Circulating mtDNA Levels Research Articles

Urinary Mitochondrial DNA Identifies Renal Dysfunction and Mitochondrial Damage in Sepsis-Induced Acute Kidney Injury.

Background Recent animal studies have shown that mitochondrial dysfunction initiates and accelerates renal injury in sepsis, but its role in sepsis remains unknown. Mitochondrial stress or dying cells can lead to fragmentation of the mitochondrial genome, which is considered a surrogate marker of mitochondrial dysfunction. Therefore, we evaluated the efficiency of urinary mitochondrial DNA (UmtDNA) as a marker of renal dysfunction during sepsis-induced acute kidney injury (AKI). Methods We isolated DNA from plasma and urine of patients. mtDNA levels were quantified by quantitative PCR. Sepsis patients were divided into no AKI, mild AKI, and severe AKI groups according to RIFLE criteria. Additionally, cecal ligation and puncture (CLP) was established in rats to evaluate the association between UmtDNA and mitochondrial function. Results A total of 52 (49.5%) developed AKI among enrolled sepsis patients. Increased systemic mtDNA did not correlate with systemic inflammation or acute renal dysfunction in sepsis patients, while AKI did not have an additional effect on circulating mtDNA levels. In contrast, UmtDNA was significantly enriched in severe AKI patients compared with that in the mild AKI or no AKI group, positively correlated with plasma creatinine, urinary neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1, and inversely with the estimated glomerular filtration rate. Additionally, UmtDNA increased in rats following CLP-induced sepsis. UmtDNA was predictive of AKI development and correlated with plasma creatinine and blood urea nitrogen in the rat sepsis model. Finally, the UmtDNA level was inversely correlated with the cortical mtDNA copy number and relative expression of mitochondrial gene in the kidney. Conclusion An elevated UmtDNA level correlates with mitochondrial dysfunction and renal injury in sepsis patients, indicating renal mitochondrial injury induced by sepsis. Therefore, UmtDNA may be regarded as a valuable biomarker for the occurrence of AKI and the development of mitochondria-targeted therapies following sepsis-induced AKI.

P 164 - Circulating mtDNA levels as an early marker for metabolic syndrome

Chronic diseases, infection and physical activity are conditions related with metabolic or oxidative stress and the releasing of mitochondria to circulation by cells. This might be due to apoptosis or transference of mitochondria from one cell to another, either as survival or as tissue repair process. Circulating levels of cell-free mitochondrial DNA (ccf-mtDNA), although controversial, have been used for cancer and sepsis diagnose. The objective of this study was to investigate the relationship between ccf-mtDNA and metabolic syndrome. In this sense, after IRB approval, healthy subjects (n=32) and adults with diabetes (n=6) were invited to participate. Body mass index (BMI) was calculated and fasting glucose measured as biomarker of metabolic syndrome. In addition, DNA was extracted from serum and real time PCR used to detect ccf-mtDNA and both parameters were compared. Our data showed that ccf-mtDNA values ranged from 10 to 100 ng/ml in subjects with normal BMI while there were no detectable levels of ccf-mtDNA in samples from overweight subjects and diabetic patients. Glucose levels did not show differences independently of their BMI, but there was an inverse relationship between ccf-mtDNA and BMI. In conclusion, our results suggest that ccf-mtDNA might represent an early biomarker to identify people with metabolic syndrome or at risk for future develpment of diabetes.

Induced hypothermia is associated with reduced circulating subunits of mitochondrial DNA in cardiac arrest patients

Induced hypothermia may protect from ischemia reperfusion injury. The mechanism of protection is not fully understood and may include an effect on mitochondria. Here we describe the effect of hypothermia on circulating mitochondrial (mt) DNA in a substudy of a multicenter randomized trial (the Target Temperature Management trial). Circulating levels of mtDNA were elevated in patients with cardiac arrest at all-time points compared to healthy controls. After 24 h of temperature management, patients kept at 33 °C had significantly lower levels of COX3, NADH1 and NADH2 compared to baseline, in contrast to those kept at 36 °C. After regain of temperature, cytochrome – B was significantly reduced in patients kept at 33 °C with cardiac arrest. Cardiac arrest results in circulating mtDNA levels, which reduced during a temperature management protocol in patients with a target temperature of 33 °C.

Circulating Monocytes Exhibit an Endotoxin Tolerance Status after Acute Ischemic Stroke: Mitochondrial DNA as a Putative Explanation for Poststroke Infections.

Patients with acute ischemic stroke (AIS) suffer from infections associated with mortality. The relevance of the innate immune system, and monocytes in particular, has emerged as an important factor in the evolution of these infections. The study enrolled 14 patients with AIS, without previous treatment, and 10 healthy controls. In the present study, we show that monocytes from patients with AIS exhibit a refractory state or endotoxin tolerance. The patients were unable to orchestrate an inflammatory response against LPS and expressed three factors reported to control the evolution of human monocytes into a refractory state: IL-1R-associated kinase-M, NFkB2/p100, and hypoxia-inducible factor-1α. The levels of circulating mitochondrial DNA (mtDNA) in patients with AIS correlated with impaired inflammatory response of isolated monocytes. Interestingly, the patients could be classified into two groups: those who were infected and those who were not, according to circulating mtDNA levels. This finding was validated in an independent cohort of 23 patients with AIS. Additionally, monocytes from healthy controls, cultured in the presence of both sera from patients and mtDNA, reproduced a refractory state after endotoxin challenge. This effect was negated by either a TLR9 antagonist or DNase treatment. The present data further extend our understanding of endotoxin tolerance implications in AIS. A putative role of mtDNA as a new biomarker of stroke-associated infections, and thus a clinical target for preventing poststroke infection, has also been identified.

Decreased Circulating mtDNA Levels in Professional Male Volleyball Players.

Exercise exerts various effects on the immune system, and evidence is emerging on its anti-inflammatory effects; the mechanisms on the basis of these modifications are poorly understood. Mitochondrial DNA (mtDNA) released from damaged cells acts as a molecule containing the so-called damage-associated molecular patterns and can trigger sterile inflammation. Indeed, high plasma levels of mtDNA are associated to several inflammatory conditions and physiological aging and longevity. The authors evaluated plasma mtDNA in professional male volleyball players during seasonal training and the possible correlation between mtDNA levels and clinical parameters, body composition, and physical performance. Plasma mtDNA was quantified by real-time PCR every 2 mo in 12 professional volleyball players (PVPs) during 2 consecutive seasons. As comparison, 20 healthy nonathlete male volunteers (NAs) were analyzed. The authors found lower levels of mtDNA in plasma of PVPs than in NAs. However, PVPs showed a decrease of circulating mtDNA only in the first season, while no appreciable variations were observed during the second season. No correlation was observed among mtDNA, hematochemical, and anthropometric parameters. Regular physical activity appeared associated with lower levels of circulating mtDNA, further confirming the protective, anti-inflammatory effect of exercise.

0474. Circulating mitochondrial dna and vitamin d in critical illness

Of the cohort patients studied, 37% were women and 84% were white. The mean age at critical care initiation was 53.5 years (SD 14.2). The mean APACHE II score was 24.5 (SD 8.3), while 100% of the cohort had SIRS, 71% had a source of infection identified and 18% had ARDS. The mean plasma 25(OH)D was 20.6 (SD 11.4) and 28.6% of the study cohort had plasma 25(OH)D ≤ 15 ng/mL. Gross unadjusted 30-day mortality was 26.5%. The mean (SD) plasma 25(OH)D was significantly higher in patients with mtDNA < 4000 copies/ml [25(OH)D 22.0 (11.2) ng/ml] relative to those with mtDNA ≥ 4000 copies/ml [25(OH)D 14.9 (10.9) ng/mL]; P < 0.001. When the cohort was analyzed with the exposure as plasma 25(OH)D and the outcome as plasma mtDNA ≥ 4000 copies/ml, we find that patients with plasma 25(OH)D < 15 ng/mL have a significantly higher odds of having plasma mtDNA ≥ 4000 copies/ml (unadjusted OR= 7.50, 95% CI 1.53-36.79; P=0.013). 25(OH)D in the cohort remains a significant predictor of plasma mtDNA ≥ 4000 copies/ml following adjustment for age, gender, race and APACHE II (adjusted OR= 13.19, 95% CI 1.69-103.34; P=0.014). Cox proportional hazard multivariable regression modeling, adjusting for ap rioridefined covariates comprising APACHE II score, age, sex, race, and plasma 25(OH)D, showed that mtDNA was predictive of all cause mortality following critical care (HR, 4.02; 95% CI, 1.14-14.20 ng/ml). Conclusions 25(OH)D levels are associated with circulating mtDNA levels. This study cannot determine a relationship between 25(OH)D and mtDNA beyond association but raises the question as to whether vitamin D-mediated pathways might play a role in linking autophagic and inflammasome processes.

DAMPs, PAMPs, and the Origins of SIRS in Bacterial Sepsis

DAMPs, PAMPs, and the Origins of SIRS in Bacterial Sepsis

Increased circulating mitochondrial DNA after myocardial infarction

Aseptic trauma patients with massive muscular damage have increased plasma levels of mitochondrial DNA (mtDNA), acting as a danger associated molecular pattern molecule (DAMP) promoting inflammation and tissue damage [1]. We hypothesized that an acute myocardial infarction (MI) would lead to increased circulating levels of mtDNA, potentially contributing to local and systemic inflammation following MI.

Mitochondrial DNA in serum of patients with prostate cancer: a predictor of biochemical recurrence after prostatectomy

To investigate the role of circulating mitochondrial DNA (mtDNA) in patients with localized prostate cancer, as recent reports show that patients with advanced cancer have increased levels of mtDNA. DNA was isolated from the serum of 100 patients with prostate cancer and 18 with benign prostate hyperplasia (BPH). A quantitative real-time polymerase chain reaction was used to amplify 79 bp and 230 bp fragments of the mitochondrial 16s-RNA gene, the short fragment representing total mtDNA, including mtDNA truncated by apoptosis, and the long fragment representing mostly mtDNA from other cell death entities. mtDNA integrity was defined as the ratio of long to short mtDNA fragments. The short and long mtDNA levels, and mtDNA integrity, were similar in patients with BPH and cancer (P = 0.940, 0.211 and 0.441, respectively), and were not correlated with clinical or pathological variables, e.g. age, prostate-specific antigen (PSA) level, cT stage, pT stage, seminal vesicle infiltration, lymph node invasion, or Gleason score (P = 0.075 to 0.961). However, patients with high levels of short mtDNA (>75th percentile) had a greater risk of PSA progression and this variable was the strongest predictor of PSA recurrence in a multivariate Cox analysis (P = 0.023; hazard ratio 0.31; 95% confidence interval 0.113-0.851). Circulating mtDNA levels did not distinguish between patients with prostate cancer or BPH. However, there was a significant increase in short mtDNA fragments in patients with early PSA recurrence after radical prostatectomy.