Pyroptosis is no ordinary cell death. Unlike apoptosis, the quiet, tidy form of programmed cell death in which cells shrink and are neatly consumed by their neighbors, pyroptosis is loud, lytic, and inflammatory. The pathway is evolutionarily conserved among eukaryotic cells and is executed by caspases—a family of proteolytic enzymes—ultimately leading to the formation of pores in the cell’s plasma membrane by members of the gasdermin protein family. When gasdermin D, the best-characterized executioner, is cleaved by inflammatory caspases such as caspase-1 or caspase-11 in mice (and caspase-4 and caspase-5 in humans), its pore-forming fragments insert into the membrane. Water rushes in, the cell swells, and it eventually ruptures, spilling its contents into the surrounding tissue.

That spill is precisely what makes pyroptosis so consequential. Among the released contents are interleukin-1β and interleukin-18, potent pro-inflammatory cytokines that are processed and activated by caspase-1 within large multiprotein signaling platforms called inflammasomes. The prototypical NLRP3 inflammasome assembles from the sensor protein NLRP3, the adaptor ASC, and caspase-1, forming supramolecular complexes sometimes described as pyroptosomes. Other inflammasomes, including NLRC4, AIM2, and NLRP1, respond to different danger signals ranging from bacterial flagellin to cytosolic DNA. In the right context—say, an intracellular bacterial infection—this explosive death is a defensive triumph, denying pathogens their replicative niche and rallying immune cells to the site. But when pyroptosis fires in the wrong place or cannot be switched off, it becomes a source of collateral tissue damage, a theme now documented in conditions from sepsis to atherosclerosis to neurodegeneration.

The ovary, the review argues, is exquisitely vulnerable to this kind of inflammatory friendly fire. Female infertility and ovarian dysfunction are closely associated with inflammation, and the ovarian follicle’s functional unit depends on granulosa cells—somatic cells that nurture the developing oocyte, mediate hormone production, and orchestrate ovulation. When granulosa cells undergo pyroptosis, the follicle loses its support system. Evidence cited in the review points to activation of the NLRP3/caspase-1/gasdermin D axis in granulosa cells across several major ovarian pathologies, including polycystic ovary syndrome (PCOS), premature ovarian insufficiency (POI), and diminished ovarian reserve. In PCOS, upregulation of TXNIP, a protein that links oxidative stress to inflammasome activation, contributes to granulosa cell dysfunction through NLRP3 activation. Hyperandrogenism, a hallmark of PCOS, has itself been shown to drive ovarian inflammation and pyroptosis, with the mechanistic target of rapamycin-linked YAP signaling implicated in follicular dysfunction.

The molecular wiring connecting metabolic stress to pyroptotic death in the ovary is becoming increasingly detailed. Oxidative stress is a central node: reactive oxygen species can trigger NLRP3 inflammasome assembly, and oxidized mitochondrial DNA released from damaged mitochondria serves as a potent inflammasome activator. The TXNIP protein acts as a molecular switch, dissociating from thioredoxin under oxidative stress and binding NLRP3 to ignite the inflammasome. Endoplasmic reticulum stress adds another layer, with the IRE1α pathway inducing TXNIP expression under irremediable stress conditions. In overweight women, local glucose elevation in the ovarian environment has been shown to activate NLRP3-dependent pyroptosis in granulosa cells, tying metabolic disease directly to reproductive cell death. Even the gut microbiome appears to play a role: microbiota dysbiosis-derived macrophage pyroptosis has been linked to PCOS through disturbance of steroidogenesis and apoptosis of granulosa cells.

