scholarly journals Hemolytic uremic syndrome–associated Shiga toxins promote endothelial-cell secretion and impair ADAMTS13 cleavage of unusually large von Willebrand factor multimers

Blood ◽  
2005 ◽  
Vol 106 (13) ◽  
pp. 4199-4209 ◽  
Author(s):  
Leticia H. Nolasco ◽  
Nancy A. Turner ◽  
Aubrey Bernardo ◽  
Zhenyin Tao ◽  
Thomas G. Cleary ◽  
...  

Shiga toxin 1 (Stx-1) and Stx-2 produced by enterohemorrhagic Escherichia coli cause the diarrhea-associated hemolytic uremic syndrome (HUS). This type of HUS is characterized by obstruction of the glomeruli and renal microvasculature by platelet-fibrin thrombi, acute renal failure, thrombocytopenia, microvascular hemolytic anemia, and plasma levels of von Willebrand factor (VWF)-cleaving protease (ADAMTS13) activity that are within a broad normal range. We investigated the mechanism of initial platelet accumulation on Stx-stimulated endothelial cells. Stx-1 or Stx-2 (1-10 nM) stimulated the rapid secretion of unusually large (UL) VWF multimeric strings from human umbilical vein endothelial cells (HUVECs) or human glomerular microvascular endothelial cells (GMVECs). Perfused normal human platelets immediately adhered to the secreted ULVWF multimeric strings. Nanomolar concentrations (1-10 nM) of the Shiga toxins were as effective in inducing the formation of ULVWF-platelet strings as millimolar concentrations (0.1-20 mM) of histamine. The rate of ULVWF-platelet string cleavage by plasma or recombinant ADAMTS13 was delayed by 3 to 10 minutes (or longer) in the presence of 10 nM Stx-1 or Stx-2 compared with 20 mM histamine. Stx-induced formation of ULVWF strings, and impairment of ULVWF-platelet string cleavage by ADAMTS13, may promote initial platelet adhesion above glomerular endothelial cells. These processes may contribute to the evolution of glomerular occlusion by platelet and fibrin thrombi in diarrhea-associated HUS.

1997 ◽  
Vol 77 (06) ◽  
pp. 1182-1188 ◽  
Author(s):  
Ulrich M Vischer ◽  
Claes B Wollheinn

Summaryvon Willebrand factor (vWf) is released from endothelial cell storage granules after stimulation with thrombin, histamine and several other agents that induce an increase in cytosolic free calcium ([Ca2+]i). In vivo, epinephrine and the vasopressin analog DDAVP increase vWf plasma levels, although they are thought not to induce vWf release from endothelial cells in vitro. Since these agents act via a cAMP-dependent pathway in responsive cells, we examined the role of cAMP in vWf secretion from cultured human umbilical vein endothelial cells. vWf release increased by 50% in response to forskolin, which activates adenylate cyclase. The response to forskolin was much stronger when cAMP degradation was blocked with IBMX, an inhibitor of phosphodiesterases (+200%), whereas IBMX alone had no effect. vWf release could also be induced by the cAMP analogs dibutyryl-cAMP (+40%) and 8-bromo-cAMP (+25%); although their effect was weak, they clearly potentiated the response to thrombin. Epinephrine (together with IBMX) caused a small, dose-dependent increase in vWf release, maximal at 10-6 M (+50%), and also potentiated the response to thrombin. This effect is mediated by adenylate cyclase-coupled β-adrenergic receptors, since it is inhibited by propranolol and mimicked by isoproterenol. In contrast to thrombin, neither forskolin nor epinephrine caused an increase in [Ca2+]j as measured by fura-2 fluorescence. In addition, the effects of forskolin and thrombin were additive, suggesting that they act through distinct signaling pathways. We found a close correlation between cellular cAMP content and vWf release after stimulation with epinephrine and forskolin. These results demonstrate that cAMP-dependent signaling events are involved in the control of exocytosis from endothelial cells (an effect not mediated by an increase in [Ca2+]i) and provide an explanation for epinephrine-induced vWf release.


2001 ◽  
Vol 2 (5) ◽  
pp. 352-354 ◽  
Author(s):  
Agnès Veyradier ◽  
François Brivet ◽  
Martine Wolf ◽  
Catherine Boyer-Neumann ◽  
Bernadette Obert ◽  
...  

