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Objective(s): The expression of pro-inflammatory substances is closely related to various diseases. Genistein (GEN), a soy isoflavone, has been proven to inhibit the production of pro-inflammatory substances in macrophages. This study aimed to determine whether GEN exerts its inhibitory effect on the expression of pro-inflammatory substances by suppressing the release of these substances via attenuating pyroptotic cell lysis. Materials and Methods: Mice were treated with lipopolysaccharide (LPS) and GEN. J774A.1 cells were treated with LPS, adenosine triphosphate (ATP), and GEN. The expression of pro-inflammatory cytokines and high mobility group box 1 (HMGB1) was measured by qRT-PCR and ELISA. The activation of caspase-1 (CASP1) and cleavage of gasdermin D (GSDMD) were determined by Western blot assay. Lactic dehydrogenase (LDH) assay and CCK8 assay were performed to determine the integrity of the cell membrane and cell viability. The concentration of intracellular potassium (K+) and the production of reactive oxygen species (ROS) were determined by the colorimetric method and flow cytometry, respectively. Results: GEN inhibited the production of IL-1 β and HMGB1 in LPS-challenged mice and LPS+ATP-treated mouse macrophages by inhibiting GSDMD-mediated pyroptotic cell lysis. Mechanistically, GEN could prevent the loss of intracellular K+ and the production of ROS caused by LPS+ATP treatment, thereby inhibiting the activation of CASP1. The pathological significance of the release of HMGB1 could be partially attributed to its ability to induce cell apoptosis. Conclusion: GEN inhibits CASP1/GSDMD-mediated pyroptotic cell lysis and the following release of pro-inflammatory substances by suppressing K+ loss and ROS production of macrophages. [ABSTRACT FROM AUTHOR]

Summary Epilepsy is a brain disorder characterized by recurrent seizures, which are brief episodes of abnormal electrical activity in the brain and involuntary movement that can lead to physical injury and loss of consciousness. Seizures are canonically accompanied by increased inflammatory cytokine production that promotes neuroinflammation, brain pathology, and seizure propagation. Understanding the source of pro‐inflammatory cytokines which promote seizure pathogenesis could be a gateway to precision epilepsy drug design. This review discusses the inflammasome in epilepsy including its role in seizure propagation and negative impacts on brain health. The inflammasome is a multiprotein complex that coordinates IL‐1β and IL‐18 production in response to tissue damage, cellular stress, and infection. Clinical evidence for inflammasome signaling in epileptogenesis is reviewed followed by a discussion of emerging strategies to modulate inflammasome activity in epilepsy. [ABSTRACT FROM AUTHOR]

Summary Inflammasomes are multi‐protein complexes that assemble within the cytoplasm of mammalian cells in response to pathogen‐associated molecular patterns (PAMPs) or damage‐associated molecular patterns (DAMPs), driving the secretion of the pro‐inflammatory cytokines IL‐1β and IL‐18, and pyroptosis. The best‐characterized inflammasome complexes are the NLRP3, NAIP‐NLRC4, NLRP1, AIM2, and Pyrin canonical caspase‐1‐containing inflammasomes, and the caspase‐11 non‐canonical inflammasome. Newer inflammasome sensor proteins have been identified, including NLRP6, NLRP7, NLRP9, NLRP10, NLRP11, NLRP12, CARD8, and MxA. These inflammasome sensors can sense PAMPs from bacteria, viruses and protozoa, or DAMPs in the form of mitochondrial damage, ROS, stress and heme. The mechanisms of action, physiological relevance, consequences in human diseases, and avenues for therapeutic intervention for these novel inflammasomes are beginning to be realized. Here, we discuss these emerging inflammasome complexes and their putative activation mechanisms, molecular and signaling pathways, and physiological roles in health and disease. [ABSTRACT FROM AUTHOR]

Xiaoxi Fan,1,2,&ast; Wenli Zhang,2,3,&ast; Ruihan Zheng,1 Yucong Zhang,1 Xianhui Lai,4 Jibo Han,5 Zimin Fang,1 Bingjiang Han,5 Weijian Huang,1 Bozhi Ye,1,2 Shanshan Dai1,6 1The Key Laboratory of Cardiovascular Disease of Wenzhou, Department of Cardiology, the First Affiliated Hospital of Wenzhou Medical University, Zhejiang, People’s Republic of China; 2The Key Laboratory of Clinical Laboratory Diagnosis and Translational Research of Zhejiang Province, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, People’s Republic of China; 3Department of Cardiovascular Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China; 4Department of Cardiology, Yuhuan County People’s Hospital of Zhejiang Province, Taizhou, People’s Republic of China; 5Department of Cardiology, the Second Affiliated Hospital of Jiaxing University, Jiaxing, Zhejiang, People’s Republic of China; 6The Key Laboratory of Emergency and Disaster Medicine of Wenzhou, Department of Emergency, the First Affiliated Hospital of Wenzhou Medical University, Zhejiang, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Shanshan Dai; Bozhi Ye, Email shanshandai137@163.com; fredye2012@163.comAim: Hypertensive nephropathy is a common complication of hypertension. However, no effective measures are currently available to prevent the progression of renal insufficiency. Gasdermin D (GSDMD) is a crucial mediator of pyroptosis that induces an excessive inflammatory response. In the present study, we aimed to determine the effect of GSDMD on the pathogenesis of hypertensive nephropathy, which may provide new insights into the treatment of hypertensive nephropathy.Methods: C57BL/6 (wild-type, WT) and Gsdmd knockout (Gsdmd−/−) mice were subcutaneously infused with angiotensin II (Ang II) via osmotic mini-pumps to establish a hypertensive renal injury model. Recombinant adeno-associated virus serotype 9 (AAV9) carrying GSDMD cDNA was used to overexpress GSDMD. Renal function biomarkers, histopathological changes, and inflammation and fibrosis indices were assessed. Transcriptome sequencing (RNA-seq) and cleavage under targets and mentation (CUT & Tag) experiments were performed to identify the downstream pathogenic mechanisms of GSDMD in hypertensive nephropathy.Results: GSDMD was activated in the kidneys of mice induced by Ang II (P < 0.001). This activation was primarily observed in the renal tubular epithelial cells (P < 0.0001). GSDMD deficiency attenuated renal injury and fibrosis induced by Ang II (P < 0.0001), whereas Gsdmd overexpression promoted renal injury and fibrosis (P < 0.01). Mechanistically, GSDMD increased Ang II–induced GATA binding protein 2 (GATA2) transcription factor expression (P < 0.01). GATA2 also bound to the aquaporin 4 (Aqp4) promoter sequence and facilitated Aqp4 transcription (P < 0.001), leading to renal injury and fibrosis. Moreover, treatment with GI-Y1, an inhibitor of GSDMD, alleviated Ang II–induced renal injury and fibrosis (P < 0.01).Conclusion: GSDMD plays an important role in the development of hypertensive nephropathy. Targeting GSDMD may be a therapeutic strategy for the treatment of hypertensive nephropathy. Keywords: gasdermin D, hypertensive nephropathy, pyroptosis, angiotensin II, aquaporin 4, GATA binding protein 2

Inflammatory diseases compromise a clinically common and diverse group of conditions, causing detrimental effects on body functions. Gasdermins (GSDM) are pore-forming proteins, playing pivotal roles in modulating inflammation. Belonging to the GSDM family, gasdermin D (GSDMD) actively mediates the pathogenesis of inflammatory diseases by mechanistically regulating different forms of cell death, particularly pyroptosis, and cytokine release, in an inflammasome-dependent manner. Aberrant activation of GSDMD in different types of cells, such as immune cells, cardiovascular cells, pancreatic cells and hepatocytes, critically contributes to the persistent inflammation in different tissues and organs. The contributory role of GSDMD has been implicated in diabetes mellitus, liver diseases, cardiovascular diseases, neurodegenerative diseases, and inflammatory bowel disease (IBD). Clinically, alterations in GSDMD levels are potentially indicative to the occurrence and severity of diseases. GSDMD inhibition might represent an attractive therapeutic direction to counteract the progression of inflammatory diseases, whereas a number of GSDMD inhibitors have been shown to restrain GSDMD-mediated pyroptosis through different mechanisms. This review discusses the current understanding and future perspectives on the role of GSDMD in the development of inflammatory diseases, as well as the clinical insights of GSDMD alterations, and therapeutic potential of GSDMD inhibitors against inflammatory diseases. Further investigation on the comprehensive role of GSDM shall deepen our understanding towards inflammation, opening up more diagnostic and therapeutic opportunities against inflammatory diseases. [ABSTRACT FROM AUTHOR]

