Project description:Cognitive impairment (CI) is a prevalent neurological condition characterized deficient attention, causal reasoning, learning and/or memory. Many genetic and environmental factors increase risk for CI, and the gut microbiome is increasingly implicated. However, the identity of gut microbes associated with CI risk, their effects on CI, and their mechanisms of action remain unclear. Here we examine the gut microbiome in response to restricted diet and intermittent hypoxia, known environmental risk factors for CI. Modeling the environmental factors together in mice potentiates CI and alters the gut microbiota. Depleting the microbiome by antibiotic treatment or germ-free rearing prevents the adverse effects of environmental risk on CI, whereas transplantation of the risk-associated microbiome into naïve mice confers CI. Parallel sequencing and gnotobiotic approaches identify the pathobiont Bilophila wadsworthia as enriched by the environmental risk factors for CI and as sufficient to induce CI. Consistent with CI-related behavioral abnormalities, B. wadsworthia and the risk-associated microbiome disrupt hippocampal activity, neurogenesis and gene expression. The CI induced by B. wadsworthia and by environmental risk factors is associated with microbiome-dependent increases in intestinal IFNy-producing Th1 cells. Inhibiting Th1 cells abrogates the adverse effects of both B. wadsworthia and environmental risk factors on CI. Together, these findings identify select gut bacteria that contribute to environmental risk for CI in mice by promoting inflammation and hippocampal dysfunction.
Project description:Alzheimer case-control samples originate from the EU funded AddNeuroMed Cohort, which is a large cross-European AD biomarker study relying on human blood as the source of RNA. The design is case-control. Cases are either Alzheimer's disease patients, subjects with mild cognitive impairment or age and gender matched controls.
Project description:Although immediate early genes (IEGs) such as Bdnf, Arc and Egr1, have been implicated in plasticity, the larger pathways related to memory and memory disorders are not well understood. Here, we combined statistical Affymetrix microarray and behavioral analyses to identify key genes and pathways associated with aging-related cognitive impairment. Aged rats were separated into cognitively unimpaired (AU) or impaired (AI) groups, based on their Morris water maze performance relative to young-adult (Y) animals. Hippocampal gene expression was assessed in Y, AU and AI on the fifth (last) day of maze training or 21 days posttraining, and in non-trained aged and young animals (eight groups, overall n = 78, one chip/animal). ANOVA, linear contrasts, and overrepresentation analyses identified genes and pathways that differed from Y generally with aging (in both AU and AI) or selectively with cognitive status (only in AI or AU). Plasticity pathways, including insulin/cAMP/IEG signaling, and glycogenolytic and lipogenic pathways, were selectively downregulated (5 days) in AI, whereas Notch2 (regulating oligodendrocyte differentiation) and myelination pathways were upregulated (particularly at 21 days). Downregulation with general aging occurred in signal transduction and axonal growth/transport pathways, whereas upegulation occurred in immune/inflammatory, lipid metabolism/transport (e.g., Lxr-Srebf1), and lysosomal pathways. In AU, receptor/signal transduction genes were selectively upregulated, suggesting possible compensatory mechanisms. Immunohistochemistry confirmed and extended results to the protein level. Thus, this study identified novel cognition-linked processes, suggesting a new model in which energy-intensive, plasticity/lipogenic processes and energy-generating pathways necessary for learning are coordinately downregulated during training, while myelinogenic programs that impair cognition are concurrently activated. Keywords: Immediate Early Genes, Insulin Signaling, Cholesterol, Myelination, Glia, Inflammation, Young and Old comparaison, behavioral-characterization, Aging-related cognitive impairment.
Project description:The presence of an extra whole or part of chromosome 21 in people with Down syndrome (DS) is associated with multiple neurological changes, including pathological aging that often meets the criteria for Alzheimer’s Disease (AD). While the mechanism underlying these changes is unknown, it has been hypothesized that the presence of the amyloid precursor protein (APP) on chromosome 21 may contribute to the phenotype. Genome-wide DNA methylation abnormalities have been shown in neural tissue of patients with AD, and cells may respond to changes in gene dosage with altered DNA methylation. We therefore examined whole-genome DNA methylation in buccal epithelial cells of adults with DS to determine whether patterns of DNA methylation correlated with DS and/or cognitive impairment. In addition we examined DNA methylation at the APP gene itself, to see whether there were changes in DNA methylation in this population. Using the Illumina 450K Human Methylation Array, we examined more than 485,000 CpG sites distributed across the genome in buccal epithelial cells. We found 297 CpGs to be differentially methylated between the groups, including 26 genes that were represented by more than one CpG. In addition, we found 331 probes that were correlated with cognitive function including 23 genes represented by more than one probe. We found no enrichment on chromosome 21 and targeted analysis of the APP gene revealed weak evidence for epigenetic impacts related to the AD phenotype. Overall, our results indicate that both Trisomy 21 and cognitive impairment are associated with distinct patterns of DNA methylation. This cohort consist of genomic DNA extracted from 20 buccal swabs, bisulphite converted and hybridized to the Illumina Infinium HumanMethylation450 Beadchip for genome wide DNA methylation profiling.
Project description:The goal of this research study is to test the feasibility of an intervention programme to reduce cognitive impairment due to cancer treatment. The investigators want to find out how acceptable the intervention and procedures are for cancer patients.
Project description:Genome wide DNA methylation profiling of isolated human CD14+16+ monocyte and CD8+ T cell samples from HIV-infected individuals with cognitive impairment and without.
Project description:Cognitive impairment due to cancer and its therapy is a major concern among cancer survivors. Extracellular vesicles (EVs) composition altered by cancer and chemotherapy may affect neurological processes such as neuroplasticity, potentially impacting the cognitive abilities of cancer survivors. We investigated the EV proteome of breast cancer patients with and without cognitive impairment following anthracycline-based chemotherapy from longitudinally collected plasma. EVs were cup-shaped and positive for Flotillin-1 and TSG-101. We identified 517 differentially expressed EV proteins between the cognitive impaired and non-impaired groups during and post-chemotherapy. The observed decreased expression of p2X purinoceptor, cofilin-1, ADAM 10, and dynamin-1 in the plasma EVs of cognitive impaired group may suggest alterations in mechanisms underlying synaptic plasticity. The reduced expression of tight junction proteins among cognitive-impaired patients may imply weakening of the blood-brain barrier. These EV protein signatures may serve as a fingerprint that underscore the mechanisms underlying cognitive impairment in cancer survivors.
Project description:Layer II stellate neurons (entorhinal cortex) and layer III cortical neurons (hippocampus CA1, middle temporal gyrus, posterior cingulate, superior frontal gyrus, primary visual cortex) were gene expression profiled. Brain regions are from individuals who had been diagnosed with mild cognitive impairment. Experiment Overall Design: ~500 neurons were selected from each of 6 brain regions. Total RNA was isolated from each batch of neurons, double round amplified, and hybridized to Affymetrix Human Genome U133 Plus 2.0 arrays.