Fractalkine, a CX3C chemokine, as a mediator of ocular angiogenesis.
OBJECTIVE
Fractalkine (FKN) is a chemoattractant and adhesion molecule for leukocytes. Angiogenic effect of FKN also has been reported. This study was an investigation of FKN-mediated angiogenesis in vitro and in vivo to determine its role in ocular angiogenic disorders.


METHODS
FKN effects on cultured human umbilical vein endothelial cells (HUVECs) and bovine retinal capillary endothelial cells (BRECs) were evaluated with chemotaxis assay and a synthetic matrix capillary tube formation assay in vitro. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis were used to detect mRNA and protein expression of FKN and its receptor, CX3CR1, in HUVECs and BRECs. A rabbit corneal neovascularization assay and an oxygen-induced retinopathy (OIR) model of mice were used to test the angiogenic property of FKN in vivo. FKN levels of vitreous samples from patients with proliferative diabetic retinopathy were measured by enzyme-linked immunosorbent assay (ELISA). Immunodepletion of FKN in PDR vitreous samples by anti-FKN polyclonal antibody was observed in endothelial cell chemotaxis assays.


RESULTS
FKN significantly induced migration of HUVECs and BRECs. FKN induced formation of endothelial cell capillary tubes on synthetic matrix. Expression of FKN and CX3CR1 was detected in HUVECs and BRECs by RT-PCR and Western blot analysis. FKN significantly induced more blood vessel growth than did the control in the rabbit corneal pocket neovascularization assay. Intravitreal injection of anti-mouse FKN antibody decreased retinal angiogenesis in the OIR model. The vitreous level of FKN was elevated in patients with PDR compared with control subjects. Immunodepletion of soluble FKN from PDR vitreous samples caused 36.6% less migration of BRECs.


CONCLUSIONS
FKN is an angiogenic mediator in vitro and in vivo. The vitreous level of FKN was elevated in patients with PDR. FKN may play an important role in ocular angiogenic disorders such as PDR.
You
Jian-Jang
JJ
Department of Ophthalmology, Keelung General Hospital, Department of Health, The Executive Yuan, Keelung, Taiwan.
Yang
Chang-Hao
CH
Huang
Jen-Shang
JS
Chen
Muh-Shy
MS
Yang
Chung-May
CM
D043925:Angiogenesis Inducing Agents / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D000073883:CX3C Chemokine Receptor 1; D002417:Cattle; D002478:Cells, Cultured; D054428:Chemokine CX3CL1 / Q000235:genetics / Q000494:pharmacology*; D002633:Chemotaxis / Q000187:drug effects*; D016510:Corneal Neovascularization / Q000209:etiology / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000378:metabolism / Q000517:prevention & control; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010100:Oxygen / Q000633:toxicity; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D018121:Receptors, Cytokine / Q000096:biosynthesis / Q000235:genetics; D015728:Receptors, HIV / Q000096:biosynthesis / Q000235:genetics; D011994:Recombinant Proteins; D015861:Retinal Neovascularization / Q000378:metabolism / Q000517:prevention & control; D012171:Retinal Vessels / Q000166:cytology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014471:Umbilical Veins / Q000166:cytology; D014822:Vitreous Body / Q000378:metabolism
D043925:Angiogenesis Inducing Agents; D000073883:CX3C Chemokine Receptor 1; D054428:Chemokine CX3CL1; D012333:RNA, Messenger; D018121:Receptors, Cytokine; D015728:Receptors, HIV; D011994:Recombinant Proteins; D010100:Oxygen