Systemic versus localized coagulation activation contributing to organ failure in critically ill patients

Efficacy and Safety of Direct Oral Anticoagulants Versus Warfarin in Patients With Atrial Fibrillation and Liver Cirrhosis

OBJECTIVE

Comparing direct oral anticoagulants (DOACs) and warfarin's efficacy and safety in patients with nonvalvular atrial fibrillation (AF) and liver cirrhosis (LC).

BACKGROUND

Evidence of the pharmacodynamics of DOACs is limited in patients with AF and LC.

METHODS

A retrospective cohort study was conducted in the largest hospital system in Taiwan, involving patients with AF and LC for the years 2012 to 2021. Hazards of thromboembolic events (ischemic stroke, transient ischemic attack, and systemic embolism), intracranial hemorrhage, gastrointestinal, major bleeding, and all-cause mortality were investigated with a new-user, active comparator design. Inverse probability of treatment weighting was applied to balance potential confounders between treatment groups.

RESULTS

In total, 478 DOAC users and 247 warfarin users were included. DOACs and warfarin demonstrated similar trends in preventing thromboembolic events, namely ischemic stroke [adjusted hazard ratio (aHR), 1.05 (95% CI: 0.42-2.61)], transient ischemic attack [aHR, 1.36 (95% CI: 0.18-10.31)], and systemic embolism [aHR, 0.49 (95% CI: 0.14-1.70)]. DOAC use was associated with a similar risk of intracranial hemorrhage [aHR, 0.65 (95% CI: 0.26-1.59)] and gastrointestinal bleeding [aHR, 0.64 (95% CI: 0.39-1.03)], a decreased risk of major bleeding [aHR, 0.64 (95% CI: 0.42-0.99)], and a reduction in mortality [aHR, 0.73 (95% CI: 0.54-0.99)]. DOAC users exhibited a significant reduction in major bleeding risk in patients with Child-Pugh class A (aHR, 0.48; 95% CI: 0.33-0.70).

CONCLUSIONS

DOACs showed potential safety advantages over warfarin for patients with nonvalvular AF and LC, particularly in reducing major bleeding risk in those with Child-Pugh class A.

Fibrinolysis associated proteins and lipopolysaccharide bioactivity in plasma and cerebrospinal fluid in multiple sclerosis

The coagulation cascade and fibrinolysis have links with neuroinflammation and increased activation of the coagulation system has been reported in MS patients. We quantified levels of D-dimer, tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and the bioactivity of bacterial lipopolysaccharide (LPS) in cerebrospinal fluid (CSF) and plasma from newly diagnosed untreated MS patients and controls. These molecules showed multiple correlations with each other as well as with age, HLA-DRB1*15:01, body-mass-index and CSF IgG. Our results confirm previous findings of increased plasma PAI-1 and LPS in MS patients compared to controls indicating changes in platelet function and gut permeability in MS.

Acute respiratory distress syndrome, acute kidney injury, and mortality after trauma are associated with increased circulation of syndecan-1, soluble thrombomodulin, and receptor for advanced glycation end products

BACKGROUND

Disruption of the vascular endothelium and endothelial glycocalyx (EG) has been described after severe trauma. Plasma has been suggested to restore microvascular integrity by preservation and repair of the EG. We sought to evaluate whether plasma administered in a 1:1:1 ratio was associated with less endothelial marker circulation than a 1:1:2 ratio.

METHODS

This is a secondary analysis of the PROPPR trial, which investigated post-traumatic resuscitation with platelets, plasma, and red blood cells in a 1:1:1 ratio compared with a 1:1:2 ratio. Syndecan-1, soluble thrombomodulin (sTM), and receptor for advanced glycation end products (RAGE) were quantified for each treatment group on admission and at 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, and 72 hours. Patients were excluded if they did not survive longer than 3 hours or had data from fewer than two time points.

RESULTS

Three hundred eight patients in the 1:1:1 group and 291 in the 1:1:2 group were analyzed. There were no statistically significant differences in syndecan-1, sTM, or RAGE between treatment groups at any time point ( p > 0.05). Patients who developed acute respiratory distress syndrome, acute kidney injury, and death had significantly elevated biomarker expression at most time points when compared with patients who did not develop these sequelae ( p < 0.05).

CONCLUSION

Administration of FFP in a 1:1:1 ratio does not consistently affect circulation of endothelial biomarkers following significant trauma when compared with a 1:1:2 ratio. The development of post-traumatic ARDS, AKI, and death was associated with increased endothelial biomarker circulation.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.

PAI-1 as a critical factor in the resolution of sepsis and acute kidney injury in old age

Elevated plasma levels of plasminogen activator inhibitor type 1 (PAI-1) are documented in patients with sepsis and levels positively correlate with disease severity and mortality. Our prior work demonstrated that PAI-1 in plasma is positively associated with acute kidney injury (AKI) in septic patients and mice. The objective of this study was to determine if PAI-1 is causally related to AKI and worse sepsis outcomes using a clinically-relevant and age-appropriate murine model of sepsis. Sepsis was induced by cecal slurry (CS)-injection to wild-type (WT, C57BL/6) and PAI-1 knockout (KO) mice at young (5-9 months) and old (18-22 months) age. Survival was monitored for at least 10 days or mice were euthanized for tissue collection at 24 or 48 h post-insult. Contrary to our expectation, PAI-1 KO mice at old age were significantly more sensitive to CS-induced sepsis compared to WT mice (24% vs. 65% survival, p = 0.0037). In comparison, loss of PAI-1 at young age had negligible effects on sepsis survival (86% vs. 88% survival, p = 0.8106) highlighting the importance of age as a biological variable. Injury to the kidney was the most apparent pathological consequence and occurred earlier in aged PAI-1 KO mice. Coagulation markers were unaffected by loss of PAI-1, suggesting thrombosis-independent mechanisms for PAI-1-mediated protection. In summary, although high PAI-1 levels are clinically associated with worse sepsis outcomes, loss of PAI-1 rendered mice more susceptible to kidney injury and death in a CS-induced model of sepsis using aged mice. These results implicate PAI-1 as a critical factor in the resolution of sepsis in old age.

Interrelationship between COVID-19 and Coagulopathy: Pathophysiological and Clinical Evidence

Since the first description of COVID-19 infection, among clinical manifestations of the disease, including fever, dyspnea, cough, and fatigue, it was observed a high incidence of thromboembolic events potentially evolving towards acute respiratory distress syndrome (ARDS) and COVID-19-associated-coagulopathy (CAC). The hypercoagulation state is based on an interaction between thrombosis and inflammation. The so-called CAC represents a key aspect in the genesis of organ damage from SARS-CoV-2. The prothrombotic status of COVID-19 can be explained by the increase in coagulation levels of D-dimer, lymphocytes, fibrinogen, interleukin 6 (IL-6), and prothrombin time. Several mechanisms have been hypothesized to explain this hypercoagulable process such as inflammatory cytokine storm, platelet activation, endothelial dysfunction, and stasis for a long time. The purpose of this narrative review is to provide an overview of the current knowledge on the pathogenic mechanisms of coagulopathy that may characterize COVID-19 infection and inform on new areas of research. New vascular therapeutic strategies are also reviewed.

