Determination of DNA damage induced by oxidative stress in hyperlipidemic patients

Triglyceride induces DNA damage leading to monocyte death by activating caspase-2 and caspase-8

Monocytes are peripheral leukocytes that function in innate immunity. Excessive triglyceride (TG) accumulation causes monocyte death and thus can compromise innate immunity. However, the mechanisms by which TG mediates monocyte death remain unclear to date. Thus, this study aimed to elucidate the mechanisms by which TG induces monocyte death. Results showed that TG induced monocyte death by activating caspase-3/7 and promoting poly (ADP-ribose) polymerase (PARP) cleavage. In addition, TG induced DNA damage and activated the ataxia telangiectasia mutated (ATM)/checkpoint kinase 2 and ATM-and Rad3-related (ATR)/checkpoint kinase 1 pathways, leading to the cell death. Furthermore, TG-induced DNA damage and monocyte death were mediated by caspase-2 and -8, and caspase-8 acted as an upstream molecule of caspase-2. Taken together, these results suggest that TG-induced monocyte death is mediated via the caspase-8/caspase-2/DNA damage/executioner caspase/PARP pathways. [BMB Reports 2023; 56(3): 166-171].

Triglyceride induces DNA damage leading to monocyte death by activating caspase-2 and caspase-8

Monocytes are peripheral leukocytes that function in innate immunity. Excessive triglyceride (TG) accumulation causes monocyte death and thus can compromise innate immunity. However, the mechanisms by which TG mediates monocyte death remain unclear to date. Thus, this study aimed to elucidate the mechanisms by which TG induces monocyte death. Results showed that TG induced monocyte death by activating caspase-3/7 and promoting poly (ADP-ribose) polymerase (PARP) cleavage. In addition, TG induced DNA damage and activated the ataxia telangiectasia mutated (ATM)/checkpoint kinase 2 and ATM-and Rad3-related (ATR)/checkpoint kinase 1 pathways, leading to the cell death. Furthermore, TG-induced DNA damage and monocyte death were mediated by caspase-2 and -8, and caspase-8 acted as an upstream molecule of caspase-2. Taken together, these results suggest that TG-induced monocyte death is mediated via the caspase-8/caspase-2/DNA damage/executioner caspase/PARP pathways. [BMB Reports 2023; 56(3): 166-171].

DNA damage response signaling: A common link between cancer and cardiovascular diseases

DNA damage response (DDR) signaling ensures genomic and proteomic homeostasis to maintain a healthy genome. Dysregulation either in the form of down- or upregulation in the DDR pathways correlates with various pathophysiological states, including cancer and cardiovascular diseases (CVDs). Impaired DDR is studied as a signature mechanism for cancer; however, it also plays a role in ischemia-reperfusion injury (IRI), inflammation, cardiovascular function, and aging, demonstrating a complex and intriguing relationship between cancer and pathophysiology of CVDs. Accordingly, there are increasing number of reports indicating higher incidences of CVDs in cancer patients. In the present review, we thoroughly discuss (1) different DDR pathways, (2) the functional cross talk among different DDR mechanisms, (3) the role of DDR in cancer, (4) the commonalities and differences of DDR between cancer and CVDs, (5) the role of DDR in pathophysiology of CVDs, (6) interventional strategies for targeting genomic instability in CVDs, and (7) future perspective.

An insight on 7- ketocholesterol mediated inflammation in atherosclerosis and potential therapeutics

7-ketocholesterol, a toxic oxidative product of oxysterol is a causative agent of several diseases and disabilities concomitant to aging including cardiovascular diseases like atherosclerosis. Auto-oxidation of cholesterol esters present in low-density lipoprotein (LDL) deposits lead to the formation of oxidized LDL (Ox-LDL) along with its byproducts, namely 7KCh. It is predominantly found in atherosclerotic plaque and also found to be more atherogenic than cholesterol by being cytotoxic, interfering with cellular homeostasis. This makes it a serious threat by being the foremost cause of morbidity and mortality worldwide and is likely to become more serious during forth coming years. It involves in mediating inflammatory mechanisms characterized by the advancement of fibroatheroma plaques. The atherosclerotic lesion is composed of Ox-LDL along with fibrotic mass consisting of immune cells and molecules. Macrophages being the specialized phagocytic cells, contribute to removal of detrimental contents of the lesion along with accumulated lipids leading to alteration of its biology and functionality due to its plasticity. Here, we have explored the known as well as proposed mechanisms involved with 7KCh associated atherogenesis along with potential therapeutic strategies for targeting 7KCh as a diagnostic and target in medicine.

Efficacy of Polyphenols in the Management of Dyslipidemia: A Focus on Clinical Studies

Polyphenols (PLPs), phytochemicals found in a wide range of plant-based foods, have gained extensive attention in view of their antioxidant, anti-inflammatory, immunomodulatory and several additional beneficial activities. The health-promoting effects noted in animal models of various non-communicable diseases explain the growing interest in these molecules. In particular, in vitro and animal studies reported an attenuation of lipid disorders in response to PLPs. However, despite promising preclinical investigations, the effectiveness of PLPs in human dyslipidemia (DLP) is less clear and necessitates revision of available literature. Therefore, the present review analyzes the role of PLPs in managing clinical DLP, notably by dissecting their potential in ameliorating lipid/lipoprotein metabolism and alleviating hyperlipidemia, both postprandially and in long-term interventions. To this end, PubMed was used for article search. The search terms included polyphenols, lipids, triglycerides, cholesterol, LDL-cholesterol and /or HDL-cholesterol. The critical examination of the trials published to date illustrates certain benefits on blood lipids along with co-morbidities in participant’s health status. However, inconsistent results document significant research gaps, potentially owing to study heterogeneity and lack of rigor in establishing PLP bioavailability during supplementation. This underlines the need for further efforts in order to elucidate and support a potential role of PLPs in fighting DLP.

