Cross-Sectional Evaluation of YKL-40 Serum Concentrations in Patients with Systemic Sclerosis. Relationship with Clinical and Serological Aspects of Disease

GIOVANNI LA MONTAGNA, SALVATORE D'ANGELO, and GABRIELE VALENTINI

ABSTRACT.

Objective. To investigate the behavior of serum YKL-40 in a cohort of patients with systemic sclerosis (SSc).

Methods. Forty SSc patients (35 women, 5 men) were investigated for serum YKL-40, soluble interleukin 2 receptor alpha (sIL-2Ra; by ELISA), von Willebrand factor (vWF; ELISA), and aminoterminal propeptide of type III procollagen (PIIINP; radioimmunoassay) concentrations. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were evaluated. Skin and organ system involvement were scored according to the Medsger organ/system severity scale.

Results. Serum YKL-40 in SSc patients (mean 132.9 ng/ml; median 75.5, 95% CI 87.8–175) was significantly higher than in controls (mean 66.6 ng/ml; median 52, 95% CI 54.6–78.6). Fourteen patients had levels > 135 ng/ml (cutoff value) with a mean of 264.7 ± 160 ng/ml. Serum YKL-40 values were found to be more frequently increased in patients with arthralgias/arthritis (10/18 cases) than in patients without such features (4/22) (p = 0.021). Significant differences were found comparing serum YKL-40 concentrations in the patients with or without joint involvement (median 138 vs 57.5 ng/ml, respectively; p = 0.007). Serum YKL-40 levels correlated with the joint involvement severity score (p = 0.018) and sIL-2Ra levels (p < 0.001). No differences were found with any therapeutic regimen.

Conclusion. This preliminary study shows that YKL-40 serum levels are increased in SSc and that they are correlated with sIL-2Ra and joint involvement, suggesting a relationship with cartilage and/or fibroblast activity. (J Rheumatol 2003;30:2147-51)

Key Indexing Terms:

YKL-40 SERUM LEVELS
SOLUBLE INTERLEUKIN 2 RECEPTOR
JOINT INVOLVEMENT
SYSTEMIC SCLEROSIS

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From the Dipartimento Medico-Chirurgico di Internistica Clinica e Sperimentale F. Magrassi e A. Lanzara, Unità Operativa di Reumatologia, Seconda Università di Napoli, Napoli, Italy.

G. La Montagna, MD, Assistant Professor of Rheumatology; S. D'Angelo, MD, Fellow in Rheumatology; G. Valentini, MD, Professor of Rheumatology and Chief of Rheumatology Unit.

Address reprint requests to Dr. G. La Montagna, Unità Operativa di Reumatologia, Seconda Università di Napoli, Policlinico Via S. Pansini, 5-80131 Napoli, Italy. E-mail: giovanni.lamontagna@unina2.it

Submitted October 9, 2002; revision accepted February 13, 2003.

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