title: Elevated receptor for activated C kinase 1 expression is involved in intracellular Ca2+ influx and potentially associated with compromised regulatory T cell function in patients with asthma.
abstract: BACKGROUND
  Regulatory T cells (T(regs)) are activated during anergy in response to T cell receptor (TCR) activation and functional immune suppression. Anergy of paediatric T(regs) is partially dependent on intracellular calcium mobility; following TCR activation, T(regs) do not exhibit increased intracellular Ca(2+) concentration ([Ca(2+) ](i)).
  
  
  OBJECTIVE
  We determined whether [Ca(2+) ](i) in adult T(regs) defined their anergy, if intracellular Ca(2+) movement was linked to regulatory functions, whether [Ca(2+)](i) was indicative of asthma pathology, and the potential molecular mechanism responsible for Ca(2+) movement in T(regs).
  
  
  METHODS
  T(regs) were purified by the magnetic bead method, and their regulatory functions were assessed by monitoring carboxyfluorescein succinimidyl ester-labelled responder T cell proliferation. The Ca(2+) response of Fura-2-labelled cells was measured using a video image analysis system. To analyse the functions of T(regs) at the molecular level, we generated Jurkat Tet-On(®) clones with doxycycline (Dox)-induced forkhead box P3 (FOXP3) protein expression.
  
  
  RESULTS
  CD4(+) CD25(+) CD127(-/low) T(regs) from participants without asthma did not elicit Ca(2+) influx in response to TCR activation, exhibited little proliferation and suppressed proliferation of CD4(+) CD25(-) T cells. In contrast, under similar conditions, T(regs) from patients with asthma exhibited increased [Ca(2+)](i) and robust proliferation with partial loss of regulatory functions. FOXP3 protein levels in Tet-On(®) clones were high after both 2- and 5-day Dox treatment; however, 5-day cells were comparable with T(regs) from patients with asthma, whereas 2-day cells were similar to T(regs) from participants without asthma. Increasing [Ca(2+)](i) induced a high level of receptor for activated C kinase 1 (RACK1) expression in 5-day cells.
  
  
  CONCLUSIONS
  We confirmed that T(regs) in patients with asthma are functionally impaired and that the abnormal regulatory functions of these cells can be analysed by [Ca(2+)](i) following TCR engagement. Furthermore, the impaired functioning of T(regs) evident in patients with asthma may be due to a high level of RACK1.
authors.affiliation: Department of Pharmacogenomics, Showa University School of Pharmacy, Shinagawa-ku, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Negoro
authors.forename: S
authors.initials: S
authors.lastname: Shimizu
authors.forename: M
authors.initials: M
authors.lastname: Narushima
authors.forename: A H
authors.initials: AH
authors.lastname: Banham
authors.forename: H
authors.initials: H
authors.lastname: Wakabayashi
authors.forename: R
authors.initials: R
authors.lastname: Takayanagi
authors.forename: T
authors.initials: T
authors.lastname: Hagiwara
authors.forename: G
authors.initials: G
authors.lastname: Roncador
authors.forename: T
authors.initials: T
authors.lastname: Osabe
authors.forename: T
authors.initials: T
authors.lastname: Yanai
authors.forename: M
authors.initials: M
authors.lastname: Kin
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: A
authors.initials: A
authors.lastname: Endo
authors.forename: H
authors.initials: H
authors.lastname: Akiyama
authors.forename: Y
authors.initials: Y
authors.lastname: Nakano
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000954:Antigens, Surface / Q000378:metabolism; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D016022:Case-Control Studies; D002460:Cell Line; D049109:Cell Proliferation; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D016130:Immunophenotyping; D042541:Intracellular Space / Q000378:metabolism; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D012307:Risk Factors; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism*
chemical_list: D000305:Adrenal Cortex Hormones; D000954:Antigens, Surface; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D002118:Calcium
keywords: FOXP3; RACK1; asthma; calcium; regulatory T cell