cfDNA correlates with endothelial damage after cardiac surgery with prolonged cardiopulmonary bypass and amplifies NETosis in an intracellular TLR9-independent manner

Ac2-26 Reduced Lung Injury After Cardiopulmonary Bypass via the AKT1/GSK3β/eNOS Pathway

INTRODUCTION

Cardiopulmonary bypass (CPB) leads to severe inflammation and lung injury. Our previous study showed that Ac2-26 (an active n-terminal peptide of Annexin A1) can reduce acute lung injury. The aim of this study was to evaluate the effect of Ac2-26 on lung injury in CPB rats.

METHODS

Forty rats were randomly divided into the sham, CPB, Ac, Ac/serine/threonine kinase 1 (AKT1), and Ac/ glycogen synthase kinase (GSK)-3β groups. The rats in the sham group only received anesthesia, intubation, and cannulation. The rats in the other 4 groups received the standard CPB procedure. The rats in the CPB, Ac, Ac/AKT1, and Ac/GSK3β groups were immediately injected with saline, Ac2-26 (1 mg/kg), Ac2-26 combined with short hairpin RNA (AKT1), or Ac2-26 combined with a GSK3β inhibitor after CPB. At 12 h after the end of CPB, the PaO2/ fraction of inspired oxygen ratio, wet/dry weight ratio and protein content in the bronchoalveolar lavage fluid (BALF) were recorded. The numbers of macrophages and neutrophils in the BALF and blood were determined. Cytokine levels in the blood and BALF were investigated. Lung tissue histology and apoptosis were estimated. The expression of nuclear factor kappa- B, AKT1, GSK3β, endothelial nitric oxide synthase and apoptosis-related proteins was analyzed. The survival of all the rats was recorded.

RESULTS

Compared with the rats in the sham group, all the parameters examined worsened in the rats that received CPB. Compared with those in the CPB group, Ac2-26 significantly improved pulmonary capillary permeability, reduced cytokine levels, and decreased histological scores and apoptosis. The protective effect of Ac2-26 on lung injury was significantly reversed by AKT1 short hairpin RNA or a GSK3β inhibitor.

CONCLUSIONS

Ac2-26 significantly reduced lung injury and inflammation after CPB. The protective effect of Ac2-26 mainly depended on the AKT1/GSK3β/endothelial nitric oxide synthase pathway.

The emerging role of neutrophil extracellular traps in ulcerative colitis

Ulcerative colitis (UC) is characterized by chronic non-recessive inflammation of the intestinal mucosa involving both innate and adaptive immune responses. Currently, new targeted therapies are urgently needed for UC, and neutrophil extracellular traps (NETs) are new therapeutic options. NETs are DNA-based networks released from neutrophils into the extracellular space after stimulation, in which a variety of granule proteins, proteolytic enzymes, antibacterial peptides, histones, and other network structures are embedded. With the deepening of the studies on NETs, their regulatory role in the development of autoimmune and autoinflammatory diseases has received extensive attention in recent years. Increasing evidence indicates that excess NETs exacerbate the inflammatory response in UC, disrupting the structure and function of the intestinal mucosal barrier and increasing the risk of thrombosis. Although NETs are usually assigned a deleterious role in promoting the pathological process of UC, they also appear to have a protective role in some models. Despite such progress, comprehensive reviews describing the therapeutic promise of NETs in UC remain limited. In this review, we discuss the latest evidence for the formation and degradation of NETs, focusing on their double-edged role in UC. Finally, the potential implications of NETs as therapeutic targets for UC will be discussed. This review aims to provide novel insights into the pathogenesis and therapeutic options for UC.

PLASMA DYNAMICS OF NEUTROPHIL EXTRACELLULAR TRAPS AND CELL-FREE DNA IN SEPTIC AND NONSEPTIC VASOPLEGIC SHOCK: A PROSPECTIVE COMPARATIVE OBSERVATIONAL COHORT STUDY

ABSTRACT

Background: The association between neutrophil extracellular traps (NETs) and the requirement for vasopressor and inotropic support in vasoplegic shock is unclear. This study aimed to investigate the dynamics of plasma levels of NETs and cell-free DNA (cfDNA) up to 48 h after the admission to the intensive care unit (ICU) for management of vasoplegic shock of infectious (SEPSIS) or noninfectious (following cardiac surgery, CARDIAC) origin. Methods: This is a prospective, observational study of NETs and cfDNA plasma levels at 0H (admission) and then at 12H, 24H, and 48H in SEPSIS and CARDIAC patients. The vasopressor inotropic score (VIS), the Sequential Organ Failure Assessment (SOFA) score, and time spent with invasive ventilation, in ICU and in hospital, were recorded. Associations between NETs/cfDNA and VIS and SOFA were analyzed by Spearman's correlation (rho), and between NETs/cfDNA and ventilation/ICU/hospitalization times by generalized linear regression. Results: Both NETs and cfDNA remained elevated over 48 h in SEPSIS (n = 46) and CARDIAC (n = 30) patients, with time-weighted average concentrations greatest in SEPSIS (NETs median difference 0.06 [0.02-0.11], P = 0.005; cfDNA median difference 0.48 [0.20-1.02], P < 0.001). The VIS correlated to NETs (rho = 0.3-0.60 in SEPSIS, P < 0.01, rho = 0.36-0.57 in CARDIAC, P ≤ 0.01) and cfDNA (rho = 0.40-0.56 in SEPSIS, P < 0.01, rho = 0.38-0.47 in CARDIAC, P < 0.05). NETs correlated with SOFA. Neither NETs nor cfDNA were independently associated with ventilator/ICU/hospitalization times. Conclusion: Plasma levels of NETs and cfDNA correlated with the dose of vasopressors and inotropes administered over 48 h in patients with vasoplegic shock from sepsis or following cardiac surgery. NETs levels also correlated with organ dysfunction. These findings suggest that similar mechanisms involving release of NETs are involved in the pathophysiology of vasoplegic shock irrespective of an infectious or noninfectious etiology.

Inflammation-, immunothrombosis,- and autoimmune-feedback loops may lead to persistent neutrophil self-stimulation in long COVID

Understanding the pathophysiology of long COVID is one of the most intriguing challenges confronting contemporary medicine. Despite observations recently made in the relevant molecular, cellular, and physiological domains, it is still difficult to say whether the post-acute sequelae of COVID-19 directly correspond to the consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This work hypothesizes that neutrophils and neutrophil extracellular traps (NETs) production are at the interconnection of three positive feedback loops which are initiated in the acute phase of SARS-CoV-2 infection, and which involve inflammation, immunothrombosis, and autoimmunity. This phenomenon could be favored by the fact that SARS-CoV-2 may directly bind and penetrate neutrophils. The ensuing strong neutrophil stimulation leads to a progressive amplification of an exacerbated and uncontrolled NETs production, potentially persisting for months beyond the acute phase of infection. This continuous self-stimulation of neutrophils leads, in turn, to systemic inflammation, micro-thromboses, and the production of autoantibodies, whose significant consequences include the persistence of endothelial and multiorgan damage, and vascular complications.

Whole blood transcriptomics reveals granulocyte colony-stimulating factor as a mediator of cardiopulmonary bypass-induced systemic inflammatory response syndrome

Objectives

Systemic inflammatory response syndrome (SIRS) is a frequent complication of cardiopulmonary bypass (CPB). SIRS is associated with significant morbidity and mortality, but its pathogenesis remains incompletely understood, and as a result, biomarkers are lacking and treatment remains expectant and supportive. This study aimed to understand the pathophysiological mechanisms driving SIRS induced by CPB and identify novel therapeutic targets that might reduce systemic inflammation and improve patient outcomes.

Methods

Twenty-one patients undergoing cardiac surgery and CPB were recruited, and blood was sampled before, during and after surgery. SIRS was defined using the American College of Chest Physicians/Society of Critical Care Medicine criteria. We performed immune cell profiling and whole blood transcriptomics and measured individual mediators in plasma/serum to characterise SIRS induced by CPB.

Results

Nineteen patients fulfilled criteria for SIRS, with a mean duration of 2.7 days. Neutrophil numbers rose rapidly with CPB and remained elevated for at least 48 h afterwards. Transcriptional signatures associated with neutrophil activation and degranulation were enriched during CPB. We identified a network of cytokines governing these transcriptional changes, including granulocyte colony-stimulating factor (G-CSF), a regulator of neutrophil production and function.

Conclusions

We identified neutrophils and G-CSF as major regulators of CPB-induced systemic inflammation. Short-term targeting of G-CSF could provide a novel therapeutic strategy to limit neutrophil-mediated inflammation and tissue damage in SIRS induced by CPB.

