The starting observation is stark. When tumor cells detach and enter the circulation, most die. They face shear stress from blood flow, a form of programmed cell death called anoikis that kills cells deprived of their normal anchoring, and constant patrolling by immune cells. Only a small fraction survive. But CTCs that travel in clusters fare dramatically better. Previous work has shown that the metastatic potential of CTC clusters is twenty-three to fifty times higher than that of single CTCs, and that approximately ninety-seven percent of metastatic events are mediated by clustered cells rather than lone travelers. These clusters come in several forms: homotypic aggregates of tumor cells sticking to each other, and heterotypic aggregates in which tumor cells bind to platelets, neutrophils, myeloid-derived suppressor cells, or even unusual T cell subsets. Each configuration carries its own protective logic, and the new study argues that understanding that logic is essential before designing drugs to break it.

The platelet component is perhaps the most visually striking. In CTC-positive samples from patients with lung cancer, breast cancer, or melanoma, roughly sixty to eighty-three percent of CTCs are associated with platelet clusters. Platelets adhere to tumor cells through two main mechanisms: P-selectin on the platelet surface recognizes complementary ligands on CTCs, and activated integrin αIIbβ3 binds fibrinogen, which acts as a molecular glue bridging the two cell types. Once attached, platelets confer several advantages. They reduce mechanical injury from shear stress, secrete cytokines that suppress natural killer cell function by lowering expression of the activating receptor NKG2D, induce epithelial-mesenchymal transition through platelet-derived growth factors and TGF-β, and educate CTCs through paracrine signaling to reinforce stem-like phenotypes. Platelet surface PD-L1 can also engage PD-1 on T cells directly, suppressing T cell function and allowing the tumor cell to hide behind a borrowed immunosuppressive shield.

Neutrophils provide a second layer of protection through a different mechanism. CTC surface VCAM-1 binds VLA-4 on neutrophils, and neutrophils respond by releasing neutrophil extracellular traps, or NETs, web-like structures of DNA and antimicrobial proteins that physically capture CTCs and promote cluster formation. Neutrophils also secrete arginase 1, interleukin-10, and reactive oxygen species, which deplete arginine needed for T cell function and directly inhibit T cell and NK cell activation. Enzymes called cathepsin G and elastase released by neutrophils degrade components of the vascular basement membrane, facilitating intravascular migration of CTCs. A particularly unusual partner is the CD4-positive CD8-positive double-positive T cell, a T cell lineage that exhibits immune desensitization upon interaction with CTCs; blocking VLA-4 with neutralizing antibodies disrupts these clusters and prolongs survival in mouse models. Together, platelets and neutrophils form what the authors describe as an immune-protective niche, a mobile microenvironment that travels with the tumor cells and neutralizes the body’s primary defenses.

NNMT enters this picture as a metabolic linchpin. The enzyme catalyzes the conversion of nicotinamide to 1-methylnicotinamide, consuming the universal methyl donor S-adenosylmethionine, or SAM, in the process. This consumption depletes SAM, which alters epigenetic regulation by reducing histone methylation marks such as H3K27me3, and it disrupts NAD-dependent deacetylases like SIRT1. In multiple cancers, high NNMT expression is associated with CTC stemness, chemoresistance, and metastatic potential. In cancer-associated fibroblasts, NNMT promotes H3K27me3 hypomethylation, enhancing complement secretion and recruitment of immunosuppressive myeloid-derived suppressor cells. Pericyte-derived NNMT promotes CTC-neutrophil cluster formation through the CXCL5/CXCR2 axis, and NNMT inhibition has been shown in preclinical models to disrupt these clusters and suppress metastasis. NNMT therefore represents a central node linking metabolic reprogramming and immune evasion in the pre-metastatic niche, and the new study asks whether its activity is coordinated with the platelet and neutrophil programs rather than acting in isolation.

To answer that question, the researchers built a hypothesis-generating computational framework rather than a traditional laboratory experiment. They analyzed bulk RNA sequencing data from 9,596 primary tumor samples across 30 cancer types from the TCGA PanCancer dataset, and cross-validated their findings in eight publicly available single-cell RNA sequencing cohorts representing eight different cancer types, encompassing 483,590 individual cells. They constructed module scores for five biological programs: epithelial-mesenchymal transition and metabolism, platelet and coagulation activity, neutrophil and NET formation, immune checkpoint and exhaustion, and cytotoxic NK cell function. A composite tri-axis score, averaging the first four programs, served as a summary measure of the protective state. Across 29 of 30 TCGA cancer types, NNMT expression was positively correlated with this composite score, with all 29 correlations reaching statistical significance after false discovery rate correction. The median cross-cancer Spearman correlation coefficient for the composite score was 0.500, with the strongest coupling observed in breast cancer, colorectal cancer, melanoma, hepatocellular carcinoma, and lung cancer.

Feature-level pseudotime analysis, which orders cells along a trajectory of increasing NNMT-associated state, showed that the metabolic, platelet, neutrophil, and immune exhaustion programs converged toward a common endpoint, suggesting coordinated activation rather than independent processes. In silico perturbation experiments, in which the researchers computationally reduced NNMT expression to the tenth percentile of its cohort-specific distribution, predicted the largest reductions in the composite protection score in colorectal-cancer stromal cells and lung fibroblasts, followed by breast-cancer CAFs and endothelial cells. This points to stromal and fibroblast-like populations as candidate NNMT-dependent compartments, a finding consistent with prior experimental work showing that NNMT in cancer-associated fibroblasts remodels the tumor microenvironment. Ligand-receptor mapping further revealed an interconnected communication network: CTCs and stromal cells recruit myeloid and NET-forming cells through CXCL5-CXCR2 and VCAM1-ITGA4 signaling, platelet-coagulation bridging forms a protective coating through fibrinogen-αIIbβ3 and P-selectin-PSGL1 interactions, and the myeloid and platelet compartments transmit immunosuppressive signals to T and NK cells through LGALS9-HAVCR2, CD274-PDCD1, PVR-TIGIT, and TGFB1-TGFBR axes.

The authors also applied supervised machine learning to test whether these axis-related features could discriminate single CTCs from clustered or leukocyte-associated CTC states. In a dataset of 281 CTC-labeled cells from GSE109761, a model combining axis features with ligand-receptor features achieved a cross-validated AUROC of 0.711, suggesting that the protective state is detectable at the single-cell level. Cross-cancer generalization was tested using leave-one-cancer-out cross-validation on TCGA data with three-year overall survival as the endpoint, and while the pooled AUROC of 0.575 was modest and unsuitable for diagnosis, the signal was reproducible across cancer types, supporting the idea that the NNMT-associated tri-axis program carries real biological information rather than being an artifact of any single tumor type.

From these findings, the researchers propose a triple-intervention strategy they call disaggregation, exposure, and clearance. The first step uses αIIbβ3 inhibitors such as tirofiban or abciximab, already approved for acute coronary syndromes, to disrupt platelet-CTC adhesion and remove the platelet cloak. The second step uses NNMT inhibitors, which remain in preclinical development, to weaken the metabolic and epigenetic resilience of CTC clusters and potentially reverse epithelial-mesenchymal plasticity, making cells more recognizable to the immune system. The third step deploys PD-1/PD-L1 antibodies to restore T cell and NK cell-mediated clearance of the now-exposed tumor cells. The authors are careful to note that no experimental studies have yet demonstrated the efficacy of combining these three drug classes, and that the synergistic effect between NNMT inhibitors and αIIbβ3 inhibitors currently constitutes a theoretical hypothesis rather than a verified therapeutic regimen.

The study also confronts the risks inherent in such a combination. αIIbβ3 inhibition carries bleeding risk, particularly in cancer patients who may already have low platelet counts, and PD-1/PD-L1 blockade can in rare cases induce immune-mediated thrombocytopenia, potentially compounding the danger. NNMT inhibition is not intrinsically tumor-cell specific, and because NAD salvage and SAM-dependent methylation are also important for T cell and NK cell proliferation and function, systemic NNMT inhibition could theoretically impair the very immune cells the strategy aims to unleash. The authors propose a staged preclinical framework involving phenotypic characterization of patient-derived CTC clusters, multicellular co-culture under physiologically relevant shear flow, immune killing assays, and animal metastasis models, with sequential dosing tested as a design variable rather than assumed to be safe. They also emphasize that CTC clusters represent only one stage of the metastatic cascade, and that even complete clearance of circulating CTCs cannot prevent progression of micrometastatic lesions already established in distant organs. The most appropriate clinical application, they suggest, may be as adjuvant treatment after primary tumor resection in patients at high risk of recurrence, potentially combined with anti-angiogenic agents or stromal modulators targeting micrometastatic niches. Whether the triple strategy can move from computational hypothesis to clinical reality will depend on the experimental validation the authors themselves identify as the critical next step.

