Thymic peptide protects vascular endothelial cells from hydrogen peroxide-induced oxidant injury

Thymosin alpha-1; a natural peptide inhibits cellular proliferation, cell migration, the level of reactive oxygen species and promotes the activity of antioxidant enzymes in human lung epithelial adenocarcinoma cell line (A549)

This research was conducted to investigate the biochemical effects of thymosin alpha-1 using human lung cancer cells (A549). The A549 cells were treated with different concentrations of Thα1 for 24 h and the growth, inhibition of cells was determined. Thα1 revealed anti-proliferative effect at 24 and 48 μg/ml after 24 h. Furthermore, it indicated antioxidant properties by significantly enhancing the activity of catalase (12 μg/ml), superoxide dismutase (6 and 12 μg/ml), and glutathione peroxidase (3, 6 and 12 μg/ml) and reducing the production of cellular ROS. Our results showed that Thα1 inhibits the migration of A549 cells in a concentration-dependent manner after 24 and 48 h. Moreover, the effect of Thα1 on apoptosis was investigated by Hoechst 33342 staining and cell cycle analysis. Results demonstrated no significant effect on the induction of apoptosis in A549 cells. In conclusion, our results showed the antioxidant properties of Thα1 on A549 cancer cells.

In vitro cytotoxicity of the chlorinated naphthoquinone dichlone to human endothelial ECV304 cells

The cytotoxicity of the pro-oxidant fungicide dichlone (2,3-dichloro-1,4-naphthoquinone), to the human endothelial cell line, ECV304, was evaluated. The sensitivity of these cells to dichlone was intermediate between that of human hepatoblastoma HepG2 cells (least sensitive) and that of human GMO5757 fibroblasts. The midpoint cytotoxicity values for a 24-hr exposure to dichlone was about 0.02 mm when evaluated with the neutral red, acid phosphatase, and XTT tetrazolium assays. Lactic acid dehydrogenase leakage, after a 4-hr exposure, occurred initially at 0.05 mm dichlone. As with other naphthoquinones, cellular metabolism of dichlone presumably could proceed either by a one- or a two-electron reduction reaction. The enhancement of potency of dichlone towards ECV304 cells pretreated with the glutathione-depleting agents, dl-buthionine-[S,R]-sulfoximine, 1-chloro-2,4-dinitrobenzene, and 1,3-bis(chloroethyl)-1-nitrosourea; the reduction in potency of dichlone to cells pretreated with (-)-2-oxo-4-thiazolidine carboxylic acid; the decrease in intracellular glutathione on exposure to dichlone; the subtle damage to the plasma membrane of dichlone-treated cells (as detected by the leakage of lactate dehydrogenase from these cells); and the lack of potentiation of dichlone toxicity by pretreatment with dicoumarol, are all consistent with the one-electron reduction reaction as the dominant pathway and with the subsequent generation of reactive oxygen molecules. The ECV304 cell line proved to be a useful research tool to study cytotoxic injury to endothelial cells.

Preparation of EVAL membranes with smooth and particulate morphologies for neuronal culture

In this work, the in vitro interaction of cerebellar granule neurons prepared from 7-day-old Wistar rats and poly ethylene-co-vinyl alcohol (EVAL) membranes was investigated. Cells were cultured in smooth and particulate EVAL membranes for up to 7 days. Particulate membranes were prepared by using 1-octanol to precipitate EVAL solutions in DMSO. Such a membrane was microporous characterized by a packed bed of particles. Voids left between the aggregated particles formed a continuous and interconnected porous network. Crystallization of the EVAL polymer induced by 1-octanol is responsible for the formation of particulate morphology. The membrane structure and its relationship with cells were examined by scanning electron microscopy and the MTT assay. It was observed that the particulate membrane was more favorable for the neuron culture than the smooth membrane. Neurons seeded on the particulate membrane were able to regenerate with formation of an extensive neuritic network. Therefore, the particulate structure may spatially mediate cellular response that can promote neuronal cell attachment, differentiation and neuritic growth, indicating that the particulate structure should be useful as a new polymer scaffold for nerve repair.

