The Nexus of cfDNA and Nuclease Biology.

Cell-free DNA (cfDNA) is a widely used noninvasive biomarker for diagnosis and prognosis of multiple disease states. Emerging evidence suggests that cfDNA might not just be passive waste products of cell death but could have a physiological and pathological function in inflammation and autoimmunity. The balance of cfDNA generation and clearance may thus be vital in health and disease. In particular, plasma nuclease activity has been linked to multiple pathologies including cancer and systemic lupus erythematosus (SLE) and associated with profound changes in the nonrandom fragmentation of cfDNA. Lastly, in this review, we explore the effects of DNA fragmentation factor B (DFFB), DNASE1L3, and DNASE1 on cfDNA levels and their fragmentomic profiles, and what these recent insights reveal about the biology of cfDNA.

Deoxyribonuclease activity negative correlates with extracellular DNA in uncomplicated singleton pregnancies in the third trimester.

OBJECTIVES: It is not clear, which factors affect extracellular DNA (ecDNA) concentrations in healthy women with singleton uncomplicated pregnancies, although deoxyribonucleases (DNases) are hypothesized to be responsible for the cleavage of plasma ecDNA. The aim of this study was to analyze potential determinants of total ecDNA including plasma DNase activity. METHODS: Plasma samples were collected from 48 healthy women with singleton uncomplicated pregnancies in the third trimester (gestation week 37). DNA was isolated and quantified using fluorometry and real time PCR. DNase activity was assessed using the single radial enzyme-diffusion method. RESULTS: Neither ecDNA, nor DNase activity were affected by maternal age or BMI. DNase activity negatively correlated with total plasma ecDNA (r=-0.40, p=0.007). Similar associations were found for ecDNA of nuclear and mitochondrial origin, but not with fetal DNA quantified using Y-targeted PCR in male fetus-bearing pregnancies. CONCLUSIONS: The role of plasma ecDNA of fetal and maternal origin is studied in the pathogenesis of pregnancy-complications. The results indicate that plasma DNase activity could negatively regulate ecDNA concentrations and should, thus, be analyzed in preeclampsia, preterm birth and other ecDNA-related pregnancy complications.

Dysregulation of the actin scavenging system and inhibition of DNase activity following severe thermal injury.

BACKGROUND: Circulating cell-free DNA (cfDNA) is not found in healthy subjects, but is readily detected after thermal injury and may contribute to the risk of multiple organ failure. The hypothesis was that a postburn reduction in DNase protein/enzyme activity could contribute to the increase in cfDNA following thermal injury. METHODS: Patients with severe burns covering at least 15 per cent of total body surface area were recruited to a prospective cohort study within 24 h of injury. Blood samples were collected from the day of injury for 12 months. RESULTS: Analysis of blood samples from 64 patients revealed a significant reduction in DNase activity on days 1-28 after injury, compared with healthy controls. DNase protein levels were not affected, suggesting the presence of an enzyme inhibitor. Further analysis revealed that actin (an inhibitor of DNase) was present in serum samples from patients but not those from controls, and concentrations of the actin scavenging proteins gelsolin and vitamin D-binding protein were significantly reduced after burn injury. In a pilot study of ten military patients with polytrauma, administration of blood products resulted in an increase in DNase activity and gelsolin levels. CONCLUSION: The results of this study suggest a novel biological mechanism for the accumulation of cfDNA following thermal injury by which high levels of actin released by damaged tissue cause a reduction in DNase activity. Restoration of the actin scavenging system could therefore restore DNase activity, and reduce the risk of cfDNA-induced host tissue damage and thrombosis.

