Persistent immune activation in HIV-1 infected ex vivo model tissues subjected to antiretroviral therapy: Soluble and extracellular vesicle-associated cytokines

BACKGROUND: Residual immune activation after successful antiretroviral therapy (ART) in HIV-1-infected patients is associated with the increased risk of complications. Cytokines, both soluble and extracellular vesicle (EV)-associated, may play an important role in this immune activation. SETTING: Ex vivo tissues were infected with X4LAI04 or R5SF162 HIV-1. Virus replicated for 16 days, or tissues were treated with the anti-retroviral drug ritonavir. METHODS: Viral replication and production of 33 cytokines in soluble and EV-associated forms were measured with multiplexed bead-based assays. RESULTS: Both variants of HIV-1 efficiently replicated in tissues and triggered upregulation of soluble cytokines, including IL-1beta, IL-7, IL-18, IFN-gamma, MIP-1alpha, MIP-1beta, and RANTES. A similar pattern was observed in EV-associated cytokine release by HIV-infected tissues. In addition, TNF-alpha and RANTES demonstrated a significant shift to a more soluble form compared with EV-associated cytokines. Ritonavir treatment efficiently suppressed viral replication; however, both soluble and EV-associated cytokines remained largely upregulated after 13 days of treatment. EV-associated cytokines were more likely to remain elevated after ART. Treatment of uninfected tissues with ritonavir itself did not affect cytokine release. CONCLUSIONS: We demonstrated that HIV-1 infection of ex vivo lymphoid tissues resulted in their immune activation as evaluated by upregulation of various cytokines, both soluble and EV-associated. This upregulation persisted despite inhibition of viral replication by ART. Thus, similar to in vivo, HIV-1-infected human tissues ex vivo continue to be immune-activated after viral suppression, providing a new laboratory model to study this phenomenon.