Systemic human CR2-targeted complement alternative pathway inhibitor ameliorates mouse laser-induced choroidal neovascularization.
OBJECTIVE
Genetic associations and the presence of complement components within pathological structures of age-related macular degeneration (AMD) have generated the hypothesis that AMD is caused by chronic local complement activation. Since the majority of activity in the common terminal pathway results from engagement of the amplification loop, the alternative pathway has been proposed as a logical therapeutic target. We recently generated a factor H (fH)-based complement inhibitor (CR2-fH) with the capacity to be "targeted" to sites of complement C3 activation. We asked whether the human therapeutic (TT30) is effective in a mouse model of AMD.


METHODS
Choroidal neovascularization (CNV) was induced by argon laser photocoagulation of Bruch's membrane. Every other day, mice received intravenous injections of TT30 or vehicles, and after 6 days, the presence or absence of CNV and CNV-related changes were evaluated. Area of CNV, photoreceptor cell function, gene expression for complement components and cytokines, vascular endothelial growth factor (VEGF) protein levels, and TT30 bioavailability were determined.


RESULTS
CNV development, which has previously been shown to require local complement activation, could be reduced by intravenous TT30 delivery. Specific inhibition of the alternative pathway not only reduced angiogenesis in CNV, but also ameliorated changes in several associated disease-related biomarkers, including diminished retinal function and molecular events known to be involved in AMD such as VEGF production. After intravenous injection, TT30 localized to CNV lesion sites in the retinal pigmented epithelium-choroid.


CONCLUSIONS
Systemic administration of TT30 was found to reduce CNV pathology. These data may open new avenues for novel systemic AMD treatment strategies.
Department of Ophthalmology, Medical University of South Carolina, 167 Ashley Avenue, Charleston, SC 29425, USA. rohrer@musc.edu
Bärbel
B
Rohrer
Beth
B
Coughlin
Mausumi
M
Bandyopadhyay
V Michael
VM
Holers
D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D000818:Animals; D015415:Biomarkers; D020256:Choroidal Neovascularization / Q000473:pathology / Q000517:prevention & control*; D017242:Complement Factor H / Q000096:biosynthesis / Q000627:therapeutic use*; D003170:Complement Pathway, Alternative / Q000187:drug effects*; D004596:Electroretinography; D006801:Humans; D007150:Immunohistochemistry; D007834:Lasers / Q000009:adverse effects*; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D010957:Plasmids; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017464:Receptors, Complement 3d / Q000096:biosynthesis / Q000627:therapeutic use*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000627:therapeutic use*; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis / Q000378:metabolism
D020533:Angiogenesis Inhibitors; D015415:Biomarkers; D008024:Ligands; D012333:RNA, Messenger; D017464:Receptors, Complement 3d; D011993:Recombinant Fusion Proteins; C574810:TT30 fusion protein, human; D042461:Vascular Endothelial Growth Factor A; D017242:Complement Factor H