title: Identification of host-targeted small molecules that restrict intracellular Mycobacterium tuberculosis growth.
abstract: Mycobacterium tuberculosis remains a significant threat to global health. Macrophages are the host cell for M. tuberculosis infection, and although bacteria are able to replicate intracellularly under certain conditions, it is also clear that macrophages are capable of killing M. tuberculosis if appropriately activated. The outcome of infection is determined at least in part by the host-pathogen interaction within the macrophage; however, we lack a complete understanding of which host pathways are critical for bacterial survival and replication. To add to our understanding of the molecular processes involved in intracellular infection, we performed a chemical screen using a high-content microscopic assay to identify small molecules that restrict mycobacterial growth in macrophages by targeting host functions and pathways. The identified host-targeted inhibitors restrict bacterial growth exclusively in the context of macrophage infection and predominantly fall into five categories: G-protein coupled receptor modulators, ion channel inhibitors, membrane transport proteins, anti-inflammatories, and kinase modulators. We found that fluoxetine, a selective serotonin reuptake inhibitor, enhances secretion of pro-inflammatory cytokine TNF-α and induces autophagy in infected macrophages, and gefitinib, an inhibitor of the Epidermal Growth Factor Receptor (EGFR), also activates autophagy and restricts growth. We demonstrate that during infection signaling through EGFR activates a p38 MAPK signaling pathway that prevents macrophages from effectively responding to infection. Inhibition of this pathway using gefitinib during in vivo infection reduces growth of M. tuberculosis in the lungs of infected mice. Our results support the concept that screening for inhibitors using intracellular models results in the identification of tool compounds for probing pathways during in vivo infection and may also result in the identification of new anti-tuberculosis agents that work by modulating host pathways. Given the existing experience with some of our identified compounds for other therapeutic indications, further clinically-directed study of these compounds is merited.
authors.affiliation: The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America ; Division of Infectious Disease and Vaccinology, School of Public Health, University of California, Berkeley, Berkeley, California, United States of America.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Stanley
authors.affiliation: The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America ; Division of Infectious Disease, Massachusetts General Hospital, Boston, Massachusetts, United States of America ; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America.
authors.forename: Amy K
authors.initials: AK
authors.lastname: Barczak
authors.affiliation: The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America.
authors.forename: Melanie R
authors.initials: MR
authors.lastname: Silvis
authors.affiliation: Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America.
authors.forename: Samantha S
authors.initials: SS
authors.lastname: Luo
authors.affiliation: Division of Infectious Disease and Vaccinology, School of Public Health, University of California, Berkeley, Berkeley, California, United States of America.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Sogi
authors.affiliation: The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America.
authors.forename: Martha
authors.initials: M
authors.lastname: Vokes
authors.affiliation: The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America.
authors.forename: Mark-Anthony
authors.initials: MA
authors.lastname: Bray
authors.affiliation: The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Carpenter
authors.affiliation: The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Moore
authors.affiliation: Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America.
authors.forename: Noman
authors.initials: N
authors.lastname: Siddiqi
authors.affiliation: Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Rubin
authors.affiliation: The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America ; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America ; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Deborah T
authors.initials: DT
authors.lastname: Hung
mesh_terms: D000818:Animals; D000995:Antitubercular Agents / Q000494:pharmacology; D004195:Disease Models, Animal; D057166:High-Throughput Screening Assays; D054884:Host-Pathogen Interactions / Q000502:physiology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism* / Q000469:parasitology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014376:Tuberculosis / Q000378:metabolism*
chemical_list: D000995:Antitubercular Agents