ANTECEDENTES: El ADN libre de las células circulantes (circulating cell-free DNA, cfDNA) no se encuentra en sujetos sanos, pero se detecta fácilmente después de una lesión térmica y puede contribuir al riesgo de fallo multiorgánico. La hipótesis fue que una disminución en la actividad de la proteína/enzima ADNasa tras la lesión térmica podría contribuir a la elevación del cfDNA que ocurre tras la misma. MÉTODOS: Los pacientes con quemaduras graves con una extensión ≥ 15% del área de superficie corporal total (total body surface area, TBSA) se incluyeron en un estudio prospectivo de cohortes durante las primeras 24 horas posteriores a la lesión. Se recogieron muestras de sangre desde el día de la lesión hasta los 12 meses posteriores a la misma. RESULTADOS: El análisis de muestras de sangre de 64 pacientes reveló una reducción significativa de la actividad de la ADNasa en los días 1 a 28 después de la lesión, en comparación con los controles sanos. Los niveles de proteína ADNasa no se vieron afectados, lo que sugiere la presencia de un inhibidor enzimático. Un análisis adicional reveló que la actina (un inhibidor de la ADNasa) estaba presente en las muestras de suero de los pacientes, pero no en los controles, y las concentraciones de la gelsolina, proteína que causa la disociación de la actina, y la proteína de unión a la vitamina D se redujeron significativamente después de la lesión térmica. En un estudio piloto de 10 pacientes con politrauma por lesiones militares, la administración de hemoderivados produjo un aumento en la actividad de la ADNasa y de los niveles de gelsolina. CONCLUSIÓN: Este estudio sugiere un nuevo mecanismo biológico para la acumulación de cfDNA después de una lesión térmica, por el cual los altos niveles de actina liberada por el tejido dañado causarían una reducción en la actividad de la ADNasa. La restauración del sistema eliminador de actina podría, por lo tanto, restaurar la actividad de la ADNasa y reducir el riesgo de daño tisular y trombosis en el huésped inducido por el cfDNA.

Neutrophil extracellular trap formation and nuclease activity in septic patients.

BACKGROUND: There is little knowledge, whether in patients with sepsis neutrophil extracellular trap (NET) formation and NET degrading nuclease activity are altered. Thus, we tested the hypotheses that 1) NET formation from neutrophils of septic patients is increased compared to healthy volunteers, both without stimulation and following incubation with mitochondrial DNA (mtDNA), a damage-associated molecular pattern, or phorbol 12-myristate 13-acetate (PMA; positive control) and 2) that serum nuclease activities are increased as well. METHODS: Following ethic committee approval, we included 18 septic patients and 27 volunteers in this prospective observational trial. Blood was withdrawn and NET formation from neutrophils was analyzed in vitro without stimulation and following incubation with mtDNA (10 µg/well) or PMA (25 nmol). Furthermore, serum nuclease activity was assessed using gel electrophoresis. RESULTS: In contrast to our hypothesis, in septic patients, unstimulated NET release from neutrophils was decreased by 46.3% (4.3% ± 1.8 SD vs. 8.2% ± 2.9, p ≤ 0.0001) and 48.1% (4.9% ± 2.5 vs. 9.4% ± 5.2, p = 0.002) after 2 and 4 h compared to volunteers. mtDNA further decreased NET formation in neutrophils from septic patients (4.7% ± 1.2 to 2.8% ± 0,8; p = 0.03), but did not alter NET formation in neutrophils from volunteers. Of note, using PMA, as positive control, we ensured that neutrophils were still able to form NETs, with NET formation increasing to 73.2% (±29.6) in septic patients and 91.7% (±7.1) in volunteers (p = 0.22). Additionally, we show that serum nuclease activity (range: 0-6) was decreased in septic patients by 39.6% (3 ± 2 vs 5 ± 0, median and ICR, p = 0.0001) compared to volunteers. CONCLUSIONS: Unstimulated NET formation and nuclease activity are decreased in septic patients. mtDNA can further reduce NET formation in sepsis. Thus, neutrophils from septic patients show decreased NET formation in vitro despite diminished nuclease activity in vivo. TRIAL REGISTRATION: DRKS00007694, german clinical trials database (DRKS). Retrospectively registered 06.02.2015.

Cell-free DNA in blood circulation is generated by DNase1L3 and caspase-activated DNase.

