Reduced deoxyribonuclease enzyme activity in response to high postinjury mitochondrial DNA concentration provides a therapeutic target for Systemic Inflammatory Response Syndrome

Cell-free mitochondria are detected in high concentrations in the plasma of orthopedic trauma patients

BACKGROUND

Trauma and surgery can derange inflammatory and hemostasis responses, potentially leading to multiple organ failure. Mitochondrial damage-associated molecular patterns are known to be part of the pathomechanism, but their exact origin remains uncertain. Recently, intact mitochondria were detected in healthy individuals' peripheral blood, which suggested a potential role in inflammation.

METHODS

In this case-control study, we quantitated cell-free mitochondria in the blood of healthy subjects (n = 4) and trauma patients (n = 25) and assessed their relationship with patient demographics, injury and shock severity, markers of tissue injury, inflammation, and blood transfusions. Blood samples were collected before and after major orthopedic trauma surgery, and cell-free mitochondria were quantified using flow cytometry, targeting the outer mitochondrial membrane protein, TOMM70. Mitotracker Deep Red staining was used to assess mitochondrial membrane potential.

RESULTS

Trauma patients had significantly more cell-free mitochondria in their plasma compared with healthy controls, with highest counts immediately after surgery. The number of cell-free mitochondria decreased by day 5 postoperatively. Trauma patients exhibited a higher proportion of active cell-free mitochondria compared with healthy controls, especially immediately after surgery, and this proportion correlated with tissue injury markers. Associations were also found with acute thrombocytopenia, Denver multiple organ failure score, and transfusion of fresh frozen plasma and cryoprecipitate.

CONCLUSION

Our findings indicate that the mere high number of cell-free mitochondria in the circulation of trauma patients is not necessarily pro-inflammatory, but their active status is associated with more severe secondary tissue injury. The natural history of cell-free mitochondria in trauma needs to be characterized, including their potential cause-effect relationship with major postinjury complications.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level III.

Molecular basis of sepsis: A New insight into the role of mitochondrial DNA as a damage-associated molecular pattern

Sepsis remains a critical challenge in the field of medicine, claiming countless lives each year. Despite significant advances in medical science, the molecular mechanisms underlying sepsis pathogenesis remain elusive. Understanding molecular sequelae is gaining deeper insights into the roles played by various damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs) in disease pathogenesis. Among the known DAMPs, circulating cell-free mitochondrial DNA (mtDNA) garners increasing attention as a key player in the immune response during sepsis and other diseases. Mounting evidence highlights numerous connections between circulating cell-free mtDNA and inflammation, a pivotal state of sepsis, characterized by heightened inflammatory activity. In this review, we aim to provide an overview of the molecular basis of sepsis, particularly emphasizing the role of circulating cell-free mtDNA as a DAMP. We discuss the mechanisms of mtDNA release, its interaction with pattern recognition receptors (PRRs), and the subsequent immunological responses that contribute to sepsis progression. Furthermore, we discuss the forms of cell-free mtDNA; detection techniques of circulating cell-free mtDNA in various biological fluids; and the diagnostic, prognostic, and therapeutic implications offering insights into the potential for innovative interventions in sepsis management.

Systemic mechanisms of necrotic cell debris clearance

Necrosis is an overarching term that describes cell death modalities caused by (extreme) adverse conditions in which cells lose structural integrity. A guaranteed consequence of necrosis is the production of necrotic cell remnants, or debris. Necrotic cell debris is a strong trigger of inflammation, and although inflammatory responses are required for tissue healing, necrotic debris may lead to uncontrolled immune responses and collateral damage. Besides local phagocytosis by recruited leukocytes, there is accumulating evidence that extracellular mechanisms are also involved in necrotic debris clearance. In this review, we focused on systemic clearance mechanisms present in the bloodstream and vasculature that often cooperate to drive the clearance of cell debris. We reviewed the contribution and cooperation of extracellular DNases, the actin-scavenger system, the fibrinolytic system and reticuloendothelial cells in performing clearance of necrotic debris. Moreover, associations of the (mis)functioning of these clearance systems with a variety of diseases were provided, illustrating the importance of the mechanisms of clearance of dead cells in the organism.

