Sexually dimorphic induction of microglial-associated neuroinflammation with hippocampal aging
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE85084 | GEO | 2017/01/10
SECONDARY ACCESSION(S): PRJNA336106
REPOSITORIES: GEO
Similar Datasets
Project description:BACKGROUND:The necessity of including both males and females in molecular neuroscience research is now well understood. However, there is relatively limited basic biological data on brain sex differences across the lifespan despite the differences in age-related neurological dysfunction and disease between males and females. METHODS:Whole genome gene expression of young (3 months), adult (12 months), and old (24 months) male and female C57BL6 mice hippocampus was analyzed. Subsequent bioinformatic analyses and confirmations of age-related changes and sex differences in hippocampal gene and protein expression were performed. RESULTS:Males and females demonstrate both common expression changes with aging and marked sex differences in the nature and magnitude of the aging responses. Age-related hippocampal induction of neuroinflammatory gene expression was sexually divergent and enriched for microglia-specific genes such as complement pathway components. Sexually divergent C1q protein expression was confirmed by immunoblotting and immunohistochemistry. Similar patterns of cortical sexually divergent gene expression were also evident. Additionally, inter-animal gene expression variability increased with aging in males, but not females. CONCLUSIONS:These findings demonstrate sexually divergent neuroinflammation with aging that may contribute to sex differences in age-related neurological diseases such as stroke and Alzheimer's, specifically in the complement system. The increased expression variability in males suggests a loss of fidelity in gene expression regulation with aging. These findings reveal a central role of sex in the transcriptomic response of the hippocampus to aging that warrants further, in depth, investigations.
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Project description:The major histocompatibility complex I (MHCI) pathway, which canonically functions in innate immune viral antigen presentation and detection, is functionally pleiotropic in the central nervous system (CNS). Alternative roles include developmental synapse pruning, regulation of synaptic plasticity, and inhibition of neuronal insulin signaling; all processes altered during brain aging. Upregulation of MHCI components with aging has been reported; however, no systematic examination of MHCI cellular localization, expression, and regulation across CNS regions, life span, and sexes has been reported. In the mouse, MHCI is expressed by neurons and microglia, and MHCI components and receptors (H2-K1, H2-D1, ?2M, Lilrb3, Klra2, CD247) display markedly different expression profiles across the hippocampus, cortex, cerebellum, brainstem, and retina. MHCI components, receptors, associated inflammatory transcripts (IL1?, IL1?, IL6, TNF?), and TAP (transporter associated with antigen processing) components are induced with aging and to a greater degree in female than male mice across CNS regions. H2-K1 and H2-D1 expression is associated with differential CG and non-CG promoter methylation across CNS regions, ages, and between sexes, and concomitant increased expression of proinflammatory genes. Meta-analysis of human brain aging data also demonstrates age-related increases in MHCI. Induction of MHCI signaling could contribute to altered synapse regulation and impaired synaptic plasticity with aging.
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Project description:Male Fischer 344 rats aged 4 months (young, n=10), 14 months (mid-aged, n=10), and 24 months (aged, n=10) were trained sequentially on two tasks: Morris Spatial Water Maze (SWM) and Object Memory Task (OMT). The training/testing sequence lasted 7 d, and hippocampal tissue was collected 24 hr later. Training and testing occured on each day except for days 2 and 3 of the 7 d sequence. (01/10/05: Series was updated to correct mislabeling of all sample signal values within the Young Treatment Group) Keywords = bioinformatics Keywords = gene expression Keywords = memory Keywords = synaptic plasticity Keywords = myelin Keywords = inflamation Keywords = aging Keywords: repeat sample
2005-01-10 | GSE854 | GEO
Project description:Microglia, the brain’s principal immune cells, have been implicated in the pathogenesis of Alzheimer’s disease (AD), a condition shown to affect more females than males. Although sex differences in microglial function and transcriptomic programming have been described across development and in disease models of AD, no studies have comprehensively identified the sex divergences that emerge in the aging mouse hippocampus. Further, existing models of AD generally develop pathology (amyloid plaques and tau tangles) early in life and fail to recapitulate the aged brain environment associated with late-onset AD. Here, we examined and compared the transcriptomic and translatomic sex effects in young and old murine hippocampal microglia. Hippocampal tissue from C57BL6/N and microglial NuTRAP mice of both sexes were collected at young (5-6 month-old [mo]) and old (22-25 mo) ages. Cell sorting and affinity purification techniques were used to isolate the microglial transcriptome and translatome for RNA-sequencing and differential expression analyses. Flow cytometry, qPCR, and imaging approaches were used to confirm the transcriptomic findings. There were marginal sex differences identified in the young hippocampal microglia, with most differentially expressed genes (DEGs) restricted to the sex chromosomes. Both sex chromosomally- and autosomally-encoded sex differences emerged with aging. These sex DEGs identified at old age were primarily female-biased and enriched in senescent and disease-associated microglial signatures. Pathway analyses identified upstream regulators induced to a greater extent in females than in males, including inflammatory mediators IFNG, TNF, and IL1B, as well as AD-risk genes TREM2 and APP. These data suggest that female microglia adopt disease-associated and senescent phenotypes in the aging mouse hippocampus, even in the absence of disease pathology, to a greater extent than males. This sexually divergent microglial phenotype may explain the difference in susceptibility and disease progression in the case of AD pathology. Future studies will need to explore sex differences in microglial heterogeneity in response to AD pathology and determine how sex-specific regulators (i.e., sex chromosomal or hormonal) elicit these sex effects.