Cell-free DNA (cfDNA) (e.g. fetal- or tumor-derived DNA) is DNA found in the blood circulation. It is now widely investigated as a biomarker for prenatal screening, tumor diagnosis, and tumor monitoring as "liquid biopsies". However, the biological and biochemical aspects of cfDNA remain unclear. Although cfDNA is considered to be mainly derived from dead cells, information is scarce as to whether it is apoptotic or necrotic and what kinds of endonucleases or DNases are involved. We induced in vivo hepatocyte necrosis and apoptosis in mice deficient in DNase1L3 (also named DNase γ) and/or caspase-activated DNase (CAD) genes with acetaminophen overdose and anti-Fas antibody treatments. We found that (i) DNase1L3 was the endonuclease responsible for generating cfDNA in acetaminophen-induced hepatocyte necrosis and (ii) CAD and DNase1L3 cooperated in producing cfDNA for anti-Fas mediated hepatocyte apoptosis.

DNase γ, DNase I and caspase-activated DNase cooperate to degrade dead cells.

Serum endonucleases are essential for degrading the chromatin released from dead cells and preventing autoimmune diseases such as systemic lupus erythematosus. Serum DNase I is known as the major endonuclease, but recently, another endonuclease, DNase γ/DNase I-like 3, gained attention. However, the precise role of each endonuclease, especially that of DNase γ, remains unclear. In this study, we distinguished the activities of DNase γ from those of DNase I in mouse serum and concluded that both cooperated in degrading DNA during necrosis: DNase γ functions as the primary chromatolytic activity, causing internucleosomal DNA fragmentation, and DNase I as the secondary one, causing random DNA digestion for its complete degradation. These results were confirmed by two in vivo experimental mouse models, in which necrosis was induced, acetaminophen-induced hepatic injury and streptozotocin-induced ß-cell necrosis models. We also determined that DNase γ functions as a backup endonuclease for caspase-activated DNase (CAD) in the secondary necrosis phase after γ-ray-induced apoptosis in vivo.

[Exceptional Diversity of Catalytic Antibodies with Varying Activity in the Blood of Autoimmune and Viral Disease Patients].

Antibodies (ABs) that target autoantigens were more abundant in the blood of humans and animals suffering from certain autoimmune and viral diseases than in the blood of healthy donors. The emergence of ABs with diverse types of catalytic activity is among the earliest manifestations of certain autoimmune diseases. The putative mechanisms that underlie the accumulation of autoantibodies and abzymes in different autoimmune diseases are addressed in the present review. The extraordinary diversity of abzymes with various types of catalytic activity is discussed.

Assessment of Deoxyribonuclease Activity in Serum Samples of Patients With Systemic Lupus Erythematosus: Fluorescence-Based Method Versus ELISA.

BACKGROUND: We report the improvement of previously described method for determining deoxyribonuclease (DNase) activity in serum samples that uses a fluorescently labeled DNA fragment as a substrate METHODS: Activity of serum DNase was analyzed in 31 patients with systemic lupus erythematosus (SLE) and 13 healthy individuals by fluoresence-based method and ELISA test RESULTS: We found a mean decrease in DNase activity between cases and controls of 12.46% measured by the fluoresence-based method and of 12.21% measured by ELISA method. High level of positive correlation between two methods for DNase activity was observed: P < 0.001 and Pearson correlation coefficient 0.740. Decreased DNase activity was found in 25 of 31 SLE patients (81%) by fluoresence-based method and in 24 of 31 SLE patients (77%) by ELISA test. We also observed the significant positive correlation between titer of anti-dsDNA antibodies and DNase activity measured by both methods (P < 0.05). CONCLUSIONS: The key improvement is the use of internal control in the fluorescence-based method, which diminishes the influence of technical errors on the obtained results and increases reliability of the assay. This improved fluorescence-based method, with additional validation, may provide an alternative to more expensive and time-consuming conventional methods, such as ELISA.

Importance of low serum DNase I activity and polyspecific anti-neutrophil cytoplasmic antibodies in propylthiouracil-induced lupus-like syndrome.