The Role and Mechanism of Metformin in Inflammatory Diseases

Metformin is a classical drug used to treat type 2 diabetes. With the development of research on metformin, it has been found that metformin also has several advantages aside from its hypoglycemic effect, such as anti-inflammatory, anti-aging, anti-cancer, improving intestinal flora, and other effects. The prevention of inflammation is critical because chronic inflammation is associated with numerous diseases of considerable public health. Therefore, there has been growing interest in the role of metformin in treating various inflammatory conditions. However, the precise anti-inflammatory mechanisms of metformin were inconsistent in the reported studies. Thus, this review aims to summarize various currently known possible mechanisms of metformin involved in inflammatory diseases and provide references for the clinical application of metformin.

Effect of Thoracic Epidural Anesthesia on Perioperative Neutrophil Extracellular Trapping Markers in Patients Undergoing Anesthesia and Surgery for Colorectal Cancer: A Randomized, Controlled Trial

BACKGROUND

Neutrophil extracellular trapping (NETosis) is an immunologic mechanism strongly linked with increased metastatic risk in colorectal cancer. The authors hypothesized that patients who received propofol-epidural anesthesia (PEA) would exhibit decreases in the expression of serum neutrophil myeloperoxidase (MPO) and citrullinated histone H3 (H3Cit) levels compared with patients who received general anesthesia (GA).

METHODS

Colorectal cancer surgery patients were randomly assigned to the PEA (n = 30) or GA (n = 30) group. Serum MPO, H3Cit, and metalloproteinase-9 (MMP-9) levels before surgery and 24 h after surgery were measured, and visual analogue scale (VAS) scores were recorded.

RESULTS

The patients who received PEA showed decreases in MPO (28.06 ± 11.23 vs 20.54 ± 7.29 ng/ ml; P = 0.004) and H3Cit [3.22 ± 0.86 vs 2.73 ± 0.94 ng/ ml; P = 0.042) 24 h after surgery compared with the patients subjected to GA. In addition, there was no difference in MMP-9 levels (75.98 ± 26.9 vs 73.45 ± 28.4 ng/ ml; P = 0.726). The visual analogue scale scores 2 h and 24 h after operation were significantly lower in PEA group (P < 0.05). The number of postoperative analgesia pump pressings and sufentanil consumptions within 48 h after surgery were significantly lower in the PEA group (P < 0.001).

CONCLUSIONS

Propofol-epidural anesthesia reduces the expression of NETosis (MPO and H3Cit) in serum during colorectal cancer surgery.

CLINICAL TRIAL REGISTRATION

ChiCTR2200066708 ( www.chictr.org.cn ).

The Effect of Local Anesthetics on Neutrophils in the Context of Different Isolation Techniques

Various functions of polymorphonuclear neutrophils (PMNs) are related to diseases and postoperative plasma changes. The influence of some local anesthetics (LAs) on PMNs obtained by conventional isolation methods and their functions has already been demonstrated. This study investigates the effect of selected LAs on PMNs, comparing a new isolation method with conventional ones. To obtain the PMNs, we performed either gelafundin sedimentation, hypotonic lysis or density gradient centrifugation. Subsequently, PMNs were mixed with different concentrations of bupivacaine, levobupivacaine, lidocaine or ropivacaine. Live cell imaging and flow cytometry were performed to quantify the migration, ROS production, NETosis and antigen expression of PMNs. We found the inhibition of chemotaxis and ROS production by LAs. PMNs showed a strong reduction in time to half maximal NETosis in response to bupivacaine and lidocaine, but not to levobupivacaine and ropivacaine. We also found distinct differences in survival time and migration duration between the isolation methods. This suggests that the careful selection of LAs has a short-term impact on in vitro PMNs.

Impact of postoperative acute kidney injury on short-term outcomes of patients with Bentall surgery for any reason

BACKGROUND

Acute kidney injury (AKI) after cardiac surgery is a well-known risk factor for increased postoperative mortality and morbidity. The effect of postoperative developed AKI on postoperative outcomes in patients after Bentall procedure has been incompletely investigated. The present study was dedicated to assessing the impact of postoperative AKI on morbidity and 30-day mortality in this specific cohort.

METHODS

In a retrospective observational study, we investigated 249 patients undergoing Bentall procedure from January 2014 to March 2018 at the University Hospital of Cologne, Germany. After excluding patients with preoperative renal impairment, patients were divided into an AKI group (n = 88) and a non-AKI group (n = 97). Postoperative outcomes and 30-day mortality were analyzed using univariate regression analysis. AKI was defined by AKIN criteria.

RESULTS

Mortality during ICU and hospital stay, as well as 30-day mortality, was significantly higher in the AKI group (all p < 0.001). Patients with postoperative developed AKI revealed 9.3-fold higher odds for ICU mortality and 6.7-fold higher odds for 30-day mortality in comparison to non-AKI group (all p < 0.004) as well as 4.5-fold higher odds for stroke. Coronary artery bypass time, as well as cross-clamp time, were similarly distributed between groups, whereas incidences of postoperative bleeding, myocardial infarction, and need for rethoracotomy occurred significantly more often in patients with postoperatively developed AKI (all p < 0.04).

CONCLUSION

Patients undergoing Bentall surgery who postoperatively developed AKI showed significantly higher morbidity and mortality. AKI points out to be an early predictor for poor outcomes. Thus, as a consequence, patients with postoperatively developed AKI should be highly monitored for immediate intervention.

The prognostic value of elevated neutrophil-lymphocyte ratio for cardiac surgery-associated acute kidney injury: A systematic review and meta-analysis

BACKGROUND

Patients undergoing cardiac surgery are at significant risk of developing postoperative acute kidney injury (AKI). Neutrophil-lymphocyte ratio (NLR) is a widely available inflammatory biomarker which may be of prognostic value in this setting.

METHODS

We conducted a systematic review and meta-analysis of studies reporting associations between perioperative NLR with postoperative AKI. We searched Medline, Embase and the Cochrane Library, without language restriction, from inception to May 2022 for relevant studies. We meta-analysed the reported odds ratios (ORs) with 95% confidence intervals (CIs) for both elevated preoperative and postoperative NLR with risk of postoperative AKI and need for renal replacement therapy (RRT). We conducted a meta-regression to explore inter-study statistical heterogeneity.

RESULTS

Twelve studies involving 10,724 participants undergoing cardiac surgery were included, with eight studies being deemed at high risk of bias using PROBAST modelling. We found statistically significant associations between elevated preoperative NLR and postoperative AKI (OR 1.45, 95% CI 1.18-1.77), as well as postoperative need for RRT (OR 2.37, 95% CI 1.50-3.72). Postoperative NLR measurements were not of prognostic significance.

CONCLUSIONS

Elevated preoperative NLR is a reliable inflammatory biomarker for predicting AKI following cardiac surgery.

DNA repair deficiency as circulating biomarker in prostate cancer

Deleterious aberrations in DNA repair genes are actionable in approximately 25% of metastatic castration-resistant prostate cancers (mCRPC) patients. Homology recombination repair (HRR) is the DNA damage repair (DDR) mechanism most frequently altered in prostate cancer; of note BRCA2 is the most frequently altered DDR gene in this tumor. Poly ADP-ribose polymerase inhibitors showed antitumor activity with a improvement in overall survival in mCRPC carrying somatic and/or germline alterations of HHR. Germline mutations are tested on peripheral blood samples using DNA extracted from peripheral blood leukocytes, while the somatic alterations are assessed by extracting DNA from a tumor tissue sample. However, each of these genetic tests have some limitations: the somatic tests are related to the sample availability and tumor heterogeneity, while the germline testing are mainly related to the inability to detect somatic HRR mutations. Therefore, the liquid biopsy, a non-invasive and easily repeatable test compared to tissue test, could identified somatic mutation detected on the circulating tumor DNA (ctDNA) extracted from a plasma. This approach should better represent the heterogeneity of the tumor compared to the primary biopsy and maybe helpful in monitoring the onset of potential mutations involved in treatment resistance. Furthermore, ctDNA may inform about timing and potential cooperation of multiple driver genes aberration guiding the treatment options in patients with mCRPC. However, the clinical use of ctDNA test in prostate cancer compared to blood and tissue testing are currently very limited. In this review, we summarize the current therapeutic indications in prostate cancer patients with DDR deficiency, the recommendation for germline and somatic-genomic testing in advanced PC and the advantages of the use liquid biopsy in clinical routine for mCRPC.

