Natural immunoglobulin M-based delivery of a complement alternative pathway inhibitor in mouse models of retinal degeneration

• Published in: Experimental eye research 2021-06, Vol.207, p.108583-108583, Article 108583
• Main Authors: Annamalai, Balasubramaniam, Parsons, Nathaniel, Nicholson, Crystal, Joseph, Kusumam, Coughlin, Beth, Yang, Xiaofeng, Jones, Bryan W., Tomlinson, Stephen, Rohrer, Bärbel
• Format: Article
• Language: English
• Subjects: Alternative pathway inhibitor; Animals; Antibodies, Monoclonal - therapeutic use; Blotting, Western; Cell Line; Cell- and Tissue-Based Therapy - methods; Choroidal neovascularization; Choroidal Neovascularization - diagnostic imaging; Choroidal Neovascularization - immunology; Choroidal Neovascularization - therapy; Complement C3 - antagonists & inhibitors; Complement C3 - genetics; Complement Inactivating Agents - therapeutic use; Complement Pathway, Alternative - drug effects; Complement system; Disease Models, Animal; Drug Delivery Systems; Encapsulated ARPE-19 cells; Immunoglobulin M - immunology; Male; Mice; Mice, Inbred C57BL; Natural antibody-mediated targeting; Recombinant Fusion Proteins; Retinal Degeneration - diagnostic imaging; Retinal Degeneration - immunology; Retinal Degeneration - therapy; Retinal Pigment Epithelium - metabolism; Smoke-induced ocular pathology; Tomography, Optical Coherence; Transfection
• ISSN: 0014-4835; 1096-0007
• DOI: 10.1016/j.exer.2021.108583

Age-related macular degeneration is a slowly progressing disease. Studies have tied disease risk to an overactive complement system. We have previously demonstrated that pathology in two mouse models, the choroidal neovascularization (CNV) model and the smoke-induced ocular pathology (SIOP) model, can be reduced by specifically inhibiting the alternative complement pathway (AP). Here we report on the development of a novel injury-site targeted inhibitor of the alternative pathway, and its characterization in models of retinal degeneration. Expression of the danger associated molecular pattern, a modified annexin IV, in injured ARPE-19 cells was confirmed by immunohistochemistry and complementation assays using B4 IgM mAb. Subsequently, a construct was prepared consisting of B4 single chain antibody (scFv) linked to a fragment of the alternative pathway inhibitor, fH (B4-scFv-fH). ARPE-19 cells stably expressing B4-scFv-fH were microencapsulated and administered intravitreally or subcutaneously into C57BL/6 J mice, followed by CNV induction or smoke exposure. Progression of CNV was analyzed using optical coherence tomography, and SIOP using structure-function analyses. B4-scFv-fH targeting and AP specificity was assessed by Western blot and binding experiments. B4-scFv-fH was secreted from encapsulated RPE and inhibited complement in RPE monolayers. B4-scFv-fH capsules reduced CNV and SIOP, and western blotting for breakdown products of C3α, IgM and IgG confirmed a reduction in complement activation and antibody binding in RPE/choroid. Data supports a role for natural antibodies and neoepitope expression in ocular disease, and describes a novel strategy to target AP-specific complement inhibition to diseased tissue in the eye. AMD risk is tied to an overactive complement system, and ocular injury is reduced by alternative pathway (AP) inhibition in experimental models. We developed a novel inhibitor of the AP that targets an injury-specific danger associated molecular pattern, and characterized it in disease models. •AMD risk is tied to an overactive complement system, and ocular injury is reduced by alternative pathway (AP) inhibition in experimental models.•We developed a novel AP inhibitor that targets an injury-specific danger associated molecular pattern, and characterized it in disea