Activation Of Inflammatory Caspases Research Articles

Inflammasomes at the Foundation of Inflammatory Cell Death Complexes.

This Pillars of Immunology article is a commentary on “The Inflammasome: A Molecular Platform Triggering Activation of Inflammatory Caspases and Processing of proIL-β,” a pivotal article written by F. Martinon, K. Burns, and J. Tschopp, published in Molecular Cell in 2002. https://doi.org/10.1016/S1097-2765(02)00599-3.

Distinct sequential death complexes regulate pyroptosis and IL-1β release in response to Yersinia blockade of immune signaling.

Pathogen infection of host cells triggers an inflammatory cell death termed pyroptosis via activation of inflammatory caspases. However, blockade of immune signaling kinases by the Yersinia virulence factor YopJ triggers cell death involving both apoptotic caspase-8 and pyroptotic caspase-1. While caspase-1 is normally activated within inflammasomes, Yersinia-induced caspase-1 activation is independent of known inflammasome components. We report that caspase-8 is an essential initiator, while caspase-1 is an essential amplifier of its own activation through two feed-forward loops involving caspase-1 auto-processing and caspase-1-dependent activation of gasdermin D and NLPR3. Notably, while Yersinia-induced caspase-1 activation and cell death are inflammasome-independent, IL-1β release requires NLPR3 inflammasome activation. Mechanistically, caspase-8 is rapidly activated within multiple foci throughout the cell, followed by assembly of a canonical inflammasome speck, indicating that caspase-8 and canonical inflammasome complex assemblies are kinetically and spatially distinct. Our findings reveal that functionally interconnected but distinct death complexes mediate pyroptosis and IL-1β release in response to pathogen blockade of immune signaling.

African swine fever virus infection regulates pyroptosis by cleaving gasdermin A via active caspase-3 and caspase-4

African swine fever (ASF), caused by the African swine fever virus (ASFV), is a viral hemorrhagic disease that affects domestic pigs and wild boars. ASFV infection causes extensive tissue damage, and the associated mechanism is poorly understood. Pyroptosis is characterized by the activation of inflammatory caspases and pore formation in the cellular plasma membrane, resulting in the release of inflammatory cytokines and cell damage. How ASFV infection regulates pyroptosis remains unclear. Here, using small interfering RNA assay and overexpression methods, we report that ASFV infection regulated pyroptosis by cleaving the pyroptosis execution protein gasdermin A (GSDMA). ASFV infection activated caspase-3 and caspase-4, which specifically cleaved GSDMA at D75-P76 and D241-V242 to produce GSDMA into five fragments, including GSDMA-N1-75, GSDMA-N1-241, and GSDMA-N76-241 fragments at the N terminal end of GSDMA. Only GSDMA-N1-241, which was produced in the late stage of ASFV infection, triggered pyroptosis and inhibited ASFV replication. The fragments GSDMA-N1-75 and GSDMA-N76-241 lose the ability to induce pyroptosis. Overall ASFV infection differentially regulates pyroptosis by GSDMA in the indicated phase, which may be conducive to its own replication. Our findings reveal a novel molecular mechanism for the regulation of pyroptosis.

Mechanisms of Inflammatory Caspase Activation in Sickle Cell Disease

Background: Sickle cell disease (SCD) is an inherited red blood cell disorder that impacts millions of people worldwide. Patients with SCD experience chronic hemolysis and have elevated serum levels of free heme. Free heme activates a variety of inflammatory pathways that contribute to the serious clinical complications of SCD. One of the inflammatory pathways activated by heme is the inflammatory caspase pathway. Our lab previously showed that heme exposure in macrophages leads to the activation of inflammatory caspase proteins caspase-1 and caspase-4. Activation of these proteins by heme leads to IL-1β release and pyroptosis, a form of inflammatory cell death. Patients with SCD have increased circulating IL-1β levels, indicating this pathway is active in patients. In mouse models, inflammatory caspases are required for hemolysis-induced neutrophil recruitment and lethality, indicating these proteins are central to hemolysis-induced inflammation. Despite the key role these proteins play following hemolysis, it remains unknown how heme activates inflammatory caspases. Interestingly, both caspase-1 and caspase-4 are required for heme-induced IL-1β release while caspase-4 alone is required for heme-induced pyroptosis. In fact, pyroptosis likely is required for IL-1β release from the cell. Based on this data, we hypothesized that caspase-4 is the apical step in this pathway and a key druggable target for controlling unchecked inflammation in SCD. Results: We first sought to determine if caspase-4 activation is upstream of caspase-1 activation. To assess this, we used an imaging-based caspase activation reporter assay. Using this system, we found that siRNA knock-down of caspase-4 in primary human macrophages significantly inhibited heme-induced caspase-1 activation (63.8% vs 26.3%, n =4, p = 0.015). This result shows that caspase-4 is upstream of heme-induced caspase-1 activation and confirmed caspase-4 activation is the initial step in this pathway. Next, we sought to determine how caspase-4 activation occurs. Other known activators of caspase-4 induce activation by directly binding to caspase-4 and inducing self-oligomerization. To determine if heme acts in a similar manner, we used a published heme-binding prediction algorithm called HeMoQuest. We found multiple predicted heme-binding sites in caspase-4. The dissociation constants for these binding sites are less than 1 µM, suggesting strong binding affinity. Importantly, there are no predicted heme binding sites in caspase-1, indicating caspase-4 is the only direct heme receptor in this pathway. To validate these binding predictions, we performed molecular docking experiments and confirmed there are multiple heme-binding sites in caspase-4. Specifically, we found two heme-binding regions in the p10 catalytic subunit of caspase-4 comprising 2-4 essential residues. We next confirmed that heme directly interacts with caspase-4 in vitro. Using a pull-down assay with heme conjugated to agarose beads, we observed heme bound to purified caspase-4 and to casapase-4 in macrophage cell-free extracts. Heme did not interact with proteins structurally related to caspase-4 including caspase-1, caspase-7, and caspase-9 and caspase-4 was not pulled down by control agarose. This confirms the specificity of the heme-caspase-4 interaction. To determine if heme binding to caspase-4 results in activation, we performed native PAGE analysis of purified caspase-4 after exposure to heme. Heme induced formation of a caspase-4 oligomer around 200 kDa in size, four-fold larger than the inactive caspase-4 monomer. Other compounds known to induce IL-1β release from cells, like microbial toxin nigericin, did not induce caspase-4 oligomerization, demonstrating the specificity of heme's effect on caspase-4. Conclusions: We have determined that caspase-4 is a direct intracellular heme receptor and that heme exposure leads to caspase-4 activation, which in turn facilitates caspase-1 activation, IL-1β release and cell death. Our future work will elucidate the functional effects of heme binding to caspase-4 in mouse models of sickle cell disease. Caspase-4 is an attractive therapeutic target as it is required for both functional outputs of inflammatory caspase activation, IL-1β release and pyroptosis. Inhibiting heme-caspase-4 interactions would provide a specific way to block the harmful effects of this pathway in patients.

Collab or Cancel? Bacterial Influencers of Inflammasome Signaling.

The immune system of multicellular organisms protects them from harmful microbes. To establish an infection in the face of host immune responses, pathogens must evolve specific strategies to target immune defense mechanisms. One such defense is the formation of intracellular protein complexes, termed inflammasomes, that are triggered by the detection of microbial components and the disruption of homeostatic processes that occur during bacterial infection. Formation of active inflammasomes initiates programmed cell death pathways via activation of inflammatory caspases and cleavage of target proteins. Inflammasome-activated cell death pathways such as pyroptosis lead to proinflammatory responses that protect the host. Bacterial infection has the capacity to influence inflammasomes in two distinct ways: activation and perturbation. In this review, we discuss how bacterial activities influence inflammasomes, and we discuss the consequences of inflammasome activation or evasion for both the host and pathogen.

CoQ10 alleviates hepatic ischemia reperfusion injury via inhibiting NLRP3 activity and promoting Tregs infiltration.

Hepatic ischemia-reperfusion injury (IRI) has been concerned as a main complication of liver surgery and transplantation. Previous studies show that reactive oxygen species (ROS) associated inflammation response and contribute to the liver damage during IRI. Coenzyme Q10 (CoQ10) has shown many beneficial effects on abrogating ROS production and ameliorating liver injury. This study found lower CoQ10 level in the process of liver IRI in a mouse model of hepatic IRI. Meanwhile, our results showed that CoQ10 administration significantly attenuate hepatic IRI proved by HE staining, serum ALT/AST. The NOD-like receptor protein 3 (NLRP3) inflammasome is activated by ROS which triggers the activation of inflammatory caspases. In this study, NLRP3 was significantly suppressed by CoQ10 while Foxp3 exhibited increased expression in liver. Furthermore, Kupffer cells (KCs) pretreated with CoQ10 under the condition of hypoxia and reoxygenation contributed to improved CD4+CD25+Foxp3+ regulatory T cells (Tregs) ratio in co-culture system. Furthermore, NLRP3 inflammasome activator treatment in vivo resulted in higher expression of caspase-1 and NLRP3 and reduction of Tregs in liver, which reversed the protection of CoQ10 in the liver injury. Taken together, our study discovered that CoQ10 can suppress NLRP3 activity in KCs and improves Foxp3+ Tregs differentiation depending on M2 macrophage polarization of KCs to ameliorate hepatic IRI.

