Project description:Multi-omics analysis highlights the link of aging-related cognitive decline with systemic inflammation and alterations of tissue-maintenance [RRBS]
Project description:Aging-related cognitive decline is associated with changes across different tissues and the gut microbiome, including dysfunction of the gut-brain axis. However, only few studies have linked multi-organ alterations to cognitive decline during aging. Here we report a multi-omics analysis integrating metabolomics, transcriptomics, DNA methylation, and metagenomics data from hippocampus, liver, colon, and fecal samples of mice, correlated with cognitive performance in the Barnes Maze spatial learning task across different age groups. We identified 734 molecular features associated with cognitive rank within individual data layers, of which 227 features remain when integrating all data layers with each other. Among the single-layer predictors, several host and microbial features were highlighted, with host-associated markers being predominant. Host features associated with cognitive function mainly belong to innate and adaptive inflammatory activity (inflammaging) and developmental processes. Our findings suggest that cognitive decline in aging is tightly coupled to systemic, age-associated inflammation, potentially initiated by microbiome-driven gastrointestinal inflammatory activity, emphasizing a link between peripheral tissue alterations and brain function.
Project description:Aging leads to a progressive deterioration in brain function, which will eventually result in cognitive decline and can develop into a dementia. The mechanisms underlying pathological cognitive decline in aging are still poorly understood. The peripheral immune system, as well as the meningeal lymphatic vasculature and the immune cells residing in the brain and meninges, are all affected by aging. Moreover, recent studies have linked the dysfunction of the meningeal lymphatic system and peripheral immunity to accelerated brain aging. We hypothesized that an age-related reduction in CCR7-dependent immune cell egress through the lymphatic vasculature mediates some aspects of aging-associated brain dysfunction, leading to cognitive decline and potentially exacerbating neurodegenerative diseases. Here, we report a reduction in CCR7 expression by meningeal T cells in aged mice and its associated increase in meningeal T-regulatory cells. Hematopoietic CCR7 deficiency mimicked the aging-associated changes in meningeal T cells and led to cognitive impairment. Interestingly, CCR7-deficient mice also presented impaired brain glymphatic function and showed increased amyloid beta (A) deposition when crossed with the 5xFAD transgenic mouse model of Alzheimer’s disease (AD). These results show that the aging-associated decrease in CCR7 expression impacts meningeal immunity, affects different aspects of brain function and exacerbates brain A pathology, highlighting its potential as a pathogenic mechanism for cognitive decline in aging and AD.
Project description:Aging is the predominant risk factor for neurodegenerative diseases. One key phenotype as brain ages is the aberrant innate immune response characterized by proinflammation. However, the molecular mechanisms underlying aging-associated proinflammation are poorly defined. Whether chronic inflammation plays a causal role in cognitive decline in aging and neurodegeneration has not been established. Here we established a mechanistic link between chronic inflammation and aging microglia, and demonstrated a causal role of aging microglia in neurodegenerative cognitive deficits. Expression of microglial SIRT1 reduces with the aging of microglia. Genetic reduction of microglial SIRT1 elevates IL-1β selectively, and exacerbates cognitive deficits in aging and in transgenic mouse models of frontotemporal dementia (FTD). Interestingly, the selective activation of IL-1β transcription by SIRT1 deficiency is likely mediated through hypomethylating the proximal promoter of IL-1β. Consistent with our findings in mice, selective hypomethylation of IL-1β at two CpG sites are found in normal aging humans and demented patients with tauopathy. Our findings reveal a novel epigenetic mechanism in aging microglia that contributes to cognitive deficits in neurodegenerative diseases. Study of changes related to alterations of SIRT1 levels in microglia of young and aged animals and in models of neurodegenerative dementia
Project description:Platelet factors regulate wound healing and also signal from the blood to the brain. However, whether platelet factors modulate cognition, a highly valued and central manifestation of brain function, is unknown. Here, we show that systemic platelet factor 4 (PF4) modulates cognition and its molecular signature. Klotho, a longevity and cognition-enhancing protein, acutely activated platelets and increased circulating platelet factors, most robustly platelet factor 4 (PF4). To directly test PF4 effects on the brain, we treated mice with vehicle or systemic PF4. In young mice, PF4 enhanced synaptic plasticity and cognition. In aging mice, PF4 restored cognitive deficits and rejuvenated a molecular signature of cognition in the aging hippocampus. Augmenting platelet factors such as PF4, a possible messenger of klotho, may enhance cognition in the young brain and rejuvenate cognitive deficits in the aging brain.
