PURPOSE: The ability of microglial cells (MG) and macrophages (MAC) to release cytokines, induce apoptosis, as well as perform phagocytic functions suggests a possible role in wound healing following oxygen-induced injury. This study was performed to determine the temporal and spatial expression of F4/80 (F4/80+) positive microglia/macrophages (MG/MAC) in areas of retinal damage in the mouse model of oxygen-induced retinopathy. METHODS: C57BL/6 postnatal day 7 (P7) mice were exposed to 75% O2 for 5 days (P12) then allowed to recover in room air. Hyperoxia-exposed (O2) mice (O2 refers to hyperoxia exposure from P7 to P12 only) were sacrificed on P12, P14, P17, and P21 and their eyes were examined. Localization of F4/80+ cells in FITC-dextran-perfused retinas allowed coordinate visualization of retinal vessels and MG/MAC via fluorescence microscopy. BrdU, a cellular proliferation marker, was injected intraperitoneally 1 h prior to sacrifice. Immunostaining was performed for a microglia and macrophage-specific antigen (F4/80) and BrdU. CCL2 (monocyte chemoattractant protein-1; MCP-1) expression was examined by quantitative real time reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: There was a marked increase (>500%) in MG/MAC in hyperoxia-exposed retinas on P17O2 and P21O2 compared to control retinas. At P17O2, MG/MAC were localized in areas of neovascularization (NV), revealing an intimate relationship between MG/MAC and neovascular tufts. However, P21O2 retinas demonstrated MG/MAC associated with avascular regions in the outer layers of the retina. Immunostaining for F4/80 and BrdU revealed rare co-localization in hyperoxia-exposed retinas. Real time RT-PCR results demonstrated increased expression of CCL2 in P14O2- and P17O2- exposed retinas. CONCLUSIONS: Our results suggest that resident retinal microglia proliferation occurs at a low frequency in response to injury in this model. The substantial increase in total F4/80+ cells in hyperoxia-exposed retinas in conjunction with the upregulation of CCL2 is consistent with recruitment of hematogenous macrophages into the retina. The temporal and spatial localization of MG/MAC adjacent to neovascular tufts suggests these cells are modulating the retinal response to ischemia-induced retinopathy.
PURPOSE: The ability of microglial cells (MG) and macrophages (MAC) to release cytokines, induce apoptosis, as well as perform phagocytic functions suggests a possible role in wound healing following oxygen-induced injury. This study was performed to determine the temporal and spatial expression of F4/80 (F4/80+) positive microglia/macrophages (MG/MAC) in areas of retinal damage in the mouse model of oxygen-induced retinopathy. METHODS: C57BL/6 postnatal day 7 (P7) mice were exposed to 75% O2 for 5 days (P12) then allowed to recover in room air. Hyperoxia-exposed (O2) mice (O2 refers to hyperoxia exposure from P7 to P12 only) were sacrificed on P12, P14, P17, and P21 and their eyes were examined. Localization of F4/80+ cells in FITC-dextran-perfused retinas allowed coordinate visualization of retinal vessels and MG/MAC via fluorescence microscopy. BrdU, a cellular proliferation marker, was injected intraperitoneally 1 h prior to sacrifice. Immunostaining was performed for a microglia and macrophage-specific antigen (F4/80) and BrdU. CCL2 (monocyte chemoattractant protein-1; MCP-1) expression was examined by quantitative real time reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: There was a marked increase (>500%) in MG/MAC in hyperoxia-exposed retinas on P17O2 and P21O2 compared to control retinas. At P17O2, MG/MAC were localized in areas of neovascularization (NV), revealing an intimate relationship between MG/MAC and neovascular tufts. However, P21O2 retinas demonstrated MG/MAC associated with avascular regions in the outer layers of the retina. Immunostaining for F4/80 and BrdU revealed rare co-localization in hyperoxia-exposed retinas. Real time RT-PCR results demonstrated increased expression of CCL2 in P14O2- and P17O2- exposed retinas. CONCLUSIONS: Our results suggest that resident retinal microglia proliferation occurs at a low frequency in response to injury in this model. The substantial increase in total F4/80+ cells in hyperoxia-exposed retinas in conjunction with the upregulation of CCL2 is consistent with recruitment of hematogenous macrophages into the retina. The temporal and spatial localization of MG/MAC adjacent to neovascular tufts suggests these cells are modulating the retinal response to ischemia-induced retinopathy.
Authors: Matthew R Ritter; Eyal Banin; Stacey K Moreno; Edith Aguilar; Michael I Dorrell; Martin Friedlander Journal: J Clin Invest Date: 2006-11-16 Impact factor: 14.808
Authors: Carmel M McVicar; Liza M Colhoun; Jodie L Abrahams; Claire L Kitson; Ross Hamilton; Reinhold J Medina; Dash Durga; Tom A Gardiner; Pauline M Rudd; Alan W Stitt Journal: PLoS One Date: 2010-07-29 Impact factor: 3.240
Authors: Xi-Qin Ding; Alexander B Quiambao; J Browning Fitzgerald; Mark J Cooper; Shannon M Conley; Muna I Naash Journal: PLoS One Date: 2009-10-12 Impact factor: 3.240