Cell Metabolism

During an immune response, metabolism changes dramatically. Metabolites are oxidized to power immune cell functions, serve as building blocks for proliferation, and act as effectors to regulate pathogen or host cells. Though metabolic changes in cultured cells have been studied extensively, metabolism changes in vivo are less understood. Here, we measured metabolomic changes across six mouse tissues in three models of immune activation: CpG-DNA cytokine storm, lymphocytic choriomeningitis virus infection, and polyI:C viral mimetic injection; and carried out metabolomics in cultured macrophages activated with different stimuli. We found most metabolomic changes were exclusive to either inflamed tissues or cultured macrophages, although itaconate was strongly induced in both contexts. We then mechanistically dissected the role of the soluble sialic acid N-glycolylneuraminic acid, which is highly induced in inflamed tissues yet only modestly in cultured macrophages. This metabolite rises in tissues in different models of inflammation, and the analogous human metabolite, N-acetylneuraminic acid, is increased in human patients experiencing inflammation. We found that N-glycolylneuraminic acid is produced in CD11b+ myeloid cells by cleavage of protein-bound sialic acid. However, blocking its production did not affect CpG-DNA liver inflammation or LCMV infection in mice. Therefore, these experiments identify soluble sialic acid as a conserved biomarker of inflammation in mice and humans and highlight the differences in metabolism between in vitro and in vivo models of inflammation.

Type 2 diabetes is linked to systemic inflammation driven by metabolic stress and aging. Although pancreatic inflammation associated with these factors is well documented, the dynamics of immune cell populations and their molecular changes remain poorly understood. We characterized immune cell alterations in the pancreas and pancreatic islets during Western diet (WD) feeding and aging using imaging mass cytometry (IMC) and single-cell RNA sequencing (scRNA-seq). Spatial and transcriptional analyses were performed to define immune cell subtype composition, activation states, and inferred cell-cell communication programs under metabolic and age-related stress conditions. Our analyses identified expansion of an F4/80low macrophage subtype and activated effector-like CD8+ T cells throughout the pancreas during WD feeding and aging. Within pancreatic islets, single-cell RNA sequencing identified a type 1 interferon-responsive macrophage population with low F4/80 expression that expanded during overnutrition. Notably, the type 1 interferon responses elicited by these stressors diverged: aging was associated with a more canonical type 1 interferon response, whereas overnutrition induced a broader response that included STAT3-associated transcriptional programs. We further provide evidence for enhanced cytokine-mediated communication between macrophages and a CD8+ cytotoxic T-cell population under overnutrition and aging. These findings show that metabolic stress and aging remodel pancreatic inflammation through overlapping but distinct immune mechanisms, involving expansion of F4/80low macrophages, activation of divergent type 1 interferon programs, and enhanced macrophage-CD8+ T-cell communication. Together, these findings suggest that distinct therapeutic approaches may be required to preserve islet function in type 2 diabetes driven by metabolic stress versus aging.

Post-meal activity can attenuate glucose excursions; however, the exact magnitude of this effect remains unquantified, and guidance is rarely personalized to the meal occasion. We linked Human Phenotype Project diet logs, continuous glucose monitoring and wearable step counts to test whether glycemic risk estimated before activity occurs can prioritize post-meal movement. An activity-blind PPGR model trained on 391,214 PPGR-valid meals from 9,561 participants generated pre-activity meal scores. Among 55,949 step-linked meals from 1,627 adults without diabetes, higher 0-120-min post-meal steps were associated with lower within-participant PPGR (-53.0 mg/dL*min per 1 s.d. higher log steps; 95% CI, -64.2 to -41.7), with larger adjusted PPGR iAUC contrasts at 1,501-2,500 observed steps (-154.4 mg/dL*min versus 0-50 steps). Associations were stronger among participants with higher glycemic-adiposity burden and after meals with higher predicted PPGR. A held-out pre-activity step-response ranking concentrated larger inverse step-PPGR associations (-79.1 top versus -15.0 mg/dL*min bottom quintile), providing a testable strategy for prediction-guided, post-meal movement prompts.

Stress involves the activation of cellular, physiological, and emotional processes that cost energy--nothing is free in biology. In mammals, the stress response involves hormone release, including norepinephrine (NE), which increases energy expenditure. To quantify the energetic cost of NE signaling in a simple cellular system, we interrogated the dose (0-10 M NE) and time-dependent (up to 10 hours) effects of adrenergic signaling in primary human fibroblasts. Oxygen consumption rates (OCR, reflecting ATP generated by mitochondria) and extracellular acidification rate (ECAR, reflecting ATP generated by glycolysis) were measured continuously using extracellular flux analysis, allowing us to estimate the ATP turnover rates, and thus cellular energy expenditure. Within the first 18 minutes (early phase), glycolysis increases up to 47% whereas respiration decreased 2-5%. Both parameters normalized within 1-2 hours for low NE concentrations. This was followed by an increase in oxidative phosphorylation (OxPhos), peaking around 9-12% by 2-6 hours (mid or late-phase). These minutes-to-hours data reveal the temporal dynamics whereby NE increases cellular energy expenditure in fibroblasts. Blocking OxPhos with oligomycin or piericidin A abolished OxPhos changes post-NE addition while conserving the glycolytic response. Withdrawal of glucose from the media significantly dampened the absolute rise in ECAR in response to NE, and instead increased OxPhos, revealing the metabolic flexibility in fibroblasts. Finally, cells with genetic defects impairing OxPhos exhibited a 50% blunted NE-driven metabolic response, consistent with the existence of an energy constraint in mitochondrial diseases. In summary, we have resolved the dynamics and flexible bioenergetic recalibrations associated with NE-driven hypermetabolism in primary human fibroblasts. Mapping the nature and magnitude of these recalibrations in humans would advance our understanding of the potential energetic forces underlying the damage to health by chronic stress.

Skeletal muscle can release endocrine stress signals during aging and wasting, but the upstream mechanisms that restrain this response remain incompletely defined. Here we identify March5 as a muscle proteostatic checkpoint that limits ATF4-dependent GDF15 production. March5 expression declined in aged and atrophic muscle, whereas muscle-specific March5 deletion induced ATF4 accumulation, marked GDF15 elevation, reduced food intake and progressive loss of body, muscle and bone mass. Restoration of feeding, GDF15 neutralization or muscle Atf4 deletion substantially attenuated the wasting phenotype. Mechanistically, March5 interacted with ATF4 and promoted its ubiquitination at K92, thereby limiting ATF4 stability and Gdf15 expression. Conversely, muscle March5 gain-of-function or pharmacological attenuation of ATF4 signaling improved feeding, body composition and physical performance in aged mice. These findings define a March5-ATF4-GDF15 endocrine stress axis linking muscle proteostatic control to feeding suppression and systemic body-composition remodeling.

Type 2 diabetes (T2D) arises from distinct diabetogenic mechanisms, but whether these mechanisms differ in their associations with hallmarks of aging remains unclear. We analyzed 449,505 UK Biobank and 374,973 All of Us participants using an overall T2D polygenic score (oPS) and eight partitioned polygenic scores (pPSs) representing distinct T2D-related mechanisms. Across organ systems, 81 age-related diseases were assigned to nine hallmarks of aging. UK Biobank analyses used Cox regression for incident hallmark-level outcomes, and All of Us analyses used logistic regression for prevalent hallmark-level outcomes. In both cohorts, the oPS was associated with disease burden across hallmarks, whereas pPS associations varied by mechanism. The obesity pPS showed the strongest and most consistent associations, while other insulin-resistance-related pPSs, including the lipodystrophy pPS, showed more modest positive associations. Beta-cell dysfunction pPS associations were close to null across hallmarks. Obesity pPS-hallmark associations were significantly attenuated after adjustment for BMI, and lipodystrophy pPS-hallmark associations after adjustment for triglyceride-to-HDL cholesterol ratio (TG/HDL-C), a marker of insulin resistance. These findings suggest that adiposity and insulin resistance, indexed by BMI and TG/HDL-C, may act as modifiable factors in the T2D genetic burden on aging hallmarks.