Inflammation plays a pivotal role in cancer development, with chronic inflammation promoting tumor progression and treatment resistance, whereas acute inflammatory responses contribute to protective anti-tumor immunity. Gasdermin D (GSDMD) mediates the release of pro-inflammatory cytokines such as IL-1b. While the release of IL-1b is directly linked to the progression of several types of cancers, the role of GSDMD in cancer is less clear. In this study, we show that GSDMD expression is upregulated in human breast, kidney, liver, and prostate cancer. Higher GSDMD expression correlated with increased survival in primary breast invasive carcinoma (BRCA), but not in liver hepatocellular carcinoma (LIHC). In BRCA, but not in LIHC, high GSDMD expression correlated with a myeloid cell signature associated with improved prognosis. To further investigate the role of GSDMD in anticancer immunity, we induced breast cancer and hepatoma tumors in GSDMD-deficient mice. Contrary to our expectations, GSDMD deficiency had no effect on tumor growth, immune cell infiltration, or cytokine expression in the tumor microenvironment, except for Cxcl10 upregulation in hepatoma tumors. In vitro and in vivo innate immune activation with TLR ligands, that prime inflammatory responses, revealed no significant difference between GSDMD-deficient and wild-type mice. These results suggest that the impact of GSDMD on anticancer immunity is dependent on the tumor type. They underscore the complex role ofinflammatory pathways in cancer, emphasizing the need for further exploration into the multifaceted effects of GSDMD in various tumor microenvironments. As several pharmacological modulators of GSDMD are available, this may lead to novel strategies for combination therapy in cancer. [ABSTRACT FROM AUTHOR]

The innate immune system serves as the first line of defense against β-coronaviruses (β-CoVs), a family of viruses that includes SARS-CoV-2. Viral sensing via pattern recognition receptors triggers inflammation and cell death, which are essential components of the innate immune response that facilitate viral clearance. However, excessive activation of the innate immune system and inflammatory cell death can result in uncontrolled release of proinflammatory cytokines, resulting in cytokine storm and pathology. PANoptosis, innate immune, inflammatory cell death initiated by innate immune sensors and driven by caspases and RIPKs through PANoptosome complexes, has been implicated in the pathology of viral infections. Therefore, understanding the molecular mechanisms regulating PANoptosis in response to β-CoV infection is critical for identifying new therapeutic targets that can mitigate disease severity. In the current study, we analyzed findings from a cell death-based CRISPR screen with archetypal β-CoV mouse hepatitis virus (MHV) as the trigger to characterize host molecules required for inflammatory cell death. As a result, we identified SMARCA4, a chromatin regulator, as a putative host factor required for PANoptosis in response to MHV. Furthermore, we observed that gRNA-mediated deletion of Smarca4 inhibited MHV-induced PANoptotic cell death in macrophages. These findings have potential translational and clinical implications for the advancement of treatment strategies for β-CoVs and other infections. [ABSTRACT FROM AUTHOR]

Gasdermin D (GSDMD)-mediated pyroptotic cell death drives inflammatory cytokine release and downstream immune responses upon inflammasome activation, which play important roles in host defense and inflammatory disorders. Upon activation by proteases, the GSDMD N-terminal domain (NTD) undergoes oligomerization and membrane translocation in the presence of lipids to assemble pores. Despite intensive studies, the molecular events underlying the transition of GSDMD from an autoinhibited soluble form to an oligomeric pore form inserted into the membrane remain incompletely understood. Previous work characterized S-palmitoylation for gasdermins from bacteria, fungi, invertebrates, as well as mammalian gasdermin E (GSDME). Here, we report that a conserved residue Cys191 in human GSDMD was S-palmitoylated, which promoted GSDMD-mediated pyroptosis and cytokine release. Mutation of Cys191 or treatment with palmitoyltransferase inhibitors cyano-myracrylamide (CMA) or 2-bromopalmitate (2BP) suppressed GSDMD palmitoylation, its localization to the membrane and dampened pyroptosis or IL-1β secretion. Furthermore, Gsdmd-dependent inflammatory responses were alleviated by inhibition of palmitoylation in vivo. By contrast, coexpression of GSDMD with palmitoyltransferases enhanced pyroptotic cell death, while introduction of exogenous palmitoylation sequences fully restored pyroptotic activities to the C191A mutant, suggesting that palmitoylation-mediated membrane localization may be distinct from other molecular events such as GSDMD conformational change during pore assembly. Collectively, our study suggests that S-palmitoylation may be a shared regulatory mechanism for GSDMD and other gasdermins, which points to potential avenues for therapeutically targeting S-palmitoylation of gasdermins in inflammatory disorders. [ABSTRACT FROM AUTHOR]

Abstract Gasdermin D (GSDMD) is emerging as an important player in autoimmune diseases, but its exact role in lupus nephritis (LN) remains controversial. Here, we identified markedly elevated GSDMD in human and mouse LN kidneys, predominantly in CD11b+ myeloid cells. Global or myeloid-conditional deletion of GSDMD was shown to exacerbate systemic autoimmunity and renal injury in lupus mice with both chronic graft-versus-host (cGVH) disease and nephrotoxic serum (NTS) nephritis. Interestingly, RNA sequencing and flow cytometry revealed that myeloid GSDMD deficiency enhanced granulopoiesis at the hematopoietic sites in LN mice, exhibiting remarkable enrichment of neutrophil-related genes, significant increases in total and immature neutrophils as well as granulocyte/macrophage progenitors (GMPs). GSDMD-deficient GMPs and all-trans-retinoic acid (ATRA)-stimulated human promyelocytes NB4 were further demonstrated to possess enhanced clonogenic and differentiation abilities compared with controls. Mechanistically, GSDMD knockdown promoted self-renewal and granulocyte differentiation by restricting calcium influx, contributing to granulopoiesis. Functionally, GSDMD deficiency led to increased pathogenic neutrophil extracellular traps (NETs) in lupus peripheral blood and bone marrow-derived neutrophils. Taken together, our data establish that GSDMD deletion accelerates LN development by promoting granulopoiesis in a calcium influx-regulated manner, unraveling its unrecognized critical role in LN pathogenesis.

Gasdermin D (GSDMD) is emerging as an important player in autoimmune diseases, but its exact role in lupus nephritis (LN) remains controversial. Here, we identified markedly elevated GSDMD in human and mouse LN kidneys, predominantly in CD11b+ myeloid cells. Global or myeloid-conditional deletion of GSDMD was shown to exacerbate systemic autoimmunity and renal injury in lupus mice with both chronic graft-versus-host (cGVH) disease and nephrotoxic serum (NTS) nephritis. Interestingly, RNA sequencing and flow cytometry revealed that myeloid GSDMD deficiency enhanced granulopoiesis at the hematopoietic sites in LN mice, exhibiting remarkable enrichment of neutrophil-related genes, significant increases in total and immature neutrophils as well as granulocyte/macrophage progenitors (GMPs). GSDMD-deficient GMPs and all-trans-retinoic acid (ATRA)-stimulated human promyelocytes NB4 were further demonstrated to possess enhanced clonogenic and differentiation abilities compared with controls. Mechanistically, GSDMD knockdown promoted self-renewal and granulocyte differentiation by restricting calcium influx, contributing to granulopoiesis. Functionally, GSDMD deficiency led to increased pathogenic neutrophil extracellular traps (NETs) in lupus peripheral blood and bone marrow-derived neutrophils. Taken together, our data establish that GSDMD deletion accelerates LN development by promoting granulopoiesis in a calcium influx-regulated manner, unraveling its unrecognized critical role in LN pathogenesis. [ABSTRACT FROM AUTHOR]

Abdominal aortic aneurysm (AAA) is a chronic aortic disease that lacks effective pharmacological therapies. This study was performed to determine the influence of treatment with the gasdermin D inhibitor necrosulfonamide on experimental AAAs. AAAs were induced in male apolipoprotein E-deficient mice by subcutaneous angiotensin II infusion (1000 ng/kg body weight/min), with daily administration of necrosulfonamide (5 mg/kg body weight) or vehicle starting 3 days prior to angiotensin II infusion for 30 days. Necrosulfonamide treatment remarkably suppressed AAA enlargement, as indicated by reduced suprarenal maximal external diameter and surface area, and lowered the incidence and reduced the severity of experimental AAAs. Histologically, necrosulfonamide treatment attenuated medial elastin breaks, smooth muscle cell depletion, and aortic wall collagen deposition. Macrophages, CD4+ T cells, CD8+ T cells, and neovessels were reduced in the aneurysmal aortas of necrosulfonamide- as compared to vehicle-treated angiotensin II-infused mice. Atherosclerosis and intimal macrophages were also substantially reduced in suprarenal aortas from angiotensin II-infused mice following necrosulfonamide treatment. Additionally, the levels of serum interleukin-1β and interleukin-18 were significantly lower in necrosulfonamide- than in vehicle-treated mice without affecting body weight gain, lipid levels, or blood pressure. Our findings indicate that necrosulfonamide reduced experimental AAAs by preserving aortic structural integrity as well as reducing mural leukocyte accumulation, neovessel formation, and systemic levels of interleukin-1β and interleukin-18. Thus, pharmacologically inhibiting gasdermin D activity may lead to the establishment of nonsurgical therapies for clinical AAA disease. [ABSTRACT FROM AUTHOR]

