NLR Family Pyrin Domain-Containing 3 Inflammasome Activation in Hepatic Stellate Cells Induces Liver Fibrosis in Mice

NLRP3 inflammasome: structure, mechanism, drug-induced organ toxicity, therapeutic strategies, and future perspectives

Drug-induced toxicity is an important issue in clinical medicine, which typically results in organ dysfunction and adverse health consequences. The family of NOD-like receptors (NLRs) includes intracellular proteins involved in recognizing pathogens and triggering innate immune responses, including the activation of the NLRP3 inflammasome. The NLRP3 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3) inflammasome is a critical component for both innate and adaptive immune responses and has been implicated in various drug-induced toxicities, including hepatic, renal, and cardiovascular diseases. The unusual activation of the NLRP3 inflammasome causes the release of pro-inflammatory cytokines, such as IL-1β and IL-18, which can lead to more damage to tissues. Targeting NLRP3 inflammasome is a potential therapeutic endeavour for suppressing drug-induced toxicity. This review provides insights into the mechanism, drug-induced organ toxicity, therapeutic strategies, and prospective therapeutic approaches of the NLRP3 inflammasome and summarizes the developing therapies that target the inflammasome unit. This review has taken up one of the foremost endeavours in understanding and inhibiting the NLRP3 inflammasome as a means of generating safer pharmacological therapies.

Dehydrotrametenolic acid methyl ester, a triterpenoid of Poria cocos, alleviates non-alcoholic steatohepatitis by suppressing NLRP3 inflammasome activation via targeting Caspase-1 in mice

Non-alcoholic steatohepatitis (NASH) has emerged as a prevalent chronic liver disease with a huge unmet clinical need. A few studies have reported the beneficial effects of Poria cocos Wolf (P. cocos) extract on NASH mice, but the active components were still unknown. In this study we investigated the therapeutic effects of dehydrotrametenolic acid methyl ester (ZQS5029-1), a lanosterol-7,9(11)-diene triterpenes in P. cocos, in a high-fat diet plus CCl4 induced murine NASH model and a GAN diet induced ob/ob murine NASH model. The NASH mice were treated with ZQS5029-1 (75 mg·kg-1·d-1, i.g.) for 6 and 8 weeks, respectively. We showed that ZQS5029-1 treatment markedly relieved liver injury, inflammation and fibrosis in both the murine NASH models. We found that ZQS5029-1 treatment significantly suppressed hepatic NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation in both the NASH murine models, and blocked lipopolysaccharides (LPS)+adenosine 5'-triphosphate (ATP)/Nigericin-induced NLRP3 inflammasome activation in bone marrow-derived macrophages (BMDMs) and Kupffer cells in vitro. We demonstrated that ZQS5029-1 directly bound to the H236 residue of mouse Caspase-1, thereby inhibiting NLRP3 inflammasome activation. The effects of ZQS5029-1 on macrophage-hepatocyte/HSC crosstalk were analyzed using the supernatants from macrophages preconditioned with LPS + ATP introduced into hepatocytes and hepatic stellate cells (HSCs). We found that the conditioned medium from the BMDMs induced injury and death, as well as lipid accumulation in hepatocytes, and activation of HSCs; these effects were blocked by conditioned medium from BMDMs treated with ZQS5029-1. Moreover, the protective effects of ZQS5029-1 on hepatocytes and HSCs were eliminated by H236A-mutation of Caspase-1. We conclude that ZQS5029-1 is a promising lead compound for the treatment of NASH by inhibiting NLRP3 inflammasome activation through targeting Caspase-1 and regulating the macrophage-hepatocyte/HSC crosstalk.

Treatment of IL-18-binding protein biologics suppresses fibrotic progression in metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH) is a chronic liver disease characterized by inflammation and fibrosis, with enhanced interleukin-18 (IL-18) signaling. IL-18-binding protein (IL-18BP) neutralizes IL-18, but its therapeutic potential in MASH is unclear. We find elevated IL-18BP and IL-18 levels in patients with MASH and mice, with free IL-18 correlating with disease severity. IL-18 stimulates interferon-gamma (IFNγ) production in CD4 T cells, increasing hepatic IL-18BP. IL-18BP-deficient mice show worsened liver inflammation and fibrosis. We develop a human IL-18BP biologics (APB-R3) and inject it to mice to evaluate its pharmacologic efficacy. APB-R3 significantly improves MASH in reducing fibrosis and inflammation and inhibits hepatic stellate cell activation via the cGMP pathway. This study proposes that abrogation of IL-18 signaling by boosting IL-18BP can strongly inhibit the development of MASH-induced fibrosis, and our engineered IL-18BP biologics can become a promising therapeutic candidate for curing MASH.

Neutrophil extracellular traps mediate pathophysiology of hepatic cells during liver injury

Neutrophil extracellular traps (NETs) are web-like, bactericidal structures produced by neutrophils and are composed principally of extracellular DNA, histones, elastase, and myeloperoxidase, among other components. NET formation is an innate immune response that is beneficial for pathogen killing and clearance. However, excessive NET formation and clearance defects can lead to inflammation and induce damage to host organs. NETs are also implicated in the development of noninfectious inflammatory disorders, such as liver injury in chronic liver diseases. The liver parenchyma contains hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, and hepatic stellate cells. Each of these cells possesses unique structures and functions, and their interactions with NETs result in pathophysiological changes contributing to liver injury. This review updates the findings related to the modes of action and molecular mechanisms by which NETs modulate the pathophysiology of various hepatic cells and potentiate liver injury. The article also reviews the roles of NETs in hepatic ischemia reperfusion injury, hepatocellular carcinoma pathogenesis, and cancer metastasis. Last, we examine data to determine whether NETs induce crosstalk among various hepatic cells during liver injury and to identify future research directions.

Mechanistic Studies on the Role of IL-17/NLRP3 in Arsenic-Induced Activation of Hepatic Stellate Cells Through Hepatocyte Proptosis

Long-term exposure to arsenic, a prevalent environmental contaminant, has been implicated in the pathogenesis of various hepatic conditions. Hepatic stellate cells (HSCs) are central to the development of liver fibrosis. Recently, the involvement of interleukin-17 (IL-17) and the NOD-like receptor protein 3 (NLRP3) inflammasome in hepatic pathologies has attracted significant research interest. Hepatocyte pyroptosis, a form of programmed cell death, is a critical factor in the occurrence of inflammation. The objective of this study was to investigate the specific roles of IL-17 and NLRP3 in the arsenic-induced activation of HSCs through hepatocyte pyroptosis. We pretreated MIHA cells with MCC950 (1 and 5 μM) and secukinumab (10 and 100 nM) for 4 h, then with NaAsO2 (25 μM) for 24 h at 37 °C under 5% CO2. After incubation, the cell-culture supernatant was collected and mixed with serum-free high-glucose DMEM medium in a 1:1 ratio to prepare the conditioned medium, which was subsequently used for the culture of LX-2 cells. The results showed that exposure to NaAsO2 induced hepatocellular pyroptosis, which led to the release of the inflammatory cytokines IL-18 and IL-1β and subsequent activation of HSCs. Treatment with the inhibitors MCC950 and secukinumab significantly reduced the secretion of Extracellular matrix (ECM) components and attenuated HSC activation. These results demonstrate that blocking the IL-17 and NLRP3 signaling pathways significantly reduces HSC activation and attenuates hepatic fibrogenesis. These results provide novel molecular targets for the prevention and treatment of arsenic-related liver fibrosis.

Exploring the Axis of Gut Microbiota-Inflammatory Cytokine-Atrial Fibrillation in the Pathogenesis of Atrial Fibrillation

A relationship may exist between the gut microbiota, inflammatory factors and atrial fibrillation (AF); however, the precise biological mechanisms linking these components remain uncertain.In this study, 211 single-nucleotide polymorphisms associated with the gut microbiota were collected from the MiBioGen consortium. Summary data for AF were sourced from large-scale genome-wide association studies. Two-step Mendelian randomization (MR) was applied to estimate the possible mediating effect of inflammatory cytokines on the causality between the gut microbiota and AF. MR confirmed the effects of class Lentisphaeria, family Bifidobacteriaceae, family XIII, genus Anaerostipes, genus Howardella, genus Intestinibacter, genus Lachnospiraceae (NK4A136 group), genus Odoribacter, genus Ruminococcus gnavus, order Bifidobacteriales, order Victivallales and phylum Lentisphaerae on AF prevention. Moreover, MR revealed the role of Fms-related tyrosine kinase 3 ligand, interleukin-6, interleukin-7, leukaemia inhibitory factor receptor, sulfotransferase 1A1 and tumour necrosis factor ligand superfamily member 12 in protecting against AF. Fibroblast growth factor 5, interleukin-2 receptor subunit β, and tumour necrosis factor had a causal effect, increasing AF risk. The mediation exploration indicated that the indirect effect of genus Rikenellaceae (RC9 gut group) (id.11191) on AF mediated by interleukin-6 was OR 1.011 (95% confidence interval 1.002–1.024; mediation proportion=23.913%). This study supplies genetic insights into the potential causal association between the gut microbiota and AF. These causal associations and mediating effects are useful for managing AF through manipulation of the gut microbiota.