OBJECTIVE: To study the role of deoxyribonuclease (DNase) I activity and ANCA in propylthiouracil (PTU)-induced lupus-like syndrome (LLS). METHODS: We compared 36 SLE patients with 17 PTU-induced LLS patients diagnosed from 2008 to 2014. We studied ANCA profile (MPO, PR3, lactoferrin, CTG, elastase, bactericidal/permeability-increasing protein), anti-dsDNA, anti-ENA, anti-nucleosome, anti-histone, anti-C1q, anti-aCL, complement components, cryoglobulins and serum DNase I activity. Healthy persons and patients without LLS treated with PTU comprised the control groups. Twelve LLS patients were serologically and clinically followed for 4.1 (S.D. 2.0) years. RESULTS: PTU-induced LLS patients less frequently had arthritis, renal and neurological manifestations, but more frequently had fever, purpura, urticarial-like vasculitis and ulceration (P < 0.01). PTU-induced LLS patients more frequently had polyspecific ANCA (anti-MPO, anti-elastase and anti-PR3 were most commonly detected) (P < 0.01). SLE patients more frequently had anti-dsDNA, anti-ENA, anti-nucleosome, anti-C1q (P < 0.01) and anti-histone antibodies (P < 0.05). PTU-induced LLS patients had lower DNase I activity than SLE patients and controls (P < 0.01). Discontinuation of PTU increased DNase I activity, although it did not reach the levels of controls (P < 0.01). After remission, MPO-ANCA decreased (P < 0.01), but persisted for a long time. CONCLUSION: PTU, as a trigger, and low DNase I activity, as a predisposing factor, may lead to LLS. Polyspecific ANCAs are useful markers for differentiating SLE from PTU-induced LLS. Low DNase I activity might be an important prognostic biomarker for PTU-induced LLS. Monitoring of ANCA and DNase I activity may prevent long-lasting exposure to causal drugs, unnecessary immunosuppressive therapy and severe complications of LLS.

Circulating nucleosomes and immunogenic cell death markers HMGB1, sRAGE and DNAse in patients with advanced pancreatic cancer undergoing chemotherapy.

Serum biomarkers are urgently needed for patient stratification and efficient treatment monitoring in pancreatic cancer (PC). Within a prospective diagnostic observation study, blood samples were obtained from 78 patients with advanced PC before and weekly during the course of palliative chemotherapy. Circulating nucleosomes and immunogenic cell death markers, high-mobility group box 1 (HMGB1), soluble receptors of advanced glycation end products (sRAGE) and DNAse activity, were measured by enzyme-linked immunosorbent assay and correlated with results of radiological staging after 2 months of treatment, with time to progression (TTP) and overall survival (OS). Median TTP and OS of PC patients were 3.9 and 7.7 months, respectively. Pretherapeutic baseline biomarker levels did not correlate with objective response; however, nucleosome levels on day (d) 28 were higher (p = 0.048) and sRAGE levels at time of staging (d56) were lower in progressive patients (p = 0.046). Concerning estimation of prognosis, high nucleosome levels (d7, d14, d21 and d56), low sRAGE levels (d56) and DNAse activity courses (d0-d7) correlated with TTP, whereas high nucleosomes (d7, d14 and d56), high HMGB1 (d21 and d56) and DNAse (d0-d7) were associated with OS. After adjustment to Karnofsky performance score, nucleosomes and HMGB1 (both d56) and DNAse (d0-d7) remained independent prognostic factors. Thus, courses of circulating nucleosomes and immunogenic cell death markers HMGB1 and sRAGE show prognostic relevance in PC patients undergoing chemotherapy.

Immunogenic cell death biomarkers HMGB1, RAGE, and DNAse indicate response to radioembolization therapy and prognosis in colorectal cancer patients.

