Expression of FLICE-inhibitory protein in synovial tissue and its association with synovial inflammation in juvenile idiopathic arthritis.
OBJECTIVE
To examine the expression of FLICE-inhibitory protein (FLIP) in juvenile idiopathic arthritis (JIA) and analyze its correlation with synovial inflammation.


METHODS
The expression of FLIP was assessed in 11 JIA and 3 normal synovial tissue samples by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. The cell types expressing FLIP were further characterized, and the correlation of FLIP expression with the degree of synovial inflammation, as well as the activity of caspase 8 was then analyzed.


RESULTS
RT-PCR revealed the expression of FLIP mRNA in all 11 JIA samples, but not in 3 normal synovial tissues. In JIA, FLIP expression could be found in both the lining and sublining layers, mainly in the macrophage-like cells. Moreover, the expression of FLIP in JIA synovial tissues was positively correlated with the degree of synovial inflammation (r = 0.563, P < 0.05).


CONCLUSIONS
The expression of antiapoptotic FLIP in JIA synovial tissue and its correlation to accumulation of inflammatory cells in synovial tissue suggests that FLIP potentially extends the lifespan of synovial cells and thus contributes to the progression of joint destruction.
Wu
Feng-Xia
FX
Institute of Rheumatology and Immunology, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, China.
Wu
Li-Jun
LJ
Luo
Xiong-Yan
XY
Yang
Ming-Hui
MH
Tang
Zhong
Z
Xie
Chuan-Mei
CM
Zhou
Jing-Guo
JG
Guan
Jian-Long
JL
Yuan
Guo-Hua
GH
D000293:Adolescent; D001171:Arthritis, Juvenile / Q000378:metabolism / Q000473:pathology; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism*; D053181:Caspase 8 / Q000378:metabolism; D002648:Child; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D008297:Male; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D013583:Synovial Membrane / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D020033:Protein Isoforms; D053181:Caspase 8