Association between circulating cell-free mitochondrial DNA and inflammation factors in noninfectious diseases: A systematic review

OBJECTIVE

This study aimed to assess the correlation between the circulating cell-free mitochondria DNA and inflammation factors in noninfectious disease by meta-analysis of data from eligible studies.

MATERIALS AND METHODS

Through a comprehensive searching of pubmed, embase, web of science, cochrane from establishment of the database to October 31, 2022, studies were selected that investigated the association of circulating cell free mitochondria DNA with inflammatory factors in non-infectious diseases. Studies that met the inclusion criteria and were published in English or Chinese were included. Data of each correlation coefficients were extracted from the paper and 95% confidence intervals were calculated. Sensitivity and heterogeneity tests were carried out for each data.

RESULTS

A total of 660 articles were retrieved and 22 were included in this meta-analysis, including 2600 patients. A fixed effects model was employed to examine ISS and IL-8, others were analyzed using random effects models. The correlation coefficient between mtDNA and ISS score was 0.37 (95%CI = [0.232;0.494]), p<0.0001, heterogeneity I2 = 46%, p = 0.11). The correlation coefficients between mtDNA and inflammatory factors are as follows: TNFα, 0.405 [(95%CI = [0.253;0.538], p<0.0001, heterogeneity I2 = 77%, p = 0.0001]. IL-6, 0.469 [(95%CI = [0.296;0.612]), p = 0.0001, heterogeneity I2 = 93%, p<0.0001]. CRP, 0.333[(95%CI = [0.149;0.494]), p = 0.005, heterogeneity I2 = 85%, p<0.0001]. IL-8, 0.343[(95%CI = [0.233;0.524]), p = 0.001, heterogeneity I2 = 50%, p = 0.09]. PCT, 0.333 [(95%CI = [0.06;0.64]), p = 0.09,heterogeneity I2 = 64%,p = 0.06]. There were no significant publication bias for TNFα, IL-6 and CRP.

CONSLUSION

Circulating cell free mtDNA was moderate positively correlated with the expression of inflammatory factors and the degree of trauma.

The Diagnostic, Therapeutic and Prognostic Relevance of Neutrophil Extracellular Traps in Polytrauma

Neutrophil extracellular traps (NETs) represent a recently discovered polymorphonuclear leukocyte-associated ancient defence mechanism, and they have also been identified as part of polytrauma patients' sterile inflammatory response. This systematic review aimed to determine the clinical significance of NETs in polytrauma, focusing on potential prognostic, diagnostic and therapeutic relevance. The methodology covered all major databases and all study types, but was restricted to polytraumatised humans. Fourteen studies met the inclusion criteria, reporting on 1967 patients. Ten samples were taken from plasma and four from whole blood. There was no standardisation of methodology of NET detection among plasma studies; however, of all the papers that included a healthy control NET, proxies were increased. Polytrauma patients were consistently reported to have higher concentrations of NET markers in peripheral blood than those in healthy controls, but their diagnostic, therapeutic and prognostic utility is equivocal due to the diverse study population and methodology. After 20 years since the discovery of NETs, their natural history and potential clinical utility in polytrauma is undetermined, requiring further standardisation and research.

The immune suppressive properties of damage associated molecular patterns in the setting of sterile traumatic injury

Associated with the development of hospital-acquired infections, major traumatic injury results in an immediate and persistent state of systemic immunosuppression, yet the underlying mechanisms are poorly understood. Detected in the circulation in the minutes, days and weeks following injury, damage associated molecular patterns (DAMPs) are a heterogeneous collection of proteins, lipids and DNA renowned for initiating the systemic inflammatory response syndrome. Suggesting additional immunomodulatory roles in the post-trauma immune response, data are emerging implicating DAMPs as potential mediators of post-trauma immune suppression. Discussing the results of in vitro, in vivo and ex vivo studies, the purpose of this review is to summarise the emerging immune tolerising properties of cytosolic, nuclear and mitochondrial-derived DAMPs. Direct inhibition of neutrophil antimicrobial activities, the induction of endotoxin tolerance in monocytes and macrophages, and the recruitment, activation and expansion of myeloid derived suppressor cells and regulatory T cells are examples of some of the immune suppressive properties assigned to DAMPs so far. Crucially, with studies identifying the molecular mechanisms by which DAMPs promote immune suppression, therapeutic strategies that prevent and/or reverse DAMP-induced immunosuppression have been proposed. Approaches currently under consideration include the use of synthetic polymers, or the delivery of plasma proteins, to scavenge circulating DAMPs, or to treat critically-injured patients with antagonists of DAMP receptors. However, as DAMPs share signalling pathways with pathogen associated molecular patterns, and pro-inflammatory responses are essential for tissue regeneration, these approaches need to be carefully considered in order to ensure that modulating DAMP levels and/or their interaction with immune cells does not negatively impact upon anti-microbial defence and the physiological responses of tissue repair and wound healing.