Radioembolization therapy (RE) is an efficient locoregional treatment for liver metastases from colorectal cancer. Serum biomarkers involved in immunogenic cell death are potentially valuable for early predicting therapy response and estimating prognosis. In a prospective observation study, blood samples were taken from 49 consecutive colorectal cancer patients with extensive hepatic metastases before, 24 and 48 hr after RE. Serum levels of high mobility group box 1 (HMGB1), receptor of glycation end products (RAGE) and activity of desoxyribonuclease were compared with response to therapy regularly determined radiologically 3 months after therapy and with overall survival. Serum levels of HMGB1 were increased already 24 hr after RE, while RAGE levels were decreased and DNAse remained unchanged. In radiological staging, 35 patients demonstrated disease progression while 14 patients had stable disease or remission. Serum HMGB1 levels 24 hr after RE were significantly higher in progressive than in nonprogressive patients while for RAGE and DNAse no difference was observed between the response groups. Concerning overall survival, high pretherapeutic (0 hr) and 24 hr levels of HMGB1 were associated with poor outcome. Multivariate analysis including HMGB1, tumor, liver and inflammation markers revealed HMGB1 and CRP as independent prognostic parameters. HMGB1 is a valuable serum biomarker for early estimation of therapy response and prognosis in colorectal cancer patients with liver metastases undergoing RE therapy.

Predictive value of immunogenic cell death biomarkers HMGB1, sRAGE, and DNase in liver cancer patients receiving transarterial chemoembolization therapy.

Transarterial chemoembolization (TACE) therapy is an effective locoregional anticancer treatment for liver cancer patients. Serum biomarkers involved in immunogenic cell death may be valuable for early predicting therapy response and estimating prognosis. Sera of 50 prospectively and consecutively included hepatocellular carcinoma (HCC) patients, undergoing TACE therapy, were taken before and 24 h after TACE application. In these samples, soluble biomarkers involved in immunogenic cell death, and among them, high-mobility group box 1 (HMGB1), soluble receptor of advanced glycation end products (sRAGE), and DNase activity were measured. They were compared with radiological response to therapy. A total of 71 TACE therapies were evaluated, of which 32 were classified as "no progression," and 39, as "progression." While HMGB1 levels increased already 24 h after TACE, there was an early decrease of sRAGE and DNase activity. Pretherapeutic and 24-h values of sRAGE were significantly higher in the no progression group than those in the progression group. There was no difference with respect to treatment response for DNase and HMGB1. Soluble RAGE is a new parameter with predictive relevance in primary liver cancer patients undergoing TACE therapy.

[The criteria of differentiated diagnostics of early arthritis on the basis of analysis of serum hyaluronidase and deoxyribonuclease activity].

The study analyzed serum hyaluronidase and deoxyribonuclease activity in patients with early arthritis--early rheumatoid arthritis and acute reactive arthritis. The criteria of their differential diagnostics were developed on the basis of data obtained. The genuine methods were applied to analyze hyaluronidase and deoxyribonuclease activity of blood serum based on formation of clot of etacridine acetate (rivanol) with hyaluronic acid and DNA inversely proportionally to their polymerization under the impact of enzymes. The increased serum hyaluronidase and deoxyribonuclease activity was established in patients with early arthritis as compared with control group (p < 0.001). The prevalence of mentioned types of activity under early rheumatoid arthritis as compared with acute reactive arthritis was detected too. The rests for differentiate diagnostics of early rheumatoid arthritis and acute reactive arthritis were developed conformed to criteria of the most useful diagnostic tests in rheumatology.

Cell-Free Double-Stranded DNA to DNase Ratio Predicts Outcome after Primary Survived Cardiac Arrest.

(1) Double-stranded DNA (dsDNA) and deoxyribonuclease (DNase) as surrogate parameters for accumulating inflammatory hazards are insufficiently studied in resuscitation research. (2) Blood samples of 76 individuals after CA were analyzed 24 and 96 h after ICU admission. Plasma levels of dsDNA, interleukin-8, and monocyte chemoattractant protein-1 and activity of DNase were assessed along with baseline characteristics, intensive care measures, and outcome data. DsDNA/DNase ratio was used as main prognostication parameter. After calculating an optimal empirical cut-off for outcome prediction (death or Cerebral Performance Category ≥3 at 6 months), multivariable logistic regression was applied. (3) Using receiver operating characteristic (ROC) analysis, an area under the curve (AUC) of 0.65 (95% CI 0.50-0.79) was found for dsDNA/DNase after 24 h versus 0.83 (95% CI 0.73-0.92) after 96 h (p = 0.03). The empirical cut-off for dsDNA/DNase ratio after 96 h was 149.97 (Youden). DsDNA/DNase ratio was associated with unfavorable outcome at six months (aOR 1.006, 95% CI 1.0017-1.0094, p = 0.005). In multivariable analysis, the association of dsDNA/DNase ratio independently predicted outcome as a continuous variable (aOR 1.004, 95% CI 1.0004-1.0079, p = 0.029) after adjusting for potential confounders. (4) DsDNA/DNase ratio at 96 h demonstrates good predictive performance for estimating outcome after CA.

cfDNA and DNases: New Biomarkers of Sepsis in Preterm Neonates-A Pilot Study.

