Relationship between Complement Membrane Attack Complex, Chemokine (C-C Motif) Ligand 2 (CCL2) and Vascular Endothelial Growth Factor in Mouse Model of Laser-induced Choroidal Neovascularization

Puran S Bora,Juan Liu,Nalini S Bora,Purushottam Jha,Ruslana G Tytarenko,Valeriy V Lyzogubov

doi:10.1074/jbc.m111.226266

Puran S Bora, Juan Liu + Show 4 more

Open Access

https://doi.org/10.1074/jbc.m111.226266

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Abstract

The present study investigated the interactions among the complement membrane attack complex (MAC), CCL2, and VEGF that occur in vivo during the development of choroidal neovascularization (CNV). We first investigated the sequential expression of MAC, CCL2, and VEGF during laser-induced CNV in C57BL/6 mice. Increased MAC deposition was detected at 1 h, CCL2 increased at 3 h, and VEGF was up-regulated at day 3 post-laser treatment. These results suggested that during laser-induced CNV, MAC, CCL2 and VEGF are formed and/or expressed in the following order: MAC → CCL2 → VEGF. To determine the cross-talk between MAC, CCL2, and VEGF during laser-induced CNV, neutralizing antibodies were injected both systemically and locally to block the bioactivity of each molecule. Blocking MAC formation inhibited CCL2 and VEGF expression and also limited CNV formation, whereas neutralization of CCL2 bioactivity did not affect MAC deposition; however, it reduced VEGF expression and CNV formation. When bioactivity of VEGF was blocked, CNV formation was significantly inhibited, but MAC deposition was not affected. Together, our results demonstrate that MAC is an upstream mediator and effect of MAC on the development of laser-induced CNV can be attributed to its direct effect on VEGF as well as its effect on VEGF that is mediated by CCL2. Understanding the interplay between immune mediators is critical to gain insight into the pathogenesis of CNV.

Highlights

Age-related macular degeneration (AMD) is usually classified into two forms: the nonexudative/dry form and the exudative/wet form [6, 7]
Studies reported in the literature have indicated a possible role of chemokines such as chemokine (C-C motif) ligand 2 (CCL2) in choroidal neovascularization (CNV) formation [33,34,35]
A combination of following four approaches was used to establish a link between membrane attack complex (MAC), the end product of complement activation, CCL2, and VEGF during the development of laser-induced CNV in mice

Summary

Introduction

AMD is usually classified into two forms: the nonexudative/dry form and the exudative/wet form [6, 7]. I.p. Injection—C57BL/6 mice were injected with monoclonal anti-mouse CCL2 antibody or control rat IgG as described under “Experimental Procedures.” Neutralization of CCL2 bioactivity did not alter the MAC deposition within laser spots both at 12 h (Fig. 4, A and B) and on day 3 post-laser treatment (Fig. 4, C and D).

Results

Conclusion