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Hypomethylation of STAT1 and HLA-DRB1 is associated with type-I interferon-dependent HLA-DRB1 expression in lupus CD8+ T cells
  1. Shaylynn Miller1,
  2. Pei-Suen Tsou1,
  3. Patrick Coit1,
  4. Elizabeth Gensterblum-Miller1,
  5. Paul Renauer1,
  6. Dallas M Rohraff1,
  7. Nathan C Kilian1,
  8. Mark Schonfeld1,
  9. Amr H Sawalha1,2
  1. 1 Division of Rheumatology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
  2. 2 Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan, USA
  1. Correspondence to Dr Amr H Sawalha, Division of Rheumatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA; asawalha{at}umich.edu

Abstract

Objective We examined genome-wide DNA methylation changes in CD8+ T cells from patients with lupus and controls and investigated the functional relevance of some of these changes in lupus.

Methods Genome-wide DNA methylation of lupus and age, sex and ethnicity-matched control CD8+ T cells was measured using the Infinium MethylationEPIC arrays. Measurement of relevant cell subsets was performed via flow cytometry. Gene expression was quantified by qPCR. Inhibiting STAT1 and CIITA was performed using fludarabine and CIITA siRNA, respectively.

Results Lupus CD8+ T cells had 188 hypomethylated CpG sites compared with healthy matched controls. Among the most hypomethylated were sites associated with HLA-DRB1. Genes involved in the type-I interferon response, including STAT1, were also found to be hypomethylated. IFNα upregulated HLA-DRB1 expression on lupus but not control CD8+ T cells. Lupus and control CD8+ T cells significantly increased STAT1 mRNA levels after treatment with IFNα. The expression of CIITA, a key interferon/STAT1 dependent MHC-class II regulator, is induced by IFNα in lupus CD8+ T cells, but not healthy controls. CIITA knockdown and STAT1 inhibition experiments revealed that HLA-DRB1 expression in lupus CD8+ T cells is dependent on CIITA and STAT1 signalling. Coincubation of naïve CD4+ T cells with IFNα-treated CD8+ T cells led to CD4+ T cell activation, determined by increased expression of CD69 and cytokine production, in patients with lupus but not in healthy controls. This can be blocked by neutralising antibodies targeting HLA-DR.

Conclusions Lupus CD8+ T cells are epigenetically primed to respond to type-I interferon. We describe an HLA-DRB1+ CD8+ T cell subset that can be induced by IFNα in patients with lupus. A possible pathogenic role for CD8+ T cells in lupus that is dependent on a high type-I interferon environment and epigenetic priming warrants further characterisation.

  • CD8+ T cells
  • lupus
  • epigenteic priming
  • HLA-DRB1
  • interferon
  • epigenetics
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Footnotes

  • SM and P-ST contributed equally.

  • Handling editor Josef S Smolen

  • Contributors All authors listed contributed and fulfil authorship criteria as follows: Substantial contributions to the conception or design of the work or the acquisition, analysis or interpretation of data for the work; Drafting the work or revising it critically for important intellectual content; Final approval of the version to be published and Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding This work was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health grant number R01AI097134.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval This study was approved by the Institutional Review Board of the University of Michigan, and each study participant signed an approved written consent prior to participating in this study.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Raw and processed DNA methylation data from patients and controls have been deposited in Gene Expression Omnibus (GEO accession number GSE123003)

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