title: Expression of K2P5.1 potassium channels on CD4+ T lymphocytes correlates with disease activity in rheumatoid arthritis patients.
abstract: BACKGROUND
  CD4+ T cells express K(2P)5.1 (TWIK-related acid-sensitive potassium channel 2 (TASK2); KCNK5), a member of the two-pore domain potassium channel family, which has been shown to influence T cell effector functions. Recently, it was shown that K(2P)5.1 is upregulated upon (autoimmune) T cell stimulation. The aim of this study was to correlate expression levels of K(2P)5.1 on T cells from patients with rheumatoid arthritis (RA) to disease activity in these patients.
  
  
  METHODS
  Expression levels of K(2P)5.1 were measured by RT-PCR in the peripheral blood of 58 patients with RA and correlated with disease activity parameters (C-reactive protein levels, erythrocyte sedimentation rates, disease activity score (DAS28) scores). Twenty patients undergoing therapy change were followed-up for six months. Additionally, synovial fluid and synovial biopsies were investigated for T lymphocytes expressing K(2P)5.1.
  
  
  RESULTS
  K(2P)5.1 expression levels in CD4+ T cells show a strong correlation to DAS28 scores in RA patients. Similar correlations were found for serological inflammatory parameters (erythrocyte sedimentation rate, C-reactive protein). In addition, K(2P)5.1 expression levels of synovial fluid-derived T cells are higher compared to peripheral blood T cells. Prospective data in individual patients show a parallel behaviour of K(2P)5.1 expression to disease activity parameters during a longitudinal follow-up for six months.
  
  
  CONCLUSIONS
  Disease activity in RA patients correlates strongly with K(2P)5.1 expression levels in CD4+ T lymphocytes in the peripheral blood in cross-sectional as well as in longitudinal observations. Further studies are needed to investigate the exact pathophysiological mechanisms and to evaluate the possible use of K(2P)5.1 as a potential biomarker for disease activity and differential diagnosis.
authors.affiliation: Department of Neurology, University of Wuerzburg, Josef-Schneider-Str. 11, Wuerzburg 97080, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Bittner
authors.forename: Nicole
authors.initials: N
authors.lastname: Bobak
authors.forename: Martin
authors.initials: M
authors.lastname: Feuchtenberger
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Herrmann
authors.forename: Kerstin
authors.initials: K
authors.lastname: Göbel
authors.forename: Raimund W
authors.initials: RW
authors.lastname: Kinne
authors.forename: Anker J
authors.initials: AJ
authors.lastname: Hansen
authors.forename: Thomas
authors.initials: T
authors.lastname: Budde
authors.forename: Christoph
authors.initials: C
authors.lastname: Kleinschnitz
authors.forename: Oliver
authors.initials: O
authors.lastname: Frey
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Tony
authors.forename: Heinz
authors.initials: H
authors.lastname: Wiendl
authors.forename: Sven G
authors.initials: SG
authors.lastname: Meuth
mesh_terms: D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology*; D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002469:Cell Separation; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D024683:Potassium Channels, Tandem Pore Domain / Q000096:biosynthesis*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C410295:KCNK5 protein, human; D024683:Potassium Channels, Tandem Pore Domain