INTRODUCTION: An early and accurate diagnosis of early onset neonatal sepsis (EONS) and late onset neonatal sepsis (LONS) is essential to improve the outcome of this devastating conditions. Especially, preterm infants are at risk. Reliable biomarkers are rare, clinical decision-making depends on clinical appearance and multiple laboratory findings. Markers of NET formation and NET turnover might improve diagnostic precision. Aim of this study was to evaluate the diagnostic value of NETs in sepsis diagnosis in neonatal preterm infants. METHODS: Plasma samples of neonatal preterm infants with suspected sepsis were collected. Blood samples were assayed for markers of NET formation and NET turnover: cfDNA, DNase1, nucleosome, NE, and H3Cit. All clinical findings, values of laboratory markers, and epidemiological characteristics were collected retrospectively. Two subpopulations were created to divide EONS from LONS. EMA sepsis criteria for neonatal sepsis were used to generate a sepsis group (EMA positive) and a control group (EMA negative). RESULTS: A total of 31 preterm neonates with suspected sepsis were included. Out of these, nine patients met the criteria for sepsis according to EMA. Regarding early onset neonatal sepsis (3 EONS vs. 10 controls), cfDNA, DNase I, nucleosome, and CRP were elevated significantly. H3Cit and NE did not show any significant elevations. In the late onset sepsis collective (6 LONS vs. 12 controls), cfDNA, DNase I, and CRP differed significantly compared to control group.

Plasma DNA and deoxyribonuclease are associated with glucose metabolism in healthy mice.

It is currently unknown why obesity leads in some patients to prediabetes and metabolic syndrome. Microinflammation potentially caused by extracellular DNA is supposed to be involved. The aim of this cross-sectional study in healthy mice was to analyze the association between plasma extracellular DNA and glucose metabolism. Fasting glycemia and insulin were measured in healthy adult female mice that subsequently underwent an oral glucose tolerance test. Indices of glucose metabolism and insulin sensitivity were calculated. DNA was isolated from plasma and quantified fluorometrically. Deoxyribonuclease (DNase) activity of plasma was measured using the single radial enzyme diffusion method. Fasting glycemia correlated negatively with both, extracellular DNA and DNase (r = -0.44 and r = -0.32, respectively). DNase was associated positively with the incremental area under curve (r = 0.35), while extracellular DNA correlated negatively with total area under curve of glycemia during oral glucose tolerance test (r = -0.34). Measures of insulin sensitivity were found to be associated with neither extracellular DNA, nor DNase. The hypothesis of an association of low DNase with increased fasting glucose was partially proved. Surprisingly, low extracellular DNA is associated with higher fasting glucose and lower glucose tolerance in mice. As novel therapeutic targets for prediabetes and metabolic syndrome are highly needed, this study provides novel unexpected associations within the limitations of the focus on physiological variability as it was conducted on healthy mice. The causality of these associations should be proved in further interventional experiments.

Familial tendency and risk of nasopharyngeal carcinoma in taiwan: effects of covariates on risk.