Chronic arsenic exposure-provoked biotoxicity involved in liver-microbiota-gut axis disruption in chickens based on multi-omics technologies

INTRODUCTION

Arsenic has been ranked as the most hazardous substance by the U.S. Agency for Toxic Substances and Disease Registry. Environmental arsenic exposure-evoked health risks have become a vital public health concern worldwide owing to the widespread existence of arsenic. Multi-omics is a revolutionary technique to data analysis providing an integrated view of bioinformation for comprehensively and systematically understanding the elaborate mechanism of diseases.

OBJECTIVES

This study aimed at uncovering the potential contribution of liver-microbiota-gut axis in chronic inorganic arsenic exposure-triggered biotoxicity in chickens based on multi-omics technologies.

METHODS

Forty Hy-Line W-80 laying hens were chronically exposed to sodium arsenite with a dose-dependent manner (administered with drinking water containing 10, 20, or 30 mg/L arsenic, respectively) for 42 d, followed by transcriptomics, serum non-targeted metabolome, and 16S ribosomal RNA gene sequencing accordingly.

RESULTS

Arsenic intervention induced a serious of chicken liver dysfunction, especially severe liver fibrosis, simultaneously altered ileal microbiota populations, impaired chicken intestinal barrier, further drove enterogenous lipopolysaccharides translocation via portal vein circulation aggravating liver damage. Furtherly, the injured liver disturbed bile acids (BAs) homoeostasis through strongly up-regulating the BAs synthesis key rate-limiting enzyme CYP7A1, inducing excessive serum total BAs accumulation, accompanied by the massive synthesis of primary BA-chenodeoxycholic acid. Moreover, the concentrations of secondary BAs-ursodeoxycholic acid and lithocholic acid were markedly repressed, which might involve in the repressed dehydroxylation of Ruminococcaceae and Lachnospiraceae families. Abnormal BAs metabolism in turn promoted intestinal injury, ultimately perpetuating pernicious circle in chickens. Notably, obvious depletion in the abundance of four profitable microbiota, Christensenellaceae, Ruminococcaceae, Muribaculaceae, and Faecalibacterium, were correlated tightly with this hepato-intestinal circulation process in chickens exposed to arsenic.

CONCLUSION

Our study demonstrates that chronic inorganic arsenic exposure evokes liver-microbiota-gut axis disruption in chickens and establishes a scientific basis for evaluating health risk induced by environmental pollutant arsenic.

The role of inflammasomes in hepatocellular carcinoma: Mechanisms and therapeutic insights

Hepatocellular carcinoma is among the most frequent forms of primary liver cancer and develops within a context of chronic inflammation, frequently associated with a multitude of risk factors, including viral infections, metabolic dysfunction-associated fatty liver disease, metabolic dysfunction-associated steatohepatitis and liver fibrosis. The tumor microenvironment is crucial for the progression of HCC, as immune cells, tumor-associated fibroblasts and hepatic stellate cells interact to promote chronic inflammation and tumor spread. Inflammasomes, the multiprotein complexes that launch the innate immune response, emerge as important mediators in the pathogenesis of HCC. Among others, the inflammasome Nucleotide-binding oligomerization domain, Leucine rich Repeat (NLR) and Pyrin (NLRP) 3 (NLRP3), and absent in melanoma 2 (AIM2), exhibit a dual role in HCC background. It has been reported that they can exert oncosuppressive functions by triggering the inflammatory death of cancer cells. Vice versa, chronic activation contributes to the development of a pro-tumorigenic environment, thus supporting tumor growth. In addition, other inflammasomes such as Nucleotide-binding oligomerization domain, Leucine rich Repeat (NLR) and Pyrin (NLRP) 6 and 12 (NLRP6 and NLRP12, respectively) regulate HCC onset and progression, although more experimental evidence is required. This review focuses on the molecular mechanisms underpinning the inflammasome's contribution to the onset, progression and spread of HCC. Moreover, we will explore the potential therapeutic approaches currently under investigation, which aim to improve the efficacy and reduce the side effects of the treatments currently available. Targeting inflammasomes may be a promising therapeutic strategy for the treatment of HCC, offering new opportunities to improve patient prognosis.

Co-exposure to different bacterial species' lipopolysaccharides with the NASH diet exacerbates NASH and liver fibrosis progression in mice

BACKGROUND AND AIM

With the obesity epidemic, nonalcoholic fatty liver disease (NAFLD) has become a public health concern, but its progression mechanism remains unclear. Experimental models mimicking human NAFLD/steatohepatitis (NASH) are crucial. This study simulates gut microbiota imbalance effects on NASH and liver fibrosis.

METHODS

We used different bacterial sources of lipopolysaccharide (LPS), including Escherichia coli (GEC) and Salmonella abortus equi (GSE), combined with a Gubra Amylin NASH (GAN) diet to induce NASH and liver fibrosis.

RESULTS

The GSE group showed significantly higher serum alanine aminotransferase, hydroxyproline, CD68-positive cells, α-smooth muscle actin, glial fibrillary acidic protein, and TNF-α, COL1A1, TGF-β, and NLRP3 expressions compared to the the GAN group. The GSE group also had higher Erysipelotrichaceae, Akkermansiaceae, and Bacteroidaceae family numbers.

CONCLUSIONS

The GAN diet with LPS treatment successfully induced NASH and fibrosis making this model useful for preclinical NASH drug testing.

Neutrophil extracellular traps activate hepatic stellate cells and monocytes via NLRP3 sensing in alcohol-induced acceleration of MASH fibrosis

OBJECTIVE

Alcohol use in metabolic dysfunction-associated steatohepatitis (MASH) is associated with an increased risk of fibrosis and liver-related death. Here, we aimed to identify a mechanism through which repeated alcohol binges exacerbate liver injury in a high fat-cholesterol-sugar diet (MASH diet)-induced model of MASH.

DESIGN

C57BL/6 mice received either chow or the MASH diet for 3 months with or without weekly alcohol binges. Neutrophil infiltration, neutrophil extracellular traps (NETs) and fibrosis were evaluated.

RESULTS

We found that alcohol binges in MASH increase liver injury and fibrosis. Liver transcriptomic profiling revealed differential expression of genes involved in extracellular matrix reorganisation, neutrophil activation and inflammation compared with alcohol or the MASH diet alone. Alcohol binges specifically increased NET formation in MASH livers in mice, and NETs were also increased in human livers with MASH plus alcohol use. We discovered that cell-free NETs are sensed via Nod-like receptor protein 3 (NLRP3). Furthermore, we show that cell-free NETs in vitro induce a profibrotic phenotype in hepatic stellate cells (HSCs) and proinflammatory monocytes. In vivo, neutrophil depletion using anti-Ly6G antibody or NET disruption with deoxyribonuclease treatment abrogated monocyte and HSC activation and ameliorated liver damage and fibrosis. In vivo, inhibition of NLRP3 using MCC950 or NLRP3 deficiency attenuated NET formation, liver injury and fibrosis in MASH plus alcohol diet-fed mice (graphical abstract).

CONCLUSION

Alcohol binges promote liver fibrosis via NET-induced activation of HSCs and monocytes in MASH. Our study highlights the potential of inhibition of NETs and/or NLRP3, as novel therapeutic strategies to combat the profibrotic effects of alcohol in MASH.

Pyroptosis is involved in maternal nicotine exposure-induced metabolic associated fatty liver disease progression in offspring mice

We have investigated whether inflammasomes and pyroptosis are activated in maternal nicotine exposure (MNE) offspring mice and whether they are involved in MNE-promoted metabolic associated fatty liver disease (MAFLD) in adult offspring. We injected pregnant mice subcutaneously with saline vehicle or nicotine twice a day on gestational days 11-21. Offspring mice from both groups were fed with a normal diet (ND) or a high-fat diet (HFD) for 6 months at postnatal day 21 to develop the MAFLD model. Serum biochemical indices were analyzed, and liver histology was performed. The expression levels of inflammasome and pyroptosis proteins were detected by western blot. We found MNE significantly aggravated the injury of MAFLD in adult offspring mice. MNE activated inflammasomes and pyroptosis in both infant and adult offspring mice. HFD treatment activated inflammasomes but not pyroptosis at 3 months, while it showed no effect at 6 months. However, pyroptosis was more severe in MNE-HFD mice than in MNE-ND mice at 6 months. Taken together, our data suggest MNE promotes MAFLD progression in adult offspring mice. MNE also induces NLRP3 and NLRP6 inflammasome activation and pyroptosis in both infant and adult offspring mice, which may be involved in MNE-promoted progression of MAFLD.

Mitochondrial GRIM19 Loss Induces Liver Fibrosis through NLRP3/IL33 Activation via Reactive Oxygen Species/NF-кB Signaling

Background and Aims

Hepatic fibrosis (HF) is a critical step in the progression of hepatocellular carcinoma (HCC). Gene associated with retinoid-IFN-induced mortality 19 (GRIM19), an essential component of mitochondrial respiratory chain complex I, is frequently attenuated in various human cancers, including HCC. Here, we aimed to investigate the potential relationship and underlying mechanism between GRIM19 loss and HF pathogenesis.

