It is only recently that the field became aware that certain tissue resident macrophages, including alveolar macrophages and microglial cells, are fetal stem cell derived lineages that behave markedly differently from blood monocyte derived macrophages. With such knowledge we need revisit the role of tissue resident macrophages as HIV-1 reservoirs and their contribution to viral persistence. We have shown that regulatory pathways in infected macrophages, such as pro-survival pathways, can be inhibited by targeting specific lncRNAs, thus driving selective cell death in infected but not uninfected macrophages. Such observations lay the groundwork for eradication of HIV-1 reservoirs, however, biologics, such as lncRNAs, are not as tractable as small molecule inhibitors to progress into therapeutics.

We have extensive, documented expertise in macrophage biology in both mouse and human lung, and we have maintained a productive anti-TB drug discovery program based on phenotypic screening for compounds active in infected macrophages. With this expertise we propose the identification and functional characterization of small molecule epigenetic inhibitors capable of modifying host macrophage programming to drive selective induction of cell death in specific myeloid cell lineages, and probing the underlying mechanism(s).

Our Specific Aims are:
1. Phenotypic Profiling HIV-1 infected HMDMs and AMs by transcriptional analysis. We will conduct transcriptional profiling on HIV-1 infected HMDMs and AMs to assess the diversity of the cellular responses to infection in both active and latent infection states in the two lineages.

2. Screening small molecule inhibitors of epigenetic programming in experimental infection in HMDMs and AMs, and in HC69.5 microglial cells. We have a library of 735 small molecule epigenetic inhibitors and will screen this compound collection against HIV-1 infected HMDMs, AMs, and against the immortalized human microglial cell line HC69.5, with the emphasis on identifying compounds that drive cell death across the different macrophage lineages and infection models.

3. Progressing hits through mode-of-action studies to identify actionable compounds. We propose analysis of HIV-1/macrophage biology prioritizing compounds that induce cell death in HIV-1 infected macrophages. Finally, to evaluate candidate compounds for their ability to drive cell death and suppress viral persistence we will assess activity through ex vivo drug treatment and cell survival and viral outgrowth from AMs from viremic HIV-1 positive human donors in Malawi.