A major aging hallmark is the accumulation of cellular senescence burden. Over time, senescent cells contribute to tissue deterioration through chronic inflammation and fibrosis driven by the senescence-associated secretory phenotype (SASP). The human ovary is one of the first organs to age, and prominent age-related fibroinflammation within the ovarian microenvironment is consistent with the presence of senescent cells, but these cells have not been characterized in the human ovary. We thus established a doxorubicin-induced model of cellular senescence to establish a "senotype" (gene/protein signature of a senescence cell state) for ovarian senescent cells. Explants of human postmenopausal ovarian cortex and medulla were treated with doxorubicin for 24 h, followed by culture for up to 10 days in a doxorubicin-free medium. Tissue viability was confirmed by histology, lack of apoptosis, and continued glucose consumption by explants. Single nuclei sequencing and proteomics revealed an unbiased signature of ovarian senescence. We identified distinct senescence profiles for the cortex and medulla, driven predominantly by epithelial and stromal cells. Proteomics uncovered subregional differences in addition to 120 proteins common to the cortex and medulla SASP. Integration of transcriptomic and proteomic analyses revealed 26 shared markers, defining a senotype of doxorubicin-induced senescence unique to the postmenopausal ovary. A subset of these proteins: Lumican, SOD2, MYH9, and Periostin were mapped onto native tissue to reveal compartment-specific localization. This senotype will help determine the role of cellular senescence in ovarian aging, inform biomarker development to identify, and therapeutic applications to slow or reverse ovarian aging, senescence, and cancer.

As humans embark on longer and deeper missions into space, it is crucial to understand how spaceflight impacts the immune system. Decades of discoveries, bolstered by recent multiomic analyses, have identified key immune processes that are affected by the spaceflight environment. These findings form the foundations of the emerging field of ‘astroimmunology’. Spaceflight stressors — such as microgravity and galactic cosmic radiation — and other mission-associated variables, including psychological stress and abnormal circadian rhythms, can disrupt or adversely affect immune cell biology. In addition, spaceflight alters host–microbiome interactions, which can increase susceptibility to opportunistic pathogens and viral reactivation. Although ground-based analogues for human spaceflight have provided insights into these stressors individually, their combined effects during spaceflight remain less understood. This Review explores our current knowledge of the effects of spaceflight stressors on the immune system and the clinical implications for human space exploration. It also highlights current and developing countermeasures, including machine-learning approaches, advanced monitoring technologies and standardized biobanking, that can facilitate research into the impact of spaceflight on the immune system. Looking ahead, progressing from low Earth orbit missions to long-term missions to the Moon, Mars and beyond will introduce new challenges, including increased radiation, variable gravity and regolith exposure. We discuss these prospective challenges and outline potential preventive and mitigative strategies for sustaining immune health to enable safe and effective space exploration and habitation of distant worlds. As more spaceflight missions plan to take humans back to the moon — and beyond — a key goal is to understand how spaceflight affects the immune system. In this Review, researchers from academia and international space agencies discuss the emergence of the field of ‘astroimmunology’. They outline the main immunological challenges we must overcome to facilitate safe space exploration by humans.

IntroductionHypertension and impaired tissue perfusion are frequent comorbidities in obesity. Since resistance arteries are the primary regulators of peripheral resistance and hence, systemic blood pressure and local blood flow control, we hypothesized that resistance arteries isolated from obese mice would display augmented myogenic reactivity and altered vasomotor responses, compared to non-obese controls. MethodsEight-week-old C57BL/6J mice were fed either a high-fat diet (60% calories from fat; HFD) or a matched control diet for 16 weeks. Body weight, fasting blood glucose, oral glucose tolerance and insulin tolerance were measured. In parallel studies, we measured mean arterial pressure, conducted echocardiographic measurements of cardiac morphology and function and assessed skeletal muscle, mesenteric and cerebral resistance artery reactivity ex vivo with pressure myography. ResultsHFD mice exhibited substantial weight gain and metabolic dysfunction compared to controls. Left ventricular wall thickness and mass were increased in HFD mice, but no other morphological or functional cardiac parameters were different from controls. Blood pressure was modestly increased in HFD mice (from 81 to 87 mmHg; measured under anesthesia); however, contrary to our hypothesis, resistance arteries from HFD mice showed no overt microvascular phenotype in any microvascular bed tested (i.e., no differences in passive diameter, myogenic reactivity or vasomotor responses to phenylephrine or acetylcholine). ConclusionWe conclude that resistance artery function is unaltered in this diet-induced model of obesity with metabolic dysfunction.

