Rats were randomly assigned to sham surgery, myocardial infarction with saline, or myocardial infarction followed by combined drug treatment, with nine animals in each group. Rats in the combination group received bevantolol at 10.5 mg/kg and tandospirone at 3.15 mg/kg by intragastric administration for seven days. Infarcted controls received 5 mL/kg of physiological saline. The doses were converted from human doses through a body-surface-area method, and tissues were collected after the final administration.

Investigators assessed infarct size using TTC/Evans blue staining. In this method, tissue unstained by Evans blue represented the ischemic area, while tissue not stained by TTC within that area represented infarction. Quantitative histological analyses used three biological replicates per group. Hematoxylin and eosin staining showed disorganized myocardium, inflammatory-cell infiltration, collagenous fibers, and visible scar in infarcted control rats. These abnormalities were less pronounced in rats receiving the combination, supporting the observation that combined treatment mitigated myocardial pathological damage after infarction.

Masson staining was used to quantify fibrosis through the collagen volume fraction, defined as the proportion of positively stained collagen area relative to total tissue area. Collagen volume fraction was higher after infarction than in sham-operated rats and lower with combined treatment than in saline-treated infarcted controls. TUNEL staining, which detects DNA fragmentation rather than apoptosis specifically, also showed a higher proportion of positive cells after infarction and a lower proportion following combined treatment. The investigators cautioned that TUNEL-positive cells can reflect multiple programmed cell-death pathways, including pyroptosis, so the assay did not quantify the separate contributions of apoptosis and pyroptosis to cardiomyocyte loss.

Enzyme-linked immunosorbent assays used six biological replicates per group to measure serum creatine kinase-MB and cardiac troponin I, serum and myocardial-tissue concentrations of interleukin-1β and interleukin-18, and myocardial-tissue concentrations of interleukin-1β and interleukin-18. Compared with sham-operated animals, infarcted controls had higher concentrations of the myocardial injury markers and inflammatory cytokines. The combined-treatment group had lower concentrations of all six measured analyte-location combinations than infarcted controls. Quantitative reverse-transcription polymerase chain reaction and Western blotting likewise showed higher myocardial interleukin-1β and interleukin-18 messenger RNA and protein expression after infarction and lower expression with the combination.

The investigators next examined NLRP3, cleaved Caspase-1, and the N-terminal domain of gasdermin D, designated GSDMD-N. Immunohistochemical staining, qRT-PCR, and Western blotting showed increased expression of these markers in infarcted controls relative to sham-operated rats and decreased expression in the combination group. These findings demonstrate lower molecular-marker expression following combined treatment; they do not, by themselves, prove that the treatment directly inhibited the pathway or that pathway suppression mediated the histological effects.

The study also assessed the precursor proteins pro-Caspase-1 and full-length GSDMD. Both were elevated after myocardial infarction. Their abundance was numerically lower in the combination group, but the differences from infarcted controls were not significant. By contrast, the ratios of cleaved Caspase-1 to pro-Caspase-1 and GSDMD-N to full-length GSDMD increased after infarction and were significantly reduced by combined treatment. The authors interpreted this pattern as consistent with less cleavage and activation of Caspase-1 and GSDMD rather than a major change in precursor-protein abundance.

Several limitations constrain the findings. The experiment did not include myocardial-infarction groups treated with bevantolol or tandospirone alone, so it cannot show that the combination was more effective than either drug or that the agents interacted synergistically. It also did not measure cardiac function, survival, or outcomes beyond the one-week treatment period, and it did not test post-infarction anxiety-like or depression-like behavior. Alternative stress-modulating drugs were not evaluated. The mechanistic interpretation remains bounded by the absence of a validated NLRP3-specific inhibitor or activator and definitive functional pyroptosis assays.

Cell-type-specific co-staining was also not performed, so the experiment could not identify which myocardial or inflammatory cell populations generated the pathway signals. These results therefore support an association between combined bevantolol and tandospirone treatment, reduced myocardial injury markers, and lower NLRP3/Caspase-1/GSDMD-associated marker expression in a short-term male rat infarction model. They do not demonstrate human clinical efficacy, long-term functional benefit, or a causal pathway mechanism.

Subject of Research: Short-term rat myocardial infarction study of bevantolol plus tandospirone and NLRP3/Caspase-1/GSDMD-associated markers

Article Title: Protection of beta-blocker and 5-hydroxytryptamine 1A receptor agonist on myocardial ischemia injury in rats by regulating the NLRP3/Caspase-1/GSDMD pathway

Article References: Chen, H., Li, Y., Liu, M., Chi, Y., & Zhang, L. (2026). Protection of beta-blocker and 5-hydroxytryptamine 1A receptor agonist on myocardial ischemia injury in rats by regulating the NLRP3/Caspase-1/GSDMD pathway. PLOS One, 21(10), e0360695. https://doi.org/10.1371/journal.pone.0360695

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360695

Keywords: rat myocardial infarction, bevantolol, tandospirone, beta-blocker, 5-HT1A receptor agonist, NLRP3 inflammasome, Caspase-1, GSDMD, myocardial inflammation, pyroptosis, Protection, hydroxytryptamine

Sickle cell disease is caused by a mutation in the beta-globin gene that produces hemoglobin S, an abnormal hemoglobin that polymerizes when oxygen levels fall. The resulting rigid, fragile red blood cells undergo hemolysis and promote chronic inflammation and vaso-occlusive episodes. The SC and SS forms included in the study differ in clinical pattern. Although SC disease is generally less severe than SS disease, it can be accompanied by hypercoagulability, retinopathy and osteonecrosis. The participants were recruited from the University Hospital of Guadeloupe’s sickle cell unit, and all were adults who had avoided acute complications, including infection, vaso-occlusive crisis, acute chest syndrome, stroke and priapism, for at least one month before enrollment.

Blood counts and biochemical measurements documented the expected biological differences between the groups. Mean hemoglobin concentration was 13.5 grams per deciliter in healthy donors, compared with 11.1 in SC patients and 8.7 in SS patients. Median reticulocyte counts were 56 × 10^9 per liter in controls, 109 × 10^9 per liter in SC patients and 209 × 10^9 per liter in SS patients, indicating substantially greater red cell turnover in SS disease. SS patients also had higher concentrations of lactate dehydrogenase, total bilirubin and aspartate aminotransferase. Thirty-one of the 47 SS patients had received hydroxycarbamide for more than six months, but the study found no significant difference between treated and untreated patients in P-selectin expression, platelet–neutrophil aggregates or platelet caspase-1 activity.

Flow cytometry showed that the proportion of platelets expressing P-selectin averaged 13.38% in healthy donors, 23.80% in SC patients and 26.86% in SS patients. The increases were significant in both patient groups relative to controls, but P-selectin expression did not differ significantly between SC and SS patients. Platelet caspase-1 activity, detected with a fluorescent inhibitor of activated caspase-1, was also elevated in both disorders: the median was 4.24% in healthy donors, 10% in SC patients and 7.91% in SS patients. The difference between the two patient groups was not significant. In SS patients, caspase-1 activity correlated positively with P-selectin expression, with a correlation coefficient of 0.3702, and the same association was present in SC patients, with a coefficient of 0.4755.

The degree of hemolysis offered additional context for the SS results. Platelet caspase-1 activity correlated negatively with fetal hemoglobin, with a coefficient of −0.3872, and positively with total bilirubin, with a coefficient of 0.3238. Correlations with reticulocyte count and aspartate aminotransferase were positive but did not meet the study’s threshold for statistical significance. No comparable hemolysis associations were detected in the SC group, although the authors cautioned that lower hemolysis and less interindividual variation in that group may have reduced the study’s statistical power. These observations are compatible with the hypothesis that products released by damaged red cells contribute to inflammatory signaling in platelets, but the study did not directly demonstrate that free hemoglobin, heme or another circulating molecule caused the association.

