Thymosin beta-4 upregulates anti-oxidative enzymes and protects human cornea epithelial cells against oxidative damage.
BACKGROUND
The ability to scavenge reactive oxygen species (ROS) is crucial for cornea epithelial cells to resist oxidative damage. The authors previously demonstrated that exogenous thymosin beta-4 (T beta(4)) was able to protect human cornea epithelial (HCE-T) cells against H(2)O(2)-induced oxidative damage, and its cellular internalisation was essential. The aim of this study is to further elucidate its protective mechanism.


METHODS
HCE-T cells with or without T beta(4) pretreatment were exposed to H(2)O(2), and the differences in caspase activity, intracellular ROS levels, cell viability, and the expression of anti-oxidative enzymes, were measured and compared.


RESULTS
Besides reducing caspase-9 activation and intracellular ROS levels induced by H(2)O(2), treatment of T beta(4) could also increase cell viability and stimulate the expression of manganese superoxide dismutase (SOD) and copper/zinc SOD. Moreover, both transcription and translation levels of catalase were also upregulated by T beta(4) in the presence of exogenous H(2)O(2). Furthermore, it was demonstrated that the addition of catalase inhibitor abrogated the protective effect of T beta(4) against H(2)O(2)-induced oxidative damage.


CONCLUSIONS
To the best of the authors' knowledge, this is the first report to show that T beta(4 )was capable of upregulating anti-oxidative enzymes in human corneal epithelial cells, and these findings further support its role in cornea protection.
Ho
J H-C
JH
Institute of Biopharmaceutical Science, National Yang-Ming University, 155 Sec 2, Li-Nong Street, Taipei 11221, Taiwan.
Tseng
K-C
KC
Ma
W-H
WH
Chen
K-H
KH
Lee
O K-S
OK
Su
Y
Y
D000975:Antioxidants / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects; D002374:Catalase / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019573:Epithelium, Corneal / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013947:Thymosin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects*; D000099201:Thymosin beta(4)
D000975:Antioxidants; D002374:Catalase; D004791:Enzyme Inhibitors; D006861:Hydrogen Peroxide; D011994:Recombinant Proteins; D013947:Thymosin; D000099201:Thymosin beta(4)