The clinical stakes are considerable. Premature ovarian insufficiency—the loss of ovarian function before age forty—affects roughly one percent of women and carries profound consequences for fertility, bone health, and cardiovascular risk. Diminished ovarian reserve, a subtler depletion of the follicular pool, is among the most frustrating diagnoses in reproductive medicine, and inflammatory and oxidative stress markers measured in follicular fluid correlate with its severity. Inflamm-aging, the chronic low-grade inflammatory state that accompanies advancing age, has been proposed as a mechanism accelerating POI. The review also notes that inflammasome components are elevated in granulosa cells and follicular fluid of women with endometriosis undergoing in vitro fertilization, and that a proinflammatory M1 macrophage phenotype with NLRC4 inflammasome activation is associated with impaired oocyte fertilization. More recently, IFN-γ-induced AIM2-dependent PANoptosis—a hybrid inflammatory death program—has been implicated in ovulatory dysfunction in PCOS, underscoring that pyroptosis is one node in a broader, interconnected network of inflammatory cell death pathways that also includes necroptosis and ferroptosis.

What elevates the review beyond mechanism is its survey of therapeutics. Because each step of the pyroptotic cascade is pharmacologically addressable, a growing list of compounds has shown promise in preclinical models of ovarian disease. Nicotinamide mononucleotide (NMN), a precursor of the NAD+ cofactor, improved ovarian reserve in models of POI by inhibiting NLRP3-mediated pyroptosis of ovarian granulosa cells, consistent with a broader literature linking NAD+ metabolism to inflammasome regulation through acetylation switches. The natural compound plumbagin rescued granulosa cell pyroptosis in PCOS by reducing WTAP-mediated N6-methylation, pointing to an epitranscriptomic layer of control. Quercetin, a widely available flavonoid, alleviated cyclophosphamide-induced premature ovarian insufficiency in mice by reducing mitochondrial oxidative stress and pyroptosis in granulosa cells. Cyproterone acetate, an antiandrogen, mediated the IRE1α signaling pathway to alleviate hyperandrogen-induced granulosa cell pyroptosis. The metabolite α-ketoglutarate improved ovarian reserve function in primary ovarian insufficiency by inhibiting NLRP3-mediated pyroptosis, while itaconic acid—classically an anti-inflammatory immunometabolite—prevented ovarian damage in diminished ovarian reserve models through NRF2-mediated pathways. Resveratrol alleviated inflammation in PCOS by inhibiting AIM2 expression, and metformin inhibited granulosa cell pyroptosis through a microRNA/NOX2/ROS pathway, suggesting that established metabolic drugs may carry unexpected reproductive benefits.

Perhaps the most futuristic entry in the therapeutic lineup comes from regenerative medicine. Exosomes—nanoscale extracellular vesicles that shuttle proteins, lipids, and nucleic acids between cells—derived from mesenchymal stem cells have been shown to attenuate NLRP3-related pyroptosis in autoimmune premature ovarian insufficiency via the NF-κB pathway. Stem cell approaches more broadly, including adipose-derived stem cells that repair chemotherapy-induced ovarian failure by inhibiting granulosa cell apoptosis and senescence, are being reinterpreted through the pyroptosis lens. Even moxibustion, the traditional practice of burning mugwort near acupuncture points, has been reported to protect against cyclophosphamide-induced premature ovarian failure in rats by inhibiting the NLRP3/caspase-1/GSDMD-dependent pyroptotic axis—an intriguing convergence of ancient practice and molecular mechanism, though the authors of the underlying work acknowledge that clinical translation remains distant and that rigorous trials are needed.

The review is candid about the gaps that remain. Most of the therapeutic evidence comes from rodent models and cultured granulosa cell lines, which imperfectly recapitulate human follicular biology; human granulosa cell lines differ meaningfully from primary cells in their endocrine profiles. Biomarkers of pyroptosis that could be measured in follicular fluid or blood to stratify patients are still lacking, and the crosstalk between pyroptosis and the other regulated death pathways—apoptosis, necroptosis, ferroptosis, and PANoptosis—in the ovary is only beginning to be mapped. Distinguishing protective from pathological pyroptosis will be essential, since complete blockade of an innate immune defense pathway carries its own risks, a lesson learned from inflammasome drug development in other inflammatory diseases. The authors call for systematic investigation of gasdermin-independent pyroptotic routes, better tools for monitoring pyroptosis dynamics in living tissue, and ultimately clinical trials that test whether pyroptosis-targeted interventions can genuinely improve fertility outcomes.

