SERUM CONCENTRATIONS OF CARBOXYTERMINAL PROPEPTIDE OF TYPE-1 PROCOLLAGEN AND TISSUE INHIBITOR OF METALLOPROTEINASE-1 IN PATIENTS WITH DERMATOMYOSITIS

Serum levels of carboxyterminal propeptide of type I procollagen (PICP ) and aminoterminal propeptide of type I procollagen (PINP) have been used as indices of collagen synthesis in patients with various fibroti c diseases during the active stages, One of the suggested contributory factors to the development of tissue fibrosis is a decrease in collag enase activity, which may be related to levels of serum tissue inhibit ors of metalloproteinases-l (TIMP-1), In this study, the serum levels of PICP and PINP in 20 patients with dermatomyositis and 29 control su bjects and of TIMP-1 in 29 patients with dermatomyositis and 29 contro l subjects were measured using an enzyme-linked immunosorbent assay (E LISA) or a radioimmunoassay (RIA), We found that the mean PICP level i n patients with dermatomyositis was significantly higher than that in normal controls (mean +/- SD 326 +/- 76 ng/ml vs 135 +/- 88 ng/ml; P < 0.001), In 60% of dermatomyositis patients, the serum PICP level was elevated (more than 311 ng/ml, i.e. 2 x SD above the mean control valu e). Elevated serum PICP levels were correlated with the incidence of e levated serum creatine kinase levels in patients with dermatomyositis, The serum concentration of PINP was not elevated in comparison with t hat of the normal control subjects (mean +/- SD 36 +/- 30 ng/ml vs 63 +/- 34 ng/ml), The mean TIMP-1 level in the patients with dermatomyosi tis was also significantly higher than in the normal control subjects (mean +/- SD 438 +/- 328 ng/ml vs 163 +/- 63 ng/ml; P < 0.001). In 59% of dermatomyositis patients, the mean serum TIMP-1 level was elevated (more than 289 ng/ml, i,e, 2 x SD above the mean control value). Seru m PICP and TIMP-1 levels might be useful for detecting disease activit y or severity in dermatomyositis.