Who and how, DNA sensors in NETs-driven inflammation

During infections, neutrophil extracellular traps act like a meshwork of molecules that captures microbes. In contrast, during sterile inflammation the presence of NETs is usually associated with tissue damage and uncontrolled inflammation. In this context, DNA acts both as activator of NETs formation and immunogenic molecule fueling inflammation within the injured tissue microenvironment. Pattern recognition receptors that specifically bind to and get activated by DNA such as Toll-like receptor-9 (TLR9), cyclic GMP-AMP synthase (cGAS), Nod-like receptor protein 3 (NLRP3) and Absence in Melanoma-2 (AIM2) have been reported to play a role in NETs formation and detection. However, how these DNA sensors contribute to NETs-driven inflammation is not well understood. Whether these DNA sensors have unique roles or on the contrary they are mostly redundant is still elusive. In this review, we summarize the known contribution of the above DNA sensors to the formation and detection of NETs in the context of sterile inflammation. We also highlight scientific gaps needed to be addressed and propose future direction for therapeutic targets.

Peptidylarginine deiminase 4 deficiency in bone marrow cells prevents plaque progression without decreasing atherogenic inflammation in apolipoprotein E-knockout mice

INTRODUCTION

Despite multiple studies in the past, the role of peptidylarginine deiminase 4 (PAD4) in atherosclerosis is currently insufficiently understood. In this regard, PAD4 deletion or inhibition of enzymatic activity was previously reported to ameliorate disease progression and inflammation. Besides, strong influence of neutrophil extracellular traps (NETs) on atherosclerosis burden has been proposed. Here, we studied the role of PAD4 for atherogenesis and plaque progression in a mouse model of atherosclerosis.

METHODS AND RESULTS

Lethally irradiated ApoE -/- mice were reconstituted with ApoE -/-/Pad4 -/- bone marrow cells and fed a high-fat diet (HFD) for 4 and 10 weeks, respectively. PAD4 deficiency did not prevent the development of atherosclerotic lesions after 4 weeks of HFD. However, after 10 weeks of HFD, mice with bone marrow cells-restricted PAD4 deficiency displayed significantly reduced lesion size, impaired lipid incorporation, decreased necrotic core area and less collagen when compared to ApoE -/- bone marrow-transplanted mice as demonstrated by histological staining. Moreover, flow cytometric analysis and quantitative real-time PCR revealed different macrophage subsets in atherosclerotic lesions and higher inflammatory response in these mice, as reflected by increased content of M1-like macrophages and upregulated aortic expression of the pro-inflammatory genes CCL2 and iNOS. Notably, diminished oxLDL uptake by in vitro-polarized M1-like macrophages was evidenced when compared to M2-like cells.

CONCLUSION

These results suggest that pharmacological inhibition of PAD4 may impede lipid accumulation and lesion progression despite no beneficial effects on vascular inflammation.

Concomitant Intra-Aortic Balloon Pumping Significantly Reduces Left Ventricular Pressure during Central Veno-Arterial Extracorporeal Membrane Oxygenation-Results from a Large Animal Model

(1) Introduction: Simultaneous ECMO and IABP therapy is frequently used. Haemodynamic changes responsible for the success of the concomitant mechanical circulatory support system approach are rarely investigated. In a large-animal model, we analysed haemodynamic parameters before and during ECMO therapy, comparing central and peripheral ECMO circulation with and without simultaneous IABP support. (2) Methods: Thirty-three female pigs were divided into five groups: (1) SHAM, (2) (peripheral)ECMO(-)IABP, (3) (p)ECMO(+)IABP, (4) (central)ECMO(-)IABP, and (5) (c)ECMO(+)IABP. Pigs were cannulated in accordance with the group and supported with ECMO (±IABP) for 10 h. Systemic haemodynamics, cardiac index (CI), and coronary and carotid artery blood flow were determined before, directly after, and at five and ten hours on extracorporeal support. Systemic inflammation (IL-6; IL-10; TNFα; IFNγ), immune response (NETs; cf-DNA), and endothelial injury (ET-1) were also measured. (3) Results: IABP support during antegrade ECMO circulation led to a significant reduction of left ventricular pressure in comparison to retrograde flow in (p)ECMO(-)IABP and (p)ECMO(+)IABP. Blood flow in the left anterior coronary and carotid artery was not affected by extracorporeal circulation. (4) Conclusions: Concomitant central ECMO and IABP therapy leads to significant reduction of intracavitary cardiac pressure, reduces cardiac work, and might therefore contribute to improved recovery in ECMO patients.

Nuclear Cell-Free DNA Predicts Adverse Events After Pediatric Cardiothoracic Surgery

BACKGROUND

Preoperative risk stratification in cardiac surgery includes patient and procedure factors that are used in clinical decision-making. Despite these tools, unidentified factors contribute to variation in outcomes. Identification of latent physiologic risk factors may strengthen predictive models. Nuclear cell-free DNA (ncfDNA) increases with tissue injury and drops to baseline levels rapidly. The goal of this investigation is to measure and to observe ncfDNA kinetics in children undergoing heart operations with cardiopulmonary bypass (CPB), linking biomarkers, organ dysfunction, and outcomes.

METHODS

This is a prospective observational study of 116 children <18 years and >3 kg undergoing operations with CPB. Plasma ncfDNA samples were collected and processed in a stepwise manner at predefined perioperative time points. The primary outcome measure was occurrence of postoperative cardiac arrest or extracorporeal membrane oxygenation.

RESULTS

Data were available in 116 patients (median age, 0.9 years [range, 0-17.4 years]; median weight, 7.8 kg [range, 3.2-98 kg]). The primary outcome was met in 6 of 116 (5.2%). Risk of primary outcome was 2% with ncfDNA <20 ng/mL and 33% with ncfDNA >20 ng/mL (odds ratio, 25; CI, 3.96-158; P = .001). Elevated ncfDNA was associated with fewer hospital-free days (P < .01).

CONCLUSIONS

This study analyzes ncfDNA kinetics in children undergoing operations with CPB for congenital heart disease. Elevated preoperative ncfDNA is strongly associated with postoperative arrest and extracorporeal membrane oxygenation. Further studies are needed to validate this technology as a tool to predict morbidity in children after cardiac surgical procedures.

Correlation between Neutrophil Extracellular Traps (NETs) Expression and Primary Graft Dysfunction Following Human Lung Transplantation

Primary graft dysfunction (PGD) is characterized by alveolar epithelial and vascular endothelial damage and inflammation, lung edema and hypoxemia. Up to one-third of recipients develop the most severe form of PGD (Grade 3; PGD3). Animal studies suggest that neutrophils contribute to the inflammatory process through neutrophil extracellular traps (NETs) release (NETosis). NETs are composed of DNA filaments decorated with granular proteins contributing to vascular occlusion associated with PGD. The main objective was to correlate NETosis in PGD3 (n = 9) versus non-PGD3 (n = 27) recipients in an exploratory study. Clinical data and blood samples were collected from donors and recipients pre-, intra- and postoperatively (up to 72 h). Inflammatory inducers of NETs' release (IL-8, IL-6 and C-reactive protein [CRP]) and components (myeloperoxidase [MPO], MPO-DNA complexes and cell-free DNA [cfDNA]) were quantified by ELISA. When available, histology, immunohistochemistry and immunofluorescence techniques were performed on lung biopsies from donor grafts collected during the surgery to evaluate the presence of activated neutrophils and NETs. Lung biopsies from donor grafts collected during transplantation presented various degrees of vascular occlusion including neutrophils undergoing NETosis. Additionally, in recipients intra- and postoperatively, circulating inflammatory (IL-6, IL-8) and NETosis biomarkers (MPO-DNA, MPO, cfDNA) were up to 4-fold higher in PGD3 recipients compared to non-PGD3 (p = 0.041 to 0.001). In summary, perioperative elevation of NETosis biomarkers is associated with PGD3 following human lung transplantation and these biomarkers might serve to identify recipients at risk of PGD3 and initiate preventive therapies.