Pathologic white adipose tissue (WAT) remodeling, characterized by fibrosis, inflammation, and adipocyte dysfunction, is a hallmark and driver of metabolic disease in obesity1. Here, we show that legacy effects of early physiological or pharmacological interventions driving adaptive adipose remodeling can mitigate maladaptive WAT remodeling and metabolic dysfunction when developing obesity later in life. Cold exposure or beta3-adrenergic receptor (beta3AR) agonism (CL316,243) induced thermogenic remodeling of WAT in male mice. After a prolonged recovery at room temperature, trained epididymal WAT reverted to an energy-storing state but retained a population of adipocytes resembling metabolically flexible visceral adipocytes found in human metabolically healthy obesity. The legacy of the antecedent treatment conferred lasting protection against glucose intolerance when later developing high fat diet (HFD)-induced obesity, with insulin sensitivity persisting for at least 20 weeks of overnutrition. This metabolic resilience was accompanied by healthy epididymal WAT expansion with reduced fibrosis and inflammation. Our findings demonstrate that short-term interventions, without genetic manipulation, can train adipose tissue, enhancing its long-term plasticity and conferring durable protection against future obesity-associated insulin resistance.

Adipose tissue harbors a significant population of regulatory T (Treg) cells that enforce immune homeostasis, yet whether Tregs function as an immunometabolic checkpoint to directly regulate core adipocyte signaling programs remains incompletely defined. Here we show that adipose Tregs function as a dominant, time-dependent checkpoint on {beta}-adrenergic signal-driven lipolytic program and signal transduction in adipocytes. Our integrated scRNA-seq, flow cytometry, and phosphoproteomics data show that prolonged adrenergic stimulation induces a progressive attenuation of activation of key lipase hormone-sensitive lipase (HSL) that coincides with Treg depletion in circulation and accumulation within white adipose tissue. Genetic perturbations establish Treg-derived interleukin-10 (IL-10) as the key mediator of this brake. IL-10 signaling through adipocyte IL-10R suppresses adrenergic HSL activation and rewires downstream signaling nodes that govern catecholamine responsiveness, lipolysis, and systemic energy homeostasis. Mechanistically, IL-10R engages a STAT3-dependent transcriptional program that induces the G-protein regulators RGS2 and RGS3, diminished PKA flux to HSL that reinforces suppression of the HSL activation state and lipolysis. Together, these findings define an adrenergic-immune feedback circuit in which Tregs fine tune the amplitude and duration of catecholamine responsiveness in adipocytes, establishing immune control of a core lipolytic pathway with implications for obesity-associated adipose dysfunction.

Mitochondrial communication coordinates adaptive responses across organelles to sustain cellular homeostasis, a network that declines with age and contributes to loss of proteostasis. Here, we identify MOTS-c, an exercise-induced mitochondrial-derived peptide (MDP) encoded within the 12S rRNA locus, as an inter-organellar arm of the mitochondrial stress response (MSR) that links mitochondrial signaling to endoplasmic reticulum (ER) proteostasis and enables adaptation to chronic stress. Using progressive stress media (PSM), a model of gradual and multifactorial metabolic stress, we show that MOTS-c enables adaptation through a biphasic program: acutely, a reversible, ATF4-independent suppression of protein synthesis; and chronically, an ATF6-biased ER unfolded protein response (UPRER) with tempered ATF4 engagement and coordinated metabolic remodeling. Whereas mitochondrial unfolded protein response (UPRmt) pathways have been extensively characterized in acute, genetic, and sustained models of mitochondrial perturbation, this work reveals how mitochondrial communication actively engages ER proteostasis during progressive and persistent metabolic stress. By expanding proteostatic capacity while tempering terminal stress signaling, MOTS-c enables cells to withstand chronic stress. Together, these findings define a MOTS-c-dependent arm of the MSR that integrates mitochondrial communication with ER proteostasis to promote chronic metabolic stress adaptation.

