Pulmonary coagulopathy as a new target in therapeutic studies of acute lung injury or pneumonia—A review:

Intrapulmonary administration of recombinant activated factor VII in pediatric, adolescent, and young adult oncology and hematopoietic cell transplant patients with pulmonary hemorrhage

Introduction

Diffuse alveolar hemorrhage (DAH) is a devastating disease process with 50-100% mortality in oncology and hematopoietic cell transplant (HCT) recipients. High concentrations of tissue factors have been demonstrated in the alveolar wall in acute respiratory distress syndrome and DAH, along with elevated levels of tissue factor pathway inhibitors. Activated recombinant factor VII (rFVIIa) activates the tissue factor pathway, successfully overcoming the tissue factor pathway inhibitor (TFPI) inhibition of activation of Factor X. Intrapulmonary administration (IP) of rFVIIa in DAH is described in small case series with successful hemostasis and minimal complications.

Methods

We completed a single center retrospective descriptive study of treatment with rFVIIa and outcomes in pediatric oncology and HCT patients with pulmonary hemorrhage at a quaternary hematology/oncology hospital between 2011 and 2019. We aimed to assess the safety and survival of patients with pulmonary hemorrhage who received of IP rFVIIa.

Results

We identified 31 patients with pulmonary hemorrhage requiring ICU care. Thirteen patients received intrapulmonary rFVIIa, while eighteen patients did not. Overall, 13 of 31 patients (41.9%) survived ICU discharge. ICU survival (n=6) amongst those in the IP rFVIIa group was 46.2% compared to 38.9% (n=7) in those who did not receive IP therapy (p=0.69). Hospital survival was 46.2% in the IP group and 27.8% in the non-IP group (p=0.45). There were no adverse events noted from use of IP FVIIa.

Conclusions

Intrapulmonary rFVIIa can be safely administered in pediatric oncology patients with pulmonary hemorrhage and should be considered a viable treatment option for these patients.

PAI-1 genetic polymorphisms influence septic patients' outcomes by regulating neutrophil activity

BACKGROUND

Plasminogen activator inhibitor-1 (PAI-1) plays an important role in the pathophysiology of sepsis, but the exact mechanism remains debatable. In this study, we investigated the associations among the serum levels of PAI-1, the incidence of 4G/5G promoter PAI-1 gene polymorphisms, immunological indicators, and clinical outcomes in septic patients.

METHODS

A total of 181 patients aged 18-80 years with sepsis between November 2016 and August 2018 in the intensive care unit in the Xinhua Hospital were recruited in this retrospective study, with 28-day mortality as the primary outcome. The initial serum level of PAI-1 and the presence of rs1799768 single nucleotide polymorphisms (SNPs) were examined. Univariate logistic regression and multivariate analyses were performed to determine the factors associated with different genotypes of PAI-1, serum level of PAI-1, and 28-day mortality.

RESULTS

The logistic analysis suggested that a high serum level of PAI-1 was associated with the rs1799768 SNP of PAI-1 (4G/4G and 4G/5G) (Odds ratio [OR]: 2.49; 95% confidence interval [CI]: 1.09, 5.68). Furthermore, a high serum level of PAI-1 strongly influenced 28-day mortality (OR 3.36; 95% CI 1.51, 7.49). The expression and activation of neutrophils (OR 0.96; 95% CI 0.93, 0.99), as well as the changes in the expression patterns of cytokines and chemokine-associated neutrophils (OR: 1.00; 95% CI: 1.00, 1.00), were both regulated by the genotype of PAI-1.

CONCLUSIONS

Genetic polymorphisms of PAI-1 can influence the serum levels of PAI-1, which might contribute to mortality by affecting neutrophil activity. Thus, patients with severe sepsis might clinically benefit from enhanced neutrophil clearance and the resolution of inflammation via the regulation of PAI-1 expression and activity.

Pathophysiology of Hypoxemia in COVID-19 Lung Disease

As the pandemic has progressed, our understanding of hypoxemia in coronavirus disease 2019 (COVID-19) lung disease has become more nuanced, although much remains to be understood. In this article, we review ventilation-perfusion mismatching in COVID-19 and the evidence to support various biologic theories offered in explanation. In addition, the relationship between hypoxemia and other features of severe COVID-19 lung disease such as respiratory symptoms, radiographic abnormalities, and pulmonary mechanics is explored. Recognizing and understanding hypoxemia in COVID-19 lung disease remains essential for risk stratification, prognostication, and choice of appropriate treatments in severe COVID-19.

