Asporin and transforming growth factor-beta gene expression in osteoblasts from subchondral bone and osteophytes in osteoarthritis.
BACKGROUND
To clarify the significance of subchondral bone and osteophytes in the pathology of osteoarthritis (OA), we investigated the expression of asporin (ASPN), transforming growth factor-beta1 (TGF-beta1), TGF-beta2, TGF-beta3, and runt-related transcription factor-2 (Runx2) genes involved in bone metabolism.


METHODS
Osteoblasts were isolated from 19 patients diagnosed with knee OA and from 4 patients diagnosed with femoral neck fracture. Osteoblast expression of mRNA encoding ASPN, TGF-beta1, TGF-beta2, TGF-beta3, and Runx2 was analyzed using real-time RT-PCR.


RESULTS
Expression of ASPN, TGF-beta1, and TGF-beta3 mRNA in the subchondral bone and osteophytes of OA patients increased compared with that of non-OA patients. The ratio of ASPN to TGF-beta1 mRNA in patients with severe cartilage damage was higher than that in patients with mild cartilage damage.


CONCLUSIONS
The increased ratio of ASPN mRNA to TGF-beta1 mRNA in patients with severe relative to mild cartilage damage indicates that increased ASPN mRNA expression was significantly associated with the severity of cartilage degeneration. This finding suggests that ASPN may regulate TGF-beta1-mediated factors in the development of OA, which may provide clues as to the underlying pathology of OA.
Sakao
Kei
K
Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
Takahashi
Kenji A
KA
Arai
Yuji
Y
Saito
Masazumi
M
Honjyo
Kuniaki
K
Hiraoka
Nobuyuki
N
Kishida
Tsunao
T
Mazda
Osam
O
Imanishi
Jiro
J
Kubo
Toshikazu
T
D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005663:Furans; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D020370:Osteoarthritis, Knee / Q000235:genetics* / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism*; D054850:Osteophyte / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D012720:Severity of Illness Index; D013876:Thiophenes; D053773:Transforming Growth Factor beta1 / Q000235:genetics* / Q000378:metabolism; D053781:Transforming Growth Factor beta2 / Q000235:genetics / Q000378:metabolism; D053782:Transforming Growth Factor beta3 / Q000235:genetics / Q000378:metabolism
C516387:3,4-bis-(2,4,5-trimethyl-thiophen-3-yl)furan-2,5-dione; C439889:ASPN protein, human; D016326:Extracellular Matrix Proteins; D005663:Furans; D012333:RNA, Messenger; D013876:Thiophenes; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2; D053782:Transforming Growth Factor beta3