| 1. |
- Ademuyiwa, Adesoji O., et al.
(författare)
-
Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
-
Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
|
|
| 2. |
- Babiker, Adil A., et al.
(författare)
-
Prothrombotic effect of prostasomes of metastatic cell and seminal origin
- 2007
-
Ingår i: The Prostate. - : Wiley. - 0270-4137 .- 1097-0045. ; 67:4, s. 378-388
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND. Prostasomes are secretory granules produced by the glandular epithelial cells of the prostate. Seminal prostasomes contain high amounts of Tissue Factor (TF) but no studies of TF on malignant cell prostasomes have been made. Here we compare the expression, phosphorylation, and function of TF on prostasomes of different origin. METHODS. TF was detected on prostasomes isolated from seminal fluid and human prostate cancer cell lines (PC-3, DU145, and LNCaP) using FACS and enzyme immunoassay (EIA). Incubation of prostasomes with radioactive ATP under conditions favoring protein kinase A activity led to phosphorylation of TF as detected by immunoprecipitation and SDS-PAGE. The prothrombotic effect of prostasomes was investigated in whole blood and recalcified plasma. Blocking experiments were performed using anti-TF antibodies and corn trypsin inhibitor. RESULTS. TF was expressed on all tested prostasome preparations with lowest values found for seminal ones. Prostasomal TF was the main endogenous substrate for prostasomal protein kinase A. All tested prostasome preparations greatly enhanced the rate of clot formation in a dose-dependent fashion, that is, the clotting capability of prostasomes seemed to be related to the extent of their expression of TF. In addition, the density of the clot varied between different prostasome preparations. When incubated in whole blood, prostasomes were found to associate to WBC thereby inducing them to express and release TF. CONCLUSIONS. These data show that TF is overexpressed and also subjected to phosphorylation by malignant cell prostasomes. This suggests major roles for prostasomes in thrombotic events that occur in some advanced cases of prostate cancer.
|
|
| 3. |
- Barbu, Andreea, et al.
(författare)
-
The role of complement factor C3 in lipid metabolism
- 2015
-
Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 67:1, s. 101-107
-
Forskningsöversikt (refereegranskat)abstract
- Abundant reports have shown that there is a strong relationship between C3 and C3a-desArg levels, adipose tissue, and risk factors for cardiovascular disease, metabolic syndrome and diabetes. The data indicate that complement components, particularly C3, are involved in lipid metabolism. The C3 fragment, C3a-desArg, functions as a hormone that has insulin-like effects and facilitates triglyceride metabolism. Adipose tissue produces and regulates the levels of complement components, which promotes generation of inflammatory initiators such as the anaphylatoxins C3a and C5a. The anaphylatoxins trigger a cyto/chemokine response in proportion to the amount of adipose tissue present, and induce inflammation and mediate metabolic effects such as insulin resistance. These observations support the concept that complement is an important participant in lipid metabolism and in obesity, contributing to the metabolic syndrome and to the low-grade inflammation associated with obesity.
|
|
| 4. |
|
|
| 5. |
- Engberg, Anna E., et al.
(författare)
-
Prediction of inflammatory responses induced by biomaterials in contact with human blood using protein fingerprint from plasma
- 2015
-
Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 36, s. 55-65
-
Tidskriftsartikel (refereegranskat)abstract
- Inappropriate complement activation is often responsible for incompatibility reactions that occur when biomaterials are used. Complement activation is therefore a criterion included in legislation regarding biomaterials testing. However, no consensus is yet available regarding appropriate complement-activation-related test parameters. We examined protein adsorption in plasma and complement activation/cytokine release in whole blood incubated with well-characterized polymers. Strong correlations were found between the ratio of C4 to its inhibitor C4BP and generation of 10 (mainly pro-inflammatory) cytokines, including IL-17, IFN-gamma, and IL-6. The levels of complement activation products correlated weakly (C3a) or not at all (C5a, sC5b-9), confirming their poor predictive values. We have demonstrated a direct correlation between downstream biological effects and the proteins initially adhering to an artificial surface after contact with blood. Consequently, we propose the C4/C4BP ratio as a robust, predictor of biocompatibility with superior specificity and sensitivity over the current gold standard. (C) 2014 Elsevier Ltd. All rights reserved.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Gustafson, Elisabet K., et al.
(författare)
-
Exposure of von Willebrand Factor on Isolated Hepatocytes Promotes Tethering of Platelets to the Cell Surface
- 2019
-
Ingår i: Transplantation. - : Wolters Kluwer. - 0041-1337 .- 1534-6080. ; 103:8, s. 1630-1638
-
Tidskriftsartikel (refereegranskat)abstract
- Background. Hepatocyte transplantation (Hctx) is a potentially attractive method for the treatment of acute liver failure and liver-based metabolic disorders. Unfortunately, the procedure is hampered by the instant blood-mediated inflammatory reaction (IBMIR), a thromboinflammatory response elicited by the vascular innate immune system, causing activation of the coagulation and complement systems and clearance of transplanted cells. Observations have also revealed platelets adhered to the surface of the hepatocytes (Hc). To establish Hctx as a clinical treatment, all factors that trigger IBMIR need to be identified and controlled. This work explores the expression of von Willebrand factor (VWF) on isolated Hc resulting in tethering of platelets. Methods. VWF on Hc was studied by flow cytometry, confocal microscopy, immunoblot, and real-time polymerase chain reaction. Interaction between Hc and platelets was studied in a Chandler loop model. Adhesion of platelets to the hepatocyte surface was demonstrated by flow cytometry and confocal microscopy. Results. Isolated Hc constitutively express VWF on their cell surface and mRNA for VWF was found in the cells. Hc and platelets, independently of coagulation formed complexes, were shown by antibody blocking studies to be dependent on hepatocyte-associated VWF and platelet-bound glycoprotein Ib alpha. Conclusions. VWF on isolated Hc causes, in contact with blood, adhesion of platelets, which thereby forms an ideal surface for coagulation. This phenomenon needs to be considered in hepatocyte-based reconstitution therapy and possibly even in other settings of cell transplantation.