Methods

GRIM19 expression was evaluated in normal liver tissues, hepatitis, hepatic cirrhosis, and HCC using human liver disease spectrum tissue microarrays. We studied hepatocyte-specific GRIM19 knockout mice and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 (Cas9) lentivirus-mediated GRIM19 gene-editing in murine hepatocyte AML12 cells in vitro and in vivo. We performed flow cytometry, immunofluorescence, immunohistochemistry, western blotting, and pharmacological intervention to uncover the potential mechanisms underlying GRIM19 loss-induced HF.

Results

Mitochondrial GRIM19 was progressively downregulated in chronic liver disease tissues, including hepatitis, cirrhosis, and HCC tissues. Hepatocyte-specific GRIM19 heterozygous deletion induced spontaneous hepatitis and subsequent liver fibrogenesis in mice. In addition, GRIM19 loss caused chronic liver injury through reactive oxygen species (ROS)-mediated oxidative stress, resulting in aberrant NF-кB activation via an IKK/IкB partner in hepatocytes. Furthermore, GRIM19 loss activated NLRP3-mediated IL33 signaling via the ROS/NF-кB pathway in hepatocytes. Intraperitoneal administration of the NLRP3 inhibitor MCC950 dramatically alleviated GRIM19 loss-driven HF in vivo.

Conclusions

The mitochondrial GRIM19 loss facilitates liver fibrosis through NLRP3/IL33 activation via ROS/NF-кB signaling, providing potential therapeutic approaches for earlier HF prevention.

Oxymatrine alleviates high-fat diet/streptozotocin-induced non-alcoholic fatty liver disease in C57BL/6 J mice by modulating oxidative stress, inflammation and fibrosis

Non-alcoholic fatty liver disease (NAFLD) represents a complex complication of type 2 diabetes mellitus (T2DM). Oxymatrine (OMT) is an alkaloid extracted from Sophora flavescens with broad pharmacological effects. However, there is currently a lack of research on OMT in the field of NAFLD. The present study aimed to explore the effects and underlying mechanisms of oxymatrine in treating T2DM with NAFLD. The T2DM mice model was induced by high-fat diet (HFD) combined with streptozotocin (STZ) injection in male C57BL/6 J mice. Animals were randomly divided into four groups (n = 8): Control group, DC group, OMT-L group (45 mg/kg i.g.), and OMT-H group (90 mg/kg, i.g.). The drug was administered once a day for 8 weeks. In addition, HepG2 hepatocytes were incubated with palmitic acid (PA) to establish a fatty liver cell model. Treated with OMT, the body weight and fasting blood glucose (FBG) of DC mice were reduced and the liver organ coefficient was significantly optimized. Meanwhile, OMT markedly enhanced the activities of key antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), and also reduced malondialdehyde (MDA) levels. These biochemical alterations were accompanied by noticeable improvements in liver histopathology. Furthermore, OMT down-regulated the expression of NOD-like receptor protein 3 (NLRP3), interleukin-1β (IL-1β), transforming growth factor-β1 (TGF-β1) and collagen I significantly, highlighting its potential in modulating inflammatory and fibrotic pathways. In conclusion, OMT improved liver impairment effectively in diabetic mice by suppressing oxidative stress, inflammation and fibrosis. These results suggest that OMT may represent a novel therapy for NAFLD with diabetes.

Innate Immunity and MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) has emerged as the most common liver disease worldwide in recent years. MASLD commonly presents as simple hepatic steatosis, but ~25% of patients develop liver inflammation, progressive fibrosis, liver cirrhosis and related hepatocellular carcinoma. Liver inflammation and the degree of fibrosis are key determinants of the prognosis. The pathophysiology of liver inflammation is incompletely understood and involves diverse factors and specifically innate and adaptive immune responses. More specifically, diverse mediators of innate immunity such as proinflammatory cytokines, adipokines, inflammasomes and various cell types like mononuclear cells, macrophages and natural killer cells are involved in directing the inflammatory process in MASLD. The activation of innate immunity is driven by various factors including excess lipids and lipotoxicity, insulin resistance and molecular patterns derived from gut commensals. Targeting pathways of innate immunity might therefore appear as an attractive therapeutic strategy in the future management of MASLD and possibly its complications.

NcRNA Regulated Pyroptosis in Liver Diseases and Traditional Chinese Medicine Intervention: A Narrative Review

Pyroptosis is a novel pro-inflammatory mode of programmed cell death that differs from ferroptosis, necrosis, and apoptosis in terms of its onset and regulatory mechanisms. Pyroptosis is dependent on cysteine aspartate protein hydrolase (caspase)-mediated activation of GSDMD, NLRP3, and the release of pro-inflammatory cytokines, interleukin-1 (IL-1β), and interleukin-18 (IL-18), ultimately leading to cell death. Non-coding RNA (ncRNA) is a type of RNA that does not encode proteins in gene transcription but plays an important regulatory role in other post-transcriptional links. NcRNA mediates pyroptosis by regulating various related pyroptosis factors, which we termed the pyroptosis signaling pathway. Previous researches have manifested that pyroptosis is closely related to the development of liver diseases, and is essential for liver injury, alcoholic fatty liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), liver fibrosis, and liver cancer. In this review, we attempt to address the role of the ncRNA-mediated pyroptosis pathway in the above liver diseases and their pathogenesis in recent years, and briefly outline that TCM (Traditional Chinese Medicine) intervene in liver diseases by modulating ncRNA-mediated pyroptosis, which will provide a strategy to find new therapeutic targets for the prevention and treatment of liver diseases in the future.

Exploring the role of genetic variations in NAFLD: implications for disease pathogenesis and precision medicine approaches

Non-alcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver diseases, affecting more than one-quarter of people worldwide. Hepatic steatosis can progress to more severe forms of NAFLD, including NASH and cirrhosis. It also may develop secondary diseases such as diabetes and cardiovascular disease. Genetic and environmental factors regulate NAFLD incidence and progression, making it a complex disease. The contribution of various environmental risk factors, such as type 2 diabetes, obesity, hyperlipidemia, diet, and sedentary lifestyle, to the exacerbation of liver injury is highly understood. Nevertheless, the underlying mechanisms of genetic variations in the NAFLD occurrence or its deterioration still need to be clarified. Hence, understanding the genetic susceptibility to NAFLD is essential for controlling the course of the disease. The current review discusses genetics' role in the pathological pathways of NAFLD, including lipid and glucose metabolism, insulin resistance, cellular stresses, and immune responses. Additionally, it explains the role of the genetic components in the induction and progression of NAFLD in lean individuals. Finally, it highlights the utility of genetic knowledge in precision medicine for the early diagnosis and treatment of NAFLD patients.

Network pharmacology and transcriptomic profiling elucidate the therapeutic effects of Ranunculus ternatus Thunb on liver fibrosis via MK3-NF-κB inhibition

Activation of hepatic stellate cells (HSCs) is critical in the progression of liver fibrosis and is a promising target for anti-hepatic fibrosis drug development. Moreover, effective pharmacological interventions targeting this pathomechanism are scarce. Our study confirms the therapeutic value of β-sitosterol, a major constituent of Ranunculus ternatus Thunb, in hepatic fibrosis and identifies its underlying mechanisms. After treatment with β-sitosterol, CCL4-induced hepatic fibrosis was reversed in mice, while inflammatory and hepatic fibrosis indices were improved. Meanwhile, we explored the molecular mechanism of β-sitosterol treatment for hepatic fibrosis and, based on RNA-seq results, found that the ameliorative effect of β-sitosterol on hepatic fibrosis was associated with the MK3 and NF-κB signalling pathways. MK3, an important kinase in the MAPK pathway, plays a role in transmitting upstream and downstream signals, whereas the NF-κB signalling pathway has been shown to be associated with HSC activation. We verified the interaction between MK3 and IκB in HSC cells using endogenous Co-IP, whereas β-sitosterol reduced the binding of MK3 to IκB and the activation of the NF-κB signalling pathway. Our findings reveal the mechanism of β-sitosterol in the treatment of liver fibrosis, suggesting that β-sitosterol may be a promising drug for the treatment of liver fibrosis and deserves further investigation.

The discovery of NLRP3 and its function in cryopyrin-associated periodic syndromes and innate immunity

From studies of individual families to global collaborative efforts, the NLRP3 inflammasome is now recognized to be a key regulator of innate immunity. Activated by a panoply of pathogen-associated and endogenous triggers, NLRP3 serves as an intracellular sensor that drives carefully coordinated assembly of the inflammasome, and downstream inflammation mediated by IL-1 and IL-18. Initially discovered as the cause of the autoinflammatory spectrum of cryopyrin-associated periodic syndrome (CAPS), NLRP3 is now also known to play a role in more common diseases including cardiovascular disease, gout, and liver disease. We have seen cohesion in results from clinical studies in CAPS patients, ex vivo studies of human cells and murine cells, and in vivo murine models leading to our understanding of the downstream pathways, cytokine secretion, and cell death pathways that has solidified the role of autoinflammation in the pathogenesis of human disease. Recent advances in our understanding of the structure of the inflammasome have provided ways for us to visualize normal and mutant protein function and pharmacologic inhibition. The subsequent development of targeted therapies successfully used in the treatment of patients with CAPS completes the bench to bedside translational loop which has defined the study of this unique protein.

