Gasdermin D plays a key role as a pyroptosis executor of non-alcoholic steatohepatitis in humans and mice

Research progress on sepsis-associated encephalopathy by inhibiting pyroptosis

Sepsis is a life-threatening condition characterized by multiple organ dysfunction syndrome resulted from dysregulated host responses to infection. Sepsis-associated encephalopathy (SAE) is one of the most common symptoms of acute-phase sepsis, with nearly 70 % of patients with sepsis ultimately developing SAE. Pyroptosis represents a type of cell death that is initiated by inflammation. This cell death type is associated with various infectious and noninfectious diseases. The gasdermin family proteins are crucial cell death executors and critical components in regulating the canonical pyroptosis pathway in microglia. In this review, we summarize the inhibitory effects of several drugs and genes on the pyroptosis pathway. Our findings suggest that several drugs (puerarin, VX765, HC067047, dexpramipexole, and Danhong injection), erbin gene, and TRIM45 knockdown improve SAE by suppressing the canonical pathway of NLRP3/caspase-1/gasdermin D-mediated pyroptosis. Therefore, they have significant importance in terms of brain protection. Moreover, we review the relevant literature published in recent years and summarize the research status and development prospects in this field to provide a basis for subsequent related research.

Discovery of a novel Thiazole amide inhibitor of Inflammasome and Pyroptosis pathways

Upon the activation of inflammasomes, inflammatory caspases cleave and activate gasdermin D (GSDMD), leading to pore formation that causes cell membrane rupture and amplifies downstream inflammatory responses. Dysregulated inflammasome activation and pyroptosis signaling pathways are implicated in numerous inflammatory diseases. In our work, a set of novel thiazole amide compounds with inhibitory activity against NLRP3 inflammasome-induced pyroptosis was identified. Of all the compounds tested, compound 21 demonstrated the most potent anti-pyroptotic effects. It suppressed GSDMD cleavage and decreased IL-1β and lactate dehydrogenase (LDH) release in a concentration-dependent manner. Compound 21 bound to NLRP3 protein and increased the thermal stability of NLRP3 concentration-dependently. The molecular docking and dynamics simulations revealed that compound 21 binds to the NLRP3 protein's active site, suppressing inflammasome activation. Further investigations showed that compound 21 also partially blocked upstream NF-κB signaling and downstream GSDMD N-terminal domain (GSDMD-NT) oligomerization, which explains its broad inhibitory effects on pyroptosis driven by multiple inflammasomes. Overall, this study presents a promising thiazole amide compound with inhibitory activity against inflammasome activation and subsequent pyroptosis, warranting further exploration.

A new type of Caspase-1 upon recognizing bacteria inhibits GSDME-dependent histone modification and NF-κB signaling

In the present study, a new type of Caspase-1 homolog is identified from Crassostrea gigas (defined as CgCas1-2D). It is composed of 2×DSRM-CASc domain and has closer evolutionary relationship with mammalian Caspase-1s. The mRNA expressions of CgCas1-2D increase significantly after Vibrio splendidus or LPS stimulation. Recombinant CgCas1-2D and its 2×DSRM and CASc domains all bind various PAMPs and bacteria. rCgCas1-2D shows the highest binding activity to human Caspase-1 substrate. Upon recognizing bacteria, CgCas1-2D co-localizes and interacts with CgGSDME, while it has no cleavage activity to CgGSDME. CgCas1-2D inhibits the histone methylation and acetylation levels and CgNF-κB/Rel nuclear translocation mediated by CgGSDME. In addition, CgCas1-2D suppresses the mRNA expression levels of cytokines mediated by GSDME-NF-κB/Rel axis. The results demonstrate that a new type of anti-inflammatory Caspase-1 identified from oyster upon recognizing various bacteria interacts with GSDME to inhibit the histone modification and NF-κB signaling to suppress the inflammation.

Mitigating PCOS progression: The protective effect of C-phycocyanin on ovarian granulosa cell pyroptosis via the NRF2/NLRP3/GSDMD pathway

BACKGROUND

Pyroptosis is a proinflammatory cell death process that contributes to inflammatory diseases. C-Phycocyanin (C-PC) is a water-soluble protein pigment primarily derived from cyanobacteria, and it exhibits anti-inflammatory effects. However, the role of natural C-PC in pyroptosis in human ovarian granulosa cells (GCs), particularly in conditions like polycystic ovary syndrome (PCOS), remains unclear. This study investigates the effects of C-PC on pyroptosis and its relevance to PCOS.

METHODS

Here dehydroepiandrosterone (DHEA) was used to induce PCOS in a mouse model that was characterized by an irregular oestrous cycle, cystic follicles and an elevated serum hormone level. DHEA treatment was used to induce GC pyroptosis. Scanning electron microscopy (SEM) was used to determine cell morphology. The expression levels of key proteins for oxidative stress and pyroptosis, including nuclear factor erythroid 2-related factor 2 (NRF2), NLR family of pyrroline-containing structural domain 3 (NLRP3) inflammasomes, cleaved caspase-1, and N-GSDMD were investigated in vivo and in vitro by Western blotting and immunofluorescence staining.

RESULTS

C-PC restored the estrous cycle in PCOS mice, reduced testosterone levels, and decreased cystic follicles. It attenuated PCOS progression by reducing oxidative stress level and suppressing GCs pyroptosis. At the cellular level, C-PC inhibited DHEA-induced GC pyroptosis by blocking NLRP3 inflammasome activation and lowering ROS, effects reversed by the NRF2 inhibitor (ML385). Molecular docking analysis and CETSA suggested that C-PC may protect against PCOS by activating the NRF2 pathway or by indirectly binding to the Ser27 site of GSDMD. In addition, C-PC suppressed ROS/p38-MAPK activation induced by DHEA, and p38-MAPK agonists diminished its effect on NLRP3 inflammasome activity and GC pyroptosis protection.

CONCLUSION

C-PC exerts a protective effect on GC pyroptosis through the NRF2/NLRP3/GSDMD and ROS/p-38 MAPK pathways, highlighting its potential to mitigate inflammation and its relevance to reproductive health issues like PCOS.

Potential of queen bee larvae as a dietary supplement for obesity management: modulating the gut microbiota and promoting liver lipid metabolism

Queen bee larvae (QBL) have been consumed as both a traditional food and medicine in China for thousands of years; however, their specific benefits for human health, particularly their potential anti-obesity property, remain underexplored. This study investigated the anti-obesity effect of QBL freeze-dried powder (QBLF) on high-fat diet (HFD) induced obesity in mice and explored the underlying mechanisms. Our findings showed that QBLF effectively reduced body weight, fasting blood glucose levels, lipid accumulation, and inflammation in HFD mice. 16S rRNA sequencing revealed that QBLF significantly modulated the gut microbiota disrupted by an HFD, notably increasing the relative abundance of beneficial microbes such as Ileibacterium, Clostridium sensu stricto 1, Incertae sedis, Streptococcus, Lactococcus, Clostridia UCG-014, and Lachnospiraceae UCG-006, which were inversely associated with obesity-related phenotypes in the mice. RNA sequencing analysis further demonstrated that QBLF intervention upregulated the expression of genes involved in liver lipid metabolism, including Pck1, Cyp4a10, Cyp4a14, and G6pc, while downregulating genes associated with the inflammatory response, such as Cxcl10, Ccl2, Traf1, Mapk15, Lcn2, and Fosb. These results suggested that QBLF can ameliorate HFD-induced obesity through regulating the gut microbiota, promoting liver lipid metabolism, and reducing inflammatory response.

High uric acid exacerbates nonalcoholic steatohepatitis through NLRP3 inflammasome and Gasdermin D-mediated pyroptosis

Hyperuricemia is independently associated with an increased risk of nonalcoholic steatohepatitis (NASH), but the underlying mechanisms responsible for this association remain unclear. We first analyzed the association between intrahepatic UA levels and gasdermin D (GSDMD)-mediated pyroptosis in vivo and in vitro. We subsequently generated hepatic-specific glucose transporter 9 (GLUT9)-knockout mice and GSDMD knockout (GSDMD-/-) mice to explore the role of intrahepatic UA in GSDMD-induced pyroptosis in NASH. We found that high intrahepatic UA levels were positively related to GSDMD-mediated pyroptosis in NASH mice. The inhibition of hepatic UA production by allopurinol alleviated hepatic inflammation and GSDMD-mediated pyroptosis in NASH mice. Hepatic-specific knockout of Glut9 significantly decreased intrahepatic UA levels, attenuated NOD-like receptor family pyrin domain containing 3 (NLRP3)-Caspase-1-GSDMD-mediated pyroptosis in hepatocytes, and ameliorated hepatic inflammation and fibrosis in different mouse models of NASH. Further experiments revealed that inhibiting the NLRP3/Caspase-1/GSDMD pathway obviously blocked UA-induced pyroptosis and inflammation in hepatocytes. Additionally, GSDMD deficiency markedly reversed hepatic inflammation and fibrosis in NASH mice. In conclusion, our results showed that high UA could induce NLRP3-Caspase1-GSDMD-mediated pyroptosis, thereby aggravating NASH in mice.

