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M. Schallenberg, P. Charalambous, U. Schröer, S. Thanos; Gm-Csf Protects Injured Retinal Ganglion Cells From Programmed Cell Death via Regulating the Expression of Apaptosis-Related Proteins and Activation of ERK1/2 Pathway. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5837.
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© ARVO (1962-2015); The Authors (2016-present)
Granulocyte macrophage colony stimulating factor (GM-CSF) is a potent hemopoetic cytcokine, which stimulates proliferation of bone marrow stem cells and inhibits apoptosis in leukocytes. In the present study, we examined whether GM-CSF is neuroprotective in retinal ganglion cells (RGC).
The epression of GM-CSF and the GM-CSF a-receptor in rat and human retina was examined by immunocytochemistry and Western blot analysis. RGC-5 cells, a retinal ganglion cell line, GM-CSF were incubated with staurosporine either in presence or absence of different concentrations of GM-CSF and co-inkubation with MEK1/2 inhibitor (U0126). Live-Death-Assay was used to assess the induced cell death. The caspase 3 activity and Bcl-2 expression was examined by Western blot analysis. The expression of phosphorylated ERK1/2 pathway proteins after incubation with GM-CSF and U0126 was analysed by Western blot. To examine the in vivo effect GM-CSF or a combination of GM-CSF and staurosporine was injected into the vitreous body of Sprague-Dawley rats. After 10 days the retinal ganglion cells were labeled retrogradely with FluoroGold injected into the contralateral superior colliculus. Four days later, each eye was enucleated and examined by counting the number of RGCs. In a second experiment the optic nerve was axotomized and GM-CSF or PBS was injected into the vitreous body. The RGCs were labeled retrogradely with 4-Di-10-Asp alpplied to the optic nerve. After two weeks the eyes were enucleated and analysed by counting the RGCs.
We identified GM-CSF and the GM-CSF a-receptor in rat and human retina as well as in RGC-5 cells. GM-CSF counteracts staurosporine induced cell death in a dose-dependent manner. Western blot analysis revealed a decreased caspase 3 activity and an increased Bcl-2 expression after co-incubation with GM-CSF. An incubation with GM-CSF activates the ERK1/2 pathway. An inhibition of MEK1/2 with U0126 strongly decreased the phosphorylation downstream in the ERK1/2 pathway and the antiapoptotic activity of GM-CSF in vitro. Like in vitro GM-CSF counteracts the staurosprine induced cell death in vivo. After axotomy the RGCs were protected against degeneration in comparision to control group.
Our data suggest that GM-CSF might be a novel therapeutic agent in neuropathic disease of the eye. Futher studies are needed to evaluate the safety and efficacy of GM-CSF in clinical trials.
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