Association between coagulation disorder scores and in-hospital mortality in ARF patients: a retrospective analysis from the MIMIC-IV database

Introduction

Acute respiratory failure (ARF) has a high mortality rate, and currently, there is no convenient risk predictor. The coagulation disorder score was proven to be a promising metric for predicting in-hospital mortality, but its role in ARF patients remains unknown.

Methods

In this retrospective study, data were extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Patients diagnosed with ARF and hospitalized for more than 2 days at their first admission were included. The coagulation disorder score was defined based on the sepsis-induced coagulopathy score and was calculated by parameters, namely, additive platelet count (PLT), international normalized ratio (INR), and activated partial thromboplastin time (APTT), based on which the participants were divided into six groups.

Results

Overall, 5,284 ARF patients were enrolled. The in-hospital mortality rate was 27.9%. High levels of additive platelet score, INR score, and APTT score were significantly associated with increased mortality in ARF patients (P < 0.001). Binary logistic regression analysis showed that a higher coagulation disorder score was significantly related to the increased risk of in-hospital mortality in ARF patients (Model 2: coagulation disorder score = 6 vs. coagulation disorder score = 0: OR, 95% CI: 7.09, 4.07-12.34, P < 0.001). The AUC of the coagulation disorder score was 0.611 (P < 0.001), which was smaller than that of sequential organ failure assessment (SOFA) (De-long test P = 0.014) and simplified acute physiology score II (SAPS II) (De-long test P < 0.001) but larger than that of additive platelet count (De-long test P < 0.001), INR (De-long test P < 0.001), and APTT (De-long test P < 0.001), respectively. In subgroup analysis, we found that in-hospital mortality was markedly elevated with an increased coagulation disorder score in ARF patients. No significant interactions were observed in most subgroups. Of note, patients who did not administrate oral anticoagulant had a higher risk of in-hospital mortality than those who administrated oral anticoagulant (P for interaction = 0.024).

Conclusion

This study found a significant positive association between coagulation disorder scores and in-hospital mortality. The coagulation disorder score was superior to the single indicators (additive platelet count, INR, or APTT) and inferior to SAPS II and SOFA for predicting in-hospital mortality in ARF patients.

Predictors of venous thromboembolism in COVID-19 patients: results of the COVID-19 Brazilian Registry

Previous studies that assessed risk factors for venous thromboembolism (VTE) in COVID-19 patients have shown inconsistent results. Our aim was to investigate VTE predictors by both logistic regression (LR) and machine learning (ML) approaches, due to their potential complementarity. This cohort study of a large Brazilian COVID-19 Registry included 4120 COVID-19 adult patients from 16 hospitals. Symptomatic VTE was confirmed by objective imaging. LR analysis, tree-based boosting, and bagging were used to investigate the association of variables upon hospital presentation with VTE. Among 4,120 patients (55.5% men, 39.3% critical patients), VTE was confirmed in 6.7%. In multivariate LR analysis, obesity (OR 1.50, 95% CI 1.11-2.02); being an ex-smoker (OR 1.44, 95% CI 1.03-2.01); surgery ≤ 90 days (OR 2.20, 95% CI 1.14-4.23); axillary temperature (OR 1.41, 95% CI 1.22-1.63); D-dimer ≥ 4 times above the upper limit of reference value (OR 2.16, 95% CI 1.26-3.67), lactate (OR 1.10, 95% CI 1.02-1.19), C-reactive protein levels (CRP, OR 1.09, 95% CI 1.01-1.18); and neutrophil count (OR 1.04, 95% CI 1.005-1.075) were independent predictors of VTE. Atrial fibrillation, peripheral oxygen saturation/inspired oxygen fraction (SF) ratio and prophylactic use of anticoagulants were protective. Temperature at admission, SF ratio, neutrophil count, D-dimer, CRP and lactate levels were also identified as predictors by ML methods. By using ML and LR analyses, we showed that D-dimer, axillary temperature, neutrophil count, CRP and lactate levels are risk factors for VTE in COVID-19 patients.