Dysregulated Neutrophil Phenotype and Function in Hospitalised Non-ICU COVID-19 Pneumonia

Rationale: Infection with the SARS-CoV2 virus is associated with elevated neutrophil counts. Evidence of neutrophil dysfunction in COVID-19 is based on transcriptomics or single functional assays. Cell functions are interwoven pathways, and understanding the effect across the spectrum of neutrophil function may identify therapeutic targets. Objectives: Examine neutrophil phenotype and function in 41 hospitalised, non-ICU COVID-19 patients versus 23 age-matched controls (AMC) and 26 community acquired pneumonia patients (CAP). Methods: Isolated neutrophils underwent ex vivo analyses for migration, bacterial phagocytosis, ROS generation, NETosis and receptor expression. Circulating DNAse 1 activity, levels of cfDNA, MPO, VEGF, IL-6 and sTNFRI were measured and correlated to clinical outcome. Serial sampling on day three to five post hospitalization were also measured. The effect of ex vivo PI3K inhibition was measured in a further cohort of 18 COVID-19 patients. Results: Compared to AMC and CAP, COVID-19 neutrophils demonstrated elevated transmigration (p = 0.0397) and NETosis (p = 0.0332), and impaired phagocytosis (p = 0.0036) associated with impaired ROS generation (p < 0.0001). The percentage of CD54+ neutrophils (p < 0.001) was significantly increased, while surface expression of CD11b (p = 0.0014) and PD-L1 (p = 0.006) were significantly decreased in COVID-19. COVID-19 and CAP patients showed increased systemic markers of NETosis including increased cfDNA (p = 0.0396) and impaired DNAse activity (p < 0.0001). The ex vivo inhibition of PI3K γ and δ reduced NET release by COVID-19 neutrophils (p = 0.0129). Conclusions: COVID-19 is associated with neutrophil dysfunction across all main effector functions, with altered phenotype, elevated migration and NETosis, and impaired antimicrobial responses. These changes highlight that targeting neutrophil function may help modulate COVID-19 severity.

NOT ALL CELL-FREE MITOCHONDRIAL DNA IS EQUAL IN TRAUMA PATIENTS

ABSTRACT

Mitochondrial DNA (mtDNA) acts as a proinflammatory damage-associated molecular pattern that stimulates innate immune activation via Toll-like receptor 9, similarly to bacterial DNA. A number of clinical studies have measured elevated cell-free mtDNA in the plasma of trauma patients, thought to originate from tissue injury and inflammatory processes; however, the magnitude of this increase, the absolute concentration, and the association with poor outcomes varies considerably across studies. Measurements of cell-free mtDNA in healthy individuals have shown that the majority of "cell-free" mtDNA (>95%) can be centrifuged/filtered from plasma in the size range of 0.45 to 5 μm, suggesting that there are larger forms of mtDNA-containing complexes in the plasma that could be considered cell-free. Whether this is true for trauma patients (and other relevant disease states) and the clinical relevance of the larger forms of mtDNA is unknown. These findings from healthy individuals also suggest that the centrifugation speeds used to generate cell-free plasma (which are rarely consistent among studies) could result in mixed populations of cell-free mtDNA that could confound associations with outcomes. We demonstrate in this study of 25 major trauma patients that the majority of the cell-free mtDNA in trauma patient plasma (>95%) is removed after centrifugation at 16,000g. Despite the larger forms of mtDNA being predominant, they do not correlate with outcomes or expected parameters such as injury/shock severity, multiple organ failure, and markers of inflammation, whereas low-molecular-weight cell-free mtDNA correlates strongly with these variables.

