Project description:This study investigates the roles of neurons, microglia, astrocytes, and oligodendrocytes in the pathogenesis of postoperative cognitive impairment, focusing on a dysregulated glia-neuron cycle. We utilized 18-month male C57BL/6 mice to model this condition, conducting single-cell RNA sequencing in the hippocampus to explore the neuroglial interactions and their implications in neuroinflammation, synaptic dysfunction, and myelin loss. This dataset includes transcriptomic profiles aimed at decoding the cellular communication in aged hippocampal cells and assessing the impact of therapeutic interventions on postoperative cognitive decline.
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:Perioperative neurocognitive disorder (PNDs) can commonly occur after major surgery in at risk patients and its occurrence increases medical healthcare burdens and even mortality. Accumulating evidence points to neuroinflammation being pivotal to the pathogenesis of these conditions. The complement cascade contributes to neuroinflammatory responses in the central nervous system (CNS) and complement C3 has been implicated in the manifestation of cognitive deficits in several neurological conditions. Neurotoxic reactive astrocytes function differently to their non-activated counterparts and release complement components in response to pathological triggers. We observed previously that surgery induces a rapid rise and then fall in cytokines but a more sustained glial activation response that coincided with postoperative cognitive impairment. In this study, we explored the relationship between the expression of complement C3, glial activation, and cognitive deficits. Using a murine model of surgery, we characterized the transcriptional profiles of hippocampal astrocytes after surgery and examined the effects of C3 suppression on the neuroinflammatory response and cognitive performance. There was a delayed but sustained rise in hippocampal C3 of astrocytic in origin after surgery which corresponded with the onset of cognitive decline. Furthermore, the A1 or the neurotoxic phenotype predominated in this postoperative astrocytic activation, and these cells have a distinct transcriptional profile including C3 upregulation. Suppression of C3 inhibited synaptic phagocytosis by microglia and attenuated postoperative cognitive impairment. Therefore, C3 from reactive astrocytes appear central to the development of cognitive dysfunction associated with postoperative neuroinflammation.
Project description:Postoperative cognitive dysfunction (POCD) is one of the severe complications inducing low life quality and high mortality after surgery, especially in elderly patients.Here we probed differentially expressed circRNAs using microarray assay in POCD patients, aiming to find potential key circRNAs related to the occurrence of POCD. Subsequently, ten dysregulated circRNAs were confirmed via quantitative real-time polymerase chain reaction (qRT-PCR) in 10 paired samples. Then, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to probe the vital functions of dysregulated genes.
Project description:It is important to maintain cognitive integrity during underwater operations, which may also trigger cognitive alterations. Cognitive effect of underwater operations and the underlying mechanism remain elusive. Here, we found a single underwater operation affects cognition in a time-dependent model. Prolonged exposure elicits significant cognitive impairment and hippocampal dysfunction, which was accompanied by activation of microglia and upregulation of pro-inflammatory cytokines. RNA-sequencing supported the involvement of neuroinflammation and indicated the critical role of CCR3. Knockdown of CCR3 significantly rescued cognitive impairment and hippocampal dysfunction. Furthermore, the upregulation of pro-inflammatory cytokines was also reversed. Mechanistically, CCR3 knockdown switched the activated microglia from a pro-inflammatory to neuroprotective phenotype. Taken together, these results highlighted the time-dependent effects of a single underwater operation on cognitive function. Knocking down CCR3 can attenuate neuroinflammation by regulating polarization of activated microglia, thereby alleviating prolonged underwater operation-induced cognitive impairment.
Project description:Background: Postoperative cognitive dysfunction (POCD) is a debilitating neurological complication in surgical patients. Current research has focused mainly on microglial activation, but less is known about the resultant neuronal synaptic changes. Recent studies have suggested that silent information regulator 1 (SIRT1) plays a critical role in several different neurological disorders via its involvement in microglial activation. In this study, we evaluate the effects of SIRT1 activation in a POCD mouse model. Methods: Exploratory laparotomy was performed in mice aged 12-14 months under sevoflurane anesthesia to establish our animal POCD model. Transcriptional changes in the hippocampus after anesthesia and surgery were evaluated by RNA sequencing. SIRT1 expression was verified by Western Blot. Mice were treated with SIRT1 agonist SRT1720 or vehicle after surgery. Changes in microglia morphology, microglial phagocytosis, presence of dystrophic neurites, and dendritic spine density were evaluated. Cognitive performance was evaluated using the Y maze and Morris water maze. Results: SIRT1 expression levels were downregulated in POCD. Exposure to anesthesia and surgery lead to alteration in microglia morphology, increased synaptic engulfment, dendritic spine loss, and cognitive deficits. These effects were alleviated by SRT1720 administration. Conclusion: This study suggests an important neuroprotective role for SIRT1 in POCD pathogenesis. Increasing SIRT1 function represents a promising therapeutic strategy for prevention and treatment of POCD.
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.