Aging Cell最新文献

Senescence is a cell fate associated with age-related pathologies; however, senescence markers are not well-defined. Using single cell multi-isotope imaging mass spectrometry (MIMS), we identified hypercondensed, transcriptionally silent DNA globules in a senescence model induced by dysfunctional telomeres. This architectural phenomenon was associated with geographically clustered transcriptional repression across somatic chromosomes with over-representation of cell cycle genes. Senescence-stimuli was associated with a higher frequency of cells that exhibited geographically concentrated transcriptional repression relative to control cells. This phenomenon was also observed in multiple other senescence models, including replicative senescence and irradiation. We further identified an enrichment of common pathways in all models of senescence, suggesting a common cellular response to this silencing phenomenon. Such large-scale clustered silencing of chromosomal segments rather than individual genes may explain senescence heterogeneity and a putative trajectory toward deep, irreversible senescence.

The mechanistic target of rapamycin (mTOR) complexes 1 and 2 (mTORC1/2) are crucial for various physiological functions. Although the role of mTORC1 in retinal pigmented epithelium (RPE) homeostasis and age-related macular degeneration (AMD) pathogenesis is established, the function of mTORC2 remains unclear. We investigated both complexes in RPE health and disease. Therefore, in this study, we have attempted to demonstrate that the specific overexpression of mammalian lethal with Sec13 protein 8 (mLST8) in the mouse RPE activates both mTORC1 and mTORC2, inducing epithelial-mesenchymal transition (EMT)-like changes and subretinal/RPE deposits resembling early AMD-like pathogenesis. Aging in these mice leads to RPE degeneration, causing retinal damage, impaired debris clearance, and metabolic and mitochondrial dysfunction. Inhibition of mTOR with TORIN1 in vitro or βA3/A1-crystallin in vivo normalized mTORC1/2 activity and restored function, revealing a novel role for the mTOR complexes in regulating RPE function, impacting retinal health and disease.

Toll-like receptor 5 (TLR5) plays a critical role beyond its traditional function in innate immunity, significantly impacting metabolic regulation and liver health. Previously, we reported that TLR5 activation extends the healthspan and lifespan of aging mice. This study demonstrates that TLR5 deficiency leads to pronounced metabolic abnormalities with age, primarily affecting liver metabolic functions rather than intestinal inflammation. Comprehensive RNA sequencing analysis revealed that TLR5 deficiency induces gene expression changes in liver tissue similar to those caused by the methionine-choline deficient (MCD) diet, particularly affecting lipid metabolism and circadian rhythm-related genes. TLR5 knockout (TLR5 KO) mice displayed an increased propensity for liver fibrosis and lipid accumulation under the MCD diet, exacerbating liver pathology. Both hepatocytes and hepatic stellate cells in TLR5 KO mice were functionally impacted, leading to metabolic dysfunction and fibrosis. These findings suggest that TLR5 could be a significant target for addressing metabolic diseases that arise and worsen with aging. Furthermore, understanding the mechanisms by which TLR5 activation extends healthspan could provide valuable insights into therapeutic strategies for enhancing longevity and managing age-related metabolic disorders.

Ageing is an inevitable biological process that impacts the immune system, leading to immunosenescence and inflammaging, which contribute to increased susceptibility to infections, autoimmune diseases and cancers in individuals over the age of 65. This review focuses on the ageing of lymph node stromal cells (LNSCs), which are crucial for maintaining lymph node (LN) structure and function. Age-related changes in LNs, such as fibrosis and lipomatosis, disrupt the LN architecture and reduce immune cell recruitment and function, impairing immune responses to infections and vaccinations. The review discusses the structural and functional decline of various LNSC subsets, including fibroblastic reticular cells (FRCs), lymphatic endothelial cells (LECs) and blood endothelial cells (BECs), highlighting their roles in immune cell activation and homeostasis. Potential strategies to restore aged LNSC function, such as enhancing LNSC activation during vaccination and using senotherapeutics, are explored. Outstanding questions regarding the mechanisms of LNSC ageing and how ageing of the LN stroma might impact autoimmune disorders are also addressed. This review aims to stimulate further research into the characterisation of aged LNSCs and the development of therapeutic interventions to improve immune function in the older adults.

The dysfunction of the dopaminergic projection from the ventral tegmental area (VTA) to the medial prefrontal cortex (mPFC) is believed to play a key role in the pathophysiology of Parkinson's disease (PD) accompanied by executive dysfunction (EDF). In this study, we identified an abnormal increase in lysophosphatidylcholine (LPC) levels in PD patients, which closely correlates with the severity of cognitive impairment. LPC disrupts the miR-2885/TDP-43 signaling pathway in microglia, driving dopaminergic presynaptic engulfment. In LPC-exposed mice, microglial activation via miR-2885/TDP-43/p65 signaling led to inflammatory cytokine and complement release, marking dopaminergic synapses for phagocytosis with a "PS/C1q" signal. Following the inhibition of LPC-induced microglial activation through chemogenetic methods, we observed a significant reduction in the phagocytosis of dopaminergic synapses, resulting in improved executive function. The miR-2885 disrupted LPC-induced dopaminergic phagocytosis and alleviated EDF. Furthermore, the accumulation of excessive TDP-43 due to the loss of miR-2885 promoted the engulfment of dopaminergic synapses by facilitating the entry of p65 into the nucleus. Inhibiting TDP-43 levels effectively mitigated LPC-induced EDF. Additionally, supplementing dopamine receptor agonists enhanced the excitability of regional glutamatergic neurons, leading to improved executive function. In summary, LPC exposure in the mPFC impairs microglial regulation, leading to dopaminergic synaptic loss and underactivity of glutamatergic neurons. These changes drive the development of executive dysfunction in PD.

