Catalase enrichment using recombinant adenovirus protects alphaTN4-1 cells from H(2)O(2)

Comparison of cardiotoxicity induced by alectinib, apatinib, lenvatinib and anlotinib in zebrafish embryos

Four tyrosine kinase inhibitors, alectinib, apatinib, lenvatinib and anlotinib, have been shown to be effective in the treatment of clinical tumors, but their cardiac risks have also raised concerns. In this study, zebrafish embryos at 6 h post fertilization (hpf) were exposed to the four drugs at concentrations of 0.05-0.2 mg/L until 72 hpf, and then the development of these embryos was quantified, including heart rate, body length, yolk sac area, pericardial area, distance between venous sinus and balloon arteriosus (SV-BA), separation of cardiac myocytes and endocardium, gene expression, vascular development and oxidative stress. At the same exposure concentrations, alectinib and apatinib had little effect on the cardiac development of zebrafish embryos, while lenvatinib and anlotinib could induce significant cardiotoxicity and developmental toxicity, including shortened of body length, delayed absorption of yolk sac, pericardial edema, prolonged SV-BA distance, separation of cardiomyocytes and endocardial cells, and downregulation of key genes for heart development. Heart rate decreased in all four drug treatment groups. In terms of vascular development, alectinib and apatinib did not inhibit the growth of embryonic intersegmental vessels (ISVs) and retinal vessels, while lenvatinib and anlotinib caused serious vascular toxicity, and the inhibition of anlotinib in vascular development was more obvious. Besides, the level of reactive oxygen species (ROS) in the lenvatinib and anlotinib treatment groups was significantly increased. Our results provide reference for comparing the cardiotoxicity of the four drugs.

Analysis of Non-Sumoylated and Sumoylated Isoforms of Pax-6, the Master Regulator for Eye and Brain Development in Ocular Cell Lines

PURPOSE

Pax-6 is a master regulator for eye and brain development. Previous studies including ours have shown that Pax-6 exists in 4 major isoforms. According to their sizes, they are named p48, p46, p43 and p32 with the corresponding molecular weight of 48, 46, 43 and 32 kd, respectively. While p48 and p46 is derived from alternative splicing, p32 Pax-6 is generated through an internal translation initiation site. As for 43 kd Pax-6, two resources have been reported. In bird, it was found that an alternative splicing can generate a p43 Pax-6. In human and mouse, we reported that the p43 kd Pax-6 is derived from sumoylation: addition of a 11 kd polypeptide SUMO1 into the p32 Pax-6 at the K91 residue. Whether other Pax-6 isoforms can be sumoylated or not remains to be explored.

METHODS

The 5 major ocular cell lines were cultured in Dulbecco's modified Eagle's medium (DMEM) containing fetal bovine serum (FBS) or rabbit serum (RBS) and 1% Penicillin- Streptomycin. The mRNA levels were analysed with qRT-PCR. The protein levels were determined with western blot analysis and quantitated with Image J.

RESULTS

Both non-sumoylated and sumoylated isoforms of Pax-6 exist in 6 major types of ocular cells among which five are lens epithelial cells, and one is retinal pigment epithelial cell. Our results revealed that the most abundant isoforms of Pax-6 are the p32 and p46 Pax-6. These two major isoforms can be sumoylated to generate p43 (mono-sumoylated p32 Pax-6), p57 and p68 Pax-6 (mono- and di-sumoylated p46 Pax-6). In addition, the splicing-generated p48 Pax-6 is also readily detected.

CONCLUSION

Our results for the first time, have determined the relative isoform abundance and also the sumoylation patterns of pax-6 in 6 major ocular cell lines.

Comparison of lens oxidative damage induced by vitrectomy and/or hyperoxia in rabbits

AIM

To compare of lens oxidative damage induced by vitrectomy and/or hyperoxia in rabbit.

METHODS

Sixteen New Zealand rabbits (2.4-2.5 kg) were randomly divided into two groups (Group A, n=12; Group B, n=4). In Group A, the right eyes were treated with vitrectomy and systemic hyperoxia (oxygen concentration: 80%-85%, 1 ATA, 4h/d) (Group A-right), and the left eyes were treated with hyperoxia without vitrectomy surgery (Group A-left). Four rabbits in group B (eight eyes) were untreated as the controls. Lens transparency was monitored with a slit lamp and recorded before and after vitrectomy. After hyperoxic treatment for 6mo, the eyeballs were removed and the lens cortices (containing the capsules) and nuclei were separated for further morphological and biochemical evaluation.

RESULTS

Six months after treatments, there were no significant morphological changes in the lenses in any experimental group when observed with a slit lamp. However, the levels of water-soluble proteins and ascorbate, and the activities of catalase and Na⁺-K⁺-ATPase were significantly reduced, whereas the levels of malondialdehyde and transforming growth factor β2 (TGF-β2) were significantly elevated, in both the cortices and nuclei of eyes treated with vitrectomy and hyperoxia. The increase in protein-glutathione mixed disulfides and the reduction in water-soluble proteins were more obvious in the lens nuclei. The levels of ascorbate in the vitreous fluid were also reduced after vitrectomy, whereas TGF-β2 increased after vitrectomy and hyperoxia. Systemic hyperoxia exposure increased these effects.

CONCLUSION

Removal of the intact vitreous gel with vitrectomy and exposing the lens to increased oxygen from the retina induce lens oxidation and aggregation. Thus, an intact vitreous gel structure may protect the lens from oxidative insult and maintain lens transparency.

Oxidative responses induced by pharmacologic vitreolysis and/or long-term hyperoxia treatment in rat lenses

PURPOSE

The aim of the study was to investigate the protective effects of intact vitreous gel on the lens after pharmacologic vitreolysis and hyperoxia exposure in rats in vivo.

METHODS

Eyes of Sprague-Dawley rats were induced to posterior vitreous detachment (PVD) by pharmacologic vitreolysis, and the rats with and without PVD were treated with hyperoxia 3 h per day for 5 months. Lens transparency was monitored by a slit-lamp biomicroscope. A series of biochemical measurements were made in extracts of the lens cortex and nucleus. Ascorbate levels were measured in the aqueous and vitreous humors.

RESULTS

No significant differences in lens transparency or morphology were observed in all groups, and no significant biochemical changes were observed in the cortex or nucleus of lenses of the PVD group. In the lens nucleus, the values of water-soluble protein concentration in PVD + hyperoxia group were lower than that of the PVD group. The levels of water-soluble proteins, glutathione (GSH) and ascorbate decreased in the hyperoxia group with an intact vitreous body. Vitreolysis enhanced the effect of hyperoxia, decreasing soluble protein, GSH and ascorbate below the levels seen in eyes with vitreolysis alone. The levels of antioxidants and soluble proteins were lower in the lens nucleus, and the effects of vitreolysis plus hyperoxia were more significant in the nucleus. Hyperoxia and hyperoxia plus vitreolysis reduced catalase activity and increased oxidized GSH to a greater extent in the lens cortex, although these treatments increased protein-GSH mixed disulfides in both regions. Long-term hyperoxia also lowered ascorbate levels in the vitreous and aqueous humors, an effect that was enhanced by vitreolysis.

CONCLUSIONS

Exposure to excess molecular oxygen produces significant oxidative damage to the lens, especially the lens nucleus. These effects were enhanced by pharmacologic vitreolysis, indicating that intact vitreous gel protects the lens from oxidative damage.

Neuroprotective effect of peroxiredoxin 6 against hypoxia-induced retinal ganglion cell damage

Background

The ability to respond to changes in the extra-intracellular environment is prerequisite for cell survival. Cellular responses to the environment include elevating defense systems, such as the antioxidant defense system. Hypoxia-evoked reactive oxygen species (ROS)-driven oxidative stress is an underlying mechanism of retinal ganglion cell (RGC) death that leads to blinding disorders. The protein peroxiredoxin 6 (PRDX6) plays a pleiotropic role in negatively regulating death signaling in response to stressors, and thereby stabilizes cellular homeostasis.

Results

We have shown that RGCs exposed to hypoxia (1%) or hypoxia mimetic cobalt chloride display reduced expression of PRDX6 with higher ROS expression and activation of NF-κB. These cells undergo apoptosis, while cells with over-expression of PRDX6 demonstrate resistance against hypoxia-driven RGC death. The RGCs exposed to hypoxia either with 1% oxygen or cobalt chloride (0-400 μM), revealed ~30%-70% apoptotic cell death after 48 and 72 h of exposure. Western analysis and real-time PCR showed elevated expression of PRDX6 during hypoxia at 24 h, while PRDX6 protein and mRNA expression declined from 48 h onwards following hypoxia exposure. Concomitant with this, RGCs showed increased ROS expression and activation of NF-κB with IkB phosphorylation/degradation, as examined with H2DCF-DA and transactivation assays. These hypoxia-induced adverse reactions could be reversed by over-expression of PRDX6.

Conclusion

Because an abundance of PRDX6 in cells was able to attenuate hypoxia-induced RGC death, the protein could possibly be developed as a novel therapeutic agent acting to postpone RGC injury and delay the progression of glaucoma and other disorders caused by the increased-ROS-generated death signaling related to hypoxia.

Neuroprotective effect of adenoviral catalase gene transfer in cortical neuronal cultures

