Antonella Mercuri

Increased circulating cell-free DNA levels and mtDNA fragments in interventional cardiologists occupationally exposed to low levels of ionizing radiation

Circulating cell‐free DNA (ccf‐DNA) and mtDNA (ccf‐mtDNA) have often been used as indicators of cell death and tissue damage in acute and chronic disorders, but little is known about changes in ccf‐DNA and ccf‐mtDNA concentrations following radiation exposure. The aim of the study was to investigate the impact of chronic low‐dose radiation exposure on serum ccf‐DNA levels and ccf‐mtDNA fragments (mtDNA‐79 and mtDNA‐230) of interventional cardiologists working in high‐volume cardiac catheterization laboratory to assess their possible role as useful radiation biomarkers. We enrolled 50 interventional cardiologists (26 males; age = 48.4 ± 10 years) and 50 age‐ and gender‐matched unexposed controls (27 males; age = 47.6 ± 8.3 years). Quant‐iT™ dsDNA High‐Sensitivity assay was used to measure circulating ccf‐DNA isolated from serum samples. Quantitative analysis of mtDNA fragments was performed by real‐time PCR. No significant relationships were found between ccf‐DNA and ccf‐mtDNA, and age, gender, smoking, or other clinical parameters. Ccf‐DNA levels (44.2 ± 31.1 vs. 30.6 ± 19.2 ng/ml, P = 0.013), ccf‐mtDNA‐79 (2.6 ± 2.1 vs. 1.1 ± 0.8, P < 0.01), and ccf‐mtDNA‐230 copies (2.0 ± 1.8 vs. 1.04 ± 0.9, P = 0.02) were significantly higher in interventional cardiologists compared with the non‐exposed group. In a subset (n = 15) of interventional cardiologists with a reliable reconstruction of cumulative professional exposure (59.7 ± 48.4 mSv; range: 1.4–182 mS), ccf‐DNA (53.2 ± 41.3 vs. 36.4 ± 22.9 and 32.2 ± 20.5, P = 0.08), mtDNA‐79 (2.4 ± 2.1 vs. 2.03 ± 1.7 and 1.09 ± 0.82, P = 0.05), and mtDNA‐230 (2.0 ± 2.2 vs. 1.5 ± 1.4 and 1.04 ± 0.9, P = 0.09) tended to be significantly increased in high‐exposure subjects compared with both low‐exposure interventional cardiologists and controls. Our results provide evidence for a possible role of circulating DNA as a relevant biomarker of cellular damage induced by exposure to chronic low‐dose radiation. Environ. Mol. Mutagen. 56:293–300, 2015.

Arsenic exposure, genetic susceptibility and leukocyte telomere length in an Italian young adult population

Arsenic-induced health effects may be associated with critically shortened telomeres. However, few data are available on the effects of arsenic exposure on telomere length. The aim of this study was to investigate the effects of chronic arsenic exposure on leukocyte telomere length (LTL) as well as the contribution of common polymorphisms in genes implicated in arsenic metabolism (GSTT1 and GSTM1) and DNA repair (hOGG1 and XRCC1). A group of 241 healthy subjects was enrolled from four areas of Italy known to be affected by natural or anthropogenic arsenic pollution. Urine samples were tested for inorganic As (iAs), monomethylarsinic (MMA) and dimethylarsinic acid (DMA). LTL was evaluated by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Genotyping was carried out by PCR-RFLP on leukocyte DNA. In multiple linear regression analysis, LTL was significantly and inversely correlated with age (β = -0.231, P = 0.006) and showed a certain trend toward significance with iAs urinary concentration (log10 iAs, β = -0.106, P = 0.08). The genotype distribution showed significant associations between GSTT1 and the As concentration (log10 iAs, P = 0.01) and metabolite patterns (log10 DMA, P = 0.05) in the urine. However, GST genes did not interact with arsenic exposure in the modulation of LTL. Conversely, the combined presence of a higher level of iAs + MMA + DMA ≥ 19.3 μg/l (F = 6.0, P interaction = 0.01), Asi ≥ 3.86 (F = 3.9, P interaction = 0.04) μg/l, iAs + MMA + DMA ≥ 15 μg/l (F = 4.2, P interaction = 0.04) and hOGG1 Cys allele was associated with a significantly lower LTL. An interaction between XRCC1 Arg399Gln and arsenic exposure was also observed (all P interaction = 0.04). These findings suggest that telomere shortening may represent a mechanism that contributes to arsenic-related disease. The interaction of hOGG1 and XRCC1 DNA repair polymorphisms and exposure enhances telomeric DNA damage. Future studies are warranted to understand better the epidemiologic impact of arsenic on telomere function as well as to identify the subgroups of exposed subjects who need better health surveillance.

Stromal cell-derived factor-1-3'A polymorphism is associated with decreased risk of myocardial infarction and early endothelial disturbance.

