Thiol antioxidants protect human lens epithelial (HLE B-3) cells against tert-butyl hydroperoxide-induced oxidative damage and cytotoxicity

Oxidative damage to lens epithelial cells plays an important role in the development of age-related cataract, and the health of the lens has important implications for overall ocular health. As a result, there is a need for effective therapeutic agents that prevent oxidative damage to the lens. Thiol antioxidants such as tiopronin or N-(2-mercaptopropionyl)glycine (MPG), N-acetylcysteine amide (NACA), N-acetylcysteine (NAC), and exogenous glutathione (GSH) may be promising candidates for this purpose, but their ability to protect lens epithelial cells is not well understood. The effectiveness of these compounds was compared by exposing human lens epithelial cells (HLE B-3) to the chemical oxidant tert-butyl hydroperoxide (tBHP) and treating the cells with each of the antioxidant compounds. MTT cell viability, apoptosis, reactive oxygen species (ROS), and levels of intracellular GSH, the most important antioxidant in the lens, were measured after treatment. All four compounds provided some degree of protection against tBHP-induced oxidative stress and cytotoxicity. Cells treated with NACA exhibited the highest viability after exposure to tBHP, as well as decreased ROS and increased intracellular GSH. Exogenous GSH also preserved viability and increased intracellular GSH levels. MPG scavenged significant amounts of ROS, and NAC increased intracellular GSH levels. Our results suggest that both scavenging ROS and increasing GSH may be necessary for effective protection of lens epithelial cells. Further, the compounds tested may be useful for the development of therapeutic strategies that aim to prevent oxidative damage to the lens.     

Astaxanthin inhibits apoptosis in alveolar epithelial cells type II in vivo and in vitro through the ROS‐dependent mitochondrial signalling pathway

Oxidative stress is an important molecular mechanism underlying lung fibrosis. The mitochondrion is a major organelle for oxidative stress in cells. Therefore, blocking the mitochondrial signalling pathway may be the best therapeutic manoeuver to ameliorate lung fibrosis. Astaxanthin (AST) is an excellent antioxidant, but no study has addressed the pathway of AST against pulmonary oxidative stress and free radicals by the mitochondrion‐mediated signalling pathway. In this study, we investigated the antioxidative effects of AST against H₂O₂‐ or bleomycin (BLM)‐induced mitochondrial dysfunction and reactive oxygen species (ROS) production in alveolar epithelial cells type II (AECs‐II) in vivo and in vitro. Our data show that AST blocks H₂O₂‐ or BLM‐induced ROS generation and dose‐dependent apoptosis in AECs‐II, as characterized by changes in cell and mitochondria morphology, translocation of apoptotic proteins, inhibition of cytochrome c (Cyt c) release, and the activation of caspase‐9, caspase‐3, Nrf‐2 and other cytoprotective genes. These data suggest that AST inhibits apoptosis in AECs‐II cells through the ROS‐dependent mitochondrial signalling pathway and may be of potential therapeutic value in lung fibrosis treatment.     

Expression of thioredoxin in bleomycin-injured airway epithelium: possible role of protection against bleomycin induced epithelial injury

Bleomycin (BLM) is an anticancer drug, administration of which leads to severe lung injury, in which the generation of intracellular reactive oxygen species (ROS) is thought to participate in that. Thioredoxin (TRX) has been found to function as a powerful antioxidant by reducing ROS, and thus protecting against ROS-mediated cytotoxicity. However, a protective role of TRX in BLM-induced lung injury has not been determined. In the present study, we therefore attempted to clarify this issue. Human TRX-transfected L929 murine fibrosarcoma cells were more resistant to BLM-induced cytotoxicity than the parental and the control transfected cells, indicating that TRX plays the protective role in BLM-induced cytotoxicity. Next, we examined TRX expression in the lung of in vivo model of BLM-induced lung injury and BLM-stimulated bronchial epithelial cells in vitro to clarify the role of TRX in BLM-induced lung injury. In the lungs of BLM-treated mice, the expression of TRX was strongly induced in bronchial epithelial cells. TRX expression was also up-regulated at both the mRNA and protein levels in cultured BEC with the treatment with BLM. However, the expression of other major antioxidants, such as Cu/Zn-SOD, Mn-SOD, catalase and glutathione peroxidase, was not affected by BLM. These observations suggest that the cellular reduction and oxidation (redox) state modified by TRX is involved in the BLM resistancy and the induction of TRX in bronchial epithelial cells might play a protective role in BLM-induced lung injury.     

