Investigating alveolar macrophages in PLWH as targets for HIV persistence, residual inflammation and immune activation

ABSTRACT HIV cellular reservoirs, residual inflammation and immune activation persist despite antiretroviral therapy (ART) in people living with HIV (PLWH), and are a barrier to eradicating HIV and achieving cure. Therefore, we urgently need to elucidate pathways induced by persistent HIV and the mechanisms that drive immune activation, viral

rebound and co-infection. While most studies have focused on memory CD4 T cells as latent HIV reservoirs, growing evidence supports a role for macrophages. Proviral DNA and RNA have been detected in alveolar macrophages (AMs) from bronchoalveolar lavage (BAL) of PLWH, implicating AMs as potential reservoirs for

HIV. We previously reported that AMs from PLWH on ART are impaired compared to those to are HIV-uninfected, with altered inflammatory phenotypes and high levels of oxidative stress, consistent with the higher susceptibility to pulmonary infections like bacterial pneumonia and tuberculosis (TB) seen in PLWH on ART. However, lung

compartments from PLWH have not been well studied and AM responses to common co-infecting pathogens such as Mycobacterium tuberculosis (Mtb) and Streptococcus pneumoniae (Spn) are poorly understood. We hypothesize that AMs from PLWH on ART contribute to residual inflammation and immune activation in lung

compartments, serve as reservoirs for persistence of HIV DNA/RNA/proteins and mount aberrant inflammatory responses to co-infection with respiratory pathogens. Our hypotheses are supported by published and preliminary data from single cell transcriptomics, flow cytometry, metabolism and immunologic studies of BAL

from PLWH on ART. To test these hypotheses, we have assembled a multidisciplinary team with expertise in lung immunology/respiratory infections (Rengarajan, MPI), HIV virology/macrophage reservoirs (Baek Kim, MPI), HIV and pulmonary medicine (Staitieh, MPI), and clinical collaborators (Marconi, Auld, Flenaugh) with

extensive experience in research bronchoscopy studies at the Ponce Center/Grady Health System, Atlanta, GA. We will conduct human BAL studies from PLWH on ART, and immunological non-responders (INRs) who are virologically suppressed but fail to reconstitute CD4 counts, to comprehensively investigate AMs as HIV

reservoirs. We will use cutting-edge technologies, virologic and immunologic approaches to uncover the mechanisms driving immune dysfunction in PLWH on ART. In Aim 1 we will determine the contribution of AMs as reservoirs for HIV persistence by defining the HIV proviral DNA, RNA and protein landscape in cellular

subpopulations from the BAL of PLWH on ART, INRs and HIV-uninfected persons. In Aim 2 we will test the hypothesis that lung compartments of PLWH on ART show dysregulation of AM and T cell immunometabolism, phenotype and function. In Aim 3 we will define the mechanisms that drive impaired AM and T cell responses

bacterial pathogens in ART responders and non-responders living with HIV. Together, our proposed studies will provide unprecedented new insights into AM and HIV dynamics, identify mechanisms that drive defective AM responses to clinically relevant pulmonary infections in PLWH, and novel targets for therapeutics.