Subject of Research: Computational analysis of NNMT-associated metabolic, thromboinflammatory, and immune co-activation in heterogeneous circulating tumor cell clusters

Article Title: NNMT-associated metabolic–thromboinflammatory–immune co-activation in heterogeneous CTC clusters: a hypothesis-generating computational framework”

Article References: Gong, J., Wang, Z., Shi, Y., Ren, M., Li, T., Li, G., & Peng, R. (2026). NNMT-associated metabolic–thromboinflammatory–immune co-activation in heterogeneous CTC clusters: a hypothesis-generating computational framework”. BMC Cancer, 26(1), Article 1085. https://doi.org/10.1186/s12885-026-16692-x

Image Credits: AI Generated

DOI: 10.1186/s12885-026-16692-x

Keywords: circulating tumor cells, CTC clusters, NNMT, metastasis, platelets, neutrophil extracellular traps, immune checkpoint blockade, cancer metabolism, epithelial-mesenchymal transition, single-cell RNA sequencing, TCGA pan-cancer, triple therapy

The research team, led by investigators at Brigham and Women’s Hospital and Harvard Medical School including M. Elizabeth Moss and Bruce Levy, applied a technique known as lipid mediator metabololipidomics, using liquid chromatography coupled with tandem mass spectrometry, to profile hundreds of fat-derived signaling molecules in blood plasma. Their subjects came from two cohorts totaling 106 participants with recent SARS-CoV-2 infection. Sixty-four went on to meet clinical criteria for Long COVID, defined by the National Academies as an infection-associated chronic condition persisting at least three months, while 42 fully recovered. By comparing lipid profiles between these groups at different time points, the researchers could ask whether the chemistry of inflammation resolution differs in people who develop the syndrome.

The logic behind the approach rests on a well-established but underappreciated branch of immunology. Essential polyunsaturated fatty acids such as arachidonic acid, docosahexaenoic acid, and eicosapentaenoic acid are not merely fuel; they are raw materials for an entire pharmacopeia of signaling molecules. Lipoxygenase enzymes convert these fats into specialized pro-resolving mediators, including lipoxins, resolvins, protectins, and maresins, which actively coordinate the return of tissues to homeostasis after injury or infection. In a self-limited inflammatory response, the body performs a metabolic class switch, pivoting from pro-inflammatory prostaglandins and leukotrienes to these pro-resolving mediators. If that switch fails, inflammation can smolder indefinitely.

The first major finding came from the acute phase. In samples drawn within 30 days of a positive test, participants who would later develop Long COVID showed significantly elevated levels of three products of the 12-lipoxygenase enzyme: 12-hydroxyeicosatetraenoic acid from arachidonic acid, 14-hydroxydocosahexaenoic acid from DHA, and 12-hydroxyeicosapentaenoic acid from EPA. This association held even after the researchers statistically controlled for the severity of the initial infection, gender, and self-reported race. A composite score aggregating all 12-lipoxygenase products was likewise a significant predictor of later Long COVID, as were aggregate measures of arachidonic acid and EPA metabolism. Notably, the pattern was not simply a byproduct of generalized platelet activation, since thromboxane products of platelet cyclooxygenase were not elevated.

The 12-lipoxygenase signal is intriguing because the enzyme is highly expressed in platelets and sits at the crossroads of clotting and inflammation. Acute SARS-CoV-2 infection is known to trigger endothelial inflammation, angiogenesis, platelet activation, and microthrombi, and the new data suggest that selective 12-lipoxygenase activation, which can occur through thrombin receptors, collagen signaling, or immune complexes independently of the cyclooxygenase pathway, may link these processes to the later development of persistent symptoms. The researchers also observed that reduced levels of interleukin-22 and of resolvin D1, a DHA-derived pro-resolving mediator, in the acute phase predicted Long COVID risk, hinting that a deficit in resolution chemistry may accompany the excess lipoxygenase activity.

After the first month, the picture shifted. In cross-sectional samples collected more than a month post-infection, the correlation structure of the lipidome itself had changed. In recovered participants, intermediates derived from the same parent fatty acid tended to rise and fall together, indicating that metabolism was organized around the available fats. In Long COVID participants, this within-family correlation was lost for the DHA and EPA families, while a strong signature of 5-lipoxygenase activation emerged across fatty acid families. The authors interpret this as an uncoupling of PUFA metabolism in Long COVID, in which enzyme activity, rather than substrate availability, drives the lipid profile, consistent with disrupted lipid mediator class switching.

Longitudinal sampling over the first year after infection sharpened the temporal picture. Levels of 15-HETE, an arachidonic acid product, remained significantly higher in Long COVID participants, while resolvin D1 was consistently lower; indeed, resolvin D1 was undetectable in 14.3 percent of Long COVID samples but in none of the recovered samples. Several metabolites, including 17-HDoHE, 14-HDoHE, and lipoxin A4, showed significant interactions with time, diverging between the groups in the three-to-nine-month window after infection. These trajectories suggest that lipoxygenase activity remains elevated for months in Long COVID even as production of key pro-resolving mediators stays depressed, a combination that could sustain defective resolution of inflammation.

The study also intersected with another leading hypothesis about Long COVID: persistence of viral proteins. Using ultra-sensitive single molecule array assays, the researchers detected SARS-CoV-2 spike protein in a subset of both Long COVID and recovered participants long after acute infection, and unsupervised clustering of the multidimensional data separated samples largely by the presence or absence of spike. Within Long COVID samples, plasma levels of 17-HDoHE correlated significantly with spike protein abundance, a relationship absent in recovered participants. When the team clustered Long COVID samples using lipid mediators alone, four distinct biochemical subtypes emerged, one enriched in 17-HDoHE and another almost entirely lacking resolvin D1, hinting that Long COVID may encompass several metabolically distinct endotypes rather than a single disease process.

The authors are careful to note limitations. The cohorts were modest in size, particularly the recovered group in the longitudinal arm, and clinical status was determined by chart review rather than validated survey instruments. Medication use, especially aspirin, which can suppress 12-lipoxygenase activity, and dietary intake of omega-3 fatty acids were not captured, and parent fatty acid levels were not quantified. Many bioactive mediators fell below detection limits in plasma, prompting the authors to call for serum-based analyses that could better distinguish deficient substrate from dysregulated enzymatic machinery.

Even so, the findings open concrete paths forward. Elevated 12-lipoxygenase products in the first month of infection could serve as an early biomarker identifying patients at risk of Long COVID before symptoms become chronic, and the results dovetail with an ongoing randomized controlled trial, ARACOV-02, testing whether supplementation with pro-resolving mediator precursors such as 17-HDoHE, 14-HDoHE, and 18-HEPE, combined with telerehabilitation, can improve outcomes in established disease. More broadly, the work reframes Long COVID as a disorder of failed inflammatory resolution, a concept that may ultimately connect viral persistence, platelet biology, and fat metabolism into a single mechanistic story, and offers researchers a biochemical handle on one of the pandemic’s most stubborn legacies.

Subject of Research: Lipoxygenase-catalyzed metabolism of essential polyunsaturated fatty acids in Long COVID

Article Title: Long COVID is associated with lipoxygenase-catalyzed metabolism of essential polyunsaturated fatty acids

Article References: Moss, M. E., Pons, S., Tavares, L. P., Tang, Y., Alter, G., Karlson, E., Baden, L., Walt, D. R., & Levy, B. D. (2026). Long COVID is associated with lipoxygenase-catalyzed metabolism of essential polyunsaturated fatty acids. iScience, 29(11), Article 117581. https://doi.org/10.1016/j.isci.2026.117581

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117581

Keywords: Long COVID, SARS-CoV-2, lipoxygenase, polyunsaturated fatty acids, specialized pro-resolving mediators, lipidomics, inflammation resolution, resolvin D1, platelets, spike protein, 12-HETE, iScience

The research team, led by Aneta Teległów of the University of Physical Culture in Krakow together with colleagues from Jagiellonian University Medical College and the University of Agriculture in Krakow, focused on hemorheology, the study of how easily blood flows through vessels. Blood is not a simple liquid like water; it is a suspension of red cells, white cells, and platelets in plasma, and its viscosity depends on hematocrit, plasma protein concentration, red cell deformability, and aggregation. When any of these properties shift, the heart must work harder to push blood through the microcirculation, and the risk of thrombosis can rise.

Previous work had suggested reasons for concern. Cold exposure triggers peripheral vasoconstriction, raises arterial pressure, and has been linked in older studies to increases in platelet counts, red cell counts, and plasma fibrinogen, a key clotting protein. Strenuous exercise itself is known to transiently raise blood viscosity through hemoconcentration and to activate platelets. The researchers wanted to know whether combining the two stresses, maximal exertion and severe cold, would produce an amplified hemorheological response that could help explain why cardiovascular events cluster during winter sports and snow shoveling.

Thirty healthy, non-smoking male students aged around twenty-two were recruited and randomly assigned to one of two groups. The experimental group performed an incremental endurance shuttle-run test inside a climate chamber held at −10 °C, while the control group ran the identical protocol outdoors at 18 °C. The test began at eight kilometers per hour and increased by half a kilometer per hour each minute, with participants running twenty-meter shuttles until exhaustion. Fasting blood samples were drawn from an antecubital vein before and immediately after the run, and the researchers measured whole blood and plasma viscosity, hematocrit, red cell deformability and aggregation, fibrinogen concentration, platelet count and activation markers, and white cell counts.

