLRP3 Inflammasome Activation by Downregulating TLR4/MAPK/NF-κB Signaling Pathway in an Experimental NASH Model

Caffeine elicits protective effects against liver diseases, such as NASH; however, its mechanism of action involving the pyrin domain-containing-3 (NLRP3) inflammasome signaling pathway remains to be elucidated. This study aimed to evaluate the effect of caffeine on the NLRP3 inflammasome signaling pathway in a rat model of NASH. NASH was induced by feeding rats a high-fat, -sucrose, and -cholesterol diet (HFSCD) for 15 weeks along with a weekly low dose (400 mg/kg, i.p.) of CCl₄. Caffeine was administered at 50 mg/kg p.o. The effects of HFSCD+CCl₄ and caffeine on the liver were evaluated using biochemical, ultrastructural, histological, and molecular biological approaches. The HFSCD+CCl₄-treated rats showed fat accumulation in the liver, elevated levels of inflammatory mediators, NLRP3 inflammasome activation, antioxidant dysregulation, and liver fibrosis. Caffeine reduced necrosis, cholestasis, oxidative stress, and fibrosis. Caffeine exhibited anti-inflammatory effects by attenuating NLRP3 inflammasome activation. Moreover, caffeine prevented increases in toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) protein levels and mitigated the phosphorylation of mitogen-activated protein kinase (MAPK). Importantly, caffeine prevented the activation of hepatic stellate cells. This study is the first to report that caffeine ameliorates NASH by inhibiting NLRP3 inflammasome activation through the suppression of the TLR4/MAPK/NF-κB signaling pathway.

Cell-specific Deletion of NLRP3 Inflammasome Identifies Myeloid Cells as Key Drivers of Liver Inflammation and Fibrosis in Murine Steatohepatitis

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide. The NLRP3 inflammasome, a platform for caspase-1 activation and release of interleukin 1β, is increasingly recognized in the induction of inflammation and liver fibrosis during NAFLD. However, the cell-specific contribution of NLRP3 inflammasome activation in NAFLD remains unknown.

METHODS

To investigate the role of NLRP3 inflammasome activation in hepatocytes, hepatic stellate cells (HSCs) and myeloid cells, a conditional Nlrp3 knock-out mouse was generated and bred to cell-specific Cre mice. Both acute and chronic liver injury models were used: lipopolysaccharide/adenosine-triphosphate to induce in vivo NLRP3 activation, choline-deficient, L-amino acid-defined high-fat diet, and Western-type diet to induce fibrotic nonalcoholic steatohepatitis (NASH). In vitro co-culture studies were performed to dissect the crosstalk between myeloid cells and HSCs.

RESULTS

Myeloid-specific deletion of Nlrp3 blunted the systemic and hepatic increase in interleukin 1β induced by lipopolysaccharide/adenosine-triphosphate injection. In the choline-deficient, L-amino acid-defined high-fat diet model of fibrotic NASH, myeloid-specific Nlrp3 knock-out but not hepatocyte- or HSC-specific knock-out mice showed significant reduction in inflammation independent of steatosis development. Moreover, myeloid-specific Nlrp3 knock-out mice showed ameliorated liver fibrosis and decreased HSC activation. These results were validated in the Western-type diet model. In vitro co-cultured studies with human cell lines demonstrated that HSC can be activated by inflammasome stimulation in monocytes, and this effect was significantly reduced if NLRP3 was downregulated in monocytes.

CONCLUSIONS

The study provides new insights in the cell-specific role of NLRP3 in liver inflammation and fibrosis. NLRP3 inflammasome activation in myeloid cells was identified as crucial for the progression of NAFLD to fibrotic NASH. These results may have implications for the development of cell-specific strategies for modulation of NLRP3 activation for treatment of fibrotic NASH.

NLRP3 Inflammasome and Pyroptosis in Liver Pathophysiology: The Emerging Relevance of Nrf2 Inducers

Inflammasomes, particularly the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3 (NLRP3) inflammasome, apparently serve as crucial regulators of the inflammatory response through the activation of Caspase-1 and induction of pro-inflammatory cytokines and pyroptotic cell death. Pyroptosis is a type of programmed cell death mediated by Caspase-1 cleavage of Gasdermin D and the insertion of its N-terminal fragment into the plasma membrane, where it forms pores, enabling the release of different pro-inflammatory mediators. Pyroptosis is considered not only a pro-inflammatory pathway involved in liver pathophysiology but also an important pro-fibrotic mediator. Diverse molecular mechanisms linking oxidative stress, inflammasome activation, pyroptosis, and the progression of liver pathologies have been documented. Numerous studies have indicated the protective effects of several antioxidants, with the ability to induce nuclear factor erythroid 2-related factor 2 (Nrf2) activity on liver inflammation and fibrosis. In this review, we have summarised recent studies addressing the role of the NLRP3 inflammasome and pyroptosis in the pathogenesis of various hepatic diseases, highlighting the potential application of Nrf2 inducers in the prevention of pyroptosis as liver protective compounds.

Mitochondria and the NLRP3 Inflammasome in Alcoholic and Nonalcoholic Steatohepatitis

Alcoholic (ASH) and nonalcoholic steatohepatitis (NASH) are advanced stages of fatty liver disease and two of the most prevalent forms of chronic liver disease. ASH and NASH are associated with significant risk of further progression to cirrhosis and hepatocellular carcinoma (HCC), the most common type of liver cancer, and a major cause of cancer-related mortality. Despite extensive research and progress in the last decades to elucidate the mechanisms of the development of ASH and NASH, the pathogenesis of both diseases is still poorly understood. Mitochondrial damage and activation of inflammasome complexes have a role in inducing and sustaining liver damage. Mitochondrial dysfunction produces inflammatory factors that activate the inflammasome complexes. NLRP3 inflammasome (nucleotide-binding oligomerization domain-like receptor protein 3) is a multiprotein complex that activates caspase 1 and the release of pro-inflammatory cytokines, including interleukin-1β (IL-1β) and interleukin-18 (IL-18), and contributes to inflammatory pyroptotic cell death. The present review, which is part of the issue "Mitochondria in Liver Pathobiology", provides an overview of the role of mitochondrial dysfunction and NLRP3 activation in ASH and NASH.