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

Development of DNase-1 Loaded Polymeric Nanoparticles Synthesized by Inverse Flash Nanoprecipitation for Neutrophil-Mediated Drug Delivery to In Vitro Thrombi

Activated neutrophils release Neutrophil Extracellular Traps (NETs), comprising decondensed chromatin, peroxidases, and serine proteases, which aid in host defense but are also implicated in thrombosis and resistance to thrombolysis. Recombinant DNase 1, which degrades NETs, may aid in thrombus dissolution synergistically with fibrinolytics. However, its short half-life and susceptibility to plasma proteases limit its therapeutic applicability. To address these limitations, DNase1 is encapsulated into polymeric nanoparticles (DNPs) using inverse Flash Nanoprecipitation (iFNP), a scalable nanoparticle synthesis technique. Previously only used with model proteins, the study demonstrates for the first time the feasibility of extending iFNP to the encapsulation of therapeutic proteins. Conditions that promote DNase1 solubility, preserve activity, and demonstrate release resulting in ex vivo NET degradation are detailed. Furthermore, the use of neutrophils, the source of NETs, as carriers for DNPs to enhance targeted delivery is investigated. These findings confirm that DNP-loaded neutrophils maintain key functionalities, including viability and oxidative burst, and associate with in vitro blood clots to deliver nanoparticles, and DNase1 protein. This study not only extends the feasibility of applying iFNP to encapsulate therapeutic proteins into polymeric nanoparticles, a promising alternative to lipid nanoparticles, but also contributes to the emerging literature on neutrophils as delivery vectors for nanocarriers.

Degradation rather than disassembly of necrotic debris is essential to enhance recovery after acute liver injury

Necrotic cell death causes loss of membrane integrity, release of intracellular contents and deposition of necrotic cell debris. Effective clearance of this debris is crucial for resolving inflammation and promoting tissue recovery. While leukocyte phagocytosis plays a major role, soluble factors in the bloodstream also contribute to debris removal. Our study examined whether enzymatic degradation or disassembly of necrotic debris enhances clearance and improves outcomes in a mouse model of drug-induced liver injury. Using intravital microscopy and on-tissue spatially-resolved microproteomics, we demonstrated that necrotic debris is more complex than anticipated, containing DNA, filamentous actin, histones, complement C3, fibrin(ogen) and plasmin(ogen), among many other components. DNase 1 treatment facilitated recovery significantly by enhancing the clearance of DNA from necrotic areas, reducing circulating nucleosomes and actin, and lowering the associated inflammatory response. However, its effect on actin and other damage-associated molecular patterns in necrotic regions was limited. Treatment with short synthetic peptides, specifically 20-amino acid-long positively charged poly L-lysine (PLK) and negatively charged poly L-glutamic acid (PLE), which displace histones from debris in vitro, did not inhibit liver injury or promote recovery. Moreover, activating plasmin to disrupt fibrin encapsulation via tissue plasminogen activator (tPa) led to increased circulating actin levels and worsening of injury parameters. These findings suggest that fibrin encapsulation is important for containing necrotic debris and that enzymatic degradation of necrotic debris is a more effective strategy to enhance tissue recovery than targeting debris disassembly.

Recombinant human DNase treatment mitigates extracellular trap mediated damage and improves long-term recovery after spinal cord injury in male mice

After traumatic spinal cord injury (SCI), inflammation and other reactive processes exacerbate tissue damage and impair long-term motor recovery. Extracellular traps (ETs) are an immune cell effector function first described in neutrophils wherein chromatin is decondensed, decorated with cytotoxic granule enzymes, and expelled from the cell body. Recently, ETs have been linked to poor functional outcomes in SCI; however, translatable agents to prevent ET-mediated damage after SCI have yet to be explored. We assessed recombinant human (rh) DNase (trade name Pulmozyme) as a potential therapeutic that could be repurposed to break down ETs after SCI. To determine the timing of treatment, we characterized the timeline of ET formation in a thoracic contusion model of SCI in mice. We found that ETs levels increased in the injured spinal cord by 4 h post injury (hpi), peaking within 24 hpi. When rhDNase was administered at 1 hpi, DNase activity in the serum remained elevated for 24 hpi with a corresponding increase in circulating ET fragments. At 6 hpi, blood-spinal cord barrier permeability was attenuated in rhDNase-treated animals. Long-term functional hind limb recovery, as assessed by the ladder rung walking test, was improved at 35 dpi in rhDNase-treated animals compared to vehicle-treated controls. RhDNase-treated animals also exhibited shorter SCI lesion lengths at 35 dpi. Altogether, our data demonstrate the potential of rhDNase as an anti-ET therapeutic to improve long-term SCI outcomes.

