Osteopontin might be involved in bone remodelling rather than in inflammation in ankylosing spondylitis.
OBJECTIVE
To determine whether osteopontin (OPN) is increased in patients with AS and to investigate its relationship to inflammatory disease activity and bone remodelling process.


METHODS
This cross-sectional study included 30 patients with AS and 23 age- and sex-matched healthy controls. We assessed clinical characteristics and laboratory parameters including the ESR, CRP, lipid profiles, the Bath AS disease activity index (BASDAI) and the Bath AS radiographic index (BASRI). To evaluate bone metabolism, we tested ALP, OCN and C-telopeptide of type I collagen (CTX-I). Plasma levels of OPN, TNF-alpha and IL-6 were measured by ELISA, and mRNA expression in peripheral blood mononuclear cells (PBMCs) was performed by RT-PCR. Changes in OPN level were also evaluated in eight patients after the treatment with a TNF-alpha blocker.


RESULTS
Patients with AS had significantly higher plasma OPN, TNF-alpha and IL-6 levels and more mRNA expression than healthy controls. Plasma OPN levels were correlated with serum ALP, OCN and CTX-I levels, but not with ESR, CRP, lipid profiles, BASDAI or BASRI. Treatment with a TNF-alpha blocker did not alter OPN levels, although it reduced the disease activity.


CONCLUSIONS
Patients with AS had higher levels of OPN compared with controls. The plasma OPN level was correlated with serum ALP, OCN and CTX-I levels, but not with disease activity in AS. OPN might be involved in bone remodelling rather than in inflammation in AS.
Department of Internal Medicine, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-ku, Seoul 120-752, South Korea. sookonlee@yuhs.ac
S T
ST
Choi
J H
JH
Kim
E-J
EJ
Kang
S-W
SW
Lee
M-C
MC
Park
Y-B
YB
Park
S-K
SK
Lee
D000328:Adult; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000627:therapeutic use; D015415:Biomarkers / Q000097:blood; D016723:Bone Remodeling; D003430:Cross-Sectional Studies; D016207:Cytokines / Q000097:blood / Q000235:genetics; D000068800:Etanercept; D005260:Female; D015870:Gene Expression; D006801:Humans; D007074:Immunoglobulin G / Q000627:therapeutic use; D000069285:Infliximab; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D053495:Osteopontin / Q000097:blood / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D018124:Receptors, Tumor Necrosis Factor / Q000627:therapeutic use; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000097:blood / Q000188:drug therapy / Q000503:physiopathology*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000097:blood; D055815:Young Adult
D000911:Antibodies, Monoclonal; D018501:Antirheumatic Agents; D015415:Biomarkers; D016207:Cytokines; D007074:Immunoglobulin G; D015850:Interleukin-6; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D053495:Osteopontin; D000069285:Infliximab; D000068800:Etanercept