Aim Genome-wide association studies have identified single-nucleotide polymorphisms at the 10q11 locus as risk factors for myocardial infarction (MI). This locus lies upstream (∼80 kb) of the stromal cell-derived factor-1 (SDF1) gene that codify for a chemokine with protective atherogenetic effects and with a major role in the mobilization, homing, and differentiation of endothelial progenitor cells (EPCs). The purpose of this study was to investigate the possible association of SDF1–3′A polymorphism, that upregulates SDF1 protein expression, with MI and early endothelial dysfunction and atherosclerosis in young healthy subjects. Methods 200 patients (181 men age 57.3 ± 7.7 years) and 230 healthy controls (96 men, age 52 ± 11.9 years) were recruited to investigate the association between MI and SDF1–3′A polymorphism. The relationship between SDF1–3′A polymorphism and brachial artery flow-mediated dilation and the number of circulating EPCs was examined in 50 healthy young adults. Results A significant difference in SDF1–3′A genotype distribution was observed between patients and controls (P = 0.006). Patients carrying the A allele had a significantly reduced MI risk compared with subjects with GG genotype (odds ratio = 0.5, 95% CI = 0.3–0.9, P = 0.001). SDF1–3′A polymorphism presented a significant interaction with other cardiovascular risk factors (Pinteraction < 0. 0001). Controls carrying the A allele showed significantly higher flow-mediated dilation (13.9 ± 4.9 vs 10.8 ± 4.3, P = 0.03) and significantly higher values of EPCs (0.029 ± 0.009 vs 0.022 ± 0.008, P = 0.02) compared with GG homozygotes. Conclusion SDF1–3′A polymorphism is associated with a decreased risk of MI and early endothelial dysfunction, strongly confirming the important atherogenic role of SDF1 gene at clinical level.

Effects of Highly Polluted Environment on Sperm Telomere Length: A Pilot Study

High environmental pressure may impair male fertility by affecting sperm quality, but the real effect remains controversial. Herein, we assessed the influence of environmental exposure on telomere length (TL) in both leukocytes (LTL) and sperm cells (STL). A pilot biomonitoring study was conducted in 112 clinically healthy, normospermic men living in various areas of Campania region (South of Italy) with high (n = 57, High Group) or low (n = 55, Low Group) environmental pressure. TL analysis was assessed by quantitative real time-PCR. STL was not significantly correlated with either age (p = 0.6) or LTL (p = 0.7), but was significantly longer in the High Group compared with the Low Group (p = 0.04). No significant difference was observed between leukocyte TL in the High or Low Group. Our results showed that male residents in areas with high environment exposure had a significant increase in STL. This finding supports the view that the human semen is a sentinel biomarker of environmental exposure.

Low-Dose Exposure to Ionizing Radiation Deregulates the Brain-Specific MicroRNA-134 in Interventional Cardiologists

Editorial, see p 2417 In recent years, there has been growing concern about the health risks for contemporary interventional cardiologists who have high and unprecedented levels of occupational ionizing radiation exposure.1 MicroRNAs (miRNAs), a class of short and highly conserved noncoding RNA molecules (≈22 nucleotides), have been shown to become dysregulated in many human diseases.2 The stability and tissue specificity of circulating miRNAs make them ideal biomarkers to explore the molecular mechanisms underlying the association between chronic low-dose radiation exposure and potential disease risk. The purpose of this study was to apply a miRNome-wide microarray to characterize the plasma miRNA profiles in interventional cardiologists professionally exposed to ionizing radiation. The study consisted of 3 stages: discovery, selection, and validation. In the discovery stage, a microarray analysis (Agilent Human miRNA Microarray 8×60K Release 19.0 platform containing 2006 human miRNA probes) was performed on plasma from 10 interventional cardiologists (6 men; age, 54±5.4 years) and 10 age- and sex-matched unexposed control subjects (6 men; age, 53.2±5.5 years). In the selection stage, all dysregulated miRNAs were evaluated in another 80 plasma samples (40 from interventional cardiologists and 40 from unexposed subjects) by quantitative real-time polymerase chain reaction. …

Prognostic value of mitochondrial DNA4977 deletion and mitochondrial DNA copy number in patients with stable coronary artery disease

BACKGROUND AND AIMS Mitochondrial DNA copy number (mtDNA-CN) depletion has been recently associated with an increased cardiovascular risk. However, the integrity of mtDNA is another key aspect of the energy metabolism and mitochondrial function. We investigated the prognostic role of peripheral blood common mitochondrial deletion (mtDNA4977) and mtDNA-CN on long-term major adverse cardiac events (MACEs) and all-cause mortality in a cohort of patients with coronary artery disease (CAD). METHODS Within the Italian GENOCOR (Genetic Mapping for Assessment of Cardiovascular Risk) cohort, we studied 515 patients (450 males, 65 ± 8 years) with known or suspected stable CAD. mtDNA4977 deletion and mtDNA-CN were assessed in peripheral blood using qRT-PCR. RESULTS During a mean follow-up of 4.5 ± 1.1 years, 78 (15%) patients had MACEs (15 cardiac deaths, 17 nonfatal myocardial infarction and 46 coronary revascularizations) and 28 patients died for non-cardiac causes. Patients with high levels of mtDNA4977 deletion (>75th) had increased risk of MACEs (log rank = 7.2, p=0.007) and all-cause mortality (log rank = 5.7, p=0.01) compared with patients with low mtDNA4977 deletion (≤75th). Multivariate Cox regression analysis showed that log mtDNA4977 was a significant predictor of MACEs (HR = 2.17; 95% CI, 1.31-3.59; p=0.003) and all-cause mortality (HR = 2.03; 95% CI: 1.13-3.65, p=0.02). Log mtDNA-CN was not significantly associated with MACEs or all-cause mortality. However, patients with high mtDNA4977 deletion (>75th) and low mtDNA-CN (<25th) had significantly increased risk for MACEs (HR: 3.73; 95% CI: 1.79-7.79; p=0.0005). CONCLUSIONS Mitochondria DNA damage was associated with an increased risk of MACEs and all-cause mortality in patients with stable CAD, confirming the critical role of mitochondrial dysfunction in atherosclerosis.