title: Elevated serum level of circulating syndecan-1 (CD138) in active systemic lupus erythematosus.
abstract: OBJECTIVE
  Systemic lupus erythematosus (SLE) is characterized by loss of B cell tolerance and by the presence of polyclonal B cell activation. Syndecan-1 (CD138) is expressed on plasma cells derived from B cells, and is suspected to play a role in SLE. We evaluated the level of soluble CD138 (sCD138) and cell surface expression of CD138 in patients with active SLE, and also examined correlations among the serum levels of BAFF, a proliferation-inducing ligand (APRIL), and CD138 in these patients.
  
  
  METHODS
  Peripheral blood samples were obtained from 22 SLE patients in an active disease state and 14 normal controls. The levels of serum sCD138, sBAFF, and sAPRIL were measured using ELISA, and cell surface CD138 was analyzed by flow cytometry. The levels of CD138 mRNA were analyzed by RT-PCR. Blood samples were obtained longitudinally when the patients were in an inactive disease state.
  
  
  RESULTS
  The levels of circulating CD138, CD138 mRNA in PBMC, and the numbers of CD20(- )CD38(+)CD138(+) plasma cells were increased in patients with active SLE in comparison with normal controls. Furthermore, the serum sCD138 level in SLE patients was found to correlate with the proportion of CD20(- )CD38(+)CD138(+) plasma cells. On the other hand, patients with active SLE showed a reduced level of sCD138, and this was inversely correlated with the serum level of sAPRIL.
  
  
  CONCLUSIONS
  These results suggest that sCD138 may be applicable as a surrogate marker of disease activity, and that syndecan-1/APRIL signaling may be a potential therapeutic target for patients with active SLE.
authors.affiliation: Department of Internal Medicine and Rheumatology, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Minowa
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Amano
authors.forename: Souichiro
authors.initials: S
authors.lastname: Nakano
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Ando
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nakiri
authors.forename: Eri
authors.initials: E
authors.lastname: Amano
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tokano
authors.forename: Shinji
authors.initials: S
authors.lastname: Morimoto
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Takasaki
mesh_terms: D000328:Adult; D053264:B-Cell Activating Factor / Q000097:blood; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000235:genetics / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D012720:Severity of Illness Index; D053668:Syndecan-1 / Q000097:blood* / Q000235:genetics / Q000378:metabolism; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13 / Q000097:blood; D055815:Young Adult
chemical_list: D053264:B-Cell Activating Factor; D012333:RNA, Messenger; D053668:Syndecan-1; C114631:TNFSF13 protein, human; C505719:TNFSF13B protein, human; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13