Cancer-associated pyroptosis: A new license to kill tumor.

Pyroptosis is a programmed necrotic cell death mediated by pore-forming Gasdermin (GSDM) proteins. After being unleashed from the C-terminal auto-inhibitory domains by proteolytic cleavage, the N-terminal domains of GSDMs oligomerize and perforate on the plasma membrane to induce cytolytic pyroptosis, releasing immune mediators and alarming the immune system. Upon infection or danger signal perception, GSDMD that functions downstream of the inflammasome, a supramolecular complex for inflammatory caspase activation, is cleaved and activated by inflammasome-activated caspase-1/4/5/11 in immune cells and epithelial cells to trigger pyroptosis and exert anti-infection protection. Unlike this inflammasome-activated pyroptosis (IAP), recent studies also suggest an emerging role of cancer-associated pyroptosis (CAP), mediated by other GSDMs in cancer cells, in provoking anti-tumor immunity. IAP and CAP share common features like cell membrane rupture but also differ in occurrence sites, activating mechanisms, secreting cytokines and biological outcomes. Here we review the most recent knowledge of cancer-associated pyroptosis and present a promising avenue for developing therapeutic interventions to enhance anti-tumor immunity for cancer treatment.

Monitoring Calcium Fluxes and Lysosome Exocytosis During Pyroptosis.

Inflammasome-mediated activation of inflammatory caspases (caspase-1, caspase-4, caspase-5, caspase-11) initiates a cascade of cellular events that lead to proinflammatory cell death, or pyroptosis. Proteolytic cleavage of gasdermin D results in the formation of transmembrane pores that allow the release of mature cytokines IL-1β and IL-18. Gasdermin pores also allow calcium influx through the plasma membrane, triggering the fusion of lysosomal compartments with the cell surface and release of their contents into the extracellular milieu in a process termed lysosome exocytosis. This chapter outlines methods for measuring calcium flux, lysosome exocytosis, and membrane disruption after inflammatory caspase activation.

Molecular Characteristics of Cell Pyroptosis and Its Inhibitors: A Review of Activation, Regulation, and Inhibitors.

Pyroptosis is an active and ordered form of programmed cell death. The signaling pathways of pyroptosis are mainly divided into canonical pathways mediated by caspase-1 and noncanonical pathways mediated by caspase-11. Cell pyroptosis is characterized by the activation of inflammatory caspases (mainly caspase-1, 4, 5, 11) and cleavage of various members of the Gasdermin family to form membrane perforation components, leading to cell membrane rupture, inflammatory mediators release, and cell death. Moderate pyroptosis is an innate immune response that fights against infection and plays an important role in the occurrence and development of the normal function of the immune system. However, excessive pyroptosis occurs and leads to immune disorders in many pathological conditions. Based on canonical pathways, research on pyroptosis regulation has demonstrated several pyroptotic inhibitors, including small-molecule drugs, natural products, and formulations of traditional Chinese medicines. In this paper, we review the characteristics and molecular mechanisms of pyroptosis, summarize inhibitors of pyroptosis, and propound that herbal medicines should be a focus on the research and development for pyroptosis blockers.

Molecular mechanisms and roles of pyroptosis in acute lung injury.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which are characterized by excessive inflammation and accompanied by diffuse injury of alveoli, can result in severe respiratory failures. The morbidity and mortality of patients remain high because the major treatments for ALI/ARDS are mainly supportive due to the lack of effective therapies. Numerous studies have demonstrated that the aggravation of coronavirus disease 2019 (COVID-19) leads to severe pneumonia and even ARDS. Pyroptosis, a biological process identified as a type of programed cell death, is mainly triggered by inflammatory caspase activation and is directly meditated by the gasdermin protein family, as well as being associated with the secretion and release of pro-inflammatory cytokines. Clinical and experimental evidence corroborates that pyroptosis of various cells in the lung, such as immune cells and structural cells, may play an important role in the pathogenesis of "cytokine storms" in ALI/ARDS, including those induced by COVID-19. Here, with a focus on ALI/ARDS and COVID-19, we summarized the recent advances in this field and proposed the theory of an inflammatory cascade in pyroptosis to identify new targets and pave the way for new approaches to treat these diseases.