Effects of N-acetylcysteine amide (NACA), a thiol antioxidant on radiation-induced cytotoxicity in Chinese hamster ovary cells

Ionizing radiation is known to cause tissue damage in biological systems, mainly due to its ability to produce reactive oxygen species (ROS) in cells. Many thiol antioxidants have been used previously as radioprotectors, but their application has been limited by their toxicity. In this investigation, we have explored the possible radioprotective effects of a newly synthesized thiol antioxidant, N-acetylcysteine amide (NACA), in comparison with N-acetylcysteine (NAC), a commonly used antioxidant. Protective effects of NACA and NAC were assessed using Chinese hamster ovary (CHO) cells, irradiated with 6 gray (Gy) radiation. Oxidative stress parameters, including levels of reduced glutathione (GSH), cysteine, malondialdehyde (MDA), and activities of antioxidant enzymes like glutathione peroxidase, glutathione reductase, and catalase, were measured. Results indicate that NACA was capable of restoring GSH levels in irradiated cells in a dose dependent manner. In addition, NACA prevented radiation-induced loss in cell viability. NACA further restored levels of malondialdehyde, caspase-3 activity, and antioxidant enzyme activities to control levels. Although NAC affected cells in a similar manner to NACA, its effects were not as significant. Further, NAC was also found to be cytotoxic to cells at higher concentrations, whereas NACA was non-toxic at similar concentrations. These results suggest that NACA may be able to attenuate radiation-induced cytotoxicity, possibly by its ability to provide thiols to cells.     

Comparative evaluation of N-acetylcysteine and N-acetylcysteineamide in acetaminophen-induced hepatotoxicity in human hepatoma HepaRG cells

Acetaminophen (N-acetyl-p-aminophenol, APAP) is one of the most widely used over-the-counter antipyretic analgesic medications. Despite being safe at therapeutic doses, an accidental or intentional overdose can result in severe hepatotoxicity; a leading cause of drug-induced liver failure in the U.S. Depletion of glutathione (GSH) is implicated as an initiating event in APAP-induced toxicity. N-acetylcysteine (NAC), a GSH precursor, is the only currently approved antidote for an APAP overdose. Unfortunately, fairly high doses and longer treatment times are required due to its poor bioavailability. In addition, oral and intravenous administration of NAC in a hospital setting are laborious and costly. Therefore, we studied the protective effects of N-acetylcysteineamide (NACA), a novel antioxidant, with higher bioavailability and compared it with NAC in APAP-induced hepatotoxicity in a human-relevant in vitro system, HepaRG. Our results indicated that exposure of HepaRG cells to APAP resulted in GSH depletion, reactive oxygen species (ROS) formation, increased lipid peroxidation, mitochondrial dysfunction (assessed by JC-1 fluorescence), and lactate dehydrogenase release. Both NAC and NACA protected against APAP-induced hepatotoxicity by restoring GSH levels, scavenging ROS, inhibiting lipid peroxidation, and preserving mitochondrial membrane potential. However, NACA was better than NAC at combating oxidative stress and protecting against APAP-induced damage. The higher efficiency of NACA in protecting cells against APAP-induced toxicity suggests that NACA can be developed into a promising therapeutic option for treatment of an APAP overdose.     

OXR1 signaling pathway as a possible mechanism of elastase-induced oxidative damage in pulmonary cells: the protective role of ellagic acid

Background and objective

Oxidative stress is a process that occurs through free radicals on the cell membranes which causes damage to the cell and intracellular organelles, especially mitochondria membranes. H2O2 induced oxidative stress in human cells is of interest in toxicological research since oxidative stress plays a main role in the etiology of several pathological conditions. Neutrophil Elastase (Serine proteinase) is involved in the pathology process of emphysema as a respiratory disease through lung inflammation, and destruction of alveolar walls. The present study investigated the direct oxidative stress effects of Elastase in comparison with H2O2 on human lung epithelial cells (A549 cells) concerning the generation of reactive oxygen species (ROS) and modulation of oxidation resistance 1 (OXR1) and its downstream pathway using the well-known antioxidant Ellagic acid as an activator of antioxidant genes.

