Gasdermin D deficiency aborts myeloid calcium influx to drive granulopoiesis in lupus nephritis.

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.

Hydrogen sulfide mitigates ox­LDL­induced NLRP3/caspase­1/GSDMD dependent macrophage pyroptosis by S­sulfhydrating caspase­1.

Macrophage pyroptosis mediates vascular inflammation and atherosclerosis (AS). Hydrogen sulfide (H2S) exerts a protective role in preventing inflammation and AS. However, its molecular mechanisms of regulating the pyroptosis signaling pathway and inhibiting macrophage pyroptosis remain unexplored. The present study aimed to determine whether H2S mitigates macrophage pyroptosis by downregulating the pyroptosis signaling pathway and S­sulfhydrating caspase­1 under the stimulation of oxidized low­density lipoprotein (ox­LDL), a pro­atherosclerotic factor. Macrophages derived from THP­1 monocytes were pre­treated using exogenous H2S donors sodium hydrosulfide (NaHS) and D,L­propargylglycine (PAG), a pharmacological inhibitor of endogenous H2S­producing enzymes, alone or in combination. Subsequently, cells were stimulated with ox­LDL or the desulfhydration reagent dithiothreitol (DTT) in the presence or absence of NaHS and/or PAG. Following treatment, the levels of H2S in THP­1 derived macrophages were measured by a methylene blue colorimetric assay. The pyroptotic phenotype of THP­1 cells was observed and evaluated by light microscopy, Hoechst 33342/propidium iodide fluorescent staining and lactate dehydrogenase (LDH) release assay. Caspase­1 activity in THP­1 cells was assayed by caspase­1 activity assay kit. Immunofluorescence staining was used to assess the accumulation of active caspase­1. Western blotting and ELISA were performed to determine the expression of pyroptosis­specific markers (NLRP3, pro­caspase­1, caspase­1, GSDMD and GSDMD­N) in cells and the secretion of pyroptosis­related cytokines [interleukin (IL)­1ß and IL­18] in the cell­free media, respectively. The S­sulfhydration of pro­caspase­1 in cells was assessed using a biotin switch assay. ox­LDL significantly induced macrophage pyroptosis by activating the pyroptosis signaling pathway. Inhibition of endogenous H2S synthesis by PAG augmented the pro­pyroptotic effects of ox­LDL. Conversely, exogenous H2S (NaHS) ameliorated ox­LDL­and ox­LDL + PAG­induced macrophage pyroptosis by suppressing the activation of the pyroptosis signaling pathway. Mechanistically, ox­LDL and the DTT increased caspase­1 activity and downstream events (IL­1ß and IL­18 secretion) of the caspase­1­dependent pyroptosis pathway by reducing S­sulfhydration of pro­caspase­1. Conversely, NaHS increased S­sulfhydration of pro­caspase­1, reducing caspase­1 activity and caspase­1­dependent macrophage pyroptosis. The present study demonstrated the molecular mechanism by which H2S ameliorates macrophage pyroptosis by suppressing the pyroptosis signaling pathway and S­sulfhydration of pro­caspase­1, thereby suppressing the generation of active caspase-1 and activity of caspase-1.

Gasdermin D silencing alleviates airway inflammation and remodeling in an ovalbumin-induced asthmatic mouse model.

