Background/Purpose:

In recent years, there is considerable interest regarding prediction and pathogenesis of syndesmophyte formation. Thus, several studies were conducted in order to identify the factors affecting this process. Today, biomarkers have become a very important field of research in spondyloarthropathy. In this regard, various biomarkers have been used to understand the underlying factors responsible from syndesmophyte formation. However, available data on this subject is still limited and additional information is required. In this study, we aimed to determine the levels of different biomarkers and analyze their relationships with syndesmophytes in ankylosing spondylitis (AS).

Methods:

Lateral plain radiographs of the cervical and lumbar spine were used for scoring syndesmophytes. The anterior sites of the lower and upper portion of each vertebra were randomly and blindly scored by 2 experienced rheumatologists. Any presence of syndesmophytes or bridging syndesmophytes was categorized as positive. The following ELISA kits were studied: hsCRP, IL-6, dickkopf-1 (DKK-1), receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), bone morphogenetic protein-7 (BMP-7), and fetuin A.

Results:

There were 86 patients (31 non-syndesmophyte, 65% male [M], 41.5±8.2 years; 55 with syndesmophyte, 71% M, 43.9±9.7 years) in the study group. Disease duration, age and sex distributions, BASFI and BASDAI were similar between the non-syndesmophyte and syndesmophyte groups (P > 0.05). However, BASMI values and current or past smoking history percentages were significantly different between the syndesmophyte negative and positive patients (P < 0.05, 3.18±1.5 vs. 4.53±1.9, and 86% vs. 58% respectively). Evaluation of soluble biomarkers revealed that the levels of OPG, sRANKL, DKK-1, sclerostin, and BMP-7 were comparable between AS patients with and without syndesmophytes (P > 0.05, table 2). However, fetuin A was significantly higher in the in the patients with syndesmophytes compared to non-syndesmophyte group (P < 0.05, Table 1). Correlation analysis showed that the presence of syndesmophytes were significantly and positively correlated with BASMI, current or past smoking history, and fetuin-A (P < 0.05, r= 0.3, 0.3 and 0.2 respectively). Regression analysis showed that fetuin A was the most important predictor of syndesmophytes (odds ratio, and 95% confidence interval = 31.2, and 0.94-1039).

Conclusion:

We suggest that fetuin A may be used as a novel biomarker to predict new bone formation in patients with AS.

Table 1: Laboratory characteristics of the study group

	AS patients		P value
	Syndesmophyte (+), n= 55	Syndesmophyte (-), n= 31
DKK-1 (pg/ml)	1967±1318	1718±1054	0.37
Sclerostin (pg/ml)	143±117	130±116	0.64
sRANKL (pmol/l)	110±95	130±74	0.32
OPG (pg/ml)	1916±593	1905±493	0.93
BMP-7 (pg/ml)	7.8±14	8.4±17	0.87
Fetuin-A (mg/ml)	1.15±0.17	1.08±0.12	0.04
hsCRP (mg/ml)	9.9±6.4	9.2±7.1	0.62
IL-6 (ng/ml)	0.003±0.001	0.003±0.001	0.86

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/fetuin-a-a-new-biomarker-related-with-syndesmophytes-in-patients-with-ankylosing-spondylitis/