Platelet–neutrophil aggregates were more frequent in SS patients than in healthy controls, reaching a median of 16.65% compared with 7.18%, a statistically significant difference. The median was 9.21% in SC patients, with no significant difference from either controls or SS patients. Because P-selectin on platelets can bind P-selectin glycoprotein-1 on leukocytes, the elevated aggregate counts in SS disease are consistent with a role for platelet activation in cell-to-cell interactions that contribute to vascular inflammation. However, aggregate levels were not significantly associated with a history of vaso-occlusive crisis or acute chest syndrome, nor with the number of either event during the three years before enrollment.

To examine whether circulating factors could transmit the effect, researchers incubated platelets from healthy donors for one hour with plasma from healthy donors or SS patients. SS plasma significantly increased platelet caspase-1 activity, raising the median from 5.17% to 15.81%, while its effect on P-selectin expression showed only a nonsignificant trend. The experiment demonstrates that material present in SS plasma can trigger an inflammatory pathway in platelets from healthy donors, consistent with the authors’ broader inflammasome hypothesis. It does not, by itself, establish which plasma constituent is responsible or prove that NLRP3 inflammasome assembly is the mechanism. Activated caspase-1 can arise downstream of inflammasome signaling, yet the study did not directly assay platelet NLRP3 or ASC assembly.

Bruton tyrosine kinase, or BTK, was investigated because it can regulate platelet activation and the NLRP3 inflammasome. Western blots showed numerically higher BTK phosphorylation in SS platelets than in controls, but the difference was not statistically significant; no significant differences were found among healthy, SC and SS groups. Phosphorylation also did not correlate significantly with either platelet caspase-1 activity or P-selectin expression. Only 12 controls, 12 SC patients and 13 SS patients were included in this analysis, limiting its ability to detect a moderate difference, and the authors noted that the sensitivity of the method might also have been insufficient. Thus, the study did not establish increased platelet BTK activation in the patient groups.

In a separate in vitro experiment, healthy platelets were exposed to 30 micromolar hemin, an oxidized form of heme chosen to approximate circulating concentrations in sickle cell disease. Hemin significantly increased P-selectin expression, from a mean of 28.78% to 67.21%, but did not significantly increase caspase-1 activity. Pretreatment with 5 micromolar ibrutinib, a BTK inhibitor, suppressed the hemin-induced P-selectin response to 10.84% on average. Ibrutinib did not significantly reduce caspase-1 activity, which remained similar to the level in hemin-treated platelets without the inhibitor. These results separate two responses under the tested conditions: hemin promoted BTK-dependent platelet degranulation, whereas it was not the principal stimulus for platelet caspase-1 activation detected here. The experiment used isolated platelets and a single concentration, so it cannot establish the behavior of the pathway during human crises or in every disease genotype.

Taken together, the results identify a blood-cell inflammatory circuit in which sickle cell disease is associated with platelet activation, elevated caspase-1 activity and, particularly in SS disease, more platelet–neutrophil aggregates. The study was observational for its patient comparisons and used in vitro experiments to probe potential mechanisms, so it does not show that caspase-1 activity causes clinical events or that inhibiting the pathway would prevent vaso-occlusion. Its principal limitations include the modest sample size, restriction to adults in steady state, incomplete BTK sampling and the absence of direct platelet NLRP3 measurements. Nevertheless, the findings support further investigation of inflammasome-related platelet signaling as a component of sickle cell thromboinflammation, while showing that different hemolytic signals and drug responses cannot be treated as interchangeable.

Subject of Research: Platelet caspase-1 activation and inflammasome-related signaling in sickle cell disease

Article Title: Activation of Platelet Caspase‐1 and P‐Selectin Over‐Expression in Sickle Cell Disease Patients: An Involvement of NLRP3 Inflammasome?

Article References: Claude, L., Martino, F., Mordier, L., Célanie, D., Bernit, E., Etienne‐Julan, M., Tressières, B., Romana, M., & Baccini, V. (2026). Activation of Platelet Caspase‐1 and P‐Selectin Over‐Expression in Sickle Cell Disease Patients: An Involvement of NLRP3 Inflammasome?. Journal of Cellular and Molecular Medicine, 30(20), Article e71390. https://doi.org/10.1111/jcmm.71390

Image Credits: AI Generated

DOI: 10.1111/jcmm.71390

Keywords: sickle cell disease, platelet activation, caspase-1, NLRP3 inflammasome, P-selectin, hemolysis, platelet-neutrophil aggregates, Bruton tyrosine kinase, hemin, Guadeloupe, Activation, Platelet

The study, published in Cell Death Discovery, focuses on lens epithelial cells, the thin layer of cells that covers the front of the lens and maintains its transparency throughout life. When these cells die or become inflamed, the structural integrity and clarity of the lens suffer. The researchers suspected that a form of inflammatory cell death called pyroptosis might be a key driver of the damage, and they traced the process back to one of the immune system’s most sensitive alarm systems: the detection of stray DNA inside the cell.

Under normal conditions, DNA belongs in the nucleus and in mitochondria, the cell’s energy-producing compartments. When fragments of genetic material appear in the cytoplasm — the fluid surrounding these compartments — it usually signals danger, either from an invading pathogen or from internal injury. A protein called cyclic GMP-AMP synthase, or cGAS, acts as the cytoplasmic DNA sensor. Upon binding stray DNA, cGAS produces a small messenger molecule that activates a protein on the endoplasmic reticulum known as STING, which in turn switches on inflammatory signaling pathways. This cGAS-STING system is a cornerstone of innate immunity, but when it fires inappropriately it can turn a cell’s own tissues into targets.

The first evidence came from human tissue. Examining anterior lens capsules removed from patients with diabetic cataract, the team found that the lens epithelial cells showed significantly elevated levels of cGAS, STING, NLRP3, caspase-1, and gasdermin D — a lineup of proteins that together define the inflammatory pathway the researchers wanted to interrogate. NLRP3 is the sensor component of a multiprotein assembly called the NLRP3 inflammasome, which assembles in response to cellular stress. Once assembled, the inflammasome activates caspase-1, an enzyme that both processes inflammatory signaling molecules and cleaves gasdermin D, the executioner protein of pyroptosis.

Pyroptosis is a particularly destructive form of programmed cell death. Unlike the quiet, tidy dismantling of apoptosis, pyroptosis ends with gasdermin D punching large pores in the cell membrane. The cell swells, bursts, and spills its contents — including mature forms of the inflammatory messengers interleukin-1β and interleukin-18 — into the surrounding tissue. This release amplifies inflammation, recruiting and activating neighboring cells and potentially damaging the extracellular matrix that keeps the lens transparent. Lactate dehydrogenase, an enzyme normally confined inside healthy cells, leaks out through these pores and serves as a convenient laboratory marker of membrane rupture.

To test whether high glucose could trigger this entire cascade in lens cells, the researchers exposed human lens epithelial cells to elevated sugar concentrations in culture. The exposure produced exactly the sequence they predicted: DNA accumulated in the cytoplasm, including fragments released from damaged mitochondria; cGAS-STING signaling switched on; the NLRP3 inflammasome and its adaptor protein ASC accumulated; caspase-1 and gasdermin D were cleaved into their active forms; lactate dehydrogenase leaked into the culture medium; and the cells secreted elevated amounts of interleukin-1β and interleukin-18. In short, high glucose transformed the lens epithelium’s own protective cells into casualties of an innate immune response gone awry.

The causal question remained: was the inflammasome actually responsible for the cell death, or merely a bystander? The team answered it with small interfering RNAs, synthetic molecules that silence specific genes. When they knocked down NLRP3 in lens epithelial cells under high-glucose conditions, the pyroptotic response collapsed. Levels of ASC, cleaved caspase-1, and cleaved gasdermin D fell, lactate dehydrogenase release dropped, and secretion of interleukin-1β and interleukin-18 diminished. Silencing cGAS or STING produced a similar protective effect and, critically, suppressed activation of the NLRP3-caspase-1-gasdermin D axis. That placement — upstream of the inflammasome — suggests that the DNA-sensing pathway acts as an initiator that feeds into and drives inflammasome activation in the diabetic lens.

