Chronic Kidney Disease (CKD) is a life-threatening pathology, often requiring haemodialysis (HD) and characterized by high oxidative stress, inflammation and perturbation of vascular endothelium. HD-patients have increased levels of von Willebrand factor (vWF), a large protein (~240kDa) released as ultra large polymers (UL-vWF, M.W.~20000-50000kDa) from vascular endothelial cells and megakaryocytes and responsible for the initiation of primary haemostasis. The pro-haemostatic potential of vWF increases with its length, which is proteolytically regulated by ADAMTS-13, a zinc-protease cleaving vWF at the single Tyr1605-Met1606 bond, and by leukocyte serine proteases, released by activated polymorphonuclear cells during bacterial infections. Previous studies showed that in vitro oxidation of Met1606 hinders vWF cleavage by ADAMTS-13, resulting in the accumulation of UL-vWF, which are not only more prothrombotic than shorter vWF oligomers but also more efficient in binding to bacterial adhesins during sepsis. Notably, HD-patients have greatly increased risk of developing dramatic cardiovascular and septic complications, whose underlying mechanisms are largely unknown. In this study, we first purified vWF from HD-patients and then chemically characterized its oxidative state. Interestingly, HD-vWF contains high carbonyl levels and increased proportion of UL-vWF polymers, which are also more resistant to ADAMTS-13. Using targeted mass spectrometry techniques, we estimated that HD-vWF contains <10% of Met1606 in the sulphoxide form. We conclude that oxidation of Met1606, impairing ADAMTS-13 cleavage, results in the accumulation of UL-vWF polymers, which recruit and activate more efficiently platelets and bind more tightly to bacterial adhesins, thus contributing to the development of thrombotic and septic complications in CKD.
Oxidation of Met1606 in von Willebrand Factor is a Risk Factor for Thrombotic and Septic Complications in Chronic Renal Failure
DE FILIPPIS, VINCENZO
;MASET, FABIO;SPOLAORE, BARBARA;POZZI, NICOLA;L. A. CALO';
2012
Abstract
Chronic Kidney Disease (CKD) is a life-threatening pathology, often requiring haemodialysis (HD) and characterized by high oxidative stress, inflammation and perturbation of vascular endothelium. HD-patients have increased levels of von Willebrand factor (vWF), a large protein (~240kDa) released as ultra large polymers (UL-vWF, M.W.~20000-50000kDa) from vascular endothelial cells and megakaryocytes and responsible for the initiation of primary haemostasis. The pro-haemostatic potential of vWF increases with its length, which is proteolytically regulated by ADAMTS-13, a zinc-protease cleaving vWF at the single Tyr1605-Met1606 bond, and by leukocyte serine proteases, released by activated polymorphonuclear cells during bacterial infections. Previous studies showed that in vitro oxidation of Met1606 hinders vWF cleavage by ADAMTS-13, resulting in the accumulation of UL-vWF, which are not only more prothrombotic than shorter vWF oligomers but also more efficient in binding to bacterial adhesins during sepsis. Notably, HD-patients have greatly increased risk of developing dramatic cardiovascular and septic complications, whose underlying mechanisms are largely unknown. In this study, we first purified vWF from HD-patients and then chemically characterized its oxidative state. Interestingly, HD-vWF contains high carbonyl levels and increased proportion of UL-vWF polymers, which are also more resistant to ADAMTS-13. Using targeted mass spectrometry techniques, we estimated that HD-vWF contains <10% of Met1606 in the sulphoxide form. We conclude that oxidation of Met1606, impairing ADAMTS-13 cleavage, results in the accumulation of UL-vWF polymers, which recruit and activate more efficiently platelets and bind more tightly to bacterial adhesins, thus contributing to the development of thrombotic and septic complications in CKD.
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