Plasma soluble thrombomodulin levels are associated with mortality in the acute respiratory distress syndrome

Arginine Methylation by PRMT1 Affects ADAMTS13 Secretion and Enzymatic Activity

BACKGROUND

ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats, 13), primarily synthesized in hepatic stellate and endothelial cells, plays a pivotal role in regulation of hemostasis by proteolytic cleavage of von Willebrand factor. Severe deficiency of plasma ADAMTS13 activity may result in thrombotic thrombocytopenic purpura, a potentially fatal blood disorder. ADAMTS13 undergoes posttranslational modifications including glycosylation, citrullination, oxidation. The present study determines the impact of arginine methylation by PRMT1 (protein arginine methyltransferase 1) on ADAMTS13 secretion and function.

METHODS

Cell culture, recombinant protein, biochemical analysis, site-directed mutagenesis, and animal models were utilized.

RESULTS

An inhibition of arginine methylation by a type I methyl transferase PRMT inhibitor (MS023) in HEK (human embryonic kidney) 293 cells expressing recombinant ADAMTS13 and in mice results in a significant reduction of ADAMTS13 secretion, but the secreted ADAMTS13 shows an increased specific activity; conversely, an overexpression of PRMT1 in HEK-293 cells and in transgenic mice results in an increase of ADAMTS13 secretion, but the secreted ADAMTS13 exhibits a significantly reduced specific activity. The altered ADAMTS13 activity appeared to be related to its conformational changes. LC-MS/MS (liquid chromatography with tandem mass spectrometry) identified greater than100 arginine methylation events on purified recombinant ADAMTS13. Site-directed mutagenesis performed on 5 highly conserved methylation sites (R193, R498, R692, R1123, and R1206) identifies the critical role of R1206 in ADAMTS13 function. The ADAMTS13 R1206K variant exhibits a 4- to 5-fold increase of specific activity, likely resulting from an alleviation of allosteric inhibition.

CONCLUSIONS

These results demonstrate the crucial role of arginine methylation in ADAMTS13 secretion and function. Our findings may shed new light on the mechanism of allosteric regulation of ADAMTS13, which may have a therapeutic implication.

The Association Between Dysglycemia and Endotheliopathy in ICU Patients With and Without Diabetes: A Cohort Study

IMPORTANCE

Dysglycemia in critically ill patients is associated with endotheliopathy. This relationship may be altered in patients with diabetes.

OBJECTIVES

Dysglycemia is common in critically ill patients and associated with increased mortality. Endotheliopathy is thought to play a role in this relationship; however, evidence is scarce. The aim of this study was to investigate the associations between dysglycemia and endotheliopathy to inform future glycemic management.

DESIGN, SETTING, AND PARTICIPANTS

This prospective observational study included 577 acutely admitted adult ICU patients at Copenhagen University Hospital-North Zealand, Denmark.

MAIN OUTCOMES AND MEASURES

Up to twenty-four hours of patient glycemia was paired with same-day levels of endothelial biomarkers measured after each 24-hour period for three consecutive days. Endotheliopathy was assessed by measurement of Syndecan-1, Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1), and soluble thrombomodulin (sTM).

RESULTS

Of the included patients, a total 57.5% were males, median age was 71 yr (interquartile range [IQR], 63-79), and 24.6% had diabetes prior to admission. Median admission time was 5 d (IQR, 3-10). Time above range (TAR) greater than 13.9 mmol/L, but not TAR 10.0-13.9 mmol/L, was associated with increase in sTM (0.01 ng/mL per %-point increase in TAR, p = 0.049) and PECAM-1 (0.01 ng/mL per %-point increase, p = 0.007). Glycemic variability was associated with increases in sTM (0.24 ng/mL per mmol/L increase in sd, p = 0.001 and 0.03 ng/mL per %-point increase in coefficient of variation, p < 0.001). Hypoglycemia 3.0-3.9 mmol/L was associated with increases in sTM (3.0 ng/mL, p < 0.001) and PECAM-1 (1.54 ng/mL, p < 0.001).

CONCLUSIONS AND RELEVANCE

In acutely admitted adult ICU patients, hypoglycemia was associated with endotheliopathy regardless of preadmission diabetes status. Hyperglycemia and high glycemic variability were associated with endotheliopathy in patients without diabetes. This suggests different responses to acute dysglycemia in patients with and without diabetes and warrants further investigation in clinical trials.

Derivation and Validation of a Clinical and Endothelial Biomarker Risk Model to Predict Persistent Pediatric Sepsis-Associated Acute Respiratory Dysfunction

BACKGROUND

Sepsis-associated ARDS results in high morbidity and mortality in children. However, heterogeneity among patients makes identifying those at risk of persistent acute respiratory dysfunction challenging. Endothelial dysfunction is a key feature of ARDS pathophysiologic characteristics, contributing to lung injury in sepsis. Incorporating endothelial biomarkers into risk models may enhance prediction of those with persistent acute respiratory dysfunction.

RESEARCH QUESTION

Can clinical variables and endothelial biomarkers measured early in the course of sepsis predict risk of persistent acute respiratory dysfunction among critically ill children?

STUDY DESIGN AND METHODS

This was a multicenter derivation and single center test cohort study of prospectively enrolled children with sepsis. The derivation cohort was split into training and holdout validation sets. We trained TreeNet (Minitab, LLC) and classification and regression tree (CART) models using clinical and endothelial biomarkers measured on day 1 of septic shock to predict risk of sepsis-associated acute respiratory dysfunction (SA ARD) on day 3. The performance of the CART model was tested in the holdout validation data set and in the independent test cohort.

RESULTS

In the derivation (n = 625) and test (n = 162) cohorts, children with day 3 SA ARD showed increased mortality, length of mechanical ventilation, and PICU length of stay compared with those without. The TreeNet and CART models yielded comparable results. The variables included in the final CART model were presence of SA ARD on day 1, Pao2 to Fio2 ratio of < 250, soluble thrombomodulin, and vascular cell adhesion molecule 1 concentrations. This model showed an area under the receiver operating characteristic curve (AUC) of 0.88 in the training data set, sensitivity of 0.91 (95% CI, 0.86-0.94), specificity of 0.76 (95% CI, 0.68-0.82), and demonstrated reproducibility in validation data set and test cohort (AUC range, 0.78-0.83).

INTERPRETATION

We derived and validated predictive models incorporating clinical and endothelial biomarkers to identify pediatric patients with septic shock at high risk of persistent acute respiratory dysfunction. Pending prospective validation, such models may facilitate enrichment and targeted intervention in future clinical trials.

Thrombomodulin: A key regulator of intravascular blood coagulation, fibrinolysis, and inflammation, and a treatment for disseminated intravascular coagulation

Thrombomodulin (TM) is an important regulator of intravascular blood coagulation, fibrinolysis, and inflammation. TM inhibits the procoagulant and proinflammatory activities of thrombin and promotes the thrombin-induced activation of protein C (PC) bound to the endothelial PC receptor (EPCR). Activated PC (APC) inactivates coagulation factors Va and VIIIa, thereby inhibiting blood clotting. APC bound to EPCR exerts anti-inflammatory and cytoprotective effects on vascular endothelial cells. TM promotes the activation of thrombin-activatable fibrinolysis inhibitor, and also protects cells in blood vessels from inflammation caused by pathogen-associated and damaged cell-associated molecules. Excessive anticoagulant, fibrinolytic, anti-inflammatory, and tissue regenerative effects in the TM-PC pathway are controlled by PC inhibitor. A recombinant TM drug (TM), a soluble form of natural TM developed from the cloned human TM gene, has been evaluated for efficacy in many clinical trials and approved as a treatment for disseminated intravascular coagulation (DIC) caused by diseases such as sepsis, solid tumors, hematopoietic tumors, and trauma. It is currently widely used to treat DIC in Japan.

The value of thrombus markers applied in patients with respiratory failure

Background

This work assessed the value of novel thrombus markers-thrombin-antithrombin complex (TAT), plasmin-a2-plasmin inhibitor complex (PIC), thrombomodulin (TM), and tissue plasminogen activator-inhibitor complex (t-PAIC) applied in patients with respiratory failure (RF), including their role in predicting thrombus formation, evaluating prognosis, and assessing disease severity.

Methods

Eighty patients with RF were enrolled and categorized into mild (n = 10), moderate (n = 9), and severe (n = 71) groups based on disease severity. Meanwhile, patients were also classified into thrombus (n = 14) and non-thrombus (n = 76) groups based on the presence of thrombus. Furthermore, they were assigned into survival (n = 70) and death (n = 20) groups based on prognosis. Traditional coagulation indicators, thrombus markers, infection-related parameters, and respiratory-related indicators were compared among patients in different groups. This work explored the predictive effects of these indicators on the degree of respiratory failure, thrombus formation, and prognosis in various patient groups. Additionally, correlations of thrombus markers and traditional coagulation indicators to respiratory-related indicators and infectionrelated indicators were analyzed.