Systemic inflammatory response syndrome is triggered by mitochondrial damage (Review)

Mitochondria are key organelles of cellular energy metabolism; both mitochondrial function and metabolism determine the physiological function of cells and serve an essential role in immune responses. Key damage‑associated molecular patterns (DAMPs), such as mitochondrial DNA and N‑formyl peptides, released following severe trauma‑induced mitochondrial damage may affect the respiratory chain, enhance oxidative stress and activate systemic inflammatory responses via a variety of inflammation‑associated signaling pathways. Severe trauma can lead to sepsis, multiple organ dysfunction syndrome and death. The present review aimed to summarize the pathophysiological mechanisms underlying the effects of human mitochondrial injury‑released DAMPs on triggering systemic inflammatory responses and to determine their potential future clinical applications in preventing and treating sepsis.

Early Plasma Nuclear DNA, Mitochondrial DNA, and Nucleosome Concentrations Are Associated With Acute Kidney Injury in Critically Ill Trauma Patients

Circulating nucleic acids, alone and in complex with histones as nucleosomes, have been proposed to link systemic inflammation and coagulation after trauma to acute kidney injury (AKI). We sought to determine the association of circulating nucleic acids measured at multiple time points after trauma with AKI risk.

Traumatic injury is associated with reduced deoxyribonuclease activity and dysregulation of the actin scavenging system

Background

Traumatic injury is associated with increased concentrations of cell-free DNA (cfDNA) in the circulation, which contribute to post-injury complications. The endonuclease deoxyribonuclease 1 (DNase-1) is responsible for removing 90% of circulating cfDNA. Recently, DNase activity was reported to be significantly reduced following major non-traumatic brain injury (TBI), but the processes responsible were not investigated. Moreover, it is not known how quickly following injury DNase activity is reduced and whether this also occurs after TBI.

Methods

At 3 post-injury time points (≤1, 4–12 and 48–72 hours), blood samples were obtained from 155 adult trauma patients that had sustained an isolated TBI (n = 21), TBI with accompanying extracranial injury (TBI⁺) (n = 53) or an extracranial injury only (ECI) (n = 81). In addition to measuring cfDNA levels and the activity and expression of DNase, circulating concentrations of monomeric globular action (G-actin), an inhibitor of DNase-1, and the actin scavenging proteins gelsolin (GSN) and vitamin D binding protein (VDBP) were determined and values compared to a cohort of healthy controls.

Results

Significantly elevated concentrations of plasma cfDNA were seen in TBI, TBI⁺ and ECI patients at all study time points when compared to healthy controls. cfDNA levels were significantly higher at ≤1 hour post-injury in ECI patients who subsequently developed multiple organ dysfunction syndrome when compared to those who did not. Plasma DNase-1 protein was significantly elevated in all patient groups at all sampling time points. In contrast, DNase enzyme activity was significantly reduced, with this impaired function evident in TBI⁺ patients within minutes of injury. Circulating concentrations of G-actin were elevated in all patient cohorts in the immediate aftermath of injury and this was accompanied by a significant reduction in the levels of GSN and VDBP.

Conclusions

The post-traumatic increase in circulating cfDNA that occurs following extracranial trauma and TBI is accompanied by reduced DNase activity. We propose that, secondary to reduced GSN and VDBP levels, elevated circulating concentrations of G-actin underlie the post-injury reduction in DNase activity. Reducing circulating cfDNA levels via therapeutic restoration of DNase-1 activity may improve clinical outcomes post-injury.

Preliminary report of in vitro and in vivo effectiveness of dornase alfa on SARS-CoV-2 infection