Therapeutic effects of statins on chromosomal DNA damage of dyslipidemic patients

Statins are a group of cholesterol lowering drugs and frequently used in the therapy of dyslipidemia. Our knowledge of the impact of statin therapy on DNA damage is as yet rudimentary. In this study, we aimed to assess the possible (1) genotoxic, cytostatic, and cytotoxic effects of statins in peripheral blood lymphocytes by using the cytokinesis-block micronucleus cytome (CBMN-cyt) assay, and (2) oxidative DNA damage by measuring plasma 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels in response to statin therapy. Thirty patients with dyslipidemia who had no chronic diseases and did not use any medicines that interfere lipid values and twenty control subjects were included in the study. Statin therapy was initiated at risk-stratified doses. Blood samples were taken before and after treatment with statins and from control subjects, and CBMN-cyt assay parameters and 8-OHdG levels were evaluated. The chromosomal DNA damage (micronuclei and nucleoplasmic bridges [NPBs]), cytostasis (nuclear division index [NDI]), and cytotoxicity (apoptotic and necrotic cell frequencies) were decreased in patients with dyslipidemia after statin treatment. No significant differences were found for 8-OHdG levels between patients with dyslipidemia before or after statin therapy. The total cholesterol and low-density lipoprotein-cholesterol levels showed positive correlations with NPB frequency in patients with dyslipidemia prior to statin treatment. The present study is the first to evaluate CBMN-cyt assay biomarkers and 8-OHdG levels in patients with dyslipidemia before and after treatment with statins. The observed reductions of chromosomal DNA damage and NDI values with statin treatment could represent an important and under-appreciated pleiotropic effect of these agents.

Impact statement

In literature, it is possible to find some in vitro cytokinesis-block micronucleus (CBMN) assay studies about human lymphocytes and statins. But, there are no data on CBMN-cytome (CBMN-cyt) assay parameters related to statin therapy in patients with dyslipidemia. The present study is the first to evaluate CBMN-cyt assay biomarkers and 8-OHdG levels in patients with dyslipidemia before treatment and after treatment with statins (5–10 mg/day rosuvastatin or 10–20 mg/day atorvastatin). In this study we show that statin therapy decreased chromosomal DNA damage (micronuclei and nucleoplasmic bridges) and nuclear division index (NDI) values in patients with dyslipidemia by possible molecular reasons independent of oxidative DNA damage. In addition, the decrease of chromosomal DNA damage and NDI values with statin treatment could be indicated by the association between statin use and reduced risk of cancer.

Effect of short-term hazelnut consumption on DNA damage and oxidized LDL in children and adolescents with primary hyperlipidemia: a randomized controlled trial

Children with primary hyperlipidemia are prone to develop premature atherosclerosis, possibly associated with increased oxidative stress. Nutritional therapy is the primary strategy in the treatment of hyperlipidemia and associated conditions. Dietary interventions with bioactive-rich foods, such as nuts, may contribute to the modulation of both lipid profile and the oxidative/antioxidant status. Our study aimed to assess the impact of a dietary intervention with hazelnuts on selected oxidative stress markers in children and adolescents with primary hyperlipidemia. A single-blind, 8-week, randomized, controlled, three-arm, parallel-group study was performed. Children and adolescents diagnosed with primary hyperlipidemia (n=60) received dietary guidelines and were randomized into three groups: group 1 received hazelnuts with skin (HZN+S), and group 2 hazelnuts without skin (HZN-S), at equivalent doses (15-30 g/day, based on body weight); group 3 (controls) received only dietary recommendations (no nuts). At baseline and after 8 weeks, plasma oxidized low-density lipoprotein (ox-LDL) concentrations, oxidative levels of DNA damage in PBMCs and potential correlation with changes in serum lipids were examined. A reduction of endogenous DNA damage by 18.9%±51.3% (P=.002) and 23.1%±47.9% (P=.007) was observed after HZN+S and HZN-S, respectively. Oxidatively induced DNA strand breaks decreased by 16.0%±38.2% (P=.02) following HZN+S treatment. Ox-LDL levels did not change after HZN+S intervention but positively correlated with total cholesterol and LDL cholesterol. A short-term hazelnut intervention improves cell DNA protection and resistance against oxidative stress but not ox-LDL in hyperlipidemic pediatric patients. The trial was registered at ISRCTN.com, ID no. ISRCTN12261900.