Clearance of Cell-Free DNA: A Novel Target for Therapeutic Utilization in Multiple Systemic Disorders

Cell-free DNA (cfDNA) holds significant promise for diagnostic and therapeutic advancements in medicine. This review delineates the utility of cfDNA in diagnostics and its therapeutic potential through clearance mechanisms for an array of diseases. Damage-associated molecular patterns (DAMPs) are endogenous molecules released by host cells during stress, or injury. As a trigger for inflammatory responses via damage-associated molecular patterns (DAMPs), cfDNA's removal via nanotechnological approaches can attenuate inflammation and promote tissue repair. While the application of cfDNA clearance is particularly auspicious in cancer, sepsis, and inflammatory conditions, it is confronted with challenges including toxicity, specificity, and the rigors of clinical trial validation. Collectively, this review delineates novel therapeutic targets to inform the development of innovative treatment strategies.

Cytosolic nucleic acid sensing as driver of critical illness: mechanisms and advances in therapy

Nucleic acids from both self- and non-self-sources act as vital danger signals that trigger immune responses. Critical illnesses such as acute respiratory distress syndrome, sepsis, trauma and ischemia lead to the aberrant cytosolic accumulation and massive release of nucleic acids that are detected by antiviral innate immune receptors in the endosome or cytosol. Activation of receptors for deoxyribonucleic acids and ribonucleic acids triggers inflammation, a major contributor to morbidity and mortality in critically ill patients. In the past decade, there has been growing recognition of the therapeutic potential of targeting nucleic acid sensing in critical care. This review summarizes current knowledge of nucleic acid sensing in acute respiratory distress syndrome, sepsis, trauma and ischemia. Given the extensive research on nucleic acid sensing in common pathological conditions like cancer, autoimmune disorders, metabolic disorders and aging, we provide a comprehensive summary of nucleic acid sensing beyond critical illness to offer insights that may inform its role in critical conditions. Additionally, we discuss potential therapeutic strategies that specifically target nucleic acid sensing. By examining nucleic acid sources, sensor activation and function, as well as the impact of regulating these pathways across various acute diseases, we highlight the driving role of nucleic acid sensing in critical illness.

Diversity of intestinal microbiota and inflammatory cytokines after severe trauma

Accumulating evidence has reported that the intestinal microbiota could play important roles in the occurrence and progression of severe trauma. However, the hypothesized potential targeted intestinal microbiota to mediate and regulate the levels of inflammatory cytokines and promote rapid recovery of body after severe trauma remains unclear. This study was aimed to explore the changes and correlation of intestinal microbiota and inflammatory cytokines in rats with severe crush and fracture trauma. The controlled laboratory study design was used, and a crush and fracture severe trauma rat model was established. 16S rRNA high-throughput gene sequencing and ELISA were used to analyze the changes in intestinal microbiota and inflammatory cytokines within one week after trauma. The correlation between intestinal microbiota and inflammatory cytokines was also analyzed. Loss of overall diversity and expansion of intestinal microbiota in the rats due to severe trauma was observed. Specifically, there was a significant increase in the abundance of Muribaculaceae [LDA (Linear Discriminant Analysis)-value = 4.814, P = 0.014] after severe trauma, while Prevotella (LDA-value = 5.235, P = 0.020) and Alloprevotella (LDA-value = 4.443, P = 0.015) were slightly lower in the trauma group than in the control group. The levels of inflammatory cytokines (IL-1α, IL-6, IL-8 and TNF-α) in the trauma group decreased from the first day to the third day and continued to increase until one week after the trauma. Prevotellaceae_UCG_001 was correlated with TNF-a (R = 0.411, P = 0.033); Lactobacillus was negatively correlated with IL-6 (R = - 0.434, P = 0.024) and IL-1α (R = - 0.419, P = 0.030) and positively correlated with IL-8 (R = 0.391, P = 0.045); and Lachnospiraceae_NK4A136_group (R = - 0.559, P = 0.027) and Muribaculaceae (R = - 0.568, P = 0.024) were negatively correlated with IL-8. Severe trauma shows stress-like activities by negatively modulating intestinal microbiota and affecting certain inflammatory cytokines contributing to host health, which implies that the regulation of potentially targeted intestinal microbiota, and further mediating and maintaining the homeostasis of inflammatory cytokines, is expected to promote the accelerating recovery of the body after severe trauma.