Emerging evidence demonstrates that pyroptosis has been implicated in the pathogenesis of asthma. Gasdermin D (GSDMD) is the pyroptosis executioner. The mechanism of GSDMD in asthma remains unclear. The aim of this study was to elucidate the potential role of GSDMD in asthmatic airway inflammation and remodeling. Immunofluorescence staining was conducted on airway epithelial tissues obtained from both asthma patients and healthy controls (HCs) to evaluate the expression level of N-GSDMD. ELISA was used to measure concentrations of cytokines (IL-1ß, IL-18, IL-17A, and IL-10) in serum samples collected from asthma patients and healthy individuals. We demonstrated that N-GSDMD, IL-18, and IL-1ß were significantly increased in samples with mild asthma compared with those from the controls. Then, wild type and Gsdmd-knockout (Gsdmd-/-) mice were used to establish asthma model. We performed histopathological staining, ELISA, and flow cytometry to explore the function of GSDMD in allergic airway inflammation and tissue remodeling in vivo. We observed that the expression of N-GSDMD, IL-18, and IL-1ß was enhanced in OVA-induced asthma mouse model. Gsdmd knockout resulted in attenuated IL-18, and IL-1ß production in both bronchoalveolar lavage fluid (BALF) and lung tissue in asthmatic mice. In addition, Gsdmd-/- mice exhibit a significant reduction in airway inflammation and remodeling, which might be associated with reduced Th17 inflammatory response and M2 polarization of macrophages. Further, we found that GSDMD knockout may improve asthmatic airway inflammation and remodeling through regulating macrophage adhesion, migration, and macrophage M2 polarization by targeting Notch signaling pathway. These findings demonstrate that GSDMD deficiency profoundly alleviates allergic inflammation and tissue remodeling. Therefore, GSDMD may serve as a potential therapeutic target against asthma.

Poking holes in the blood-brain barrier.

Bacterial lipopolysaccharide (LPS) is implicated in disrupting the blood-brain barrier (BBB). In a recent issue of Nature, Wei et al. now show that LPS activates the inflammatory caspases (4, 5, and 11) and gasdermin D (GSDMD) in brain endothelial cells, which triggers their pyroptotic cell death and disrupts the BBB.

The role of inflammasome in chronic viral hepatitis.

Infections of hepatotropic viruses cause a wide array of liver diseases including acute hepatitis, chronic hepatitis and the consequently developed cirrhosis and hepatocellular carcinoma (HCC). Among the five classical hepatotropic viruses, hepatitis B virus (HBV) and hepatitis C virus (HCV) usually infect human persistently and cause chronic hepatitis, leading to major troubles to humanity. Previous studies have revealed that several types of inflammasomes are involved in the infections of HBV and HCV. Here, we summarize the current knowledge about their roles in hepatitis B and C. NLRP3 inflammasome can be activated and regulated by HBV and HCV. It is found to exert antiviral function or mediates inflammatory response in viral infections depending on different experimental models. Besides NLRP3 inflammasome, IFI16 and AIM2 inflammasomes participate in the pathological process of hepatitis B, and NALP3 inflammasome may sense HCV infection in hepatocytes. The inflammasomes affect the pathological process of viral hepatitis through its downstream secretion of inflammatory cytokines interleukin-1ß (IL-1ß) and IL-18 or induction of pyroptosis resulting from cleaved gasdermin D (GSDMD). However, the roles of inflammasomes in different stages of viral infection remains mainly unclear. More proper experimental models of viral hepatitis should be developed for specific studies in future, so that we can understand more about the complexity of inflammasome regulation and multifunction of inflammasomes and their downstream effectors during HBV and HCV infections.

Cardiolipin oxidized by ROS from complex II acts as a target of gasdermin D to drive mitochondrial pore and heart dysfunction in endotoxemia.

Cardiac dysfunction, an early complication of endotoxemia, is the major cause of death in intensive care units. No specific therapy is available at present for this cardiac dysfunction. Here, we show that the N-terminal gasdermin D (GSDMD-N) initiates mitochondrial apoptotic pore and cardiac dysfunction by directly interacting with cardiolipin oxidized by complex II-generated reactive oxygen species (ROS) during endotoxemia. Caspase-4/11 initiates GSDMD-N pores that are subsequently amplified by the upregulation and activation of NLRP3 inflammation through further generation of ROS. GSDMD-N pores form prior to BAX and VDAC1 apoptotic pores and further incorporate into BAX and VDAC1 oligomers within mitochondria membranes to exacerbate the apoptotic process. Our findings identify oxidized cardiolipin as the definitive target of GSDMD-N in mitochondria of cardiomyocytes during endotoxin-induced myocardial dysfunction (EIMD), and modulation of cardiolipin oxidation could be a therapeutic target early in the disease process to prevent EIMD.