Comprehensive Analysis Reveals the Molecular Features and Immune Infiltration of PANoptosis-Related Genes in Metabolic Dysfunction-Associated Steatotic Liver Disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD), a chronic inflammatory disorder characterized by alcohol-independent hepatic lipid accumulation, remains poorly understood in terms of PANoptosis involvement.

METHODS

We integrated high-throughput sequencing data with bioinformatics to profile differentially expressed genes (DEGs) and immune infiltration patterns in MASLD, identifying PANoptosis-associated DEGs (PANoDEGs). Machine learning algorithms prioritized key PANoDEGs, while ROC curves assessed their diagnostic efficacy. Cellular, animal, and clinical validations confirmed target expression.

RESULTS

Three PANoDEGs (SNHG16, Caspase-6, and Dynamin-1-like protein) exhibited strong MASLD associations and diagnostic significance. Immune profiling revealed elevated M1 macrophages, naïve B cells, and activated natural killer cells in MASLD tissues versus controls. Further experiments verified the expression of the key PANoDEGs.

CONCLUSIONS

This study provides new insights for further studies on the pathogenesis and treatment strategies of PANoptosis in MASLD.

High fat and high cholesterol diet induced cognitive impairment in GSDMD knockout mice via the compensatory activation of apoptosis pathway

Via the GSDMD knockout (KO) mice as model, we aimed to determine the roles of GSDMD-mediated pyroptosis and its crosstalk with apoptosis in regulating high fat high cholesterol (HFHC) diet associated cognitive dysfunction. Wild type (WT) and GSDMD KO mice were divided into 4 groups, i.e. WT control (WTCON), WT fed with HFHC (WTHFHC), GSDMD KO control (KOCON), GSDMD KO HFHC (KOHFHC). Compared to the KOCON group, mice from the KOHFHC group demonstrated the worst learning and memory disabilities. In the hippocampus, p-Tau ser404, RIPK1/RIP, cleaved caspase-3 and apoptosis rate were increased, while BDNF and p-CREB were reduced from the KOHFHC group. In the cortex, p-Tau ser404, p-Tau ser396, RIPK1/RIP, cleaved caspase-8 and cleaved caspase-3 were significantly increased, while BDNF, synaptophysin were reduced from KOHFHC group. RNA sequencing analysis showed that 2 pathways closely related to apoptosis were significantly upregulated from KOHFHC group compared to KOCON group, including apoptosis and positive regulation of execution phase of apoptosis. The combination of palmitic acid with LDC7559 further increased the number of apoptotic cells and cleaved caspase-3 protein expression compared to vehicle in BV2 cells and HT22 cells. In conclusion, knocking out GSDMD gene in mice had no notable effects on learning and memory abilities under normal diet, but notably led to cognitive dysfunction when stimulated by a high-fat and high-cholesterol diet. The inhibition of pyroptosis may unexpectedly compensate for the activation of exogenous apoptotic pathways, this might be associated with worsening of tau phosphorylation, synaptic plasticity, and neuroinflammation.

Identification of pyroptosis-associated gene to predict fibrosis and reveal immune characterization in non-alcoholic fatty liver disease

Despite advances in research, studies on predictive models for Non-Alcoholic Fatty Liver Disease (NAFLD)-related fibrosis remain limited. Identifying new biomarkers to distinguish Non-Alcoholic Steatohepatitis (NASH) from NAFLD would aid in the treatment of NASH. Gene expression and clinical profiles of NAFL and NASH patients were collected from databases. Differentially expressed genes with prognostic value were used to construct predictive model. Validation of fibrosis stage-related pyroptosis-related genes (PRGs) was performed using Sprague-Dawley rats liver fibrosis models induced by CCl4 or PS. Immune cell infiltration assessment demonstrated that stromal score, immune score, and ESTIMATE score were higher in patients with NASH compared to those with NAFL. BAX, BAK1, PYCARD, and NLRP3 were identified as hub genes that exhibit a strong correlation with fibrosis stage. Additionally, the expression of these genes was increased in fibrotic liver tissues induced by CCl4 and PS. The pyroptosis-associated gene signature effectively predicts the degree of liver fibrosis in NASH patients. Our study indicates that BAX, BAK1, PYCARD, and NLRP3 might serve as biomarkers for NASH-associated fibrosis.

The Ways to Die: Cell Death in Liver Pathophysiology

Liver diseases are closely associated with various cell death mechanisms, including apoptosis, necroptosis, autophagy, pyroptosis, and ferroptosis. Each process contributes uniquely to the pathophysiology of liver injury and repair. Importantly, these mechanisms are not limited to hepatocytes; they also significantly involve nonparenchymal cells. This review examines the molecular pathways and regulatory mechanisms underlying these forms of cell death in hepatocytes, emphasizing their roles in several liver diseases, such as ischemia-reperfusion injury, metabolic dysfunction-associated steatotic liver disease, drug-induced liver injury, and alcohol-associated liver disease. Recent insights into ferroptosis and pyroptosis may reveal novel therapeutic targets for managing liver diseases. This review aims to provide a comprehensive overview of these cell death mechanisms in the context of liver diseases, detailing their molecular signaling pathways and implications for potential treatment strategies.

Molecular mechanisms of pyroptosis in non-alcoholic steatohepatitis and feasible diagnosis and treatment strategies

Pyroptosis is a distinct form of cell death that plays a critical role in intensifying inflammatory responses. It primarily occurs via the classical pathway, non-classical pathway, caspase-3/6/7/8/9-mediated pathways, and granzyme-mediated pathways. Key effector proteins involved in the pyroptosis process include gasdermin family proteins and pannexin-1 protein. Pyroptosis is intricately linked to the onset and progression of non-alcoholic steatohepatitis (NASH). During the development of NASH, factors such as pyroptosis, innate immunity, lipotoxicity, endoplasmic reticulum stress, and gut microbiota imbalance interact and interweave, collectively driving disease progression. This review analyzes the molecular mechanisms of pyroptosis and its role in the pathogenesis of NASH. Furthermore, it explores potential diagnostic and therapeutic strategies targeting pyroptosis, offering new avenues for improving the diagnosis and treatment of NASH.

Bifidobacterium adolescentis prevents diabetes-induced liver injury via pyroptosis attenuation

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), along with non-alcoholic steatohepatitis (NASH), lacks definitive therapy and typically remains asymptomatic until reaching advanced stages. Lipid metabolism and inflammation management using probiotics such as Bifidobacterium adolescentis is suggested to alleviate or suppress NAFLD development. Hence, this study aims to investigate the effects of Bifidobacterium adolescentis treatment on mitigating pyroptosis, an inflammatory cell death pathway, in the liver of rats with NAFLD induced by high-fat diet (HFD) and streptozotocin (STZ) administration.

METHODS

Forty 8-week adult male Sprague Dawley rats were divided into four groups. Bifidobacterium adolescentis was administered for 8 and 16 weeks at 4 × 1010 CFU/day to rats fed a high-fat diet (HFD). Subsequently, the mRNA expression levels of pyroptotic-related genes including Cas1, Cas3, Cas11, NLRP3, GSDMD, IL-1β, and NF-κB were quantified in liver tissue using quantitative polymerase chain reaction (qPCR). Histopathological alterations and stereological changes in liver structure, as well as lipid profile (FBG, TG, TC, HDL, LDL), and liver indices (ALT, AST, ALP, LDH), were also evaluated across the different groups.

RESULTS

Bifidobacterium adolescentis administration significantly reduced the expression levels of NF-κB and pyroptotic-related genes. Additionally, this probiotic effectively reversed the adverse effects of the high-fat diet (HFD) on liver volume, Kupffer cell numbers, and hepatocyte nuclei. Furthermore, it improved the lipid profile and liver indices of rats fed with the HFD.

