Differential time responses in inflammatory and oxidative stress markers after a marathon: An observational study.

Acute and adaptive changes in systemic markers of oxidatively generated nucleic acid modifications (i.e., 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo)) as well as inflammatory cytokines (i.e., C-reactive protein, interleukin-6, interleukin-10, and tumour necrosis factor alpha), a liver hormone (i.e., fibroblast growth factor 21 (FGF21)), and bone metabolism markers (sclerostin, osteocalcin, C-terminal telopeptide, and N-terminal propeptide of type 1 procollagen) were investigated following a marathon in 20 study participants. Immediate changes were observed in inflammatory cytokines, FGF21, and bone metabolism markers following the marathon. In contrast, no immediate changes in urinary excretion of 8-oxodG and 8-oxoGuo were evident. Four days after the marathon, decreased urinary excretion of 8-oxodG (-2.9 (95% CI -4.8;-1.1) nmol/24 h, P < 0.01) and 8-oxoGuo (-5.8 (95% CI -10.3;-1.3) nmol/24 h, P = 0.02) was observed. The excretion rate of 8-oxodG remained decreased 7 days after the marathon compared to baseline (-2.3 (95%CI -4.3;-0.4) nmol/24 h, P = 0.02), whereas the excretion rate of 8-oxoGuo was normalized. In conclusion marathon participation immediately induced a considerable inflammatory response, but did not increase excretion rates of oxidatively generated nucleic acid modifications. In fact, a delayed decrease in oxidatively generated nucleic acid modifications was observed suggesting adaptive antioxidative effects following exercise. ABBREVIATIONS: 8-oxodG: 8-oxo-7,8-dihydro-2'-deoxyguanosine; 8-oxoGuo: 8-oxo-7,8-dihydroguanosine; CI: confidence interval; CTX: C-terminal telopeptide of type 1 collagen; DXA: dual-energy X-ray absorptiometry; ELISA: enzyme-linked immunosorbent assay; FGF21: Fibroblast growth factor 21; h: hour; hsCRP: high sensitivity C-reactive protein; IL: interleukin; IQR: interquartile range; MS: mass spectrometry: P1NP: N-terminal propeptide of type 1 procollagen; TNFα: tumour necrosis factor alpha; UPLC: ultra-performance liquid chromatography.

Clarithromycin, trimethoprim, and penicillin and oxidative nucleic acid modifications in humans: randomised, controlled trials.

AIMS: In vitro studies have demonstrated that formation of reactive oxygen species (ROS) contributes to the effect of bactericidal antibiotics. The formation of ROS is not restricted to bacteria, but also occurs in mammalian cells. Oxidative stress is linked to several diseases. This study investigates whether antibiotic drugs induce oxidative stress in healthy humans as a possible mechanism for adverse reactions to the antibiotic drugs. METHODS: This study contains information from two randomised, controlled trials. Participants underwent 1 week treatment with clarithromycin, trimethoprim, phenoxymethylpenicillin (penicillin V), or placebo. Oxidative modifications were measured as 24-h urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), and plasma levels of malondialdehyde before and after treatment as a measurement of DNA oxidation, RNA oxidation, and lipid peroxidation, respectively. RESULTS: Clarithromycin significantly increased urinary excretion of 8-oxodG by 22.0% (95% confidence interval (CI): 3.6-40.4%) and 8-oxoGuo by 14.9% (95% CI: 3.7-26.1%). Further, we demonstrated that trimethoprim significantly lowered urinary excretion of 8-oxodG by 21.7% (95% CI: 5.8-37.6%), but did not influence urinary excretion of 8-oxoGuo. Penicillin V did not influence urinary excretion of 8-oxodG or 8-oxoGuo. None of the antibiotic drugs influenced plasma levels of malondialdehyde. CONCLUSION: Clarithromycin significantly increases oxidative nucleic acid modifications. Increased oxidative modifications might explain some of clarithromycin's known adverse reactions. Trimethoprim significantly lowers DNA oxidation but not RNA oxidation. Penicillin V had no effect on oxidative nucleic acid modifications.

