Increase In Oxidative DNA Damage Research Articles

Under pressure-exploring partner changes, physiological responses and telomere dynamics in northern gannets across varying breeding conditions.

Life history theory predicts trade-offs between reproduction and survival in species like the northern gannet (Morus bassanus). During breeding, demanding foraging conditions lead them to expand their foraging range and diversify their diet, increasing the risk of reproductive failure. Changing partners may enhance breeding success but lead to more physiological costs. To investigate the physiological costs of reproduction upon partner changes, we measured and compared 21 biomarkers related to telomere dynamics, oxidative stress, inflammation, hematology, nutritional status, and muscle damage. We used a longitudinal approach with gannets (n=38) over three contrasting years (2017, 2018 and 2019). Our results suggest that annual breeding conditions exert a greater influence on physiological changes than partnership status. Individuals that changed partner experienced greater short-term stress than retained partners. This transient increase in stress was marked by short-term increases in oxidative lipid damage, lower antioxidant capacity, signs of inflammation, and greater weight loss than individuals that retained partners. During favorable conditions, individuals that changed mates had stabilized telomere length, decreased antioxidant capacity, glucose concentration, and muscle damage, along with increased oxygen transport capacity. Conversely, unfavorable breeding conditions led to increased telomere attrition, stabilized antioxidant capacity, decreased inflammation susceptibility, diminished oxygen transport capacity, and increased muscle damage. In the cases where partners were retained, distinct physiological changes were observed depending on the year's conditions, yet the telomere dynamics remained consistent across both partnership status categories. During the favorable year, there was an increase in unsaturated fatty acids and oxygen transport capacity in the blood, coupled with a reduction in inflammation potential and protein catabolism. In contrast, during the unfavorable year in the retained mates, we observed an increase in oxidative DNA damage, antioxidant capacity, weight loss, but a decrease in inflammation susceptibility as observed in changed mates. Our study shows that behavioral flexibility such as mate switching can help seabirds cope with the challenges of food scarcity during reproduction, but these coping strategies may have a negative impact on physiological status at the individual level. In addition, the marked reduction in telomere length observed during harsh conditions, coupled with the stabilization of telomere length in favorable conditions, highlights the long-term physiological impact of annual breeding conditions on seabirds. These findings underscore the effect on their potential survival and fitness, emphasizing that the influence of annual breeding conditions is greater than that of partnership status.

Failure to repair endogenous DNA damage in β-cells causes adult-onset diabetes in mice.

Age is the greatest risk factor for the development of type 2 diabetes mellitus (T2DM). Age-related decline in organ function is attributed to the accumulation of stochastic damage, including damage to the nuclear genome. Islets of T2DM patients display increased levels of DNA damage. However, whether this is a cause or consequence of the disease has not been elucidated. Here, we asked if spontaneous, endogenous DNA damage in β-cells can drive β-cell dysfunction and diabetes, via deletion of Ercc1, a key DNA repair gene, in β-cells. Mice harboring Ercc1-deficient β-cells developed adult-onset diabetes as demonstrated by increased random and fasted blood glucose levels, impaired glucose tolerance, and reduced insulin secretion. The inability to repair endogenous DNA damage led to an increase in oxidative DNA damage and apoptosis in β-cells and a significant loss of β-cell mass. Using electron microscopy, we identified β-cells in clear distress that showed an increased cell size, enlarged nuclear size, reduced number of mature insulin granules, and decreased number of mitochondria. Some β-cells were more affected than others consistent with the stochastic nature of spontaneous DNA damage. Ercc1-deficiency in β-cells also resulted in loss of β-cell function as glucose-stimulated insulin secretion and mitochondrial function were impaired in islets isolated from mice harboring Ercc1-deficient β-cells. These data reveal that unrepaired endogenous DNA damage is sufficient to drive β-cell dysfunction and provide a mechanism by which age increases the risk of T2DM.

Development of a model for studying the developmental consequences of oxidative sperm DNA damage by targeting redox-cycling naphthoquinones to the Sertoli cell population.

Oxidative stress can be induced in the testes by a wide range of factors, including scrotal hyperthermia, varicocele, environmental toxicants, obesity and infection. The clinical consequences of such stress include the induction of genetic damage in the male germ line which may, in turn, have serious implications for the health and wellbeing of the progeny. In order to confirm the transgenerational impact of oxidative stress in the testes, we sought to develop an animal model in which this process could be analysed. Our primary approach to this problem was to induce Sertoli cells (robust, terminally differentiated, tissue-specific testicular cells whose radioresistance indicates significant resistance to oxidative stress) to generate high levels of reactive oxygen species (ROS) within the testes. To achieve this aim, six follicle-stimulating hormone (FSH) peptides were developed and compared for selective targeting to Sertoli cells both in vitro and in vivo. Menadione, a redox-cycling agent, was then conjugated to the most promising FSH candidate using a linker that had been optimised to enable maximum production of ROS in the targeted cells. A TM4 Sertoli cell line co-incubated with the FSH-menadione conjugate in vitro exhibited significantly higher levels of mitochondrial ROS generation (10-fold), lipid peroxidation (2-fold) and oxidative DNA damage (2-fold) than the vehicle control. Additionally, in a proof-of-concept study, ten weeks after a single injection of the FSH-menadione conjugate in vivo, injected male mice were found to exhibit a 1.6 fold increase in DNA double strand breaks and 13-fold increase in oxidative DNA damage to their spermatozoa while still retaining their ability to initiate a pregnancy. We suggest this model could now be used to study the influence of chronic oxidative stress on testicular function with emphasis on the impact of DNA damage in the male germ line on the mutational profile and health of future generations.