Targeting NETosis in Acute Brain Injury: A Systematic Review of Preclinical and Clinical Evidence

Acute brain injury (ABI) remains one of the leading causes of death and disability world-wide. Its treatment is challenging due to the heterogeneity of the mechanisms involved and the variability among individuals. This systematic review aims at evaluating the impact of anti-histone treatments on outcomes in ABI patients and experimental animals and defining the trend of nucleosome levels in biological samples post injury. We performed a search in Pubmed/Medline and Embase databases for randomized controlled trials and cohort studies involving humans or experimental settings with various causes of ABI. We formulated the search using the PICO method, considering ABI patients or animal models as population (P), comparing pharmacological and non-pharmacological therapy targeting the nucleosome as Intervention (I) to standard of care or no treatment as Control (C). The outcome (O) was mortality or functional outcome in experimental animals and patients affected by ABI undergoing anti-NET treatments. We identified 28 studies from 1246 articles, of which 7 were experimental studies and 21 were human clinical studies. Among these studies, only four assessed the effect of anti-NET therapy on circulating markers. Three of them were preclinical and reported better outcome in the interventional arm compared to the control arm. All the studies observed a significant reduction in circulating NET-derived products. NETosis could be a target for new treatments. Monitoring NET markers in blood and cerebrospinal fluid might predict mortality and long-term outcomes. However, longitudinal studies and randomized controlled trials are warranted to fully evaluate their potential, as current evidence is limited.

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.

Development of a Clonal and High-Yield Mammalian Cell Line for the Manufacturing of a Hyperactive Human DNase I with Extended Plasma Half-Life Using PASylation® Technology

Cumulative evidence from several pre-clinical studies suggests that restoration of plasma DNase activity in a thrombo-inflammatory state may improve clinical outcomes. Following injury, hyperactivated immune cells release large amounts of granular proteins together with DNA, which often accumulate in the surrounding environment in so-called neutrophil extracellular traps (NETs). Degradation of excess NETs by systemic DNase administration offers a promising therapeutic approach to ameliorate inflammation and dissolve intravascular clots. In order to expand the therapeutic utility of human DNase I, a variant of the enzyme was developed that has both a prolonged systemic half-life and a higher catalytic activity compared to Dornase alfa (Pulmozyme®), the recombinant form of DNase I approved for inhaled therapy of cystic fibrosis. The hyperactive enzyme was "PASylated" by genetic fusion with a strongly hydrophilic and biodegradable PAS-polypeptide to increase its hydrodynamic volume and retard kidney filtration. A stable TurboCell™ CHO-K1-based cell line was generated which is suitable for the future production of PASylated DNase I according to good manufacturing practice (GMP). Furthermore, a robust bioprocess strategy was devised and an effective downstream process was developed. The final protein product is characterized by excellent purity, favorable physicochemical properties, a 14-fold higher DNA-degrading activity than Dornase alfa and a sustained pharmacokinetic profile, with a 22-fold slower clearance in rats.