Tissue factor in COVID-19-associated coagulopathy

Evidence of micro- and macro-thrombi in the arteries and veins of critically ill COVID-19 patients and in autopsies highlight the occurrence of COVID-19-associated coagulopathy (CAC). Clinical findings of critically ill COVID-19 patients point to various mechanisms for CAC; however, the definitive underlying cause is unclear. Multiple factors may contribute to the prothrombotic state in patients with COVID-19. Aberrant expression of tissue factor (TF), an initiator of the extrinsic coagulation pathway, leads to thrombotic complications during injury, inflammation, and infections. Clinical evidence suggests that TF-dependent coagulation activation likely plays a role in CAC. Multiple factors could trigger abnormal TF expression and coagulation activation in patients with severe COVID-19 infection. Proinflammatory cytokines that are highly elevated in COVID-19 (IL-1β, IL-6 and TNF-α) are known induce TF expression on leukocytes (e.g. monocytes, macrophages) and non-immune cells (e.g. endothelium, epithelium) in other conditions. Antiphospholipid antibodies, TF-positive extracellular vesicles, pattern recognition receptor (PRR) pathways and complement activation are all candidate factors that could trigger TF-dependent procoagulant activity. In addition, coagulation factors, such as thrombin, may further potentiate the induction of TF via protease-activated receptors on cells. In this systematic review, with other viral infections, we discuss potential mechanisms and cell-type-specific expressions of TF during SARS-CoV-2 infection and its role in the development of CAC.

Systemic thrombolytics as rescue therapy for COVID-19 patients with acute respiratory distress syndrome: A retrospective observational study

Background

Coronavirus disease 2019 (COVID-19) pneumonia with severe acute respiratory distress syndrome (ARDS) is often associated with a progressive respiratory failure that is refractory to maximal ventilatory support and other ARDS strategies. Studies show evidence of a hypercoagulable state in COVID-19 patients, including capillary thrombosis and alveolar fibrin deposits which impede normal gas exchange. In this context, thrombolysis is considered as a salvage therapy to rescue critically hypoxemic patients.

Methods

In this retrospective observational study, the efficacy of thrombolysis on outcome of COVID-19 ARDS with respiratory failure was analyzed. Patients with severe ARDS and d-dimer levels of 5 μg/ml or above were initiated on alteplase, as a 25 mg bolus followed by a 25 mg infusion over 22 h. Primary outcome was intensive care unit (ICU) mortality and secondary outcomes were change in PaO2/FiO2 24 h after thrombolysis, avoidance of intubation, ventilator free days (VFD), and ICU and hospital length-of-stay (LOS).

Results

Thirteen out of 34 patients with severe COVID ARDS underwent thrombolysis. They had lower ICU mortality than non-thrombolysed patients (23.1% vs. 71.4%, P = 0.006), greater percentage improvement in PaO2/FiO2 (116% vs. 31.5%, P = 0.002), more VFDs (13 days vs. 0 day, P = 0.004), and lesser requirement for intubation (23.1% vs. 76.2%, P = 0.004). ICU and hospital LOS were similar.

Conclusion

Thrombolysis can be considered as a rescue therapy for nonintubated COVID-19 ARDS patients with severe hypoxemic respiratory failure, who show evidence of a procoagulant state. Larger studies are needed before inclusion into the regular treatment protocol for COVID-19 patients.

Circulating Thrombomodulin: Release Mechanisms, Measurements, and Levels in Diseases and Medical Procedures

Thrombomodulin (TM) is a type-I transmembrane protein that is mainly expressed on endothelial cells and plays important roles in many biological processes. Circulating TM of different forms are also present in biofluids, such as blood and urine. Soluble TM (sTM), comprised of several domains of TM, is the major circulating TM which is generated by either enzymatic or chemical cleavage of the intact protein under different conditions. Under normal conditions, sTM is present in low concentrations (<10 ng/mL) in the blood but is elevated in several pathological conditions associated with endothelial dysfunction such as cardiovascular, inflammatory, infection, and metabolic diseases. Therefore, sTM level has been examined for monitoring disease development, such as disseminated intravascular coagulation (DIC), sepsis and multiple organ dysfunction syndrome in patients with novel coronavirus disease 2019 (COVID-19) recently. In addition, microvesicles (MVs) that contain membrane TM (MV-TM) have been found to be released from activated cells which also contribute to levels of circulating TM in certain diseases. Several release mechanisms of sTM and MV-TM have been reported, including enzymatic, chemical, and TM mutation mechanisms. Measurements of sTM and MV-TM have been developed and explored as biomarkers in many diseases. In this review, we summarize all these advances in three categories as follows: (1) release mechanisms of circulating TM, (2) methods for measuring circulating TM in biological samples, and (3) correlation of circulating TM with diseases. Altogether, it provides a whole picture of recent advances on circulating TM in health and disease.

