Characterization of HIV-1 Infection in Microglia-Containing Human Cerebral Organoids

Abstract

The achievement of an HIV cure is dependent on the eradication or permanent silencing of HIV-latent viral reservoirs, including the understudied central nervous system (CNS) reservoir. This requires a deep understanding of the molecular mechanisms of HIV’s entry into the CNS, latency establishment, persistence, and reversal. Therefore, representative CNS culture models that reflect the intercellular dynamics and pathophysiology of the human brain are urgently needed in order to study the CNS viral reservoir and HIV-induced neuropathogenesis. In this study, we characterized a human cerebral organoid model in which microglia grow intrinsically as a CNS culture model to study HIV infection in the CNS. We demonstrated that both cerebral organoids and isolated organoid-derived microglia (oMG), infected with replication-competent HIVbal reporter viruses, support productive HIV infection via the CCR5 co-receptor. Productive HIV infection was only observed in microglial cells. Fluorescence analysis revealed microglia as the only HIV target cell. Susceptibility to HIV infection was dependent on the co-expression of microglia-specific markers and the CD4 and CCR5 HIV receptors. Altogether, this model will be a valuable tool within the HIV research community to study HIV–CNS interactions, the underlying mechanisms of HIV-associated neurological disorders (HAND), and the efficacy of new therapeutic and curative strategies on the CNS viral reservoir.

3D engineered tissue models for studying human-specific infectious viral diseases

“…HIV can affect many organs because it can travel through blood and lymph vessels, destroying immune cells during infection [ 169 ]. Based on these characteristics, HIV-infected immune cells are produced mainly in 3D in vitro models and then co-cultured with various organ models to conduct experiments [ 170 ]. To verify the malfunction of HIV-infected immune cells, a 3D human-derived cell-based organ model is needed as a microenvironment.…”

“…To verify the malfunction of HIV-infected immune cells, a 3D human-derived cell-based organ model is needed as a microenvironment. Gumbs et al prepared cerebral organoids containing microglia and analyzed the changes after infection with HIV [ 170 ]. Existing cerebral organoids had less than 1% microglia, but the authors additionally co-cultured microglia to confirm the interaction between HIV and microglia.…”

The potential role of HIV-1 latency in promoting neuroinflammation and HIV-1-associated neurocognitive disorder

“…A significant advance is the use of iMG to study responses to antiretroviral drugs [55], HIV-1 replication and pathogenesis, and microglial activation [34,56]. The culmination of this approach, which may allow the study of microglia in the context of neurons and astrocytes, is the use of 3D cerebral organoids generated from iPSC-derived neural progenitor cells combined with iMG [57].…”

Shock and kill within the CNS: A promising HIV eradication approach?

“…However, HIV reverse transcription has been shown to be inhibited via the expression of the restriction factor SAM domain and HD domain‐containing protein 1 in cells of the myeloid lineage 108 . Nevertheless, human primary microglia cultures and in vitro microglial culture models have shown productive HIV infection with M‐tropic viruses via the CD4 and CCR5 receptor, but did not support infection with T‐tropic viruses 107,109,110 . Moreover, studies with SIV in rhesus macaques and HIV‐infected humanized immunodeficient mice show productive infection and suspected latency of replication competent virus in microglia and perivascular macrophages during ART suppression as shown by increase in viral load upon cell stimulation 23,111–113 .…”

“…Recent technologic advancements in stem cell research have enabled the generation of a variety of CNS cell types including cerebral organoids and opened unique opportunities to study host‐virus interactions in the CNS 123 . HIV infection of induced pluripotent stem cell (iPSC)‐derived microglia and organoid‐derived microglia, decreased after the 1st week of infection, resembling HIV infection in vivo 109,110,116 . 2D coculture models incorporating iPSC‐derived microglia with iPSC‐derived astrocytes and/or iPSC‐derived neurons and 3D cerebral organoids can be used to address the true cellular targets of HIV in the CNS and the role of surrounding CNS cells in supporting infection and the development of neural injury 109,124,125 .…”