Bronchopulmonary dysplasia (BPD) is a common serious complication of premature babies. No effective means control it. Hyperoxia damage is one of the important mechanisms of BPD. The reaserach confirmed pyroptosis existed in BPD. Dexmedetomidine is a new, high-specific a2 receptor agonist. Previous research foundation found that dexmedetomidine has a protective effect on BPD. To investigate how dexmedetomidine improves hyperoxic lung injury in neonatal mice by regulating pyroptosis. Neonatal rats were randomly divided into four groups: normal control group, hyperoxic injury group, air plus dexmedetomidine group, and hyperoxia plus dexmedetomidine group. After seven days the lungs of rats in each group were extracted, and the wet-to-dry weight ratio of the lung was measured. The lung injury in rats was observed using hematoxylin-eosin staining. Additionally, the expression and localization of nucleotidebinding oligomerization domain-like receptor thermal protein domain associated protein 3 (NLRP3), apoptosisassociated speck-like protein (ASC), and gasdermin D (GSDMD) proteins were examined in the lungs of rats using immunofluorescence staining. The mRNA levels of NLRP3, ASC, caspase-1, and interleukin 18 (IL-18) in the lungs of rats were determined using real-time PCR. Moreover, the protein levels of NLRP3, ASC, caspase-1/cleaved caspase-1, interleukin 1beta (IL-1b), IL-18, and tunor necrosis factor alpha (TNF-a) were detected in lungs of rats using Western blot. The extent of mitochondrial damage in lung tissues of each group was observed by transmission electron microscopy. The lung tissue injury of the neonatal rats was significantly improved in the hyperoxia plus dexmedetomidine group compared to the hyperoxic injury group. Furthermore, the expressions of pyroptosis-related proteins such as NLRP3, ASC, cleaved-caspase-1, and GSDMD were significantly decreased, along with the expressions of inflammatory factors in lung tissues. By inhibiting the NLRP3/caspase-1/GSDMD pyroptosis pathway, dexmedetomidine reduces the activation and release of inflammatory factors and provides a protective effect against hyperoxic lung injury in neonatal mice. [ABSTRACT FROM AUTHOR]

Noncanonical pyroptosis is triggered by Caspase 4/5/11, which cleaves Gasdermin D (GSDMD), leading to cell lysis. While GSDMD has been studied previously in systemic lupus erythematosus (SLE), the role of pyroptosis in SLE pathogenesis remains unclear and contentious, with limited understanding of Caspase 11‐mediated pyroptosis in this condition. In this study, we explored the level of Caspase 11‐mediated pyroptosis in SLE, identifying both the upstream pathways and the interaction between pyroptosis and adaptive immune responses. We observed increased Caspase 5/11 and GSDMD‐dependent pyroptosis in the macrophages/monocytes of both lupus patients and mice. We identified serum lipopolysaccharide (LPS), released from the gut due to a compromised gut barrier, as the signal that triggers Caspase 11 activation in MRL/lpr mice. We further discovered that pyroptotic macrophages promote the differentiation of mature B cells independently of T cells. Additionally, inhibiting Caspase 11 and preventing LPS leakage proved effective in improving lupus symptoms in MRL/lpr mice. These findings suggest that elevated serum LPS, resulting from a damaged gut barrier, induces Caspase 11/GSDMD‐mediated pyroptosis, which in turn promotes B cell differentiation and enhances autoimmune responses in SLE. Thus, targeting Caspase 11 could be a viable therapeutic strategy for SLE. [ABSTRACT FROM AUTHOR]

Objective To observe the changes in the expression of absent in melanoma 2(AIM2), inflammasome signal pathway-related factors, double-stranded DNA (dsDNA), interleukin (IL)-1β, IL-18 and gasdermin D (GSDMD) in peripheral blood mononuclear cells (PBMCs) of patients with acute gouty arthritis, to analyze the relationship between AIM2, GSDMD in mononuclear cells and the condition of patients with acute gouty arthritis [WBC, PLT, ESR, CRP, IL1β, IL-18, BMI, UA, BUN, serum creatinine (SCr), creatinine clearance rate (CCr), TG, TC], and to explore the role of AIM2 inflammasome signal pathway-mediated pyroptosis in the development and progression of acute gouty arthritis. Methods Thirty patients with acute gouty arthritis (observation group) and 30 healthy controls (control group) were included to compare the levels of AIM2, GSDMD in PBMCs, and IL-1β, IL-18, and dsDNA in serum. Spearman correlation analysis was used to investigate the relationships between AIM2 mRNA, GSDMD mRNA, and the related indicators of patients with acute gouty arthritis (IL-1β, IL-18, WBC, PLT, ESR, CRP, BMI, UA, BUN, SCr, CCr, TG, and TC). Results Compared with the control group, the expression levels of AIM2 and GSDMD mRNA in PBMCs of the observation group were higher (both P<0. 05), and the levels of serum dsDNA, IL-1β, IL-18 were higher (all P<0. 01). AIM2 mRNA in PBMCs was positively correlated with WBC, ESR, CRP, BMI, TC, TG, and SCr (all P<0. 05), and GSDMD mRNA was positively correlated with ESR, IL-1β, and SCr (all P<0. 05). Conclusion The levels of AIM2, GSDMD in PBMCs, and dsDNA, IL-1β, and IL-18 in the serum of patients with acute gouty arthritis increase, indicating that AIM2 inflammasome-mediated pyroptosis may be involved in the development and progression of acute gouty arthritis. [ABSTRACT FROM AUTHOR]

Acute liver failure (ALF) is a life-threatening disease with high mortality. Given excessive inflammation is one of the major pathogenesis of ALF, candidates targeting inflammation could be beneficial in the condition. Now the effect of hyperactivated succinate dehydrogenase (SDH) on promoting inflammation in lipopolysaccharide (LPS)-treated macrophages has been studied. However, its role and mechanism in ALF is not well understood. Here intraperitoneal injection of D -galactosamine and LPS was conducted in male C57BL/6 J mice to induce the ALF model. Dimethyl malonate (DMM), which inhibited SDH activity, was injected intraperitoneally 30 min before ALF induction. Macrophage pyroptosis was induced by LPS plus adenosine triphosphate (ATP). Pyroptosis-related molecules and proteins including GSDMD oligomer were examined by ELISA and western blot techniques, respectively. ROS production was assessed by fluorescence staining. The study demonstrated SDH activity was increased in liver macrophages from ALF mice. Importantly, DMM administration inhibited ROS, IL-1β, and pyroptosis-associated proteins levels (NLRP3, cleaved caspase-1, GSDMD-N, and GSDMD oligomers) both in the ALF model and in macrophages stimulated with LPS plus ATP. In vitro, ROS promoted pyroptosis by facilitating GSDMD oligomerization. Additionally, when ROS levels were increased through the addition of H 2 O 2 to the DMM group, the levels of GSDMD oligomers were reverted. In conclusion, SDH hyperactivation promotes macrophage pyroptosis by ROS-mediated GSDMD oligomerization, suggesting that targeting this pathway holds promise as a strategy for treating ALF and other inflammatory diseases. [Display omitted] • Hyperactivation of SDH in liver macrophages is associated with ALF mice. • Increased SDH activity promotes pyroptosis in macrophages by ROS in vitro and in vivo. • ROS accelerates macrophage pyroptosis by GSDMD oligomerization. [ABSTRACT FROM AUTHOR]

The article discusses the limited cell-membrane permeability of fluorochrome-labeled inhibitors of caspase-1 (FLICA reagents) and its implications for studying caspase-1 activation and its role in inflammation and cell death. The study found that FLICA reagents require gasdermin D (GSDMD) membrane pores to efficiently enter cells and bind active caspase-1. The article emphasizes the importance of considering the permeability of FLICA reagents and the appropriateness of controls when planning experiments and interpreting data. The research was supported by various funding sources and the authors declare potential conflicts of interest. [Extracted from the article]

