Raynaud's Phenomenon and Plasma Endothelin: Correlations with Capillaroscopic Patterns in Systemic Sclerosis

Objective: We evaluated endothelin (ET)-1 plasma levels and some clinical measures in patients with primary Raynaud's phenomenon (PRP), and in patients with systemic sclerosis (SSc) and secondary RP (SRP), in the latter according to their different nailfold videocapillaroscopy (NVC) patterns of microangiopathy (early, active, and late).

Methods: Ninety-nine patients with SSc, 49 with PRP, and 45 control subjects were studied. NVC was performed in all patients to distinguish the pattern of microvascular damage, and the morphological alterations were scored by a semiquantitative rating scale. ET-1 plasma levels were evaluated in all individuals by ELISA.

Results: ET-1 plasma levels were significantly higher (p=0.001) in patients with both PRP and SRP, compared to controls. A significant positive correlation (p=0.03) was found between ET-1 plasma levels and SRP duration, but not between ET-1 plasma levels and PRP duration. Significant correlations were observed in patients with SSc between ET-1 plasma levels and clinical measures (e.g., digital ulcers), as well as the score value of single NVC measures, such as the number of capillaries, "ramified" capillaries, and enlarged capillaries (p<0.05). Finally, the highest ET-1 plasma levels were found in patients with SSc showing the late pattern of microangiopathy when compared to the early pattern (p=0.03) and to controls (p=0.003).

Conclusion: Highest ET-1 plasma levels were detected in the more advanced stage of the SSc microangiopathy, namely the late NVC pattern, characterized by capillary loss and increased tissue fibrosis; this might support the involvement of ET-1 in the progression of the microvascular/fibrotic SSc damage.