NOD1 and NOD2 Are Potential Therapeutic Targets for Cancer Immunotherapy.

The nucleotide oligomerization domain (NOD)-like receptors (NLRs) are a group of intracellular proteins that are essential for controlling the host's innate immune response. The cytosolic nucleotide binding oligomerization domains 1 and 2 receptors (NOD1 and NOD2) are the most widely investigated NLRs. As pattern recognition receptors (PRRs), NOD1 and NOD2 may recognize and bind endogenous damage associated molecular patterns (DAMPs) and external pathogenic associated molecular patterns (PAMPs), directing the activation of inflammatory caspases through engaging the adaptor protein RIP2, which further activates the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways, thereby mediating host innate immunity and regulating the adaptive immunity. Previous research has identified NOD1 and NOD2 as key players in inflammatory disease and host-microbial defense. Despite numerous studies claiming that NOD1 and NOD2 are linked to tumorigenesis and tumor development, it is still unclear whether NOD1 and NOD2 act as cancer's friends or foes. In this review, we focus on concluding the current research progress on the role of NOD1 and NOD2 in a variety of cancers and discussing the potential reasons for the contradicting role of NOD1 and NOD2 in cancers. This review may help better understand the role of NOD1 and NOD2 in cancer and shed light on NOD1 and NOD2 as potential therapeutic targets for tumor immunotherapy.

Connexins, Pannexins and Gap Junctions in Perinatal Brain Injury.

Perinatal brain injury secondary to hypoxia-ischemia and/or infection/inflammation remains a major cause of disability. Therapeutic hypothermia significantly improves outcomes, but in randomized controlled trials nearly half of infants still died or survived with disability, showing that additional interventions are needed. There is growing evidence that brain injury spreads over time from injured to previously uninjured regions of the brain. At least in part, this spread is related to opening of connexin hemichannels and pannexin channels, both of which are large conductance membrane channels found in many brain cells. Opening of these membrane channels releases adenosine triphosphate (ATP), and other neuroactive molecules, into the extracellular space. ATP has an important role in normal signaling, but pathologically can trigger the assembly of the multi-protein inflammasome complex. The inflammasome complex promotes activation of inflammatory caspases, and release of inflammatory cytokines. Overall, the connexin hemichannel appears to play a primary role in propagation of injury and chronic disease, and connexin hemichannel blockade has been shown to be neuroprotective in multiple animal models. Thus, there is potential for some blockers of connexin or pannexin channels to be developed into targeted interventions that could be used in conjunction with or separate to therapeutic hypothermia.

Caspase-4 and -5 Biology in the Pathogenesis of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disease of the gastrointestinal tract, associated with high levels of inflammatory cytokine production. Human caspases-4 and -5, and their murine ortholog caspase-11, are essential components of the innate immune pathway, capable of sensing and responding to intracellular lipopolysaccharide (LPS), a component of Gram-negative bacteria. Following their activation by LPS, these caspases initiate potent inflammation by causing pyroptosis, a lytic form of cell death. While this pathway is essential for host defence against bacterial infection, it is also negatively associated with inflammatory pathologies. Caspases-4/-5/-11 display increased intestinal expression during IBD and have been implicated in chronic IBD inflammation. This review discusses the current literature in this area, identifying links between inflammatory caspase activity and IBD in both human and murine models. Differences in the expression and functions of caspases-4, -5 and -11 are discussed, in addition to mechanisms of their activation, function and regulation, and how these mechanisms may contribute to the pathogenesis of IBD.

Gasdermin D mediates doxorubicin-induced cardiomyocyte pyroptosis and cardiotoxicity via directly binding to doxorubicin and changes in mitochondrial damage