The results were striking for what they did not show. Both groups displayed the expected exercise-induced hemoconcentration: plasma volume fell, hematocrit and hemoglobin rose, and platelet numbers increased, consistent with the well-documented splenic release of stored platelets during intense effort. Yet the magnitude of these changes was essentially the same whether the men had sprinted in deep cold or in mild air. Fibrinogen concentrations did not rise in either group, and there was no significant difference between the cold-exposed and control groups in any of the measured clotting or rheological variables.

Plasma viscosity, often considered a sensitive marker of cardiovascular risk, was unchanged by the cold exposure itself. The authors note that this finding aligns with some earlier reports but contradicts others that described viscosity increases during cold exposure at rest. One possible explanation is that the participants wore insulating clothing during the cold trial, blunting the skin-level cold stimulus, and that the short duration of the exercise bout was insufficient to trigger the fluid shifts and inflammatory responses that longer exposures produce. The young age and excellent health of the volunteers may also have allowed their compensatory mechanisms, including rapid plasma volume regulation, to fully offset any cold-induced hemoconcentration.

The study’s authors are careful to frame the findings within their limits. The cohort consisted exclusively of young, healthy, recreationally active men, a group whose cardiovascular systems respond flexibly to combined stress. The results cannot be extrapolated to older adults, people with coronary artery disease, or people with hypertension, in whom cold-induced vasoconstriction and impaired adaptive responses are known to raise event risk. Indeed, epidemiological data consistently show that winter cardiovascular mortality spikes precisely in populations whose hemorheological and vascular reserve is compromised.

Nevertheless, the work carries a practical message for the growing number of people who exercise outdoors in winter. For healthy young individuals, a brief high-intensity session in temperatures around −10 °C, dressed appropriately, does not appear to push blood rheology into a prothrombotic state beyond what the exercise itself already causes. The platelet increase observed in both groups reflects a normal, transient physiological response to maximal exertion rather than a cold-specific hazard, and it resolves as plasma volume normalizes.

The researchers suggest that future studies should examine longer cold exposures, female participants, older adults, and clinical populations to map where the protective compensatory mechanisms begin to fail. They also propose measuring additional markers such as catecholamines and inflammatory cytokines to clarify the signaling pathways linking cold, exertion, and blood rheology. Until then, the message for winter runners and athletes is cautiously reassuring: the deep cold of a January morning is unlikely to turn a hard sprint into a clotting crisis for a healthy young body, though anyone with cardiovascular risk factors should still treat cold-weather exertion with respect.

Subject of Research: Effects of acute sprint exercise in cold versus thermoneutral conditions on blood hemorheology in young men

Article Title: Acute hemorheological responses to an incremental shuttle-run test at -10 °C versus 18 °C in young healthy men

Article References: Teległów, A., Rembiasz, K., Pobędza, J., Cebula, Ł., Dziechciowski, Z., Czerwiński, A., Leśniowski, J., Marchewka, J., & Mika, P. (2026). Acute hemorheological responses to an incremental shuttle-run test at -10 °C versus 18 °C in young healthy men. Frontiers in Physiology, 17, Article 1935076. https://doi.org/10.3389/fphys.2026.1935076

Image Credits: AI Generated

DOI: 10.3389/fphys.2026.1935076

Keywords: hemorheology, blood viscosity, cold exposure, exercise physiology, platelets, fibrinogen, cardiovascular risk, shuttle-run test, plasma volume, winter sports, Acute, hemorheological

The study, published in the journal iScience, draws on the Chinese Multi-provincial Cohort Study-Proteomics Project, a community-based prospective investigation rooted in a population cohort initiated in 1992. For the proteomics arm, 2,621 individuals from the Beijing area with available blood samples were enrolled, and after excluding 71 people who had already experienced cardiovascular events before the 2002 baseline examination, 2,550 participants entered the final analysis. Their average age at baseline was 57.5 years, and 44 percent were men. Crucially, the researchers did not rely on a single blood draw: up to four repeated PDGFD measurements were available per participant across visits in 2002, 2007, 2012, and 2020 through 2023, yielding 5,308 protein measurements in total.

Measuring PDGFD required a high-throughput proteomic platform. The team used the SomaScan 11K assay, in which modified single-stranded DNA molecules called SOMAmers bind to target proteins in small aliquots of serum and are quantified on a DNA microarray, with concentrations reported in relative fluorescence units. Quality control figures pointed to solid reproducibility: the median intra-assay coefficient of variation was 3.67 percent in one subcohort and 3.42 percent in the other, while the inter-assay coefficient of variation between batches was 6.87 percent, considered acceptable for this type of measurement. Participants were followed for fatal and non-fatal acute coronary events and ischemic stroke until the end of 2023, with events adjudicated by physicians using the World Health Organization MONICA protocol and supplemented by linkage to national vital registration and hospital information systems.

Over a median follow-up of 20.3 years, 463 participants, or 18.2 percent of the cohort, developed atherosclerotic cardiovascular disease, while 264 participants experienced competing events such as hemorrhagic stroke or non-cardiovascular death. The central finding was consistent across every statistical model the researchers applied. Each standard deviation increase in circulating PDGFD was associated with a 19 percent higher risk of atherosclerotic cardiovascular disease, with a hazard ratio of 1.19. When the analysis was adjusted sequentially for medication use, for the full set of risk factors recommended by the 2020 Chinese Society of Cardiology guidelines for primary prevention, and even for a polygenic risk score capturing inherited cardiovascular susceptibility, the association did not budge, hovering between hazard ratios of 1.22 and 1.24, all statistically significant.

The robustness of the signal was tested from multiple angles. Accounting for competing risks, a statistical necessity when people die of other causes before ever developing heart disease, softened the estimate to a hazard ratio of 1.14 but left it significant. The association held when the researchers used only baseline PDGFD levels, when they used lagged measurements deliberately excluding the blood draw closest to a cardiovascular event to guard against reverse causation, and when they removed anyone who developed disease within the first five years of follow-up, a maneuver designed to weed out pre-existing, undiagnosed atherosclerosis. Only the analysis based on averaged PDGFD levels failed to reach statistical significance, though its effect estimate remained directionally consistent, likely because fewer participants and fewer events were available in that restricted sample.

What elevates the study beyond a conventional association analysis is its use of the target trial emulation framework, a technique that borrows the logic of a randomized controlled trial and applies it to observational data. Before emulating any intervention, the researchers verified a key biological premise: genetic variants associated with serum PDGFD levels mapped to the PDGFD locus itself and shared a consistent association signal, indicating that circulating PDGFD is predominantly regulated by cis-acting variation at its own gene region rather than by distant pleiotropic pathways. That genetic evidence, they argue, justifies treating hypothetical PDGFD-lowering interventions as genuine mimics of a therapeutic effect rather than statistical artifacts.

The emulation itself was technically ambitious. Using targeted maximum likelihood estimation, or TMLE, with a Super Learner algorithm combining generalized linear models, intercept-only models, and random survival forests, the team cloned the cohort into hypothetical treatment arms in which circulating PDGFD was reduced by sustained percentages ranging from 10 to 90 percent. Under the natural course of no intervention, the estimated twenty-year cumulative risk of atherosclerotic cardiovascular disease was 19.0 percent. Lowering PDGFD by 40 to 50 percent pushed that risk down to between 16.8 and 14.8 percent, an absolute risk reduction of 2.3 to 4.4 percentage points, a benefit statistically comparable to the treat-to-target LDL cholesterol lowering strategy used as a positive control, which achieved an absolute risk reduction of 2.8 percentage points. A parallel analysis using the parametric g-formula, a more conservative modeling approach, produced smaller estimates but the same dose-response pattern, with reductions ranging from 0.6 percentage points for a 10 percent PDGFD cut to 3.6 percentage points for a 90 percent cut.

The biology behind these numbers fits a coherent picture. PDGFD is a member of the platelet-derived growth factor family, and previous genetic studies had already flagged the PDGFD gene as perhaps the only growth factor pathway gene associated with coronary artery disease risk. Experimental work has shown that PDGFD promotes the recruitment of immune cells and the migration and proliferation of vascular smooth muscle cells, drives extracellular matrix deposition and vascular structural remodeling, and participates in the platelet-driven inflammatory cascade that creates the pro-inflammatory microenvironment in which atherosclerotic plaques take root. Elevated PDGFD expression has been observed in resident vascular cells and infiltrating inflammatory cells within human atherosclerotic lesions. Platelets, once viewed purely as clotting agents, are now understood to accelerate atherosclerosis by amplifying local inflammation and promoting vascular wall remodeling through crosstalk between endothelial cells and immune cells, and PDGFD appears to sit upstream of much of that signaling.

The subgroup analyses added a layer of personalization that could shape future trials. The estimated benefits of hypothetical PDGFD lowering were largest among people aged 60 and older, men, smokers, individuals with a body mass index of 24 or higher, and those classified as high risk by the ten-year cardiovascular prediction model, where absolute risk changes reached as much as 15.1 percentage points. The pattern echoes a Swedish cohort in which PDGFD gene polymorphism was linked to increased cardiovascular mortality specifically in elderly men, and preclinical findings that obesity upregulates adipose PDGFD and promotes its proteolytic activation, potentially explaining why the obesity subgroup showed outsized estimated benefits. Intriguingly, non-smokers displayed a clear dose-response relationship between the degree of PDGFD lowering and predicted risk reduction, while smokers showed a stronger overall effect but no dose-response gradient, possibly because smoking’s own vascular damage overwhelms the incremental gains from progressively lowering the protein.

