Circulating mitochondrial DNA as biomarker linking environmental chemical exposure to early preclinical lesions elevation of mtDNA in human serum after exposure to carcinogenic halo-alkane-based pesticides

There is a need for a panel of suitable biomarkers for detection of environmental chemical exposure leading to the initiation or progression of degenerative diseases or potentially, to cancer. As the peripheral blood may contain increased levels of circulating cell-free DNA in diseased individuals, we aimed to evaluate this DNA as effect biomarker recognizing vulnerability after exposure to environmental chemicals. We recruited 164 individuals presumably exposed to halo-alkane-based pesticides. Exposure evaluation was based on human biomonitoring analysis; as biomarker of exposure parent halo-methanes, -ethanes and their metabolites, as well as the hemoglobin-adducts methyl valine and hydroxyl ethyl valine in blood were used, complemented by expert evaluation of exposure and clinical intoxication symptoms as well as a questionnaire. Assessment showed exposures to halo alkanes in the concentration range being higher than non-cancer reference doses (RfD) but (mostly) lower than the occupational exposure limits. We quantified circulating DNA in serum from 86 individuals with confirmed exposure to off-gassing halo-alkane pesticides (in storage facilities or in home environment) and 30 non-exposed controls, and found that exposure was significantly associated with elevated serum levels of circulating mitochondrial DNA (in size of 79 bp, mtDNA-79, p = 0.0001). The decreased integrity of mtDNA (mtDNA-230/mtDNA-79) in exposed individuals implicates apoptotic processes (p = 0.015). The relative amounts of mtDNA-79 in serum were positively associated with the lag-time after intoxication to these chemicals (r = 0.99, p<0.0001). Several months of post-exposure the specificity of this biomarker increased from 30% to 97% in patients with intoxication symptoms. Our findings indicate that mitochondrial DNA has a potential to serve as a biomarker recognizing vulnerable risk groups after exposure to toxic/carcinogenic chemicals.

Decreased mitochondrial DNA content in association with exposure to polycyclic aromatic hydrocarbons in house dust during wintertime: from a population enquiry to cell culture

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants that are formed in combustion processes. At the cellular level, exposure to PAHs causes oxidative stress and/or some of it congeners bind to DNA, which may interact with mitochondrial function. However, the influence of these pollutants on mitochondrial DNA (mtDNA) content remains largely unknown. We determined whether indoor exposure to PAHs is associated with mitochondrial damage as represented by blood mtDNA content. Blood mtDNA content (ratio mitochondrial/nuclear DNA copy number) was determined by real-time qPCR in 46 persons, both in winter and summer. Indoor PAH exposure was estimated by measuring PAHs in sedimented house dust, including 6 volatile PAHs and 8 non-volatile PAHs. Biomarkers of oxidative stress at the level of DNA and lipid peroxidation were measured. In addition to the epidemiologic enquiry, we exposed human TK6 cells during 24 h at various concentrations (range: 0 to 500 µM) of benzo(a)pyrene and determined mtDNA content. Mean blood mtDNA content averaged (±SD) 0.95±0.185. The median PAH content amounted 554.1 ng/g dust (25^th–75^th percentile: 390.7–767.3) and 1385ng/g dust (25^th–75^th percentile: 1000–1980) in winter for volatile and non-volatile PAHs respectively. Independent for gender, age, BMI and the consumption of grilled meat or fish, blood mtDNA content decreased by 9.85% (95% CI: −15.16 to −4.2; p = 0.002) for each doubling of non-volatile PAH content in the house dust in winter. The corresponding estimate for volatile PAHs was −7.3% (95% CI: −13.71 to −0.42; p = 0.04). Measurements of oxidative stress were not correlated with PAH exposure. During summer months no association was found between mtDNA content and PAH concentration. The ability of benzo(a)pyrene (range 0 µM to 500 µM) to lower mtDNA content was confirmed in vitro in human TK6 cells. Based on these findings, mtDNA content can be a target of PAH toxicity in humans.

A role for mitochondria in gestational diabetes mellitus?

