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Extracellular DNA, also called cell-free DNA, released from dying cells or activated immune cells can be recognized by the immune system as a danger signal causing or enhancing inflammation. The cleavage of extracellular DNA is crucial for limiting the inflammatory response and maintaining homeostasis. Deoxyribonucleases (DNases) as enzymes that degrade DNA are hypothesized to play a key role in this process as a determinant of the variable concentration of extracellular DNA. DNases are divided into two families—DNase I and DNase II, according to their biochemical and biological properties as well as the tissue-specific production. Studies have shown that low DNase activity is both, a biomarker and a pathogenic factor in systemic lupus erythematosus. Interventional experiments proved that administration of exogenous DNase has beneficial effects in inflammatory diseases. Recombinant human DNase reduces mucus viscosity in lungs and is used for the treatment of patients with cystic fibrosis. This review summarizes the currently available published data about DNases, their activity as a potential biomarker and methods used for their assessment. An overview of the experiments with systemic administration of DNase is also included. Whether low-plasma DNase activity is involved in the etiopathogenesis of diseases remains unknown and needs to be elucidated.

Extracellular DNA (ecDNA) is DNA outside of cells, which is a result of various mechanisms. EcDNA is believed to be a cause of various pathogeneses as well as their potential biomarker. EcDNA is believed to also be part of small extracellular vesicles (sEVs) from cell cultures. If ecDNA is present in sEVs in plasma, their membrane may protect it from degradation by deoxyribonucleases. Moreover, sEVs play a role in the intercellular communication, and they can therefore transfer ecDNA between cells. The aim of this study was to investigate the presence of ecDNA in sEVs isolated from fresh human plasma by the ultracentrifugation and density gradient, which serves to exclude the co-isolation of non-sEVs compartments. The novelty of the current study is the investigation of the localization and subcellular origin of the ecDNA associated with sEVs in plasma, as well as the estimation of the approximate concentration. The cup-shaped sEVs were confirmed by transmission electron microscopy. The highest concentration of particles was in the size of 123 nm. The presence of the sEVs markers CD9 and TSG101 was confirmed by western blot. It was found that 60–75% of DNA is on the surface of sEVs, but a part of the DNA is localized inside the sEVs. Moreover, both nuclear and mitochondrial DNA were present in plasma EVs. Further studies should focus on the potential harmful autoimmune effect of DNA carried by plasma EVs or specifically sEVs.

Rheumatoid arthritis (RA) as a chronic autoimmune inflammatory disease increases extracellular DNA (ecDNA). Our previous study has shown that anti-inflammatory treatment reduces ecDNA, but it is unclear whether there is an association with treatment response. The aim of this study was to analyze the changes of ecDNA induced by biological disease-modifying antirheumatic drugs (bDMARDs) in RA patients with an emphasis on the subcellular origin of ecDNA. Plasma samples from 40 RA patients were collected in three different time-points: before treatment with bDMARDs as well as 3 and 12 months following treatment initiation. Total, nuclear and mitochondrial ecDNA was quantified using fluorometry and real-time PCR. Disease activity score (DAS28) and C-reactive protein (CRP) were used to monitor the clinical status and the response to treatment. Treatment with bDMARDs elicited an overall improvement of the clinical status: DAS28 and CRP showed a significant decrease by 54% and 43%, respectively, after 3 months of treatment. A significant decrease of total ecDNA by 60% and nuclear ecDNA by 58% was detected only in good responders after 3 months of bDMARDs treatment. No significant changes of plasma ecDNA concentration were observed in moderate and non-responders. Deoxyribonuclease activity was not affected by the treatment. None of the analyzed biomarkers differed between the groups at baseline. Plasma ecDNA especially of nuclear origin could potentially be useful to monitor the treatment response in RA. Further studies should shed light on disease-treatment interplay implicated in ecDNA origin potentially linked to neutrophil extracellular traps.

