Protective Effect of Peroxiredoxin 6 in Ischemia/Reperfusion-Induced Damage of Small Intestine.

BACKGROUND: Strong oxidative stress starting in the epithelium upon restoration of blood cell circulation is a major cause of necrosis of the intestinal epithelium in ischemia/reperfusion-induced damage. AIM: The purpose of this study was to investigate the tissue-protective effect of exogenous peroxiredoxin 6 (Prx6) in ischemia/reperfusion-induced damage of small intestine. METHODS: The research was carried out using a model of acute superior mesenteric artery occlusion in Wistar male rats. Exogenous Prx6 was administrated intravenously 15 min prior to small intestine ischemia. The distribution of endogenous Prx6 in the small intestine was determined by immunohistochemical analysis. The expression level of antioxidant enzymes was evaluated by RT-PCR in real time. RESULTS: Exogenous Prx6 injected to animals intravenously was detected in blood vessel lumens, and its diffuse distribution was subsequently confirmed in the intestinal epithelium. Expression analysis of genes coding for major antioxidant enzymes demonstrated a significant activation of SOD 1, SOD 3, Prx6, GPx2, GPx7 expression during I/R-induced damage of the small intestine. Injection of exogenous Prx6 prior to induced ischemia resulted in minimization of oxidative injury by reducing necrosis and apoptosis, by normalization of gene activity of antioxidant enzyme. It eventually led to a reduction of epithelium destruction in the small intestine. By contrast, administration of a purified mutant form of Prx6 (Prx6C47S) without peroxidase activity had no protective effect. CONCLUSION: The application of exogenous Prx6 enables normalization of the antioxidant status of the small intestine and reduction of cell destruction upon I/R-induced organ damage.

Topical administration of peroxiredoxin-6 on the cornea suppresses inflammation and neovascularization induced by ultraviolet radiation.

PURPOSE: To investigate the effect of topical administration of peroxiredoxin-6 (PRDX6) on ultraviolet-induced corneal injury. METHODS: Corneal transparency and neovascularization were observed with a slit-lamp microscope and hematoxylin and eosin staining. The oxidative damage was determined with a commercial malondialdehyde (MDA) kit. The expressions of PRDX6, polymorphonuclear neutrophil (PMN), vascular endothelial growth factor (VEGF), and pigment epithelium-derived factor (PEDF) were determined by immunohistochemistry and Western blot. The expressions of genes related with antioxidant defense systems and cell apoptosis were detected by RT-PCR. RESULTS: The irradiated corneas appeared opaque and had high levels of MDA. Peripheral neovascularization and neutrophils appeared in the control and buffer-treated groups (with no treatment or PRDX6 diluent, respectively), whereas they were significantly suppressed in the PRDX6-treated group. The MDA content of the corneas in the PRDX6-treated group was significantly lower than that of the control and buffer-treated groups (P < 0.05). In the PRDX6-treated group the immunoreactivity of VEGF was lower, and that of PEDF was higher, than that in the control and buffer-treated groups. In addition, there were expression correlations between PRDX6 and PMN, VEGF, PEDF. The expressions of genes related with antioxidant defense systems and cell apoptosis were significant different between buffer- and PRDX6-treated groups (P < 0.05). CONCLUSIONS: The topically administered PRDX6 maintained the homeostasis of corneal cells, reduced inflammation, and suppressed neovascularization and apoptosis under ultraviolet irradiation.

TAT-mediated peroxiredoxin 5 and 6 protein transduction protects against high-glucose-induced cytotoxicity in retinal pericytes.

AIMS: Hyperglycemia-induced oxidative stress is implicated in pericyte apoptosis seen in diabetic retinopathy. The six mammalian Peroxiredoxins (PRDXs) comprise a novel family of antioxidative proteins that negatively regulate oxidative stress-induced apoptosis by controlling reactive oxygen species (ROS) levels. MAIN METHODS: Sprague-Dawley rats were used to detect the retinal expressions of PRDXs1-6. Pig pericytes cultured in high-glucose medium were used to monitor the protective effect of PRDX5 and 6 against high-glucose-associated change. Recombinant PRDX5 and 6 proteins were linked to the Trans-Activating Transduction (TAT) domain from HIV-1 TAT protein for their efficient delivery into cells/tissues. KEY FINDINGS: We found higher expression of PRDX5 and 6 mRNAs and PRDX5 and 6 proteins in retina than the other Prdxs (Prdx1-4). Western blotting affirmed the intracellular presence of TAT-linked proteins and revealed the efficient transduction of TAT-HA-PRDX5 and 6 in these cells. Extrinsic supply of TAT-HA-PRDX5 and 6 proteins inhibited the oxidative stress-induced DNA damage after high-glucose exposure in pig pericytes. The cell survival and apoptosis assay revealed that extrinsic supply of TAT-HA-PRDX5 and 6 proteins was responsible for inhibiting hyperglycemia-induced pericyte apoptosis. SIGNIFICANCE: Results suggest that delivery of PRDX5 and 6 might protect hyperglycemia-induced pericyte loss to inhibit oxidative stress.