Serum matrix metalloproteinases and tissue inhibitors of metalloproteinases in ankylosing spondylitis: MMP-3 is a reproducibly sensitive and specific biomarker of disease activity

Objective. To submit serum levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) to statistical analyses to test their exact degrees of clinical usefulness as biomarkers for detecting high disease activity in ankylosing spondylitis (AS), comparing them with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Methods. Serum levels of MMP-1, -3, -9 and TI MP-1 and -2 were measured in 42 AS patients and 20 healthy controls. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) provided the gold standard for measuring disease activity. Patients with BASDAI ≥4 were regarded as having high disease activity. The results were compared with results for a separate cohort of 41 AS patients. Results. Only MMP-3 levels were significantly higher in AS patients than in healthy controls (P