BACKGROUND: Cell death and neuroinflammation are two important targets in the treatment of spinal cord injury. Pyroptosis is a programmed cell death closely related to neuroinflammation and targeted inhibition of pyroptosis after spinal cord injury is a promising therapeutic strategy. OBJECTIVE: To summarize the molecular mechanism, positive and negative regulatory factors and therapeutic strategies of pyroptosis in spinal cord injury. METHODS: The search terms were “spinal cord injury, pyroptosis, nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), Caspase, Gasdermin D (GSDMD), IL-1β, IL-18” and 93 English literatures included in PubMed and Web of Science were finally selected for review. RESULTS AND CONCLUSION: As a newly discovered programmed cell death, pyroptosis has been shown to play an important role in the secondary injury stage after spinal cord injury. Among the regulatory factors of pyroptosis after spinal cord injury, CD73, NRF2, GDF-11, dopamine, FANCC and miR-423-5P could inhibit pyroptosis, while TLR4 and Aopps could promote pyroptosis. In terms of treatment, the active ingredients of traditional Chinese medicine (paeonol, tripterine, betulinic acid, piperine, kaempferol, and camptothecin), exosomes of various cell origins, and some drugs (metformin, topotecan, lithium, zinc, and carbon monoxide-releasing molecule 3) can effectively inhibit pyroptosis and reduce secondary spinal cord injury, but the toxicity and specific dose of these drugs need to be further studied. The specific molecular mechanism by which pyroptosis aggravates spinal cord injury is still poorly understood. The role of non-classical pathways and other inflammasomes is worth further exploration. At present, the research on pyroptosis after spinal cord injury only stays at the animal experiment stage. There are no related clinical studies and no approved targeted therapeutic drugs. (6) The application of pyroptosis after spinal cord injury has great potential, and its specific regulatory mechanism should be further studied in the future to provide a new target for the treatment of spinal cord injury. [ABSTRACT FROM AUTHOR]

Inflammatory illnesses, such as periodontitis and atherosclerotic coronary heart disease (ASCHD), trigger the production of pro-inflammatory mediators. The aim of this study was to assess the accuracy of using salivary interleukin-1β (IL-1β), interleukin-18 (IL-18), and gasdermin D (GSDMD) in discerning patients with periodontitis with and without ASCHD from healthy individuals, and to assess their correlation with clinical periodontal parameters and low-density lipoprotein (LDL) levels. The study involved 120 participants: 30 were healthy subjects (control group, C), 30 had generalized periodontitis (group P), 30 had ASCHD and clinically healthy periodontium (group AS-C), and 30 had ASCHD and generalized periodontitis (group AS-P). Saliva and blood samples were collected, and periodontal characteristics such as plaque index, bleeding on probing, probing pocket depth, and clinical attachment loss were examined. IL-1β, IL-18, and GSDMD levels from saliva were determined using ELISA. LDL levels were determined from the blood samples. Groups P, AS-C, and AS-P had higher levels of salivary IL-1β, IL-18, and GSDMD than group C. The receiver operating characteristic (ROC) curves of all biomarkers showed high diagnostic accuracy, with a significant positive correlation with the clinical parameters and LDL levels. The observed correlations between the studied pro-inflammatory mediators and disease severity suggest that these biomarkers could serve as indicators of disease progression in conditions such as periodontitis and ASCHD. [ABSTRACT FROM AUTHOR]

Pyroptosis is a programmed cell death process that frequently occurs in many diseases, including hyperuricemic nephropathy (HN). In HN, a range of stimuli mediates inflammation, leading to the activation of inflammasomes and the production of gasdermin D (GSDMD). Baicalin (BA), a natural flavonoid renowned for its antioxidant and anti‐inflammatory properties, was investigated for its role in HN in this study. Initially, HN‐like inflammation and pyroptosis were induced in HK‐2 cells with treatment of monosodium urate (MSU), followed by the BA treatment. The expression of pyroptosis‐associated genes, Panx‐1 and P2X7, at both mRNA and protein levels was assessed through real‐time polymerase chain reaction (RT‐qPCR) and Western blotting (WB) without or with BA treatment. The results showed that expression of Panx‐1 and P2X7 at mRNA and protein levels was increased in MSU‐treated HK‐2 cells, which subsequently decreased upon the BA treatment. Further experiments showed that BA could combine NLRP3 inflammasome and GSDMD, destabilizing GSDMD protein. Moreover, BA protected the cell membrane from MSU‐induced damage, as evidenced by Hoechst 33342 and PI double staining, lactate dehydrogenase (LDH) assays, and electron microscopy observations. These results suggest that BA is involved in the regulating Panx‐1/P2X7 pathways and thus inhibits pyroptosis, highlighting its potential therapeutic effect for HN. [ABSTRACT FROM AUTHOR]

Inflammation plays a pivotal role in cancer development, with chronic inflammation promoting tumor progression and treatment resistance, whereas acute inflammatory responses contribute to protective anti-tumor immunity. Gasdermin D (GSDMD) mediates the release of pro-inflammatory cytokines such as IL-1β. While the release of IL-1β is directly linked to the progression of several types of cancers, the role of GSDMD in cancer is less clear. In this study, we show that GSDMD expression is upregulated in human breast, kidney, liver, and prostate cancer. Higher GSDMD expression correlated with increased survival in primary breast invasive carcinoma (BRCA), but not in liver hepatocellular carcinoma (LIHC). In BRCA, but not in LIHC, high GSDMD expression correlated with a myeloid cell signature associated with improved prognosis. To further investigate the role of GSDMD in anticancer immunity, we induced breast cancer and hepatoma tumors in GSDMD-deficient mice. Contrary to our expectations, GSDMD deficiency had no effect on tumor growth, immune cell infiltration, or cytokine expression in the tumor microenvironment, except for Cxcl10 upregulation in hepatoma tumors. In vitro and in vivo innate immune activation with TLR ligands, that prime inflammatory responses, revealed no significant difference between GSDMD-deficient and wild-type mice. These results suggest that the impact of GSDMD on anticancer immunity is dependent on the tumor type. They underscore the complex role of inflammatory pathways in cancer, emphasizing the need for further exploration into the multifaceted effects of GSDMD in various tumor microenvironments. As several pharmacological modulators of GSDMD are available, this may lead to novel strategies for combination therapy in cancer.

Sulfur mustard (SM) is a highly toxic blister agent which has been used many times in several wars and conflicts and caused heavy casualties. Ease of production and lack of effective therapies make SM a potential threat to public health. SM intoxication causes severe damage on various target organs, such as the skin, eyes, and lungs. In addition, SM exposure can also lead to hepatotoxicity and severe liver injuries. However, despite decades of research, the molecular mechanism underlying SM-induced liver damage remains obscure. SM can be converted into various products via complex hepatic metabolism in vivo. There are some pieces of evidence that one of the oxidation products of SM, divinyl sulfone (DVS), exhibits even more significant toxicity than SM. Nevertheless, the molecular toxicology of DVS is still hardly known. In the present study, we confirmed that DVS is even more toxic than SM in the human hepatocellular carcinoma cell line HepG2. Further mechanistic study revealed that DVS exposure (200 μM) promotes pyroptosis in HepG2 cells, while SM (400 μM) mainly induces apoptosis. DVS induces gasdermin D (GSDMD) mediated pyroptosis, which is independent of caspases activation but depends on the large amounts of reactive oxygen species (ROS) and severe oxidative stress produced during DVS exposure. Our findings may provide novel insights for understanding the mechanism of SM poisoning and may be helpful to discover promising therapeutic strategies for SM intoxication. [ABSTRACT FROM AUTHOR]

• NLRP3 inflammasome inhibition improves CIH-induced cognitive impairment in mice. • CIH activates microglia-specific NLRP3 inflammasome via ROS-NF-κB signaling. • IL-1β releases from microglia in a GSDMD-dependent manner without pyroptosis. • IL-1β impairs cognitive function by impairing synaptic plasticity of hippocampus. Hypoxia/reoxygenation caused by chronic intermittent hypoxia (CIH) plays an important role in cognitive deficits in patients with obstructive sleep apnea. However, the precise underlying mechanism remains unclear. This study investigated whether the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is involved in CIH-induced spatial learning and memory impairment in mice, and the possible underlying upstream and downstream mechanisms. The C57BL/6 male mice were exposed to CIH (21% O 2 -6% O 2 , 4 min/cycle, 8 h/day) for 9 weeks to investigate the role of NLRP3 in CIH-induced spatial learning and memory impairment in mice. BV2 cells were exposed to intermittent hypoxia (21% O 2 -1% O 2 , 90 min/cycle) for 48 h to investigate the possible mechanisms in vitro. We found that: 1) inhibition of NLRP3 inflammasome activation improved CIH-induced spatial learning and memory impairment in mice. 2) CIH damaged hippocampal neurons but increased the number of microglia in mice hippocampi; CIH activated microglia-specific NLRP3 inflammasome, leading to upregulation of matured IL-1β and N-GSDMD. 3) intermittent hypoxia activated NLRP3 inflammasome via the ROS-NF-κB signaling pathway to promote the release of matured IL-1β from microglia in a GSDMD-dependent manner without pyroptosis. 4) The IL-1β released from microglia might impair the synaptic plasticity of hippocampal CA3-CA1 synapses by acting on IL-1 receptors in hippocampal neurons. Our findings reveal that ROS-NF-κB-NLRP3 inflammasome-GSDMD dependent IL-1β release from microglia may participate in CIH-induced spatial learning and memory impairment by acting on hippocampal neuronal IL-1 receptor, leading to synaptic plasticity impairment. [ABSTRACT FROM AUTHOR]