2017 ◽  
Vol 44 (5) ◽  
pp. 531-537 ◽  
Author(s):  
P. V. Avdonin ◽  
A. A. Tsitrina ◽  
G. Y. Mironova ◽  
P. P. Avdonin ◽  
I. L. Zharkikh ◽  
...  

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Natalia I Dmitrieva ◽  
Maurice B Burg

Hypercoagulability increases the risk of thrombi that cause cardiovascular events. Dehydration and hypernatremia are often accompanied by thrombosis, but the mechanisms are not clear. Von Willebrand Factor is secreted by endothelium, affecting aggregation of platelets and promoting activation of the coagulation cascade and formation of thrombi. Here we show that in culture of primary Human Umbilical Vein Endothelia Cells, elevating medium osmolality to 320-380 mosmol/kg by adding NaCl reversibly increases both vWF mRNA and vWF secretion. The high NaCl increases expression of tonicity regulated transcription factor NFAT5 and its binding to promoter of vWF gene, suggesting that vWF upregulation is caused by hypertonic signaling. To elevate NaCl in vivo, we modeled mild dehydration, subjecting mice to water restriction (WR) for 9 days by feeding them with gel food containing 30% of water. Such WR elevates blood sodium from 145.1±0.5 to 150.2±1.3 mmol/l and activates hypertonic signaling as evidenced from increased expression of NFAT5 in tissues. WR increased vWF mRNA in liver and lung and raised vWF protein in blood. Immunostaining of liver revealed increased production of vWF protein by endothelium and increased number of microthrombi inside capillaries. WR also increased blood level of D-dimer, a fibrinogen degradation product indicative of ongoing coagulation and thrombolysis. We conclude that elevation of extracellular sodium within the physiological range raises expression and secretion of von Willebrand Factor sufficiently to increase coagulability of blood and risk of thrombosis. The results suggest that hydration and salt intake are modifiable factors that affect coagulability and thrombosis through high salt-dependent secretion of vWF from endothelial cells.


2021 ◽  
Vol 100 (4) ◽  
pp. 12-19
Author(s):  
Kh.М. Emirova ◽  
◽  
O.M. Orlova ◽  
E.M. Chichuga ◽  
А.L. Мuzurov ◽  
...  

Atypical hemolytic uremic syndrome (aHUS) is an orphan disease caused by hyperactivation of the alternative complement pathway. Objective of the study: to assess the state of the «ADAMTS13 – von Willebrand factor (vWF) – platelets» system in children with aHUS. Materials and methods of research: [by the FRET method (fluorescence resonance energy transfer) for the FRETSVWF73 (Peptide Institude, Inc., Japan)] hydrolysis of the fluorescent substrate and ADAMTS13 antigen [by ELISA using TECHNOZYM® ADAMTS13 5450551 ELISA (Technoclone GmbH, Austria)], vWF activity [for platelet agglutination (aggregation) in the presence of ristomycin (NPO Renam reagent kit for the ALAT-230LA-2 aggregometer, Russia)] and vWF antigen [by ELISA using the TECHNOZYM® vWF kit: Ag 5450201 ELISA (Technoclone GmbH , Austria)]. Results: there was a decrease in the activity and concentration of ADAMTS13 in 63% and 62% of patients, respectively. A decrease in vWF activity was noted in 44% of cases, an increase in its concentration – in 54% of children. Thrombocytopenia was diagnosed in 99% of children. Conclusion: the imbalance in the «ADAMTS13 – vWF – platelets» system supports the process of thrombus formation with the development of organ ischemia in aHUS under conditions of endothelial dysfunction. Reduced ADAMTS13 activity predicts the severity of the disease.


1987 ◽  
Author(s):  
Richard B Levene ◽  
Francis M Booyse ◽  
Juan Chediak ◽  
Therodore S Zimmerman ◽  
David M Livingston ◽  
...  