Still, the conceptual shift is hard to overstate. For decades, infertility treatment has focused on manipulating hormones and retrieving oocytes, with inflammation treated as background noise. If pyroptosis proves to be a central, druggable driver of follicular demise, then a prescription pad that once held only gonadotropins and metformin might one day include NLRP3 inhibitors, gasdermin blockers, NAD+ boosters, and engineered exosomes designed to quiet the inflammatory storm inside the ovary. The review by Ajoolabady and colleagues does not claim that a cure is at hand, but it makes a compelling case that the molecular arsonist behind ovarian failure has finally been identified—and that the tools to extinguish it are already within reach.

Subject of Research: The role of pyroptosis, an inflammatory form of programmed cell death, in ovarian dysfunction and female infertility

Article Title: Pyroptosis in Patients with Ovarian Dysfunction and Infertility: Molecular Mechanisms and Therapeutics

Article References: Pyroptosis in Patients with Ovarian Dysfunction and Infertility: Molecular Mechanisms and Therapeutics. (n.d.). https://doi.org/10.1007/s43032-026-02208-2

Image Credits: AI Generated

DOI: 10.1007/s43032-026-02208-2

Keywords: pyroptosis, ovarian dysfunction, infertility, NLRP3 inflammasome, gasdermin D, granulosa cells, polycystic ovary syndrome, premature ovarian insufficiency, inflammation, caspase-1, nicotinamide mononucleotide, exosomes

The study, led by Qingtao Ni, Xiuyuan Yang, and Jingjing Bao, with corresponding author Chi Pan of The Affiliated Taizhou People’s Hospital of Nanjing Medical University, focuses on pyroptosis, a form of programmed cell death that has captivated cancer biologists in recent years. Unlike apoptosis, the quiet and orderly demise that most cell death research has traditionally centered on, pyroptosis is loud and destructive. Cells undergoing pyroptosis swell, rupture, and spill their contents into the surrounding tissue, triggering a potent inflammatory response. This explosive exit is orchestrated by members of the gasdermin family of proteins, which form pores in the cell membrane, and by inflammatory caspases such as caspase-1, which cleave those gasdermins into their active forms. The released cellular contents, including signaling molecules such as interleukin-1 beta and interleukin-18, can alert the immune system to danger. For tumor cells, this is often a catastrophic event, which is precisely why oncologists are interested in learning how to switch it on deliberately.

Yet the regulatory mechanisms governing pyroptosis in triple-negative breast cancer have remained poorly charted. To map them, the researchers began with an integrated bioinformatics analysis of publicly available gene expression datasets from the Gene Expression Omnibus, hunting for genes that are differentially expressed in breast cancer tissue compared with healthy tissue. From this screen, one gene stood out as a hub of malignant activity: MELK, short for maternal embryonic leucine zipper kinase. The team confirmed in clinical triple-negative breast cancer specimens that MELK is significantly upregulated in these tumors, and that elevated levels are associated with more advanced disease and poorer prognosis. Functionally, when the researchers manipulated MELK levels in triple-negative breast cancer cell lines, they found that the kinase actively promoted the hallmarks of cancer aggression: proliferation, migration, and invasion.

On the other side of the balance sat a microRNA. MicroRNAs are short, non-coding RNA molecules, roughly 22 nucleotides long, that do not encode proteins but instead regulate gene expression after transcription. They bind to complementary sequences in messenger RNA transcripts, marking them for degradation or blocking their translation into protein. A single microRNA can thereby tune the output of dozens of genes simultaneously. The microRNA in question here, miR-205-3p, was frequently found at reduced levels in triple-negative breast cancer samples, a pattern consistent with a tumor-suppressive role. When the researchers restored or elevated miR-205-3p in triple-negative breast cancer cell lines, the effect was striking: the cells underwent caspase-1-dependent pyroptosis, a conclusion supported by the appearance of cleaved fragments of both gasdermin D and gasdermin E, the executioner proteins of the pyroptotic pathway, as well as the release of interleukin-1 beta and interleukin-18 measured by Western blotting and enzyme-linked immunosorbent assay.