Cells are subjected to dynamic mechanical environments which impart forces and induce cellular responses. In age-related conditions like pulmonary fibrosis, there is both an increase in tissue stiffness and an accumulation of senescent cells. While senescent cells produce a senescence-associated secretory phenotype (SASP), the impact of physical stimuli on both cellular senescence and the SASP is not well understood. Here, we show that mechanical tension, modeled using cell culture substrate rigidity, influences senescent cell markers like SA-β-gal and secretory phenotypes. Comparing human primary pulmonary fibroblasts (IMR-90) cultured on physiological (2 kPa), fibrotic (50 kPa), and plastic (approximately 3 GPa) substrates, followed by senescence induction using doxorubicin, we identified unique high-stiffness-driven secretory protein profiles using mass spectrometry and transcriptomic signatures, both showing an enrichment in collagen proteins. Consistently, clusters of p21+ cells are seen in fibrotic regions of bleomycin induced pulmonary fibrosis in mice. Computational meta-analysis of single-cell RNA sequencing datasets from human interstitial lung disease confirmed these stiffness SASP genes are highly expressed in disease fibroblasts and strongly correlate with mechanotransduction and senescence-related pathways. Thus, mechanical forces shape cell senescence and their secretory phenotypes.

The "gut-brain axis" is an emerging target in Alzheimer's disease (AD), although its immunological features remain poorly understood. Using single-cell RNA sequencing, coupled to extensive spectral-tuning flow cytometry validation of the colon immune compartment in the 5XFAD amyloid-β mouse model, we found several AD-associated changes including in B/plasma cell activity. Notably, levels of CXCR4+ antibody-secreting cells are reduced in 5XFAD colons. This change corresponds with accumulating CXCR4+ B cells and gut-specific IgA+ cells in the brain and dura mater, respectively. Consistently, a chemokine ligand for CXCR4, CXCL12, is expressed at higher levels in the 5XFAD brain and in in silico-analyzed human AD brain studies, supporting altered neuroimmune trafficking. An inulin prebiotic fiber diet could expand gut IgA+ cells, rescue peripheral Treg levels, reduce dysbiosis, improve serum microbial metabolite levels, and attenuate overall AD-associated frailty. Our study reveals key aspects of the gut-brain axis and highlights potential targets against AD.

Reduced dietary fiber intake is associated with, and may have contributed to, the post-mid-20th century increase in immune-mediated chronic inflammatory diseases, including inflammatory bowel disease (IBD). Reduced fiber intake has resulted, in part, from increased consumption of highly refined foods including those made from white flours, generation of which involves removal of much of the fiber naturally present in wheat kernels. Accordingly, we hypothesized that wheat fiber (WF) might protect against chronic inflammatory diseases. We tested this notion in a murine T-cell-transfer colitis model. Rag1-/- mice were fed purified (open-source) low-fiber diets enriched, or not, with WF and then administered CD45Rbhi T-cells. WF conferred robust protection in this colitis model as assessed by an array of clinical, histopathologic, morphologic, and immune-related parameters. WF's protection against colitis associated with a microbiota-dependent increase in Foxp3+ T-cells (Tregs), which could be recapitulated in vitro. WF did not induce Tregs in mice lacking conserved non-coding sequence 1 knock-out (CNS1), which is known to drive peripheral Treg development, nor did WF protect against T-cell-transfer colitis driven by transplant of colitogenic T-cells from CNS1-/- mice. Thus, enriching diet with WF has potential to promote microbiota-dependent peripheral Treg development and, consequently, protect against chronic inflammatory diseases.

