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- Georgopoulos, Lindsay J., et al.
(author)
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Preclinical evaluation of innate immunity to baculovirus gene therapy vectors in whole human blood
- 2009
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In: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 46:15, s. 2911-2917
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Journal article (peer-reviewed)abstract
- Interactions of gene therapy vectors with human blood components upon intravenous administration have a significant effect on vector efficacy and patient safety. Here we describe methods to evaluate these interactions and their effects in whole human blood, using baculovirus vectors as a model. Opsonisation of baculovirus particles by binding of IgM and C3b was demonstrated, which is likely to be the cause of the significant blood cell-associated virus that was detected. Preventing formation of the complement C5b-9 (membrane attack) complex maintained infectivity of baculovirus particles as shown by studying the effects of two specific complement inhibitors, Compstatin and a C5a receptor antagonist. Formation of macroscopic blood clots after 4h was prevented by both complement inhibitors. Pro- and anti-inflammatory cytokines Il-1beta, IL-6, IL-8 and TNF-alpha were produced at variable levels between volunteers and complement inhibitors showed patient-specific effects on cytokine levels. Whilst both complement inhibitors could play a role in protecting patients from aggressive inflammatory reactions, only Compstatin maintained virus infectivity. We conclude that this ex vivo model, used here for the first time with infectious agents, is a valuable tool in evaluating human innate immune responses to gene therapy vectors or to predict the response of individual patients as part of a clinical trial or treatment. The use of complement inhibitors for therapeutic viruses should be considered on a patient-specific basis.
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- Goto, Masafumi, et al.
(author)
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Dissecting the instant blood-mediated inflammatory reaction in islet xenotransplantation
- 2008
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In: Xenotransplantation. - : Wiley. - 0908-665X .- 1399-3089. ; 15:4, s. 225-234
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Journal article (peer-reviewed)abstract
- BACKGROUND: A massive destruction of transplanted tissue occurs immediately following transplantation of pancreatic islets from pig to non-human primates. The detrimental instant blood-mediated inflammatory reaction (IBMIR), triggered by the porcine islets, is a likely explanation for this tissue loss. This reaction may also be responsible for mediating an adaptive immune response in the recipient that requires a heavy immunosuppressive regimen. MATERIALS AND METHODS: Low molecular weight dextran sulfate (LMW-DS) and the complement inhibitor Compstatin were used in a combination of in vitro and in vivo studies designed to dissect the xenogeneic IBMIR in a non-human primate model of pancreatic islet transplantation. Adult porcine islets (10,000 IEQs/kg) were transplanted intraportally into three pairs of cynomolgus monkeys that had been treated with LMW-DS or heparin (control), and the effects on the IBMIR were characterized. Porcine islets were also incubated in human blood plasma in vitro to assess complement inhibition by LMW-DS and Compstatin. RESULTS: Morphological scoring and immunohistochemical staining revealed that the severe islet destruction and macrophage, neutrophilic granulocyte, and T-cell infiltration observed in the control (heparin-treated) animals were abrogated in the LMW-DS-treated monkeys. Both coagulation and complement activation were significantly reduced in monkeys treated with LMW-DS, but IgM and complement fragments were still found on the islet surface. This residual complement activation could be inhibited by Compstatin in vitro. CONCLUSIONS: The xenogeneic IBMIR in this non-human primate model is characterized by an immediate binding of antibodies that triggers deleterious complement activation and a subsequent clotting reaction that leads to further complement activation. The effectiveness of LMW-DS (in vivo and in vitro) and Compstatin (in vitro) in inhibiting this IBMIR provides the basis for a protocol that can be used to abrogate the IBMIR in pig-human clinical islet transplantation.
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- Mangsbo, Sara M, 1981-, et al.
(author)
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Complement Activation by CpG in a Human Whole Blood Loop System : Mechanisms and Immunomodulatory Effects
- 2009
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In: Journal of Immunology. - : The American Association of Immunologists, Inc.. - 0022-1767 .- 1550-6606. ; 183:10, s. 6724-6732
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Journal article (peer-reviewed)abstract
- Phosphorothioate oligodeoxynucleotides can activate complement, and experimental murine studies have revealed differential effects upon simultaneous TLR stimulation and complement activation compared with either event alone. We set out to investigate the immune stimulatory effects of CpG 2006 in fresh non-anticoagulated human blood with or without presence of active complement. We also sought to elucidate the mechanism behind complement activation upon stimulation with phosphorothioate CpG 2006. In a human blood loop system, both backbone and sequence-specific effects by CpG were counteracted by selective inhibition of C3. Furthermore, DNA backbone-mediated CD40 and CD83 expression on monocytes and sequence-specific IL-6 and TNF production were reduced by complement inhibition. CpG-induced complement activation occurred via either the classical or the alternative pathway and deposits of both IgM and properdin, two activators of complement, were detected on CpG after incubation with EDTA plasma. Quartz crystal microbalance with dissipation monitoring demonstrated alternative pathway convertase build-up onto CpG as a likely pathway to initiate and sustain complement activation. Specific inhibition of C3 suppressed CpG 2006 uptake into monocytes indicating that C3 fragments are involved in CpG internalization. The interplay between complement and TLR9 signaling demonstrated herein warrants further investigation.