IL-8 Induces Neutrophil Extracellular Trap Formation in Severe Thermal Injury

Neutrophil extracellular traps (NETs) have a dual role in the innate immune response to thermal injuries. NETs provide an early line of defence against infection. However, excessive NETosis can mediate the pathogenesis of immunothrombosis, disseminated intravascular coagulation (DIC) and multiple organ failure (MOF) in sepsis. Recent studies suggest that high interleukin-8 (IL-8) levels in intensive care unit (ICU) patients significantly contribute to excessive NET generation. This study aimed to determine whether IL-8 also mediates NET generation in patients with severe thermal injuries. IL-8 levels were measured in serum samples from thermally injured patients with ≥15% of the total body surface area (TBSA) and healthy controls (HC). Ex vivo NET generation was also investigated by treating isolated neutrophils with serum from thermal injured patients or normal serum with and without IL-8 and anti-IL-8 antibodies. IL-8 levels were significantly increased compared to HC on days 3 and 5 (p < 0.05) following thermal injury. IL-8 levels were also significantly increased at day 5 in septic versus non-septic patients (p < 0.001). IL-8 levels were also increased in patients who developed sepsis compared to HC at days 3, 5 and 7 (p < 0.001), day 10 (p < 0.05) and days 12 and 14 (p < 0.01). Serum containing either low, medium or high levels of IL-8 was shown to induce ex vivo NETosis in an IL-8-dependent manner. Furthermore, the inhibition of DNase activity in serum increased the NET-inducing activity of IL-8 in vitro by preventing NET degradation. IL-8 is a major contributor to NET formation in severe thermal injury and is increased in patients who develop sepsis. We confirmed that DNase is an important regulator of NET degradation but also a potential confounder within assays that measure serum-induced ex vivo NETosis.

Severe thermal and major traumatic injury results in elevated plasma concentrations of total heme that are associated with poor clinical outcomes and systemic immune suppression

Background

Traumatic and thermal injuries result in a state of systemic immune suppression, yet the mechanisms that underlie its development are poorly understood. Released from injured muscle and lysed red blood cells, heme is a damage associated molecular pattern with potent immune modulatory properties. Here, we measured plasma concentrations of total heme in over 200 traumatic and thermally-injured patients in order to examine its relationship with clinical outcomes and post-injury immune suppression.

Methods

Blood samples were collected from 98 burns (≥15% total body surface area) and 147 traumatically-injured (injury severity score ≥8) patients across the ultra-early (≤1 hour) and acute (4-72 hours) post-injury settings. Pro-inflammatory cytokine production by lipopolysaccharide (LPS) challenged whole blood leukocytes was studied, and plasma concentrations of total heme, and its scavengers haptoglobin, hemopexin and albumin measured, alongside the expression of heme-oxygenase-1 (HO-1) in peripheral blood mononuclear cells (PBMCs). LPS-induced tumour necrosis factor-alpha (TNF-α) production by THP-1 cells and monocytes following in vitro heme treatment was also examined.

Results

Burns and traumatic injury resulted in significantly elevated plasma concentrations of heme, which coincided with reduced levels of hemopexin and albumin, and correlated positively with circulating levels of pro and anti-inflammatory cytokines. PBMCs isolated from trauma patients 4-12 and 48-72 hours post-injury exhibited increased HO-1 gene expression. Non-survivors of burn injury and patients who developed sepsis, presented on day 1 with significantly elevated heme levels, with a difference of 6.5 µM in heme concentrations corresponding to a relative 52% increase in the odds of post-burn mortality. On day 1 post-burn, heme levels were negatively associated with ex vivo LPS-induced TNF-α and interleukin-6 production by whole blood leukocytes. THP-1 cells and monocytes pre-treated with heme exhibited significantly reduced TNF-α production following LPS stimulation. This impairment was associated with decreased gene transcription, reduced activation of extracellular signal-regulated kinase 1/2 and an impaired glycolytic response.

Conclusions

Major injury results in elevated plasma concentrations of total heme that may contribute to the development of endotoxin tolerance and increase the risk of poor clinical outcomes. Restoration of the heme scavenging system could be a therapeutic approach by which to improve immune function post-injury.

Associations of Fatty Liver Disease With Recovery After Traumatic Injury

INTRODUCTION

Fatty liver disease (FLD) is associated with systemic inflammation, metabolic disease, and socioeconomic risk factors for poor health outcomes. Little is known on how adults with FLD recover from traumatic injury.

METHODS

We studied adults admitted to the intensive care unit of a level 1 trauma center (2016-2020), excluding severe head injury/cirrhosis (N = 510). We measured the liver-spleen attenuation difference in Hounsfield units (HUL-S) using virtual noncontrast computerized tomography scans: none (HUL-S>1), mild (-10≤HUL-S<1), moderate/severe (HUL-S < -10). We used Cox models to examine the "hazard" of recovery from systemic inflammatory response (SIRS score 2 or higher) organ dysfunction, defined as sequential organ failure assessment score 2 or higher, and lactate clearance (<2 mmol/L) in relation to FLD.

