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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

Major depressive disorder (MDD) is a debilitating neuropsychiatric condition characterized by persistent low mood, affecting approximately 322 million individuals worldwide. With a staggering 15% mortality rate due to suicide among patients, MDD represents a critical global health challenge. Emerging evidence implicates microRNAs (miRNAs) in the pathogenesis of neuropsychiatric disorders; however, the role of miR-146a-3p in MDD-particularly its mechanistic involvement and potential as a diagnostic biomarker-remains unexplored. In this study, we integrated multi-database bioinformatics analyses with experimental validation to identify miR-146a-3p as a key regulator of MDD progression. Our computational screening revealed miR-146a-3p as a putative risk-associated non-coding RNA, alongside brain-derived neurotrophic factor (BDNF), a well-established MDD susceptibility gene. In vivo studies demonstrated a significant upregulation of miR-146a-3p and concurrent downregulation of BDNF in MDD model mice. Further bioinformatic predictions and dual-luciferase reporter assays confirmed a direct interaction between miR-146a-3p and BDNF mRNA, leading to post-transcriptional suppression of BDNF expression. Mechanistically, miR-146a-3p overexpression impaired synaptic plasticity, as evidenced by reduced levels of key synaptic proteins such as postsynaptic density protein 95 (PSD95) and synapsin (SYN-1), while in vitro transfection experiments validated its negative regulation of BDNF. Critically, intranasal delivery of a miR-146a-3p antagomir or exogenous BDNF protein rescued depressive-like behaviors in murine models, as assessed by open-field, forced swim, and tail suspension tests. These interventions restored synaptic protein expression and ameliorated behavioral deficits, suggesting a therapeutic avenue for MDD. Our findings establish miR-146a-3p as a pivotal epigenetic modulator of MDD pathogenesis, acting through direct suppression of BDNF-dependent synaptic plasticity. The reversibility of this pathway via antagomir inhibition highlights miR-146a-3p's dual potential as both a diagnostic biomarker and a therapeutic target. This study provides foundational insights for developing miRNA-based interventions in mood disorders. Show less

MicroRNAs, as key regulators in gene expression, may hold the key to understanding Alzheimer disease (AD) pathogenesis and diagnosis. To explore the expression level of miR-106b-3p in the serum of AD patients, and evaluate its diagnostic value for AD. A total of 250 AD patients and 200 healthy controls were enrolled. Real-time quantitative PCR with fluorescence detection was used to determine the relative expression level of miR-106b-3p. Correlation was analyzed by the Pearson linear correlation analysis. The receiver operating characteristic was used to evaluate the diagnostic efficacy of serum miR-106b-3p for AD. In vitro AD cellular models were established to explore the potential mechanism of miR-106b-3p in AD. The expression of miR-106b-3p in the serum of AD patients is significantly elevated, and its level is negatively correlated with the MMSE score. ROC curve analysis shows that it has certain diagnostic value. miR-106b-3p is a risk factor associated with AD. In addition, miR-106b-3p targets BDNF, affects the functions of SH-SY5Y cells, and promotes the occurrence and development of AD. Serum miR-106b-3p is significantly elevated in AD and may serve as a diagnostic biomarker. Preliminary evidence suggests it promotes AD progression by targeting BDNF, highlighting its potential as a therapeutic target for early intervention. Show less

Maternal immune activation (MIA) is a key environmental risk factor for neurodevelopmental disorders such as schizophrenia. MicroRNAs are critical regulators of brain development, yet their role in MIA-induced pathology remains unclear. We found that miR-322-5p was significantly upregulated in the prefrontal cortex of MIA-exposed offspring and directly targeted the 3' untranslated region of brain-derived neurotrophic factor (BDNF), inhibiting its expression. This upregulation impaired BDNF/TrkB/AKT signaling and reduced the synaptic protein PSD95, leading to hypoactivity, cognitive deficits, social impairments, and disrupted sensorimotor gating. Inhibition of miR-322-5p or overexpression of BDNF in the prefrontal cortex restored signaling and reversed both behavioral and molecular abnormalities. These results identify miR-322-5p as a key mediator of MIA-induced neuropathology via repression of BDNF signaling and suggest its potential as a therapeutic target in neurodevelopmental disorders. Show less