CONCLUSION

This study demonstrates that B. adolescentis supplementation prevents diabetes-induced liver injury by attenuating pyroptosis. These findings suggest that Bifidobacterium adolescentis may be a promising therapeutic approach for managing NAFLD and its associated complications, primarily by modulating key genes associated with pyroptosis and inflammation in rats fed with a high-fat diet.

Life-threatening risk factors contribute to the development of diseases with the highest mortality through the induction of regulated necrotic cell death

Chronic diseases affecting the cardiovascular system, diabetes mellitus, neurodegenerative diseases, and various other organ-specific conditions, involve different underlying pathological processes. However, they share common risk factors that contribute to the development and progression of these diseases, including air pollution, hypertension, obesity, high cholesterol levels, smoking and alcoholism. In this review, we aim to explore the connection between four types of diseases with different etiologies and various risk factors. We highlight that the presence of risk factors induces regulated necrotic cell death, leading to the release of damage-associated molecular patterns (DAMPs), ultimately resulting in sterile inflammation. Therefore, DAMP-mediated inflammation may be the link explaining how risk factors can lead to the development and maintenance of chronic diseases. To explore these processes, we summarize the main cell death pathways activated by the most common life-threatening risk factors, the types of released DAMPs and how these events are associated with the pathophysiology of diseases with the highest mortality. Various risk factors, such as smoking, air pollution, alcoholism, hypertension, obesity, and high cholesterol levels induce regulated necrosis. Subsequently, the release of DAMPs leads to chronic inflammation, which increases the risk of many diseases, including those with the highest mortality rates.

Portal hypertension aggravates Helicobacter pylori induced liver injury in mice via activating pyroptosis pathway

In recent years, it has been discovered that the pathogenic effect of Helicobacter pylori (H. pylori) is not only limited to the gastroduodenal region, but also plays a certain role in the occurrence and development of liver diseases. The aim of this study is to ascertain the existence of Helicobacter pylori translocation, investigate whether it leads to liver injury and its potential mechanism and examine whether portal hypertension exacerbates liver damage caused by H. pylori translocation. Twenty four male SPF C57BL/6J mice were divided into four groups (6 in each group): (1) control group (Normal); (2) portal hypertension group (PHT); (3) H. pylori infected group (Hp); (4) H. pylori and Portal hypertension group (Hp and PHT). The histopathological changes of the liver and gastric tissues were measured by HE staining and immunohistochemistry (IHC); ALT, AST, IL-6 and INF-γ was measured by ELISA; Western blot detected the expression of pyroptotic proteins in the liver. The pro-inflammatory mediators and liver function indexes of mice in Hp group, Hp and PHT group were higher than those in the normal and PHT group. In addition, the liver inflammatory cell infiltration and ballooning of the two groups of mice were more severe than those in the normal group and PHT group, Hp and PHT group were more severe; Hp group, Hp and PHT group mice liver tissues activated the pyroptotic process through NLRP3 inflammasome, which eventually led to cell damage. Post mice infection by H. pylori, H. pylori will translocate to the liver, and induce liver injury by aggravating inflammation and promoting pyroptosis. Moreover, when portal hypertension occurs, it promotes the displacement of H. pylori, thereby aggravating liver injury.

Sirtuin 1 Is a Potential Target for the Treatment of Neurogenic Intermittent Claudication by Modulating Pyroptosis

Neurogenic intermittent claudication (NIC) pathogenesis associated with lumbar spinal stenosis (LSS) remains unclear. However, pyroptosis has been implicated in the pathogenesis of various central nervous system disorders. Therefore, the present study aimed to explore the potential role of pyroptosis in NIC progression. Additionally, the present study investigated the possible involvement of Sirtuin 1 (Sirt1), a protein recognized for its neuroprotective properties, in mitigating the progression of NIC by alleviating pyroptosis. In the current study, a rat model of NIC associated with LSS was successfully constructed by inserting a silicone strip into the vertebral plates. The Basso Beattie Bresnahan score was employed to assess the motor function of rats. Western blot analysis was performed to measure the levels of pyroptosis-related proteins in rat spinal cord tissue. Meanwhile, PC-12 cells were cultured with H2O2 to establish an in vitro model of oxidative stress, allowing to investigate the effects of Sirt1 on cell pyroptosis and oxidative stress in H2O2-treated cells. The current results showed that rats with NIC developed both motor and sensory dysfunction. Additionally, NIC surgery notably elevated NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), gasdermin D N-terminal (GSDMD-N), and IL-1β levels in the spinal cord tissues of rats, suggesting that pyroptosis is activated in the context of NIC. Significantly, downregulation of Sirt1 exacerbated malondialdehyde and reactive oxygen species levels, and simultaneously reduced GSH levels in H2O2-stimulated PC-12 cells, suggesting that Sirt1 deficiency can aggravate oxidative stress. Meanwhile, downregulation of Sirt1 also led to increased levels of NLRP3, ASC, GSDMD-N, and cleaved caspase 1 in H2O2-stimulated PC-12 cells, suggesting that Sirt1 deficiency can further enhance the pyroptosis in these cells. Targeting pyroptosis signaling may yield new insights into the treatment of NIC. The mechanisms mediated by pyroptosis could offer valuable perspectives on the pathogenesis and management of this condition.

Unveiling the nexus: pyroptosis and its crucial implications in liver diseases

Pyroptosis, a distinctive form of programmed cell death orchestrated by gasdermin proteins, manifests as cellular rupture, accompanied by the release of inflammatory factors. While pyroptosis is integral to anti-infection immunity, its aberrant activation has been implicated in tumorigenesis. The liver, as the body's largest metabolic organ, is rich in various enzymes and governs metabolism. It is also the primary site for protein synthesis. Recent years have witnessed the emergence of pyroptosis as a significant player in the pathogenesis of specific liver diseases, exerting a pivotal role in both physiological and pathological processes. A comprehensive exploration of pyroptosis can unveil its contributions to the development and regression of conditions such as hepatitis, cirrhosis, and hepatocellular carcinoma, offering innovative perspectives for clinical prevention and treatment. This review consolidates current knowledge on key molecules involved in cellular pyroptosis and delineates their roles in liver diseases. Furthermore, we discuss the potential of leveraging pyroptosis as a novel or existing anti-cancer strategy.

The liver as a central "hub" of the immune system: pathophysiological implications

The purpose of this review is to describe the immune function of the liver, guiding the reader from the homeostatic tolerogenic status to the aberrant activation demonstrated in chronic liver disease. An extensive description of the pathways behind the inflammatory modulation of the healthy liver will be provided focusing on the complex immune cell network residing within the liver. The limit of tolerance will be presented in the context of organ transplantation, seizing the limits of homeostatic mechanisms that fail in accepting the graft, progressing eventually toward rejection. The triggers and mechanisms behind chronic activation in metabolic liver conditions and viral hepatitis will be discussed. The last part of the review will be dedicated to one of the greatest paradoxes for a tolerogenic organ, developing autoimmunity. Through the description of the three most common autoimmune liver diseases, the autoimmune reaction against hepatocytes and biliary epithelial cells will be dissected.

Quercetin, a natural flavonoid, protects against hepatic ischemia-reperfusion injury via inhibiting Caspase-8/ASC dependent macrophage pyroptosis

INTRODUCTION

Hepatic ischemia-reperfusion injury (IRI) is an inevitable adverse event following liver surgery, leading to liver damage and potential organ failure. Despite advancements, effective interventions for hepatic IRI remain elusive, posing a significant clinical challenge. The innate immune response significantly contributes to the pathogenesis of hepatic IRI by promoting an inflammatory cytotoxic cycle. We have reported that blocking GSDMD-induced pyroptosis in innate immunity cells protected hepatic IRI from inflammatory injury. However, the search for effective pyroptosis inhibitors continues.

OBJECTIVES

This study aims to evaluate whether quercetin, a natural flavonoid, can inhibit GSDMD-induced pyroptosis and mitigate hepatic IRI.

METHODS

We established the hepatic IRI murine model and cellular pyroptosis model to evaluate the efficacy of quercetin.

RESULTS

Quercetin effectively alleviated hepatic IRI-induced tissue necrosis and inflammation. We found that during hepatic IRI, the cleavage of GSDMD occurred in hepatic macrophages, but not in other non-parenchymal cells. Quercetin inhibited the cleavage of GSDMD in macrophages. Moreover, we found that quercetin blocked the ASC assembly to inhibit the formation of NLRP3 inflammasomes and AIM2 inflammasomes, suppressing macrophage pyroptosis. Co-immunoprecipitation experiments confirmed that quercetin inhibited the interaction between ASC and Caspase-8, which is the mechanism of ASC complex and inflammasome formation. Overexpression of Caspase-8 abolished the anti-pyroptosis effect of quercetin in NLRP3 and AIM2 inflammasome signaling. Furthermore, we found that the hepatoprotective activity of quercetin was reduced in myelocytic GSDMD-deficient mice.

CONCLUSION

Our findings suggest that quercetin has beneficial effects on hepatic IRI. Quercetin could attenuate hepatic IRI and target inhibition of macrophage pyroptosis via blocking Caspase-8/ASC interaction. We recommend that quercetin might serve as a targeted approach for the prevention and personalized treatment of hepatic IRI in perioperative patients.

Association of Lifestyle-Induced Weight Loss With Gene Expression in Subcutaneous Adipose Tissue in Metabolic Syndrome

AIMS

Lifestyle-induced weight loss (LIWL) is considered an effective therapy for the treatment of metabolic syndrome (MetS). The role of differentially expressed genes (DEGs) in adipose tissue function and in the success of LIWL in MetS is still unclear. We investigated the effect of 6 months of LIWL on transcriptional regulation in subcutaneous adipose tissue (SAT). Aiming to identify a LIWL-associated "gene signature" in SAT, DEGs were fitted into a linear regression model.

MATERIALS AND METHODS

The study is embedded in a prospective, two-arm, controlled, monocentric, randomized, 6-month interventional trial in individuals with MetS following LIWL. The trial included 43 nonsmoking, nondiabetic men aged 45-55 years with MetS.

RESULTS

In total, we identified 642 DEGs in SAT after 6 months of LIWL. The identified DEGs were validated in two cross-sectional cohorts analyzing SAT from individuals with and without obesity. Gene enrichment analysis of the DEGs revealed the strongest association with cholesterol metabolic processes. Accordingly, DEGs were correlated with the lipid parameters HDL cholesterol, LDL cholesterol, and triglycerides in corresponding serum samples. We identified 3 genes with an AUC of 0.963 (95% CI: 0.906-1.0) associated with a loss of more than 10% of initial body weight that was maintained for at least 12 months after LIWL, namely SUMO3 (Small ubiquitin-related modifier 3), PRKG2 (Protein Kinase CGMP-Dependent 2), and ADAP2 (ArfGAP with Dual PH Domains 2).

CONCLUSION

In summary, we have identified DEGs in SAT after LIWL, which may play an important role in metabolic functions. In particular, altered gene expression in SAT may predict sustained weight loss.

Role of gasdermins in chronic kidney disease

Gasdermins (GSDMs), functioning as membrane perforating proteins, can be activated by canonical inflammasomes, noncanonical inflammasomes, as well as non-inflammasomes, leading to cell pyroptosis and the subsequent release of inflammatory mediators. Increasing evidence has implicated that GSDMs are associated with chronic kidney disease (CKD), including diabetes nephropathy, lupus nephritis, obstructive nephropathy, and crystalline nephropathy. This review centers on the role of GSDMs-mediated pyroptosis in the pathogenesis of CKD, providing novel ideas for enhancing the prognosis and therapeutic strategies of CKD.

Mechanistic insights into gasdermin-mediated pyroptosis

Pyroptosis, a novel mode of inflammatory cell death, is executed by membrane pore-forming gasdermin (GSDM) family members in response to extracellular or intracellular injury cues and is characterized by a ballooning cell morphology, plasma membrane rupture and the release of inflammatory mediators such as interleukin-1β (IL-1β), IL-18 and high mobility group protein B1 (HMGB1). It is a key effector mechanism for host immune defence and surveillance against invading pathogens and aberrant cancerous cells, and contributes to the onset and pathogenesis of inflammatory and autoimmune diseases. Manipulating the pore-forming activity of GSDMs and pyroptosis could lead to novel therapeutic strategies. In this Review, we discuss the current knowledge regarding how GSDM-mediated pyroptosis is initiated, executed and regulated, its roles in physiological and pathological processes, and the crosstalk between different modes of programmed cell death. We also highlight the development of drugs that target pyroptotic pathways for disease treatment.

Nuclear factor erythroid 2-related factor 2 ameliorates disordered glucose and lipid metabolism in liver: Involvement of gasdermin D in regulating pyroptosis

BACKGROUND

The epidemic of metabolic dysfunction-associated fatty liver disease linked to excessive high-fat diet (HFD) consumption has sparked widespread public concern. Nuclear factor erythroid 2-related factor 2 (NRF2) has been reported to improve glucose/lipid metabolism, liver lipid degeneration and alleviate HFD-induced inflammation. However, its pathways and mechanisms of action are not fully understood.

METHODS

To confirm the effect of NRF2 on glucose/lipid metabolism in the liver, Nrf2-/- mice as well as liver-specific Nrf2 knockout mice, and AAV-TBG-Nrf2 were employed. The hyperinsulinemic-euglycemic clamp was utilized to determine the effect of NRF2 on glucose metabolism. To elucidate the effect of NRF2 on pyroptosis, we performed western blots, immunofluorescence, quantitative real-time PCR, and Flow cytometry experiments. Finally, chromatin immunoprecipitation-seq and dual-luciferase reporter assay was used to underscore the transcriptional regulatory effect of NRF2 on Gsdmd.

RESULTS

We found that overexpression of Nrf2 inhibited the expression of inflammatory cytokines and pyroptosis markers, including cle-Caspase1, NLRP3 and the N-terminus of gasdermin D (N-GSDMD) both in vivo and in vitro, while Nrf2 deficiency was the opposite. Specifically, with NRF2 expression up-regulated, GSDMD expression decreased and Gsdmd overexpression partially reversed the effect of Nrf2 overexpression on pro-inflammatory phenotype. Mechanistically, we demonstrate that NRF2 binds to the Gsdmd promoter at the -2110 - 1130 bp site, inhibiting the GSDMD expression and thereby improving glucose/lipid metabolism and liver steatosis.

CONCLUSION

Our data indicate that NRF2 is an effective inhibitor of pyroptosis and has a multi-target effect in the treatment of obesity-related metabolic diseases.

KEY POINTS

MAFLD is associated with increased hepatocytes NRF2 expression. NRF2 alleviates MAFLD by suppressing pyroptosis. NRF2 directly inhibits GSDMD expression to regulate pyroptosis. Targeting the NRF2-pyroptosis (GSDMD) axis offers a potential therapeutic strategy for MAFLD.

Aquaporin-5 facilitates liver regeneration following hepatectomy via ROS/GSDMD pathway

During the proliferative phase of liver regeneration, insufficient regulation of hepatocyte hydrogen peroxide (H2O2) overproduction can result in oxidative stress and hepatocyte death. This study aims to investigate the influence of Aquaporin 5 (Aqp5) on liver regeneration by evaluating its role in reactive oxygen species (ROS) generation and NLRP3-GSDMD-mediated pyroptosis. A 70 % partial hepatectomy (PHx) model was established in Aqp5-/- mice to evaluate the pathological changes in the liver. Reactive oxygen species (ROS) production was assessed using a dichlorodihydrofluorescein diacetate (DCFH-DA) assay. Aqp5 deficiency significantly increased ROS production, the number of TUNEL-positive cells, and disrupted mitochondrial membrane potential in the liver of Aqp5-deficient mice. The impact of Aqp5 on ROS/NLRP3/Gasdermin-D (GSDMD)-mediated pyroptosis was examined through the administration of N-acetyl-L-cysteine (NAC, an ROS scavenger) or disulfiram (DSF, a GSDMD inhibitor). In Aqp5-deficient mice, the regenerative liver exhibited increased expression of NLRP3, enhanced activation of caspase-1 and GSDMD, as well as elevated secretion of IL-1β. Treatment with DSF significantly attenuated GSDMD-mediated pyroptosis triggered by Aqp5 deficiency in the regenerating liver. Furthermore, the administration of NAC to Aqp5-deficient mice resulted in a reduction in the expression levels of NLRP3, the activity levels of caspase-1 and GSDMD, as well as the release of IL-1β. Our findings indicate that the deficiency of Aqp5 facilitates GSDMD activation through the production of ROS. The suppression of ROS or inhibition of GSDMD significantly alleviates the damage and pyroptosis observed in Aqp5-deficient regenerative liver.

