Antioxidants

Dehydroascorbic acid (DHA), the oxidized form of vitamin C, exhibits specific toxicity against KRAS-mutant cancer cells; however, the early metabolic reprogramming mechanisms leading to cell death remain incompletely understood. In this study, we reveal the non-linear, dose-dependent response of the intracellular metabolome during the ultra-early phase of 1-hour DHA exposure. Under 1 mM DHA exposure, an early significant accumulation of the primary catabolite erythrulose (p = 0.030) and moderate consumption of glutamate (p = 0.0086) were observed, while core TCA cycle homeostasis and cell viability were preserved. In contrast, under 10 mM DHA exposure, an acute and profound alteration of the metabolic profile was observed. Along with the significant accumulation of glycerate, indicative of a glycolytic blockade, and the terminal peroxidation product oxalate, core TCA cycle intermediates such as -ketoglutarate and malate showed rapid depletion (Log2FC < -2.0, p < 10-7). Furthermore, coupled with this acute energy depletion, a statistically significant accumulation of free methionine (Log2FC = 1.14, p = 0.011), which was below the limit of detection in the control, was identified alongside profound depletions of glutamate (p < 0.001) and cysteine (p = 0.0027). These results strongly suggest that the initial response to high-dose DHA is not merely a linear accumulation of oxidative stress, but rather an "abrupt metabolic switch" characterized by rapid TCA cycle dysfunction followed by the early signature of a methionine trap.

All-trans-retinal (atRAL) is a photoreactive aldehyde generated during visual pigment regeneration, and impaired atRAL clearance contributes to oxidative stress and retinal degeneration. Retinol dehydrogenase 12 (RDH12) reduces atRAL to all-trans-retinol, yet the temporal mechanisms linking its upstream enzymatic activity to downstream cellular stress adaptations remain poorly defined. Here, we utilized stable RDH12-expressing HEK293T cells to match proteomic and lipidomic profiles and performed cell viability assays to map the transition from acute atRAL stress to cellular recovery. RDH12 expression increased cellular tolerance to retinaldehyde-induced cytotoxicity. Acute atRAL exposure engaged the supply arm of the KEAP1-NRF2 program with increased HMOX1, SLC7A11, GCLC, MGST2, and MGST3, while the terminal glutathione peroxidase arm declined. Acute exposure was accompanied by membrane remodeling, indicated by increased glycerophospholipid enzyme abundance and increased stress-signaling ceramides and lysophosphatidylcholines. Concurrently, acute stress induced upregulation of the transferrin receptor (TFRC) and SLC11A2, which influence intracellular iron flux and enable Fenton chemistry that can lead to oxidative stress. During recovery, RDH12-expressing cells exhibited a distinct post-atRAL molecular state characterized by increased abundance of phosphatidylcholines (PCs) and ether-linked PCs, and proteome changes associated with cytoskeletal organization and antioxidant processes. Furthermore, we performed a pharmacological rescue with Ferrostatin-1, which indicated that atRAL-induced cytotoxicity in RDH12-expressing cells is dependent, in part, on lipid radical propagation and lipid peroxidation, supporting ferroptosis-regulated cell death. Collectively, the multiomics and biological findings establish a novel temporal sequence for retinaldehyde toxicity, showing that RDH12 is a critical component of upstream metabolic defense for acute aldehyde clearance, late-stage lipid detoxification, and adaptive membrane lipid homeostasis.

Background: Selenium is a vital trace element involved in antioxidant defence and cardiovascular health. Although selenium deficiency is implicated in cardiomyopathies, its early cardiac effects and underlying mechanisms remain poorly defined. Methods: C57BL6/Njr mice were fed either a selenium deficient or control diet for 12 weeks. Systemic selenium status, cardiac function by echocardiography, left ventricular (LV) transcriptomic profiles, redox balance, and circadian pathway markers were assessed, including sex-specific analyses. Results: Selenium deficiency reduced plasma selenium levels without inducing overt cardiac hypertrophy or fibrosis. Echocardiography showed preserved ejection fraction and fractional shortening but reduced global longitudinal strain, indicating early systolic dysfunction. Cardiac stress markers were increased predominantly in male mice. Left ventricular RNA sequencing revealed enrichment of pathways related to cardiac remodelling, redox regulation, mitochondrial function, and circadian rhythm. Additional protein and metabolic analyses supported sex-specific redox circadian alterations, with males showing a more pronounced stress response profile. Conclusions: Dietary selenium deficiency induces early myocardial dysfunction and molecular remodelling before overt cardiac failure. These changes are associated with redox and circadian pathway disruption and show sex specific features, suggesting that selenium contributes to cardiac homeostasis through sex dependent redox circadian regulation.

