Project description:Extracellular vesicles (EVs) are involved in intercellular communication in health and disease and affect processes including immune and antiviral responses. We have previously demonstrated that ultracentrifuged serum is depleted of EVs and, when used in cell culture media, is associated with declines in growth and viability of numerous cultured cell types. Although EVs had been reported to enhance or interfere with HIV-1 infection, depending on the setting, the effects of EVs on HIV-1 production and infectivity of released virions were unknown. In this study, we examined the effects of EV-depleted serum on HIV-1 replication in primary cells and cell lines, including two HIV-1 latency models. Cell culture media were prepared with EV-replete fetal bovine serum (FBS) or serum depleted of EVs via ultracentrifugation or a proprietary method (ThermoFisher/Gibco). T-cell and myeloid-lineage cell lines, including ACH-2 and U1 HIV-1 latency models, and primary cells were grown in 10% FBS-based culture media. Cell counts, viability, and proliferation were assessed throughout. HIV-1 production and infectivity were measured by p24 ELISA and luciferase reporter cell lines, respectively. Flow cytometry, Seahorse assays, and miRNA and mRNA expression arrays were done to assess cellular responses to EV-depleted conditions. Significant increases in HIV-1 production were observed in EV-depleted conditions, along with, in some cases, morphology changes and decreased cell viability. Add-back of pelleted EVs reduced HIV-1 production almost to baseline. Primary cells appeared to be less susceptible to EV depletion. ACH-2 and U1 latency models also produced more HIV-1 under EV-depleted conditions. Virus produced under EV-depleted conditions was more infectious. Changes in cellular metabolism and gene expression were associated with EV-depleted culture. The EV environment of HIV-1 infected cells appears to have a significant effect on virus production and infectivity. In cell lines of HIV-latency, significantly higher concentrations of p24 were observed in those cells cultured in EVD conditions. EV-dependence of cell cultures should be examined carefully prior to examining additional experimental variables. However, we also sound a cautionary note that direct actions of EVs may be accompanied by the effects of other, closely associated factors.

Project description:Microglia are resident immune cells of the brain that play important roles in mediating inflammatory responses in several neurological diseases via direct and indirect mechanisms. One indirect mechanism may involve extracellular vesicle (EV) release, so that the molecular cargo transported by microglia-derived EVs can have functional effects by facilitating intercellular communication. The molecular composition of microglia-derived EVs, and how microglial activation states impacts EV composition and EV-mediated effects in neuroinflammation, remain poorly understood. We hypothesize that microglia-derived EVs have unique molecular profiles that are determined by microglial activation state. Using size-exclusion chromatography to purify EVs from BV2 microglia, combined with proteomic (label-free quantitative mass spectrometry or LFQ-MS) and transcriptomic (mRNA and non-coding RNA seq) methods, we obtained comprehensive molecular profiles of microglia-derived EVs. LFQ-MS identified several classic EV proteins (tetraspanins, ESCRT machinery, and heat shock proteins), in addition to over 200 proteins not previously reported in the literature. Unique mRNA and microRNA signatures of microglia-derived EVs were also identified. After treating BV2 microglia with lipopolysaccharide (LPS), interleukin-10, or transforming growth factor beta, to mimic pro-inflammatory, anti-inflammatory, or homeostatic states, respectively, LFQ-MS and RNA seq revealed novel state-specific proteomic and transcriptomic signatures of microglia-derived EVs. Particularly, LPS treatment had the most profound impact on proteomic and transcriptomic compositions of microglia-derived EVs. Furthermore, we found that EVs derived from LPS-activated microglia were able to induce pro-inflammatory transcriptomic changes in resting responder microglia, confirming the ability of microglia-derived EVs to relay functionally-relevant inflammatory signals. These comprehensive microglia-EV molecular datasets represent important resources for the neuroscience and glial communities, and provide novel insights into the role of microglia-derived EVs in neuroinflammation.

Dataset Information

Heat inactivation of foetal bovine serum performed after EV-depletion influences the proteome of cell-derived extracellular vesicles

Publications

Heat inactivation of foetal bovine serum performed after EV-depletion influences the proteome of cell-derived extracellular vesicles.

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