The effect of smoking on the urinary excretion of 8-oxodG and 8-oxoGuo in patients with type 2 diabetes.

Over the past decades, attention has been paid to understanding the impact of oxidative stress and related modifications of DNA and RNA on various human health risks. A recent meta-analysis comprising 1915 smokers and 3462 non-smokers found a significantly higher level of DNA oxidation measured as urinary 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) excretion in smokers compared with non-smokers in a healthy population. We aimed to investigate if an increased urinary excretion of 8-oxodG in smokers versus never smokers and former smokers could be verified in a population with type 2 diabetes. Additionally, we measured RNA oxidation levels through urinary excretion of 8-oxo-7, 8-dihydroguanosine (8-oxoGuo). Our study included urinary samples from 2721 type 2 diabetic patients, analyzed using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Logistic regression was used to examine the relationship between daily smokers (n = 462) versus former (n = 1341) and never smokers (n = 918) regarding the RNA and DNA oxidation, respectively. We did not find any significant effect of smoking on urinary excretion of 8-oxodG or 8-oxoGuo in our study. Due to a sparse study area, it is still too early to draw any conclusions on smoking and RNA-oxidation. Regarding DNA oxidation, our study suggests that the effect of smoking seen in healthy populations might be attenuated in patients with type 2 diabetes.

Markers of oxidative stress in obese men with and without hypertension.

OBJECTIVES: The aim of our study was to investigate if the 24-hour excretion of the urinary markers for oxidative stress to DNA and RNA, measured as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydro-guanosine (8-oxoGuo), respectively, were increased in obese individuals with or without hypertension compared to lean controls. METHODS: A total of 63 obese hypertensive men (obeseHT), 40 obese normotensive men (obeseNT) and 27 lean normotensive men (leanNT) were included in the study. Body mass index (BMI) was between 20.0 and 24.9 kg/m2 in leanNT participants and ≥30 kg/m2 in obese participants. Hypertension was defined as a mean 24-hour systolic ambulatory blood pressure (AMBP) ≥ 130 mmHg or a mean 24-hour diastolic AMBP ≥80 mmHg and normotension as mean 24-hour AMBP <130/80 mmHg. Twenty-four hour urinary 8-oxoGuo and 8-oxodG excretion (nmol/24 h) were measured by a validated liquid chromatography-tandem mass spectrometry method (UPLC-MS/MS). RESULTS: Urinary 8-oxoGuo excretion was (median and [interquartile range]) 30.8 [27.8-32.2] nmol/24 h in leanNT, 36.8 [31.3-40.2] nmol/24 h in obeseNT and 40.6 [31.7-48.5] nmol/24 h in obeseHT. The difference was statistically significant (p = .002) and post hoc tests showed a significant difference between leanNT and obeseHT (p = .001) as well as obeseNT (p = .002), whereas the two obese groups did not differ (p = .6). No statistically significant differences in 8-oxodG concentrations were observed between the three groups (p = .3). CONCLUSION: The measurement of urinary excretion of 8-oxoGuo suggests that obesity in men, but not hypertension, is associated with increased oxidative damage to RNA.

Reduction of oxidative stress on DNA and RNA in obese patients after Roux-en-Y gastric bypass surgery-An observational cohort study of changes in urinary markers.