Purpose. Neuroblastoma is the most common malignancy of infancy, and cancer cells strongly depend on iron metabolism for proliferation. Whether sub-cytotoxic iron load reprograms mitochondrial and redox metabolism, and how this relates to the malignant behavior of neuroblastoma cells, is poorly defined. We hypothesized that exposure of human neuroblastoma cells to a non-toxic iron overload perturbs mitochondrial and redox metabolism, thereby affecting cancer cell properties. Methods. SH-SY5Y neuroblastoma cells were exposed to 100 M iron sulfate for 24 h. The resulting changes were monitored using complementary methods, including cell viability, cytotoxicity, proliferation and migration assays, intracellular iron quantification by ICP-MS, confocal imaging of mitochondrial morphology and membrane potential ({Delta}{Psi}m), high-resolution respirometry with flux control ratios, probe-based oxidant and H2O2 measurements, and label-free quantitative proteomics with Ingenuity Pathway Analysis. Results. Non-toxic iron loading raised intracellular iron about four-fold, promoted cell proliferation and reduced migration. Iron induced mitochondrial fragmentation and {Delta}{Psi}m depolarization while preserving mitochondrial content and OXPHOS coupling efficiency. Among respiratory states, only proton-leak respiration increased, paralleled by a higher leak/ETS coupling ratio. Total cellular oxidant levels and H2O2 output were strongly reduced. The proteome showed downregulation of ribosomal proteins and translation/RNA-processing components and upregulation of histones and ferritin. Conclusion. Mild iron exposure reprograms mitochondrial and redox metabolism in neuroblastoma cells. The observed selective increase in proton leak lowers {Delta}{Psi}m to a range that biophysically limits oxidant production while OXPHOS coupling is preserved. Interfering with this adaptive, proton leak-dependent and preventive antioxidant program may offer a way to alter neuroblastoma progression.

Purpose: Age is the leading factor for age-related macular degeneration (AMD), in which retinal pigmented epithelium (RPE) atrophy is a hallmark. The nuclear factor-erythroid 2-related factor 2 (Nrf2), a major anti-stress transcription factor, decreases in AMD, suggesting bioenergetic stress interacts with age during AMD pathogenesis. We profiled visual function and gene expression of the retina and RPE-choroid with Nrf2 deletion and aging. Methods: We tested 3mo and 14mo Nrf2 null (Nrf2 KO) and Nrf2 WT mice for optokinetic tracking (OKT) and dark-adapted electroretinography (ERG) responses. Eyes were harvested for retina outer nuclear layer (ONL) thickness analysis and retina and RPE-choroid cup RNA isolation for RNAseq profiling. Results: Visual acuity was reduced with aging with lower values in the Nrf2 KO vs Nrf2 WT comparison at 14mo. We observed aged-related reduction of a-, b-, and c-wave ERG amplitudes in both WT and KO mice. Age-related c-wave decline was exacerbated by Nrf2 loss. By RNAseq, two-way ANOVA of RPE-choroid samples revealed differentially expressed genes (DEGs) with age and genotype main effects, as well as DEGs with age and genotype interaction effects. Age DEGs were over-represented in pathways related to inflammation and phagocytosis. Genotype DEGs were associated with alterations in antioxidant and inflammatory processes. Retina RNAseq showed age and genotype DEGs. Conclusions: Ablation of Nrf2 exacerbates age-related declines suggesting that decrease in Nrf2 with aging has functional consequences for inflammation/resiliency. We provide retina and RPE-choroid bulk-RNAseq datasets from the same cohort of mice that can be interrogated to better understand degeneration of retina/RPE-choroid.