The authors are careful to frame the findings as population-level evidence rather than proof of clinical efficacy. Residual confounding by factors such as socioeconomic status cannot be excluded, the causal assumptions underlying the emulation may not be fully satisfied, and the extreme intervention scenarios were explored to map dose-response patterns rather than to represent achievable therapies. The cohort’s geographic concentration in Beijing and its lower smoking prevalence than national estimates may limit generalizability, and the study did not evaluate other PDGF family members such as PDGFA, PDGFB, and PDGFC, leaving the specificity of PDGFD’s role unresolved. Still, the triangulation of longitudinal associations, genetic support, dual causal inference methods, and a positive control intervention gives the result unusual weight. With considerable residual cardiovascular risk persisting despite modern lipid, glucose, and blood pressure therapies, PDGFD now stands as a genuinely modifiable candidate, awaiting the randomized trials that will determine whether lowering it in the clinic can deliver the benefits the simulations promise.

Subject of Research: The association between circulating platelet-derived growth factor D levels and atherosclerotic cardiovascular disease risk

Article Title: Potential role of platelet-derived growth factor D in atherosclerotic cardiovascular disease risk

Article References: Deng, X., Yang, Z., Jia, P., Liu, Y., Zhang, Y., Deng, Q., Yang, N., Hao, Y., Han, L., Sun, J., Lu, W., Sun, X., Qi, Y., & Liu, J. (2026). Potential role of platelet-derived growth factor D in atherosclerotic cardiovascular disease risk. iScience, 29(11), Article 117864. https://doi.org/10.1016/j.isci.2026.117864

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117864

Keywords: PDGFD, atherosclerotic cardiovascular disease, platelets, target trial emulation, proteomics, SomaScan, coronary artery disease, LDL cholesterol, causal inference, polygenic risk score, vascular smooth muscle cells, inflammation

The research team, led by Yao Zhang, Yue Cheng, Han Ni Soe and Zhipeng Xu, used molecular dynamics simulations to interrogate the mechanical behavior of GPVI and CLEC-2 assemblies with an unusually direct approach. Rather than relying on a single structural model, the investigators deliberately compared three distinct extracellular architectures. The first was a reconstructed GPVI dimer based on the Protein Data Bank entry 2GI7, a classic representation of how two GPVI molecules pair up. The second was a domain-swapped GPVI assembly derived from the more recent structure 7NMU, in which parts of each protein molecule exchange positions with their partner in a way that fundamentally entangles the pair. The third was a crystallographic contact observed between CLEC-2 molecules. By subjecting all three to the same pulling protocol and the same constant-force conditions, the researchers could isolate the effect of architecture alone, free from confounding differences in simulation technique.

The central experiment mimicked, in silico, what happens when flowing blood tugs on receptor pairs that anchor platelets to one another. In the early phase of forced separation, defined as the first five nanometers of imposed distance between the receptors, the reconstructed GPVI dimer proved noticeably easier to pull apart than either CLEC-2 or the domain-swapped GPVI assembly. Both the peak force required and the total mechanical work expended were lower for the conventional GPVI dimer. In practical terms, this means the standard model of GPVI association, the one most often depicted in textbooks, is the weakest link among the three architectures when it comes to resisting the initial stages of mechanical disruption.

The differences became even more dramatic when the team switched from a displacement-driven pulling scheme to constant-force loading, a mode that more closely resembles the steady, sustained stresses experienced by receptor clusters in a growing thrombus. Applying forces ranging from 400 to 600 piconewtons, the researchers measured how long each assembly took to reach a defined extension endpoint. The reconstructed GPVI dimer arrived at that endpoint markedly earlier than the domain-swapped assembly, and under several loading conditions the passage times differed by more than an order of magnitude. An order of magnitude is not a subtle refinement; it is the difference between a receptor association that fails almost immediately under load and one that persists long enough to contribute meaningfully to the mechanical integrity of a platelet plug.

When the imposed separation was extended to approximately ten nanometers, the fate of the two GPVI architectures diverged completely. In the reconstructed dimer, every interreceptor heavy-atom contact vanished, meaning the two protein molecules lost all direct physical association with one another. Crucially, however, the simulation showed that local structural features survived the ordeal: peptide backbones remained connected and disulfide bridges, the covalent staples that hold each protein’s own fold together, stayed intact. In other words, the receptors themselves were not destroyed by the force; they simply let go of each other. This distinction matters, because it suggests that mechanical failure under these conditions is a dissociation event at the interface rather than a catastrophic unfolding of individual receptor domains.

The domain-swapped GPVI preparation told an entirely different story. Because segments of each molecule are woven into the fold of its partner, the assembly resists separation across a much larger portion of the pulling pathway. Force applied to one end is transmitted through an interlocking network of exchanged structural elements, so the pair does not surrender its contact until the receptors have been dragged much further apart. The researchers describe this quality as substantially greater mechanical persistence, and their simulations show it is an emergent property of the topology of the swap rather than of any single strong bond. Domain swapping, long appreciated by structural biologists as a curiosity of protein crystallography, thus acquires a new mechanical identity as a built-in reinforcement mechanism.

Why should this matter beyond the simulation box? The authors argue that uncertainty in the true architecture of GPVI on the platelet surface can translate into large differences in force transmission and persistence under load. Experimental structures of GPVI assemblies have been obtained under different conditions and capture different oligomeric states, and the field has not settled on which arrangement dominates on living platelets. If the conventional dimer is the prevalent form, receptor clusters may be relatively labile, reorganizing readily as the thrombus matures. If domain-swapped assemblies are common, the same clusters could be far more mechanically stubborn, holding platelets together through pulses of arterial pressure. The new results show that these possibilities are not merely cosmetic differences in molecular bookkeeping; they are mechanically equivalent to choosing between a fragile link and a reinforced one.

The study also carries a broader methodological lesson for the growing field of mechanobiology, which seeks to understand how cells sense and respond to physical forces. Receptors are routinely studied through their binding affinities and signaling outputs, quantities measured under near-equilibrium conditions that say little about behavior under sustained load. The GPVI-CLEC-2 comparison demonstrates that two receptors serving related physiological roles can occupy opposite ends of the mechanical persistence spectrum, and that the same receptor can occupy different points on that spectrum depending on its extracellular arrangement. Force, in this view, is not a secondary consideration bolted onto biochemistry but a dimension of receptor function in its own right, one that structural uncertainty can swing wildly.

Looking ahead, the findings open several avenues for experimental and translational work. If architecture-dependent persistence influences the stability of extracellular receptor associations during thrombus formation, as the authors propose, then the mechanical lifetime of receptor clusters under load becomes a potential target for antithrombotic strategies. A molecule that destabilizes force-resistant GPVI assemblies, or conversely one that stabilizes them in bleeding disorders, would exploit a lever that current drugs do not touch. Testing these ideas will require bridging the gap between simulated pulling forces and the complex, dynamic environment of a living vessel, where receptors cluster, diffuse and encounter their ligands in real time. For now, the study delivers a clear conceptual message: the shape of a receptor assembly outside the cell is not a passive detail, but a determinant of how long that assembly endures when the blood demands everything of it. The clots that save lives, it turns out, may owe part of their strength to molecular architecture that scientists are only beginning to map.

Subject of Research: Mechanical persistence of platelet GPVI and CLEC-2 receptor extracellular assemblies under force

Article Title: Distinct extracellular architectures shape mechanical persistence in GPVI and CLEC-2 receptor assemblies

Article References: Zhang, Y., Cheng, Y., Soe, H. N., & Xu, Z. (2026). Distinct extracellular architectures shape mechanical persistence in GPVI and CLEC-2 receptor assemblies. PLOS Computational Biology, 22(10), e1014884. https://doi.org/10.1371/journal.pcbi.1014884

Image Credits: AI Generated

DOI: 10.1371/journal.pcbi.1014884

Keywords: platelets, GPVI, CLEC-2, molecular dynamics, mechanobiology, thrombus formation, receptor clustering, domain swapping, constant-force simulation, blood clotting, protein mechanics, PLOS Computational Biology

The team’s first clue came from combination experiments in living animals. When the researchers paired anti-platelet agents with an antibody that blocks PD-L1—a cornerstone immune checkpoint target exploited by tumors to disarm T cells—they observed a synergistic anti-tumor effect that neither treatment achieved alone. That synergy hinted that platelets were actively contributing to the tumor’s defenses rather than merely bystanders in the tumor microenvironment. When the investigators looked more closely at tumors, they found that activated platelets were adhering directly to tumor-infiltrating CD8-positive T cells. Critically, when platelet activity was suppressed alongside PD-L1 blockade, this adhesion was reduced, and the T cells showed enhanced activation. In other words, stripping platelets away from the immune cells appeared to unleash at least some of the anti-tumor firepower that checkpoint inhibitors are designed to restore.

To determine whether this was a direct cause-and-effect relationship rather than an indirect consequence of the tumor environment, the team built a controlled laboratory system that isolated the players. They used cytotoxic T lymphocytes derived from induced pluripotent stem cells—a line known as CTL3-3—engineered to specifically recognize the WT1 antigen, a protein expressed on many cancer cells and a well-established tumor-associated target. When intact platelets were added to the co-culture of these antigen-specific killer cells and cancer cells, the platelets suppressed the T cells’ cytotoxic activity. The suppression was unmistakable: T cells that would otherwise have efficiently killed their WT1-expressing targets became measurably less lethal in the presence of platelets.

