Altered VWF:ADAMTS13 homeostasis is a target for therapeutic intervention in sickle cell disease

Stroke is a leading cause of death and disability. The only therapy available is recombinant tissue plasminogen activator, but side effects limit its use. Platelets play a crucial role during stroke, and the inflammatory reaction promotes neurodegeneration. von Willebrand factor (VWF), an adhesion molecule for platelets, is elevated in patients with acute stroke. The activity of VWF is modulated by ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type I repeats-13) that cleaves VWF to smaller less-active forms. We recently documented that ADAMTS13 negatively regulates both thrombosis and inflammation. We report that deficiency or reduction of VWF reduces infarct volume up to 2-fold after focal cerebral ischemia in mice, thus showing the importance of VWF in stroke injury. In contrast, ADAMTS13 deficiency results in larger infarctions, but only in mice that have VWF. Importantly, infusion of a high dose of recombinant human ADAMTS13 into a wild-type mouse immediately before reperfusion reduces infarct volume and improves functional outcome without producing cerebral hemorrhage. Furthermore, recombinant ADAMTS13 did not enhance bleeding in a hemorrhagic stroke model. Our findings show the importance of VWF in regulating infarction and suggest that recombinant ADAMTS13 could be considered as a new therapeutic agent for prevention and/or treatment of stroke.

Sickle cell disease (SCD) is a severe genetic blood disorder characterized by hemolytic anemia, episodic vaso-occlusion, and progressive organ damage. Current management of the disease remains symptomatic or preventative. Specific treatment targeting major complications such as vaso-occlusion is still lacking. Recent studies have identified various cellular and molecular factors that contribute to the pathophysiology of SCD. Here, we review the role of these elements and discuss the opportunities for therapeutic intervention.

Researchers of sickle cell disease have traditionally used health care utilization as a proxy for pain and underlying vaso-occlusion. However, utilization may not completely reflect the amount of self-reported pain or acute, painful episodes (crises). To examine the prevalence of self-reported pain and the relationship among pain, crises, and utilization in adults with sickle cell disease. Prospective cohort study. Academic and community practices in Virginia. 232 patients age 16 years or older with sickle cell disease. Patients completed a daily diary for up to 6 months, recording their maximum pain (on a scale of 0 to 9); whether they were in a crisis (crisis day); and whether they used hospital, emergency, or unscheduled ambulatory care for pain on the previous day (utilization day). Summary measures included both simple proportions and adjusted probabilities (for repeated measures within patients) of pain days, crisis days, and utilization days, as well as mean pain intensity. Pain (with or without crisis or utilization of care) was reported on 54.5% of 31 017 analyzed patient-days (adjusted probability, 56%). Crises without utilization were reported on 12.7% of days and utilization on only 3.5% (unadjusted). In total, 29.3% of patients reported pain in greater than 95% of diary days, whereas only 14.2% reported pain in 5% or fewer diary days (adjusted). The frequency of home opiate use varied and independently predicted pain, crises, and utilization. Mean pain intensity on crisis days, noncrisis pain days, and total pain days increased as the percentage of pain days increased (P < 0.001). Intensity was significantly higher on utilization days (P < 0.001). However, utilization was not an independent predictor of crisis, after controlling for pain intensity. The study was done in a single state. Patients did not always send in their diaries. Pain in adults with sickle cell disease is the rule rather than the exception and is far more prevalent and severe than previous large-scale studies have portrayed. It is mostly managed at home; therefore, its prevalence is probably underestimated by health care providers, resulting in misclassification, distorted communication, and undertreatment.