Results

Upon admission, levels of thrombin-antithrombin complex (TAT), plasmin-a2-plasmin inhibitor complex (PIC), and tissue plasminogen activator-inhibitor complex (t-PAIC) in the thrombus group were sharply higher in contrast to those in the non-thrombus group, showing obvious differences (P<0.05). Patients in the death group experienced remarkably elevated TAT, PIC, t-PAIC, thrombomodulin (TM), and to the survival group (P<0.05). In addition, high-sensitivity C-reactive protein (hs-CRP) in the death group was higher to that in the survival group (P<0.05). Platelet count (PLT) and procalcitonin (PCT) were sharply lower in the survival group (P<0.05). In groups of varying severity, PCT exhibited an elevated level in the severe, demonstrating great differences to the mild to moderate groups (P<0.05). Besides, TAT, PIC, TM, and t-PAIC showed higher sensitivity and accuracy in predicting severe RF, with higher specificity in predicting thrombus formation in RF patients. In correlation analysis, a positive correlation was observed between TT, PCT, and the fraction of inspired oxygen (FiO2). The activated partial thromboplastin time (APTT), PCT, and FiO2 exhibited positive correlations. Additionally, a positive association existed between fibrinogen (FIB), hs-CRP, and PLT. A positive link was identified between D-dimer and hs-CRP, PIC and PLT, as well as tPAIC and PCT.

Conclusions

Thrombus markers exerted a crucial effect in patients experiencing respiratory failure, serving as pivotal indicators for assessing the severity of the condition, identifying thrombotic risk, and predicting prognosis.

Impact of Thrombomodulin Polymorphism -33G>A on Acute Myocardial Infarction Risk and Circulating Inflammatory Markers

BACKGROUND

There is increasing evidence that thrombomodulin (THBD) polymorphisms, along with inflammatory markers [i.e., C-reactive protein (CRP), fibrinogen, albumin], may increase the risk of acute myocardial infarction (AMI). The aim of the study was to investigate the role of the THBD -33G>A polymorphism (rs1042579) as a marker of AMI risk and to correlate it with serum levels of inflammatory markers.

METHODS

Case-control study of 277 AMI patients and 329 healthy controls. A binary logistic regression analysis was performed to evaluate the association between the parameters studied and AMI risk.

RESULTS

The frequencies of genotypes AA, GA, and GG of the THBD -33G>A polymorphism were 31.4%, 45.5%, and 23.1% in patients and 21.6%, 44.1%, and 34.3% in controls. A significant association was found between the AA genotype of the THBD -33G>A polymorphism (AA: OR = 2.011, 95% CI 1.561-3.074, P < .001) or A allele (A: OR = 1.725, 95% CI 1.493-2.510, P < .001) and AMI risk. A backward stepwise logistic regression method combining AMI status as the dependent variable and conventional risk factors (age, smoking, arterial hypertension (HTA), diabetes, dyslipidemia, CRP, albumin, fibrinogen, serum angiotensin converting enzyme (ACE) activity, serum malondialdehyde, conjugated dienes, glutathione peroxidase, cardiac troponin-I (cTnI) and THBD AA genotype) as independent variables showed that the most predictive risk factors for AMI were smoking, HTA, albumin, fibrinogen, CRP, ACE activity, cTnI, and the THBD AA-genotype with odds ratios of 2.942, 2.203, 2.352, 1.323, 1.652, 1.014, 2.105, and 3.781 respectively. The AA genotype was associated with increased diastolic blood pressure, CRP, ACE activity, and albumin levels.

CONCLUSIONS

The study shows that the THBD -33G>A polymorphism should be included in the stratification of AMI risk.

Developing a predictive nomogram for mortality in patients with extrapulmonary acute respiratory distress syndrome: the prognostic value of serum soluble thrombomodulin, lung ultrasound score, and lactate

Objective: This study aimed to elucidate the prognostic significance of serum soluble thrombomodulin (sTM), lung ultrasound score (LUS), and lactate levels in patients with extrapulmonary acute respiratory distress syndrome (ARDS), with the goal of refining mortality risk prediction in this cohort. Methods: In a prospective cohort of 95 patients with extrapulmonary ARDS admitted to the intensive care unit, we investigated the primary endpoint of 28-day mortality. Utilizing Lasso-Cox regression analysis, we identified independent prognostic factors for mortality. A predictive nomogram was developed incorporating these factors, and its performance was validated through several statistical measures, including the consistency index, calibration plot, internal validation curve, decision curve analysis, interventions avoided analysis, receiver operating characteristic curve analysis, and Kaplan-Meier survival analysis. We further conducted a subgroup analysis to examine the impact of prone positioning on patient outcomes. Results: The study identified baseline serum sTM, LUS, and lactate levels as independent predictors of 28-day mortality in extrapulmonary ARDS patients. The predictive nomogram demonstrated superior prognostic accuracy compared to the use of sTM, LUS, or lactate levels alone, and outperformed traditional prognostic tools such as the Acute Physiology and Chronic Health Evaluation II score and the partial pressure of arterial oxygen to fractional inspired oxygen ratio. The subgroup analysis did not show a significant impact of prone positioning on the predictive value of the identified biomarkers. Conclusion: Our study results support the development and validation of a novel prognostic nomogram that integrates key clinical biomarkers and ultrasound imaging scores to predict mortality in patients with extrapulmonary ARDS. While our research is preliminary, further studies and validation are required.

Early predictive values of clinical assessments for ARDS mortality: a machine-learning approach

Acute respiratory distress syndrome (ARDS) is a devastating critical care syndrome with significant morbidity and mortality. The objective of this study was to evaluate the predictive values of dynamic clinical indices by developing machine-learning (ML) models for early and accurate clinical assessment of the disease prognosis of ARDS. We conducted a retrospective observational study by applying dynamic clinical data collected in the ARDSNet FACTT Trial (n = 1000) to ML-based algorithms for predicting mortality. In order to compare the significance of clinical features dynamically, we further applied the random forest (RF) model to nine selected clinical parameters acquired at baseline and day 3 independently. An RF model trained using clinical data collected at day 3 showed improved performance and prognostication efficacy (area under the curve [AUC]: 0.84, 95% CI: 0.78-0.89) compared to baseline with an AUC value of 0.72 (95% CI: 0.65-0.78). Mean airway pressure (MAP), bicarbonate, age, platelet count, albumin, heart rate, and glucose were the most significant clinical indicators associated with mortality at day 3. Thus, clinical features collected early (day 3) improved performance of integrative ML models with better prognostication for mortality. Among these, MAP represented the most important feature for ARDS patients' early risk stratification.

Novel mechanisms of action of emerging therapies of hereditary thrombotic thrombocytopenic purpura

INTRODUCTION

Hereditary thrombotic thrombocytopenic purpura (hTTP) is caused by deficiency of plasma ADAMTS13 activity, resulting from ADAMTS13 mutations. ADAMTS13 cleaves ultra large von Willebrand factor (VWF), thus reducing its multimer sizes. Hereditary deficiency of plasma ADAMTS13 activity leads to the formation of excessive platelet-VWF aggregates in small arterioles and capillaries, resulting in hTTP.

AREAS COVERED

PubMed search from 1956 to 2024 using thrombotic thrombocytopenic purpura and therapy identified 3,675 articles. Only the articles relevant to the topic were selected for discussion, which focuses on pathophysiology, clinical presentations, and mechanisms of action of emerging therapeutics for hTTP. Current therapies include infusion of plasma, or coagulation factor VIII, or recombinant ADAMTS13. Emerging therapies include anti-VWF A1 aptamers or nanobody and gene therapies with adeno-associated viral vector or self-inactivated lentiviral vector or a sleeping beauty transposon system for a long-term expression of a functional ADAMTS13 enzyme.

EXPERT OPINION

Frequent plasma infusion remains to be the standard of care in most parts of the world, while recombinant ADAMTS13 has become the treatment of choice for hTTP in some of the Western countries. The success of gene therapies in preclinical models may hold a promise for future development of these novel approaches for a cure of hTTP.

Mechanisms of pulmonary endothelial barrier dysfunction in acute lung injury and acute respiratory distress syndrome

Endothelial cells (ECs) form a semi-permeable barrier between the interior space of blood vessels and the underlying tissues. Pulmonary endothelial barrier integrity is maintained through coordinated cellular processes involving receptors, signaling molecules, junctional complexes, and protein-regulated cytoskeletal reorganization. In acute lung injury (ALI) or its more severe form acute respiratory distress syndrome (ARDS), the loss of endothelial barrier integrity secondary to endothelial dysfunction caused by severe pulmonary inflammation and/or infection leads to pulmonary edema and hypoxemia. Pro-inflammatory agonists such as histamine, thrombin, bradykinin, interleukin 1β, tumor necrosis factor α, vascular endothelial growth factor, angiopoietin-2, and platelet-activating factor, as well as bacterial toxins and reactive oxygen species, cause dynamic changes in cytoskeletal structure, adherens junction disorganization, and detachment of vascular endothelial cadherin (VE-cadherin) from the actin cytoskeleton, leading to an increase in endothelial permeability. Endothelial interactions with leukocytes, platelets, and coagulation enhance the inflammatory response. Moreover, inflammatory infiltration and the associated generation of pro-inflammatory cytokines during infection cause EC death, resulting in further compromise of the structural integrity of lung endothelial barrier. Despite the use of potent antibiotics and aggressive intensive care support, the mortality of ALI is still high, because the mechanisms of pulmonary EC barrier disruption are not fully understood. In this review, we summarized recent advances in the studies of endothelial cytoskeletal reorganization, inter-endothelial junctions, endothelial inflammation, EC death, and endothelial repair in ALI and ARDS, intending to shed some light on the potential diagnostic and therapeutic targets in the clinical management of the disease.