Staphylococcus Aureus Membrane Vesicles Kill Tumor Cells Through a Caspase-1-Dependent Pyroptosis Pathway.

Introduction: Nanosized outer membrane vesicles (OMVs) from Gram-negative bacteria have attracted increasing interest because of their antitumor activity. However, the antitumor effects of MVs isolated from Gram-positive bacteria have rarely been investigated. Methods: MVs of Staphylococcus aureus USA300 were prepared and their antitumor efficacy was evaluated using tumor-bearing mouse models. A gene knock-in assay was performed to generate luciferase Antares2-MVs for bioluminescent detection. Cell counting kit-8 and lactic dehydrogenase release assays were used to detect the toxicity of the MVs against tumor cells in vitro. Active caspase-1 and gasdermin D (GSDMD) levels were determined using Western blot, and the tumor inhibition ability of MVs was determined in B16F10 cells treated with a caspase-1 inhibitor. Results: The vesicular particles of S. aureus USA300 MVs were 55.23 ± 8.17 nm in diameter, and 5 µg of MVs remarkably inhibited the growth of B16F10 melanoma in C57BL/6 mice and CT26 colon adenocarcinoma in BALB/c mice. The bioluminescent signals correlated well with the concentrations of the engineered Antares2-MVs (R2 = 0.999), and the sensitivity for bioluminescence imaging was 4 × 10-3 µg. Antares2-MVs can directly target tumor tissues in vivo, and 20 µg/mL Antares2-MVs considerably reduced the growth of B16F10 and CT26 tumor cells, but not non-carcinomatous bEnd.3 cells. MV treatment substantially increased the level of active caspase-1, which processes GSDMD to trigger pyroptosis in tumor cells. Blocking caspase-1 activation with VX-765 significantly protected tumor cells from MV killing in vitro and in vivo. Conclusion: S. aureus MVs can kill tumor cells by activating the pyroptosis pathway, and the induction of pyroptosis in tumor cells is a promising strategy for cancer treatment.

Cutaneous inflammasome driving ASC / gasdermin-D activation and IL-1ß-secreting macrophages in severe atopic dermatitis.

Atopic dermatitis (AD) is an inflammatory skin disease with intense pruritus, and chronic skin colonization by Staphylococcus aureus. To understand the inflammatory status in AD, we investigated the inflammasome complex, that activates ASC (Apoptosis-associated speck-like protein containing a CARD), caspase-1 and GSDMD (gasdermin-D), and production of IL-1ß and IL-18. We aimed to evaluate the expression of the inflammasome pathway in the skin of adults with AD. Thirty patients with moderate to severe AD and 20 healthy controls were enrolled in the study. We performed the analysis of the inflammasome components NLRP1, NLRP3, AIM-2, IL-1ß, IL-18, Caspase-1, ASC, GSDMD, and CD68 expression (macrophage marker) by immunohistochemistry and immunofluorescence. The main findings included increased expression of NLRP3, NLRP1 and AIM-2 at dermal level of severe AD; augmented IL-18 and IL-1ß expression at epidermis of moderate and severe patients, and in the dermis of severe AD; augmented expression of ASC, caspase-1 and GSDMD in both epidermis and dermis of moderate and severe AD. We detected positive correlation between caspase-1, GSDMD and IL-1ß (epidermis) and caspase-1 (dermis) and AD severity; NLRP3, AIM-2 and IL-1ß, and NLRP3 with IL-18 in the epidermis; ASC, GSDMD and IL-1ß, and NLRP3, AIM-2, caspase-1, and IL-18 in the dermis. We also evidenced the presence of CD68+ macrophages secreting GSDMD, ASC and IL-1ß in moderate and severe AD. Cutaneous macrophages, early detected in moderate AD, have its role in the disease inflammatory mechanisms. Our study indicates a canonical activation pathway of inflammasomes, reinforced by the chronic status of inflammation in AD. The analysis of the inflammasome complex evidenced an imbalance in its regulation, with increased expression of the evaluated components, which is remarkably in severe AD, emphasizing its relevance as potential disease biomarkers and targets for immunomodulatory interventions.

