The research team, led by Gaoquan Zheng, Dianqing Li, and colleagues, set out to test whether a deliberate local pH signal built into the implant interface could guide neutrophil behavior and strengthen host antibacterial defense without adding any exogenous bactericidal agent. Neutrophils are among the first innate immune cells recruited to infected sites, and beyond phagocytosis and degranulation they can release neutrophil extracellular traps, or NETs, which are extracellular chromatin-based networks that capture pathogens and limit their spread. Prior work had hinted that extracellular pH regulates this process: bicarbonate-rich pancreatic fluid has been shown to promote PADI4-dependent aggregated NET formation, a high bicarbonate-to-CO2 ratio and moderately alkaline pH favor NET release, and extracellular acidosis suppresses ROS-dependent NETosis. What remained poorly understood was how such a physicochemical cue is converted into functional changes inside the neutrophil, and whether it could be harnessed at a biomaterial surface.

To create the alkaline interface, the researchers subjected titanium plates to a hydrothermal reaction in a mixed sodium hydroxide and hydrogen peroxide solution at 80 degrees Celsius for 24 hours, followed by hydrochloric acid-mediated ion exchange to remove excess sodium-containing alkaline species and a thermal treatment ramping to 450 degrees Celsius. The resulting material, designated Ti-A, developed a uniform nanoscale porous architecture visible by scanning electron microscopy, in contrast to the relatively smooth pristine titanium surface. X-ray diffraction confirmed a mixed anatase and rutile TiO2 crystalline structure, and X-ray photoelectron spectroscopy detected a distinct sodium signal reflecting the incorporation of sodium-related species during alkali treatment. Critically, pH measurements taken approximately two millimeters above the surface showed that Ti-A maintained a local pH of roughly 7.88 in ultrapure water and, importantly, remained within a mildly alkaline range of about 7.49 to 7.78 even under physiological buffering conditions in PBS and cell culture medium over 48 hours.

The team then verified that this modified surface was compatible with the cells that matter. Rat bone marrow mesenchymal stem cells cultured on Ti-A retained well-organized F-actin cytoskeletons and intact nuclear morphology, with metabolic activity remaining approximately 92 percent of that observed on pristine titanium despite a modest but significant reduction. Neutrophils exposed to Ti-A for six hours retained roughly 89 percent of their CCK-8 metabolic signal, indicating that the interface did not cause extensive loss of neutrophil viability during the NET-induction period. With biocompatibility established, the researchers turned to the central question of whether Ti-A could trigger bona fide NET formation rather than nonspecific DNA leakage. SYTOX Green staining revealed more extracellular DNA-positive structures on Ti-A than on pristine Ti, and DNase I treatment markedly reduced these networks, confirming their dependence on a DNA scaffold.

Further molecular evidence strengthened the case. Ti-A markedly increased signals of citrullinated histone H3, a chromatin modification closely associated with NET formation, which colocalized with extracellular chromatin regions. Enzyme-linked immunosorbent assays showed higher levels of MPO-DNA complexes in the Ti-A group, indicating co-release of extracellular chromatin with neutrophil granule proteins, a biochemical hallmark of genuine NETs. When neutrophils and S. aureus were co-incubated on the surfaces for six hours, Ti-A achieved an antibacterial rate of approximately 86.67 percent compared with 47.50 percent on pristine titanium. Even without neutrophils present, Ti-A reduced bacterial survival, demonstrating intrinsic surface antibacterial activity, but the addition of neutrophils revealed a substantial host-mediated enhancement on top of that direct effect.

To dissect the mechanism, the researchers applied two pharmacological tools. DNase I, which degrades the extracellular DNA backbone of NETs, caused colony formation on Ti-A to rise sharply and the antibacterial rate to fall to a level close to that of Ti-A alone, indicating that NET-associated extracellular DNA structures were a major contributor to the enhanced killing. Cytochalasin D, which inhibits actin-dependent phagocytosis, also reduced the antibacterial rate, but it remained higher than that of Ti-A alone, suggesting that phagocytosis contributed without fully accounting for the neutrophil-mediated advantage. Together, these experiments established that beyond directly restricting bacterial survival, the alkaline interface amplified neutrophil extracellular killing as the dominant antibacterial mechanism.

The deepest insight of the study came from untargeted metabolomic profiling of neutrophils stimulated on the two surfaces. Volcano plot analysis revealed 77 upregulated and 7 downregulated metabolites in the Ti-A group, with lipid metabolism dominating the differential profile. Sphingosine and N-palmitoyl-D-sphingosine were elevated and ranked among the most important metabolites distinguishing Ti-A-stimulated neutrophils from controls, while 6-phosphogluconic acid, a metabolite of the oxidative pentose phosphate pathway that supplies NADPH for reactive oxygen species generation, was also increased. KEGG enrichment analysis placed sphingolipid metabolism and sphingolipid signaling among the top enriched pathways. This metabolic signature pointed the investigators toward a specific signaling axis: sphingosine can be phosphorylated by sphingosine kinase 1, or SPHK1, to generate sphingosine-1-phosphate, which signals through receptors including S1PR2 and may engage calcium- and MAPK-related pathways linked to PAD4 activation, histone H3 citrullination, chromatin decondensation, and NET formation.

Subsequent molecular and pharmacological experiments supported this model. Neutrophils on Ti-A showed markedly stronger intracellular oxidative signals by DCFH-DA fluorescence and flow cytometry, and both SPHK1 and S1PR2 were significantly upregulated at the mRNA and protein levels. Notably, PMA, a standard positive NET-inducing stimulus, enhanced oxidative activity without inducing comparable SPHK1 or S1PR2 increases, indicating that this upregulation is not a generic consequence of NET induction but is more closely tied to the sphingolipid remodeling triggered by Ti-A. When the researchers blocked the pathway with PF-543, a selective SPHK1 inhibitor, or with DPI, which suppresses NADPH oxidase-derived ROS production, both the web-like extracellular DNA structures and the intracellular oxidative signal were significantly attenuated. Because neither inhibitor completely abolished NET formation, the authors conclude that the SPHK1-S1PR2/ROS axis makes a substantial contribution while operating alongside other signaling events initiated at the interface.

The strategy then faced its most demanding test in vivo. Titanium and Ti-A implants preloaded with S. aureus were inserted into femoral condyle defects in rats. At three days after surgery, fewer colonies were recovered from peri-implant bone tissues in the Ti-A group, accompanied by stronger Ly6G neutrophil staining, enhanced H3Cit signals indicating histone citrullination, and elevated SPHK1 and S1PR2 expression at the interface. At two months, bacterial burden remained significantly lower around Ti-A implants, and micro-CT reconstruction showed more newly formed bone with significantly higher bone volume fraction and bone mineral density. Histology revealed richer bone matrix and collagen deposition, stronger osteopontin staining, and milder inflammatory infiltration, while H&E staining of major organs showed no pathological damage, indicating no evident systemic toxicity.

Importantly, the modified interface did not trade immune-antibacterial activity for impaired osteogenic function. In vitro, Ti-A supported stronger alkaline phosphatase staining and activity, more extensive Alizarin Red S mineral deposition, and increased Runx2 and Col1a1 expression during osteogenic induction. The authors caution that the biological consequences of NET formation depend strongly on timing, magnitude, and clearance: early NETs can immobilize bacteria and assist macrophage-mediated killing, whereas persistent or excessive NETs may sustain inflammation and damage tissue. Their experiments did not track NET formation and clearance continuously, and serial measurements at intermediate time points will be needed to define how the response subsides as the interface shifts from infection control toward tissue repair. Nevertheless, the work positions mild interfacial alkalinity as a host-responsive design cue for anti-infective bone implants, offering a route to coordinate early infection control and subsequent bone regeneration that could hold particular translational value for patients facing infected bone defects where both problems must be solved concurrently.

Subject of Research: Mildly alkaline titanium implant interfaces regulating neutrophil sphingolipid immunometabolism and NET formation for antibacterial host defense and bone repair

Article Title: Interfacial mild alkalinity shapes Neutrophil immunometabolism through sphingolipid remodeling to enhance antibacterial host defense

Article References: Interfacial mild alkalinity shapes Neutrophil immunometabolism through sphingolipid remodeling to enhance antibacterial host defense. (n.d.). https://doi.org/10.1016/j.mtbio.2026.103691

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103691

Keywords: neutrophils, neutrophil extracellular traps, implant-associated infection, titanium implant, interfacial pH, sphingolipid metabolism, SPHK1, S1PR2, reactive oxygen species, Staphylococcus aureus, osseointegration, bone regeneration

NETosis is a relatively recent addition to the immunology lexicon. First recognised as a mechanism for trapping and killing microbes, it involves the formation of neutrophil extracellular traps, or NETs, which are web-like lattices of DNA studded with antimicrobial proteins. The process can unfold in two distinct ways. In vital NETosis, the neutrophil remains alive and functional while deploying its DNA weapon, typically in response to pathogen-associated molecular patterns derived from microbes. In suicidal or lytic NETosis, the cell perishes: its nuclear envelope disintegrates, its plasma membrane ruptures, and DNA chains decorated with citrullinated histones, neutrophil elastase and myeloperoxidase spill into the extracellular space. The molecular choreography is intricate. An enzyme called peptidyl-arginine deiminase 4 citrullinates histones, loosening the grip of chromatin, while granule enzymes translocate to the nucleus to cleave histones further, allowing the genetic material to decondense before its dramatic release.