One obvious question was whether platelets were exerting this effect through soluble factors—chemical signals released into the surrounding fluid—rather than through physical contact. To test this, the researchers collected supernatants, the liquid fractions from cultures of activated platelets, and applied them to the T cells. These supernatants did partially suppress cytotoxicity, suggesting that platelet-derived soluble mediators contribute something to the inhibitory effect. But the suppression achieved by soluble factors alone was consistently weaker than the suppression caused by intact platelets. That difference was telling. It implied that the dominant mechanism required the platelets themselves to be physically present, in contact with the T cells, rather than merely whispering chemical instructions from a distance.

Flow cytometry analysis then revealed the nature of that physical contact. Activated platelets express P-selectin, also known as CD62P, a transmembrane adhesion molecule stored in platelet granules and rapidly displayed on the cell surface when platelets are activated. The analysis showed that these P-selectin-bearing platelets directly interact with the CTL3-3 T cells. The team confirmed the interaction with two independent imaging approaches: immunofluorescence staining, which visualized the molecular partners at the interface between the cells, and electron microscopy, which captured the ultrastructural detail of platelets clinging to T cell surfaces. Together, these techniques established that the platelet-T cell adhesion was not an artifact of the assay but a reproducible, physically verifiable phenomenon.

The molecular identity of the T cell-side partner proved to be PSGL-1, the canonical ligand for P-selectin. PSGL-1 is a glycoprotein best known for its role in guiding leukocytes through the bloodstream and into tissues during inflammation, where it engages selectins on vascular endothelial cells. The researchers used neutralizing antibodies to block either P-selectin on the platelets or PSGL-1 on the T cells. Either intervention inhibited the adhesion between the two cell types and, crucially, restored the cytotoxic activity of the T cells in the presence of platelets. This bidirectional blockade experiment is the strongest evidence in the study that the P-selectin–PSGL-1 axis is the functional conduit through which platelets suppress tumor killing. When the handshake is interrupted, the T cells recover their ability to destroy their targets.

Equally important is what the platelets did not do. The researchers found that the interaction suppressed the antigen-specific killing activity of the T cells without affecting their proliferation. The T cells continued to divide and expand normally; they simply became less effective executioners while in contact with platelets. This distinction matters for therapeutic thinking. A mechanism that throttles the cytotoxic function of T cells while leaving their numbers intact suggests a reversible, contact-dependent form of immune regulation—one that could potentially be switched off pharmacologically without causing the broader immune dysfunction that might accompany agents that deplete or globally suppress T cells. It also distinguishes this mechanism from classical checkpoint pathways such as PD-1/PD-L1, which alter T cell activation states through signaling rather than through physical sequestration.

The broader context of this work sits at the intersection of hematology and tumor immunology, a crossroads that has attracted growing attention in recent years. Platelets are known to interact with cancer cells in ways that facilitate tumor progression and enhance malignancy—they shield circulating tumor cells from immune surveillance in the bloodstream, promote metastatic seeding, and release a cargo of growth factors and immunomodulatory molecules. Cancer patients frequently exhibit platelet activation and thrombocytosis, and high platelet counts have been associated with poorer prognosis across multiple tumor types. What has remained murky is the direct effect of platelets on the anti-tumor activity of CD8-positive T cells, the population that immunotherapies from checkpoint inhibitors to engineered T cell therapies ultimately depend upon. By demonstrating a direct, receptor-defined inhibitory interaction, this study fills a conceptual gap and provides a mechanistic explanation for why anti-platelet strategies might synergize with immunotherapy.

The therapeutic implications are tantalizing but must be tempered with caution. The combination of anti-platelet agents and PD-L1 blockade produced synergistic anti-tumor effects in the preclinical setting, and the mechanistic work identifies P-selectin and PSGL-1 as druggable nodes—both are accessible to neutralizing antibodies, and agents targeting the selectin pathway already exist in other clinical contexts. Yet translating these findings into patients will require careful navigation of platelet biology’s essential role in hemostasis. Systemic platelet inhibition carries bleeding risks, and any strategy would need to selectively disrupt the platelet-T cell interaction without compromising clotting. Blocking the P-selectin–PSGL-1 axis specifically, rather than platelet function broadly, may offer a narrower therapeutic window, but this remains to be tested in clinical studies. The current work was conducted in animal models and in vitro systems, and tumor immunology is notorious for promising mechanisms that fail to survive translation.

Nevertheless, the study reframes platelets from passive clotting agents into active participants in the immune battlefield of cancer, and it does so with unusual mechanistic precision—identifying the cell types, the contact dependence, the receptor-ligand pair, and the functional consequence, all within a single coherent experimental arc. For a field racing to explain why immunotherapies work spectacularly in some patients and fail in others, the discovery that activated platelets can handcuff CD8-positive T cells through P-selectin binding offers a new variable to measure, a new biomarker to explore, and a new combination to test. If subsequent studies confirm that the same interaction operates in human tumors and that disrupting it safely enhances checkpoint inhibitor responses, the humble platelet—long celebrated for saving lives one clot at a time—may find itself recast as an accomplice of cancer, and its inhibition as an unexpected weapon in the immunotherapy arsenal.

Subject of Research: The inhibition of CD8-positive T cell anti-tumor activity by platelet P-selectin binding to PSGL-1

Article Title: P-Selectin on activated platelets inhibits the anti-tumor activity of CD8+ T cells through PSGL-1 binding

Article References: Nishiguchi, S., Yokomura, M., Gomibuchi, Y., Nagano, S., Yasunaga, T., Hirohashi, Y., Kawamoto, H., Takagi, S., & Katayama, R. (2026). P-Selectin on activated platelets inhibits the anti-tumor activity of CD8+ T cells through PSGL-1 binding. Cancer Immunology, Immunotherapy. https://doi.org/10.1007/s00262-026-04578-7

Image Credits: AI Generated

DOI: 10.1007/s00262-026-04578-7

Keywords: platelets, P-selectin, PSGL-1, CD8-positive T cells, cancer immunotherapy, PD-L1 blockade, WT1 antigen, cytotoxic T lymphocytes, tumor microenvironment, immune checkpoint inhibitors, iPSC-derived T cells, tumor immunology

The biological problem the index addresses is the defining paradox of Kawasaki disease. The illness presents as a feverish, inflammatory condition of childhood, with mucocutaneous signs such as cracked lips, conjunctival injection, rash and swollen lymph nodes, yet its most consequential damage is vascular. In the acute phase, a diffuse inflammatory process targets the medium-sized arteries, and the coronary arteries are particularly vulnerable. When inflammation weakens the arterial wall, the vessel can dilate into an aneurysm, a lesion that may regress over time or persist for life, setting the stage for stenosis, thrombosis and ischemic heart disease decades later. Intravenous immunoglobulin, given within the first ten days of illness, dramatically reduces this risk, but a meaningful fraction of children still develop coronary abnormalities, and some fail to respond to first-line therapy at all. Identifying those children early, ideally at the first encounter, is the goal of every risk-stratification effort in the field.

Current practice relies on a patchwork of tools. The American Heart Association, in its 2024 scientific statement on the diagnosis and management of Kawasaki disease, emphasizes echocardiographic surveillance and clinical judgment, and standardized Z-score formulas are used to express a child’s coronary artery dimensions relative to body surface area, allowing clinicians to distinguish dilation from aneurysm and to track progression. Predictive models have also been developed, including a widely discussed risk model validated in a North American population by Son and colleagues, which combines demographic and laboratory variables to estimate aneurysm probability before treatment begins. Saad and colleagues themselves have contributed to this effort, publishing a predictive modeling approach for early risk stratification in Pediatric Research earlier in 2026. Yet each tool has limitations: models built in one population may not transfer to another, Z-scores depend on accurate imaging and appropriate formula selection, and no single laboratory value has proven sufficiently discriminating on its own.

Into this gap steps the Aggregate Index of Systemic Inflammation. The AISI belongs to a family of composite inflammatory cell indexes that have attracted growing attention across medicine because they can be derived at no additional cost from parameters already reported on every differential blood count. In its standard formulation, the index multiplies the platelet count, the neutrophil count and the monocyte count, and divides by the lymphocyte count. Each component captures a facet of the inflammatory response: neutrophils and monocytes are the cellular vanguard of innate inflammation, platelets are acute-phase reactants whose numbers climb as interleukin-6 drives thrombopoiesis, and lymphocytes tend to fall under the suppressive weight of stress hormones and inflammatory cytokines. A high AISI therefore reflects a convergence of myeloid activation, thrombocytosis and relative lymphopenia, a pattern that in many diseases tracks the intensity of systemic inflammation more faithfully than any single cell line.

