Illuminating host-mycobacterial interactions with functional genomic screening to inhibit mycobacterial pathogenesis

Existing antibiotics are inadequate to defeat tuberculosis (TB), a leading cause of death worldwide. We sought potential targets for host-directed therapies (HDTs) by investigating the host immune response to mycobacterial infection. We used CRISPR/Cas9-mediated high-throughput genetic screens to identify perturbations that improve the survival of human phagocytic cells infected with Mycobacterium bovis BCG (Bacillus Calmette-Guerin), as a proxy for Mycobacterium tuberculosis (Mtb). Many of these perturbations constrained the growth of intracellular mycobacteria. We identified over 100 genes associated with diverse biological pathways as potential HDT targets. We validated key components of the type I interferon and aryl hydrocarbon receptor signaling pathways that respond to the small-molecule inhibitors cerdulatinib and CH223191, respectively; these inhibitors enhanced human macrophage survival and limited the intracellular growth of Mtb. Thus, high-throughput functional genomic screens can elucidate highly complex host-pathogen interactions and serve to identify HDTs with the potential to improve TB treatment.