Are serum thrombomodulin and interleukin-8 levels associated with disease severity and mortality in critically ill children with respiratory failure?

Background/aim

Thrombomodulin (TM) is found on endothelial cell surfaces and increases in response to endothelial injury of different organs. Interleukin (IL)-8 regulates pulmonary inflammation. TM and IL-8 are candidate biological markers of acute respiratory distress syndrome (ARDS). The aim of the present study was to compare TM and IL-8 levels in pediatric patients with and without ARDS who received respiratory support and to determine their relationships with prognosis.

Materials and methods

This was a prospective observational study of 55 patients who received respiratory support in the pediatric intensive care unit. Eighteen patients without active infection were defined as the control group. Two blood samples were taken for serum IL-8 and TM levels on the first and third days of respiratory support.

Results

The patient group had significantly higher IL-8 and TM levels than the control group [median IL-8: 102.7 (IQR: 180.42-189.47) vs. 45.4 (55.14-70.49) ng/L, p = 0.011; median TM: 6.9 (6.83-9.18) vs. 3.4 (3.62-5.05) ng/mL, p = 0.021]. Patients with ARDS had significantly higher marker levels on the first and third days than those who did not have ARDS. The TM and IL-8 levels of deceased patients were significantly higher than those of the survivors on the first day. In mortality prediction, the cut-off point for IL-8 was found to be >154.7 ng/L, which had sensitivity of 76.9% and specificity of 73.8%. The cut-off point for TM was >8.4 ng/mL, which had sensitivity of 76.9% and specificity of 66.7%.

Conclusion

In our study, higher marker levels correlated with impaired oxygenation and higher mortality. Higher TM and IL-8 levels in ARDS might reflect the degree of vascular injury and inflammation.

Blood group O is associated with ARDS development but exhibits lower mortality in the intensive care unit - A retrospective multicentre study

Background

Acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in the intensive care unit (ICU). Previous studies have suggested that blood group A increases the risk of developing ARDS following sepsis and major trauma. This study investigated the association between ABO and Rh blood groups and ARDS development and mortality in ARDS.

Methods

Patients admitted to the ICUs at Skåne University Hospital in Lund and Malmö, Sweden, in 2016 were retrospectively screened for ARDS according to the Berlin definition. Clinical data, patient characteristics, lab results, and survival data were collected from medical records and registry data. In addition, chest radiographs were reviewed by radiologists. ARDS development and 30-day mortality were analysed using multivariable logistic regression.

Results

A total of 1439 ICU patients were included. Of these, 10% had ARDS. Blood group O was associated with an increased risk of having or developing ARDS compared to blood group A (odds ratio [OR] 1.79, 95% confidence interval [CI] 1.13-2.84, p = 0.014). Among ARDS patients, blood group O had decreased 30-day mortality compared to blood group A (OR 0.25, 95% CI 0.09-0.67, p = 0.007). The Rh blood group was not associated with ARDS development or mortality.

Conclusion

In this study of ICU patients, blood group O was associated with an increased risk of having or developing ARDS but a decreased mortality in ARDS compared to blood group A. Further studies are needed to clarify the relationship and underlying mechanisms of the ABO blood group and ARDS.

Acute respiratory distress syndrome heterogeneity and the septic ARDS subgroup

Acute respiratory distress syndrome (ARDS) is an acute diffuse inflammatory lung injury characterized by the damage of alveolar epithelial cells and pulmonary capillary endothelial cells. It is mainly manifested by non-cardiogenic pulmonary edema, resulting from intrapulmonary and extrapulmonary risk factors. ARDS is often accompanied by immune system disturbance, both locally in the lungs and systemically. As a common heterogeneous disease in critical care medicine, researchers are often faced with the failure of clinical trials. Latent class analysis had been used to compensate for poor outcomes and found that targeted treatment after subgrouping contribute to ARDS therapy. The subphenotype of ARDS caused by sepsis has garnered attention due to its refractory nature and detrimental consequences. Sepsis stands as the most predominant extrapulmonary cause of ARDS, accounting for approximately 32% of ARDS cases. Studies indicate that sepsis-induced ARDS tends to be more severe than ARDS caused by other factors, leading to poorer prognosis and higher mortality rate. This comprehensive review delves into the immunological mechanisms of sepsis-ARDS, the heterogeneity of ARDS and existing research on targeted treatments, aiming to providing mechanism understanding and exploring ideas for accurate treatment of ARDS or sepsis-ARDS.

Assays to quantify fibrinolysis: strengths and limitations. Communication from the International Society on Thrombosis and Haemostasis Scientific and Standardization Committee on fibrinolysis

Fibrinolysis is a series of enzymatic reactions that degrade insoluble fibrin. Plasminogen activators convert the zymogen plasminogen to the active serine protease plasmin, which cleaves and solubilizes crosslinked fibrin clots into fibrin degradation products. The quantity and quality of fibrinolytic enzymes, their respective inhibitors, and clot structure determine overall fibrinolysis. The quantity of protein can be measured by antigen-based assays, and both quantity and quality can be assessed using functional assays. Furthermore, variations of commonly used assays have been reported, which are tailored to address the role(s) of specific fibrinolytic factors and cellular elements (eg, platelets, neutrophils, and red blood cells). Although the concentration and/or activity of a protein can be quantified, how these individual components contribute to the overall fibrinolysis outcome can be challenging to determine. This difficulty is due to temporal changes within and around the thrombi during the clot breakdown, particularly the fibrin matrix structure, and composition. Furthermore, terms such as "fibrinolytic activity/potential," "plasminogen activation," and "plasmin activity" are often used interchangeably despite having different definitions. The purpose of this review is to 1) summarize the assays measuring fibrinolysis activity and potential, 2) facilitate the interpretation of data generated by these assays, and 3) summarize the strengths and limitations of these assays.

Are circulating endothelial cells the next target for transcriptome-level pathway analysis in ARDS?

Acute respiratory distress syndrome (ARDS) has had no mortality-improving pharmacological intervention despite 50 years of high-caliber research due to its heterogeneity (Huppert LA, Matthay MA, Ware LB. Semin Respir Crit Care Med 40: 31-39, 2019). For the field to advance, better definitions for ARDS subgroups that more uniformly respond to therapies are needed (Bos LDJ, Scicluna BP, Ong DSY, Cremer O, van der Poll T, Schultz MJ. Am J Respir Crit Care Med 200: 42-50, 2019; Dickson RP, Schultz MJ, T van der P, Schouten LR, Falkowski NR, Luth JE, Sjoding MW, Brown CA, Chanderraj R, Huffnagle GB, Bos LDJ, Biomarker Analysis in Septic ICU Patients (BASIC) Consortium. Am J Respir Crit Care Med 201: 555-563, 2020; Sinha P, Calfee CS. Am J Respir Crit Care Med 200: 4-6, 2019; Calfee CS, Delucchi K, Parsons PE, Thompson BT, Ware LB, Matthay MA, NHLBI ARDS Network. Lancet Respir Med 2: 611-620, 2014; Hendrickson CM, Matthay MA. Pulm Circ 8: 1-12, 2018). A plethora of high-quality clinical research has uncovered the next generation of soluble biomarkers that provide the predictive enrichment necessary for trial recruitment; however, plasma-soluble markers do not specify the damaged organ of origin nor do they provide insight into disease mechanisms. In this perspective, we make the case for querying the transcriptome of circulating endothelial cells (CECs), which when shed from vessels after inflammatory insult, become heralds of site-specific inflammatory damage. We review the application of CEC quantification to multiple disease phenotypes (including myocardial infarction, vasculitides, cancer, and ARDS), in each case supporting the association of CEC number with disease severity. We also argue for the utility of single-cell RNA transcriptomics to the understanding of cell-specific contributions to disease pathophysiology and its potential to uncover novel insight on signals contributing to CEC shedding in ARDS.

Association and predictive value of soluble thrombomodulin with mortality in patients with acute respiratory distress syndrome: systematic review and meta-analysis

Background

Acute respiratory distress syndrome (ARDS) is a heterogeneous illness that has a high mortality rate. The role and predictive value of soluble thrombomodulin (sTM) in ARDS mortality is disputable, so the present study aimed to evaluate the association and predictive value of sTM for the in-hospital mortality of ARDS.

Methods

PubMed, Web of Science, Embase, Cochrane Library, Chongqing VIP, WanFang, China National Knowledge Infrastructure (CNKI), and Chinese Biomedical Literature databases were searched for relevant literature published before October 10, 2022. Relevant observable studies were included for analysis. The Newcastle-Ottawa Scale and QUAPAS (Quality Assessment of Prognostic Accuracy Studies) were employed to appraise the quality of the included studies.