Perturbations in indices of oxidative stress, oxidative DNA damage and lung function in chronic exposure to wood dust in Southern Nigeria

Objectives Oxidative stress (OS) and oxidative DNA damage accruing from chronic exposure to wood dust have been implicated in the development of chronic lung conditions among woodworkers. Indices of OS, inflammation, oxidative DNA damage and lung function in relation to duration of exposure to wood dust were assessed in woodworkers to determine their possible utility as risk evaluation indices for chronic lung conditions. Methods Ninety participants comprising 30 active woodworkers, 30 passive woodworkers, and 30 controls were enrolled into this cross-sectional study. The total plasma peroxides, total antioxidant capacity (TAC), oxidative stress index (OSI), malondialdehyde (MDA), reduced glutathione, nitric oxide, high sensitivity C-reactive protein (hs-CRP), 8-hydroxy-2′-deoxyguanosine (8-OHdG) and peak expiratory flow rate (PEFR) were determined in all participants. Results Woodworkers had lower PEFR, TAC, and higher malondialdehyde, OSI, hs-CRP, and 8-OHdG compared to controls (p < 0.05). Active woodworkers had higher malondialdehyde, 8-OHdG, and hs-CRP compared to passive woodworkers (p < 0.05). Increasing duration of exposure to wood dust is associated with higher malondialdehyde, hs-CRP, and 8-OHdG in active woodworkers (p < 0.05) and higher 8-OHdG and hs-CRP in passive woodworkers (p < 0.05). Negative correlation was observed between hs-CRP and TAC (r=−0.367, p = 0.048) in active workers. Conclusion The association of exposure to wood dust with elevated indices of inflammation, OS, lipid peroxidation, oxidative DNA damage, and reduction in antioxidants and peak expiratory flow rate; and the concomitant increase in oxidative DNA damage and inflammation with increasing duration of exposure suggest that these indices may be useful in predicting woodworkers at risk of development of chronic lung conditions.

#2629 ROS-SCAVENGING BLOCKS GLUCOSE INDUCED OXIDATIVE PERITONEAL CELL DAMAGE IN VITRO

Abstract Background and Aims Peritoneal dialysis (PD) is an effective method of renal replacement therapy (RRT). The long-term use of PD as RRT is limited due to adverse effects of high glucose-based PD fluids (PDFs) to the structure and function of the peritoneal membrane. Our group recently elucidated one pathological mechanism showing that glucose-based PDFs enhance oxidative DNA-damage in PD patients due to reduced thioredoxin (TRX) activity trigged by thioredoxin-interacting-protein (TXNIP) upregulation (Oberacker et al., 2022). Therefore, the aim of this in vitro study was to investigate drug treatments to mitigate oxidative stress and oxidative DNA-damage due to glucose-dependent induction of TXNIP expression. Method Using a mesotheliomal cell line (NCl-H28, ATCC) we performed in vitro studies mitigating reactive oxygen species (ROS) production and oxidative DNA damage as well. Cells were treated for three and eight hours with high-glucose media (1.5%, 2.3% and 4.25% glucose; glucose concentrations were adapted to PDFs from Fresenius Medical Care) compared to control media (normal glucose concentration). mRNA expression of TXNIP, TRX and further redox-related genes like superoxide dismutases (SODs) or catalase were analyzed by qPCR. Since TRX is negatively regulated by TXNIP, we investigated TRX activity in cell lysates. ROS production was monitored using a bioluminescent assay and immunofluorescence using the redox dye CellRoxGreen as well. The content of oxidative DNA-damage was investigated by immunofluorescence. Furthermore, we have preliminary analysis using primary human peritoneal mesothelial cells derived from PD effluent (PDF). Results We demonstrated a dose-dependent upregulation of round 1.5 fold TXNIP expression on mRNA level. However, no change in the expression of TRX, SODs and catalase could be observed. Interestingly, we observed a 20% reduction in TRX activity upon glucose stimulation compared to cells treated with control media. These findings are consistent with the previously published data on human peritoneal biopsies. Beyond, we demonstrated a dose-dependent increase in ROS production and increase in oxidative DNA-damage. However, ROS production and oxidative DNA damage could be prevented upon pre-incubation with the ROS-scavenger N-acetylcysteine (NAC). Conclusion Here, we show that enhanced levels of ROS and oxidative DNA damage due to glucose induced TXNIP expression could be diminished using ROS scavengers. These findings show that further antioxidative substances may be potential drugs, which could also be potential drug candidates for use in clinical practice to treat PD patients.

