Iloprost treatment summer-suspension: effects on skin thermal properties and cytokine profile in systemic sclerosis patients

Aim: Aim of the study was to assess whether Iloprost treatment summer suspension modifies systemic cytokines levels, cutaneous thermal properties and functional response to a cold-induced stress in patients affected by systemic sclerosis (SSc). Methods: Twenty-eight patients fulfilling the American College of Rheumatology (ACR) criteria for SSc were included in the study. Patients recorded number, duration and pain-severity of Raynaud phenomenon (RP). Pain-severity was determined by a visual analog scale. Cytokines expression and production in peripheral blood mononuclear cells and serum were evaluated by RT-PCR and ELISA assay. Basal finger temperature (Tb), distal-dorsal difference temperature (DTdd) and thermal recovery time (tr) from cold stress were measured by means of functional infrared imaging (fIR). Measurements were performed in late spring, during routine Iloprost therapy (1-3 days infusion of 0.5-2 ng/kg every month), and in late summer after a therapy-withdrawal period. Results: Deterioration of SSc patients' skin thermal properties was observed in the period of therapy withdrawal (Tb reduction and tr enhancement; no DTdd differences) despite the improvement in symptoms of RP. A reduction in IL-12/23p40 gene expression was recorded after therapy withdrawal and a direct correlation between IL-12/23p40 and IL-23p19 gene expression was observed, stronger after therapy suspension. Conclusion: Our data suggest that Iloprost treatment summer suspension may induce the loss of the therapy beneficial effect on microcirculation despite the objective reduction of RP, thus favouring a continuous use of Iloprost in absence of severe side effects. Iloprost showed to modulate only IL-23 expression corroborating the idea that this cytokine is crucial for SSc development and progression.