A prospective cohort study of dynamic cell-free DNA elevation during cardiac surgery with cardiopulmonary bypass

Cardiac surgery and cardiopulmonary bypass (CPB) are associated with a systemic inflammatory reaction that occasionally induces a life-threatening organ dysfunction caused by the dysregulated host response to the damage-associated molecular patterns (DAMPs). In severe inflammation, cell-free DNA (cfDNA) and histones are released by inflammatory cells and damaged tissue and act as DAMPs. We sought to characterize the changes in circulating cell-free DNA (cfDNA) levels during CPB. Primary outcomes were renal failure, ventilation time (>18 hr), length of stay (LOS) in the intensive care unit (ICU) (>48hr), hospital LOS (>15 days), and death. We looked for associations with blood tests and comparison to standard scores. In a prospective cohort study, we enrolled 71 patients undergoing non-emergent coronary artery bypass grafting. Blood was drawn at baseline, 20 and 40 minutes on CPB, after cross-clamp removal, and 30 minutes after chest closure. cfDNA was measured by our fast fluorescent method. Baseline cfDNA levels [796 (656–1063) ng/ml] increased during surgery, peaked after cross-clamp removal [2403 (1981–3357) ng/ml] and returned to baseline at recovery. The difference in cfDNA from 20 to 40 minutes on CPB (ΔcfDNA 40–20) inversely correlated with peripheral vascular disease (PVD), longer ventilation time, and longer ICU and hospital length of stay (LOS). Receiver operating characteristic (ROC) curve of ΔcfDNA 40–20 for long ICU-LOS (>48hr) was with an area under the curve (AUC) of 0.738 (p = 0.022). ROC AUC of ΔcfDNA 40–20 to long Hospital LOS (>15 days) was 0.787 (p = 0.006). Correction for time on CPB in a multivariate logistic regression model improved ROC-AUC to 0.854 (p = 0.003) and suggests that ΔcfDNA 40–20 is an independent risk factor. To conclude, of measured parameters, including STS and Euroscore, the predictive power of ΔcfDNA 40–20 was the highest. Thus, measurement of ΔcfDNA 40–20 may enable early monitoring of patients at higher risk. Further studies on the mechanism behind the negative association of ΔcfDNA 40–20 with PVD and outcomes are warranted.

Elevated nuclear and mitochondrial cell-free deoxyribonucleic acid measurements are associated with death after infant cardiac surgery

OBJECTIVES

Mortality rates following pediatric cardiac surgery with cardiopulmonary bypass have declined over decades, but have plateaued in recent years. This is in part attributable to persistent issues with postoperative global inflammation and myocardial dysfunction, commonly manifested by systemic inflammatory response syndrome and low cardiac output syndrome, respectively. Quantified cell-free DNA (cfDNA), of nuclear or mitochondrial origin, has emerged as a biomarker for both inflammation and myocardial injury. Recent data suggest that nuclear cfDNA (ncfDNA) may quantify inflammation, whereas mitochondrial cfDNA (mcfDNA) may correlate with the degree of myocardial injury. We hypothesize that threshold levels of ncfDNA and mcfDNA can be established that are sensitive and specific for postoperative mortality mediated through independent pathways, and that association will be enhanced with combined analysis.

METHODS

Prospective observational study of infants younger than age 1 year undergoing planned surgery with cardiopulmonary bypass. The study received institutional review board approval. Samples were drawn before skin incision, immediately after completion of cardiopulmonary bypass, and subsequently at predetermined intervals postoperatively. Association of early postoperative ncfDNA and mcfDNA levels with mortality were assessed by logistic regression with cut-points chosen by receiving operating characteristic curve exploration.

RESULTS

Data were available in 59 patients. Median age and weight were 122 days (interquartile range, 63-154 days) and 4.9 kg (interquartile range, 3.9-6.2 kg). Median STAT category was 3 (interquartile range, 1-4). The primary outcome of death was met in 3 out of 59 (5%). Combined analysis of ncfDNA and mcfDNA levels at 12 hours after the initiation of cardiopulmonary bypass with death at a threshold of 50 ng/mL ncfDNA and 17 copies/μL mcfDNA yielded 100% sensitivity and negative predictive value. The specificity (91%) and positive predictive value (38%) increased through combined analysis compared with univariate analysis. Combined analysis exhibited high specificity (93%) and negative predictive value (78%) for prolonged (>30 postoperative days) hospitalization.

CONCLUSIONS

Combined analysis of early postoperative ncfDNA and mcfDNA can stratify risk of mortality and prolonged hospitalization following infant cardiac surgery. Evaluation of both ncfDNA and mcfDNA to identify states of generalized inflammation and myocardial injury may allow for targeted interventions and improved outcomes.

Tumor regionalization after surgery: Roles of the tumor microenvironment and neutrophil extracellular traps

Surgery is unanimously regarded as the primary strategy to cure solid tumors in the early stages but is not always used in advanced cases. However, tumor surgery must be carefully considered because the risk of metastasis could be increased by the surgical procedure. Tumor surgery may result in a deep wound, which induces many biological responses favoring tumor metastasis. In particular, NETosis, which is the process of forming neutrophil extracellular traps (NETs), has received attention as a risk factor for surgery-induced metastasis. To reduce cancer mortality, researchers have made efforts to prevent secondary metastasis after resection of the primary tumor. From this point of view, a better understanding of surgery-induced metastasis might provide new strategies for more effective and safer surgical approaches. In this paper, recent insights into the surgical effects on metastasis will be reviewed. Moreover, in-depth opinions about the effects of NETs on metastasis will be discussed.

Therapies that limit the formation of web-like structures formed by white cells known as neutrophils may lower the risk of cancer spread (metastasis) following surgical tumor removal. Removing solid tumors remains a key cancer treatment, but in some cases surgery itself increases the risk of metastasis. Jong-Wan Park at Seoul National University, South Korea, and co-workers reviewed current understanding of metastasis following surgery. Surgical removal destroys the architecture supporting cancer cells but this can release tumor cells into blood vessels. The stress of deep wounds also affects immune responses, most notably neutrophil extracellular traps (NETs), web-like structures formed by neutrophils to trap and kill pathogens. NETs have previously been implicated in metastasis. In a post-surgical environment enriched in neutrophils and pro-inflammatory cytokines, NET formation may help cancer cells thrive, promoting metastasis.

Circulating cell free DNA and citrullinated histone H3 as useful biomarkers of NETosis in endometrial cancer

BACKGROUND

Cancer mortality is mainly caused by organ failure and thrombotic events. It has been demonstrated that NETosis, a chromatin release mechanism implemented by neutrophils, may contribute to these lethal systemic effects. Our aim was to investigate NETosis biomarkers in endometrial cancer (EC).

METHODS

The experiments were conducted on 21 healthy subjects (HS) with no gynecological conditions, and on 63 EC patients. To assess the presence of NETosis features, IHC and IF was performed using antibodies against citrullinated histone H3 (citH3), neutrophil elastase (NE) and histone 2B. Serum levels of cell free DNA (cfDNA), cell free mitochondrial DNA (cfmtDNA) and citH3 were measured by qPCR using one microliter of deactivated serum, and by ELISA assay respectively. Fragmentation pattern of serum cfDNA was analyzed using the Agilent 2100 Bioanalyzer and High Sensitivity DNA Chips. Receiver operating characteristic (ROC) analysis was used to identify a cut off for cfDNA and cfmtDNA values able to discriminate between ECs and HSs. Correlation analysis and multiple correspondence analysis (MCA) between cfDNA, mtcfDNA, citH3 and blood parameters were used to identify the potential association among serum parameters in EC grades.

RESULTS

We demonstrated the presence of NETosis features in tissues from all EC grades. Serum cfDNA and cfmtDNA levels discriminate ECs from HSs and a direct correlation between citH3 and cfDNA content and an inverse correlation between cfmtDNA and citH3 in EC sera was observed, not detectable in HSs. MCA indicates cfDNA, cfmtDNA and citH3 as features associated to G1 and G2 grades. A correlation between increased levels of cfDNA, citH3 and inflammation features was found. Finally, serum nucleosomal cfDNA fragmentation pattern varies in EC sera and correlates with increased levels of cfDNA, citH3, lymphocytes and fibrinogen.

CONCLUSION

Our data highlight the occurrence of NETosis in EC and indicate serum cfDNA and citH3 as noninvasive biomarkers of tumor-induced systemic effects in endometrial cancer.

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.

Association of neutrophil extracellular traps with the production of circulating DNA in patients with colorectal cancer

We postulate that a significant part of circulating DNA (cirDNA) originates in the degradation of neutrophil extracellular traps (NETs). In this study, we examined the plasma level of two markers of NETs (myeloperoxidase (MPO) and neutrophil elastase (NE)), as well as cirDNA levels in 219 patients with a metastatic colorectal cancer (mCRC), and in 114 healthy individuals (HI). We found that in patients with mCRC the content of these analytes was (i) highly correlated, and (ii) all statistically different (p < 0.0001) than in HI (N = 114). These three NETs markers may readily distinguish between patients with mCRC from HI, (0.88, 0.86, 0.84, and 0.95 AUC values for NE, MPO, cirDNA, and NE + MPO + cirDNA, respectively). Concomitant analysis of anti-phospholipid (anti-cardiolipin), NE, MPO, and cirDNA plasma concentrations in patients with mCRC might have value for thrombosis prevention, and suggested that NETosis may be a critical factor in the immunological response/phenomena linked to tumor progression.

