Angiogenic and angiostatic factors in systemic sclerosis: increased levels of vascular endothelial growth factor are a feature of the earliest disease stages and are associated with the absence of fingertip ulcers

Abstract

To examine whether the lack of sufficient neoangiogenesis in systemic sclerosis (SSc) is caused by a decrease in angiogenic factors and/or an increase in angiostatic factors, the potent proangiogenic molecules vascular endothelial growth factor (VEGF) and basic fibroblast growth factor, and the angiostatic factor endostatin were determined in patients with SSc and in healthy controls. Forty-three patients with established SSc and nine patients with pre-SSc were included in the study. Serum levels of VEGF, basic fibroblast growth factor and endostatin were measured by ELISA. Age-matched and sex-matched healthy volunteers were used as controls. Highly significant differences were found in serum levels of VEGF between SSc patients and healthy controls, whereas no differences could be detected for endostatin and basic fibroblast growth factor. Significantly higher levels of VEGF were detected in patients with Scl-70 autoantibodies and in patients with diffuse SSc. Patients with pre-SSc and short disease duration showed significant higher levels of VEGF than healthy controls, indicating that elevated serum levels of VEGF are a feature of the earliest disease stages. Patients without fingertip ulcers were found to have higher levels of VEGF than patients with fingertip ulcers. Levels of endostatin were associated with the presence of giant capillaries in nailfold capillaroscopy, but not with any other clinical parameter. The results show that the concentration of VEGF is already increased in the serum of SSc patients at the earliest stages of the disease. VEGF appears to be protective against ischemic manifestations when concentrations of VEGF exceed a certain threshold level.

Figure 1

(a) Serum levels of vascular endothelial growth factor (VEGF) in patients with established systemic sclerosis (SSc) and in healthy controls. Data are shown as box plots, with upper and lower quartiles shaded. Highly significant differences were found for serum levels of VEGF compared with healthy controls. (b) Serum levels of VEGF analyzed according to the disease subset. Patients with diffuse SSc showed significant higher levels of VEGF than did patients with limited SSc. ^#P < 0.05.

Figure 2

Serum levels of (a) endostatin and (b) basic fibroblast growth factor (bFGF) in patients with established systemic sclerosis (SSc) and in healthy controls. Levels of endostatin and bFGF were not enhanced in the patients compared with healthy controls. Data are shown as box plots, with upper and lower quartiles shaded.

Figure 3

Serum levels of vascular endothelial growth factor (VEGF) according to disease duration. The analysis included patients with pre-systemic sclerosis (pre-SSc) (autoantibodies, capillaroscopy changes and Raynaud's phenomenon, but not yet fulfilling American College of Rheumatology criteria), patients with early SSc (diffuse SSc <3 years, limited SSc < 5 years) and patients with intermediate/late (imed/late) SSc (diffuse SSc ≥ 3 years, limited SSc ≥ 5 years). In all groups including patients with pre-SSc, VEGF levels were significantly increased compared with controls. No differences were found between patients with different disease duration. Data are shown as box plots, with upper and lower quartiles shaded. ^#P < 0.05.

Figure 4

Serum levels of vascular endothelial growth factor (VEGF) analyzed according to the presence of anti-Scl-70 autoantibodies. Patients with anti-topoisomerase I (Scl-70) autoantibodies (Scl-70 pos) showed significant higher levels of VEGF than patients without anti-Scl-70 autoantibodies (but positive for antinuclear antibodies) (Scl-70 neg) and higher levels than patients without detectable autoantibodies. Data are shown as box plots, with upper and lower quartiles shaded. ^#P < 0.05.

Figure 5

Serum levels of vascular endothelial growth factor (VEGF) in systemic sclerosis (SSc) patients with and without fingertip ulcers. Compared with healthy controls, serum levels of VEGF were increased in patients with fingertip ulcers. In patients without fingertip ulcers, however, levels of VEGF were even more enhanced, indicating that VEGF might be protective against the development of fingertip ulcers if its serum concentration exceeds a certain threshold level. Data are shown as box plots, with upper and lower quartiles shaded. ^#P < 0.05.