RESULTS

Fifty-one participants had mild and 29 had moderate/severe FLD. The association of FLD with recovery from SIRS differed according to whether an individual had shock on admission (hazard ratio [HR] = 0.76; 95% confidence interval [CI] 0.55-1.05 with shock; HR = 1.81; 95% CI 1.43-2.28 without shock). Compared to patients with no FLD, the hazard of lactate clearance was similar for mild FLD (HR = 1.04; 95% CI 0.63-1.70) and lower for moderate/severe FLD (HR = 0.40; 95% CI 0.18-0.89).

CONCLUSIONS

FLD is common among injured adults. Associations of FLD with outcomes after shock and critical illness warrant further study.

Potential therapeutic targets for trauma management

Despite advances in medical treatments for severe trauma, it remains a critical condition associated with high mortality. During trauma, the release of endogenous damage-associated molecular patterns (DAMPs) can induce immune dysfunction, leading to sepsis or multiple organ dysfunction syndrome (MODS). Vaccines based on specific pathogen antigens and pathogen-associated molecular patterns (PAMPs) contribute largely to the prevention of communicable diseases through the induction of adaptive immune responses. Vaccines developed based on autologous molecules may also promote recovery from non-communicable diseases (NCDs) by eliciting appropriate immune responses, as recent clinical trials indicate. Developing new vaccines targeting DAMPs may be an effective pre-protective measure for trauma management. We describe the role of DAMPs in post-traumatic immune dysfunction and discuss the potential of harnessing them for trauma vaccine development as well as the risks and challenges.

Measurement of Urinary Gc-Globulin by a Fluorescence ELISA Technique: Method Validation and Clinical Evaluation in Septic Patients-A Pilot Study

A major complication of sepsis is the development of acute kidney injury (AKI). In case of acute tubular damage, Gc-globulin, a known serum sepsis marker is increasingly filtrated into the urine therefore, urinary Gc-globulin (u-Gc) levels may predict septic AKI. We developed and validated a competitive fluorescence ELISA method for u-Gc measurement. Serum and urine samples from septic patients were collected in three consecutive days (T1, T2, T3) and data were compared to controls. Intra- and interassay imprecisions were CV < 14% and CV < 20%, respectively, with a recovery close to 100%. Controls and septic patients differed (p < 0.001) in their u-Gc/u-creatinine levels at admission (T1, median: 0.51 vs. 79.1 µg/mmol), T2 (median: 0.51 vs. 57.8 µg/mmol) and T3 (median: 0.51 vs. 55.6 µg/mmol). Septic patients with AKI expressed higher u-Gc/u-creatinine values than those without AKI at T1 (median: 23.6 vs. 136.5 µg/mmol, p < 0.01) and T3 (median: 34.4 vs. 75.8 µg/mmol, p < 0.05). AKI-2 stage patients exhibited more increased u-Gc/u-creatinine levels at T1 (median: 207.1 vs. 53.3 µg/mmol, p < 0.05) than AKI-1 stage individuals. Moderate correlations (p < 0.001) were observed between u-Gc/u-creatinine and se-urea, se-creatinine, se-hsCRP, WBC, u-total protein, u-albumin, u-orosomucoid/u-creatinine, and u-Cystatin C/u-creatinine levels. U-Gc testing may have a predictive value for AKI in septic patients.

Cell-Free DNA in Plasma and Serum Indicates Disease Severity and Prognosis in Blunt Trauma Patients

Background: Trauma is still a major cause of mortality in people < 50 years of age. Biomarkers are needed to estimate the severity of the condition and the patient outcome. Methods: Cell-free DNA (cfDNA) and further laboratory markers were determined in plasma and serum of 164 patients at time of admission to the emergency room. Among them were 64 patients with severe trauma (Injury Severity Score (ISS) ≥ 16), 51 patients with moderate trauma (ISS < 16) and 49 patients with single fractures (24 femur neck and 25 ankle fractures). Disease severity was objectified by ISS and Glasgow Coma Scale (GCS). Results: cfDNA levels in plasma and serum were significantly higher in patients with severe multiple trauma (SMT) than in those with moderate trauma (p = 0.002, p = 0.003, respectively) or with single fractures (each p < 0.001). CfDNA in plasma and serum correlated very strongly with each other (R = 0.91; p < 0.001). The AUC in ROC curves for identification of SMT patients was 0.76 and 0.74 for cfDNA in plasma and serum, respectively—this was further increased to 0.84 by the combination of cfDNA and hemoglobin. Within the group of multiple trauma patients, cfDNA levels were significantly higher in more severely injured patients and patients with severe traumatic brain injury (GCS ≤ 8 versus GCS > 8). Thirteen (20.3%) of the multiple trauma patients died during the first week after trauma. Levels of cfDNA were significantly higher in non-surviving patients than in survivors (p < 0.001), reaching an AUC of 0.81 for cfDNA in both, plasma and serum, which was further increased by the combination with hemoglobin and leukocytes. Conclusions: cfDNA is valuable for estimation of trauma severity and prognosis of trauma patients.