The appeal of such an index in Kawasaki disease is grounded in the disease’s own biology. Recent reviews, including a 2024 analysis in Nature Reviews Rheumatology by Noval Rivas and colleagues, have highlighted platelets not as passive bystanders but as active mediators of vascular inflammation in the illness. Platelets interact directly with activated endothelium, release pro-inflammatory and pro-thrombotic mediators, and contribute to the remodeling of the vessel wall that underlies aneurysm formation. Neutrophils, meanwhile, have been implicated in endothelial injury through the release of neutrophil extracellular traps, and monocytes infiltrate the inflamed arterial wall. The idea that a product of these very cell counts might correlate with coronary outcomes is therefore not a statistical accident in search of a mechanism; it is a hypothesis with a plausible pathophysiological backbone. The same logic has propelled AISI research in adult cardiovascular medicine, where a 2024 retrospective study in the Journal of Inflammation Research reported associations between the index and clinical outcomes in patients with acute myocardial infarction.

The immediate trigger for the commentary is a study by Liu, Peng and Zhou, published online in Pediatric Research in September 2026, which examined the association between the AISI and coronary artery aneurysm in patients with Kawasaki disease. That investigation reported that a higher AISI was associated with the presence of coronary artery aneurysm, suggesting that the index could help identify children who require closer coronary surveillance. Saad and his co-authors, writing from institutions spanning Egypt, Jordan, Russia, Saudi Arabia, the United Kingdom and Pakistan, use their commentary to appraise what this finding means for practice. Their assessment, summarized in the article’s impact statements, is measured: the AISI may serve as an additional inflammatory marker for identifying children with Kawasaki disease who need closer coronary monitoring, and AISI-based risk stratification may ultimately contribute to personalized approaches in disease management.

The commentary’s caution is as instructive as its enthusiasm. The authors state plainly that current evidence supports further prospective validation before the AISI can be included in treatment decision pathways. This is a crucial distinction in pediatric cardiology, where treatment intensification, such as the addition of corticosteroids or other adjunctive agents for high-risk children, carries its own risks and where misclassifying a low-risk child as high-risk can expose an infant to unnecessary immunosuppression. A retrospective association, however biologically plausible, does not establish that the index adds predictive information beyond what is already captured by age, sex, days of fever at diagnosis, baseline laboratory values and serial echocardiography. Establishing incremental value requires prospective cohorts, ideally across multiple populations, in which the AISI is measured at diagnosis and tested against coronary outcomes in models that already include established predictors.

Several technical considerations will shape that validation. The AISI’s components are not static: platelet counts in Kawasaki disease typically rise in the second week of illness, so the timing of the blood draw relative to fever onset materially changes the value. Thrombocytosis may be absent in the first days, precisely when treatment decisions must be made, which raises the question of whether an early AISI retains discriminative power. Related composite indexes built from the same count, such as ratios pairing platelets, neutrophils or monocytes with lymphocytes, have been studied in other inflammatory and surgical settings, and head-to-head comparisons would clarify whether the full four-component product offers genuine added sensitivity. Albumin, a negative acute-phase reactant that has been linked to coronary lesion progression in retrospective cohorts, and other conventional markers such as C-reactive protein, provide further benchmarks against which any new index must prove itself. Standardization of cutoffs, which vary across studies and populations, is another unresolved hurdle.

The broader significance of the commentary lies in its vision of low-cost, widely accessible risk stratification. The complete blood count is among the cheapest and most universally available tests in medicine, including in the low- and middle-income settings where Kawasaki disease is often diagnosed late and where advanced imaging may be scarce. An index that extracts additional prognostic information from data already in hand, without new reagents, equipment or expense, aligns squarely with the needs of global pediatric practice. If prospective studies confirm that the AISI meaningfully refines aneurysm risk prediction, it could be incorporated into the early triage of children at diagnosis, flagging those who warrant intensified anti-inflammatory therapy, more frequent echocardiography or referral to specialized centers. Conversely, if validation fails, the episode will still have sharpened the field’s understanding of how cellular inflammation relates to coronary pathology.

For now, the message from Saad and colleagues is one of disciplined optimism. The Aggregate Index of Systemic Inflammation is not a new test but a new lens on an old one, and its candidacy in Kawasaki disease rests on a coherent mechanistic rationale and an emerging body of evidence rather than on settled proof. The authors declare no competing interests and received no external funding for the commentary, and they frame the index explicitly as a potential complement to, not a substitute for, established clinical and echocardiographic assessment. Children with Kawasaki disease will continue to be managed according to current guidelines, with intravenous immunoglobulin, aspirin and serial coronary imaging. But the commentary signals that the next chapter of aneurysm risk prediction may be written not with expensive biomarkers or novel imaging, but with a few numbers multiplied together from a blood count that every febrile child already receives.

Subject of Research: Evaluation of the Aggregate Index of Systemic Inflammation as a marker of coronary aneurysm risk in Kawasaki disease

Article Title: Inflammatory burden and coronary aneurysm risk in Kawasaki disease: appraising the Aggregate Index of Systemic Inflammation

Article References: Saad, K., Aly, S. E., Zeid, S. S. K., Ahmad, A. R., Elfarargy, M. S., Elkossi, M., Mumtaz, M. H., & Temsah, M.-H. (2026). Inflammatory burden and coronary aneurysm risk in Kawasaki disease: appraising the Aggregate Index of Systemic Inflammation. Pediatric Research. https://doi.org/10.1038/s41390-026-05590-4

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05590-4

Keywords: Kawasaki disease, coronary artery aneurysm, Aggregate Index of Systemic Inflammation, AISI, inflammation, pediatric cardiology, risk stratification, complete blood count, platelets, echocardiography, intravenous immunoglobulin, biomarkers

Late-onset sepsis, typically defined as a serious bloodstream or systemic infection occurring more than 72 hours after birth, remains one of the most feared complications in neonatal intensive care. Unlike early-onset disease, which is usually acquired around the time of delivery, late-onset sepsis emerges in infants who are already hospitalized, often extremely premature and already dependent on life-sustaining technology. Because blood cultures in newborns can be negative even during genuine infection, clinicians frequently rely on a constellation of indirect clues, and thrombocytopenia, a platelet count below 150 × 10⁹ per liter, has long been treated as one of the more ominous among them. Platelets fall during sepsis for several reasons, including consumption in microvascular clotting, impaired production in the bone marrow, and immune-mediated destruction, which is why a dropping count is often read as a signal that infection is severe or worsening.

The problem, as the study’s authors point out, is that platelet counts in the neonatal intensive care unit are rarely a clean signal. Premature infants naturally have lower platelet counts than term babies, and many infants in the NICU are thrombocytopenic for reasons that have nothing to do with sepsis, including neonatal alloimmune thrombocytopenia, drug effects, or the generalized illness of extreme prematurity itself. A low platelet count measured shortly before a suspected sepsis episode may therefore reflect the infant’s baseline fragility rather than the virulence of the infection. If that is the case, then associating thrombocytopenia with poor outcomes tells us less about sepsis severity than about which infants were already the sickest, and any predictive model built on the marker risks simply rediscovering prematurity and baseline respiratory dependence under a different name.

To disentangle this, the researchers constructed a cohort from the neonatal subset of MIMIC-III, a large, de-identified intensive care database developed at Beth Israel Deaconess Medical Center and the Massachusetts Institute of Technology. For each infant, they included the first presumed late-onset sepsis episode that was derived from antibiotic administration linked to blood-specimen collection and occurred more than 72 hours after birth. Baseline thrombocytopenia was defined as a platelet count below 150 × 10⁹ per liter recorded within six hours before the onset of the episode. The endpoint was deliberately designed to capture respiratory burden rather than death alone: an infant met the endpoint if he or she either died within 28 days or remained on mechanical ventilation 48 hours after sepsis onset. This composite reflects the practical reality that in the NICU, prolonged ventilator dependence is one of the most consequential downstream costs of a severe infectious episode.

The cohort ultimately comprised 397 infants, of whom 174, or 43.8 percent, met the composite endpoint. The composition of that endpoint is itself revealing: 172 infants had persistent mechanical ventilation at 48 hours, while only 8 died within 28 days. In other words, the endpoint was overwhelmingly dominated by ventilation status rather than mortality, a fact that would shape every subsequent interpretation. Platelet counts were available for 328 of the infants, and only 28 of those were thrombocytopenic at baseline, a small subgroup that would constrain the statistical precision of every estimate involving the exposure of interest.

The primary analysis used complete-case logistic regression, adjusting for baseline covariates, and produced an adjusted odds ratio of 1.34 for the association between thrombocytopenia and the endpoint, with a 95 percent confidence interval spanning 0.40 to 5.09. That interval is wide enough to include both a substantial protective effect and a substantial harmful one, which in statistical terms means the association was imprecise rather than demonstrably null. The researchers were careful in their language: they did not conclude that platelets are irrelevant, only that this dataset could not yield a precise independent estimate of their contribution. In a field where small, imprecise studies are often overinterpreted in either direction, that restraint is notable.

Far more striking was what happened when the team examined ventilation at the time of sepsis onset. In a contextual sensitivity model that included whether the infant was already being mechanically ventilated when the episode began, baseline ventilation carried an adjusted odds ratio of 30.19, with a 95 percent confidence interval of 13.48 to 73.06, while the platelet estimate barely moved, sitting at an adjusted odds ratio of 1.17 with a confidence interval of 0.27 to 5.49. An odds ratio of that magnitude for baseline ventilation indicates that the composite endpoint was, to a large extent, measuring the infant’s pre-existing respiratory status rather than a new deterioration caused by sepsis. An infant already on a ventilator when infection is suspected is very likely still to be on one 48 hours later, regardless of how the infection evolves, which means the endpoint largely re-encodes baseline illness severity.

