The therapeutic options in systemic sclerosis (SSc) are limited mainly to the management of complications, and decelerating fibrosis and preventing disease progression are still great challenges. Extracorporeal photopheresis (ECP) is one of the promising therapeutic strategies in SSc; nevertheless, there is no consensus on the ideal timing and frequency of treatment cycles. In the present study, we evaluated the long-term effects of consecutive ECP treatments, and the stability of clinical and laboratory improvements. We enrolled nine patients with diffuse cutaneous SSc and performed 12 ECP cycles (24 ECP treatments) per patient in total. ECP cycles were carried out once in every 6 weeks, and each cycle consisted of two procedures. Sixteen healthy individuals served as controls for laboratory assessment. Following the sixth ECP cycle, we observed further improvement in skin score, which was confirmed by high-resolution ultrasonography as well. After the second ECP cycle, values of Tr1 and CD4+CD25(bright) Treg cells increased; however, Tr1 cells remained under control values until the 10th cycle. Suppressor activity of CD4+CD25+ Treg cells improved, while percentages of Th17 cells decreased. At the end of 12-month follow-up, we did not observe significant deterioration in skin involvement; however, improvement in laboratory parameters diminished after 12 months. If the first six ECP cycles are effective, uninterrupted continuation of treatment should be considered, which may lead to the normalization of Tr1 cell values along with further clinical improvement. Our laboratory observations indicate that immunomodulatory effect of ECP treatments lasts for 1 year only.
Keywords: Clinical effects; Extracorporeal photopheresis; Immune regulation; Immunological effects; Systemic sclerosis.