Expression of granzyme B in human articular chondrocytes.
OBJECTIVE
To investigate the expression of granzyme B (GrB) in normal and rheumatoid arthritis (RA) articular cartilage, and to analyze the relationship between the expression of GrB and apoptotic chondrocytes in RA cartilage.


METHODS
Normal cartilage samples were obtained from 9 resected joints and RA cartilage samples were obtained from 12 patients with RA during joint replacement surgery. Cartilage sections were analyzed by immunohistochemistry for the presence of GrB, and the mRNA expression of GrB in chondrocytes was analyzed by in situ hybridization and nonquantitative and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). The expression of perforin (PFN) was also assessed. Apoptotic chondrocytes were detected using TUNEL staining and their morphology was examined using electron microscopy.


RESULTS
The immunohistochemical analyses revealed GrB and PFN expression in normal chondrocytes and a larger number of GrB and PFN-positive chondrocytes in RA cartilage. In situ hybridization and RT-PCR confirmed the expression of GrB and PFN mRNA, and semiquantitative RT-PCR showed elevated concentrations of GrB and PFN expression in RA chondrocytes. The distribution of GrB and PFN-positive cells in the RA cartilage samples was similar to that of apoptotic cells.


CONCLUSIONS
GrB and PFN expression is present in normal human articular chondrocytes and elevated in RA chondrocytes. The targets and precise functions of GrB expressed in chondrocytes remain to be determined, but GrB may be involved in the remodeling mechanism of matrix macromolecules and the endogenous degradation of RA cartilage.
Horiuchi
Kiwamu
K
Institute of Rheumatology, Tokyo Women's Medical University, Tokyo, Japan. k-hori@muf.biglobe.ne.jp
Saito
Seiji
S
Sasaki
Ryohei
R
Tomatsu
Taisuke
T
Toyama
Yoshiaki
Y
D000906:Antibodies; D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism*; D019902:Chondrocytes / Q000201:enzymology* / Q000648:ultrastructure; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D053804:Granzymes; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008854:Microscopy, Electron; D008875:Middle Aged; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger / Q000032:analysis; D012697:Serine Endopeptidases / Q000235:genetics* / Q000276:immunology / Q000378:metabolism
D000906:Antibodies; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger; D054353:Perforin; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases