Assessing Free-Radical-Mediated DNA Damage during Cardiac Surgery: 8-Oxo-7,8-dihydro-2'-deoxyguanosine as a Putative Biomarker

Transcriptomic responses of peripheral blood leukocytes to cardiac surgery after acute inflammation, and three months recovery

Traumatic perioperative conditions may trigger early systemic responses, activate leukocytes and reprogram the immune system. We hypothesize that leukocyte activation may not revert to pre-surgical states, and that protracted activation may emerge with increased risks of comorbidities. We tested this concept by examining the transcriptomes of monocytes and T cells in a representative observational cohort of patients (n = 13) admitted for elective cardiac surgery. Transcriptomes in T cells and monocytes were compared from before surgery (t0), and monocytes were analyzed longitudinally after acute (t24hr), and convalescent (t3m) time points. Monocytes and T cells expressed distinct transcriptomes, reflected by statistically significant differential expression of 558 T cell related genes. Monocytes expressed genes related to protein degradation and presented atypical activation of surface markers and cytoplasmic functions over time. Additionally, monocytes exhibited limited transcriptomic heterogeneity prior to surgery, and long-term patterns of gene expression associated with atherosclerosis showed three temporally distinct signatures. These data establish that post-cardiac surgery transcriptomes of monocytes differ even at three months compared to baselines, which may reflect latent ('smoldering') inflammation and persistent progression of tissue degenerative processes that should inform clinical care.

GSTM2 alleviates heart failure by inhibiting DNA damage in cardiomyocytes

BACKGROUND

Heart failure (HF) seriously threatens human health worldwide. However, the pathological mechanisms underlying HF are still not fully clear.

RESULTS

In this study, we performed proteomics and transcriptomics analyses on samples from human HF patients and healthy donors to obtain an overview of the detailed changes in protein and mRNA expression that occur during HF. We found substantial differences in protein expression changes between the atria and ventricles of myocardial tissues from patients with HF. Interestingly, the metabolic state of ventricular tissues was altered in HF samples, and inflammatory pathways were activated in atrial tissues. Through analysis of differentially expressed genes in HF samples, we found that several glutathione S-transferase (GST) family members, especially glutathione S-transferase M2-2 (GSTM2), were decreased in all the ventricular samples. Furthermore, GSTM2 overexpression effectively relieved the progression of cardiac hypertrophy in a transverse aortic constriction (TAC) surgery-induced HF mouse model. Moreover, we found that GSTM2 attenuated DNA damage and extrachromosomal circular DNA (eccDNA) production in cardiomyocytes, thereby ameliorating interferon-I-stimulated macrophage inflammation in heart tissues.

CONCLUSIONS

Our study establishes a proteomic and transcriptomic map of human HF tissues, highlights the functional importance of GSTM2 in HF progression, and provides a novel therapeutic target for HF.

8-Hydroxy-2-Deoxyguanosine and 8-Iso-Prostaglandin F2α: Putative Biomarkers to assess Oxidative Stress Damage Following Robot-Assisted Radical Prostatectomy (RARP)

Objective: Prostate cancer (PCa) is the most common type of cancer. Biomarkers help researchers to understand the mechanisms of disease and refine diagnostic panels. We measured urinary 8-hydroxy-2-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin F2α (8-IsoF2α) to assess oxidative stress damage in PCa patients undergoing robot-assisted radical prostatectomy (RARP). Methods: Forty PCa patients were enrolled in the study. Urine was collected before (T0) and 3 months after the RARP procedure (T1). 8-OHdG and 8-IsoF2α were measured through liquid chromatography-tandem mass spectrometry. Sex- and age-matched healthy subjects served as controls (CTRL). Results: At T0, patients exhibited significantly higher levels of 8-OHdG than CTRL (p = 0.026). At T1, 23/40 patients who completed the 3-month follow-up showed levels of 8-OHdG that were significantly lower than at T0 (p = 0.042), and comparable to those of the CTRL subjects (p = 0.683). At T0, 8-Iso-PGF2α levels were significantly higher in PCa patients than in CTRL subjects (p = 0.0002). At T1, 8-Iso-PGF2α levels were significantly lower than at T0 (p < 0.001) and were comparable to those of CTRL patients (p = 0.087). Conclusions: A liquid chromatography-tandem mass spectrometry method reveals enhanced OHdG and 8-Iso-PGF2α in the urine of PCa patients. RARP normalizes such indices of oxidative stress. Large-sized sample studies and long-term follow-ups are now needed to validate these urinary biomarkers for use in the early prevention and successful treatment of PCa.

Recent progress in the LC-MS/MS analysis of oxidative stress biomarkers

The presence of a dynamic and balanced equilibrium between the production of reactive oxygen (ROS) and nitrogen (RNS) species and the in-house antioxidant defense mechanisms is characteristic for a healthy body. During oxidative stress (OS), this balance is switched to increased production of ROS and RNS, exceeding the capacity of physiological antioxidant systems. This can cause damage to biological molecules, leading to loss of function and even cell death. Nowadays, there is increasing scientific and clinical interest in OS and the associated parameters to measure the degree of OS in biofluids. An increasing number of reports using LC-MS/MS methods for the analysis of OS biomarkers can be found. Since bioanalysis is usually complicated by matrix effects, various types of cleanup procedures are used to effectively separate the biomarkers from the matrix. This is an essential part of the analysis to prepare a reproducible and homogenous solution suitable for injection onto the column. The present review gives a summary of the chromatographic methods used for the determination of OS biomarkers in both urine and plasma, serum, and whole blood samples. The first part mainly describes the biological background of the different OS biomarkers, while the second part reports examples of chromatographic methods for the analysis of different metabolites connected with OS in biofluids, covering a period from 2015 till early 2020. The selected examples mainly include LC-MS/MS methods for isoprostanes, oxidized proteins, oxidized lipoproteins, and DNA/RNA biomarkers. The last part explains the clinical relevance of this review.

Cardiac arrhythmia catheter ablation procedures guided by x-ray imaging: N-acetylcysteine protection against radiation-induced cellular damage (CARAPACE study): study design

PURPOSE

Catheter ablation (CA) procedures are characterized by exposure to ionizing radiations (IR). IR can cause DNA damage and may lead to carcinogenesis if not efficiently repaired. The primary endpoint of this study is to investigate whether intravenous administration of N-acetylcysteine prior to CA procedure may prevent systemic oxidative stress and genomic DNA damage induced by exposure to IR.

METHODS

The "Cardiac Arrhythmia catheter ablation procedures guided by x-Ray imaging: N-Acetylcysteine Protection Against radiation induced Cellular damagE" (CARAPACE) study is a prospective, randomized, single-blinded, parallel-arm monocenter study enrolling 550 consecutive patients undergoing CA at the Arrhythmology Unit of Centro Cardiologico Monzino (CCM). Inclusion criteria are age ≥ 18, indication for CA procedure guided by IR imaging, and written informed consent. IR levels will be measured via fluoroscopy time, effective dose, and dose area product. Glutathione and glutathione disulfide concentrations will be measured, and urinary levels of 8-iso-prostaglandin-F_2α and 8-hydroxy-2-deoxyguanosine will be quantified. The enrolled patients will be randomized 1:1 to the N-acetylcysteine group or to the control group.

RESULTS

We expect that pre-operative administration of N-acetylcysteine will prevent IR-induced systemic oxidative stress. The study will provide data on oxidative DNA damage assessed by urinary 8-hydroxy-2-deoxyguanosine levels and direct evidence of genomic DNA damage in blood cells by comet assay.

CONCLUSION

Catheter ablation procedures can lead to IR exposure and subsequent DNA damage. N-acetylcysteine administration prior to the procedure may prevent them and therefore lead to less possible complications.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04154982).

Molecular Scavengers, Oxidative Stress and Cardiovascular Disease

Cardiovascular disease (CVD) is the number one cause of deaths worldwide, with yearly deaths due to atherothrombosis-i [...].

Does Fluoroscopy Induce DNA Oxidative Damage in Patients Undergoing Catheter Ablation?

As no studies before now have thoroughly investigated the risk associated with the exposure to low-dose ionizing radiations in patients undergoing catheter ablation (CA), we aimed to evaluate the oxidative and DNA damage in 59 CA patients (10 of whom received N-acetylcysteine (NAC) before the procedure). A burst of oxidized/reduced glutathione ratio was observed 3 hours after procedure that was diminished by NAC administration. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) concentrations, index of oxidative DNA damage, showed a peak 24 hours after CA. A positive correlation between 8-OHdG peak and fluoroscopy time and a negative correlation among 8-OHdG decrease (from the peak to 48 hours after CA) and all procedure parameters were found. Furthermore, DNA tail percentages (which reflect the extent and the number of DNA strand breaks) positively correlated with 8-OHdG concentrations. This study evaluates for the first time the kinetic of oxidative damage in patients undergoing CA procedure. Our findings raise the question of whether 8-OHdG can be used as a circulating biomarker of DNA oxidative damage induced by low-dose ionizing radiations in different clinical settings. Antioxid. Redox Signal. 28, 1137-1143.