Elevated Plasma Levels of Cell-Free DNA During Liver Transplantation Are Associated With Activation of Coagulation

Prompt Thrombo-Inflammatory Response to Ischemia-Reperfusion Injury and Kidney Transplant Outcomes

Introduction

In kidney transplantation (KT), the role of the intravascular innate immune system (IIIS) in response to ischemia-reperfusion injury (IRI) is not well-understood. Here, we studied parallel changes in the generation of key activation products of the proteolytic cascade systems of the IIIS following living donor (LD) and deceased donor (DD) transplantation and evaluated potential associations with clinical outcomes.

Methods

In a cohort study, 63 patients undergoing LD (n = 26) and DD (n = 37) transplantation were prospectively included. Fifteen DD kidneys were preserved with hypothermic machine perfusion (HMP), and the remaining were cold stored. Activation products of the kallikrein-kinin, coagulation, and complement systems were measured in blood samples obtained systemically at baseline and locally from the transplant renal vein at 1, 10, and 30 minutes after reperfusion.

Results

DD kidneys exhibited a prompt and interlinked activation of all 3 cascade systems of IIIS postreperfusion, indicating a robust and local thrombo-inflammatory response to IRI. In this initial response, the complement activation product sC5b-9 exhibited a robust correlation with other IIIS activation markers and displayed a strong association with short-term and mid-term (24-month) graft dysfunction. In contrast, LD kidneys did not exhibit this thrombo-inflammatory response. The use of HMP was associated with reduced thromboinflammation and preserved mid-term kidney function.

Conclusion

Kidneys from DD are vulnerable to a prompt thrombo-inflammatory response to IRI, which adversely affects both short-term and long-term allograft function. Strategies aimed at minimizing graft immunogenicity prior to reperfusion are crucial to mitigate the intricate inflammatory response to IRI.

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 ).

Neutrophil extracellular traps predict postoperative pulmonary complications in paediatric patients undergoing parental liver transplantation

BACKGROUND

Parental liver transplantation (PLT) improves long-term survival rates in paediatric hepatic failure patients; however, the mechanism of PLT-induced postoperative pulmonary complications (PPCs) is unclear.

METHODS

A total of 133 paediatric patients undergoing PLT were included. Serum levels of NET components, including circulating free DNA (cfDNA), DNA-histone complex, and myeloperoxidase (MPO)-DNA complex, were detected. The occurrence of PPCs post-PLT, prolonged intensive care unit (ICU) stay and death within one year were recorded as the primary and secondary outcomes.

RESULTS

The overall rate of PPCs in the hospital was 47.4%. High levels of serum cfDNA, DNA-histone complexes and MPO-DNA complexes were associated with an increased risk of PPCs (for cfDNA, OR 2.24; for DNA-histone complex, OR 1.64; and for MPO-DNA, OR 1.94), prolonged ICU stay (OR 1.98, 4.26 and 3.69, respectively), and death within one year (OR 1.53, 2.65 and 1.85, respectively). The area under the curve of NET components for the prediction of PPCs was 0.843 for cfDNA, 0.813 for DNA-histone complexes, and 0.906 for MPO-DNA complexes. During the one-year follow-up, the death rate was higher in patients with PPCs than in patients without PPCs (14.3% vs. 2.9%, P = 0.001).

CONCLUSIONS

High serum levels of NET components are associated with an increased incidence of PPCs and death within one year in paediatric patients undergoing PLT. Serum levels of NET components serve as a biomarker for post-PLT PPCs and a prognostic indicator.

Neutrophil extracellular traps (NETs), transfusion requirements and clinical outcomes in orthotopic liver transplantation