Dornase alfa, the recombinant form of the human DNase I enzyme, breaks down neutrophil extracellular traps (NET) that include a vast amount of DNA fragments, histones, microbicidal proteins and oxidant enzymes released from necrotic neutrophils in the highly viscous mucus of cystic fibrosis patients. Dornase alfa has been used for decades in patients with cystic fibrosis to reduce the viscoelasticity of respiratory tract secretions, to decrease the severity of respiratory tract infections, and to improve lung function. Previous studies have linked abnormal NET formations to lung diseases, especially to acute respiratory distress syndrome (ARDS). It is well known that novel coronavirus disease 2019 (COVID-19) pneumonia progresses to ARDS and even multiple organ failure. High blood neutrophil levels are an early indicator of COVID-19 and predict severe respiratory diseases. Also it is reported that mucus structure in COVID-19 is very similar to that in cystic fibrosis due to the accumulation of excessive NET in the lungs. In this study, we showed the recovery of three individuals with COVID-19 after including dornase alfa in their treatment. We followed clinical improvement in the radiological analysis (two of three cases), oxygen saturation (Spo₂), respiratory rate, disappearance of dyspnoea, coughing and a decrease in NET formation and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load after the treatment. Also here, we share our preliminary results suggesting that dornase alfa has an anti-viral effect against SARS-CoV-2 infection in a green monkey kidney cell line, Vero, and a bovine kidney cell line, MDBK, without determined cytotoxicity on healthy peripheral blood mononuclear cells.

Deoxyribonucleases and Their Applications in Biomedicine

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.

Use of DAMPs and SAMPs as Therapeutic Targets or Therapeutics: A Note of Caution

This opinion article discusses the increasing attention paid to the role of activating damage-associated molecular patterns (DAMPs) in initiation of inflammatory diseases and suppressing/inhibiting DAMPs (SAMPs) in resolution of inflammatory diseases and, consequently, to the future roles of these novel biomarkers as therapeutic targets and therapeutics. Since controlled production of DAMPs and SAMPs is needed to achieve full homeostatic restoration and repair from tissue injury, only their pathological, not their homeostatic, concentrations should be therapeutically tackled. Therefore, distinct caveats are proposed regarding choosing DAMPs and SAMPs for therapeutic purposes. For example, we discuss the need to a priori identify and define a context-dependent “homeostatic DAMP:SAMP ratio” in each case and a “homeostatic window” of DAMP and SAMP concentrations to guarantee a safe treatment modality to patients. Finally, a few clinical examples of how DAMPs and SAMPs might be used as therapeutic targets or therapeutics in the future are discussed, including inhibition of DAMPs in hyperinflammatory processes (e.g., systemic inflammatory response syndrome, as currently observed in Covid-19), administration of SAMPs in chronic inflammatory diseases, inhibition of SAMPs in hyperresolving processes (e.g., compensatory anti-inflammatory response syndrome), and administration/induction of DAMPs in vaccination procedures and anti-cancer therapy.

Comparative analysis of excretory-secretory products of muscle larvae of three isolates of Trichinella pseudospiralis by the iTRAQ method

Trichinella pseudospiralis is a non-encapsulated intracellular parasitic nematode that can possess a strong ability to modulate the host immune response. Here, we compared the differentially expressed proteins of excretory-secretory (ES) products in three isolates of T. pseudospiralis muscle larvae (ML) [from Russia (RUS), United States of America (USA) and Australia (AUS)] using isobaric tags for relative and absolute quantification (iTRAQ)-based technology. A total of 2591 nonredundant proteins were identified, of which 65 (146), 72 (98) and 43 (103) significantly upregulated (downregulated) differentially expressed proteins were detected among pairwise comparisons (T4RUS vs T4USA, T4AUS vs T4USA and T4RUS vs T4AUS). In addition, GO annotation, KEGG and STRING analyses were carried out on the screened differentially altered proteins. The main biological processes involved included carbohydrate metabolic processes, DNA metabolic processes, cellular protein modification processes and homeostatic processes. The majority of KEGG pathways were found to be related to the metabolic pathways, lysosome pathway and protein processing in endoplasmic reticulum. Moreover, all ES protein expression levels involved in the lysosome pathway were significantly higher in the T4USA isolate than in the other two isolates. We also found differences in the expression of some important immunoregulatory proteins, such as protein disulfide-isomerase, thioredoxin protein and deoxyribonuclease-2-alpha, between different isolates of T. pseudospiralis ML. Flow cytometry was used to detect the increase in the CD4+/CD8 + T-cell ratio in pig peripheral blood and to verify the effect of T. pseudospiralis on the Th1/Th2 polarization of the host. Quantitative real-time PCR analysis also confirmed that the changes in the transcriptional level of genes were consistent with those at the proteomic level. These findings reveal the possible role of significantly differentially expressed proteins in ES products of the different isolates of T. pseudospiralis in antagonizing and participating in the regulation of the host immune response and maintaining a stable growth environment.