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Hamad, Osama A., 1978-, et al.
(författare)
-
Complement activation triggered by chondroitin sulfate released by thrombin receptor-activated platelets
- 2008
-
Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 6:8, s. 1413-1421
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Chondroitin sulfate (CS) is a glycosaminoglycan released by activated platelets. OBJECTIVE: Here we test the hypothesis that CS released by activated platelets can trigger complement activation in the fluid phase. METHODS AND RESULTS: Thrombin receptor-activating peptide (TRAP)-6 was used to activate platelets in platelet-rich plasma and blood, anticoagulated with the thrombin inhibitor lepirudin. TRAP activation induced fluid-phase complement activation, as reflected by the generation of C3a and sC5b-9, which could be attenuated by the C3 inhibitor compstatin. Chondroitinase ABC treatment of supernatants from activated platelets totally inhibited the activation, indicating that platelet-derived CS had initiated the complement activation. Furthermore, addition of purified CS to plasma strongly triggered complement activation. C1q was identified as the recognition molecule, as it bound directly to CS, and CS-triggered complement activation could be restored in C1q-depleted serum by adding purified C1q. TRAP activation of whole blood increased the expression of CD11b on leukocytes and generation of leukocyte-platelet complexes. It was demonstrated that these leukocyte functions were dependent on C3 activation and signaling via C5a, as this expression could be inhibited by compstatin and by a C5aR antagonist. CONCLUSIONS: We conclude that platelets trigger complement activation in the fluid phase by releasing CS, which leads to inflammatory signals mediated by C5a.
|
|
| 12. |
- Hamad, Osama A., 1978-, et al.
(författare)
-
Complement component C3 binds to activated normal platelets without preceding proteolytic activation and promotes binding to complement receptor 1
- 2010
-
Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 184:5, s. 2686-2692
-
Tidskriftsartikel (refereegranskat)abstract
- It has been reported that complement is activated on the surface of activated platelets, despite the presence of multiple regulators of complement activation. To reinvestigate the mechanisms by which activated platelets bind to complement components, the presence of complement proteins on the surfaces of nonactivated and thrombin receptor-activating peptide-activated platelets was analyzed by flow cytometry and Western blot analyses. C1q, C4, C3, and C9 were found to bind to thrombin receptor-activating peptide-activated platelets in lepirudin-anticoagulated platelet-rich plasma (PRP) and whole blood. However, inhibiting complement activation at the C1q or C3 level did not block the binding of C3 to activated platelets. Diluting PRP and chelating divalent cations also had no effect, further indicating that the deposition of complement components was independent of complement activation. Furthermore, washed, activated platelets bound added C1q and C3 to the same extent as platelets in PRP. The use of mAbs against different forms of C3 demonstrated that the bound C3 consisted of C3(H(2)O). Furthermore, exogenously added soluble complement receptor 1 was shown to bind to this form of platelet-bound C3. These observations indicate that there is no complement activation on the surface of platelets under physiological conditions. This situation is in direct contrast to a number of pathological conditions in which regulators of complement activation are lacking and thrombocytopenia and thrombotic disease are the ultimate result. However, the generation of C3(H(2)O) represents nonproteolytic activation of C3 and after factor I cleavage may act as a ligand for receptor binding.
|
|
| 13. |
- Hamad, Osama A., et al.
(författare)
-
Contact activation of C3 enables tethering between activated platelets and polymorphonuclear leukocytes via CD11b/CD18
- 2015
-
Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 114:6, s. 1207-1217
-
Tidskriftsartikel (refereegranskat)abstract
- Complement component C3 has a potential role in thrombotic pathologies. It is transformed, without proteolytic cleavage, into C3(H2O) upon binding to the surface of activated platelets. We hypothesise that C3(H2O) bound to activated platelets and to platelet-derived microparticles (PMPs) contributes to platelet-PMN complex (PPC) formation and to the binding of PMPs to PMNs. PAR-1 activation of platelets in human whole blood from normal individuals induced the formation of CD16(+)/CD42a(+) PPC. The complement inhibitor compstatin and a C5a receptor antagonist inhibited PPC formation by 50 %, while monoclonal antibodies to C3(H2O) or anti-CD11b inhibited PPC formation by 75-100 %. Using plasma protein-depleted blood and blood from a C3-deficient patient, we corroborated the dependence on C3, obtaining similar results after reconstitution with purified C3. By analogy with platelets, PMPs isolated from human serum were found to expose C3(H2O) and bind to PMNs. This interaction was also blocked by the anti-C3(H2O) and anti-CD11b monoclonal antibodies, indicating that C3(H2O) and CD11b are involved in tethering PMPs to PMNs. We confirmed the direct interaction between C3(H2O) and CD11b by quartz crystal microbalance analysis using purified native C3 and recombinant CD11b/CD18 and by flow cytometry using PMP and recombinant CD11b. Transfectants expressing CD11b/CD18 were also shown to specifically adhere to surface-bound C3(H2O). We have identified contact-activated C3(H2O) as a novel ligand for CD11b/CD18 that mediates PPC formation and the binding of PMPs to PMNs. Given the various roles of C3 in thrombotic reactions, this finding is likely to have important pathophysiological implications.
|
|
| 14. |
|
|
| 15. |
- Hamad, Osama A., 1978-, et al.
(författare)
-
Contribution of chondroitin sulfate A to the binding of complement proteins to activated platelets
- 2010
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:9, s. e12889-
-
Tidskriftsartikel (refereegranskat)abstract
- Exposure of chondroitin sulfate A (CS-A) on the surface of activated platelets is well established. The aim of the present study was to investigate to what extent CS-A contributes to the binding of C1q and the complement regulators C1 inhibitor (C1INH), C4b-binding protein (C4BP), and factor H to platelets. Human serum was passed over Sepharose conjugated with CS-A, and bound proteins were identified by Western blotting, and mass spectrometric analysis. C1q was identified as the main protein that specifically bound to CS-A, but C4BP and factor H were also shown to interact. Binding of C1INH was dependent of the presence of C1q and not bound to CS-A from C1q-depleted serum. The specific interactions observed of these proteins with CS-A were subsequently confirmed by surface plasmon resonance analysis using purified proteins. Importantly, C1q, C4BP, and factor H were shown to bind also to activated platelets and this interaction was inhibited by a CS-A-specific monoclonal antibody, thereby linking the binding of C1q, C4BP, and factor H to exposure of CS-A on platelets. CS-A-bound C1q was also shown to amplify the binding of model immune complexes to both microtiter plate-bound CS-A and to activated platelets. In conclusion, this study supports the concept that CS-A contributes to the binding of C1q, C4BP, and factor H to platelets, thereby adding CS-A to the previously reported binding sites for these proteins on the platelet surface. CS-A-bound C1q seems to amplify the binding of immune complexes to activated platelets, suggesting a role for this molecule in immune complex diseases.
|
|
| 16. |
- Hamad, Osama A., 1978-
(författare)
-
Crosstalk Between Activated Platelets and the Complement System
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Several studies have shown that complement and thrombotic events co-exist. Platelets have been suspected to act as the bridge between the two cascade systems. To study the platelet-induced complement activation we developed a system in which platelets were activated by thrombin receptor activating peptide (TRAP) in platelet rich plasma (PRP) or whole blood anti-coagulated using the specific thrombin inhibitor, lepirudin. TRAP-activated platelets induced a fluid-phase complement activation measured as generation of C3a and sC5b-9, triggered by released chondroitin sulphate-A (CS-A) which interacted with C1q and activated the complement system through the classical pathway. Complement components C1q, C3, C4 and C9 were also shown to bind to TRAP-activated platelets but this binding did not seem to be due to a complement activation since blocking of complement activation at the C1q or C3 levels did not affect the binding of the complement proteins. The C3 which bound to activated platelets consisted of C3(H2O), indicating that bound C3 was not proteolytically activated. Binding of C1q was partially dependent on CS-A exposure on activated platelets. The abolished complement activation on the surface of activated platelets was suggested to be dependent on the involvement of several complement inhibitors. We confirmed the binding of C1INH and factor H to activated platelets. To this list we have added another potent complement inhibitor, C4BP. The binding of factor H and C4BP was shown to be dependent on exposure of CS-A on activated platelets. The physiological relevance of these reactions was reflected in an elevated expression of CD11b on leukocytes, and increased generation of platelet-leukocyte complexes. The platelets were involved in these events by at least two different mechanisms; generation of C5a which activated leukocytes and binding of C3(H2O)/iC3(H2O), a ligand to the intergrin CD11b/CD18 on their surface. These mechanisms add further to the understanding of how platelets interact with the complement system and will help us to understand the role of the complement system in cardiovascular disease and thrombotic conditions.
|
|
| 17. |
- Hamad, Osama A., 1978-, et al.
(författare)
-
Non-proteolytically activated C3 promotes binding of activated platelets and platelet-derived microparticles to leukocytes via CD11b/CD18
- 2012
-
Ingår i: Immunobiology. - : Elsevier BV. - 0171-2985 .- 1878-3279. ; 217:11, s. 1191-1191
-
Tidskriftsartikel (refereegranskat)abstract
- Background:We have previously demonstrated that complement component C3 binds to the surface of activated platelets, independent of proteolytic activation. The resulting form of C3, termed C3(H2O), was shown to be a ligand for recombinant CD35 (complement receptor 1, CR1). Previous studies by others have indicated that platelet-leukocyte complex (PLC) formation is dependent on the interaction between platelet exposed P-selectin (CD62P) and its ligand, PSGL-1, on leukocytes. In addition, CD11b/CD18 (Mac-1 or CR3) has been shown to participate in this reaction, but its ligand has not yet been identified.Objective:To test the hypothesis that C3 bound to activated platelets and platelet-derived microparticles (PMPs) can act as a ligand for CD11b/CD18 (CR3) and contribute to PLC formation.Methods and results:Blood cells were depleted of plasma proteins. After extensive washing, C3 was added, and the leukocytes were activated with C5a and the platelets with thrombin receptor-activating peptide (TRAP). PLC formation was detected by flow cytometry (monocytes: CD14+/CD42a+, granulocytes: CD16+/CD42a+). For both granulocytes and monocytes, the addition of C3 significantly enhanced PLC formation. Formation of PLC was inhibited by both anti-P-selectin and anti-CD11b monoclonal antibodies. In addition, PMPs isolated from serum, were found to expose C3(H2O) and bind to leukocytes in a fashion similar to activated platelets.Conclusion:We have identified proteolytically non-activated C3 as a ligand for CD11b in the formation of PLC and possibly the binding of PMPs to leukocytes. This observation most likely has pathophysiological implications for the recently reported links between thrombotic disease and the complement system.