Vigna unguiculata modulates cholesterol induced cardiac markers, genotoxicity and gene expressions profile in an experimental rabbit model

Vigna unguiculata (VU) leaves are edible and used as a leafy vegetable in cuisine from traditional times in India. This study was designed to investigate the cardioprotective effect of VU in cholesterol fed rabbits. The animals were randomly divided into 4 groups of 6 animals each and the experimental period was 3 months. Group I-ND [normal diet 40 g feed], Group II-ND + FVU [flavanoid fraction of Vigna unguiculata (150 mg kg (-1) per body weight)], Group III-ND + CH [cholesterol (400 mg)] and Group IV-ND + CH (400 mg) +FVU (150 mg kg(-1) per body weight). After the experimental period, animals were sacrificed and the various parameters, such as cardiac markers, toxicity parameters, genotoxicity and gene expression, were investigated. Cholesterol feeding causes a significant increase in the levels of cardiac marker enzymes, namely lactate dehydrogenase (LDH) and creatine phospokinase (CPK), atherogenic index, toxicity parameters like serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) were elevated. Antioxidant enzyme levels were decreased, lipid peroxidation products in heart tissue and inflammatory markers, namely cyclooxygenase (COX2) and lipooxygenase (LOX15) in peripheral blood monocytes (PBMCs), were significantly increased. A genotoxicity study using a Comet assay and gene expression by reverse transcriptase-polymerase chain reaction (RT-PCR) of transforming growth factor-b1 (TGF-b1) and heme oxygenase-1 (HO-1) from heart tissue showed an altered expression in the disease group. The supplementation of the flavonoid fraction of Vigna unguiculata leaves (FVU) in the CH + FVU group caused the reversal of the above parameters and cardiotoxicity to near normal when compared with the CH group and FVU. This study revealed the cardioprotective nature of Vigna unguiculata in preventing cardiovascular diseases and this effect is attributed to the presence of antioxidants and the antihyperlipidemic properties of the flavonoid fraction of Vigna unguiculata leaves.

Changes in the level of spontaneous DNA damage in whole blood leukocytes during storage

We evaluated structural damage to DNA (%TDNA) in blood leukocytes from healthy donors of different age at different periods (0-6 days) of blood storage at 4-8°C. It was found that the basal level of DNA damage increased and intracellular antioxidant level decreased during storage. Mean %TDNA was 6.8±3.3% in the fresh blood and 19.2±8.1% after 5-day storage. The experiments with exposure to reactive oxygen species induced by irradiation suggest that depletion of low-molecular-weight endogenous antioxidants occurs as soon as after 5-h storage. Our results suggest that storage time should be taken into account when assessing the basal and induced levels of leukocyte DNA damage by the comet assay.

DNA damage and oxidative status in newly diagnosed, untreated, dipper and non-dipper hypertensive patients

DNA damage occurs more often in hypertensive patients than in non-hypertensive individuals. We sought to investigate lymphocyte DNA damage and total antioxidant status (TAS) levels in patients with dipper hypertension (DH) and non-dipper hypertension (NDH). Thirty-three patients with NDH (NDH group), 31 patients with DH (DH group) and 20 healthy volunteers (control group) were included in the study. Measurements from ambulatory blood pressure monitoring were obtained for all subjects. DNA damage was assessed in peripheral lymphocytes by comet assay, and plasma TAS levels were determined using an automated measurement method. The mean DNA damage value of the NDH group was higher than that of both the DH and control groups (P=0.002 and P<0.001, respectively). The mean DNA damage value of the DH group was higher than that of the control group (P<0.001). The mean TAS level of the NDH group was lower than that of both the DH and control groups (P=0.001 and P<0.001, respectively), and the mean TAS level of the DH group was lower than that of the control group (P<0.001). DNA damage was negatively associated with TAS level (r=-0.692, P<0.001) and positively associated with high sensitive c-reactive protein level (r=0.315, P=0.012). DNA damage increased in the NDH group compared with both the DH group and control group. This condition may be related to increased oxidative stress in the NDH group compared with the DH and control groups.

Combined effects of niacin and chromium treatment on heart of hyperlipidemic rats

The present study was undertaken to investigate the effects of the combination of niacin and chromium(III)-chloride on heart glutathione (GSH), lipid peroxidation (LPO) levels, serum paraoxonase (PON), gamma-glutamyl transferase (GGT) activities and protein carbonyl contents (PCC) of hyperlipidemic rats. In this study, female Swiss albino rats were used. They were divided into four groups. The animals of the first group (group I) were fed with pellet chow. The rats (group II) were fed with a lipogenic diet consisting of 2% cholesterol, 0.5% cholic acid and 20% sunflower oil added to the pellet chow, and given 3% alcoholic water for 60 days. The rats (group III) were fed with the same lipogenic diet and treated by gavage technique with CrCl(3) 6H(2)O to a dose of 250 µg/kg and 100 mg/kg niacin for 45 days, 15 days after experimental animals were done hyperlipidemic. Group IV was fed with pellet chow and treated with 250 µg/kg CrCl(3) 6H(2)O and 100 mg/kg niacin for 45 days. On the 60th day, the heart tissue and blood samples were taken from animals. As a result, heart LPO, serum GGT activity and serum PCC were increased; serum PON activity and heart GSH levels were decreased in hyperlipidemic rats. Treatment with combined niacin and chromium reversed these effects. In conclusion, the combined treatment with niacin and chromium might induce a protective effect on heart tissue.