Mitochondrial activity is critical for maintenance of correct glucose homeostasis and alteration in mitochondrial content or function may progressively lead to the development of insulin resistance. Evidence on the possible role of mitochondria in the pathogenesis of gestational diabetes mellitus (GDM) is conversely scanty and inconsistent. The aim was to evaluated mitochondrial DNA (mtDNA) content in peripheral blood of pregnant women with GDM. We selected 25 pregnant women affected by GDM and 50 controls with physiological pregnancies. A blood sample was collected at 32-36 weeks' gestation, stored and thawed simultaneously. The mtDNA content was determined utilizing a quantitative real-time polymerase chain reaction by the Taqman method, using a genomic control and a target gene. Results are expressed as copy number per nuclear DNA. The median (interquartile range) mtDNA content in GDM and controls was 122 (107-198) and 170 (129-196), respectively (p = 0.039). The mtDNA content was also correlated to GDM treatment, self-blood glucose monitoring and newborns' weight, but these analyses failed to document any statistically significant association. Attenuated mitochondrial function may play a role in the development of GDM. Further experiments are required to definitely clarify whether this defect represents a primary event in the pathogenesis of the disease.

mtDNA(4977) deletion is not a common feature in patients with premature ovarian failure and primary infertility

The aim of the current study was to investigate the incidence of mtDNA(4977) deletion in peripheral blood leukocytes of patients diagnosed with premature ovarian failure (POF) and primary infertility. The study group consisted of 17 patients with POF, 32 women with primary infertility, and 31 fertile women with the prevalence of the mtDNA(4977) deletion using the reverse transcription-polymerase chain reaction (RT-PCR) based technology. None of the patients affected by POF revealed mtDNA(4977) deletion. This deletion was detected only in one 26-year-old infertile patient. No significant difference in relation to mtDNA(4977) deletion was reported between the groups investigated (p > 0.05). In conclusion, mtDNA(4977) deletion is not a common finding in peripheral blood leukocytes of women affected by POF and primary infertility. The occurrence of mtDNA(4977) deletion in women between 20 and 39 years of age may not increase with increasing patients' age, independently of their fertility status.

Detection and quantification of a radiation-associated mitochondrial DNA deletion by a nested real-time PCR in human peripheral lymphocytes

In this study we implemented a new assay using a nested real-time polymerase chain reaction (PCR) to detect radiation-induced common deletion (CD) in mitochondrial DNA (mtDNA) of human peripheral lymphocytes. A standard curve for real-time PCR was established by applying a plasmid DNA containing human normal mtDNA or mutated mtDNA. Human peripheral lymphocyte DNA was amplified and quantified by real-time PCR using primer sets for total damaged or mutated mtDNA, plus probes labeled with the fluorescent dyes. The first-round PCR generated multiple products were used as the template for a second-round PCR. We herein describe a nested real-time PCR assay capable of quantifying mtDNA bearing the CD in human peripheral lymphocytes following exposure (in vitro) to (137)Cs γ-rays in a dose range of 0.5 up to 5Gy. The reproducibility of this assay was evident for both unirradiated and irradiated samples by examining human blood lymphocytes from 14 donors. This technique was sensitive enough to detect deletions in mtDNA at low dose levels, as low as 0.5Gy, and higher levels of CD mtDNA were evident at higher doses (≥1Gy), however, there was no consistent dose-response relationship.

Lack of evidence for mtDNA as a biomarker of innate immune activation in HIV infection

Many human immunodeficiency virus (HIV) infected individuals suffer from persistent immune activation. Chronic inflammation and immune dysregulation have been associated with an increased risk of age-related diseases even among patients on highly active antiretroviral therapy. The factors leading to immune activation are complex, but have been hypothesized to include persistent viral replication with cellular death as well as microbial translocation across the gastrointestinal tract. Both processes may trigger innate immune responses since many native molecules released from dying cells are similar in structure to pathogen associated molecular patterns. These damage associated molecular patterns include mitochondrial DNA and formylated peptides. We hypothesized that circulating mitochondrial nucleic acid could serve as a biomarker for HIV-associated cell death and drive innate immune activation in infected individuals. We developed a quantitative polymerase chain reaction assay for plasma mitochondrial DNA and validated it on normal blood donors. We then measured mitochondrial DNA levels in acute and chronic HIV infection. While the assay proved to be accurate with a robust dynamic range, we did not find a significant association between HIV disease status and circulating mitochondrial DNA. We did, however, observe a negative correlation between age and plasma mitochondrial DNA levels in individuals with well-controlled HIV.

