Sunday, November 24, 2024
11/24/2024
One of the principal obstacles to curing HIV is the existence of viral reservoirs in distinct compartments and cell types that are unaffected by antiretroviral therapy (ART). In the central nervous system (CNS), these reservoirs are comprised of myeloid cells, such as perivascular macrophages and microglia. Critically, these reservoirs are generally established prior to the initiation of ART and the presence of ART in the CNS does not affect the established reservoir in long-lived myeloid populations. Thus, even in individuals on suppressive ART, persistently infected CNS macrophages and microglia can drive ongoing neuroinflammation and provide a source of HIV for viral recrudescence during medication hiatus or failure. Our ability to eliminate these reservoirs is severely limited by the lack of understanding of the transcriptional and epigenetic regulation of HIV in myeloid cells. To effectively target and eliminate CNS reservoirs in people living with HIV (PLWH), it is critical to define the transcriptional mechanisms mediating persistent infection in distinct CNS myeloid populations. The impact of HIV infection in the CNS is heightened in PLWH who have substance use disorders, including those who take and/or misuse therapeutic drugs such as benzodiazepines (BDZ). Benzodiazepines are used by more than 30 million Americans, have high abuse liability and misuse of these drugs accounts for 15 – 20% of their use. Benzodiazepines are prescribed to a growing number of PLWH and are associated with an increased risk of neurocognitive symptoms in this population. Little is known about the mechanisms by which BDZ impact HIV neuropathogenesis. Our published and preliminary data indicate that BDZ can alter the transcriptional regulation of HIV infection. To better understand and treat the development of neuroHIV in PLWH who use and/or misuse BDZ, it is vital to determine who benzodiazepines affect the transcriptional programs in myeloid cells. We hypothesize that both macrophages and microglia enter a semi-quiescent transcriptional state during ART exposure and that benzodiazepines disrupt this state and increase transcriptional activity and viral replication. Our data show that the BDZ Xanax, as well as some latency reactivation agents, mediate a dose-dependent increase in p24 production in infected, ART-treated cells. Our preliminary studies suggest these effects may result from BDZ interactions with the epigenetic regulator RUNX1. We posit that these changes in HIV replication in myeloid cells reflect the epigenetic state of the provirus. Thus, the growing population of PLWH who use BDZ is at greater risk of more severe neuropathogenesis. It also suggests that BDZ may provide the basis for novel therapeutics to manipulate HIV transcription in myeloid cells. Therefore, we will evaluate the transcriptional and epigenetic mechanisms sustaining the semi-quiescent state of HIV transcription in ART- treated human macrophages (Aim 1), define the differences in transcriptional and epigenetic processes in different types of myeloid cells using human syngeneic iPSC-derived macrophages and microglia (Aim 2), and examine the effect of benzodiazepines on transcription HIV-infected, ART-treated myeloid cells (Aim 3).
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