Cytotoxic CD4 + T Cells Eliminate Senescent Cells by Targeting Commensal Cytomegalovirus Antigen

SSRN Electronic Journal

2022 May 27

Hasegawa, T;Oka, T;Son, H;Azin, M;Eisenhaure, T;Lieb, D;Hacohen, N;Demehri, S;
| DOI: 10.2139/ssrn.4102631

Senescent cell accumulation has been implicated in the pathogenesis of aging-associated diseases including cancer. The mechanism that prevents the accumulation of senescent cells in aging human organs is unclear. Here, we demonstrate that a commensal virus-immune axis controls the senescent fibroblast accumulation in the human skin. Senescent fibroblasts increased in old compared with young skin. However, they did not increase with advancing age in elderly. Increased CXCL9 and cytotoxic CD4+ T cell (CD4 CTL) recruitment were significantly associated with reduced senescent fibroblasts in the old skin. Senescent fibroblasts expressed human leukocyte antigen class II (HLA-II) and human cytomegalovirus glycoprotein B (HCMV-gB), becoming direct CD4 CTL targets. Skin-resident CD4 CTL eliminated HCMV-gB+ senescent fibroblasts in an HLA-II-dependent manner and HCMV-gB activated CD4 CTL from the human skin. Collectively, our findings demonstrate HCMV reactivation in senescent cells, which can be directly eliminated by CD4 CTL through the recognition of the HCMV-gB antigen.

BS18 Enhanced matrix stiffness prevents vsmc contractility: how calcium signalling and microtubule stability regulate vascular compliance during ageing

Basic science

2022 Jun 01

Johnson, R;Ahmed, S;Solanki, R;Wostear, F;Afewerki, T;Warren, D;
| DOI: 10.1136/heartjnl-2022-bcs.198

Rationale DNA damage accumulation is a hallmark of vascular smooth muscle cell (VSMC) ageing. Importantly, VSMC DNA damage accumulation and ageing has been implicated in the progression of cardiovascular disease (CVD), including atherosclerosis and vascular calcification. Chemotherapy drugs used in the treatment of many cancers are known to induce DNA damage in cardiovascular cells and accelerate CVD. Histone deacetylase (HDAC) inhibitors are drugs being investigated for novel treatments of many cancers. HDACs perform many vital functions in cells; HDAC6 is known to deacetylate alpha-tubulin to regulate microtubule stability and flexibility. We have recently shown that microtubule stability regulates both VSMC morphology and contractility. Therefore, in this study we investigate the impact of HDAC6 inhibition upon VSMC function. Methodology We use polyacrylamide hydrogels (PAHs)

Aging alters mechanisms underlying voluntary movements in spinal motor neurons of mice, primates, and humans

JCI insight

2023 May 08

Castro, RW;Lopes, MC;Settlage, RE;Valdez, G;
PMID: 37154159 | DOI: 10.1172/jci.insight.168448

Spinal motor neurons have been implicated in the loss of motor function that occurs with advancing age. However, the cellular and molecular mechanisms that impair the function of these neurons during aging remain unknown. Here, we show that motor neurons do not die in old female and male mice, rhesus monkeys, and humans. Instead, these neurons selectively and progressively shed excitatory synaptic inputs throughout the soma and dendritic arbor during aging. Thus, aged motor neurons contain a motor circuitry with a reduced ratio of excitatory to inhibitory synapses that may be responsible for the diminished ability to activate motor neurons to commence movements. An examination of the motor neuron translatome (ribosomal transcripts) in male and female mice reveals genes and molecular pathways with roles in glia-mediated synaptic pruning, inflammation, axonal regeneration, and oxidative stress that are upregulated in aged motor neurons. Some of these genes and pathways are also found altered in motor neurons affected with amyotrophic lateral sclerosis (ALS) and responding to axotomy, demonstrating that aged motor neurons are under significant stress. Our findings show mechanisms altered in aged motor neurons that could serve as therapeutic targets to preserve motor function during aging.