The activation of the pyrin inflammasome represents a highly intriguing mechanism employed by the innate immune system to effectively counteract pathogenic agents. Despite its key role in innate immunity, pyrin has also garnered significant attention due to its association with a range of autoinflammatory diseases (AIDs) including familial Mediterranean fever caused by disruption of the MEFV gene, or in other genes involved in its complex regulation mechanisms. Pyrin activation is strictly dependent on homeostasisaltering molecular processes, mostly consisting of the disruption of the small Ras Homolog Family Member A (RhoA) GTPases by pathogen toxins. The downstream pathways are regulated by the phosphorylation of specific pyrin residues by the kinases PKN1/2 and the binding of the chaperone 14-3-3. Furthermore, a key role in pyrin activation is played by the cytoskeleton and gasdermin D, which is responsible for membrane pores in the context of pyroptosis. In addition, recent evidence has highlighted the role of steroid hormone catabolites and alarmins S100A8/A9 and S100A12 in pyrin-dependent inflammation. The aim of this article is to offer a comprehensive overview of the most recent evidence on the pyrin inflammasome and its molecular pathways to better understand the pathogenesis behind the significant group of pyrinrelated AIDs. [ABSTRACT FROM AUTHOR]

• Gasdermin D (GSDMD) activation occurs in oligodendrocytes and CNS macrophages. • GDSMD and Ninjurin 1 are induced in neuroinflammatory demyelination. • GSDMD genetic deletion reduces neuroinflammatory demyelination and axonal injury. • GSDMD activation represents a potential therapeutic target for progressive MS. Neuroinflammation coupled with demyelination and neuro-axonal damage in the central nervous system (CNS) contribute to disease advancement in progressive multiple sclerosis (P-MS). Inflammasome activation accompanied by proteolytic cleavage of gasdermin D (GSDMD) results in cellular hyperactivation and lytic death. Using multiple experimental platforms, we investigated the actions of GSDMD within the CNS and its contributions to P-MS. Brain tissues from persons with P-MS showed significantly increased expression of GSDMD, NINJ1, IL-1β, and −18 within chronic active demyelinating lesions compared to MS normal appearing white matter and nonMS (control) white matter. Conditioned media (CM) from stimulated GSDMD+/+ human macrophages caused significantly greater cytotoxicity of oligodendroglial and neuronal cells, compared to CM from GSDMD-/- macrophages. Oligodendrocytes and CNS macrophages displayed increased Gsdmd immunoreactivity in the central corpus callosum (CCC) of cuprizone (CPZ)-exposed Gsdmd+/+ mice, associated with greater demyelination and reduced oligodendrocyte precursor cell proliferation, compared to CPZ-exposed Gsdmd-/- animals. CPZ-exposed Gsdmd+/+ mice exhibited significantly increased G-ratios and reduced axonal densities in the CCC compared to CPZ-exposed Gsdmd-/- mice. Proteomic analyses revealed increased brain complement C1q proteins and hexokinases in CPZ-exposed Gsdmd-/- animals. [18F]FDG PET imaging showed increased glucose metabolism in the hippocampus and whole brain with intact neurobehavioral performance in Gsdmd-/- animals after CPZ exposure. GSDMD activation in CNS macrophages and oligodendrocytes contributes to inflammatory demyelination and neuroaxonal injury, offering mechanistic and potential therapeutic insights into P-MS pathogenesis. [ABSTRACT FROM AUTHOR]

Objective: Salmonella enterica serovar Typhimurium (S. Typhimurium) is a representative model organism for investigating host–pathogen interactions. It was reported that S. Typhimurium spvC gene alleviated intestinal inflammation to aggravate systemic infection, while the precise mechanisms remain unclear. In this study, the influence of spvC on the antibacterial defense of macrophage/neutrophil mediated by gasdermin D (GSDMD) was investigated. Methods: Mouse macrophage-like cell lines J774A.1 and RAW264.7, neutrophil-like cells derived from HL-60 cells (human promyletic leukemia cell lines) were infected with S. Typhimurium wild type, spvC deletion and complemented strains. Cell death was evaluated by LDH release and Annexin V-FITC/PI staining. Macrophage pyroptosis and neutrophil NETosis were detected by western blotting, live cell imaging and ELISA. Flow cytometry was used to assess the impact of spvC on macrophage-neutrophil cooperation in macrophage (dTHP-1)-neutrophil (dHL-60) co-culture model pretreated with GSDMD inhibitor disulfiram. Wild-type and Gsdmd−/− C57BL/6J mice were utilized for in vivo assay. The degree of phagocytes infiltration and inflammation were analyzed by immunofluorescence and transmission electron microscopy. Results: Here we find that spvC inhibits pyroptosis in macrophages via Caspase-1/Caspase-11 dependent canonical and non-canonical pathways, and restrains neutrophil extracellular traps extrusion in GSDMD-dependent manner. Moreover, spvC could ameliorate macrophages/neutrophils infiltration and cooperation in the inflammatory response mediated by GSDMD to combat Salmonella infection. Conclusions: Our findings highlight the antibacterial activity of GSDMD in phagocytes and reveal a novel pathogenic mechanism employed by spvC to counteract this host defense, which may shed new light on designing effective therapeutics to control S. Typhimurium infection. [ABSTRACT FROM AUTHOR]

Abstract Recent studies indicate a significant upregulation of gasdermin D (GSDMD) in acute kidney injury (AKI), a severe medical condition characterized by high morbidity and mortality globally. In this study, we identified and validated the therapeutic effects of small molecule inhibitors targeting the GSDMD pathway for AKI treatment. Using a drug screening assay, we evaluated thousands of small molecules from DrugBank against Lipopolysaccharide (LPS) and Nigericin‐stimulated immortalized bone marrow‐derived macrophages (iBMDMs) to discern GSDMD pathway activators. We simulated AKI in primary renal tubular epithelial cells using hydrogen peroxide (H2O2) exposure. Furthermore, AKI in mouse models was induced via cisplatin and ischemia/reperfusion. Our findings highlight stevioside as a potent GSDMD activator exhibiting minimal toxicity. Experimental results, both in vitro and in vivo, demonstrate stevioside's significant potential in alleviating renal tubular epithelial cell injury and AKI histological damage. After stevioside treatment, a notable decrease in cleaved GSDMD‐N terminal levels was observed coupled with diminished inflammatory factor release. This observation was consistent in both cisplatin‐ and ischemia/reperfusion‐induced AKI mouse models. Collectively, our research suggests that stevioside could be a promising candidate for modulating GSDMD signaling in AKI treatment.

Abstract Noncanonical pyroptosis is triggered by Caspase 4/5/11, which cleaves Gasdermin D (GSDMD), leading to cell lysis. While GSDMD has been studied previously in systemic lupus erythematosus (SLE), the role of pyroptosis in SLE pathogenesis remains unclear and contentious, with limited understanding of Caspase 11‐mediated pyroptosis in this condition. In this study, we explored the level of Caspase 11‐mediated pyroptosis in SLE, identifying both the upstream pathways and the interaction between pyroptosis and adaptive immune responses. We observed increased Caspase 5/11 and GSDMD‐dependent pyroptosis in the macrophages/monocytes of both lupus patients and mice. We identified serum lipopolysaccharide (LPS), released from the gut due to a compromised gut barrier, as the signal that triggers Caspase 11 activation in MRL/lpr mice. We further discovered that pyroptotic macrophages promote the differentiation of mature B cells independently of T cells. Additionally, inhibiting Caspase 11 and preventing LPS leakage proved effective in improving lupus symptoms in MRL/lpr mice. These findings suggest that elevated serum LPS, resulting from a damaged gut barrier, induces Caspase 11/GSDMD‐mediated pyroptosis, which in turn promotes B cell differentiation and enhances autoimmune responses in SLE. Thus, targeting Caspase 11 could be a viable therapeutic strategy for SLE.

Abstract The NLRP3 inflammasome is an intracellular sensor and an essential component of the innate immune system involved in danger recognition. An important hallmark of inflammasome activation is the formation of a single supramolecular punctum, known as a speck, per cell, which is the site where the pro-inflammatory cytokines IL-1β and IL-18 are converted into their bioactive form. Speck also provides the platform for gasdermin D protein activation, whose N-terminus domain perforates the plasma membrane, allowing the release of mature cytokines alongside with a highly inflammatory form of cell death, namely pyroptosis. Although controlled NLRP3 inflammasome-pyroptosis pathway activation preserves mucosal immunity homeostasis and contributes to host defense, a prolonged trigger is deleterious and could lead, in genetically predisposed subjects, to the onset of inflammatory bowel disease, including Crohn's disease and ulcerative colitis, as well as to gastrointestinal cancer. Experimental evidence shows that the NLRP3 inflammasome has both protective and pathogenic abilities. In this review we highlight the impact of the NLRP3-pyroptosis axis on the pathophysiology of the gastrointestinal tract at molecular level, focusing on newly discovered features bearing pro- and anti-inflammatory and neoplastic activity, and on targeted therapies tested in preclinical and clinical trials.