Although NETosis has been implicated in atherosclerosis and thromboinflammation, its role in chronic heart failure remained underexplored. The research team, led by Sawa Kostin and colleagues, examined left ventricular tissue from 21 patients undergoing orthotopic heart transplantation. The patients fell into three groups matched for age, symptom severity, medication and comorbidities: seven with inflammatory cardiomyopathy following histologically proven myocarditis, seven with idiopathic dilated cardiomyopathy, and seven with ischaemic cardiomyopathy caused by severe coronary artery disease. Crucially, in the ischaemic group the researchers analysed only tissue remote from previous infarcts, ensuring that observed inflammation reflected the failing heart as a whole rather than scarred regions. As controls, they used myocardial samples from five patients with aortic stenosis whose left ventricular function was fully preserved and whose tissue showed no damage, inflammation or fibrosis.

The results were striking. Using immunolabelling for CD66b, a neutrophil marker, the team found that control myocardium contained a median of just 2.48 neutrophils per square millimetre. In the failing hearts, that figure soared to 11.4 cells in dilated cardiomyopathy, 13.9 in ischaemic cardiomyopathy and 15.5 in inflammatory cardiomyopathy, a four- to six-fold increase. To detect NETosis directly, the researchers stained for citrullinated histone 3 and myeloperoxidase, two molecular signatures of NET formation. Confocal microscopy revealed thin, long NET structures, ranging from 5 to 50 micrometres, positive for both DNA and citrullinated histone 3, weaving through the failing myocardium. No such structures appeared in control tissue.

Biochemical and molecular assays corroborated the microscopy. Western blot analysis showed that citrullinated histone 3 protein levels were 4.8-fold higher in inflammatory cardiomyopathy, 4.4-fold higher in ischaemic cardiomyopathy and 2.7-fold higher in dilated cardiomyopathy compared with controls, with all differences statistically significant. Quantitative polymerase chain reaction confirmed that myeloperoxidase messenger RNA was three to four times more abundant in the failing hearts. When the researchers counted neutrophils positive for both CD66b and citrullinated histone 3, they found medians of 7.94 cells per square millimetre in inflammatory cardiomyopathy, 5.51 in dilated cardiomyopathy and 5.79 in ischaemic cardiomyopathy, against just 1.12 in controls. Triple staining for CD66b, citrullinated histone 3 and myeloperoxidase revealed a 4.6- to 6.1-fold increase across all heart failure groups, with no significant differences between aetiologies.

Macrophages told an equally compelling story. These highly plastic cells, which can polarise into classically activated M1-like macrophages that drive inflammation or alternatively activated M2-like macrophages that promote repair and phagocytosis, are among the most active immune participants in cardiac remodelling. Counting CD68-positive cells, the team found a median of 13.3 macrophages per square millimetre in control myocardium, rising to 47.1 in dilated cardiomyopathy, 55.4 in ischaemic cardiomyopathy and 69.4 in inflammatory cardiomyopathy. Remarkably, macrophage numbers correlated very strongly with neutrophil counts, with a Spearman coefficient of 0.918, suggesting the two cell populations accumulate in lockstep within the diseased heart.

Phenotyping revealed a decisive shift. In control tissue, only about 3 percent of macrophages displayed the M1-like profile, identified by co-expression of CD68 with tumour necrosis factor alpha or interleukin-6, while roughly 6.5 percent were M2-like, marked by CD206 or arginase-1. In the failing hearts, M1-like macrophages dominated: 78.5 percent in inflammatory cardiomyopathy, 54.5 percent in ischaemic cardiomyopathy and 53.2 percent in dilated cardiomyopathy. M2-like macrophages also increased, reaching roughly 21 to 23 percent, but never matched the proinflammatory surge. The resulting M1-to-M2 ratio, a measure of inflammatory balance, stood at 3.19 in inflammatory cardiomyopathy and around 2.5 to 2.6 in the other groups, compared with just 0.63 in controls, all differences statistically significant.

The pivotal finding emerged when the researchers correlated NETosis with macrophage polarisation. The percentage of M1-like macrophages correlated positively and significantly with the number of neutrophils undergoing NETosis, with a correlation coefficient of 0.79 for triple-positive citH3/MPO/CD66b cells and 0.68 for citH3/CD66b cells. In contrast, M2-like macrophages showed no meaningful association with NETosis, with coefficients near zero and non-significant p-values. Triple immunolabelling for citrullinated histone 3, tumour necrosis factor alpha and CD206 provided visual confirmation: NET-forming neutrophils were consistently surrounded by far more TNF-alpha-positive M1-like macrophages than CD206-positive M2-like cells.

What might this interplay mean mechanistically? Prior work offers intriguing clues. Co-culture experiments have shown that both M1- and M2-like macrophages can degrade NETs, with M1-like cells dominating the early phagocytic response and M2-like cells completing clearance later. Studies in acute pulmonary ischaemia-reperfusion injury have described a mutual feedback loop in which NETosis drives M1-like polarisation, which in turn promotes further NETosis. The authors suggest that in chronic heart failure this reciprocal interaction may create a positive feedback loop that sustains low-grade myocardial inflammation, a recognised hallmark of the disease. Alternatively, the M1 skewing could represent a compensatory attempt to clear excessive NETs, one that fails to suppress NET formation itself. The concurrent rise in M2-like macrophages, albeit more modest, may reflect involvement in clearing dead cardiomyocytes and contributing to fibrosis, given that the failing heart loses an estimated 20 percent of its cardiomyocytes each year in terminal stages.

The authors are careful to note that correlation does not establish causation, and that the observed associations may be consequences of chronic heart failure rather than drivers of it. The study’s limitations include the small number of patients, the differing aetiologies across groups and considerable interindividual variability. Nevertheless, the consistency of the findings across inflammatory, dilated and ischaemic forms of the disease, and the earlier observation that neutrophil and macrophage accumulation precedes overt heart failure in compensated hypertrophy, lend weight to the idea that this immune axis matters. Recent research also implicates extracellular vesicles released by injured cardiomyocytes in promoting neutrophil-driven inflammation and macrophage polarisation, suggesting multiple routes by which tissue damage could ignite the NETosis-macrophage circuit. If future studies confirm a causal role, inhibiting NETosis or restoring the balance between M1- and M2-like macrophages could become genuine therapeutic strategies for chronic heart failure, a condition that still lacks treatments targeting its inflammatory underpinnings. For now, the study provides a rigorous anatomical and molecular map of that circuit in human tissue, and a clear hypothesis for the next generation of experiments.

Subject of Research: The association between neutrophil extracellular trap formation and proinflammatory macrophage polarisation in human heart failure

Article Title: Increased NETosis in Patients With Heart Failure Is Associated With Macrophage Activation Towards a Proinflammatory Phenotype

Article References: Kostin, S., Cabrera‐Fuentes, H. A., Richter, M., Krizanic, F., Ritter, O., Boisvert, W. A., Preissner, K. T., Kelesidis, T., Siasos, G., & Pagonas, N. (2026). Increased NETosis in Patients With Heart Failure Is Associated With Macrophage Activation Towards a Proinflammatory Phenotype. Journal of Cellular and Molecular Medicine, 30(17), Article e71306. https://doi.org/10.1111/jcmm.71306

Image Credits: AI Generated

DOI: 10.1111/jcmm.71306

Keywords: heart failure, NETosis, neutrophils, macrophages, M1 polarisation, myocardial inflammation, citrullinated histone 3, myeloperoxidase, cardiac remodelling, innate immunity, cardiomyopathy, immunohistochemistry

The clinical backdrop makes the advance urgent. Gastric cancer remains one of the world’s deadliest malignancies, characterized by molecular heterogeneity, a high propensity for metastatic spread, and frequent therapeutic resistance. Immune checkpoint blockade, particularly antibodies against the PD-1/PD-L1 axis, has transformed outcomes in several tumor types, yet in gastric cancer the response rates stubbornly remain below 30 percent, with a substantial fraction of patients showing intrinsic resistance from the very first dose. The researchers turned to cancer genetics for an explanation. A significant subset of gastric cancers, especially those defined by chromosomal instability, carry two simultaneous alterations: loss of the tumor suppressor TP53 and hyperactivation of YAP, the transcriptional co-activator that serves as the main effector of the Hippo signaling pathway. YAP1 is amplified in roughly 18 percent of human gastric cancers, and the combination of YAP activation with p53 loss correlates clinically with aggressive, refractory disease. Whether this genetic pairing was a mere correlation or a true causal driver of immunotherapy resistance was the central question the study set out to answer.

To probe that question, the investigators engineered a sophisticated mouse model they call AYP. These animals carry a conditional, constitutively active YAP1 mutant, designated Yap1-6A, in which six phosphorylation sites were mutated so the protein resists degradation, together with floxed Tp53 alleles. Both alterations were activated specifically in the Atp4b-expressing parietal cell lineage of the stomach, which encompasses parietal cell progenitors, pre-parietal cells, and mature acid-producing cells. After tamoxifen induction, the mice developed invasive gastric adenocarcinoma within two to three months, with a median survival of 131 days. Crucially, the model demonstrated biological synergy rather than mere additivity: mice with YAP activation alone or p53 loss alone failed to develop gastric cancer even ten months after induction, while the double-hit configuration produced fully penetrant, aggressive malignancy. Histopathological examination revealed the full spectrum of human disease, including well-differentiated intestinal-type tumors, poorly differentiated signet-ring cell carcinomas of the diffuse type, and mixed forms, all accompanied by dense immune infiltration.