NLRP3 inflammasome activation promotes liver inflammation and fibrosis in experimental biliary atresia

BACKGROUND

Biliary atresia (BA) is characterized by a progressive fibroinflammatory cholangiopathy in early infants with unknown etiology. Although innate immune disorder is involved in its mechanism, role of NLRP3 inflammasome in BA remains largely undefined.

AIM

To explore the role of NLRP3 inflammasome in BA.

METHODS

The expressions of NLRP3 inflammasome-related genes were determined in BA patients. Role of NLRP3 inflammasome was evaluated using MCC950 in experimental BA. Furthermore, gadolinium chloride, a macrophage scavenger, was applied to validate the inflammasome's cellular localization. Finally, the effects of NLRP3 inflammasome activation on liver fibrosis were explored in vivo and vitro in experimental BA.

RESULTS

The components of NLRP3 inflammasome were up-regulated in BA patients. Inflammasome-related genes showed positively correlated with liver inflammation and fibrosis in BA patients. In experimental BA, inflammasome-related genes were up-regulated, and their expressions were inhibited by MCC950, which promoted mice growth, protected liver function, alleviated obstructive jaundice, inhibited liver inflammation, and reduced serum IL-1β level. NLRP3 inflammasome was expressed in macrophages, and macrophage elimination exerted the same protective roles as MCC950 did in BA. Additionally, NLRP3 inflammasome activation promoted liver fibrosis in experimental BA.

CONCLUSIONS

NLRP3 inflammasome activation in macrophages promoted liver inflammation and fibrosis in experimental BA.

Progress in the Correlation Between Inflammasome NLRP3 and Liver Fibrosis

Liver fibrosis is a reversible condition that occurs in the early stages of chronic liver disease. To develop effective treatments for liver fibrosis, understanding the underlying mechanism is crucial. The NOD-like receptor protein 3 (NLRP3) inflammasome, which is a part of the innate immune system, plays a crucial role in the progression of various inflammatory diseases. NLRP3 activation is also important in the development of various liver diseases, including viral hepatitis, alcoholic or nonalcoholic liver disease, and autoimmune liver disease. This review discusses the role of NLRP3 and its associated molecules in the development of liver fibrosis. It also highlights the signal pathways involved in NLRP3 activation, their downstream effects on liver disease progression, and potential therapeutic targets in liver fibrosis. Further research is encouraged to develop effective treatments for liver fibrosis.

[Adeno-associated virus-mediated hepatocyte-specific NDUFA13 overexpression protects against CCl4-induced liver fibrosis in mice by inhibiting hepatic NLRP3 activation]

OBJECTIVE

To investigate the protective effect of NDUFA13 protein against acute liver injury and liver fibrosis in mice and explore the possible mechanisms.

METHODS

BALB/C mice (7 to 8 weeks old) were divided into normal group, CCl4 group, CCl4+AAV-NC group and CCl4+AAV-NDU13 group (n=18). Mouse models of liver fibrosis were established by intraperitoneal injection of CCl4 twice a week for 3, 5 or 7 weeks, and the recombinant virus AAV8-TBG-NC or AAV8-TBG-NDUFA13 was injected via the tail vein 7-10 days prior to CCl4 injection. After the treatments, pathological changes in the liver of the mice were observed using HE and Masson staining. Hepatic expression levels of NDUFA13 and α-SMA were detected with Western blotting, and the coexpression of NDUFA13 and NLRP3, TNF-α and IL-1β, and α-SMA and collagen Ⅲ was analyzed with immunofluorescence assay.

RESULTS

HE and Masson staining showed deranged liver architecture, necrotic hepatocytes and obvious inflammatory infiltration and collagen fiber deposition in mice with CCl4 injection (P < 0.001). NDUFA13 expression markedly decreased in CCl4-treated mice (P < 0.001), while a significant reduction in inflammatory aggregation and fibrosis was observed in mice with AAV-mediated NDUFA13 overexpression (P < 0.001). In CCl4+AAV-NDU13 group, immunofluorescence assay revealed markedly weakened activation of NLRP3 inflammasomes (P < 0.001), significantly decreased TNF-α and IL-1β secretion (P < 0.001), and inhibited hepatic stellate cell activation (P < 0.05) and collagen formation in the liver (P < 0.001).

CONCLUSION

Mitochondrial NDUFA13 overexpression in hepatocytes protects against CCl4- induced liver fibrosis in mice by inhibiting activation of NLRP3 signaling.

The anti-liver fibrosis effect of Tibetan medicine (Qiwei Tiexie capsule) is related to the inhibition of NLRP3 inflammasome activation in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Qiwei Tiexie capsule (QWTX) is an improved form of a classical prescription of Tibetan medicine-Qiwei Tiexie pill. It has been employed in the treatment of a variety of chronic liver disorders, including liver fibrosis. Uncertainty still exists regarding the mechanism of QWTX action in liver fibrosis.

AIM OF THE STUDY

Confirm the anti-liver fibrosis effect of QWTX and reveal its mechanism from the perspective of NOD-like receptor protein 3 (NLRP3) inflammasome activation.

MATERIALS AND METHODS

In vivo experiment: A rat model of carbon tetrachloride -induced liver fibrosis was constructed. All rats were randomly divided into six groups: a control group, a model group, a group receiving the positive drug (Biejia Ruangan tablet), and three groups receiving QWTX at high, medium, and low doses. The contents of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin (TBil) were detected in serum. Hematoxylin and eosin staining and Masson's staining were used to assess the histomorphological alteration of the liver. The levels of glutathione peroxidase, hydroxyproline, tumor necrosis factor alpha (TNF-α), and interleukin 1 beta (IL-1β) in the liver were determined using the corresponding detection kits. Real-time polymerase chain reaction, immunofluorescence, and western blotting were used to determine the expression levels of NLRP3, adaptor protein (ASC), caspase-1, and alpha-smooth muscle actin (α-SMA). In vitro experiment: Four groups of rat hepatic stellate cell line (HSC-T6) cells were created: the control group, the low-dose QWTX group (0.05 mg/mL), the medium-dose QWTX group (0.1 mg/mL), and the high-dose QWTX group (0.2 mg/mL). Cell viability was assessed using a cell counting kit, and the amounts of collagen type I (Col I) and IL-1β in the cell lysate were measured using an enzyme-linked immunosorbent assay kit. The mRNA and protein expression of NLRP3, ASC, caspase-1, and α-SMA were also estimated.

RESULTS

QWTX had an inhibitory effect on liver fibrosis and a negative effect on HSC activation, while it improved liver histopathological injury and abnormal liver function and increased hydroxyproline content and glutathione peroxidase activity in vivo. QWTX decreased the expression of α-SMA, NLRP3, caspase-1, ASC, and IL-1β both in vitro and in vivo.

CONCLUSIONS

Tibetan medicine QWTX had a significant anti-liver fibrosis effect that was related to the inhibition of NLRP3 inflammasome activation in vivo and in vitro.

Auranofin attenuates Schistosoma mansoni egg-induced liver granuloma and fibrosis in mice

Schistosomiasis is a serious tropical disease. Despite extensive research into the etiology of liver fibrosis, effective therapeutic options remain limited. This study aims to assess the effectiveness of auranofin in treating hepatic granuloma and fibrogenesis produced by Schistosoma (S.) mansoni eggs. Auranofin is a gold complex that contains thioglucose tetraacetate and triethylphosphine. Eighty BALB/c male mice were divided into four groups (n=20/group): negative control (GI), positive control (GII), and early (GIII) and late (GIV) treatment groups with oral auranofin according to beginning of treatment 4th week and 6th week post-infection. Mice were infected subcutaneously in a dose of 60±10 cercariae/mouse. Worm counts, egg loads, and oogram patterns were determined. Biochemical, histological, and immunostaining of interleukin-1β (IL-1β), Sirtuin 3 (SIRT3), and smooth muscle actin (SMA) were assessed. GIII showed a significant decrease in the total S. mansoni worm burden and ova/gram in liver tissue (with reduction percent of 63.07% and 78.26%, respectively). Schistosomal oogram patterns, immature and mature ova, also showed a significant decrease. The reduction in granuloma number and size was 40.63% and 48.66%, respectively, in GIII, whereas in GIV, the reduction percent was 76.63% and 67.08%. In addition, the degree of fibrosis was significantly diminished in both treated groups. GIV showed significant reduction in IL-1β and SMA expression and increase in SIRT3 expression. These findings reveal how auranofin suppresses the development of liver fibrosis. Therefore, it is crucial to take another look at auranofin as a prospective medication for the treatment of S. mansoni egg-induced hepatic granuloma and consequent fibrosis.