In the present study, the authors compared the long-term risk of nasopharyngeal carcinoma (NPC) of male participants in an NPC multiplex family cohort with that of controls in a community cohort in Taiwan after adjustment for anti-Epstein-Barr virus (EBV) seromarkers and cigarette smoking. A total of 43 incident NPC cases were identified from the 1,019 males in the NPC multiplex family cohort and the 9,622 males in the community cohort, for a total of 8,061 person-years and 185,587 person-years, respectively. The adjusted hazard ratio was 6.8 (95% confidence interval (CI): 2.3, 20.1) for the multiplex family cohort compared with the community cohort. In the evaluation of anti-EBV viral capsid antigen immunoglobulin A and anti-EBV deoxyribonuclease, the adjusted hazard ratios were 2.8 (95% CI: 1.3, 6.0) and 15.1 (95% CI: 4.2, 54.1) for those positive for 1 EBV seromarker and positive for both seromarkers, respectively, compared with those negative for both EBV seromarkers. The adjusted hazard ratio was 31.0 (95% CI: 9.7, 98.7) for participants who reported a family history of NPC and who were anti-EBV-seropositive compared with individuals without such a history who were anti-EBV-seronegative. The findings suggest that both family history of NPC and anti-EBV seropositivity are important determinants of subsequent NPC risk and that the effect of family history on NPC risk cannot be fully explained by mediation through EBV serologic responses.

Electrochemical sensor for blood deoxyribonucleases: design and application to the diagnosis of autoimmune thyroiditis.

We designed an electrochemical sensor based on a carbon nanotube modified electrode (ME) to analyze DNA-cleaving activity. The cleavage of high molecular weight DNA resulted in an increase in the oxidation current from DNA guanine nucleotides due to a change in DNA adsorptive behavior on the surface of the ME. DNA digestion with DNAse I was accompanied by a linear increase in the DNA signal in proportion to the enzyme activity. We then proposed an assay based on the sensor for the direct assessment of the total deoxyribonuclease activity of blood serum as well as the separate detection of DNAse I and DNA abzymes. The assay was applied to analyze deoxyribonucleases in sera from 21 healthy donors and 17 patients with autoimmune thyroiditis. Our results show that the response of the sensor to DNA cleavage by blood deoxyribonucleases is a promising diagnostic criterion for autoimmune thyroiditis. This sensor can be implemented in a disposable screen-printed electrode format for application in clinical laboratories.

[Enhanced serum DNAase activity in hypersensitization to pollen allergens].

Factor analysis of cross-sensitization to 24 common allergens and correlation analysis of the relationship between the hypersensitivity to the allergens and some biochemical markers (the intensity of serum chemiluminescence, the content of SH-groups, and the activity of lysosomal enzymes) of the health status were carried out in a sample of Moscow residents with allergic diseases. A significant correlation was found between the serum levels of specific IgE antibodies to pollen allergens and the activity of serum acid DNAase (R = 0.498; p = 0.009; N = 67). The revealed regularity may be used to devise a test for the differential diagnosis of pollenoses and suggests that there are possible differences in the levels of apoptosis and cytogenetic damages between patients with pollenoses and those with other allergic diseases.

Sex Difference in Plasma Deoxyribonuclease Activity in Rats.

Extracellular DNA (ecDNA) activates immune cells and is involved in the pathogenesis of diseases associated with inflammation such as sepsis, rheumatoid arthritis or metabolic syndrome. DNA can be cleaved by deoxyribonucleases (DNases), some of which are secreted out of cells. The aim of this experiment was to describe plasma DNase activity in relation to extracellular DNA in adult rats, to analyse potential sex differences and to prove whether they are related to endogenous testosterone. Adult Lewis rats (n=28) of both sexes were included in the experiment. Male rats were gonadectomized or sham-operated and compared to intact female rats. Plasma ecDNA and DNase activity were measured using fluorometry and single radial enzyme diffusion assay, respectively. Concentrations of nuclear ecDNA and mitochondrial ecDNA were determined using real-time PCR. Females had 60% higher plasma DNase activity than males ( p=0.03). Gonadectomy did not affect plasma DNase in males. Neither the concentration of total ecDNA, nor nuclear or mitochondrial DNA in plasma differed between the groups. No significant correlations between DNase and ecDNA were found. From previous studies on mice, it was expected, that male rats will have higher DNase activity. In contrast, our study in rats showed the opposite sex difference. This sex difference seems not to be caused by endogenous testosterone. Interestingly, no sex differences were observed in plasma ecDNA suggesting a complex or missing association between plasma ecDNA and DNase. The observed sex difference in plasma DNase should be taken into account in animal models of ecDNA-associated diseases.