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Dual Orexin Receptor Antagonism with Lemborexant Enhances Microglial Clearance of β-Amyloid in Mice

ABSTRACT: Background: Sleep regulates brain amyloid-beta (Aβ) levels, and disruption of sleep is a risk factor for Alzheimer’s Disease (AD) and can exacerbate amyloid pathology. The orexin/hypocretin system, a key sleep-wake regulator, represents an emerging therapeutic target in AD, though the effects of FDA-approved dual orexin receptor antagonist drugs (DORAs) on amyloid pathology are unknown. Here, we assessed and compared the effects of lemborexant (LEM), an FDA-approved DORA, and doxepin, an anti-histaminergic sleep drug, on amyloid pathology and glial responses in the APP/PS1 mouse model of AD. Methods: APP/PS1 mice were treated with lemborexant (10 or 30mg/kg daily) or doxepin (35mg/kg daily) for 3 months, starting just before the onset of amyloid plaque accumulation, or for 1 month after plaque pathology was established. Sleep was measured using a piezoelectric system, and amyloid pathology and glial responses were quantified by immunohistochemistry and confocal microscopy, as well as single cell RNAseq of isolated microglia. Amyloid plaques were labeled with methoxy-X04 to monitor plaque growth, and microglial plaque phagocytosis was assessed by flow cytometry. Microglial elimination was performed using the CSF1r inhibitor PLX3397. Results: Despite equivalent total sleep enhancement, LEM more effectively prevented formation of and slowed growth of both fibrillar and diffuse Aβ plaques. LEM enhanced peri-plaque microglial activation and enhanced microglial amyloid phagocytosis in vivo. Single-cell microglial transcriptomics showed a LEM-mediated shift toward pro-phagocytic and antigen-presentation gene signatures. Depleting microglia via CSF1R inhibition abolished LEM’s anti-amyloid effects, underscoring microglia as essential mediators. Conclusions: These results demonstrate that dual orexin receptor antagonism with lemborexant can augment microglial function to mitigate AD pathology.

ORGANISM(S): Mus musculus

PROVIDER: GSE312840 | GEO | 2026/05/01

REPOSITORIES: GEO

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Project description:PLCγ2-P522R (phospholipase C gamma 2, proline 522 to arginine) is a protective variant that reduces the risk for late onset Alzheimer’s disease (LOAD). Recently, it was shown to decrease β-amyloid pathology in 5XFAD mouse model of AD. In this study, our goal was to investigate the protective functions of PLCγ2-P522R variant in less aggressive mouse model of AD as well as to assess underlying mechanisms at the molecular and cellular level using mouse and human microglia models. The effects of the protective PLCγ2-P522R variant on microglia activation, AD-related β-amyloid and neuronal pathologies, as well as behavioral changes were investigated in PLCγ2-P522R knock-in mice crossbred with an APP/PS1 mouse model of AD. Transcriptomic, proteomic, and functional studies were carried out in cultured and acutely isolated adult PLCγ2-P522R mouse microglia to study molecular mechanisms. Finally, microglia-like cell models generated from blood and skin biopsy samples of the PLCγ2-P522R variant carriers were employed to translate the key findings in human cells. Our results demonstrate that the PLCγ2-P522R variant reduces brain β-amyloid plaque burden of APP/PS1 mice. Simultaneously, PLCγ2-P522R variant increased non-proinflammatory microglia activation and microglia clustering around β-amyloid plaques, leading to reduced β-amyloid plaque-associated neuronal dystrophy. In cultured mouse primary microglia, PLCγ2-P522R variant decreased accumulation of large lipid droplets, reduced cell stress, and increased acute response to strong inflammatory stimuli. Transcriptomic and proteomic analyses in acutely isolated adult mouse microglia as well as in human monocyte-derived microglial cells showed that PLCγ2-P522R upregulates mitochondrial fatty acid oxidation and downregulates inflammatory/interferon signaling pathways. Accordingly, PLCγ2-P522R increased mitochondrial respiration in iPSC -derived microglial cells. Together, these findings suggest that PLCγ2-P522R variant exerts protection against AD-associated β-amyloid and neuronal pathologies via enhancing microglial barrier formation around β-amyloid plaques, but suppressing pro-inflammatory activation. Observed changes in fatty acid metabolism and mitochondrial flexibility as well as the downregulation of genes involved in inflammatory signaling pathways suggest that these protective effects of the PLCγ2-P522R variant are mediated through an anti-ageing mechanism.

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Dual Orexin Receptor Antagonism with Lemborexant Enhances Microglial Clearance of β-Amyloid in Mice

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