ENDOTHELIAL GLYCOCALYX SHEDDING IN INTRA-ABDOMINAL SEPSIS: A FEASIBILITY STUDY

ABSTRACT

Background: The endothelial glycocalyx layer (EGL) is a complex meshwork of glycosaminoglycans and proteoglycans that protect the vascular endothelium. Cleavage or shedding of EGL-specific biomarkers, such as hyaluronic acid (HA) and syndecan-1 (SDC-1, CD138) in plasma, have been shown to be associated with poor clinical outcomes. However, it is unclear whether levels of circulating EGL biomarkers are representative of the EGL injury within the tissues. The objective of the present feasibility study was to describe a pathway for plasma and tissue procurement to quantify EGL components in a cohort of surgical patients with intra-abdominal sepsis. We sought to compare differences between tissue and plasma EGL biomarkers and to determine whether EGL shedding within the circulation and/or tissues correlated with clinical outcomes. Methods: This was a prospective, observational, single-center feasibility study of adult patients (N = 15) with intra-abdominal sepsis, conducted under an approved institutional review boards. Blood and resected tissue (pathologic specimen and unaffected peritoneum) samples were collected from consented subjects at the time of operation and 24-48 hours after surgery. Endothelial glycocalyx layer biomarkers (i.e., HA and SDC-1) were quantified in both tissue and plasma samples using a CD138 stain and ELISA kit, respectively. Pairwise comparisons were made between plasma and tissue levels. In addition, we tested the relationships between measured EGL biomarkers and clinical status and patient outcomes. Results: Fifteen patients with intra-abdominal sepsis were enrolled in the study. Elevations in EGL-specific circulating biomarkers (HA, SDC-1) were positively correlated with postoperative SOFA scores and weakly associated with resuscitative volumes at 24 hours. Syndecan-1 levels from resected pathologic tissue significantly correlated with SOFA scores at all time points ( R = 0.69 and P < 0.0001) and positively correlated with resuscitation volumes at 24 hours ( R = 0.41 and P = 0.15 for t = 24 hours). Tissue and circulating HA and SDC-1 positively correlated with SOFA >6. Conclusions: Elevations in both circulating and tissue EGL biomarkers were positively correlated with postoperative SOFA scores at 24 hours, with resected pathologic tissue EGL levels displaying significant correlations with SOFA scores at all time points. Tissue and circulating EGL biomarkers were positively correlated at higher SOFA scores (SOFA > 6) and could be used as indicators of resuscitative needs within 24 hours of surgery. The present study demonstrates the feasibility of tissue and plasma procurement in the operating room, although larger studies are needed to evaluate the predictive value of these EGL biomarkers for patients with intra-abdominal sepsis.

Endothelial Cell Phenotypes Demonstrate Different Metabolic Patterns and Predict Mortality in Trauma Patients

In trauma patients, shock-induced endotheliopathy (SHINE) is associated with a poor prognosis. We have previously identified four metabolic phenotypes in a small cohort of trauma patients (N = 20) and displayed the intracellular metabolic profile of the endothelial cell by integrating quantified plasma metabolomic profiles into a genome-scale metabolic model (iEC-GEM). A retrospective observational study of 99 trauma patients admitted to a Level 1 Trauma Center. Mass spectrometry was conducted on admission samples of plasma metabolites. Quantified metabolites were analyzed by computational network analysis of the iEC-GEM. Four plasma metabolic phenotypes (A-D) were identified, of which phenotype D was associated with an increased injury severity score (p < 0.001); 90% (91.6%) of the patients who died within 72 h possessed this phenotype. The inferred EC metabolic patterns were found to be different between phenotype A and D. Phenotype D was unable to maintain adequate redox homeostasis. We confirm that trauma patients presented four metabolic phenotypes at admission. Phenotype D was associated with increased mortality. Different EC metabolic patterns were identified between phenotypes A and D, and the inability to maintain adequate redox balance may be linked to the high mortality.

SHock-INduced Endotheliopathy (SHINE): A mechanistic justification for viscoelastography-guided resuscitation of traumatic and non-traumatic shock

Irrespective of the reason for hypoperfusion, hypocoagulable and/or hyperfibrinolytic hemostatic aberrancies afflict up to one-quarter of critically ill patients in shock. Intensivists and traumatologists have embraced the concept of SHock-INduced Endotheliopathy (SHINE) as a foundational derangement in progressive shock wherein sympatho-adrenal activation may cause systemic endothelial injury. The pro-thrombotic endothelium lends to micro-thrombosis, enacting a cycle of worsening perfusion and increasing catecholamines, endothelial injury, de-endothelialization, and multiple organ failure. The hypocoagulable/hyperfibrinolytic hemostatic phenotype is thought to be driven by endothelial release of anti-thrombogenic mediators to the bloodstream and perivascular sympathetic nerve release of tissue plasminogen activator directly into the microvasculature. In the shock state, this hemostatic phenotype may be a counterbalancing, yet maladaptive, attempt to restore blood flow against a systemically pro-thrombotic endothelium and increased blood viscosity. We therefore review endothelial physiology with emphasis on glycocalyx function, unique biomarkers, and coagulofibrinolytic mediators, setting the stage for understanding the pathophysiology and hemostatic phenotypes of SHINE in various etiologies of shock. We propose that the hyperfibrinolytic phenotype is exemplified in progressive shock whether related to trauma-induced coagulopathy, sepsis-induced coagulopathy, or post-cardiac arrest syndrome-associated coagulopathy. Regardless of the initial insult, SHINE appears to be a catecholamine-driven entity which early in the disease course may manifest as hyper- or hypocoagulopathic and hyper- or hypofibrinolytic hemostatic imbalance. Moreover, these hemostatic derangements may rapidly evolve along the thrombohemorrhagic spectrum depending on the etiology, timing, and methods of resuscitation. Given the intricate hemochemical makeup and changes during these shock states, macroscopic whole blood tests of coagulative kinetics and clot strength serve as clinically useful and simple means for hemostasis phenotyping. We suggest that viscoelastic hemostatic assays such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are currently the most applicable clinical tools for assaying global hemostatic function-including fibrinolysis-to enable dynamic resuscitation with blood products and hemostatic adjuncts for those patients with thrombotic and/or hemorrhagic complications in shock states.

Long-Term Health Consequences of SARS-CoV-2: Assumptions Based on SARS-CoV-1 and MERS-CoV Infections

Coronavirus Disease-2019 (COVID-19) is one of the worst pandemics in the history of the world. It is the third coronavirus disease that has afflicted humans in a short span of time. The world appears to be recovering from the grasp of this deadly pandemic; still, its post-disease health effects are not clearly understood. It is evident that the vast majority of COVID-19 patients usually recovered over time; however, disease manifestation is reported to still exist in some patients even after complete recovery. The disease is known to have left irreversible damage(s) among some patients and these damages are expected to cause mild or severe degrees of health effects. Apart from the apparent damage to the lungs caused by SARS-CoV-1, MERS-CoV, and SARS-CoV-2 infection, COVID-19-surviving patients display a wide spectrum of dysfunctions in different organ systems that is similar to what occurs with SARS-CoV-1 and MERS diseases. The major long COVID-19 manifestations include the following aspects: (1) central nervous system, (2) cardiovascular, (3) pulmonary, (4) gastrointestinal, (5) hematologic, (6) renal and (7) psycho-social systems. COVID-19 has a disease display manifestation in these organs and its related systems amongst a large number of recovered cases. Our study highlights the expected bodily consequences of the pandemic caused by SARS-CoV-2 infection based on the understanding of the long-term effects of SARS-CoV-1 and MERS-CoV.

Endothelial Activation and Microcirculatory Disorders in Sepsis

The vascular endothelium is crucial for the maintenance of vascular homeostasis. Moreover, in sepsis, endothelial cells can acquire new properties and actively participate in the host's response. If endothelial activation is mostly necessary and efficient in eliminating a pathogen, an exaggerated and maladaptive reaction leads to severe microcirculatory damage. The microcirculatory disorders in sepsis are well known to be associated with poor outcome. Better recognition of microcirculatory alteration is therefore essential to identify patients with the worse outcomes and to guide therapeutic interventions. In this review, we will discuss the main features of endothelial activation and dysfunction in sepsis, its assessment at the bedside, and the main advances in microcirculatory resuscitation.