Background/Objectives: Aldehyde dehydrogenase 2 (ALDH2), a mitochondrial enzyme, mitigates cellular stress by detoxifying reactive aldehydes produced during alcohol exposure and endogenous metabolic processes. ALDH2*2 polymorphism, which results in deficient catalytic activity, is prevalent in East Asian populations and is associated with an increased risk of cancer and other diseases. While the effects of ALDH2 deficiency on cellular stress responses are well documented, the specific metabolic dysregulations arising from this deficiency require further investigation. Methods; An ALDH2 knockout subline of SKBR-3 cells was established using CRISPR/Cas9 strategy. The metabolomic profiles of control (SKBR-3/C) and ALDH2 knockout (SKBR-3/ADKO) cells were evaluated via ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS). Results: ALDH2 knockout in SKBR-3 cells resulted in increased cellular stress, evidenced by elevated levels of 8-OHdG, reactive oxygen species (ROS), and malondialdehyde (MDA). Metabolomic analysis of the paired cell lines assigned a total of 5,033 signals, of which 281 were significantly different (fold change [&ge;] 2, p-value <0.05) between the two groups. Pathway analysis with MetaboAnalyst identified significant metabolic pathways associated with ALDH2 deficiency, particularly those involving arginine biosynthesis, and arginine and proline metabolism. ALDH2 deficiency reprogramed arginine metabolism toward polyamine pathways while suppressing the urea cycle. Network analysis further revealed alterations in amino acid and lipid metabolism in ALDH2-deficient cells. Conclusions; This study provides a novel insight into the role of ALDH2 in cancer metabolism and may have broader implication for cancer biology.

Purpose: The neural retina and retinal pigment epithelium/choroid (RPE/Cho) are metabolically coupled. Metabolic dysfunction of the RPE/Cho contributes to photoreceptor death in age-related macular degeneration (AMD). This study aimed to determine how aging, a major risk factor for AMD, alters the proteome and metabolic pathways in the retina and RPE/Cho. Methods: We performed quantitative proteomics on neural retina and RPE/Cho from young (8-week) and old (73-week) C57BL/6J mice. The differentially expressed proteins between old and young, as well as between the retina and RPE/Cho, were visualized using volcano plots and heatmaps, and functional analyses were assessed by Gene Ontology enrichment tools. Results: Aging altered the expression of 85 retinal proteins and 272 RPE/Cho, with 16 shared between tissues. In the aged retina, proteins associated with NADP(H) metabolism, neurodegeneration, and immunity were mostly upregulated, while proteins in lipid metabolism, transcription, and epigenetic regulation decreased. In the aged RPE/Cho, all 21 significantly altered lysosomal enzymes and transport proteins increased, together with complement components, and photoreceptor outer segment proteins. These changes accompanied increases in proteins associated with lipid metabolism and protection against lipid peroxidation, while several glutathione metabolism enzymes decreased. Seven shared proteins involved in lipid and NADP(H) metabolism, changed in opposite directions between retina and RPE/Cho. Comparison of the retinal and RPE/Cho proteomes identified 3073 differentially abundant proteins, of which 2452 maintained tissue-specific differences across both age groups, while approximately 17% showed age-dependent shifts in tissue enrichment. These shifts involved proteins associated with metabolism, extracellular matrix, visual function, lysosomal pathways, and innate immunity. Within the metabolic proteome, several glycolytic and fatty acid oxidation proteins showed greater relative enrichment in RPE/Cho with age, whereas glucose transporters and mitochondrial complexes shifted toward the retina. Conclusions: Overall, these findings show that aging differentially remodels the retina and RPE/Cho proteome, accompanied by altered metabolic specialization between the two tissues.