Project description:This SuperSeries is composed of the following subset Series: GSE24992: Drosophila brain microRNA expression with age: miRNA profiling GSE25007: Drosophila brain gene expression with age: mRNA profiling GSE25008: Drosophila brain gene expression between wildtype and miR-34 null flies Refer to individual Series. Aging is the most prominent risk factor for human neurodegenerative disease, but underlying mechanisms that connect two processes are less well characterized. With age, the brain undergoes functional decline and perhaps degeneration. Such decline may not just contribute to normal aging, but also enhance susceptibility to and progression of age-related neurodegenerative diseases. Therefore, defining intrinsic factors and pathways that underline the normal integrity of the adult nervous system may lead to insights that potentially link aging and neurodegeneration. Here, we report a highly conserved microRNA (miRNA), miR-34, as a modulator of aging and neurodegeneration. Using Drosophila, we show that fly miR-34 expression is brain-enriched and strikingly upregulated with age. Functional studies reveal that, whereas animals without miR-34 are normal as young adults, upon aging, they gradually show late-onset deficits characteristic of accelerated brain aging; these include a transcriptional signature of aged animals, coupled with rapid functional decline, loss of brain integrity, followed by a catastrophic decline in adult viability. Moreover, upregulation of miR-34 protects against neurodegeneration induced by pathogenic human polyglutamine (polyQ) disease protein. We next reveal a dramatic effect of miR-34 to silence the Eip74EF gene of steroid hormone pathways in the adult, which is crucial to maintain the normal aging. Collectively, these data define a miR-34-mediated mechanism that specifically affects long-term integrity of the adult nervous system. miR-34 function in Drosophila may thus present a link that functionally connects aging and neurodegeneration. Our studies implicate essential roles of miRNA- dependent pathways in maintenance of the adult brain, disease pathogenesis and healthy aging.
Project description:Systemic inflammation can lead to neuro-inflammation with both acute consequences and long-lasting deleterious effects, such as cognitive decline and the exacerbation of neurodegenerative disease progression. We investigated the role in regulating this process of the activation of the transcription factor Nrf2 in brain endothelial cells.
Project description:The aim of this study was to identify alterations in hippocampal synaptic mRNA expression with aging and cognitive decline. Transcriptional profiling and subsequent bioinformatic analysis was performed to identify the most highly regulated pathways of genes. Interestingly, the antigen processing and presentation pathway was identified as the most highly regulated pathway with aging. Adult (12 month) and aged (28 month) Fischer 344 x Brown Norway (F1) hybrid rats were assessed for cognitive performance using the Morris water maze task and were divided into Adult (n=5), Aged Cognitively Intact (n=8), and Aged Cognitively Impaired (n=7) groups. One week following testing, all animals were sacrificed, the hippocampi were dissected, and synaptosomes were isolated for subsequent transcriptomic profiling. Only 5 cognitively intact animals were processed on the arrays.
Project description:This study focused on transcription in the medial PFC (mPFC) as a function of age and cognition. Young and aged F344 rats were characterized on tasks, attentional set shift and spatial memory, which depend on the mPFC and hippocampus, respectively. Differences in transcription associated with age and cognitive function were examined using RNA sequencing to construct transcriptomic profiles for the mPFC, white matter, and region CA1 of the hippocampus. The results indicate regional differences in vulnerability to aging associated with increased expression of immune and defense response genes and a decline in synaptic and neural activity genes. Importantly, we provide evidence for region specific transcription related to behavior. In particular, expression of transcriptional regulators and neural activity-related immediate-early genes (IEGs) are increased in the mPFC of aged animals that exhibit delayed set shift behavior; relative to age-matched animals that exhibit set shift behavior similar to younger animals.
Project description:Protective immunity, essential for brain maintenance and repair, may be compromised in Alzheimer’s disease (AD). Here, using high-dimensional single-cell mass cytometry, we find a unique immunometabolic signature in circulating CD4+ T cells preceding symptom onset in individuals with familial AD, featured by the elevation of CD38 expression. Using female 5xFAD mice, a mouse model of AD, we show that treatment with an antibody directed to CD38 leads to restored metabolic fitness, improved cognitive performance, and attenuated local neuroinflammation. Comprehensive profiling across distinct immunological niches in 5xFAD mice, reveals a high level of disease-associated CD4+ T cells that produce IL-17A in the dural meninges, previously linked to cognitive decline. Targeting CD38 leads to abrogation of meningeal TH17 immunity and cortical IL-1beta, breaking the negative feedback loop between these two compartments. Taken together, the present findings suggest CD38 as an immunometabolic checkpoint that could be adopted as a pre-clinical biomarker for early diagnosis of AD and might also be therapeutically targeted alone or in combination with other immunotherapies for disease modification.