Fever and hypothermia represent two opposite strategies for fighting systemic inflammation. Fever results in immune activation; hypothermia is associated with energy conservation. Systemic Inflammatory Response Syndrome (SIRS) remains a significant cause of mortality worldwide. SIRS can lead to a broad spectrum of clinical symptoms but importantly, patients can develop fever or hypothermia. During infection, polymorphonuclear cells (PMNs) such as neutrophils prevent pathogen dissemination through the formation of neutrophil extracellular traps (NETs) that ensnare and kill bacteria. However, when dysregulated, NETs also promote host tissue damage. Herein, we tested the hypothesis that temperature modulates NETs homeostasis in response to infection and inflammation. NETs formation was studied in response to infectious ( Escherichia coli , Staphylococcus aureus ) and sterile (mitochondria) agents. When compared to body temperature (37°C), NETs formation increased at 40°C; interestingly, the response was stunted at 35°C and 42°C. While CD16+ CD49d+ PMNs represent a small proportion of the neutrophil population, they formed ~45-85% of NETs irrespective of temperature. Temperature increased formyl peptide receptor 1 (FPR1) expression to a differential extent in CD16+ CD49d- vs . CD49d+ PMNSs, suggesting further complexity to neutrophil function in hypo/hyperthermic conditions. The capacity of NETs to induce Toll-like receptor 9 (TLR9)-mediated NF-κB activation was found to be temperature independent. Interestingly, NET degradation was enhanced at higher temperatures, which corresponded with greater plasma DNase activity in response to temperature increase. Collectively, our observations indicate that NETs formation and clearance are enhanced at 40°C whilst temperatures of 35°C and 42°C attenuate this response. Targeting PMN-driven immunity may represent new venues for intervention in pathological inflammation.

Background: Periodontitis is a chronic disease with a complex etiology that includes bacterial colonization, excessive inflammation, and oxidative stress. The hormone melatonin has antioxidant properties and might contribute to alleviating chronic conditions by reducing oxidative stress. The aim of this study was to analyze the effect of exogenous melatonin on periodontitis in an animal model of the disease as well as in patients with periodontitis. Methods: In rats with ligature-induced periodontitis, melatonin was administered in drinking water for two weeks. In the human study, patients with treatment-resistant periodontitis were asked to rinse their mouths with a solution containing melatonin or placebo every evening for two weeks. Periodontal status as well as salivary markers of oxidative stress were assessed at the end of the study. Results: Neither radiography nor μCT revealed any significant effects of melatonin on alveolar bone loss. Gum recession was the only improved macroscopic measure in rats (p < 0.05). Analysis of salivary markers of oxidative stress revealed no effects of treatment in rats or humans despite clearly elevated melatonin concentrations in melatonin treated groups. Conclusion: Our results do not support the use of melatonin for the treatment of periodontitis. However, the negative outcome is limited by the short duration of the study and the chosen route of application as well as the dose of melatonin.

We investigated how maternal gestational diabetes (GDM) impacts the metabolic status of offspring. GDM was induced in CD1 mice consuming a fast-food diet (FFD) by repeated low-dose streptozotocin injections before mating. Offspring of normoglycemic standard chow or the FFD consuming dams served as controls. In 4-week-old offspring weaned to standard chow, plasma concentrations of extracellular DNA, inflammatory markers, and parameters of the cardiometabolic status (glycemia, liver lipid content; body, organ, and fat weight) were determined. Two-factor analysis of variance indicated that the male offspring of GDM dams manifest postnatal growth retardation and lower relative kidney weight. Regardless of sex, GDM offspring manifest the lowest IL-1α levels, and other inflammatory markers showed mild and inconsistent alterations. Offspring of dams consuming the FFD displayed higher liver triacylglycerols content. The three groups of offspring showed no significant differences in glycemia and extracellular DNA. Partial least squares-discriminant analysis indicated that male GDM offspring present lower kidney, body, and brown adipose tissue weights; lower IL-1α levels, and higher concentrations of GM-CSF and IL-10 compared with their FFD counterparts. The model failed to select discriminative variables in females. In conclusion, in mice, maternal GDM in the absence of obesity adversely affects the early growth of juvenile male offspring.

Circulating extracellular DNA (ecDNA) is known to worsen the outcome of many diseases. ecDNA released from neutrophils during infection or inflammation is present in the form of neutrophil extracellular traps (NETs). It has been shown that higher ecDNA concentration occurs in a number of inflammatory diseases including inflammatory bowel disease (IBD). Enzymes such as peptidyl arginine deiminases (PADs) are crucial for NET formation. We sought to describe the dynamics of ecDNA concentrations and fragmentation, along with NETosis during a mouse model of chemically induced colitis. Plasma ecDNA concentration was highest on day seven of dextran sulfate sodium (DSS) intake and the increase was time-dependent. This increase correlated with the percentage of cells undergoing NETosis and other markers of disease activity. Relative proportion of nuclear ecDNA increased towards more severe colitis; however, absolute amount decreased. In colon explant medium, the highest concentration of ecDNA was on day three of DSS consumption. Early administration of PAD4 inhibitors did not alleviate disease activity, but lowered the ecDNA concentration. These results uncover the biological characteristics of ecDNA in IBD and support the role of ecDNA in intestinal inflammation. The therapeutic intervention aimed at NETs and/or nuclear ecDNA has yet to be fully investigated.

