Systematic annotation of celiac disease loci refines pathological pathways and suggests a genetic explanation for increased interferon-gamma levels

Vinod Kumar, Javier Gutierrez-Achury, Kartiek Kanduri, Rodrigo Almeida, Barbara Hrdlickova, Daria V. Zhernakova, Harm-Jan Westra, Juha Karjalainen, Isis Ricano-Ponce, Yang Li, Anna Stachurska, Ettje F. Tigchelaar, Wayel H. Abdulahad, Harri Lahdesmaki, Marten H. Hofker, Alexandra Zhernakova, Lude Franke, Riitta Lahesmaa, Cisca Wijmenga, Sebo Withoff*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

42 Citations (Scopus)

Abstract

Although genome-wide association studies and fine mapping have identified 39 non-HLA loci associated with celiac disease (CD), it is difficult to pinpoint the functional variants and susceptibility genes in these loci. We applied integrative approaches to annotate and prioritize functional single nucleotide polymorphisms (SNPs), genes and pathways affected in CD. CD-associated SNPs were intersected with regulatory elements categorized by the ENCODE project to prioritize functional variants, while results from cis-expression quantitative trait loci (eQTL) mapping in 1469 blood samples were combined with co-expression analyses to prioritize causative genes. To identify the key cell types involved in CD, we performed pathway analysis on RNA-sequencing data from different immune cell populations and on publicly available expression data on non-immune tissues. We discovered that CD SNPs are significantly enriched in B-cell-specific enhancer regions, suggesting that, besides T-cell processes, B-cell responses play a major role in CD. By combining eQTL and co-expression analyses, we prioritized 43 susceptibility genes in 36 loci. Pathway and tissue-specific expression analyses on these genes suggested enrichment of CD genes in the Th1, Th2 and Th17 pathways, but also predicted a role for four genes in the intestinal barrier function. We also discovered an intricate transcriptional connectivity between CD susceptibility genes and interferon-gamma, a key effector in CD, despite the absence of CD-associated SNPs in the IFNG locus. Using systems biology, we prioritized the CD-associated functional SNPs and genes. By highlighting a role for B cells in CD, which classically has been described as a T-cell-driven disease, we offer new insights into the mechanisms and pathways underlying CD.

Original languageEnglish
Pages (from-to)397-409
Number of pages13
JournalHuman Molecular Genetics
Volume24
Issue number2
DOIs
Publication statusPublished - 15-Jan-2015

Keywords

  • GENOME-WIDE ASSOCIATION
  • CELL-DIFFERENTIATION
  • MULTIPLE COMMON
  • RISK VARIANTS
  • EXPRESSION
  • SIGNATURES
  • INITIATION
  • NETWORKS
  • REVEALS
  • GLIADIN

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