COL18A1 and systemic sclerosis: Serum levels of endostatin were significantly increased in naïve SSc patients (22.21 ± 2.80 ng/ml) compared both with healthy controls (12.84 ± 2.52 ng/ml, p = 0.02) and CYC-treated SSc patients (13.95 ± 2.11 ng/ml, p = 0.03) (Fig 6A).