Risk of Pulmonary-Reproductive Dysfunctions, Inflammation and Oxidative DNA Damage in Exposure to Polycyclic Aromatic Hydrocarbon in Cigarette Smokers.

Background: Exposure to cigarette smoke has been associated with pulmonary and reproductive dysfunctions; inflammatory response, oxidative stress and oxidative DNA damage induced by polycyclic aromatic hydrocarbons (PAHs) present in cigarette smoke have been implicated in the pathogenesis of these disorders. The peak expiratory flow rate (PEFR), a biomarker of inflammation and oxidative DNA damage (8-hydroxy-2-deoxyguanosine (8-OHdG), tumor necrosis factor alpha (TNF-α)), reproductive hormones (testosterone (TST), luteinizing hormone (LH), follicle stimulating hormone (FSH)) cotinine and urinary PAH metabolite (1-hydroxypyrene (1-HOP)) were estimated in male active smokers. Methods: One hundred men aged 20-47 years, comprising 50 active male smokers and 50 non-smokers, were randomly recruited into this comparative cross-sectional study. The PEFR was measured using a peak flow meter, serum levels of cotinine, FSH, LH, TST, TNF-α, and urine 8-OHdG by enzyme-linked immunosorbent assay and 1-HOP by high-performance liquid chromatography. Data analysis was done using a t-test and correlation analysis at p≤0.05. Results: Smokers had significantly higher cotinine (49.73±31.76 versus 0.51±0.69 ng/ml, p≤0.001), 8-OHdG (16.34±12.10 versus 5.79±2.14 ng/ml, p≤0.001) and lower PEFR (309.20±56.05 versus 452.80±45.76 L/min, p≤0.001) and LH (5.75±2.06 versus 6.97±2.79 mIU/ml, p=0.015) compared to non-smokers. Duration of exposure to cigarette smoke correlated positively with cotinine (r=0.937, p≤0.001) and 1-HOP (r=0.813, p≤0.001) while cotinine correlated positively with 1-HOP (r=0.863, p≤0.001) only in smokers. Conclusion: Reduced lung function and luteinizing hormone and concurrent increase in oxidative DNA damage associated with exposure to cigarette smoke may suggest the involvement of PAH-induced DNA damage in the development of pulmonary and reproductive impairment in smokers.

Monitoring DNA polymerase β mitochondrial localization and dynamics

Mouse fibroblasts lacking (null) DNA polymerase β (pol β) were transfected with fluorescently tagged pol β and stained with biomarkers to allow visualization within living cells by confocal microscopy. Transient transfection resulted in varying pol β expression levels. Separating cells into three groups based on pol β fluorescence intensity and morphological distribution, permitted analysis of the concentration dependence and spatial distribution of cytoplasmic pol β. Colocalization between pol β and mitochondria was pol β concentration dependent. A decrease in overlap with nucleoids containing mitochondrial DNA (mtDNA) was observed at the highest pol β intensity where pol β exhibits a tubular appearance, suggesting the ability to load elevated levels of pol β into mitochondria readily available for relocation to damaged mtDNA. The dynamics of pol β and mitochondrial nucleoids were followed by confocal recording of time series images. Two populations of mitochondrial nucleoids were observed, with and without pol β. Micro-irradiation, known to form DNA single-strand breaks, in a line across nucleus and cytoplasm of pol β stably transfected cells enhanced apparent localization of pol β with mitochondria in the perinuclear region of the cytoplasm near the nuclear membrane. Exposure of pol β expressing cells to H2O2 resulted in a time-dependent increase in cytoplasmic pol β observed by immunofluorescence analysis of fixed cells. Further screening revealed increased levels of colocalization of pol β with a mitochondrial probe and an increase in oxidative DNA damage in the cytoplasm. ELISA quantification confirmed an increase of an oxidative mitochondrial base lesion, 7,8-dihydro-8-oxoguanine, after H2O2 treatment. Taken together, the results suggest that pol β is recruited to mitochondria in response to oxidatively-induced mtDNA damage to participate in mtDNA repair.

The Relationship between Exposure to Airborne Particulate and DNA Adducts in Blood Cells in an Urban Population of Subjects with an Unhealthy Body Mass Index.