Type 1 diabetes (T1D) involves immune-mediated destruction of pancreatic {beta}-cells, yet current disease-modifying therapies mainly target immunity without enhancing {beta}-cell resilience. We show selective neuropeptide Y4 receptor (Y4R) agonism protects {beta}-cells while reshaping islet immunity across T1D models. Multi-modal localisation using cell sorting, qPCR, RNAscope and fluorescent ligand competition demonstrated predominant Y4R expression and functional accessibility on mouse and human {beta}-cells. Selective Y4R agonism was non-toxic and did not impair islet network integrity, Ca{superscript 2} dynamics, glucose-stimulated insulin secretion or systemic glucose tolerance. Y4R activation conferred cytoprotection against inflammatory cytokines, streptozotocin, lipotoxicity and ER stress, reducing caspase-3/7 activation and {beta}-cell loss whilst sustaining insulin release and promoting proliferation in both mouse and human islets. Bulk RNA-seq revealed a coordinated {beta}-cell resilience programme characterised by reinforced identity and insulin processing, KEAP1-NFE2L2-driven antioxidative and proteostatic activation, and suppression of EIF2 signalling and associated biosynthetic and ER stress pathways. Concurrently, Y4R agonism dampened pathogenic chemokine and cytokine networks, including CXCL10, CCL3/4/7 and IL-6, while preserving IL-2 and Foxp3 signals, thereby limiting CD8 T cell, CD4 T cell and macrophage chemotaxis toward cytokine-stressed islets. Reduced immune-cell recruitment was conserved in a fully human immune-islet system, where Y4R activation significantly attenuated IL-2-activated human PBMC migration and invasion toward cytokine-stressed human islets. In a stringent NY8.3 CD8 T cell adoptive-transfer model, systemic Y4R agonism significantly delayed diabetes onset. These data position Y4R as a {beta}-cell-centric therapeutic target coupling intrinsic resilience with local immune modulation, offering a complementary approach for {beta}-cell preservation in T1D and islet replacement therapies. Graphical abstractThe selective Y4 receptor agonist K22 binds {beta}-cell-enriched NPY4R in mouse and human islets, activates a {beta}-cell resilience programme that preserves insulin secretion under inflammatory and metabolic stress, and simultaneously dampens islet chemokine output, thereby limiting innate and adaptive immune-cell recruitment and delaying autoimmune diabetes onset. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=119 SRC="FIGDIR/small/736290v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@11af8d3org.highwire.dtl.DTLVardef@1c60d37org.highwire.dtl.DTLVardef@18dd142org.highwire.dtl.DTLVardef@1a56cdb_HPS_FORMAT_FIGEXP M_FIG C_FIG

Systemic aging and metabolic overload remodel the vasculature; however, how endothelial cells integrate these stresses across organs remains unclear. Using multi-organ single-cell and spatial transcriptomics with functional validation, we mapped endothelial and hematopoietic responses in adipose tissue, skeletal muscle, liver, and heart. Organ-specific endothelial transcriptional features were relatively preserved, whereas chronic stress selectively reconfigured regulatory programs: aging induced a conserved Irf/Stat-centered endothelial program, while high-fat diet engaged organ-biased lipid and remodeling programs. Spatial analysis revealed perivascular niches centered on aging-associated interferon-stimulated endothelial activation, with neighboring immune and stromal cells expressing C3 and LRP1-associated signals. Rather than simply amplifying inflammation, these niches contained mechanisms that restrained IFN activation, as C3 depletion upregulated vascular IRF7 expression. In parallel, the IFN downstream effector BST2 promoted anti-inflammatory macrophage differentiation and suppressed atherosclerosis. These findings define vascular inflammaging as an organ-resolved niche process in which endothelial IFN activation is coupled to local inflammatory restraint. HighlightsO_LIAging induces a shared endothelial type I IFN program across organs. C_LIO_LIA high-fat diet triggers organ-biased endothelial remodeling programs. C_LIO_LIPerivascular interferon niches couple inflammation with local restraint. C_LIO_LIIFN-induced endothelial BST2 promotes CD200R-associated macrophage regulatory features. C_LI

