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Serum extracellular vesicle depletion processes affect release and infectivity of HIV-1 in culture.

ABSTRACT: Extracellular vesicles (EVs) are involved in intercellular communication and affect processes including immune and antiviral responses. Blood serum, a common cell culture medium component, is replete with EVs and must be depleted prior to EV-related experiments. The extent to which depletion processes deplete non-EV particles is incompletely understood, but depleted serum is associated with reduced viability and growth in cell culture. Here, we examined whether serum depleted by two methods affected HIV-1 replication. In cell lines, including HIV-1 latency models, increased HIV-1 production was observed, along with changes in cell behavior and viability. Add-back of ultracentrifuge pellets (enriched in EVs but possibly other particles) rescued baseline HIV-1 production. Primary cells were less sensitive to serum depletion processes. Virus produced under processed serum conditions was more infectious. Finally, changes in cellular metabolism, surface markers, and gene expression, but not miRNA profiles, were associated with depleted serum culture. In conclusion, depleted serum conditions have a substantial effect on HIV-1 production and infectivity. Dependence of cell cultures on "whole serum" must be examined carefully along with other experimental variables, keeping in mind that the effects of EVs may be accompanied by or confused with those of closely associated or physically similar particles.

SUBMITTER: Liao Z

PROVIDER: S-EPMC5451420 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Serum extracellular vesicle depletion processes affect release and infectivity of HIV-1 in culture.

Liao Zhaohao Z Muth Dillon C DC Eitan Erez E Travers Meghan M Learman Lisa N LN Lehrmann Elin E Witwer Kenneth W KW

Scientific reports 20170531 1

Extracellular vesicles (EVs) are involved in intercellular communication and affect processes including immune and antiviral responses. Blood serum, a common cell culture medium component, is replete with EVs and must be depleted prior to EV-related experiments. The extent to which depletion processes deplete non-EV particles is incompletely understood, but depleted serum is associated with reduced viability and growth in cell culture. Here, we examined whether serum depleted by two methods affe ...[more]

PMID: 28566772

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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:BackgroundExtracellular Vesicles (EV) recently have been implicated in the pathogenesis of HIV-1 syndromes, including neuroinflammation and HIV-1 associated neurological disorder (HAND). Cocaine, an illicit stimulant drug used worldwide is known to exacerbate these HIV-1 associated neurological syndromes. However, the effects of cocaine on EV biogenesis and roles of EVs in enhancing HIV-1 pathogenesis are not yet well defined.ResultsHere, we investigated the effects of cocaine on EV biogenesis and release in HIV-1 infected immune cells and explored their roles in elicitation of neuroinflammation. We found that cocaine significantly augmented the release of EVs from uninfected and HIV-1 infected T-cells, DCs and macrophages. Further analysis of the molecular components of EVs revealed enhanced expression of adhesion molecules integrin β1 and LFA-1 in those EVs derived from cocaine treated cells. Intriguingly, in EVs derived from HIV-1 infected cells, cocaine treatment significantly increased the levels of viral genes in EVs released from macrophages and DCs, but not in T-cells. Exploring the molecular mechanism to account for this, we found that DCs and macrophages showed enhanced expression of the cocaine receptor Sigma 1-Receptor compared to T-cells. In addition, we found that cocaine significantly altered the integrity of the RNA-induced silencing complex (RISC) in HIV-1 infected macrophages and DCs compared to untreated HIV-1 infected cells. Characterizing further the molecular mechanisms involved in how cocaine increased EV release, we found that cocaine decreased the expression of the interferon-inducible protein BST-2; this resulted in altered trafficking of intracellular virus containing vesicles and EV biogenesis and release. We also observed EVs released from cocaine treated HIV-1 infected macrophages and DCs enhanced HIV-1 trans-infection to T-cells compared to those from untreated and HIV-1 infected cells. These EVs triggered release of proinflammatory cytokines in human brain microvascular endothelial cells (HBMECs) and altered monolayer integrity.ConclusionsTaken together, our results provide a novel mechanism which helps to elucidate the enhanced prevalence of neurological disorders in cocaine using HIV-1 infected individuals and offers insights into developing novel therapeutic strategies against HAND in these hosts.

Project description:While extracellular vesicles (EVs) continue to gain interest for therapeutic applications, their clinical translation is limited by a lack of optimal isolation methods. We sought to determine how universally applied isolation methods impact EV purity and yield. EVs were isolated by ultracentrifugation (UC), polyethylene glycol precipitation, Total Exosome Isolation Reagent, an aqueous two-phase system with and without repeat washes or size exclusion chromatography (SEC). EV-like particles could be detected for all isolation methods but varied in their purity and relative expression of surface markers (Alix, Annexin A2, CD9, CD63 and CD81). Assessments of sample purity were dependent on the specificity of characterisation method applied, with total particle counts and particle to protein (PtP) ratios often not aligning with quantitative measures of tetraspanin surface markers obtained using high-resolution nano-flow cytometry. While SEC resulted in the isolation of fewer particles with a relatively low PtP ratio (1.12 × 107 ± 1.43 × 106 vs highest recorded; ATPS/R 2.01 × 108 ± 1.15 × 109, p ⩽ 0.05), EVs isolated using this method displayed a comparatively high level of tetraspanin positivity (e.g. ExoELISA CD63⁺ particles; 1.36 × 1011 ± 1.18 × 1010 vs ATPS/R 2.58 × 1010 ± 1.92 × 109, p ⩽ 0.001). Results originating from an accompanying survey designed to evaluate pragmatic considerations surrounding method implementation (e.g. scalability and cost) identified that SEC and UC were favoured for overall efficiency. However, reservations were highlighted in the scalability of these methods, which could potentially hinder downstream therapeutic applications. In conclusion, variations in sample purity and yield were evident between isolation methods, while standard non-specific assessments of sample purity did not align with advanced quantitative high-resolution analysis of EV surface markers. Reproducible and specific assessments of EV purity will be critical for informing therapeutic studies.

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Serum extracellular vesicle depletion processes affect release and infectivity of HIV-1 in culture.

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Serum extracellular vesicle depletion processes affect release and infectivity of HIV-1 in culture.

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