Thrombocytopathy vs Platelet hyper-reactivity in COVID-19: diverse pathologies, disease outcomes and therapeutic implications

Coagulopathy is an evident complication of COVID-19 with predominance of a prothrombotic state. Platelet activation plays a key role. The terms "hyper-reactivity" and "hyperactivity" used in recent literature may not be clear or sufficient to explain the pathological events involved in COVID-related thrombosis (CRT). Inflammation may play a bigger role compared to thrombosis in COVID-related mortality because a smaller percentage of patients with COVID-19 die due to direct effects of thrombosis. Not all COVID-19 patients have thrombocytopenia and a few show thrombocytosis. We believe the platelet pathology is more complex than just activation or hyper-activation, particularly due to the platelets' role in inflammation. Understanding the pathology and consequences of platelets' role may help optimize management strategies and diminish CRT-associated morbidity and mortality. In this viewpoint report, we examine the published evidence of platelet hyper-reactivity in COVID-19 with a focused analysis of the key pathologies, diverse alterations, disease outcomes, and therapeutic targets. We believe that COVID-19 is a disease of inflammation and pathologic platelets, and based on the complexity and diverse pathologies, we propose the term "thrombocytopathy" as a more reflective term of the platelets' involvement in COVID-19. In our opinion, thrombocytopathy is the unpredictable pathologic alterations of platelets in function, morphology and number, caused by different factors with a variety of presentations.

COVID-19 associated coagulopathy is correlated with increased age and markers of inflammation response

Background: The severe manifestations of the coronavirus disease 2019 (COVID-19) are linked to viral hyper-inflammation, cytokine release syndrome and subsequent coagulation disturbances. The most common coagulation abnormality observed in COVID-19 patients is the elevation of the plasma levels of D-dimers. The aim of this study was to evaluate the characteristics of COVID-19-associated inflammatory syndrome and coagulopathy, in correlation with disease severity.

Methods: We performed a cross-sectional study, enrolling all consecutive COVID-19 patients treated in the Adulti 3 Department of the Prof. Dr. Matei Bals National Institute of Infectious Diseases, Bucharest, Romania, between 1st march and 30th September 2020. We recorded clinical and epidemiological characteristics, inflammatory markers, coagulation abnormalities and lymphocyte count. The severity of lung involvement was assessed using native Computed Tomography examination.

Results: We included 106 patients with SARS-COV2 infection, 50 males (47.2%) and 56 females (52.8%), age range 14-91 years. All markers of inflammation were increased in our study in patients with severe disease, as were lactate dehydrogenase, monocyte distribution width, and neutrophil-to-lymphocyte ratio. An elevated level of serum D-dimers was observed in approximately half of our subjects and was associated with disease severity. Our best linear regression model for predicting COVID-19 coagulopathy (manifested as abnormal D-dimer levels) included age, fibrinogen, and lymphocyte count.

Conclusion: Our findings emphasize the association between COVID-19 coagulopathy and the presence of systemic inflammation. A significant proportion of patients with moderate and severe disease had coagulation abnormalities and these were linked with the presence of inflammation and older age..

Systemic inflammation in COVID‐19 patients may induce various types of venous and arterial thrombosis: A systematic review

COVID‐19 is a global pandemic with a daily increasing number of affected individuals. Thrombosis is a severe complication of COVID‐19 that leads to a worse clinical course with higher rates of mortality. Multiple lines of evidence suggest that hyperinflammation plays a crucial role in disease progression. This review compiles clinical data of COVID‐19 patients who developed thrombotic complications to investigate the possible role of hyperinflammation in inducing hypercoagulation. A systematic literature search was performed using PubMed, Embase, Medline and Scopus to identify relevant clinical studies that investigated thrombotic manifestations and reported inflammatory and coagulation biomarkers in COVID‐19 patients. Only 54 studies met our inclusion criteria, the majority of which demonstrated significantly elevated inflammatory markers. In the cohort studies with control, D‐dimer was significantly higher in COVID‐19 patients with thrombosis as compared to the control. Pulmonary embolism, deep vein thrombosis and strokes were frequently reported which could be attributed to the hyperinflammatory response associated with COVID‐19 and/or to the direct viral activation of platelets and endothelial cells, two mechanisms that are discussed in this review. It is recommended that all admitted COVID‐19 patients should be assessed for hypercoagulation. Furthermore, several studies have suggested that anticoagulation may be beneficial, especially in hospitalized non‐ICU patients. Although vaccines against SARS‐CoV‐2 have been approved and distributed in several countries, research should continue in the field of prevention and treatment of COVID‐19 and its severe complications including thrombosis due to the emergence of new variants against which the efficacy of the vaccines is not yet clear.

Time Course of Hemostatic Disruptions After Traumatic Brain Injury: A Systematic Review of the Literature

Almost two-thirds of patients with severe traumatic brain injury (TBI) develop some form of hemostatic disturbance, which contributes to poor outcome. While the initial head injury often leads to impaired clot formation, TBI is also associated with an increased risk of thrombosis. Most likely there is a progression from early bleeding to a later prothrombotic state. In this paper, we systematically review the literature on the time course of hemostatic disruptions following TBI. A MEDLINE search was performed for TBI studies reporting the trajectory of hemostatic assays over time. The search yielded 5,049 articles, of which 4,910 were excluded following duplicate removal as well as title and abstract review. Full-text assessment of the remaining articles yielded 33 studies that were included in the final review. We found that the first hours after TBI are characterized by coagulation cascade dysfunction and hyperfibrinolysis, both of which likely contribute to lesion progression. This is then followed by platelet dysfunction and decreased platelet count, the clinical implication of which remains unclear. Later, a poorly defined prothrombotic state emerges, partly due to fibrinolysis shutdown and hyperactive platelets. In the clinical setting, early administration of the antifibrinolytic agent tranexamic acid has proved effective in reducing head-injury-related mortality in a subgroup of TBI patients. Further studies evaluating the time course of hemostatic disruptions after TBI are warranted in order to identify windows of opportunity for potential treatment options.

Hypercoagulability in COVID-19: A review of the potential mechanisms underlying clotting disorders

Severe acute respiratory syndrome coronavirus-2 has emerged as a new viral pandemic, causing Coronavirus disease 2019 (COVID-19) leading to a wide array of symptoms ranging from asymptomatic to severe respiratory failure. However, coagulation disorders have been found in some patients infected with SARS-CoV-2, leading to either a clotting disorder or hemorrhage. Several mechanisms attempt to explain the mechanism behind the pro-coagulant state seen with COVID-19 patients, including different receptor binding, cytokine storm, and direct viral endothelial damage. SARS-CoV-2 has also been recently found to bind to CLEC4M receptor, a receptor that participates in the clearance of von Willebrand Factor and Factor VIII. The competitive binding of SARS-CoV-2 to CLEC4M could lead to decreased clearance, and therefore a promotion of a pro-coagulative state; however, an experimental study needs to be done to prove such an association.