The metastatic behavior of the model proved equally faithful to the human condition. By three to four months after induction, the majority of AYP mice had disseminated disease involving the gastric lymph node, diaphragm, liver, pancreas, mediastinal lymph node, and lung, with metastatic incidence rates recorded for each organ across the cohort. Fluorescent labeling confirmed that the metastatic lesions originated from the Atp4b-lineage tumor cells. When the researchers treated these mice with anti-PD-1 antibodies for three weeks, the results were sobering but clinically familiar: stomach weights were unchanged, metastatic incidence and morphology were unaltered, and histopathology confirmed no therapeutic response. Immune profiling showed only a modest reduction in neutrophils, regulatory T cells, and group 3 innate lymphoid cells. In other words, the AYP tumors were intrinsically resistant to PD-1 blockade despite being what immunologists would call hot tumors, densely infiltrated with immune cells that should, in principle, be attackable.

To find the mechanism, the team performed single-cell RNA sequencing on nearly 50,000 high-quality cells harvested from the stomach, gastric lymph node, and visible liver and lung metastases of AYP mice and matched wild-type controls. The analysis identified three distinct tumor cell clusters, and gene set variation analysis revealed strong enrichment of Hippo signaling, YAP/TAZ target gene signatures, epithelial-mesenchymal transition features, and immunosuppression programs. When the researchers compared the mouse tumor transcriptomes with a single-cell dataset from 26 gastric cancer patients, the AYP tumor cells correlated closely with human poorly differentiated gastric adenocarcinoma, including signet-ring cell carcinoma, with high correlation coefficients for signature genes such as OLFM4, PLA2G2A, and ENO1. A dominant feature of the microenvironment, at both primary and metastatic sites, was a pronounced infiltration of neutrophils displaying characteristics of polymorphonuclear myeloid-derived suppressor cells, key systemic mediators of immunosuppression that are clinically associated with poor immunotherapy responses. Depleting neutrophils substantially inhibited tumor development and metastasis, establishing these cells as essential players rather than bystanders.

The search for the molecular bridge between YAP and the suppressive microenvironment converged on BST2, or bone marrow stromal cell antigen 2. Integrated analysis of tumor cell signature genes and genes downregulated after YAP1 knockout identified BST2 as a top candidate. Immunofluorescence confirmed that BST2 was co-expressed with the tumor marker KRT7 specifically within tumor tissue and was undetectable in normal gastric epithelium. Clinically, the pattern was striking: both BST2 and YAP1 transcription were markedly higher in gastric cancer patients whose disease progressed on anti-PD-1 therapy than in those achieving complete or partial responses, mirroring established immunosuppressive markers such as NR4A1 and CD55. Mechanistically, the team showed that deleting YAP1 with CRISPR/Cas9 significantly reduced both BST2 mRNA and surface protein levels, and CUT&RUN assays demonstrated direct binding of the YAP1-TEAD4 transcriptional complex to the Bst2 promoter, formally establishing BST2 as a direct YAP target gene.

Functional experiments then revealed BST2 as a genuine immune checkpoint operating on innate immune cells. Deleting BST2 from AYP tumor cells had only a marginal effect on proliferation in a dish but significantly impaired tumor formation and growth in living mice, accompanied by reduced numbers of tumor-infiltrating neutrophils and lower PD-L1 expression on those cells, decreased exhaustion of natural killer and CD4 T cells, and increased production of the cytotoxic enzyme Granzyme B. Ligand-receptor interaction analysis pointed to BST2 engaging a receptor called PIRA2, the murine ortholog of human leukocyte immunoglobulin-like receptors, which is highly expressed on neutrophils. Co-immunoprecipitation and protein truncation experiments mapped the physical interface: the coiled-coil domain of BST2 directly binds the Ig-like domain of PIRA2 through two distinct contact surfaces. Co-culture assays confirmed that AYP tumor cells drive bone marrow cells toward an immunosuppressive SiglecF-positive, PD-L1-positive neutrophil phenotype, an effect abolished either by BST2 knockout or by a BST2-blocking antibody.

The liver emerged as a particularly instructive battleground. Kupffer cells, the resident macrophages of the liver, also express high levels of PIRA2, and transcriptional profiling showed that AYP mice accumulated immunosuppressive Kupffer cell subsets at the expense of immunostimulatory ones. In co-culture, AYP tumor cells expanded the pool of CD11b-high Kupffer cells and upregulated the suppressive markers Arg1 and PD-L1, effects again dependent on BST2. In a liver metastasis model based on splenic injection of tumor cells, BST2 deficiency significantly prolonged host survival, reduced metastatic tumor burden, and boosted Granzyme B production by liver CD8 T cells, indicating reinvigorated anti-tumor immunity. The therapeutic culmination came in the spontaneous AYP model itself: combining anti-BST2 with anti-PD-1 antibodies reduced stomach weights by nearly 30 percent compared with anti-PD-1 alone, restored glandular tissue architecture, and, most strikingly, completely eradicated visible liver metastases in all treated animals while suppressing lymph node spread beyond what either agent achieved alone.

The implications reach beyond gastric cancer. BST2 was upregulated in tumors from resistant patients across multiple cancer types, suggesting it may function as a pan-tumor marker of anti-PD-1 failure, and its known role in suppressing plasmacytoid dendritic cells offers a plausible explanation for how anti-BST2 therapy also curbed lymph node metastases. The study also raises tantalizing questions about the microbial dimension, since bacteria such as Helicobacter pylori and Streptococcus anginosus can activate YAP signaling in gastric epithelium, potentially sustaining the BST2-driven resistance program. Significant work remains before patients benefit: the downstream signaling events of BST2-PIRA2 engagement are not fully mapped, structural studies of the interaction are needed to design high-affinity blockers, and humanized anti-BST2 antibodies must now prove themselves in patient-derived models. Still, for the large population of patients whose hot, immune-infiltrated gastric tumors inexplicably shrug off PD-1 blockade, the identification of a druggable YAP-BST2 axis offers something they have not had before: a mechanistic explanation and a concrete combination strategy to test in the clinic.

Subject of Research: YAP-BST2-mediated intrinsic resistance to anti-PD-1 immunotherapy in metastatic gastric cancer

Article Title: Targeting the YAP‐BST2 Axis Overcomes Intrinsic Anti‐PD‐1 Resistance in Metastatic Gastric Cancer

Article References: Zhang, W., Wang, S., Wang, M., Yu, R., Yue, J., Shao, L., Zhang, H., Zhu, M., Tian, L., Cheng, S., Qin, W., Tang, Y., Han, Y., Wang, W., An, L., Meng, Y., Jiao, S., & Zhou, Z. (2026). Targeting the YAP‐BST2 Axis Overcomes Intrinsic Anti‐PD‐1 Resistance in Metastatic Gastric Cancer. Advanced Science, Article e77708. https://doi.org/10.1002/advs.77708

Image Credits: AI Generated

DOI: 10.1002/advs.77708

Keywords: gastric cancer, immunotherapy resistance, YAP, TP53, BST2, PD-1, neutrophils, Kupffer cells, PIRA2, Hippo pathway, mouse model, liver metastasis

The research team, led by investigators at the University Hospital Zurich, examined 112 patients who died or suffered a recurrent myocardial infarction within one year of their initial event, matching each case one-to-one with a control patient of the same age, sex, infarct subtype, symptom-onset timing, and recruiting site. All blood samples were drawn within 24 hours of symptom onset, capturing the inflammatory landscape at a moment when standard clinical markers had often not yet begun their climb. Compared with controls, the patients who later experienced adverse outcomes had significantly higher plasma concentrations of IL-8, cell-free DNA, and myeloperoxidase, along with a higher neutrophil-to-lymphocyte ratio.

These three soluble markers tell a coherent biological story. Interleukin-8, also known as CXCL8, is released by endothelial cells, monocytes, and macrophages at the first sign of injury and creates a chemical gradient that draws neutrophils to the damaged myocardium. Once there, neutrophils expel neutrophil extracellular traps, web-like structures composed of cell-free DNA studded with enzymes such as myeloperoxidase. Although these traps serve a protective purpose against pathogens, in the setting of atherosclerosis they can activate platelets and coagulation factors, potentially worsening the very thrombotic process that caused the infarction. The simultaneous elevation of IL-8, cfDNA, and MPO in patients who fared poorly points to a hyperactive IL-8 and NET axis operating in the hours immediately after coronary occlusion.

Perhaps the most striking finding concerns timing. When patients were stratified by how quickly they reached the hospital after symptoms began, IL-8 levels were already significantly elevated in those presenting within three hours, whereas high-sensitivity troponin T only became clearly discriminative in late presenters beyond six hours. Within the hyper-acute window, IL-8 outperformed troponin, NT-proBNP, C-reactive protein, and kidney function markers in distinguishing future events from stable outcomes. After adjusting for these confounders, the association between IL-8 and the combined endpoint of death or recurrent infarction was strongest among early presenters, with an odds ratio of 2.65 for patients arriving within six hours of symptom onset.

The temporal analysis extended to the prognosis itself. When the researchers focused on early adverse events occurring within thirty days, the association between IL-8 and risk strengthened markedly, reaching an adjusted odds ratio of 4.47. A formal statistical test confirmed a significant interaction between IL-8 levels and symptom-onset time, meaning that the predictive value of this chemokine is genuinely tied to how early in the disease course the measurement is taken. This finding carries practical implications, because the first hours after symptom onset have long been a diagnostic blind spot in which traditional biomarkers lag behind the rapidly evolving pathology.