Materials and methods

The human pulmonary epithelial cells (A549) were divided into the nine groups including Negative control, Positive control (H2O2), Elastase (15, 30, and 60 mU/mL), Ellagic acid (10 μmol/L), and Elastase?+?Ellagic acid. Cytotoxicity, ROS generation, oxidative stress profile, level of reactive metabolites, and gene expression of OXR1 and its downstream genes were measured in all groups.

Results

The obtained data demonstrated that Elastase exposure caused oxidative stress damage in a dose-depended manner which was associated with decreases in antioxidant defense system genes. Conversely, treatment with Ellagic acid as a potent antioxidant showed improved antioxidant enzyme activity and content which was in line with the upregulation of OXR1 signaling pathway genes.

Conclusions

The present findings can highlight the novel mechanism underlying the oxidative stress induced by Neutrophil Elastase through OXR1 and related genes. Moreover, the benefit of Ellagic acid on cytoprotection, resulting from its antioxidant properties was documented.

     

Iron deposition-induced ferroptosis in alveolar type II cells promotes the development of pulmonary fibrosis

Ferroptosis is a newly discovered type of regulated cell death, characterized by the iron-dependent accumulation of lipid reactive oxygen species, which has been implicated in numerous human diseases. However, its role in pulmonary fibrosis, a fatal lung disease with unknown etiology, is largely unknown. Here, we investigated the role of ferroptosis in pulmonary fibrosis. We found a large amount of iron deposition in the lung tissue of patients with pulmonary fibrosis. We observed ferroptosis in alveolar type II (ATII) cells, fibrotic lung tissues of BLM-induced pulmonary fibrosis mice. BLM-induced increase in iron level was accompanied by pathological changes, collagen deposition, and ferroptosis in ATII cells, indicating iron deposition-induced ferroptosis, which promoted the development of pulmonary fibrosis. Moreover, deferoxamine (DFO) completely prevented the pro-fibrosis effects of BLM by reducing iron deposition and ferroptosis in ATII cells. Genes associated with intracellular iron metabolism and homeostasis, such as transferrin receptor 1, divalent metal transporter 1, and ferroportin-1, and showed abnormal expression levels in animal tissues and lung epithelial MLE-12 cells, which responded to BLM stimulation. Overall, we demonstrated that BLM-induced iron deposition in MLE-12 cells is prone to both mitochondrial dysfunction and ferroptosis and that DFO reverses this phenotype. In the future, understanding the role of ferroptosis may shed new light on the etiology of pulmonary fibrosis. Ferroptosis inhibitors or genetic engineering of ferroptosis-related genes might offer potential targets to treat pulmonary fibrosis.     

Exploring the possible mitoprotective and neuroprotective potency of thymoquinone,betanin, and vitamin D against cytarabine-induced mitochondrial impairment and neurotoxicity in rats' brain

It has been suggested that cytarabine (Ara-C) induces toxicity via mitochondrial dysfunction and oxidative stress. Therefore, we hypothesized that mitochondrial protective agents and antioxidants can reduce cytarabine-induced neurotoxicity. For this purpose, 48 male Wistar rats were assigned into eight equal groups include control group, Ara-C (70 mg/kg, i.p.) group, Ara-C plus betanin (25 mg/kg, i.p.) group, Ara-C plus vitamin D (500 U/kg, i.p.) group, Ara-C plus thymoquinone (0.5 mg/kg, i.p.) group, betanin group, vitamin group, and thymoquinone group. The activity of acetylcholinesterase (AChE), and butyrylcholinesterase (BChE), the concentrations of antioxidants (reduced glutathione and oxidized glutathione), oxidative stress (malondialdehyde) biomarkers, mitochondrial toxicity parameters as well as histopathological alteration in brain tissues were measured. Our results demonstrated that Ara-C exposure significantly declines the brain enzymes activity (AChE and BChE), levels of antioxidant biomarkers (GSH), and mitochondrial functions, but markedly elevate the levels of oxidative stress biomarkers (MDA) and mitochondrial toxicity. Almost all of the previously mentioned parameters (especially mitochondrial toxicity) were retrieved by betanin, vitamin D, and thymoquinone compared to Ara-C group. These findings conclusively indicate that betanin, vitamin D, and thymoquinone administration provide adequate protection against Ara-C-induced neurotoxicity through modulations of oxidative, antioxidant activities, and mitochondrial protective (mitoprotective) effects.     

