348 Immunomodulatory Effects of Extracorporeal Photochemotherapy in Systemic Sclerosis

BACKGROUND: The aim of the present study was to evaluate the clinical and immunomodulatory effects of extracorporeal photochemotherapy (ECP) in systemic sclerosis (SSc). METHODS: In the study, we enrolled 16 patients with diffuse cutaneous SSc, who received 12 ECP treatments in total. Skin involvement was assessed by modified Rodnan skin score and high-resolution ultrasonography. Blood samples were taken prior to the first therapy and 6 weeks after each cycle. Samples were also obtained from 16 healthy controls. Lymphocyte subgroups were quantified by flow cytometry, autoantibodies were determined by ELISA technique, and levels of 17 circulating cytokines were measured by multiplex cytokine assay. We used in vitro test to assess the changes in suppressor capability of CD4+CD25+ Treg cells. RESULTS: After ECP treatments, the dermal thickness reduced and the mobility of the joints improved. Internal organ involvement did not deteriorate. Initially, patients had lower numbers and percentages of peripheral NKT, Th1, Tr1 and CD4+CD25+ Treg cells, compared to control values. Moreover, the suppressor activity of Treg cells was lower. During the therapy, the values of Tr1 and Treg cells elevated, and the suppressor capacity of Treg cells improved. Initially, patients had higher numbers and proportions of NK and Th17 cells, compared to control values. During the therapy, values of Th17 cells decreased. Levels of CCL2 and TGF-beta decreased, while the concentration of IL-1Ra, IL-10 and HGF increased during ECP. CONCLUSIONS: ECP contributes to the restoration of the balance between regulatory and effector immune mechanisms, leading to the deceleration of disease progression.