[Changes of mitochondrial DNA/nuclear DNA ratio in the blood serum following X-ray irradiation of mice at various doses]

Using quantitative real-time PCR, the copy number of mitochondrial and nuclear DNA fragments in mouse blood serum was estimated at different time points following X-ray irradiation at various doses (from 0.5 to 10 Gy). The changes in the correlation between mtDNA and nuclear DNA (mtDNA/nucDNA) in blood serum reflect the degree of radiation injury depending on the dose of irradiation. Exposure to radiation at 10 Gy and massive cell death caused by this lethal dose result in a sharp decrease by an order of magnitude of the mtDNA/nucDNA ratio in the mouse serum; the value of this parameter did not recover within the next 3 days. The opposite effect was revealed when mice were exposed to irradiation at the dose of I Gy, which is not followed by massive cell death, but leads to a higher level of the mtDNA damage as compared with the nuclear DNA protected by histones. Defective mtDNA molecules enter the bloodstream, which results in an increase of the mtDNA/nucDNA ratio in serum. Under irradiation of mice at the intermediate dose of 3 Gy the two processes described above are exhibited at once. During the first hours after irradiation an apoptotic death of radiosensitive cells and release of a large number of nuclear DNA fragments in the serum are initiated, which reduces the mtDNA/nucDNA ratio. However, at later times after irradiation, starting from 5 days, an increase of the mtDNA/nucDNA ratio is observed in the serum, presumably as a result of reparation and elimination of defective mtDNA. Thus, the mtDNA/nucDNA ratio in the serum of irradiated mice reflects the degree of the radiation damage to cells and may be considered as a biological marker of radiation injury in the future.

Clinical features and heteroplasmy in blood, urine and saliva in 34 Dutch families carrying the m.3243A > G mutation

The m.3243A>G mutation has become known as the MELAS mutation. However, many other clinical phenotypes associated with this mutation have been described,most frequently being Maternally Inherited Diabetes and Deafness (MIDD). The m.3243A>G mutation, can be detected in virtually all tissues, however heteroplasmy differs between samples. Recent reports indicate, a preference to perform mutation analysis in Urinary Epithelial Cells(UEC). To test this, and to study a correlation between the mutational load in different tissues with two mitochondrial scoring systems (NMDAS and NPMDS) we investigated 34 families carrying the m.3243A>G mutation. Heteroplasmy was determined in three non-invasively collected samples,namely leucocytes, UEC and buccal mucosa. We included 127 patients, of which 82 carried the m.3243A>G mutation.None of the children (n011) had specific complaints. In adults(n071), a median NMDAS score of 15 (IQR 10-24) was found. The most prevalent symptoms were hearing loss(68 %), gastro-intestinal problems (59 %), exercise intolerance(54 %) and glucose intolerance (52 %). Ten patients had neurologic involvement. Buccal mucosa had the best correlation with the NMDAS in all adults (r00.437, p<0.001),whereas UEC had the strongest correlation with the NMDAS in severely affected patients (r00.593, p00.002). Heteroplasmy declined significantly with increasing age in all three samples (leucocytes r0-0.705 (p<0.001), UEC r0-0.374 (p00.001), buccal mucosa r0-0.460 (p<0.001). In our cohort of 82 patients, the m.3243A>Gmutation causes a wide variety of signs and symptoms, MIDD being far more prevalent than MELAS. Looking at the characteristics of the three noninvasively available tissues for testing heteroplasmy we confirm that UEC are the preferred sample to test [corrected].

Placental mitochondrial DNA content and particulate air pollution during in utero life

BACKGROUND

Studies emphasize the importance of particulate matter (PM) in the formation of reactive oxygen species and inflammation. We hypothesized that these processes can influence mitochondrial function of the placenta and fetus.

OBJECTIVE

We investigated the influence of PM₁₀ exposure during pregnancy on the mitochondrial DNA content (mtDNA content) of the placenta and umbilical cord blood.

METHODS

DNA was extracted from placental tissue (n = 174) and umbilical cord leukocytes (n = 176). Relative mtDNA copy numbers (i.e., mtDNA content) were determined by real-time polymerase chain reaction. Multiple regression models were used to link mtDNA content and in utero exposure to PM₁₀ over various time windows during pregnancy.

