Abstract:

Objective To measure the expression of activin receptor-like kinases 1 （ALK1） in dermal fibroblasts from patients with systemic scleroderma （SSc） and to estimate its role in the production of fibronectin and plasminogen activator inhibitor-1 （PAI-1）. Methods Dermal fibroblasts were isolated from the lesions of 12 patients with SSc as well as the normal skin of 14 healthy controls, and subjected to a primary culture. The third-passage fibroblasts were used in the next experiment. Western blot and indirect immunofluorescence technique were utilized to quantify the expression of ALK1. A specific siRNA targeting ALK1 was designed, constructed, and transiently transfected into the control dermal fibroblasts, which were then classified into 2 groups to be cultured with or without the presence of transforming growth factor （TGF）-β1 for 72 hours followed by the detection of fibronectin and PAI-1 expression with Western blot. Results As Western blot and direct immunofluorescence technique showed, both control and SSc fibroblasts showed an expression of ALK1 in the cytoplasm and membrane, and the expression intensity of ALK1 in SSc fibroblasts was significantly higher than that in the control fibroblasts （1.97 ± 0.05 vs. 1.12 ± 0.03, t = 50.96, P < 0.05）. The expression of ALK1, fibronectin and PAI-1 was decreased by 90%, 58% and 31% respectively in specific siRNA-transfected SSc fibroblasts compared with the control siRNA-transfected fibroblasts. TGFβ1 significantly increased the expression of ALK1, fibronectin and PAI-1 in the control siRNA-transfected fibroblasts, but the increase was markedly inhibited by the siRNA-targeting ALK1. Conlusion TGFβ1 can promote the production of fibronectin and PAI-1 via ALK1 in fibroblasts, and ALK1 may be involved in the development of sclerosis in SSc.