Biology subjects

Grassi-Oliveira, R.

Publications and source records attributed to Grassi-Oliveira, R..

3 recordsLinked to original sources

bioRxiv2026

GW4869 depletes macrophages and increases number of extracellular vesicles in murine peritoneal cavity fluid

Pharmacological approaches to inhibit extracellular vesicle (EV) release in vivo are increasingly used, although the effects of such compounds on local cellular environments are not fully understood. In this study, we examined the impact of intraperitoneal (i.p.) administration of the neutral sphingomyelinase inhibitor GW4869 on EV levels in the peritoneal cavity. Repeated GW4869 i.p. injections elicited a marked local inflammatory response, reduced peritoneal macrophage numbers, and paradoxically increased EV concentrations 24 hours after treatment. Independent macrophage depletion reproduced this rise in EV levels, indicating that macrophage loss and associated cellular remodeling contribute substantially to EV accumulation. These observations indicate that GW4869 can perturb local immune homeostasis in vivo, a confound that must be considered when using this compound as a putative selective inhibitor of EV release.

cell biology↗

bioRxiv2025

Extracellular vesicles from morphine-exposed prefrontal cortex carry transcriptomic and proteomic signatures of synaptic dysfunction

Extracellular vesicles (EVs) released by neurons and glial cells mediate intercellular communication in the brain and regulate synaptic function, neuronal survival, and neuropathological processes. Although chronic opioid exposure induces widespread neuroadaptations, the contribution of brain-derived EVs (BDEVs) to these processes remains largely unknown. Here, we isolated BDEVs from the prefrontal cortex of rats chronically exposed to morphine and performed integrative transcriptomic and proteomic analyses of their molecular cargo. Total RNA sequencing combined with unbiased proteomics revealed that morphine profoundly reprograms the BDEV transcriptome and proteome, enriching pathways related to synaptic plasticity, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, and neurodegeneration. Among the most prominent alterations, the synaptic regulator ARC was consistently modulated at the mRNA level, while the ER stress marker HSPA5 was altered at both mRNA and protein levels. Functional assays further demonstrated that BDEVs derived from morphine-treated rats were sufficient to reconfigure transcriptional programs in naive cortical neurons, affecting genes associated with synaptic remodeling and excitability. Collectively, these findings provide the first evidence that chronic opioid exposure reprograms BDEV cargo in a brain region critical for addiction and that these vesicles can propagate transcriptional reorganization to recipient neurons. BDEVs thus emerge as active mediators of morphine-induced neuroadaptations and as potential targets for biomarker discovery and therapeutic intervention in opioid use disorder.

neuroscience↗

bioRxiv2024

Lipidomic and Proteomic Insights from Extracellular Vesicles in Postmortem Dorsolateral Prefrontal Cortex Reveal Substance Use Disorder-Induced Brain Changes

Substance use disorder (SUD) significantly increases the risk of neurotoxicity, inflammation, oxidative stress, and impaired neuroplasticity. The activation of inflammatory pathways by substances may lead to glial activation and chronic neuroinflammation, potentially mediated by the release of extracellular particles (EPs), such as extracellular condensates (ECs) and extracellular vesicles (EVs). These particles, which reflect the physiological, pathophysiological, and metabolic states of their cells of origin, might carry molecular signatures indicative of SUD. In particular, our study investigated neuroinflammatory signatures in SUD by isolating EVs from the dorsolateral prefrontal cortex (dlPFC) Brodmanns area 9 (BA9) in postmortem subjects. We isolated BA9-derived EVs from postmortem brain tissues of eight individuals (controls: n=4, SUD: n=4). The EVs were analyzed for physical properties (concentration, size, zeta potential, morphology) and subjected to integrative multi-omics analysis to profile the lipidomic and proteomic characteristics. We assessed the interactions and bioactivity of EVs by evaluating their uptake by glial cells. We further assessed the effects of EVs on complement mRNA expression in glial cells as well as their effects on microglial migration. No significant differences in EV concentration, size, zeta potential, or surface markers were observed between SUD and control groups. However, lipidomic analysis revealed significant enrichment of glycerophosphoinositol bisphosphate (PIP2) in SUD EVs. Proteomic analysis indicates downregulation of SERPINB12, ACYP2, CAMK1D, DSC1, and FLNB, and upregulation of C4A, C3, and ALB in SUD EVs. Gene ontology and protein-protein interactome analyses highlight functions such as cell motility, focal adhesion, and acute phase response signaling that is associated with the identified proteins. Both control and SUD EVs increased C3 and C4 mRNA expression in microglia, but only SUD EVs upregulated these genes in astrocytes. SUD EVs also significantly enhanced microglial migration in a wound healing assay.This study successfully isolated EVs from postmortem brains and used a multi-omics approach to identify EV-associated lipids and proteins in SUD. Elevated C3 and C4 in SUD EVs and the distinct effects of EVs on glial cells suggest a crucial role in acute phase response signaling and neuroinflammation.

neuroscience↗