Increased eNOS levels in hereditary angioedema

Hereditary angio-edema (HAE), characterized by recurrent episodes of angioedema involving the skin and the mucosa of the upper respiratory or the gastrointestinal tracts, results from heterozygosity for deficiency of the serine proteinase inhibitor (serpin), C1 inhibitor (C1-INH).

In this study, serum inflammatory cytokine levels and circulating endothelial cells collected from HAE patients during both acute attacks and asymptomatic periods were evaluated.

Twenty-four patients with Type I and 1 patient with Type II HAE in an asymptomatic period (Group I), 8 patients with Type I HAE during a mild to moderate acute attack (Group II) and 20 healthy subjects (13 females, mean age: 32.1±8.2years) were included. Serum IL-6, IL-8, IL-1β, TNF-α, vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) levels were detected by ELISA. Circulating endothelial cells (CECs) and circulating endothelial progenitors (CEPs) were evaluated using Fluorescence Activated Cell Sorting (FACS).

Serum eNOS levels of HAE patients were significantly higher than healthy subjects (p<0.006) while mean TNF-α levels in Group I were slightly lower (p<0.03) than Group II. There were no differences in terms of other inflammatory cytokines between the control subjects and HAE patients who were either in an asymptomatic period or experiencing an acute attack. CECs and CEPs were also similar.

These results suggest that an inflammatory response is not necessary to trigger HAE attacks. On the other hand, increased eNOS levels might reflect a sustained hyperpermeability state in HAE patients.