Cell culture experiments, however convincing, cannot capture the complexity of a living eye. The researchers therefore turned to a diabetic rat model, in which elevated blood sugar produces lens clouding resembling the human condition. Delivering small interfering RNAs targeting cGAS, STING, or NLRP3 to the animals significantly reduced lens opacity and improved the histopathological appearance of the lens epithelium and cortex under the microscope. The improvement across all three molecular targets strengthens the argument that the pathway operates as an integrated axis in vivo, rather than as isolated biochemical events, and demonstrates for the first time in a living system that interrupting this signaling at multiple points can preserve lens clarity.

The findings carry real therapeutic weight. Current drug development efforts against inflammatory diseases increasingly target cGAS-STING and NLRP3, and inhibitors of both pathways are in various stages of preclinical and clinical evaluation for conditions ranging from gout to neurodegeneration. The new work suggests that such compounds — or gene-silencing approaches like the siRNAs used here — could one day complement glucose control as a strategy to slow or prevent diabetic cataract. Because the pathway was validated at three separate nodes in animal models, it offers several potential points of pharmacological intervention, each of which might be exploited depending on safety and delivery considerations.

Important caveats remain before the laboratory results can inform clinical practice. The animal work used rats, whose lenses differ in some respects from human lenses, and the duration of intervention was limited relative to the years over which diabetic cataract develops in patients. Delivering RNA therapeutics or small-molecule inhibitors to the lens in a safe, sustained way is an unsolved engineering problem, and innate immune pathways such as cGAS-STING perform essential protective functions elsewhere in the body, so systemic suppression carries risks that local, eye-targeted approaches would need to avoid. Nevertheless, by identifying cytosolic DNA accumulation as the trigger and tracing a complete signaling route from cGAS through STING and the NLRP3 inflammasome to gasdermin D–mediated rupture of lens epithelial cells, the study reframes diabetic cataract not simply as a passive consequence of sugar-induced protein damage, but as an active, targetable inflammatory disease — a conceptual shift that could reshape how researchers search for the first true drug treatment for this blinding complication.

Subject of Research: The role of cGAS-STING signaling and NLRP3 inflammasome-mediated pyroptosis in high glucose-induced diabetic cataract

Article Title: Inhibition of cGAS-STING signaling and NLRP3 inflammasome-mediated pyroptosis reduces lens opacity and inflammation in high glucose-induced cataract

Article References: Yu, Y., Chen, H., Hu, L., Gao, S., Xiao, Y., Wu, X., Yu, M., Lin, H., & Liu, Z. (2026). Inhibition of cGAS-STING signaling and NLRP3 inflammasome-mediated pyroptosis reduces lens opacity and inflammation in high glucose-induced cataract. Cell Death Discovery. https://doi.org/10.1038/s41420-026-03382-7

Image Credits: AI Generated

DOI: 10.1038/s41420-026-03382-7

Keywords: diabetic cataract, cGAS-STING, NLRP3 inflammasome, pyroptosis, lens epithelial cells, gasdermin D, caspase-1, mitochondrial DNA, interleukin-1β, siRNA, inflammation, lens opacity

The researchers, led by Mami Amaki and Yasutomo Imai, hypothesized that caspase-1 might control IL-33 release from keratinocytes in vivo. Their reasoning drew on a parallel case: IL-1α, like IL-33, is a nuclear cytokine stored under steady-state conditions, and its extracellular release requires caspase-1. Previous studies, however, had suggested that IL-33 release is independent of caspase-1, but those conclusions came largely from non-cutaneous tissues or in vitro systems. In the airway epithelium, for example, allergen protease-activated stress granule assembly and gasdermin D fragmentation have been shown to control IL-33 secretion without caspase-1. The Japanese team suspected that the skin might operate by different rules, and their new findings support that idea.

The first technical step was to establish where caspase-1 actually resides in skin. Using immunofluorescence staining of mouse skin sections with a Cy3-conjugated anti-caspase-1 P10 polyclonal antibody, the researchers detected caspase-1 immunoreactivity in the nuclei of epidermal keratinocytes. No specific staining appeared in caspase-1/11-deficient mice, which served as negative controls. This was a significant observation because earlier studies had concluded that caspase-1 expression was restricted to hematopoietic cells, conclusions based largely on the absence of detectable interleukin-1 beta-processing activity and the limited sensitivity of the detection methods available at the time. Subsequent work with improved methodologies has revealed low-level but functional caspase-1 expression in epithelial cells, including keratinocytes. For caspase-1 to be involved in the release of a nuclear alarmin like IL-33, the protease would need to be present in keratinocyte nuclei, and the new staining data confirm exactly that.

Next, the team examined what happens to nuclear IL-33 when the skin is stimulated. They applied 20 microliters of 0.5 percent 2,4-dinitrofluorobenzene (DNFB), a contact-sensitizing hapten dissolved in acetone and olive oil, to the left ear of mice while the right ear received vehicle alone. Six hours later, they processed the ear skin for immunofluorescence staining for IL-33, using an affinity-purified rabbit anti-mouse IL-33 polyclonal antibody detected with a biotinylated goat anti-rabbit IgG secondary antibody and streptavidin-conjugated Alexa Fluor 594, with nuclei counterstained using DAPI. The disappearance of nuclear IL-33 staining in keratinocytes was interpreted as evidence that IL-33 had been released into the extracellular space, an established surrogate readout that parallels findings in experimental allergic rhinitis, where allergen challenge induces a rapid loss of IL-33 staining in nasal epithelial cells alongside increased IL-33 levels in nasal lavage fluids.

The result was striking. In wild-type mice, IL-33 fluorescence in the epidermis was substantially reduced six hours after DNFB treatment, consistent with the team’s previous report that cutaneous stimulation triggers extracellular IL-33 release in vivo. In caspase-1/11-deficient mice, however, IL-33 immunoreactivity remained clearly detectable in the nuclei of epidermal keratinocytes at the same time point. In other words, deleting caspase-1/11 prevented the DNFB-induced loss of keratinocyte IL-33. Notably, quantitative real-time PCR showed that DNFB application increased Il33 mRNA expression in both wild-type and caspase-1/11-deficient mice, even though nuclear IL-33 staining persisted in the knockout animals. This indicates that Il33 transcription is induced by DNFB independently of IL-33 release, meaning the protease is specifically required for the release step rather than for the transcriptional response.

To test whether this release mechanism matters for actual disease, the researchers crossed their caspase-1/11-deficient mice with the hK14mIL33tg transgenic line, which overexpresses murine IL-33 in keratinocytes under the control of the human keratin-14 promoter. These IL33tg mice spontaneously develop atopic dermatitis-like skin inflammation. When caspase-1/11 was deleted in this background, the resulting IL33tg Casp1/11KO mice exhibited markedly attenuated skin inflammation compared with IL33tg mice. Histological examination of hematoxylin and eosin-stained skin sections showed pronounced leukocyte and eosinophil infiltration accompanied by epidermal hyperplasia in IL33tg mice, while these pathological features were minimal in the double-deficient animals, indicating a substantially reduced inflammatory response in the absence of caspase-1/11.

The molecular signature of the type 2 immune response told the same story. Quantitative PCR analysis of skin tissue, performed with a TaqMan RNA-to-Ct Kit and an ABI7900HT sequence detection system, revealed significant reductions in the expression of type 2 cytokines including Il4, Il5, and Il13, as well as Prg2, which encodes eosinophil peroxidase and serves as a specific marker of murine eosinophils. The reduction in Prg2 expression was consistent with the histological findings showing markedly reduced eosinophil infiltration in IL33tg Casp1/11KO mice. Together, these data indicate that caspase-1/11 deficiency suppresses IL-33-driven type 2 immune responses in the skin, dampening the entire downstream allergic cascade that IL-33 normally sets in motion through ILC2 activation.

The findings carry important caveats that the authors address candidly. The knockout mice used in the study have historically been described as caspase-1-deficient, but they are now recognized to carry a combined deficiency of both caspase-1 and caspase-11, because the Casp1 and Casp11 genes lie in close genomic proximity within the same gene cluster, resulting in simultaneous disruption of both loci in this strain. The potential contribution of caspase-11 therefore cannot be formally excluded. However, previous studies indicate that epithelial inflammasome-related responses, including IL-33 regulation, are mainly mediated by caspase-1 rather than caspase-11. Caspase-11 is primarily implicated in noncanonical inflammasome signaling in myeloid cells and localizes predominantly in the cytoplasm, making its direct involvement in the nuclear export of IL-33 from keratinocytes less likely. The authors also note that loss of nuclear staining does not directly quantify extracellular IL-33 levels, so future studies using biochemical measurements will be needed to confirm the release mechanism.