Abstract Background Inflammasome activation and the subsequent release of pro-inflammatory cytokines including Interleukin 1β (IL-1β) have been widely reported to contribute to the progression of retinal degenerations, including age-related macular degeneration (AMD), the leading cause of blindness in the Western World. The role of Gasdermin D (GSDMD), a key executioner of pyroptosis following inflammasome activation, however, is less well-established. In this study we aimed to characterise the role of GSDMD in the healthy and degenerating retina, and uncover its role as a conduit for IL-1β release, including via extracellular vesicle (EV)-mediated release. Methods GSDMD mutant and knockout mice, in vitro models of inflammation and a well-established in vivo model of retinal degeneration (photo-oxidative damage; PD) were utilised to explore the role and pathological contribution of GSDMD in regulating IL-1β release and propagating retinal inflammation. RNA sequencing of whole retinas was used to investigate GSDMD-mediated inflammation during degeneration. The role of EVs in GSDMD-mediated IL-1β release was investigated using nanoparticle tracking analysis, ELISA and EV inhibition paradigms. Finally, the therapeutic efficacy of targeting GSDMD was examined using GSDMD-specific siRNA. Results We identified in this work that mice deficient in GSDMD had better-preserved retinal function, increased photoreceptor survivability and reduced inflammation. RNA-Seq analysis revealed that GSDMD may propagate inflammation in the retina via NF-κB signalling cascades and release of pro-inflammatory cytokines. We also showed that IL-1β was packaged and released via EV in a GSDMD-dependent manner. Finally, we demonstrated that impairing GSDMD function using RNAi or blocking EV release was able to reduce IL-1β content in cell-free supernatant and EV. Conclusions Taken together, these results suggest that pyroptotic pore-forming protein GSDMD plays a key role in the propagation of retinal inflammation, in particular via the release of EV-encapsulated IL-1β. Targeting GSDMD using genetic or pharmacological inhibitors may pose a therapeutic opportunity to dampen inflammatory cascades and delay the progression of retinal degeneration.

The innate immune system serves as the first line of defense against β-coronaviruses (β-CoVs), a family of viruses that includes SARS-CoV-2. Viral sensing via pattern recognition receptors triggers inflammation and cell death, which are essential components of the innate immune response that facilitate viral clearance. However, excessive activation of the innate immune system and inflammatory cell death can result in uncontrolled release of proinflammatory cytokines, resulting in cytokine storm and pathology. PANoptosis, innate immune, inflammatory cell death initiated by innate immune sensors and driven by caspases and RIPKs through PANoptosome complexes, has been implicated in the pathology of viral infections. Therefore, understanding the molecular mechanisms regulating PANoptosis in response to β-CoV infection is critical for identifying new therapeutic targets that can mitigate disease severity. In the current study, we analyzed findings from a cell death-based CRISPR screen with archetypal β-CoV mouse hepatitis virus (MHV) as the trigger to characterize host molecules required for inflammatory cell death. As a result, we identified SMARCA4, a chromatin regulator, as a putative host factor required for PANoptosis in response to MHV. Furthermore, we observed that gRNA-mediated deletion of Smarca4 inhibited MHV-induced PANoptotic cell death in macrophages. These findings have potential translational and clinical implications for the advancement of treatment strategies for β-CoVs and other infections.

Abstract Ischemia–reperfusion injury occurs after reperfusion treatment for patients suffering myocardial infarction, however the underlying mechanisms are incompletely understood and effective pharmacological interventions are limited. Here, we report the identification and characterization of the FDA-approved drug disulfiram (DSF) as a cardioprotective compound. By applying high-throughput chemical screening, we found that DSF decreased H2O2-induced cardiomyocyte death by inhibiting Gasdermin D, but not ALDH1, in cardiomyocytes. Oral gavage of DSF decreased myocardial infarct size and improved heart function after myocardial ischemia–reperfusion injury in rats. Therefore, this work reveals DSF as a potential therapeutic compound for the treatment of ischemic heart disease.

Inflammatory bowel disease (IBD) is a chronic relapsing gastrointestinal disorder, while the treatment effect is not satisfactory. Immune responsive gene 1 (IRG1) is a highly expressed gene in macrophage in response to inflammatory response and catalyzes the production of itaconate. Studies have reported that IRG1/itaconate has a significant antioxidant effect. This study aimed to investigate the effect and mechanism of IRG1/itaconate on dextran sulfate sodium (DSS)-induced colitis in vivo and in vitro. In vivo experiments, we found IRG1/itaconate exerted protective effects against acute colitis by increasing mice weight, the length of colon, reducing disease activity index and colonic inflammation. Meanwhile, IRG1 deletion aggravated the macrophages/CD4+/CD8+ T-cell accumulation, and increased the release of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, the activation of nuclear factor-κB (NF-κB)/mitogen-activated protein kinase (MAPK) signaling pathway, and gasdermin D (GSDMD) mediated pyroptosis. Four-octyl itaconate (4-OI), a derivative of itaconate, attenuated these changes, therefore relieved DSS-induced colitis. In vitro experiment, we found 4-OI inhibited the reactive oxygen species production, thereby inhibiting the activation of MAPK/NF-κB signaling pathway in RAW264.7 and murine bone-marrow-derived macrophages. Simultaneously, we found 4-OI inhibited caspase1/GSDMD-mediated pyroptosis to reduce the release of cytokines. Finally, we found anti-TNF-α agent reduced the severity of DSS-induced colitis and inhibited gasdermin E (GSDME)-mediated pyroptosis in vivo. Meanwhile, our study revealed that 4-OI inhibited caspase3/GSDME-mediated pyroptosis induced by TNF-α in vitro. Taken together, IRG1/itaconate exerted a protective role in DSS-induced colitis by inhibiting inflammatory response and GSDMD/GSDME-mediated pyroptosis, which could be a promising candidate for IBD therapy.

Septic shock is characterized by an excessive inflammatory response depicted in a cytokine storm that results from invasive bacterial, fungi, protozoa, and viral infections. Non-canonical inflammasome activation is crucial in the development of septic shock promoting pyroptosis and proinflammatory cytokine production via caspase-11 and gasdermin D (GSDMD). Here, we show that NAD+ treatment protected mice toward bacterial and lipopolysaccharide (LPS)-induced endotoxic shock by blocking the non-canonical inflammasome specifically. NAD+ administration impeded systemic IL-1β and IL-18 production and GSDMD-mediated pyroptosis of macrophages via the IFN-β/STAT-1 signaling machinery. More importantly, NAD+ administration not only improved casp-11 KO (knockout) survival but rendered wild type (WT) mice completely resistant to septic shock via the IL-10 signaling pathway that was independent from the non-canonical inflammasome. Here, we delineated a two-sided effect of NAD+ blocking septic shock through a specific inhibition of the non-canonical inflammasome and promoting immune homeostasis via IL-10, underscoring its unique therapeutic potential.

Diabetic cardiomyopathy (DCM) is a pathophysiological condition triggered by diabetes mellitus (DM), which can lead to heart failure (HF). One of the most important cellular processes associated with DCM is the death of cardiomyocytes. Gasdermin D (GSDMD) plays a key role in mediating pyroptosis, a type of programmed cell death closely associated with inflammasome activation. Recent studies have revealed that pyroptosis is induced during hyperglycemia, which is crucial to the development of DCM. Although the effects of pyroptosis on DCM have been discussed, the relationship between DCM and GSDMD is not fully clarified. Recent studies gave us the impetus for clarifying the meaning of GSDMD in DCM. The purpose of this review is to summarize new and emerging insights, mainly discussing the structures of GSDMD and the mechanism of pore formation, activation pathways, molecular mechanisms of GSDMD-mediated pyroptosis, and the therapeutic potential of GSDMD in DCM. The implications of this review will pave the way for a new therapeutic target in DCM. [ABSTRACT FROM AUTHOR]