Results

Thirteen articles were included in the present study. The eligible studies were of moderate to high quality [Newcastle-Ottawa Scale (NOS) 5-8 scores], and the high risk of bias in the included studieson predictive value was mainly distributed in participant and analysis domains of QUAPAS. There were 1,992 patients with ARDS, and 538 died. Our meta-analysis demonstrated that nonsurvivors had more significantly increased sTM levels than did survivors [standardized mean difference (SMD) =1.473; 95% CI: 0.874-2.072; P<0.001]. Elevated sTM levels had an independent correlation with higher mortality in patients with ARDS [pooled odds ratio (OR) =2.126; 95% CI: 1.548-2.920; P<0.001]. sTM showed satisfactory performance in predicting the mortality of ARDS [summary receiver operating characteristic curve (SROC) =0.78; 95% CI: 0.64-0.89]. The pooled sensitivity was 72% (95% CI: 66-77%), and the pooled specificity was 77% (95% CI: 72-82%). Subgroup analysis showed no significant difference in the sTM levels between nonsurvivors and survivors in terms of patients with direct ARDS (SMD =0.813; 95% CI: -0.673 to 2.229; P=0.253).

Conclusions

sTM is associated with hospital mortality in ARDS and shows moderate predictive performance. As a result, it is a potential candidate for predicting the mortality of ARDS. However, caution is needed when sTM is used to predict adverse outcomes in patients with direct ARDS.

Assessment of Patient Health-Related Quality of Life and Functional Outcomes in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To describe health-related quality of life (HRQL) and functional outcomes in pediatric acute respiratory distress syndrome (ARDS) and to determine risk factors associated with poor outcome defined as death or severe reduction in HRQL at 28 days or ICU discharge.

DESIGN

Prospective multisite cohort-outcome study conducted between 2019 and 2020.

SETTING

Eight academic PICUs in the United States.

PATIENTS

Children with ARDS based on standard criteria.

INTERVENTIONS

Patient characteristics and illness severity were collected during PICU admission. Parent proxy-report measurements were obtained at baseline, day 28/ICU discharge, month 3, and month 9, utilizing Pediatric Quality of Life Inventory and Functional Status Scale (FSS). A composite outcome evaluated using univariate and multivariate analysis was death or severe reduction in HRQL (>25% reduction in the Pediatric Quality of Life Inventory at day 28/ICU discharge.

MEASUREMENTS AND MAIN RESULTS

This study enrolled 122 patients with a median age of 3 years (interquartile range, 1-12 yr). Common etiologies of ARDS included pneumonia ( n = 63; 52%) and sepsis ( n = 27; 22%). At day 28/ICU discharge, half (50/95; 53%) of surviving patients with follow-up data reported a greater than 10% decrease in HRQL from baseline, and approximately one-third of participants ( n = 19/61; 31%) reported a greater than 10% decrease in HRQL at 9 months. Trends in FSS were similar. Of 104 patients with data, 47 patients (45%) died or reported a severe decrease of greater than 25% in HRQL at day 28/ICU discharge. Older age was associated with an increased risk of death or severe reduction in HRQL (odds ratio, 1.08; CI, 1.01-1.16).

CONCLUSIONS

Children with ARDS are at risk for deterioration in HRQL and FSS that persists up to 9 months after ARDS. Almost half of children with ARDS experience a poor outcome including death or severe reduction in HRQL at day 28/ICU discharge.

The suppressive effects of Mer inhibition on inflammatory responses in the pathogenesis of LPS-induced ALI/ARDS

The pathogenesis of sepsis-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) has not yet been fully elucidated. Growth arrest-specific 6 (Gas6) has marked effects on hemostasis and reduces inflammation through its interaction with receptor tyrosine kinases of the TAM family: Tyro3, Axl, and Mer. Here, we found that plasma concentrations of Gas6 and soluble Mer were greater in patients with severe sepsis or septic ALI/ARDS compared with those in normal healthy donors. To determine whether the Gas6-Mer axis was critical in the pathogenesis of ALI/ARDS, we investigated the effects of intravenous administration of the selective Mer inhibitor UNC2250 on lipopolysaccharide (LPS)-induced ALI in mouse models subjected to inhalation of LPS. UNC2250 markedly inhibited the infiltration into the lungs of neutrophils and monocytes with increased amounts of Gas6 and Mer proteins, severe lung damage, and increased amounts of reactive oxygen species (ROS) in LPS-induced ALI in mice. In human pulmonary aortic endothelial cells, LPS induced decreases in the amounts of endothelial nitric oxide synthase, thrombomodulin, and vascular endothelial-cadherin, which was blocked by treatment with UNC2250. UNC2250 also inhibited the LPS-dependent increases in cell proliferation and enhanced apoptosis in HL-60 cells, a human neutrophil-like cell line, and RAW264.7 cells, a mouse monocyte/macrophage cell line. These data provide insights into the potential multiple beneficial effects of the Mer inhibitor UNC2250 as a therapeutic reagent to treat inflammatory responses in ALI/ARDS.

Endotheliopathy is associated with slower liberation from mechanical ventilation: a cohort study

Background

Endotheliopathy is suggested as pivotal pathophysiology of sepsis and trauma-associated organ failure, but its role in acute respiratory failure is not yet determined. We investigated if endotheliopathy biomarkers at ICU admission are associated with illness severity and clinical outcomes in patients with acute respiratory failure requiring mechanical ventilation.

Methods

We conducted a prospective single-center cohort study including 459 mechanically ventilated adults at ICU admission. Plasma levels of three endotheliopathy biomarkers were measured at ICU admission: Syndecan-1, soluble Thrombomodulin (sTM), and Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1). The primary outcome was the rate of liberation from mechanical ventilation, which is presented together with the rate of the competing risk of death while still on mechanical ventilation. Secondary outcomes were PaO₂/FiO₂-ratios on admission and on last measurement in patients dying within five days, and 30-day all-cause mortality. The primary outcome and 30-day all-cause mortality were analyzed using Cox regression, controlled for gender, age, chronic obstructive pulmonary disease, septic shock, heart failure, PaO₂/FiO₂-ratio at admission, respiratory infection, acute kidney injury, and bilirubin. PaO₂/FiO₂-ratios were analyzed using linear regression, controlled for age, chronic obstructive pulmonary disease, respiratory infection, and shock.

Results

Patients with high sTM were liberated from mechanical ventilation at a lower rate (adjusted hazard ratio (HR) 0.71, for an increase from the 25th to the 75th percentile, 95% confidence interval (CI) 0.54–0.93, p = 0.01). Patients with high PECAM-1 were liberated from mechanical ventilation at a lower rate, but only during the first 5 days (adjusted HR 0.72, for an increase from the 25th to the 75th percentile, 95% CI 0.58–0.9, p < 0.01). High levels of Syndecan-1 and PECAM-1 were associated with a higher rate of death while still on mechanical ventilation. sTM and PECAM-1 were negatively associated with PaO₂/FiO₂-ratio at ICU admission and no biomarker was associated with last measured PaO₂/FiO₂-ratio. High levels of all biomarkers were associated with higher 30-day all-cause mortality.

Conclusion

In acute respiratory failure, endotheliopathy biomarkers are associated with lower rates of liberation from mechanical ventilation, hypoxemia at ICU admission, and 30-day all-cause mortality.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03877-y.

Coagulation System Activation for Targeting of COVID-19: Insights into Anticoagulants, Vaccine-Loaded Nanoparticles, and Hypercoagulability in COVID-19 Vaccines

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as COVID-19, is currently developing into a rapidly disseminating and an overwhelming worldwide pandemic. In severe COVID-19 cases, hypercoagulability and inflammation are two crucial complications responsible for poor prognosis and mortality. In addition, coagulation system activation and inflammation overlap and produce life-threatening complications, including coagulopathy and cytokine storm, which are associated with overproduction of cytokines and activation of the immune system; they might be a lead cause of organ damage. However, patients with severe COVID-19 who received anticoagulant therapy had lower mortality, especially with elevated D-dimer or fibrin degradation products (FDP). In this regard, the discovery of natural products with anticoagulant potential may help mitigate the numerous side effects of the available synthetic drugs. This review sheds light on blood coagulation and its impact on the complication associated with COVID-19. Furthermore, the sources of natural anticoagulants, the role of nanoparticle formulation in this outbreak, and the prevalence of thrombosis with thrombocytopenia syndrome (TTS) after COVID-19 vaccines are also reviewed. These combined data provide many research ideas related to the possibility of using these anticoagulant agents as a treatment to relieve acute symptoms of COVID-19 infection.

Antibiotics as immunomodulators: a potential pharmacologic approach for ARDS treatment

First described in the mid-1960s, acute respiratory distress syndrome (ARDS) is a life-threatening form of respiratory failure with an overall mortality rate of approximately 40%. Despite significant advances in the understanding and treatment of ARDS, no substantive pharmacologic therapy has proven to be beneficial, and current management continues to be primarily supportive. Beyond their antibacterial activity, several antibiotics such as macrolides and tetracyclines exert pleiotropic immunomodulatory effects that might be able to rectify the dysregulated inflammatory response present in patients with ARDS. This review aims to provide an overview of preclinical and clinical studies that describe the immunomodulatory effects of antibiotics in ARDS. Moreover, the underlying mechanisms of their immunomodulatory properties will be discussed. Further studies are necessary to investigate their full therapeutic potential and to identify ARDS phenotypes which are most likely to benefit from their immunomodulatory effects.