•

NETs markers correlate with cirDNA amounts in patients with mCRC not in healthy subjects

•

Quantifying NETs markers and cirDNA could distinguish mCRC from healthy subjects

•

Analysis of NETs markers, cirDNA, and aPL may have value for thrombosis prevention

•

A strong fraction of cirDNA concentration could be derived from NETs in patients with mCRC

NETosis in ischemic/reperfusion injuries: An organ-based review

Neutrophil extracellular trap (NETosis), the web-like structures induced by neutrophil death, is an important inflammatory mechanism of the immune system leading to reactive oxygen species production/coagulopathy, endothelial dysfunction, atherosclerosis, and ischemia. NETosis exerts its role through different mechanisms such as triggering Toll-like receptors, inflammatory cytokines, platelet aggregation, neutrophil activation/infiltration, and vascular impairment. NETosis plays a key role in the prognosis of coronary artery disease, ischemic injury of kidney, lung, gastrointestinal tract and skeletal muscles. In this review, we explored the molecular mechanisms involved in NETosis, and ischemic/reperfusion injuries in body organs.

Properties and Application of Cell-Free DNA as a Clinical Biomarker

Biomarkers are valuable tools in clinical practice. In 2001, the National Institutes of Health (NIH) standardized the definition of a biomarker as a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention. A biomarker has clinical relevance when it presents precision, standardization and reproducibility, suitability to the patient, straightforward interpretation by clinicians, and high sensitivity and/or specificity by the parameter it proposes to identify. Thus, serum biomarkers should have advantages related to the simplicity of the procedures and to the fact that venous blood collection is commonplace in clinical practice. We described the potentiality of cfDNA as a general clinical biomarker and focused on endothelial dysfunction. Circulating cell-free DNA (cfDNA) refers to extracellular DNA present in body fluid that may be derived from both normal and diseased cells. An increasing number of studies demonstrate the potential use of cfDNA as a noninvasive biomarker to determine physiologic and pathologic conditions. However, although still scarce, increasing evidence has been reported regarding using cfDNA in cardiovascular diseases. Here, we have reviewed the history of cfDNA, its source, molecular features, and release mechanism. We also show recent studies that have investigated cfDNA as a possible marker of endothelial damage in clinical settings. In the cardiovascular system, the studies are quite new, and although interesting, stronger evidence is still needed. However, some drawbacks in cfDNA methodologies should be overcome before its recommendation as a biomarker in the clinical setting.

Neutrophil extracellular traps in inflammatory bowel diseases: Implications in pathogenesis and therapeutic targets

Crohn's disease (CD) and ulcerative colitis (UC) are the two main forms of inflammatory bowel disease (IBD). Among the various immune cells involved in IBD, neutrophils are the first to infiltrate and appear to contribute to the impairment of the epithelial barrier, destruction of tissues by oxidative and proteolytic damage, as well as to the perpetuation of inflammation by the release of cytokines and chemokines associated with pro-inflammatory effects. In addition to basic effector mechanisms, such as phagocytosis and chemotaxis, neutrophils can also form extracellular traps (NETs), which is made up of a mesh-like structure - which contains its chromatin (DNA + histones) together with granules and enzymes, such as myeloperoxidase (MPO) and neutrophilic elastase (NE) - and that acts as a trap that can result in the death of extracellular pathogens and/or can promote tissue damage. Recent evidence indicates that NETs also play an important and significant role in the pathogenesis of IBD. Previous studies have reported increased levels of NETs in tissue and serum samples from patients with IBD, as well as in experimental colitis. In this review, we discuss current knowledge about the formation of NETs and their role in the pathophysiology of IBD, pointing out potential mechanisms by which NETs promote tissue damage, as well as their involvement in complications associated with IBD. In addition, we propose potential targets for therapy to regulate the production of NETs, making it possible to expand the current spectrum of therapies for IBD.

Hepatitis C Virus Clearance by Direct-Acting Antivirals Agents Improves Endothelial Dysfunction and Subclinical Atherosclerosis: HEPCAR Study

INTRODUCTION

Hepatitis C virus (HCV) infection has been related to increased cardiovascular (CV) risk. The aim of this study was to analyze the impact of sustained virological response (SVR) on endothelial dysfunction and subclinical atherosclerosis in patients with hepatitis C virus treated with direct-acting antiviral agents.

METHODS

A total of 114 patients were prospectively recruited and underwent CV risk assessment including (i) endothelial dysfunction determined through laser Doppler flowmetry and (ii) subclinical atherosclerosis, elucidated by the ankle-brachial index (ABI). Atherogenic lipid profile (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides); markers of oxidative stress (oxidized low-density lipoprotein antibodies [OLAbs]), soluble markers of adhesion (vascular cell adhesion molecule [VCAM], e-selectin, and soluble markers of angiogenesis; and vascular endothelial growth factor, endothelial [EMPs] and platelet [PMPs] apoptotic microparticles, and cell-free DNA [cfDNA]) were measured. All determinations were performed at baseline, 12 weeks (SVR time), and 1 year after treatment.

RESULTS

In patients with endothelial dysfunction, area of hyperemia improved after virus clearance (P = 0.013) and was related to significant decrease in VCAM, e-selectin (P < 0.001), and cfDNA (P = 0.017) and to increased OLAb levels (P = 0.001). In patients with subclinical atherosclerosis at baseline, a significantly improved ABI was seen after HCV clearance (P < 0.001). Levels of both EMPs and PMPs also decreased after SVR and at follow-up (P = 0.006 and P = 0.002, respectively).

DISCUSSION

HCV clearance improved not only liver function but also endothelial dysfunction and subclinical atherosclerosis promoted by decrease in levels of VCAM, e-selectin, cfDNA, and PMPs and EMPs.

Perioperative Neutrophil-Lymphocyte Ratio Predicts Mortality After Cardiac Surgery: Systematic Review and Meta-Analysis

OBJECTIVES

Neutrophil-lymphocyte ratio (NLR) is an inflammatory biomarker that has been evaluated across a variety of surgical disciplines and is widely predictive of poor postoperative outcome, but its value in cardiac surgery is unclear. The authors did this systematic review and meta-analysis to determine the impact of elevated perioperative NLR on survival after cardiac surgery.

DESIGN

Systematic review and meta-analysis of study-level data.

SETTING

Multiple hospitals involved in an international pool of studies.

PARTICIPANTS

Adults undergoing cardiac surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The authors searched multiple databases from inception until November 2020. They generated summary hazard ratios (HR) and odds ratios (OR) for the association of elevated preoperative NLR with long-term and short-term mortality following cardiac surgery. They separately reported on elevated postoperative NLR. Between-study heterogeneity was explored using metaregression. The authors included 12 studies involving 13,262 patients undergoing cardiac surgery. Elevated preoperative NLR was associated with worse long-term (>30 days) (hazard ratio [HR] 1.56; 95% CI [confidence interval], 1.18-2.06; 8 studies) and short-term (<30 days) mortality (OR 3.18; 95% CI, 1.90-5.30; 7 studies). One study reported the association of elevated postoperative NLR with long-term mortality (HR 8.58; 95% CI, 2.55-28.85). There was considerable between-study heterogeneity for the analysis of long-term mortality (I² statistic 94.39%), which mostly was explained by study-level variables, such as the number of variables adjusted for by included studies and how many of these significantly increased the risk of long-term mortality, high risk of bias, and number of study centers, as well as participant level factors, such as average participant age and hypertension prevalence.

CONCLUSIONS

Perioperative NLR is an independent predictor of short-term and long-term postoperative mortality following cardiac surgery. Further research is required to determine which patient-level factors modify the prognostic value of NLR and to evaluate its role in routine clinical practice.

Circulating Tumor DNA Testing for Homology Recombination Repair Genes in Prostate Cancer: From the Lab to the Clinic

Approximately 23% of metastatic castration-resistant prostate cancers (mCRPC) harbor deleterious aberrations in DNA repair genes. Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) therapy has shown improvements in overall survival in patients with mCRPC who harbor somatic and/or germline alterations of homology recombination repair (HRR) genes. Peripheral blood samples are typically used for the germline mutation analysis test using the DNA extracted from peripheral blood leucocytes. Somatic alterations can be assessed by extracting DNA from a tumor tissue sample or using circulating tumor DNA (ctDNA) extracted from a plasma sample. Each of these genetic tests has its own benefits and limitations. The main advantages compared to the tissue test are that liquid biopsy is a non-invasive and easily repeatable test with the value of better representing tumor heterogeneity than primary biopsy and of capturing changes and/or resistance mutations in the genetic tumor profile during disease progression. Furthermore, ctDNA can inform about mutation status and guide treatment options in patients with mCRPC. Clinical validation and test implementation into routine clinical practice are currently very limited. In this review, we discuss the state of the art of the ctDNA test in prostate cancer compared to blood and tissue testing. We also illustrate the ctDNA testing workflow, the available techniques for ctDNA extraction, sequencing, and analysis, describing advantages and limits of each techniques.