Microgravity is associated with immunological dysfunction, though the mechanisms are poorly understood. Here, using single-cell analysis of human peripheral blood mononuclear cells (PBMCs) exposed to short term (25 hours) simulated microgravity, we characterize altered genes and pathways at basal and stimulated states with a Toll-like Receptor-7/8 agonist. We validate single-cell analysis by RNA sequencing and super-resolution microscopy, and against data from the Inspiration-4 (I4) mission, JAXA (Cell-Free Epigenome) mission, Twins study, and spleens from mice on the International Space Station. Overall, microgravity alters specific pathways for optimal immunity, including the cytoskeleton, interferon signaling, pyroptosis, temperature-shock, innate inflammation (e.g., Coronavirus pathogenesis pathway and IL-6 signaling), nuclear receptors, and sirtuin signaling. Microgravity directs monocyte inflammatory parameters, and impairs T cell and NK cell functionality. Using machine learning, we identify numerous compounds linking microgravity to immune cell transcription, and demonstrate that the flavonol, quercetin, can reverse most abnormal pathways. These results define immune cell alterations in microgravity, and provide opportunities for countermeasures to maintain normal immunity in space. The phenotype and function of immune cells could change during spaceflight. Here the authors use simulated microgravity, coupled to validation with spaceflight data, to assess whether there are distinct gene expression changes in resting and TLR 7/8 stimulated PBMCs and found conserved changes in IFN signalling, the cytoskeleton, IL-6 and sirtuin signalling.

The accumulation of lipid and the formation of macrophage foam cells is a hallmark of atherosclerosis, a chronic inflammatory disease. To better understand the role of macrophage lipid accumulation in inflammation during atherogenesis, we studied early molecular events that follow the accumulation of oxidized low-density lipoprotein (oxLDL) in cultured mouse macrophages. We previously showed that oxLDL accumulation downregulates the inflammatory response in conjunction with downregulation of late-phase glycolysis. In this study, we show that within hours after LPS stimulation, macrophages with accumulated oxLDL maintain early-phase glycolysis but selectively downregulate activation of AKT2, one of three AKT isoforms. The inhibition of AKT2 activation reduced LPS-induced ATP citrate lyase activation, acetyl-CoA production, and acetylation of histone 3 lysine 27 (H3K27ac) in certain inflammatory gene promoters. In contrast to oxLDL, multiple early LPS-induced signaling pathways were inhibited in macrophages with accumulated cholesterol, including TBK1, AKT1, AKT2, MAPK, and NF-κB, and early-phase glycolysis. The selective inhibition of LPS-induced AKT2 activation was dependent on the generation of mitochondrial oxygen radicals during the accumulation of oxLDL in macrophages prior to LPS stimulation. This is consistent with increased oxidative phosphorylation, fatty acid synthesis, and oxidation pathways found by comparative transcriptomic analyses of oxLDL-loaded versus control macrophages. Our study shows a functional connection between oxLDL accumulation, inactivation of AKT2, and the inhibition of certain inflammatory genes through epigenetic changes that occur soon after LPS stimulation, independent of early-phase glycolysis.

Environmental risk factors possess the potential to modulate the pathogenesis of type I diabetes (T1D). Foremost among these factors are early life influences impacting the gastrointestinal (GI) tract. During infancy, both the microbiota and immune system are influenced by maternal factors contributing to key events in the neonatal GI tract. Despite the well-known importance of maternal factors on infant immune development, whether maternal immune dysregulation and dysbiosis can perpetuate the same in offspring remains largely unknown. To explore how these maternal factors impact offspring disease development, we used IgA-deficiency induced maternal dysbiosis in Non-Obese Diabetic (NOD) dams to study T1D development in their progeny. We found that maternal dysbiosis led to changes in IgA-sufficient offspring immune development resulting in heightened GI immune activity. Maternal dysbiosis also contributed to altered microbiome establishment in progeny, such that pups exhibited reduced colonic abundance of Akkermansia muciniphila and Clostridoides difficile. In adulthood, these mice exhibited a lowered incidence of T1D. This protection was replicated by fostering high incidence offspring to dysbiotic dams, prompting us to propose that altered breast milk composition in dysbiotic dams can influence immune development and microbiome establishment in offspring, contributing to T1D resistance. ### Competing Interest Statement The authors have declared no competing interest.

