Tumor necrosis factor and its receptors in the neuroretina and retinal vasculature after ischemia-reperfusion injury in the pig retina

[摘要] Purpose: Numerous studies have beenperformed aimed at limiting the extent of retinal injury afterischemia, but there is still no effective pharmacological treatmentavailable. The aim of the present study was to examine the role oftumor necrosis factor (TNF)α and its receptors (TNF-R1 and TNF-R2),especially considering the neuroretina and the retinal vasculaturesince the retinal blood vessels are key organs in circulatory failure. Methods: Retinal ischemia was induced inpigs by elevating the intraocular pressure to 80 mmHg in one eye,while the other eye served as a control (sham-operated). One hour ofischemia was followed by 5 or 12 h of reperfusion. Retinal circulationwas examined in vivo by fundus imaging and fluorescein angiography.TNF-α levels were measured in the vitreous using an angiogenesisantibody array test. The presence and amounts of TNF-α, TNF-R1, andTNF-R2 were investigated in the neuroretina and in the retinal bloodvessels, using immunofluorescence staining and real-time PCRtechniques. Results: Fundus imaging showedobstructed blood flow when ischemia was induced, and reperfusion wasclearly visualized using fluorescein angiography. Ischemia resulted inelevated levels of TNF-α protein in the vitreous and TNF-α mRNAin the neuroretina. TNF-α immunofluorescence staining was localized tothe Müller cells and the outer plexiform layer of the neuroretina. Theexpression of TNF-R1 and TNF-R2 mRNA was increased inboth the neuroretina and retinal arteries followingischemia-reperfusion. Immunofluorescence double staining for TNF-R1 andeither smooth muscle actin or 4',6-diamidino-2-phenylindole (DAPI)indicated expression in the cell membranes of the vascular smoothmuscle cells. Double staining with TNF-R1 and calbindin showedlocalization to the horizontal cells in the outer plexiform layer ofthe neuroretina. Conclusions: Retinal ischemia results inincreased expression of TNF-α and its receptors (TNF-R1 and TNF-R2).Cellular signaling pathways involving TNF may be important in thedevelopment of retinal injury following ischemia and thus aninteresting target for future development of pharmacologicaltherapeutics.

[学科分类] 生物化学/生物物理