Oxidative stress and mitochondrial dysfunction play a role in myelodysplastic syndrome development,diagnosis, and prognosis: A pilot study

Abstract

The imbalance between reactive oxygen species (ROS) production and their elimination by antioxidants leads to oxidative stress. Depending on their concentration, ROS can trigger apoptosis or stimulate cell proliferation. We hypothesized that oxidative stress and mitochondrial dysfunction may participate not only in apoptosis detected in some myelodysplastic syndrome (MDS) patients, but also in increasing proliferation in other patients. We investigated the involvement of oxidative stress and mitochondrial dysfunction in MDS pathogenesis, as well as assessed their diagnostic and prognostic values. Intracellular peroxides, superoxide, superoxide/peroxides ratio, reduced glutathione (GSH), and mitochondrial membrane potential (Δψ_mit) levels were analyzed in bone marrow cells from 27 MDS patients and 12 controls, by flow cytometry. We observed that all bone marrow cell types from MDS patients had increased intracellular peroxide levels and decreased GSH content, compared with control cells. Moreover, oxidative stress levels were MDS subtype— and risk group—dependent. Low-risk patients had the highest ROS levels, which can be related with their high apoptosis; and intermediate-2-risk patients had high Δψ_mit that may be associated with their proliferative potential. GSH levels were negatively correlated with transfusion dependency, and peroxide levels were positively correlated with serum ferritin level. GSH content proved to be an accurate parameter to discriminate patients from controls. Finally, patients with high ROS or low GSH levels, as well as high superoxide/peroxides ratio had lower overall survival. Our results suggest that oxidative stress and mitochondrial dysfunction are involved in MDS development, and that oxidative stress parameters may constitute novel diagnosis and/or prognosis biomarkers for MDS.     

Protective effects of diosgenin in the hyperlipidemic rat model and in human vascular endothelial cells against hydrogen peroxide-induced apoptosis

Hyperlipidemia is a major cause of atherosclerosis and atherosclerosis-associated conditions in cardiovascular diseases. Oxidative stress, as a main risk factor causes vascular endothelial cell apoptosis, which is implicated in the pathogenesis of cardiovascular disorders. Diosgenin, an aglycone of steroidal saponins, has been reported to exert anti-proliferative and proapoptotic actions on cancer cells widely. In this study, we propose that diosgenin can protect the hyperlipidemic rats and prevent endothelial apoptosis under oxidative stress. We investigated the hypolipidemic and antioxidative effects of diosgenin on rats fed with high cholesterol and high fat diet for 6 weeks. Serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), glutathione peroxidase (GSH-PX), nitric oxide synthase (NOS), hepatic malondialdehyde (MDA), lipoprotein lipase (LPL), hepaticlipase (HL) and superoxide dismutase (SOD) activities were evaluated. Then we explored the effects and mechanism of diosgenin against hydrogen peroxide-induced apoptosis of human vein endothelium cells (HUVECs). Intracellular reactive oxygen species (ROS), glutathione (GSH), nitric oxide (NO), DNA fragment formation and mitochondrial membrane potentials (ΔΨm) were determined. Diosgenin treatment increased LPL, HL, SOD, GSH-PX and NOS activities, thus attenuated oxygen free radicals, decreased MDA, TC, TG and LDL-C levels in hyperlipidemic rats. Diosgenin pretreatment significantly attenuated H₂O₂-induced apoptosis in HUVECs, intracellular ROS, GSH depletion, DNA fragment formation, and restored NO, ΔΨm. These results suggested that diosgenin is a very useful compound to control hyperlipidemia by both improving the lipid profile and modulating oxidative stress and prevent H₂O₂-induced apoptosis of HUVECs, in partly through regulating mitochondrial dysfunction pathway.     