NK-cell-elicited gasdermin-D-dependent hepatocyte pyroptosis induces neutrophil extracellular traps that facilitate HBV-related acute-on-chronic liver failure

BACKGROUND AND AIMS

HBV infection is a major etiology of acute-on-chronic liver failure (ACLF). At present, the pattern and regulation of hepatocyte death during HBV-ACLF progression are still undefined. Evaluating the mode of cell death and its inducers will provide new insights for developing therapeutic strategies targeting cell death. In this study, we aimed to elucidate whether and how immune landscapes trigger hepatocyte death and lead to the progression of HBV-related ACLF.

APPROACH AND RESULTS

We identified that pyroptosis represented the main cell death pattern in the liver of patients with HBV-related ACLF. Deficiency of MHC-I in HBV-reactivated hepatocytes activated cytotoxic NK cells, which in turn operated in a perforin/granzyme-dependent manner to trigger GSDMD/caspase-8-dependent pyroptosis of hepatocytes. Neutrophils selectively accumulated in the pyroptotic liver, and HMGB1 derived from the pyroptotic liver constituted an important factor triggering the generation of pathogenic extracellular traps in neutrophils (NETs). Clinically, elevated plasma levels of myeloperoxidase-DNA complexes were a promising prognostic biomarker for HBV-related ACLF. More importantly, targeting GSDMD pyroptosis-HMGB1 release in the liver abrogates NETs that intercept the development of HBV-related ACLF.

CONCLUSIONS

Studying the mechanisms that selectively modulate GSDMD-dependent pyroptosis, as well as its immune landscapes, will provide a novel strategy for restoring the liver function of patients with HBV-related ACLF.

GSDMD-mediated pyroptosis: molecular mechanisms, diseases and therapeutic targets

Pyroptosis is a regulated form of inflammatory cell death in which Gasdermin D (GSDMD) plays a central role as the key effector molecule. GSDMD-mediated pyroptosis is characterized by complex biological features and considerable heterogeneity in its expression, mechanisms, and functional outcomes across various tissues, cell types, and pathological microenvironments. This heterogeneity is particularly pronounced in inflammation-related diseases and tumors. In the context of inflammatory diseases, GSDMD expression is typically upregulated, and its activation in macrophages, neutrophils, T cells, epithelial cells, and mitochondria triggers both pyroptotic and non-pyroptotic pathways, leading to the release of pro-inflammatory cytokines and exacerbation of tissue damage. However, under certain conditions, GSDMD-mediated pyroptosis may also serve a protective immune function. The expression of GSDMD in tumors is regulated in a more complex manner, where it can either promote immune evasion or, in some instances, induce tumor cell death. As our understanding of GSDMD's role continues to progress, there have been advancements in the development of inhibitors targeting GSDMD-mediated pyroptosis; however, these therapeutic interventions remain in the preclinical phase. This review systematically examines the cellular and molecular complexities of GSDMD-mediated pyroptosis, with a particular emphasis on its roles in inflammation-related diseases and cancer. Furthermore, it underscores the substantial therapeutic potential of GSDMD as a target for precision medicine, highlighting its promising clinical applications.

Long-read sequencing of 945 Han individuals identifies structural variants associated with phenotypic diversity and disease susceptibility

Genomic structural variants (SVs) are a major source of genetic diversity in humans. Here, through long-read sequencing of 945 Han Chinese genomes, we identify 111,288 SVs, including 24.56% unreported variants, many with predicted functional importance. By integrating human population-level phenotypic and multi-omics data as well as two humanized mouse models, we demonstrate the causal roles of two SVs: one SV that emerges at the common ancestor of modern humans, Neanderthals, and Denisovans in GSDMD for bone mineral density and one modern-human-specific SV in WWP2 impacting height, weight, fat, craniofacial phenotypes and immunity. Our results suggest that the GSDMD SV could serve as a rapid and cost-effective biomarker for assessing the risk of cisplatin-induced acute kidney injury. The functional conservation from human to mouse and widespread signals of positive natural selection suggest that both SVs likely influence local adaptation, phenotypic diversity, and disease susceptibility across diverse human populations.

Artemether Ameliorates Non-Alcoholic Steatohepatitis by Restraining Cross-Talk Between Lipotoxicity-Induced Hepatic Hepatocytes and Macrophages

Non-alcoholic steatohepatitis (NASH) has no effective treatment drug. Our previous study initially found that artemether (Art) treatment significantly attenuates NSAH by regulating liver lipid metabolism. This study further elucidates new mechanisms of Art in improving liver inflammation and provides evidence for drug repurposing. Herein, we utilized HFHF diet-induced animal model and macrophage models to detect the mechanisms of Art in NASH. We confirmed that Art significantly reduced hepatic steatosis, injury, and fibrosis in a high-fat high-fructose (HFHF) diet-induced animal model. Art significantly suppressed the activation of inflammatory macrophages and secretion of pro-inflammatory cytokine (IL-1β) by reducing serum double-stranded DNA (dsDNA) levels and triggering the AIM2/Caspase-1/GSDMD signaling in vivo. dsDNA-induced Caspase-1 and PI-positive cells pyroptosis, AIM2 inflammasome activation, IL-1β, and IL-18 secretion increase were inhibited by Art in vitro. Furthermore, we found Art effectively suppressed mitochondrial DNA (mtDNA), a typical form of dsDNA, released from free fatty acid (FFA)-stressed hepatocytes, which further inhibited AIM2 inflammasome mediated-pyroptosis through decreasing the cleavage of Caspase-1/GSDMD/IL-1β. Moreover, inhibition of the AIM2 gene partly reversed the inhibitory effect of Art on macrophage pyroptosis. Impaired mitochondrial structure and function were confirmed in FFA-stressed hepatocytes and the HFHF-diet-induced NASH mouse model, which was reversed by Art treatment. The present study provides evidence for Art as a potential anti-pyroptosis therapeutic agent for NASH treatment.

Inhibition of IRE-1α Alleviates Pyroptosis and Metabolic Dysfunction-Associated Steatohepatitis by Suppressing Gasdermin D

OBJECTIVES

Metabolic dysfunction-associated steatohepatitis (MASH) is a significant risk factor for cirrhosis and hepatocellular carcinoma, for which there is currently no effective treatment. This study aimed to investigate the regulatory mechanism between endoplasmic reticulum stress (ER stress) and pyroptosis in the liver under the context of MASH.

METHODS AND RESULTS

Pyroptosis was examined in both in vivo and in vitro ER stress models. The expression levels of nucleotide-binding oligomerisation domain-like receptor protein 3 (NLRP3), gasdermin D (GSDMD), caspase-1, IL-1β, and IL-18 tended to increase, and "ASC specks" colocalised with the swollen ER in living cells. However, in the pyroptotic model, increased ER stress was not observed. Moreover, the overexpression of inositol-requiring enzyme 1α (IRE-1α), one of the main ER stress sensors, led to increases in the levels of NLRP3 and GSDMD. However, after IRE-1α was blocked by chemical inhibitors or siRNAs, pyroptosis was also abrogated. These data showed that ER stress regulated pyroptosis through IRE-1α. Furthermore, the immunoprecipitation results clearly indicated that GSDMD efficiently bound to IRE-1α when ER stress was stimulated. In the MASH model, IRE-1α was specifically inhibited by pharmacological or genetic methods, which improved the pathology of MASH by alleviating ER stress and pyroptosis. In patients with MASH, both ER stress markers and pyroptosis markers including IRE-1α, glucose-regulated protein 78, GSDMD/GSDMD-N, p20, and NLRP3, are highly expressed in the liver.

CONCLUSIONS

This study revealed that ER stress may regulate pyroptosis through IRE-1α-GSDMD pathway, which accelerates the progression of MASH. These findings may offer new insights for the treatment of MASH.

Dual role of pyroptosis in liver diseases: mechanisms, implications, and therapeutic perspectives

Pyroptosis, a form of programmed cell death induced by inflammasome with a mechanism distinct from that of apoptosis, occurs via one of the three pathway types: classical, non-classical, and granzyme A/B-dependent pyroptosis pathways. Pyroptosis is implicated in various diseases, notably exhibiting a dual role in liver diseases. It facilitates the clearance of damaged hepatocytes, preventing secondary injury, and triggers immune responses to eliminate pathogens and damaged cells. Conversely, excessive pyroptosis intensifies inflammatory responses, exacerbates hepatocyte damage and promotes the activation and proliferation of hepatic stellate cells, accelerating liver fibrosis. Furthermore, by sustaining an inflammatory state, impacts the survival and proliferation of cancer cells. This review comprehensively summarizes the dual role of pyroptosis in liver diseases and its therapeutic strategies, offering new theoretical foundations and practical guidance for preventing and treating of liver diseases.