Mammalian energy homeostasis depends on coordinated metabolism across tissues, with the liver acting as a central hub for systemic energy balance and biosynthetic precursor supply. Although hepatic mitochondrial dysfunction is implicated in diverse pathologies, mitochondrial regulation across liver microanatomical space and time remains incompletely defined. Here, we mapped how mitochondrial- and nuclear-encoded genes supporting mitochondrial function vary along spatial gradients within the lobule and across the feeding-fasting cycle in mice. Integrating these transcriptomic features with quantitative measurements of mitochondrial morphology in periportal and pericentral hepatocytes, we showed that functional hepatocyte subtypes are distinguished by pronounced mitochondrial divergence, including cells with exceptionally low mitochondrial gene expression and reduced secretory protein production. We described that higher periportal oxidative phosphorylation relies on an exceptionally high periportal mitochondrial transcript fraction, while nuclear mitochondrial-function genes do not follow this pattern. The increased periportal mitochondrial transcript abundance coincided with substantially increased periportal cytoplasmic mitochondrial density. In humans, we recapitulated the higher periportal mitochondrial transcript abundance and showed that mitochondrial-function genes exhibited rhythmic expression patterns, more so in women. Together, these data establish a spatially and temporally resolved reference dataset of hepatic mitochondrial regulation that provides a reference for interpreting liver single-cell datasets and mechanistic pathophysiological studies.

Hypoxia is a potent stressor and a major cause of {beta}-cell failure and loss after islet transplantation. Autophagy is a critical homeostatic mechanism that preserves organelle integrity and metabolic balance in cells under stress, but whether it supports {beta}-cell adaptation to sustained oxygen deprivation is unclear. Here, we used {beta}-cell-specific Atg5 knockout together with hypoxia and transplantation models, to demonstrate that autophagy is a major determinant of {beta}-cell survival during oxygen limitation and supports islet graft function. However, prolonged hypoxia suppressed autophagic flux, reduced lysosomal activity, and led to autophagosome accumulation, indicating failure of the lysosomal clearance pathway. This was accompanied by a marked reduction in transcription factor EB (TFEB) and its lysosomal target genes. Genetic and pharmacological activation of TFEB restored lysosomal gene expression and cathepsin B activity and improved {beta}-cell viability under hypoxia, implicating TFEB decline as a contributor to autophagy-lysosome dysfunction. Together, these findings outline a sequence in which autophagy initially safeguards {beta}-cells but becomes ineffective under sustained hypoxia as TFEB levels fall, identifying TFEB as a potential target to strengthen {beta}-cell resilience and survival in islet transplantation.

Hyperglycemia in Type 1 Diabetes (T1D) is managed almost exclusively via exogenous insulin therapy, an approach restricted by significant glycemic fluctuations, long-term side effects such as weight gain, and high economic burden. Identifying physiological pathways capable of clearing blood glucose independent of insulin is therefore of paramount clinical importance. Here, we demonstrate that liver-specific stearoyl-CoA desaturase-1 (SCD1) deficiency protects against diabetic hyperglycemia and hepatic steatosis in an insulin-independent manner. SCD1 ablation decreases cellular oleate availability, altering lipid flux and redirecting excess cholesterol into alternative biosynthetic pathways. This redirection drives a 2-fold elevation in hepatic bile acids and a striking 10-fold increase in plasma bile acids, predominantly characterized by the accumulation of taurocholic acid. This shifted bile acid pool stimulates the expression of glucose transporter 1 (Glut1) in the liver via activation of the nuclear hormone receptor FXR, facilitating basal glucose clearance in the absence of insulin. Genetic deletion models show that while the hepatokine FGF21 serves as a partial mediator of this phenotype, the local bile acid-FXR axis remains a sufficient driver of systemic glucose clearance. Finally, we show that dietary oleate supplementation completely reverses this protective phenotype, turning down Glut1 expression and restoring overt diabetes. Together, our findings uncover a novel bile acid-FXR-Glut1 signaling axis triggered by SCD1 inhibition, offering a framework for insulin-independent glycemic control.