Differential urine proteome analysis of a ventilator-induced lung injury rat model by label-free quantitative and parallel reaction monitoring proteomics

Urine is a promising resource for biomarker research. Therefore, the purpose of this study was to investigate potential urinary biomarkers to monitor the disease activity of ventilator-induced lung injury (VILI). In the discovery phase, a label-free data-dependent acquisition (DDA) quantitative proteomics method was used to profile the urinary proteomes of VILI rats. For further validation, the differential proteins were verified by parallel reaction monitoring (PRM)-targeted quantitative proteomics. In total, 727 high-confidence proteins were identified with at least 1 unique peptide (FDR ≤ 1%). Compared to the control group, 110 proteins (65 upregulated, 45 downregulated) were significantly changed in the VILI group (1.5-fold change, P < 0.05). The canonical pathways and protein-protein interaction analyses revealed that the differentially expressed proteins were enriched in multiple functions, including oxidative stress and inflammatory responses. Finally, thirteen proteins were identified as candidate biomarkers for VILI by PRM validation. Among these PRM-validated proteins, AMPN, MEP1B, LYSC1, DPP4 and CYC were previously reported as lung-associated disease biomarkers. SLC31, MEP1A, S15A2, NHRF1, XPP2, GGT1, HEXA, and ATPB were newly discovered in this study. Our results suggest that the urinary proteome might reflect the pathophysiological changes associated with VILI. These differential proteins are potential urinary biomarkers for the activity of VILI.

Coagulation Dysfunction in Acute Respiratory Distress Syndrome and Its Potential Impact in Inflammatory Subphenotypes

The Acute Respiratory Distress Syndrome (ARDS) has caused innumerable deaths worldwide since its initial description over five decades ago. Population-based estimates of ARDS vary from 1 to 86 cases per 100,000, with the highest rates reported in Australia and the United States. This syndrome is characterised by a breakdown of the pulmonary alveolo-epithelial barrier with subsequent severe hypoxaemia and disturbances in pulmonary mechanics. The underlying pathophysiology of this syndrome is a severe inflammatory reaction and associated local and systemic coagulation dysfunction that leads to pulmonary and systemic damage, ultimately causing death in up to 40% of patients. Since inflammation and coagulation are inextricably linked throughout evolution, it is biological folly to assess the two systems in isolation when investigating the underlying molecular mechanisms of coagulation dysfunction in ARDS. Although the body possesses potent endogenous systems to regulate coagulation, these become dysregulated and no longer optimally functional during the acute phase of ARDS, further perpetuating coagulation, inflammation and cell damage. The inflammatory ARDS subphenotypes address inflammatory differences but neglect the equally important coagulation pathway. A holistic understanding of this syndrome and its subphenotypes will improve our understanding of underlying mechanisms that then drive translation into diagnostic testing, treatments, and improve patient outcomes.

Value of Thrombomodulin as a Marker for Sepsis in Critically Ill Children

OBJECTIVE

Pediatric sepsis is altered organ function in critically ill children and a main etiology of mortality for children. Therefore, the authors aimed to assess the role of serum thrombomodulin as valuable biomarker in the diagnosis and prognosis of sepsis in acutely ill pediatrics in the intensive unit.

METHODS

This prospective clinical study conducted on 140 acutely ill patients admitted to the Pediatric Intensive Care Unit (PICU) of Menoufia University Hospital and 50 apparently healthy controls from October 2018 through September 2019. All included children were subjected to clinical examination and the Pediatric Risk of Mortality (PRISM) and Pediatric Index of Mortality II (PIM II) scores were calculated. Serum thrombomodulin was measured for both patients and the control group upon admission. The children were followed for a period of 30 d.

RESULTS

Serum thrombomodulin level was increased among all the patients and those with systemic inflammatory response syndrome (SIRS), sepsis and severe sepsis compared with controls (p < 0.001). Furthermore, serum thrombomodulin was higher in patients who died than who survived (p = 0.005). Thrombomodulin had area under Receiver Operating Characteristic Curve (AUC) =0.915 for predicting sepsis, whereas C-reactive protein had AUC = 0.789. According to the prognosis, thrombomodulin had AUC = 0.711 for predicting mortality whereas PRISM and PIM scores had AUC = (0.918, 0.960) respectively.

CONCLUSIONS

Serum thrombomodulin is a promising marker for pediatric sepsis. The data showed that serum thrombomodulin had a valuable role in diagnosis of sepsis early in critically ill pediatrics.

Thrombomodulin is associated with increased mortality and organ failure in mechanically ventilated children with acute respiratory failure: biomarker analysis from a multicenter randomized controlled trial

BACKGROUND

Acute respiratory failure (ARF) can progress to acute respiratory distress syndrome and death. Biomarkers may allow for risk stratification and prognostic enrichment in ARF. Thrombomodulin (TM) is a transmembrane antithrombotic mediator expressed in endothelial cells. It is cleaved into its soluble form (sTM) during inflammation and vascular injury. Levels of sTM correlate with inflammation and end organ dysfunction.

METHODS

This was a prospective observational study of 432 patients aged 2 weeks-17 years requiring invasive mechanical ventilation. It was ancillary to the multicenter clinical trial, Randomized Evaluation of Sedation Titration for Respiratory Failure (RESTORE). After consent, patients had up to 3 plasma samples collected at 24-h intervals within 5 days after intubation. sTM was assayed by ELISA. The Hazard ratio (HR) for 90-day mortality was determined by Cox regression. Mixed effect models (MEM) were used to test for association with extrapulmonary multiorgan failure (MOF) and oxygenation index (OI). Age, race, sex and PRISM-III scores were used as confounding variables for multivariable analyses.

RESULTS

sTM values ranged from 16.6 to 670.9 ng/ml within 5 days after intubation. Higher sTM was associated with increased 90-day mortality (n = 432, adjusted HR = 1.003, p = 0.02) and worse OI in the first 5 days after intubation (n = 252, Estimate = 0.02, p < 0.01). Both initial and slope of sTM were associated with increased extrapulmonary MOF in unadjusted and adjusted analyses (Intercept, Estimate = 0.003, p < 0.0001; and slope, Estimate = 0.01, p = 0.0009, n = 386).

CONCLUSIONS

Plasma sTM is associated with mortality, severity of hypoxic respiratory failure and worsening extrapulmonary MOF in children with ARF. This suggests a role of vascular injury in the pathogenesis of ARF and provides potential applicability towards targeted therapies.

TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT00814099 . In healthy lung endothelium, thrombomodulin (TM) recruits thrombin to activate Protein-C (PC/APC), that inhibits plasminogen activator-1 (PAI-1) and thrombosis. In inflamed and damaged endothelium, TM is cleaved into its soluble form (sTM), precluding its usual regulation of thrombosis. In this study, we measured plasma sTM levels in pediatric patients with respiratory failure and found that sTM correlated with mortality and other clinical markers of poor outcomes.

Inflammatory Biomarkers Are Associated With a Decline in Functional Status at Discharge in Children With Acute Respiratory Failure: An Exploratory Analysis

Supplemental Digital Content is available in the text.

To evaluate the link between early acute respiratory failure and functional morbidity in survivors using the plasma biomarkers interleukin-8, interleukin-1 receptor antagonist, thrombomodulin, and plasminogen activator inhibitor-1. We hypothesized that children with acute respiratory failure with higher levels of inflammation would have worse functional outcomes at discharge, as measured by Pediatric Overall Performance Category.

Novel Perspectives Regarding the Pathology, Inflammation, and Biomarkers of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is an acute inflammation of the lung resulting from damage to the alveolar-capillary membrane, and it is diagnosed using a combination of clinical and physiological variables. ARDS develops in approximately 10% of hospitalised patients with pneumonia and has a mortality rate of approximately 40%. Recent research has identified several biomarkers associated with ARDS pathophysiology, and these may be useful for diagnosing and monitoring ARDS. They may also highlight potential therapeutic targets. This review summarises our current understanding of those clinical biomarkers: (1) biomarkers of alveolar and bronchiolar injury, (2) biomarkers of endothelial damage and coagulation, and (3) biomarkers for treatment responses.

Endothelial Damage in Acute Respiratory Distress Syndrome

The pulmonary endothelium is a metabolically active continuous monolayer of squamous endothelial cells that internally lines blood vessels and mediates key processes involved in lung homoeostasis. Many of these processes are disrupted in acute respiratory distress syndrome (ARDS), which is marked among others by diffuse endothelial injury, intense activation of the coagulation system and increased capillary permeability. Most commonly occurring in the setting of sepsis, ARDS is a devastating illness, associated with increased morbidity and mortality and no effective pharmacological treatment. Endothelial cell damage has an important role in the pathogenesis of ARDS and several biomarkers of endothelial damage have been tested in determining prognosis. By further understanding the endothelial pathobiology, development of endothelial-specific therapeutics might arise. In this review, we will discuss the underlying pathology of endothelial dysfunction leading to ARDS and emerging therapies. Furthermore, we will present a brief overview demonstrating that endotheliopathy is an important feature of hospitalised patients with coronavirus disease-19 (COVID-19).

