title: Early applications of granulocyte colony-stimulating factor (G-CSF) can stabilize the blood-optic-nerve barrier and ameliorate inflammation in a rat model of anterior ischemic optic neuropathy (rAION).
abstract: Granulocyte colony-stimulating factor (G-CSF) was reported to have a neuroprotective effect in a rat model of anterior ischemic optic neuropathy (rAION model). However, the therapeutic window and anti-inflammatory effects of G-CSF in a rAION model have yet to be elucidated. Thus, this study aimed to determine the therapeutic window of G-CSF and investigate the mechanisms of G-CSF via regulation of optic nerve (ON) inflammation in a rAION model. Rats were treated with G-CSF on day 0, 1, 2 or 7 post-rAION induction for 5 consecutive days, and a control group were treated with phosphate-buffered saline (PBS). Visual function was assessed by flash visual evoked potentials at 4 weeks post-rAION induction. The survival rate and apoptosis of retinal ganglion cells were determined by FluoroGold labeling and TUNEL assay, respectively. ON inflammation was evaluated by staining of ED1 and Iba1, and ON vascular permeability was determined by Evans Blue extravasation. The type of macrophage polarization was evaluated using quantitative real-time PCR (qRT-PCR). The protein levels of TNF-α and IL-1β were analyzed by western blotting. A therapeutic window during which G-CSF could rescue visual function and retinal ganglion cell survival was demonstrated at day 0 and day 1 post-infarct. Macrophage infiltration was reduced by 3.1- and 1.6-fold by G-CSF treatment starting on day 0 and 1 post-rAION induction, respectively, compared with the PBS-treated group (P<0.05). This was compatible with 3.3- and 1.7-fold reductions in ON vascular permeability after G-CSF treatment compared with PBS treatment (P<0.05). Microglial activation was increased by 3.8- and 3.2-fold in the early (beginning treatment at day 0 or 1) G-CSF-treated group compared with the PBS-treated group (P<0.05). Immediate (within 30 mins of infarct) treatment with G-CSF also induced M2 microglia/macrophage activation. The cytokine levels were lower in the group that received immediate G-CSF treatment compared to those in the later G-CSF treatment group (P<0.05). Early treatment with G-CSF stabilized the blood-ON barrier to reduce macrophage infiltration and induced M2 microglia/macrophage polarization to decrease the expressions of pro-inflammatory cytokines in this rAION model.
authors.affiliation: Institute of Eye Research, Buddhist Tzu Chi General Hospital, Hualien, Taiwan.
authors.forename: Yao-Tseng
authors.initials: YT
authors.lastname: Wen
authors.affiliation: Department of Ophthalmology, Far Eastern Memorial Hospital, Banciao District, New Taipei City, Taiwan Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan.
authors.forename: Tzu-Lun
authors.initials: TL
authors.lastname: Huang
authors.affiliation: Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien, Taiwan.
authors.forename: Sung-Ping
authors.initials: SP
authors.lastname: Huang
authors.affiliation: Department of Dermatology, China Medical University Hospital, Taichung, Taiwan Department of Dermatology, College of Medicine, China Medical University, Taichung, Taiwan miriamchangch@gmail.com rktsai@tzuchi.com.tw.
authors.forename: Chung-Hsing
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Institute of Eye Research, Buddhist Tzu Chi General Hospital, Hualien, Taiwan Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan miriamchangch@gmail.com rktsai@tzuchi.com.tw.
authors.forename: Rong-Kung
authors.identifier: 0000-0001-8760-5739
authors.initials: RK
authors.lastname: Tsai
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002199:Capillary Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004195:Disease Models, Animal; D005074:Evoked Potentials, Visual / Q000187:drug effects; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology / Q000627:therapeutic use*; D007150:Immunohistochemistry; D007249:Inflammation / Q000097:blood / Q000473:pathology*; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D017628:Microglia / Q000187:drug effects / Q000378:metabolism; D009900:Optic Nerve / Q000187:drug effects / Q000473:pathology*; D018917:Optic Neuropathy, Ischemic / Q000097:blood* / Q000188:drug therapy* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017208:Rats, Wistar; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D015415:Biomarkers; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016179:Granulocyte Colony-Stimulating Factor
keywords: Blood–optic-nerve barrier; Granulocyte colony-stimulating factor (G-CSF); Macrophage infiltration; Microglia/macrophage polarization; Rat anterior ischemic optic neuropathy (rAION)