Bulky DNA adducts are a combined sign of aromatic chemical exposure, as well as an individual’s ability to metabolically activate carcinogens and repair DNA damage. The present study aims to investigate the association between PM exposure and DNA adducts in blood cells, in a population of 196 adults with an unhealthy BMI (≥25). For each subject, a DNA sample was obtained for quantification of DNA adducts by sensitive32P post-labelling methods. Individual PM10 exposure was derived from daily mean concentrations measured by single monitors in the study area and then assigned to each subject by calculating the mean of the 30 days (short-term exposure), and of the 365 (long-term exposure) preceding enrolment. Multivariable linear regression models were used to study the association between PM10 and DNA adducts. The majority of analysed samples had bulky DNA adducts, with an average value of 3.7 ± 1.6 (mean ± SD). Overall, the findings of the linear univariate and multiple linear regression showed an inverse association between long-term PM10 exposure and adduct levels; this unexpected result might be since the population consists of subjects with an unhealthy BMI, which might show an atypical reaction to airborne urban pollutants; a hermetic response which happens when small amounts of pollutants are present. Pollutants can linger for a long time in the adipose tissue of obese persons, contributing to an increase in oxidative DNA damage, inflammation, and thrombosis when exposure is sustained.

Genotoxicity and Gene Expression in the Rat Lung Tissue following Instillation and Inhalation of Different Variants of Amorphous Silica Nanomaterials (aSiO2 NM).

Several reports on amorphous silica nanomaterial (aSiO2 NM) toxicity have been questioning their safety. Herein, we investigated the in vivo pulmonary toxicity of four variants of aSiO2 NM: SiO2_15_Unmod, SiO2_15_Amino, SiO2_7 and SiO2_40. We focused on alterations in lung DNA and protein integrity, and gene expression following single intratracheal instillation in rats. Additionally, a short-term inhalation study (STIS) was carried out for SiO2_7, using TiO2_NM105 as a benchmark NM. In the instillation study, a significant but slight increase in oxidative DNA damage in rats exposed to the highest instilled dose (0.36 mg/rat) of SiO2_15_Amino was observed in the recovery (R) group. Exposure to SiO2_7 or SiO2_40 markedly increased oxidative DNA lesions in rat lung cells of the exposure (E) group at every tested dose. This damage seems to be repaired, since no changes compared to controls were observed in the R groups. In STIS, a significant increase in DNA strand breaks of the lung cells exposed to 0.5 mg/m3 of SiO2_7 or 50 mg/m3 of TiO2_NM105 was observed in both groups. The detected gene expression changes suggest that oxidative stress and/or inflammation pathways are likely implicated in the induction of (oxidative) DNA damage. Overall, all tested aSiO2 NM were not associated with marked in vivo toxicity following instillation or STIS. The genotoxicity findings for SiO2_7 from instillation and STIS are concordant; however, changes in STIS animals were more permanent/difficult to revert.

Toxicity assessment of industrial engineered and airborne process-generated nanoparticles in a 3D human airway epithelial in vitro model

The advanced ceramic technology has been pointed out as a potentially relevant case of occupational exposure to nanoparticles (NP). Not only when nanoscale powders are being used for production, but also in the high-temperature processing of ceramic materials there is also a high potential for NP release into the workplace environment. In vitro toxicity of engineered NP (ENP) [antimony tin oxide (Sb2O3•SnO2; ATO); zirconium oxide (ZrO2)], as well as process-generated NP (PGNP), and fine particles (PGFP), was assessed in MucilAir™ cultures at air–liquid interface (ALI). Cultures were exposed during three consecutive days to varying doses of the aerosolized NP. General cytotoxicity [lactate dehydrogenase (LDH) release, WST-1 metabolization], (oxidative) DNA damage, and the levels of pro-inflammatory mediators (IL-8 and MCP-1) were assessed. Data revealed that ENP (5.56 µg ATO/cm2 and 10.98 µg ZrO2/cm2) only caused mild cytotoxicity at early timepoints (24 h), whereas cells seemed to recover quickly since no significant changes in cytotoxicity were observed at late timepoints (72 h). No meaningful effects of the ENP were observed regarding DNA damage and cytokine levels. PGFP affected cell viability at dose levels as low as ∼9 µg/cm2, which was not seen for PGNP. However, exposure to PGNP (∼4.5 µg/cm2) caused an increase in oxidative DNA damage. These results indicated that PGFP and PGNP exhibit higher toxicity potential than ENP in mass per area unit. However, the presence of a mucociliary apparatus, as it occurs in vivo as a defense mechanism, seems to considerably attenuate the observed toxic effects. Our findings highlight the potential hazard associated with exposure to incidental NP in industrial settings.

Oxidative Stress, Folate Receptor Autoimmunity, and CSF Findings in Severe Infantile Autism.