Inflammatory phenomena have a direct impact on the prognosis of orthotopic liver transplantation (OLT). Neutrophil extracellular traps (NETs) contribute to OLT inflammation and hemostasis imbalance in OLT. The association between NETosis, clinical outcomes and transfusion requirements is not determined. To evaluate NETs release during OLT and the effect of NETosis ontransfusion requirements and adverse outcomes in a prospective cohort of patients submitted to OLT. We quantified citrullinated histones (cit-H3) and circulating-free-DNA (cf-DNA) in ninety-three patients submitted to OLT in three periods: pre-transplant, after graft reperfusion and before discharge. NETs markers were compared between these periods using ANOVA test. The association of NETosis and adverse outcomes was evaluated using regression models adjusted for age, sex and corrected MELD. We observed a peak of circulating NETs following reperfusion, evidenced by a 2.4-fold increase in cit-H3 levels in the post-graft reperfusion period (median levels of cit-H3 pre transplant: 0.5 ng/mL, after reperfusion: 1.2 ng/mL and at discharge 0.5 ng/mL, p < 0.0001). We observed an association between increased levels of cit-H3 and in-hospital death (OR = 1.168, 95% CI 1.021-1.336, p = 0.024). No association was found between NETs markers and transfusion requirements. There is a prompt release of NETs after reperfusion that is associated with poorer outcomes and death. Intraoperative NETs release seems to be independent of transfusion requirements. These findings highlight the relevance of inflammation promoted by NETS and its impact on OLT adverse clinical outcomes.

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.

Neutrophil extracellular traps facilitate cancer metastasis: cellular mechanisms and therapeutic strategies

Background

The formation of neutrophil extracellular traps (NETs) was initially discovered as a novel immune response against pathogens. Recent studies have also suggested that NETs play an important role in tumor progression. This review summarizes the cellular mechanisms by which NETs promote distant metastasis and discusses the possible clinical applications targeting NETs.

Method

The relevant literature from PubMed and Google Scholar (2001–2021) have been reviewed for this article.

Results

The presence of NETs has been detected in various primary tumors and metastatic sites. NET-associated interactions have been observed throughout the different stages of metastasis, including initial tumor cell detachment, intravasation and extravasation, the survival of circulating tumor cells, the settlement and the growth of metastatic tumor cells. Several in vitro and in vivo studies proved that inhibiting NET formation resulted in anti-cancer effects. The biosafety and efficacy of some NET inhibitors have also been demonstrated in early phase clinical trials.

Conclusions

Considering the role of NETs in tumor progression, NETs could be a promising diagnostic and therapeutic target for cancer management. However, current evidence is mostly derived from experimental models and as such more clinical studies are still needed to verify the clinical significance of NETs in oncological settings.

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.

Neutrophil extracellular traps mediate severe lung injury induced by influenza A virus H1N1 in mice coinfected with Staphylococcus aureus

Influenza virus and bacterial infection contributed to massive morbidity and mortality. However, the underlying mechanisms were poorly understood. A coinfected model was generating by using sublethal doses of influenza A virus H1N1 A/FM/1/47(H1N1) and methicillin-resistant Staphylococcus aureus (MRSA). Further, the model was optimized to achieve the highest peak of mortality initiated by intranasal infection with 0.2LD₅₀ H1N1 and 0.16LD₅₀ MRSA at 3 days interval. Excessive neutrophil recruitment, accompanied by high levels of inflammatory cytokines and chemokines, and increased bacterial and viral load were observed in coinfected mice. Under the inflammatory environments triggered by H1N1 and MRSA, the excessive neutrophil recruitment led to the formation of neutrophil extracellular traps (NETs), associated with severe inflammation and vascular endothelial injury. Importantly, the severity of lung injury could be alleviated by treatment with DNase I or a selective neutrophil elastase inhibitor (NEi). Therefore, our data suggested that excessive neutrophil recruitment and NETs formation contributed to severe inflammation and acute lung injury in coinfected animals.

Plasma Donor-Derived Cell-Free DNA Levels Are Associated With the Inflammatory Burden and Macrophage Extracellular Trap Activity in Renal Allografts