The role and therapeutic targeting of the CCL2/CCR2 signaling axis in inflammatory and fibrotic diseases

CCL2, a pivotal cytokine within the chemokine family, functions by binding to its receptor CCR2. The CCL2/CCR2 signaling pathway plays a crucial role in the development of fibrosis across multiple organ systems by modulating the recruitment and activation of immune cells, which in turn influences the progression of fibrotic diseases in the liver, intestines, pancreas, heart, lungs, kidneys, and other organs. This paper introduces the biological functions of CCL2 and CCR2, highlighting their similarities and differences concerning fibrotic disorders in various organ systems, and reviews recent progress in the diagnosis and treatment of clinical fibrotic diseases linked to the CCL2/CCR2 signaling pathway. Additionally, further in-depth research is needed to explore the clinical significance of the CCL2/CCR2 axis in fibrotic conditions affecting different organs.

10-Hydroxy-2-decenoic acid attenuates nonalcoholic fatty liver disease by activating AMPK-α signaling pathway

Nonalcoholic fatty liver disease (NAFLD) originates from metabolic dysfunctions, is one of the most commonly encountered liver disorders worldwide, characterized by ectopic lipid deposition within hepatocytes, accompanied by hepatocellular injury and necroinflammation. Currently, NAFLD has very few treatment options. Purified from royal jelly, 10-hydroxy-2-decenoic acid (10-HDA) is the primary bioactive ingredient with a series of beneficial effects against various metabolic diseases. Herein, we investigated the effects of 10-HDA in methionine and choline deficiency (MCD) diet induced NAFLD model and free fatty acids (FFAs) induced lipid-laden hepatocyte model and explored the underlying mechanisms. In the mice fed with MCD diet, 10-HDA treatment significantly reduced hepatic steatosis, hepatocellular injury, apoptosis, inflammatory response and fibrosis. In vitro, 10-HDA treatment reduced lipid accumulation and apoptosis in hepatocytes induced by FFAs. Mechanistically, 10-HDA therapy restored AMPK-α phosphorylation, leading to the phosphorylation and inactivation acetyl-CoA carboxylase (ACC). Consequently, this increased the expression of carnitine palmitoyl transferase 1α(CPT1α), and peroxisome proliferators-activated receptors α (PPARα), and lowered the expression of cleavage forms of sterol regulatory element binding protein-1 (SREBP-1) and fatty acid synthetase (FASN). Furthermore, pretreating the cells with the AMPK-α inhibitor, compound C, greatly eliminated these beneficial effects of 10-HDA. Additionally, molecular docking analysis indicated that 10-HDA bound the domain of AMPK-α1 subunit. Based on these findings, 10-HDA suppresses hepatic lipogenesis via AMPK-α-dependent suppression of the ACC pathway, thus inhibiting hepatocellular injury, apoptosis, inflammatory response and fibrosis. 10-HDA may represent a promising candidate drug for the treatment of NAFLD.

PD-1+CD8+ T Cell-Mediated Hepatocyte Pyroptosis Promotes Progression of Murine Autoimmune Liver Disease

The specific mechanisms underlying effector pathways in autoimmune liver disease remain enigmatic and therefore constructing appropriate murine models to investigate disease pathogenesis becomes critical. A spontaneous severe murine model of autoimmune liver disease has been previously established in dnTGFβRII Aire-/- mice, exhibiting disease phenotypes that resemble both human primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH). The data suggests that auto-reactive liver-specific CD8+ T cells are the primary pathogenic cells in liver injury. In this study, these data are advanced through the use of both single-cell sequencing and extensive in vitro analysis. The results identify a specific expanded pathogenic subset of PD-1+CD8+ T cells in the liver, exhibiting strong functional activity and cytotoxicity against target cells. Depletion of PD-1+CD8+ T cells using CAR-T cells effectively alleviates the disease. GSDMD-mediated pyroptosis is found to be aberrantly activated in the livers of model mice, and treatment with a GSDMD-specific inhibitor significantly inhibits disease progression. In vitro experiments reveal that PD-1+CD8+ T cells can induce the pyroptosis of hepatocytes through elevated production of granzyme B and perforin-1. These results provide a novel explanation for the cytotoxic activity of pathogenic liver PD-1+CD8+ T cells in autoimmune liver diseases and offer potential therapeutic targets.

Gasdermin D deletion prevents liver injury and exacerbates extrahepatic damage in a murine model of alcohol-induced ACLF

Background

Gasdermin D (GSDM-D), a key executor of pyroptosis, is increased in various liver diseases and contributes to disease progression. Alcohol induces inflammasome activation and cell death, which are both linked to GSDM-D activation. However, its role in alcohol-induced acute-on-chronic liver failure (ACLF) remains unclear.

Methods

ACLF was induced in GSDM-D-deficient or wild-type (WT) mice by 28-day bile duct ligation surgery plus a single 5 g/kg alcohol binge leading to acute decompensation. Nine hours after the alcohol binge, blood, liver, kidney and cerebellum specimens were collected for analysis.

Results

Active GSDM-D was significantly increased in humans and mice ACLF livers compared with both healthy controls and cirrhotic livers. GSDM-D-deficient mice with ACLF showed decreased inflammation, neutrophil infiltration and fibrosis in the liver, together with a reduction in pyroptotic, apoptotic and necroptotic death, compared with WT ACLF mice. Notably, GSDM-D-deficient mice also showed decreased liver regeneration and hepatocyte function. This was associated with an increase in senescence and expression of stem-like/cholangiocyte markers in the liver. Interestingly, in the kidney, GSDM-D-deficient mice showed an increase in histopathological damage score, decreased function and increased expression of necroptosis-related genes. In the cerebellum, GSDM-D deficiency increased the expression of neuroinflammation markers, astrocyte activation and apoptosis-related genes.

Conclusion

Our data indicate that GSDM-D deficiency has organ-specific effects in ACLF. While it reduces inflammation, neutrophil activation, cell death and fibrosis in the liver, GSDM-D deficiency impairs the synthetic function and increases senescence in hepatocytes. GSDM-D deficiency also increases kidney injury and neuroinflammation in ACLF.

Identification of two repurposed drugs targeting GSDMD oligomerization interface I to block pyroptosis

As an executor of pyroptosis, gasdermin D (GSDMD) plays a critical role in inflammatory diseases and cancer. Thus, GSDMD is currently being widely explored as a drug target. Existing inhibitors targeting GSDMD, such as necrosulfonamide, disulfiram, and fumarate, primarily prevent pyroptosis by modifying human/mouse C191/C192 in the N-terminal fragment of GSDMD. However, cysteine modification can prevent the function of important proteins or enzymes, thereby leading to adverse reactions. Here, we chose an alternative key intervention site for GSDMD activation, which is located at the oligomerization interface I of its pore-forming structure. Through high-throughput virtual and experimental screening and in combination with efficacy and pharmacological validation, we have identified two safe, specific "repurposed drugs" that potently suppress GSDMD-mediated pyroptosis. Moreover, the candidates exhibited synergistic therapeutic effects of "1 + 1>2" in murine sepsis and tumorigenesis models. These recently identified GSDMD inhibitors hold great promise for clinical translation in the development of anti-inflammatory and anti-cancer immunotherapies.

Impacts and potential mechanisms of fine particulate matter (PM2.5) on male testosterone biosynthesis disruption

Exposure to PM2.5 is the most significant air pollutant for health risk. The testosterone level in male is vulnerable to environmental toxicants. In the past, researchers focused more attention on the impacts of PM2.5 on respiratory system, cardiovascular system, and nervous system, and few researchers focused attention on the reproductive system. Recent studies have reported that PM2.5 involved in male testosterone biosynthesis disruption, which is closely associated with male reproductive health. However, the underlying mechanisms by which PM2.5 causes testosterone biosynthesis disruption are still not clear. To better understand its potential mechanisms, we based on the existing scientific publications to critically and comprehensively reviewed the role and potential mechanisms of PM2.5 that are participated in testosterone biosynthesis in male. In this review, we summarized the potential mechanisms of PM2.5 triggering the change of testosterone level in male, which involve in oxidative stress, inflammatory response, ferroptosis, pyroptosis, autophagy and mitophagy, microRNAs (miRNAs), endoplasmic reticulum (ER) stress, and N6-methyladenosine (m6A) modification. It will provide new suggestions and ideas for prevention and treatment of testosterone biosynthesis disruption caused by PM2.5 for future research.