Early DNase-I therapy delays secondary brain damage after traumatic brain injury in adult mice

Traumatic brain injury (TBI) causes the release of danger-associated molecular patterns (DAMP) from damaged or dead cells, which contribute to secondary brain damage after TBI. Cell-free DNA (cfDNA) is a DAMP known to cause disruption of the blood-brain barrier (BBB), promote procoagulant processes, brain edema, and neuroinflammation. This study tested the hypothesis that administration of deoxyribonuclease-I (DNase-I) has a beneficial effect after TBI. Mice (n = 84) were subjected to controlled cortical impact (CCI) and posttraumatic intraperitoneal injections of low dose (LD) or high dose (HD) of DNase-I or vehicle solution at 30 min and 12 h after CCI. LD was most effective to reduce lesion volume (p = 0.003), brain water content (p < 0.0001) and to stabilize BBB integrity (p = 0.019) 1 day post-injury (dpi). At 6 h post injury LD-treated animals showed less cleavage of fibrin (p = 0.0014), and enhanced perfusion as assessed by micro-computer-tomography (p = 0.027). At 5 dpi the number of Iba1-positive cells (p = 0.037) were reduced, but the number of CD45-positive cells, motoric function and brain lesion volume was not different. Posttraumatic-treatment with DNase-I therefore stabilizes the BBB, reduces the formation of brain edema, immune response, and delays secondary brain damage. DNase-I might be a new approach to extend the treatment window after TBI.

Multi-Omics, an Integrated Approach to Identify Novel Blood Biomarkers of Alzheimer's Disease

The metabolomic and proteomic basis of mild cognitive impairment (MCI) and Alzheimer's disease (AD) is poorly understood, and the relationships between systemic abnormalities in metabolism and AD/MCI pathogenesis is unclear. This study compared the metabolomic and proteomic signature of plasma from cognitively normal (CN) and dementia patients diagnosed with MCI or AD, to identify specific cellular pathways and new biomarkers altered with the progression of the disease. We analysed 80 plasma samples from individuals with MCI or AD, as well as age- and gender-matched CN individuals, by utilising mass spectrometry methods and data analyses that included combined pathway analysis and model predictions. Several proteins clearly identified AD from the MCI and CN groups and included plasma actins, mannan-binding lectin serine protease 1, serum amyloid A2, fibronectin and extracellular matrix protein 1 and Keratin 9. The integrated pathway analysis showed various metabolic pathways were affected in AD, such as the arginine, alanine, aspartate, glutamate and pyruvate metabolism pathways. Therefore, our multi-omics approach identified novel plasma biomarkers for the MCI and AD groups, identified changes in metabolic processes, and may form the basis of a biomarker panel for stratifying dementia participants in future clinical trials.

Early dynamics of glial fibrillary acidic protein and extracellular DNA in plasma of mice after closed head traumatic brain injury

BACKGROUND

Glial fibrillary acidic protein (GFAP) in plasma is an established biomarker of traumatic brain injury (TBI) in humans. Plasma extracellular DNA (ecDNA) is a very sensitive, although nonspecific marker of tissue damage including TBI. Whether plasma GFAP or ecDNA could be used as an early non-invasive biomarker in the mouse model of closed head injury is unknown. The aim of this paper was to describe the early dynamics of plasma GFAP and ecDNA in the animal model of closed head TBI.

METHODS

Closed head TBI was induced using the weight-drop method in 40 adult CD1 mice and blood was collected in different time points (1, 2 or 3h) after TBI in different groups of mice. Plasma GFAP and ecDNA and ecDNA fragmentation from the experimental groups were compared to healthy controls. In the surviving mice, a static rods test was performed 30 days after TBI to assess the neurological outcome of TBI.