The correlation between gut microbiome and atrial fibrillation: pathophysiology and therapeutic perspectives

Regulation of gut microbiota and its impact on human health is the theme of intensive research. The incidence and prevalence of atrial fibrillation (AF) are continuously escalating as the global population ages and chronic disease survival rates increase; however, the mechanisms are not entirely clarified. It is gaining awareness that alterations in the assembly, structure, and dynamics of gut microbiota are intimately engaged in the AF progression. Owing to advancements in next-generation sequencing technologies and computational strategies, researchers can explore novel linkages with the genomes, transcriptomes, proteomes, and metabolomes through parallel meta-omics approaches, rendering a panoramic view of the culture-independent microbial investigation. In this review, we summarized the evidence for a bidirectional correlation between AF and the gut microbiome. Furthermore, we proposed the concept of "gut-immune-heart" axis and addressed the direct and indirect causal roots between the gut microbiome and AF. The intricate relationship was unveiled to generate innovative microbiota-based preventive and therapeutic interventions, which shed light on a definite direction for future experiments.

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.

Hepatic SPARC Expression Is Associated with Inflammasome Activation during the Progression of Non-Alcoholic Fatty Liver Disease in Both Mice and Morbidly Obese Patients

The severity of non-alcoholic fatty liver disease (NAFLD) ranges from simple steatosis to steatohepatitis, and it is not yet clearly understood which patients will progress to liver fibrosis or cirrhosis. SPARC (Secreted Protein Acidic and Rich in Cysteine) has been involved in NAFLD pathogenesis in mice and humans. The aim of this study was to investigate the role of SPARC in inflammasome activation, and to evaluate the relationship between the hepatic expression of inflammasome genes and the biochemical and histological characteristics of NAFLD in obese patients. In vitro studies were conducted in a macrophage cell line and primary hepatocyte cultures to assess the effect of SPARC on inflammasome. A NAFLD model was established in SPARC knockout (SPARC-/-) and SPARC+/+ mice to explore inflammasome activation. A hepatic RNAseq database from NAFLD patients was analyzed to identify genes associated with SPARC expression. The results were validated in a prospective cohort of 59 morbidly obese patients with NAFLD undergoing bariatric surgery. Our results reveal that SPARC alone or in combination with saturated fatty acids promoted IL-1β expression in cell cultures. SPARC-/- mice had reduced hepatic inflammasome activation during the progression of NAFLD. NAFLD patients showed increased expression of SPARC, NLRP3, CASP1, and IL-1β. Gene ontology analysis revealed that genes positively correlated with SPARC are linked to inflammasome-related pathways during the progression of the disease, enabling the differentiation of patients between steatosis and steatohepatitis. In conclusion, SPARC may play a role in hepatic inflammasome activation in NAFLD.

Role of inflammasomes and cytokines in immune dysfunction of liver cirrhosis

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

Cellular stress in the pathogenesis of nonalcoholic steatohepatitis and liver fibrosis

The burden of chronic liver disease is rising substantially worldwide. Fibrosis, characterized by excessive deposition of extracellular matrix proteins, is the common pathway leading to cirrhosis, and limited treatment options are available. There is increasing evidence suggesting the role of cellular stress responses contributing to fibrogenesis. This Review provides an overview of studies that analyse the role of cellular stress in different cell types involved in fibrogenesis, including hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells and macrophages.

Pyroptosis and gasdermins-Emerging insights and therapeutic opportunities in metabolic dysfunction-associated steatohepatitis

In recent years, there has been a rapid expansion in our understanding of regulated cell death, leading to the discovery of novel mechanisms that govern diverse cell death pathways. One recently discovered type of cell death is pyroptosis, initially identified in the 1990s as a caspase-1-dependent lytic cell death. However, further investigations have redefined pyroptosis as a regulated cell death that relies on the activation of pore-forming proteins, particularly the gasdermin family. Among the key regulators of pyroptosis is the inflammasome sensor NOD-like receptor 3 (NLRP3), a critical innate immune sensor responsible for regulating the activation of caspase-1 and gasdermin D. A deeper understanding of pyroptosis and its interplay with other forms of regulated cell death is emerging, shedding light on a complex regulatory network controlling pore-forming proteins and cell fate. Cell death processes play a central role in diseases such as metabolic dysfunction-associated steatotic liver disease, metabolic dysfunction-associated steatohepatitis, autoinflammatory disorders, and cancer. Cell death often acts as a starting point in these diseases, making it an appealing target for drug development. Yet, the complete molecular mechanisms are not fully understood, and new discoveries reveal promising novel avenues for therapeutic interventions. In this review, we summarize recent evidence on pathways and proteins controlling pyroptosis and gasdermins. Furthermore, we will address the role of pyroptosis and the gasdermin family in metabolic dysfunction-associated steatotic liver disease and steatohepatitis. Additionally, we highlight new potential therapeutic targets for treating metabolic dysfunction-associated steatohepatitis and other inflammatory-associated diseases.

Inhibition of the NF-κB Signaling Pathway Alleviates Pyroptosis in Bladder Epithelial Cells and Neurogenic Bladder Fibrosis

Most children with a neurogenic bladder (NB) have bladder fibrosis, which causes irreversible bladder dysfunction and damage to the upper urinary tract. However, the mechanism of bladder fibrosis remains unclear. This study aimed to investigate the underlying causes of bladder fibrosis. Here, the lumbar 6 (L6) and sacral 1 (S1) spinal nerves of Sprague Dawley rats were severed bilaterally to establish NB models. Using RNA-seq, we discovered that the NF-κB signaling pathway and inflammation were upregulated in spinal cord injury (SCI)-induced bladder fibrosis. Subsequent Western blotting, enzyme-linked immunosorbent assays, immunohistochemical staining, and immunofluorescence staining verified the RNA-seq findings. To further clarify whether the NF-κB signaling pathway and pyroptosis were involved in bladder fibrosis, a TGF-β1-treated urinary epithelial cell line (SV-HUC-1 cells) was used as an in vitro model. Based on the results of RNA-seq, we consistently found that the NF-κB signaling pathway and pyroptosis might play important roles in TGF-β1-treated cells. Further experiments also confirmed the RNA-seq findings in vitro. Moreover, using the NLRP3 inhibitor MCC950 rescued TGF-β1-induced fibrosis, and the NF-κB signaling pathway inhibitor BAY 11-7082 effectively rescued TGF-β1-induced pyroptosis and the deposition of extracellular matrix by SV-HUC-1 cells. In summary, our research demonstrated for the first time that the NF-κB signaling pathway inhibition rescued bladder epithelial cells pyroptosis and fibrosis in neurogenic bladders.

Galectin-3: therapeutic targeting in liver disease

INTRODUCTION

The rising incidence of liver diseases is a worldwide healthcare concern. However, the therapeutic options to manage chronic inflammation and fibrosis, the processes at the basis of morbidity and mortality of liver diseases, are very limited. Galectin 3 (Gal-3) is a protein implicated in fibrosis in multiple organs. Several Gal-3 inhibitors are currently in clinical development.

AREAS COVERED

This review describes our current understanding of the role of Gal-3 in chronic liver diseases, with special emphasis on fibrosis. Also, we review therapeutic advances based on Gal-3 inhibition, describing drug properties and their current status in clinical research.

EXPERT OPINION

Currently, the known effects of Gal-3 point to a direct activation of the NLRP3 inflammasome leading to its activation in liver macrophages and activated macrophages play a key role in tissue fibrogenesis. However, more research is needed to elucidate the role of Gal-3 in the different activation pathways, dissecting the intracellular and extracellular mechanisms of Gal-3, and its role in pathogenesis. Gal-3 could be a target for early therapy of numerous hepatic diseases and, given the lack of therapeutic options for liver fibrosis, there is a strong pharmacologic potential for Gal-3-based therapies.

NOD-like receptors in the pathogenesis of metabolic (dysfunction)-associated fatty liver disease: Therapeutic agents targeting NOD-like receptors

BACKGROUND AND AIMS

In metabolic (dysfunction)-associated fatty liver disease (MAFLD), activation of inflammatory processes marks the transition of simple steatosis to steatohepatitis, which can further evolve to advanced fibrosis or hepatocellular carcinoma. Under the stress of chronic overnutrition, the innate immune system orchestrates hepatic inflammation through pattern recognition receptors (PRRs). Cytosolic PRRs that include NOD-like receptors (NLRs) are crucial for inducing inflammatory processes in the liver.

METHODS

A literature search was performed with Medline (PubMed), Google Scholar and Scopus electronic databases till January 2023, using relevant keywords to extract studies describing the role of NLRs in the pathogenesis of MAFLD.

RESULTS

Several NLRs operate through the formation of inflammasomes, which are multimolecular complexes that generate pro-inflammatory cytokines and induce pyroptotic cell death. A multitude of pharmacological agents target NLRs and improve several aspects of MAFLD. In this review, we discuss the current concepts related to the role of NLRs in the pathogenesis of MAFLD and its complications. We also discuss the latest research on MAFLD therapeutics functioning through NLRs.