A natural question followed: was miR-205-3p simply silencing MELK directly? The answer, perhaps surprisingly, was no. Although MELK overexpression partially reversed the suppression of malignant behavior caused by miR-205-3p, the team’s experiments, including a dual-luciferase reporter assay, a standard technique for verifying direct binding between a microRNA and its target transcript, showed that miR-205-3p does not directly target MELK. Instead, the true direct target turned out to be a different molecule entirely: HSP90AB1, the heat shock protein 90 alpha family class B member 1, a molecular chaperone best known for stabilizing a wide array of client proteins inside the cell. The reporter assays confirmed that miR-205-3p binds directly to HSP90AB1 transcripts and represses their expression.

This discovery reframed the entire regulatory architecture. HSP90AB1, it emerged, sits at the center of a tug-of-war between the tumor-suppressive microRNA and the oncogenic kinase. The researchers found that MELK positively regulates HSP90AB1, enhancing its expression, and that this enhancement serves to inhibit the pyroptotic pathway. In other words, MELK protects triple-negative breast cancer cells from inflammatory self-destruction by keeping the chaperone abundant, while miR-205-3p promotes pyroptosis by stripping that protection away. When miR-205-3p represses HSP90AB1, the downstream gasdermin D and gasdermin E cleavage cascade is unleashed, and the cell dies by pyroptosis. When MELK is abundant and drives HSP90AB1 upward, the miR-205-3p/HSP90AB1/GSDMD axis is suppressed, and the cell survives to proliferate, migrate, and invade.

The interplay between these two regulators through their shared target ultimately determines cellular fate, the authors conclude. This kind of indirect antagonism, in which a microRNA and a kinase converge on a common downstream effector rather than on each other, adds a layer of nuance to how researchers think about microRNA-mediated tumor suppression. It also helps explain why MELK has repeatedly surfaced in cancer studies as a driver of malignancy: beyond its established roles in cell cycle control and signaling, it appears to function as a critical upstream brake on pyroptosis, keeping tumor cells from triggering the inflammatory form of death that would otherwise expose them to immune attack.

The therapeutic implications are considerable. Triple-negative breast cancer has long been an attractive candidate for immunotherapy and other novel approaches precisely because its inflammatory microenvironment, when it exists, correlates with better responses. If pyroptosis can be pharmacologically induced in these tumors, the resulting release of damage-associated molecular patterns and inflammatory interleukins could convert a cold tumor into a hot one, recruiting immune cells to the site of disease. The newly described miR-205-3p/HSP90AB1/GSDMD axis offers several potential intervention points: restoring miR-205-3p activity, inhibiting MELK, or directly targeting HSP90AB1 function. MELK inhibitors have already attracted attention in drug development pipelines, and the present study provides a fresh mechanistic rationale for exploring them in triple-negative breast cancer, not merely as anti-proliferative agents but as sensitizers of immunogenic cell death.

As with all laboratory studies, the path from cell culture to clinic is long. The experiments relied on established triple-negative breast cancer cell lines and clinical specimens, and the authors note that the work was approved by the Ethical Committee of Jiangsu Taizhou People’s Hospital with written informed consent from participants. Delivering microRNA mimics to tumors remains a formidable delivery challenge, and the precise consequences of triggering pyroptosis in a living tumor, where inflammatory signals can sometimes fuel growth as easily as they can ignite immune clearance, will require careful evaluation in animal models and, eventually, clinical trials. Still, the study adds an important piece to the puzzle of why triple-negative breast cancer cells resist death, and it identifies a concrete molecular switch—HSP90AB1, poised between a protective kinase and a lethal microRNA—that future therapies might one day flip. For patients facing the hardest-to-treat form of breast cancer, that switch represents a genuinely new lead.