Salvianolic acid B inhibits myofibroblast transdifferentiation in experimental pulmonary fibrosis via the up-regulation of Nrf2

Salvianolic acid B (SalB) is one of the most bioactive components extracted from Salvia miltiorrhiza, and its antioxidant capacity corresponds with its protective effects against cell injury from oxidative stress. The aim of the present study was to evaluate the effect of SalB on experimental pulmonary fibrosis and its ability to ameliorate the oxidative/antioxidative imbalance during fibrosis pathogenesis. The anti-fibrotic activity of SalB was first confirmed in Transforming growth factor β1(TGF-β1)-stimulated MRC-5 cells. The protection of SalB against oxidative stress during fibrogenesis in vitro was verified by detecting ROS production, the levels of glutathione (GSH) and malondialdehyde (MDA). The Western blot and PCR results indicated that SalB could up-regulate nuclear factor erythroid-derived 2-like 2 (Nrf2) at both the protein and mRNA levels and induce Nrf2 nuclear translocation in vitro, which may be the mechanism underlying the anti-fibrotic capacity of SalB. Furthermore, the anti-fibrotic and antioxidant capacities of SalB in vivo were confirmed in rats with BLM-induced pulmonary fibrosis. The immunohistochemistry results showed that Nrf2 was absent in fibroblastic foci (FF) areas, while the SalB treatment could increase the expression of Nrf2 in lung tissues, especially in FF areas.     

Effect of 0.25 ppm ozone exposure on pulmonary damage induced by bleomycin

To study the effect of ozone in a chronically damaged lung, we used a bleomycin (BLM) induced pulmonary fibrosis model. Both endotracheal instillation of BLM and O3 exposure both produce lung inflammation and fibrosis. Oxidative stress would be a common mechanism of damage for both BLM and O3. Our aim was to assess lung injury induced by 5 and 60 days of intermittent exposure to 0.25 ppm O3 in rats with bleomycin-induced pulmonary fibrosis. Thirty-day-old Sprague Dawley rats were endotracheally instilled with BLM (1 U/100 g body weight) and, 30 days later, exposed to 0.25 ppm 03 (0.25 ppm 4 h per day, 5 days a week). Histopatology controls were instilled with saline and breathing room air. Histopathological evaluation of lungs was done 5 and 60 days after O3 exposure. BLM-induced lung damage did not change after 60 days of intermittent O3 exposure. Five days of O3 exposure increased the mean score of BLM-induced pulmonary inflammation and fibrosis (p=0.06). Frequency of bronchopneumonia increased from 1/7 to 6/6 (p <0.001), suggesting that a short-term exposure to O3 in a previously damaged lung might be a risk factor for developing further lung injury.     

IDH2 deficiency exacerbates acetaminophen hepatotoxicity in mice via mitochondrial dysfunction-induced apoptosis

Acetaminophen (APAP)-induced hepatotoxicity is a major factor in liver failure and its toxicity is associated with the generation of reactive oxygen species (ROS), decreased levels of reduced glutathione (GSH) and overall oxidative stress. Mitochondrial NADP⁺-dependent isocitrate dehydrogenase (IDH2) was demonstrated as an essential enzyme for mitochondria to maintain their antioxidant system by generating NADPH, which is an essential reducing equivalent for GSH turnover in mitochondria. Here, we investigated the role of IDH2 in APAP-induced liver injury with IDH2 deficient (idh2^−/−) mice. Hepatotoxicity was promoted through apoptotic cell death following APAP administration in IDH2 deficient hepatocytes compared to that in wild-type hepatocytes. Apoptosis was found to result from the induction of ER stress and mitochondrial dysfunction as shown by the blocking the effect of phenylbutyrate and Mdivi1, respectively. In addition, mito-TEMPO, a scavenger of mitochondrial ROS, was seen to ameliorate APAP-induced hepatotoxicity in idh2^−/− mice. In conclusion, IDH2 deficiency leads to a fundamental shortage of GSH that increases susceptibility to ROS generation and oxidative stress. This leads to excessive mitochondrial dysfunction and ER stress induction in response to APAP administration. Our study provides further evidence that IDH2 has a protective role against APAP-induced liver injury and emphasizes the importance of the elaborate linkages and functions of the antioxidant system in liver health.     

