The effects of erdosteine, N-acetylcysteine, and vitamin E on nicotine-induced apoptosis of pulmonary cells

Identification of Nicotinic Acetylcholine Receptor for N-Acetylcysteine to Rescue Nicotine-induced Injury Using Beating Cilia in Primary Tissue Derived Airway Organoids

Smoking is one of the major contributors to airway injuries. N-acetylcysteine (NAC) has been proposed as a treatment or preventive measure for such injuries. However, the exact nature of the smoking-induced injury and the protective mechanism of NAC are not yet fully understood. Here, patient tissue-derived airway organoids for modeling smoking-induced injury, therapeutic investigation, and mechanism studies are developed. Airway organoids consist mainly of ciliated cells, together with basal cells, goblet cells, and myofibroblast-like cells. The organoids display apical-out and basal-in polarity and are enriched in beating cilia, which are sensitive to smoking challenge and NAC treatment. An algorithm is developed to measure ciliary beating activity by analyzing the altered beating pattern of cilia in response to nicotine challenge and NAC treatment. Nicotinic acetylcholine receptors (nAChRs) expressed by airway organoids are involved in the mechanisms of nicotine-induced injury through the nicotine-nAChR pathway. In contrast to the common understanding that NAC has an antioxidative effect that mitigates airway damage, it is elucidated that NAC binding to nicotine can abolish the binding capacity of nicotine to nAChRs and thus prevent nicotine-induced injury. This study focuses on the advances and potential of humanized organoids in understanding biological processes, mechanisms, and identifying therapeutic targets.

Inhibitory effects of vitamin E on osteocyte apoptosis and DNA oxidative damage in bone marrow hemopoietic cells at early stage of steroid-induced femoral head necrosis

Apoptosis and DNA oxidative damage serve significant roles in the pathogenesis of steroid-induced femoral head necrosis. Vitamin E demonstrates anti-apoptotic and anti-oxidant properties. Therefore, the present study investigated the effects of vitamin E on osteocyte apoptosis and DNA oxidative damage in bone marrow hemopoietic cells at an early stage of steroid-induced femoral head osteonecrosis. Japanese white rabbits were randomly divided into three groups (steroid, vitamin E-treated, and control groups), each comprising 12 rabbits. Those in the steroid group (group S) were initially injected twice with an intravenous dose of 100 µg/kg Escherichia coli endotoxin, with a 24 h interval between the two injections, and then with an intramuscular dose of 20 mg/kg methylprednisolone, three times at intervals of 24 h in order to establish a rabbit model of osteonecrosis. The vitamin E treated group (group E) received the same treatment as group S, and were administered 0.6 g/kg/d vitamin E daily from the beginning of modeling. The control group (group C) was injected with normal saline at the equivalent dosage and times as the aforementioned two groups. Two time points, weeks 4 and 6 following the completion of modeling, were selected. Osteonecrosis was verified by histopathology with hematoxylin-eosin staining. The apoptosis rate of osteonecrosis was analyzed by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The apoptosis expression levels of caspase-3 and B-cell lymphoma 2 (Bcl-2), and DNA oxidative damage of bone marrow hematopoietic cells were analyzed by immunohistochemistry. At weeks 4 and 6 following the completion of modeling, the vacant bone lacunae rates of group E were 15.87±1.97 and 25.09±2.67%, respectively, lower than the results of 20.02±2.21 and 27.79±1.39% for group S; and the osteocyte apoptosis indexes of group E were 20.99±2.95 and 33.93±1.62%, respectively, lower than the results of 26.46±3.37 and 39.90±3.74% from group S. In addition, the Bcl-2 expression at week 4 in the femoral head tissues of group E was higher compared with group S; and the proportion of Bcl-2-positive cells of group E was 9.81±1.01%, higher compared with group S at 8.26±1.13%. The caspase-3 staining data at week 4 in femoral head tissues demonstrated that in the 12 femoral heads of group S, four were negative (32%) and eight were positive (68%); in group E, five were negative (45%) and seven were positive (55%); and in group C, 11 were negative (95%) and one was positive (5%). In addition, the DNA oxidative damage rate at week 4 in the bone marrow hemopoietic cells of group E was (7.24±1.44%), lower compared with group S (11.80±1.26%), and higher compared with group C (5.75±1.47%). Vitamin E is effective in intervening in apoptosis through decreasing caspase-3 expression and upregulating Bcl-2 expression, and by alleviating DNA oxidative damage in bone marrow hemopoietic cells at the early stage of steroid-induced femoral head necrosis in rabbit models.

