Heterogeneous GM-CSF signaling in macrophages is associated with control of Mycobacterium tuberculosis

Variability in bacterial sterilization is a key feature of Mycobacterium tuberculosis (Mtb) disease. In a population of human macrophages, there are macrophages that restrict Mtb growth and those that do not. However, the sources of heterogeneity in macrophage state during Mtb infection are poorly understood. Here, we perform RNAseq on restrictive and permissive macrophages and reveal that the expression of genes involved in GM-CSF signaling discriminates between the two subpopulations. We demonstrate that blocking GM-CSF makes macrophages more permissive of Mtb growth while addition of GM-CSF increases bacterial control. In parallel, we find that the loss of bacterial control that occurs in HIV-Mtb coinfected macrophages correlates with reduced GM-CSF secretion. Treatment of coinfected cells with GM-CSF restores bacterial control. Thus, we leverage the natural variation in macrophage control of Mtb to identify a critical cytokine response for regulating Mtb survival and identify components of the antimicrobial response induced by GM-CSF.
GM-CSF has been implicated in Mycobacterium tuberculosis (Mtb) host control. Here, the authors show that activation of GM-CSF discriminates Mtb-restrictive from -permissive macrophages while co-infection with HIV disrupts GM-CSF-mediated signaling, rendering macrophages susceptible to bacterial infection.