M2 Macrophage‐Derived Migrasomes Mediate Ischaemia‐Induced Retinal Neovascularization by Targeting TREM2

ABSTRACT Retinal neovascular diseases are leading causes of global blindness. Migrasomes, organelles released during cell migration, play a role in intercellular communication and are present in M2 macrophages, which are critical to the pathology of retinal neovascular diseases. This study investigates the involvement of M2 macrophage‐derived migrasomes in ischaemia‐induced retinal neovascularization (RNV). Migrasomes are isolated from macrophages and characterized by Western blotting and transmission electron microscopy. Compared with controls, M2 macrophage‐derived migrasomes significantly enhance human retinal microvascular endothelial cell (HREC) functions by Cell Counting Kit‐8, transwell, and tube formation assays, and markedly contribute to the pathological retinal angiogenesis of oxygen‐induced retinopathy (OIR) mice. Triggering receptor expressed on myeloid cells 2 (TREM2) is selected as the potential downstream target of M2 macrophage‐derived migrasomes by proteomic analysis. Moreover, the depletion of M2 macrophages in OIR retinas reduces the levels of migrasomes and TREM2. BTC and PLA1A overexpression in HRECs could attenuate decreased HREC functions induced by sh‐TREM2 M2 macrophage‐derived migrasomes. These findings demonstrate that TREM2‐enriched M2 macrophage‐derived migrasomes contribute to pathological RNV in vivo and positively regulate HREC functions in vitro through targeting TREM2‐BTC/PLA1A, which may serve as biomarkers and therapeutic targets for retinal neovascular diseases.