Systemic Coagulopathy in Hospitalized Patients With Coronavirus Disease 2019: A Systematic Review and Meta-Analysis

Coagulation activation has been reported in several cohorts of patients Coronavirus Disease 2019 (COVID-19). However, the true burden of systemic coagulopathy in COVID-19 remains unknown. In this systematic review and meta-analysis, we performed a literature search using PubMed, EMBASE, and Cochrane Database to identify studies that reported the prevalence of systemic coagulopathy using established criteria in patients with COVID-19. The primary outcome was the prevalence of systemic coagulopathy (disseminated intravascular coagulation [DIC] and/or sepsis-induced coagulopathy [SIC]). Pooled prevalences and 95% confidence intervals [CIs] were calculated using random-effects model. A total of 5 studies including 1210 patients with confirmed COVID-19 were included. The pooled prevalence of systemic coagulopathy was 7.1% (95%CI: 3.2%,15.3%, I² = 93%). The pooled prevalence of DIC (N = 721) and SIC (N = 639) were 4.3% (95%CI 1.7%, 10.4%, I² = 84%) and 16.2% (95%CI: 9.3%, 26.8%, I² = 74%), respectively. Only 2 studies reported the prevalence of elevated D-dimer levels with the pooled prevalence of 84.6% (95%CI: 52.0%,96.5%, I² = 94%). Average D-dimer and fibrinogen levels were remarkably increased, while platelet counts, PT, and aPTT ratios were minimally affected in COVID-19. The estimated prevalence of systemic coagulopathy in patients with COVID-19 was low despite D-dimer elevation in most patients. Relatively low systemic coagulopathy in COVID-19 may contribute to the high incidence of thrombosis rather than bleeding in patients with COVID-19.

Focus on the Gut-Kidney Axis in Health and Disease

The recent new developments in technology with culture-independent techniques including genome sequencing methodologies shed light on the identification of microbiota bacterial species and their role in health and disease. Microbiome is actually reported as an important predictive tool for evaluating characteristic shifts in case of disease. Our present review states the development of different renal diseases and pathologies linked to the intestinal dysbiosis, which impacts on host homeostasis. The gastrointestinal-kidney dialogue provides intriguing features in the pathogenesis of several renal diseases. Without any doubt, investigation of this interconnection consists one of the most cutting-edge areas of research with potential implications on our health.

COVID-19 and Microvascular Disease: Pathophysiology of SARS-CoV-2 Infection With Focus on the Renin-Angiotensin System

The recently described severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected millions of people, with thousands of fatalities. It has prompted global efforts in research, with focus on the pathophysiology of coronavirus disease-19 (COVID-19), and a rapid surge of publications. COVID-19 has been associated with a myriad of clinical manifestations, including the lungs, heart, kidneys, central nervous system, gastrointestinal system, skin, and blood coagulation abnormalities. The endothelium plays a key role in organ dysfunction associated with severe infection, and current data suggest that it is also involved in SARS-CoV-2-induced sepsis. This critical review aimed to address a possible unifying mechanism underlying the diverse complications of COVID-19: microvascular dysfunction, with emphasis on the renin-angiotensin system. In addition, research perspectives are suggested in order to expand understanding of the pathophysiology of the infection.

Understanding immunopathology of severe dengue: lessons learnt from sepsis

Endothelial dysfunction leading to vascular permeability and plasma leakage are characteristic features of severe dengue and sepsis. However, the mechanisms underlying these immune-pathologies remain unclear. The risk of severe dengue and sepsis development depend on patient-related and pathogen-related factors. Additionally, comorbidities increase the risk of severe disease and their incidence hampers correct diagnosis and treatments. To date, there is no efficient therapy to combat severe dengue and sepsis. Here, we discuss the differences and similarities between the pathogenesis of severe dengue and that of bacterial sepsis. We identify gaps in knowledge that need to be better understood in order to move towards the rational development and/or usage of therapeutic strategies to ameliorate severe dengue disease.

Coagulation dysfunction in COVID-19: The interplay between inflammation, viral infection and the coagulation system

COVID-19 is a new pandemic, caused by Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-Cov2) infection and characterized by a broad spectrum of clinical manifestations.

Inflammation and the innate immune system have been recently recognized as pivotal players in the most severe forms, characterized by significantly elevated levels of pro-inflammatory cytokines. In this setting, several studies have also reported the presence of abnormalities in coagulation parameters and platelets count, possibly identifying a subgroup of patients with poor prognosis. Some reports of full-blown thromboembolic events are emerging.

Among the possible mechanisms underlying coagulation dysfunction, the so-called "cytokine storm" seems to play a pivotal role. Other candidate factors include virus-specific mechanisms, related to the virus interaction with renin angiotensin system (RAS) and the fibrinolytic pathway, but also comorbidities affecting these patients.

Coagulation dysfunction is therefore a candidate risk factor for adverse outcomes in COVID-19 and should be carefully addressed in clinical practice.

Unfractionated heparin inhibits histone-mediated coagulation activation and thrombosis in mice

INTRODUCTION

Histones play pivotal roles in the pathophysiology of sepsis. Different studies have reported that unfractionated heparin (UFH) can improve histone-mediated organ dysfunction. However, in such studies, UFH was usually pretreated or injected with histones concurrently, which was obviously inconsistent with clinical practice. Therefore, this study aimed to figure out whether UFH can inhibit histone-induced coagulation activation and thrombosis when histones have caused coagulation disorder already.

METHODS

Male C57/BL6 mice of average weight ~22 g were randomly divided into three groups. The histone group was injected with histones 50 mg/kg through the tail vein. The histone + UFH group was injected with UFH (400 U/kg) through the tail vein 1 h or 6 h after the induction of histones. The control group was injected with equal volume of sterile saline. The lungs were harvested 3 h after UFH administration. In survival studies, mice were treated with UFH (800 U/kg, n = 10) or sterile saline (n = 10) intravenously after histones (75 mg/kg) injection and observed for 7 days.

RESULTS

1) UFH improved survival rate in mice injected with lethal doses of histones; 2) UFH alleviated histone-induced lung injury and pulmonary edema; 3) UFH improved histone-induced endothelial cell injury; 4) UFH improved histone-mediated high expression of TF, PAI-1, fibrinogen and low expression of TM.

CONCLUSION

UFH can effectively attenuate histone-induced lung injury, coagulation activation and thrombosis.

Hemostatic Testing in Critically Ill Infants and Children

Children with critical illness frequently manifest imbalances in hemostasis with risk of consequent bleeding or pathologic thrombosis. Traditionally, plasma-based tests measuring clot formation by time to fibrin clot generation have been the "gold standard" in hemostasis testing. However, these tests are not sensitive to abnormalities in fibrinolysis or in conditions of enhanced clot formation that may lead to thrombosis. Additionally, they do not measure the critical roles played by platelets and endothelial cells. An added factor in the evaluation of these plasma-based tests is that in infants and young children plasma levels of many procoagulant and anticoagulant proteins are lower than in older children and adults resulting in prolonged clot generation times in spite of maintaining a normal hemostatic "balance." Consequently, newer assays directly measuring thrombin generation in plasma and others assessing the stages hemostasis including clot initiation, propagation, and fibrinolysis in whole blood by viscoelastic methods are now available and may allow for a global measurement of the hemostatic system. In this manuscript, we will review the processes by which clots are formed and by which hemostasis is regulated, and the rationale and limitations for the more commonly utilized tests. We will also discuss selected newer tests available for the assessment of hemostasis, their "pros" and "cons," and how they compare to the traditional tests of coagulation in the assessment and management of critically ill children.

Platelets Are Critical Key Players in Sepsis

Host defense against infection is based on two crucial mechanisms: the inflammatory response and the activation of coagulation. Platelets are involved in both hemostasis and immune response. These mechanisms work together in a complex and synchronous manner making the contribution of platelets of major importance in sepsis. This is a summary of the pathophysiology of sepsis-induced thrombocytopenia, microvascular consequences, platelet-endothelial cells and platelet–pathogens interactions. The critical role of platelets during sepsis and the therapeutic implications are also reviewed.