There is another puzzle worth noting. Several studies have suggested a role for caspase-1 in IL-33 inactivation rather than release, since IL-33 can be inactivated after maturation by caspase-1. If caspase-1-mediated inactivation were essential in vivo, IL-33-transgenic mice lacking caspase-1/11 would be expected to show exacerbated skin inflammation, yet the opposite was observed. The authors also point out that pharmacological inhibition of caspase-1 may not fully reflect its role in alarmin release, because for IL-1α the presence of caspase-1 protein, rather than its enzymatic activity, can be required for secretion. Because caspase-1/11 was deleted in all cells in the mice used, the possibility that caspase-1 deficiency in immune cells influences IL-33-induced skin inflammation cannot be excluded, though the marked reduction in inflammation suggests that caspase-1/11 deficiency affects an early step in IL-33-driven skin inflammation, most likely IL-33 release from keratinocytes.

The broader implication is that alarmin biology may be tissue-specific in ways the field has not fully appreciated. IL-33 can be released independently of caspase-1 in other tissues, notably the airway epithelium, where gasdermin D-mediated pathways dominate. But in the skin, the new evidence suggests that caspase-1 is involved in the pathogenic release of IL-33 from keratinocytes in vivo, and that this release step is a critical control point for atopic dermatitis-like inflammation. If the findings hold up in biochemical assays and in human tissue, they could reshape how researchers think about targeting IL-33 in atopic dermatitis, pointing to the release machinery within keratinocytes as a potential therapeutic frontier alongside the IL-33-blocking antibodies already in clinical development.

Subject of Research: Immunology

Article Title: Deficiency of inflammatory caspases attenuates IL-33–mediated dermatitis

Article References: Amaki, M., Murata, T., Kanazawa, N., & Imai, Y. (2026). Deficiency of inflammatory caspases attenuates IL-33–mediated dermatitis. Journal of Cutaneous Immunology and Allergy, 9, Article 16358. https://doi.org/10.3389/jcia.2026.16358

Image Credits: AI Generated

DOI: 10.3389/jcia.2026.16358

Keywords: atopic dermatitis, IL-33, caspase-1, keratinocytes, alarmin, skin inflammation, type 2 cytokines, innate lymphoid cells, Deficiency, inflammatory, caspases, attenuates

The review, led by Rahul A. Sachdeo of Krishna Institute of Medical Sciences in Karad, India, together with colleagues from Krishna Institute of Pharmacy and the Gaurishankar Institute of Pharmaceutical Education and Research, weaves together decades of immunology research into a single framework. Its central claim is provocative: the same inflammasome complexes that protect us in the first hours after injury can, when they stay active too long, drive the persistent inflammation, tissue destruction, and scarring that turn an ordinary wound into a lifelong medical problem.

Inflammasomes are multi-protein sensors of the innate immune system, the body’s ancient first line of defense. Several family members matter in wounded skin, including NLRP3, AIM2, NLRC4, NLRP1, and Pyrin. Each sensor detects a different danger signal, from bacterial molecules to stray DNA released by damaged cells. Once triggered, an inflammasome assembles into an activation platform that switches on inflammatory caspases, most notably caspase-1. Caspase-1 then performs two critical tasks: it cleaves the inactive precursor forms of the signaling molecules interleukin-1 beta and interleukin-18 into their mature, biologically active versions, and it promotes a fiery form of programmed cell death called pyroptosis, which proceeds through pores formed by the protein gasdermin D.

In the short term, this machinery is lifesaving. Pyroptosis flushes intracellular pathogens out of infected cells, mature interleukin-1 beta recruits immune cells to clear debris and fight infection, and the resulting inflammatory signals help coordinate the earliest phases of tissue repair. Wound healing itself is a highly choreographed sequence of four overlapping stages: hemostasis, inflammation, proliferation, and remodeling. Transient inflammasome activity is what allows the wound to transition smoothly from the inflammatory phase into the proliferative phase, when new tissue is built. The trouble begins when the switch never gets flipped off.

Sustained or dysregulated inflammasome activation keeps caspase-1 running and pyroptosis churning, flooding the wound environment with inflammatory cytokines and cell contents. The result is persistent inflammation, ongoing tissue injury, and aberrant remodeling of the extracellular matrix, the protein scaffold that gives tissue its structure. Over time, this chaotic environment pushes the wound toward fibrosis, an excessive deposition of scar-like matrix, and toward the chronic wound state in which regeneration grinds to a halt. The review emphasizes that distinguishing inflammasome molecules’ roles as mechanistic mediators of this damage from their potential as measurable biomarkers and therapeutic targets is now a central task for the field.

What makes the review timely is its focus on specific molecular fingerprints. The authors catalog a broad panel of candidate biomarkers spanning the entire inflammasome pathway: the sensors themselves, the adaptor proteins that link them to caspases, the inflammatory caspases, pyroptosis-related mediators such as gasdermin D, the cytokines they release, and oxidative stress-associated factors. Oxidative stress is deeply entangled with inflammasome biology, since reactive oxygen species are known to regulate NLRP-family sensors, creating a crosstalk loop in which metabolic and inflammatory signals amplify one another. Molecules such as thioredoxin-interacting protein, which links high glucose to NLRP3 activation, illustrate how metabolic dysfunction can be read out through inflammasome-associated markers.

The review also highlights how modern genomic technologies are transforming biomarker discovery. Transcriptomic, proteomic, and metabolomic approaches can identify candidate molecules at scale, while single-cell RNA sequencing and spatial transcriptomics add two crucial dimensions: which cells are producing the signal, and where in the wound they are located. This cell-specific and spatial information matters enormously in wounds, where keratinocytes, macrophages, and fibroblasts exchange signals across a heterogeneous landscape. Recent work showing that diabetic wound keratinocytes can induce macrophage NLRP3 expression through interleukin-1 receptor signaling, and that interferon-gamma priming enables NLRP3 activation in human keratinocytes, underscores how cell-type-specific these interactions are. Such resolution, the authors argue, can improve biomarker validation and allow clinicians to stratify wound states far more precisely than current visual assessment allows.

One of the review’s most clinically valuable contributions is its comparison across wound types. Diabetic foot ulcers, pressure ulcers, venous leg ulcers, burn wounds, and fibrotic scars all involve inflammasome-mediated mechanisms, but each is driven by a distinct trigger. In diabetes, metabolic dysfunction and high glucose drive NLRP3 activation; in pressure ulcers, ischemia-reperfusion injury generates oxidative stress that aggravates tissue damage; in venous leg ulcers, venous hypertension sustains inflammatory pressure on the tissue; in burns, thermal injury releases damage-associated molecular patterns that activate inflammasomes, and studies in mouse models suggest NLRP3 activity is actually required for healing after burns; and in fibrotic scars, dysregulated tissue remodeling, often intertwined with transforming growth factor beta signaling, locks the wound into a scar-producing program. Understanding these shared and condition-specific pathways could allow therapies to be tailored to the biology of each wound rather than applied generically.

The therapeutic implications are already taking shape. Small-molecule NLRP3 inhibitors, first validated as potential treatments for inflammatory diseases, are being explored for diabetic wounds, and nanotechnology-based delivery systems and stimulus-responsive hydrogels are being designed to modulate inflammasome activity directly at the wound site. Meanwhile, smart wound dressings that monitor biological parameters in real time could eventually incorporate inflammasome-derived markers, turning a passive bandage into a diagnostic device. Cytokine ratios measured in chronic wound swabs, such as interleukin-1 beta relative to its natural antagonist the interleukin-1 receptor antagonist, have already been proposed as potential biomarkers of wound healing stage and infection status, hinting that the clinic may not be far behind the laboratory.