Objective: Colorectal adenocarcinoma (COAD) is a complex and lethal cancer characterized by genetic mutations and epigenetic alterations. Gasdermin proteins, such as gasdermin C (GSDMC) and gasdermin D (GSDMD), play crucial roles in pyroptotic cell death, presenting these proteins as potential targets for diagnosis markers and therapy across various cancers, including COAD. Our study investigated the epigenetic regulation of GSDMC and GSDMD in COAD using bioinformatics and in vitro experiments. Materials and Methods: This study examined the expression and epigenetic control of pyroptosis-related proteins in COAD using bioinformatics tools and databases such as Timer2.0, UALCAN, EWAS Open Platform, Gene Set Cancer Analysis (GSCA), Receiver Operating Characteristic (ROC) plotter, and WANDERER. To investigate target gene expression, HTC-116 and SW620 cell lines were subjected to treatments with estrogen, a DNA methylation inhibitor (5-azacytidine), and a histone deacetylase inhibitor (vorinostat). Results: The results showed that the expression of GSDMC and GSDMD varies based on the subtype of COAD. We established that these genes are regulated through DNA hypermethylation in the cg05316065 island for GSDMC and the cg10810860 island for GSDMD. Additionally, the identification of 5-fluorouracil, oxaliplatin, fluoropyrimidine monotherapy, and capecitabine as predictive biomarkers for GSDMC and GSDMD genes underscores the potential clinical utility in cancer therapy. Our results showed that a combined treatment involving 5-azacytidine, vorinostat, and estrogen increases the expression of these genes, potentially guiding cells toward pyroptosis. Conclusions: This comprehensive analysis reveals the complex roles of GSDMC and GSDMD genes in cancer progression, showcasing their susceptibility to epigenetic regulation and impact on chemotherapy responses. These findings offer crucial insights into their significance as potential targets for diagnosis and therapy in cancer, thereby paving the way for personalized treatment strategies. [ABSTRACT FROM AUTHOR]

The canonical NOD-like receptor family pyrin domain containing 3 (NLRP3) pathway involves a priming step to induce pro-IL-1β followed by a secondary signal such as K+ efflux to activate inflammasome formation. This then leads to the maturation of IL-1β and the formation of gasdermin D (GSDMD) pores that initiate pyroptosis and mediate IL-1β release. In contrast, primary human monocytes also engage an alternative pathway in response to toll-like receptor (TLR) 4 activation, without the need for a secondary signal. Data from a monocyte-like cell line suggest that the alternative pathway functions via the TLR adaptor protein TIR-domain-containing adapter-inducing interferon-b (TRIF), receptor-interacting protein kinase 1 (RIPK1), FAS-associated death domain (FADD) and caspase-8 upstream of NLRP3 activation, but in the absence of K+ efflux or pyroptosis. Usage of the alternative pathway by other members of the TLR family that induce IL-1β but do not signal through TRIF, has yet to be explored in primary human monocytes. Furthermore, the mechanism by which IL-1β is released from monocytes remains unclear. Therefore, this study investigated if the alternative NLRP3 inflammasome pathway is initiated following activation of TLRs other than TLR4, and if GSDMD was necessary for the release of IL-1β. Monocytes were stimulated with ligands that activate TLR1/2, TLR2/6, TLR4 and TLR7 and/or TLR8 (using a dual ligand). Similar to TLR4, all of the TLRs investigated induced IL-1β release in a NLRP3 and caspase-1 dependent manner, indicating that TRIF may not be an essential upstream component of the alternative pathway. Furthermore, inhibition of RIPK1 kinase activity had no effect on IL-1β release. Although IL-1β was released independently of K+ efflux and pyroptosis, it was significantly reduced by an inhibitor of GSDMD. Therefore, it is feasible that low level GSDMD pore formation may facilitate the release of IL-1β from the cell, but not be present in sufficient quantities to initiate pyroptosis. Together these data suggest that the alternative pathway operates independently of RIPK1 kinase activity, downstream of diverse TLRs including TLR4 in primary human monocytes and supports the potential for IL-1β release via GSDMD pores alongside other unconventional secretory pathways. [ABSTRACT FROM AUTHOR]

Pyroptosis is a form of programmed cell death mediated by gasdermins, particularly gasdermin D (GSDMD), which is widely expressed in tissues throughout the body. GSDMD belongs to the gasdermin family, which is expressed in a variety of cell types including epithelial cells and immune cells. It is involved in the regulation of anti-inflammatory responses, leading to its differential expression in a wide range of diseases. In this review, we provide an overview of the current understanding of the major activation mechanisms and effector pathways of GSDMD. Subsequently, we examine the importance and role of GSDMD in different diseases, highlighting its potential as a pan-biomarker. We specifically focus on the biological characteristics of GSDMD in several diseases and its promising role in diagnosis, early detection, and differential diagnosis. Furthermore, we discuss the application of GSDMD in predicting prognosis and monitoring treatment efficacy in cancer. This review proposes a new strategy to guide therapeutic decision-making and suggests potential directions for further research into GSDMD. [ABSTRACT FROM AUTHOR]

This case-control study was to examine the association between the single nucleotide polymorphism of AIM2 and Pycard genes with susceptibility to periodontitis with and without coronary heart disease, to determine interleuken-18 and gasdermin D levels in the saliva of periodontitis with and without coronary heart disease patients, as well as their correlation with salivary interleuken-18 and gasdermin D levels and clinical periodontal parameters.Methods: The present study recruited 120 participants: 30 were healthy subjects (control, C), 30 had generalized periodontitis (P), 30 had atherosclerosis coronary heart disease with clinically healthy periodontium (AS-C), and 30 had atherosclerosis coronary heart disease with generalized periodontitis (AS-P). All individuals' demographic data recorded, saliva and blood samples collected, then periodontal characteristics were detailed. These parameters include plaque index, bleeding on probing, probing pocket depth, and clinical attachment loss. AIM2 and Pycard gene polymorphisms were analyzed by polymerase chain reaction assay, electrophoresis and sequencing. An enzyme-linked immunosorbent assay (ELISA) was conducted to determine the level of interleuken-18 and gasdermin D in their saliva.Results: The study result of high frequency (T) in single-nucleotide polymorphisms. The high genotypes distribution of GT and TT genotypes in the AIM2 gene and the CT and TT genotypes in the Pycard gene were detected in the periodontitis, atherosclerosis coronary heart disease with healthy periodontium and atherosclerosis coronary heart disease with generalized periodontitis groups as compared to control group. Elevation of salivary interleuken-18 and gasdermin D levels in three patients' groups compared to healthy controls. Both these single-nucleotide polymorphisms also significantly correlated with higher salivary interleuken-18 and gasdermin D levels and worse clinical indices of periodontitis.Conclusion: Single-nucleotide polymorphisms in the AIM2 and Pycard genes are associated with an increased risk of developing periodontitis with and/or without coronary heart disease. Elevation of salivary interleuken-18 and gasdermin D levels associated and impacted on periodontitis with and/or without coronary heart disease. These single-nucleotide polymorphisms may provide evidence for a genetic role in the pathogenesis of periodontitis with and without atherosclerosis coronary heart disease. [ABSTRACT FROM AUTHOR]

Caspase activation results in pyroptosis, an inflammatory cell death that contributes to several inflammatory diseases by releasing inflammatory cytokines and cellular contents. Fusobacterium nucleatum is a periodontal pathogen frequently detected in human cancer and inflammatory bowel diseases. Studies have reported that F. nucleatum infection leads to NLRP3 activation and pyroptosis, but the precise activation process and disease association remain poorly understood. This study demonstrated that F. nucleatum infection exacerbates acute colitis in mice and activates pyroptosis through caspase‐11‐mediated gasdermin D cleavage in macrophages. Furthermore, F. nucleatum infection in colitis mice induces the enhancement of IL‐1⍺ secretion from the colon, affecting weight loss and severe disease activities. Neutralization of IL‐1⍺ protects F. nucleatum infected mice from severe colitis. Therefore, F. nucleatum infection facilitates inflammation in acute colitis with IL‐1⍺ from colon tissue by activating noncanonical inflammasome through gasdermin D cleavage. [ABSTRACT FROM AUTHOR]

The NLRP3 inflammasome is an intracellular sensor and an essential component of the innate immune system involved in danger recognition. An important hallmark of inflammasome activation is the formation of a single supramolecular punctum, known as a speck, per cell, which is the site where the pro-inflammatory cytokines IL-1β and IL-18 are converted into their bioactive form. Speck also provides the platform for gasdermin D protein activation, whose N-terminus domain perforates the plasma membrane, allowing the release of mature cytokines alongside with a highly inflammatory form of cell death, namely pyroptosis. Although controlled NLRP3 inflammasome-pyroptosis pathway activation preserves mucosal immunity homeostasis and contributes to host defense, a prolonged trigger is deleterious and could lead, in genetically predisposed subjects, to the onset of inflammatory bowel disease, including Crohn's disease and ulcerative colitis, as well as to gastrointestinal cancer. Experimental evidence shows that the NLRP3 inflammasome has both protective and pathogenic abilities. In this review we highlight the impact of the NLRP3-pyroptosis axis on the pathophysiology of the gastrointestinal tract at molecular level, focusing on newly discovered features bearing pro- and anti-inflammatory and neoplastic activity, and on targeted therapies tested in preclinical and clinical trials. [ABSTRACT FROM AUTHOR]