CONCLUSIONS

NLRs play a significant role in the pathogenesis of MAFLD and its consequences, especially through generation of inflammasomes, such as NLRP3 inflammasomes. Lifestyle changes (exercise, coffee consumption) and therapeutic agents (GLP-1 receptor agonists, sodium-glucose cotransporter-2 inhibitors, obeticholic acid) improve MAFLD and its complications partly through blockade of NLRP3 inflammasome activation. New studies are required to explore these inflammatory pathways fully for the treatment of MAFLD.

The NLRP3 inflammasome: contributions to inflammation-related diseases

The NOD-like receptor protein 3 (NLRP3) inflammasome is a protein complex that regulates innate immune responses by activating caspase-1 and the inflammatory cytokines interleukin (IL)-1β and IL-18. Multiple studies have demonstrated the importance of the NLRP3 inflammasome in the development of immune and inflammation-related diseases, including arthritis, Alzheimer's disease, inflammatory bowel disease, and other autoimmune and autoinflammatory diseases. This review first explains the activation and regulatory mechanism of the NLRP3 inflammasome. Secondly, we focus on the role of the NLRP3 inflammasome in various inflammation-related diseases. Finally, we look forward to new methods for targeting the NLRP3 inflammasome to treat inflammation-related diseases, and provide new ideas for clinical treatment.

Interleukin-18 signaling promotes activation of hepatic stellate cells in mouse liver fibrosis

BACKGROUND AND AIMS

Nucleotide-binding oligomerization domain-like receptor-family pyrin domain-containing 3 (NLRP3) inflammasome activation has been shown to result in liver fibrosis. Mechanisms and downstream signaling remain incompletely understood. Here, we studied the role of IL-18 in hepatic stellate cells (HSCs), and its impact on liver fibrosis.

APPROACH AND RESULTS

We observed significantly increased serum levels of IL-18 (128.4 pg/ml vs. 74.9 pg/ml) and IL-18 binding protein (BP; 46.50 ng/ml vs. 15.35 ng/ml) in patients with liver cirrhosis compared with healthy controls. Single cell RNA sequencing data showed that an immunoregulatory subset of murine HSCs highly expresses Il18 and Il18r1 . Treatment of cultured primary murine HSC with recombinant mouse IL-18 accelerated their transdifferentiation into myofibroblasts. In vivo , IL-18 receptor-deficient mice had reduced liver fibrosis in a model of fibrosis induced by HSC-specific NLRP3 overactivation. Whole liver RNA sequencing analysis from a murine model of severe NASH-induced fibrosis by feeding a choline-deficient, L-amino acid-defined, high fat diet showed that genes related to IL-18 and its downstream signaling were significantly upregulated, and Il18-/- mice receiving this diet for 10 weeks showed protection from fibrotic changes with decreased number of alpha smooth muscle actin-positive cells and collagen deposition. HSC activation triggered by NLRP3 inflammasome activation was abrogated when IL-18 signaling was blocked by its naturally occurring antagonist IL-18BP. Accordingly, we observed that the severe inflammatory phenotype associated with myeloid cell-specific NLRP3 gain-of-function was rescued by IL-18BP.

CONCLUSIONS

Our study highlights the role of IL-18 in the development of liver fibrosis by its direct effect on HSC activation identifying IL-18 as a target to treat liver fibrosis.

Mincle-GSDMD-mediated release of IL-1β small extracellular vesicles from hepatic macrophages in ethanol-induced liver injury

BACKGROUND

Macrophage-inducible C-type lectin (Mincle) is expressed on hepatic macrophages and senses ethanol (EtOH)-induced danger signals released from dying hepatocytes and promotes IL-1β production. However, it remains unclear what and how EtOH-induced Mincle ligands activate downstream signaling events to mediate IL-1β release and contribute to alcohol-associated liver disease (ALD). In this study, we investigated the association of circulating β-glucosylceramide (β-GluCer), an endogenous Mincle ligand, with severity of ALD and examined the mechanism by which β-GluCer engages Mincle on hepatic macrophages to release IL-1β in the absence of cell death and exacerbates ALD.

METHOD AND RESULTS

Concentrations of β-GluCer were increased in serum of patients with severe AH and correlated with disease severity. Challenge of hepatic macrophages with lipopolysaccharide and β-GluCer induced formation of a Mincle and Gsdmd-dependent secretory complex containing chaperoned full-length gasdermin D (Hsp90-CDC37-NEDD4) with polyubiquitinated pro-IL-1β and components of the Caspase 8-NLRP3 inflammasome loaded as cargo in small extracellular vesicles (sEVs). Gao-binge EtOH exposure to wild-type, but not Mincle-/- and Gsdmd-/-, mice increased release of IL-1β-containing sEVs from liver explant cultures. Myeloid-specific deletion of Gsdmd similarly decreased the formation of sEVs by liver explant cultures and protected mice from EtOH-induced liver injury. sEVs collected from EtOH-fed wild-type, but not Gsdmd-/-, mice promoted injury of cultured hepatocytes and, when injected into wild-type mice, aggravated Gao-binge EtOH-induced liver injury.

CONCLUSION

β-GluCer functions as a danger-associated molecular pattern activating Mincle-dependent gasdermin D-mediated formation and release of IL-1β-containing sEVs, which in turn exacerbate hepatocyte cell death and contribute to the pathogenesis of ALD.

Mechanisms of NLRP3 inflammasome-mediated hepatic stellate cell activation: Therapeutic potential for liver fibrosis

The liver injury leads to an inflammatory response, which causes the activation of hepatic stellate cells (HSCs) that further secrete ECM proteins and play an important role in liver fibrosis. Moreover, the inflammatory response is a driving force for fibrogenesis, which is triggered by many types of injuries. Exaggerated inflammatory immune responses are mediated by cytoplasmic protein complexes known as inflammasomes, which are involved in many chronic liver diseases. Inflammasomes are pattern recognition receptors (PRRs) that can sense any microbial motifs known as pathogen-associated molecular patterns (PAMPs), and host- or environmental-derived stress signals known as damage-associated molecular patterns (DAMPs). The inflammasomes cause caspase-mediated proteolytic cleavage of pro-IL-1β and pro-IL-18 into active IL-1β and IL-18. In this review, we provide a comprehensive summary of the important roles of NLRP3 inflammasome in the pathogenesis of liver fibrosis with an emphasis on several direct and indirect pathways responsible for the NLRP3 inflammasome-mediated HSCs activation and fibrogenesis. In addition, we discuss the general pharmacological and genetics strategies for the inhibition of NLRP3 inflammasome activation and its downstream signaling with examples of emerging pharmacotherapeutics, targeting the NLRP3 inflammasome signaling as well as a possible way to develop effective and safer NLRP3 inflammasome inhibitors.

STING mediates hepatocyte pyroptosis in liver fibrosis by Epigenetically activating the NLRP3 inflammasome

The activation of stimulator of interferon genes (STING) and NOD-like receptor protein 3 (NLRP3) inflammasome-mediated pyroptosis signaling pathways represent two distinct central mechanisms in liver disease. However, the interconnections between these two pathways and the epigenetic regulation of the STING-NLRP3 axis in hepatocyte pyroptosis during liver fibrosis remain unknown. STING and NLRP3 inflammasome signaling pathways are activated in fibrotic livers but are suppressed by Sting knockout. Sting knockout ameliorated hepatic pyroptosis, inflammation, and fibrosis. In vitro, STING induces pyroptosis in primary murine hepatocytes by activating the NLRP3 inflammasome. H3K4-specific histone methyltransferase WD repeat-containing protein 5 (WDR5) and DOT1-like histone H3K79 methyltransferase (DOT1L) are identified to regulate NLRP3 expression in STING-overexpressing AML12 hepatocytes. WDR5/DOT1L-mediated histone methylation enhances interferon regulatory transcription factor 3 (IRF3) binding to the Nlrp3 promoter and promotes STING-induced Nlrp3 transcription in hepatocytes. Moreover, hepatocyte-specific Nlrp3 deletion and downstream Gasdermin D (Gsdmd) knockout attenuate hepatic pyroptosis, inflammation, and fibrosis. RNA-sequencing and metabolomics analysis in murine livers and primary hepatocytes show that oxidative stress and metabolic reprogramming might participate in NLRP3-mediated hepatocyte pyroptosis and liver fibrosis. The STING-NLRP3-GSDMD axis inhibition suppresses hepatic ROS generation. In conclusion, this study describes a novel epigenetic mechanism by which the STING-WDR5/DOT1L/IRF3-NLRP3 signaling pathway enhances hepatocyte pyroptosis and hepatic inflammation in liver fibrosis.

