Novel compstatin family peptides inhibit complement activation by drusen-like deposits in human retinal pigmented epithelial cell cultures

Abstract

We have used a novel human retinal pigmented epithelial (RPE) cell-based model that mimics drusen biogenesis and the pathobiology of age-related macular degeneration to evaluate the efficacy of newly designed peptide inhibitors of the complement system. The peptides belong to the compstatin family and, compared to existing compstatin analogs, have been optimized to promote binding to their target, complement protein C3, and to enhance solubility by improving their polarity/hydrophobicity ratios. Based on analysis of molecular dynamics simulation data of peptide-C3 complexes, novel binding features were designed by introducing intermolecular salt bridge-forming arginines at the N-terminus and at position -1 of N-terminal dipeptide extensions. Our study demonstrates that the RPE cell assay has discriminatory capability for measuring the efficacy and potency of inhibitory peptides in a macular disease environment.

Keywords: AMD; AP; ApoE; C3; C3b; C3c; C5b-9; ELISA; FB; MD; PDB; RP-HPLC; RPE; age-related macular degeneration; alternative pathway of complement activation; apolipoprotein E; complement inhibitors; complement system; complement system protein 3; compstatin family peptides; drusen; enzyme-linked immunosorbent assay; factor B; macular degeneration; molecular dynamics; protein data bank; retinal pigmented epithelium; reversed phase high performance liquid chromatography; the b-fragment of C3; the c-fragment of C3; the membrane attack complex consisting of complement proteins C5b, C6, C7, C8, and C9(n).