American Journal of Hematology 81:492–498 (2006)
ADAMTS13 Activity in Sickle Cell Disease John-John B. Schnog,1–3* Johanna A. Kremer Hovinga,4 Soraya Krieg,4 S¸ akir Akin,2,5 Bernhard La¨mmle,4 Dees P.M. Brandjes,1 Melvin R. Mac Gillavry,1 Fred D. Muskiet,6 and Ashley J. Duits2 on behalf of the CURAMA study groupy 1
Department of Internal Medicine, Slotervaart Hospital, Amsterdam, The Netherlands 2 Red Cross Blood Bank Foundation, Curac¸ao, Netherlands Antilles 3 Department of Internal Medicine, St. Elisabeth Hospital, Curac¸ao, Netherlands Antilles 4 Department of Hematology and Central Hematology Laboratory, Inselspital, University Hospital Berne, Switzerland 5 Department of Hematology, Erasmus Medical Center, Rotterdam, The Netherlands 6 Department of Pediatrics, St. Elisabeth Hospital, Curac¸ao, Netherlands Antilles
Sickle red blood cell (SRBC)-endothelial adhesion plays a central role in sickle cell disease (SCD)-related vaso-occlusion. As unusually large von Willebrand factor (ULVWF) multimers mediate SRBC-endothelial adhesion, we investigated the activity of ADAMTS13, the metalloprotease responsible for cleaving ULVWF multimers, in SCD. ADAMTS13 activity was determined using a quantitative immunoblotting assay. VWF:Ag and VWF:RCo were determined using commercial assays. The high-molecular-weight VWF multimer percentage was determined by employing gel electrophoresis. ADAMTS13 activity was similar among asymptomatic patients (n = 8), patients at presentation with a painful crisis (n = 23), and healthy controls. ADAMTS13/VWF:Ag ratios were lower in patients compared to healthy HbAA controls, with the lowest values at presentation with a painful crisis (P = 0.02). Division of samples in those with VWF:RCo/VWF:Ag ratios < 0.70 and those with ratios 0.70 revealed significantly more samples with ratios < 0.70 (P = 0.01) collected during painful crises. ULVWF multimers were detected in 6 patient samples and in 1 control sample. ADAMTS13/VWF:Ag ratios were inversely related to the duration of symptoms at presentation with an acute vaso-occlusive event (rs –0.67, P = 0.002). Although SCD is characterized by elevated VWF:Ag levels, no severe ADAMTS13 deficiency was detected in our patients. Am. J. Hematol. C 2006 Wiley-Liss, Inc. 81:492–498, 2006. V Key words: sickle cell disease; ADAMTS13; von Willebrand factor
INTRODUCTION Vaso-occlusion occurs continuously in patients with sickle cell disease (SCD), leading to ischemic organ damage with a decreased quality of life and
life expectancy. Exacerbations of this ongoing process come to the attention of the clinician as distinct clinical entities such as painful crises, ischemic strokes, and acute chest syndromes (ACSs) [1]. Over
J.B.S. and J.A.K.H. contributed equally to this work. y
The CURAMA study group is a collaborative effort studying sickle cell disease in the Netherlands and the Netherlands Antilles. Participating centers: the Department of Internal Medicine, Slotervaart Hospital, Amsterdam, the Netherlands; the Department of Vascular Medicine and the Department of Hematology, Academic Medical Center, Amsterdam, the Netherlands; the Department of Hematology, Erasmus Medical Center, Rotterdam, the Netherlands; the Department of Pathology, Groningen University Hospital, the Netherlands; the Department of Internal Medicine, the Laboratory of Clinical Thrombosis and Hemostasis, and the Cardiovascular Research Institute, Academic Hospital Maastricht, the Netherlands; The Red Cross Blood Bank Foundation, Curac¸ao, Netherlands Antilles; the Antillean Institute for Health Research, Curac¸ao, Netherlands Antilles. C 2006 Wiley-Liss, Inc. V
This work was supported in part by grants from the MachGaensslen Foundation Switzerland (to J.A.K.H.), the Swiss National Science Foundation (Grant 3200B0-108261 to B.L. and J.A.K.H.), and the Netherlands Antilles Foundation for Higher Clinical Education (NASKHO). *Correspondence to: J.B. Schnog, Department of Internal Medicine (9B), Louwesweg 6, 1066 EC, Amsterdam, The Netherlands. E-mail:
[email protected] Received for publication 19 August 2005; Accepted 9 December 2005 Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/ajh.20653
ADAMTS13 Activity in SCD
the past decades it has become evident that adhesive interactions between sickle red blood cells (SRBCs) and activated endothelium play an important role in the pathophysiology of vaso-occlusion [2]. Adhesion of SRBCs (as well as platelets and activated leukocytes) to activated vascular endothelium and/or to subendothelial structures (exposed as a result of endothelial damage and activation) prolongs the transit time of sickle erythrocytes through the microcirculation. This allows more time for HbS polymerization, leading to the entrapment of more SRBCs and, ultimately, to tissue ischemia and infarction. Many putative adhesion proteins and their receptors have been implicated in sickle cell adhesion, with one of the possible mechanisms of SRBC-(sub)endothelial adhesion occurring via unusually large von Willebrand factor (ULVWF) multimers [3–6]. At sites of vessel wall injury, ULVWF multimers (20,000 kDa and larger) are released from the activated endothelial cell’s Weibel Palade bodies and bind to the subendothelial matrix, thereby providing binding sites for platelets and initiating the formation of a platelet plug [7]. Under normal circumstances, these ULVWF multimers are rapidly cleaved into smaller and less thrombogenic VWF multimers by plasma proteases, the primary being the metalloprotease ADAMTS13 (‘‘a disintegrin-like and metalloprotease domain with thrombospondin type I motifs’’). A severe deficiency of ADAMTS13 activity (