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

Lactobacillus casei CRL 431 improves endothelial and platelet functionality in a pneumococcal infection model

Streptococcus pneumoniae is able to activate coagulation and induce platelet aggregation, both of which are typical responses to systemic inflammation. The interactions between inflammation and coagulation and between soluble adhesion molecules and endothelial cells are important in the pathogenesis of an unbalanced haemostatic system. Therefore, an exaggerated and/or insufficiently controlled haemostatic activity may appreciably contribute to the severity of the disease. The aim of the present study was to evaluate the effect of the oral administration of Lactobacillus casei CRL 431 on platelet and endothelial activation mechanisms in a respiratory pneumococcal infection model in mice. S. pneumoniae induced an increase in platelet counts and enhanced the expression of P-selectin in control group, with higher endothelial activation in lung shown by the increase in von Willebrand factor (vWF) and vascular cell adhesion molecule 1 (VCAM-1) expression. Also, infection induced a decrease in CXCR-4 leukocytes, increased expression in annexinV and cell death at the pulmonary level and decreased antithrombin levels in bronchoalveolar lavage. In contrast, L. casei mice restored platelet counts, favoured faster P-selectin expression, lower vWF levels and VCAM-1 expression than control group. Also, L. casei induced higher levels of annexinV expression and lower cell death in the lung. Moreover, it was able to modulate antithrombin levels within the normal range, which would indicate lower coagulation activation and a protective effect locally exerted by L. casei. In this work, the ability of L. casei to favourably modulate platelet and endothelial functionality during a pulmonary infection with S. pneumoniae was demonstrated. Our findings offer a promising perspective for the use of this probiotic strain in the prevention of thrombotic complications associated with pneumococcal pneumonia, especially in at-risk patients. In addition, the use of L. casei would provide novel alternatives for the prevention and treatment of thrombosis associated with various diseases.

Derangement of the endothelial glycocalyx in sepsis

The vascular endothelial surface is coated by the glycocalyx, a ubiquitous gel-like layer composed of a membrane-binding domain that contains proteoglycans, glycosaminoglycan side-chains, and plasma proteins such as albumin and antithrombin. The endothelial glycocalyx plays a critical role in maintaining vascular homeostasis. However, this component is highly vulnerable to damage and is also difficult to examine. Recent advances in analytical techniques have enabled biochemical, visual and computational investigation of this vascular component. The glycocalyx modulates leukocyte-endothelial interactions, thrombus formation and other processes that lead to microcirculatory dysfunction and critical organ injury in sepsis. It also acts as a regulator of vascular permeability and contains mechanosensors as well as receptors for growth factors and anticoagulants. During the initial onset of sepsis, the glycocalyx is damaged and circulating levels of glycocalyx components, including syndecans, heparan sulfate and hyaluronic acid, can be measured and are reportedly useful as biomarkers for sepsis. Also, a new methodology using side-stream dark-field imaging is now clinically available for assessing the glycocalyx. Multiple factors including hypervolemia and hyperglycemia are toxic to the glycocalyx, and several agents have been proposed as therapeutic modalities, although no single treatment has been proven to be clinically effective. In this article, we review the derangement of the glycocalyx in sepsis. Despite the accumulated knowledge regarding the important roles of the glycocalyx, the relationship between derangement of the endothelial glycocalyx and severity of sepsis or disseminated intravascular coagulation has not been adequately elucidated and further work is needed.

Elevated Syndecan-1 after Trauma and Risk of Sepsis: A Secondary Analysis of Patients from the Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) Trial

BACKGROUND

Endotheliopathy of trauma is characterized by breakdown of the endothelial glycocalyx. Elevated biomarkers of endotheliopathy, such as serum syndecan-1 (Synd-1) ≥ 40 ng/mL, have been associated with increased need for transfusions, complications, and mortality. We hypothesized that severely injured trauma patients who exhibit elevated Synd-1 levels shortly after admission have an increased likelihood of developing sepsis.

STUDY DESIGN

We analyzed a subset of patients from the Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) trial who survived at least 72 hours after hospital admission, and we determined elevated Synd-1 levels (≥ 40 ng/mL) 4 hours after hospital arrival. Sepsis was defined a priori as meeting systemic inflammatory response criteria and having a known or suspected infection. Univariate analysis was performed to identify variables associated with elevated Synd-1 levels and sepsis. Significant variables at a value of p < 0.2 in the univariate analysis were chosen by purposeful selection and analyzed in a mixed effects multivariate logistic regression model to account for the 12 different study sites.

RESULTS

We included 512 patients. Of these, 402 (79%) had elevated Synd-1 levels, and 180 (35%) developed sepsis. Median Synd-1 levels at 4 hours after admission were 70 ng/dL (interquartile range [IQR] 36 to 157 ng/dL) in patients who did not develop sepsis, and 165 ng/dL [IQR 67 to 336 ng/dL] in those who did (p < 0.001). Adjusting for treatment arm and site, multivariable analyses revealed that elevated Synd-1 status, Injury Severity Score (ISS), and total blood transfused were significantly associated with an increased likelihood of developing sepsis.

CONCLUSIONS

Elevated Synd-1 levels 4 hours after admission in severely injured adult trauma patients who survived the initial 72 hours after hospital admission are associated with subsequent sepsis.

Lactobacillus casei beneficially modulates immuno-coagulative response in an endotoxemia model

: The current study aims at evaluating the effect of the oral administration of Lactobacillus casei CERELA (CRL) 431 on parameters implicated in inflammation-coagulation interaction using a model of acute inflammation induced by lipopolysaccharide (LPS) in mice. Six-week-old Balb/c mice were treated with L. casei for 5 consecutive days. Then treated and untreated mice received an LPS injection (L. casei + LPS and LPS groups, respectively). Liver and kidney were removed, blood samples were obtained, and hemostatic and inflammatory parameters were evaluated at different times post LPS injection. Preventive L. casei administration induced a significant decrease in proinflammatory TNF-α and IL-6 cytokines by decreasing tissue factor expression in liver and kidney. Moreover, the lower expression of tissue factor in the L. casei + LPS group led to a lower activation of the coagulation system, which was observed by the fast systemic restoration of factors VII and V coagulation factors and antithrombin levels. This study highlights the capacity of L. casei to modulate the hemostatic unbalance in an acute endotoxemia model. Our findings showed the ability of L. casei CRL 431 to regulate the immuno-coagulative response. This fact could be helpful to propose new adjunctive strategies addressed to the restoration of physiological anticoagulant mechanisms in sepsis patients.

Disseminated intravascular coagulation: an update on pathogenesis and diagnosis

INTRODUCTION

Activation of the hemostatic system can occur in many clinical conditions. However, a systemic and strong activation of coagulation complicating clinical settings such as sepsis, trauma or malignant disease may result in the occurrence disseminated intravascular coagulation (DIC). Areas covered: This article reviews the clinical manifestation and relevance of DIC, the various conditions that may precipitate DIC and the pathogenetic pathways underlying the derangement of the hemostatic system, based on clinical and experimental studies. In addition, the (differential) diagnostic approach to DIC is discussed. Expert commentary: In recent years a lot of precise insights in the pathophysiology of DIC have been uncovered, leading to a better understanding of pathways leading to the hemostatic derangement and providing points of impact for better adjunctive treatment strategies. In addition, simple diagnostic algorithms have been developed and validated to establish a diagnosis of DIC in clinical practice.