Within the group of patients who experienced adverse outcomes, those who died had higher IL-8 and cfDNA levels than those who survived with a recurrent infarction, suggesting that fatal outcomes are characterized by an even more intense neutrophil-driven inflammatory response. The neutrophil-to-lymphocyte ratio, a simple calculation available from any standard blood count, was likewise higher in the death subgroup, echoing results from large trials such as CANTOS, where each quartile increase in this ratio corresponded to a roughly twenty percent rise in major adverse cardiovascular events.

Unsupervised clustering of the inflammatory data added another layer of insight. When patients were grouped according to their combined profiles of IL-8, cfDNA, neutrophil-to-lymphocyte ratio, and high-sensitivity C-reactive protein, one cluster was significantly enriched in patients presenting with acute heart failure, defined clinically as a Killip Class of two or higher, and in those who ultimately died. This overlap between systemic inflammation and acute heart failure suggests that high IL-8 levels may partly reflect the mechanistic basis of pump dysfunction rather than merely accompanying it, although the observational design of the study cannot resolve whether inflammation causes heart failure or simply mirrors it.

The researchers also tested whether adding IL-8 to the widely used GRACE 2.0 risk score would improve its predictive accuracy. After rigorous cross-validation, neither IL-8 alone nor the combined panel of inflammatory markers produced a statistically significant improvement over the existing score for the overall cohort, likely because the score already captures much of the relevant risk and because late presenters diluted the hyper-acute signal. The authors therefore frame IL-8 not as a universal upgrade to existing risk tools but as a precision-medicine candidate for the specific subgroup of patients who present within hours of symptom onset.

Several caveats temper the enthusiasm. The study was observational and matched by design, so it cannot establish causality, and the lack of an IL-8 gene in mice complicates experimental efforts to probe the chemokine’s role directly. Genetic association studies hint that polymorphisms in the IL-8 promoter influence both circulating levels and acute coronary syndrome risk, but larger studies will be needed to determine whether IL-8 drives worse outcomes or simply reports on them. The authors also note that no clinical cutoff value for IL-8 can be proposed from a case-control design, and external validation in an independent cohort remains essential.

Even so, the prospect of a point-of-care IL-8 test, paired with the humble neutrophil-to-lymphocyte ratio, offers a tantalizing vision for emergency cardiology: a rapid, early, and biologically grounded assessment of risk during the very first hours of a heart attack, when every clinical decision carries the greatest weight. Therapies targeting IL-8 signaling are already being explored in oncology, and this study adds urgency to investigating whether similar approaches might one day quiet the inflammatory storm that follows myocardial infarction.

Subject of Research: Interleukin-8 and neutrophil-related biomarkers as prognostic markers for one-year mortality after acute myocardial infarction

Article Title: Interleukin-8 and other neutrophil-related biomarkers are associated with 1-year mortality in patients with acute myocardial infarction

Article References: Wang, Y.-J., Matter, M. A., Rossi, V. A., Heg, D., Costantino, S., Paneni, F., Gallino, C., Stähli, B. E., Räber, L., Windecker, S., Mach, F., Gencer, B., Klingenberg, R., Rodondi, N., Nanchen, D., Levesque, M. P., Demler, O. V., Ruschitzka, F., & Matter, C. M. (2026). Interleukin-8 and other neutrophil-related biomarkers are associated with 1-year mortality in patients with acute myocardial infarction. Clinical Research in Cardiology. https://doi.org/10.1007/s00392-026-03026-x

Image Credits: AI Generated

DOI: 10.1007/s00392-026-03026-x

Keywords: interleukin-8, acute myocardial infarction, neutrophils, neutrophil extracellular traps, cell-free DNA, myeloperoxidase, neutrophil-to-lymphocyte ratio, biomarkers, mortality, inflammation, GRACE 2.0, cardiology

The new particles, described in Bioengineering & Translational Medicine, were created by researchers at the University of Michigan who wanted to solve a persistent problem in corticosteroid therapy. Dexamethasone has shown real promise in recent clinical trials for ARDS, improving outcomes where older steroids failed. Yet those benefits typically require high doses over prolonged regimens, and they appear limited to certain patient subgroups, with some patients actually faring worse after treatment. Free dexamethasone circulating through the bloodstream also triggers well-documented systemic effects, including neutrophilia, an abnormal rise in blood neutrophil counts, and lymphopenia, the depletion of lymphocytes. The Michigan team reasoned that if the drug could be packaged so that it preferentially reached neutrophils themselves, the therapeutic effect would be concentrated at the source of tissue damage while the rest of the body would be spared.

The fabrication strategy is elegantly simple. The researchers added an iron sulfate solution dropwise into a stirred solution of dexamethasone phosphate, triggering a nucleation-and-growth process in which amorphous iron-phosphate particles form with dexamethasone incorporated throughout the particle matrix. The resulting nanoparticles, dubbed Dex NP, measured approximately 75 nanometers in diameter with a zeta potential between negative 10 and negative 20 millivolts. Scanning electron microscopy confirmed uniform particle morphology, and energy-dispersive X-ray spectroscopy mapping showed that iron and dexamethasone phosphate were evenly distributed across each particle rather than segregated into layers. There was just one problem: when these first-generation particles were incubated with human neutrophils in whole blood, the cells ignored them completely. No internalization occurred, which meant the drug delivery concept would fail before it even left the bench.

The breakthrough came from reconsidering the particle surface. Nanoparticle behavior in blood is governed largely by the protein corona, the layer of plasma proteins that adsorbs onto the particle within seconds of exposure. Albumin, the most abundant plasma protein, is a known dysopsonin, meaning its presence on a particle surface actively discourages phagocytes from engulfing it. The team hypothesized that the ionic iron within the particle matrix could be exploited to change the surface chemistry. Because iron oxide can form at temperatures as low as 200 degrees Celsius in open air, the researchers heated their particles to 200, 215, and 230 degrees and monitored how the protein corona changed. Only temperatures above 215 degrees altered protein adsorption, so 215 degrees became the standard oxidation step, transforming Dex NP into DexOx NP.

Characterization confirmed the transformation worked exactly as intended. X-ray photoelectron spectroscopy of the top 10 nanometers of the particle surface revealed a shift from ferrous to ferric iron, consistent with iron oxide formation, while Fourier transform infrared spectroscopy showed that the characteristic peaks of dexamethasone phosphate survived the heating intact. This mattered because dexamethasone begins to thermally degrade only above 200 degrees Celsius, with degradation onset at 256 degrees under controlled heating rates, and the brief oxidation window used here was measured in minutes rather than the hour-long exposures that have degraded the drug in prior polymer studies. Release assays in phosphate-buffered saline at physiological temperature showed that dexamethasone emerging from the particles remained as therapeutically active as the free drug, confirming the payload was not compromised during manufacturing.

The biological consequences of oxidation were striking. When FITC-labeled particles were incubated in whole human blood and mouse blood, flow cytometry showed a distinct fluorescence shift in the neutrophil population for DexOx NP but not for the unoxidized particles, and confocal microscopy visualized the oxidized particles sitting inside neutrophils. Protein corona analysis explained why: total adsorbed protein dropped after oxidation, with marked reductions in the albumin and transferrin bands at roughly 60 and 80 kilodaltons, proteins known to adsorb poorly to iron oxide. Meanwhile, a slight increase in bands between 150 and 200 kilodaltons suggested immunoglobulins, which activate complement and drive phagocytosis, had taken their place. Less albumin blocking the surface and more immunoglobulin flagging the particle combined to make DexOx NP irresistible to neutrophils.

Safety testing came next, and the particles passed cleanly. DexOx NP caused no hemolysis of red blood cells, did not activate platelets, and left unactivated neutrophils untouched, indicating the particles could be infused systemically without triggering the very inflammation they were designed to treat. In activated neutrophils, however, the therapeutic effect was dramatic. When lipopolysaccharide was used to simulate bacterial activation, DexOx NP preserved L-selectin, an adhesion molecule shed during neutrophil activation, reducing shedding by 68 percent. This outperformed both free dexamethasone phosphate and the poorly internalized Dex NP, neither of which changed L-selectin expression at all. The effect depended on the glucocorticoid receptor, since mifepristone, a receptor antagonist, blunted the benefit, and control experiments with plain iron oxide particles confirmed the activity came from the dexamethasone rather than the metal.

The particles also tamed NETosis, the explosive process by which activated neutrophils expel DNA and intracellular contents, which drives tissue damage in ARDS. In neutrophils stimulated with phorbol 12-myristate 13-acetate, DexOx NP reduced total NET formation by 21 percent over five hours, while free dexamethasone phosphate, unoxidized particles, and cargo-free polystyrene particles had no effect. The mechanism likely involves inhibition of NADPH oxidase, the enzyme complex that initiates NET formation and whose p47phox subunit is a known corticosteroid target. Because internalized particles release dexamethasone directly into the cytosol where the glucocorticoid receptor resides, the team suggests the intracellular delivery route accelerates and amplifies the drug’s action compared with diffusion of free steroid from the extracellular fluid.