|
|
| 18. |
- Hamad, Osama A, et al.
(författare)
-
Platelets, Complement, and Contact Activation : Partners in inflammation and thrombosis
- 2012
-
Ingår i: Current Topics in Innate Immunity II. - New York, NY : Springer. - 9781461401056 - 9781461401063 ; , s. 185-205
-
Konferensbidrag (refereegranskat)abstract
- Platelet activation during thrombotic events is closely associated with complement and contact system activation, which in turn leads to inflammation . Here we review the interactions between activated platelets and the complement and contact activation systems in clotting blood. Chondroitin sulfate A (CS-A), released from alpha granules during platelet activation, is a potent mediator of crosstalk between platelets and the complement system. CS-A activates complement in the fluid phase, generating anaphylatoxins that mediate leukocyte activation. No complement activation seems to occur on the activated platelet surface, but C3 in the form of C3(H2O) is bound to the surfaces of activated platelets . This finding is consistent with the strong expression of membrane-bound complement regulators present at the platelet surface. CS-A exposed on the activated platelets is to a certain amount responsible for recruiting soluble regulators to the surface. Platelet-bound C3(H2O) acts as a ligand for leukocyte CR1 (CD35), potentially enabling platelet–leukocyte interactions. In addition, platelet activation leads to the activation of contact system enzymes, which are specifically inhibited by antithrombin, rather than by C1INH, as is the case when contact activation is induced by material surfaces. Thus, in addition to their traditional role as initiators of secondary hemostasis, platelets also act as mediators and regulators of inflammation in thrombotic events.
|
|
| 19. |
|
|
| 20. |
- Hendaus, Mohamed A., et al.
(författare)
-
Child abuse and neglect in a rapidly developing country : Parents' perspectives
- 2020
-
Ingår i: Journal of Family Medicine and Primary Care. - : Wolters Kluwer. - 2249-4863 .- 2278-7135. ; 9:6, s. 3053-3059
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To identify parental awareness and knowledge regarding child abuse and neglect in the State of Qatar.Methods: A cross-sectional study using a questionnaire was conducted at Hamad Medical Corporation, the only tertiary pediatric hospital in the State of Qatar at the time of the study. Parents of children of all ages were offered a questionnaire that included demographic details, parental knowledge, and awareness of child abuse and neglect.Results: 300 questionnaires were completed (response rate = 95%). More than 70% of parents were older than 30 years of age, 60% of them were females, and 66% were college graduates. The majority of the participants stated their familiarity about child abuse, and 6% witnessed morbidity or mortality due to child abuse in the society. Despite the identified laws, only 50% of the parents were aware of laws restricting child abuse. In regards to children with special needs, only 16% of the participants agreed that disabled children are at a higher risk of abuse compared to healthy children, while 33% were neutral and 52% disagreed. In addition, one-fifth of the respondents stated that hitting is discipline, while 63% disagreed. Almost one-third of the respondents agreed that hitting hands and buttock or hitting with soft objects is acceptable form of discipline. Unexpectedly, one-quarter of participants stated that it is okay to hit a child as long as no damage incurs. As for verbal abuse, around one-third of parents stated that yelling is not a form of child abuse, and that yelling does not affect growth and development. Comparing both corporal and verbal abuse, approximately 70% of parents stated that yelling is less harmful than hitting. In terms of child neglect, around half of the respondents agreed with the statement "Leaving a child (<5 years) unattended at home is a form of neglect," while 42% were neutral. Finally, approximately 50% of the participants believed that it is okay to depend on nannies in assisting their children in eating and using the bathroom.Conclusion: Parents residing in the State of Qatar believe that they have a good knowledge regarding child abuse and neglect. However, this study shows many deficiencies in parental knowledge of child abuse and neglect. Parents' attitudes and perceptions are considered indispensable targets for community health intervention.
|
|
| 21. |
|
|
| 22. |
- Klapper, Yvonne, et al.
