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AGED CD8+ T CELLS DRIVE COGNITIVE DECLINE VIA GZMK [transfer]

ABSTRACT: Changes in peripheral CD8+ T cells are a prominent hallmark of immune aging. While infiltrating CD8+ T cells are implicated in aging and neurodegenerative disease-related pathology in the brain, the role of aged non-infiltrating CD8+ T cells has yet to be fully defined. Here, we show that targeting activated aged peripheral CD8+ T cells rescues age-related cognitive decline. Using heterochronic parabiosis and single cell transcriptomics analysis we observed that aged peripheral CD8+ T cells maintain properties intrinsic to their age, being refractory to the effects of a young or aged systemic milieu. Systemic exposure of young mice to aged CD8+ T cells elicited synaptic-related aging transcriptional signatures in the hippocampus and impaired cognition. Inhibiting migration of aged peripheral CD8+ T cells to lymph nodes mitigated pro-aging effects on the young hippocampus. Conversely, targeting aged CD8+ T cells restored synaptic-related signatures in the aged hippocampus and ameliorated cognitive impairments. Mechanistically, we identified granzyme k (GZMK) as a secreted age-associated CD8+ T cell-derived factor that impairs cognitive function. Together, our data identify activated aged CD8+ T cells and their secreted factors as potential therapeutic targets to rescue cognition in old age.

ORGANISM(S): Mus musculus

PROVIDER: GSE266468 | GEO | 2025/05/02

REPOSITORIES: GEO

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Project description:Metabolic, mitochondrial and behavioral correlations with transcriptional profiles from the CA1 and DG hippocampal regions of young and aged rhesus macaque. Increasing evidence indicates that obesity correlates with impaired cognitive performance during normal aging and is a major risk factor for Alzheimer’s disease. However, little is known regarding how peripheral metabolic variables affect cellular pathways in brain regions important for memory. Brain inflammation, mitochondrial dysregulation, and altered transcriptional regulation have all been found to occur with aging, and recent microarray analyses in rodent models have linked these processes and others to age-related memory impairment. However, whether these brain changes are also associated with metabolic variables is not known. Aging monkeys exhibit several metabolic changes similar to those seen in humans. Here, we tested peripheral-brain relationships in six young (7.0 +/- 0.3 years) and six aged (23.5 +/- 0.7 years) female rhesus monkeys. Animal cognition was gauged with a variable delay task; blood constituents were assessed with a serum chemistry panel emphasizing markers of metabolic dysfunction; mitochondrial function was measured from the hippocampus of one hemisphere; and the CA1 and dentate gyrus regions of the other hippocampus were dissected out for gene expression microarray analysis. Aged animals showed reduced performance on the behavioral task, exhibited aspects of metabolic dysregulation including increased insulin, triglyceride, and chylomicron levels (consolidated into a peripheral metabolic index), and showed a significant age-related reduction in State III oxidation, a measure of mitochondrial function. Microarray analyses revealed hundreds of genes that correlated with the peripheral metabolic index. However, DAVID statistical pathway analyses showed that upregulated inflammatory genes in CA1 and downregulated transcriptional regulation genes in dentate gyrus and CA1 were particularly overrepresented among genes correlated with the peripheral index. Thus, the association of metabolic variables with specific neuropathological processes in different regions of the hippocampal formation may have implications for mechanisms through which peripheral metabolism alters the risk for Alzheimer’s disease. Keywords: Rhesus hippocampal aging

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AGED CD8+ T CELLS DRIVE COGNITIVE DECLINE VIA GZMK [transfer]

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