Phosphate uptake in PhoX: Molecular mechanisms.

PhoX is a high-affinity phosphate binding protein, present in Xanthomonas citri, a phytopathogen responsible for the citrus canker disease. Performing molecular dynamics simulations and different types of computational analyses, we study the molecular mechanisms at play in relation to phosphate binding, revealing the global functioning of the protein: PhoX naturally oscillates along its global normal modes, which allow it to explore both bound and unbound conformations, eventually attracting a nearby negative phosphate ion to the highly positive electrostatic potential on its surface, particularly close to the binding pocket. There, several hydrogen bonds are formed with the two main domains of the structure. Phosphate creates, in this way, a strong bridge that connects the domains, keeping itself between them, in a tight closed conformation, explaining its high binding affinity.

Inhibition of ROS/caspase-3/GSDME-mediated pyroptosis alleviates high glucose-induced injury in AML-12 cells.

Diabetic liver injury (DLI) is a chronic complication of the liver caused by diabetes, and its has become one of the main causes of nonalcoholic fatty liver disease (NAFLD). The gasdermin E (GSDME)-dependent pyroptosis signaling pathway is involved in various physiological and pathological processes; however, its role and mechanism in DLI are still unknown. This study was performed to investigate the role of GSDME-mediated pyroptosis in AML-12 cell injury induced by high glucose and to evaluate the therapeutic potential of caspase-3 inhibition for DLI. The results showed that high glucose activated apoptosis by regulating the apoptotic protein levels including Bax, Bcl-2, and enhanced cleavage of caspase-3 and PARP. Notably, some of the hepatocytes treated with high glucose became swollen, accompanied by GSDME-N generation, indicating that pyroptosis was further induced by active caspase-3. Moreover, the effects of high glucose on AML-12 cells could be partly reversed by a reactive oxygen scavenger (NAC) and caspase-3 specific inhibitor (Z-DEVD-FMK), which suggests high glucose induced GSDME-dependent pyroptosis in AML-12 cells through increasing ROS levels and activating caspase-3. In conclusion, our results show that high glucose can induce pyroptosis in AML-12 cells, at least in part, through the ROS/caspase-3/GSDME pathway，and inhibition of caspase-3 can ameliorate high glucose-induced hepatocyte injury, providing an important basis for clarifying the pathogenesis and treatment of DLI.

Degrasyn alleviates osteoarthritis by blocking macrophagic pyroptosis via suppressing NLRP3/GSDMD signaling pathway and protecting chondrocytes.

Synovitis and cartilage destruction are crucial characteristics of osteoarthritis (OA). Inflammatory cytokines, such as IL-1ß, are secreted by synovial macrophages, leading to cartilage destruction. Pyroptosis is a lytic form of programmed cell death, which could be triggered by the NLRP3 inflammasome of macrophages. Pyroptosis promotes the secretion of IL-1ß and is supposed as a potential biomarker for OA. However, the function of Pyroptosis and NLRP3 inflammasome and its regulatory mechanism for activation is unclear in OA. In this study, we found that Degrasyn could alleviate the GSDMD-mediated pyroptosis of macrophages and the release of IL-1ß, caspase-1, and LDH. Furthermore, it selectively impedes the form of ASC oligomer and speckle to effectively suppress the NLRP3 inflammasome during its assembly phase. Notably, Degrasyn exhibited potential chondroprotective effects in a co-culture system. Additionally, these results also indicate that Degrasyn mitigates synovitis and cartilage damage in a murine model of destabilization of the medial meniscus (DMM)-induced OA. In summary, Degrasyn emerges as a promising pharmaceutical agent for synovitis, paving the way for innovative therapeutic approaches to OA. Our findings underscore the potential of Degrasyn as a viable candidate for OA therapeutics, demonstrating its ability to regulate pyroptosis and NLRP3 inflammasome activation.