Challenges remain before inflammasome biomarkers reach the bedside. Inflammasome activation is context-dependent, and a marker that signals danger in one wound type may signal productive repair in another, as the burn studies suggest. Validation will require large, well-characterized patient cohorts and multi-omic profiling across wound types and healing stages. Yet the framework laid out in this review offers something chronic wound medicine has lacked: a mechanistic, measurable, and spatially resolved language for describing why some wounds heal and others stall. If that language can be translated into routine diagnostics, the millions of patients caught in the cycle of chronic inflammation and scarring may finally get the precision care their wounds demand.

Subject of Research: The role of inflammasome-derived biomarkers in wound healing, chronic inflammation, fibrosis, and precision therapeutics

Article Title: Inflammasome-derived biomarkers in wound healing: linking tissue repair, chronic inflammation, fibrosis, and precision therapeutics

Article References: Sachdeo, R. A., Khanwelkar, C., Shete, A., Patil, S. J., & Pawar, N. B. (2026). Inflammasome-derived biomarkers in wound healing: linking tissue repair, chronic inflammation, fibrosis, and precision therapeutics. Molecular Biology Reports, 53(1), Article 1610. https://doi.org/10.1007/s11033-026-12783-x

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12783-x

Keywords: inflammasome, NLRP3, wound healing, chronic wounds, pyroptosis, biomarkers, fibrosis, caspase-1, diabetic foot ulcers, interleukin-1 beta, single-cell RNA sequencing, precision medicine

The starting point of the investigation was a molecule with a double life. High mobility group box 1, or HMGB1, is a nuclear protein that normally helps organize DNA and regulate gene transcription inside healthy cells. But when cells are stressed, injured or dying, HMGB1 can be released into the surrounding tissue, where it acts as a danger signal, an alarm molecule that summons and activates the immune system. In cancer, this alarm function can backfire spectacularly. Chronic inflammation is a recognized hallmark of malignancy, and HMGB1 has previously been implicated in promoting tumor growth, invasion and metastasis in cancers ranging from hepatocellular carcinoma to colorectal and pancreatic tumors. What remained unclear was precisely how the oxygen-starved environment inside tumors regulates HMGB1, and what that regulation means for cancers of the oral cavity.

To answer that question, the researchers began with human tissue. They profiled HMGB1 expression in clinical specimens of oral squamous cell carcinoma and compared it with clinicopathological information from the same patients. The results were unambiguous: HMGB1 was constitutively upregulated in the tumor tissues, and the degree of overexpression tracked with clinically ominous features. Tumors with higher HMGB1 levels tended to be larger, and elevated expression was positively associated with lymph node metastasis, the process by which oral cancer cells spread to the neck and dramatically worsen prognosis. When the team constructed Kaplan-Meier survival curves, patients whose tumors expressed the most HMGB1 fared significantly worse than those with lower levels, marking the protein as a candidate prognostic biomarker for the disease.

With the clinical correlation established, the investigators turned to controlled experiments in cell culture to determine whether hypoxia was driving the HMGB1 surge. When oral squamous cell carcinoma cells were exposed to hypoxic conditions, their HMGB1 expression rose markedly. More importantly, the team traced what happened downstream. Hypoxia also increased the levels of NLRP3, a sensor protein that assembles into a multi-subunit complex known as the inflammasome, and of cleaved caspase-1, the proteolytic enzyme that the NLRP3 inflammasome activates. Alongside these inflammatory components, the cells accumulated HIF-1α, the master transcriptional regulator of the hypoxic response. The picture that emerged was of a coordinated pathway: low oxygen elevates HMGB1, and HMGB1 in turn sustains the activation of the NLRP3 inflammasome and its enzymatic output through caspase-1.

The functional consequences of this signaling cascade were tested by silencing HMGB1 in the cancer cells. The results showed that the protein is not merely a passive byproduct of hypoxia but an active driver of malignant behavior. When HMGB1 was knocked down, the hypoxia-induced expression of NLRP3, cleaved caspase-1 and HIF-1α all fell, indicating that HMGB1 sits upstream of the entire axis. Hypoxia alone had markedly enhanced the proliferation of the oral cancer cells, and it also induced pyroptosis, an inflammatory form of programmed cell death executed by gasdermin pores that release interleukin-1 family cytokines. Intriguingly, hypoxia alleviated a G2/M phase arrest in the cell cycle, freeing the cells to progress through division more readily. All of these pro-tumor effects were reversed when HMGB1 was depleted, demonstrating that the molecule is required for hypoxia to exert its full malignant influence on oral cancer cells.

The interplay between hypoxia, inflammation and cell death revealed here is more nuanced than a simple growth signal. Pyroptosis is classically viewed as an anti-cancer process, since it inflames the tumor bed and can alert immune cells to the presence of abnormal tissue. Yet the new findings suggest that in the hypoxic context of oral squamous cell carcinoma, the HMGB1-driven inflammasome activity coexists with, and may even support, enhanced proliferation. The authors propose that the net effect of the pathway is pro-tumor: the same caspase-1 activation that triggers inflammatory death in some cells appears to accompany conditions that release surviving cells from cell cycle constraints and accelerate their expansion. This kind of dual role echoes a broader theme in tumor immunology, in which inflammatory pathways that evolved to fight infection can be co-opted by cancers to remodel their microenvironment in self-serving ways.

Critical evidence came from animal models, where the team could test whether the pathway mattered in the complexity of a living organism rather than a culture dish. In murine xenograft models, in which human oral cancer cells are implanted into mice, knocking down HMGB1 inhibited tumor growth. Separately, the researchers examined the downstream links of the axis using models deficient in NLRP3 or caspase-1, and found that loss of either component delayed the progression of oral cancer. To extend the relevance beyond transplanted tumors, the team also employed a 4-NQO-induced carcinogenesis protocol, a chemically induced model that recapitulates the stepwise development of oral squamous cell carcinoma in mice, from premalignant lesions to invasive cancer. Together, these in vivo experiments established that the HMGB1/NLRP3/caspase-1 axis is not an artifact of cell culture but a functional driver of tumor progression in intact animals.

The study builds on a substantial body of prior work implicating both HMGB1 and the NLRP3 inflammasome in head and neck malignancies. Earlier research from some of the same collaborators had shown that NLRP3 promotes tumor growth and metastasis in oral squamous cell carcinoma, that a microRNA called miR-22 suppresses oral cancer cell proliferation by targeting NLRP3, and that NLRP3 expression in tumor-associated macrophages predicts poor prognosis in head and neck squamous cell carcinoma. Other groups had connected hypoxia-induced HMGB1 to tumor growth in liver cancer through Toll-like receptor 9, and to the self-renewal of glioma stem cells through the receptor RAGE. The new study unifies these threads by placing HMGB1 upstream of the inflammasome in a hypoxia-dependent pathway specific to oral cancer, and by validating the entire axis from clinical specimens through cell biology to animal models.

Therapeutically, the findings point to a strategy that differs from conventional approaches. Because HMGB1 is upregulated in tumor tissue and correlates with poor outcomes, it offers both a biomarker for identifying high-risk patients and a target for intervention. Blocking the pathway at any of its three nodes, whether by neutralizing HMGB1, inhibiting NLRP3 assembly or suppressing caspase-1 activity, delayed cancer progression in the experimental systems. Inflammasome inhibitors are already an active area of drug development for inflammatory and metabolic diseases, and HMGB1-targeting agents have been explored in contexts from acute liver failure to sepsis. The new data suggest that repurposing or refining such inhibitors for oral squamous cell carcinoma, particularly for tumors with documented hypoxia and high HMGB1 expression, could be a viable avenue. The authors also note that hypoxia itself is a known barrier to radiotherapy and immunotherapy, so a pathway that links hypoxia to inflammatory tumor promotion may help explain why some oral cancers resist current treatments.

Oral squamous cell carcinoma remains a disease with a heavy global burden, particularly in regions where tobacco use, alcohol consumption and betel quid chewing are prevalent, and survival rates for advanced disease have improved only modestly in recent decades. A molecular axis that connects the tumor’s oxygen-starved core to inflammatory proliferation, and that is measurable in clinical specimens and targetable in animal models, offers a fresh angle of attack. As with all preclinical research, the distance between xenograft mice and patients is considerable, and questions remain about how best to inhibit the pathway without suppressing the beneficial inflammatory responses that guard against infection. But the study provides a clear mechanistic blueprint: hypoxia raises HMGB1, HMGB1 activates the NLRP3 inflammasome, caspase-1 carries the signal forward, and oral cancer cells proliferate. Interrupting that relay, the researchers conclude, may offer a viable therapeutic strategy for a cancer that urgently needs new options.