The 8-oxoguanine glycosylase I (hOGG1) Ser326Cys variant affects the susceptibility to multi-vessel disease in Taiwan coronary artery disease patients

8-hydroxydeoxyguanosine, the key lesion of oxidative DNA damage, contributes to the development of coronary artery disease (CAD). In humans, 8-hydroxydeoxyguanosine is repaired by the enzyme 8-oxoguanine glycosylase I (hOGG1). We investigated the association between the hOGG1 Ser(326)Cys polymorphism and the presence and the severity of CAD in a Taiwan population. Genotypes of the hOGG1 Ser(326)Cys polymorphism were determined from 1397 participants enrolled in this study (378 CAD patients and 1019 controls). CAD severity was indicated both by number of vessels affected (single-vessel disease, SVD vs. multi-vessel disease, MVD), and by individual diffuse score. Real-time polymerase chain reaction was used to determine genotype, using allele-specific TaqMan probes. We found that presence of the hOGG1 Ser(326)Cys polymorphism was associated with a significantly increased risk of CAD and multi-vessel disease when assuming a dominant model of inheritance (OR: 1.52 [95%:1.082~2.133], p=0.015; OR: 2.26 [95%:1.232~4.156], p=0.007). This result was confirmed by multivariate analysis, after adjustment for age, gender, body-mass index, diabetes hypertension, hypercholesterolemia and smoking (OR: 1.78 [95%:1.127~2.806], p<0.005; OR: 2.44 [95%:1.276~4.651], p<0.001). In the present study, hOGG1 Ser(326)Cys polymorphism is a novel genetic marker to be independently associated with the development and severity of CAD in Taiwanese population.

Effect of coronary angiography on oxidative DNA damage observed in circulating lymphocytes

Endogenous oxidative DNA damage is caused by multiple endogenous and exogenous factors. It is not completely known whether coronary angiography has an effect on DNA damage. The aim of this study was to investigate whether coronary angiography causes oxidative DNA damage. Fifty-four patients who underwent elective coronary angiography for diagnostic purpose were enrolled to the study. For each subject, the frequency of oxidative DNA damage was analyzed by using the comet assay, which is a sensitive biomarker of DNA damage, before and after diagnostic procedures. A highly significant increase of DNA damage mean score was observed in all patients after the coronary angiography procedure (p < 0.001). No significant associations were found between the change in oxidative DNA damage and dose of contrast media and radiation exposure time. A significant correlation was observed between the change of DNA damage and age, hyperlipidemia, hypertension, smoking, Gensini score index, and vitamin B(12) (r = 0.496, p< 0.001 ; r = 0.416, p = 0.002; r = 0.284, p = 0.038; r = 0.275, p = 0.044; r = 0.742, p < 0.001; r = -0.347, p = 0.048, respectively). The change of oxidative DNA damage was higher in patients with 3-vessel disease compared with 2-vessel disease, 1-vessel disease, and normal coronary arteries (99.6 +/-8.4, 62.0 +/-2.0, 43.2 +/-8.4, 21.6 +/-11.6 respectively; ANOVA p < 0.001). Multiple linear regression analysis showed that age and Gensini score index were independent predictors of the change of DNA damage (beta = 0.425, p = 0.003, beta = 0.684, p = 0.001 respectively). Our findings demonstrate that increased oxidative DNA damage in undergoing coronary angiography might be dependent on the severity of coronary artery disease and age, rather than on contrast media and radiation exposure time.

Polymorphism of p53 gene codon 72 in Kuwaiti with coronary artery disease and diabetes

BACKGROUND AND AIM

Polymorphism in the p53 gene at codon 72 has been linked to the development of certain diseases including cancer. A possible association between such polymorphism and the development of coronary artery disease (CAD) and diabetes is being investigated, but no conclusive evidence has been reached yet. Our study is the first pilot study to be conducted on Kuwaitis suffering from CAD and diabetes, aiming at investigating the possible existence of the above association.

MATERIALS AND METHODS

We analyzed the genotype distribution and allele frequency of p53 gene at codon 72 in 158 CAD samples and 110 controls, and in 142 diabetic and 130 controls.

RESULTS

Analysis of CAD patients revealed an alarming significant association between the disease and the existence of diabetes (P=0.0007). Also, the CAD patients had significantly higher level of triglyceride (P<0.0001) and cholesterol (P<0.0001) as compared to control. As for the polymorphism in p53 gene codon 72, we could not detect any association with the genotype Pro/Pro, Pro/Arg or Arg/Arg distribution (P=0.28) or allele (Pro or Arg) frequency (P=0.25) in the CAD patients. Similarly, no association was found with the genotype Pro/Pro, Pro/Arg or Arg/Arg distribution (P=0.44) or allele (Pro or Arg) frequency (P=0.26) in the diabetic patients.

CONCLUSION

CAD seems to be strongly linked to diabetes in Kuwait. Polymorphism in the p53 gene at codon 72 revealed no significant association with the development of CAD or diabetes in Kuwait, which confirms other similar results obtained in the US and Asia.

Neuropeptides induced a pronounced and statin-sensitive dysregulation of mevalonate cycle in human monocytes of patients with hypercholesterolemia

Angiotensin II (Ang II) and leptin generate statin-inhibitable superoxide anion production that accounts for only part of the entire superoxide anion production. In our recent studies, we aimed at elucidating whether Ang II and leptin, affecting the intensity of the mevalonate cycle, are able to increase endogenous cholesterol synthesis. Furthermore, we compared the superoxide anion and cholesterol production capability of monocytes of healthy control volunteers and monocytes obtained from patients with hypercholesterolemia (HC). We also studied the differences of the produced statin-inhibitable superoxide anion and cholesterol synthesis in control and HC-monocytes, depending on the applied stimulating ligands. In control and HC-monocytes--stimulated by Ang II, leptin, fenyl-Me-Leu-Phe (FMLP), phorbol-12-myristate-13-acetate (PMA) and A23187--we determined the proportion of mevalonate cycle-dependent and -independent superoxide and cholesterol production, using lovastatin (Lov), and 25-hydroxycholesterol (25-HC). According to our results; (1) superoxide anion generation in HC-monocytes was elevated after Ang II, leptin and FMLP-stimulation, whereas PMA and A23187-stimulation had lower stimulating effect in HC than in control cells. (2) Cholesterol synthesis was increased only after stimulation with Ang II and leptin. (3) The Ang II and leptin-induced total superoxide anion generation and cholesterol synthesis were more elevated in HC than in control monocytes. (4) In contrast, the increase in Lov and 25-HC sensitive cholesterol synthesis were higher in resting, but lower in stimulated HC monocytes than in control cells. Summarizing our results, we concluded that Ang II and leptin are involved in enhancement of endogenous cholesterol synthesis through a statin-sensitive pathway.