BackgroundReactive oxygen species (ROS) overproduction, inflammatory cytokines, and plasma mediators disrupt alveolar tight junction integrity and perpetuate oxidative injury in acute respiratory distress syndrome (ARDS). Biological heterogeneity of ARDS, reflected by hyper- and hypoinflammatory subphenotypes with distinct plasma mediator profiles, may contribute to heterogeneity of treatment effect. Stem cell-derived EVs have been shown to exert regenerative and immunomodulatory effects by horizontal transfer of proteins, lipids and genetic material to injured target cells. This study investigated whether extracellular vesicles derived from bone marrow (MSC-EVs) and adipose tissue (ASC-EVs) mesenchymal stem cells restore barrier integrity and redox homeostasis, and whether efficacy differs across subphenotypes. MethodsBronchial epithelial cells (BEAS-2B), microvascular endothelial cells (HMEC-1), and small airway epithelial cells (SAEC) were challenged with plasma from patients with hyperinflammatory or hypoinflammatory ARDS subphenotypes, including those treated with venovenous ECMO. MSC-EVs or ASC-EVs were added concomitantly with plasma exposure or six hours later, at a dose of 5,000 particles/cell. After 24 h, the expression of actin and tight junction proteins, zonula occludens (ZO)-1, occludin, and vascular endothelial (VE)-cadherin, was evaluated by immunofluorescence. Oxidative stress parameters, antioxidant defenses, and antioxidant enzyme activities, were measured. ResultsPlasma from patients with the hyperinflammatory ARDS subphenotype induced marked disruption of ZO-1, occludin, and VE-cadherin expression, together with actin cytoskeletal rearrangement, across BEAS-2B, HMEC-1, and SAEC cells. Barrier disruption was accompanied by increased oxidative stress markers and altered antioxidant enzyme activity. Both MSC-EVs and ASC-EVs restored tight junction protein expression and cytoskeletal organization when administered either concurrently with ARDS plasma or 6 hours after exposure, and both effectively modulated redox parameters. Delayed administration 6 hours after injury produced greater effects for several oxidative stress endpoints, particularly in cells challenged with hypoinflammatory plasma. ConclusionARDS-associated plasma mediators induce subphenotype-dependent impairment of epithelial-endothelial barrier integrity through oxidative mechanisms. Both MSC-EVs and ASC-EVs mitigate this injury, with efficacy that varies according to ARDS subphenotype and timing of administration.

Background: Alpha-mannosidosis (AM) is a debilitating lysosomal storage disorder (LSD) caused by insufficient activity of alpha-mannosidase, an enzyme responsible for cleavage of alpha-linked mannose residues from N-glycan-type oligosaccharides during their degradation. As a result, specific oligosaccharides accumulate in tissues and are also detectable in body fluids. AM is a progressive multi-organ disease for which hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT) are therapeutic options, however, treatment results depend considerably on early diagnosis. Therefore, inclusion of AM into newborn screening panels would significantly contribute to improving therapeutic outcome. Methods: A rapid and fully quantitative method for the specific AM oligosaccharide biomarker Man2GlcNAc in dried blood spots (DBS) using ultra-performance liquid chromatography coupled to tandem-mass spectrometry was developed. DBS from 420 controls, 27 AM patients (including five newborn screening samples), and 35 patients with other LSDs were analyzed. Results: A distinct separation in biomarker concentrations was observed between unaffected individuals and untreated AM patients (0.1 - 0.8 vs 3.2 - 11.3 mol Man2GlcNAc/L, p<0.0001). Furthermore, Man2GlcNAc concentrations significantly differed between untreated patients and those on ERT (n = 17, p<0.0001) or after HSCT (n = 15, p<0.0001), and between both treatment groups (p<0.0001). Moreover, we demonstrated that this method is appropriate for monitoring treatment efficacy by analysis of samples from individual patients before and after initiation of therapy. We retrospectively analyzed residual samples of dried blood spots (DBS) from routine newborn screening that had been stored from patients with later-confirmed AM, which resulted in clear separation from the concentrations observed in a newborn screening control cohort (7.7 - 11.3 vs 0.1 - 0.8 mol Man2GlcNAc/L, p=0.0001). Conclusion: We present a simple and rapid method for quantitative analysis of the specific AM oligosaccharide biomarker Man2GlcNAc, which is remarkably stable compared to enzymatic assays. Thus, the method is useful for selective screening in suspected cases as well as for monitoring the response to different forms of treatment. Furthermore, Man2GlcNAc has the potential to serve as a useful biomarker for newborn screening offering the prospect of earlier treatment initiation, improved therapeutic outcome and higher quality of life for AM patients.

