A humanized antibody that regulates the alternative pathway convertase: potential for therapy of renal disease associated with nephritic factors

Paixao-Cavalcante, Danielle, Torreira, Eva, Lindorfer, Margaret A., Rodriguez de Cordoba, Santiago, Morgan, Bryan ORCID: https://orcid.org/0000-0003-4075-7676, Taylor, Ronald P., Llorca, Oscar and Harris, Claire 2014. A humanized antibody that regulates the alternative pathway convertase: potential for therapy of renal disease associated with nephritic factors. The Journal of Immunology 192 (10) , pp. 4844-4851. 10.4049/jimmunol.1303131

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Abstract

Dysregulation of the complement alternative pathway can cause disease in various organs that may be life-threatening. Severe alternative pathway dysregulation can be triggered by autoantibodies to the C3 convertase, termed nephritic factors, which cause pathological stabilization of the convertase enzyme and confer resistance to innate control mechanisms; unregulated complement consumption followed by deposition of C3 fragments in tissues ensues. The mAb, 3E7, and its humanized derivative, H17, have been shown previously to specifically bind activated C3 and prevent binding of both the activating protein, factor B, and the inhibitor, factor H, which are opposite effects that complicate its potential for therapy. Using ligand binding assays, functional assays, and electron microscopy, we show that these Abs bind C3b via a site that overlaps the binding site on C3 for the Ba domain within factor B, thereby blocking an interaction essential for convertase formation. Both Abs also bind the preformed convertase, C3bBb, and provide powerful inhibition of complement activation by preventing cleavage of C3. Critically, the Abs also bound and inhibited C3 cleavage by the nephritic factor–stabilized convertase. We suggest that by preventing enzyme formation and/or cleavage of C3 to its active downstream fragments, H17 may be an effective therapy for conditions caused by severe dysregulation of the C3 convertase and, in particular, those that involve nephritic factors, such as dense deposit disease.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine Systems Immunity Research Institute (SIURI)
Subjects:	Q Science > QR Microbiology > QR180 Immunology
Publisher:	American Association of Immunologists
ISSN:	0022-1767
Date of Acceptance:	17 March 2014
Last Modified:	31 Oct 2022 08:55
URI:	https://orca.cardiff.ac.uk/id/eprint/79242

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