Recent studies have confirmed the role of plasma donor-derived cell-free DNA (ddcfDNA) as a reliable non-invasive biomarker for allograft injury after kidney transplantation. Whereas the variability of plasma ddcfDNA levels among recipients has limited their clinical use. This study aimed to explore the intrinsic factors associated with plasma ddcfDNA elevation by investigating the impact of Banff lesions and inflammatory infiltrates on ddcfDNA levels in kidney transplant recipients. From March 2017 to September 2019, a total of 106 kidney transplant recipients with matched allograft biopsies were included, consisting of 13 recipients with normal/nonspecific changes, 13 recipients with borderline changes, 60 with T cell-mediated rejection, and 20 with antibody-mediated rejection. Histologic classification was performed according to the Banff 2017 criteria by two experienced pathologists. Plasma ddcfDNA fractions ranged from 0.12% to 10.22%, with a median level of 0.91%. Banff histology subelements including glomerulitis, intimal arteritis, and severe interstitial inflammation were correlated with increased plasma ddcfDNA levels. The inflammatory cell infiltrate in the allografts was phenotyped by immunochemistry and automatically counted by digital image recognition. Pearson correlation analysis revealed a significant positive correlation between macrophage infiltrations in allografts and plasma ddcfDNA levels. Additionally, macrophage extracellular trap (MET) activity was significantly associated with the rise in plasma ddcfDNA levels. Our findings demonstrated that plasma ddcfDNA could reflect the inflammatory state in renal allografts and suggested the potential role of METs in the pathogenesis of allograft injury.

Liver ischaemia-reperfusion injury: a new understanding of the role of innate immunity

Liver ischaemia-reperfusion injury (LIRI), a local sterile inflammatory response driven by innate immunity, is one of the primary causes of early organ dysfunction and failure after liver transplantation. Cellular damage resulting from LIRI is an important risk factor not only for graft dysfunction but also for acute and even chronic rejection and exacerbates the shortage of donor organs for life-saving liver transplantation. Hepatocytes, liver sinusoidal endothelial cells and Kupffer cells, along with extrahepatic monocyte-derived macrophages, neutrophils and platelets, are all involved in LIRI. However, the mechanisms underlying the responses of these cells in the acute phase of LIRI and how these responses are orchestrated to control and resolve inflammation and achieve homeostatic tissue repair are not well understood. Technological advances allow the tracking of cells to better appreciate the role of hepatic macrophages and platelets (such as their origin and immunomodulatory and tissue-remodelling functions) and hepatic neutrophils (such as their selective recruitment, anti-inflammatory and tissue-repairing functions, and formation of extracellular traps and reverse migration) in LIRI. In this Review, we summarize the role of macrophages, platelets and neutrophils in LIRI, highlight unanswered questions, and discuss prospects for innovative therapeutic regimens against LIRI in transplant recipients.

Generation of neutrophil extracellular traps in patients with acute liver failure is associated with poor outcome

BACKGROUND AND AIMS

Acute liver failure (ALF) is characterized by significant changes in the hemostatic system and by systemic inflammation. The formation of neutrophil extracellular traps (NETs), in which an activated neutrophil expels its DNA, histones, and granular enzymes, such as myeloperoxidase (MPO), has been associated with immune-mediated and thrombotic diseases. We hypothesized that formation of NETs in patients with ALF contributes to progression of disease.

APPROACH AND RESULTS

A total of 676 patients with ALF (international normalized ratio [INR], ≥1.5) or severe acute liver injury (ALI; INR, ≥2.0) were recruited from the U.S. ALF Study Group Registry between 2011 and 2018, of whom 308 patients (45.6%) had acetaminophen-induced ALF. Up to 21 days after admission, 483 patients (71.5%) survived without liver transplantation (LT). Levels of cell-free DNA (cfDNA) and the specific NET marker MPO-DNA complexes were measured in plasma samples obtained on admission and compared to levels in healthy controls. In addition, liver tissue obtained at transplantation of 20 ALF patients was stained for NETs. Levels of cfDNA were 7.1-fold, and MPO-DNA complexes 2.5-fold, higher in patients with ALF compared to healthy controls. cfDNA levels were not associated with 21-day transplant-free survival, but were higher in those patients with more-severe disease on admission, as reflected by various laboratory and clinical parameters. MPO-DNA levels were 30% higher in patients with ALF who died or required urgent LT. Liver tissue of ALF patients stained positive for NETs in 12 of 18 evaluable patients.

CONCLUSIONS

Here, we provide evidence for NET formation in patients with ALF. Elevated plasma levels of MPO-DNA complexes in patients with ALF were associated with poor outcome, which suggests that NET formation contributes to disease progression.

Predicting portal thrombosis in cirrhosis: A prospective study of clinical, ultrasonographic and hemostatic factors

BACKGROUND & AIMS

Portal vein thrombosis (PVT) is a relatively frequent event in patients with cirrhosis. While different risk factors for PVT have been reported, such as decreased portal blood flow velocity (PBFV) and parameters related with severity of portal hypertension, these are based on retrospective studies assessing only a discrete number of parameters. The aim of the current study was to evaluate the incidence and risks factors for non-tumoral PVT development in a large prospective cohort of patients with cirrhosis.

METHODS

We performed an exhaustive evaluation of clinical, biochemical, inflammatory and acquired/hereditary hemostatic profiles in 369 patients with cirrhosis without PVT who were prospectively followed-up. Doppler ultrasound was performed at baseline and every 6 months or whenever clinically indicated. PVT development was always confirmed by computed tomography.

RESULTS

Twenty-nine patients developed non-tumoral PVT, with an incidence of 1.6%, 6% and 8.4% at 1, 3 and 5 years, respectively. Low platelet count, PBFV <15 cm/sec and history of variceal bleeding were factors independently associated with a high PVT risk. No relationship between PVT development and any other clinical biochemical, inflammatory and acquired or hereditary hemostatic parameter was found.

CONCLUSIONS

In patients with cirrhosis, the factors predictive of PVT development were mainly those related to the severity of portal hypertension. Our results do not support the role of hemostatic alterations (inherited or acquired) and inflammatory markers in the prediction of PVT in patients with cirrhosis.

LAY SUMMARY

Patients with cirrhosis and more severe portal hypertension are at higher risk of non-tumoral portal vein thrombosis development. Acquired or inherited hemostatic disorders, as well as inflammatory status, do not seem to predict the development of portal vein thrombosis in patients with cirrhosis.

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.

Impact of transplantation on neutrophil extracellular trap formation in patients with end-stage renal disease: A single-center, prospective cohort study

ABSTRACT

Increased neutrophil extracellular trap (NET) formation associates with high cardiovascular risk and mortality in patients with end-stage renal disease (ESRD). However, the effect of transplantation on NETs and its associated markers remains unclear. This study aimed to characterize circulating citrullinated Histone H3 (H3cit) and Peptidyl Arginase Deiminase 4 (PAD4) in ESRD patients undergoing transplantation and evaluate the ability of their neutrophils to release NETs.This prospective cohort study included 80 healthy donors and 105 ESRD patients, out of which 95 received a transplant. H3cit and PAD4 circulating concentration was determined by enzyme-linked immunosorbent assay in healthy donors and ESRD patients at the time of enrollment. An additional measurement was carried out within the first 6 months after transplant surgery. In vitro NET formation assays were performed in neutrophils isolated from healthy donors, ESRD patients, and transplant recipients.H3cit and PAD4 levels were significantly higher in ESRD patients (H3cit, 14.38 ng/mL [5.78-27.13]; PAD4, 3.22 ng/mL [1.21-6.82]) than healthy donors (H3cit, 6.45 ng/mL [3.30-11.65], P < .0001; PAD4, 2.0 ng/mL [0.90-3.18], P = .0076). H3cit, but not PAD4, increased after transplantation, with 44.2% of post-transplant patients exhibiting high levels (≥ 27.1 ng/mL). In contrast, NET release triggered by phorbol 12-myristate 13-acetate was higher in neutrophils from ESRD patients (70.0% [52.7-94.6]) than healthy donors (32.2% [24.9-54.9], P < .001) and transplant recipients (19.5% [3.5-65.7], P < .05).The restoration of renal function due to transplantation could not reduce circulating levels of H3cit and PAD4 in ESRD patients. Furthermore, circulating H3cit levels were significantly increased after transplantation. Neutrophils from transplant recipients exhibit a reduced ability to form NETs.

Prophylactic fresh frozen plasma and platelet transfusion have a prothrombotic effect in patients with liver disease

BACKGROUND AND AIMS

Patients with liver disease acquire complex changes in their hemostatic system, resulting in prolongation of the international normalized ratio and thrombocytopenia. Abnormalities in these tests are commonly corrected with fresh frozen plasma (FFP) or platelet transfusions before invasive procedures. Whether these prophylactic transfusions are beneficial and truly indicated is increasingly debated. In this study, we studied ex vivo effects of FFP and platelet transfusions in patients with liver disease-associated hemostatic changes in a real-life clinical setting.