Subject of Research: The regulatory mechanism by which miR-205-3p induces pyroptosis in triple-negative breast cancer through HSP90AB1 and antagonism of MELK.

Article Title: miR-205-3p induces pyroptosis in triple-negative breast cancer by targeting HSP90AB1 and antagonizing MELK

Article References: Ni, Q., Yang, X., Bao, J., Yi, T., & Pan, C. (2026). miR-205-3p induces pyroptosis in triple-negative breast cancer by targeting HSP90AB1 and antagonizing MELK. BMC Cancer. https://doi.org/10.1186/s12885-026-17028-5

Image Credits: AI Generated

DOI: 10.1186/s12885-026-17028-5

Keywords: triple-negative breast cancer, pyroptosis, miR-205-3p, HSP90AB1, MELK, gasdermin D, gasdermin E, caspase-1, microRNA, tumor suppression, cell death, BMC Cancer

Microglia are the sentinels of the central nervous system. In the healthy brain they patrol their territory with ramified processes, sampling the microenvironment for signs of danger. When ischemia strikes, they rapidly shift into an activated state, and for years researchers described this shift using a binary model: pro-inflammatory M1-like microglia that amplify tissue damage, and anti-inflammatory M2-like microglia that promote repair. The new review argues that this tidy dichotomy has outlived its usefulness. Single-cell sequencing studies have revealed a far richer spectrum of microglial subtypes, each with distinct transcriptional profiles, metabolic preferences, and functional consequences. Polarization, in this view, is not a switch but a continuum—a dynamic landscape of states that cells occupy, abandon, and re-enter as the post-stroke environment evolves.

At the heart of this transformation lies a profound metabolic reprogramming. Resting microglia rely primarily on oxidative phosphorylation, the efficient mitochondrial process that converts nutrients into ATP. After ischemia, however, oxygen and glucose scarcity forces a shift toward aerobic glycolysis, the same fermentative strategy that Warburg observed in cancer cells. This metabolic pivot is orchestrated in large part by hypoxia-inducible factor 1-alpha, or HIF-1α, which stabilizes under low-oxygen conditions and drives expression of glycolytic enzymes such as hexokinase 2. The result is a cell that burns glucose wastefully but rapidly, generating the biosynthetic intermediates and NADPH it needs to fuel an immune response—while simultaneously producing lactate and succinate as metabolic byproducts with signaling roles of their own.

The review pays particular attention to mitochondria, which are not merely passive casualties of ischemia but active participants in the inflammatory cascade. Under normal conditions, a network of mitochondrial quality control mechanisms—collectively termed MQC—keeps these organelles healthy. Mitochondrial dynamics, the constant fission and fusion of the network, allow damaged segments to be segregated. Mitophagy, guided by the PINK1-Parkin pathway, then removes severely compromised mitochondria before they can do harm. Ischemia disrupts this surveillance system. The mitochondrial permeability transition pore opens, membrane potential collapses, and the quality control machinery becomes overwhelmed. The consequence is the release of a battery of mitochondrial damage-associated molecular patterns: reactive oxygen species generated at the electron transport chain, fragments of oxidized mitochondrial DNA, and cardiolipin, a phospholipid normally confined to the inner mitochondrial membrane that becomes a potent danger signal when exposed to the cytosol.

These mitochondrial alarm signals converge on one of the most consequential immune complexes known: the NLRP3 inflammasome. NLRP3, a cytosolic pattern-recognition receptor, assembles with the adaptor protein ASC and procaspase-1 into a multi-protein platform that activates caspase-1. The review highlights how several metabolic and mitochondrial cues converge to trigger this assembly. Succinate, which accumulates during ischemia, can drive reverse electron transport through mitochondrial complex I, supercharging the production of mitochondrial reactive oxygen species. Oxidized mitochondrial DNA binds directly to NLRP3. Extracellular lactate and cytosolic cardiolipin provide additional priming and activation signals. Once assembled, the inflammasome executes its inflammatory program: caspase-1 cleaves pro-interleukin-1β and pro-interleukin-18 into their mature, secreted forms, and cleaves gasdermin D to release its N-terminal fragment, GSDMD-NT.

