title: Systemic sclerosis sera affect fibrillin-1 deposition by dermal blood microvascular endothelial cells: therapeutic implications of cyclophosphamide.
abstract: BACKGROUND
  Systemic sclerosis (SSc) is a connective tissue disorder characterized by endothelial cell injury, autoimmunity and fibrosis. The following three fibrillin-1 alterations have been reported in SSc. (1) Fibrillin-1 microfibrils are disorganized in SSc dermis. (2) Fibrillin-1 microfibrils produced by SSc fibroblasts are unstable. (3) Mutations in the FBN1 gene and anti-fibrillin-1 autoantibodies have been reported in SSc. Fibrillin-1 microfibrils, which are abundantly produced by blood and lymphatic microvascular endothelial cells (B-MVECs and Ly-MVECs, respectively), sequester in the extracellular matrix the latent form of the potent profibrotic cytokine transforming growth factor β (TGF-β). In the present study, we evaluated the effects of SSc sera on the deposition of fibrillin-1 and microfibril-associated glycoprotein 1 (MAGP-1) and the expression of focal adhesion molecules by dermal B-MVECs and Ly-MVECs.
  
  
  METHODS
  Dermal B-MVECs and Ly-MVECs were challenged with sera from SSc patients who were treatment-naïve or under cyclophosphamide (CYC) treatment and with sera from healthy controls. Fibrillin-1/MAGP-1 synthesis and deposition and the expression of αvβ₃ integrin/phosphorylated focal adhesion kinase and vinculin/actin were evaluated by immunofluorescence and quantified by morphometric analysis.
  
  
  RESULTS
  Fibrillin-1 and MAGP-1 colocalized in all experimental conditions, forming a honeycomb pattern in B-MVECs and a dense mesh of short segments in Ly-MVECs. In B-MVECs, fibrillin-1/MAGP-1 production and αvβ₃ integrin expression significantly decreased upon challenge with sera from naïve SSc patients compared with healthy controls. Upon challenge of B-MVECs with sera from CYC-treated SSc patients, fibrillin-1/MAGP-1 and αvβ₃ integrin levels were comparable to those of cells treated with healthy sera. Ly-MVECs challenged with SSc sera did not differ from those treated with healthy control sera in the expression of any of the molecules assayed.
  
  
  CONCLUSIONS
  Because of the critical role of fibrillin-1 in sequestering the latent form of TGF-β in the extracellular matrix, its decreased deposition by B-MVECs challenged with SSc sera might contribute to dermal fibrosis. In SSc, CYC treatment might limit fibrosis through the maintenance of physiologic fibrillin-1 synthesis and deposition by B-MVECs.
authors: Marilisa
authors: M
authors: Villano
authors: Annalisa
authors: A
authors: Borghini
authors: Mirko
authors: M
authors: Manetti
authors: Erica
authors: E
authors: Gabbrielli
authors: Antonella
authors: A
authors: Rossi
authors: Piersante
authors: P
authors: Sestini
authors: Anna
authors: A
authors: Milia
authors: Francesca
authors: F
authors: Nacci
authors: Serena
authors: S
authors: Guiducci
authors: Marco
authors: M
authors: Matucci-Cerinic
authors: Lidia
authors: L
authors: Ibba-Manneschi
authors: Elisabetta
authors: E
authors: Weber
mesh_terms: D002478:Cells, Cultured; D003285:Contractile Proteins; D003520:Cyclophosphamide / Q000627:therapeutic use; D042783:Endothelial Cells / Q000378:metabolism*; D016326:Extracellular Matrix Proteins; D005260:Female; D000071838:Fibrillin-1; D000071837:Fibrillins; D005455:Fluorescent Antibody Technique; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism*; D008875:Middle Aged; D000072260:RNA Splicing Factors; D012595:Scleroderma, Systemic / Q000097:blood* / Q000188:drug therapy; D012867:Skin / Q000098:blood supply; D054392:Adipokines
chemical_list: D003285:Contractile Proteins; D003520:Cyclophosphamide; D016326:Extracellular Matrix Proteins; D000071838:Fibrillin-1; D000071837:Fibrillins; D007166:Immunosuppressive Agents; D008840:Microfilament Proteins; D000072260:RNA Splicing Factors; C000605722:FBN1 protein, human; D054392:Adipokines; C016598:microfibrillar protein
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