Mitochondrial transplantation has recently emerged as an alternative treatment for cardiovascular disease (CVD), aimed at increasing mitochondrial number and improving mitochondrial function. Though mitochondrial dysfunction is a key factor in the development of right ventricular hypertrophy/failure, the effects of mitochondrial transplantation on disease mitigation have been largely unexplored. Therefore, this in vitro study aimed to determine whether the transplantation of exogenous L6 myotube mitochondria mitigates negative outcomes in H9C2 cardiomyocytes that were stimulated to hypertrophy with phenylephrine. Control (CTL), control with mitochondrial transplantation (MitoTx), Phenylephrine only (Phe-only), and phenylephrine with mitochondrial transplantation (Phe+MitoTx) treatments were evaluated. Pilot experiments indicated mitochondrial transplantation into healthy cardiomyocytes acutely increased Complex I-linked oxidative phosphorylation (OXPHOS) capacity (p=0.005) and maximal respiratory capacity (p=0.022) within 24 hours, and these data alongside microscopic evidence of fluorescently labeled L6 mitochondria in H9C2 cardiomyocytes suggested successful transplantation. Regarding treatment comparisons, Phe-only showed a significant increase in cell area (p<0.05), while Phe+MitoTx blunted the hypertrophic cardiomyocyte response. Consistent with these results, proteomic analysis of 4,806 proteins showed that transplantation enriched the mitochondrial proteome, impacting pathways including OXPHOS, respiration, fatty acid and amino acid metabolism, while suppressing extracellular matrix remodeling and de-differentiation signatures. This response was observed in healthy and phenylephrine-stressed cardiomyocytes. In conclusion, our in vitro data indicates that transplantation of L6 skeletal muscle mitochondria mitigates negative effects induced by phenylephrine in H9C2 cardiomyocytes. However, more rigorous in vivo studies are needed to determine if this is a suitable approach for disease mitigation.

Acute respiratory distress syndrome (ARDS) is marked by severe pulmonary edema and concomitant hypoxia, affecting hundreds of thousands of people a year, especially those in critical care conditions or suffering from septic shock. Previous studies have implicated that the ketogenic diet, a high-fat and low-carbohydrate diet, modulates inflammatory responses. However, the impact of the ketogenic diet on septic ARDS outcomes is unknown. Here, we demonstrated that mice on a ketogenic diet showed strikingly reduced lung injury and inflammation compared to those on a control diet during a murine model of endotoxin-induced lung injury, induced by intratracheal lipopolysaccharide (LPS) injection. Immune mass cytometry studies on lung tissue indicated that the ketogenic diet reduces immune cell infiltration. Treating mice with beta-hydroxybutyrate (BHB), the primary metabolite of ketogenesis, after the onset of ARDS reduced pulmonary edema and lung inflammation, as well as NF-kB activity, suggesting strong therapeutic potential. By multiplex analysis in bronchial alveolar lavage fluid, we observed that the ketogenic diet or BHB administration attenuates the chemotaxis and activation of immune cells. Altogether, our findings reveal that the ketogenic diet provides lung protection during endotoxin-induced lung injury through BHB.

The cornea is the outermost layer of the eye, most vulnerable to injury including from chemical exposure, either environmental, industrial or chemical weapons. For example, exposure of the eye to sulfur mustard (SM) can cause mustard gas keratopathy, resulting in devastating consequences for vision. Available treatments for corneal mustard keratopathy are either ineffective, or if used for a prolonged time, have deleterious side effects. Here, we aimed to harness the anti-inflammatory and anti-angiogenic peptide angiotensin-(1-7), known as Ang-(1-7), that is derived from the renin-angiotensin system (RAS). We designed and developed a protein-like polymer (PLP) displaying a brush of norleucine modified Ang (1-7) peptides (NLE Ang (1-7) PLP), which is a more potent derivative of Ang-(1-7), for administration as an eye drop. In a mouse model of nitrogen mustard (NM)-induced corneal injury, topical treatment and intraperitoneal (i.p.) injection of NLE Ang (1-7) PLP persistently minimized: (i) corneal haze; (ii) edema; (iii), expression of pro-inflammatory and pro-angiogenic genes; and (iv) neovascularization and conjunctivalization as evidenced after a prolonged treatment and recovery period. Collectively, our observations have demonstrated the efficacy of this novel polymer proteomimetic based eye drop treatment in reducing chemical agent-induced corneal injury as well as indicating its potential application in other ocular surface diseases associated with inflammation and angiogenesis.