Autism spectrum disorders (ASD) diagnostic procedure still lacks a uniform biological marker. This review gathers the information on microRNAs (miRNAs) specifically as a possible source of biomarkers of ASD. Extracellular vesicles, and their subset of exosomes, are believed to be a tool of cell-to-cell communication, and they are increasingly considered to be carriers of such a marker. The interest in studying miRNAs in extracellular vesicles grows in all fields of study and therefore should not be omitted in the field of neurodevelopmental disorders. The summary of miRNAs associated with brain cells and ASD either studied directly in the tissue or biofluids are gathered in this review. The heterogeneity in findings from different studies points out the fact that unified methods should be established, beginning with the determination of the accurate patient and control groups, through to sample collection, processing, and storage conditions. This review, based on the available literature, proposes the standardized approach to obtain the results that would not be affected by technical factors. Nowadays, the method of high-throughput sequencing seems to be the most optimal to analyze miRNAs. This should be followed by the uniformed bioinformatics procedure to avoid misvalidation. At the end, the proper validation of the obtained results is needed. With such an approach as is described in this review, it would be possible to obtain a reliable biomarker that would characterize the presence of ASD.

Extracellular DNA (ecDNA) is studied as a possible biomarker, but also as a trigger of the immune responses important for the pathogenesis of several diseases. Extracellular deoxyribonuclease (DNase) activity cleaves ecDNA. The aim of our study was to describe the interindividual variability of ecDNA and DNase activity in the plasma of healthy mice, and to analyze the potential determinants of the variability, including sex, age, and bodyweight. In this experiment, 58 adult CD1 mice (41 females and 31 males) of a variable age (3 to 16 months old) and bodyweight (females 25.7 to 52.1 g, males 24.6 to 49.6 g) were used. The plasma ecDNA was measured using a fluorometric method. The nuclear ecDNA and mitochondrial ecDNA were quantified using real-time PCR. The deoxyribonuclease activity was assessed using the single radial enzyme diffusion method. The coefficient of variance for plasma ecDNA was 139%, and for DNase 48%. Sex differences were not found in the plasma ecDNA (52.7 ± 73.0 ηg/mL), but in the DNase activity (74.5 ± 33.5 K.u./mL for males, and 47.0 ± 15.4 K.u./mL for females). There were no associations between plasma ecDNA and bodyweight or the age of mice. Our study shows that the variability of plasma ecDNA and DNase in adult healthy mice is very high. Sex, age, and bodyweight seem not to be major determinants of ecDNA variability in healthy mice. As ecDNA gains importance in the research of several diseases, it is of importance to understand its production and cleavage. Further studies should, thus, test other potential determinants, taking into account cleavage mechanisms other than DNase.

BackgroundExtracellular DNA (ecDNA) is increased in inflammation and it also induces inflammation. In patients with rheumatoid arthritis (RA), plasma ecDNA is higher than in healthy controls. Due to low specificity, it cannot be used for screening, but it might be useful for monitoring and prognosis of therapy success. The effect of treatment with biological disease-modifying antirheumatic drugs (bDMARDs) on plasma ecDNA in RA patients with regards to its subcellular origin has not been analyzed yet. The aim of this study was to describe the effects of bDMARDs on plasma ecDNA and its nuclear (nDNA) and mitochondrial (mtDNA) fractions in patients with RA.MethodsPlasma samples of 32 patients with RA were collected before, as well as 3 and 6 months after starting the treatment with bDMARDs. Total plasma ecDNA was quantified fluorometrically. The subcellular origin of ecDNA was assessed using real time PCR. Treatment success was monitored using DAS28 and C-reactive protein (CRP).ResultsThe clinical status of patients improved. Both DAS28 and CRP decreased by 52 and 73% after 3 months of treatment. Plasma ecDNA decreased significantly only after 6 months (by 26%). Real-time PCR showed that both, nDNA and mtDNA decreased by 63 and by 45% after 6 months.ConclusionTreatment with bDMARDs decreases plasma ecDNA of both nuclear and mitochondrial origin. Dynamics of ecDNA is slower than dynamics of standard clinical markers. Therefore, it is likely to be not useful for monitoring of the disease progress, at least for RA.