Protocol for TRAUMADORNASE: a prospective, randomized, multicentre, double-blinded, placebo-controlled clinical trial of aerosolized dornase alfa to reduce the incidence of moderate-to-severe hypoxaemia in ventilated trauma patients

Background

Acute respiratory distress syndrome continues to drive significant morbidity and mortality after severe trauma. The incidence of trauma-induced, moderate-to-severe hypoxaemia, according to the Berlin definition, could be as high as 45%. Its pathophysiology includes the release of damage-associated molecular patterns (DAMPs), which propagate tissue injuries by triggering neutrophil extracellular traps (NETs). NETs include a DNA backbone coated with cytoplasmic proteins, which drive pulmonary cytotoxic effects. The structure of NETs and many DAMPs includes double-stranded DNA, which prevents their neutralization by plasma. Dornase alfa is a US Food and Drug Administration-approved recombinant DNase, which cleaves extracellular DNA and may therefore break up the backbone of NETs and DAMPs. Aerosolized dornase alfa was shown to reduce trauma-induced lung injury in experimental models and to improve arterial oxygenation in ventilated patients.

Methods

TRAUMADORNASE will be an institution-led, multicentre, double-blinded, placebo-controlled randomized trial in ventilated trauma patients. The primary trial objective is to demonstrate a reduction in the incidence of moderate-to-severe hypoxaemia in severe trauma patients during the first 7 days from 45% to 30% by providing aerosolized dornase alfa as compared to placebo. The secondary objectives are to demonstrate an improvement in lung function and a reduction in morbidity and mortality. Randomization of 250 patients per treatment arm will be carried out through a secure, web-based system. Statistical analyses will include a descriptive step and an inferential step using fully Bayesian techniques. The study was approved by both the Agence Nationale de la Sécurité du Médicament et des Produits de Santé (ANSM, on 5 October 2018) and a National Institutional Review Board (CPP, on 6 November 2018). Participant recruitment began in March 2019. Results will be published in international peer-reviewed medical journals.

Discussion

If early administration of inhaled dornase alfa actually reduces the incidence of moderate-to-severe hypoxaemia in patients with severe trauma, this new therapeutic strategy may be easily implemented in many clinical trauma care settings. This treatment may facilitate ventilator weaning, reduce the burden of trauma-induced lung inflammation and facilitate recovery and rehabilitation in severe trauma patients.

Trial registration

ClinicalTrials.gov, NCT03368092. Registered on 11 December 2017.

Deoxyribonuclease Reduces Tissue Injury and Improves Survival After Hemorrhagic Shock

BACKGROUND

Hemorrhagic shock (HS) caused by rapid loss of a large amount of blood is the leading cause of early death after severe injury. When cells are damaged during HS, many intracellular components including DNA are released into the circulation and function as endogenous damage-associated molecular patterns (DAMPs) that can trigger excessive inflammatory response and subsequently multiple organ dysfunction. We hypothesized that the administration of deoxyribonuclease I (DNase I) could reduce cell-free DNA and attenuate tissue damage in HS.

METHODS

Eight-week-old male C57BL/6 mice underwent HS by controlled bleeding from the femoral artery for 90 min, followed by resuscitation with Ringer's lactate solution (vehicle) or DNase I (10 mg/kg BW).

RESULTS

At 20 h after HS, serum levels of cell-free DNA were increased by 7.6-fold in the vehicle-treated HS mice compared with sham, while DNase I reduced its levels by 47% compared with the vehicle group. Serum levels of tissue injury markers (lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase) and proinflammatory cytokine interleukin 6 were significantly reduced in the DNase I-treated mice. In the lungs, messenger RNA levels of proinflammatory cytokines (interleukin 6 and interleukin 1 β), chemoattractant macrophage inflammatory protein - 2, and myeloperoxidase activity were significantly decreased in HS mice after DNase I. Finally, DNase I significantly improved the 10-day survival rate in HS mice.

CONCLUSIONS

Administration of DNase I attenuates tissue damage and systemic and lung inflammation, leading to improvement of survival in HS mice. Thus, DNase I may potentially serve as an adjunct therapy for managing patients with HS.