Systemic Endothelial Activation Is Associated With Early Acute Respiratory Distress Syndrome in Children With Extrapulmonary Sepsis

OBJECTIVES

Systemic endothelial activation may contribute to sepsis-associated organ injury, including acute respiratory distress syndrome. We hypothesized that children with extrapulmonary sepsis with versus without acute respiratory distress syndrome would have plasma biomarkers indicative of increased endothelial activation and that persistent biomarker changes would be associated with poor outcome.

DESIGN

Observational cohort.

SETTING

Academic PICU.

PATIENTS

Patients less than 18 years old with sepsis from extrapulmonary infection with (n = 46) or without (n = 54) acute respiratory distress syndrome and noninfected controls (n = 19).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Endothelial (angiopoietin-1, angiopoietin-2, tyrosine kinase with immunoglobulin-like loop epidermal growth factor homology domain 2, vascular endothelial growth factor, soluble fms-like tyrosine kinase, von Willebrand factor, E-selectin, intercellular adhesion molecule, vascular cell adhesion molecule, thrombomodulin) and inflammatory biomarkers (C-reactive protein, interleukin-6, and interleukin-8) were measured from peripheral plasma collected within 3 days (time 1) of sepsis recognition and at 3-6 days (time 2) and 7-14 days (time 3). Time 1 biomarkers and longitudinal measurements were compared for sepsis patients with versus without acute respiratory distress syndrome and in relation to complicated course, defined as greater than or equal to two organ dysfunctions at day 7 or death by day 28. Angiopoietin-2, angiopoietin-2/angiopoietin-1 ratio, tyrosine kinase with immunoglobulin-like loop epidermal growth factor homology domain 2, vascular endothelial growth factor, von Willebrand factor, E-selectin, intercellular adhesion molecule, vascular cell adhesion molecule, thrombomodulin, endocan, C-reactive protein, interleukin-6, and interleukin-8 were different between sepsis and noninfected control patients at time 1. Among patients with sepsis, those with acute respiratory distress syndrome had higher angiopoietin-2/angiopoietin-1 ratio, vascular endothelial growth factor, vascular cell adhesion molecule, thrombomodulin, endocan, interleukin-6, and interleukin-8 than those without acute respiratory distress syndrome (all p < 0.003). Angiopoietin-2 and angiopoietin-2/angiopoietin-1 ratio remained higher in sepsis with versus without acute respiratory distress syndrome after multivariable analyses. Time 1 measures of angiopoietin-2, angiopoietin-2/-1 ratio, von Willebrand factor, and endocan were indicative of complicated course in all sepsis patients (all area under the receiver operating curve ≥ 0.80). In sepsis without acute respiratory distress syndrome, soluble fms-like tyrosine kinase decreased more quickly and von Willebrand factor and thrombomodulin decreased more slowly in those with complicated course.

CONCLUSIONS

Children with extrapulmonary sepsis with acute respiratory distress syndrome had plasma biomarkers indicative of greater systemic endothelial activation than those without acute respiratory distress syndrome. Several endothelial biomarkers measured near sepsis recognition were associated with complicated course, whereas longitudinal biomarker changes yielded prognostic information only in those without sepsis-associated acute respiratory distress syndrome.

COVID-19-associated coagulopathy: An exploration of mechanisms

An ongoing global pandemic of viral pneumonia (coronavirus disease [COVID-19]), due to the virus SARS-CoV-2, has infected millions of people and remains a threat to many more. Most critically ill patients have respiratory failure and there is an international effort to understand mechanisms and predictors of disease severity. Coagulopathy, characterized by elevations in D-dimer and fibrin(ogen) degradation products (FDPs), is associated with critical illness and mortality in patients with COVID-19. Furthermore, increasing reports of microvascular and macrovascular thrombi suggest that hemostatic imbalances may contribute to the pathophysiology of SARS-CoV-2 infection. We review the laboratory and clinical findings of patients with COVID-19-associated coagulopathy, and prior studies of hemostasis in other viral infections and acute respiratory distress syndrome. We hypothesize that an imbalance between coagulation and inflammation may result in a hypercoagulable state. Although thrombosis initiated by the innate immune system is hypothesized to limit SARS-CoV-2 dissemination, aberrant activation of this system can cause endothelial injury resulting in loss of thromboprotective mechanisms, excess thrombin generation, and dysregulation of fibrinolysis and thrombosis. The role various components including neutrophils, neutrophil extracellular traps, activated platelets, microparticles, clotting factors, inflammatory cytokines, and complement play in this process remains an area of active investigation and ongoing clinical trials target these different pathways in COVID-19.

Overcoming Barriers: The Endothelium As a Linchpin of Coronavirus Disease 2019 Pathogenesis?

OBJECTIVE

Coronavirus disease 2019 (COVID-19) is a global pandemic involving >5 500 000 cases worldwide as of May 26, 2020. The culprit is the severe acute respiratory syndrome coronavirus-2, which invades cells by binding to ACE2 (angiotensin-converting enzyme 2). While the majority of patients mount an appropriate antiviral response and recover at home, others progress to respiratory distress requiring hospital admission for supplemental oxygen. In severe cases, deterioration to acute respiratory distress syndrome necessitating mechanical ventilation, development of severe thrombotic events, or cardiac injury and dysfunction occurs. In this review, we highlight what is known to date about COVID-19 and cardiovascular risk, focusing in on the putative role of the endothelium in disease susceptibility and pathogenesis. Approach and Results: Cytokine-driven vascular leak in the lung alveolar-endothelial interface facilitates acute lung injury in the setting of viral infection. Given that the virus affects multiple organs, including the heart, it likely gains access into systemic circulation by infecting or passing from the respiratory epithelium to the endothelium for viral dissemination. Indeed, cardiovascular complications of COVID-19 are highly prevalent and include acute cardiac injury, myocarditis, and a hypercoagulable state, all of which may be influenced by altered endothelial function. Notably, the disease course is worse in individuals with preexisting comorbidities that involve endothelial dysfunction and may be linked to elevated ACE2 expression, such as diabetes mellitus, hypertension, and cardiovascular disease.

CONCLUSIONS

Rapidly emerging data on COVID-19, together with results from studies on severe acute respiratory syndrome coronavirus-1, are providing insight into how endothelial dysfunction may contribute to the pandemic that is paralyzing the globe. This may, in turn, inform the design of biomarkers predictive of disease course, as well as therapeutics targeting pathogenic endothelial responses.

Biomarkers in pediatric sepsis: a review of recent literature

Sepsis remains the leading cause of death in infants and children worldwide. Prompt diagnosis and monitoring of infection is pivotal to guide therapy and optimize outcomes. No single biomarker has so far been identified to accurately diagnose sepsis, monitor response and predict severity. We aimed to assess existing evidence of available sepsis biomarkers, and their utility in pediatric population. C-reactive protein and procalcitonin remain the most extensively evaluated and used biomarkers. However, biomarkers related to endothelial damage, vasodilation, oxidative stress, cytokines/chemokines and cell bioproducts have also been identified, often with regard to the site of infection and etiologic pathogen; still, with controversial utility. A multi-biomarker model driven by genomic tools could establish a personalized approach in future disease management.

A systematic review of biomarkers multivariately associated with acute respiratory distress syndrome development and mortality

Background

Heterogeneity of acute respiratory distress syndrome (ARDS) could be reduced by identification of biomarker-based phenotypes. The set of ARDS biomarkers to prospectively define these phenotypes remains to be established.

Objective

To provide an overview of the biomarkers that were multivariately associated with ARDS development or mortality.

Data sources

We performed a systematic search in Embase, MEDLINE, Web of Science, Cochrane CENTRAL, and Google Scholar from inception until 6 March 2020.

Study selection

Studies assessing biomarkers for ARDS development in critically ill patients at risk for ARDS and mortality due to ARDS adjusted in multivariate analyses were included.

Data extraction and synthesis

We included 35 studies for ARDS development (10,667 patients at risk for ARDS) and 53 for ARDS mortality (15,344 patients with ARDS). These studies were too heterogeneous to be used in a meta-analysis, as time until outcome and the variables used in the multivariate analyses varied widely between studies. After qualitative inspection, high plasma levels of angiopoeitin-2 and receptor for advanced glycation end products (RAGE) were associated with an increased risk of ARDS development. None of the biomarkers (plasma angiopoeitin-2, C-reactive protein, interleukin-8, RAGE, surfactant protein D, and Von Willebrand factor) was clearly associated with mortality.

Conclusions

Biomarker data reporting and variables used in multivariate analyses differed greatly between studies. Angiopoeitin-2 and RAGE in plasma were positively associated with increased risk of ARDS development. None of the biomarkers independently predicted mortality. Therefore, we suggested to structurally investigate a combination of biomarkers and clinical parameters in order to find more homogeneous ARDS phenotypes.

PROSPERO identifier

PROSPERO, CRD42017078957

Effect of sevoflurane and propofol on tourniquet-induced endothelial damage: a pilot randomized controlled trial for knee-ligament surgery

BACKGROUND

The glycocalyx layer is a key structure in the endothelium. Tourniquet-induced ischemic periods are used during orthopedic surgery, and the reactive oxygen species generated after ischemia-reperfusion may mediate the shedding of the glycocalyx. Here, we describe the effects of tourniquet-induced ischemia-reperfusion and compare the effects of sevoflurane and propofol on the release of endothelial biomarkers after ischemia-reperfusion in knee-ligament surgery.

