Differential expression of nitric oxide by dermal microvascular endothelial cells from patients with scleroderma

Vascular abnormalities in scleroderma are fundamental to the pathogenesis o f this disease. The objective of this study was to characterize dermal micr ovascular endothelial cells (DMEC) isolated from scleroderma patients with respect to growth and expression of the constitutive form of endothelial ni tric oxide synthase (eNOS). DMEC from patients with both systemic sclerosis (SSc) and localized scleroderma (Loc Scl) contained small intact microvasc ular structures in contrast to single cell isolations obtained from control skin. Immunoaffinity selection on anti-PECAM-1 beads yielded pure populati ons of DMEC expressing normal markers. While the morphology and initial gro wth of SSc DMEC closely paralleled control cells, the growth of SSc DMEC de creased with time in culture (doubling time of 3 days vs. 5 days). Expressi on of ecNOS mRNA was reduced in; both Loc Sd and SSc as shown by semi-quant itative RT-PCR (p < 0.001). Western blots showed variable but generally low er ecNOS protein levels and decreased levels of nitrogen oxides in media we re found from both SSc and Loc Sd relative to control cells. The results in dicate an intrinsic defect in the mechanism of nitric oxide production in D MEC isolated from scleroderma patients and suggest its possible involvement in the pathophysiology of scleroderma.