The immunosuppressive Tuberculosis-associated microenvironment inhibits viral replication and promotes HIV-1 latency in CD4+ T cells
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is the most common coinfection among people living with HIV-1. This coinfection alters the efficacy of the immune response against both HIV-1 and Mtb, and is associated with accelerated HIV-1 disease progression and reduced survival. Enhanced HIV-1 replication in macrophages induced by Mtb coinfection may contribute to the worsened clinical outcomes observed in HIV-1/TB coinfected individuals. However, the impact of the HIV-1/TB coinfection on HIV-1 replication and latency in CD4+ T cells remains poorly studied.  In this study, we used the acellular fraction of tuberculous pleural effusion (TB-PE) as a proxy for the microenvironment generated by Mtb infection. Using this physiologically relevant fluid, we investigated whether viral replication and HIV-1 latency in CD4+ T cells are affected by a TB-associated microenvironment. Interestingly, our results revealed that TB-PE shaped the transcriptional profile of CD4+ T cells impairing T cell receptor-dependent cell activation and decreased HIV-1 replication. Moreover, this immunosuppressive TB microenvironment promoted viral latency and inhibited HIV-1 reactivation in CD4+ T cells from people living with HIV-1.  This study indicates that the immune response induced by TB may contribute to the persistence of the viral reservoir by silencing HIV-1 expression in individuals coinfected with both pathogens, allowing the virus to persist undetected by the immune system and increasing the size of the HIV-1 latent reservoir in cells at the site of the coinfection. Overall design: To understand the effect of the immune response to TB on CD4+ T cells and its potential impact on HIV-1 replication, we assessed the transcriptional profile of primary CD4+ T cells treated with TB-PE. Bulk RNA sequencing (RNAseq) was performed on primary CD4+ T cells isolated from 3 healthy donors and treated with TB-PE. In addition, since T cell activation increases CD4+ T cells susceptibility to HIV-1 infection, we also investigated the impact of TB-PE on CD4 T cells activated by anti-CD3/CD28 antibodies.