Subject of Research: Hypoxia-induced HMGB1/NLRP3/Caspase-1 inflammatory signaling in oral squamous cell carcinoma progression

Article Title: Hypoxia-induced HMGB1/NLRP3/Caspase-1 signaling axis enhances proliferation of oral squamous cell carcinoma

Article References: Wu, K., Zhang, S., Cao, L., Wang, J., Wang, M., Zheng, Z., & Feng, X. (2026). Hypoxia-induced HMGB1/NLRP3/Caspase-1 signaling axis enhances proliferation of oral squamous cell carcinoma. British Journal of Cancer. https://doi.org/10.1038/s41416-026-03632-6

Image Credits: AI Generated

DOI: 10.1038/s41416-026-03632-6

Keywords: oral squamous cell carcinoma, hypoxia, HMGB1, NLRP3 inflammasome, caspase-1, pyroptosis, HIF-1α, tumor microenvironment, prognostic biomarker, inflammation, xenograft model, cancer therapy

Pyroptosis is not an ordinary death. It is a programmed, highly inflammatory form of cell suicide that serves as an alarm system for the immune system. It is triggered when pathogen-associated or danger-associated molecular patterns are detected in the cytosol, the fluid interior of the cell. Upon sensing these threats, caspase-1 in humans and mice, along with caspase-4, caspase-5 in humans and caspase-11 in mice, cleaves a protein called gasdermin D, or GSDMD. This cleavage releases the N-terminal fragment of GSDMD, which migrates to the cell membrane and oligomerizes into pores. These pores disrupt the osmotic balance of the cell, allowing water to rush in, causing the cell to swell, burst and spill its inflammatory contents, including the potent cytokine interleukin-1β, into the surrounding tissue.

While this fiery demise is useful for containing infection, overactive pyroptosis is a driver of disease. Excessive pyroptotic cell death has been implicated in atherosclerosis, arthritis, Alzheimer’s disease, HIV and various types of cancer. This has made the inflammatory caspases attractive drug targets, and caspase inhibitors have captured the attention of scientists and clinicians alike. Yet developing safe and clinically effective caspase inhibitors has proven remarkably difficult. The central problem is selectivity. Caspases are a family of proteases with overlapping substrate preferences, which makes it difficult to inhibit one member without affecting others. Many existing inhibitors block caspases involved in both pyroptosis and apoptosis, the quiet, non-inflammatory form of cell death that is essential for development and immunity. Worse, inhibiting caspase-8 can sensitize cells to necroptosis, another damaging form of cell death, potentially trading one pathology for another.

To escape this trap, Groborz and colleagues took a rational, chemistry-driven approach. They exploited the known substrate preferences of individual caspases to synthesize a library of roughly one hundred tetrapeptides, each attached to an acyloxymethyl ketone, or AOMK, group. These reactive chemical groups allow the tetrapeptides to bind covalently and irreversibly to the active sites of their target caspases, ensuring durable inhibition. From this library, several candidates emerged that suppressed cell death driven by caspase-1, caspase-4 and caspase-11 while leaving staurosporine-induced apoptosis untouched. One of the most potent, named KGR-3, stood out as a strong inhibitor of caspase-1 and caspase-4.

The detailed characterization of KGR-3 revealed just how precisely it worked. The compound blocked pyroptosis by preventing the cleavage of GSDMD, thereby stopping pore formation at its source. It also attenuated the release of interleukin-1β and lactate dehydrogenase, a standard marker of membrane rupture, in response to activation of the NLRP3 and NLRP1 inflammasomes, the multiprotein complexes that activate caspase-1. Crucially, KGR-3 did not interfere with hallmarks of apoptosis such as caspase-1-induced blebbing or caspase-3 cleavage, nor did it affect necrosis triggered by listeriolysin O, a bacterial toxin. Cells treated with KGR-3 not only avoided death; their swelling and lysis were suppressed and they continued to grow and divide. The inhibitor appeared to grant cells a genuine reprieve rather than merely delaying the inevitable.

Yet a puzzling observation threatened to undermine the whole story. KGR-3 and its chemical siblings showed limited permeability in healthy cells, meaning they should not have been able to reach the intracellular caspases they so effectively inhibited. This paradox led the authors to a bold hypothesis: pyroptosis itself facilitates inhibitor uptake. Like a Trojan horse being wheeled through the gates of a besieged city, the caspase inhibitors were exploiting the very pores formed during pyroptosis to slip inside and reach the caspases driving the process. To test this idea, the researchers used propidium iodide and YOYO-1, two small fluorescent molecules that normally cannot cross intact membranes. Both entered cells in a GSDMD-dependent manner, providing strong evidence that gasdermin pores admit small molecules from the outside.

The story became even more sophisticated when the researchers examined what happened to the membrane damage inflicted along the way. In KGR-3-treated cells, GSDMD-induced membrane injury was repaired by the endosomal sorting complexes required for transport, known as the ESCRT machinery. This repair system is a conserved cellular mechanism that seals small membrane wounds. When the researchers expressed dominant-negative versions of the ESCRT proteins VPS4A and CHMP3, KGR-3 lost its protective effect, and pyroptosis proceeded. This finding challenges the simple binary view of pyroptosis as an irreversible commitment to death. Instead, it suggests a pharmacologically accessible window between the initiation of pyroptosis and final lysis, a period during which GSDMD pores disrupt the membrane enough to admit the drug, but not so extensively that repair by ESCRT becomes impossible. Recent research has independently highlighted the reversibility of GSDMD pore formation and shown that ESCRT can limit pyroptosis and cytokine secretion after inflammasome activation, lending further support to this model.

There is also an elegant pharmacological lesson hidden in the poor permeability of these compounds. In traditional drug development, limited cell permeability is considered a weakness. Here, it becomes a feature. Because the inhibitors can only enter cells whose membranes have already been breached by gasdermin pores, they are restricted to unhealthy cells, those actively undergoing pyroptosis, and are excluded from healthy neighbors. This built-in targeting mechanism could limit the off-target effects that have plagued broader caspase inhibitors, offering a new design principle: drugs need not always be membrane permeable if the disease state itself creates the doorway. The study thus overturns the conventional assumption that any drug aimed at an intracellular target must be able to cross an intact plasma membrane.

Translating the concept into animals required further chemical refinement. KGR-3 itself showed limited efficacy in vivo, but another tetrapeptide from the library, KGR-53, proved more promising. It was selected for animal testing because of its potent inhibition of caspase-11, a key mediator of endotoxic shock induced by lipopolysaccharide in mice. Because negatively charged compounds are transported inefficiently through GSDMD pores, the team designed a derivative called KGR-53P that lacks a negative charge. This optimized compound inhibited GSDMD cleavage and blocked the caspase-1- and caspase-11-dependent secretion of interleukin-1β and interleukin-18, while leaving both intrinsic and extrinsic apoptosis intact. In a mouse model of endotoxic shock, a condition driven by runaway caspase-11 activity, this selectivity could prove decisive.

The work is not without caveats, as Henry and O’Neill note in their highlight. First, the entry of KGR-3 through GSDMD pores has not been directly visualized. Although the GSDMD-dependent uptake of propidium iodide and YOYO-1 strongly implies that the pores serve as entry routes for small molecules, attempts to image KGR-3 itself failed because fluorescent tagging compromised the compound’s potency, permeability or toxicity. Second, KGR-53 showed evidence of liver toxicity in vivo, and it remains unclear whether this toxicity stems from the AOMK chemistry, an off-target effect or an entirely different mechanism. These open questions will shape the next phase of research. Even so, the conceptual advance is considerable. If the window between pyroptosis initiation and lysis can be reliably exploited, a new class of anti-inflammatory drugs could emerge that intervene only where inflammation is already burning, leaving healthy tissue untouched. The gates that pyroptosis opens may, in the end, become the route by which medicine tames it.

