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- Brandwijk, Ricardo J. M. G. E., et al.
(författare)
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Pitfalls in complement analysis : A systematic literature review of assessing complement activation
- 2022
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background: The complement system is an essential component of our innate defense and plays a vital role in the pathogenesis of many diseases. Assessment of complement activation is critical in monitoring both disease progression and response to therapy. Complement analysis requires accurate and standardized sampling and assay procedures, which has proven to be challenging. Objective: We performed a systematic analysis of the current methods used to assess complement components and reviewed whether the identified studies performed their complement measurements according to the recommended practice regarding pre-analytical sample handling and assay technique. Results are supplemented with own data regarding the assessment of key complement biomarkers to illustrate the importance of accurate sampling and measuring of complement components. Methods: A literature search using the Pubmed/MEDLINE database was performed focusing on studies measuring the key complement components C3, C5 and/or their split products and/or the soluble variant of the terminal C5b-9 complement complex (sTCC) in human blood samples that were published between February 2017 and February 2022. The identified studies were reviewed whether they had used the correct sample type and techniques for their analyses. Results: A total of 92 out of 376 studies were selected for full-text analysis. Forty-five studies (49%) were identified as using the correct sample type and techniques for their complement analyses, while 25 studies (27%) did not use the correct sample type or technique. For 22 studies (24%), it was not specified which sample type was used. Conclusion: A substantial part of the reviewed studies did not use the appropriate sample type for assessing complement activation or did not mention which sample type was used. This deviation from the standardized procedure can lead to misinterpretation of complement biomarker levels and hampers proper comparison of complement measurements between studies. Therefore, this study underlines the necessity of general guidelines for accurate and standardized complement analysis
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- Flockhart, Mikael, et al.
(författare)
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Glucosinolate-rich broccoli sprouts protect against oxidative stress and improve adaptations to intense exercise training.
- 2023
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Ingår i: Redox Biology. - : Elsevier. - 2213-2317. ; 67
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Tidskriftsartikel (refereegranskat)abstract
- Oxidative stress plays a vital role for the adaptive responses to physical training. However, excessive oxidative stress can precipitate cellular damage, necessitating protective mechanisms to mitigate this effect. Glucosinolates, found predominantly in cruciferous vegetables, can be converted into isothiocyanates, known for their antioxidative properties. These compounds activate crucial antioxidant defence pathways and support mitochondrial function and protein integrity under oxidative stress, in both Nrf2-dependent and independent manners. We here administered glucosinolate-rich broccoli sprouts (GRS), in a randomized double-blinded cross-over fashion to 9 healthy subjects in combination with daily intense exercise training for 7 days. We found that exercise in combination with GRS significantly decreased the levels of carbonylated proteins in skeletal muscle and the release of myeloperoxidase into blood. Moreover, it lowered lactate accumulation during submaximal exercise, and attenuated the severe nocturnal hypoglycaemic episodes seen during the placebo condition. Furthermore, GRS in combination with exercise improved physical performance, which was unchanged in the placebo condition.
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- Thomas, Anub Mathew, et al.
(författare)
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Combined Inhibition of C5 and CD14 Attenuates Systemic Inflammation in a Piglet Model of Meconium Aspiration Syndrome.
- 2018
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Ingår i: Neonatology. - : S. Karger. - 1661-7800 .- 1661-7819. ; 113:4, s. 322-330
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Meconium aspiration syndrome (MAS) is a severe lung condition affecting newborns and it can lead to a systemic inflammatory response. We previously documented complement activation and cytokine release in a piglet MAS model. Additionally, we showed ex vivo that meconium-induced inflammation was dependent on complement and Toll-like receptors.OBJECTIVES: To assess the efficacy of the combined inhibition of complement (C5) and CD14 on systemic inflammation induced in a forceful piglet MAS model.METHODS: Thirty piglets were randomly allocated to a treatment group receiving the C5-inhibitor SOBI002 and anti-CD14 (n = 15) and a nontreated control group (n = 15). MAS was induced by intratracheal meconium instillation, and the piglets were observed for 5 h. Complement, cytokines, and myeloperoxidase (MPO) were measured by ELISA.RESULTS: SOBI002 ablated C5 activity and the formation of the terminal complement complex in vivo. The combined inhibition attenuated the inflammasome cytokines IL-1β and IL-6 by 60 (p = 0.029) and 44% (p = 0.01), respectively, and also MPO activity in the bronchoalveolar fluid by 42% (p = 0.017). Ex vivo experiments in human blood revealed that the combined regimen attenuated meconium-induced MPO release by 64% (p = 0.008), but there was only a negligible effect with single inhibition, indicating a synergic cross-talk between the key molecules C5 and CD14.CONCLUSION: Combined inhibition of C5 and CD14 attenuates meconium-induced inflammation in vivo and this could become a future therapeutic regimen for MAS.
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- Andersson, Linnea, et al.