Expression Changes of Apoptotic Genes in Tissues from Mice Exposed to Nicotine

Objective:

Smoking is the leading preventable cause of various diseases such as lung cancer, chronic obstructive pulmonary disease and cardiovascular disease. Nicotine, one of the major toxic components of tobacco, contributes to the pathogenesis of different diseases.

Methods:

Given the controversy about nicotine toxicity, the present study was conducted to determine apoptotic effects of nicotine on the heart, kidney, lung and liver of male mice. Real-time PCR was performed to identify mRNA expression changes in apoptotic-related genes between nicotine treated and control mice.

Result:

In the heart and lung, nicotine caused significant decrease in P53, Bax and Caspase-3 mRNA expression levels compared to the control group. However, in the kidney and liver, the result was significant increase in Bax, Caspase-2, Caspase-3 and a significant decrease in P53 mRNA expression (p<0.01). DNA fragmentation assays indicated no fragmentation in the heart and lung, but in the kidney and liver of nicotine treated mice, isolated DNA was fragmented.

Conclusion:

Our study provided insight into the molecular mechanisms of nicotine anti-apoptotic effects on the heart and lung as well as pro-apoptotic effects on kidney and liver via a P53-independent pathway.

Investigation of the protective effect of ellagic acid for preventing kidney injury in rats exposed to nicotine during the fetal period

We investigated the possible protective effects of ellagic acid on rat kidneys exposed to nicotine during the fetal period. Twenty pregnant female rats were divided randomly into four groups: control (C), nicotine (N), ellagic acid (EA) and nicotine + ellagic acid (N + EA). Nicotine and ellagic acid treatments were continued throughout the pregnancies and for 15 days after delivery. On day 15, all neonatal pups were sacrificed and their kidneys were removed for biochemical and histopathological examination. The nicotine treatment significantly decreased body weight, total glutathione (GSH), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities, and increased malondialdehyde (MDA) and nitric oxide (NO) levels in the N group compared to controls. EA treatment ameliorated decreased body weight, GSH, GSH-Px and SOD activities, and increased MDA and NO levels in group N + EA compared to group N (p < 0.05). Nicotine caused kidney damage as shown by incomplete development of glomeruli and Bowman's capsules. Nicotine also caused greater apoptosis in group N compared to group C. Ellagic acid treatment produced histological kidney structure that was closer to normal and it exerted an anti-apoptotic effect in the N + EA group compared to the N group. EA played a protective role against nicotine-induced nephrotoxicity and oxidative stress in rats owing to its antioxidant, radical scavenging and anti-apoptotic effects.

Nicotine mediates oxidative stress and apoptosis through cross talk between NOX1 and Bcl-2 in lung epithelial cells

Nicotine contributes to the onset and progression of several pulmonary diseases. Among the various pathophysiological mechanisms triggered by nicotine, oxidative stress and cell death are reported in several cell types. We found that chronic exposure to nicotine (48h) induced NOX1-dependent oxidative stress and apoptosis in primary pulmonary cells. In murine (MLE-12) and human (BEAS-2B) lung epithelial cell lines, nicotine acted as a sensitizer to cell death and synergistically enhanced apoptosis when cells were concomitantly exposed to hyperoxia. The precise signaling pathway was investigated in MLE-12 cells in which NOX1 was abrogated by a specific inhibitor or stably silenced by shRNA. In the early phase of exposure (1h), nicotine mediated intracellular Ca(2+) fluxes and activation of protein kinase C, which in its turn activated NOX1, leading to cellular and mitochondrial oxidative stress. The latter triggered the intrinsic apoptotic machinery by modulating the expression of Bcl-2 and Bax. Overexpression of Bcl-2 completely prevented nicotine's detrimental effects, suggesting Bcl-2as a downstream key regulator in nicotine/NOX1-induced cell damage. These results suggest that NOX1 is a major contributor to the generation of intracellular oxidative stress induced by nicotine and might be an important molecule to target in nicotine-related lung pathologies.

