title: Gene expression signature of tolerance and lymphocyte subsets in stable renal transplants: results of a cross-sectional study.
abstract: BACKGROUND
  In kidney transplants operational tolerance has been associated with up-regulation of B cell differentiation genes and an increased number of total, naive and transitional peripheral B cells. The aim is to evaluate tolerance biomarkers in different cohorts of stable renal transplants under immunosuppression.
  
  
  METHODS
  This is a cross-sectional study conducted in renal transplants. We evaluate genetic tolerance signature and lymphocyte subsets in stable transplants treated with calcineurin inhibitors (CNI) at 1 (n=15), 5 (n=14) and 10 (n=16) years, and azathioprine-treated transplants followed 30 years (n=8). Healthy volunteers (n=10) and patients with chronic rejection (n=15) served as controls.
  
  
  RESULTS
  We confirm that peripheral expression of IGKV1D-13 and IGKV4-1 genes by RT-PCR distinguish tolerant (n=10) from stable transplants (n=10) provided by the International Tolerance Network. Tolerance signature was defined as the lowest expression for both genes in tolerant patients. In CNI-treated patients, genetic signature of tolerance and B cells showed a time-dependent increase not observed in azathioprine-treated patients (p<0.01). Genetic tolerance signature was observed in 0% at 1, 7% at 5 and 25% at 10-years while it was not observed in azathioprine-treated and chronic rejection patients. Fifteen out of 16 CNI-treated transplants at 10 years were revaluated 3 months apart. Nine did not show the tolerance signature in any determination, 4 in one and 2 in both determinations. Genetic signature of tolerance was associated with an increase of total, naive and transitional B cells (p<0.05).
  
  
  CONCLUSIONS
  IGKV1D-13 and IGKV4-1 gene expression and its linked B cell populations increase during follow up in CNI-treated patients. At 10 years, 2 out of 15 CNI treated patients consistently express biomarkers associated with true tolerance. In azathioprine-treated patients these biomarkers were down-regulated.
authors.affiliation: Nephrology Department, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain. Electronic address: fjmoreso@vhebron.net.
authors.forename: Francesc
authors.initials: F
authors.lastname: Moreso
authors.affiliation: Nephrology Department, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Irina B
authors.initials: IB
authors.lastname: Torres
authors.affiliation: Immunology Department, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Spain.
authors.forename: Monica
authors.initials: M
authors.lastname: Martínez-Gallo
authors.affiliation: Pangaea Biotech S.L., Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Benlloch
authors.affiliation: Nephrology Department, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Carme
authors.initials: C
authors.lastname: Cantarell
authors.affiliation: Nephrology Department, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Manel
authors.initials: M
authors.lastname: Perelló
authors.affiliation: Pangaea Biotech S.L., Spain.
authors.forename: José
authors.initials: J
authors.lastname: Jimeno
authors.affiliation: Immunology Department, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pujol-Borrell
authors.affiliation: Nephrology Department, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Seron
mesh_terms: D001379:Azathioprine / Q000627:therapeutic use; D016175:B-Lymphocyte Subsets / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D065095:Calcineurin Inhibitors / Q000627:therapeutic use; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects / Q000235:genetics* / Q000276:immunology*; D016867:Immunocompromised Host / Q000235:genetics* / Q000276:immunology; D007145:Immunoglobulin kappa-Chains / Q000235:genetics; D016130:Immunophenotyping; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D059467:Transcriptome
chemical_list: D065095:Calcineurin Inhibitors; D007145:Immunoglobulin kappa-Chains; D007166:Immunosuppressive Agents; D001379:Azathioprine
keywords: B cells; Chronic rejection; Immunosuppression; Lymphocyte subpopulations; Operational tolerance; Renal transplantation