Increased oxidative stress in obesity and diabetes is associated with morbidity and mortality risks. Levels of oxidative damage to DNA and RNA can be estimated through measurement of 8-oxo-7,8-dihydro-2´-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) in urine. Both markers have been associated with type 2 diabetes, where especially 8-oxoGuo is prognostic for mortality risk. We hypothesized that Roux-en-Y gastric bypass (RYGB) surgery that has considerable effects on bodyweight, hyperglycemia and mortality, might be working through mechanisms that reduce oxidative stress, thereby reducing levels of the urinary markers. We used liquid chromatography coupled with tandem mass spectrometry to analyze the content of 8-oxodG and 8-oxoGuo in urinary samples from 356 obese patients treated with the RYGB-procedure. Mean age (SD) was 44.2 (9.6) years, BMI was 42.1 (5.6) kg/m2. Ninety-six (27%) of the patients had type 2 diabetes. Excretion levels of each marker before and after surgery were compared as estimates of the total 24-hour excretion, using a model based on glomerular filtration rate (calculated from cystatin C, age, height and weight), plasma- and urinary creatinine. The excretion of 8-oxodG increased in the first months after RYGB. For 8-oxoGuo, a gradual decrease was seen. Two years after RYGB and a mean weight loss of 35 kg, decreased hyperglycemia and insulin resistance, excretion levels of both markers were reduced by approximately 12% (P < 0.001). For both markers, mean excretion levels were about 30% lower in the female subgroup (P < 0.0001). Also, in this subgroup, excretion of 8-oxodG was significantly lower in patients with than without diabetes. We conclude, that oxidative damage to nucleic acids, reflected in the excretion of 8-oxodG and 8-oxoGuo, had decreased significantly two years after RYGB-indicating that reduced oxidative stress could be contributing to the many long-term benefits of RYGB-surgery in obesity and type 2 diabetes.

The effect of structured personal care on RNA oxidation: A 19-year follow-up of the randomized trial Diabetes Care in General Practice (DCGP).

AIMS: The urinary marker of RNA oxidation, 8­oxo­7,8­dihydroguanosine (8-oxoGuo), but not the corresponding marker of DNA oxidation, 8­oxo­7,8­dihydro­2'­deoxyguanosine (8-oxodG), is a prognostic biomarker in patients with type 2 diabetes (T2D). The aim of the present study was to investigate the effect of structured personal care (individualized multifactorial treatment) versus standard care on RNA oxidation level in patients with T2D and to assess if the effect of structured personal care on all-cause and diabetes-related mortality was modified by RNA oxidation level. METHODS: Urine samples were analyzed for 8-oxoGuo/8-oxodG from 1381 newly diagnosed T2D patients from the cluster randomized trial Diabetes Care in General Practice cohort, and 970 patients were reexamined after six years of intervention. RESULTS: The yearly variation in RNA oxidation levels were not significantly different between the structured personal care group and standard care group. The effect of treatment on all-cause and diabetes-related mortality was not modified by the level of RNA oxidation. No changes in DNA oxidation were seen. CONCLUSIONS: Structured personal care does not influence RNA oxidation level nor is it better for patients with high RNA oxidation level. Thus, structured personal care may not impact the disease-related aspects identified by RNA oxidation level in T2D patients.

Oxidatively generated modifications to nucleic acids in vivo: Measurement in urine and plasma.

BACKGROUND: The oxidized guanine nucleosides, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), derived from DNA and RNA, respectively, were used to investigate the importance of oxidative stress to nucleic acids in vivo. High urinary excretion of 8-oxodG is associated with cancer development, whereas high urinary excretion of 8-oxoGuo is associated with mortality in type 2 diabetes. Like creatinine, these small water-soluble molecules are not reabsorbed in the kidney. Therefore, 8-oxo nucleoside/creatinine reciprocal concentration ratios are identical in plasma and urine. The total amount of 8-oxo guanine nucleosides excreted by the kidneys is the product of plasma concentration and glomerular filtration rate. METHODS: With relevant equations and an estimated glomerular filtration rate, the 24-h urinary excretion of 8-oxodG and 8-oxoGuo was calculated in 2679 subjects with type 2 diabetes, displaying good correlation with the measured urinary 8-oxo nucleoside/creatinine ratio: DNA oxidation r = 0.86 and RNA oxidation r = 0.84 (p < 0.05 for both). RESULTS: Survival analyses based on the quartiles of the 8-oxodG/creatinine ratio and the quartiles of calculated 24-h urinary excretion rate of the 2679 subjects gave similar hazard ratio estimates for death due to all causes. This finding was similar for the 8-oxoGuo hazard ratio estimates. CONCLUSIONS: This study shows that oxidatively generated modifications to DNA and RNA in vivo can be measured using 1) a spot urine sample, normalized to urinary creatinine, 2) 24-h urine, or 3) a single plasma sample based on concentrations of 8-oxo nucleoside and creatinine and glomerular filtration rate.

