title: Breg Cells Are Numerically Decreased and Functionally Impaired in Patients With Systemic Sclerosis.
abstract: OBJECTIVE
  Breg cells, a regulatory cell subset that produces interleukin-10 (IL-10), play a significant role in suppressing autoimmune responses and preventing autoimmunity. This study was undertaken to examine the number and function of Breg cells in patients with systemic sclerosis (SSc), a disease with many autoantibodies.
  
  
  METHODS
  Forty-five patients with SSc (12 with early SSc, 33 with established disease including 16 with SSc-associated pulmonary fibrosis [PF]), 12 healthy control subjects, and 10 patients with rheumatoid arthritis (RA)-associated PF were studied. The phenotypes of immature/transitional Breg cells (CD19+CD24(high) CD38(high) ) and memory Breg cells (CD19+CD27+CD24(high) ) were evaluated by flow cytometry. The function of Breg cells was assessed by measuring the production of IL-10 after B cell activation. In addition, activation of p38 MAPK and STAT-3 was measured following stimulation of the cells with B cell receptor (BCR) and Toll-like receptor 9 (TLR-9).
  
  
  RESULTS
  Percentages of memory Breg cells were decreased in patients with early SSc (mean ± SEM 1.85 ± 0.38%), those with established SSc (1.6 ± 0.88%), those with SSc-associated PF (1.52 ± 0.17%), and those with RA-associated PF (1.58 ± 0.26%), compared to healthy controls (6.3 ± 0.49%; each P < 0.001). Percentages of transitional Breg cells were also decreased. Expression of IL-10 by Breg cells after stimulation with TLR-9 was impaired in patients with SSc, particularly those with SSc-associated PF. Activation of STAT-3 and p38 MAPK was impaired in naive and memory B cells from patients with SSc after stimulation with BCR and TLR-9. Expression of the stimulatory CD19 receptor was increased in B cells and also increased, to a lesser extent, in Breg cells from patients with SSc compared to healthy controls. Percentages of memory B cells were decreased in patients with SSc, particularly in those with SSc-associated PF.
  
  
  CONCLUSIONS
  This is the first study to demonstrate that Breg cells are phenotypically and functionally impaired in patients with SSc. Furthermore, in SSc, B cells exhibit impaired p38 MAPK and STAT-3 activation upon stimulation with BCR and TLR-9. The findings of decreased numbers of Breg cells along with increased expression of CD19 support the idea of B cell autoaggression acting as an immunopathogenic mediator in SSc.
authors.affiliation: University of Thessaly, Larissa, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Mavropoulos
authors.affiliation: University of Thessaly, Larissa, Greece.
authors.forename: Theodora
authors.initials: T
authors.lastname: Simopoulou
authors.affiliation: University of Thessaly, Larissa, Greece.
authors.forename: Areti
authors.initials: A
authors.lastname: Varna
authors.affiliation: University of Thessaly, Larissa, Greece.
authors.forename: Christos
authors.initials: C
authors.lastname: Liaskos
authors.affiliation: University of Thessaly, Larissa, Greece.
authors.forename: Christina G
authors.initials: CG
authors.lastname: Katsiari
authors.affiliation: University of Thessaly, Larissa, Greece.
authors.forename: Dimitrios P
authors.initials: DP
authors.lastname: Bogdanos
authors.affiliation: University of Thessaly, Larissa, Greece.
authors.forename: Lazaros I
authors.initials: LI
authors.lastname: Sakkas
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000276:immunology; D000328:Adult; D000368:Aged; D018941:Antigens, CD19 / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000276:immunology; D060151:B-Lymphocytes, Regulatory / Q000276:immunology*; D051927:CD24 Antigen / Q000276:immunology; D016022:Case-Control Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016753:Interleukin-10 / Q000276:immunology; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000209:etiology / Q000276:immunology*; D011947:Receptors, Antigen, B-Cell; D050796:STAT3 Transcription Factor / Q000276:immunology; D012595:Scleroderma, Systemic / Q000150:complications / Q000276:immunology*; D012720:Severity of Illness Index; D051217:Toll-Like Receptor 9; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000276:immunology; D048051:p38 Mitogen-Activated Protein Kinases / Q000276:immunology
chemical_list: D018941:Antigens, CD19; D051927:CD24 Antigen; C508609:IL10 protein, human; D011947:Receptors, Antigen, B-Cell; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D051217:Toll-Like Receptor 9; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D016753:Interleukin-10; D048051:p38 Mitogen-Activated Protein Kinases; D051997:ADP-ribosyl Cyclase 1