METHODS

We included 19 patients who were deemed to require prophylactic FFP transfusion by their treating physician and 13 that were prescribed platelet transfusion before a procedure. Hemostatic status was assessed in blood samples taken before and after transfusion and compared with healthy controls (n = 20).

RESULTS

Ex vivo thrombin generation was preserved in patients with liver disease before FFP transfusion. Following FFP transfusion, both in and ex vivo thrombin generation significantly increased, as evidenced by a 92% and 38% increase in thrombin-antithrombin and prothrombin fragment 1 + 2 levels, respectively, and a 20% increase in endogenous thrombin potential. Platelet counts increased from 28 [21-41] × 109 /L before to 43 [39-64] × 109 /L after platelet transfusion (P < .01), and was accompanied by increases in in vivo markers of hemostatic activation.

CONCLUSIONS

FFP and platelet transfusion resulted in increased thrombin generation and platelet counts in patients with liver disease, indicating a prothrombotic effect. However, whether all transfusions were truly indicated and had a clinically relevant effect is questionable.

Donor-specific cell-free DNA as a biomarker in liver transplantation: A review

Due to advances in modern medicine, liver transplantation has revolutionised the prognosis of many previously incurable liver diseases. This progress has largely been due to advances in immunosuppressant therapy. However, despite the judicious use of immunosuppression, many liver transplant recipients still experience complications such as rejection, which necessitates diagnosis via invasive liver biopsy. There is a clear need for novel, minimally-invasive tests to optimise immunosuppression and improve patient outcomes. An emerging biomarker in this ''precision medicine'' liver transplantation field is that of donor-specific cell free DNA. In this review, we detail the background and methods of detecting this biomarker, examine its utility in liver transplantation and discuss future research directions that may be most impactful.

In vitro hypercoagulability and ongoing in vivo activation of coagulation and fibrinolysis in COVID-19 patients on anticoagulation

BACKGROUND

COVID-19 is associated with a substantial risk of venous thrombotic events, even in the presence of adequate thromboprophylactic therapy.

OBJECTIVES

We aimed to better characterize the hypercoagulable state of COVID-19 patients in patients receiving anticoagulant therapy.

METHODS

We took plasma samples of 23 patients with COVID-19 who were on prophylactic or intensified anticoagulant therapy. Twenty healthy volunteers were included to establish reference ranges.

RESULTS

COVID-19 patients had a mildly prolonged prothrombin time, high von Willebrand factor levels and low ADAMTS13 activity. Most rotational thromboelastometry parameters were normal, with a hypercoagulable maximum clot firmness in part of the patients. Despite detectable anti-activated factor X activity in the majority of patients, ex vivo thrombin generation was normal, and in vivo thrombin generation elevated as evidenced by elevated levels of thrombin-antithrombin complexes and D-dimers. Plasma levels of activated factor VII were lower in patients, and levels of the platelet activation marker soluble CD40 ligand were similar in patients and controls. Plasmin-antiplasmin complex levels were also increased in patients despite an in vitro hypofibrinolytic profile.

CONCLUSIONS

COVID-19 patients are characterized by normal in vitro thrombin generation and enhanced clot formation and decreased fibrinolytic potential despite the presence of heparin in the sample. Anticoagulated COVID-19 patients have persistent in vivo activation of coagulation and fibrinolysis, but no evidence of excessive platelet activation. Ongoing activation of coagulation despite normal to intensified anticoagulant therapy indicates studies on alternative antithrombotic strategies are urgently required.