Baicalin attenuates acute skin damage induced by ultraviolet B via inhibiting pyroptosis.

As the outermost layer of the human body, the skin suffers from various external factors especially light damage, among which ultraviolet B (UVB) irradiation is common and possesses a relatively high biological damage capacity. Pyroptosis is a newly discovered type of programmed cell death, which can induce cell rupture and induce local inflammatory response. However, the molecular mechanisms of pyroptosis in photodamaged skin is poorly understood. Baicalin, a flavonoid extracted from the desiccated root of Scutellaria baicalensis Georgi (Huang Qin). Despite its antioxidant abilities, whether baicalin protects skin by attenuating UVB-induced pyroptosis remains unclear, which was the aim of this study. The UVB-induced acute skin damage model was established by using human immortalized keratinocytes (HaCaT cells) and Kunming (KM) strain mice. The protective dose selection for baicalin is 50 µM in vitro and 100 mg/kg in vivo. In in vitro study, UVB irradiation significantly decreased cell viability, increased cell death and oxidative stress in HaCaT cells, while pretreatment with baicalin improved these phenomena. Furthermore, the baicalin pretreatment notably suppressed nuclear factor kappa B (NF-κB) translocation, the NLRP3 inflammasome activation and gasdermin D (GSDMD) maturation, thus effectively attenuating UVB-induced pyroptosis. In in vivo study, the baicalin pretreatment mitigated epidermal hyperplasia, collagen fiber fragmentation, oxidative stress and pyroptosis in UVB-irradiated mouse skin. In a nutshell, this study suggests that baicalin could be a potential protective agent to attenuate acute skin damage induced by UVB irradiation through decreasing oxidative stress and suppressing NF-κB/NLRP3/GSDMD-involved pyroptosis.

BRCA1 safeguards genome integrity by activating chromosome asynapsis checkpoint to eliminate recombination-defective oocytes.

In the meiotic prophase, programmed DNA double-strand breaks are repaired by meiotic recombination. Recombination-defective meiocytes are eliminated to preserve genome integrity in gametes. BRCA1 is a critical protein in somatic homologous recombination, but studies have suggested that BRCA1 is dispensable for meiotic recombination. Here we show that BRCA1 is essential for meiotic recombination. Interestingly, BRCA1 also has a function in eliminating recombination-defective oocytes. Brca1 knockout (KO) rescues the survival of Dmc1 KO oocytes far more efficiently than removing CHK2, a vital component of the DNA damage checkpoint in oocytes. Mechanistically, BRCA1 activates chromosome asynapsis checkpoint by promoting ATR activity at unsynapsed chromosome axes in Dmc1 KO oocytes. Moreover, Brca1 KO also rescues the survival of asynaptic Spo11 KO oocytes. Collectively, our study not only unveils an unappreciated role of chromosome asynapsis in eliminating recombination-defective oocytes but also reveals the dual functions of BRCA1 in safeguarding oocyte genome integrity.

Gasdermin D palmitoylation: to cleave or not to cleave?

Recent studies have identified Cys191 in gasdermin D (GSDMD) as a highly targeted regulatory module controlling pyroptosis. Using chemical biology and genetic models, Du, Healy et al. recently identified GSDMD palmitoylation as a key regulatory step in GSDMD activation.

GSDMD in regulated cell death: A novel therapeutic target for sepsis.