DNA damage in metabolic syndrome and its association with antioxidative and oxidative measurements

The purpose of this study was to assess DNA damage levels in subjects with metabolic syndrome (MetS). Sixty-five subjects with MetS and 65 controls were enrolled in this study. Levels of DNA damage, total antioxidant capacity (TAC), total peroxide and oxidative stress index (OSI) were measured. We found that DNA damage levels were significantly increased [155.5 (60-264) vs. 93.2 (0-208) arbitrary units; p < 0.001] and TAC levels were significantly decreased in MetS than in control (1.34 +/- 0.27 vs. 55 +/- 0.33 mmol Trolox equivalent/l; p < 0.001). A significant falling trend in TAC levels and a significant rising trend in DNA damage values with the increase in the number of metabolic disturbances (anova p < 0.001 for both) were observed. Total peroxide (30.9 +/- 4.9 vs. 21.3 +/- 2.5 micromol H2O2/l; p < 0.001) and OSI levels [2.4 (1.3-3.8) vs. 1.4 (0.7-2.3) arbitrary units; p < 0.001] were significantly higher in the subjects with MetS than in controls. We found significant negative correlation between DNA damage and TAC levels in MetS (r = -0.656, p < 0.001) and in control (r = -0.546, p < 0.001). In multiple linear regression analysis, age, body mass index, presence of MetS and number of the components of MetS were independent predictors of log-transformed DNA damage (p < 0.05, for all). DNA damage is increased in patients with MetS. The increase in DNA damage might be occur because of the increase in the imbalance between the production of oxidants and antioxidant defences in subjects with MetS.

Oxidative DNA damage and activation of c-Jun N-terminal kinase pathway in fibroblasts from patients with hereditary spastic paraplegia

1. Hereditary spastic paraplegia (HSP) is a genetically heterogeneous group of neurodegenerative disorders affecting 1 in 10,000 individuals. The present study was aimed to elucidate the role played by reactive oxygen species (ROS) in the pathogenesis of this disease. 2. To address this question we used 7-11 passaged fibroblasts from HSP patients to measure the extent of DNA damage induced by H2O2 treatment and to evaluate the JNK phosphorylation level after hydrogen peroxide and serum stimuli. 3. The present study demonstrates that HSP cells compared to controls are more sensitive to DNA damages induced by H2O2 treatment, and that JNK phosphorylation levels are increased in HSP fibroblasts compared to controls after hydrogen peroxide and serum stimuli. These results suggest a ROS-mediated pathogenetic mechanism for this disease.

Increased plasma malondialdehyde and protein carbonyl levels and lymphocyte DNA damage in patients with angiographically defined coronary artery disease

We investigated the oxidative modifications of lipids, proteins and DNA, three potential molecular targets of oxidative stress, in 30 patients with angiographically defined coronary artery disease (CAD) and 30 healthy control subjects. In addition, we examined relationships between these oxidative modifications and the severity of vascular lesions in patients with CAD. Malondialdehyde (MDA) and protein carbonyl (PC) levels, as well as ferric reducing antioxidant power (FRAP), were measured in the plasma. DNA damage was evaluated as single strand breaks (SSBs), formamidopyrimidine glycosylase (Fpg) and endonuclease III (E-III)-sensitive sites by the comet assay in DNA isolated from lymphocytes. MDA and PC levels increased, but FRAP values decreased, in patients as compared to controls. However, these values did not vary with the number of affected coronary vessels and were not correlated with Duke score, a parameter of the severity of vascular lesions in patients with CAD. We also found that lymphocyte DNA damage (SSBs, Fpg and E-III sites) were increased in patients. Although there were no significant differences in SSBs values in patients grouped according to affected vessel number, Fpg and E-III sites increased. We also detected significant correlations between Duke scores and SSBs and Fpg sites. Serum cholesterol, triglyceride and LDL-cholesterol levels were found to increase, but HDL-cholesterol levels decreased in CAD patients, but these lipids were not correlated with Duke scores. The results of this study reinforce the presence of increased combined oxidative modifications in lipid, protein and DNA in patients with CAD. However, lymphocyte DNA damage seems to be a more reliable assay than MDA and PC determinations to detect the severity of vascular lesions in patients.

Interaction of hyperbaric oxygen, nitric oxide, and heme oxygenase on DNA strand breaks in vivo

Hyperbaric oxygen (HBO), e.g. pure oxygen breathing at supra-atmospheric pressures, represents a well-suited model for investigating oxidative stress-induced DNA damage as well as protective mechanisms. While the induction of heme oxygenase-1 (HO-1) seems to be crucial for this protection against this DNA damage, the role of nitric oxide (NO) remains unclear. HO-1 expression is a major regulator of the inducible NO synthase (iNOS), and therefore we investigated the effect of the interaction between HBO, NO, and HO-1 on DNA damage. Prior to exposure to HBO (3 h at 3 bar ambient pressure) rats randomly received vehicle (HBO alone, 1 mL 0.9% saline, n=8), the NO donor molsidomine (SIN-10, 40 mg/kg, n=8) or the HO-1 blocker tin-mesopophyrin (Sn-MP, 50 micromol/kg, n=8). Additional groups received SIN-10 without exposure to HBO, i.e. breathing air under normobaric conditions for 3h (SIN-10 alone, 40 mg/kg, n=6), vehicle without HBO (negative controls, n=6), and ethylmethanesulfonate without HBO (EMS, 200 mg/kg) (positive controls n=4). Immediately after the 3 h HBO or air breathing period blood was analysed for DNA strand breaks (tail moment in the alkaline comet assay) and nitrite+nitrate (chemoluminescence). Whereas the tail moment was ten-fold higher after EMS than in the negative controls, there was no effect of HBO nor SIN-10 alone. Together with HBO, pretreatment with SIN-10 doubled the tail moment, and Sn-MP increased it by 50%. In contrast to Sn-MP or HBO alone, SIN-10 resulted in a five-fold increase of nitrite+nitrate concentrations. We conclude that both HO-1 blockade and excess NO release promote DNA damage during HBO exposure in vivo. The effect of HO-1 inhibition is probably independent of the regulatory function of HO-1 for iNOS.

Searching for the role and the most suitable biomarkers of oxidative stress in Alzheimer's disease and in other neurodegenerative diseases

The contribution of oxidative stress to neurodegeneration is not peculiar of a specific neurodegenerative disease, oxidative stress has been found implicated in a number of neurodegenerative disorders among which Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS). Even increasing are studies dealing with the search for peripheral biomarkers of oxidative stress in biological fluids or even in peripheral tissues themselves such as fibroblasts or blood cells. The application of the modified version of the comet assay for the detection of oxidised purines and pyrimidines in peripheral blood leukocytes results particularly useful if the study requires repeated blood drawn from the same individual, for instance if a clinical trial is performed with a preventive therapy. Likely damage occurs to every category of biological macromolecules and we consider, in the context of neurodegenerative diseases, particularly critical the proteic level. The identification of subjects at risk to develop AD or with pre-pathogenic conditions, the possibility to use "a battery of assays" for the detection of oxidative damage at peripheral level, together with recent advances in brain imaging, will allow to better address studies aimed not only to therapeutic purposes but also mainly to primary prevention.

Relationship between DNA damage, total antioxidant capacity and coronary artery disease

OBJECTIVE

It has been known that there was a relation between the levels of DNA damage and the severity of the coronary artery disease (CAD). However, little is known about association of DNA damage with total antioxidant capacity (TAC) and CAD. The aim of this study is to evaluate the relationship between DNA damage, TAC and CAD.

METHODS

We used the comet assay to measure DNA damage from 53 patients with angiographically documented CAD and 42 patients with angiographically documented normal coronary vessel. The extent and severity of CAD was calculated to Gensini score index. TAC of plasma was determined using a novel automated measurement method.

RESULTS

Mean values of DNA damage were significantly higher in CAD patients than in the control group (p<0.001). There was a positive correlation between Gensini score index and DNA damage (r=0.590, p<0.001). Additionally, significantly positive correlations between score of DNA damage, and diabetes, smoking, obesity and hyperlipidemia were found (p<0.05). There was also a negative correlation between TAC and DNA damage (r=-0.711, p<0.001). The DNA damage was significantly higher in diabetic, smoker, hyperlipidemic and obese individuals than those without these conditions (p=0.001, p=0.006, p=0.001, p=0.004, respectively).

CONCLUSIONS

These data indicate that the level of DNA damage is increased and TAC level is decreased in CAD. DNA damage is correlated with the severity of the CAD, and levels of TAC.

Atorvastatin effect on high-density lipoprotein-associated paraoxonase activity and oxidative DNA damage

OBJECTIVE

High-density lipoprotein (HDL)-associated antioxidant paraoxonase (PON) may reduce low-density lipoprotein (LDL) oxidation and prevent atherosclerosis. The aim of this present study was to investigate the effect of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor atorvastatin on hydrogen-peroxide-induced DNA damage by comet assay and the correlation between oxidative DNA damage and antioxidant PON activity.

METHODS

Thirteen type-II/a hyperlipidemic patients were enrolled in the study. We examined the effect of 10 mg/day atorvastatin treatment on lipid levels and the degree of DNA damage in lymphocytes separated from hyperlipidemic patients, nitric oxide (NO), thiobarbituric acid-reactive substances (TBARS), PON levels and activity.

RESULTS

After 6 months, atorvastatin treatment significantly decreased serum cholesterol and LDL-cholesterol levels. The triglyceride level did not change, and there was no significant change in the HDL cholesterol level. The visual score characteristic to the degree of DNA damage in comet assay was significantly decreased, as well as the TBARS level, while the level of NO was non-significantly increased. PON activity and the PON/HDL ratio were significantly increased after atorvastatin treatment. There was a negative correlation between DNA damage and PON activity, as well as between DNA damage and the PON/HDL ratio before and after atorvastatin treatment.

CONCLUSION

These findings show that atorvastatin treatment favorably affected the lipid profile, increasing the activity of HDL-associated PON and decreasing the cytotoxic effect of oxidative stress.