Age-dependent dysregulation of locus coeruleus firing in a transgenic rat model of Alzheimer's disease

Neurobiology of Aging

2023 Feb 01

Kelberman, M;Rorabaugh, J;Anderson, C;Marriott, A;DePuy, S;Rasmussen, K;McCann, K;Weiss, J;Weinshenker, D;
| DOI: 10.1016/j.neurobiolaging.2023.01.016

Hyperphosphorylated tau in the locus coeruleus (LC) is ubiquitous in prodromal Alzheimer's disease (AD), and LC neurons degenerate as AD progresses. Hyperphosphorylated tau alters firing rates in other brain regions, but its effects on LC neurons are unknown. We assessed single unit LC activity in anesthetized wild-type (WT) and TgF344-AD rats at 6 months, which represents a prodromal stage when LC neurons are the only cells containing hyperphosphorylated tau in TgF344-AD animals, and at 15 months when β-amyloid (Aβ) and tau pathology are both abundant in the forebrain. At baseline, LC neurons from TgF344-AD rats were hypoactive at both ages compared to WT littermates but showed elevated spontaneous bursting properties. Differences in footshock-evoked LC firing depended on age, with 6-month TgF344-AD rats demonstrating aspects of hyperactivity, and 15-month transgenic rats showing hypoactivity. Early LC hyperactivity is consistent with appearance of prodromal neuropsychiatric symptoms and is followed by LC hypoactivity which contributes to cognitive impairment. These results support further investigation into disease stage-dependent noradrenergic interventions for AD.

Rejuvenation of the aged brain immune cell landscape in mice through p16-positive senescent cell clearance

Nature communications

2022 Sep 27

Zhang, X;Pearsall, VM;Carver, CM;Atkinson, EJ;Clarkson, BDS;Grund, EM;Baez-Faria, M;Pavelko, KD;Kachergus, JM;White, TA;Johnson, RK;Malo, CS;Gonzalez-Suarez, AM;Ayasoufi, K;Johnson, KO;Tritz, ZP;Fain, CE;Khadka, RH;Ogrodnik, M;Jurk, D;Zhu, Y;Tchkonia, T;Revzin, A;Kirkland, JL;Johnson, AJ;Howe, CL;Thompson, EA;LeBrasseur, NK;Schafer, MJ;
PMID: 36167854 | DOI: 10.1038/s41467-022-33226-8

Cellular senescence is a plausible mediator of inflammation-related tissue dysfunction. In the aged brain, senescent cell identities and the mechanisms by which they exert adverse influence are unclear. Here we used high-dimensional molecular profiling, coupled with mechanistic experiments, to study the properties of senescent cells in the aged mouse brain. We show that senescence and inflammatory expression profiles increase with age and are brain region- and sex-specific. p16-positive myeloid cells exhibiting senescent and disease-associated activation signatures, including upregulation of chemoattractant factors, accumulate in the aged mouse brain. Senescent brain myeloid cells promote peripheral immune cell chemotaxis in vitro. Activated resident and infiltrating immune cells increase in the aged brain and are partially restored to youthful levels through p16-positive senescent cell clearance in female p16-InkAttac mice, which is associated with preservation of cognitive function. Our study reveals dynamic remodeling of the brain immune cell landscape in aging and suggests senescent cell targeting as a strategy to counter inflammatory changes and cognitive decline.

Vasculature atrophy causes a stiffened microenvironment that augments epidermal stem cell differentiation in aged skin

Nature Aging

2022 Jul 01

Ichijo, R;Maki, K;Kabata, M;Murata, T;Nagasaka, A;Ishihara, S;Haga, H;Honda, T;Adachi, T;Yamamoto, T;Toyoshima, F;
| DOI: 10.1038/s43587-022-00244-6