RESULTS

In multivariate-adjusted analysis, a 10-µg/m³ increase in PM₁₀ exposure during the last month of pregnancy was associated with a 16.1% decrease [95% confidence interval (CI): -25.2, -6.0%, p = 0.003] in placental mtDNA content. The corresponding effect size for average PM₁₀ exposure during the third trimester was 17.4% (95% CI: -31.8, -0.1%, p = 0.05). Furthermore, we found that each doubling in residential distance to major roads was associated with an increase in placental mtDNA content of 4.0% (95% CI: 0.4, 7.8%, p = 0.03). No association was found between cord blood mtDNA content and PM₁₀ exposure.

CONCLUSIONS

Prenatal PM₁₀ exposure was associated with placental mitochondrial alterations, which may both reflect and intensify oxidative stress production. The potential health consequences of decreased placental mtDNA content in early life must be further elucidated.

Detection of Low Levels of the Mitochondrial tRNALeu(UUR) 3243A>G Mutation in Blood Derived from Patients with Diabetes

BACKGROUND

Mutations in the human mitochondrial genome have been suspected to play a significant role in the etiological development of mitochondrial diabetes. Detection of the 3243A>G mutation in the mitochondrial transfer RNALeu(UUR) gene (MTTL1), especially at low heteroplasmy levels, is highly desirable since it facilitates the diagnosis and subsequent management of the disease. The proportions of mutant mitochondrial DNA (mtDNA) can vary between tissues and are usually significantly higher in muscle than in blood, but muscle biopsies from patients with diabetes are rarely available.

METHODS

Here, we describe a technique that can not only determine the presence of MTTL1 3243A>G, but can also estimate the percentage of mutant DNA. The technique is based on the use of the WAVE system for the high-performance liquid chromatography (HPLC)-mediated analysis of mutation-specific restriction fragments derived from mutant PCR amplicons. PCR amplicon restriction fragment analysis by HPLC (PARFAH) can also be used for the detection of other mutations.

RESULTS

This PARFAH analytical approach led to the discovery of the 3243A>G mutation in blood samples from a series of patients who had initially been reported to lack the mutation, even though matrilineal relatives had been shown to harbor the mutation associated with maternally inherited diabetes and deafness (MIDD) or mitochondrial myopathy encephalopathy lactic acidosis stroke-like episodes (MELAS) phenotypes. We have established that the PARFAH method can reliably detect as little as 1% mutant DNA in a sample, which would normally be missed by commonly used gel electrophoresis or sequencing methods.

CONCLUSIONS

The PARFAH method not only provides a sensitive, high-throughput, and cost-effective strategy for the detection of low levels of mtDNA mutations in peripheral tissues, but also facilitates the estimation of the percentage of mutant DNA in the sample. The fact that samples can be readily obtained from peripheral tissues in many cases will avoid the need for invasive muscle biopsies. Our ability to detect low levels of mtDNA mutations in blood samples of carriers will allow us to reassess the prevalence of the MTTL1 3243A>G mutation in patients with diabetes.

Decreased peripheral blood mitochondrial DNA content is related to HbA1c, fasting plasma glucose level and age of onset in type 2 diabetes mellitus

AIMS

Mitochondrial DNA (mtDNA) content is essential for maintaining normal mitochondrial function, and the mitochondrial function is critical for the production and the release of insulin in Type 2 diabetes mellitus. We investigated whether peripheral blood mtDNA content was reduced in Type 2 diabetes, and what were the major factors?

METHODS

The mtDNA content of peripheral blood in a sample of 147 Type 2 diabetes and 170 normal Chinese subjects was determined by amplification of the mitochondrial gene CYT-B and normalized by a nuclear DNA β-globin gene. Fasting plasma glucose, HbA(1c) , fasting plasma insulin and lipid profile (HDL-cholesterol, LDL-cholesterol, total cholesterol, triglyceride) were analysed with commercial kits on an automatic analyser.

RESULTS

In Type 2 diabetes group, the mean HbA(1c) was 62 mmol/mol (7.8%). Moreover, BMI, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, LDL-cholesterol, triglyceride, fasting plasma insulin and homeostasis model assessment for insulin resistance were significantly higher in Type 2 diabetes group than that in control group. Peripheral blood mtDNA content was 24% lower than that in the controls (1.4 ± 0.5 vs. 1.8 ± 0.7, P < 0.001). The mtDNA content was negatively correlated with BMI, fasting plasma glucose, fasting plasma insulin, homeostasis model assessment for insulin resistance (P < 0.01), and age, triglyceride and LDL-cholesterol levels (P < 0.05); while positively correlated with HDL-cholesterol level (P < 0.05) in both groups. Stepwise regression analysis indicated that HbA(1c), fasting plasma glucose and age of onset were the major factors affecting the mtDNA content in the Type 2 diabetes group; however, BMI was the only variable associated with lower mtDNA content in control group.