Doxorubicin (Dox), as a widely used anthracycline antitumor drug, can cause severe cardiotoxicity. Cardiomyocyte death and inflammation are involved in the pathophysiology of Dox-induced cardiotoxicity (DIC). Gasdermin D (GSDMD) is known as a key executioner of pyroptosis, which is a pro-inflammatory programmed cell death. We aimed to investigate the impact of GSDMD on DIC and systematically reveal its underlying mechanisms. Our findings indicated that Dox induced cardiomyocyte pyroptosis in a GSDMD-dependent manner by utilizing siRNA or overexpression-plasmid technique. We then generated GSDMD global knockout mice via CRISPR/Cas9 system and found that GSDMD deficiency reduced Dox-induced cardiomyopathy. Dox induced the activation of inflammatory caspases, which subsequently mediated GSDMD-N generation indirectly. Using molecular dynamics simulation and cell-free systems, we confirmed that Dox directly bound to GSDMD and facilitated GSDMD-N-mediated pyroptosis. Furthermore, GSDMD also mediated Dox-induced mitochondrial damage via Bnip3 and mitochondrial perforation in cardiomyocytes. These findings provide fresh insights into the mechanism of how Dox-engaged GSDMD orchestrates adverse cardiotoxicity and highlight the prospects of GSDMD as a potential target for DIC.

Inflammasomes in Cancer Progression and Anti-Tumor Immunity.

The inflammasomes are critical regulators of innate immunity, inflammation and cell death and have emerged as important regulators of cancer development and control. Inflammasomes are assembled by pattern recognition receptors (PRR) following the sensing of microbial- or danger-associated molecular patterns (MAMPs/DAMPs) and elicit inflammation through the oligomerization and activation of inflammatory caspases. These cysteinyl-aspartate proteases cleave the proinflammatory cytokines IL-1β and IL-18 into their biologically active mature form. The roles of the inflammasomes and associated pro-inflammatory cytokines vary greatly depending on the cancer type. Here we discuss recent studies highlighting contrasting roles of the inflammasome pathway in curbing versus promoting tumorigenesis. On one hand, the inflammasomes participate in stimulating anti-tumor immunity, but they have also been shown to contribute to immunosuppression or to directly promote tumor cell survival, proliferation, and metastasis. A better understanding of inflammasome functions in different cancers is thus critical for the design of novel cancer immunotherapies.

Visualization of Inflammatory Caspases Induced Proximity in Human Monocyte-Derived Macrophages.

Inflammatory caspases include caspase-1, -4, -5, -11, and -12 and belong to the subgroup of initiator caspases. Caspase-1 is required to ensure correct regulation of inflammatory signaling and is activated by proximity-induced dimerization following recruitment to inflammasomes. Caspase-1 is abundant in the monocytic cell lineage and induces maturation of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 to active secreted molecules. The other inflammatory caspases, caspase-4 and -5 (and their murine homolog caspase-11) promote IL-1β release by inducing pyroptosis. Caspase Bimolecular Fluorescence Complementation (BiFC) is a tool used to measure inflammatory caspase induced proximity as a readout of caspase activation. The caspase-1, -4, or -5 prodomain, which contains the region that binds to the inflammasome, is fused to non-fluorescent fragments of the yellow fluorescent protein Venus (Venus-N [VN] or Venus-C [VC]) that associate to reform the fluorescent Venus complex when the caspases undergo induced proximity. This protocol describes how to introduce these reporters into primary human monocyte-derived macrophages (MDM) using nucleofection, treat the cells to induce inflammatory caspase activation, and measure caspase activation using fluorescence and confocal microscopy. The advantage of this approach is that it can be used to identify the components, requirements, and localization of the inflammatory caspase activation complex in living cells. However, careful controls need to be considered to avoid compromising cell viability and behavior. This technique is a powerful tool for the analysis of dynamic caspase interactions at the inflammasome level as well as for the interrogation of the inflammatory signaling cascades in living MDM and monocytes derived from human blood samples.

Inflammatory Caspase Activity Mediates HMGB1 Release and Differentiation in Myoblasts Affected by Peripheral Arterial Disease.

Introduction: We previously showed that caspase-1 and -11, which are activated by inflammasomes, mediate recovery from muscle ischemia in mice. We hypothesized that similar to murine models, inflammatory caspases modulate myogenicity and inflammation in ischemic muscle disease. Methods: Caspase activity was measured in ischemic and perfused human myoblasts in response to the NLRP3 and AIM2 inflammasome agonists (nigericin and poly(dA:dT), respectively) with and without specific caspase-1 or pan-caspase inhibition. mRNA levels of myogenic markers and caspase-1 were assessed, and protein levels of caspases-1, -4, -5, and -3 were measured by Western blot. Results: When compared to perfused cells, ischemic myoblasts demonstrated attenuated MyoD and myogenin and elevated caspase-1 mRNA. Ischemic myoblasts also had significantly higher enzymatic caspase activity with poly(dA:dT) (p < 0.001), but not nigericin stimulation. Inhibition of caspase activity including caspase-4/-5, but not caspase-1, blocked activation effects of poly(dA:dT). Ischemic myoblasts had elevated cleaved caspase-5. Inhibition of caspase activity deterred differentiation in ischemic but not perfused myoblasts and reduced the release of HMGB1 from both groups. Conclusion: Inflammatory caspases can be activated in ischemic myoblasts by AIM2 and influence ischemic myoblast differentiation and release of pro-angiogenic HMGB1. AIM2 inflammasome involvement suggests a role as a DNA damage sensor, and our data suggest that caspase-5 rather than caspase-1 may mediate the downstream mediator of this pathway.