(författare)
-
Mediation of a non-proteolytic activation of complement component C3 by phospholipid vesicles
- 2014
-
Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 35:11, s. 3688-3696
-
Tidskriftsartikel (refereegranskat)abstract
- Liposomes are becoming increasingly important as drug delivery systems, to target a drug to specific cells and tissues and thereby protecting the recipient from toxic effects of the contained drug. Liposome preparations have been described to activate complement. In this study, we have investigated complement activation triggered by neutral dimyristoyl-phosphocholine (DMPC) liposomes in human plasma and whole-blood systems. Incubation in plasma led to the generation of complement activation products (C3a and sC5b-9). Unexpectedly, investigations of surface-bound C3 revealed contact activated, conformationally changed C3 molecules on the liposomes. These changes were characterized by Western blotting with C3 monoclonal antibodies, and by incubating liposomes with purified native C3 and factors I and H. Quartz crystal microbalance analysis confirmed binding of C3 to planar DMPC surfaces. In addition, we demonstrated that DMPC liposomes bound to or were phagocytized by granulocytes in a complement-dependent manner, as evidenced by the use of complement inhibitors. In summary, we have shown that C3 is activated both by convertase-dependent cleavage, preferentially in the fluid phase, by mechanisms which are not well elucidated, and also by contact activation into C3(H2O) on the DMPC surface. In particular, this contact activation has implications for the therapeutic regulation of complement activation during liposome treatment. (C) 2013 Elsevier Ltd. All rights reserved.
|
|
| 23. |
- Knabl, Ludwig, et al.
(författare)
-
Shiga toxin 2a binds antithrombin and heparin, but does not directly activate platelets
- 2018
-
Ingår i: International Journal of Medical Microbiology. - : Elsevier BV. - 1438-4221 .- 1618-0607. ; 308:7, s. 969-976
-
Tidskriftsartikel (refereegranskat)abstract
- Escherichia coli-induced hemolytic uremic syndrome (eHUS) is a life-threatening complication of infection with Shiga toxin (Stx), in particular Stx2a-producing Escherichia coli. Enhanced coagulation activation with formation of microthrombi seems to be a key event in development of eHUS. Platelet activation has been postulated as a possible, but controversially debated mechanism. The present study investigated the effect of Stx2a on plasmatic coagulation and platelets. Binding studies were initially performed with ELISA and co-immunoprecipitation and supported by quartz crystal microbalance with dissipation monitoring (QCM-D). Antithrombin (AT) activity was measured using the automated BCS XP (R) system. ROTEM (R) was used for functional coagulation testing. Platelet binding and activation was studied with FACS and light-transmission aggregometry. We found binding of Stx2a to AT, an important inhibitor of blood coagulation, but only a mild albeit significant reduction of AT activity against FXa in the presence of Stx2a. QCM-D analysis also showed binding of Stx2a to heparin and an impaired binding of AT to Stx2a-bound heparin. ROTEM (R) using Stx2a-treated platelet-poor plasma revealed a significant, but only moderate shortening of clotting time. Neither binding nor activation of platelets by Stx2a could be demonstrated. In summary, data of this study suggest that Stx2a binds to AT, but does not induce major effects on plasmatic coagulation. In addition, no interaction with platelets occurred. The well-known non-beneficial administration of heparin in eHUS patients could be explained by the interaction of Stx2a with heparin.
|
|
| 24. |
|
|
| 25. |
- Kozarcanin, Huda, et al.
(författare)
-
The lectin complement pathway serine proteases (MASPs) represent a possible crossroad between the coagulation and complement systems in thromboinflammation
- 2016
-
Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 14:3, s. 531-545
-
Tidskriftsartikel (refereegranskat)abstract
- The lectin pathway's MASP-1/2 activates coagulation factors but the trigger of the activation is unknown. MASP-1/2 activation was assessed by quantifying complexes between MASPs and antithrombin/C1-inhibitor. Activated platelets and fibrin were demonstrated to activate MASP-1 and MASP-2 both invitro and invivo. These findings may represent a crossroad between the complement and the coagulation systems. Summary Background The activated forms of the complement lectin pathway (LP) proteases MASP-1 and MASP-2 are able to cleave the coagulation factors prothrombin, fibrinogen, factor XIII and thrombin-activatable fibrinolysis inhibitor invitro. In vivo studies also show that MASP-1 is involved in thrombogenesis. Objectives To clarify the not yet identified mechanisms involved in triggering activation of the LP during thrombotic reactions. Methods Novel sandwich-ELISAs for detection of complexes between MASP-1 or MASP-2 and the serpins C1 inhibitor (C1-INH) or antithrombin (AT), were used to specifically detect and quantify the activated forms of MASP-1 and MASP-2. Results Activated platelets were shown by flow cytometry to bind Ficolin-1, -2 and -3 but not MBL, which was associated with activation of MASP-1 and MASP-2. We also demonstrated that fibrin and the plasmin-generated fibrin fragment DD in plasma, bind and activate MASP-1 and MASP-2. As demonstrated by the ELISA and SDS-PAGE/Western blotting, the fibrin-associated activation was reflected in a specific inactivation by AT during clotting without the assistance of heparin. In all other cases the MASPs were, as previously reported, inactivated by C1-INH. In systemic lupus erythematosus patients with thrombotic disease and in polytrauma patients, the levels of activated MASP-1 and MASP-2 in complex with both AT and C1-INH were associated with markers of thrombotic disease and contact/coagulation system activation. Conclusions MASP-1 and MASP-2 are activated during blood clotting. This activation is triggered by activated platelets and by the generation of fibrin during thrombotic reactions invitro and invivo, and may represent a novel activation/amplification mechanism in thromboinflammation.
|
|
| 26. |
|
|
| 27. |
- Moll, Guido, et al.
(författare)
-
Are Therapeutic Human Mesenchymal Stromal Cells Compatible with Human Blood?