CONCLUSION

Our results demonstrate that lower peripheral blood mtDNA content is associated with Type 2 diabetes in Chinese individuals, and HbA(1c), fasting plasma glucose and age of onset are the major factors affecting the mtDNA content.

Plasma nuclear and mitochondrial DNA levels as predictors of outcome in severe sepsis patients in the emergency room

BACKGROUND AND AIM

The sensitivity and specificity of biomarkers and scoring systems used for predicting fatality of severe sepsis patients remain unsatisfactory. This study aimed to determine the prognostic value of circulating plasma DNA levels in severe septic patients presenting at the Emergency Department (ED).

METHODS

Sixty-seven consecutive patients with severe sepsis and 33 controls were evaluated. Plasma DNA levels were estimated by real-time quantitative polymerase chain reaction assay using primers for the human β-hemoglobin and ND2 gene. The patients' clinical and laboratory data on admission were analyzed.

RESULTS

The median plasma nuclear and mitochondria DNA levels for severe septic patients on admission were significantly higher than those of the controls. The mean plasma nuclear DNA level on admission correlated with lactate concentration (γ = 0.36, p = 0.003) and plasma mitochondrial DNA on admission (γ = 0.708, p < 0.001). Significant prognostic factors for fatality included mechanical ventilation within the first 24 hours (p = 0.013), mean sequential organ failure assessment (SOFA) score on admission (p = 0.04), serum lactate (p < 0.001), and both plasma nuclear and mitochondrial DNA on admission (p < 0.001). Plasma mitochondrial DNA was an independent predictor of fatality by stepwise logistic regression such that an increase by one ng/mL in level would increase fatality rate by 0.7%.

CONCLUSION

Plasma DNA has potential use for predicting outcome in septic patients arriving at the emergency room. Plasma mitochondrial DNA level on admission is a more powerful predictor than lactate concentration or SOFA scores on admission.

Ethidium bromide as a marker of mtDNA replication in living cells

Mitochondrial DNA (mtDNA) in tumor cells was found to play an important role in maintaining the malignant phenotype. Using laser scanning confocal fluorescence microscopy (LSCFM) in a recent work, we reported a variable fluorescence intensity of ethidium bromide (EB) in mitochondria nucleoids of living carcinoma cells. Since when EB is bound to nucleic acids its fluorescence is intensified; a higher EB fluorescence intensity could reflect a higher DNA accessibility to EB, suggesting a higher mtDNA replication activity. To prove this hypothesis, in the present work we studied, by LSCFM, the EB fluorescence in mitochondria nucleoids of living neuroblastoma cells, a model system in which differentiation affects the level of mtDNA replication. A drastic decrease of fluorescence was observed after differentiation. To correlate EB fluorescence intensity to the mtDNA replication state, we evaluated the mtDNA nascent strands content by ligation-mediated real-time PCR, and we found a halved amount of replicating mtDNA molecules in differentiating cells. A similar result was obtained by BrdU incorporation. These results indicate that the low EB fluorescence of nucleoids in differentiated cells is correlated to a low content of replicating mtDNA, suggesting that EB may be used as a marker of mtDNA replication in living cells.

Increased mitochondrial DNA copy number in occupations associated with low-dose benzene exposure

BACKGROUND

Benzene is an established leukemogen at high exposure levels. Although low-level benzene exposure is widespread and may induce oxidative damage, no mechanistic biomarkers are available to detect biological dysfunction at low doses.

OBJECTIVES

Our goals were to determine in a large multicenter cross-sectional study whether low-level benzene is associated with increased blood mitochondrial DNA copy number (mtDNAcn, a biological oxidative response to mitochondrial DNA damage and dysfunction) and to explore potential links between mtDNAcn and leukemia-related epigenetic markers.

METHODS

We measured blood relative mtDNAcn by real-time polymerase chain reaction in 341 individuals selected from various occupational groups with low-level benzene exposures (> 100 times lower than the Occupational Safety and Health Administration/European Union standards) and 178 referents from three Italian cities (Genoa, Milan, Cagliari).

RESULTS

In each city, benzene-exposed participants showed higher mtDNAcn than referents: mtDNAcn was 0.90 relative units in Genoa bus drivers and 0.75 in referents (p = 0.019); 0.90 in Milan gas station attendants, 1.10 in police officers, and 0.75 in referents (p-trend = 0.008); 1.63 in Cagliari petrochemical plant workers, 1.25 in referents close to the plant, and 0.90 in referents farther from the plant (p-trend = 0.046). Using covariate-adjusted regression models, we estimated that an interquartile range increase in personal airborne benzene was associated with percent increases in mtDNAcn equal to 10.5% in Genoa (p = 0.014), 8.2% (p = 0.008) in Milan, 7.5% in Cagliari (p = 0.22), and 10.3% in all cities combined (p < 0.001). Using methylation data available for the Milan participants, we found that mtDNAcn was associated with LINE-1 hypomethylation (-2.41%; p = 0.007) and p15 hypermethylation (+15.95%, p = 0.008).

CONCLUSIONS

Blood MtDNAcn was increased in persons exposed to low benzene levels, potentially reflecting mitochondrial DNA damage and dysfunction.

The effects of sepsis on mitochondria

BACKGROUND

Sepsis is associated with mitochondrial dysfunction and impaired oxygen consumption, which may condition clinical outcome independent of tissue oxygenation. However, mitochondrial role in sepsis severity remains unknown. We aimed to characterize mitochondrial function in sepsis, establish its origin and cellular consequences, and determine its correlation with clinical symptoms and outcome.

METHODS

Different markers of mitochondrial activity, nitrosative and oxidative stress, apoptosis, and inflammation were measured in peripheral blood mononuclear cells (PBMCs) and plasma of 19 septic patients and 20 controls. Plasma capacity to induce mitochondrial dysfunction was assessed in muscle mitochondria from 5 healthy individuals incubated with plasma of septic patients or controls.

RESULTS

Despite unaltered mitochondrial mass and protein synthesis, enzymatic mitochondrial complexes I, III, and IV and oxygen consumption were significantly inhibited in sepsis. Septic plasma tended to reduce oxygen consumption of healthy mitochondria and showed significantly increased amounts of extracellular mitochondrial DNA and inflammatory cytokines, especially in patients presenting adverse outcome. Active nuclear factor kappa-light-chain enhancer of activated B cells (NFKB) was also significantly increased, together with nitric oxide, oxidative stress and apoptosis. Additionally, sepsis severity significantly correlated with complex I inhibition, NFKB activation and intercellular adhesion molecule expression.

CONCLUSIONS

A plasmatic factor such as nitric oxide, increased in inflammation and able to induce mitochondrial dysfunction, oxidative stress and apoptosis, may be responsible for cell damage in sepsis. Together with bacterial infection, leakage of mitochondrial DNA from damaged cells into circulation could contribute to systemic inflammatory response syndrome. Mitochondrial dysfunction and inflammation correlate with sepsis severity and outcome, becoming targets for supporting therapies.

Mitochondrial DNA copy number in peripheral blood in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is associated with insulin resistance and various metabolic diseases; and recently, elevated oxidative stress has been detected in PCOS. Mitochondria are highly susceptible to oxidative damage; and disordered mitochondrial function at the cellular level can impact whole-body metabolic homeostasis, leading to the hypothesis that abnormalities in markers of mitochondrial metabolism are related to PCOS. We compared mitochondrial DNA (mtDNA) copy number in women with and without PCOS and investigated the independent relationship between mtDNA copy number and PCOS after adjustment for metabolic parameters. Fifty women with PCOS and 60 age- and body mass index-matched healthy women were studied. Mitochondrial DNA copy numbers as well as metabolic parameters and indices of insulin resistance were assessed. Mitochondrial DNA copy numbers were significantly lower in women with PCOS (P < .01). In the PCOS group, mtDNA copy number was negatively correlated with indices of insulin resistance, waist circumference, and triglyceride levels and positively correlated with sex hormone-binding globulin levels. In multiple logistic regression, the corresponding odds ratios (95% confidence interval) for PCOS by log-transformed mtDNA copy number and homeostasis model assessment of insulin resistance were 0.15 (0.04-0.56) and 4.26 (1.43-12.68), respectively, after adjustment for age, body mass index, and other metabolic factors. We report decreased mtDNA copy numbers in PCOS patients in relation to controls independently of insulin resistance or other metabolic factors. The pathophysiological and clinical significance of this finding requires further investigation.

South American camelid illegal traffic detection by means of molecular markers

South American camelids comprise the wild species guanaco and vicuña and their respective domestic relatives llama and alpaca. The aim of the present study was to determine by DNA analysis to which of these species belong a herd of camelids confiscated from a llama breeder but alleged to be alpacas by the prosecution, and to evaluate the usefulness of mitochondrial and autosomal DNA markers to solve judicial cases involving camelid taxa. Cytochrome b and cytochrome oxidase I mitochondrial genes and 7 STR were analyzed in 25 confiscated samples. Mitochondrial results were inconclusive because 18 of the sequestered samples presented haplotypes that corresponded to the guanaco haplogroup and the remaining seven belonged to a vicuña linage. Microsatellite data of casework samples and llama reference samples revealed different genetic profiles by the presence of private alleles at two microsatellites suggesting that the confiscated animals could be alpaca, or at least alpaca hybrids instead of pure llama.

Increased plasma levels of extracellular mitochondrial DNA during HIV infection: a new role for mitochondrial damage-associated molecular patterns during inflammation

HIV infection is characterized by a chronic inflammatory state. Recently, it has been shown that mitochondrial DNA (mtDNA) released from damaged or dead cells can bind Toll like receptor-9 (TLR9), an intracellular receptor that responds to bacterial or viral DNA molecules. The activation of TLR9 present within monocytes or neutrophils results in a potent inflammatory reaction, with the production of proinflammatory cytokines. We measured plasma levels of mtDNA in different groups of HIV(+) patients, i.e., those experiencing an acute HIV infection (AHI), long term non progressors (LTNP), late presenters (LP) taking antiretroviral therapy for the first time, and healthy controls. We found that in AHI and LP mtDNA plasma levels were significantly higher than in healthy individuals or in LTNP. Plasma mtDNA levels were not correlated to peripheral blood CD4(+) T cell count, nor to markers of immune activation, but had a significant correlation with plasma viral load, revealing a possible role for mtDNA in inflammation, or as a biomarker of virus-induced damage.

Alteration of mtDNA copy number, mitochondrial gene expression and extracellular DNA content in mice after irradiation at lethal dose

High steady-state transcriptional activity is essential for normal mitochondrial function. The requisite transcription rate is satisfied in part by high copy number of mitochondrial DNA (mtDNA). In the present study, we analyze mtDNA copy number by real-time PCR in nucleated blood cells from control mice and mice exposed to 1- or 10-Gy X-radiation. Transcription of the oxidative phosphorylation-associated genes cytb, atp6, nd4, nd2 and d-loop region was monitored in these nucleated blood cells similarly by real-time PCR. We observed a 50% decrease in the ratio of mitochondrial to nuclear DNA (mtDNA/nDNA) in blood cells, while the mtDNA/nDNA ratio in serum increased. After a lethal 10-Gy dose of X-irradiation, we observed an 80% decrease in the number of circulating lymphocytes. In response to a 10-Gy radiation dose, we observed transiently increased mtDNA/nDNA ratio and transcription within the initial 5 h post-treatment. At 24-72 h, the mtDNA/nDNA ratio in surviving cells was reduced to the level observed in blood cells irradiated with 1 Gy. We observed a decrease in the serum mtDNA/nDNA ratio due to an increase in nDNA content rather than a decrease in mtDNA. Taken together, results presented herein suggest that the mtDNA/nDNA ratio may be of clinical value potentially as a diagnostic tool, particularly in oncology patients undergoing radiation therapy.

HVRII of mtDNA in cord blood cells of newborn children and in their saliva 10 years later

Comparison of hypervariable region II nucleotide sequences of mitochondrial DNA obtained from cord blood cells and saliva cells of the same individual at birth and after ten years revealed a few differences at the so-called mutation hot spots (three transitions and three indels within the C-tract). The personal identity of samples was proved by short tandem repeat profiling. Comparison of individuals living in two regions that differ by air pollution, however, did not reveal statistically significantly increased number of mutations in the population from the region of poorer environmental conditions, although indicating such tendency.