Recognizing this, the investigators prespecified a subgroup analysis restricted to infants who were not ventilated at the onset of the episode, a population in which the endpoint would more plausibly reflect new respiratory deterioration attributable to the septic event. This subgroup offered the clearest clinical contrast, but it was also underpowered: 183 infants contributed only 21 endpoint events, yielding an adjusted odds ratio of 1.42 for thrombocytopenia with a confidence interval of 0.17 to 8.32. Once again, the estimate was too imprecise to support any firm conclusion. The authors also conducted a supplementary variable-availability assessment using the paediatric intensive care database from the Children’s Hospital of Zhejiang University School of Medicine, but they explicitly note that this supported only an assessment of variable availability, not a replication of the endpoint analysis, underscoring how difficult it remains to validate such composite outcomes across different data environments.

The methodological honesty of the paper extends to its supplementary materials, which include robustness and contextual ventilation analyses, continuous platelet modeling, diagnostics for maturity variables, a bias-reduced birth-weight sensitivity analysis, and a fully reproducible analytic code archive for cohort construction. The team also validated the recovery of gestational age from the database, an important step given how much of neonatal risk stratification depends on accurate maturity assessment. Model performance was assessed with standard diagnostics, including the Akaike information criterion and the area under the receiver operating characteristic curve, and observed versus predicted endpoint risk was examined by decile. None of these checks rescued a precise platelet signal, but they collectively demonstrate the kind of transparency that exploratory database studies need if their findings are to be interpreted responsibly.

The practical takeaway for clinicians and researchers is twofold. First, in a historical MIMIC-III NICU cohort, baseline thrombocytopenia did not yield a precise independent association with a 48-hour respiratory-support burden endpoint in presumed late-onset sepsis, and the endpoint itself was driven mainly by persistent baseline ventilation, with the thrombocytopenic subgroup too small to support confident inference. Second, and perhaps more importantly, the study illustrates how composite endpoints built around ventilation status can be dominated by pre-existing respiratory dependence, potentially masking or distorting the effects of the exposures they are meant to illuminate. The authors conclude that these findings cannot exclude clinically important platelet associations, and they call for larger, contemporary cohorts using endpoints such as respiratory escalation or ventilator-free days, which are less entangled with baseline ventilator status. Until such studies are available, a low platelet count in a newborn with suspected late-onset sepsis should prompt careful attention, but it should not be treated as a stand-alone verdict on how the next critical 48 hours will unfold.

Subject of Research: Baseline thrombocytopenia as a predictor of respiratory-support burden in presumed neonatal late-onset sepsis

Article Title: Baseline thrombocytopenia and 48-hour respiratory-support burden in presumed neonatal late-onset sepsis: an exploratory MIMIC-III NICU cohort study

Article References: Yu, X., Zheng, Z., Gu, W., & Wei, Z. (2026). Baseline thrombocytopenia and 48-hour respiratory-support burden in presumed neonatal late-onset sepsis: an exploratory MIMIC-III NICU cohort study. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07738-x

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07738-x

Keywords: neonatal sepsis, late-onset sepsis, thrombocytopenia, platelets, NICU, mechanical ventilation, MIMIC-III, retrospective cohort study, neonatology, respiratory support, BMC Pediatrics, clinical prediction

The stakes are higher than the word platelet might suggest. As people age, their platelets become hyperreactive, aggregating more readily and contributing to the elevated risk of heart attacks and strokes in older adults. Megakaryocytes sit at the origin of that problem. These enormous cells, which can contain up to 64 copies of the genome, undergo a metabolically demanding maturation program before shedding platelets into the bloodstream. Aging impairs their proliferation, differentiation, and quality-control machinery through both intrinsic cellular defects and changes in the bone marrow environment. Yet the precise molecular drivers of megakaryocyte decline during natural aging have remained poorly defined, and no targeted nutritional intervention had been shown to reverse it.

The research team, led by investigators affiliated with the Sun Yat-sen University Health System, took an unusually rigorous approach for a nutrition study. Rather than relying on accelerated genetic aging models, they used naturally aged male C57BL/6J mice, dividing 84 animals into cohorts starting at 1, 9, 15, 19, 21, and 23 months of age. Each cohort received either a control diet or the same diet supplemented with CoQ10 at 550 milligrams per kilogram of chow for 12 weeks, a dose the authors calculate as roughly equivalent to 300 milligrams per day for a 60-kilogram adult. The mice were then analyzed at 4, 12, 18, 22, 24, and 26 months of age, spanning nearly the entire murine lifespan.

The systemic effects of the supplement were clear and age-dependent. CoQ10-treated mice showed reduced levels of reactive oxygen species and malondialdehyde, a marker of lipid peroxidation, along with increased total antioxidant capacity and higher activity of the antioxidant enzymes superoxide dismutase, catalase, and glutathione. Chronic inflammation, the smoldering fire that accompanies aging, also receded: plasma concentrations of the inflammatory cytokines IL-6, TNF-alpha, and IL-1beta were significantly lower in supplemented animals, with IL-1beta dropping as early as 12 months. Circulating klotho, a protein whose decline is closely associated with aging, was modestly preserved, reaching statistical significance at 24 months. Notably, blood levels of ubiquinol and ubiquinone, the two forms of CoQ10, rose most clearly in mice older than 22 months, suggesting the biological effects of supplementation become most pronounced in advanced age, when endogenous CoQ10 availability has waned.

Within the bone marrow, the changes were striking. Colony-forming assays revealed that megakaryocytes from CoQ10-fed mice proliferated more vigorously, forming larger and more numerous colonies at 12, 16, and 18 months. Flow cytometry showed increased proportions of cells expressing the maturation markers CD41 and CD61, and ploidy analysis revealed a shift toward highly polyploid 16N, 32N, and 64N megakaryocytes, the fully mature end-stage cells most capable of platelet production, whereas control animals accumulated predominantly 8N cells. Apoptosis among megakaryocytes, which rises with age, was significantly reduced in the supplemented groups at 22, 24, and 26 months.

The mechanistic thread connecting these improvements was autophagy, the conserved intracellular recycling process by which cells digest damaged proteins and organelles. Autophagic activity declines with age across many tissues, and in the megakaryocytes of naturally aged mice the researchers observed exactly that pattern: the ratio of lipidated LC3-II to LC3-I, a standard readout of autophagosome formation, fell progressively, while the cargo receptor p62 accumulated. Twelve weeks of CoQ10 reversed both markers at nearly every age examined. Because LC3 and p62 were measured under steady-state conditions in the animal experiments, the authors are careful to note that these data indicate altered autophagic activity but do not by themselves prove enhanced autophagic flux in vivo.

To find the molecular link, the team turned to unbiased quantitative proteomics using Astral DIA mass spectrometry on megakaryocytes isolated from 24-month-old mice. Among the proteins upregulated by CoQ10, one stood out: COPS3, a core subunit of the COP9 signalosome, an evolutionarily conserved complex that regulates protein stability by deneddylating Cullin-RING ubiquitin ligases. In fact, the proteomic data showed that COPS3 was the most highly represented protein within the biological process of protein deneddylation, and several other COP9 subunits rose in parallel. Western blotting across the age series confirmed that COPS3 expression declines gradually with age and that CoQ10 supplementation significantly restores it, particularly at 24 months. Because the COP9 signalosome governs ubiquitin signaling, which is intricately intertwined with autophagy regulation, COPS3 offered a plausible bridge between the supplement and the cellular cleaning crew.

Cell-culture experiments in senescent MEG-01 human megakaryocytic cells, driven into senescence with hydrogen peroxide, put the hypothesis to the test. CoQ10 treatment raised COPS3 levels and shifted the autophagy markers in the direction of enhanced flux, and these effects persisted even when autophagy was pharmacologically blocked with LY294002. Critically, when the researchers silenced COPS3 with siRNA, the CoQ10-induced increase in the LC3-II/LC3-I ratio, the reduction in p62, and the improvements in maturation-marker expression and polyploidization were all partially attenuated. A bafilomycin A1 turnover assay, which blocks lysosomal degradation and thereby reveals how much LC3-II is actually being delivered to lysosomes, provided direct evidence that CoQ10 enhances autophagic flux rather than merely causing autophagosomes to pile up. The incomplete rescue after COPS3 knockdown tells an honest story: COPS3 is a functional contributor to CoQ10’s effects, but not their sole mediator, and gain-of-function and rescue experiments remain to be done.

The downstream consequence for platelet biology is perhaps the most clinically tantalizing finding. Collagen-induced platelet aggregation, which rises with age and peaks before declining at the very oldest ages, was significantly suppressed in CoQ10-fed mice from 18 through 26 months. Activation markers CD62P and JON/A, an antibody that reports the active conformation of the integrin alphaIIb-beta3, were similarly reduced. Importantly, these benefits came without apparent costs: platelet counts, reticulated platelet percentages, and tail-bleeding times were unchanged, suggesting the supplement tames platelet hyperreactivity without crippling primary hemostasis. The authors caution, however, that tail-bleeding time is a crude measure of hemostasis and that these results should not be read as evidence that CoQ10 prevents thrombosis in older adults.

