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- Nilsson, Per H., 1980-, et al.
(author)
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Eculizumab-C5 complexes express a C5a neoepitope in vivo : Consequences for interpretation of patient complement analyses
- 2017
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In: Molecular Immunology. - : Elsevier. - 0161-5890 .- 1872-9142. ; 89, s. 111-114
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Journal article (peer-reviewed)abstract
- The complement system has obtained renewed clinical focus due to increasing number of patients treated with eculizumab, a monoclonal antibody inhibiting cleavage of C5 into C5a and C5b. The FDA approved indications are paroxysmal nocturnal haemoglobinuria and atypical haemolytic uremic syndrome, but many other diseases are candidates for complement inhibition. It has been postulated that eculizumab does not inhibit C5a formation in vivo, in contrast to what would be expected since it blocks C5 cleavage. We recently revealed that this finding was due to a false positive reaction in a C5a assay. In the present study, we identified expression of a neoepitope which was exposed on C5 after binding to eculizumab in vivo. By size exclusion chromatography of patient serum obtained before and after infusion of eculizumab, we document that the neoepitope was exposed in the fractions containing the eculizumab-C5 complexes, being positive in this actual C5a assay and negative in others. Furthermore, we confirmed that it was the eculizumab-C5 complexes that were detected in the C5a assay by adding an anti-IgG4 antibody as detection antibody. Competitive inhibition by anti-C5 antibodies localized the epitope to the C5a moiety of C5. Finally, acidification of C5, known to alter C5 conformation, induced a neoepitope reacting identical to the one we explored, in the C5a assays. These data are important for interpretation of complement analyses in patients treated with eculizumab.
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- Thomas, Anub Mathew, et al.
(author)
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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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In: Neonatology. - : S. Karger. - 1661-7800 .- 1661-7819. ; 113:4, s. 322-330
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Journal article (peer-reviewed)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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