Plasma Nucleosomes in Primary Breast Cancer

Simple Summary

Nucleosomes composed of DNA and histone proteins enter the extracellular space and end eventually in the circulation when cells die. In blood plasma, they could represent a nonspecific marker of cell death, potentially useful for noninvasive monitoring of cancer. The aim of this study was to analyze circulating nucleosomes in relation to patient/tumor characteristics and prognosis in nonmetastatic breast cancer. This study included 92 patients with breast cancer treated with surgery. Plasma nucleosomes were detected in samples taken in the morning on the day of surgery. Circulating nucleosomes were positively associated with the systemic inflammation but not with other patient/tumor characteristics. Patients with lower nucleosomes had lower risk of disease recurrence compared to patients with higher nucleosomes. Our data suggest that plasma nucleosomes in nonmetastatic breast cancer are associated with systemic inflammation and might have a prognostic value. The underlying mechanisms require further studies.

Abstract

When cells die, nucleosomes composed of DNA and histone proteins enter the extracellular space and end eventually in the circulation. In plasma, they might serve as a nonspecific marker of cell death, potentially useful for noninvasive monitoring of tumor dynamics. The aim of this study was to analyze circulating nucleosomes in relation to patient/tumor characteristics and prognosis in primary breast cancer. This study included 92 patients with breast cancer treated with surgery for whom plasma isolated was available in the biobank. Plasma nucleosomes were detected in samples taken in the morning on the day of surgery using Cell Death Detection ELISA kit with anti-histone and anti-DNA antibodies. Circulating nucleosomes were positively associated with the systemic inflammatory index (SII), but not with other patient/tumor characteristics. Patients with high SII in comparison to low SII had higher circulating nucleosomes (by 59%, p = 0.02). Nucleosomes correlated with plasma plasminogen activator inhibitor-1, IL-15, IL-16, IL-18, and hepatocyte growth factor. Patients with lower nucleosomes had significantly better disease-free survival (HR = 0.46, p = 0.05). In a multivariate analysis, nucleosomes, hormone receptor status, HER2 status, lymph node involvement, and tumor grade were independent predictors of disease-free survival. Our data suggest that plasma nucleosomes in primary breast cancer are associated with systemic inflammation and might have a prognostic value. The underlying mechanisms require further studies.

Netting Liver Disease: Neutrophil Extracellular Traps in the Initiation and Exacerbation of Liver Pathology

The liver plays a vital role in the immune system. Its unique position in the portal circulation and the architecture of the hepatic sinusoids, in combination with the wide-ranged population of immunocompetent cells, make the liver function as an immune filter. To aid in pathogen clearance, once challenged, the liver initiates the rapid recruitment of a wide variety of inflammatory cells, including neutrophils. These neutrophils, in conjunction with platelets, facilitate the release of neutrophil extracellular traps (NETs), which are web-like structures of decondensed nuclear DNA, histones, and neutrophil proteins. NETs function as both a physical and a chemical barrier, binding and killing pathogens circulating in the blood stream. In addition to their antimicrobial role, NETs also bind platelets, activate coagulation, and exacerbate host inflammatory response. This interplay between inflammation and coagulation drives microvascular occlusion, ischemia, and (sterile) damage in liver disease. Although direct clinical evidence of this interplay is scarce, preliminary studies indicate that NETs contribute to progression of liver disease and (thrombotic) complications. Here, we provide an overview of the pathological mechanisms of NETs in liver disease. In addition, we summarize clinical evidence for NETs in different disease etiologies and complications of liver disease and discuss the possible implications for the use of NETs as a diagnostic marker and a therapeutic target in liver disease.

Increased Cell-Free DNA Plasma Concentration Following Liver Transplantation Is Linked to Portal Hepatitis and Inferior Survival

Donor organ quality is crucial for transplant survival and long-term survival of patients after liver transplantation. Besides bacterial and viral infections, endogenous damage-associated molecular patterns (DAMPs) can stimulate immune responses. Cell-free DNA (cfDNA) is one such DAMP that exhibits highly proinflammatory effects via DNA sensors. Herein, we measured cfDNA after liver transplantation and found elevated levels when organs from resuscitated donors were transplanted. High levels of cfDNA were associated with high C-reactive protein, leukocytosis as well as granulocytosis in the recipient. In addition to increased systemic immune responses, portal hepatitis was observed, which was associated with increased interface activity and a higher numbers of infiltrating neutrophils and eosinophils in the graft. In fact, the cfDNA was an independent significant factor in multivariate analysis and increased concentration of cfDNA was associated with inferior 1-year survival. Moreover, cfDNA levels were found to be decreased significantly during the postoperative course when patients underwent continuous veno-venous haemofiltration. In conclusion, patients receiving livers from resuscitated donors were characterised by high postoperative cfDNA levels. Those patients showed pronounced portal hepatitis and systemic inflammatory responses in the short term leading to a high mortality. Further studies are needed to evaluate the clinical relevance of cfDNA clearance by haemoadsorption and haemofiltration in vitro and in vivo.

