Clinical correlations of potential activity markers in systemic sclerosis

The objectives of the project were the following: (1) to establish a group of patients with a confirmed diagnosis of systemic sclerosis (Ssc), (2) to perform a detailed entrance examination of each patient, (3) to determine concentrations of potential activity markers, and (4) to make a comprehensive examination of each patient 1 year after inclusion into the study. A total of 49 patients were examined, 36 with a limited form of SSc, 9 with diffuse SSc, and 4 with other forms of SSc. We determined plasma or serum levels of the N-terminal propeptide of procollagen type III (NPIIIP), interleukin-6 (IL-6), soluble receptor for interleukin-2 (sIL-2r), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular adhesion molecule-1 (sVCAM-1), von Willebrand factor antigen (vWFAg), and big endothelin-1 (BET-1) using commercial kits, and urinary excretion of pyridinoline (PYR) and deoxypyridinoline (D-PYR) using high-performance liquid chromatography. Correlations of these markers with selected clinical data were calculated. The mean levels of all potential activity markers were increased compared with normal values, but differences were not significant. The levels of NPIIIP, D-PYR, and IL-6 were normal. The measured values after 1 year did not differ from the entry values. At entry, NPIIIP concentrations correlated with the finger-to-palm distance, and D-PYR corresponded with findings on a simplified health assessment questionnaire (FQ). IL-6 levels correlated with the leukocyte count, sIL-2r with the FQ, and ET-1 with the diffuse lung capacity for carbon monoxide. In general, we found only a few clinical correlates of potential activity markers. Our data confirmed the correlations of collagen metabolism markers with skin involvement and FQ, as was reported previously. Larger studies in this field are needed.