Phenylketonuria (PKU) is an autosomal recessive disorder caused by PAH gene defects and can cause irreversible neurological damage as early as the fetal period; however, non-invasive prenatal monitoring methods are lacking. In this study, Pah+/- female mice were mated with Pah+/-; male mice and wild-type male mice, respectively. Urine samples were collected longitudinally from pregnant mice at 10 time points during gestation from Day 1 to Day 19. Data-independent acquisition (DIA) quantitative proteomics combined with GO/KEGG analysis, WGCNA, and a dual-strategy LASSO-random forest approach was used to screen candidate biomarkers. The results showed that stable differentially expressed proteins between groups were detectable as early as Day 1, and the differences persisted throughout gestation and exhibited temporal dynamics. Permutation tests indicated that the probability of random generation of the differential protein combination was low (0.04-0.06), suggesting that it was not randomly generated. The intersection of the two strategies yielded five proteins, GINM1, PRG4, LY6A, NTM, and YIPF3, and after including GLO1, a total of six candidate biomarkers were obtained. The candidate proteins had interaction or co-expression associations with 14 proteins involved in PKU mechanisms, with GLO1 serving as a network hub. This study found that the maternal urine proteome can non-invasively reflect the systemic response induced by fetal-origin PKU, providing proof of concept and candidate biomarker resources for non-invasive early-pregnancy screening of PKU.

Opening of the mitochondrial permeability transition (PT) pore is an important step in necrotic cell death in various pathologic conditions such as ischemia-reperfusion injury. Methylglyoxal (MGO) is a byproduct of glycolysis that covalently modifies proteins (i.e., glycation) and is widely regarded as toxic (glycative stress), contributing to the pathology of diabetes. Paradoxically, MGO has been shown to inhibit PT pore opening, but the mechanism of this effect is poorly understood. Herein we show that glycation is elevated in various cardioprotective scenarios. Furthermore, building on a serendipitous finding of the ability of phosphate to block MGO's effect on the PT pore, we used proteomics to map potential sites mediating this effect. From this analysis, mitochondrial creatine kinase (CK) emerged as a phosphate-sensitive MGO target with links to the PT pore. Although MGO inhibited CK activity, this did not appear to be important for its effect on the PT pore. Rather, MGO modified sites on CK that are important for its membrane binding, which likely mediates the combined effects of MGO and phosphate on the PT pore. Furthermore, a consensus sequence for MGO modifications in mitochondria is reported.

Palladium (Pd), a technology critical platinum group metal, is increasingly lost to the environment through anthropogenic activity, yet the molecular basis of Pd uptake and tolerance in plants remains poorly understood. Here, we examine the role of the Arabidopsis thaliana (Arabidopsis) COPT2 copper transporter in Pd transport and plant stress responses. Expression of COPT2 in Saccharomyces cerevisiae conferred Pd sensitivity, indicating a capability for Pd transport. Arabidopsis copt2 loss-of-function mutants accumulated less Pd in shoots and exhibited reduced reactive oxygen species (ROS) production, supporting a direct role for COPT2 in Pd distribution and associated oxidative stress. Our subsequent transcriptome profiling revealed extensive changes under Pd exposure, including downregulation of HMA2 and aquaporins, and upregulation of HMA7, glutathione transferases, and glutamine synthetase GLN1;1, consistent with the activation of metal detoxification and redox homeostasis pathways. Together, these findings identify COPT2 as a key transport protein mediating the uptake of Pd in Arabidopsis and suggest that Pd induces similar detoxification mechanisms as zinc (Zn), copper (Cu) and cadmium (Cd), providing a foundation for engineering plants for precious metal recovery.