Background Biomarkers such as oxidative stress, folate receptor alpha (FRα) autoimmunity, and abnormal brain serotonin turnover are common in autism. Methods Oxidative stress biomarkers with pro- and antioxidants were measured in the severe form of infantile autism (n = 38) and controls (n = 24). Children and parents had repeated testing for serum FR autoantibodies, spinal fluid dopamine and serotonin metabolites, pterins, and N5-methyltetrahydrofolate (MTHF). Statistical analysis assessed correlations between variables. Genetic analysis included the SLC6A4 and SLC29A4 genes encoding synaptic serotonin reuptake proteins. Results Compared to controls, the autism group showed a significant increase in oxidative DNA damage in lymphocytes, plasma ceruloplasmin and copper levels with a high copper/zinc ratio, thiol proteins, and superoxide dismutase (SOD) activity. Vitamin C levels were significantly diminished. In most autistic patients, the vitamin A (64%) and D (70%) levels were low. Serum FR autoantibodies fluctuating over 5–7 week periods presented in 68% of all autistic children, 41% of parents vs. 3.3% of control children and their parents. CSF showed lowered serotonin 5-hydroxyindole acetic acid (5HIAA) metabolites in 13 (34%), a low 5HIAA to HVA (dopamine metabolite) ratio in 5 (13%), low 5HIAA and MTHF in 2 (5%), and low MTHF in 8 patients (21%). A known SLC6A4 mutation was identified only in 1 autistic child with low CSF 5HIAA and a novel SLC29A4 mutation was identified in identical twins. Low CSF MTHF levels among only 26% of subjects can be explained by the fluctuating FR antibody titers. Two or more aberrant pro-oxidant and/or antioxidant factors predisposed to low CSF serotonin metabolites. Three autistic children having low CSF 5HIAA and elevated oxidative stress received antioxidative supplements followed by CSF 5HIAA normalisation. Conclusion In autism, we found diverse combinations for FR autoimmunity and/or oxidative stress, both amenable to treatment. Parental and postnatal FR autoantibodies tend to block folate passage to the brain affecting folate-dependent pathways restored by folinic acid treatment, while an abnormal redox status tends to induce reduced serotonin turnover, corrected by antioxidant therapy. Trial Registration. The case-controlled study was approved in 2008 by the IRB at Liège University (Belgian Number: B70720083916). Lay Summary. Children with severe infantile autism frequently have serum folate receptor autoantibodies that block the transport of the essential vitamin folate across the blood-brain barrier to the brain. Parents are often asymptomatic carriers of these serum folate receptor autoantibodies, which in mothers can block folate passage across the placenta to their unborn child. This folate deficiency during the child's intrauterine development may predispose to neural tube defects and autism. Oxidative stress represents a condition with the presence of elevated toxic oxygen derivatives attributed to an imbalance between the formation and protection against these toxic reactive oxygen derivatives. Oxidative stress was found to be present in autistic children where these reactive oxygen derivatives can cause damage to DNA, which changes DNA function and regulation of gene expression. In addition, excessive amounts of these toxic oxygen derivatives are likely to damage the enzyme producing the neuromessenger serotonin in the brain, diminished in about 1/3 of the autistic children. Testing children with autism for oxidative stress and its origin, as well as testing for serum folate receptor autoantibodies, could open new approaches towards more effective treatments.

Two Cultivars of Ocimum basilicum Leaves Extracts Attenuate Streptozotocin-mediated Oxidative Stress in Diabetic Rats.

Leaves of basil plant (Ocimum basilicum) are often used for medicinal purposes because of their bioactive constituents, yet the antioxidant properties of this plant are not fully studied in the field of diabetes. The present study investigated the antioxidant property and anti-diabetic effect of two basil cultivars of Ocimum basilicum, 'Italian Genovese' and 'Thyrsiflora', in a Streptozotocin (STZ) rat model of diabetes . Sixty adult Sprague Dawley rats (n = 10/group) were divided into 6 groups: Three non-diabetic and three diabetic groups that either did not receive any supplementation or were supplemented with the leaves extract of one or the other cultivar. After 13 weeks of feeding, all rats were sacrificed, pancreatic tissues were homogenized and used for evaluating oxidative DNA damage and dichlorofluorescein fluorescence (DCF) assay. Blood was collected for the measurements of glucose and insulin. The STZ caused oxidative stress in the diabetic group as evidenced by an increase in oxidative DNA damage and also caused DCF production in pancreatic tissues as compared to non-diabetic groups, (p<0.05). The STZ treatment resulted in hyperglycemia and low serum insulin level in diabetic rats. Supplementation with extracts of 'Italian Genovese' and 'Thyrsiflora' to the diabetic groups significantly abrogated the STZ-mediated effects (p<0.05). The results indicated that the extracts from the leaves of the two examined basil cultivars act as potent antioxidants and combat the STZ-mediated diabetogenic effect.

Lichen sclerosus: the role of oxidative stress in the pathogenesis of the disease and its possible transformation into carcinoma.

Lichen sclerosus (LS) is an autoimmune chronic inflammatory disease usually involving the anogenital skin of both sexes; more rarely LS exclusively involves extragenital areas. As a chronic inflammatory disease, in most cases, LS evolves and progresses causing scleroatrophy of the skin or scars which may cause stenosis in the affected areas. A few LS patients are at risk of developing squamous cell carcinoma in their lifetime, but appropriate long-term treatment diminishes the possibility of a malignant evolution. Oxidative stress (OS) has been proven to play a role not only in the pathogenesis of LS, but also in the development and progression of the disease. OS, by causing DNA damage and lipid peroxidation, contributes directly to the possible malignant transformation of LS. Moreover, the increase in oxidative DNA damage is associated with mutations in tumor suppressor genes. Considering the role that OS plays in LS, therapeutic use of antioxidants appears to be rational and possible, in association with other treatments. Antioxidants would counteract the oxidative DNA damage, which is the most important factor for the progression of LS and its malignant transformation.

The role of cytochrome P450 2E1 on ethanol-mediated oxidative stress and HIV replication in human monocyte-derived macrophages

BackgroundAlcohol consumption is considered to be a major health problem among people living with HIV/AIDS. Our previous reports have shown that ethanol reduced intracellular concentrations of antiretroviral drugs elvitegravir and darunavir in the HIV-1-infected U1 cell line. Ethanol also increased HIV-1 replication despite the presence of elvitegravir. Our previous finding has also shown that the levels of cytochrome P450 enzyme 2E1 (CYP2E1) and oxidative stress in blood monocytes were induced, while the concentration of alcohol in the plasma was reduced in HIV-1-infected alcohol users compared to uninfected alcohol users. However, the role of CYP2E1 in ethanol-enhanced oxidative stress and HIV-1 replication is still unclear. MethodsThis study examined the chronic effects (14 days) of ethanol on HIV viral load, oxidative DNA damage, expression of CYP2E1, expression of antioxidant enzymes (AOEs), expression of reactive oxygen species (ROS) in human monocyte-derived macrophages (MDM). Further, to evaluate the role of CYP2E1 in mediating ethanol-induced viral replication, CYP2E1 siRNA and CYP2E1 selective inhibitor were used in the HIV-1-infected U1 cell line following ethanol treatment. ResultsChronic ethanol exposure demonstrated an increase in oxidative DNA damage and CYP2E1 expression in both non-infected and HIV-1-infected MDM. Our results showed that ethanol chronic exposure increased HIV-1 replication by ~3-fold in HIV-1-infected MDM. This ethanol-enhanced HIV-1 replication was associated with an increased oxidative DNA damage, an increased expression of CYP2E1, and a decreased expression of antioxidant enzyme PRDX6. In HIV-1-infected U1 cell line, we observed a decreased viral replication (~30%) and a decreased DNA damage (~100%) after repression of CYP2E1 by siRNA, upon ethanol exposure. We also observed a decreased viral replication (~25%) after inhibition of CYP2E1 by using selective CYP2E1 inhibitor. ConclusionsThe data suggest that chronic ethanol exposure increases HIV-1 replication in MDM, at least in part, through CYP2E1-mediated oxidative stress. These results are clinically relevant to potentially find effective treatment strategies for HIV-1-infected alcohol users.

Abstract 2430: Targeting Nrf2 in esophageal adenocarcinoma sensitizes cancer cells to cisplatin treatment

Abstract Background: The incidence rate of the esophageal adenocarcinoma (EAC) has increased rapidly among men since 1976 in the USA. EAC is considered to originate from premalignant Barrett's esophagus (BE) which results from chronic gastroesophageal reflux disease (GERD). It has been reported that oxidative stress is steadily increased in GERD-BE-EAC progression cascade. NFE2-related factor 2 (Nrf2) is a major regulator of cellular anti-oxidant properties that maintains cell viability and cellular homeostasis. Methods and Results: Using Western blot analysis, we detected overexpression of Nrf2 protein in several EAC cell lines, as compared to BE cell lines (CPA, BAR10T) and normal esophageal squamous cell lines. Nrf2 overexpression was also confirmed in primary EAC samples, using immunohistochemistry on a tissue microarray that contained 76 EACs. Knockdown of Nrf2 by siRNA or CRISPR/CAS9 in EAC cells (FLO1 and OE33), that have constitutive high levels of Nrf2, enhanced the sensitivity of cancer cells to cisplatin (CDDP). We confirmed these results by using a Nrf2 specific inhibitor (Brusatol). Further studies demonstrated that dysfunction of Nrf2, either through knockdown of Nrf2 expression or using its specific inhibitor, depleted several Nrf2 target genes such as GR, HO-1, GSTM2, GPX3 and GPX4, which have anti-oxidative properties, leading to a significant increase in cellular ROS levels. The excessive ROS levels resulted in an increase in oxidative DNA damage (measured by 8-oxoguanine) and double strand breaks (measured by p-H2AX) which were further increased by treatment with CDDP with subsequent increase in cancer cell death. Conclusion: These results indicate that constitutive overexpression of Nrf2 in EAC cells protects tumor cells from high level of ROS and favors tumor cell survival and drug resistance. Targeting Nrf2 through its specific inhibitor may have a therapeutic window in EAC. Additional studies are ongoing to determine the molecular mechanisms underlying NRF2 overexpression in EACs. Citation Format: Dunfa Peng, Tianling Hu, Shoumin Zhu, Wael El-Rifai. Targeting Nrf2 in esophageal adenocarcinoma sensitizes cancer cells to cisplatin treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2430.

Mice Lacking the Cytochrome P450 1B1 Gene Are Less Susceptible to Hyperoxic Lung Injury Than Wild Type

Supplemental oxygen is a life-saving intervention administered to individuals suffering from respiratory distress, including adults with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Despite the clinical benefit, supplemental oxygen can create a hyperoxic environment that increases reactive oxygen species, oxidative stress, and lung injury. We have previously shown that cytochrome P450 (CYP)1A enzymes decrease susceptibility to hyperoxia-induced lung injury. In this investigation, we determined the role of CYP1B1 in hyperoxic lung injury in vivo. Eight- to ten-week old C57BL/6 wild type (WT) and Cyp1b1-/- mice were exposed to hyperoxia (>95% O2) for 24-72 h or maintained in room air (21% O2). Lung injury was assessed by histology and lung weight to body weight (LW/BW) ratios. Extent of inflammation was determined by assessing pulmonary neutrophil infiltration and cytokine levels. Lipid peroxidation markers were quantified by gas chromatography mass spectrometry, and oxidative DNA adducts were quantified by 32P-postlabeling as markers of oxidative stress. We found that Cyp1b1-/- mice displayed attenuation of lung weight and pulmonary edema, particularly after 48-72 h of hyperoxia compared with WT controls. Further, Cyp1b1-/- mice displayed decreased levels of pulmonary oxidative DNA adducts and pulmonary isofurans after 24 h of hyperoxia. Cyp1b1-/- mice also showed increased pulmonary CYP1A1 and 1A2 and mRNA expression. In summary, our results support the hypothesis that Cyp1b1-/- mice display decreased hyperoxic lung injury than wild type counterparts and that CYP1B1 may act as a pro-oxidant during hyperoxia exposure, contributing to increases in oxidative DNA damage and accumulation of lipid hydroperoxides.

Elevated oxidative DNA damage in patients with coronary artery disease and its association with oxidative stress biomarkers

Objective: The objective of the present study was to evaluate oxidative DNA damage in peripheral blood leukocytes (PBLs) of patients with coronary artery disease (CAD) and to explore the relationship of oxidised purine and pyrimidine with oxidative stress.Methods: The study participants (n = 100) included 50 patients and unrelated 50 age-, sex- and population-subgroup (Jat Sikhs)-matched healthy controls. Oxidative DNA damage using the modified enzymatic comet in PBLs, and malondialdehyde (MDA) levels, total oxidant status (TOS) and total antioxidant status (TAS) in blood serum samples using spectrophotometric methods was determined.Results: The basal DNA damage of percent tail DNA (T-DNA%) was increased as were tail moment (TM) and olive tail moment (OTM). Oxidative DNA damage in terms of oxidised purines and oxidised pyrimidines was also significantly (p < .001) elevated in patients. Rather the advanced stages of CAD, unstable angina and acute myocardial infarction had significantly more basal and oxidative DNA damage (p < .05) compared to stable angina. MDA levels (p < .01) and TOS (p < .001) were increased significantly in patients with significant (p < .001) decrease in TAS. There was positive correlation of oxidised purines (T-DNA% r = 0.399, p = .004; TM r = 0.623, p = .001; OTM r = 0.456, p= .001) and of total oxidative damage (TM r = 0.515, p = .001; OTM r = 0.463, p = .001) with disease severity, and, with TOS (r = 0.279, p = .050) and negative with TAS (r = −0.341, p = .015). Multiple linear regression analysis revealed TOS and disease severity as independent predictors of oxidative DNA damage.Conclusions: There was significant increase in oxidative DNA damage and oxidative stress in CAD patients compared to levels in healthy controls.