(författare)
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Storage of Transfusion Platelet Concentrates is Associated with Complement Activation and Reduced Ability of Platelets to Respond to Protease-Activated Receptor-1 and Thromboxane A2 Receptor
- 2024
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 25:2
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Tidskriftsartikel (refereegranskat)abstract
- Platelet activation and the complement system are mutually dependent. Here, we investigated the effects of storage time on complement activation and platelet function in routinely produced platelet concentrates. The platelet concentrates (n = 10) were stored at 22 degrees C for seven days and assessed daily for complement and platelet activation markers. Additionally, platelet function was analyzed in terms of their responsiveness to protease-activated receptor-1 (PAR-1) and thromboxane A2 receptor (TXA(2)R) activation and their capacity to adhere to collagen. Complement activation increased over the storage period for all analyzed markers, including the C1rs/C1-INH complex (fold change (FC) = 1.9; p < 0.001), MASP-1/C1-INH complex (FC = 2.0; p < 0.001), C4c (FC = 1.8, p < 0.001), C3bc (FC = 4.0; p < 0.01), and soluble C5b-9 (FC = 1.7, p < 0.001). Furthermore, the levels of soluble platelet activation markers increased in the concentrates over the seven-day period, including neutrophil-activating peptide-2 (FC = 2.5; p < 0.0001), transforming growth factor beta 1 (FC = 1.9; p < 0.001) and platelet factor 4 (FC = 2.1; p < 0.0001). The ability of platelets to respond to activation, as measured by surface expression of CD62P and CD63, decreased by 19% and 24% (p < 0.05) for PAR-1 and 69-72% (p < 0.05) for TXA(2)R activation, respectively, on Day 7 compared to Day 1. The extent of platelet binding to collagen was not significantly impaired during storage. In conclusion, we demonstrated that complement activation increased during the storage of platelets, and this correlated with increased platelet activation and a reduced ability of the platelets to respond to, primarily, TXA(2)R activation.
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- Berg, Aase, et al.
(författare)
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Complement Activation Correlates With Disease Severity and Contributes to Cytokine Responses in Plasmodium falciparum Malaria
- 2015
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Ingår i: The Internet Journal of Infectious Diseases. - : Oxford University Press (OUP). - 1528-8366 .- 0022-1899 .- 1537-6613. ; 212:11, s. 1835-1840
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Tidskriftsartikel (refereegranskat)abstract
- The impact of complement activation and its possible relation to cytokine responses during malaria pathology was investigated in plasma samples from patients with confirmed Plasmodium falciparum malaria and in human whole-blood specimens stimulated with malaria-relevant agents ex vivo. Complement was significantly activated in the malaria cohort, compared with healthy controls, and was positively correlated with disease severity and with certain cytokines, in particular interleukin 8 (IL-8)/CXCL8. This was confirmed in ex vivo-stimulated blood specimens, in which complement inhibition significantly reduced IL-8/CXCL8 release. P. falciparum malaria is associated with systemic complement activation and complement-dependent release of inflammatory cytokines, of which IL-8/CXCL8 is particularly prominent.
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- Gerogianni, Alexandra, et al.
(författare)
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Heme Interferes With Complement Factor I-Dependent Regulation by Enhancing Alternative Pathway Activation
- 2022
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Hemolysis, as a result of disease or exposure to biomaterials, is characterized by excess amounts of cell-free heme intravascularly and consumption of the protective heme-scavenger proteins in plasma. The liberation of heme has been linked to the activation of inflammatory systems, including the complement system, through alternative pathway activation. Here, we investigated the impact of heme on the regulatory function of the complement system. Heme dose-dependently inhibited factor I-mediated degradation of soluble and surface-bound C3b, when incubated in plasma or buffer with complement regulatory proteins. Inhibition occurred with factor H and soluble complement receptor 1 as co-factors, and the mechanism was linked to the direct heme-interaction with factor I. The heme-scavenger protein hemopexin was the main contaminant in purified factor I preparations. This led us to identify that hemopexin formed a complex with factor I in normal human plasma. These complexes were significantly reduced during acute vasoocclusive pain crisis in patients with sickle cell disease, but the complexes were normalized at their baseline outpatient clinic visit. Hemopexin exposed a protective function of factor I activity in vitro, but only when it was present before the addition of heme. In conclusion, we present a mechanistic explanation of how heme promotes uncontrolled complement alternative pathway amplification by interfering with the regulatory capacity of factor I. Reduced levels of hemopexin and hemopexin-factor I complexes during an acute hemolytic crisis is a risk factor for heme-mediated factor I inhibition.
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- Gerogianni, Alexandra, 1993-
(författare)
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The role of the thromboinflammatory response under hemolytic conditions : pathophysiological mechanisms and therapeutic inhibition
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In blood circulation, the complement and the coagulation cascades, together with platelets and endothelial cells form a complex network of crosstalk. When dysregulated, these interactions can lead to inflammation in combination with thrombosis (thromboinflammation) and the manifestation of pathophysiological complications. As complement activation and thromboinflammation are often associated with intravascular hemolysis, e.g., sickle cell disease (SCD), we aimed to study these reactions in relation to heme, a product of hemolysis. Furthermore, our goal was to evaluate whether exposure to biomaterials results in hemolysis-induced thromboinflammation, and to examine the potential of complement inhibition.Our findings show that heme could lead to a significant thromboinflammatory response in our in vitro whole blood model, as seen by complement-, cell- and coagulation- activation, as well as increased cytokine secretion. Inflammation, including complement activation, was also linked with increased heme concentrations in vivo in hemolytic disease in SCD patients. The mechanism of action was attributed to uncontrolled alternative pathway (AP) activation, as heme was shown to bind and inhibit the main AP regulator, factor I, resulting in increased concentrations of fluid phase and surface-bound C3b.Moreover, administration of iron oxide nanoparticles (IONPs) in vitro and implantation of left ventricular assist device (LVAD) in vivo were monitored and correlated with increased hemolytic, e.g., heme, and thromboinflammatory markers, e.g., complement-, endothelial cell- and platelet- activation. Targeting complement components C5 and C3 in vitro was shown overall beneficial in the presence of heme or IONPs respectively. In our settings, the majority of the thromboinflammatory markers measured were successfully attenuated, indicating that complement fuels this response.In conclusion, the results in this thesis stress that heme-induced complement activation is an important player in thromboinflammation. In addition, we propose that complement inhibition can be used as a therapeutic approach in hemolytic conditions and as a strategy to enhance biomaterials’ biocompatibility.
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