Capillary dimension measured by computer-based digitalized image correlated with plasma endothelin-1 levels in patients with systemic sclerosis

Endothelial and vascular damage are main leading disability in systemic sclerosis (SSc). Raynaud's phenomenon is the early symptom that presents vascular damage. Nailfold capillaroscopy (NFC) is an easily accessible diagnostic tool in secondary Raynaud's phenomenon. Considering the endothelial damage, clinical manifestations, and plasma cytokines was compared with traditionally used NFC parameter for, which to observe the number of capillaries, deletions in 3 mm, apical limb width and the capillary width itself. We hypothesize that a computer-based NFC system can generate a new powerful parameter which predicts the capillary dimension. We investigated the relationship among the plasma endothelin-1 (ET-1), clinical manifestations and quantitative analysis of computerized NFC, and to assess the optimal method in SSc. The level of ET-1 in 60 SSc patients, 30 healthy, and 23 disease controls were measured by enzyme-linked immunosorbent assay (ELISA) kit. We present a significant difference in all parameters of NFC between SSc patients and control groups. ET-1 level was increased in patients with SSc. In SSc group, capillary dimension and loss of capillaries were strongly associated with digital ulceration (p < 0.01) and pulmonary hypertension (p < 0.05). Capillary dimension and ET-1 level was in correlation with skin-hardening grade, and was higher in SSc patients with pulmonary hypertension or digital ulcer. Capillary dimension showed strong correlation with the endothelin-1 in SSc, healthy and disease control groups. (Rs = 0.31/p < 0.05, Rs = 0.82/p < 0.001, Rs = 0.83/p < 0.001). The results suggest that computer-based microscopic analysis of NFC is a useful method that potentially provides information on organ involvement and plasma ET-1. Capillary dimension maybe a powerful parameter possibly applicable in outpatient clinic for assessing SSc patients.