Curcumin Alleviates Aflatoxin B1-Induced Liver Pyroptosis and Fibrosis by Regulating the JAK2/NLRP3 Signaling Pathway in Ducks

Aflatoxin B₁ (AFB₁) is a serious pollutant in feed and food which causes liver inflammation, fibrosis, and even cirrhosis. The Janus kinase 2 (JAK2)/signal transducers and activators of the transcription 3 (STAT3) signaling pathway is widely involved in inflammatory response and promotes the activation of nod-like receptor protein 3 (NLRP3) inflammasome, thus leading to pyroptosis and fibrosis. Curcumin is a natural compound with anti-inflammatory and anti-cancer properties. However, whether AFB₁ exposure leads to the activation of the JAK2/NLRP3 signaling pathway in the liver and whether curcumin can regulate this pathway to influence pyroptosis and fibrosis in the liver remains unclear. In order to clarify these problems, we first treated ducklings with 0, 30, or 60 µg/kg AFB₁ for 21 days. We found that AFB₁ exposure caused growth inhibition, liver structural and functional damage, and activated JAK2/NLRP3-mediated liver pyroptosis and fibrosis in ducks. Secondly, ducklings were divided into a control group, 60 µg/kg AFB₁ group, and 60 µg/kg AFB₁ + 500 mg/kg curcumin group. We found that curcumin significantly inhibited the activation of the JAK2/STAT3 pathway and NLRP3 inflammasome, as well as the occurrence of pyroptosis and fibrosis in AFB₁-exposed duck livers. These results suggested that curcumin alleviated AFB₁-induced liver pyroptosis and fibrosis by regulating the JAK2/NLRP3 signaling pathway in ducks. Curcumin is a potential agent for preventing and treating liver toxicity of AFB₁.

Attenuation of hepatic fibrosis by p-Coumaric acid via modulation of NLRP3 inflammasome activation in C57BL/6 mice

A prolonged high-fat and high-sucrose (HFHS) diet induces hepatic inflammation and mediates hepatic stellate cell (HSC) activation, which result in hepatic fibrosis. Aberrant activation of the innate immune system components, such as the NOD-like receptor protein 3 (NLRP3) inflammasome, has been implicated in HSC activation and hepatic fibrosis. We have previously shown that p-coumaric acid (PCA)-enriched peanut sprout extracts exert anti-inflammatory effects. However, it is unknown whether PCA reduces hepatic fibrosis by modulating innate immunity and HSC activation. To test this hypothesis, C57BL/6 male mice were randomly assigned to three groups and fed low-fat (LF) diet (11% calories from fat), high-fat (HF) diet (60% calories from fat, 0.2% cholesterol) with sucrose drink (20% sucrose, HFHS), or HFHS diet with PCA treatment (HFHS+PCA, 50 mg/kg body weight, intraperitoneally) for 13 weeks. The results showed that PCA treatment (1) partly improved systemic insulin sensitivity without altering adiposity, (2) attenuated hepatic signaling pathways associated with NLRP3 inflammasome activation, including toll-like receptor 4 (TLR4)/nuclear factor kappa B (NFκB), and endoplasmic reticulum/oxidative stress, and (3) reduced circulating interleukin (IL)-1β levels. More importantly, PCA ameliorated hepatic fibrosis compared to that in the HFHS group, and the anti-fibrogenic effects of PCA were confirmed in vitro in transforming growth factor β (TGFβ) treated-LX-2 HSCs. The role of PCA in decreased NLRP3 activation and caspase-1 cleavage was recapitulated in primary bone marrow‒derived macrophages. These findings indicate that PCA contributes to the prevention of HFHS diet‒mediated liver fibrosis, partly by attenuating the activation of the NLRP3 inflammasome.

Oxidative stress-related canonical pyroptosis pathway, as a target of liver toxicity triggered by zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnO NPs) have been widely used in the fields of daily necessities, clinical diagnosis, drug delivery and agricultural production. The improper use of ZnO NPs could pose a risk to ecological environment and public health. Liver has been known as a critical toxic target of ZnO NPs. However, the question whether ZnO NPs lead to hepatocyte death through pyroptosis has not been answered yet, and the effect of oxidative stress on ZnO NPs-induced pyroptosis remains a mystery. We revealed that ZnO NPs disrupted zinc homeostasis and induced oxidative stress impairment in rat liver. Meanwhile, ZnO NPs triggered the assembly of NLRP3-ASC-Caspase-1 inflammatory complex and pyroptosis in both rat liver and HepG2 cells, further causing the activation of GSDMD, promoting the leakage of inflammatory cytokines including IL-1β and IL-18. Importantly, the inhibition of oxidative stress was found to provide protection against pyroptosis in hepatocyte exposed to ZnO NPs. We identified a novel mechanism of liver damage induced by ZnO NPs, demonstrating the activation of canonical Caspase-1-dependent pyroptosis pathway and clarifying the protection of antioxidation against pyroptosis damage. Our discovery provided a support for risk assessment of ZnO NPs and target exploration for clinical treatment related to pyroptosis.

Intercellular communication among liver cells in the perisinusoidal space of the injured liver: Pathophysiology and therapeutic directions

Hepatic stellate cells (HSCs) in the perisinusoidal space are surrounded by hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, and other resident immune cells. In the normal liver, HSCs communicate with these cells to maintain normal liver functions. However, after chronic liver injury, injured hepatocytes release several proinflammatory mediators, reactive oxygen species, and damage-associated molecular patterns into the perisinusoidal space. Consequently, such alteration activates quiescent HSCs to acquire a myofibroblast-like phenotype and express high amounts of transforming growth factor-β1, angiopoietins, vascular endothelial growth factors, interleukins 6 and 8, fibril forming collagens, laminin, and E-cadherin. These phenotypic and functional transdifferentiation lead to hepatic fibrosis with a typical abnormal extracellular matrix synthesis and disorganization of the perisinusoidal space of the injured liver. Those changes provide a favorable environment that regulates tumor cell proliferation, migration, adhesion, and survival in the perisinusoidal space. Such tumor cells by releasing transforming growth factor-β1 and other cytokines, will, in turn, activate and deeply interact with HSCs via a bidirectional loop. Furthermore, hepatocellular carcinoma-derived mediators convert HSCs and macrophages into protumorigenic cell populations. Thus, the perisinusoidal space serves as a critical hub for activating HSCs and their interactions with other cell types, which cause a variety of liver diseases such as hepatic inflammation, fibrosis, cirrhosis, and their complications, such as portal hypertension and hepatocellular carcinoma. Therefore, targeting the crosstalk between activated HSCs and tumor cells/immune cells in the tumor microenvironment may also support a promising therapeutic strategy.

Treating inflammation to combat non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) with its more progressive form non-alcoholic steatohepatitis (NASH) has become the most common chronic liver disease, thereby representing a great burden for patients and healthcare systems. Specific pharmacological therapies for NAFLD are still missing. Inflammation is an important driver in the pathogenesis of NASH, and the mechanisms underlying inflammation in NAFLD represent possible therapeutic targets. In NASH, various intra- and extrahepatic triggers involved in the metabolic injury typically lead to the activation of different immune cells. This includes hepatic Kupffer cells, i.e. liver-resident macrophages, which can adopt an inflammatory phenotype and activate other immune cells by releasing inflammatory cytokines. As inflammation progresses, Kupffer cells are increasingly replaced by monocyte-derived macrophages with a distinct lipid-associated and scar-associated phenotype. Many other immune cells, including neutrophils, T lymphocytes - such as auto-aggressive cytotoxic as well as regulatory T cells - and innate lymphoid cells balance the progression and regression of inflammation and subsequent fibrosis. The detailed understanding of inflammatory cell subsets and their activation pathways prompted preclinical and clinical exploration of potential targets in NAFLD/NASH. These approaches to target inflammation in NASH include inhibition of immune cell recruitment via chemokine receptors (e.g. cenicriviroc), neutralization of CD44 or galectin-3 as well as agonism to nuclear factors like peroxisome proliferator-activated receptors and farnesoid X receptor that interfere with the activation of immune cells. As some of these approaches did not demonstrate convincing efficacy as monotherapies, a rational and personalized combination of therapeutic interventions may be needed for the near future.

Activation of primary hepatic stellate cells and liver fibrosis induced by targeting TGF-β1/Smad signaling in schistosomiasis in mice

BACKGROUND

In mice, liver fibrosis is the most serious pathologic change during Schistosoma japonicum (S. japonicum) infection. Schistosomiasis is mainly characterized by schistosome egg-induced granulomatous fibrosis. Hepatic stellate cells (HSCs) are mainly responsible for the net accumulation of collagens and fibrosis formation in the liver. Activated HSCs regulated by transforming growth factor-β1 (TGF-β1)/Smad signaling have emerged as the critical regulatory pathway in hepatitis virus or carbon tetrachloride-induced liver fibrosis. However, the detailed mechanism of HSC activation in schistosome-induced liver fibrosis is poorly understood.

METHODS

Schistosoma japonicum-induced murine models and a control group were generated by abdominal infection with 15 (± 1) cercariae. The purity of cultured primary HSCs was evaluated by immunocytochemistry. The histopathological changes in the livers of infected mice were estimated by hematoxylin-eosin and Masson staining. Dynamic expression of pro-fibrotic molecules and microRNAs was detected by real-time quantitative PCR (RT-qPCR). Mainly members involved in the TGF-β1/Smad signaling pathway were examined via RT-qPCR and Western blot.

RESULTS

The egg-induced granulomatous inflammation formed at 4 weeks post-infection (wpi) and developed progressively. Alpha-smooth muscle actin (α-SMA), collagen I, collagen III, TGF-β1, Smad2, Smad3, and Smad4 showed a significant increase in mitochondrial RNA (mRNA) and protein expression compared with the control group at 7 and 9 weeks post-infection (wpi), while an opposite effect on Smad7 was observed. In addition, the mRNA expression of microRNA-21 (miRNA-21) was significantly increased at 7 wpi, and the mRNA expression of miRNA-454 was decreased starting from 4 wpi.