METHODS

This pilot, single-center, blinded, randomized, controlled trial included 16 healthy patients. After spinal anesthesia, hypnosis was achieved with sevoflurane or propofol according to randomization. During the perioperative period, five venous blood samples were collected for quantification of syndecan-1, heparan sulfate, and thrombomodulin from blood serum by using ELISA assays kits. Sample size calculation was performed to detect a 25% change in the mean concentration of syndecan-1 with an alpha of 0.05 and power of 80%.

RESULTS

For our primary outcome, a two-way ANOVA with post-hoc Bonferroni correction analysis showed no differences in syndecan-1 concentrations between the sevoflurane and propofol groups at any time point. In the sevoflurane group, we noted an increase in syndecan-1 concentrations 90 min after tourniquet release in the sevoflurane group from 34.6 ± 24.4 ng/mL to 47.9 ± 29.8 ng/mL (Wilcoxon test, p < 0.01) that was not observed in patients randomized to the propofol group. The two-way ANOVA showed no intergroup differences in heparan sulfate and thrombomodulin levels.

CONCLUSIONS

Superficial endothelial damage without alterations in the cell layer integrity was observed after tourniquet knee-ligament surgery. There was no elevation in serum endothelial biomarkers in the propofol group patients. Sevoflurane did not show the protective effect observed in in vitro and in vivo studies.

TRIAL REGISTRATION

The trial was registered in www.clinicaltrials.gov (ref: NCT03772054, Registered 11 December 2018).

Biomarkers in pediatric acute respiratory distress syndrome

Pediatric acute respiratory distress syndrome (PARDS) is a heterogenous process resulting in a severe acute lung injury. A single indicator does not exist for PARDS diagnosis. Rather, current diagnosis requires a combination of clinical and physiologic variables. Similarly, there is little ability to predict the path of disease, identify those at high risk of poor outcomes or target therapies specific to the underlying pathophysiology. Biomarkers, a measured indicator of a pathologic state or response to intervention, have been studied in PARDS due to their potential in diagnosis, prognostication and measurement of therapeutic response. Additionally, PARDS biomarkers show great promise in furthering our understanding of specific subgroups or endotypes in this highly variable disease, and thereby predict which patients may benefit and which may be harmed by PARDS specific therapies. In this chapter, we review the what, when, why and how of biomarkers in PARDS and discuss future directions in this quickly changing landscape.

Association of endothelial and glycocalyx injury biomarkers with fluid administration, development of acute kidney injury, and 90-day mortality: data from the FINNAKI observational study

Background

Injury to endothelium and glycocalyx predisposes to vascular leak, which may subsequently lead to increased fluid requirements and worse outcomes. In this post hoc study of the prospective multicenter observational Finnish Acute Kidney Injury (FINNAKI) cohort study conducted in 17 Finnish intensive care units, we studied the association of Syndecan-1 (SDC-1), Angiopoetin-2 (Ang-2), soluble thrombomodulin (sTM), vascular adhesion protein-1 (VAP-1) and interleukin-6 (IL-6) with fluid administration and balance among septic critical care patients and their association with development of acute kidney injury (AKI) and 90-day mortality.

Results

SDC-1, Ang-2, sTM, VAP-1 and IL-6 levels were measured at ICU admission from 619 patients with sepsis. VAP-1 decreased (p < 0.001) and IL-6 increased (p < 0.001) with increasing amounts of administered fluid, but other biomarkers did not show differences according to fluid administration. In linear regression models adjusted for IL-6, only VAP-1 was significantly associated with fluid administration on day 1 (p < 0.001) and the cumulative fluid balance on day 5/ICU discharge (p = 0.001). Of 415 patients admitted without AKI, altogether 112 patients (27.0%) developed AKI > 12 h from ICU admission (AKI_>12 h). They had higher sTM levels than patients without AKI, and after multivariable adjustment log, sTM level was associated with AKI_>12 h with OR (95% CI) of 12.71 (2.96–54.67), p = 0.001). Ninety-day non-survivors (n = 180; 29.1%) had higher SDC-1 and sTM levels compared to survivors. After adjustment for known confounders, log SDC-1 (OR [95% CI] 2.13 [1.31–3.49], p = 0.002), log sTM (OR [95% CI] 7.35 [2.29–23.57], p < 0.001), and log Ang-2 (OR [95% CI] 2.47 [1.44–4.14], p = 0.001) associated with an increased risk for 90-day mortality. Finally, patients who had high levels of all three markers, namely, SDC-1, Ang-2 and sTM, had an adjusted OR of 5.61 (95% CI 2.67–11.79; p < 0.001) for 90-day mortality.

Conclusions

VAP-1 and IL-6 associated with fluid administration on the first ICU day. After adjusting for confounders, sTM was associated with development of AKI after 12 h from ICU admission. SDC-1, Ang-2 and sTM were independently associated with an increased risk for 90-day mortality.

Prognostic value of endothelial biomarkers in refractory cardiogenic shock with ECLS: a prospective monocentric study

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is often used in critical patients with severe myocardial failure. However, the mortality rate of patients on ECMO is often high. Recent studies have suggested that endothelial activation with subsequent vascular barrier breakdown is a critical pathogenic mechanism of organ damage and is related to the outcome of critical illness. This study aimed to determine whether endothelial biomarkers can be served as prognostic factors for the outcome of patients on ECMO.

METHODS

This prospective study enrolled 23 critically ill patients on veno-arterial ECMO in the intensive care units of a tertiary care hospital between March 2014 and February 2015. Serum samples were tested for thrombomodulin, angiopoietin (Ang)-1, Ang-2, and vascular endothelial growth factor (VEGF). Demographic, clinical, and laboratory data were also collected.

RESULTS

The overall mortality rate was 56.5%. The combination of Ang-2 at the time of ECMO support (day 0) and VEGF at day 2 had the ability to discriminate mortality (area under receiver operating characteristic curve [AUROC], 0.854; 95% confidence interval: 0.645-0.965).

CONCLUSIONS

In this study, we found that the combination of Ang-2 at day 0 and VEGF at day 2 was a modest model for mortality discrimination in this group of patients.

Inflammatory response of mesenchymal stromal cells after in vivo exposure with selected trauma-related factors and polytrauma serum

Polytrauma (PT) is a life-threatening disease and a major global burden of injury. Mesenchymal stromal cells (MSC) might be a therapeutic option for PT patients due to their anti-inflammatory and regenerative potential. We hypothesised that the inflammatory response of MSC is similar after exposure to selected trauma-relevant factors to sera from PT patients (PTS). Therefore, we investigated the effects of a mixture of defined factors, supposed to play a role on MSC in the early phase of PT. Additionally, in a translational approach we investigated the effect of serum from PT patients on MSC in vitro. MSC were incubated with a PT cocktail in physiological (PTCL) and supra-physiological (PTCH) concentrations or PTS. The effect on gene expression and protein secretion of MSC was analysed by RNA sequencing, ELISA and Multiplex assays of cell culture supernatant. Stimulation of MSC with PTCH, PTCL or IL1B led to significant up- or downregulation of 470, 183 and 469 genes compared to unstimulated MSC at 6 h. The intersection of differentially expressed genes in these groups was very high (92% overlap with regard to the PTCL group; treated for 6 h). Cytokine secretion profile of MSC revealed that IL1B mimics the effect of a more complex PT cocktail as well. However, there was only a minor proportion of overlapping differentially expressed genes between the MSC group stimulated with early times of PTS and the MSC group stimulated with PTCH, PTCL and IL1B. In conclusion, the effect of sera from PT patients on MSC activation cannot be simulated by the chosen trauma-relevant factors. Furthermore, we conclude that while IL1B might be useful to prime MSC prior to therapeutic application, it might not be as useful for the in vitro study of functional properties of MSC in the context of PT.

Acute Respiratory Distress Syndrome Phenotypes

The acute respiratory distress syndrome (ARDS) phenotype was first described over 50 years ago and since that time significant progress has been made in understanding the biologic processes underlying the syndrome. Despite this improved understanding, no pharmacologic therapies aimed at the underlying biology have been proven effective in ARDS. Increasingly, ARDS has been recognized as a heterogeneous syndrome characterized by subphenotypes with distinct clinical, radiographic, and biologic differences, distinct outcomes, and potentially distinct responses to therapy. The Berlin Definition of ARDS specifies three severity classifications: mild, moderate, and severe based on the PaO₂ to FiO₂ ratio. Two randomized controlled trials have demonstrated a potential benefit to prone positioning and neuromuscular blockade in moderate to severe phenotypes of ARDS only. Precipitating risk factor, direct versus indirect lung injury, and timing of ARDS onset can determine other clinical phenotypes of ARDS after admission. Radiographic phenotypes of ARDS have been described based on a diffuse versus focal pattern of infiltrates on chest imaging. Finally and most promisingly, biologic subphenotypes or endotypes have increasingly been identified using plasma biomarkers, genetics, and unbiased approaches such as latent class analysis. The potential of precision medicine lies in identifying novel therapeutics aimed at ARDS biology and the subpopulation within ARDS most likely to respond. In this review, we discuss the challenges and approaches to subphenotype ARDS into clinical, radiologic, severity, and biologic phenotypes with an eye toward the future of precision medicine in critical care.