Sepsis is a life-threatening multi-organ dysfunction syndrome caused by an abnormal host response to infection. Regulated cell death is essential for maintaining tissue homeostasis and eliminating damaged, infected, or aging cells in multicellular organisms. Gasdermin D, as a member of the gasdermin family, plays a crucial role in the formation of cytoplasmic membrane pores. Research has found that GSDMD plays important roles in various forms of regulated cell death such as pyroptosis, NETosis, and necroptosis. Therefore, through mediating regulated cell death, GSDMD regulates different stages of disease pathophysiology. This article mainly summarizes the concept of GSDMD, its role in regulated cell death, its involvement in organ damage associated with sepsis-related injuries mediated by regulated cell death via GSDMD activation and introduces potential drugs targeting GSDMD that may provide more effective treatment options for sepsis patients through drug modification.

Oxidative photocatalysis on membranes triggers non-canonical pyroptosis.

Intracellular membranes composing organelles of eukaryotes include membrane proteins playing crucial roles in physiological functions. However, a comprehensive understanding of the cellular responses triggered by intracellular membrane-focused oxidative stress remains elusive. Herein, we report an amphiphilic photocatalyst localised in intracellular membranes to damage membrane proteins oxidatively, resulting in non-canonical pyroptosis. Our developed photocatalysis generates hydroxyl radicals and hydrogen peroxides via water oxidation, which is accelerated under hypoxia. Single-molecule magnetic tweezers reveal that photocatalysis-induced oxidation markedly destabilised membrane protein folding. In cell environment, label-free quantification reveals that oxidative damage occurs primarily in membrane proteins related to protein quality control, thereby aggravating mitochondrial and endoplasmic reticulum stress and inducing lytic cell death. Notably, the photocatalysis activates non-canonical inflammasome caspases, resulting in gasdermin D cleavage to its pore-forming fragment and subsequent pyroptosis. These findings suggest that the oxidation of intracellular membrane proteins triggers non-canonical pyroptosis.

Prognostic and chemotherapeutic implications of a novel four-gene pyroptosis model in head and neck squamous cell carcinoma.

Background: Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers. Chemotherapy remains one dominant therapeutic strategy, while a substantial proportion of patients may develop chemotherapeutic resistance; therefore, it is particularly significant to identify the patients who could achieve maximum benefits from chemotherapy. Presently, four pyroptosis genes are reported to correlate with the chemotherapeutic response or prognosis of HNSCC, while no study has assessed the combinatorial predicting efficacy of these four genes. Hence, this study aims to evaluate the predictive value of a multi-gene pyroptosis model regarding the prognosis and chemotherapeutic responsiveness in HNSCC. Methods: By utilizing RNA-sequencing data from The Cancer Genome Atlas database and the Gene Expression Omnibus database, the pyroptosis-related gene score (PRGscore) was computed for each HNSCC sample by performing a Gene Set Variation Analysis (GSVA) based on four genes (Caspase-1, Caspase-3, Gasdermin D, Gasdermin E). The prognostic significance of the PRGscore was assessed through Cox regression and Kaplan-Meier survival analyses. Additionally, chemotherapy sensitivity stratified by high and low PRGscore was examined to determine the potential association between pyroptosis activity and chemosensitivity. Furthermore, chemotherapy sensitivity assays were conducted in HNSCC cell lines in vitro. Results: As a result, our study successfully formulated a PRGscore reflective of pyroptotic activity in HNSCC. Higher PRGscore correlates with worse prognosis. However, patients with higher PRGscore were remarkably more responsive to chemotherapy. In agreement, chemotherapy sensitivity tests on HNSCC cell lines indicated a positive association between overall pyroptosis levels and chemosensitivity to cisplatin and 5-fluorouracil; in addition, patients with higher PRGscore may benefit from the immunotherapy. Overall, our study suggests that HNSCC patients with higher PRGscore, though may have a less favorable prognosis, chemotherapy and immunotherapy may exhibit better benefits in this population.

Macrophage-Derived GSDMD Plays an Essential Role in Atherosclerosis and Cross Talk Between Macrophages via the Mitochondria-STING-IRF3/NF-κB Axis.