Erythrocyte Antioxidant Enzyme Activities and Lipid Peroxidation in Patients with Types IIb and IV Hyperlipoproteinemias

We measured lipid peroxidation and antioxidant enzymes in erythrocytes of types IIb and IV hyperlipoproteinemic (HLP) human subjects in comparison with age-matched controls. Thiobarbituric acid-reactive substances (TBARS), a measure of lipid peroxidation, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), glutathione reductase (GR), and catalase (CAT) were determined in erythrocytes. We also measured lipid parameters including triglycerides (TG), total cholesterol (TC), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), apolipoprotein AI, and apolipoprotein B, and antioxidant related substances such as serum albumin, free iron, ferritin, ceruloplasmin. Thirty-two subjects (females 15, males 17) with type IIb (the mean age 45.6+/-8 [S.E.]), 34 with type IV (females 16, males 18) (the mean age 47+/-10 [S.E.]), and 36 normolipidemic voluntary subjects (females 18, males 18) (the mean age 46+/-8 [S.E.]) were included in the study. Erythrocytes were prepared by classical washing method (0.9% NaCl) from venous blood samples. The mean TBARS levels in plasma and erythrocyte suspensions were found to be significantly higher in both types IIb and IV hyperlipoproteinemics. Erythrocyte SOD and GSH-Px activities were decreased but erythrocyte GR activity did not change in both types IIb and IV hyperlipoproteinemics. Erythrocyte CAT activity was decreased in type IIb, but it was increased in type IV hyperlipoproteinemics. Erythrocyte SOD activity was negatively correlated with plasma TG level, whereas plasma free iron was positively correlated with plasma TBARS level in type IV hyperlipoproteinemics. These results suggest the presence of oxidative injury in patients with type IIb or IV hyperlipoproteinemia, and that the responses of erythrocyte antioxidant enzymes to oxidant stress are different in these conditions.

Impairment of the cytotoxic and oxidative activities of 7 beta-hydroxycholesterol and 7-ketocholesterol by esterification with oleate

Atherosclerosis involves inflammatory processes, as well as cytotoxic and oxidative reactions. In atherosclerotic plaques, these phenomena are revealed by the presence of dead cells, oxidized lipids, and oxidative DNA damage, but the molecules triggering these events are still unknown. As 7 beta-hydroxycholesterol and 7-ketocholesterol, which are present at elevated concentrations in atherosclerotic lesions, are strongly cytotoxic and pro-oxidative, their effects were determined on cell death, superoxide anion and nitric oxide production, lipid peroxidation, and oxidative DNA damage. 7-Ketocholesterol- and 7 beta-hydroxycholesterol-induced cell death leads to a loss of mitochondrial potential, to increased permeability to propidium iodide, and to morphological nuclear changes (swelling, fragmentation, and/or condensation of nuclei). These effects are preceded by the formation of cytoplasmic monodansylcadaverine-positive structures and are associated with a rapid enhancement of cells overproducing superoxide anions, a decrease in cells producing nitric oxide, lipid peroxidation (formation of malondialdehyde and 4-hydroxynonenal adducts, low ratio of [unsaturated fatty acids]/[saturated fatty acids]) as well as oxidative DNA damage (8-oxoguanine formation). Noteworthy, none of the cytotoxic features previously observed with 7 beta-hydroxycholesterol and 7-ketocholesterol were noted with cholesterol, 7 beta-hydroxycholesteryl-3-oleate and 7-ketocholesteryl-3-oleate, with the exception of a slight increase in superoxide anion production with 7 beta-hydroxycholesteryl-3-oleate. This finding supports the theory that 7 beta-hydroxycholesterol and 7-ketocholesterol could induce cytotoxic and oxidative processes observed in atherosclerotic lesions and that esterification of these compounds may contribute to reducing atherosclerosis progression.

Coronary atherosclerosis and somatic mutations: an overview of the contributive factors for oxidative DNA damage

Coronary artery disease (CAD) is a multifactorial process that appears to be caused by the interaction of environmental risk factors with multiple predisposing genes. Genetic research on CAD has traditionally focused on investigation aimed at identifying disease-susceptibility genes. Recent evidence suggests that somatically acquired DNA mutations may also contribute significantly to the pathogenesis of the disease, underlining the similarity between atherosclerotic and carcinogenic processes. The generation of oxidative stress has been emphasized as an important cause of DNA damage in atherosclerosis. This review highlights some of the major atherogenic risk factors as likely mediators in the oxidative modification of DNA. It also examines the hypothesis that an increase in oxidative stress may derive from "oxidatively" damaged mitochondria. Accordingly, further research in this field should be given high priority, since increased somatic DNA damage could be an important pathogenic factor and an additional prognostic predictor, as well as a potential target for therapeutic strategies in coronary artery disease.