CONCLUSION

Our present findings revealed that HSCs regulated by the TGF-β1/Smad signaling pathway play an important role in liver fibrosis in S. japonicum-infected mice, which may provide proof of concept for liver fibrosis in schistosomiasis.

Regulation of the macrophage-hepatic stellate cell interaction by targeting macrophage peroxisome proliferator-activated receptor gamma to prevent non-alcoholic steatohepatitis progression in mice

BACKGROUND & AIMS

Macrophages display remarkable plasticity and can interact with surrounding cells to affect hepatic immunity and tissue remodelling during the progression of liver diseases. Peroxisome proliferator-activated receptor gamma (PPARγ) plays a critical role in macrophage maturation, polarization and metabolism. In this study, we investigated the role of PPARγ in macrophage-hepatic stellate cell (HSC) interaction during non-alcoholic steatohepatitis (NASH) development.

METHODS

Wild-type, Pparg^fl/fl and Pparg^ΔLyz2 mice were fed a methionine- and choline-deficient (MCD) diet to induce NASH. Depletion of macrophages was performed using an injection of gadolinium chloride intraperitoneally. PPARγ-overexpressing or PPARγ-knockout macrophages were stimulated with saturated fatty acid (SFA) and cocultured with HSCs in a conditioned medium or the transwell coculture system.

RESULTS

Depletion of macrophages inhibited HSC activation and ameliorated NASH progression in MCD diet-fed mice. Coculturing HSCs with macrophages or culturing HSCs in a macrophage-conditioned medium-facilitated HSC activation, and this effect was magnified when macrophages were metabolically activated by SFA. Moreover, the absence of PPARγ in macrophages enhanced metabolic activation, promoting the migration and activation of HSCs through IL-1β and CCL2. In contrast, overexpression of PPARγ in macrophages obtained the opposite effects. In vivo, macrophage-specific PPARγ knockout affected the phenotype of hepatic macrophages and HSCs, involving the MAPK and NLRP3/caspase-1/IL-1β signalling pathways. Infiltrating hepatic monocyte-derived macrophages became the predominant macrophages in NASH liver, especially in Pparg^ΔLyz2 mice, paralleling with aggravated inflammation and fibrosis.

CONCLUSIONS

Regulating macrophage PPARγ affected the metabolic activation of macrophages and their interaction with HSCs. Macrophage-specific PPARγ may be an attractive therapeutic target for protecting against NASH-associated inflammation and fibrosis.

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.

Antifibrotic effect and long-term outcome of SGLT2 inhibitors in patients with NAFLD complicated by diabetes mellitus

The aim of this retrospective multicenter study was to clarify the antifibrotic effect and long-term outcome of sodium glucose cotransporter 2 inhibitors (SGLT2-Is) in patients with nonalcoholic fatty liver disease (NAFLD) complicated by type 2 diabetes mellitus (T2DM). Of the 1262 consecutive patients with T2DM who recently received SGLT2-Is, 202 patients with NAFLD had been receiving SGLT2-Is for more than 48 weeks and were subjected to this analysis. Furthermore, 109 patients who had been on SGLT2-I therapy for more than 3 years at the time of analysis were assessed for the long-term effects of SGLT2-Is. Significant decreases in body weight, liver transaminases, plasma glucose, hemoglobin A1c, and Fibrosis-4 (FIB-4) index were found at week 48. Overall, the median value of FIB-4 index decreased from 1.42 at baseline to 1.25 at week 48 (p < 0.001). In the low-risk group (FIB-4 index < 1.3), there was no significant change in the FIB-4 index. In the intermediate-risk (≥1.3 and <2.67) and high-risk (≥2.67) groups, the median levels significantly decreased from 1.77 and 3.33 at baseline to 1.58 and 2.75 at week 48, respectively (p < 0.001 for both). Improvements in body weight, glucose control, liver transaminases, and FIB-4 index were found at 3 years of SGLT2-I treatment. In the intermediate-risk and high-risk groups (≥1.3 FIB-4 index), the FIB-4 index maintained a significant reduction from baseline throughout the 3 years of treatment. Conclusion: This study showed that SGLT2-Is offered a favorable effect on improvement in FIB-4 index as a surrogate marker of liver fibrosis in patient with NAFLD complicated by T2DM, especially those with intermediate and high risks of advanced fibrosis, and this antifibrotic effect is sustained for the long term.

Toll-like receptor 4 signaling pathway mediates both liver and kidney injuries in mice with hepatorenal syndrome

Hepatorenal syndrome (HRS) is a complication of cirrhosis with high morbidity and mortality. Nevertheless, the underlying mechanism involving how kidney injury aggravates the progression of cirrhosis remains unclear. This study aims to explore the role of the Toll-like receptor 4 (TLR4) signaling pathway in mediating liver and kidney injuries in HRS mice induced by unilateral ureteral obstruction (UUO) and/or bile duct ligation (BDL). Two weeks after UUO, there were no obvious pathological changes in mouse liver and the unligated side of kidney. Nevertheless, impaired liver and kidney functions, inflammatory response, and fibrosis were examined in mice after 2 wk of BDL. Compared with those of other groups, mice in the BDL + UUO group presented severer liver and kidney injuries, higher levels of inflammatory factors, and faster deposition of collagens, suggesting that kidney injuries accelerated the aggravation of HRS. Correlation analysis identified a positive correlation between expression levels of inflammatory factors and fibrotic levels. Meanwhile, TLR4 and its ligand MyD88 were upregulated during the process of liver and kidney injuries in HRS mice. Further animal experiments in transgenic TLR4^-/- mice or in those treated with TAK242, a small molecule inhibitor of TLR4, showed that blocking the TLR4 signaling pathway significantly improved survival quality and survival rate in HRS mice by alleviating liver fibrosis and kidney injury. It is concluded that kidney dysfunction plays an important role in the aggravation of cirrhosis, which may be attributed to the TLR4 signaling pathway. Targeting TLR4 could be a promising therapeutic strategy for protecting both liver and kidneys in patients with HRS.NEW & NOTEWORTHY Our study established BDL, UUO, and BDL + UUO models, providing a novel idea for analyzing liver and kidney diseases. It is highlighted that the kidney injury accelerated the aggravation of HRS via inflammatory response, which could be protected by inhibiting the TLR4 signaling pathway. We believed that targeting TLR4 was a promising therapeutic strategy for protecting both liver and kidney functions in patients with HRS.

NLRP3 inflammasome in digestive diseases: From mechanism to therapy

Digestive system diseases remain a formidable challenge to human health. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most characteristic multimeric protein complex and is involved in a wide range of digestive diseases as intracellular innate immune sensors. It has emerged as a research hotspot in recent years. In this context, we provide a comprehensive review of NLRP3 inflammasome priming and activation in the pathogenesis of digestive diseases, including clinical and preclinical studies. Moreover, the scientific evidence of small-molecule chemical drugs, biologics, and phytochemicals, which acts on different steps of the NLRP3 inflammasome, is reviewed. Above all, deep interrogation of the NLRP3 inflammasome is a better insight of the pathomechanism of digestive diseases. We believe that the NLRP3 inflammasome will hold promise as a novel valuable target and research direction for treating digestive disorders.

FASN inhibition targets multiple drivers of NASH by reducing steatosis, inflammation and fibrosis in preclinical models

Fatty acid synthase (FASN) is an attractive therapeutic target in non-alcoholic steatohepatitis (NASH) because it drives de novo lipogenesis and mediates pro-inflammatory and fibrogenic signaling. We therefore tested pharmacological inhibition of FASN in human cell culture and in three diet induced mouse models of NASH. Three related FASN inhibitors were used; TVB-3664, TVB-3166 and clinical stage TVB-2640 (denifanstat). In human primary liver microtissues, FASN inhibiton (FASNi) decreased triglyceride (TG) content, consistent with direct anti-steatotic activity. In human hepatic stellate cells, FASNi reduced markers of fibrosis including collagen1α (COL1α1) and α-smooth muscle actin (αSMA). In CD4+ T cells exposed to NASH-related cytokines, FASNi decreased production of Th17 cells, and reduced IL-1β release in LPS-stimulated PBMCs. In mice with diet induced NASH l, FASNi prevented development of hepatic steatosis and fibrosis, and reduced circulating IL-1β. In mice with established diet-induced NASH, FASNi reduced NAFLD activity score, fibrosis score, ALT and TG levels. In the CCl4-induced FAT-NASH mouse model, FASN inhibition decreased hepatic fibrosis and fibrosis markers, and development of hepatocellular carcinoma (HCC) tumors by 85%. These results demonstrate that FASN inhibition attenuates inflammatory and fibrotic drivers of NASH by direct inhibition of immune and stellate cells, beyond decreasing fat accumulation in hepatocytes. FASN inhibition therefore provides an opportunity to target three key hallmarks of NASH.