RESULTS

Despite a trend of higher plasma GFAP after TBI the differences between the groups were not statistically significant. Plasma ecDNA was higher by 50% after 1h (P<0.05) and 2h (P<0.05) after TBI and was highly variable after 3h. Plasma ecDNA, but not GFAP, was partially predictive of the neurological impairment of the mice.

CONCLUSION

In this study, we have described the early dynamics of plasma GFAP and ecDNA after TBI in mice. According to our results, ecDNA in plasma is a more sensitive early marker of TBI than GFAP. Analysis of tissue-specific ecDNA might improve its predictive value regarding the survival and neurobehavioral outcome.

Unveiling Leukocyte Extracellular Traps in Inflammatory Responses of the Central Nervous System

Over the past nearly two decades, increasing evidence has uncovered how immune cells can actively extrude genetic material to entrap invading pathogens or convey sterile inflammatory signals that contribute to shaping immune responses. Originally identified in neutrophils, the release of decondensed chromatin fibers decorated with antimicrobial proteins, called extracellular traps (ETs), has been recognized as a specific form of programmed inflammatory cell death, which is now known to occur in several other leukocytes. Subsequent reports have shown that self-DNA can be extruded from immune cells even in the absence of cell death phenomena. More recent data suggest that ETs formation could exacerbate neuroinflammation in several disorders of the central nervous system (CNS). This review article provides an overview of the varied types, sources, and potential functions of extracellular DNA released by immune cells. Key evidence suggesting the involvement of ETs in neurodegenerative, traumatic, autoimmune, and oncological disorders of the CNS will be discussed, outlining ongoing challenges and drawing potentially novel lines of investigation.

Exploratory Investigation of the Plasma Proteome Associated with the Endotheliopathy of Trauma

BACKGROUND

The endotheliopathy of trauma (EoT) is associated with increased mortality following injury. Herein, we describe the plasma proteome related to EoT in order to provide insight into the role of the endothelium within the systemic response to trauma.

METHODS

99 subjects requiring the highest level of trauma activation were included in the study. Enzyme-linked immunosorbent assays of endothelial and catecholamine biomarkers were performed on admission plasma samples, as well as untargeted proteome quantification utilizing high-performance liquid chromatography and tandem mass spectrometry.

RESULTS

Plasma endothelial and catecholamine biomarker abundance was elevated in EoT. Patients with EoT (n = 62) had an increased incidence of death within 24 h at 21% compared to 3% for non-EoT (n = 37). Proteomic analysis revealed that 52 out of 290 proteins were differentially expressed between the EoT and non-EoT groups. These proteins are involved in endothelial activation, coagulation, inflammation, and oxidative stress, and include known damage-associated molecular patterns (DAMPs) and intracellular proteins specific to several organs.

CONCLUSIONS

We report a proteomic profile of EoT suggestive of a surge of DAMPs and inflammation driving nonspecific activation of the endothelial, coagulation, and complement systems with subsequent end-organ damage and poor clinical outcome. These findings support the utility of EoT as an index of cellular injury and delineate protein candidates for therapeutic intervention.

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.

The Citrullination-Neutrophil Extracellular Trap Axis in Chronic Diseases

Citrullination of proteins is crucial for the formation of neutrophil extracellular traps (NETs) − strands of nuclear DNA expulsed in the extracellular environment along with antimicrobial proteins in order to halt the spread of pathogens. Paradoxically, NETs may be immunogenic and contribute to inflammation. It is known that for the externalization of DNA, a group of enzymes called peptidyl arginine deiminases (PADs) is required. Current research often looks at citrullination, NET formation, PAD overexpression, and extracellular DNA (ecDNA) accumulation in chronic diseases as separate events. In contrast, we propose that citrullination can be viewed as the primary mechanism of autoimmunity, for instance by the formation of anti-citrullinated protein antibodies (ACPAs) but also as a process contributing to chronic inflammation. Therefore, citrullination could be at the center, connecting and impacting multiple inflammatory diseases in which ACPAs, NETs, or ecDNA have already been documented. In this review, we aimed to highlight the importance of citrullination in the etiopathogenesis of a number of chronic diseases and to explore the diagnostic, prognostic, and therapeutic potential of the citrullination-NET axis.

