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Clozapine is the most effective treatment for treatment-resistant schizophrenia but has been linked to cognitive impairment and brain volume reductions. The potential mechanisms underlying these effects remain unclear. Microglial exosomes, which carry microRNAs (miRNAs) and other cargo, act as immune-neuron communication vectors capable of modulating neuronal function and cognition. We compared cognitive performance and inflammatory markers across clozapine-treated individuals, haloperidol-treated individuals, and healthy controls. Human microglial cells were treated with clozapine and assessed for phenotypic changes and exosome production. Exosomes from control and clozapine-treated microglia were applied to neuroblastoma cells and primary murine cortical neurons to assess neurite outgrowth and brain-derived neurotrophic factor (BDNF) expression. C. elegans were exposed to exosomes and evaluated for lifespan, healthspan markers, and cognitive function via olfactory associative learning assays. Exosomal miRNA cargo was characterized by small RNA sequencing. Clozapine-treated individuals exhibited elevated systemic inflammatory markers and lower cognitive performance compared with healthy controls. Clozapine altered microglial morphology, reduced proliferation and migration, and significantly increased exosome production. Small RNA sequencing identified six dysregulated miRNAs in clozapine-induced microglial exosomes, including upregulation of miR-34a-5p. Exposure of neurons to clozapine-induced exosomes reduced neurite length, branch points, and BDNF expression. In C. elegans, clozapine-induced exosomes reduced lifespan and severely impaired learning and short-term memory. These findings identify a neuroimmune exosomal pathway through which clozapine-exposed microglia can impair neuronal structure and cognition, associated with dysregulated miRNA cargo. This work provides a framework linking microglial immune signalling, extracellular vesicle biology, and cognitive vulnerability during clozapine exposure. Show less

Women face a heightened risk of Alzheimer's disease (AD), partly attributed to post-menopausal estrogen loss. Given that ERβ activation avoids the oncogenic risks of ERα and GPR40 plays a pivotal role in neuronal function, the ERβ/GPR40 axis show a promising therapeutic target for anti-AD drug discovery. To inspect the role of this axis, we employed Vincamine (Vin), a monoterpenoid indole alkaloid from Madagascar periwinkle that we previously identified as a GPR40 agonist. To elucidate the role of ERβ/GPR40 axis in AD pathogenesis and to investigate the therapeutic potential of Vin in ameliorating AD-related deficits. We combined analyses of clinical data from female AD patients (GSE33000) with the research in 3×Tg-AD mice to examine the differences in ERβ/GPR40 expression. The binding of ERβ and GPR40 was detected by CUT&Tag assay, protein-DNA docking simulation and molecular dynamics simulation assays. Vin was used to evaluate the therapeutic potential of ERβ/GPR40 axis activation for AD. The underlying mechanisms were investigated by assay against the adeno-associated virus (AAV)-CMV-PHP.eB-KD-GPR40 injected 3×Tg-AD female mice. ERβ and GPR40 are both downregulated in brains of female AD patients and 3×Tg-AD mice, and ERβ directly binds to GPR40 promoter. Brain-specific GPR40 knockdown caused cognitive impairment in female wild type (WT) mice. Vin as a GPR40 agonist but not an ERβ ligand ameliorated AD-like pathology in 3×Tg-AD female mice. Specifically, Vin suppressed neuroinflammation via GPR40/NF-κB/NLRP3 pathway, inhibited neuronal tau hyperphosphorylation via GPR40/GSK3β/CaMKII pathway, while promoted synaptic plasticity via GPR40/PKA/CREB/BDNF pathway. To our knowledge, our study provides the first identification of the specific ERβ-binding regions and key residues within the GPR40 promoter, offering novel mechanistic insight into their transcriptional regulation. Furthermore, our work establishes ERβ/GPR40 axis as a potentially therapeutic strategy for female AD and highlight the medication interest of Vin in treating this disease. Show less