Total and endothelial cell-derived cell-free DNA in blood plasma does not change during menstruation

Assays measuring cell-free DNA (cfDNA) in blood have widespread potential in modern medicine. However, a comprehensive understanding of cfDNA dynamics in healthy individuals is required to assist in the design of assays that maximise the signal driven by pathological changes, while excluding fluctuations that are part of healthy physiological processes. The menstrual cycle involves major remodelling of endometrial tissue and associated apoptosis, yet there has been little investigation of the impact of the menstrual cycle on cfDNA levels. Paired plasma samples were collected from 40 healthy women on menstruating (M) and non-menstruating (NM) days of their cycle. We measured total cfDNA by targeting ALU repetitive sequences and measured endothelial-derived cfDNA by methylation-specific qPCR targeting an endothelium-unique unmethylated CDH5 DNA region. CfDNA integrity and endothelial cfDNA concentration, but not total cfDNA, are consistent across time between NM and M. No significant changes in total (ALU-115 p = 0.273; ALU-247 p = 0.385) or endothelial cell specific (p = 0.301) cfDNA were observed, leading to the conclusion that menstrual status at the time of diagnostic blood collection should not have a significant impact on the quantitation of total cfDNA and methylation-based cancer assays.

Role of biomaterials in the diagnosis, prevention, treatment, and study of corona virus disease 2019 (COVID-19)

Recently emerged novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the resulting corona virus disease 2019 (COVID-19) led to urgent search for methods to prevent and treat COVID-19. Among important disciplines that were mobilized is the biomaterials science and engineering. Biomaterials offer a range of possibilities to develop disease models, protective, diagnostic, therapeutic, monitoring measures, and vaccines. Among the most important contributions made so far from this field are tissue engineering, organoids, and organ-on-a-chip systems, which have been the important frontiers in developing tissue models for viral infection studies. Also, due to low bioavailability and limited circulation time of conventional antiviral drugs, controlled and targeted drug delivery could be applied alternatively. Fortunately, at the time of writing this paper, we have two successful vaccines and new at-home detection platforms. In this paper, we aim to review recent advances of biomaterial-based platforms for protection, diagnosis, vaccination, therapeutics, and monitoring of SARS-CoV-2 and discuss challenges and possible future research directions in this field.

Ultrasensitive circulating tumor DNA analysis enables precision medicine: experimental workflow considerations

Introduction: Circulating tumor DNA (ctDNA) has become a relevant biomarker in cancer management, allowing tumor assessment through analysis of minimally invasive liquid biopsies. Applications include screening, diagnostics, monitoring of treatment efficacy and detection of minimal residual disease as well as relapse. The potential of ctDNA analysis is significant, but several biological and technical challenges need to be addressed before widespread clinical implementation.Areas covered: Several clinical applications where ctDNA analysis may be beneficial require detection of individual DNA molecules. Consequently, to acquire accurate and informative data the entire workflow from sampling to final data interpretation needs to be optimized. In this review, we discuss the biological and technical challenges of ctDNA analysis and how preanalytical and analytical approaches affect different cancer applications.Expert opinion: While numerous studies have demonstrated the potential of using ctDNA in cancer applications, yet few reports about true clinical utility exist. Despite encouraging data, the sensitivity of ctDNA analyses, i.e. the probability to detect presence of cancer in liquid biopsies, is still an issue. Analysis of multiple mutations in combination with simultaneous assessment of other analytes is one solution. Improved standardization and guidelines will also facilitate the introduction of ctDNA analysis into clinical routine.

Innate Receptor Activation Patterns Involving TLR and NLR Synergisms in COVID-19, ALI/ARDS and Sepsis Cytokine Storms: A Review and Model Making Novel Predictions and Therapeutic Suggestions

Severe COVID-19 is characterized by a “cytokine storm”, the mechanism of which is not yet understood. I propose that cytokine storms result from synergistic interactions among Toll-like receptors (TLR) and nucleotide-binding oligomerization domain-like receptors (NLR) due to combined infections of SARS-CoV-2 with other microbes, mainly bacterial and fungal. This proposition is based on eight linked types of evidence and their logical connections. (1) Severe cases of COVID-19 differ from healthy controls and mild COVID-19 patients in exhibiting increased TLR4, TLR7, TLR9 and NLRP3 activity. (2) SARS-CoV-2 and related coronaviruses activate TLR3, TLR7, RIG1 and NLRP3. (3) SARS-CoV-2 cannot, therefore, account for the innate receptor activation pattern (IRAP) found in severe COVID-19 patients. (4) Severe COVID-19 also differs from its mild form in being characterized by bacterial and fungal infections. (5) Respiratory bacterial and fungal infections activate TLR2, TLR4, TLR9 and NLRP3. (6) A combination of SARS-CoV-2 with bacterial/fungal coinfections accounts for the IRAP found in severe COVID-19 and why it differs from mild cases. (7) Notably, TLR7 (viral) and TLR4 (bacterial/fungal) synergize, TLR9 and TLR4 (both bacterial/fungal) synergize and TLR2 and TLR4 (both bacterial/fungal) synergize with NLRP3 (viral and bacterial). (8) Thus, a SARS-CoV-2-bacterium/fungus coinfection produces synergistic innate activation, resulting in the hyperinflammation characteristic of a cytokine storm. Unique clinical, experimental and therapeutic predictions (such as why melatonin is effective in treating COVID-19) are discussed, and broader implications are outlined for understanding why other syndromes such as acute lung injury, acute respiratory distress syndrome and sepsis display varied cytokine storm symptoms.

Long-acting nanoparticulate DNase-1 for effective suppression of SARS-CoV-2-mediated neutrophil activities and cytokine storm

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new strain of coronavirus not previously identified in humans. Globally, the number of confirmed cases and mortality rates of coronavirus disease 2019 (COVID-19) have risen dramatically. Currently, there are no FDA-approved antiviral drugs and there is an urgency to develop treatment strategies that can effectively suppress SARS-CoV-2-mediated cytokine storms, acute respiratory distress syndrome (ARDS), and sepsis. As symptoms progress in patients with SARS-CoV-2 sepsis, elevated amounts of cell-free DNA (cfDNA) are produced, which in turn induce multiple organ failure in these patients. Furthermore, plasma levels of DNase-1 are markedly reduced in SARS-CoV-2 sepsis patients. In this study, we generated recombinant DNase-1-coated polydopamine-poly(ethylene glycol) nanoparticulates (named long-acting DNase-1), and hypothesized that exogenous administration of long-acting DNase-1 may suppress SARS-CoV-2-mediated neutrophil activities and the cytokine storm. Our findings suggest that exogenously administered long-acting nanoparticulate DNase-1 can effectively reduce cfDNA levels and neutrophil activities and may be used as a potential therapeutic intervention for life-threatening SARS-CoV-2-mediated illnesses.

Bioinspired DNase-I-Coated Melanin-Like Nanospheres for Modulation of Infection-Associated NETosis Dysregulation

The current outbreak of the beta-coronavirus (beta-Cov) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began in December 2019. No specific antiviral treatments or vaccines are currently available. A recent study has reported that coronavirus disease 2019 (COVID-19), the disease caused by SARS-CoV-2 infection, is associated with neutrophil-specific plasma membrane rupture, and release excessive neutrophil extracellular traps (NETs) and extracellular DNAs (eDNAs). This mechanism involves the activation of NETosis, a neutrophil-specific programmed cell death, which is believed to play a crucial role in COVID-19 pathogenesis. Further progression of the disease can cause uncontrolled inflammation, leading to the initiation of cytokine storms, acute respiratory distress syndrome (ARDS), and sepsis. Herein, it is reported that DNase-I-coated melanin-like nanospheres (DNase-I pMNSs) mitigate sepsis-associated NETosis dysregulation, thereby preventing further progression of the disease. Recombinant DNase-I and poly(ethylene glycol) (PEG) are used as coatings to promote the lengthy circulation and dissolution of NET structure. The data indicate that the application of bioinspired DNase-I pMNSs reduce neutrophil counts and NETosis-related factors in the plasma of SARS-CoV-2 sepsis patients, alleviates systemic inflammation, and attenuates mortality in a septic mouse model. Altogether, the findings suggest that these nanoparticles have potential applications in the treatment of SARS-CoV-2-related illnesses and other beta-CoV-related diseases.