The decisive test came in a mouse model of acute lung injury, where lipopolysaccharide was instilled into the airways and treatments were injected into the tail vein one hour later. Both DexOx NP and free dexamethasone significantly reduced immune cell infiltration into the lungs, cutting total bronchoalveolar lavage cells by 37 and 34 percent respectively and neutrophil counts by 41 and 39 percent. Both treatments lowered the inflammatory cytokines IL-6 and TNF-alpha, and DexOx NP significantly reduced KC, a chemokine that recruits neutrophils to inflamed tissue. Cargo-free polystyrene particles, which neutrophils also engulf, did nothing, proving the benefit came from the drug rather than from particle diversion alone. Crucially, the side-effect profiles diverged sharply: free dexamethasone raised blood neutrophil counts by 57 percent and increased the neutrophil-to-lymphocyte ratio by 64 percent, classic signs of systemic steroid exposure, while DexOx NP produced neither effect. Liver enzymes, leukocyte counts, and body weight remained normal in healthy mice given the particles.

The findings point toward a broader strategy for taming acute inflammation without the blunt instrument of systemic steroids. Because the particles are composed of iron and the drug itself, with no exogenous polymer carrier, they avoid the stability, reproducibility, and loading problems that plague conventional formulations such as liposomes and PLGA particles. The researchers, who have filed a patent on composite drug particles, note that the approach could extend beyond dexamethasone to other corticosteroids and inflammatory diseases driven by neutrophil dysregulation. For a condition like ARDS, where clinicians have long struggled to harness steroid power without immunological collateral damage, a nanoparticle that speaks directly to the immune system’s most volatile cells represents a meaningful step toward precision anti-inflammatory medicine.

Subject of Research: Targeted dexamethasone nanoparticles that modulate neutrophil activity to treat acute neutrophilic inflammation and acute lung injury

Article Title: Iron‐dexamethasone nanoparticles mitigate acute neutrophilic inflammation

Article References: Felder, M. L., Guevara, M. V., Kupor, D., & Eniola‐Adefeso, O. (2026). Iron‐dexamethasone nanoparticles mitigate acute neutrophilic inflammation. Bioengineering & Translational Medicine, Article e70173. https://doi.org/10.1002/btm2.70173

Image Credits: AI Generated

DOI: 10.1002/btm2.70173

Keywords: neutrophils, dexamethasone, nanoparticles, acute lung injury, ARDS, drug delivery, inflammation, NETosis, protein corona, iron oxide, corticosteroids, immunomodulation

The phenomenon at the centre of the study is known as browning. White adipose tissue is primarily a storage organ, packing energy into a single large lipid droplet per cell. Under certain conditions, however, white fat depots recruit or generate beige adipocytes, cells enriched with mitochondria and with uncoupling protein 1, or UCP1, a molecule that dissipates the mitochondrial proton gradient as heat rather than capturing the energy as ATP. Browning is normally driven by cold exposure or by beta-adrenergic signalling, the same sympathetic pathway that activates classical brown fat. When beige adipogenesis works well, the body burns more fuel and stores less fat. When it fails, visceral fat expands and metabolic disease tends to follow.

Using male mice, the researchers found that stimulating beta-adrenergic receptors with the drug CL316,243, or exposing animals to cold, unexpectedly triggered an influx of neutrophils into epididymal white adipose tissue, a visceral fat depot, but not into subcutaneous fat or brown fat. These infiltrating neutrophils carried activated neutrophil elastase and proteinase 3, enzymes stored in granules and released during inflammation. At the same time that the tissue was being instructed to brown, the arriving neutrophils were deploying proteases that shut the process down. The team showed that when neutrophil elastase was genetically deleted, or when the enzyme was blocked locally within the fat pad using sivelestat, an approved neutrophil elastase inhibitor, browning of visceral fat in response to adrenergic stimulation was substantially rescued, and UCP1 protein levels rose.

The mechanistic work went several layers deep. First, the proteases acted on beige adipocyte precursors, the progenitor cells from which new beige fat cells arise. Neutrophil elastase and proteinase 3 suppressed the proliferation of these precursors by downregulating CDK4 and cyclin D1, two core components of the cell cycle machinery that drive the G1 to S phase transition. With those drivers suppressed, precursor cells became arrested, reducing the pool of cells available for commitment to the beige lineage. This matters because de novo recruitment of beige adipocytes from progenitors, rather than mere activation of pre-existing cells, is a major route through which visceral fat gains thermogenic capacity during cold adaptation.

Second, the enzymes interfered with the differentiation programme itself. The researchers identified insulin-like growth factor binding protein 3, or IGFBP-3, as a critical substrate. IGFBP-3 supports beige adipocyte differentiation, and the neutrophil proteases cleaved it, degrading the factor and thereby weakening the differentiation signal. Prior literature had established that neutrophil elastase and proteinase 3 can function as IGFBP proteases in inflammatory settings, and the new work places that degradative activity squarely within fat tissue biology, linking it to impaired beige adipogenesis. When protease activity was inhibited, IGFBP-3 was preserved and differentiation proceeded more effectively.

Third, the study revealed an indirect route of inhibition. Neutrophil-derived proteases promoted the polarization of adipose tissue macrophages toward the M1, classically inflammatory phenotype. M1 macrophages secrete pro-inflammatory cytokines that are known to suppress thermogenic gene expression and to antagonize the type 2 immune signals, including eosinophil-derived interleukins and M2 macrophage activity, that normally support beige fat development. By tipping the macrophage balance toward inflammation, neutrophils created a tissue environment hostile to thermogenic adipocyte formation, compounding their direct effects on precursors and differentiation.

Importantly, the findings were not confined to mouse models. Analysis of publicly available single-cell RNA sequencing datasets from human adipose tissue revealed elevated expression of ELANE, the gene encoding neutrophil elastase, and PRTN3, the gene encoding proteinase 3, in visceral fat of individuals with obesity, particularly those with type 2 diabetes, compared with subcutaneous fat. Conversely, IGFBP3 expression in adipocytes showed correlations consistent with the proteolytic pathway identified in mice. In laboratory cultures, recombinant human neutrophil elastase and proteinase 3 suppressed the proliferation of human visceral preadipocytes, arrested their cell cycle, and impaired their differentiation into beige adipocytes, mirroring the murine results at the level of human cells.

The therapeutic implications emerged from experiments in mice fed a high-fat diet. Long-term feeding sustained neutrophil infiltration specifically in epididymal visceral fat over ten months. When diet-induced obese mice received sivelestat, the drug suppressed neutrophil activity, enhanced cold-induced browning of visceral fat, decreased visceral fat content, and increased energy expenditure. Sivelestat is already clinically validated for other indications, having been developed and used as a neutrophil elastase inhibitor for acute lung injury and acute respiratory distress syndrome, notably in Japan and in experimental protocols for COVID-19-related lung damage. The prospect of repurposing an existing, safety-characterized drug for obesity treatment is precisely the kind of translational shortcut that draws attention in metabolic medicine, although the authors and the field will recognize that mouse-to-human translation in adipose biology is notoriously fraught, and that sex differences in both browning and neutrophil behaviour, documented in this study and in prior work, complicate extrapolation.

What makes the study conceptually striking is the reversal of expectations. Earlier research had emphasized destructive roles of neutrophils in adipose tissue, including elastase-driven insulin resistance described by Talukdar and colleagues in 2012, and more recent work has even suggested neutrophils help preserve energy stores in activated fat. The new findings position neutrophils as active gatekeepers of adipose plasticity, dynamically throttling the tissue’s thermogenic capacity exactly when sympathetic signals demand it. Whether this represents an evolutionary trade-off, dampening energy expenditure during inflammatory stress, or a maladaptive modern interaction between chronic low-grade inflammation of obesity and an ancient immune programme, remains an open question. What is clear is that the protease activity provides a concrete, druggable point of intervention in a pathway previously managed only through diffuse targets such as sympathetic stimulation, which carries cardiovascular side effects in humans.

The work also refines the emerging picture of immune-metabolic crosstalk in fat. Eosinophils, M2 macrophages, and type 2 cytokines have been shown to promote beige fat; sympathetic neuron-associated macrophages can do the opposite by consuming norepinephrine. Neutrophils and their serine proteases now join this cast, with a mechanism that operates at three levels at once: cell cycle arrest of progenitors, proteolytic destruction of a differentiation factor, and inflammatory remodelling of the macrophage landscape. For the millions of people carrying metabolically harmful visceral fat, the study suggests that taming neutrophil elastase could, in principle, unlock the fat-burning potential already latent within their tissue, and it hands researchers a precise molecular target with which to test that proposition in the clinic.

Subject of Research: How neutrophil serine proteases inhibit thermogenic browning of visceral white adipose tissue

Article Title: Neutrophil serine proteases inhibit thermogenic capacity of visceral white adipose tissue

Article References: Yuan, L., Wu, X., Zong, J., Jiang, M., Gao, S., Zhang, Z., Huang, X., Zhu, M., Xiang, M., Wang, L., Ping, Z., Pan, Y., Ye, D., Xu, A., & Hoo, R. L. C. (2026). Neutrophil serine proteases inhibit thermogenic capacity of visceral white adipose tissue. Nature Metabolism. https://doi.org/10.1038/s42255-026-01598-6

Image Credits: AI Generated

DOI: 10.1038/s42255-026-01598-6

Keywords: neutrophils, neutrophil elastase, proteinase 3, visceral adipose tissue, fat browning, beige adipocytes, thermogenesis, UCP1, obesity, sivelestat, IGFBP-3, macrophage polarization

Haematitum occupies an unusual place in the Chinese Materia Medica. Classified as a mineral-based medicine rather than a plant or animal product, it is used clinically as a hemostatic and antiemetic, and classical texts warn that it should not be taken for long stretches. Modern toxicology has largely confirmed those warnings, documenting lung toxicity in both animal models and clinical observations, but the underlying biology has remained murky. Toxicity studies of mineral medicines often stop at the tissue level, leaving open the question of which cells fail first and which molecular signals carry the injury from one organ system to another.

