title: Global DNA methylation changes and differential gene expression in Anaplasma phagocytophilum-infected human neutrophils.
abstract: BACKGROUND
  Anaplasma phagocytophilum is an obligate intracellular prokaryotic pathogen that both infects and replicates within human neutrophils. The bacterium represses multiple antimicrobial functions while simultaneously increasing proinflammatory functions by reprogramming the neutrophil genome. Previous reports show that many observed phenotypic changes are in part explained by altered gene transcription. We recently identified that large chromosomal regions of the neutrophil genome are differentially expressed during A. phagocytophilum infection. Because of this, we sought to determine whether gene expression programs altered by infection were the result of changes in the host neutrophil DNA methylome.
  
  
  RESULTS
  Within 24 h of infection, marked increases in DNA methylation were observed genome-wide as compared with mock-infected controls and pharmacologic inhibition of DNA methyltransferases resulted in decreased bacterial growth. New regions of DNA methylation were enriched at intron and exon junctions; however, intragenic methylation did not correlate with altered gene expression. In contrast, intergenic DNA methylation was associated with A. phagocytophilum-induced gene expression changes. Within the major histocompatibility complex locus on chromosome 6, a region with marked changes in infection-induced differential gene expression, new regions of methylation were localized to boundaries of active and inactive chromatin.
  
  
  CONCLUSIONS
  These data strongly suggest that A. phagocytophilum infection, in addition to altering histone structure, alters DNA methylation and the epigenome of its host cell to promote survival and replication, providing evidence that such bacterial infection can radically alter the epigenome of its host cell.
authors.affiliation: Graduate Program in Cellular and Molecular Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD USA ; Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD USA ; Department of Pathology, University of Maryland School of Medicine, Baltimore, MD USA ; Department of Microbiology and Immunology, University School of Medicine, Baltimore, MD USA.
authors.forename: Sara H G
authors.initials: SH
authors.lastname: Sinclair
authors.affiliation: Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD USA.
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Yegnasubramanian
authors.affiliation: Graduate Program in Cellular and Molecular Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD USA ; Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD USA ; Department of Pathology, University of Maryland School of Medicine, Baltimore, MD USA ; Department of Microbiology and Immunology, University School of Medicine, Baltimore, MD USA.
authors.forename: J Stephen
authors.initials: JS
authors.lastname: Dumler
keywords: Anaplasma phagocytophilum; Cellular reprogramming; DNA methylation; Hypermethylation; MHC locus