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Complement C3 released from neurotoxic reactive astrocytes impairs learning and memory in the mouse model of postoperative neurodegenerative disorders

ABSTRACT: 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.

ORGANISM(S): Mus musculus

PROVIDER: GSE199318 | GEO | 2024/03/13

REPOSITORIES: GEO

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Project description:Objective: Emerging evidence suggested that brain angiotensin-(1-7) (Ang-(1-7)) deficiency contributed to the pathogenesis of Alzheimer’s disease (AD). Meanwhile, our previous studies revealed that restoration of brain Ang-(1-7) levels provided neuroprotection by inhibition of inflammatory responses during AD progress. However, the potential molecular mechanisms by which Ang-(1-7) modulates neuroinflammation remain unclear. Materials and Methods: APP/PS1 mice were injected intraperitoneally with AVE0991 (a nonpeptide analogue of Ang-(1-7)) once a day for 30 consecutive days. Cognitive functions, neuronal and synaptic integrity, and inflammation-related markers were assessed. Since astrocytes played a crucial role in AD-related neuroinflammation whilst long noncoding RNAs (lncRNAs) were reported to participate in modulating inflammatory responses, astrocytes of APP/PS1 mice were then isolated for high-throughput lncRNA sequencing to identify the most differentially expressed lncRNA following AVE0991 treatment. Afterward, the downstream pathway of this lncRNA in the anti-inflammatory action of AVE0991 were investigated using primary astrocytes. Results: The protection of AVE0991 against cognitive impairment and neuronal and synaptic damage in APP/PS1 mice was confirmed. For the first time, we demonstrated that AVE0991 suppressed astrocytic NLRP3 inflammasome-mediated neuroinflammation via a lncRNA SNHG14-dependent manner. SNHG14 acted as a sponge of miR-223-3p while NLRP3 represented a direct target of miR-223-3p in astrocytes. In addition, miR-223-3p participated in the AVE0991-induced suppression of astrocytic NLRP3 inflammasome. Conclusion: These results suggest that AVE0991 inhibits astrocyte-mediated neuroinflammation via SNHG14/miR-223-3p/NLRP3 pathway. Moreover, these results reveal the underlying mechanisms by which Ang-(1-7) inhibits neuroinflammation under AD condition and uncovers the potential of its nonpeptide analogue AVE0991 in AD treatment.

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Complement C3 released from neurotoxic reactive astrocytes impairs learning and memory in the mouse model of postoperative neurodegenerative disorders

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