The study is candid about its limits. The mechanistic cell work used an induced senescence model rather than primary megakaryocytes, the in vitro CoQ10 concentration of 100 micromolar exceeds what oral supplementation typically achieves in blood, only a single dietary dose was tested, and only male mice were studied, leaving open whether females respond similarly. How CoQ10, a molecule best known for shuttling electrons inside mitochondria, signals to the nucleus to raise COPS3 expression remains unresolved, though prior work showing that CoQ10 modulates Nrf2 and NF-kappaB-dependent transcription offers plausible routes. Even with those caveats, the convergence of a lifespan-scale dietary intervention, proteomic discovery, genetic knockdown, and flux assays makes a compelling case that CoQ10 supports proteostatic resilience in aging megakaryocytes through a COPS3-autophagy axis. For a supplement often dismissed as scientifically soft, that is a remarkably concrete mechanism, and it points toward nutritional strategies for the platelet dysfunction of aging that now deserve proper clinical scrutiny.

Subject of Research: Effects of dietary coenzyme Q10 on age-related megakaryocyte dysfunction via COPS3-mediated autophagy activation

Article Title: Dietary CoQ10 Ameliorates Age‐Related Megakaryocyte Dysfunction via COPS3‐Mediated Activation of Autophagy

Article References: Xu, Y., Mao, Y.-H., Song, F., He, F., Wu, Y., Wang, C., Wang, M., Xie, S., Ni, H., & Yang, Y. (2026). Dietary CoQ10 Ameliorates Age‐Related Megakaryocyte Dysfunction via COPS3 ‐Mediated Activation of Autophagy. Aging Cell, 25(10), Article e70726. https://doi.org/10.1111/acel.70726

Image Credits: AI Generated

DOI: 10.1111/acel.70726

Keywords: coenzyme Q10, megakaryocytes, autophagy, COPS3, COP9 signalosome, aging, platelets, oxidative stress, inflammaging, bone marrow, proteomics, Aging Cell

The study, conducted by Özge Sönmez and Ahmet Emre Eşkazan of the Division of Hematology at Cerrahpaşa Faculty of Medicine, Istanbul University-Cerrahpaşa, used a web-based questionnaire to probe how hematologists manage extreme thrombocytosis, the technical term for platelet counts that far exceed the normal range of roughly 150,000 to 450,000 per microliter. Fifty-six hematologists participated in the survey, which was supported by the Turkish Society of Hematology and approved by the local clinical studies ethics committee at Istanbul University-Cerrahpaşa. The authors set out to map real-world clinical behavior in a domain where evidence is thin, expert opinion varies widely, and the consequences of over-treatment or under-treatment can be serious for patients with essential thrombocythemia, one of the classical Philadelphia-negative myeloproliferative neoplasms.

The central finding concerns the platelet threshold at which physicians choose to intensify therapy. Cytoreductive treatment, which uses medications such as hydroxyurea to suppress platelet production in the marrow, was favored by 41.1 percent of respondents once platelet counts reached or exceeded 1000 × 10⁹ per liter, the celebrated million-platelet mark. But when the threshold was raised to 1500 × 10⁹ per liter, the proportion of hematologists opting for cytoreduction jumped to 83.9 percent. In other words, the million mark alone is not a universal trigger for action; it is a point of debate. Only when counts approach one and a half million does a strong majority of specialists converge on drug-based platelet lowering, a pattern that mirrors the cautious, risk-adapted philosophy embedded in contemporary myeloproliferative neoplasm guidelines.

Why does the million mark inspire such hesitation? The answer lies in the biology of extreme thrombocytosis. Very high platelet counts do not simply increase the risk of blood clots; paradoxically, they also raise the risk of bleeding. The mechanism is acquired von Willebrand disease, a condition in which the sheer excess of circulating platelets adsorbs and proteolytically cleaves von Willebrand factor, the adhesive protein that platelets and clotting depend on. As platelets multiply, they effectively devour their own hemostatic infrastructure, and the largest von Willebrand multimers disappear first. A patient with a platelet count of a million or more may therefore present with gastrointestinal bleeding or bruising rather than thrombosis, and giving aspirin to such a patient in the belief that high platelets mean high clot risk can precipitate dangerous hemorrhage.

This biological nuance explains the second pillar of the survey: laboratory assessment. A striking 78.6 percent of hematologists reported testing for von Willebrand factor ristocetin cofactor activity, abbreviated vWF:RCo, at the time of diagnosis of extreme thrombocytosis. This assay measures the functional capacity of von Willebrand factor to support platelet adhesion under shear stress, and it is the workhorse test for detecting the acquired form of the deficiency. The near-universal uptake of this test among survey respondents suggests that the field has internalized the lesson that platelet number alone is an unreliable guide to bleeding risk, and that documenting acquired von Willebrand disease is now considered a standard part of the initial evaluation when counts soar into the extreme range.

Aspirin decisions revealed an equally disciplined logic. In the presence of cardiovascular risk factors and in the absence of acquired von Willebrand disease, 91.1 percent of hematologists favored aspirin therapy for patients with platelet counts of at least 1000 × 10⁹ per liter, and 78.6 percent favored it at counts of at least 1500 × 10⁹ per liter. The slight decline at the higher threshold is telling: the very patients with the most extreme counts are also the most likely to harbor acquired von Willebrand disease, so the antiplatelet drug that protects one patient’s arteries becomes a hemorrhagic hazard for another. The survey thus captures, in numerical form, the delicate balancing act that defines extreme thrombocytosis management, where the same count can argue for and against the same drug depending on a single laboratory result.

When asked why they initiate cytoreductive treatment at all, respondents cited three goals with roughly equal frequency: prevention of thrombosis, prevention of bleeding, and control of symptoms such as headaches, erythromelalgia, and visual disturbances. This even distribution is itself informative. It shows that hematologists do not view cytoreduction solely as an anti-thrombotic strategy. Lowering the platelet count can restore von Willebrand factor levels and relieve bleeding, and it can also ameliorate the microvascular symptoms that plague many patients with essential thrombocythemia regardless of their thrombotic risk score. The therapeutic rationale, in practice, is tripartite, and the survey suggests that experienced clinicians weigh all three aims rather than fixating on any single one.

The most novel element of the report is its comparison with artificial intelligence. The authors posed the same clinical scenarios to AI programs and recorded the recommendations the models produced. The AI-generated advice supported von Willebrand testing, endorsed cytoreductive treatment particularly at platelet counts of 1500 × 10⁹ per liter or above, and generally recommended aspirin only for patients with counts of at least 1000 × 10⁹ per liter who did not have acquired von Willebrand disease. Across several clinical scenarios, the differences between the human specialists and the machine recommendations were few. The authors are careful to frame this comparison as exploratory, and they stop short of claiming that AI can substitute for clinical judgment, but the convergence is noteworthy at a time when large language models are being proposed as clinical decision aids.

The significance of this convergence deserves careful interpretation. On one hand, it suggests that the consensus positions in hematology, such as testing for acquired von Willebrand disease and reserving aggressive cytoreduction for the most extreme counts, are encoded deeply enough in the published literature that AI systems trained on that literature reproduce them faithfully. On the other hand, it raises the question of whether AI is genuinely reasoning or simply echoing the dominant patterns of its training data, including their blind spots. Where expert opinion is divided, as it clearly is at the million-platelet threshold where only about four in ten specialists opt for cytoreduction, an AI that confidently recommends a single course of action could flatten legitimate clinical nuance into false certainty. The survey’s exploratory design is a prudent acknowledgment of that risk.

For patients with essential thrombocythemia, the practical message of the study is reassuring in one respect and cautionary in another. Reassuring, because the management of extreme thrombocytosis appears to follow a coherent, biologically informed playbook: check von Willebrand function, tailor aspirin to its result, and reserve cytoreductive drugs chiefly for the most extreme counts or for patients with thrombosis, bleeding, or disabling symptoms. Cautionary, because the survey also exposes genuine variability at the margins, with more than half of specialists declining to treat at exactly one million platelets while others intervene. As Sönmez and Eşkazan conclude, extreme thrombocytosis itself remains an important driver of treatment decisions, particularly above 1500 × 10⁹ per liter, and the near-agreement between experienced hematologists and AI recommendations offers a provocative glimpse of a future in which algorithms may help standardize care, provided they are validated rigorously and deployed with the same humility that the survey’s authors bring to their own exploratory analysis.

Subject of Research: Clinical management of extreme thrombocytosis in essential thrombocythemia, comparing hematologist survey responses with artificial intelligence recommendations

Article Title: When platelets reach a million: insights from hematologists

Article References: Sönmez, Ö., & Eşkazan, A. E. (2026). When platelets reach a million: insights from hematologists. Annals of Hematology. https://doi.org/10.1007/s00277-026-07183-x

Image Credits: AI Generated

DOI: 10.1007/s00277-026-07183-x

Keywords: essential thrombocythemia, extreme thrombocytosis, platelets, cytoreductive therapy, acquired von Willebrand disease, aspirin, von Willebrand factor, myeloproliferative neoplasms, hematology, artificial intelligence, clinical survey, thrombosis