Frontiers in Immunology (Jun 2018)

CD19+CD24hiCD38hi B Cells Are Expanded in Juvenile Dermatomyositis and Exhibit a Pro-Inflammatory Phenotype After Activation Through Toll-Like Receptor 7 and Interferon-α

  • Christopher J. M. Piper,
  • Meredyth G. Ll. Wilkinson,
  • Meredyth G. Ll. Wilkinson,
  • Claire T. Deakin,
  • Claire T. Deakin,
  • Claire T. Deakin,
  • Georg W. Otto,
  • Georg W. Otto,
  • Stefanie Dowle,
  • Stefanie Dowle,
  • Chantal L. Duurland,
  • Stuart Adams,
  • Emiliano Marasco,
  • Elizabeth C. Rosser,
  • Anna Radziszewska,
  • Anna Radziszewska,
  • Rita Carsetti,
  • Yiannis Ioannou,
  • Yiannis Ioannou,
  • Philip L. Beales,
  • Philip L. Beales,
  • Daniel Kelberman,
  • Daniel Kelberman,
  • David A. Isenberg,
  • David A. Isenberg,
  • Claudia Mauri,
  • Kiran Nistala,
  • Lucy R. Wedderburn,
  • Lucy R. Wedderburn,
  • Lucy R. Wedderburn

DOI
https://doi.org/10.3389/fimmu.2018.01372
Journal volume & issue
Vol. 9

Abstract

Read online

Juvenile dermatomyositis (JDM) is a rare form of childhood autoimmune myositis that presents with proximal muscle weakness and skin rash. B cells are strongly implicated in the pathogenesis of the disease, but the underlying mechanisms are unknown. Therefore, the main objective of our study was to investigate mechanisms driving B cell lymphocytosis and define pathological features of B cells in JDM patients. Patients were recruited through the UK JDM Cohort and Biomarker study. Peripheral blood B cell subpopulations were immunophenotyped by flow cytometry. The results identified that immature transitional B cells were significantly expanded in active JDM, actively dividing, and correlated positively with disease activity. Protein and RNAseq analysis revealed high interferon alpha (IFNα) and TLR7-pathway signatures pre-treatment. Stimulation of B cells through TLR7/8 promoted both IL-10 and IL-6 production in controls but failed to induce IL-10 in JDM patient cells. Interrogation of the CD40–CD40L pathway (known to induce B cell IL-10 and IL-6) revealed similar expression of IL-10 and IL-6 in B cells cultured with CD40L from both JDM patients and controls. In conclusion, JDM patients with active disease have a significantly expanded immature transitional B cell population which correlated with the type I IFN signature. Activation through TLR7 and IFNα may drive the expansion of immature transitional B cells in JDM and skew the cells toward a pro-inflammatory phenotype.

Keywords