Mechanisms and Therapeutic Potential of Multiple Forms of Cell Death in Myocardial Ischemia-Reperfusion Injury

Programmed cell death, especially programmed necrosis such as necroptosis, ferroptosis, and pyroptosis, has attracted significant attention recently. Traditionally, necrosis was thought to occur accidentally without signaling pathways, but recent discoveries have revealed that molecular pathways regulate certain forms of necrosis, similar to apoptosis. Accumulating evidence indicates that programmed necrosis is involved in the development of various diseases, including myocardial ischemia-reperfusion injury (MIRI). MIRI occurs when blood flow and oxygen return to an ischemic area, causing excessive production of reactive oxygen species. While this reperfusion is critical for treating myocardial infarction, it inevitably causes cellular damage via oxidative stress. Furthermore, this cellular damage triggers multiple forms of cardiomyocyte death, which is the primary cause of inflammation, cardiac tissue remodeling, and ensuing heart failure. Therefore, understanding the molecular mechanisms of various forms of cell death in MIRI is crucial for therapeutic target discovery. Developing therapeutic strategies to inhibit multiple cell death pathways simultaneously could provide effective protection against MIRI. In this paper, we review the fundamental molecular pathways and MIRI-specific mechanisms of apoptosis, necroptosis, ferroptosis, and pyroptosis. Additionally, we suggest that the simultaneous suppression of multiple cell death pathways could be an effective therapy and identify potential therapeutic targets for implementing this strategy.

The Circadian Clock Gene Bmal1 Regulates Microglial Pyroptosis After Spinal Cord Injury via NF-κB/MMP9

BACKGROUND

The treatment of spinal cord injury (SCI) is usually ineffective, because neuroinflammatory secondary injury is an important cause of the continuous development of spinal cord injury, and microglial pyroptosis is an important step of neuroinflammation. Recently, Bmal1, a core component of circadian clock genes (CCGs), has been shown to play a regulatory role in various tissues and cells. However, it is still unclear whether Bmal1 regulates microglial pyroptosis after SCI.

METHODS

In this study, we established an in vivo mouse model of SCI using Bmal1 knockout (KO) mice and wild-type (WT) mice, and lipopolysaccharide (LPS)-induced pyroptosis in BV2 cells as an in vitro model. A series of molecular and histological methods were used to detect the level of pyroptosis and explore the regulatory mechanism in vivo and in vitro respectively.

RESULTS

Both in vitro and in vivo results showed that Bmal1 inhibited NLRP3 inflammasome activation and microglial pyroptosis after SCI. Further analysis showed that Bmal1 inhibited pyroptosis-related proteins (NLRP3, Caspase-1, ASC, GSDMD-N) and reduced the release of IL-18 and IL-1β by inhibiting the NF-κB /MMP9 pathway. It was important that NF-κB was identified as a transcription factor that promotes the expression of MMP9, which in turn regulates microglial pyroptosis after SCI.

CONCLUSIONS

Our study initially identified that Bmal1 regulates the NF-κB /MMP9 pathway to reduce microglial pyroptosis and thereby reduce secondary spinal cord injury, providing a new promising therapeutic target for SCI.

miR-103-3p attenuates liver injury with severe acute pancreatitis by inhibiting pyroptosis through miR-103-3p/NLRP1 axis

BACKGROUND

Severe acute pancreatitis (SAP) is a common digestive system disorder in clinical practice, and it is often associated with liver damage in patients with severe acute pancreatitis. Several studies have indicated that pyroptosis plays a role in liver damage following severe acute pancreatitis (SAP). However, the precise mechanisms remain unclear. This study aims to elucidate the association and specific mechanisms between liver injury following SAP and pyroptosis, providing theoretical support for research on SAP-induced liver injury.

METHODS

A rat model of SAP with concomitant liver injury was successfully established. The expression levels of miR-103-3p across different liver tissue groups were quantified using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Bioinformatic analyses and dual-luciferase reporter assays confirmed that NLRP1 is a direct target of miR-103-3p. In vivo assessments of miR-103-3p levels were performed, and the extent of cell pyroptosis during liver injury post-SAP was evaluated through western blotting, qRT-PCR, scanning electron microscopy, histopathology, immunofluorescence, and immunohistochemistry. The role of miR-103-3p in regulating NLRP1-mediated pyroptosis and its impact on SAP-induced liver injury were validated.

RESULTS

This study reports that following SAP-induced liver injury, the expression of miR-103-3p in liver tissue was significantly decreased, and cell pyroptosis was involved in the process of liver injury. Experimental validation indicated that NLRP1 was a downstream target of miR-103-3p. Overexpression of miR-103-3p in vitro significantly alleviated the severity of liver injury following SAP, while simultaneously inhibiting cell pyroptosis.

CONCLUSION

These findings indicate that pyroptosis may be linked to SAP-induced liver injury and that miR-103-3p mitigates hepatocyte pyroptosis by reducing liver injury through the suppression of NLRP1 expression.

Exosomes derived from diabetic microenvironment-preconditioned mesenchymal stem cells ameliorate nonalcoholic fatty liver disease and inhibit pyroptosis of hepatocytes

AIM

Pyroptosis, a type of programmed cell death, is a key mechanism underlying non-alcoholic fatty liver disease (NAFLD). Mesenchymal stem cell (MSC)-derived exosomes (MSC-Exos) have the potential to ameliorate NAFLD, an effect that is enhanced by curcumin preconditioning. We previously reported that diabetic microenvironment preconditioning enhances the secretion capacity and anti-inflammatory activity of MSCs. Therefore, we hypothesized that MSC-Exos would inhibit hepatocyte pyroptosis and thereby ameliorate NAFLD, and that diabetic microenvironment preconditioning would enhance these effects.

METHODS

MSCs were preconditioned in a diabetic microenvironment (pMSCs). MSC-Exos and pMSC-Exos collected from MSCs or pMSCs were applied to methionine- and choline-deficient (MCD)-induced NAFLD mice and in vitro models involving induction with lipopolysaccharide or palmitic acid to mimic hepatic steatosis and injury. MCC950 treatment was used as a positive control. We analyzed the characteristics of NAFLD and pyroptosis markers. Protein profiles of MSC-Exos and pMSC-Exos were evaluated by label-free quantitative proteomics.

RESULTS

In vivo, MSC-Exos partially attenuated inflammation and fibrosis, but not lipid deposition and NAFLD progression in the livers of NAFLD mice. pMSC-Exos significantly improved lipid metabolism, hepatic steatosis, inflammation, and fibrosis but also retarded the progression of NAFLD. Pyroptosis was upregulated in the liver of NAFLD mice. MSC-Exos and pMSC-Exos inhibited pyroptosis, and the effect of the latter was greater than that of the former. In vitro, MSC-Exos and pMSC-Exos ameliorated hepatocyte steatosis, lipid metabolism disorder, and inflammation, and pMSC-Exos exerted a greater inhibitory effect on hepatocyte pyroptosis than MSC-Exos did, which were remitted after inhibition of peroxiredoxin-1 (PRDX-1).

CONCLUSION

MSC-Exos ameliorated NAFLD and inhibited hepatocyte pyroptosis by downregulating the NLRP3/Caspase-1/GSDMD pathway, effects enhanced by pMSC-Exos, partly due to PRDX-1 upregulation.

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.

