title: DNA hypermethylation of the forkhead box protein 3 (FOXP3) promoter in CD4+ T cells of patients with systemic sclerosis.
abstract: BACKGROUND
  Systemic sclerosis (SSc) is a complex autoimmune disease that involves dysregulation of immune homeostasis. The failure of impaired regulatory T cells (Tregs) to maintain immune homeostasis plays a major role in the development of SSc. Transcriptional silencing of the forkhead box protein 3 gene (FOXP3) via hypermethylation of regulatory regions has been identified as a hallmark of committed Tregs and several autoimmune disorders.
  
  
  OBJECTIVE
  To investigate whether aberrant expression and methylation of FOXP3 occurs in CD4+ T cells of patients with SSc and their roles in the pathogenesis of SSc.
  
  
  METHODS
  FOXP3 expression in CD4+ T cells was measured by real-time quantitative reverse-itranscriptase polymerase chain reaction and western blot. Bisulfite sequencing was performed to determine the methylation status of the FOXP3 proximal promoter sequence. The percentage of Treg cells was estimated by flow cytometry.
  
  
  RESULTS
  Decreased FOXP3 expression was observed in CD4+ T cells from patients with SSc. The methylation levels of the FOXP3 regulatory sequences were elevated and inversely correlated with FOXP3 mRNA expression in patients with SSc. The number of Tregs was significantly reduced in patients with SSc. Treatment of SSc CD4+ T cells with a DNA methylation inhibitor, 5-azacytidine, reduced the mean methylation levels, and enhanced FOXP3 expression and Treg generation. The promoter methylation status and expression level of FOXP3 are significantly associated with disease activity.
  
  
  CONCLUSIONS
  The contribution of the hypermethylation of the FOXP3 promoter to decreased FOXP3 expression and the subsequent quantitative defects of Tregs may mediate the immune dysfunction in SSc.
authors.affiliation: Department of Dermatology, Second Xiangya Hospital, Central South University, 139 Ren-Min Road, Changsha, 410011, China.
authors.forename: Y Y
authors.initials: YY
authors.lastname: Wang
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: X H
authors.initials: XH
authors.lastname: Sun
authors.forename: R Z
authors.initials: RZ
authors.lastname: Liu
authors.forename: Y
authors.initials: Y
authors.lastname: Shu
authors.forename: T
authors.initials: T
authors.lastname: Kanekura
authors.forename: J H
authors.initials: JH
authors.lastname: Huang
authors.forename: Y P
authors.initials: YP
authors.lastname: Li
authors.forename: J C
authors.initials: JC
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Zhao
authors.forename: Q J
authors.initials: QJ
authors.lastname: Lu
authors.forename: R
authors.initials: R
authors.lastname: Xiao
mesh_terms: D000328:Adult; D000963:Antimetabolites / Q000494:pharmacology; D001374:Azacitidine / Q000494:pharmacology; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D019175:DNA Methylation / Q000502:physiology*; D015536:Down-Regulation; D005260:Female; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D006801:Humans; D008297:Male; D012595:Scleroderma, Systemic / Q000276:immunology / Q000378:metabolism*; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000378:metabolism
chemical_list: D000963:Antimetabolites; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D001374:Azacitidine