2023-08-18 | GSE233400 | GEO
Project description:Aging is associated with low-grade chronic systemic inflammation. Elevated peripheral serum cytokines and chemokines contribute to age-related diseases and correlate with cognitive decline. This study compared the effects of repeated lipopolysaccharide (LPS) treatment in young rats to age-related changes in hippocampal-dependent cognition, synaptic transmission, and transcription. Young (5-7 months) Fischer 344 X Brown Norway hybrid rats were injected intraperitoneally once a week for 6-7 weeks with either LPS (1 mg/kg) or vehicle. Older (14-16 months) rats received a similar injection schedule of vehicle. Older-vehicle animals and young-LPS rats exhibited impaired retention of spatial memory. Examination of the transcriptome of the CA1 and the dentate gyrus indicated that older-vehicle and young-LPS animals exhibited an increase in immune response genes. In contrast to aging, young-LPS animals exhibited an increased expression of genes related to the synapse. Even though young-LPS animals increased the expression of synaptic genes, LPS treatment reduced hippocampal CA3-CA1 total synaptic response and N-methyl-D-aspartate receptor (NMDAR)-mediated component of the synaptic response. Interestingly, the decrease in NMDAR function was not redox-sensitive. This study demonstrates that repeated exposure to LPS has long-term effects on hippocampal synaptic transmission and memory; however, young animals exhibited transcriptional recovery after LPS treatment. Recovery likely results from the acute nature of repeated LPS injections, relative to chronic systemic inflammation observed during aging.
2020-11-30 | GSE140685 | GEO
Project description:DNA methylation is a central regulator of genome function, and altered methylation patterns are indicative of biological aging and mortality. Age-related cellular, biochemical, and molecular changes in the hippocampus lead to cognitive impairments and greater vulnerability to neurodegenerative disease that varies between the sexes. The role of hippocampal epigenomic changes with aging in these processes is unknown as no genome-wide analyses of age-related methylation changes have considered the factor of sex in a controlled animal model. High-depth, genome-wide bisulfite sequencing of young (3 month) and old (24 month) male and female mouse hippocampus revealed that while total genomic methylation amounts did not change with aging, specific sites in CG and non-CG (CH) contexts demonstrated age-related increases or decreases in methylation that were predominantly sexually divergent. Differential methylation with age for both CG and CH sites was enriched in intergenic and intronic regions and under-represented in promoters, CG islands, and specific enhancer regions in both sexes, suggesting that certain genomic elements are especially labile with aging, even if the exact genomic loci altered are predominantly sex-specific. Lifelong sex differences in autosomal methylation at CG and CH sites were also observed. The lack of genome-wide hypomethylation, sexually divergent aging response, and autosomal sex differences at CG sites was confirmed in human data. These data reveal sex as a previously unappreciated central factor of hippocampal epigenomic changes with aging. In total, these data demonstrate an intricate regulation of DNA methylation with aging by sex, cytosine context, genomic location, and methylation level.
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Project description:BACKGROUND: Brain aging is a multi-factorial process due to both genetic and environmental factors. The zebrafish has recently become a popular model organism for examining aging and age-related diseases because as in humans they age gradually and exhibit cognitive decline. Few studies have examined the biological changes in the aging brain that may contribute to these declines and none have examined them within individuals with respect to gender. Our aim was to identify the main genetic pathways associated with zebrafish brain aging across gender. We chose males and females from specific age groups (young, 7.5-8.5 months and old, 31-36 months) based on the progression of cognitive decline in zebrafish. RNA was isolated from individual brains and subjected to microarray and qPCR analysis. Statistical analyses were performed using a two-way ANOVA and the relevant post-hoc tests. RESULTS: Our results demonstrated that in the brains of young and old male and female zebrafish there were over 500 differentially expressed genes associated with multiple pathways but most notably were those related to neurogenesis and cell differentiation, as well as brain and nervous system development. CONCLUSIONS: The gene expression of multiple pathways is altered with age and differentially expressed in males and females. Future studies will be aimed at determining the causal relationships of age-related changes in gene expression in individual male and female brains, as well as possible interventions that counteract these alterations.
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Project description:Gene expression profiles were assessed in the hippocampus, entorhinal cortex, superior-frontal gyrus, and postcentral gyrus across the lifespan of 55 cognitively intact individuals aged 20-99 years. Perspectives on global gene changes that are associated with brain aging emerged, revealing two overarching concepts. First, different regions of the forebrain exhibited substantially different gene profile changes with age. For example, comparing equally powered groups, 5,029 probe sets were significantly altered with age in the superior-frontal gyrus, compared with 1,110 in the entorhinal cortex. Prominent change occurred in the sixth to seventh decades across cortical regions, suggesting that this period is a critical transition point in brain aging, particularly in males. Second, clear gender differences in brain aging were evident, suggesting that the brain undergoes sexually dimorphic changes in gene expression not only in development but also in later life. Globally across all brain regions, males showed more gene change than females. Further, Gene Ontology analysis revealed that different categories of genes were predominantly affected in males vs. females. Notably, the male brain was characterized by global decreased catabolic and anabolic capacity with aging, with down-regulated genes heavily enriched in energy production and protein synthesis/transport categories. Increased immune activation was a prominent feature of aging in both sexes, with proportionally greater activation in the female brain. These data open opportunities to explore age-dependent changes in gene expression that set the balance between neurodegeneration and compensatory mechanisms in the brain and suggest that this balance is set differently in males and females, an intriguing idea.
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