Importance: Phosphorylated tau at threonine 217 (p-tau217) and brain-derived tau (BD-tau) are increasingly used as blood biomarkers of Alzheimer's disease (AD) and related neurological disorders. However, the distributions and biological correlates of elevated plasma p-tau217 and BD-tau in plasma from individuals eligible for blood donation remain unclear. Objective: To estimate the proportions of plasma p-tau217 and BD-tau exceeding exploratory study-specific thresholds, and examine associated inflammatory and transcriptomic features. Design: Cross-sectional study. Setting: Hospital blood bank. Participants: 257 de-identified donor samples were obtained between September 2025 and June 2026. Plasma samples from 30 population reference participants and 20 AD patients were used to derive study-specific thresholds. Complementary transcriptomic analyses were performed in 29 fresh whole blood samples. Main Outcomes and Measures: The primary outcome was the proportion of donor samples exceeding the study-specific ROC-derived Youden threshold. The proportion exceeding the prespecified published p-tau217 threshold was the secondary outcome. Other measures included plasma concentrations of BD-tau, tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6); correlations among plasma p-tau217, BD-tau and inflammatory cytokines; and associated transcriptomic alterations. Results: Plasma p-tau217 concentrations exceeded the study-specific ROC-derived Youden threshold in 53 of 256 donor samples (21%; 95% CI, 16%-26%) and the published threshold, used for a secondary comparison, in 99 of 256 samples (39%; 95% CI, 33%-45%). Plasma BD-tau concentrations exceeded the study-specific threshold in 89 of 257 samples (35%; 95% CI, 29%-41%). Plasma p-tau217 concentrations were positively associated with plasma TNF-alpha (Kendall's tau = 0.339; P < .001) and IL-6 (Kendall's tau = 0.310; P < .001) concentrations. Exploratory transcriptomic analyses identified gene expression patterns associated with p-tau217 concentrations. Measurement using a second p-tau217 antibody showed the similar findings. Conclusions and Relevance: Plasma p-tau217 and BD-tau concentrations exceeded exploratory study-specific thresholds in a subset of blood-donor samples, and higher p-tau217 concentrations were associated with inflammatory biomarkers and exploratory transcriptomic differences. These findings raise the possibility of elevated circulating tau species in some blood donors, but their clinical significance requires confirmation. Whether elevated circulating p-tau217 in donated blood has biological consequences for transfusion recipients is unknown, but deserves investigation.

Computational safety evaluation of phytochemical libraries commonly relies on models trained on experimentally tested compounds and applied to much larger and chemically diverse collections. An important but often overlooked question is whether predicted compounds are adequately represented within the experimental chemical space underlying these models. Here, we examined this question for the Indian Medicinal Plants, Phytochemistry and Therapeutics (IMPPAT) database using experimentally characterized datasets for three anti-target endpoints: hERG blockade, cytochrome P450 (CYP) inhibition, and pregnane X receptor (PXR) induction. After structure standardization, 14,956 unique IMPPAT compounds were compared with 8,877 hERG, 4,905 CYP, and 4,138 PXR reference compounds using consensus nearest-neighbor similarity based on Morgan and atom-pair fingerprints. At a Tanimoto similarity threshold of 0.80, only 0.92%, 0.30%, and 0.46% of IMPPAT compounds had close measured analogs in the hERG, CYP, and PXR datasets, respectively. Relative to the internal nearest-neighbor distributions of the reference datasets, a typical IMPPAT compound lay near the 1st percentile, indicating substantial chemical-space separation. Compounds with close experimental analogs also showed distinct molecular characteristics, with descriptor-based logistic regression yielding cross-validated AUC values of 0.77-0.80. Plant-level enrichment was markedly reduced after excluding widely distributed metabolites and was further restricted when the nearest measured analog was required to have pIC50 or pEC50 [&ge;] 5. The remaining signals were concentrated in a limited number of taxa, including Rauvolfia, Sinopodophyllum/Dysosma, Cinchona, and Catharanthus roseus. Overall, most IMPPAT phytochemicals lack close structural representation among currently measured anti-target compounds. Computational safety predictions for these molecules should therefore be interpreted as extrapolations and accompanied by explicit measures of structural support. Absence of a close experimental analog should be regarded as a gap in available evidence rather than evidence of safety.

The human host defence peptide LL-37 mediates pleiotropic immunomodulatory functions that can be both pro- and anti-inflammatory. Under inflammatory conditions in the lungs, LL-37 is susceptible to the post-translational modification (PTM) citrullination. The impact of this PTM on LL-37's immunomodulatory functions is not fully understood. Therefore, we characterized the transcriptome and cytokine profile in response to LL-37 and citrullinated-LL-37 (citLL-37), in human bronchial epithelial cells (HBEC). Cells were stimulated with either LL-37 or citLL-37 (0.5 M), or a scrambled peptide (sLL-37). RNA after 4 hours (h) was analyzed with NanoString nCounter Host Response Panel, and 96 cytokines were examined (after 24 h) in tissue culture supernatants (Luminex platform). Genes and cytokines with a Log2 fold-change [&ge;]0.5 with p<0.05 compared to unstimulated cells were considered differentially expressed (DE). These studies revealed overlapping and distinct biosignatures. There were 118 DE genes with LL-37 and 71 with citLL-37, of which magnitude of change was significantly different for 32 genes. 16 out of 17 DE genes altered by both peptides were directly related to inflammation, and these were significantly less (by ~45%) with citLL-37 compared to LL-37. Similarly, inflammatory cytokines enhanced in response to LL-37 were significantly less (by 37-94%) with citLL-37. Overall, our findings indicate that citrullination of LL-37 does not abrogate cellular response in HBEC, instead dampens the inflammatory biosignature induced by LL-37.

