THE USE OF SEROLOGIC MARKERS FOR COLLAGEN-SYNTHESIS AND DEGRADATION IN SYSTEMIC-SCLEROSIS

Background: Systemic sclerosis is characterized by excessive accumulat ion of collagen in all involved organs. Serum markers of collagen synt hesis and degradation, the aminoterminal propeptide of type III procol lagen (PIIINP), the carboxyterminal propeptide of type I procollagen ( PICP), and the crosslinked telopeptide of type I collagen (ICTP), can be measured. Objective: Our purpose was to investigate these markers i n different subgroups of untreated patients with systemic sclerosis an d in patients before and after various types of therapy. PIIINP and PI CP were also investigated in blister fluid from involved and uninvolve d skin. Methods: Sera from 97 patients and suction blister fluid from 13 patients were radioimmunoassayed. Results: The highest levels of PI IINP and PICP were found in blister fluid from involved skin. Patients with systemic sclerosis had higher serum levels of PIIINP than contro l subjects. The highest levels were found in patients with diffuse cut aneous systemic (type III) sclerosis; increased serum PIIINP was also characteristic of type II limited cutaneous systemic sclerosis. Most p atients with limited cutaneous type I systemic sclerosis had normal le vels. Serum PICP was within normal limits in all three types of system ic sclerosis. Variations in ICTP type I collagen degradation in genera l followed PICP. Immunosuppressive drugs significantly reduced PIIINP, whereas no significant decrease was found after photopheresis. PICP a nd ICTP also diminished after treatment with D-penicillamine and cyclo phosphamide given together with prednisone. Conclusion: PIIINP can be recommended for monitoring collagen synthesis in systemic sclerosis. O ur data support the use of immunosuppressive therapy for this disease.