900 MHz pulse-modulated radiofrequency radiation induces oxidative stress on heart, lung, testis and liver tissues

Oxidative stress may affect many cellular and physiological processes including gene expression, cell growth, and cell death. In the recent study, we aimed to investigate whether 900 MHz pulse-modulated radiofrequency (RF) fields induce oxidative damage on lung, heart and liver tissues. We assessed oxidative damage by investigating lipid peroxidation (malondialdehyde, MDA), nitric oxide (NOx) and glutathione (GSH) levels which are the indicators of tissue toxicity. A total of 30 male Wistar albino rats were used in this study. Rats were divided randomly into three groups; control group (n = 10), sham group (device off, n = 10) and 900 MHz pulsed-modulated RF radiation group (n = 10). The RF rats were exposed to 900 MHz pulsed modulated RF radiation at a specific absorption rate (SAR) level of 1.20 W/kg 20 min/day for three weeks. MDA and NOx levels were increased significantly in liver, lung, testis and heart tissues of the exposed group compared to sham and control groups (p < 0.05). Conversely GSH levels were significantly lower in exposed rat tissues (p < 0.05). No significantly difference was observed between sham and control groups. Results of our study showed that pulse-modulated RF radiation causes oxidative injury in liver, lung, testis and heart tissues mediated by lipid peroxidation, increased level of NOx and suppression of antioxidant defense mechanism.     

Comparative cytoprotective effects of carbocysteine and fluticasone propionate in cigarette smoke extract-stimulated bronchial epithelial cells

Cigarette smoke extracts (CSE) induce oxidative stress, an important feature in chronic obstructive pulmonary disease (COPD), and oxidative stress contributes to the poor clinical efficacy of corticosteroids in COPD patients. Carbocysteine, an antioxidant and mucolytic agent, is effective in reducing the severity and the rate of exacerbations in COPD patients. The effects of carbocysteine on CSE-induced oxidative stress in bronchial epithelial cells as well as the comparison of these antioxidant effects of carbocysteine with those of fluticasone propionate are unknown. The present study was aimed to assess the effects of carbocysteine (10⁻⁴ M) in cell survival and intracellular reactive oxygen species (ROS) production (by flow cytometry) as well as total glutathione (GSH), heme oxygenase-1 (HO-1), nuclear-related factor 2 (Nrf2) expression and histone deacetylase 2 (HDAC-2) expression/activation in CSE-stimulated bronchial epithelial cells (16-HBE) and to compare these effects with those of fluticasone propionate (10⁻⁸ M). CSE, carbocysteine or fluticasone propionate did not induce cell necrosis (propidium positive cells) or cell apoptosis (annexin V-positive/propidium-negative cells) in 16-HBE. CSE increased ROS production, nuclear Nrf2 and HO-1 in 16-HBE. Fluticasone propionate did not modify intracellular ROS production, GSH and HDCA-2 but reduced Nrf2 and HO-1 in CSE-stimulated 16-HBE. Carbocysteine reduced ROS production and increased GSH, HO-1, Nrf2 and HDAC-2 nuclear expression/activity in CSE-stimulated cells and was more effective than fluticasone propionate in modulating the CSE-mediated effects. In conclusion, the present study provides compelling evidences that the use of carbocysteine may be considered a promising strategy in diseases associated with corticosteroid resistance.     

Bioconjugates of curcumin display improved protection against glutathione depletion mediated oxidative stress in a dopaminergic neuronal cell line: Implications for Parkinson’s disease

Oxidative stress is implicated in mitochondrial dysfunction associated with neurodegeneration in Parkinson’s disease (PD). Depletion of the cellular antioxidant glutathione (GSH) resulting in oxidative stress is considered as an early event in neurodegeneration. We previously showed that curcumin, a dietary polyphenol from turmeric induced GSH synthesis in experimental models and protected against oxidative stress. Here we tested the effect of three bioconjugates of curcumin (involving diesters of demethylenated piperic acid, valine and glutamic acid) against GSH depletion mediated oxidative stress in dopaminergic neuronal cells and found that the glutamic acid derivative displayed improved neuroprotection compared to curcumin.     