The role of N-acetyl-cysteine in the lung remote injury after hepatic ischemia and reperfusion in rabbits

PURPOSE: To study the lesions in the lung of rabbits caused by ischemia/reperfusion hepatic (I/R) after the use of N-acetyl-cysteine (NAC). METHODS: Twenty-four rabbits distributed in two groups: control group GI (n = 12) 5% glucose solution and experiment group GII (n = 12) NAC. The animals were pre-anesthetized with 1% acepromazine maleate and anesthetized with ketamine 10% and 2% xylazine intramuscularly. The GI and GII were given glucose solution intravenously or NAC 15min before occlusion of the hepatic pedicle (30 min). After the period of reperfusion of 24h (n = 6) or 48h (n = 6), liver and lung samples were collected for histology and immunohistochemistry to assess the impairment of cell. RESULTS: The animals of GII and GII-24h-48h showed parenchyma liver close to normal, when using NAC. The GII and GII-24h-48h showed lower thickness of alveolar cells that GI and GI-24h-48h. The expression of caspase 3 in lung cells GII presented smaller value compared to the GI group. CONCLUSION: N-acetyl-cysteine administered 15min prior to the injury ischemia/reperfusion had a significant protective role by minimizing lung injury and apoptotic morphology in the period observed.

Analysis of nicotine-induced DNA damage in cells of the human respiratory tract

Epithelium of the upper and lower airways is a common origin of tobacco-related cancer. The main tobacco alkaloid nicotine may be associated with tumor progression. The potential of nicotine in inducing DNA mutations as a step towards cancer initiation is still controversially discussed. Different subtypes of nicotinic acetylcholine receptors (nAChR) are expressed in human nasal mucosa and a human bronchial cell line representing respiratory mucosa as a possible target for receptor-mediated pathways. In the present study, both cell systems were investigated with respect to DNA damage induced by nicotine and its mechanisms. Specimens of human nasal mucosa were harvested during surgery of the nasal air passage. After enzymatic digestion over night, single cells were exposed to an increasing nicotine concentration between 0.001 mM and 4.0mM. In a second step co-incubation was performed using the antioxidant N-acetylcysteine (NAC) and the nAChR antagonist mecamylamine. DNA damage was assessed using the alkali version of the comet assay. Dose finding experiments for mecamylamine to evaluate the maximal inhibitory effect were performed in the human bronchial cell line BEAS-2B with an increasing mecamylamine concentration and a constant nicotine concentration. The influence of nicotine in the apoptotic pathway was evaluated in BEAS-2B cells with the TUNEL assay combined with flow cytometry. After 1h of nicotine exposure with 0.001, 0.01, 0.1, 1.0 and 4.0mM, significant DNA damage was determined at 1.0mM. Further co-incubation experiments with mecamylamine and NAC were performed using 1.0mM of nicotine. The strongest inhibitory effect was measured at 1.0mM mecamylamine and this concentration was used for co-incubation. Both, the antioxidant NAC at a concentration of 1.0mM, based on the literature, as well as the receptor antagonist were capable of complete inhibition of the nicotine-induced DNA migration in the comet assay. A nicotine-induced increase or decrease in apoptosis as assessed by the TUNEL assay in BEAS-2B could not be detected. These results support the hypothesis that oxidative stress is responsible for nicotine-induced DNA damage. Similar results exist for other antioxidants in different cell systems. The decrease in DNA damage after co-incubation with a nAChR antagonist indicates a receptor-dependent pathway of induction for oxidative stress. Further investigations concerning pathways of receptor-mediated DNA damage via nAChR, the role of reactive oxygen species and apoptosis in this cell system will elucidate underlying mechanisms.

