Thioredoxin Protects Retinal Microvascular Cell Injury Caused By Hydrogen Peroxide

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 16591754
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Ophthalmology
• Research Institution: Shimane University
• Principal Investigator: KODAMA Tatsuo Shimane University, Faculty of Medicine, Associate Professor, 医学部, 助教授 (60215283)
• Co-Investigator(Kenkyū-buntansha): MASUDA Hisashi Shimane University, Faculty of Medicine, Assistant Professor, 医学部, 助手 (80304278) ; OHIRA Akihiro Shimane University, Faculty of Medicine, Professor, 医学部, 教授 (00169054)
• Project Period (FY): 2004 – 2005
• Keywords: Oxidative Stress / Retinal Microvessel / Thioredoxin / Pericyte

Research Abstract

Objective : Thioredoxin (TRX) is an endogenous redox that has cytoprotective effects against various type of oxidative stresses. We previously found that TRX is upregulated in retinal tissue in response to retinal ischemia-reperfusion, and provided the cell death assay using the freshly isolated rat retinal microvasuculature containing pericytes. The aim of this study was to determine the role of TRX against oxidative stress-induced cell death in the freshly isolated retinal microvessels.
Materials & Methods : Microvessels from Sprague-Dawley rat retinas were freshly isolated using a modified "tissue-print" method. As a model of oxidative-stress, microvessels were exposed to hydrogen peroxide (H2O2). TRX or mutant TRX (active cysteine residues were changed to serine) were added to examine the effect on cell viability. Cell viability was assayed by trypan blue exclusion. To evaluate the role of apoptosis in this cytotoxicity, immunohistochemical procedure using a monoclonal antibody to s ingle-stranded DNA was performed.
Results : After 4 hours of oxidative stress, 61.2+/-15.6% of microvascular cells were dead. This was significantly more cell death than observed in the untreated cells (2.5+/-1.8%). When cells were incubated with H2O2 plus TRX for 4 hours, cytotoxicity was 29.8+/-12.9%. TRX significantly reduced cell death induced by H2O2. When cells were incubated with H2O2 plus mutant TRX for 4 hours, cytotoxicity was 52.6+/-6.9%. Mutant TRX did not reduce cell death induced by H2O2.
Discussion : In this study, retinal pericytes were vulnerable to damage induced by H2O2. Endothelial cytotoxicity was observed thereafter. Apoptotic process was suggested in the pericyte death. Exogenous TRX delayed these oxidative cell deaths in the retinal microvasculature. TRX has two redox-active cysteine residues. These results suggest that TRX has anti-apoptotic effects and that cysteine residues play an important role in this cytoprotection.
Conclusion : TRX plays a protective role against H2O2-induced retinal microvascular cytotoxicity.