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Ann Rheum Dis doi:10.1136/annrheumdis-2012-202944
  • Basic and translational research
  • Extended report

IL-7 receptor α expressing B cells act proinflammatory in collagen-induced arthritis and are inhibited by sympathetic neurotransmitters

  1. Rainer H Straub1
  1. 1Laboratory of Experimental Rheumatology and Neuroendocrine Immunology, Department of Internal Medicine I, University Hospital Regensburg, Regensburg, Germany
  2. 2Deptartment of Orthopaedic Surgery, University Hospital Regensburg, Asklepios Clinic Bad Abbach, Bad Abbach, Germany
  3. 3Experimental Orthopedics, ZMB/BioPark1; University Hospital Regensburg, Regensburg, Germany
  1. Correspondence to Dr Georg Pongratz, Laboratory of Exp. Rheumatology and Neuroendocrine Immunology, Department of Internal Medicine I, University Hospital Regensburg, Regensburg 93042, Germany; georg.pongratz{at}klinik.uni-regensburg.de
  • Accepted 24 February 2013
  • Published Online First 16 March 2013

Abstract

Objectives The sympathetic nervous system (SNS) as well as the interleukin (IL)-7/IL-7 receptor (IL-7R) system play a role in the pathogenesis of arthritis. However, the target cells and mechanisms involved are not fully resolved. The goal of this study was to determine if B cells are influenced by IL-7 and to investigate the possible interplay between the SNS and the IL-7/IL-7R system on B cells in arthritis.

Methods Collagen type II-induced arthritis (CIA) in DBA1 mice. ELISA to determine specific anti-CII antibodies. Fluorescence activated cell sorting (FACS) analysis to determine IL-7R+ cells and intracellular phosphorylated signal transducer and activator of transcription 5 (pSTAT5). Immunohistochemistry to show IL-7R+ B cells in rheumatoid arthritis (RA) and osteoarthritis (OA) synovial tissue.

Results IL-7 stimulated IL-7R+ mature B cells act proinflammatory (increased clinical score, increased anticollagen type II antibodies) after cell transfer in CIA. The sympathetic neurotransmitter norepinephrine abrogates this effect. Expression of IL-7Rα is increased when B cells are activated (anti-CD40 or lipopolysaccharide) in vitro and stimulating the IL-7R induces intracellular accumulation of pSTAT5. α- And β-adrenergic agonists show no influence on expression levels of IL-7R on activated B cells; however, intracellular IL-7R downstream signalling is abrogated via the β2-adreonceptor (β2AR) agonist terbutaline. IL-7R and β2AR are also expressed on B cells in synovial tissue from RA and OA patients.

Conclusions These data indicate that IL7R+ B cells have a proinflammatory role in arthritis which can be inhibited by the sympathetic neurotransmitter norepinephrine via inhibition of IL-7R signalling.