Immunology
Doxycycline Inhibits Polarization of Macrophages to the Proangiogenic M2-type and Subsequent Neovascularization*

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Macrophages occur along a continuum of functional states between M1-type polarized macrophages with antiangiogenic and antitumor activity and M2-type polarized macrophages, which have been implicated to promote angiogenesis and tumor growth. Proangiogenic M2-type macrophages promote various pathologic conditions, including choroidal neovascularization in models of neovascular age-related macular degeneration, or certain cancers, such as glioblastoma multiforme. Thus, a potential novel therapeutic approach to target pathological angiogenesis in these conditions would be to inhibit the polarization of macrophages toward the proangiogenic M2-type. However, no pharmacological inhibitors of M2-type macrophage polarization have been identified yet. Here we performed an unbiased pharmacological and small chemical screen to identify drugs that inhibit proangiogenic M2-type macrophage polarization and block pathologic macrophage-driven neovascularization. We identified the well tolerated and commonly used antibiotic doxycycline as a potent inhibitor of M2-type polarization of macrophages. Doxycycline inhibited, in a dose-dependent manner, M2-type polarization of human and bone marrow-derived mouse macrophages without affecting cell viability. Furthermore, doxycycline inhibited M2-type macrophage polarization and subsequent neovascularization in vivo in a laser injury model of choroidal neovascularization. Thus, doxycycline could be used to enhance current antiangiogenic treatment approaches in various conditions that are promoted by proangiogenic M2-type macrophages, including neovascular age-related macular degeneration and certain cancers.

Angiogenesis
Antibiotics
Inflammation
Innate Immunity
Macrophages
Wound Healing
Macular Degeneration

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*

This study was supported, in whole or in part, by NEI, National Institutes of Health Grant NEI R01-EY019297 (to A. G. M.). This work was also supported by a Shiseido research grant (to A. G. M.) and by a Dermatology Foundation research grant (to L. H.).

This article contains supplemental Figs. S1 and S2 and Tables S1 and S2.