Phenotypic Expression of ADAMTS13 in Glomerular Endothelial Cells

BACKGROUND: ADAMTS13 is the physiological von Willebrand factor (VWF)-cleaving protease. The aim of this study was to examine ADAMTS13 expression in kidneys from ADAMTS13 wild-type (Adamts13(+/+)) and deficient (Adamts13(−/−)) mice and to investigate the expression pattern and bioactivity in human glomerular endothelial cells. METHODOLOGY/PRINCIPAL FINDINGS: Immunohistochemistry was performed on kidney sections from ADAMTS13 wild-type and ADAMTS13-deficient mice. Phenotypic differences were examined by ultramorphology. ADAMTS13 expression in human glomerular endothelial cells and dermal microvascular endothelial cells was investigated by real-time PCR, flow cytometry, immunofluorescence and immunoblotting. VWF cleavage was demonstrated by multimer structure analysis and immunoblotting. ADAMTS13 was demonstrated in glomerular endothelial cells in Adamts13(+/+) mice but no staining was visible in tissue from Adamts13(−/−) mice. Thickening of glomerular capillaries with platelet deposition on the vessel wall was detected in Adamts13(−/−) mice. ADAMTS13 mRNA and protein were detected in both human endothelial cells and the protease was secreted. ADAMTS13 activity was demonstrated in glomerular endothelial cells as cleavage of VWF. CONCLUSIONS/SIGNIFICANCE: Glomerular endothelial cells express and secrete ADAMTS13. The proteolytic activity could have a protective effect preventing deposition of platelets along capillary lumina under the conditions of high shear stress present in glomerular capillaries.