BACKGROUND: Macrophages play a crucial role in atherosclerotic plaque formation, and the death of macrophages is a vital factor in determining the fate of atherosclerosis. GSDMD (gasdermin D)-mediated pyroptosis is a programmed cell death, characterized by membrane pore formation and inflammatory factor release. METHODS: ApoE-/- and Gsdmd-/- ApoE-/- mice, bone marrow transplantation, and AAV (adeno-associated virus serotype 9)-F4/80-shGSDMD (shRNA-GSDMD) were used to examine the effect of macrophage-derived GSDMD on atherosclerosis. Single-cell RNA sequencing was used to investigate the changing profile of different cellular components and the cellular localization of GSDMD during atherosclerosis. RESULTS: First, we found that GSDMD is activated in human and mouse atherosclerotic plaques and Gsdmd-/- attenuates the atherosclerotic lesion area in high-fat diet-fed ApoE-/- mice. We performed single-cell RNA sequencing of ApoE-/- and Gsdmd-/- ApoE-/- mouse aortas and showed that GSDMD is principally expressed in atherosclerotic macrophages. Using bone marrow transplantation and AAV-F4/80-shGSDMD, we identified the potential role of macrophage-derived GSDMD in aortic pyroptosis and atherosclerotic injuries in vivo. Mechanistically, GSDMD contributes to mitochondrial perforation and mitochondrial DNA leakage and subsequently activates the STING (stimulator of interferon gene)-IRF3 (interferon regulatory factor 3)/NF-κB (nuclear factor kappa B) axis. Meanwhile, GSDMD regulates the STING pathway activation and macrophage migration via cytokine secretion. Inhibition of GSDMD with GSDMD-specific inhibitor GI-Y1 (GSDMD inhibitor Y1) can effectively alleviate the progression of atherosclerosis. CONCLUSIONS: Our study has provided a novel macrophage-derived GSDMD mechanism in the promotion of atherosclerosis and demonstrated that GSDMD can be a potential therapeutic target for atherosclerosis.

Periplogenin inhibits pyroptosis of fibroblastic synoviocytes in rheumatoid arthritis through the NLRP3/Caspase-1/GSDMD signaling pathway.

Although the pathogenesis of rheumatoid arthritis (RA) remains unclear, an increasing number of studies have confirmed that pyroptosis of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) is an important factor affecting the progression of RA. Periplogenin (PPN) is a natural cardiac glycoside; reportedly, it exerts anti-inflammatory and analgesic effects in diseases by inhibiting cell growth and migration. This study aimed to determine the effect of PPN on the growth, migration, and invasion of RA-FLS and the potential mechanism of pyroptosis regulation. We discovered that PPN could inhibit the migration and invasion abilities of RA-FLS and block their growth cycle, down-regulate the secretion and activation of NLRP3, Caspase-1, GSDMD, IL-1ß, and IL-18, and reduce the number of pyroptosis. In summary, PPN inhibited pyroptosis, reduced the release of inflammatory factors, and improved RA-FLS inflammation by regulating the NLRP3/Caspase-1/GSDMD signaling pathway.

Intraepithelial mast cells drive gasdermin C-mediated type 2 immunity.

A specialized population of mast cells residing within epithelial layers, currently known as intraepithelial mast cells (IEMCs), was originally observed over a century ago, yet their physiological functions have remained enigmatic. In this study, we unveil an unexpected and crucial role of IEMCs in driving gasdermin C-mediated type 2 immunity. During helminth infection, αEß7 integrin-positive IEMCs engaged in extensive intercellular crosstalk with neighboring intestinal epithelial cells (IECs). Through the action of IEMC-derived proteases, gasdermin C proteins intrinsic to the epithelial cells underwent cleavage, leading to the release of a critical type 2 cytokine, interleukin-33 (IL-33). Notably, mast cell deficiency abolished the gasdermin C-mediated immune cascade initiated by epithelium. These findings shed light on the functions of IEMCs, uncover a previously unrecognized phase of type 2 immunity involving mast cell-epithelial cell crosstalk, and advance our understanding of the cellular mechanisms underlying gasdermin C activation.