Indicator of RNA oxidation in urine for the prediction of mortality in patients with type 2 diabetes and microalbuminuria: A post-hoc analysis of the Steno-2 trial.

OBJECTIVE: The RNA oxidation product, 8-oxo-7,8-dihydroguanosine (8-oxoGuo), has been associated with mortality in patients with type 2 diabetes (T2D). However, the identification and the potential effect of approved treatments decreasing urine 8-oxoGuo level remain unraveled. In the Steno-2 study intensified multifactorial treatment compared with conventional multifactorial treatment reduced mortality in T2D patients with microalbuminuria by 45%. We assessed association between 8-oxoGuo at advanced baseline and total mortality with up to 19.9 years follow-up and from end of intervention to end of follow-up up to (up to 13.9 years). MATERIALS AND METHODS: In 1993, 160 T2D patients with microalbuminuria were included in the Steno-2 trial. Urine samples from baseline were not available, but samples were available from 155 patients (97%) in 1995 (advanced baseline) and from 125 patients (96%) in 2001 (end of intervention). Hazard ratios (HR) for log2-transformed 8-oxoGuo and dichotomized (cut-off at median; low vs. high RNA oxidation) were estimated using Cox regressions. RESULTS: During follow-up of 19.9 years after advanced baseline, 89 died and no association between 8-oxoGuo and mortality was found (p = 0.40). From the end of 7.8 years of intervention and during remaining 13.9 years of observation, 61 died and doubling the urine 8-oxoGuo level was associated with mortality with a HR 3.08 (95% CI [1.86 -5.12]; p < 0.001) after multiple adjustments. Patients with low 8-oxoGuo in the intensified-treatment had the lowest risk of dying compared with high 8-oxoGuo in the conventional-treatment both from advanced baseline onwards, adjusted HR 0.40 (95% CI [0.21 -0.75]; p = 0.004), and from end of intervention onwards, adjusted HR 0.28 (95% CI [0.13 -0.61]; p = 0.001). CONCLUSIONS: In T2D patients with microalbuminuria, high levels of urine 8-oxoGuo after 7.8 years of multifactorial intervention was associated with higher mortality during 13.9 years of post-trial follow-up. Patients with low 8-oxoGuo in the intensified treatment group had the lowest risk of dying.

RNA oxidation and iron levels in patients with diabetes.

AIM: The urinary biomarker for oxidative stress to RNA, 8-oxo-7,8-dihydro-guanosine (8-oxoGuo) is associated with mortality in patients with type 2 diabetes. Iron has also been linked to diabetes. In individuals with untreated hereditary iron overload it has been observed that 8-oxoGuo was higher compared to controls. In the current study, we hypothesized that 8-oxoGuo was associated with diagnosis of diabetes, and that iron confounded this association. METHODS: Participants from a general Danish population were included in the study (n = 3567). UPLC-MS/MS method was used for 8-oxoGuo (nmol/mmol creatinine) measurement in spot urine. Iron biomarkers included total plasma iron, ferritin, transferrin saturation (TS) and transferrin. RESULTS: 8-oxoGuo was 17% higher in diabetes patients (n = 208) compared to non-diabetes controls. Unadjusted logistic regression model showed an odds ratio of diabetes of 1.38 (95%CI:1.21-1.57, P < 0.0001) per unit increase of 8-oxoGuo. When the model was adjusted for possible confounders the odds ratio was 1.09 (95%CI:0.94-1.26, P = 0.24). When additional adjustment was performed including ferritin, TS, or transferrin, respectively, the OR were 1.14 (95%CI:0.97-1.33, P = 0.09), 1.10 (95%CI: 0.95-1.28, P = 0.18), and 1.17 (95%CI:1.01-1.38, P = 0.04). CONCLUSIONS: Our study indicates that 8-oxoGuo is higher in diabetes patients. The lack of association between 8-oxoGuo and diabetes in the adjusted model may be due to the cross-sectional design including post-treatment bias. Our data did not show consistent effect of all iron biomarkers in relation to diabetes. Most likely, the iron biomarkers were affected by inflammation thus not reflecting true iron levels.