Activated Protein C has No Effect on Pulmonary Capillary Endothelial Function in Septic Patients with Acute Respiratory Distress Syndrome: Association of Endothelial Dysfunction with Mortality

INTRODUCTION

Pulmonary capillary endothelium-bound (PCEB) angiotensin-converting enzyme (ACE) activity is a direct and quantifiable index of pulmonary endothelial function that decreases early in acute respiratory distress syndrome (ARDS) and correlates with its severity. Endothelial dysfunction is a major pathophysiology that underlies sepsis-related ARDS. Recombinant human activated protein C (rhAPC), now withdrawn from the market, has been used in the recent past as an endothelial-protective treatment in patients with septic organ dysfunction.

METHODS

We investigated the effect of rhAPC on pulmonary endothelial function in 19 septic patients suffering from ARDS. Applying indicator-dilution type techniques, we measured single-pass transpulmonary percent metabolism (%M) and hydrolysis (v) of the synthetic, biologically inactive, and highly specific for ACE substrate, ³H-benzoyl-Phe-Ala-Pro (BPAP), under first-order reaction conditions, and calculated lung functional capillary surface area before and after treatment with rhAPC.

RESULTS

Pulmonary endothelium ACE activity was severely impaired in septic patients with ARDS, and was not affected by rhAPC treatment. Additionally, poor outcome was related to a more profound decrease in PCEB-ACE activity. Angiotensin-converting enzyme-substrate utilization was statistically significantly lower in non-survivors as compared to survivors, with no changes over time within each group: BPAP %M: 32.7 ± 3.4% at baseline to 25.6 ± 2.9% at day 7 in survivors versus 20.8 ± 2.8 to 15.5 ± 5%, respectively, in non-survivors (p = 0.044), while hydrolysis (v): 0.41 ± 0.06 at baseline to 0.30 ± 0.04 at day 7 in survivors compared to 0.24 ± 0.04 to 0.18 ± 0.06, respectively, in non-survivors (p = 0.049).

CONCLUSION

rhAPC administration in septic patients with ARDS did not improve PCEB-ACE activity indices. However, these indices might be useful in the early recognition of septic patients with ARDS at high risk of mortality.

Integrative model of leukocyte genomics and organ dysfunction in heart failure patients requiring mechanical circulatory support: a prospective observational study

BACKGROUND

The implantation of mechanical circulatory support devices in heart failure patients is associated with a systemic inflammatory response, potentially leading to death from multiple organ dysfunction syndrome. Previous studies point to the involvement of many mechanisms, but an integrative hypothesis does not yet exist. Using time-dependent whole-genome mRNA expression in circulating leukocytes, we constructed a systems-model to improve mechanistic understanding and prediction of adverse outcomes.

METHODS

We sampled peripheral blood mononuclear cells from 22 consecutive patients undergoing mechanical circulatory support device (MCS) surgery, at 5 timepoints: day -1 preoperative, and postoperative days 1, 3, 5, and 8. Clinical phenotyping was performed using 12 clinical parameters, 2 organ dysfunction scoring systems, and survival outcomes. We constructed a strictly phenotype-driven time-dependent non-supervised systems-representation using weighted gene co-expression network analysis, and annotated eigengenes using gene ontology, pathway, and transcription factor binding site enrichment analyses. Genes and eigengenes were mapped to the clinical phenotype using a linear mixed-effect model, with Cox models also fit at each timepoint to survival outcomes.

RESULTS

We inferred a 19-module network, in which most module eigengenes correlated with at least one aspect of the clinical phenotype. We observed a response of advanced heart failure patients to surgery orchestrated into stages: first, activation of the innate immune response, followed by anti-inflammation, and finally reparative processes such as mitosis, coagulation, and apoptosis. Eigengenes related to red blood cell production and extracellular matrix degradation became predictors of survival late in the timecourse corresponding to multiorgan dysfunction and disseminated intravascular coagulation.

CONCLUSIONS

Our model provides an integrative representation of leukocyte biology during the systemic inflammatory response following MCS device implantation. It demonstrates consistency with previous hypotheses, identifying a number of known mechanisms. At the same time, it suggests novel hypotheses about time-specific targets.

Correlation between Interleukin-6 and Thrombin-Antithrombin III Complex Levels in Retinal Diseases

PURPOSE

This study aims to evaluate and correlate the levels of interleukin-6 (IL-6) and thrombin-antithrombin III complex (TAT) in the vitreous of patients with different vitreoretinal pathologies.

METHODS

Vitreous samples were collected from 78 patients scheduled for pars plana vitrectomy at a tertiary medical center. Patients were divided by the underlying vitreoretinal pathophysiology, as follows: macular hole (MH)/epiretinal membrane (ERM) (n = 26); rhegmatogenous retinal detachment (RRD) (n = 32); and proliferative diabetic retinopathy (PDR) (n = 20). Levels of IL-6 and TAT were measured by enzyme-linked immunosorbent assay and compared among the groups.

RESULTS

A significant difference was found in the vitreal IL-6 and TAT levels between the MH/ERM group and both the PDR and RRD groups (P < 0.001 for all). Diabetes was associated with higher IL-6 levels in the RRD group. Different relationships between the IL-6 and TAT levels were revealed in patients with different ocular pathologies.

CONCLUSION

Our results imply that variations in vitreal TAT level may be attributable not only to an inflammatory reaction or blood-retinal barrier breakdown, but also to intraocular tissue-dependent regulation of thrombin.

Expression and Function of Granzymes A and B in Escherichia coli Peritonitis and Sepsis

Escherichia (E.) coli is the most common causative pathogen in peritonitis, the second most common cause of sepsis. Granzymes (gzms) are serine proteases traditionally implicated in cytotoxicity and, more recently, in the inflammatory response. We here sought to investigate the role of gzms in the host response to E. coli-induced peritonitis and sepsis in vivo. For this purpose, we used a murine model of E. coli intraperitoneal infection, resembling the clinical condition commonly associated with septic peritonitis by this bacterium, in wild-type and gzmA-deficient (gzmA^−/−), gzmB^−/−, and gzmAxB^−/−mice. GzmA and gzmB were predominantly expressed by natural killer cells, and during abdominal sepsis, the percentage of these cells expressing gzms in peritoneal lavage fluid decreased, while the amount of expression in the gzm⁺ cells increased. Deficiency of gzmA and/or gzmB was associated with increased bacterial loads, especially in the case of gzmB at the primary site of infection at late stage sepsis. While gzm deficiency did not impact neutrophil recruitment into the abdominal cavity, it was accompanied by enhanced nucleosome release at the primary site of infection, earlier hepatic necrosis, and more renal dysfunction. These results suggest that gzms influence bacterial growth and the host inflammatory response during abdominal sepsis caused by E. coli.

Disseminated intravascular coagulation caused by moojenactivase, a procoagulant snake venom metalloprotease

Snake venom toxins that activate coagulation factors are key players in the process of venom-induced coagulopathy, and account for severe clinical manifestations. The present study applies a variety of biochemical, hematological, and histopathological approaches to broadly investigate the intravascular and systemic effects of moojenactivase (MooA), the first described PIIId subclass metalloprotease isolated from Bothrops sp. venom that activates coagulation factors. MooA induced consumption coagulopathy with high toxic potency, characterized by prolongation of prothrombin and activated partial thromboplastin time, consumption of fibrinogen and the plasma coagulation factors X and II, and thrombocytopenia. MooA promoted leukocytosis and expression of the proinflammatory cytokines interleukin-6 and tumor necrosis factor-α, accompanied by tissue factor-dependent procoagulant activity in peripheral blood mononuclear cells. This metalloprotease also caused intravascular hemolysis, elevated plasma levels of creatine kinase-MB, aspartate transaminase, and urea/creatinine, and induced morphopathological alterations in erythrocytes, heart, kidney, and lungs associated with thrombosis and hemorrhage. Diagnosis of MooA-induced disseminated intravascular coagulation represents an important approach to better understand the pathophysiology of Bothrops envenomation and develop novel therapeutic strategies targeting hemostatic disturbances.