Stem cell loss causes tissue deterioration associated with aging. The accumulation of genomic and oxidative stress-induced DNA damage is an intrinsic cue for stem cell loss1 [/articles/s43587-022-00244-6#ref-CR1],2 [/articles/s43587-022-00244-6#ref-CR2]; however, whether there is an external microenvironmental cue that triggers stem cell loss remains unclear. Here we report that the involution of skin vasculature causes dermal stiffening that augments the differentiation and hemidesmosome fragility of interfollicular epidermal stem cells (IFESCs) in aged mouse skin. Aging-related IFESC dysregulation occurs in plantar and tail skin, and is correlated with prolonged calcium influx, which is contributed by the mechanoresponsive ion channel Piezo1 (ref. 3 [/articles/s43587-022-00244-6#ref-CR3]). Epidermal deletion of Piezo1 ameliorated IFESC dysregulation in aged skin, whereas Piezo1 activation augmented IFESC differentiation and hemidesmosome fragility in young mice. The dermis stiffened with age, which was accompanied by dermal vasculature atrophy. Conversely, induction of the dermal vasculature softened the dermis and ameliorated IFESC dysregulation in aged skin. Single-cell RNA sequencing of dermal fibroblasts identified an aging-associated anti-angiogenetic secretory molecule, pentraxin 3 (ref. 4 [/articles/s43587-022-00244-6#ref-CR4]), which caused dermal sclerotization and IFESC dysregulation in aged skin. Our findings show that the vasculature softens the microenvironment for stem cell maintenance and provide a potential mechanobiology-based therapeutic strategy against skin disorders in aging.

Protein phosphatase 2A activators reverse age-related behavioral changes by targeting neural cell senescence

Aging cell

2023 Jan 16

Xing, J;Chen, K;Gao, S;Pousse, M;Ying, Y;Wang, B;Chen, L;Wang, C;Wang, L;Hu, W;Lu, Y;Gilson, E;Ye, J;
PMID: 36644807 | DOI: 10.1111/acel.13780

The contribution of cellular senescence to the behavioral changes observed in the elderly remains elusive. Here, we observed that aging is associated with a decline in protein phosphatase 2A (PP2A) activity in the brains of zebrafish and mice. Moreover, drugs activating PP2A reversed age-related behavioral changes. We developed a transgenic zebrafish model to decrease PP2A activity in the brain through knockout of the ppp2r2c gene encoding a regulatory subunit of PP2A. Mutant fish exhibited the behavioral phenotype observed in old animals and premature accumulation of neural cells positive for markers of cellular senescence, including senescence-associated β-galactosidase, elevated levels cdkn2a/b, cdkn1a, senescence-associated secretory phenotype gene expression, and an increased level of DNA damage signaling. The behavioral and cell senescence phenotypes were reversed in mutant fish through treatment with the senolytic ABT263 or diverse PP2A activators as well as through cdkn1a or tp53 gene ablation. Senomorphic function of PP2A activators was demonstrated in mouse primary neural cells with downregulated Ppp2r2c. We conclude that PP2A reduction leads to neural cell senescence thereby contributing to age-related behavioral changes and that PP2A activators have senotherapeutic properties against deleterious behavioral effects of brain aging.

Single-cell analysis of the aging female mouse hypothalamus

Nature Aging

2022 Jul 01

Hajdarovic, K;Yu, D;Hassell, L;Evans, S;Packer, S;Neretti, N;Webb, A;
| DOI: 10.1038/s43587-022-00246-4

Alterations in metabolism, sleep patterns, body composition and hormone status are all key features of aging. While the hypothalamus is a well-conserved brain region that controls these homeostatic and survival-related behaviors, little is known about the intrinsic features of hypothalamic aging. Here, we perform single-nuclei RNA sequencing of 40,064 hypothalamic nuclei from young and aged female mice. We identify cell type-specific signatures of aging in neuronal subtypes as well as astrocytes and microglia. We uncover changes in cell types critical for metabolic regulation and body composition and in an area of the hypothalamus linked to cognition. Our analysis also reveals an unexpected female-specific feature of hypothalamic aging: the master regulator of X inactivation, Xist, is elevated with age, particularly in hypothalamic neurons. Moreover, using machine learning, we show that levels of X chromosome genes and Xist itself, can accurately predict cellular age. This study identifies critical cell-specific changes of the aging hypothalamus in mammals and uncovers a potential marker of neuronal aging in females.