To answer those questions, the researchers established a mouse model of Haematitum-induced lung injury and then interrogated it with three complementary technologies. Sixteen S ribosomal RNA sequencing mapped shifts in the gut bacterial community, untargeted metabolomics catalogued the small molecules accumulating in lung tissue, and single-cell RNA sequencing constructed a comprehensive atlas of the lung’s cellular landscape, capturing the gene-expression signatures of every major cell type simultaneously. This combined approach allowed the team to connect events at three scales at once: the microbial ecosystem of the intestine, the metabolic chemistry of the lung, and the behavior of individual immune cells within it.

The first domino to fall, according to the data, is the intestinal barrier. Mice receiving high-dose Haematitum showed clear disruption of the gut lining, the selective wall of epithelial cells that normally confines the trillions of microbes in the intestine while allowing nutrients to pass. With that wall compromised, the composition of the microbiome shifted dramatically, and the relative abundance of Klebsiella, an opportunistic bacterial genus notorious for its role in hospital-acquired infections, rose sharply. Microbial metabolites that should have remained sealed within the bowel began entering the bloodstream, hitching a ride through the circulation toward distant organs, including the lungs.

Once those metabolites reached the lung, correlation analysis revealed a striking statistical association between gut dysbiosis and disturbances in a single metabolic network: the glycerophospholipid pathway. Glycerophospholipids are the phospholipid building blocks of cellular membranes and the constituents of pulmonary surfactant, the fatty film that keeps the air sacs of the lung from collapsing. Disruption of this pathway implies that the injured lung was not merely inflamed but was also losing the lipid machinery required for structural integrity and normal immune signaling, creating a metabolically destabilized environment in which immune cells were primed to misfire.

The single-cell data then identified the two cell types at the center of the injury: macrophages and neutrophils. Macrophages, the lung’s resident sentinels, normally enforce calm by patrolling the tissue and suppressing excessive inflammation. The sequencing showed that the PPAR signaling pathway in these macrophages had been inhibited. PPAR, or peroxisome proliferator-activated receptor, is a nuclear receptor that regulates lipid metabolism and anti-inflammatory gene programs; when its activity drops, macrophages lose their anti-inflammatory identity. In the Haematitum-exposed mice, the silenced macrophages began releasing inflammatory factors, most notably tumor necrosis factor-alpha, a potent pro-inflammatory cytokine that functions as a broadcast alarm to the rest of the immune system.

TNF-alpha, in this model, acted as the messenger that recruited and reshaped the second cast member. Colocalization experiments confirmed the spatial relationship between macrophages and the cytokine, while the single-cell analysis showed that neutrophils exposed to the signal activated their own TNF signaling pathway. Neutrophils are the immune system’s shock troops, short-lived cells packed with destructive enzymes and reactive chemicals designed to annihilate pathogens. When appropriately activated, they are lifesavers; when triggered inappropriately, they shred healthy tissue. Under the influence of macrophage-derived TNF-alpha, the neutrophils in the injured lungs acquired what the authors describe as a highly destructive phenotype, and the synergy between the two cell types drove both inflammation and apoptosis, or programmed cell death, across the lung tissue.

Crucially, the team did not stop at correlation. By pharmacologically manipulating the axis they had identified, administering a PPAR-gamma agonist to restore the macrophage pathway, or a TNF-alpha inhibitor to block the cytokine signal, they showed that cellular abnormalities could be effectively reversed and lung injury significantly alleviated. That interventional rescue is the strongest evidence that the PPAR-gamma/TNF-alpha axis is not merely a bystander in the toxicity but its functional core. It also immediately suggests a therapeutic strategy: drugs that prop up anti-inflammatory macrophage programs or mop up excess TNF-alpha could, in principle, mitigate the pulmonary side effects of prolonged mineral medicine use.

The study also offered a solution rooted in the tradition itself. Haematitum is classically paired with Inula japonica Thunb., a flowering herb used in combination formulas for respiratory complaints, and the researchers evaluated this pairing in their model. The combination reduced lung toxicity, and computational prediction suggested that components within Inula japonica act as natural PPAR-gamma agonists, effectively replenishing the very pathway that Haematitum suppresses. Meanwhile, mice that received Haematitum at a common clinical dose rather than a high dose avoided the severe cascade altogether, reinforcing the traditional dosing guidance and suggesting that the toxicity is dose-dependent rather than intrinsic at all exposure levels.

Beyond its immediate implications for one traditional medicine, the work carries broader lessons for the toxicology of mineral-based drugs and for the rapidly growing field of gut-lung axis research. It demonstrates that organ toxicity can originate far from the organ that suffers it, with a disrupted intestinal barrier serving as the gateway for circulating microbial metabolites that rewire metabolism and immunity elsewhere in the body. It also provides a template for how single-cell transcriptomics, metabolomics, and microbiome sequencing can be braided together to resolve multi-organ toxicity mechanisms that no single technology could untangle alone. For clinicians and regulators weighing the safety of mineral medicines, the message is concrete: protect the gut, respect the dose, and watch the PPAR-gamma/TNF-alpha axis as a biomarker of trouble ahead. The authors note that these findings advance understanding of mineral medicine toxicology and offer a reference framework for the safe clinical application of traditional Chinese medicines whose ancient warnings, it turns out, described a molecular pathway that modern science has only now begun to read.

Subject of Research: Mechanism of Haematitum-induced lung injury mediated by gut dysbiosis and macrophage-neutrophil crosstalk along the gut-lung axis

Article Title: Single-cell transcriptomics reveals macrophage-neutrophil crosstalk in Haematitum-induced lung injury associated with gut dysbiosis

Article References: Single-cell transcriptomics reveals macrophage-neutrophil crosstalk in Haematitum-induced lung injury associated with gut dysbiosis. (n.d.). https://doi.org/10.1186/s12967-026-08954-w

Image Credits: AI Generated

DOI: 10.1186/s12967-026-08954-w

Keywords: Haematitum, gut-lung axis, gut dysbiosis, Klebsiella, macrophages, neutrophils, TNF-alpha, PPAR signaling, glycerophospholipid metabolism, single-cell RNA sequencing, traditional Chinese medicine, lung injury

Post COVID-19 condition is characterized by persistent and highly heterogeneous symptoms that most prominently affect the cardiopulmonary system, including breathlessness, fatigue, exercise intolerance, and dysautonomia. Despite years of research, the biological mechanisms driving these symptoms remain poorly understood. Previous work has documented immune dysregulation and epigenetic alterations in peripheral blood following acute infection, but the lung itself, the primary site of infection and immune activation, has remained largely unexplored at the epigenetic level in this patient group.

The research team, led by Frida Nikesjö, Kristofer Hedman, and Maria Lerm of Linköping University, recruited 13 patients who had experienced persistent symptoms affecting daily life for more than 12 weeks after COVID-19 in 2020 and 2021. Participants were referred to the Department of Clinical Physiology at Linköping University Hospital, where they provided blood and induced sputum samples at study inclusion and again one year later. Induced sputum has been validated as a reliable and biologically informative source of pulmonary immune cells for methylome analysis, allowing the researchers to isolate neutrophil-enriched and macrophage-enriched cell fractions from the lung environment.

At each visit, patients also completed validated questionnaires covering fatigue, quality of life, and dyspnea, and underwent objective physiological testing including symptom-limited cardiopulmonary exercise testing, dynamic spirometry, and single-breath carbon monoxide diffusion capacity measurement. To reduce dimensionality in this small cohort, the team combined questionnaire scores and physiological outcomes into a single symptom-physiology composite variable, categorizing each measure from normal to severely abnormal using clinical reference limits.

Genome-wide DNA methylation profiling was performed using the Illumina Infinium Methylation EPIC 850K array, with rigorous preprocessing that removed failed and cross-reactive probes, sex chromosome sites, and probes containing common single nucleotide polymorphisms. Cell type proportions were estimated using the EpiDISH reference-based deconvolution method, and longitudinal differential methylation was assessed within individuals using the limma framework, with patient identity as a blocking factor and estimated cell proportions, sex, age, body mass index, and smoking status included as covariates. Differentially methylated CpG sites required both an absolute mean methylation difference greater than 0.15 and a false discovery rate-adjusted p-value below 0.05.

The most striking finding was a sharp divergence between compartments. No significant longitudinal DNA methylation changes were detected in peripheral blood mononuclear cells, yet pronounced changes emerged in both lung-derived fractions. In the neutrophil-enriched fraction, the researchers identified 446 differentially methylated CpG sites between the two time points, 70 hypermethylated and 376 hypomethylated, mapping to 274 unique genes. Pathway enrichment analysis across 334 KEGG pathways revealed 43 significantly enriched processes, with Wnt signalling and circadian entrainment among the most prominent. Notably, 87 of the affected genes are known to interact with SARS-CoV-2 proteins according to the BioGRID database.