Thrombin contributes to protective immunity in pneumonia-derived sepsis via fibrin polymerization and platelet-neutrophil interactions

Essentials Immunity and coagulation are linked during sepsis but the role of thrombin is not fully elucidated. We investigated the effect of thrombin inhibition on murine Klebsiella pneumosepsis outcome. Thrombin is crucial for survival and limiting bacterial growth in pneumonia derived sepsis. Thrombin improves host defense via fibrin and enhancement of platelet-neutrophil interactions.

SUMMARY

Background Innate immunity and coagulation are closely linked during sepsis. Their interaction can be detrimental to the outcome because of microvascular failure but can also enhance host defense. The role of thrombin therein has not been fully elucidated. Objective We aimed to investigate the contribution of thrombin to the host response during pneumonia-derived sepsis. Methods Mice treated with the specific thrombin inhibitor dabigatran or control chow were infected with the common human sepsis pathogen Klebsiella (K.) pneumoniae via the airways. In subsequent infection experiments, mice were additionally treated with ancrod to deplete fibrinogen. Ex vivo Klebsiella growth was assessed by incubating human whole blood or specific blood components in various conditions with Klebsiella. Results Thrombin inhibition by dabigatran enhanced bacterial outgrowth and spreading, and accelerated mortality. Thrombin inhibition did not influence neutrophil recruitment to the lung or activation or neutrophil extracellular trap formation. Dabigatran reduced D-dimer formation and fibrin deposition in the lung. Fibrin depletion also enhanced bacterial outgrowth and spreading, and thrombin inhibition had no additional effect. Both thrombin and fibrin polymerization inhibited ex vivo Klebsiella outgrowth in human whole blood, which was neutrophil dependent, and the effect of thrombin required the presence of platelets and platelet protease activated receptor-1. In vivo thrombin inhibition reduced platelet-neutrophil complex formation and endothelial cell activation, but did not prevent sepsis-induced thrombocytopenia or organ damage. Conclusions These results suggest that thrombin plays an important role in protective immunity during pneumonia-derived sepsis by fibrin polymerization and enhancement of platelet-neutrophil interactions.

Shock induced endotheliopathy (SHINE) in acute critical illness - a unifying pathophysiologic mechanism

One quarter of patients suffering from acute critical illness such as severe trauma, sepsis, myocardial infarction (MI) or post cardiac arrest syndrome (PCAS) develop severe hemostatic aberrations and coagulopathy, which are associated with excess mortality. Despite the different types of injurious “hit”, acutely critically ill patients share several phenotypic features that may be driven by the shock. This response, mounted by the body to various life-threatening conditions, is relatively homogenous and most likely evolutionarily adapted. We propose that shock-induced sympatho-adrenal hyperactivation is a critical driver of endothelial cell and glycocalyx damage (endotheliopathy) in acute critical illness, with the overall aim of ensuring organ perfusion through an injured microvasculature. We have investigated more than 3000 patients suffering from different types of acute critical illness (severe trauma, sepsis, MI and PCAS) and have found a potential unifying pathologic link between sympatho-adrenal hyperactivation, endotheliopathy, and poor outcome. We entitled this proposed disease entity, shock-induced endotheliopathy (SHINE). Here we review the literature and discuss the pathophysiology of SHINE.

Functional human 3D microvascular networks on a chip to study the procoagulant effects of ambient fine particulate matter

Exposure to ambient fine particulate matter (FPM) has been thought to be associated with cardiovascular disease.

Thermoregulation as a disease tolerance defense strategy

Physiological responses that occur during infection are most often thought of in terms of effectors of microbial destruction through the execution of resistance mechanisms, due to a direct action of the microbe, or are maladaptive consequences of host-pathogen interplay. However, an examination of the cellular and organ-level consequences of one such response, thermoregulation that leads to fever or hypothermia, reveals that these actions cannot be readily explained within the traditional paradigms of microbial killing or maladaptive consequences of host-pathogen interactions. In this review, the concept of disease tolerance is applied to thermoregulation during infection, inflammation and trauma, and we discuss the physiological consequences of thermoregulation during disease including tissue susceptibility to damage, inflammation, behavior and toxin neutralization.

Coagulation Gene Expression Profiling in Infants With Necrotizing Enterocolitis

OBJECTIVES

Coagulopathy and mesenteric thrombosis are common in premature neonates with necrotizing enterocolitis (NEC). This pilot study aimed to investigate the hypothesis that there are changes in the gene expression related to the coagulation and anticoagulation systems in NEC.

METHODS

Consecutive neonates (n = 11) with NEC (Bell stages 2-3) were recruited. Two comparison groups, matched for birth weight and corrected gestational age, were selected based on the absence of inflammation and coagulopathy (healthy control, n = 10), or the presence of a confirmed blood infection (sepsis control, n = 12). A pathway-specific quantitative polymerase chain reaction array was used to determine the expression of 94 genes involved in human blood coagulation and anticoagulation cascade.

RESULTS

Twelve genes of the coagulation and anticoagulation systems were significantly altered in the patients with NEC compared with healthy controls. In particular, neutrophil elastase, CD63, PROS1, HGF, and F12 were significantly upregulated (mean fold changes [FCs] +2.74, P < 0.05) with an overall procoagulant effect; MFGE8, factor II (thrombin) receptor-like 1 (F2RL1), FGL2, PLAT, PROCR, SERPIND1, and HNF4A were significantly downregulated (mean FCs -2.45, P < 0.05) with a reduction in fibrinolysis and endothelial regeneration. In the comparison between NEC and sepsis, we did observe a significant difference in expression of F2RL1 (FC -2.50, P = 0.01).

CONCLUSIONS

We have identified potential biomarkers associated with coagulopathy and disease progression in NEC. In particular, the overall procoagulant status, at the transcriptional level, should be further investigated to unveil molecular mechanisms leading to intestinal necrosis, multiorgan failure, and death.

Disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is an acquired syndrome characterized by widespread intravascular activation of coagulation that can be caused by infectious insults (such as sepsis) and non-infectious insults (such as trauma). The main pathophysiological mechanisms of DIC are inflammatory cytokine-initiated activation of tissue factor-dependent coagulation, insufficient control of anticoagulant pathways and plasminogen activator inhibitor 1-mediated suppression of fibrinolysis. Together, these changes give rise to endothelial dysfunction and microvascular thrombosis, which can cause organ dysfunction and seriously affect patient prognosis. Recent observations have pointed to an important role for extracellular DNA and DNA-binding proteins, such as histones, in the pathogenesis of DIC. The International Society on Thrombosis and Haemostasis (ISTH) established a DIC diagnostic scoring system consisting of global haemostatic test parameters. This scoring system has now been well validated in diverse clinical settings. The theoretical cornerstone of DIC management is the specific and vigorous treatment of the underlying conditions, and DIC should be simultaneously managed to improve patient outcomes. The ISTH guidance for the treatment of DIC recommends treatment strategies that are based on current evidence. In this Primer, we provide an updated overview of the pathophysiology, diagnosis and management of DIC and discuss the future directions of basic and clinical research in this field.

