# Extracellular condensates (ECs) are endogenous modulators of HIV transcription and latency reactivation

## TL;DR

Extracellular condensates from SIV-infected macaques can reactivate latent HIV, but those from THC-treated macaques suppress this reactivation.

## Contribution

This study identifies extracellular condensates as endogenous modulators of HIV latency and shows their regulation by THC treatment.

## Key findings

- VEH | SIV ECs activate latent HIV transcription and increase viral antigen expression.
- THC | SIV ECs inhibit HIV transcription and latency reactivation.
- ECs alter host transcriptome and secretome to either suppress or promote HIV reactivation.

## Abstract

The persistence of HIV latent reservoir is the major challenge to HIV cure because latent viruses serve as sources for viral rebound upon ART cessation. Mechanisms regulating viral persistence are not well understood; thus, there is a compelling need for research focusing on addressing the knowledge gap related to HIV persistence. The present study focuses on the effect of extracellular condensates (ECs) on latent HIV/SIV reactivation in the brain in the context of HIV infection using the SIV-infected rhesus macaque model. We used in vitro model systems of post-integration latency and primary peripheral blood mononuclear cells isolated from HIV-infected ART-suppressed donors to explore the role of basal ganglia (BG) isolated extracellular condensates (ECs) in reprogramming HIV latent cells. We found that BG ECs from uninfected macaques (VEH) and SIV infected macaques (VEH | SIV) activated latent HIV transcription in various model systems. VEH | SIV ECs significantly increased the expression and production of viral antigen in latently infected cells. Activation of viral transcription, antigen expression, and latency reactivation was inhibited by ECs from the brain of macaques treated with Delta-9-tetrahydrocannabinol (THC) and infected with SIV (THC | SIV). Virus produced by latently infected cells treated with VEH | SIV ECs potentiated cell-cell and cell-free HIV transmission. VEH | SIV ECs also reversed dexamethasone-mediated inhibition of HIV transcription while TNFα-mediated reactivation of latency was reversed by THC | SIV ECs. Transcriptome and secretome analyses of total RNA and supernatants from latently infected cells treated with ECs revealed significant alterations in gene expression and cytokine secretion. THC | SIV ECs increased secretion of Th2 and decreased secretion of proinflammatory cytokines. Most strikingly, while VEH/SIV ECs robustly induced expression of HIV RNA in latently HIV-infected cells, increased the frequency of HIV gag p24 expressing cells in HIV-infected CD4 + T cells within PBMCs, and production of extracellular HIV gag p24, long-term low-dose THC administration enriched ECs with anti-inflammatory cargo that significantly diminished their ability to reactivate latent HIV, an indication that ECs are endogenous host factors that may regulate HIV persistence.

ECs isolated from SIV infected rhesus macaques (VEH | SIV ECs) are positive regulators of LTR-dependent HIV transcription and production of infectious viral particles in vitro.ECs isolated from THC treated SIV infected rhesus macaques (THC | SIV ECs) prevents the transcription and reactivation of HIV in latently infected cells and prevents production of HIV gag p24 and viral particles in vitro.ECs reprogram host transcriptome and secretome in manners that suppress or promote reactivation of latent HIV reservoir.These observations were made in HIV latently infected cell lines, including T cell lines, monocytes, microglia, as well as in primary peripheral blood mononuclear cells (PBMC) isolated from HIV-infected ART-suppressed donors.

ECs isolated from SIV infected rhesus macaques (VEH | SIV ECs) are positive regulators of LTR-dependent HIV transcription and production of infectious viral particles in vitro.

ECs isolated from THC treated SIV infected rhesus macaques (THC | SIV ECs) prevents the transcription and reactivation of HIV in latently infected cells and prevents production of HIV gag p24 and viral particles in vitro.

ECs reprogram host transcriptome and secretome in manners that suppress or promote reactivation of latent HIV reservoir.

These observations were made in HIV latently infected cell lines, including T cell lines, monocytes, microglia, as well as in primary peripheral blood mononuclear cells (PBMC) isolated from HIV-infected ART-suppressed donors.