- 2012
-
Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 30:7, s. 1565-1574
-
Tidskriftsartikel (refereegranskat)abstract
- Multipotent mesenchymal stromal cells (MSCs) are tested in numerous clinical trials. Questions have been raised concerning fate and function of these therapeutic cells after systemic infusion. We therefore asked whether culture-expanded human MSCs elicit an innate immune attack, termed instant blood-mediated inflammatory reaction (IBMIR), which has previously been shown to compromise the survival and function of systemically infused islet cells and hepatocytes. We found that MSCs expressed hemostatic regulators similar to those produced by endothelial cells but displayed higher amounts of prothrombotic tissue/stromal factors on their surface, which triggered the IBMIR after blood exposure, as characterized by formation of blood activation markers. This process was dependent on the cell dose, the choice of MSC donor, and particularly the cell-passage number. Short-term expanded MSCs triggered only weak blood responses in vitro, whereas extended culture and coculture with activated lymphocytes increased their prothrombotic properties. After systemic infusion to patients, we found increased formation of blood activation markers, but no formation of hyperfibrinolysis marker D-dimer or acute-phase reactants with the currently applied dose of 1.0-3.0 x 10(6) cells per kilogram. Culture-expanded MSCs trigger the IBMIR in vitro and in vivo. Induction of IBMIR is dose-dependent and increases after prolonged ex vivo expansion. Currently applied doses of low-passage clinical-grade MSCs elicit only minor systemic effects, but higher cell doses and particularly higher passage cells should be handled with care. This deleterious reaction can compromise the survival, engraftment, and function of these therapeutic cells.
|
|
| 28. |
- Moll, Guido, et al.
(författare)
-
Different Procoagulant Activity of Therapeutic Mesenchymal Stromal Cells Derived from Bone Marrow and Placental Decidua
- 2015
-
Ingår i: Stem Cells and Development. - : Mary Ann Liebert Inc. - 1547-3287 .- 1557-8534. ; 28:S2, s. 50-51
-
Tidskriftsartikel (refereegranskat)abstract
- While therapeutic mesenchymal stromal/stem cells (MSCs) have usually been obtained from bone marrow, perinatal tissues have emerged as promising new sources of cells for stromal cell therapy. In this study, we present a first safety follow-up on our clinical experience with placenta-derived decidual stromal cells (DSCs), used as supportive immunomodulatory and regenerative therapy for patients with severe complications after allogeneic hematopoietic stem cell transplantation (HSCT). We found that DSCs are smaller, almost half the volume of MSCs, which may favor microvascular passage. DSCs also show different hemocompatibility, with increased triggering of the clotting cascade after exposure to human blood and plasma in vitro. After infusion of DSCs in HSCT patients, we observed a weak activation of the fibrinolytic system, but the other blood activation markers remained stable, excluding major adverse events. Expression profiling identified differential levels of key factors implicated in regulation of hemostasis, such as a lack of prostacyclin synthase and increased tissue factor expression in DSCs, suggesting that these cells have intrinsic blood-activating properties. The stronger triggering of the clotting cascade by DSCs could be antagonized by optimizing the cell graft reconstitution before infusion, for example, by use of low-dose heparin anticoagulant in the cell infusion buffer. We conclude that DSCs are smaller and have stronger hemostatic properties than MSCs, thus triggering stronger activation of the clotting system, which can be antagonized by optimizing the cell graft preparation before infusion. Our results highlight the importance of hemocompatibility safety testing for every novel cell therapy product before clinical use, when applied using systemic delivery.
|
|
| 29. |
- Moll, Guido, et al.
(författare)
-
Do ABO Blood Group Antigens Hamper the Therapeutic Efficacy of Mesenchymal Stromal Cells?
- 2014
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1, s. e85040-
-
Tidskriftsartikel (refereegranskat)abstract
- Investigation into predictors for treatment outcome is essential to improve the clinical efficacy of therapeutic multipotent mesenchymal stromal cells (MSCs). We therefore studied the possible harmful impact of immunogenic ABO blood groups antigens - genetically governed antigenic determinants - at all given steps of MSC-therapy, from cell isolation and preparation for clinical use, to final recipient outcome. We found that clinical MSCs do not inherently express or upregulate ABO blood group antigens after inflammatory challenge or in vitro differentiation. Although antigen adsorption from standard culture supplements was minimal, MSCs adsorbed small quantities of ABO antigen from fresh human AB plasma (ABP), dependent on antigen concentration and adsorption time. Compared to cells washed in non-immunogenic human serum albumin (HSA), MSCs washed with ABP elicited stronger blood responses after exposure to blood from healthy O donors in vitro, containing high titers of ABO antibodies. Clinical evaluation of hematopoietic stem cell transplant (HSCT) recipients found only very low titers of anti-A/B agglutination in these strongly immunocompromised patients at the time of MSC treatment. Patient analysis revealed a trend for lower clinical response in blood group O recipients treated with ABP-exposed MSC products, but not with HSA-exposed products. We conclude, that clinical grade MSCs are ABO-neutral, but the ABP used for washing and infusion of MSCs can contaminate the cells with immunogenic ABO substance and should therefore be substituted by non-immunogenic HSA, particularly when cells are given to immunocompentent individuals.
|
|
| 30. |
- Moll, Guido, et al.