Trauma-Induced Coagulopathy Is Associated with a Complex Inflammatory Response in the Rat

Severe trauma can lead to a coagulopathy in patients, which is associated with increased mortality. We developed a rat polytrauma model that demonstrates a similar progression of coagulopathy. Because coagulation is influenced by changes in inflammation, and this interrelationship is poorly understood, we have studied the progression of inflammation, and its correlation with coagulation, in this rat model of severe polytrauma. Sprague-Dawley rats were anesthetized with isoflurane. Polytrauma was induced by damaging 10 cm of small intestines, right and medial liver lobes, right leg skeletal muscle, femur fracture, and hemorrhaging 40% of blood volume. No resuscitation was given. Polytrauma and hemorrhage resulted in a significant decrease in the number of lymphocytes and an increase in monocytes and granulocytes. There was an increase in plasma proinflammatory cytokines: tumor necrosis factor α (40×), interleukin (IL)-6 (20×), IL-1β (16×), IL-17 (15×), interferon γ (10×), IL-1α (8×) and IL-12p70 (5×); anti-inflammatory cytokines: IL-10 (100×), IL-13 (16×), and IL-4 (5×); chemokines: growth-regulated protein/keratinocyte chemoattractant (30×), macrophage inflammatory protein 3α (10×), regulated and normal T-cell expressed and secreted (3×); and growth factors: vascular endothelial growth factor (5×), granulocyte macrophage colony-stimulating factor (6×), macrophage colony-stimulating factor (3×), granulocyte colony-stimulating factor (2×), and IL-5 (3×). There was a strong and significant correlation between prothrombin time, activated partial thromboplastin time, fibrinogen, and fibrin monomer concentration, and many cytokines. Polytrauma with hemorrhage is associated with a coagulopathy and a complex inflammatory response consisting of a concurrent rise in both proinflammatory and anti-inflammatory cytokines. The rise in plasma concentrations of chemokines and growth factors likely contribute to the mobilization of monocytes and granulocytes. There is strong correlation between prothrombin time, activated partial thromboplastin time, and IL-10 and IL-1β. This relationship could be exploited for the development of resuscitation strategies that attenuate these cytokines and allow for better outcomes in patients with trauma through concomitant modulation of inflammation and coagulopathy.

Endothelial and Microcirculatory Function and Dysfunction in Sepsis

The microcirculation is a series of arterioles, capillaries, and venules that performs essential functions of oxygen and nutrient delivery, customized to the unique physiologic needs of the supplied organ. The homeostatic microcirculatory response to infection can become harmful if overactive and/or dysregulated. Pathologic microcirculatory dysfunction can be directly visualized by intravital microscopy or indirectly measured via detection of circulating biomarkers. Although several treatments have been shown to protect the microcirculation during sepsis, they have not improved patient outcomes when applied indiscriminately. Future outcomes-oriented studies are needed to test sepsis therapeutics when personalized to a patient's microcirculatory dysfunction.

In-line Filtration Decreases Systemic Inflammatory Response Syndrome, Renal and Hematologic Dysfunction in Pediatric Cardiac Intensive Care Patients

Cardiac surgery with cardiopulmonary bypass (CPB) frequently leads to systemic inflammatory response syndrome (SIRS) with concomitant organ malfunction. Infused particles may exacerbate inflammatory syndromes since they activate the coagulation cascade and alter inflammatory response or microvascular perfusion. In a randomized, controlled, prospective trial, we have previously shown that particle-retentive in-line filtration prevented major complications in critically ill children. Now, we investigated the effect of in-line filtration on major complications in the subgroup of cardiac patients. Children admitted to tertiary pediatric intensive care unit were randomized to either control or filter group obtaining in-line filtration throughout complete infusion therapy. Risk differences and 95 % confidence intervals (CI) of several complications such as SIRS, sepsis, mortality, various organ failure and dysfunction were compared between both groups using the Wald method. 305 children (n = 150 control, n = 155 filter group) with cardiac diseases were finally analyzed. The majority was admitted after cardiac surgery with CPB. Risk of SIRS (-11.3 %; 95 % CI -21.8 to -0.5 %), renal (-10.0 %; 95 % CI -17.0 to -3.0 %) and hematologic (-8.1 %; 95 % CI -14.2 to -0.2 %) dysfunction were significantly decreased within the filter group. No risk differences were demonstrated for occurrence of sepsis, any other organ failure or dysfunctions between both groups. Infused particles might aggravate a systemic hypercoagulability and inflammation with subsequent organ malfunction in pediatric cardiac intensive care patients. Particle-retentive in-line filtration might be effective in preventing SIRS and maintaining renal and hematologic function. In-line filtration offers a novel therapeutic option to decrease morbidity in cardiac intensive care.

Immunological characterization of compensatory anti-inflammatory response syndrome in patients with severe sepsis: a longitudinal study*

OBJECTIVES

To perform a complete immunological characterization of compensatory anti-inflammatory response syndrome in patients with sepsis and to explore the relationship between these changes and clinical outcomes of 28-day mortality and secondary infections.

DESIGN

Prospective single-center study conducted between April 2011 and December 2012.

SETTING

ICUs from Hospital Universitario San Vicente Fundación at Medellin, Colombia.

PATIENTS

One hundred forty-eight patients with severe sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

At days 0, 1, 3, 5, 10, and 28, we determined the expression of HLA-DR in monocytes and the apoptosis and the proliferation index in T lymphocytes, as well as the levels of tumor necrosis factor-α, interleukin-6, interleukin-1β, interleukin-10, and transforming growth factor-β in both plasma and cell culture supernatants of peripheral blood mononuclear cells. The mean percentage of HLA-DR was 60.7 at enrollment and increased by 0.9% (95% CI, 0.7-1.2%) per day. The mean percentage of CD4 T cells and CD8 T cells AV+/7-AAD- at enrollment was 37.2% and 20.4%, respectively, but it diminished at a rate of -0.5% (95% CI, -0.7% to -0.3%) and -0.3% (95% CI, -0.4% to -0.2%) per day, respectively. Plasma levels of interleukin-6 and interleukin-10 were 290 and 166 pg/mL and decreased at a rate of -7.8 pg/mL (95% CI, -9.5 to -6.1 pg/mL) and -4 pg/mL (95% CI, -5.1 to -2.8 pg/mL) per day, respectively. After controlling for confounders, only sustained plasma levels of interleukin-6 increase the risk of death (hazard ratio 1.003; 95% CI, 1.001-1.006).

CONCLUSIONS

We found no evidence to support a two-phase model of sepsis pathophysiology. However, immunological variables did behave in a mixed and time-dependent manner. Further studies should evaluate changes over time of interleukin-6 plasma levels as a prognostic biomarker for critically ill patients.

Platelets protect from septic shock by inhibiting macrophage-dependent inflammation via the cyclooxygenase 1 signalling pathway

Although it has long been known that patients with sepsis often have thrombocytopenia and that septic patients with severe thrombocytopenia have a poor prognosis and higher mortality, the role of platelets in the pathogenesis of sepsis is poorly understood. Here we report a protective role of platelets in septic shock. We show that experimental thrombocytopenia induced by intraperitoneal injection of an anti-glycoprotein Ibα monoclonal antibody increases mortality and aggravates organ failure, whereas transfusion of platelets reduces mortality in lipopolysaccharide-induced endotoxemia and a bacterial infusion mouse sepsis model. Plasma concentrations of proinflammatory cytokines TNF-α and IL-6 are elevated by thrombocytopenia and decreased by platelet transfusion in septic mice. Furthermore, we identify that platelets protect from septic shock by inhibiting macrophage-dependent inflammation via the COX1/PGE₂/EP4-dependent pathway. Thus, these findings demonstrate a previously unappreciated role for platelets in septic shock and suggest that platelet transfusion may be effective in treating severely septic patients.