title: Expression of the apoptosis accelerator Bax in rheumatoid arthritis synovium.
abstract: OBJECTIVE
  The aim of this study was to analyze the expression of apoptosis-related molecules in rheumatoid arthritis (RA) synovium, with special emphasis on the apoptosis accelerator Bax.
  
  
  METHODS
  Immunohistochemical analysis of Bax, Bcl-2, and Bcl-x(L) was performed in tissue specimens of patients with RA and compared to normal synovial tissue. Expression of Bax was additionally determined by double labeling with CD68, p53, and Ki-67 (clone MIB-1). Apoptotic cells were further identified by the terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) method.
  
  
  RESULTS
  In RA, expression of Bax was higher than in healthy controls and occurred in CD68-positive and -negative synoviocytes. Strong Bax staining was also found in chondrocytes at sites of cartilage degradation. Bax-positive synoviocytes could be detected with p53 and also with Ki-67. Bax and Bcl-x(L) were markedly colocalized in synovium. The TUNEL method revealed only few positive synoviocytes.
  
  
  CONCLUSIONS
  The marked colocalization of Bax and antiapoptotic Bcl-x(L) as well as the low frequency of TUNEL-positive cells in RA synovium suggest that Bax activity is not sufficient to decrease synovial hyperplasia in RA. Apoptotic mechanisms in RA chondrocytes might also be important for the pathogenesis of joint damage.
authors.affiliation: Institute of Pathology, University of Mainz, 55101 Mainz, Germany.
authors.forename: Insa
authors.initials: I
authors.lastname: Hilbers
authors.forename: Torsten
authors.initials: T
authors.lastname: Hansen
authors.forename: Peter K
authors.initials: PK
authors.lastname: Petrow
authors.forename: Andreas
authors.initials: A
authors.lastname: Gaumann
authors.forename: Rolf
authors.initials: R
authors.lastname: Bräuer
authors.forename: Günther
authors.initials: G
authors.lastname: Salzmann
authors.forename: Renate E
authors.initials: RE
authors.lastname: Gay
authors.forename: Hartwig
authors.initials: H
authors.lastname: Kosmehl
authors.forename: C James
authors.initials: CJ
authors.lastname: Kirkpatrick
authors.forename: Steffen
authors.initials: S
authors.lastname: Gay
authors.forename: Jörg
authors.initials: J
authors.lastname: Kriegsmann
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D005260:Female; D019254:Genes, bcl-2 / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000096:biosynthesis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000276:immunology; D013583:Synovial Membrane / Q000737:chemistry / Q000378:metabolism*; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
chemical_list: C494826:BAX protein, human; C494811:BCL2L1 protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein