Cytosolic phospholipase A2 mediates arachidonoyl phospholipid hydrolysis in immortalized rat brain endothelial cells stimulated by oxidized LDL.

We tested the hypothesis that oxidized low-density lipoprotein (oxLDL), administered in sublethal doses to the culture medium of immortalized rat brain endothelial cells (ECs, GP8.39), acts as a prooxidant signal to stimulate peroxidation processes and membrane phospholipid hydrolysis. ECs were grown at confluence in a medium with or without native LDL (nLDL) or oxLDL (1.5 mg/dish; up to 350-450 nmol hydroperoxides/mg protein) for two temporally distinct phases (short incubation period up to 1 h, or long incubation period spanning 24 h). Peroxidation parameters (conjugated dienes, MDA, hydroperoxides and LDH release) and arachidonic acid (AA) release were determined. Cell lysates and subcellular fractions were assayed for cPLA(2) while the cytotoxic effect and apoptosis were monitored by morphological changes, trypan blue dye exclusion, MTT reduction test, caspase-3 activity, COMET and laser confocal fluorescence microscopy (LCFM) analyses. Effects of alpha-tocopherol and 85-kDa PLA(2) inhibitor (AACOCF(3)), alone or in combination, were also tested. Immunoblot analysis of cPLA(2) was carried out on cell fraction proteins. After incubation for 1 or 24 h, oxLDL (100-200 microM hydroperoxides), but not nLDL, markedly increased lipid peroxidation, cPLA(2) activity and AA release in a dose-dependent manner. AACOCF(3) and antioxidant alpha-tocopherol (1 mM) strongly inhibited the prooxidant-stimulated AA release. Long-term exposure (24 h) to oxLDL (100 microM) had no effect on the cPLA(2) protein content as tested by Western immunoblot analysis, while showing a sharp cytotoxic effect on the cells. Caspase-3 activity and LCFM analysis indicated that oxLDL (100/200 microM) were able to trigger an apoptotic process. The results suggest that (i) ECs may be the target of extensive oxidative damage caused by oxLDL; (ii) activation of cPLA(2) mediates liberation of AA; (iii) cPLA(2) expression was not stimulated by long-term exposure to oxLDL; (iv) oxidized specific constituents of oxLDL, acting as regulatory signals, increase the ability of ECs to degrade membrane phospholipids, end products of which are linked to the development of atherosclerotic lesions.

Ethanol-induced injury in rat primary cortical astrocytes involves oxidative stress: effect of idebenone.

Ethanol-induced neurological disorders have recently been characterised. Indeed, evidence has been collected indicating that chronic ethanol consumption leads to direct or indirect changes in the viability of central nervous system cells. Here we investigated the role of free radical overproduction in primary cortical rat astroglial cells undergoing chronic treatment with ethanol (100 microM). In particular, exposure of astroglial cell cultures to ethanol for 12 consecutive days produced an increased release of lactic dehydrogenase, a decrease on glutamine synthase activity being both effects accompanied by decrease in astroglial viability as detected by MTT (Thiazolyl Blue) test. These effects were accompanied by an increased formation of malondialdehyde (a marker of lipid peroxidation) and by abnormal formation of heat shock protein, being both effects antagonised by liposomally entrapped idebenone, a non-peptidyl free radical scavenger. Taken together, these results suggest that ethanol-induced injury on astroglial cells are mediated by abnormal formation of free radical species and this may represent a useful approach in the treatment of ethanol-related brain disorders.

Switching off HSP70 and i-NOS to study their role in normal and H2O2-stressed human fibroblasts.

i-NOS and HSP70 antisense oligonucleotides were used to study the role of the two well known stress-regulated molecules on cell survival of both untreated control, and H2O2-stressed human fibroblasts. Cell survival was assessed either by LDH release or by MTT assay. The levels of cytosolic i-NOS and HSP70 were tested by using immunoblotting analysis, and reactive oxygen species (ROS) production was quantified. Compared to the values observed in untreated control cells, anti HSP70-transfected human fibroblasts showed an increase in ROS production, i-NOS level and LDH release. The addition of 0.12 mM H2O2 for 20 min. to the HSP70-deprived fibroblasts did not modify the percentage of LDH release observed in H2O2 stressed cells, but reduced cell viability increasing both ROS production and i-NOS level. Anti i-NOS-transfected fibroblasts, compared to the control untreated cells, showed no modification in ROS production, while cell survival was improved. When treated with H2O2 the i-NOS depleted cells counteracted ROS formation as well as LDH release but negatively affected cell viability and HSP70 levels, compared to the results obtained with H2O2 alone-treated fibroblasts. The data indicates that the induced decrease in HSP70 level in oxidative stress conditions makes fibroblasts more prone to oxidative injury and also increases i-NOS level. Whereas in one way the forced decrease in i-NOS expression seems to counteract ROS production stimulated by the oxidative insult in the cells, in another way, since it causes a decrease in HSP70 expression as well as in cell viability, it seems to activate some unidentified pathways affecting cell demise.

Improved antioxidant effect of idebenone-loaded polyethyl-2-cyanoacrylate nanocapsules tested on human fibroblasts.

PURPOSE: The protective antioxidant role of idebenone both as free drug and drug-loaded Tween 80-coated polyethyl-2-cyanoacrylate (PECA) nanocapsules is reported. The relationship between oxidative damage and apoptotic or nonapoptotic cell death is evaluated in vitro. METHODS: Idebenone-loaded nanocapsules were prepared with the interfacial polymerization method in the presence of Tween 80. Human nonimmortalized fibroblasts. under different stress conditions, either 0.5 mM diethylmaleate (DEM) for 60 min or 0.1 mM H2O2 for 30 min, were used as the experimental in vitro model. The production of reactive oxygen species, the cell viability, and the nuclear DNA damage were evaluated. The presence of apoptotic damage was evaluated both by the determination of caspase-3-like protein activity and by Promega's fluorescent apoptotic detection system. RESULTS: DEM and H2O2 affected the cultured cells in different ways. DEM induced a moderate cellular insult, which was efficaciously antagonized by idebenone-loaded PECA nanocapsules. H2O2 elicited severe damage to nuclear DNA, which was reduced by idebenoneloaded PECA nanocapsules. The free drug was less effective than idebenone-loaded nanocapsules. CONCLUSIONS: The findings reported here demonstrate that an improved antioxidant effect was obtained with a low idebenone concentration (0.5 microM) when the drug was entrapped within Tween 80-coated PECA nanocapsules.

De Toni-Debré-Fanconi syndrome due to a palindrome-flanked deletion in mitochondrial DNA.

We report the molecular findings in a child presenting with sideroblastic anemia and proximal tubulopathy. Analysis of mitochondrial DNA (mtDNA) from fibroblasts showed the presence of a 3.3-kb single deletion in 50% of the genomes. This mutation is, unlike other previously reported deletions in tubulopathy patients, not flanked by direct repeat sequences but by palindrome sequences at the deletion breakpoints, suggesting an unusual mechanism for production of deletion. These findings further expand our knowledge of the syndrome of anemia and tubulopathy due to single deletions of mtDNA.