Telomeres are repetitive nucleoprotein complexes at chromosomal termini essential for maintaining genome stability. Telomeric RNA, or TERRA, is a previously presumed long noncoding RNA of heterogeneous lengths that contributes to end-capping structure and function, and facilitates telomeric recombination in tumors that maintain telomere length via the telomerase-independent Alternative Lengthening of Telomeres (ALT) pathway. Here, we investigated TERRA in the radiation-induced DNA damage response (DDR) across astronauts, high-altitude climbers, healthy donors, and cellular models. Similar to astronauts in the space radiation environment and climbers of Mt. Everest, in vitro radiation exposure prompted increased transcription of TERRA, while simulated microgravity did not. Data suggest a specific TERRA DDR to telomeric double-strand breaks (DSBs), and provide direct demonstration of hybridized TERRA at telomere-specific DSB sites, indicative of protective TERRA:telomeric DNA hybrid formation. Targeted telomeric DSBs also resulted in accumulation of TERRA foci in G2-phase, supportive of TERRA's role in facilitating recombination-mediated telomere elongation. Results have important implications for scenarios involving persistent telomeric DNA damage, such as those associated with chronic oxidative stress (e.g., aging, systemic inflammation, environmental and occupational radiation exposures), which can trigger transient ALT in normal human cells, as well as for targeting TERRA as a therapeutic strategy against ALT-positive tumors. Transcriptomics (RNA-seq) data reveal significantly increased telomeric RNA, or TERRA, in response to spaceflight and radiation exposure (compared to baseline and ground control samples).

Lipid accumulation in macrophages (Mφs) is a hallmark of atherosclerosis. Yet, how lipid loading modulates Mφ inflammatory responses remains unclear. We endeavored to gain mechanistic insights into how pre-loading with free cholesterol modulates Mφ metabolism upon LPS-induced TLR4 signaling. We found that activities of prolyl hydroxylases (PHDs) and factor inhibiting HIF (FIH) are higher in cholesterol loaded Mφs post-LPS stimulation, resulting in impaired HIF-1α stability, transactivation capacity and glycolysis. In RAW264.7 cells expressing mutated HIF-1α proteins resistant to PHDs and FIH activities, cholesterol loading failed to suppress HIF-1α function. Cholesterol accumulation induced oxidative stress that enhanced NRF2 protein stability and triggered a NRF2-mediated antioxidative response prior to and in conjunction with LPS stimulation. LPS stimulation increased NRF2 mRNA and protein expression, but it did not enhance NRF2 protein stability further. NRF2 deficiency in Mφs alleviated the inhibitory effects of cholesterol loading on HIF-1α function. Mutated KEAP1 proteins defective in redox sensing expressed in RAW264.7 cells partially reversed the effects of cholesterol loading on NRF2 activation. Collectively, we showed that cholesterol accumulation in Mφs induces oxidative stress and NRF2 stabilization, which when combined with LPS-induced NRF2 expression leads to enhanced NRF2-mediated transcription that ultimately impairs HIF-1α-dependent glycolytic and inflammatory responses.