Thymosin alpha-1: evidence for an antiatherogenic effect

In the present study, the effects of thymosin alpha1 on lipid peroxidation were studied in an in vivo model of experimental hypercholesterolemia. In groups II-IV, rabbits were fed a high-cholesterol diet 2% (w/w) for 10 weeks. Thereafter, rabbits in group III were fed a normal diet for another 14 days and those in group IV were given a normal diet plus 25 microg/kg thymosin alpha1 intraperitoneally every other day for the same period. At the end of this period, plasma and erythrocyte lipid levels and susceptibility of erythrocytes to lipid peroxidation were determined in all groups. Hypercholesterolemic rabbits had high plasma and erythrocyte lipid peroxide (TBARS) levels compared to control animals fed a normal diet. Plasma and erythrocyte TBARS levels significantly decreased in the thymosin-alpha1-injected rabbits. In thymosin-alpha1-treated animals (group IV), most of the lipid plaques were replaced by fibrous tissue. These findings suggest that thymosin alpha1 may have some beneficial effects on the treatment of atherosclerosis by normalizing blood lipid levels and by substantially protecting endothelial cells against free radical injury.

Oxidative injury induced by synthetic humic acid polymer and monomer in cultured rabbit articular chondrocytes

Humic substance has been proposed as one of the causative factors of Kashin-Beck disease (KBD), an endemic osteoarthritic disorder with necrosis of chondrocytes widely prevalent in some regions of China. In order to exclude the complications of natural humic substance, here we prepared phenolic polymers of synthetic humic acid (SHA) by oxidation of phenolic monomer, the protocatechuic acid (PCA). The biological effects of SHA and PCA on primary culture of rabbit articular chondrocytes were investigated. We found that not only SHA but also PCA caused chondrocyte injury, as evidenced by the loss of cell viability measured with methylthiazol tetrazolium (MTT) assay and the increased release of intracellular lactate dehydrogenase (LDH). Both SHA and PCA could result in lipid peroxidation and glutathione (GSH) depletion in chondrocytes, indicating that oxidative stress may be involved in chondrocyte injury. Furthermore, a marked increase in intracellular calcium level ([Ca2+]i) occurred after chondrocytes treated with SHA or PCA. These results suggest that chondrocyte injury elicited by SHA or PCA may be mediated through the occurrence of oxidative stress and the disruption of intracellular Ca2+ homeostasis. Data also suggest that the monomeric phenolic acid may be considered one of the causative factors of KBD in addition to humic substance.

Fructus corni attenuates oxidative stress in macrophages and endothelial cells

The antioxidant effect of a Chinese medicinal herb, Fructus corni extract (FCE), was investigated using models of oxidative stress in macrophages and vascular endothelial cells. Murine macrophages (J774) were incubated with FCE at 37 degrees C and 5% CO2 for 1 hr. Oxidative burst was triggered by zymosan and measured with a fluorescent probe. FCE exhibited a concentration- dependent suppression of oxidative burst. Confluent monolayers of bovine pulmonary artery endothelial cells (PAEC) were preincubated with FCE for 20 hrs, washed, and then exposed to an organic oxidant t-butyl hydroperoxide (tBHP) for 2 hrs. Cell viability was assessed by methylthiazol tetrazolium (MTT) assay, and cell injury by the release of intracellular lactate dehydrogenase (LDH). Lipid peroxidation products of PAEC were determined by measuring thiobarbituric acid-reactive substances (TBARS). Exposure of PAEC to tBHP resulted in decreased cell viability, increased LDH release, and elevated TBARS. Preincubation of PAEC with FCE significantly reversed these changes. Our results demonstrated that FCE can protect vascular endothelial cells from oxidant injury. The data thus suggest that Fructus corni may be useful for the prevention and/or treatment of disorders associated with oxidative damage.

