Daniel Zecher1, Arun Cumpelik, Jürg A Schifferli. 1. From the Department of Biomedicine (D.Z., A.C., J.S.), Department of Transplantation Immunology and Nephrology (D.Z.), and Department of Medicine (D.Z., J.S.), University Hospital Basel, Basel University, Basel, Switzerland.
Abstract
OBJECTIVE: Transfusion of aged blood has been associated with increased morbidity and mortality in critically ill patients. During storage, erythrocytes release increasing numbers of microvesicles (red blood cell-derived microvesicles [RBC-MV]). We hypothesized that RBC-MV mediate some of the deleterious effects of aged blood transfusions. APPROACH AND RESULTS: We established a murine transfusion model using RBC-MV purified from aged mouse erythrocytes. Injection of RBC-MV into healthy mice had no effect. However, they aggravated pulmonary leukocyte sequestration and peripheral blood leukopenia induced by lipopolysaccharides. Lipopolysaccharide-induced proinflammatory cytokines were significantly increased in plasma after RBC-MV injection. These effects were not seen in C5aR-deficient mice. In vitro, RBC-MV bound C3 fragments after incubation with plasma but failed to bind immunoglobulins, C1q, or mannose-binding lectin. Preventing thrombin generation inhibited complement activation in vitro and in vivo and reversed the proinflammatory effects of RBC-MV in lipopolysaccharide-primed mice. Finally, the RBC-MV-induced phenotype was recapitulated using phosphatidylserine-expressing liposomes, suggesting that surface expression of phosphatidylserine by RBC-MV was mechanistically involved. CONCLUSIONS: These results point toward a thrombin-dependent mechanism of complement activation by RBC-MV independent of the classical, lectin, or alternative pathway. Besides identifying RBC-MV as potential mediators of transfusion-related morbidity, our findings may be relevant for other inflammatory disorders involving intravascular microvesicle release, for example, sickle cell disease or thrombotic microangiopathy.
OBJECTIVE: Transfusion of aged blood has been associated with increased morbidity and mortality in critically illpatients. During storage, erythrocytes release increasing numbers of microvesicles (red blood cell-derived microvesicles [RBC-MV]). We hypothesized that RBC-MV mediate some of the deleterious effects of aged blood transfusions. APPROACH AND RESULTS: We established a murine transfusion model using RBC-MV purified from aged mouse erythrocytes. Injection of RBC-MV into healthy mice had no effect. However, they aggravated pulmonary leukocyte sequestration and peripheral blood leukopenia induced by lipopolysaccharides. Lipopolysaccharide-induced proinflammatory cytokines were significantly increased in plasma after RBC-MV injection. These effects were not seen in C5aR-deficient mice. In vitro, RBC-MV bound C3 fragments after incubation with plasma but failed to bind immunoglobulins, C1q, or mannose-binding lectin. Preventing thrombin generation inhibited complement activation in vitro and in vivo and reversed the proinflammatory effects of RBC-MV in lipopolysaccharide-primed mice. Finally, the RBC-MV-induced phenotype was recapitulated using phosphatidylserine-expressing liposomes, suggesting that surface expression of phosphatidylserine by RBC-MV was mechanistically involved. CONCLUSIONS: These results point toward a thrombin-dependent mechanism of complement activation by RBC-MV independent of the classical, lectin, or alternative pathway. Besides identifying RBC-MV as potential mediators of transfusion-related morbidity, our findings may be relevant for other inflammatory disorders involving intravascular microvesicle release, for example, sickle cell disease or thrombotic microangiopathy.
Authors: Gregory M Vercellotti; Agustin P Dalmasso; Terry R Schaid; Julia Nguyen; Chunsheng Chen; Marna E Ericson; Fuad Abdulla; Trevor Killeen; Margaret A Lindorfer; Ronald P Taylor; John D Belcher Journal: Am J Hematol Date: 2019-01-03 Impact factor: 10.047