Studies were conducted to characterize the biosynthesis of von Willebrand factor (vWf) by cultured endothelial cells (EC) derived from the umbilical vein of a patient with type HA von Willebrand’ s disease. The patient’ s EC, compared with those from normal individuals, produced vWf which had decreased amounts of large multimers and an increase in rapidly migrating satellite species, features which are characteristic of plasma vWf from patients with type IIA von Willebrand’ s disease. The typQ IIA EC produced a full spectrum of vWf multimers in both cell lysates and post-culture medium, although the relative amounts of the larger species were decreased. The large multimers were degraded in conjunction with the appearance of rapidly migrating satellites which contained =170 kDa proteolytic fragments. Kinetic studies demonstrated that the =170 kDa species is not a primary translation product Normal metabolically labeled vWf, incubated with either the patient’ s EC or medium conditioned by these cells, was not similarly degraded. These results demonstrated that this patient’ s clinical phenotype is due to abnormal proteolysis and not to a primary failure of subunit oligomerization. Moreover, the increased degradation is attributable to increased proteolytic sensitivity of an abnormal vWf molecule rather than to pathologically elevated levels of endogenous proteases. Experiments using monoclonal antibodies which recognize either N- or C-associated epitopes have localized the defect to the N-terminal portion of the vWf molecule, which is believed to be involved in the inter-dimer polymerization reaction. The type DA EC also contained a single vWf mRNA species which comigrated with that from normal EC. However, the type HA EC contained 8-10 fold more vWf mRNA than their normal counterparts. These results suggest that the functional defect in this patient is caused by a subtle mutation in the vWf coding sequence leading to increased proteolytic sensitivity of its protein product


1987 ◽  
Author(s):  
J C Giddings ◽  
L Shall

Human umbilical vein endothelial cells (EC) were cultured in the presence of 4p-phorbol 12-myristate 13-acetate (PMA, 10ug/l), interleukin 1 (IL-1, 1 unit/ml) and interleukin 2 (IL-2, 1 unit/ml), and secretion of von Willebrand factor activity (vWF, Ristocetin co-factor) and von Willebrand factor antigen (vWFAG, ELISA Technique) measured at intervals. Confluent control EC were treated with PMA, IL-1 and IL-2, and the supernatant medium assayed for release of vWF and vWFAg. Treated cells were also examined for vWFAg by immuno-fluorescence. The levels of both vWF and vWFAg in cultures containing IL-1 were significantly higher than those in control cultures after 5-6 days growth. Moreover, vWF and vWFAg increased significantly in the supernatant of confluent control EC incubated further in the presence of IL-1. Furthermore, the characteristic fluorescence pattern of endothelial vWFAg was markedly reduced in EC treated with IL-1. The levels of vWF and vWFAg in cultures containing PMA were also significantly higher than those of control cultures. In these conditions, however, the growth of cells appeared to be enhanced, and confluence was observed after about 6 days in the presence of PMA compared to 9 - 10 days in control cultures. The mean levels of vWF and vWFAg in the supernatant of EC incubated with PMA were higher than the control values but the differences were not statistically significant. Immunofluorescence of PMA-treated cells suggested that vWFAg might be less granular than in control cells but the differences were not as marked as those seen with IL-1. The results of all assays in the presence of IL-2 were not significantly different from those of control cells. In all instances no morphological evidence of endothelial injury was observed and more than 90% of cells remained viable at the termination of cultures. The results indicated that the synthesis and release of vWF were increased in the presence of PMA, and secretion of vWF was stimulated by IL-1. The data suggest that secreted vWF might contribute to the previously reported enhanced procoagulant and adhesive properties of EC treated with these substances.


1992 ◽  
Vol 286 (2) ◽  
pp. 631-635 ◽  
Author(s):  
M A Carew ◽  
E M Paleolog ◽  
J D Pearson

Secretion of von Willebrand factor (vWf) glycoprotein from storage granules in human umbilical-vein endothelial cells was studied in vitro. Either elevation of intracellular Ca2+ concentration ([Ca2+]i) with a Ca2+ ionophore or activation of protein kinase (PK) C by phorbol 12-myristate 13-acetate caused vWf secretion, and together the agents acted synergistically. However, when vWf release was stimulated by receptor-mediated agonists, selective inhibition of PKC had no effect on histamine-induced secretion and significantly elevated thrombin-induced secretion. Furthermore, ATP, which efficiently elevates [Ca2+]i in these cells, was a very poor effector of vWf release. We conclude that elevation of [Ca2+]i by physiological agonists is necessary for vWf release, but other signalling mechanisms, as yet uncharacterized, but not due to PKC activation, are required for full induction of the secretory pathway.


Sign in / Sign up

Export Citation Format

Share Document