Impaired proliferation and DNA synthesis of a human tumor cell line (HeLa) caused by short treatment with the anti-anemic drug jectofer (ferric-sorbitol-citrate) and the lipid peroxidation product 4-hydroxynonenal

Anti-anaemic drug, ferric-sorbitol-citrate complex (FSC), inhibit tumour cell growth through the mechanisms which are complex and not entirely understood. The probable mechanisms of described effects of iron is iron-induced oxidative stress of the treated cells. Hence, the effects of FSC on HeLa cell growth in vitro were compared with the biological activity of one of the major mediators of the oxygen free radicals--aldehyde 4-hydroxinonenal (HNE), to see if the effects of FSC and of HNE resemble each other. Impaired proliferative ability and DNA synthesis of HeLa cells was observed after treatment with anti-anaemic drug FSC for 24 hours. After treatment with FSC and culturing of HeLa cells in fresh medium for 24 or 96 hours the cells did not proliferate at all, DNA synthesis was transiently recovered and then diminished again. HNE blocked cell proliferation during the time the aldehyde was present in culture and 24 h later. Afterwards, the cells proliferated as control non-treated cells. HNE did not inhibit DNA synthesis during treatment, but intensity of 3H-thymidine incorporation was lower after preincubation. Thus, both FSC and HNE interfere with the basic mechanisms of the cell growth regulation, while antitumour activity of FSC resembles, but does not necessarily include iron induced lipid peroxidation.

Thymosin alpha 1 protects liver and aorta from oxidative damage in atherosclerotic rabbits

The thymus hormones were reported to be effective on lipid peroxidation and the antioxidant system. Thymus plays a broader role than just regulating the immune system. Thymosin alpha 1 is the first subgroup extracted from thymosin F5 and has higher biological activity than thymosin F5. In the present study, we have examined the effects of thymosin alpha 1 on lipid levels and lipid peroxidation and glutathione (GSH) content in the plasma, liver and aorta tissues of atherosclerotic rabbits. At the end of thymosin alpha 1 treatment, we determined the lipid levels and lipid peroxidation of the plasma, liver and aorta tissues and hepatic subcellular fractions in these rabbits. Our results demonstrated that thymosin alpha 1 might normalize changed lipid levels and increased lipid peroxides and also elevate decreased GSH in the plasma, liver and aorta tissues of atherosclerotic rabbits. Results of this study suggest that thymosin alpha 1 may be beneficial to prevent and/or to treat atherosclerosis.

Mutual dependence of growth modifying effects of 4-hydroxynonenal and fetal calf serum in vitro

Recently, the hypothesis has been put forward that 4-hydroxynonenal (HNE), an aldehydic product of lipid peroxidation, contributes to the mechanisms of oxygen toxicity and to the selective pressure exerted by exposure to hyperoxia. Here it has been studied whether HNE itself is involved in mechanisms that convey increased resistance of the cells to the toxicity of HNE. The following four cell lines, different in their basic biological features, were used: nonmalignant Chinese hamster lung fibroblasts V79 (established cell line), human carcinoma HeLa (established cell line), pigmented murine melanoma B16f10 (primary culture), and amelanotic murine melanoma B16BL6 (primary culture). The cells were pretreated in vitro with a toxic dose of HNE (50 microM), and afterwards the effect of a second exposure to the same dose of HNE on 3H-thymidine incorporation was examined. Cells were cultured in the absence and in the presence of fetal calf serum (FCS), because it had been shown that a growth modifying effect of HNE depends on an unknown serum factor. The results showed that, regardless of the type of cells, preculturing them with 50 microM HNE in the presence of serum changed the reactivity of the cells to added serum as well as to additional HNE treatment. Thus, HNE precultured cells incorporated less 3H-thymidine in the presence of serum than if cultured under serum-free conditions. On the other hand, HNE precultured cells became less sensitive to further HNE treatment, but only if cultured in the presence of serum.(ABSTRACT TRUNCATED AT 250 WORDS)