IDH2 deficiency accelerates skin pigmentation in mice via enhancing melanogenesis

Melanogenesis is a complex biosynthetic pathway regulated by multiple agents, which are involved in the production, transport, and release of melanin. Melanin has diverse roles, including determination of visible skin color and photoprotection. Studies indicate that melanin synthesis is tightly linked to the interaction between melanocytes and keratinocytes. α-melanocyte-stimulating hormone (α-MSH) is known as a trigger that enhances melanin biosynthesis in melanocytes through paracrine effects. Accumulated reactive oxygen species (ROS) in skin affects both keratinocytes and melanocytes by causing DNA damage, which eventually leads to the stimulation of α-MSH production. Mitochondria are one of the main sources of ROS in the skin and play a central role in modulating redox-dependent cellular processes such as metabolism and apoptosis. Therefore, mitochondrial dysfunction may serve as a key for the pathogenesis of skin melanogenesis. Mitochondrial NADP+-dependent isocitrate dehydrogenase (IDH2) is a key enzyme that regulates mitochondrial redox balance and reduces oxidative stress-induced cell injury through the generation of NADPH. Downregulation of IDH2 expression resulted in an increase in oxidative DNA damage in mice skin through ROS-dependent ATM-mediated p53 signaling. IDH2 deficiency also promoted pigmentation on the dorsal skin of mice, as evident from the elevated levels of melanin synthesis markers. Furthermore, pretreatment with mitochondria-targeted antioxidant mito-TEMPO alleviated oxidative DNA damage and melanogenesis induced by IDH2 deficiency both in vitro and in vivo. Together, our findings highlight the role of IDH2 in skin melanogenesis in association with mitochondrial ROS and suggest unique therapeutic strategies for the prevention of skin pigmentation.

Genetic and microscopic assessment of the human chemotherapy-exposed placenta reveals possible pathways contributive to fetal growth restriction

IntroductionFetal growth restriction (FGR) carries an increased risk of perinatal mortality and morbidity. A major cause of FGR is placental insufficiency. After in utero chemotherapy-exposure, an increased incidence of FGR has been reported. In a prospective cohort study we aimed to explore which pathways may contribute to chemotherapy-associated FGR. MethodsPlacental biopsies were collected from 25 cancer patients treated with chemotherapy during pregnancy, and from 66 control patients. Differentially expressed pathways between chemotherapy-exposed patients and controls were examined by whole transcriptome shotgun sequencing (WTSS) and Ingenuity Pathway Analysis (IPA). Immunohistochemical studies for 8-OHdG and eNOS (oxidative DNA damage), proliferation (PCNA) and apoptosis (Cleaved Caspase 3) were performed. The expression level of eNOS, PCNA and IGFBP6 was verified by real-time quantitative Reverse Transcription Polymerase Chain Reaction (RT-qPCR). ResultsMost differential expressed genes between chemotherapy-exposed patients and controls were related to growth, developmental processes, and radical scavenging networks. The duration of chemotherapy exposure had an additional impact on the expression of genes related to the superoxide radicals degeneration network. Immunohistochemical analyses showed a significantly increased expression of 8-OHdG (P = 0.003) and a decreased expression of eNOS (P=0.015) in the syncytiotrophoblast of the placenta of cancer patients. A decreased expression of PCNA was detected by immunohistochemistry as RT-qPCR (NS). ConclusionChemotherapy exposure during pregnancy results in an increase of oxidative DNA damage and might impact the placental cellular growth and development, resulting in an increased incidence of FGR in this specific population. Further large prospective cohort studies and longitudinal statistical analyses are needed.

Ascorbic acid protects male rat brain from oral potassium dichromate-inducedoxdative DNA damage and apoptotic changes: the expression patterns of caspase-3, P 53, Bax, and Bcl-2 genes.

Our study designed to study the potential of potassium dichromate (K2Cr2O7) oral exposure to induce damage in male rat brain and to compare the possible protective role of vitamin C (VC) either pre and/or concurrent supply against (K2Cr2O7) induced changes. Thirty male rats were divided into five groups. First control group received distilled water (C), second received 120mg/kg b.wt (VC), third received 25mg/kg b.wt K2Cr2O7 (Cr), fourth group received VC together with K2Cr2O7 by the same former doses (VC + Cr), and the fifth group received the same oral doses of VC 2weeks prior to and along with K2Cr2O7 for 6weeks (VC + Cr pro/co treated). The obtained results revealed that K2Cr2O7 induced a significant decrease in cholinergic activity, glutathione reductase GR activity, reduced glutathione content GSH and ATP levels. Furthermore, K2Cr2O7 induced a significant increase in oxidative DNA damage indicated by 8-hydroxy 2'-deoxyguanosine (8OH2'dG) and formation of apoptotic DNA ladders, significant increase in malondialdehyde (MDA), protein carbonyl, and lactate dehydrogenase enzyme. Increased mRNA expression of pro-apoptotic genes, including caspase-3, p53, and Bax, unlike Bcl-2 expression, was decreased. K2Cr2O7 increased caspase-3 and decreased Bcl-2 immuno-labeling. VC supply noticeably ameliorates K2Cr2O7-induced changes which were more significantly in VC pro and concurrent supplement rather than VC concurrent supply only. Finally, it is concluded that K2Cr2O7 oral administration induced oxidative apoptotic changes in rat brain and confirms the usefulness of VC pre and concurrent supply for the amelioration of K2Cr2O7-induced events more significantly than VC concurrent supply only.