Genome-wide RNAi screen in IFN-?-treated human macrophages identifies genes mediating resistance to the intracellular pathogen Francisella tularensis.

ABSTRACT: Interferon-gamma (IFN-?) inhibits intracellular replication of Francisella tularensis in human monocyte-derived macrophages (HMDM) and in mice, but the mechanisms of this protective effect are poorly characterized. We used genome-wide RNA interference (RNAi) screening in the human macrophage cell line THP-1 to identify genes that mediate the beneficial effects of IFN-? on F. tularensis infection. A primary screen identified ?200 replicated candidate genes. These were prioritized according to mRNA expression in IFN-?-primed and F. tularensis-challenged macrophages. A panel of 20 top hits was further assessed by re-testing using individual shRNAs or siRNAs in THP-1 cells, HMDMs and primary human lung macrophages. Six of eight validated genes tested were also found to confer resistance to Listeria monocytogenes infection, suggesting a broadly shared host gene program for intracellular pathogens. The F. tularensis-validated hits included 'druggable' targets such as TNFRSF9, which encodes CD137. Treating HMDM with a blocking antibody to CD137 confirmed a beneficial role of CD137 in macrophage clearance of F. tularensis. These studies reveal a number of important mediators of IFN-? activated host defense against intracellular pathogens, and implicate CD137 as a potential therapeutic target and regulator of macrophage interactions with Francisella tularensis.

SUBMITTER: Zhou H 

PROVIDER: S-EPMC3281001 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature