title: B cell depletion therapy upregulates Dkk-1 skin expression in patients with systemic sclerosis: association with enhanced resolution of skin fibrosis.
abstract: Rituximab (RTX) may favorably affect skin and lung fibrosis in patients with systemic sclerosis (SSc); however, the underlying molecular mechanisms remain unknown. We aimed to explore the hypothesis that RTX may mediate its antifibrotic effects by regulating the expression of Dickkopf-1 (Dkk-1), an inhibitor of the Wnt pathway.
  
  
  
  Fourteen patients with SSc and five healthy subjects were recruited. Dkk-1 expression was immunohistochemically assessed in skin biopsies obtained from 11 patients with SSc (8 treated with RTX and 3 with standard treatment), whereas DKK1 gene expression was assessed in 3 patients prior to and following RTX administration.
  
  
  
  In baseline biopsies obtained from all patients with SSc but not in healthy subjects, Dkk-1 was undetectable in skin fibroblasts. Following RTX treatment, four out of eight patients had obvious upregulation of Dkk-1 skin expression. Similarly, RTX treatment correlated with a significant 4.8-fold upregulation of DKK1 gene expression (p = 0.030). In contrast, TGFβ expression in the upper dermis was significantly attenuated following treatment. Moreover, this decreased expression of TGFβ in the skin was significantly more pronounced in the subgroup of patients with Dkk-1 upregulation. In this subgroup TGFβ was downregulated by 50.88 % in contrast to only 15.98 % in patients who did not have Dkk-1 upregulation (p = 0.022).
  
  
  
  This is the first study demonstrating a link between B cell depletion and skin Dkk-1 upregulation in patients with SSc. RTX-mediated B cell depletion may mechanistically function via the recently established TGFβ-Dkk-1 axis in improving skin fibrosis.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Patras University Hospital, University of Patras Medical School, Rion, Patras, 26504, Greece. jimdaoussis@hotmail.com.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Daoussis
authors.affiliation: Department of Patholology, Patras University Hospital, University of Patras Medical School, Patras, Greece.
authors.forename: Athanassios
authors.initials: A
authors.lastname: Tsamandas
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Patras University Hospital, University of Patras Medical School, Rion, Patras, 26504, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Antonopoulos
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Patras University Hospital, University of Patras Medical School, Rion, Patras, 26504, Greece.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Filippopoulou
authors.affiliation: Department of Anatomy-Histology-Embryology, Laboratory of Bone and Soft Tissue Studies, University of Patras Medical School, Patras, Greece.
authors.forename: Dionysios J
authors.initials: DJ
authors.lastname: Papachristou
authors.affiliation: Department of Anatomy-Histology-Embryology, Laboratory of Bone and Soft Tissue Studies, University of Patras Medical School, Patras, Greece.
authors.forename: Nicholaos I
authors.initials: NI
authors.lastname: Papachristou
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Patras University Hospital, University of Patras Medical School, Rion, Patras, 26504, Greece.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Andonopoulos
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Patras University Hospital, University of Patras Medical School, Rion, Patras, 26504, Greece.
authors.forename: Stamatis-Nick
authors.initials: SN
authors.lastname: Liossis
mesh_terms: D000328:Adult; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D005355:Fibrosis / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007118:Immunoassay; D007150:Immunohistochemistry; D007155:Immunologic Factors / Q000627:therapeutic use*; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D008212:Lymphocyte Depletion; D008297:Male; D008875:Middle Aged; D000069283:Rituximab / Q000627:therapeutic use*; D012595:Scleroderma, Systemic / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D012867:Skin / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016212:Transforming Growth Factor beta; D015854:Up-Regulation
chemical_list: C501126:DKK1 protein, human; D007155:Immunologic Factors; D036341:Intercellular Signaling Peptides and Proteins; D016212:Transforming Growth Factor beta; D000069283:Rituximab
keywords: B cell depletion; Dickkopf-1; Dkk-1; Fibrosis; Rituximab; Scleroderma; Skin; Systemic sclerosis; TGFβ