Multispectral LEDs Eliminate Lipofuscin-Associated Autofluorescence for Immunohistochemistry and CD44 Variant Detection by in Situ Hybridization in Aging Human, non-Human Primate, and Murine Brain

ASN neuro

2022 Sep 27

Adeniyi, PA;Fopiano, KA;Banine, F;Garcia, M;Gong, X;Keene, CD;Sherman, LS;Bagi, Z;Back, SA;
PMID: 36164936 | DOI: 10.1177/17590914221123138

A major limitation of mechanistic studies in aging brains is the lack of routine methods to robustly visualize and discriminate the cellular distribution of tissue antigens using fluorescent immunohistochemical multi-labeling techniques. Although such approaches are routine in non-aging brains, they are not consistently feasible in the aging brain due to the progressive accumulation of autofluorescent pigments, particularly lipofuscin, which strongly excite and emit over a broad spectral range. Consequently, aging research has relied upon colorimetric antibody techniques, where discrimination of tissue antigens is often challenging. We report the application of a simple, reproducible, and affordable protocol using multispectral light-emitting diodes (mLEDs) exposure for the reduction/elimination of lipofuscin autofluorescence (LAF) in aging brain tissue from humans, non-human primates, and mice. The mLEDs lamp has a broad spectral range that spans from the UV to infrared range and includes spectra in the violet/blue and orange/red. After photo quenching, the LAF level was markedly reduced when the tissue background fluorescence before and after mLEDs exposure was compared (p < 0.0001) across the spectral range. LAF elimination was estimated at 95 ± 1%. This approach permitted robust specific fluorescent immunohistochemical co-visualization of commonly studied antigens in aging brains. We also successfully applied this method to specifically visualize CD44 variant expression in aging human cerebral white matter using RNAscope fluorescent in-situ hybridization. Photo quenching provides an attractive means to accelerate progress in aging research by increasing the number of molecules that can be topologically discriminated by fluorescence detection in brain tissue from normative or pathological aging.

Repopulated microglia induce expression of Cxcl13 with differential changes in Tau phosphorylation but do not impact amyloid pathology

Journal of neuroinflammation

2022 Jul 04

Karaahmet, B;Le, L;Mendes, MS;Majewska, AK;O'Banion, MK;
PMID: 35787714 | DOI: 10.1186/s12974-022-02532-9

Adult microglia rely on self-renewal through division to repopulate and sustain their numbers. However, with aging, microglia display morphological and transcriptional changes that reflect a heightened state of neuroinflammation. This state threatens aging neurons and other cells and can influence the progression of Alzheimer's disease (AD). In this study, we sought to determine whether renewing microglia through a forced partial depletion/repopulation method could attenuate AD pathology in the 3xTg and APP/PS1 mouse models.We pharmacologically depleted the microglia of two cohorts of 21- to 22-month-old 3xTg mice and one cohort of 14-month-old APP/PS1 mice using PLX5622 formulated in chow for 2 weeks. Following depletion, we returned the mice to standard chow diet for 1 month to allow microglial repopulation. We assessed the effect of depletion and repopulation on AD pathology, microglial gene expression, and surface levels of homeostatic markers on microglia using immunohistochemistry, single-cell RNAseq and flow cytometry.Although we did not identify a significant impact of microglial repopulation on amyloid pathology in either of the AD models, we observed differential changes in phosphorylated-Tau epitopes after repopulation in the 3xTg mice. We provide evidence that repopulated microglia in the hippocampal formation exhibited changes in the levels of homeostatic microglial markers. Lastly, we identified novel subpopulations of microglia by performing single-cell RNAseq analysis on CD45int/+ cells from hippocampi of control and repopulated 3xTg mice. In particular, one subpopulation induced after repopulation is characterized by heightened expression of Cxcl13.Overall, we found that depleting and repopulating microglia causes overexpression of microglial Cxcl13 with disparate effects on Tau and amyloid pathologies.