Staphylococcus aureus mediates pyroptosis in bovine mammary epithelial cell via activation of NLRP3 inflammasome

Cell death and inflammation are intimately linked during mastitis due to Staphylococcus aureus (S. aureus). Pyroptosis, a programmed necrosis triggered by gasdermin protein family, often occurs after inflammatory caspase activation. Many pathogens invade host cells and activate cell-intrinsic death mechanisms, including pyroptosis, apoptosis, and necroptosis. We reported that bovine mammary epithelial cells (MAC-T) respond to S. aureus by NOD-like receptor protein 3 (NLRP3) inflammasome activation through K+ efflux, leading to the recruitment of apoptosis-associated speck-like protein (ASC) and the activation of caspase-1. The activated caspase-1 cleaves gasdermin D (GSDMD) and forms a N-terminal pore forming domain that drives swelling and membrane rupture. Membrane rupture results in the release of the pro-inflammatory cytokines IL-18 and IL-1β, which are activated by caspase-1. Can modulate GSDMD activation by NLRP3-dependent caspase-1 activation and then cause pyroptosis of bovine mammary epithelial cells.

Inflammatory Caspases: Toward a Unified Model for Caspase Activation by Inflammasomes.

Inflammasomes are inflammatory signaling complexes that provide molecular platforms to activate the protease function of inflammatory caspases. Caspases-1, -4, -5, and -11 are inflammatory caspases activated by inflammasomes to drive lytic cell death and inflammatory mediator production, thereby activating host-protective and pathological immune responses. Here, we comprehensively review the mechanisms that govern the activity of inflammatory caspases. We discuss inflammatory caspase activation and deactivation mechanisms, alongside the physiological importance of caspase activity kinetics. We also examine mechanisms of caspase substrate selection and how inflammasome and cell identities influence caspase activity and resultant inflammatory and pyroptotic cellular programs. Understanding how inflammatory caspases are regulated may offer new strategies for treating infection and inflammasome-driven disease.

Caspase-4/11-Mediated Pulmonary Artery Endothelial Cell Pyroptosis Contributes to Pulmonary Arterial Hypertension.

Endothelial dysfunction enhances vascular inflammation, which initiates pulmonary arterial hypertension (PAH) pathogenesis, further induces vascular remodeling and right ventricular failure. Activation of inflammatory caspases is an important initial event at the onset of pyroptosis. Studies have shown that caspase-1-mediated pyroptosis has played a crucial role in the pathogenesis of PAH. However, the role of caspase-11, another inflammatory caspase, remains to be elucidated. Therefore, the purpose of this study was to clarify the role of caspase-11 in the development of PAH and its mechanism on endothelial cell function. The role of caspase-11 in the progression of PAH and vascular remodeling was assessed in vivo. In vitro, the effect of caspase-4 silencing on the human pulmonary arterial endothelial cells pyroptosis was determined. We confirmed that caspase-11 and its human homolog caspase-4 were activated in PAH animal models and TNF (tumor necrosis factor)-α-induced human pulmonary arterial endothelial cells. Caspase-11-/- relieved right ventricular systolic pressure, right ventricle hypertrophy, and vascular remodeling in Sugen-5416 combined with chronic hypoxia mice model. Meanwhile, pharmacological inhibition of caspase-11 with wedelolactone exhibited alleviated development of PAH on the monocrotaline-induced rat model. Moreover, knockdown of caspase-4 repressed the onset of TNF-α-induced pyroptosis in human pulmonary arterial endothelial cells and inhibited the activation of pyroptosis effector GSDMD (gasdermin D) and GSDME (gasdermin E). These observations identified the critical role of caspase-4/11 in the pyroptosis pathway to modulate pulmonary vascular dysfunction and accelerate the progression of PAH. Our findings provide a potential diagnostic and therapeutic target in PAH.