Persistent type I interferon signaling within the brain of people with HIV on ART with cognitive impairment.

To better understand the molecular mechanism that drives neuroinflammation, we analyzed the protein profiles of 27 brains from HIV with HIV (PWH) on antiretroviral therapy (ART), including various stages of HIV-associated neurocognitive disorders (HAND), and compared them to 9 HAND-negative controls. We found that most of the proteins that were increased-about 66.7%-were involved in immune response pathways. Of these, 23.3% were specifically related to type I interferon (IFN-I) signaling, which remains active in the brain through both HIV-related and unrelated mechanisms. Using single-cell RNA sequencing (scRNA-seq) on brain tissues collected during rapid autopsies from participants in the Last Gift cohort, we found that IFN-I signaling was especially strong in astrocytes, microglia (MG), and endothelial cells. In a mini-brain organoid model of acute HIV infection, IFN-I signaling was also highly active in astrocytes but less so in MG. Interestingly, IFN-I activation can happen without HIV being present-expression of human endogenous retrovirus-W1 (HERV-W1) Env can directly trigger this response in astrocytes, and it continues in glial cells even with effective ART. Together, our findings point to persistent IFN-I activation in glial and endothelial cells in the brain, which may contribute to neuroinflammation and cognitive disorders in PWH on ART.