Activities of recombinant human bleomycin hydrolase on bleomycins and engineered analogues revealing new opportunities to overcome bleomycin-induced pulmonary toxicity

The bleomycins (BLMs) are widely used in combination therapies for the treatment of various cancers. Dose-dependent and cumulative pulmonary toxicity is the major cause of BLM-associated morbidity, limiting the broad uses of BLMs as anticancer drugs. The organ specificity of BLM-induced toxicity has been correlated with the expression of the hBLMH gene, encoding the human bleomycin hydrolase (hBLMH), which is poorly expressed in the lung. hBLMH hydrolyzes BLMs into the biologically inactive deamido BLMs, thereby protecting organs from BLM-induced toxicity. Here we report (i) expression of hBLMH and production and isolation of recombinant human bleomycin hydrolase (rhBLMH) from E. coli, (ii) structural characterization of deamido BLM A2 and B2 isolated from rhBLMH-catalyzed hydrolysis of BLM A2 and B2, and (iii) kinetic characterization of the rhBLMH-catalyzed hydrolysis of BLM A2 and B2, in comparison with five BLM analogues. rhBLMH from E. coli catalyzes rapid and efficient hydrolysis of all BLMs tested, exhibiting a superior catalytic efficiency for BLM B2. These findings reveal new opportunities to overcome BLM-induced pulmonary toxicity in chemotherapies, potentially by exploring BLM B2 as the preferred congener, engineering designer BLMs with optimized activity for rhBLMH, or co-administrating rhBLMH directly into the lung as a potential protein therapeutic.     

Curcumin treatment alleviates the effects of glutathione depletion in vitro and in vivo: therapeutic implications for Parkinson's disease explained via in silico studies

Oxidative stress has been implicated in the degeneration of dopaminergic neurons in the substantia nigra (SN) of Parkinson's disease (PD) patients. An important biochemical feature of presymptomatic PD is a significant depletion of the thiol antioxidant glutathione (GSH) in these neurons resulting in oxidative stress, mitochondrial dysfunction, and ultimately cell death. We have earlier demonstrated that curcumin, a natural polyphenol obtained from turmeric, protects against peroxynitrite-mediated mitochondrial dysfunction both in vitro and in vivo. Here we report that treatment of dopaminergic neuronal cells and mice with curcumin restores depletion of GSH levels, protects against protein oxidation, and preserves mitochondrial complex I activity which normally is impaired due to GSH loss. Using systems biology and dynamic modeling we have explained the mechanism of curcumin action in a model of mitochondrial dysfunction linked to GSH metabolism that corroborates the major findings of our experimental work. These data suggest that curcumin has potential therapeutic value for neurodegenerative diseases involving GSH depletion-mediated oxidative stress.     

Cyclophilin A inhibits A549 cell oxidative stress and apoptosis by modulating the PI3K/Akt/mTOR signaling pathway

The excessive and inappropriate production of reactive oxygen species (ROS) can cause oxidative stress and is implicated in the pathogenesis of lung cancer. Cyclophilin A (CypA), a member of the immunophilin family, is secreted in response to ROS. To determine the role of CypA in oxidative stress injury, we investigated the role that CypA plays in human lung carcinoma (A549) cells. Here, we showed the protective effect of human recombinant CypA (hCypA) on hydrogen peroxide (H₂O₂)-induced oxidative damage in A549 cells, which play crucial roles in lung cancer. Our results demonstrated that hCypA substantially promoted cell viability, superoxide dismutase (SOD), glutathione (GSH), and GSH peroxidase (GSH-Px) activities, and attenuated ROS and malondialdehyde (MDA) production in H₂O₂-induced A549 cells. Compared with H₂O₂-induced A549 cells, Caspase-3 activity in hCypA-treated cells was significantly reduced. Using Western blotting, we showed that hCypA facilitated Bcl-2 expression and inhibited Bax, Caspase-3, Caspase-7, and PARP-1 expression. Furthermore, hCypA activates the PI3K/Akt/mTOR pathway in A549 cells in response to H₂O₂ stimulation. Additionally, peptidyl-prolyl isomerase activity was required for PI3K/Akt activation by CypA. The present study showed that CypA protected A549 cells from H₂O₂-induced oxidative injury and apoptosis by activating the PI3K/Akt/mTOR pathway. Thus, CypA might be a potential target for lung cancer therapy.