Neutrophil Extracellular Traps and Liver Disease

Neutrophil extracellular traps, or NETs, are heterogenous, filamentous structures which consist of extracellular DNA, granular proteins, and histones. NETs are extruded by a neutrophil in response to various stimuli. Although NETs were initially implicated in immune defense, subsequent studies have implicated NETs in a spectrum of disease processes, including autoimmune disease, thrombosis, and cancer. NETs also contribute to the pathogenesis of several common liver diseases, including alcohol-associated liver disease and portal hypertension. Although there is much interest in the therapeutic potential of NET inhibition, future clinical applications must be balanced against potential increased risk of infection.

Extended hypothermic oxygenated machine perfusion enables ex situ preservation of porcine livers for up to 24 hours

Background & Aims

End-ischemic hypothermic oxygenated machine perfusion (HOPE) of the donor liver for 1-2 h mitigates ischemia-reperfusion injury during subsequent liver transplantation. Extended preservation time may be preferred to facilitate difficult recipient hepatectomy or to optimize logistics. We therefore investigated whether end-ischemic dual HOPE (DHOPE) could extend preservation time for up to 24 h using a porcine liver reperfusion model.

Methods

Following 30 min warm ischemia, porcine livers were subjected to 2 h static cold storage (SCS), followed by 2 h, 6 h, or 24 h DHOPE (n = 6 per group). Subsequent normothermic reperfusion was performed for 4 h using autologous blood. Two livers preserved by 24 h SCS served as additional controls. A proof of principle confirmation was carried out in 2 discarded human livers subjected to extended DHOPE. Hepatocellular and cholangiocyte injury and function were assessed. Oxidative stress levels and histology were compared between groups.

Results

Perfusion flows remained stable during DHOPE, regardless of duration. After normothermic reperfusion, livers perfused for 24 h by DHOPE had similar lactate clearance, blood pH, glucose, and alanine aminotransferase levels, and biliary pH, bicarbonate, and LDH levels, as livers perfused for 2 h and 6 h. Levels of malondialdehyde and high-mobility group box 1 in serum and liver parenchyma were similar for all groups. Histological analysis of bile ducts and liver parenchyma revealed no differences between the groups. Extended DHOPE in discarded human livers preserved hepatocellular and cholangiocyte function and histology after reperfusion. In contrast, livers preserved by 24 h SCS were non-functioning.

Conclusion

Extended end-ischemic DHOPE enabled successful preservation of porcine and discarded human donor livers for up to 24 h. Extended DHOPE enables safe extension of preservation time, which may facilitate allocation and transplantation from a logistical perspective, and further expand the donor pool.

Lay summary

It has been suggested that preserving liver grafts with a technique called (dual) hypothermic oxygenated machine perfusion ([D]HOPE) leads to better outcomes after transplantation than if livers are stored on ice, especially if an organ is of lesser quality. In this study, we showed that DHOPE could be used to preserve liver grafts for up to 24 h. This extended procedure could be used globally to facilitate transplantation and expand the donor pool.

Increased Circulating Levels of Neutrophil Extracellular Traps During Cardiopulmonary Bypass

Background

The intensity of inflammatory response triggered by cardiopulmonary bypass (CPB) during cardiac surgery has been associated with adverse outcomes. Neutrophils might contribute to organ injury through the liberation of DNA histone-based structures named “neutrophil extracellular traps” (NETs). Our objective was to assess circulating NETs levels before and after cardiac surgery in low-risk and high-risk patients.