Disease tolerance limits infectious disease severity through tissue damage control mechanisms that do not target pathogens directly. Here we demonstrate that age-dependent decline in adipose tissue lipolysis compromises disease tolerance to SARS-CoV-2 infection. Young adult mice exhibited robust adipocyte lipolysis and 80% survival, whereas old mice showed impaired adipocyte lipolysis and only 20% survival. Genetic repression of adipocyte lipolysis eliminated this age-dependent survival advantage without affecting viral titers, revealing that adipocyte lipolysis is essential for disease tolerance to SARS-CoV-2 in young adults. Impaired adipocyte lipolysis in aged mice was associated with a plasma lipidomic signature that predicts COVID-19 severity and mortality in three independent human cohorts. Mechanistically, adipocyte lipolysis provides free fatty acids (FFA) to support bone marrow emergency myelopoiesis, through CD36- and CPT1-dependent FFA cellular uptake and mitochondrial import, respectively. Bone marrow derived monocytes migrate to the lung via CCL2/CCR2-dependent mechanism where they enforce an immune-metabolic communication network with parenchymal cells to sustain lung structure and function. This circuit is not required to confer protection against influenza infection, revealing pathogen-specific disease tolerance mechanisms. These findings reveal adipose tissue catabolism as a central age-dependent factor responsible for exacerbated COVID-19 mortality in aged populations.

Brown adipocytes (BAs) hold therapeutic promise for obesity and metabolic diseases. While interscapular BAs derive from Pax3+/Myf5+ dermomyotome, peri-aortic BAs are inferred from an unknown Pax3+/Myf5- somitic origin. Here, we identify human endotome as an MYF5-independent source of peri-aortic BAs. Through interrogating public mouse organogenesis and in-house human trunk embryoid single-cell data, we show that the early endotome cells are MYF5-independent and are primed by TGF-{beta}-induced epithelial-to-mesenchymal transition. Mechanistically, endotome-to-BA specification requires sequential BMP inhibition and Wnt activation. This roadmap results in UCP1-expressing and metabolically active BAs that transcriptionally resemble in vivo peri-aortic BAT. The multipotent endotome cells also give rise to vascular smooth muscle and endothelial cells, offering a self-sufficient source for BAT vasculature. Endotome-derived BAs show accelerated differentiation, reduced heterogeneity, and sustained Wnt activity. Thus, the endotome provides a versatile platform for generating BAs and supporting vasculature, with implications for cell-based therapy and tissue engineering in metabolic disease.

Epstein-Barr virus (EBV) causes over 200,000 cancers annually, including immunoblastic lymphomas in immunosuppressed hosts. Most transformed cells arrest, yet survive when deprived of the essential amino acid methionine. We instead find that EBV transformed lymphoblastoid cell lines (LCLs), which model the EBV latency III program-driven B-cell lymphoproliferative diseases of immunosuppressed hosts, rapidly die upon methionine restriction. Methionine restriction elevated LCL lipid reactive oxygen species and triggered ferroptosis. Whereas methionine restriction hypomethylates the EBV genome and triggers viral reactivation in latency I Burkitt cells by lowering the cellular methylation potential, the LCL latency III program instead redirected methionine toward redox defense, without altering the SAM/SAH ratio. Stable-isotope tracing revealed that latency III strongly induces transsulfuration, synthesizing cysteine de novo to support glutathione pools. The EBV oncoprotein LMP2A, which mimics B-cell receptor signaling, supported newly infected human B cell cystathionine-{beta}-synthase and cystathionine-{gamma}-lyase expression and methionine dependence, phenocopied by immunoglobulin crosslinking. In vivo, dietary methionine restriction impaired LCL xenograft outgrowth and depleted tumor cystine. Combined methioninase and cyst(e)inase administration blocked both cysteine sources, collapsed tumor glutathione levels, and triggered ferroptosis. Our results define methionine metabolism as a targetable ferroptosis vulnerability of EBV-transformed B cells. HighlightsO_LIMethionine restriction triggers EBV-transformed lymphoblastoid B cell ferroptosis C_LIO_LIEBV latency III induces transsulfuration to sustain LCL cysteine and glutathione C_LIO_LIMethioninase or dietary methionine restriction strongly impair LCL growth in vivo C_LIO_LIMethioninase plus cyst(e)inase collapses xenograft GSH levels and drives ferroptosis C_LI