Iron induced RNA-oxidation in the general population and in mouse tissue.

Iron promotes formation of hydroxyl radicals by the Fenton reaction, subsequently leading to potential oxidatively generated damage of nucleic acids. Oxidatively generated damage to RNA, measured as 8-oxo-7,8-dihydroguanosine (8-oxoGuo) in urine, is increased in patients with genetic iron overload, which have led us to test the hypothesis that high iron status, assessed by iron biomarkers and genetic disposition, increases urinary excretion of 8-oxoGuo. In a general Danish population study we used a Mendelian randomization design with HFE genotypes as a proxy for iron status and supplemented with ex vivo experiments in mice muscle tissue exposed to iron(II) sulfate to attempt to clarify this hypothesis. The biomarkers ferritin, transferrin, and transferrin saturation (TS) were associated with 8-oxoGuo (in linear univariable and multivariable regression analyses: P < 0.001). Mendelian randomization indicated a causal pathway between genetically elevated iron biomarkers (assessed by ferritin and TS) and high levels of 8-oxoGuo. The ex vivo experiments showed a monotonically increase in 8-oxoGuo with increased iron concentration (ANOVA: P = 0.0008) that was prevented with iron chelation (P = 0.01). Our results indicate a causal relationship between iron biomarkers and 8-oxoGuo. Furthermore, the ex vivo experiment shows a mechanistic link between iron and 8-oxoGuo formation. Both iron overload and the biomarker 8-oxoGuo have been linked to e.g. diabetes, which merits future studies to investigate if iron induced 8-oxoGuo is involved in disease development.

The effect of empagliflozin on oxidative nucleic acid modifications in patients with type 2 diabetes: protocol for a randomised, double-blinded, placebo-controlled trial.

INTRODUCTION: Cardiovascular disease is the leading cause of morbidity and mortality in patients with type 2 diabetes (T2D). Although glycaemic control reduces microvascular complications, the effect of intensive treatment strategies or individual drugs on macrovascular diseases is still debated. RNA oxidation is associated with increased mortality in patients with T2D. Inspired by animal studies showing effect of a sodium-glucose cotransporter-2 (SGLT-2) inhibitor (empagliflozin) on oxidative stress and a recent trial evaluating empagliflozin that demonstrated improved cardiovascular outcomes in patients with T2D at high risk of cardiovascular events, we hypothesise that empagliflozin lowers oxidative stress. METHODS AND ANALYSIS: In this randomised, double-blinded and placebo-controlled study, 34 adult males with T2D will be randomised (1:1) to empagliflozin or placebo once daily for 14 days as add-on to ongoing therapy. The primary endpoints will be changes in 24-hour urinary excretion of 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) determined before and after intervention (by ultra-performance liquid chromatography tandem mass-spectrometry). Additionally, fasting levels of malondialdehyde (MDA) will be determined in plasma before and after intervention (by high-performance liquid chromatography). Further, the plasma levels of iron, transferrin, transferrin-saturation, and ferritin are determined to correlate the iron metabolism to the markers of oxidative modifications. ETHICS AND DISSEMINATION: The study protocol has been approved by the Regional Committee on Biomedical Research Ethics (approval number H-16017433), the Danish Medicines Agency, and the Danish Data Protection Agency, and will be carried out under the surveillance and guidance of the GCP unit at Bispebjerg Frederiksberg Hospital, University of Copenhagen in compliance with the ICH-GCP guidelines and in accordance with the Declaration of Helsinki. The results of this study will be presented at national and international conferences, and submitted to a peer-reviewed international journal with authorship in accordance with Internation Committee of Medical Journal Editors (ICMJE) Recommendations state. TRIAL REGISTRATION: Study name: EMPOX; Pre-results: clinicaltrials.gov (NCT02890745). Protocol version 5.1 - August, 2016.