Subject of Research: Selective inflammatory caspase inhibitors that enter cells through gasdermin D pores to inhibit pyroptosis

Article Title: A Trojan horse story: does pyroptosis open the gates to its own inhibition?

Article References: Henry, Ó. C., & O’Neill, L. A. J. (2026). A Trojan horse story: does pyroptosis open the gates to its own inhibition?. Cell Research. https://doi.org/10.1038/s41422-026-01302-z

Image Credits: AI Generated

DOI: 10.1038/s41422-026-01302-z

Keywords: pyroptosis, gasdermin D, inflammatory caspases, caspase-1, caspase-11, GSDMD, ESCRT, inflammasome, cell death, innate immunity, drug design, inflammation

To appreciate why this result has generated attention, it helps to understand what the NLRP3 inflammasome actually is. The inflammasome is a multiprotein complex assembled inside innate immune cells such as macrophages and monocytes when they detect danger signals. NLRP3, a member of the NOD-like receptor family of pattern-recognition proteins, acts as the sensor component of the complex. When activated by an extraordinarily diverse array of triggers, ranging from bacterial toxins and viral RNA to crystals of monosodium urate and cholesterol, as well as metabolic stress and mitochondrial dysfunction, NLRP3 recruits the adaptor protein ASC, which in turn recruits and enables procaspase-1 to cleave itself into active caspase-1. Active caspase-1 then processes the immature pro-inflammatory cytokines interleukin-1 beta and interleukin-18 into their mature, secreted forms, and also triggers gasdermin D cleavage, the executive step of a lytic inflammatory cell death programme called pyroptosis.

The consequences of this pathway reaching the circulation are profound. Interleukin-1 beta is one of the most potent pyrogenic and inflammatory cytokines in the body, and excessive or misplaced NLRP3 activation has been implicated in an impressive list of human conditions. These include gout and other crystal arthropathies, atherosclerosis, type 2 diabetes, non-alcoholic fatty liver disease, inflammatory bowel disease, chronic kidney disease, age-related macular degeneration, and a family of rare autoinflammatory syndromes known collectively as cryopyrin-associated periodic syndromes, which arise from gain-of-function mutations in the NLRP3 gene itself. Growing evidence also links inflammasome-driven neuroinflammation to neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease, a connection of particular interest to the Penney laboratory, whose work focuses on the metabolic underpinnings of neurodegeneration. The NLRP3 inflammasome has therefore become one of the most intensively pursued drug targets in immunology, with pharmaceutical companies developing direct NLRP3 inhibitors, interleukin-1 blocking biologics, and compounds that interfere with downstream caspase-1 or gasdermin D activity.

Against this backdrop, the Liu study adds something genuinely new: a naturally occurring nutrient that appears to restrain the pathway at the level of the inflammasome itself. Arginine occupies an unusual position in human metabolism. It is classified as semi-essential, meaning that although the body can synthesise it, endogenous production may not always meet demand, particularly during periods of rapid growth, illness, or metabolic stress. The amino acid sits at a busy metabolic crossroads. It is the obligate substrate for nitric oxide synthase enzymes, which generate the vasodilatory and immunoregulatory signalling molecule nitric oxide. It is also cleaved by arginase enzymes into urea and ornithine, feeding the urea cycle and the polyamine biosynthesis pathway, and it serves as a precursor for creatine, proline, and glutamate. Because different immune cell populations express different complements of arginine-metabolising enzymes, arginine availability shapes immune responses in ways that have been appreciated for years, most famously in the context of tumour immunology, where myeloid-derived suppressor cells deplete arginine from the tumour microenvironment to blunt T cell function.

Previous work had already hinted at an anti-inflammatory dimension to arginine biology. Studies in cell culture and animal models had reported that arginine supplementation could reduce inflammatory cytokine production in certain settings, and clinical nutrition research had explored arginine’s effects in surgical recovery, wound healing, and critically ill patients, with mixed but occasionally encouraging results. What remained unclear was whether these effects reflected a direct action on inflammasome signalling or indirect consequences of altered metabolism, improved blood flow, or changes in the broader cytokine milieu. The Liu study, as framed by Truong, Trainor and Penney, addresses this gap by demonstrating that l-arginine can inhibit inflammasome activation, positioning the amino acid as a modulator of the NLRP3 pathway itself rather than a general anti-inflammatory agent acting at a distance.

The technical significance of such a mechanism deserves emphasis. Inflammasome activation proceeds through a carefully choreographed sequence that typically requires two signals. The first, often initiated when a pathogen-associated molecular pattern engages a toll-like receptor, primes the cell by inducing transcription of NLRP3 and pro-interleukin-1 beta through the NF-kappa B pathway. The second signal, delivered by any of the heterogeneous NLRP3 triggers, sets off a chain of post-translational events including NLRP3 deubiquitination, oligomerisation, and the recruitment of ASC into large punctate specks visible under the microscope. A compound that interferes with this assembly process, or with the upstream events that license it, can suppress the release of mature interleukin-1 beta without broadly disabling the innate immune system, which is precisely the therapeutic window that inflammasome drug developers have been trying to occupy. A nutrient that achieves a version of this effect through a dietary route would be remarkable, because it would suggest that the inflammasome is wired to sense and respond to nutritional state, integrating metabolic information into immunological decision-making.

This idea fits within a broader and rapidly growing field of immunometabolism, which examines how cellular metabolic pathways govern immune cell behaviour. It is now well established that macrophages polarising toward an inflammatory phenotype undergo a metabolic shift resembling the Warburg effect, favouring glycolysis even in the presence of oxygen, while accumulating broken tricarboxylic acid cycle intermediates that themselves feed back into inflammatory signalling. Succinate, for example, stabilises hypoxia-inducible factor 1-alpha and drives interleukin-1 beta production, whereas itaconate, an immune cell-derived metabolite, acts as an endogenous anti-inflammatory brake. Itaconate has already inspired a class of drug development efforts built around its cell-permeable derivatives. Arginine, on the evidence highlighted in the Nature Metabolism commentary, may now join the ranks of metabolites that function as genuine immunological signalling molecules rather than mere metabolic substrates.

The commentators also situate the finding in a therapeutic landscape that is already crowded but far from solved. Direct NLRP3 inhibitors have shown promise in clinical trials for a range of inflammatory conditions, and interleukin-1 targeted biologics such as anakinra, canakinumab and rilonacept are approved for specific autoinflammatory and cardiovascular indications, with the canakinumab anti-inflammatory thrombosis outcomes study having demonstrated reduced cardiovascular event rates in patients treated with the antibody. Yet these biologics are expensive, require injection, and carry infection risks inherent to dampening innate immunity. A dietary supplement that modulates the same pathway upstream would, if validated, offer a fundamentally different risk-benefit profile, cost structure, and route of administration. The authors of the commentary explicitly highlight the potential of dietary arginine supplementation as a treatment for NLRP3-related disease, a statement that will inevitably capture the imagination of both researchers and the public.

Caution, however, is warranted, and the commentary itself is framed as a preview of promising early science rather than a prescription. Arginine supplementation is not without complications. High doses can cause gastrointestinal discomfort and, because arginine is a nitric oxide precursor, can influence blood pressure and vascular tone in ways that may be undesirable in some patients. In certain disease contexts, arginine metabolism can be co-opted by pathogens and tumours, and the balance between nitric oxide synthase and arginase activity determines whether arginine availability is helpful or harmful. Moreover, translating cell culture and animal findings into safe and effective human supplementation requires careful dose-ranging, attention to pharmacokinetics, and trials in well-defined patient populations. The history of nutrition science is littered with nutrients that looked spectacular in preclinical models and failed to deliver in randomised trials, a pattern that any responsible reading of this work must acknowledge.