(författare)
-
Do Cryopreserved Mesenchymal Stromal Cells Display Impaired Immunomodulatory and Therapeutic Properties?
- 2014
-
Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 32:9, s. 2430-2442
-
Tidskriftsartikel (refereegranskat)abstract
- We have recently reported that therapeutic mesenchymal stromal cells (MSCs) have low engraftment and trigger the instant blood mediated inflammatory reaction (IBMIR) after systemic delivery to patients, resulting in compromised cell function. In order to optimize the product, we compared the immunomodulatory, blood regulatory, and therapeutic properties of freeze-thawed and freshly harvested cells. We found that freeze-thawed MSCs, as opposed to cells harvested from continuous cultures, have impaired immunomodulatory and blood regulatory properties. Freeze-thawed MSCs demonstrated reduced responsiveness to proinflammatory stimuli, an impaired production of anti-inflammatory mediators, increased triggering of the IBMIR, and a strong activation of the complement cascade compared to fresh cells. This resulted in twice the efficiency in lysis of thawed MSCs after 1 hour of serum exposure. We found a 50% and 80% reduction in viable cells with freshly detached as opposed to thawed in vitro cells, indicating a small benefit for fresh cells. In evaluation of clinical response, we report a trend that fresh cells, and cells of low passage, demonstrate improved clinical outcome. Patients treated with freshly harvested cells in low passage had a 100% response rate, twice the response rate of 50% observed in a comparable group of patients treated with freeze-thawed cells at higher passage. We conclude that cryobanked MSCs have reduced immunomodulatory and blood regulatory properties directly after thawing, resulting in faster complement-mediated elimination after blood exposure. These changes seem to be paired by differences in therapeutic efficacy in treatment of immune ailments after hematopoietic stem cell transplantation.
|
|
| 31. |
- Nilsson, Bo, et al.
(författare)
-
C3 and C4 are strongly related to adipose tissue variables and cardiovascular risk factors
- 2014
-
Ingår i: European Journal of Clinical Investigation. - : John Wiley & Sons. - 0014-2972 .- 1365-2362. ; 44:6, s. 587-596
-
Tidskriftsartikel (refereegranskat)abstract
- Background In several reports, C3 and C4 have been linked to diabetes and cardiovascular disease (CVD). Here, we investigate this link and the degree of C3 activation in elderly individuals. Methods In this study, C3 and C4 and the activation fragment C3a-desArg were analysed in 1016 subjects aged 70, in which blood pressure, lipid variables and fasting blood glucose were assessed. Results C3 levels were related to all the investigated classical cardiovascular risk factors and the metabolic syndrome (BMI, waist circumference, fat distribution, blood pressure, blood glucose levels, TG) except total cholesterol and LDL cholesterol in a highly significant fashion (Spearman up to 0,5; P<0.0001). C4 and C3a-desArg were associated in the same fashion but less significantly, while the ratios C4/C3 or C3a-desArg/C3 were not, indicating thatthe association was not directly related to complement activation. The levels C3 and to a lesser degree C4 and C3a-desArg were associated particularly with CRP, but also with E-selectin and ICAM-1. In addition, C3 and C4 levels were shown to decline significantly in 15 female subjects enrolled in a weight-reduction programme over 4 months. Conclusion A strong relation between C3, C4 and C3a-desArg levels, adipose tissue and risk factors of CVD was established. The data support that theadipose tissue produces complement components and generates initiators of inflammation, such as C3a and C5a, able to trigger a cyto/chemokine response, in proportion to the amount of adipose tissue. This corroborates the concept that complement contributes to the low-grade inflammation associated with obesity.
|
|
| 32. |
|
|
| 33. |
- Nilsson Ekdahl, Kristina, et al.
(författare)
-
Contact (kallikrein/kinin) system activation in whole human blood induced by low concentrations of α-Fe2O3 nanoparticles
- 2018
-
Ingår i: Nanomedicine. - : Elsevier. - 1549-9634 .- 1549-9642. ; 14:3, s. 735-744
-
Tidskriftsartikel (refereegranskat)abstract
- Iron-oxide nanoparticles (NPs) generated by environmental events are likely to represent health problems. α-Fe2O3 NPs were synthesized, characterized and tested in a model for toxicity utilizing human whole blood without added anticoagulant. MALDI-TOF of the corona was performed and activation markers for plasma cascade systems (complement, contact and coagulation systems), platelet consumption and release of growth factors, MPO, and chemokine/cytokines from blood cells were analyzed. The coronas formed on the pristine α-Fe2O3 NPs contained contact system proteins and they induced massive activation of the contact (kinin/kallikrein) system, as well as thrombin generation, platelet activation, and release of two pro-angiogeneic growth factors: platelet-derived growth factor and vascular endothelial growth factor, whereas complement activation was unaffected. The α-Fe2O3 NPs exhibited a noticeable toxicity, with kinin/kallikreinactivation, which may be associated with hypotension and long-term angiogenesis in vivo, with implications for cancer, arteriosclerosis and pulmonary disease.
|
|
| 34. |
- Nilsson Ekdahl, Kristina, et al.
(författare)
-
Dangerous liaisons : complement, coagulation, and kallikrein/kinin cross-talk act as a linchpin in the events leading to thromboinflammation
- 2016
-
Ingår i: Immunological Reviews. - : Wiley. - 0105-2896 .- 1600-065X. ; 274:1, s. 245-269
-
Forskningsöversikt (refereegranskat)abstract
- Innate immunity is fundamental to our defense against microorganisms. Physiologically, the intravascular innate immune system acts as a purging system that identifies and removes foreign substances leading to thromboinflammatory responses, tissue remodeling, and repair. It is also a key contributor to the adverse effects observed in many diseases and therapies involving biomaterials and therapeutic cells/organs. The intravascular innate immune system consists of the cascade systems of the blood (the complement, contact, coagulation, and fibrinolytic systems), the blood cells (polymorphonuclear cells, monocytes, platelets), and the endothelial cell lining of the vessels. Activation of the intravascular innate immune system in vivo leads to thromboinflammation that can be activated by several of the system's pathways and that initiates repair after tissue damage and leads to adverse reactions in several disorders and treatment modalities. In this review, we summarize the current knowledge in the field and discuss the obstacles that exist in order to study the cross-talk between the components of the intravascular innate immune system. These include the use of purified in vitro systems, animal models and various types of anticoagulants. In order to avoid some of these obstacles we have developed specialized human whole blood models that allow investigation of the cross-talk between the various cascade systems and the blood cells. We in particular stress that platelets are involved in these interactions and that the lectin pathway of the complement system is an emerging part of innate immunity that interacts with the contact/coagulation system. Understanding the resulting thromboinflammation will allow development of new therapeutic modalities.
|
|
| 35. |
- Nilsson Ekdahl, Kristina, et al.
(författare)
-
Evaluation of the blood compatibility of materials, cells and tissues: Basic concepts, test models and practical guidelines
- 2013
-
Ingår i: Complement Therapeutics. - Boston, MA : Springer. - 9781461441175 - 9781461441182 ; 735, s. 257-270
-
Bokkapitel (refereegranskat)abstract
- Medicine today uses a wide range of biomaterials, most of which make contact with blood permanently or transiently upon implantation. Contact between blood and nonbiological materials or cells or tissue of nonhematologic origin initiates activation of the cascade systems (complement, contact activation/coagulation) of the blood, which induces platelet and leukocyte activation.Although substantial progress regarding biocompatibility has been made, many materials and medical treatment procedures are still associated with severe side effects. Therefore, there is a great need for adequate models and guidelines for evaluating the blood compatibility of biomaterials. Due to the substantial amount of cross talk between the different cascade systems and cell populations in the blood, it is advisable to use an intact system for evaluation.Here, we describe three such in vitro models for the evaluation of the biocompatibility of materials and therapeutic cells and tissues. The use of different anticoagulants and specific inhibitors in order to be able to dissect interactions between the different cascade systems and cells of the blood is discussed. In addition, we describe two clinically relevant medical treatment modalities, the integration of titanium implants and transplantation of islets of Langerhans to patients with type 1 diabetes, whose mechanisms of action we have addressed using these in vitro models.
|
|
| 36. |
- Speth, Cornelia, et al.
(författare)
-
Complement and platelets : Mutual interference in the immune network
- 2015
-
Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 67:1, s. 108-118
-
Forskningsöversikt (refereegranskat)abstract
- In recent years, the view of platelets has changed from mere elements of hemostasis to immunological multitaskers. They are connected in manifold ways to other cellular and humoral components of the immune network, one of which is the complement system, a potent player in soluble innate immunity. Our article reviews the crucial and complex interplay between platelets and complement, focusing on mutual regulation of these two interaction partners by their respective molecular mechanisms. Furthermore, the putative relevance of these processes to infectious diseases, inflammatory conditions, and autoimmune disorders, as well as the treatment of patients with biomaterials is highlighted. (C) 2015 Elsevier Ltd. All rights reserved.
|
|
| 37. |
- Thulin, Åsa, et al.
(författare)
-
Activated platelets provide a functional microenvironment for the antiangiogenic fragment of histidine-rich glycoprotein
- 2009
-
Ingår i: Molecular Cancer Research. - 1541-7786 .- 1557-3125. ; 7:11, s. 1792-1802
-
Tidskriftsartikel (refereegranskat)abstract
- The angiogenesis inhibitor histidine-rich glycoprotein (HRG) constitutes one of several examples of molecules regulating both angiogenesis and hemostasis. The antiangiogenic properties of HRG are mediated via its proteolytically released histidine- and proline-rich (His/Pro-rich) domain.Using a combination of immunohistochemistry and massspectrometry, we here provide biochemical evidence for thepresence of a proteolytic peptide, corresponding to the antiangiogenic domain of HRG, in vivo in human tissue. This finding supports a role for HRG as an endogenous regulator of angiogenesis. Interestingly, the His/Pro-rich peptide bound to the vessel wall in tissue from cancer patients but not to the vasculature in tissue from healthy persons.Moreover, the His/Pro-rich peptide was found in close association with platelets. Relesate from in vitro–activated platelets promoted binding of the His/Pro-rich domain of HRG to endothelial cells, an effect mediated by Zn2+.Previous studies have shown that zinc-dependent bindingof the His/Pro-rich domain of HRG to heparan sulfate on endothelial cells is required for inhibition of angiogenesis.We describe a novel mechanism to increase the local concentration and activity of an angiogenesis inhibitor,which may reflect a host response to counteract angiogenesis during pathologic conditions. Our finding that tumor angiogenesis is elevated in HRG-deficient mice supports this conclusion.
|
|