Endogenous Deoxyribonuclease Activity and Cell-Free Deoxyribonucleic Acid in Acute Ischemic Stroke: A Cohort Study

BACKGROUND AND PURPOSE

Cell-free DNA (cfDNA) and endogenous deoxyribonuclease activity are opposing mediators and might influence the inflammatory response following acute ischemic stroke. In this cohort study, we investigated the relation between these markers, circulating inflammatory mediators and clinical course including occurrence of stroke-associated infections (SAI) in patients with acute stroke.

METHODS

Ninety-two patients with stroke due to large vessel occlusion undergoing mechanical thrombectomy were prospectively recruited at Hannover Medical School from March 2018 to August 2019. Deoxyribonuclease activity, cfDNA, damage-associated molecular patterns, and circulating cytokines were measured in venous blood collected immediately before mechanical thrombectomy and 7 days later. Reperfusion status was categorized (sufficient/insufficient). Clinical outcome was evaluated using the modified Rankin Scale after 90 days, where a score of 3 to 6 was considered unfavorable. To validate findings regarding SAI, another stroke cohort (n=92) was considered with blood taken within 24 hours after stroke onset.

RESULTS

Patients with unfavorable clinical outcome had higher cfDNA concentrations. After adjustment for confounders (Essen Stroke Risk Score, National Institutes of Health Stroke Scale, and sex), 7-day cfDNA was independently associated with clinical outcome and especially mortality (adjusted odds ratio: 3.485 [95% CI, 1.001-12.134] and adjusted odds ratio: 9.585 [95% CI, 2.006-45.790]). No association was found between reperfusion status and cfDNA or deoxyribonuclease activity. While cfDNA concentrations correlated positively, deoxyribonuclease activity inversely correlated with distinct biomarkers. Baseline deoxyribonuclease activity was lower in patients who developed SAI compared with patients without SAI. This association was confirmed after adjustment for confounding factors (adjusted odds ratio: 0.447 [95% CI, 0.237-0.844]). In cohort 2, differences of deoxyribonuclease activity between patients with and without SAI tended to be higher with higher stroke severity.

CONCLUSIONS

The interplay of endogenous deoxyribonuclease activity and cfDNA in acute stroke entails interesting novel diagnostic and potential therapeutic approaches. We confirm an independent association of cfDNA with a detrimental clinical course after stroke due to large vessel occlusion. This study provides first evidence for lower endogenous deoxyribonuclease activity as risk factor for SAI after severe stroke.

The role of neutrophil extracellular traps in acute lung injury

Acute lung injury (ALI) is a heterogeneous inflammatory condition associated with high morbidity and mortality. Neutrophils play a key role in the development of different forms of ALI, and the release of neutrophil extracellular traps (NETs) is emerging as a common pathogenic mechanism. NETs are essential in controlling pathogens, and their defective release or increased degradation leads to a higher risk of infection. However, NETs also contain several pro-inflammatory and cytotoxic molecules than can exacerbate thromboinflammation and lung tissue injury. To reduce NET-mediated lung damage and inflammation, DNase is frequently used in preclinical models of ALI due to its capability of digesting NET DNA scaffold. Moreover, recent advances in neutrophil biology led to the development of selective NET inhibitors, which also appear to reduce ALI in experimental models. Here we provide an overview of the role of NETs in different forms of ALI discussing existing gaps in our knowledge and novel therapeutic approaches to modulate their impact on lung injury.

Role of Cell-Free DNA and Deoxyribonucleases in Tumor Progression

Many studies have reported an increase in the level of circulating cell-free DNA (cfDNA) in the blood of patients with cancer. cfDNA mainly comes from tumor cells and, therefore, carries features of its genomic profile. Moreover, tumor-derived cfDNA can act like oncoviruses, entering the cells of vulnerable organs, transforming them and forming metastatic nodes. Another source of cfDNA is immune cells, including neutrophils that generate neutrophil extracellular traps (NETs). Despite the potential eliminative effect of NETs on tumors, in some cases, their excessive generation provokes tumor growth as well as invasion. Considering both possible pathological contributions of cfDNA, as an agent of oncotransformation and the main component of NETs, the study of deoxyribonucleases (DNases) as anticancer and antimetastatic agents is important and promising. This review considers the pathological role of cfDNA in cancer development and the role of DNases as agents to prevent and/or prohibit tumor progression and the development of metastases.