Circulating cell-free DNA improves the molecular characterisation of Ph-negative myeloproliferative neoplasms

Genetic studies in patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) are essential to establish the correct diagnosis and to optimise their management. Recently, it has been demonstrated that it is possible to detect molecular alterations analysing cell-free DNA (cfDNA) in plasma samples, which is known as liquid biopsy. We have assessed the molecular profile of a cohort of 107 MPN patients [33 polycythaemia vera (PV), 56 essential thrombocythaemia (ET), 14 primary myelofibrosis (PMF) and 4 unclassifiable MPN] by next-generation sequencing (NGS) using cfDNA and paired granulocyte DNA. A high concentration of cfDNA in plasma was observed in patients with high molecular complexity, in MPL-mutated cases, and in PMF patients. Targeted sequencing of cfDNA showed a comparable mutational profile (100% accuracy) to the one obtained in granulocytic DNA and a strong correlation was observed between the variant allele frequency (VAF) of gene mutations in both DNA sources. The median VAF detected in cfDNA (29·0%; range: 0·95-91·73%) was significantly higher than the VAF detected in granulocytes (median 25·2%; range: 0·10-95·5%), especially for MPL mutations (44·3% vs. 22·5%). In conclusion, our data support the use of cfDNA as a fast, sensitive and accurate strategy for performing molecular characterisation of MPN patients.

Phenotypes from cell-free DNA

Cell-free DNA (cfDNA) has the potential to enable non-invasive detection of disease states and progression. Beyond its sequence, cfDNA also represents the nucleosomal landscape of cell(s)-of-origin and captures the dynamics of the epigenome. In this review, we highlight the emergence of cfDNA epigenomic methods that assess disease beyond the scope of mutant tumour genotyping. Detection of tumour mutations is the gold standard for sequencing methods in clinical oncology. However, limitations inherent to mutation targeting in cfDNA, and the possibilities of uncovering molecular mechanisms underlying disease, have made epigenomics of cfDNA an exciting alternative. We discuss the epigenomic information revealed by cfDNA, and how epigenomic methods exploit cfDNA to detect and characterize cancer. Future applications of cfDNA epigenomic methods to act complementarily and orthogonally to current clinical practices has the potential to transform cancer management and improve cancer patient outcomes.

Circulating cell-free DNA level predicts all-cause mortality independent of other predictors in the Health 2000 survey

Increased levels of circulating cell-free DNA (cf-DNA) are associated with and predict poor health outcomes. However, its predictive ability for mortality in population-based samples remains understudied. We analysed the capability of cf-DNA to predict all-cause mortality and assessed whether it adds predictive value on top of the other risk factors in the Health 2000 survey (n = 1,257, 46–76 years of age, 15-years-follow-up, 18% deceased). When analysed in a multivariate model with the other factors that independently predicted mortality in the sample (age, gender, self-rated health, smoking and plasma levels of glucose and adiponectin), increases in cf-DNA levels were associated with increased risk of mortality (hazard ratio [HR] for 0.1 µg increase in cf-DNA: 1.017, 95% confidence interval [CI] 1.008–1.026, p = 0.0003). Inclusion of cf-DNA in the model improved the model fit and discrimination. Stratifying the analysis by cardiovascular disease (CVD) status indicated that cf-DNA predicted mortality equally well in individuals with (HR 1.018, 95% CI 1.008–1.026, p = 0.002) and without (HR 1.018, 95% CI 1.001–1.035, p = 0.033) CVD. In conclusion, our study indicates that cf-DNA level predicts mortality in middle-aged and older individuals, also among those with established CVD, and adds significant value to mortality prediction. Our results thus underscore the role of cf-DNA as a viable marker of health.

Endothelial colony-forming cells reduced the lung injury induced by cardiopulmonary bypass in rats

Background

Cardiopulmonary bypass (CPB) results in severe lung injury via inflammation and endothelial injury. The aim of this study was to evaluate the effect of endothelial colony-forming cells (ECFCs) on lung injury in rats subjected to CPB.

Methods

Thirty-two rats were randomized into the sham, CPB, CPB/ECFC and CPB/ECFC/L-NIO groups. The rats in the sham group received anaesthesia, and the rats in the other groups received CPB. The rats also received PBS, ECFCs and L-NIO-pre-treated ECFCs. After 24 h of CPB, pulmonary capillary permeability, including the PaO₂/FiO₂ ratio, protein levels in bronchoalveolar lavage fluid (BALF) and lung tissue wet/dry weight were evaluated. The cell numbers and cytokines in BALF and peripheral blood were tested. Endothelial injury, lung histological injury and apoptosis were assessed. The oxidative stress response and apoptosis-related proteins were analysed.

Results

After CPB, all the data deteriorated compared with those obtained in the S group (sham vs CPB vs CPB/ECFC vs CPB/ECFC/L-NIO: histological score 1.62 ± 0.51 vs 5.37 ± 0.91 vs 3.37 ± 0.89 vs 4.37 ± 0.74; PaO₂/FiO₂ 389 ± 12 vs 233 ± 36 vs 338 ± 28 vs 287 ± 30; wet/dry weight 3.11 ± 0.32 vs 6.71 ± 0.73 vs 4.66 ± 0.55 vs 5.52 ± 0.57; protein levels in BALF: 134 ± 22 vs 442 ± 99 vs 225 ± 41 vs 337 ± 53, all P < 0.05). Compared to the CPB treatment, ECFCs significantly improved pulmonary capillary permeability and PaO₂/FiO₂. Similarly, ECFCs also decreased the inflammatory cell number and pro-inflammatory factors in BALF and peripheral blood, as well as the oxidative stress response in the lung tissue. ECFCs reduced the lung histological injury score and apoptosis and regulated apoptosis-related proteins in the lung tissue. Compared with the CPB/ECFC group, all the indicators were partly reversed by the L-NIO.

Conclusions

ECFCs significantly reduced lung injury induced by inflammation after CPB.

Plasma cell-free DNA predicts pediatric cerebral malaria severity

BACKGROUNDPrediction of adverse outcomes in cerebral malaria (CM) is difficult. We hypothesized that cell-free DNA (cfDNA) levels would facilitate identification of severe and potentially fatal CM cases.METHODSIn this retrospective study, plasma from Malawian children with CM (n = 134), uncomplicated malaria (UM, n = 77), and healthy controls (HC, n = 60) was assayed for cfDNA using a fluorescence assay. Host and parasite cfDNA was measured by quantitative PCR. Immune markers were determined by ELISA, Luminex, or cytometric bead array.RESULTSTotal cfDNA increased with malaria severity (HC versus UM, P < 0.001; HC versus CM, P < 0.0001; UM versus CM, P < 0.0001), was elevated in retinopathy-positive (Ret+) CM relative to Ret- CM (7.66 versus 5.47 ng/μL, P = 0.027), and differentiated Ret+ fatal cases from survivors (AUC 0.779; P < 0.001). cfDNA levels in patients with non-malarial febrile illness (NMF, P = 0.25) and non-malarial coma (NMC, P = 0.99) were comparable with UM. Host DNA, rather than parasite DNA, was the major cfDNA contributor (UM, 268 versus 67 pg/μL; CM, 2824 versus 463 pg/μL). Host and parasite cfDNA distinguished CM by retinopathy (host, AUC 0.715, P = 0.0001; parasite, AUC 0.745, P = 0.0001), but only host cfDNA distinguished fatal cases (AUC 0.715, P = 0.0001). Total cfDNA correlated with neutrophil markers IL-8 (rs = 0.433, P < 0.0001) and myeloperoxidase (rs = 0.683, P < 0.0001).CONCLUSIONQuantifying plasma cfDNA is a simple assay useful in identifying children at risk for fatal outcome and has promise as a point-of-care assay. Elevated cfDNA suggests a link with host inflammatory pathways in fatal CM.FUNDINGNIH NCATS (AK), Burroughs-Wellcome (AK), and National Health and Medical Research Council of Australia (SJR).

Toll-like receptor 9 and the inflammatory response to surgical trauma and cardiopulmonary bypass

Objectives

Cardiac surgery can lead to post-operative end-organ complications secondary to activation of systemic inflammatory response. We hypothesize that surgical trauma or cardiopulmonary bypass (CPB) may initiate systemic inflammatory response via release of mitochondrial DNA (mtDNA) signaling Toll-like receptor 9 (TLR9) and interleukin-6 production (IL-6).