Methods

This prospective cohort study included 2 groups of patients undergoing elective cardiac surgery with the use of CPB. The first group consisted of low-risk patients (European System for Cardiac Operative Risk Evaluation II ≤ 1%), and the second group included high-risk patients (European System for Cardiac Operative Risk Evaluation II ≥ 5%). Blood samples were drawn pre-CPB and 3 hours post-CPB separation. Measurements of circulating NETs, interleukin-6, C-reactive protein, myeloperoxidase, citrullinated histone 3, and pentraxin-related protein 3 levels were performed at each time point.

Results

Twenty-four patients, 12 high-risk and 12 low-risk patients, were included. Circulating NETs measurements changed from a median of 0.054 before CPB to 0.084 at 3 hours post-CPB separation, with a median increase of 0.037 (P < 0.001) per patient. No difference was noted between the high-risk and low-risk groups. A linear relationship was found between the circulating NETs measurements 3 hours post-CPB and CPB duration (ß = 0.047; confidence interval, 0.012-0.081; P = 0.01 R² = 0.27). A correlation was found between the change in NETs with citrullinated histone 3 and myeloperoxidase levels, but not between NETs and other inflammatory biomarkers.

Conclusions

Circulating NETs measurements increases during cardiac surgery with postsurgical levels proportional to CPB duration. The clinical significance of NETs production during cardiac surgery should be further investigated.

Plasma levels of circulating DNA are associated with outcome, but not with activation of coagulation in decompensated cirrhosis and ACLF

Acute-on-chronic liver failure (ACLF) is a recently (re)defined syndrome of acute decompensation of cirrhosis that presents with extrahepatic organ failure(s) and poor outcome. Given the prominent role of inflammation and activation of coagulation in ACLF, we hypothesized that ACLF might be characterized by the generation of neutrophil extracellular traps (NETs), that could drive both activation of coagulation and progression of organ failure.

Methods

We measured markers of circulating DNA, activation of coagulation, inflammation, and oxidative stress in 52 patients with acute decompensation (AD) of cirrhosis and 57 patients with ACLF on admission, and compared levels with 40 healthy controls.

Results

All analytes were higher in patients compared to controls. Plasma levels of cell-free DNA, but not of the specific NET marker myeloperoxidase-DNA complexes were higher in patients with ACLF compared to AD cirrhosis. In addition, TAT complexes (coagulation), IL-6 (inflammation), and TBARS (oxidative stress) were higher in ACLF compared to AD. Markers for activation of coagulation were not associated with circulating DNA, IL-6, or TBARS. In contrast, levels of circulating DNA, IL-6, and TBARS were higher in patients with more severe disease, higher in patients with organ failure, and higher in patients that died within 30 days of admission. Importantly, myeloperoxidase-DNA levels did not differ between patients with complications and poor outcome.

Conclusions

Collectively, we show that cell-free DNA, inflammation, and oxidative stress are associated with outcomes in AD and ACLF, but not with activation of coagulation. Our data argue against a role of NETs in activation of coagulation and in progression of organ failure in patients with AD and ACLF.

Lay summary

Acute-on-chronic liver failure is a devastating syndrome that can follow acute decompensation of chronic liver disease. Herein, we demonstrate that these patients accumulate DNA released from dying cells in their blood, and that the quantity of this DNA is related to the outcome of disease. We also show that outcome of disease is not related to recently described neutrophil extracellular traps, which have been shown in animal models to play vital roles in the progression of liver diseases.

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Levels of circulating DNA, IL6, and TBARS are higher in patients with ACLF than in patients with AD

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Circulating DNA, IL6, and TBARS are higher in patients with organ failure and those who died

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Circulating DNA, IL6, and TBARS are not correlated with markers of activation of coagulation

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The neutrophil extracellular trap marker MPO-DNA was not related to coagulation or outcome

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DNA- or NET-related coagulation does not appear to drive ACLF progression

Abdominal Organ Transplantation: Noteworthy Literature in 2018

A PubMed search revealed 1382 articles on pancreatic transplantation, 781 on intestinal transplantation, more than 7200 on kidney transplantation, and more than 5500 on liver transplantation published between January 1, 2018, and December 31, 2018. After narrowing the list down to human studies, 436 pancreatic, 302 intestinal, 1920 liver, and more than 2000 kidney transplantation studies were screened for inclusion in this review.