Antibodies are essential to immune homeostasis due to their roles in neutralizing pathogenic agents. However, failures in central and peripheral checkpoints that eliminate autoreactive B cells can undermine self-tolerance and generate autoantibodies that mistakenly target self-antigens, leading to inflammation and autoimmune diseases. While autoantibodies are well-studied in autoimmune and in some communicable diseases, their roles in chronic conditions, such as obesity and aging, are less understood. Obesity and aging share similar aspects of immune dysfunction, such as diminished humoral responses and heightened chronic inflammation, which can disrupt immune tolerance and foster autoantigen production, thus giving rise to autoreactive B cells and autoantibodies. In return, these events may also contribute to the pathophysiology of obesity and aging, to the associated autoimmune disorders linked to these conditions, and to the development of immunosenescence, an age-related decline in immune function that heightens vulnerability to infections, chronic diseases, and loss of self-tolerance. Furthermore, the cumulative exposure to antigens and cellular debris during obesity and aging perpetuates pro-inflammatory pathways, linking immunosenescence with other aging hallmarks, such as proteostasis loss and mitochondrial dysfunction. This review examines the mechanisms driving autoantibody generation during obesity and aging and discusses key putative antigenic targets across these conditions. We also explore the therapeutic potential of emerging approaches, such as CAR-T/CAAR-T therapies, vaccines, and BiTEs, to tackle autoimmune-related conditions in aging and obesity.

Spaceflight induces an immune response in astronauts. To better characterize this effect, we generated single-cell, multi-ome, cell-free RNA (cfRNA), biochemical, and hematology data for the SpaceX Inspiration4 (I4) mission crew. We found that 18 cytokines/chemokines related to inflammation, aging, and muscle homeostasis changed after spaceflight. In I4 single-cell multi-omics data, we identified a "spaceflight signature" of gene expression characterized by enrichment in oxidative phosphorylation, UV response, immune function, and TCF21 pathways. We confirmed the presence of this signature in independent datasets, including the NASA Twins Study, the I4 skin spatial transcriptomics, and 817 NASA GeneLab mouse transcriptomes. Finally, we observed that (1) T cells showed an up-regulation of FOXP3, (2) MHC class I genes exhibited long-term suppression, and (3) infection-related immune pathways were associated with microbiome shifts. In summary, this study reveals conserved and distinct immune disruptions occurring and details a roadmap for potential countermeasures to preserve astronaut health. Multiple omics platforms and deep single-cell profiling in the I4 astronauts reveal both conserved and distinct immune system disruptions across missions, provide a single-cell immune reference for future missions.

The “gut-brain axis” is emerging as an important target in Alzheimer’s disease (AD). However, immunological mechanisms underlying this axis remain poorly understood. Using single-cell RNA sequencing of the colon immune compartment in the 5XFAD amyloid-β (Aβ) mouse model, we uncovered AD-associated changes in ribosomal activity, oxidative stress, and BCR/plasma cell activity. Strikingly, levels of colon CXCR4+ antibody secreting cells (ASCs) were significantly reduced. This corresponded with accumulating CXCR4+ B cells and gut-specific IgA+ cells in the brain and dura mater, respectively. Consistently, a chemokine ligand for CXCR4, CXCL12, was expressed at higher levels in 5XFAD glial cells and in in silico analyzed human brain studies, supporting altered neuroimmune trafficking. An inulin prebiotic fiber diet attenuated AD markers including Aβ plaques and overall frailty. These changes corresponded to an expansion of gut IgA+ cells and rescued peripheral Tregs levels. Our study points to a key glia-gut axis and potential targets against AD.Study Highlights ### Competing Interest StatementD.A.W. is a co-founder of Propion Inc., a company that studies gut immune interventions for aging and related diseases. Other authors of this manuscript declare no competing interests.

Chronic inflammation is considered a hallmark of aging. In a recent issue of Nature, Widjaja et al. examined genetic and pharmacologic inhibition of interleukin (IL)-11 on aging pathology and found that inhibiting IL-11 signaling increases lifespan and healthspan in mice.