Analysis of oxidative processes and of myelin figures formation before and after the loss of mitochondrial transmembrane potential during 7beta-hydroxycholesterol and 7-ketocholesterol-induced apoptosis: comparison with various pro-apoptotic chemicals

Among oxysterols oxidized at C7 (7alpha-, 7beta-hydroxycholesterol, and 7-ketocholesterol) 7beta-hydroxycholesterol and 7-ketocholesterol are potent inducers of cell death and probably play central roles in atherosclerosis. As suggested by our previous investigations, 7-ketocholesterol might be a causative agent of vascular damage by inducing apoptosis and enhancing superoxide anion (O2*-) production. To determine the precise relationships between cytotoxicity and oxidative stress, the ability of oxysterols oxidized at C7 to induce apoptosis, to stimulate O2*- production and to promote lipid peroxidation was compared with different pro-apoptotic chemicals: antitumoral drugs (VB, Ara-C, CHX, and VP-16) and STS. All compounds, except 7alpha-hydroxycholesterol, induced apoptosis characterized by the occurrence of cells with fragmented and/or condensed nuclei, loss of mitochondrial potential, caspase-3 activation, PARP degradation, and internucleosomal DNA fragmentation. The highest proportion of apoptotic cells was found with antitumoral drugs and STS, whereas the highest overproduction of O2*- detected before and after the loss of mitochondrial potential was obtained with 7beta-hydroxycholesterol and 7-ketocholesterol. Overproduction of O2*- was always correlated with enhanced lipid peroxidation. Vit E was only capable to significantly counteract apoptosis and oxidative stress induced by 7beta-hydroxycholesterol, 7-ketocholesterol, VB and STS. By electron and fluorescence microscopy, myelin figures evocating autophagic vacuoles were barely observed under treatment with 7beta-hydroxycholesterol and 7-ketocholesterol, and their formation occurring before the loss of mitochondrial potential was reduced by Vit E. In the presence of 7alpha-hydroxycholesterol, no enhancement of O2*- production, no lipid peroxidation, and no formation of myelin figures were observed. Collectively, our data demonstrate, that there can be a more or less important stimulation of oxidative stress during apoptosis. They also suggest that enhancement of O2*- production associated with lipid peroxidation during 7beta-hydroxycholesterol and 7-ketocholesterol-induced apoptosis could contribute to in vivo vascular injury, and that myelin figures could constitute suitable markers of oxysterol-induced cell death.

Elevated levels of oxidative DNA damage in patients with coronary artery disease

BACKGROUND

Somatic DNA damage has been suggested to contribute to the pathogenesis of atherosclerosis. However, little is known about the role of oxidative DNA damage in patients with coronary artery disease (CAD).

METHODS

In this study, we used the comet assay to measure oxidative DNA damage (DNA strand breaks and enzyme-sensitive sites) in peripheral blood lymphocytes from 13 patients with angiographically documented CAD and 11 age- and sex-matched control participants.

RESULTS

Mean values of DNA strand breaks, oxidized pyrimidines and altered purines were significantly higher in CAD patients than in the control group (11.9 +/- 1.4, 18.0 +/- 2.7 and 18.1 +/- 3.1 compared with 3.3 +/- 0.2, 2.7 +/- 0.5 and 4.5 +/- 1.1; P < 0.0001, P < 0.0001 and P = 0.0009, respectively). Moreover, oxidized purines (for example, 8-oxo-guanine) increased with the number of affected vessels and positively correlated with the extent of CAD measured by means of the number of the coronary lesions (P = 0.76, P = 0.003) and the Duke scoring system (P = 0.66, P = 0.01). Diabetic patients showed higher levels of oxidized pyrimidines (31.3 +/- 5.5 compared with 14.1 +/- 2.7; P = 0.013), while patients with dyslipidemia had elevated altered purines compared with normal patients (20.4 +/- 2.6 compared with 4.9 +/- 3.1; P = 0.03).

CONCLUSIONS

These data indicate an overall elevation of oxidative DNA damage in CAD patients correlated with the severity of the disease and some atherogenic risk factors, suggesting a possible role of oxidative genetic damage in the pathogenesis of atherosclerosis.

P53 codon 72 polymorphism in coronary artery disease: no evidence for association with increased risk or micronucleus frequency

A common polymorphism at codon 72 (Arg72Pro) of the p53 gene, a gene which codes for a tumor-suppressor protein with both antiproliferative and pro-apoptotic actions, has recently been reported to be a risk factor for coronary luminal narrowing after angioplasty. However, the association of the polymorphism with coronary artery disease (CAD) risk has not been studied. We evaluated the distribution of the Arg72Pro genotype in 250 patients, 180 with angiographically documented CAD and 70 with normal coronary angiography, by using polymerase chain reaction amplification of patient DNA followed by restriction enzyme digestion. We also examined the association between the Arg72Pro genotype and chromosome damage in 82 male patients (60 CAD and 22 no-CAD) by the micronucleus (MN) test in human lymphocytes, a sensitive assay for chromosome breakage and aneuploidy. The frequencies of Pro/Pro, Pro/Arg, and Arg/Arg genotypes in CAD patients were not significantly different from those who were CAD-free (chi(2) = 0.20, P = 0.90) and not significantly associated with the extent and severity of CAD. A significant increase in MN frequency was observed in relation to smoking status (8.4 +/- 0.6, 11.9 +/- 1 and 12.0 +/- 1.6, for non smokers, ex-smokers and smokers, respectively; P = 0.02). Moreover, diabetic patients showed higher levels of MN than normal patients (13.5 +/- 1.4 vs. 9.6 +/- 0.5, P = 0.0025). Also, MN frequency was significantly higher in CAD patients than in no-CAD patients (11.2 +/- 0.7 vs. 8.0 +/- 0.9, P = 0.02) and increased with the number of affected vessels (9.3 +/- 0.1, 12.2 +/- 1.5 and 12.5 +/- 1.3 for one-, two-, and three-vessel disease, respectively; P = 0.02). However, there were no associations between MN frequency and the Arg72Pro polymorphism. Although there appears to be an association between CAD and MN frequency, our results indicate that the Arg72Pro polymorphism does not have a significant impact on CAD or MN frequencies.