Endothelin-1 Does Not Change the Function of Monocyte-Derived Dendritic Cells Grown from Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is characterized by both vasculopathy and autoimmunity. The interplay between these pathogenetic links requires further exploration. The aim was to assess the interrelationship of endothelin-1 (ET-1), a vasoconstrictor peptide, whose levels are usually elevated in the plasma of the patients with SSc and the function of monocyte-derived dendritic cells (MDDCs), which serve as organizers of the immune response. MDDCs were grown from 5 patients with SSc and severe Raynaud's phenomenon and 5 healthy volunteers. The cells were further stimulated by synthetic ET-1, lipopolysaccharide (LPS) or both. The production of endogenous ET-1, TNF and IL-12 was assessed by RT-PCR and/or ELISA. The plasma levels of ET-1 were significantly higher in patients with SSc compared to healthy controls (p = 0.0005). The production of ET-1 by MDDCs was negligible in all examined conditions, while the release of TNF and IL-12 was stimulated by LPS but not by ET-1. The in vitro concentration of the exogenous ET-1, where added, was comparable to the plasma levels of ET-1 in patients with SSc. High plasma levels of ET-1 are characteristic for the patients with SSc and severe Raynaud's phenomenon. An in vitro model with concentrations of ET-1 comparable to those in the plasma of SSc patients has been elaborated. The examined function of MDDCs from SSc patients and healthy volunteers did not differ under these conditions and was not dependent on the presence of ET-1.