What happens next is where the review makes its most striking conceptual contribution. GSDMD-NT is not simply a bystander in inflammation—it migrates to the mitochondria and perforates both the inner and outer mitochondrial membranes, forming pores that further destabilize these organelles. This establishes a self-amplifying positive feedback loop: mitochondrial damage releases the signals that activate the NLRP3 inflammasome, and inflammasome activation inflicts further mitochondrial damage. In the ischemic brain, where microglia are already metabolically stressed, this loop can lock the cell into a hyperinflammatory state that persists long after the initial insult. The authors also note that activated mitochondrial DNA can engage the STING pathway, adding an interferon-mediated dimension to the inflammatory response and further entrenching the pro-inflammatory phenotype.

Crucially, the review insists that this axis cannot be understood without considering time. The authors stratify the MQC–metabolism–inflammation network into three temporal phases. In the hyperacute phase, within minutes to hours of vessel occlusion, energy failure and mitochondrial permeability transition dominate, and the earliest danger signals are released. In the subacute phase, spanning hours to days, microglial polarization reaches its peak, glycolytic reprogramming is fully established, and NLRP3-driven cytokine release shapes the evolving lesion. In the chronic phase, weeks to months later, a lingering population of chronically activated microglia sustains low-grade inflammation that interferes with tissue remodeling and repair. Each phase, the authors argue, presents distinct therapeutic windows and distinct molecular targets, and interventions that ignore this temporal structure are unlikely to succeed.

The review is also refreshingly candid about the translational bottlenecks that have stalled progress from bench to bedside. Numerous NLRP3 inhibitors and mitochondrial protective agents have shown promise in rodent models of stroke, yet clinical trials have repeatedly disappointed. One reason, the authors emphasize, lies in fundamental differences between mice and humans. The NLRP3 inflammasome and its regulatory feedback mechanisms differ in important ways between the two species, meaning that regulatory circuits mapped in mouse models must be interpreted with caution before being extrapolated to patients. The authors call for humanized models and bidirectional clinical validation to close this gap, alongside single-cell multi-omics approaches to map the full diversity of microglial subpopulations in the human ischemic brain, and metabolic flux analysis to quantify the actual thresholds at which metabolites such as succinate and lactate become pathogenic.

Two testable hypotheses emerge from the framework. The first proposes that the strength and duration of the mitochondrial damage–inflammasome feedback loop determines whether microglia resolve toward a reparative phenotype or remain trapped in a chronic inflammatory state—suggesting that early stabilization of mitochondrial quality control could steer the entire trajectory of post-stroke inflammation. The second proposes that specific metabolite thresholds, rather than bulk shifts in metabolic pathway activity, are the critical determinants of NLRP3 activation, implying that precise quantification of metabolite flux in individual microglial subtypes will be essential for rational drug design. Both hypotheses lend themselves to direct experimental interrogation with the tools now available, from metabolomics to live imaging of mitochondrial dynamics.

For a field that has long treated metabolism, mitochondria, and inflammation as separate chapters of the stroke story, this integrated framework offers something genuinely new: a systems-level map of how the pieces fit together in space and time. If the hypotheses hold up, the implications extend beyond ischemic stroke to any neurological condition in which microglial metabolism and inflammasome activation run amok, from traumatic brain injury to neurodegenerative disease. The therapeutic challenge remains formidable—timing interventions to the right phase, achieving selectivity for pathogenic microglial states, and bridging the species divide—but the review provides a clear conceptual scaffold on which the next generation of experiments, and perhaps eventually therapies, can be built.