Background: Inflammasome activation and the subsequent release of pro-inflammatory cytokines including Interleukin 1β (IL-1β) have been widely reported to contribute to the progression of retinal degenerations, including age-related macular degeneration (AMD), the leading cause of blindness in the Western World. The role of Gasdermin D (GSDMD), a key executioner of pyroptosis following inflammasome activation, however, is less well-established. In this study we aimed to characterise the role of GSDMD in the healthy and degenerating retina, and uncover its role as a conduit for IL-1β release, including via extracellular vesicle (EV)-mediated release. Methods: GSDMD mutant and knockout mice, in vitro models of inflammation and a well-established in vivo model of retinal degeneration (photo-oxidative damage; PD) were utilised to explore the role and pathological contribution of GSDMD in regulating IL-1β release and propagating retinal inflammation. RNA sequencing of whole retinas was used to investigate GSDMD-mediated inflammation during degeneration. The role of EVs in GSDMD-mediated IL-1β release was investigated using nanoparticle tracking analysis, ELISA and EV inhibition paradigms. Finally, the therapeutic efficacy of targeting GSDMD was examined using GSDMD-specific siRNA. Results: We identified in this work that mice deficient in GSDMD had better-preserved retinal function, increased photoreceptor survivability and reduced inflammation. RNA-Seq analysis revealed that GSDMD may propagate inflammation in the retina via NF-κB signalling cascades and release of pro-inflammatory cytokines. We also showed that IL-1β was packaged and released via EV in a GSDMD-dependent manner. Finally, we demonstrated that impairing GSDMD function using RNAi or blocking EV release was able to reduce IL-1β content in cell-free supernatant and EV. Conclusions: Taken together, these results suggest that pyroptotic pore-forming protein GSDMD plays a key role in the propagation of retinal inflammation, in particular via the release of EV-encapsulated IL-1β. Targeting GSDMD using genetic or pharmacological inhibitors may pose a therapeutic opportunity to dampen inflammatory cascades and delay the progression of retinal degeneration. [ABSTRACT FROM AUTHOR]

While exposure to long amphibolic asbestos fibers (L > 10 µm) results in the development of severe diseases including inflammation, fibrosis, and mesothelioma, the pathogenic activity associated with short fibers (L < 5 µm) is less clear. By exposing murine macrophages to short (SFA) or long (LFA) fibers of amosite asbestos different in size and surface chemistry, we observed that SFA internalization resulted in pyroptotic-related immunogenic cell death (ICD) characterized by the release of the pro-inflammatory damage signal (DAMP) IL-1α after inflammasome activation and gasdermin D (GSDMD)-pore formation. In contrast, macrophage responses to non-internalizable LFA were associated with tumor necrosis factor alpha (TNF-α) release, caspase-3 and -7 activation, and apoptosis. SFA effects exclusively resulted from Toll-like receptor 4 (TLR4), a pattern-recognition receptor (PRR) recognized for its ability to sense particles, while the response to LFA was elicited by a multifactorial ignition system involving the macrophage receptor with collagenous structure (SR-A6 or MARCO), reactive oxygen species (ROS) cascade, and TLR4. Our findings indicate that asbestos fiber size and surface features play major roles in modulating ICD and inflammatory pathways. They also suggest that SFA are biologically reactive in vitro and, therefore, their inflammatory and toxic effects in vivo should not be underestimated. [ABSTRACT FROM AUTHOR]

Neuroinflammation is an early event during the pathogenesis of neurodegenerative disorders. Most studies focus on how the factors derived from pathogens or tissue damage activate the inflammation-pyroptosis cell death pathway. It is unclear whether endogenous neurotransmitters could induce inflammatory responses in neurons. Our previous reports have shown that dopamine-induced elevation of intracellular Zn2+ concentration via the D1-like receptor (D1R) is a prerequisite for autophagy and cell death in primary cultured rat embryonic neurons. Here we further examined that this D1R-Zn2+ signaling initiates the transient inflammatory response leading to cell death in cultured cortical neurons. Pretreating the cultured neurons with Zn2+ chelator and inhibitors against inflammation could enhance the cell viability in neurons treated with dopamine and dihydrexidine, an agonist of D1R. Both dopamine and dihydrexidine greatly enhanced inflammasome formation; a Zn2+ chelator, N,N,N′,N′-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine, suppressed this increment. Dopamine and dihydrexidine increased the expression levels of NOD-like receptor pyrin domain-containing protein 3 and enhanced the maturation of caspase-1, gasdermin D, and IL-1β; these changes were all Zn2+-dependent. Dopamine treatment did not recruit the N-terminal of the gasdermin D to the plasma membrane but enhanced its localization to the autophagosomes. Pretreating the neurons with IL-1β could increase the viability of neurons challenged with dopamine. These results demonstrate a novel D1R-Zn2+ signaling cascade activating neuroinflammation and cell death. Therefore, maintaining a balance between dopamine homeostasis and inflammatory responses is an important therapeutic target for neurodegeneration. Dopamine elicits transient inflammatory responses in cultured cortical neurons via the D1R−Zn2+ signaling pathway. Dopamine elevates [Zn2+]i to induce the formation of inflammasomes, which activates caspase-1, resulting in the maturation of IL-1β and gasdermin D (GSDMD). Therefore, the homeostasis of dopamine and Zn2+ are critical therapeutic targets for inflammation-derived neurodegeneration. [ABSTRACT FROM AUTHOR]

Activation of gasdermin D (GSDMD) and its concomitant cardiomyocyte pyroptosis are critically involved in multiple cardiac pathological conditions. Pharmacological inhibition or gene knockout of GSDMD could protect cardiomyocyte from pyroptosis and dysfunction. Thus, seeking and developing highly potent GSDMD inhibitors probably provide an attractive strategy for treating diseases targeting GSDMD. Through structure-based virtual screening, pharmacological screening and subsequent pharmacological validations, we preliminarily identified GSDMD inhibitor Y1 (GI-Y1) as a selective GSDMD inhibitor with cardioprotective effects. Mechanistically, GI-Y1 binds to GSDMD and inhibits lipid- binding and pyroptotic pore formation of GSDMD-N by targeting the Arg7 residue. Importantly, we confirmed the cardioprotective effect of GI-Y1 on myocardial I/R injury and cardiac remodeling by targeting GSDMD. More extensively, GI-Y1 also inhibited the mitochondrial binding of GSDMD-N and its concomitant mitochondrial dysfunction. The findings of this study identified a new drug (GI-Y1) for the treatment of cardiac disorders by targeting GSDMD, and provide a new tool compound for pyroptosis research. [ABSTRACT FROM AUTHOR]

Neutrophils are an important source of interleukin (IL)-1β and other cytokines because they are recruited to sites of infection and inflammation in high numbers. Although secretion of processed, bioactive IL-1β by neutrophils is dependent on NLRP3 and Gasdermin D (GSDMD), IL-1α secretion by neutrophils has not been reported. In this study, we demonstrate that neutrophils produce IL-1α following injection of Aspergillus fumigatus spores that express cell-surface β-glucan. Although IL-1α secretion by lipopolysaccharide (LPS)/ATP-activated macrophages and dendritic cells is GSDMD dependent, IL-1α secretion by β-glucan-stimulated neutrophils occurs independently of GSDMD. Instead, we found that bioactive IL-1α is in exosomes that were isolated from cell-free media of β-glucan-stimulated neutrophils. Further, the exosome inhibitor GW4869 significantly reduces IL-1α in extracellular vesicles (EVs) and total cell-free supernatant. Together, these findings identify neutrophils as a source of IL-1α and demonstrate a role for EVs, specifically exosomes, in neutrophil secretion of bioactive IL-1α.

Abstract Background Ventilator-induced lung injury (VILI) is caused by overdistension of the alveoli by the repetitive recruitment and derecruitment of alveolar units. This study aims to investigate the potential role and mechanism of fibroblast growth factor 21 (FGF21), a metabolic regulator secreted by the liver, in VILI development. Methods Serum FGF21 concentrations were determined in patients undergoing mechanical ventilation during general anesthesia and in a mouse VILI model. Lung injury was compared between FGF21-knockout (KO) mice and wild-type (WT) mice. Recombinant FGF21 was administrated in vivo and in vitro to determine its therapeutic effect. Results Serum FGF21 levels in patients and mice with VILI were significantly higher than in those without VILI. Additionally, the increment of serum FGF21 in anesthesia patients was positively correlated with the duration of ventilation. VILI was aggravated in FGF21-KO mice compared with WT mice. Conversely, the administration of FGF21 alleviated VILI in both mouse and cell models. FGF21 reduced Caspase-1 activity, suppressed the mRNA levels of Nlrp3, Asc, Il-1β, Il-18, Hmgb1 and Nf-κb, and decreased the protein levels of NLRP3, ASC, IL-1β, IL-18, HMGB1 and the cleaved form of GSDMD. Conclusions Our findings reveal that endogenous FGF21 signaling is triggered in response to VILI, which protects against VILI by inhibiting the NLRP3/Caspase-1/GSDMD pyroptosis pathway. These results suggest that boosting endogenous FGF21 or the administration of recombinant FGF21 could be promising therapeutic strategies for the treatment of VILI during anesthesia or critical care.