Estradiol pretreatment attenuated nicotine-induced endothelial cell apoptosis via estradiol functional membrane receptor

Cigarette smoking is highly associated with increased cardiovascular disease complications. The female population, however, manifests reduced cardiovascular morbidity. We define nicotine's effect upon human umbilical vein endothelial cells (HUVECs), determine whether estradiol might ameliorate endothelial dysfunction via its membrane estrogen receptor (mER), and attempt to elucidate the underlying mechanisms. Endothelial cells were pretreated with estradiol-BSA and measured resultant ion flux across the cells via the patch clamp technique to assess mER is functionality. Estradiol-BSA administration was associated with 30% decreased nicotine-induced apoptosis and also attenuated nicotine-activated phosphorylation of p38 and ERK. Pretreatment of estradiol-BSA triggered a low calcium influx, suggesting ahead low influx calcium played a critical role in the underlying protective mechanisms of estradiol. Furthermore, this estradiol-BSA protection against apoptosis remained effective in the presence of tamoxifen, an intracellular estrogen receptor (iER) inhibitor. Additionally, tamoxifen did not abolish estradiol-BSA's inhibitory effect upon p38 and ERK's activation, giving evidence to the obligatory role of p38 and ERK signaling in the estradiol-BSA's anti-apoptotic action via mER. Our study provides evidence that nicotine enhances endothelial cell apoptosis, but estrogen exerts anti-apoptotic effect through its functional membrane estrogen receptor. Clinically, the nicotine in cigarettes might contribute to endothelial dysfunction, whereas ambient estradiol may provide cellular protection against nicotine-induced injury through its functional membrane receptor via MAPK pathway downregulation.

Cell proliferation kinetics and genotoxicity in lymphocytes of smokers living in Mexico City

Genotoxicity caused by tobacco smoke was assessed in peripheral blood lymphocytes of smokers living in Mexico City by determining sister chromatid exchange (SCE), cell proliferation kinetics (CPK), replication index (RI) and mitotic index (MI). Nicotine levels, and its major metabolite cotinine, were also estimated in urine samples using gas-chromatography-mass spectrometry to quantify smoking intensity. The outcome of the analysis and the comparison of the 77-smoker group with a non-smoking control group showed that moderate and heavy smokers exhibited significant differences (P < 0.001 and P < 0.05, respectively) in CPK, with an underlying delay in the cellular cycle; similarly, RI was significantly different in these groups (P < 0.001 and P < 0.0001, respectively). There were significant correlations (P < 0.05) between age and number of years the subject had been smoking, as well as between RI and nicotine and cotinine levels and between CPK (M1, M2 and M3) and nicotine and cotinine levels. Smokers were classified for the analysis according to the nicotine levels (it is in relation to number of cigarettes smoked per day) found in urine (ng/mL) as: light (10-250), moderate (251-850) and heavy (851-4110). Significant differences in CPK were found (P < 0.05) between moderate and heavy smokers and non-smokers. Significant differences in RI were found between moderate (P < 0.001) and heavy smokers (P < 0.0001) and non-smokers, but not for the light smoking group. MI was determined in 57 of the smokers, whereas SCE frequency was only recorded in 34 smokers. Both parameters yielded no significant differences, nor correlations with any of the assessed variables. In conclusion, cytokinetic and cytostatic effects were mainly detected in heavy and moderate smokers. Cell cycle delay and RI decrease were found in all ;healthy' smokers. The nicotine and cotinine exposure (causing oxidative damage to DNA) may have implications in the decrease in cell replication due to direct damage to DNA and/or a decrease in the DNA repair mechanisms. Alternatively, nicotine and cotinine may possibly induce apoptosis.

Differential induction of heme oxygenase-1 against nicotine-induced cytotoxicity via the PI3K, MAPK, and NF-kappa B pathways in immortalized and malignant human oral keratinocytes

BACKGROUND

Heme oxygenase-1 (HO-1) exhibits cytoprotective effects in many different cell types and is induced by nicotine exposure in human gingival fibroblasts. However, the role of HO-1 in cancer cells exposed to nicotine has not previously been described.