Visual function deteriorates throughout the natural course of aging. Age-related structural and functional adaptations are observed in the retina, the light-sensitive neuronal tissue of the eye where visual perception begins. Molecular mechanisms underlying retinal aging are still poorly understood, highlighting the need to identify biomarkers for better prognosis and alleviation of aging-associated vision impairment. Here, we investigate dynamics of transcriptional dysregulation in the retina and identify affected pathways within distinct retinal cell types. Using an optimized protocol for single-cell RNA sequencing of mouse retinas at 3, 12, 18, and 24 months, we detect a progressive increase in the number of differentially expressed genes across all retinal cell types. The extent and direction of expression changes varies, with photoreceptor, bipolar, and Müller cells showing the maximum number of differentially expressed genes at all age groups. Furthermore, our analyses uncover transcriptionally distinct, heterogeneous subpopulations of rod photoreceptors and bipolar cells, distributed across distinct areas of the retina. Our findings provide a plausible molecular explanation for enhanced susceptibility of rod cells to aging and correlate with the observed loss of scotopic sensitivity in elderly individuals.

The study of biomarkers in biofluids and tissues expanded our understanding of the biological processes that drive physiological and functional manifestations of aging. However, most of these studies were limited to examining one biological compartment, an approach that fails to recognize that aging pervasively affects the whole body. The simultaneous modeling of hundreds of metabolites and proteins across multiple compartments may provide a more detailed picture of healthy aging and point to differences between chronological and biological aging. Herein, we report proteomic analyses of plasma and urine collected in healthy men and women, age 22-92 years. Using these data, we developed a series of metabolomic and proteomic predictors of chronological age for plasma, urine, and skeletal muscle. We then defined a biological aging score, which measures the departure between an individual's predicted age and the expected predicted age for that individual based on the full cohort. We show that these predictors are significantly and independently related to clinical phenotypes important for aging, such as inflammation, iron deficiency anemia, muscle mass, and renal and hepatic functions. Despite a different set of selected biomarkers in each compartment, the different scores reflect a similar degree of deviation from healthy aging in single individuals, thus allowing identification of subjects with significant accelerated or decelerated biological aging.

Idiopathic pulmonary fibrosis (IPF) is an age-associated disease characterized by the irreversible accumulation of excessive extracellular matrix components by activated myofibroblasts (aMYFs). Following bleomycin administration in young mice, fibrosis formation associated with efficient resolution takes place limiting the clinical relevance of this model for IPF. In this study, we used aged mice in combination with bleomycin administration to trigger enhanced fibrosis formation and delayed resolution as a more relevant model for IPF. Alveolosphere assays were carried out to compare the alveolar resident mesenchymal niche activity for AT2 stem cells in young versus old mice. Lineage tracing of the Acta2+ aMYFs in old mice exposed to bleomycin followed by scRNAseq of the lineage-traced cells isolated during fibrosis formation and resolution was performed to delineate the heterogeneity of aMYFs during fibrosis formation and their fate during resolution. Integration of previously published similar scRNAseq results using young mice was carried out. Our results show that alveolar resident mesenchymal cells from old mice display decreased supporting activity for AT2 stem cells. Our findings suggest that the cellular and molecular mechanisms underlying the aMYFs formation and differentiation towards the Lipofibroblast phenotype are mostly conserved between young and old mice. In addition to persistent fibrotic signaling in aMYF from old mice during resolution, we also identified differences linked to interleukin signaling in old versus young alveolar fibroblast populations before and during bleomycin injury. Importantly, our work confirms the relevance of a subcluster of aMYFs in old mice that is potentially relevant for future management of IPF.

As global life expectancy increases, the focus has shifted from merely extending lifespan to promoting healthy aging. GSTA1, GSTA2, and GSTA3 (GSTA1-3), members of the alpha class of glutathione S-transferases, are involved in diverse biological processes, including metabolism and immune regulation, highlighting their potential influence on human health span and lifespan. In this study, we employed Caenorhabditis elegans as a model organism to investigate the role of gst-35, an ortholog of mammalian GSTA1-3, in healthy aging. Our results demonstrated that gst-35 overexpression has detrimental effects on multiple physiological functions in nematodes. Specifically, gst-35 overexpression significantly reduced lifespan, impaired development and growth, and substantially diminished reproductive capacity, physical fitness, and stress resistance. In contrast, gst-35 knockout partially enhanced physical fitness and stress resistance. Comprehensive RNA-sequencing transcriptome analysis revealed that gst-35 overexpression disrupted metabolic homeostasis and induced lysosomal dysfunction. These effects were mediated through the activation of the pmk-1 signaling pathway and suppression of skr genes, which collectively impaired healthy aging processes. These findings illuminate the complex role of gst-35 in aging and provide valuable insights into the molecular mechanisms underlying healthy aging, offering potential targets for interventions aimed at promoting health span.