Mycobacterium tuberculosis Induced Interferon Pathways Distinguish Responses of Alveolar and Monocyte-derived Human Macrophages
Monica Campo 1, Kimberly A. Dill-McFarland 2, Glenna J. Peterson 2, Basilin Benson 3, Shawn J Skerrett 2, Thomas R. Hawn 2
1 Department of Medicine, University of Minnesota, Minneapolis, MN
2 Department of Medicine, University of Washington, Seattle, WA
3 Benaroya Research Institute, Seattle, WA
The study was supported by NIH grants K08AI130266 to MC, K24AI137310 (TRH), and contract number 75N93019C00070 (TRH).
Alveolar macrophages (AMs) and recruited monocyte-derived macrophages (MDMs) mediate early lung immune responses to Mycobacterium tuberculosis (Mtb). Differences in the response of these distinct cell types is poorly understood and may provide insight into mechanisms of TB pathogenesis. We hypothesized that Mtb induces unique and essential anti-microbial pathways in human AMs compared to MDMs.
Using paired human AMs and 5-day MCSF-derived MDMs from 6 healthy volunteers, we infected cells for 6 hours with Mtb H37Rv, isolated RNA, and analyzed transcriptomic profiles with RNASeq. We found 681 genes that were Mtb-dependent in AMs compared to MDMs, 107 that were induced in both cell types but in different directions, and 4538 that were Mtb-dependent in MDMs but not AMs (FDR < 0.05). Using hypergeometric enrichment of DEGs in Broad Hallmark gene sets, we found that IFNA Response and IFNG Response were the only gene sets selectively induced in Mtb-infected AM (FDR < 10E-13), a finding confirmed by gene set enrichment analysis (FDR < 0.05). In contrast, MYC targets, unfolded protein response and MTORC1 signaling, were selectively enriched in MDMs (FDR < 0.05). IFNA1, IFNA8, IFNE, and IFNL1 were specifically and highly upregulated in AMs compared to MDMs at baseline and/or after Mtb infection. IFNA8 modulated Mtb-induced pro-inflammatory cytokines and, compared to other interferons, stimulated unique transcriptional profiles. Several DNA sensors and Interferon Regulatory Factors had higher expression at baseline and/or after Mtb infection in AMs compared to MDMs. These findings demonstrate that Mtb infection induced unique transcriptional responses in human AMs compared to MDMs, including upregulation of the IFN response pathway and specific DNA sensors and interferon genes.