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| 7. |
- Markiewski, Maciej M., et al.
(author)
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Complement and coagulation : strangers or partners in crime?
- 2007
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In: Trends in immunology. - : Elsevier BV. - 1471-4906 .- 1471-4981. ; 28:4, s. 184-192
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Research review (peer-reviewed)abstract
- The convergence between complement and the clotting system extends far beyond the chemical nature of the complement and coagulation components, both of which form proteolytic cascades. Complement effectors directly enhance coagulation. These effects are supplemented by the interactions of complement with other inflammatory mediators that can increase the thrombogenicity of blood. In addition, complement inhibits anticoagulant factors. The crosstalk between complement and coagulation is also well illustrated by the ability of certain coagulation enzymes to activate complement components. Understanding the interplay between complement and coagulation has fundamental clinical implications in the context of diseases with an inflammatory pathogenesis, in which complement-coagulation interactions contribute to the development of life-threatening complications. Here, we review the interactions of the complement system with hemostasis and their roles in various diseases.
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| 8. |
- Nilsson, Bo, et al.
(author)
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The role of complement in biomaterial-induced inflammation
- 2007
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In: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 44:1-3, s. 82-94
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Journal article (peer-reviewed)abstract
- Biomaterials are regularly used in various types of artificial tissues and organs, such as oxygenators, plasmapheresis equipment, hemodialysers, catheters, prostheses, stents, vascular grafts, miniature pumps, sensors and heart aids. Although progress has been made regarding bioincompatibility, many materials and procedures are associated with side effects, in particular bioincompatibility-induced inflammation, infections and subsequent loss of function. After cardiopulmonary bypass, coagulopathies can occur and lead to cognitive disturbances, stroke and extended hospitalization. Hemodialysis is associated with anaphylatoid reactions that cause whole-body inflammation and may contribute to accelerated arteriosclerosis. Stents cause restenosis and, in severe cases, thrombotic reactions. This situation indicates that there is still a need to try to understand the mechanisms involved in these incompatibility reactions in order to be able to improve the biomaterials and to develop treatments that attenuate the reactions and thereby reduce patients' discomfort, treatment time and cost. This overview deals with the role of complement in the incompatibility reactions that occur when biomaterials come in contact with blood and other body fluids.
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- Tjernberg, Jenny, et al.
(author)
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Acute antibody-mediated complement activation mediates lysis of pancreatic islets cells and may cause tissue loss in clinical islet transplantation
- 2008
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In: Transplantation. - 0041-1337 .- 1534-6080. ; 85:8, s. 1193-1199
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Journal article (peer-reviewed)abstract
- BACKGROUND: Clinical islet transplantation is associated with loss of transplanted islets necessitating tissue from more than one donor to obtain insulin independence. The instant blood-mediated inflammatory reaction (IBMIR) is one explanation to the tissue loss. Complement activation is an important cytotoxic component of the IBMIR, and in the present study, we have investigated this component in detail. METHODS: Isolated human islets were analyzed by large particle flow cytometry and confocal microscopy after incubation in human ABO-compatible hirudin-plasma. RESULTS: After incubation in plasma, the islets bound IgG and IgM, CIq, C4, C3 and C9. The binding of C3b/iC3b was evident already after 5 min. The binding of C3b/iC3b and the generation of C3a and sC5b-9 were inhibited by the complement inhibitor Compstatin. Lysis as reflected by propidium iodide (PI) staining and release of C-peptide was also inhibited by Compstatin. There were significant correlations between IgM/IgG versus C3b/iC3b and between sC5b-9 and C-peptide. CONCLUSION: The conclusion is that complement is activated by natural IgG and IgM antibodies already after 5 min. The complement activation leads to lysis of cells of the pancreatic islets. This very rapid reaction may be an essential entity of the damage induced by the IBMIR in clinical islet transplantation.
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