Introduction: Periodontitis in patients with diabetes mellitus results in chronic inflammation, which is the central issue in developing an efficient and consistent treatment plan. Dendritic cells (DC) are antigen presenting cells that initiate the immune inflammatory responses and contribute to the pathogenesis of both diseases. In this study, we investigated the impact of hyperglycemic microenvironment on DC immunometabolism, the cell phenotypes and immunogenic functions. Methodology: Human monocyte differentiated DC and mice bone marrow derived DC were cultured in the presence of 5.5-, 11-, and 25- mM glucose to simulate diabetic microenvironment. Cells were activated with advanced-glycation-end product (AGE) and lipopolysaccharides (LPS) from Porphyromanas gingivalis for 24 hours and processed for transcription, metabolic and microscopic analysis. Expression of activation markers (CD80, CD83, CD86, HLA-DR) and proteins involved in glycolysis (HK2, LDHA, GLUT1) in DC were calculated by qRT-PCR. Lactic acid production and OXPHOS assays, including Seahorse metabolic flux analyzer were utilized to determine the effects on metabolism. Impact on the phagocytic capacity was analyzed using fluorescent microspheres uptake. Cytokine expressions for tumor necrosis factor alpha [TNF- α ], interleukin [IL]-1 β , IL-6, IL-10, and Interferon gamma [IFN- γ ] were evaluated in cell supernatants from DC and DC-T cell coculture. Results: Under simulated hyperglycemic microenvironment an increase in cell dendrite extensions, and activation markers were upregulated in both monocytes differentiated DC and BMDC. There was a significant increase in glycolysis as evident from the gene expression, cell metabolic flux, and lactic acid production. Cell OXPHOS activities was reduced to compensate for the increase in glycolysis. Pro-inflammatory cytokines (TNF- α and IL-1 β ) were significantly increased and this increase was directly proportional to the glucose concentrations. Whereas, phagocytic capability of DC, and their ability to activate T cells decreased with hyperglycemia. Conclusions: Hyperglycemic microenvironment resulted in DC changes with increased expressions of activation markers, glycolytic metabolism, and increased pro-inflammatory cytokines, while impairing phagocytosis and adaptive immunity induction. BMDC and human monocyte differentiated-DC exhibit similar responses toward hyperglycemia, AGE, and LPS. This work emphasizes that diabetes mellitus has an inflammatory impact on DC immunometabolism and immunogenic functions.

The recent acceleration of commercial, private and multi-national spaceflight has created an unprecedented level of activity in low Earth orbit, concomitant with the largest-ever number of crewed missions entering space and preparations for exploration-class (lasting longer than one year) missions. Such rapid advancement into space from many new companies, countries and space-related entities has enabled a 'second space age'. This era is also poised to leverage, for the first time, modern tools and methods of molecular biology and precision medicine, thus enabling precision aerospace medicine for the crews. The applications of these biomedical technologies and algorithms are diverse, and encompass multi-omic, single-cell and spatial biology tools to investigate human and microbial responses to spaceflight. Additionally, they extend to the development of new imaging techniques, real-time cognitive assessments, physiological monitoring and personalized risk profiles tailored for astronauts. Furthermore, these technologies enable advancements in pharmacogenomics, as well as the identification of novel spaceflight biomarkers and the development of corresponding countermeasures. In this Perspective, we highlight some of the recent biomedical research from the National Aeronautics and Space Administration, Japan Aerospace Exploration Agency, European Space Agency and other space agencies, and detail the entrance of the commercial spaceflight sector (including SpaceX, Blue Origin, Axiom and Sierra Space) into aerospace medicine and space biology, the first aerospace medicine biobank, and various upcoming missions that will utilize these tools to ensure a permanent human presence beyond low Earth orbit, venturing out to other planets and moons.

Obesity has been implicated in the rise of autoimmunity in women. We report that obesity induces a serum protein signature that is associated with T helper 1 (Th1), interleukin (IL)-17, and multiple sclerosis (MS) signaling pathways selectively in human females. Females, but not male mice, subjected to diet-induced overweightness/obesity (DIO) exhibited upregulated Th1/IL-17 inflammation in the central nervous system during experimental autoimmune encephalomyelitis, a model of MS. This was associated with worsened disability and a heightened expansion of myelin-specific Th1 cells in the peripheral lymphoid organs. Moreover, at steady state, DIO increased serum levels of interferon (IFN)-α and potentiated STAT1 expression and IFN-γ production by naive CD4+ T cells uniquely in female mice. This T cell phenotype was driven by increased adiposity and was prevented by the removal of ovaries or knockdown of the type I IFN receptor in T cells. Our findings offer a mechanistic explanation of how obesity enhances autoimmunity.