METHODS

We investigated the effects of nicotine on HO-1 protein expression and cell viability in immortalized (IHOK) and malignant (HN12) human oral keratinocyte cells using the 3,4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide assay and Western blotting. We also examined the involvement of the phosphoinositide-3-kinase (PI3K), mitogen-activated protein kinase (MAPK), and nuclear factor-kappaB (NF-kappaB) signaling pathways in nicotine-induced cytotoxicity and HO-1 levels in IHOK and HN12 cells.

RESULTS

Nicotine-induced HO-1 production and had cytotoxic effects on cells in both a concentration- and time-dependent manner. Nicotine-induced cytotoxicity and accumulation of HO-1 were greater in IHOK cells than in HN12 cells. Molecular inhibitors of the ERK, p38 MAP kinase, PI3 K, and NF-kappaB signaling pathways blocked the cytotoxic effects and induction of HO-1 expression by nicotine. Treatment with antioxidants (bilirubin, N-acetylcysteine) protected cells against nicotine-induced cytotoxicity and blocked the upregulation of HO-1, the effects of which were more pronounced in IHOK cells than in HN12 cells.

CONCLUSIONS

Collectively, these results suggest that HO-1 plays a principal role in the protective response to nicotine in oral cancer and immortalized keratinocytes. Moreover, the addition of exogenous antioxidants may help to protect oral epithelial cells as chemopreventive agents against nicotine-induced oxidative stress.

Nicotine and apoptosis

Cigarette smoking is associated with a plethora of different diseases. Nicotine is the addictive component of cigarette but also acts onto cells of the non-neuronal system, including immune effector cells. Although nicotine itself is usually not referred to as a carcinogen, there is ongoing debate whether nicotine functions as a 'tumor enhancer.' By binding to nicotinic acetylcholine receptors, nicotine deregulates essential biological processes like angiogenesis, apoptosis, and cell-mediated immunity. Apoptosis plays critical roles in a wide variety of physiologic processes during fetal development and in adult tissue and is also a fundamental aspect of the biology of malignant diseases. This review provides an overlook how nicotine influences apoptotic processes and is thus directly involved in the etiology of pathological conditions like cancer and obstructive diseases.

Erdosteine prevents colonic inflammation through its antioxidant and free radical scavenging activities

After intracolonic administration of trinitrobenzene sulphonic acid (TNBS), Sprague-Dawley rats were treated orally either with saline or erdosteine (100 mg/kg per day), a sulfhydryl-containing antioxidant, for 3 days. On the 4th day, rats were decapitated and distal colon was removed for the macroscopic and microscopic damage scoring, for the measurement of malondialdehyde (MDA), glutathione (GSH) and collagen levels, myeloperoxidase (MPO) activity, luminol and lucigenin chemiluminescence (CL) and DNA fragmentation. Lactate dehydrogenase (LDH) activity, tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, and antioxidant capacity were assayed in blood samples. Colitis caused significant increases in the colonic CL values, macroscopic and microscopic damage scores, MDA and collagen levels, MPO activity and DNA fragmentation, along with a significant decrease in tissue GSH level. Similarly, serum cytokines and LDH were elevated in the saline-treated colitis group as compared with the control group. On the other hand, erdosteine treatment reversed all these biochemical indices, and histopathologic alterations induced by TNBS, suggesting that erdosteine protects the colonic tissue via its radical scavenging and antioxidant activities.

An overview of erdosteine antioxidant activity in experimental research

Erdosteine was introduced in the market as a mucolytic agent for chronic pulmonary diseases more than 10 years ago. The drug contains two blocked sulphydryl groups one of which, after hepatic metabolization and opening of the thiolactone ring, becomes available both for the mucolytic and free radical scavenging and antioxidant activity too. There are several experimental evidences which support the protective effect of erdosteine in acute injury induced by a variety of pharmacological or noxious agents, mediated by products of oxidative stress. Experimental data in animal assigned to receive the noxious agent evidence that co-treatment with erdosteine increases the tissue antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase, compared with the toxic agent alone; meanwhile erdosteine decreases the tissue level of nitric oxide, xanthine oxidase, which catalyze oxygen-free radical production. In summary, erdosteine prevents the accumulation of free oxygen radicals when their production is accelerated and increases antioxidant cellular protective mechanisms. The final result is a protective effect on tissues which reduces lipid peroxidation, neutrophil infiltration or cell apoptosis mediated by noxious agents. Recent positive clinical trials in humans seem to fulfill the impressive promises that theory and experimental research have put forward.