Mechanism of epigallocatechin gallate in treating non-alcoholic fatty liver disease: Insights from network pharmacology and experimental validation

To explore the therapeutic effects along with the molecular mechanisms of epigallocatechin gallate (EGCG) in non-alcoholic fatty liver disease (NAFLD) treatment using network pharmacology as well as animal experiments. Firstly, the Traditional Chinese Medicine (TCM) Systems Pharmacology Database was searched to identify the potential targets of EGCG. The DisGeNET Database was used to screen the potential targets of NAFLD. The GeneCards Database was searched to identify related genes involved in pyroptosis. Subsequently, the intersecting genes of EGCG targeting pyroptosis to regulate NAFLD were obtained using a Venn diagram. Simultaneously, the aforementioned intersecting genes were used to construct a drug-disease target protein-protein interaction (PPI) network. The DAVID database was adopted for Gene Ontology (GO) as well as Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The main pathway-target network was determined. Next, the potential mechanism of EGCG targeting pyroptosis to regulate NAFLD was investigated and validated through in vivo experiments. 626 potential targets of EGCG, 447 target genes of NAFLD, and 568 potential targets of pyroptosis were identified. The number of common targets between EGCG, NAFLD, and pyroptosis was 266. GO biological process items and 92 KEGG pathways were determined based on the analysis results. Animal experiments demonstrated that EGCG could ameliorate body weight, glucolipid metabolism, steatosis, and liver injury, enhance insulin sensitivity, and improve glucose tolerance in NAFLD mice through the classical pathway of pyroptosis. EGCG could effectively treat NAFLD through multiple targets and pathways. It was concluded that EGCG ameliorates hepatocyte steatosis, pyroptosis, dyslipidemia, and inflammation in NAFLD mice fed a high-fat diet (HFD), and the protective mechanism could be associated with the NLRP3-Caspase-1-GSDMD classical pyroptosis pathway.

Perinatal exposure to PBEB aggravates liver injury via macrophage-derived TWEAK in male adult offspring mice under western diet

Liver injury and inflammation are the most commonly observed adverse outcomes following exposure to penta-brominated flame retardants (penta-BFRs). However, the role of inflammation in the development of liver injury in their alternatives has not yet been explored. Our study aimed to investigate the effects and the underlying mechanism of perinatal exposure to pentabromoethylbenzene (PBEB), a penta-BDE alternative, on liver injury in adult offspring mice under both chow and western diet in later life. Results showed that perinatal exposure to PBEB at 0.2 mg/kg or above led to liver injury in male offspring upon challenge with a western diet, but not in females. Utilizing the Olink immunology panel, our study specifically revealed an upregulation of tumor necrosis factor-related weak inducer of apoptosis (TWEAK) within the livers of male mice. This cytokine was further demonstrated to derive from the secretion by infiltrating macrophages in livers both in vivo and in vitro, which facilitated a shift towards M1 macrophage polarization. TWEAK further activated the hepatic NF-κB and NLRP3 inflammasome pathways, subsequently leading to hepatic pyroptosis in male mice of maternal PBEB exposure. Inhibition of TWEAK signaling mitigated macrophage polarization and inflammasome induction in a co-culture system of macrophages and liver cells. Our findings revealed that perinatal exposure to PBEB precipitated liver injury, partially through an inflammatory pathway mediated by macrophage-derived TWEAK, in male mice offspring under western diet.

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.

Liver Transplantation: A Test of Cellular Physiology, Preservation, and Injury

Liver transplantation has evolved into a mature clinical field, but scarcity of usable organs poses a unique challenge. Expanding the donor pool requires novel approaches for protecting hepatic physiology and cellular homeostasis. Here we define hepatocellular injury during transplantation, with an emphasis on modifiable cell death pathways as future therapeutics.

GSDME promotes MASLD by regulating pyroptosis, Drp1 citrullination-dependent mitochondrial dynamic, and energy balance in intestine and liver

Dysregulated metabolism, cell death, and inflammation contribute to the development of metabolic dysfunction-associated steatohepatitis (MASH). Pyroptosis, a recently identified form of programmed cell death, is closely linked to inflammation. However, the precise role of pyroptosis, particularly gasdermin-E (GSDME), in MASH development remains unknown. In this study, we observed GSDME cleavage and GSDME-associated interleukin-1β (IL-1β)/IL-18 induction in liver tissues of MASH patients and MASH mouse models induced by a choline-deficient high-fat diet (CDHFD) or a high-fat/high-cholesterol diet (HFHC). Compared with wild-type mice, global GSDME knockout mice exhibited reduced liver steatosis, steatohepatitis, fibrosis, endoplasmic reticulum stress, lipotoxicity and mitochondrial dysfunction in CDHFD- or HFHC-induced MASH models. Moreover, GSDME knockout resulted in increased energy expenditure, inhibited intestinal nutrient absorption, and reduced body weight. In the mice with GSDME deficiency, reintroduction of GSDME in myeloid cells-rather than hepatocytes-mimicked the MASH pathologies and metabolic dysfunctions, as well as the changes in the formation of neutrophil extracellular traps and hepatic macrophage/monocyte subclusters. These subclusters included shifts in Tim4+ or CD163+ resident Kupffer cells, Ly6Chi pro-inflammatory monocytes, and Ly6CloCCR2loCX3CR1hi patrolling monocytes. Integrated analyses of RNA sequencing and quantitative proteomics revealed a significant GSDME-dependent reduction in citrullination at the arginine-114 (R114) site of dynamin-related protein 1 (Drp1) during MASH. Mutation of Drp1 at R114 reduced its stability, impaired its ability to redistribute to mitochondria and regulate mitophagy, and ultimately promoted its degradation under MASH stress. GSDME deficiency reversed the de-citrullination of Drp1R114, preserved Drp1 stability, and enhanced mitochondrial function. Our study highlights the role of GSDME in promoting MASH through regulating pyroptosis, Drp1 citrullination-dependent mitochondrial function, and energy balance in the intestine and liver, and suggests that GSDME may be a potential therapeutic target for managing MASH.

The regulation of pyroptosis by post-translational modifications: molecular mechanisms and therapeutic targets

Pyroptosis, a type of programmed cell death mediated by gasdermin family proteins, releases a large amount of immune stimulatory substances, which further contribute to inflammation and elicit an adaptive immune response against tumours and pathogens. And it occurs through multiple pathways that involve the activation of specific caspases and the cleavage of gasdermins. Post-translational modifications (PTMs) could influence the chemical properties of the modified residues and neighbouring regions, ultimately affecting the activity, stability, and functions of proteins to regulate pyroptosis. Many studies have been conducted to explore the influence of PTMs on the regulation of pyroptosis. In this review, we provide a comprehensive summary of different types of PTMs that influence pyroptosis, along with their corresponding modifying enzymes. Moreover, it elaborates on the specific contributions of different PTMs to pyroptosis and delves into how the regulation of these modifications can be leveraged for therapeutic interventions in cancer and inflammatory diseases.

A preliminary study of T-2 toxin that cause liver injury in rats via the NF-kB and NLRP3-mediated pyroptosis pathway

T-2 toxin is recognized as the most potent and prevalent secondary metabolite among monotrichous mycotoxins produced by Fusarium species. Multiple studies have substantiated the hepatotoxic effects of T-2 toxin. This study aimed to investigate whether NF-κB and NLRP3-mediated pyroptosis is involved in the underlying mechanism of T-2 toxin hepatotoxicity. We designed three groups of rat models, blank control; solvent control and T-2 toxin (0.2 mg/kg body weight/day), which were euthanized at week 8 after gavage staining of the toxin. Through HE staining and biochemical indicators associated with liver injury, we observed that T-2 toxin induced liver damage in rats. By Western blot analysis and qRT-PCR, we found that the expression levels of pyroptosis-related genes and proteins were significantly higher in the T-2 toxin group. In addition, we also found a significant increase in the expression of p-NF-κB protein, an upstream regulator of NLRP3. In conclusion, NF-κB and NLRP3-mediated pyroptosis may be involved in the mechanism of hepatotoxic action of T-2 toxin, which provides a new perspective.

Apoptosis, autophagy, ferroptosis, and pyroptosis in cisplatin-induced ototoxicity and protective agents

Cisplatin is widely used to treat various solid tumors. However, its toxicity to normal tissues limits its clinical application, particularly due to its ototoxic effects, which can result in hearing loss in patients undergoing chemotherapy. While significant progress has been made in preclinical studies to elucidate the cellular and molecular mechanisms underlying cisplatin-induced ototoxicity (CIO), the precise mechanisms remain unclear. Moreover, the optimal protective agent for preventing or mitigating cisplatin-induced ototoxicity has yet to be identified. This review summarizes the current understanding of the roles of apoptosis, autophagy, ferroptosis, pyroptosis, and protective agents in cisplatin-induced ototoxicity. A deeper understanding of these cell death mechanisms in the inner ear, along with the protective agents, could facilitate the translation of these agents into clinical therapeutics, help identify new therapeutic targets, and provide novel strategies for cisplatin-based cancer treatment.