Subject of Research: Microglial metabolic reprogramming, mitochondrial dysfunction, and NLRP3 inflammasome activation in cerebral ischemia

Article Title: Metabolic reprogramming and polarization of microglia in cerebral ischemia: the roles of mitochondria and inflammasomes

Article References: Ding, Y., Li, N., Li, Q., Zhang, H., He, L., Gao, F., & Li, P. (2026). Metabolic reprogramming and polarization of microglia in cerebral ischemia: the roles of mitochondria and inflammasomes. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-08947-9

Image Credits: AI Generated

DOI: 10.1186/s12967-026-08947-9

Keywords: ischemic stroke, microglia, mitochondrial quality control, metabolic reprogramming, NLRP3 inflammasome, neuroinflammation, mitochondrial dysfunction, aerobic glycolysis, gasdermin D, single-cell sequencing, HIF-1alpha, neuroimmunology

Inflammasomes are cytosolic signaling complexes assembled by pattern recognition receptors in response to a wide array of danger-associated and pathogen-associated molecular patterns. Among the best characterized is the NLRP3 inflammasome, which can be activated by an extraordinary diversity of stimuli, ranging from extracellular ATP and crystalline substances such as monosodium urate to perturbations in cellular homeostasis including mitochondrial dysfunction and ionic flux. Structural studies, notably cryo-electron microscopy analyses, have revealed that NLRP3 oligomerizes into a large ring-like platform that recruits the adaptor protein ASC through pyrin domain interactions. ASC in turn nucleates the polymerization of procaspase-1 filaments through its caspase recruitment domain, creating a branched, star-shaped assembly that has become iconic in the field of innate immunity.

The review emphasizes how this hierarchical assembly process, in which a receptor seeds adaptor polymerization which then seeds effector activation, is a recurring architectural principle across inflammasome families. DNA-sensing receptors such as AIM2 and the Pyrin family of receptors, as well as the more recently described sensors like NLRP1 and CARD8, all converge on the same downstream machinery despite recognizing fundamentally different ligands. This convergence explains how a limited set of adaptor and effector molecules can translate an enormous diversity of upstream danger signals into a uniform cellular response: the activation of inflammatory caspases, cleavage of the cytokine precursors pro-interleukin-1 beta and pro-interleukin-18, and induction of a lytic form of cell death known as pyroptosis.

Pyroptosis itself has been structurally dissected at the level of its executioner, gasdermin D. Activated inflammatory caspases cleave gasdermin D to release an N-terminal fragment that oligomerizes into membrane pores, causing osmotic lysis and the release of intracellular contents, including mature interleukin-1 beta. Recent structures of gasdermin pores have clarified how the positively charged face of the oligomer interacts with membrane lipids and how pore formation is regulated. This level of mechanistic detail has direct pharmacological implications, because small molecules that block gasdermin pore formation or inflammasome assembly could dampen pathological inflammation in conditions as varied as gout, atherosclerosis, type 2 diabetes, inflammatory bowel disease, and neurodegenerative disease, all of which have been linked to excessive inflammasome activity.

Beyond canonical inflammasomes, the review devotes substantial attention to PANoptosis, a recently articulated form of inflammatory programmed cell death that integrates features of pyroptosis, apoptosis, and necroptosis within a single, coordinated complex termed the PANoptosome. Unlike a classical inflammasome, a PANoptosome contains components from multiple cell death pathways simultaneously, including Z-DNA-binding protein 1, or ZBP1, which senses Z-form nucleic acids generated during viral infection, together with receptor-interacting protein kinases and other death-domain proteins. Structural and biochemical studies suggest that these complexes assemble through a web of homotypic and heterotypic domain interactions, creating a platform capable of activating multiple death effector machineries in parallel and amplifying inflammatory signaling to a degree that neither pathway could achieve alone.

ZBP1 has emerged as a particularly instructive example of how structural insights inform PANoptosome biology. Its two Z-nucleic acid binding domains recognize the unusual left-handed conformation of Z-DNA and Z-RNA, which accumulates in cells infected with viruses such as influenza A. Upon ligand binding, ZBP1 engages RIPK3 through RHIM domain interactions, and in certain contexts also recruits NLRP3 and ASC, thereby coupling viral sensing directly to necroptosis, pyroptosis, and cytokine release. Mutations that disrupt these interactions protect mice from lethal influenza-associated inflammation, underscoring the in vivo importance of this pathway and highlighting RHIM-mediated interactions as a potential drug target in severe viral pneumonia and other contexts of pathogenic inflammation.

