title: Defects in IL-2R signaling contribute to diminished maintenance of FOXP3 expression in CD4(+)CD25(+) regulatory T-cells of type 1 diabetic subjects.
abstract: OBJECTIVE
  In humans, multiple genes in the interleukin (IL)-2/IL-2 receptor (IL-2R) pathway are associated with type 1 diabetes. However, no link between IL-2 responsiveness and CD4(+)CD25(+)FOXP3(+) regulatory T-cells (Tregs) has been demonstrated in type 1 diabetic subjects despite the role of these IL-2-dependent cells in controlling autoimmunity. Here, we address whether altered IL-2 responsiveness impacts persistence of FOXP3 expression in Tregs of type 1 diabetic subjects.
  
  
  METHODS
  Persistence of Tregs was assessed by culturing sorted CD4(+)CD25(hi) natural Tregs with IL-2 and measuring FOXP3 expression over time by flow cytometry for control and type 1 diabetic populations. The effects of IL-2 on FOXP3 induction were assessed 48 h after activation of CD4(+)CD25(-) T-cells with anti-CD3 antibody. Cytokine receptor expression and signaling upon exposure to IL-2, IL-7, and IL-15 were determined by flow cytometry and Western blot analysis.
  
  
  RESULTS
  Maintenance of FOXP3 expression in CD4(+)CD25(+) Tregs of type 1 diabetic subjects was diminished in the presence of IL-2, but not IL-7. Impaired responsiveness was not linked to altered expression of the IL-2R complex. Instead, IL-2R signaling was reduced in Tregs and total CD4(+) T-cells of type 1 diabetic subjects. In some individuals, decreased signal transducer and activator of transcription 5 phosphorylation correlated with significantly higher expression of protein tyrosine phosphatase N2, a negative regulator of IL-2R signaling.
  
  
  CONCLUSIONS
  Aberrant IL-2R signaling in CD4(+) T-cells of type 1 diabetic subjects contributes to decreased persistence of FOXP3 expression that may impact establishment of tolerance. These findings suggest novel targets for treatment of type 1 diabetes within the IL-2R pathway and suggest that an altered IL-2R signaling signature may be a biomarker for type 1 diabetes.
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, Washington, USA.
authors.forename: S Alice
authors.initials: SA
authors.lastname: Long
authors.forename: Karen
authors.initials: K
authors.lastname: Cerosaletti
authors.forename: Paul L
authors.initials: PL
authors.lastname: Bollyky
authors.forename: Megan
authors.initials: M
authors.lastname: Tatum
authors.forename: Heather
authors.initials: H
authors.lastname: Shilling
authors.forename: Sheng
authors.initials: S
authors.lastname: Zhang
authors.forename: Zhong-Yin
authors.initials: ZY
authors.lastname: Zhang
authors.forename: Catherine
authors.initials: C
authors.lastname: Pihoker
authors.forename: Srinath
authors.initials: S
authors.lastname: Sanda
authors.forename: Carla
authors.initials: C
authors.lastname: Greenbaum
authors.forename: Jane H
authors.initials: JH
authors.lastname: Buckner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D015704:CD4 Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D018929:Cell Culture Techniques; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000235:genetics*; D006801:Humans; D007376:Interleukin-2 / Q000276:immunology / Q000494:pharmacology; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology*; D015851:Interleukin-7 / Q000494:pharmacology; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015398:Signal Transduction; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D055815:Young Adult
chemical_list: D015704:CD4 Antigens; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D007376:Interleukin-2; D053645:Interleukin-2 Receptor alpha Subunit; D015851:Interleukin-7