The role of biomarkers of endothelial activation in predicting morbidity and mortality in patients with severe sepsis and septic shock in intensive care: A prospective observational study

INTRODUCTION

Endothelial dysfunction plays an essential role in the pathogenesis of sepsis. The study aimed to illustrate the associations between the dynamic change (from day 1 to day 7) in biomarker concentration of endothelial dysfunction and outcomes in severe sepsis and septic shock in the intensive care unit (ICU).

MATERIALS AND METHODS

We studied 102 patients enrolled in the Beijing Chao-yang Hospital affiliated with the Capital Medical University. A receiver operating characteristic (ROC) curve were used to assess the prognostic values of the circulating adhesion Angiopoietin-2/Angiopoietin-1 ratio (Ang-2/Ang-1) and Angiopoietin-1/Tie-2 ratio (Ang-1/Tie-2), intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and thrombomodulin (TM). Spearman's rank correlation and a multiple regression analysis were used to assess the relationship between the change in sequential organ failure assessment (Δ SOFA) score (SOFA score at day 7 minus SOFA score at day 1) and the levels of Δ Ang-2/Ang-1 and Δ Ang-1/Tie-2 ratios, ΔsICAM-1, ΔsVCAM-1 and Δ sTM.

RESULTS

The Ang-2/Ang-1 ratio, sICAM-1, sVCAM-1 and sTM levels significantly increased from day 1 to day 7 (all p = 0.045), and the Ang-1/Tie-2 ratio level markedly decreased from day 1 and day 7 (p = 0.027) in non-survivors. The biomarkers at Days 1 and 7 had significant prognostic value for 90-day mortality in severe sepsis and septic shock in ICU. The difference in biomarkers for endothelial dysfunction were suggested to be effective, independent predictors of changes in Δ SOFA.

CONCLUSIONS

Endothelial dysfunction may constitute an independent contributor to sepsis-associated outcomes in ICU.

Endothelial biomarkers in human sepsis: pathogenesis and prognosis for ARDS

Experimental models of sepsis in small and large animals and a variety of in vitro preparations have established several basic mechanisms that drive endothelial injury. This review is focused on what can be learned from the results of clinical studies of plasma biomarkers of endothelial injury and inflammation in patients with sepsis. There is excellent evidence that elevated plasma levels of several biomarkers of endothelial injury, including von Willebrand factor antigen (VWF), angiopoietin-2 (Ang-2), and soluble fms-like tyrosine kinase 1 (sFLT-1), and biomarkers of inflammation, especially interleukin-8 (IL-8) and soluble tumor necrosis factor receptor (sTNFr), identify sepsis patients with a higher mortality. There are also some data that elevated levels of endothelial biomarkers can identify which patients with non-pulmonary sepsis will develop acute respiratory distress syndrome (ARDS). If ARDS patients are divided among those with indirect versus direct lung injury, then there is an association of elevated levels of endothelial biomarkers in indirect injury and markers of inflammation and alveolar epithelial injury in patients with direct lung injury. New research suggests that the combination of biologic and clinical markers may make it possible to segregate patients with ARDS into hypo- versus hyper-inflammatory phenotypes that may have implications for therapeutic responses to fluid therapy. Taken together, the studies reviewed here support a primary role of the microcirculation in the pathogenesis and prognosis of ARDS after sepsis. Biological differences identified by molecular patterns could explain heterogeneity of treatment effects that are not explained by clinical factors alone.

Association of day 4 cumulative fluid balance with mortality in critically ill patients with influenza: A multicenter retrospective cohort study in Taiwan

Background

Fluid balance is a fundamental management of patients with sepsis, and this study aimed to investigate the impact of cumulative fluid balance on critically ill patients with influenza admitted to an intensive care unit (ICU).

Methods

This multicenter retrospective cohort study was conducted by the Taiwan Severe Influenza Research Consortium (TSIRC) which includes eight medical centers. Patients with virology-proven influenza infection admitted to ICUs between October 2015 and March 2016 were included for analysis.

Results

A total of 296 patients were enrolled (mean age: 61.4±15.6 years; 62.8% men), and 92.2% (273/296) of them required mechanical ventilation. In the survivors, the daily fluid balance was positive from day 1 to day 3, and then gradually became negative from day 4 to day 7, whereas daily fluid balance was continuously positive in the non-survivors. Using the cumulative fluid balance from day 1–4 as a cut-off point, we found that a negative cumulative day 1–4 fluid balance was associated with a lower 30-day mortality rate (log-rank test, P = 0.003). To evaluate the impact of shock on this association, we divided the patients into shock and non-shock groups. The positive correlation between negative day 1–4 fluid balance and mortality was significant in the non-shock group (log-rank test, P = 0.008), but not in the shock group (log-rank test, P = 0.396). In a multivariate Cox proportional hazard regression model adjusted for age, sex, cerebrovascular disease, and PaO2/FiO2, day 1–4 fluid balance was independently associated with a higher 30-day mortality rate (aHR 1.088, 95% CI: 1.007–1.174).

Conclusions

A negative day 1–4 cumulative fluid balance was associated with a lower mortality rate in critically ill patients with influenza. Our findings indicate the critical role of conservative fluid strategy in the management of patients with complicated influenza.

Anticoagulant therapy in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) presents a complex pathophysiology characterized by pulmonary activated coagulation and reduced fibrinolysis. Despite advances in supportive care of this syndrome, morbidity and mortality remains high, leading to the need of novel therapies to combat this disease. Focus these therapies in the inhibition of ARDS development pathophysiology is essential. Beneficial effects of anticoagulants in ARDS have been proved in preclinical and clinical trials, thanks to its anticoagulant and anti-inflammatory properties. Moreover, local administration by nebulization in the alveolar compartment increases local efficacy and does not produce systemic bleeding. In this review the coagulation and fibrinolytic pathway and its pharmacological targets to treat ARDS are summarized.

Molecular and Immune Biomarkers in Acute Respiratory Distress Syndrome: A Perspective From Members of the Pulmonary Pathology Society

Acute respiratory distress syndrome (ARDS) is a multifactorial syndrome with high morbidity and mortality rates, characterized by deficiency in gas exchange and lung mechanics that lead to hypoxemia, dyspnea, and respiratory failure. Histologically, ARDS is characterized by an acute, exudative phase, combining diffuse alveolar damage and noncardiogenic edema, followed by a later fibroproliferative phase. Despite an enhanced understanding of ARDS pathogenesis, the capacity to predict the development of ARDS and to risk-stratify patients with the disease remains limited. Biomarkers may help to identify patients at the greatest risk of developing ARDS, to evaluate response to therapy, to predict outcome, and to improve clinical trials. The ARDS pathogenesis is presented in this article, as well as concepts and information on biomarkers that are currently used clinically or are available for laboratory use by academic and practicing pathologists and the developing and validating of new assays, focusing on the assays' major biologic roles in lung injury and/or repair and to ultimately suggest innovative, therapeutic approaches.

Increased serum thrombomodulin level is associated with disease severity and mortality in pediatric sepsis

Background

Endothelial dysfunction plays an important role in the pathophysiology of sepsis. As previously reported, the serum thrombomodulin is elevated in diseases associated with endothelial injury.

Objective

The aim of this study was to investigate the association of serum thrombomodulin level in different pediatric sepsis syndromes and evaluate the relationship with disease severity and mortality.

Methods

We prospectively collected cases of sepsis treated in a pediatric intensive care unit from June 2012 to July 2015 at Chang Gung Children’s Hospital in Taoyuan, Taiwan. Clinical characteristics and serum thrombomodulin levels were analyzed.

Results

Increased serum thrombomodulin levels on days 1 and 3 of the diagnosis of sepsis were found in different pediatric sepsis syndromes. Patients with septic shock had significantly increased serum thrombomodulin levels on days 1 and 3 [day 1: median, 6.9 mU/ml (interquartile range (IQR): 5.8–12.8) and day 3: median, 5.8 mU/ml (IQR: 4.6–10.8)] compared to healthy controls [median, 3.4 mU/ml (IQR: 2.3–4.2)] (p = <0.001 and 0.001, respectively) and those with sepsis [day 1: median, 2.9 mU/ml (IQR: 1.8–4.7) and day 3: median, 3 mU/ml (IQR: 1.5–3.5)] and severe sepsis [day 1: median, 3.3 mU/ml (IQR: 1.3–8.6) and day 3: median, 4.4 mU/ml (IQR: 0.5–6)] (p = <0.001 and 0.001, respectively). There was also a significant positive correlation between serum thrombomodulin level on day 1 and day 1 PRISM-II, PELOD, P-MOD and DIC scores. The patients who died had significantly higher serum thrombomodulin levels on days 1 and 3 [day 1: median, 9.9 mU/ml (IQR: 6.2–15.6) and day 3: median, 10.4 mU/ml (IQR: 9.2–11.7)] than the survivors [day 1; median, 4.4 mU/ml (IQR: 2.2–7.5) and day 3: [median, 3.5 mU/ml (IQR: 1.6–5.7)] (p = 0.046 and 0.012, respectively).

Conclusion

Increased serum thrombomodulin levels were found in different pediatric sepsis syndromes and correlated with disease severity and mortality.