Background: Henoch-Schonlein purpura (HSP) is a kind of systemic small vessel vasculitis in children. Endothelium cells injury induced by IgA1 is considered important in the pathogenesis of HSP. Research found that the apoptosis of vein endothelial cells was related to the vasculitis in HSP patients. Purpose: To observe the effect of IgA1 from HSP patients on the apoptosis of HUVEC and firstly analyze the mechanism of the apoptosis of HUVEC induced by IgA1. Methods: HUVECs were cultured in 3 different conditional media with IgA1 from HSP patients, normal healthy children and simply medium (blank control). Serum IgA1 was purified by jacalin affinity chromatography. The rates of apoptosis in HUVEC incubated with IgA1 were determined by TUNEL method and flow cytometry, respectively. The expression of the cytoskeletal proteins, such as FAK, Vinculin and MLCK was detected with the methods of Real-time PCR and Westernblot, respectively. Results: The present study showed that the apoptosis rate of HUVEC by IgA1 isolated from HSP patients was higher than blank control (14.77% ± 2.23% vs 2.25% ± 0.77%) (P < 0.01) and the rate of HUVEC by IgA1 from normal healthy children was higher than blank control (9.97% ± 1.48% vs 2.25% ± 0.77%) (P < 0.01). The cytoskeletal proteins, such as FAK, Vinculin and MLCK expression were down-regulated in HUVEC co-cultured with IgA1 isolated from HSP patients for 24h. Conclusion: These findings firstly on IgA1 from HSP patients may induce apoptosis of vascular endothelial cells through inhibiting the cytoskeletal proteins expression. IgA1 may accelerate progression of HSP by inducing apoptosis of vascular endothelial cells.
