Neutrophil a-defensins promote thrombosis in vivo by altering fibrin formation, structure, and stability

© 2019 by The American Society of Hematology. Inflammation and thrombosis are integrated, mutually reinforcing processes, but the interregulatory mechanisms are incompletely defined. Here, we examined the contribution of a-defensins (a-defs), antimicrobial proteins released from activated human neutrophils, on clot formation in vitro and in vivo. Activation of the intrinsic pathway of coagulation stimulates release of a-defs from neutrophils. a-Defs accelerate fibrin polymerization, increase fiber density and branching, incorporate into nascent fibrin clots, and impede fibrinolysis in vitro. Transgenic mice (Def 11 ) expressing human a-Def-1 developed larger, occlusive, neutrophil-rich clots after partial inferior vena cava (IVC) ligation than those that formed in wild-type (WT) mice. IVC thrombi extracted from Def 11 mice were composed of a fibrin meshwork that was denser and contained a higher proportion of tightly packed compressed polyhedral erythrocytes than those that developed in WT mice. Def 11 mice were resistant to thromboprophylaxis with heparin. Inhibiting activation of the intrinsic pathway of coagulation, bone marrow transplantation from WT mice or provision of colchicine to Def 11 mice to inhibit neutrophil degranulation decreased plasma levels of a-defs, caused a phenotypic reversion characterized by smaller thrombi comparable to those formed in WT mice, and restored responsiveness to heparin. These data identify a-defs as a potentially important and tractable link between innate immunity and thrombosis

Neutrophil a-defensins promote thrombosis in vivo by altering fibrin formation, structure, and stability

© 2019 by The American Society of Hematology. Inflammation and thrombosis are integrated, mutually reinforcing processes, but the interregulatory mechanisms are incompletely defined. Here, we examined the contribution of a-defensins (a-defs), antimicrobial proteins released from activated human neutrophils, on clot formation in vitro and in vivo. Activation of the intrinsic pathway of coagulation stimulates release of a-defs from neutrophils. a-Defs accelerate fibrin polymerization, increase fiber density and branching, incorporate into nascent fibrin clots, and impede fibrinolysis in vitro. Transgenic mice (Def 11 ) expressing human a-Def-1 developed larger, occlusive, neutrophil-rich clots after partial inferior vena cava (IVC) ligation than those that formed in wild-type (WT) mice. IVC thrombi extracted from Def 11 mice were composed of a fibrin meshwork that was denser and contained a higher proportion of tightly packed compressed polyhedral erythrocytes than those that developed in WT mice. Def 11 mice were resistant to thromboprophylaxis with heparin. Inhibiting activation of the intrinsic pathway of coagulation, bone marrow transplantation from WT mice or provision of colchicine to Def 11 mice to inhibit neutrophil degranulation decreased plasma levels of a-defs, caused a phenotypic reversion characterized by smaller thrombi comparable to those formed in WT mice, and restored responsiveness to heparin. These data identify a-defs as a potentially important and tractable link between innate immunity and thrombosis

Worse Outcome in Stroke Patients Treated with rt-PA Without Early Reperfusion: Associated Factors

[Abstract] Based on preclinical studies suggesting that recombinant tissue plasminogen activator (rt-PA) may promote ischemic brain injuries, we investigated in patients the possible risk of worse clinical outcome after rt-PA treatment as a result of its inability to resolve cerebral ischemia. Here, we designed a cohort study using a retrospective analysis of patients who received treatment with intravenous (4.5-h window) or intraarterial rt-PA, without or with thrombectomy. Controls were consecutive patients who did not receive recanalization treatment, who met all inclusion criteria. As a marker of reperfusion, we defined the variable of early neurological improvement as the difference between the score of the National Institute of Health Stroke Scale (NIHSS) (at admission and 24 h). The main variable was worsening of the patient's functional situation in the first 3 months. To compare quantitative variables, we used Student's t test or the Mann-Whitney test. To estimate the odds ratios of each independent variable in the patient's worsening in the first 3 months, we used a logistic regression model. We included 1154 patients; 577 received rt-PA, and 577 served as controls. In the group of patients treated with rt-PA, 39.4% who did not present clinical reperfusion data developed worsening within 3 months after stroke compared with 3.5% of patients with reperfusion (P < 0.0001). These differences were not significant in the control group. In summary, administration of rt-PA intravenously or intraarterially without reperfusion within the first 24 h may be associated with a higher risk of functional deterioration in the first 3 months.This study was supported by the Spanish Ministry of Economy and Competitiveness (SAF2014-56336-R), Xunta de Galicia (Consellería de Educación: GRC2014/027 and Axencia Galega de Innovación), Instituto de Salud Carlos III (PI13/00292 and PI14/01879), Spanish Research Network on Cerebrovascular Diseases RETICS-INVICTUS (RD16/0019), European Union FEDER program. Furthermore, T. Sobrino (CP12/03121) and F. Campos (CP14/00154) are recipients of research contracts (Miguel Servet Program of Instituto de Salud Carlos III). Clara Correa-Paz is the recipient of an FPI fellowship (BES-2015-073933) Spanish Ministry of Economy and Competitiveness.info:eu-repo/grantAgreement/MINECO/Programa Estatal de I+D+I Orientada a los Retos de la Sociedad/SAF2014-56336-R/ES/NANONEUROPROTECCION TERMO-MOLECULAR VECTORIZADA EN LA ISQUEMIA CEREBRALXunta de Galicia; GRC2014/027info:eu-repo/grantAgreement/MINECO/Programa Estatal de I+D+I Orientada a los Retos de la Sociedad/PI13%2F00292/ES/Encapsulación del activador del plasminógeno tisular (tPA) en nanoestructuras vectorizadas y eco-sensiblesinfo:eu-repo/grantAgremeent/MINECO/Programa Estatal de I+D+I Orientada a los Retos de la Sociedad/PI14%2F01879/ES/Reprogramación in vivo del cerebro isquémico como nueva opción terapéutica en el infarto cerebralinfo:eu-repo/grantAgreement/MINECO/Programa Estatal de I+D+I Orientada a los Retos de la Sociedad/RD16%2F0019%2F0015/ES/Red de Enfermedades Vasculares Cerebrales. INVICTUS PLUSinfo:eu-repo/grantAgreement/MINECO/Programa Estatal de I+D+I Orientada a los Retos de la Sociedad/CP14%2F00154/ES/info:eu-repo/grantAgreement/MINECO/Programa Estatal de Promoción del Talento y su Empleabilidad/BES-2015-073933/ES