Macrophage depletion inhibits experimental choroidal neovascularization.
OBJECTIVE
To investigate the role of macrophages in the development of laser-induced choroidal neovascularization (CNV) by selective depletion with liposomal clodronate (Cl(2)MDP-LIP).


METHODS
Laser photocoagulation was used to induce CNV in wild-type C57BL/6J mice. Animals were treated with intravenous (IV) and/or subconjunctival (SC) Cl(2)MDP-LIP or PBS-LIP at the following time points: 2 days before, immediately after, 2 days before and immediately after, or 2 days after laser injury. CNV responses were compared on the basis of en masse volumetric measurements and fluorescein angiography after laser photocoagulation. Macrophages were identified by immunostaining for F4/80, and vascular endothelial growth factor (VEGF) expression was quantified by ELISA.


RESULTS
Macrophages invaded the site of laser injury within 1 day of photocoagulation and peaked at 3 days. IV Cl(2)MDP-LIP significantly decreased the volume of CNV and angiographic leakage when administered 2 days before and/or immediately after laser injury, but not when administered 2 days after injury. SC Cl(2)MDP-LIP significantly decreased lesion volume when coadministered with IV PBS-LIP but not IV Cl(2)MDP-LIP. IV Cl(2)MDP-LIP was significantly more beneficial when administered 2 days before laser injury than immediately after, but combining SC Cl(2)MDP-LIP with IV treatment eliminated this difference. Reduction in CNV volume correlated with VEGF protein levels and number of infiltrating macrophages.


CONCLUSIONS
Generalized macrophage depletion reduced the size and leakage of laser-induced CNV and was associated with decreased macrophage infiltration and VEGF protein. These findings define the role of the macrophage as a critical component in initiating the laser-induced CNV response.
Sakurai
Eiji
E
Department of Ophthalmology, University of Kentucky, Lexington, Kentucky 40536-0284, USA.
Anand
Akshay
A
Ambati
Balamurali K
BK
van Rooijen
Nico
N
Ambati
Jayakrishna
J
D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D000963:Antimetabolites / Q000008:administration & dosage; D002465:Cell Movement / Q000502:physiology; D020256:Choroidal Neovascularization / Q000503:physiopathology* / Q000517:prevention & control; D004002:Clodronic Acid / Q000008:administration & dosage; D004195:Disease Models, Animal; D016228:Endothelial Growth Factors / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005451:Fluorescein Angiography; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D008081:Liposomes; D008222:Lymphokines / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D000943:Antigens, Differentiation; D000963:Antimetabolites; D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D008081:Liposomes; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C036763:monocyte-macrophage differentiation antigen; D004002:Clodronic Acid