Redox homeostasis requires both inducible antioxidant defense and constitutive machinery that continuously regenerates cellular reducing capacity. How these systems are altered across lung cell populations in chronic obstructive pulmonary disease (COPD) remains unclear. We integrated donor-level single-nucleus lung transcriptomes with smoke-exposure models, independent cohorts, and large-scale pharmacologic perturbation data. Both redox programs were reduced in established COPD, but constitutive redox support showed the greater loss, concentrated in fibroblasts and lymphatic endothelium. In fibroblasts, PGC-1 target-program output showed the most negative effect among 515 regulator programs despite preserved PPARGC1A expression. Smoke exposure activated inducible antioxidant defense across experimental models, whereas this adaptive program was reduced in established COPD. Pharmacologic perturbations further separated the two arms of redox homeostasis, with redox-directed interventions producing larger transcriptional responses in inducible defense and a distinct set of compounds increasing constitutive support together with PGC-1 target output and movement away from an independently defined COPD fibroblast state. These findings identify a cell-selective loss of constitutive redox support in COPD and implicate reduced PGC-1 target-program output in the fibroblast redox phenotype.

Background: Mitochondrial dysfunction is a hallmark of ageing and is implicated in the pathogenesis of sarcopenia. Genetically confirmed mitochondrial disease provides a biologically definitive model of impaired oxidative phosphorylation against which novel functional assessments can be validated. We investigated whether a brief, submaximal, non-ischaemic intermittent isometric handgrip exercise protocol combined with Near Infra-Red Spectroscopy (NIRS) could detect distinct muscle oxygenation signatures in mitochondrial disease and sarcopenia. Methods: Adults with genetically confirmed mitochondrial disease (n=10, 7 female) and group-matched controls (n=19, 11 female), underwent assessment of maximal grip force, handgrip relaxation kinetics and a 3-minute intermittent submaximal isometric handgrip test (40% maximal voluntary contraction, 1Hz contraction/relaxation) with continuous force recording at 2000Hz and simultaneous NIRS. Findings were compared with 23 community-dwelling older adults from the Muscle Ageing and Sarcopenia Study (MASS) Lifecourse cohort (n=23, 13 female) including seven with probable or confirmed sarcopenia according to European Working Group on Sarcopenia in Older People (EWGSOP2) criteria. Results: Participants with mitochondrial disease demonstrated an attenuated reduction in tissue saturation index (TSI) during exercise compared with controls (TSI % {middle dot} s150-180s: -59.9 {+/-} 94.5 vs -175.1 {+/-} 128.4; p=0.02). Total haemoglobin (THb) responses did not differ between groups (p=0.10). In contrast, participants with probable or confirmed sarcopenia showed exaggerated reduction in TSI compared with non-sarcopenic participants (TSI % {middle dot} s150-180s: -256.5 {+/-} 146.0 vs -121.2 {+/-} 95.2; p=0.05), while THb responses remained similar. The association between sarcopenia and TSI differed by sex (interaction coefficient -240, p=0.016), with greater TSI reductions observed in males with sarcopenia. Differences in TSI between mitochondrial disease and control groups were independent of age and sex. No statistically significant associations were observed between THb responses and age, sex or force production. Conclusions: A brief, non-ischaemic handgrip exercise protocol combined with NIRS identified divergent muscle oxygenation responses in mitochondrial disease and sarcopenia. The attenuated TSI response observed in genetically confirmed mitochondrial disease is consistent with impaired oxygen utilisation secondary to defective oxidative phosphorylation, whereas the exaggerated TSI reduction observed in sarcopenia suggests a distinct physiological mechanism, potentially involving impaired oxygen delivery, reduced muscle efficiency, or both. This portable and non-invasive approach has significant potential as a physiological biomarker for mechanistic studies and clinical trials in ageing and neuromuscular disease. More broadly, our findings demonstrate how biologically defined rare diseases can provide a powerful framework for interpreting mechanisms in common heterogeneous age-related conditions.