Even with those caveats, the convergence of this study with parallel lines of evidence makes the moment notable. Recent literature has linked arginine metabolism to neuroinflammation and neurodegenerative disease, to the metabolic dysfunction that accompanies ageing, and to the regulation of macrophage activation states, and the accompanying commentary argues that these threads now weave together into a coherent picture in which arginine availability is a meaningful determinant of inflammasome activity. If subsequent work confirms the mechanism, identifies the molecular point at which arginine intervenes in the NLRP3 assembly cascade, and demonstrates therapeutic benefit in humans, the field may look back on this as an early milestone in the use of targeted nutrition to control pathological inflammation. For now, the study stands as a striking reminder that the boundary between metabolism and immunity is porous, and that the molecules on our dinner plates are participants in the molecular conversations that decide when our immune systems hold their fire and when they ignite.

Subject of Research: Inhibition of the NLRP3 inflammasome by the amino acid l-arginine

Article Title: Arginine inhibits a key innate immune signalling hub

Article References: Truong, Q. N., Trainor, A. R., & Penney, J. (2026). Arginine inhibits a key innate immune signalling hub. Nature Metabolism. https://doi.org/10.1038/s42255-026-01638-1

Image Credits: AI Generated

DOI: 10.1038/s42255-026-01638-1

Keywords: NLRP3 inflammasome, arginine, innate immunity, inflammation, interleukin-1 beta, immunometabolism, caspase-1, pyroptosis, macrophages, nitric oxide, inflammatory disease, dietary supplementation

NLRP3, short for NOD-like receptor pyrin domain 3, is a pattern-recognition protein that assembles into a multi-protein machine known as an inflammasome. When the sensor detects danger signals, ranging from cholesterol crystals to products of cellular damage, it triggers the enzyme caspase-1, which in turn processes the inflammatory messengers interleukin-1 beta and interleukin-18. Caspase-1 also cleaves Gasdermin D, producing an N-terminal fragment that punches pores in the cell membrane and initiates a fiery form of cell death called pyroptosis. Inflammasome hyperactivation is already infamous in human medicine: inherited gain-of-function mutations in NLRP3 cause cryopyrin-associated periodic syndromes, devastating autoinflammatory diseases. What has been missing is direct in vivo evidence showing what happens when this same sensor is chronically overactive specifically within the smooth muscle cells of the artery wall.

To answer that question, the team, led by Yun-Ting Wang, Xiang Li, and Yang Zhang, engineered a mouse carrying an Nlrp3 gain-of-function mutation, the L351P variant, exclusively in vascular smooth muscle cells by combining the knock-in allele with a Myh11-driven Cre recombinase. This model, dubbed Nlrp3-SMKI, allowed the investigators to isolate the contribution of smooth muscle-intrinsic inflammasome signaling from the contributions of immune cells and endothelium. The researchers then subjected these animals and control mice to partial ligation of the carotid artery under hypercholesterolemic conditions, a well-established surgical model that produces disturbed blood flow, endothelial dysfunction, and rapid development of neointimal lesions that mimic human restenosis and early atherosclerosis.

The results were striking even before any surgical injury was applied. In unligated arteries of the mutant mice, the team already detected elevated caspase-1 activation-associated signaling, indicating that the hyperactive inflammasome was quietly simmering within the vessel wall under baseline conditions. When the carotid artery was partially ligated, this inflammatory activity surged further, revealing that the gain-of-function mutation primed the smooth muscle cells to mount an exaggerated response to vascular stress. In other words, the mutation did not merely add inflammation after injury; it fundamentally lowered the threshold at which the arterial wall responded to danger.

Downstream of caspase-1, the pathological cascade unfolded across multiple fronts. The ligated arteries of the mutant mice showed heightened vascular inflammation, marked by increased expression of VCAM1, an adhesion molecule that recruits inflammatory cells, and by greater accumulation of macrophage-associated signals within the vessel wall. The researchers also documented enhanced Gasdermin D and Gasdermin D N-terminal-associated signaling, the molecular signature of pyroptotic cell injury, together with increased numbers of TUNEL-positive cells indicating cell death. These findings weave smooth muscle cells into the inflammatory fabric of the lesion in a way that earlier cell-culture studies had suggested but could not prove in a living organism.

The functional consequence was a dramatically worsened structural outcome. Neointimal lesion growth was significantly exacerbated in the mutant animals, as measured by increased intimal area and an elevated intima-to-media ratio, the standard metrics of pathological vessel thickening. Because the only genetic difference between the experimental and control groups was the hyperactive Nlrp3 allele confined to smooth muscle cells, the study provides compelling causal evidence that smooth muscle-intrinsic inflammasome signaling is not a passive bystander in intimal hyperplasia but an active driver of lesion expansion.

Perhaps the most clinically provocative finding concerned lipid metabolism. The injured arteries of the mutant mice accumulated more lipid and displayed foam cell-like remodeling, including within regions containing alpha-smooth muscle actin-positive cells. Foam cells, the cholesterol-engorged cells that define atherosclerotic plaques, have traditionally been associated with macrophages, but a growing body of literature shows that vascular smooth muscle cells can undergo phenotypic switching and adopt foam cell characteristics, becoming a major and underappreciated cellular component of plaques. The new data indicate that NLRP3 hyperactivation within smooth muscle cells actively promotes this lipid-laden transformation in the injured arterial wall, linking inflammasome signaling directly to one of the hallmarks of atherosclerosis.

Beneath these observations, the researchers uncovered a possible mechanistic explanation involving cellular housekeeping. The mutant arteries showed reduced expression of transcription factor EB, or TFEB, the master regulator of lysosomal biogenesis and autophagy, along with altered expression of lysosome- and autophagy-related markers. TFEB orchestrates the cell’s waste-disposal and recycling systems, and previous work by some of the same investigators showed that activating TFEB ameliorates smooth muscle dedifferentiation and neointima formation in mice fed a high-fat diet. The new findings suggest that NLRP3 hyperactivation may disrupt these stress-adaptive pathways, leaving smooth muscle cells less able to digest damaged proteins, clear lipids, and maintain their contractile identity during vascular remodeling. The association between inflammasome overactivity and impaired lysosomal-autophagic function offers an attractive framework for understanding how inflammation and metabolic dysfunction reinforce each other in the diseased artery.

The clinical implications are considerable. Cardiovascular disease remains the leading cause of death worldwide, and while statins and the anti-inflammatory antibody canakinumab have demonstrated that taming inflammation reduces cardiovascular events, broadly suppressing the immune system carries risks. The new study suggests that a more precise strategy, targeting NLRP3-associated signaling specifically within vascular smooth muscle cells, could limit restenosis after stenting or bypass grafting and slow plaque progression without wholesale immunosuppression. Several NLRP3 inhibitors are already in development for other inflammatory conditions, and the mouse model created by the Houston and Richmond team provides a platform for testing whether such compounds can keep injured arteries open. As with all murine studies, translation to human patients will require careful validation, and the authors note that their data establish associations alongside causal effects that warrant further mechanistic dissection. Still, by pinpointing a single molecular sensor in a single cell type as a linchpin of arterial thickening, the work transforms our understanding of what happens inside a vessel wall after injury, and it offers a concrete molecular bullseye for the next generation of cardiovascular anti-inflammatory therapies.

Subject of Research: The role of vascular smooth muscle NLRP3 inflammasome hyperactivation in arterial intimal hyperplasia and restenosis

Article Title: Vascular smooth muscle-specific NLRP3 hyperactivation exacerbates arterial intimal hyperplasia in mice

Article References: Wang, Y.-T., Moura, A. K., Zuo, R., Gao, W., McConnell, B. K., Li, G., Li, P.-L., Li, X., & Zhang, Y. (2026). Vascular smooth muscle-specific NLRP3 hyperactivation exacerbates arterial intimal hyperplasia in mice. Journal of Molecular Medicine, 104(1), Article 116. https://doi.org/10.1007/s00109-026-02724-3

Image Credits: AI Generated

DOI: 10.1007/s00109-026-02724-3

Keywords: NLRP3, inflammasome, vascular smooth muscle cells, intimal hyperplasia, restenosis, caspase-1, Gasdermin D, pyroptosis, TFEB, lysosome-autophagy, foam cells, atherosclerosis

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: Ajoolabady, A., Kim, B., Tuomilehto, J., Pratico, D., Ren, J., & Harrath, A. H. (2026). Pyroptosis in Patients with Ovarian Dysfunction and Infertility: Molecular Mechanisms and Therapeutics. Reproductive Sciences. 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