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Myeloid cells contribute indirectly to VEGF expression upon hypoxia via activation of Müller cells

Authors

  • C. Nuernberg
  • N. Kociok
  • C. Brockmann
  • T. Lischke
  • S. Crespo-Garcia
  • N. Reichhart
  • S. Wolf
  • R. Baumgrass
  • S.A. Eming
  • S. Beer-Hammer
  • A.M. Joussen

Journal

  • Experimental Eye Research

Citation

  • Exp Eye Res 166: 56-69

Abstract

  • Anti-VEGF-directed therapies have been a milestone for treating retinal vascular diseases. Depletion of monocyte lineage cells suppresses pathological neovascularization in the oxygen-induced retinopathy mouse model. However, the question whether myeloid-derived VEGF-A expression is responsible for the pathogenesis in oxygen-induced retinopathy remained unknown. We analyzed LysMCre-driven myeloid cell-specific VEGF-A knockout mice as well as mice with complete depletion of circulating macrophages through clodronate-liposome treatment in the oxygen-induced retinopathy model by immunohistochemistry, qPCR, and flow cytometry. Furthermore, we analyzed VEGF-A mRNA expression in MIO-M1 cells alone and in co-culture with BV-2 cells in vitro. The myeloid cell-specific VEGF-A knockout did not change relative retinal VEGF-A mRNA levels, the relative avascular area or macrophage/granulocyte numbers in oxygen-induced retinopathy and under normoxic conditions. We observed an insignificantly attenuated pathology in systemically clodronate-liposome treated knockouts but evident VEGF-A expression in activated Müller cells on immunohistochemically stained sections. MIO-M1 cells had significantly higher expression levels of VEGF-A in co-culture with BV-2 cells compared to cultivating MIO-M1 cells alone. Our data show that myeloid-derived cells contribute to pathological neovascularization in oxygen-induced retinopathy through activation of VEGF-A expression in Müller cells.


DOI

doi:10.1016/j.exer.2017.10.011