Insulin can misfold and assemble into amyloid fibrils, a process linked not only to complications of insulin therapy but also to proteotoxic stress in pancreatic {beta}-cells. Despite growing interest in the pathological consequences of insulin aggregation, prevention efforts are limited by an incomplete understanding of the endogenous mechanisms that counteract it. Here, we identify Fas apoptosis inhibitory molecule (FAIM) as an endogenous suppressor of insulin amyloid formation. FAIM reduces {beta}-sheet formation and redirects insulin toward disordered, growth-incompetent assemblies. Further, FAIM attenuates the cytotoxicity of insulin aggregates in vitro. We hypothesize that this effect arises from masking aggregation-prone regions of insulin and show through structural modeling that FAIM interacts with both insulin chains. These findings extend the anti-aggregation function of FAIM to insulin and suggest a mechanism for endogenous suppression of insulin amyloid formation. More broadly, our results provide insight into the regulation of insulin assembly and highlight FAIM as a candidate modulator of proteostasis in metabolic disease. Statement for a broader audienceInsulin can clump together into harmful aggregates, contributing to complications of insulin therapy and potentially damaging the insulin-producing cells of the pancreas. This study identifies the naturally occurring protein FAIM as a protective factor that inhibits the formation of these harmful aggregates and reduces their toxicity. These findings improve our understanding of how cells protect insulin from harmful aggregation and may open new avenues for developing therapies to combat diabetes-related protein aggregation.

The pace of aging can be delayed by mutations, dietary manipulations, and drugs, yet the metabolic mechanisms underlying longevity interventions remain poorly understood. Here we present a multi-tissue metabolomic analysis of male UM-HET3 mice treated from 4 to 12 months of age with five validated longevity interventions: rapamycin, acarbose, 17-estradiol, canagliflozin, or caloric restriction. Using a feature-stabilized XGBoost pipeline applied to seven tissues, we show that metabolomic profiles can identify treated mice as likely recipients of a lifespan-extending intervention well before survival differences emerge. A leave-one-intervention-out procedure confirmed that models trained on any four interventions successfully classified mice from a fifth, unseen intervention, implying shared metabolic alterations across mechanistically distinct treatments. The most influential metabolites -- defined as the minimum set explaining 50% of cumulative model gain -- differed substantially across tissues. Only ergothioneine, a dietary antioxidant, ranked highly in more than two tissues: it was elevated by all five interventions in plasma and brain, and by four of five in muscle. Enrichment analyses further identified coordinated remodeling of lipid classes in plasma, perigonadal fat, and kidney. These findings reveal tissue-specific metabolic reprogramming shared across mechanistically distinct longevity interventions and, pending validation against interventions that do not extend lifespan, suggest a path toward metabolomic screening of candidate anti-aging drugs.

Cells release membrane-bound extracellular vesicles into the bloodstream laden with proteins that may reflect their physiological state. How this circulating EV proteome changes across life remains poorly understood. Identifying molecular signatures of aging in accessible biofluids could facilitate earlier intervention and monitoring of age-related disease. Many circulating aging proteome studies rely on affinity-based platforms which suffer from poor cross-species translation, ambiguous signal attribution, and inconsistent agreement between platforms. Here, we present a characterization of the aging plasma EV proteome from a cross-sectional cohort of 86 male and female C57BL/6J mice (5-31 months). We leveraged a species-agnostic EV enrichment (Mag-Net) and mass spectrometry to detect 2,575 protein groups from 15,969 peptides. Protein abundance heterogeneity increased with age and the abundance of 272 proteins were significantly correlated with chronological age including established senescence and frailty markers. Proteins increasing with age were enriched in genome maintenance pathways, while those decreasing were associated with the extracellular matrix organization and lipid metabolism. Notably, several of the strongest age-increased proteins converged on Alzheimer's and Parkinson's disease pathology. We observed sexual divergence in the aging EV proteome not previously characterized at this resolution. A proteomic clock built from this data accurately predicts chronological age, and peptide-level analysis reveals aging signals invisible at protein-level. These findings demonstrate that EV-enriched plasma proteomics can identify known aging markers, reveal novel sex-specific age-related changes, and generate predictive models of chronological age. This study provides a species-agnostic foundation for proteomic clocks that complement epigenetic approaches to monitor aging and evaluate healthspan.