Clinical relevance of guanine-derived urinary biomarkers of oxidative stress, determined by LC-MS/MS

Abstract

A reliable and fast liquid chromatography-tandem mass spectrometry method has been developed for the simultaneous determination of three oxidized nucleic acid damage products in urine, 8-oxoguanine (8-oxoGua), 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo). We applied this method to assess the effect of various urine workup procedures on the urinary concentrations of the oxidized nucleic acid products. Our results showed that frozen urine samples must be warmed (i.e., to 37 °C) to re-dissolve any precipitates prior to analysis. We showed that common workup procedures, such as thawing at room temperature or dilution with deionized water, are not capable of releasing fully the oxidized nucleic acid products from the precipitates, and result in significant underestimation (up to ~ 100% for 8-oxoGua, ~ 86% for both 8-oxodGuo and 8-oxoGuo).With this method, we further assessed and compared the ability of the three oxidized nucleic acid products, as well as malondialdehyde (MDA, a product of lipid peroxidation), to biomonitor oxidative stress in vivo. We measured a total of 315 urine samples from subjects with burdens of oxidative stress from low to high, including healthy subjects, patients with chronic obstructive pulmonary disease (COPD), and patients on mechanical ventilation (MV). The results showed that both the MV and COPD patients had significantly higher urinary levels of 8-oxoGua, 8-oxodGuo, and 8-oxoGuo (P < 0.001), but lower MDA levels, compared to healthy controls. Receiver operating characteristic curve analysis revealed that urinary 8-oxoGuo is the most sensitive biomarker for oxidative stress with area under the curve (AUC) of 0.91, followed by 8-oxodGuo (AUC: 0.80) and 8-oxoGua (AUC: 0.76). Interestingly, MDA with AUC of 0.34 failed to discriminate the patients from healthy controls. Emerging evidence suggests a potential clinical utility for the measurement of urinary 8-oxoGuo, and to a lesser extent 8-oxodGuo, which is strongly supported by our findings.

Statin treatment, oxidative stress and inflammation in a Danish population

“…We observed differential effects on DNA and RNA oxidation, a phenomenon also observed after intervention with olive oil [33]. A recent study also found such a differential effect in diseases, however, favoring RNA oxidation as a marker [6]. The underlying mechanisms for the differences between DNA and RNA oxidation are not known in detail, and the exact origin of the oxidized nucleotides is still unclear [7], [8].…”

“…The exact source of 8-oxodG and 8-oxoGuo is still debatable. However, the current acceptable interpretation is that they reflect the rate of guanine oxidation in the nucleic acids and their precursor pools [5], [6], [7], [8]. Increased levels of 8-oxodG and 8-oxoGuo are associated with aging, smoking, type 2 diabetes mellitus (T2DM), hypertension, neurodegenerative diseases, cardiovascular disease (CVD) and certain cancers [4], [9], [10], [11], [12].…”

Reliability and Usefulness of Different Biomarkers of Oxidative Stress in Chronic Obstructive Pulmonary Disease

“…By means of these methods, a significant increase or no differences in the levels of DNA damage has been detected in the blood and urine of COPD patients compared to the controls; however, a significant increase has been found in sputum. [25,30,37,43,75,[92][93][94][95][96][97] (Table 2).…”

Exenatide inhibits NF-κB and attenuates ER stress in diabetic cardiomyocyte models

“…Secondary antibodies conjugated to Alexa fluorophores were purchased from Molecular Probes (Life Technologies). DAPI was used to stain nuclei [59]. For some co-localization experiments, when two primary antibodies were raised in rabbits, one of the primary antibodies was detected using the regular procedure, while the second primary antibody was conjugated with Alexa fluorophore 488 using a commercially available kit (Life Technologies) [60].…”