Reduced availability of reactive oxygen species is a key component of neuroprotection against various toxic stimuli. Recently we showed that the hydrogen peroxide scavenger catalase plays a central role in delayed preconditioning induced by the mitochondrial ATP-sensitive potassium channel opener BMS-191095. The purpose of the experiments discussed here was to investigate the neuroprotective effect of catalase in vitro using a recombinant adenoviral catalase gene transfer protocol. To induce catalase overexpression, cultured rat cortical neurons were infected with the adenoviral vector Ad5CMVcatalase and control cells were incubated with Ad5CMVntLacZ for 24 h. Gene transfer effectively increased catalase protein levels and activity, but did not influence other antioxidants tested. Ad5CMVcatalase, with up to 10 plaque forming units (pfu) per neuron, did not affect cell viability under control conditions and did not protect against glutamate excitotoxicity or oxygen-glucose deprivation. In contrast, catalase overexpression conferred a dose-dependent protection against exposure to hydrogen peroxide (viability: control, 33.02+/-1.09%; LacZ 10 pfu/cell, 32.85+/-1.51%; catalase 1 pfu/cell, 62.09+/-4.17%*; catalase 2 pfu/cell, 98.71+/-3.35%*; catalase 10 pfu/cell, 99.68+/-1.99%*; *p<0.05 vs. control; mean+/-SEM). Finally, the protection could be antagonized using the catalase inhibitor 3-aminotriazole. Our results support the view that enhancing cellular antioxidant capacity may play a crucial role in neuroprotective strategies.

Peroxiredoxin 6 delivery attenuates TNF-alpha-and glutamate-induced retinal ganglion cell death by limiting ROS levels and maintaining Ca2+ homeostasis

Higher expression of reactive oxygen species (ROS) is implicated in neurological disorders. A major event in glaucoma, the death of retinal ganglion cells (RGCs), has been associated with elevated levels of glutamate and TNF-alpha in the RGCs' local microenvironment. Herein we show that the transduction of Peroxiredoxin 6 (PRDX6) attenuates TNF-alpha- and glutamate-induced RGC death, by limiting ROS and maintaining Ca2+ homeostasis. Immunohistochemical staining of rat retina disclosed the presence of PRDX6 in RGCs, and Western and real-time PCR analysis revealed an abundance of PRDX6 protein and mRNA. RGCs treated with glutamate and/or TNF-alpha displayed elevated levels of ROS and reduced expression of PRDX6, and underwent apoptosis. A supply of PRDX6 protected RGCs from glutamate and TNF-alpha induced cytotoxicity by reducing ROS level and NF-kappaB activation, and limiting increased intracellular Ca2+ influx. Results provide a rationale for use of PRDX6 for blocking ROS-mediated pathophysiology in glaucoma and other neuronal disorders.

Properties of grape seed proanthocyanidins and quercetin in human lymphocytes

This study addresses the in vitro protective effects of proanthocyanidins and quercetin on the frequency of micronuclei with reference to the antioxidant status of cultured human lymphocytes also subjected to 2 Gy of ?-radiation. Treatment of lymphocytes with proanthocyanidins induced a significant decrease in the frequency of micronuclei and reduction of malonyldialdehyde production, as well as increased catalase and glutathione S-transferase activity. Quercetin induces a higher incidence of micronuclei and production of malonyldialdehyde. The seven-fold increase of micronuclei frequency induced by a therapeutic dose of ?-radiation was decreased in the presence of proanthocyanidins. These results demonstrate that proanthocyanidins may be important in the prevention of ROS-induced oxidative lymphocyte damage by decreasing DNA damage, lowering membrane lipid peroxidation, and increasing the activity AOP enzymes, as well as by reducing the level of ?-radiation-induced DNA damage. Our results support the potential benefits of proanthocyanidins as efficient antioxidants and radioprotectors.

Zinc-desferrioxamine reduces damage to lenses exposed to hyperbaric oxygen and has an ameliorative effect on catalase and Na, K-ATPase activities

Our purpose was to investigate the effects of exposure to high partial pressure of oxygen on lens optical quality and on the activities of lenticular catalase and Na, K-ATPase in culture and to examine the effect of zinc-desferrioxamine (Zn-DFO) addition to cultured lenses exposed to high oxygen partial pressure on these parameters. Bovine lenses, kept in organ culture, were exposed to different combinations of partial pressure of oxygen with and without addition of Zn-DFO complex (20 microM) and examined during a 14-day period. Lens optical quality, catalase, and Na, K-ATPase activity were compared between study and control groups. Two hundred lenses were included in the present study. Decreased lenticular optical quality and decreased catalase and Na, K-ATPase activities were observed in lenses exposed to hyperbaric oxygen. Lenses exposed to normobaric oxygen showed a reduction in these parameters to a lesser degree. The damaging optical and enzymatic effects of oxygen on lenses in culture increased in magnitude along the culture period. Addition of Zn-DFO to the culture just before the exposure to hyperbaric oxygen eliminated most of the optical and enzymatic oxygen-induced damage. Addition of Zn-DFO after the first exposure demonstrated reduction in the oxidative damage induced reduction of optical quality in a time-dependent manner - the later the addition of Zn-DFO took place the smaller the protective effect observed. High oxygen load has toxic effects on bovine lenses in organ culture conditions as determined by optical parameters as well as reduction of catalase and Na, K-ATPase activities. These toxic effects can be attenuated by introducing Zn-DFO just before lenses are exposed to oxygen. The beneficial effect of Zn-DFO, applied after lenses have been exposed to hyperbaric oxygen, on the oxidative damage was time-dependent - the earlier the application the more significant the observed protective effect. The present results may indicate a possible future role for Zn-DFO as a protective agent against oxygen-induced human cataract formation.