In the macrophage-enriched fraction, 34 differentially methylated CpG sites were identified, evenly split between hyper- and hypomethylation. Although these changes did not map significantly to any KEGG pathways, an overlap analysis revealed a single gene, KIAA0930, that was differentially methylated in both lung cell fractions. This gene has been implicated in hypoxia adaptation and lung cancer development, and protein interaction analyses place it at a network hub connected to the 14-3-3 protein family, part of the Reactome pathway describing how SARS-CoV-2 targets host intracellular and regulatory pathways. BioGRID further identifies a direct interaction between KIAA0930 and ORF3A, a viral accessory protein known to modulate immune responses and cellular stress pathways.

Crucially, the epigenetic changes were not merely molecular noise. Seventy differentially methylated CpG sites, mapping to 54 genes, showed changes in methylation that correlated with changes in the symptom-physiology composite variable over the year of follow-up. Seven participants improved symptomatically, three remained stable, and three worsened, and their methylation trajectories tracked these clinical courses. Protein interaction and Gene Ontology analyses of the correlated genes revealed significant enrichment in biological pathways related to cardiac function, including a module connected to the KEGG pathway for viral myocarditis, a finding that resonates with the cardiopulmonary symptoms, such as exercise intolerance and dysautonomia, that dominate the clinical picture of post COVID-19 condition.

The authors are careful to frame the study as exploratory and hypothesis-generating. The cohort of 13 patients is small, control samples from pre-pandemic healthy subjects were used only for contextual reference rather than direct statistical comparison, and the lung cell isolation approach yielded enriched rather than fully homogeneous fractions. Neutrophil proportions were higher at the first time point, and residual confounding from comorbidities or treatments cannot be excluded. Without longitudinally matched controls, age-related or time-dependent methylation changes unrelated to post COVID-19 condition cannot be fully ruled out, and no causal relationship between the epigenetic alterations and symptoms can be inferred from these data.

Nevertheless, the findings carry significant implications. The tissue-specific nature of the rewiring suggests that peripheral blood, the workhorse of most long COVID biomarker studies, may be an incomplete window into the disease process, and that neutrophil biology in particular may persist in an altered state well beyond acute infection, consistent with reports of immature and activated neutrophils, neutrophil extracellular trap formation, and epigenetic reprogramming of bone marrow progenitors after COVID-19. The enrichment of pathways involving AMPK signalling, circadian entrainment, and dopaminergic synapses also aligns intriguingly with recent clinical observations, including evidence that the AMPK activator metformin reduces the incidence of post COVID-19 condition. Larger longitudinal studies with matched controls and mechanistic validation will be needed to determine whether these pulmonary epigenetic signatures are drivers of persistent illness, scars of prior infection, or downstream echoes of physiological stress, but this first longitudinal map of the lung methylome in long COVID provides a clear and testable starting point.

Subject of Research: Longitudinal DNA methylation changes in lung immune cells of patients with post COVID-19 condition

Article Title: Longitudinal epigenetic rewiring in lung immune cells in patients with post COVID-19 condition

Article References: Nikesjö, F., Smiljanić, J., Sayyab, S., Martínez-Enguita, D., Gustafsson, M., Rosvall, M., Hedman, K., & Lerm, M. (2026). Longitudinal epigenetic rewiring in lung immune cells in patients with post COVID-19 condition. Epigenetics Communications, 6(1), Article 5. https://doi.org/10.1186/s43682-026-00046-6

Image Credits: AI Generated

DOI: 10.1186/s43682-026-00046-6

Keywords: post COVID-19 condition, long COVID, DNA methylation, epigenetics, lung immune cells, neutrophils, macrophages, induced sputum, SARS-CoV-2, cardiopulmonary symptoms, KIAA0930, viral myocarditis

The scale of neutrophil involvement in cancer is staggering. Neutrophils are the most numerous circulating leukocytes in humans, produced at a rate of roughly one hundred billion cells per day in the bone marrow, and they can constitute the dominant immune population within many solid tumors. Large-scale analyses of the tumor immune landscape across human cancers have repeatedly found that high intratumoral neutrophil content correlates with poor prognosis in numerous malignancies, including renal cell carcinoma, head and neck cancer and non-small cell lung cancer. The neutrophil-to-lymphocyte ratio, a simple blood measurement, has emerged as one of the most robust prognostic biomarkers in oncology, predicting outcomes across tumor types and even forecasting response to immune checkpoint inhibitors.

Why would the immune system’s first responders become cancer’s accomplices? The answer, the review argues, lies in the extraordinary plasticity of neutrophils and their exquisite sensitivity to environmental cues. Tumors are, in the words of a classic 1986 observation by Harold Dvorak, wounds that do not heal, and neutrophils are the cells that respond to wounds. Cancers exploit the same inflammatory programs that neutrophils deploy during tissue repair. Tumor-derived signals such as granulocyte colony-stimulating factor, transforming growth factor-beta, interleukin-8 and other chemokines reprogram both the production and the function of neutrophils, driving emergency granulopoiesis in the bone marrow and recruiting immature, immunosuppressive granulocytes into the circulation and the tumor bed.

Once inside the tumor microenvironment, neutrophils promote cancer through several mechanistically distinct pathways. They release vascular endothelial growth factor and, critically, matrix metalloproteinase-9, an enzyme that liberates sequestered VEGF from the extracellular matrix and triggers the angiogenic switch that transforms a dormant lesion into a growing tumor. Studies in mouse models of multistage carcinogenesis showed that infiltrating neutrophils mediate this initial angiogenic switch, and human neutrophils are unique in releasing MMP-9 free of its natural inhibitor TIMP-1, making it an especially potent driver of new blood vessel formation. Neutrophil elastase, another granule protease, can degrade insulin receptor substrate-1 in tumor cells to accelerate lung tumor growth, and myeloid cell-derived reactive oxygen species have been shown to induce mutagenesis in adjacent epithelial cells, directly fueling the genomic instability that drives malignant transformation.

Perhaps no neutrophil behavior has attracted more attention in recent years than the formation of neutrophil extracellular traps, or NETs. First described in 2004 as web-like structures of DNA, histones and granule proteins that ensnare bacteria, NETs have since been implicated in a remarkable range of tumor-promoting processes. Recent work published in Nature demonstrated that NETs drive vascular occlusion, tumor necrosis and metastasis, linking phenomena long thought to be independent. NETs can sequester circulating tumor cells, shielding them from cytotoxic lymphocytes and natural killer cells; NET-associated DNA can bind the receptor CCDC25 on cancer cells, directing their migration; and NETs produced during systemic inflammation can awaken dormant cancer cells, triggering metastatic relapse years after primary tumor removal. Strikingly, the metastatic spread of breast cancer has been shown to accelerate during sleep, when rhythmic fluctuations in circulating neutrophils and cancer cell dynamics converge.

Neutrophils also construct the pre-metastatic niche, the distant soil that primary tumors prepare to receive their disseminated seeds. Tumor-derived factors mobilize neutrophils and their progenitors to future metastatic sites, where they suppress natural killer cell activity, remodel the extracellular matrix and create an immunologically permissive environment. In breast cancer models, neutrophils support the lung colonization of metastasis-initiating cells, and chronic stress has been shown to increase metastasis through neutrophil-mediated changes to the microenvironment. Even glucocorticoids, widely used clinically, can promote breast cancer metastasis by acting on these cells. The circadian biology of neutrophils, governed by an intrinsic molecular timer that coordinates immune defense and vascular protection, adds another layer of complexity to how and when these cells enable metastatic spread.

Yet the story is emphatically not one-directional. The review devotes substantial attention to the antitumor capacities of neutrophils, which many of the same molecules can mediate depending on context. Neutrophil elastase, which promotes tumor growth in some settings, has been shown in other contexts to selectively kill cancer cells and attenuate tumorigenesis, with important differences between mouse and human neutrophils in the production of its inhibitor, secretory leukocyte proteinase inhibitor. Activated neutrophils exert direct cytotoxicity against melanoma cells through reactive oxygen species, and tumor-associated neutrophils in early-stage human lung cancer can stimulate T cell responses rather than suppress them. Tumor-entrained neutrophils have even been shown to inhibit metastatic seeding in the lung, providing early evidence of spontaneous antimetastatic function. The pro- versus antitumor polarization of neutrophils, famously framed as N1 versus N2 states, is now understood to reflect a continuum of environmentally determined functional states rather than fixed identities.

This dual nature is precisely what makes neutrophils such compelling therapeutic targets. The review highlights several promising strategies. Neutrophil-activating therapy, developed by the Stanford group, demonstrated that pharmacologically activated neutrophils can eradicate tumors and reduce metastases independently of adaptive immunity. CD40 agonist antibodies recruit a subset of neutrophils associated with tumor control, and T cell immunotherapies have been shown to engage neutrophils to eliminate antigen-escape variants that would otherwise survive checkpoint blockade. Bacille Calmette-Guerin, the century-old tuberculosis vaccine used to treat bladder cancer, works in part by reprogramming hematopoiesis so that neutrophils develop the capacity to attack tumor cells, and interferon-gamma induces NET formation with tumor-killing activity in colorectal cancer. On the inhibitory side, CXCR2 antagonists, peptidyl arginine deiminase 4 inhibitors that block NET formation, arginase inhibitors, and antibodies that block the NET-associated immunosuppressive enzyme arginase-1 are all in clinical development, several in combination with checkpoint inhibitors.