Materials and methods

The role of TLR9 in systemic inflammatory response in cardiac surgery was studied using a murine model of sternotomy and a porcine model of sternotomy and CPB. mtDNA and IL-6 were measured with and without TLR9-antagonist treatment. To study ischemia-reperfusion injury, we utilized an ex-vivo porcine kidney model.

Results

In the rodent model (n = 15), circulating mtDNA increased 19-fold (19.29 ± 3.31, p < 0.001) and plasma IL-6 levels increased 59-fold (59.06 ± 14.98) at 1-min post-sternotomy compared to pre-sternotomy. In the murine model (n = 11), administration of TLR-9 antagonists lowered IL-6 expression post-sternotomy when compared to controls (59.06 ± 14.98 vs. 5.25 ± 1.08) indicating that TLR-9 is a positive regulator of IL-6 after sternotomy. Using porcine models (n = 10), a significant increase in circulating mtDNA was observed after CPB (Fold change 29.9 ± 4.8, p = 0.005) and along with IL-6 following renal ischaemia-reperfusion. Addition of the antioxidant sulforaphane reduced circulating mtDNA when compared to controls (FC 7.36 ± 0.61 vs. 32.0 ± 4.17 at 60 min post-CPB).

Conclusion

CPB, surgical trauma and ischemic perfusion injury trigger the release of circulating mtDNA that activates TLR-9, in turn stimulating a release of IL-6. Therefore, TLR-9 antagonists may attenuate this response and may provide a future therapeutic target whereby the systemic inflammatory response to cardiac surgery may be manipulated to improve clinical outcomes.

Validation of CDr15 as a new dye for detecting neutrophil extracellular trap

Neutrophil extracellular trap (NET) is one of the first-line defenses against microbes. Under certain circumstances, however, it also plays an aggravating factor in diverse inflammation-related diseases including cancers and vascular diseases. Our aim is to develop a new method to detect NET in cells and tissues using a DNA-specific fluorescence probe CDr15. CDr15 was characterized to be impermeable to the cell membranes and to emit a strong fluorescence in association with extracellular DNAs in NET. Due to these properties, CDr15 was successfully shown to quantify NETs in vitro and to be applicable for real-time monitoring NET formation in PMA-stimulated neutrophils. Even in formaldehyde-fixed tumor specimens, CDr15 could detect NETs spreading around cancer cells. Compared with DAPI and SYTOX DNA dyes, CDr15 showed a lower level of background fluorescence and a higher specificity in NET detection. Based on these results, we propose CDr15 as a novel marker of NET to be applicable in experimental and clinical studies.

INFLUENCE OF THE ACUTE INFLAMMATION AND ENDOTHELIAL DYSFUNCTION ON THE RETINAL VEIN OCCLUSION FORMATION AFTER CARDIO-SURGICAL INTERFERENCES WITH THE USE OF CARDIOPULMONARY BYPASS

Acute inflammation and endothelial dysfunction (EDF) are typical pathological processes, which determine the development of retinal vein occlusion (RVO) during cardio-surgery with the use of cardiopulmonary bypass (CB), but the connection of seromarkers according to the terms of occlusion appearance remains undefined. The aim – to determine the influence of the acute inflammation and EDF for RVO formation after cardio-surgical interferences with the use of CB according to the terms of occlusion appearance. Material and methods. There were selected for the research the data of 137 eyes (126 patients, the main group) with RVO after the surgery with CB. The comparison group contains the data about examination of 86 eyes (43 patients), who had not any occlusion during all term of examination. The control group consisted of 10 eyes (5 patients) without occlusion, which were examined before surgery. An ophthalmologist 2, 7, 30, 60, 90 and 180 days after cardio-surgical interference, examined patients. The content of IL-6, IL-8 and VE-cadherin in blood serum was determined by immunoenzyme technique (Bender Medsystems, Austria). Statistical data processing was performed with the use of Statistica 10 program (StatSoft, Inc., USA), regression analysis – with the use of the program package GLZ. Results. The conduction of cardio-surgeries with the use of CB caused an increase of the interleukins content in the early period (IL-6 on the 2nd and 7th days, and IL-8 up to 30 days), while the content of VE-cadherin (VE-C) was slightly increased during almost all period of monitoring. With the availability of RVO, the content of IL-6 during all terms of occlusion appearance was significantly higher, the content of IL-6 was up to 30 days, and the content of VE-C in a greater degree was after the 7th day. The regression analysis showed that after 1-2 days RVO appearance was directly related with the content of IL-6 and IL-8 in the blood, on the 3rd and 7th days – only with the content of IL-8, on the 8th and 30th days – with the content of all markers, and then with the content of IL-6 and VE-C. The accuracy of the prediction of the presence or absence of RVO at the appropriate period according to the calculated regression model is at least 78 % (p <0.001), what proves the influence of markers on the development of RVO. Conclusions. The undertaken study shows the meaning of the acute inflammation and EDF by appearance of RVO with the use of CB, what justifies the application of the preventive measures - at the early stages the restriction of activity of the inflammatory process, at the later stages – prevention of EDF development.

Cell free DNA as a diagnostic and prognostic marker for cardiovascular diseases

Release of cell free DNA (cfDNA) from damaged or dead cells routinely occurs in normal physiology. Recently, cfDNA has emerged as an essential biomarker in cardiovascular disease (CVD) of potential prognostic and diagnostic significance. Within the last decade, significant research efforts have been devoted to uncovering the mechanisms mediating cfDNA release and its outcome-predicting ability. The current review focuses on the pathways for cfDNA release in myocardial infarction, heart failure and hypertension, and discusses implementation of cfDNA monitoring to assess the overall development of these disease states and predict future complications.

Flow Cytometry-Based Quantification of Neutrophil Extracellular Traps Shows an Association with Hypercoagulation in Septic Shock and Hypocoagulation in Postsurgical Systemic Inflammation-A Proof-of-Concept Study

This proof-of-concept study aimed to evaluate a novel method of flow cytometry-based quantification of neutrophil extracellular traps (NETs) in septic shock patients and to identify possible interactions between the number of free-circulating NETs and alterations of the coagulatory system. Patients suffering from septic shock, a matched control group (CTRL), and patients suffering from systemic inflammation after cardiac (CABG) or major abdominal surgery (MAS) were enrolled in this prospective proof-of-concept study. Compared to the matched controls, free-circulating NETs were significantly elevated in septic shock and postsurgical patients (data are presented in median (IQR)); septic shock: (2.7 (1.9-3.9); CABG: 2.7 (2.1-3.7); MAS: 2.7 (2.1-3.9); CTRL: 1.6 (1-2); CTRL vs. septic shock: p = 0.001; CTRL vs. CABG: p < 0.001; CTRL vs. MAS: p < 0.001). NETs correlated positively with FIBTEM mean clot firmness (MCF) in septic shock patients (r = 0.37, p < 0.01) while they correlated negatively in surgical patients (CABG: r = -0.28, p < 0.01; MAS: r = -0.25, p = 0.03). Flow-cytometric quantification of NETs showed a significant increase in free-circulating NETs under inflammatory conditions. Furthermore, this study hints to an association of the number of NETs with hypercoagulation in septic shock patients and hypocoagulation in surgery-induced inflammation.

Targeting of cell-free DNA by DNase I diminishes endothelial dysfunction and inflammation in a rat model of cardiopulmonary bypass

The use of cardiopulmonary bypass (CPB) results in the activation of leukocytes, release of neutrophil extracellular traps (NETs) and severe inflammation. We hypothesize that targeting of circulating cell-free DNA (cfDNA) by DNases might represent a feasible therapeutic strategy to limit CPB-associated side effects. Male Wistar rats (n = 24) underwent CPB with deep hypothermic circulatory arrest (DHCA) and were divided into 3 groups: control (group 1), one i.v. bolus DNase I before CPB start (group 2) and a second DNase I dose before reperfusion (group 3). We found a positive correlation between plasma cfDNA/NETs levels and compromised endothelial vasorelaxation after CPB. DNase I administration significantly diminished plasma cfDNA/NETs levels. Further, a dose-dependent improvement in endothelial function accompanied by significant reduction of circulating intercellular adhesion molecule (ICAM)-1 was observed. Rats of group 3 had significantly reduced plasma IL-6 levels and downregulated expression of adhesion molecules resulting in impaired leukocyte extravasation and reduced MPO activity in lungs. Mechanistically, digestion of NETs by DNase I significantly diminished NETs-dependent upregulation of adhesion molecules in human endothelial cells. Altogether, systemic DNase I administration during CPB efficiently reduced cfDNA/NETs-mediated endothelial dysfunction and inflammation and might represents a promising therapeutic strategy for clinical practice.