Application of the C3 inhibitor compstatin in a human whole blood model designed for complement research – 20 years of experience and future perspectives

Mollnes, Tom Eirik; Storm, Benjamin; Brekke, Ole-Lars; Nilsson, Per H.; Lambris, John D.

doi:10.1016/j.smim.2022.101604

Cited by 5 publications

(2 citation statements)

References 89 publications

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“…We first investigated whether SARS‐CoV‐2 could activate complement by inoculating the virus at a multiplicity of infection (MOI) 0.1 and 1.0 in a lepirudin‐anticoagulated human blood model and subsequently measuring plasma C5a with an ELISA. This model simulates a naïve and complete complement system and contains all soluble and membrane‐bound complement factors, receptors and inhibitors, thereby enabling it to detect all pathways of complement activation and their functional consequences 19 Indeed, SARS‐CoV‐2‐inoculated whole blood at MOI 1.0 showed an increase in C5a of 5–10 ng mL −1 and 30–50 ng mL −1 above that in the mock control at 30 min and 24 h, respectively (Figure 1a ). This occurred on the background of the de novo complement activation permitted by lepirudin, as reflected in the increased baseline observed at 24 h following mock infection.…”

Section: Resultsmentioning

confidence: 99%

SARS‐CoV‐2 triggers complement activation through interactions with heparan sulfate

Amarilla

Lee

et al. 2022

Clin & Trans Imm

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Objectives To determine whether SARS‐CoV‐2 can trigger complement activation, the pathways that are involved and the functional significance of the resultant effect. Methods SARS‐CoV‐2 was inoculated into a human lepirudin‐anticoagulated whole blood model, which contains a full repertoire of complement factors and leukocytes that express complement receptors. Complement activation was determined by measuring C5a production with an ELISA, and pretreatment with specific inhibitors was used to identify the pathways involved. The functional significance of this was then assessed by measuring markers of C5a signalling including leukocyte C5aR1 internalisation and CD11b upregulation with flow cytometry. Results SARS‐CoV‐2 inoculation in this whole blood model caused progressive C5a production over 24 h, which was significantly reduced by inhibitors for factor B, C3, C5 and heparan sulfate. However, this phenomenon could not be replicated in cell‐free plasma, highlighting the requirement for cell surface interactions with heparan sulfate. Functional analysis of this phenomenon revealed that C5aR1 signalling and CD11b upregulation in granulocytes and monocytes was delayed and only occurred after 24 h. Conclusion SARS‐CoV‐2 is a noncanonical alternative pathway activator that progressively triggers complement activation through interactions with heparan sulfate.

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Section: Resultsmentioning

confidence: 99%

SARS‐CoV‐2 triggers complement activation through interactions with heparan sulfate

Amarilla

Lee

et al. 2022

Clin & Trans Imm

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“…Different inhibitors were included to selectively block complement activation at various nodes, as well as TLR signaling. For the analysis of inflammatory cytokines, incubation was performed for four hours, since cytokines are in general not pre-formed but require gene transcription and protein translation (109). To study complement activation, incubation took place for 30 minutes for optimal resolution, i.e., be the best signal-to-noise ratio.…”

Section: Whole Blood Modelmentioning

confidence: 99%

The role of the thromboinflammatory response under hemolytic conditions: pathophysiological mechanisms and therapeutic inhibition

Gerogianni¹

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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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Recent developments in C3-targeted complement therapeutics

Mastellos

Lambris²

2022

Seminars in Immunology

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Application of the C3 inhibitor compstatin in a human whole blood model designed for complement research – 20 years of experience and future perspectives

Cited by 5 publications

References 89 publications

SARS‐CoV‐2 triggers complement activation through interactions with heparan sulfate

SARS‐CoV‐2 triggers complement activation through interactions with heparan sulfate

The role of the thromboinflammatory response under hemolytic conditions: pathophysiological mechanisms and therapeutic inhibition

Recent developments in C3-targeted complement therapeutics

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