title: Low frequency of CD4+CD25+ Treg in SLE patients: a heritable trait associated with CTLA4 and TGFbeta gene variants.
abstract: BACKGROUND
  CD4+CD25+ regulatory T cells play an essential role in maintaining immune homeostasis and preventing autoimmunity. Therefore, defects in Treg development, maintenance or function have been associated with several human autoimmune diseases including Systemic Lupus Erythematosus (SLE), a systemic autoimmune disease characterized by loss of tolerance to nuclear components and significantly more frequent in females.
  
  
  RESULTS
  To investigate the involvement of Treg in SLE pathogenesis, we determined the frequency of CD4+CD25+CD45RO+ T cells, which encompass the majority of Treg activity, in the PBMC of 148 SLE patients (76 patients were part of 54 families), 166 relatives and 117 controls. SLE patients and their relatives were recruited in several Portuguese hospitals and through the Portuguese Lupus Association. Control individuals were blood donors recruited from several regional blood donor centers. Treg frequency was significantly lower in SLE patients than healthy controls (z = -6.161, P < 0.00001) and intermediate in the relatives' group. Remarkably, this T cell subset was also lower in females, most strikingly in the control population (z = 4.121, P < 0.001). We further ascertained that the decreased frequency of Treg in SLE patients resulted from the specific reduction of bona fide FOXP3+CD4+CD25+ Treg. Treg frequency was negatively correlated with SLE activity index (SLEDAI) and titers of serum anti-dsDNA antibodies. Both Treg frequency and disease activity were modulated by IVIg treatment in a documented SLE case. The segregation of Treg frequency within the SLE families was indicative of a genetic trait. Candidate gene analysis revealed that specific variants of CTLA4 and TGFbeta were associated with the decreased frequency of Treg in PBMC, while FOXP3 gene variants were associated with affection status, but not with Treg frequency.
  
  
  CONCLUSIONS
  SLE patients have impaired Treg production or maintenance, a trait strongly associated with SLE disease activity and autoantibody titers, and possibly resulting from the inability to convert FOXP3+CD25- into FOXP3+CD25+ T cells. Treg frequency is highly heritable within SLE families, with specific variants of the CTLA4 and TGFbeta genes contributing to this trait, while FOXP3 contributes to SLE through mechanisms not involving a modulation of Treg frequency. These findings establish that the genetic components in SLE pathogenesis include genes related to Treg generation or maintenance.
authors.affiliation: Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6 2780-156 Oeiras, Portugal. mbarreto@igc.gulbenkian.pt
authors.forename: Marta
authors.initials: M
authors.lastname: Barreto
authors.forename: Ricardo C
authors.initials: RC
authors.lastname: Ferreira
authors.forename: Lara
authors.initials: L
authors.lastname: Lourenço
authors.forename: Maria F
authors.initials: MF
authors.lastname: Moraes-Fontes
authors.forename: Eugénia
authors.initials: E
authors.lastname: Santos
authors.forename: Miguel
authors.initials: M
authors.lastname: Alves
authors.forename: Cláudia
authors.initials: C
authors.lastname: Carvalho
authors.forename: Berta
authors.initials: B
authors.lastname: Martins
authors.forename: Rita
authors.initials: R
authors.lastname: Andreia
authors.forename: João F
authors.initials: JF
authors.lastname: Viana
authors.forename: Carlos
authors.initials: C
authors.lastname: Vasconcelos
authors.forename: Luísa
authors.initials: L
authors.lastname: Mota-Vieira
authors.forename: Carlos
authors.initials: C
authors.lastname: Ferreira
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Demengeot
authors.forename: Astrid M
authors.initials: AM
authors.lastname: Vicente
mesh_terms: D000367:Age Factors; D000974:Antibodies, Antinuclear / Q000097:blood; D015703:Antigens, CD / Q000235:genetics* / Q000276:immunology; D015704:CD4 Antigens; D060908:CTLA-4 Antigen; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000276:immunology; D005838:Genotype; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics / Q000276:immunology; D053645:Interleukin-2 Receptor alpha Subunit / Q000235:genetics* / Q000276:immunology; D017493:Leukocyte Common Antigens; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000235:genetics* / Q000276:immunology / Q000503:physiopathology; D008297:Male; D011110:Polymorphism, Genetic; D019655:Quantitative Trait, Heritable; D012720:Severity of Illness Index; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000276:immunology
chemical_list: D000974:Antibodies, Antinuclear; D015703:Antigens, CD; D015704:CD4 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D007376:Interleukin-2; D053645:Interleukin-2 Receptor alpha Subunit; D016212:Transforming Growth Factor beta; D017493:Leukocyte Common Antigens