Antibody-based approaches represent another frontier. Neutrophils are extraordinarily potent mediators of antibody-dependent cellular cytotoxicity, and IgA antibodies in particular trigger superior neutrophil-mediated killing of cancer cells compared with conventional IgG, engaging the Fc-alpha receptor to produce vigorous respiratory bursts and trogoptosis, a process in which neutrophils progressively strip membrane fragments from antibody-coated targets. Combining IgA-based therapeutics with blockade of the CD47-SIRP-alpha innate immune checkpoint, which prevents phagocytosis, has shown enhanced neutrophil cytotoxicity against neuroblastoma and other malignancies. Even more ambitiously, researchers have engineered chimeric antigen receptor neutrophils derived from induced pluripotent stem cells, which possess potent activity against solid tumors and can serve as delivery vehicles for tumor-microenvironment-responsive nanodrugs in glioblastoma. Neutrophils bearing adhesive polymer micropatches have been proposed as a drug-free immunotherapy platform.

The authors caution that translating these findings into the clinic requires resolving fundamental questions about neutrophil heterogeneity, nomenclature and species differences. A consensus statement has established standards for myeloid-derived suppressor cell classification, and recent single-cell atlases have mapped neutrophil developmental trajectories across tissues and disease states, revealing that mature and immature neutrophils converge on similar transcriptional signatures within tumors. Human and mouse neutrophils differ in important ways, including their circadian rhythms, granule composition and lifespan, with human neutrophils surviving approximately five days rather than hours as once believed. Nevertheless, the convergence of mechanistic insight, biomarker validation and early clinical activity suggests that the field has reached an inflection point. Neutrophils, long dismissed as terminally differentiated foot soldiers, are now recognized as master regulators of the tumor ecosystem, and learning to command them, rather than simply deplete them, may define the next era of cancer immunotherapy.

Subject of Research: The roles of neutrophils in tumor progression, immunosuppression, metastasis and cancer therapy

Article Title: Neutrophils in cancer

Article References: Diehl, M. I., Basto, P. A., Abikenari, M. A., Linde, I. L., Okwan-Duodu, D., & Engleman, E. G. (2026). Neutrophils in cancer. Nature Reviews Cancer. https://doi.org/10.1038/s41568-026-00968-2

Image Credits: AI Generated

DOI: 10.1038/s41568-026-00968-2

Keywords: neutrophils, cancer, tumor microenvironment, neutrophil extracellular traps, metastasis, immunosuppression, angiogenesis, tumor-associated neutrophils, immunotherapy, myeloid-derived suppressor cells, NETosis, granulopoiesis

Adipose tissue in mammals is broadly divided into subcutaneous depots, found under the skin, and visceral depots, which pad the abdominal organs. Although both store energy in the form of lipid droplets, they differ dramatically in their behavior and their consequences for health. Subcutaneous fat is comparatively benign and can undergo thermogenic remodeling, a process in which ordinary white adipocytes acquire features of brown fat cells, becoming packed with mitochondria that burn fuel to produce heat. Visceral fat, by contrast, resists this transformation, known as beiging, and instead tends to enlarge, release fatty acids into the portal circulation, and secrete inflammatory signals that promote insulin resistance. Why visceral fat refuses to beige has long been an open question.

The concept of beiging itself has a rich experimental history. Work from several laboratories over the past two decades, including studies by Rosenwald and colleagues and by Chitraju and colleagues, established that cold exposure and sympathetic nervous system activation recruit new adipocyte precursors in subcutaneous fat that differentiate into thermogenically competent beige adipocytes. Drugs such as beta-adrenergic agonists can induce similar remodeling. Yet when researchers apply the same stimuli to visceral depots, the response is muted or absent. Yuan and colleagues set out to identify what actively enforces this depot specificity, suspecting that the local tissue microenvironment, rather than an intrinsic defect in visceral adipocyte precursors, might be responsible.

The investigative trail led the researchers to neutrophils, the most abundant white blood cells in the human body and classic first responders to infection. Neutrophils are armed with an arsenal of serine proteases, including neutrophil elastase, proteinase 3, and cathepsin G, which they normally deploy to destroy pathogens and remodel extracellular matrix. Earlier work had already implicated neutrophil enzymes in metabolic regulation: Talukdar and colleagues showed in 2012 that neutrophil elastase deficiency protects mice from obesity-associated insulin resistance, and Mansuy-Aubert and colleagues demonstrated in 2013 that neutrophils modulate insulin sensitivity in adipose tissue. What remained unknown was whether these proteases could gate a specific developmental program within fat tissue.

Yuan and colleagues now show that they can. In their model, serine proteases released by neutrophils that reside in or traffic to visceral fat cleave key signaling components required for the beiging program, effectively putting the brakes on thermogenic differentiation before it can begin. When the researchers depleted neutrophils or blocked their proteases, visceral adipose tissue regained some capacity for beiging, acquiring multilocular lipid droplets, elevated mitochondrial content, and increased expression of thermogenic genes. The effect was depot-specific: subcutaneous fat, which hosts fewer of these protease-releasing neutrophils under resting conditions, was largely unaffected, providing a mechanistic explanation for the natural dichotomy between the two depots.

The technical logic of the study is notable for the way it integrates cellular, molecular, and physiological levels of analysis. Single-cell and population-level transcriptomic profiling allowed the authors to map the immune composition of visceral versus subcutaneous depots and to quantify the enrichment of neutrophil signatures and protease transcripts in visceral fat. Genetic and pharmacological perturbations, including protease-deficient models and pharmacologic inhibitors of the sort previously characterized by Korkmaz and colleagues in their comprehensive pharmacological reviews of neutrophil serine proteases, established causality rather than mere correlation. Functional readouts of thermogenesis, including respiratory measurements and gene expression panels anchored on canonical markers such as Ucp1, confirmed that the histological and molecular shifts translated into genuine changes in adipose tissue function.

Why would the body actively suppress heat production in its visceral fat? The authors and the commentary authors offer several evolutionary and physiological interpretations. Thermogenesis is metabolically expensive, and skeletal and cardiac muscle plus brown fat already serve as principal heat-generating organs during cold defense. Restricting beiging to subcutaneous depots may allow the body to preserve the mechanical and structural integrity of visceral fat, which cushions organs, while avoiding the wasteful combustion of a fuel depot located in the abdominal cavity. At the same time, neutrophils are recruited in greater numbers to visceral fat during obesity, as demonstrated classically by Weisberg and Xu and their colleagues in 2003, suggesting that a system designed to restrain thermogenesis in lean animals may become maladaptive when inflammation drives excessive neutrophil accumulation and further locks visceral fat into an metabolically unfavorable state.

The translational implications are considerable. Pharmacological strategies to induce beiging have struggled precisely because systemically administered thermogenic stimuli produce off-target effects, particularly on the cardiovascular system, through beta-adrenergic activation. A pathway that actively suppresses beiging in one specific depot offers an alternative therapeutic logic: relieve the brake rather than press the accelerator. If neutrophil serine protease activity in visceral fat could be selectively inhibited, patients with obesity or type 2 diabetes might regain some of the thermogenic and insulin-sensitizing capacity that their subcutaneous fat already possesses. Protease inhibitors exist for related enzymes, and neutrophil elastase inhibitors have been tested in inflammatory lung disease, providing a medicinal chemistry starting point, although the challenge of targeting protease activity specifically within visceral adipose tissue without impairing antimicrobial immunity remains substantial.

The study also carries conceptual weight for immunometabolism as a field. Over the past two decades, adipose tissue macrophages and T cells have been established as central players in obesity-associated inflammation, following foundational observations linking immune infiltration to metabolic dysfunction in fat. Neutrophils, by contrast, were long treated as short-lived, terminally differentiated cells with narrow antimicrobial functions. The new work joins a growing body of evidence, including the 2026 study by Son and colleagues in Nature on neutrophil heterogeneity, that neutrophils are functionally versatile cells whose granule contents can reprogram the behavior of surrounding tissues. Tol and Stienstra emphasize in their commentary that the identification of protease-gated depot specificity fundamentally reframes neutrophils as custodians of adipose tissue identity, not merely as inflammatory mercenaries.

Important questions remain. The precise molecular targets of the proteases within the beiging pathway, whether they act on adipocyte precursors directly, on extracellular matrix cues, or on paracrine signals from other stromal cells, will require further dissection. It is also unclear whether chronic pharmacological inhibition of these enzymes in adult animals produces durable, safe increases in visceral thermogenesis, or whether the brake exists to prevent pathology of its own. Human relevance, as always in mouse-first immunometabolism, must be established: visceral fat biopsies from people with varying degrees of obesity and metabolic health could test whether neutrophil protease abundance correlates with impaired beiging capacity in our own species. Nevertheless, by identifying a concrete, druggable class of enzymes that explains why visceral fat refuses to become a furnace, Yuan and colleagues have converted a long-standing observational puzzle into a tractable therapeutic opportunity, and have added an unexpected chapter to the story of how the immune system writes the metabolic rules of our bodies.

Subject of Research: Depot-specific suppression of visceral fat beiging by neutrophil-derived serine proteases

Article Title: Neutrophil proteases put the brakes on visceral beiging

Article References: Tol, M. J., & Stienstra, R. (2026). Neutrophil proteases put the brakes on visceral beiging. Nature Metabolism. https://doi.org/10.1038/s42255-026-01606-9

Image Credits: AI Generated

DOI: 10.1038/s42255-026-01606-9

Keywords: neutrophils, serine proteases, visceral adipose tissue, beiging, thermogenesis, immunometabolism, obesity, insulin resistance, adipose tissue plasticity, innate immune cells, metabolism, Neutrophil