Erdosteine treatment attenuates oxidative stress and fibrosis in experimental biliary obstruction

Oxidative stress, in particular lipid peroxidation, induces collagen synthesis and causes fibrosis. The aim of this study was to assess the antioxidant and antifibrotic effects of erdosteine on liver fibrosis induced by biliary obstruction in rats. Liver fibrosis was induced in Wistar albino rats by bile duct ligation (BDL). Erdosteine (10 mg/kg, orally) or saline was administered for 28 days. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) levels were determined to assess liver functions and tissue damage, respectively. Pro-inflammatory cytokines, TNF-alpha, IL-1beta and IL-6 and antioxidant capacity (AOC) were assayed in plasma samples. Liver tissues were taken for determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and collagen content. Production of reactive oxidants was monitored by chemiluminescence assay. Serum AST, ALT, LDH, and plasma cytokines were elevated in the BDL group as compared to controls and were significantly decreased by erdosteine treatment. Hepatic GSH level and plasma AOC, depressed by BDL, were elevated back to control level with erdosteine treatment. Furthermore, hepatic luminol and lucigenin chemiluminescence (CL), MDA level, MPO activity and collagen content in BDL group increased dramatically compared to control and reduced by erdosteine treatment. Since erdosteine administration alleviated the BDL-induced oxidative injury of the liver and improved the hepatic functions, it seems likely that erdosteine with its antioxidant and antifibrotic properties, may be of potential therapeutic value in protecting the liver fibrosis and oxidative injury due to biliary obstruction.

Vitamin E and Apoptosis

Vitamin E is a generic term that refers to a family of compounds that is further divided into two subgroups called tocopherols and tocotrienols. All natural forms of tocopherols and tocotrienols are potent antioxidants that regulate peroxidation reactions and controls free radical production within the body. However, it is now firmly established that many of the biological actions mediated by individual vitamin E isoforms are not dependent on their antioxidant activity. Furthermore, synthetic ether derivatives of vitamin E that no longer possess antioxidant activity also display a wide range of biological activities. One of the most intriguing therapeutic applications for natural vitamin E and vitamin E derivatives currently being investigated is their use as anticancer agents. Specific forms of vitamin E display potent apoptotic activity against a wide range of cancer cell types, while having little or no effect on normal cell function or viability. Experimental studies have also determined that the intracellular mechanisms mediating the apoptotic effects of specific vitamin E compounds display great diversity in different types of caner cells and has been found to restore multidrug resistant tumor cells sensitivity to chemotherapeutic agents. These findings strongly suggest that some natural and synthetic analogues of vitamin E can be used effectively as anticancer therapy either alone or in combination to enhance the therapeutic efficacy and reduce toxicity of other anticancer agents.

Effects of oral alpha-tocopherol on lung response in rat model of allergic asthma

OBJECTIVE AND BACKGROUND

Asthma is a chronic inflammatory disease in which an oxidant/antioxidant imbalance plays an important role. d-alpha-tocopherol (biologically the most active form of vitamin E) has redox properties and by scavenging the free radicals can act as an antioxidant. The aim of this study was to examine the effects of orally administered alpha-tocopherol in a rat model of allergic asthma.

METHODOLOGY

Actively sensitized rats (OA) were treated with alpha-tocopherol (400 mg/kg/day for 10 days) or vehicle; 1 h after the last dose, they were challenged with antigen aerosol. The antigen-induced airway hyperresponsiveness to direct bronchoconstrictor (serotonin), the inflammatory cell infiltrate and histological changes were determined 1 or 24 h after the antigen challenge.

RESULTS

Alpha-tocopherol pretreatment was not significantly effective at reducing the studied parameters when compared with controls, even though there was a tendency to a reduction in bronchial responsiveness and in eosinophil and neutrophil infiltration.

CONCLUSION

Alpha-tocopherol when administered in the chosen study design in an animal model of asthma had no major effect on airway inflammation. The effect of antioxidants deserves further evaluation.