One of the central themes of the review is that autoinhibition is a universal feature of innate immune sensors, reflecting the danger of accidental self-destruction if these potent inflammatory pathways are triggered spuriously. NLRP3, for example, is held in an inactive conformation by its LRR domain folding back onto the nucleotide-binding domain, a constraint released through a multi-step activation process involving NEK7 binding, deubiquitination, and translocation to the Golgi or endosomal membranes. Similar autoinhibitory mechanisms govern NLRP1, which releases its inhibitory function upon proteasomal degradation of an N-terminal regulatory segment, and pyrin, which is restrained by phosphorylation-dependent sequestration through binding to 14-3-3 proteins. Structural biology has provided atomic-level explanations for how disease-associated mutations, including those causing cryopyrin-associated periodic syndromes and familial Mediterranean fever, destabilize these autoinhibited states and drive constitutive inflammasome activation.

The therapeutic implications of this structural knowledge are considerable and span several classes of intervention. Direct inhibitors of NLRP3, such as MCC950 and its derivatives, have demonstrated efficacy in preclinical models of numerous inflammatory diseases and are progressing through clinical evaluation. Second-generation approaches include compounds that block ASC speck formation, inhibitors of inflammatory caspases, gasdermin D antagonists designed to prevent pore formation, and agents targeting upstream cytokine signaling through blockade of interleukin-1 family receptors. For PANoptosome-driven diseases, particularly severe viral infections and certain hereditary autoinflammatory syndromes, strategies that interrupt specific protein-protein interfaces, such as the RHIM-dependent interaction between ZBP1 and RIPK3, represent an emerging frontier. The review argues that structural data, by revealing precisely where and how these complexes assemble, will be indispensable for the rational design of such inhibitors.

Challenges nonetheless remain substantial. Inflammasome components are large, flexible, and often membrane-associated, complicating structural determination of full assemblies in physiologically relevant states. Much of the available structural information derives from isolated domains, truncated constructs, or oligomers assembled in vitro, and bridging the gap between these reductionist structures and the behavior of intact complexes in living cells remains a priority. Moreover, the redundancy and interconnection of inflammatory cell death pathways mean that blocking one arm may simply redirect signaling through another, arguing for combination approaches informed by a systems-level understanding of PANoptosome architecture and regulation.

Taken together, the review frames inflammasomes and PANoptosomes not as isolated curiosities of innate immunity but as a structurally unified family of molecular decision-making machines whose misregulation underlies a broad spectrum of human disease. As cryo-electron microscopy, cryogenic electron tomography, and single-molecule imaging continue to reveal these assemblies at ever higher resolution in increasingly native contexts, the prospect of precisely targeted anti-inflammatory therapeutics, capable of silencing pathological inflammation while preserving beneficial host defense, moves steadily closer to reality.

Subject of Research: Structural and mechanistic analysis of innate immune sensors that assemble inflammasomes and PANoptosomes

Article Title: Innate immune sensors of inflammasomes and PANoptosomes: structural–mechanistic insights and therapeutic implications

Article References: Upadhyay, S., Nagampalli, R., Resende, S., & Kanneganti, T.-D. (2026). Innate immune sensors of inflammasomes and PANoptosomes: structural–mechanistic insights and therapeutic implications. Cell Research. https://doi.org/10.1038/s41422-026-01287-9

Image Credits: AI Generated

DOI: 10.1038/s41422-026-01287-9

Keywords: innate immunity, inflammasome, PANoptosis, PANoptosome, NLRP3, ZBP1, ASC, caspase-1, gasdermin D, pyroptosis, structural biology, anti-inflammatory therapeutics