The dynamic changes of macrophage morphology in progression of choroidal neovascularization in laser-induced choroidal neovascularization mice model 

Abstract Background: Neovascular AMD is responsible for the majority of severe vision loss which is mainly caused by choroidal neovascularization (CNV) . It persists or recurs in a subset of patients and regression at 5 years of anti-VEGF treatment or later. The precise mechanisms contribute to CNV continue to be elucidated. According to our previous studies, macrophage play a critical role in CNV, herein, we aim to unveil the conceret morphological changes of macrophage in CNV process to help us understand the dynamic changes intuitively. Methods: Mice were subjected to laser injury to induce CNV, and lesion expansion and macrophages, transformation were tracked using immunofluorescence and confocal analysis. Several strategies were taken to verify the dynamic changes of macrophage: Immunofluorescence and confocal assays were performed on choroidal flat-mount to evaluate the morphologe and phenotype of macrophage in different CNV phase and further certified with western-blot and RT-PCR. Results: Location of infiltrated macrophages was dynamic after laser injury in CNV mice model and morphology of macrophages was also in dynamic changing. Branching macrophage were gradually shift to be round with the progression of CNV which were certificated to be M2 phenotype shift. Conclusions: The dynamic changes of macrophage morphology were obviously in CNV formation and round-shaped M2 phenotype was proved to promote neovascularization. In general, the changes of morphology we found in this study can further help us to know the critical role macrophages play in CNV progression and to exploite the potential treatment option for CNV implied by macrophage polarity shift.