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MAP-2:CD55 chimeric construct effectively modulates complement activation
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DOI：10.1096/fj.202300571R.png)
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Abstract
En 中文
The complement system is a complex, tightly regulated protein cascade involved in pathogen defense and the pathogenesis of several diseases. Thus, the development of complement modulators has risen as a potential treatment for complement-driven inflammatory pathologies. The enzymatically inactive MAP-2 has been reported to inhibit the lectin pathway by competing with its homologous serine protease MASP-2. The membrane-bound complement inhibitor CD55 acts on the C3/C5 convertase level. Here, we fused MAP-2 to the four N-terminal domains of CD55 generating a targeted chimeric inhibitor to modulate complement activation at two different levels of the complement cascade. Its biological properties were compared in vitro with the parent molecules. While MAP-2 and CD55 alone showed a minor inhibition of the three complement pathways when co-incubated with serum (IC50(MAP-2+CD55)(1-4) = 60.98, 36.10, and 97.01 nM on the classical, lectin, and alternative pathways, respectively), MAP-2:CD55(1-4) demonstrated a potent inhibitory activity (IC50(MAP-2:CD55)(1-4) = 2.94, 1.76, and 12.86 nM, respectively). This inhibitory activity was substantially enhanced when pre-complexes were formed with the lectin pathway recognition molecule mannose-binding lectin (IC50(MAP-2:CD55)(1-4) = 0.14 nM). MAP-2:CD55(1-4) was also effective at protecting sensitized sheep erythrocytes in a classical hemolytic assay (CH50 = 13.35 nM). Finally, the chimeric inhibitor reduced neutrophil activation in full blood after stimulation with Aspergillus fumigatus conidia, as well as phagocytosis of conidia by isolated activated neutrophils. Our results demonstrate that MAP-2:CD55(1-4) is a potent complement inhibitor reinforcing the idea that engineered fusion proteins are a promising design strategy for identifying and developing drug candidates to treat complement-mediated diseases.
Keywords:
CD55
complement inhibition
complement regulation
lectin pathway
MAP-2
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