Transcriptome and chromatin accessibility mapping reveals a type I Interferon response triggered by Mycobacterium tuberculosis infection

Abstract

Tuberculosis, a deadly infectious lung disease caused by Mycobacterium tuberculosis (Mtb), remains the leading cause of bacterial disease-related deaths worldwide. The success of Mtb as a human pathogen depends on its ability to manipulate host immune response pathways, many of which are regulated by epigenetic mechanisms that control the accessibility of chromatin to the transcriptional machinery. Recent reports suggest that host phosphatases, such as PPM1A, may play a role in the regulation of chromatin accessibility during bacterial infections. However, changes in genome-wide chromatin accessibility during Mtb infection and whether PPM1A plays a role in this process remains unknown. Using combinatorial chromatin accessibility (ATAC-seq) and transcriptomics (RNA-seq) profiling of wild-type (WT), PPM1A knockout (ΔPPM1A) and PPM1A overexpressing (PPM1A+) macrophages, we demonstrate that Mtb infection induces global chromatin remodeling consistent with changes in gene expression signatures. The strongest concordant chromatin accessibility and gene expression signature triggered by Mtb infection was enriched for genes involved in the type I interferon (IFN) signaling pathways. Modulation of PPM1A expression results in altered chromatin accessibility signatures during Mtb infection that are reflected in the total number, chromosome location and directionality of change. Transcription factor motif analysis revealed an enrichment for transcription factors involved in the type I IFN pathway during Mtb infection, including IRF4, MEF2A, CEBPD and JDP2. In contrast, both deletion and overexpression of PPM1A produced unique transcription factor enrichment signatures linked to the genomic regions with altered chromatin accessibility. Our study demonstrates that altered type I IFN responses in Mtb-infected macrophages occurs as a result of genome-wide changes in chromatin accessibility, and that PPM1A likely plays a role in a subset of these signatures.