Deciphering the genetic control of gene expression following Mycobacterium leprae antigen stimulation

PLoS Genet. 2017 Aug 9;13(8):e1006952. doi: 10.1371/journal.pgen.1006952. eCollection 2017 Aug.

Abstract

Leprosy is a human infectious disease caused by Mycobacterium leprae. A strong host genetic contribution to leprosy susceptibility is well established. However, the modulation of the transcriptional response to infection and the mechanism(s) of disease control are poorly understood. To address this gap in knowledge of leprosy pathogenicity, we conducted a genome-wide search for expression quantitative trait loci (eQTL) that are associated with transcript variation before and after stimulation with M. leprae sonicate in whole blood cells. We show that M. leprae antigen stimulation mainly triggered the upregulation of immune related genes and that a substantial proportion of the differential gene expression is genetically controlled. Indeed, using stringent criteria, we identified 318 genes displaying cis-eQTL at an FDR of 0.01, including 66 genes displaying response-eQTL (reQTL), i.e. cis-eQTL that showed significant evidence for interaction with the M. leprae stimulus. Such reQTL correspond to regulatory variations that affect the interaction between human whole blood cells and M. leprae sonicate and, thus, likely between the human host and M. leprae bacilli. We found that reQTL were significantly enriched among binding sites of transcription factors that are activated in response to infection, and that they were enriched among single nucleotide polymorphisms (SNPs) associated with susceptibility to leprosy per se and Type-I Reaction, and seven of them have been targeted by recent positive selection. Our study suggested that natural selection shaped our genomic diversity to face pathogen exposure including M. leprae infection.

MeSH terms

  • Antigens, Bacterial / immunology*
  • Down-Regulation
  • Genetic Association Studies
  • Genetic Predisposition to Disease
  • Host-Pathogen Interactions / genetics
  • Humans
  • Leprosy / genetics*
  • Leprosy / immunology
  • Mycobacterium leprae
  • Polymorphism, Single Nucleotide
  • Principal Component Analysis
  • Quantitative Trait Loci*
  • RNA, Bacterial / isolation & purification
  • Up-Regulation

Substances

  • Antigens, Bacterial
  • RNA, Bacterial

Grants and funding

This work was supported by a Foundation grant from the Canadian Institutes of Health Research (CIHR FDN – 14332) to ES. This research was supported through resource allocation in the Guillimin high performance computing cluster by Compute Canada (www.computecanada.ca) and Calcul Québec (http://www.calculquebec.ca/) (jrt-675-01). JM was supported by a CIHR fellowship (MFE-127384) and in part by a grant from the Laboratory of Excellence Integrative Biology of Emerging Infectious Diseases (LabEx IBEID: http://www.pasteur.fr/labex/ibeid). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.