Editorial: Cognitive and Motor Control Based on Brain-Computer Interfaces for Improving the Health and Well-Being in Older Age

Frontiers in human neuroscience

2022 Apr 06

Belkacem, AN;Falk, TH;Yanagisawa, T;Guger, C;
PMID: 35463924 | DOI: 10.3389/fnhum.2022.881922

Human striatal glia differentially contribute to AD- and PD-specific neurodegeneration

Nature Aging

2023 Feb 09

Xu, J;Farsad, H;Hou, Y;Barclay, K;Lopez, B;Yamada, S;Saliu, I;Shi, Y;Knight, W;Bateman, R;Benzinger, T;Yi, J;Li, Q;Wang, T;Perlmutter, J;Morris, J;Zhao, G;
| DOI: 10.1038/s43587-023-00363-8

A, Upset plot showing the overlap between putamen conserved marker genes of Ast-0, Ast-1 and Ast-2 astrocyte with marker genes of mouse DAA and Gfap-high astrocytes from Habib et al., 2020. B, Violin plots showing the expression level distributions of orthologous genes of murine DAA and Gfap-high astrocyte marker genes in the putamen astrocytes. C, PCA plot using murine DAA and Gfap-high astrocyte marker gene logFC of gene expression (comparing murine DAA and Gfap-high astrocyte with Gfap-low astrocytes, downloaded from Habib et al., 2020) and the logFC of the human orthologous genes (comparing putamen Ast-1 and Ast-2 with Ast-0 astrocytes). D,E, Violin plots showing the expression level distributions of reactive astrocyte marker genes in astrocytes from the (D) putamen and (E) prefrontal cortex. F, Violin plots showing the expression level distributions of A1-, A2-specific activated astrocyte markers and JAK-STAT3 pathway genes. G, Top 10 GO terms in the Biological Process category enriched in the astrocyte subpopulation signature genes (hypergeometric test, FDR-adjusted P value < 0.05, ≥ 5 query genes). Conserved marker genes plotted in panel (B), (D) and (E) were determined by FindConservedMarkers using Wilcoxon Rank Sum test and _metap_ R package with meta-analysis combined P value < 0.05 comparing gene expression in the given cluster with the other cell clusters for AD (n = 4), PD (n = 4) and the controls (n = 4). Genes plotted in (F) were not statistically significantly higher in any of the astrocyte subpopulations.

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	Description
sense Example: Hs-LAG3-sense	Standard probes for RNA detection are in antisense. Sense probe is reverse complent to the corresponding antisense probe.
Intron# Example: Mm-Htt-intron2	Probe targets the indicated intron in the target gene, commonly used for pre-mRNA detection
Pool/Pan Example: Hs-CD3-pool (Hs-CD3D, Hs-CD3E, Hs-CD3G)	A mixture of multiple probe sets targeting multiple genes or transcripts
No-XSp Example: Hs-PDGFB-No-XMm	Does not cross detect with the species (Sp)
XSp Example: Rn-Pde9a-XMm	designed to cross detect with the species (Sp)
O# Example: Mm-Islr-O1	Alternative design targeting different regions of the same transcript or isoforms
CDS Example: Hs-SLC31A-CDS	Probe targets the protein-coding sequence only
EnEm	Probe targets exons n and m
En-Em	Probe targets region from exon n to exon m
Retired Nomenclature
tvn Example: Hs-LEPR-tv1	Designed to target transcript variant n
ORF Example: Hs-ACVRL1-ORF	Probe targets open reading frame
UTR Example: Hs-HTT-UTR-C3	Probe targets the untranslated region (non-protein-coding region) only
5UTR Example: Hs-GNRHR-5UTR	Probe targets the 5' untranslated region only
3UTR Example: Rn-Npy1r-3UTR	Probe targets the 3' untranslated region only
Pan Example: Pool	A mixture of multiple probe sets targeting multiple genes or transcripts

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