Understanding the pathophysiology of typical acute respiratory distress syndrome and severe COVID-19

Introduction

Typical acute respiratory distress syndrome (ARDS) and severe coronavirus-19 (COVID-19) pneumonia share complex pathophysiology, a high mortality rate, and an unmet need for efficient therapeutics.

Areas covered

This review discusses the current advances in understanding the pathophysiologic mechanisms underlying typical ARDS and severe COVID-19 pneumonia, highlighting specific aspects of COVID-19-related acute hypoxemic respiratory failure that require attention. Two models have been proposed to describe the mechanisms of respiratory failure associated with typical ARDS and severe COVID-19 pneumonia.

Expert opinion

ARDS is defined as a syndrome rather than a distinct pathologic entity. There is great heterogeneity regarding the pathophysiologic, clinical, radiologic, and biological phenotypes in patients with ARDS, challenging clinicians, and scientists to discover new therapies. COVID-19 has been described as a cause of pulmonary ARDS and has reopened many questions regarding the pathophysiology of ARDS itself. COVID-19 lung injury involves direct viral epithelial cell damage and thrombotic and inflammatory reactions. There are some differences between ARDS and COVID-19 lung injury in aspects of aeration distribution, perfusion, and pulmonary vascular responses.

Recent Topics of Pneumococcal Vaccination: Indication of Pneumococcal Vaccine for Individuals at a Risk of Pneumococcal Disease in Adults

Pneumococcal disease is one of the most common and severe vaccine-preventable diseases (VPDs). Despite the advances in antimicrobial treatment, pneumococcal disease still remains a global burden and exhibits a high mortality rate among people of all ages worldwide. The immunization program of the pneumococcal conjugate vaccine (PCV) in children has decreased pneumococcal disease incidence in several countries. However, there are several problems regarding the pneumococcal vaccine, such as indications for immunocompetent persons with underlying medical conditions with a risk of pneumococcal disease, the balance of utility and cost, i.e., cost-effectiveness, vaccine coverage rate, serotype replacement, and adverse events. Especially for individuals aged 19-64 at risk of pneumococcal disease, physicians and vaccine providers should make a rational decision whether the patients should be vaccinated or not, since there is insufficient evidence supporting it. We describe this review regarding topics and problems regarding pneumococcal vaccination from the clinician's point of view.

Advocacy of targeting protease-activated receptors in severe coronavirus disease 2019

Identifying drug targets mitigating vascular dysfunction, thrombo-inflammation and thromboembolic complications in COVID-19 is essential. COVID-19 coagulopathy differs from sepsis coagulopathy. Factors that drive severe lung pathology and coagulation abnormalities in COVID-19 are not understood. Protein-protein interaction studies indicate that the tagged viral bait protein ORF9c directly interacts with PAR2, which modulates host cell IFN and inflammatory cytokines. In addition to direct interaction of SARS-CoV-2 viral protein with PARs, we speculate that activation of PAR by proteases plays a role in COVID-19-induced hyperinflammation. In COVID-19-associated coagulopathy elevated levels of activated coagulation proteases may cleave PARs in association with TMPRSS2. PARs activation enhances the release of cytokines, chemokines and tissue factor expression to propagate IFN-dependent inflammation, leukocyte-endothelial interaction, vascular permeability and coagulation responses. This hypothesis, corroborated by in vitro findings and emerging clinical evidence, will focus targeted studies of PAR1/2 blockers as adjuvant drugs against cytokine release syndrome and COVID-19-associated coagulopathy.

Difference of coagulation features between severe pneumonia induced by SARS-CoV2 and non-SARS-CoV2

Severe coronavirus disease 2019 (COVID-19) is commonly complicated with coagulopathy, the difference of coagulation features between severe pneumonia induced by SARS-CoV2 and non-SARS-CoV2 has not been analyzed. Coagulation results and clinical features of consecutive patients with severe pneumonia induced by SARS-CoV2 (COVID group) and non-SARS-CoV2 (non-COVID group) in Tongji hospital were retrospectively analyzed and compared. Whether patients with elevated D-dimer could benefit from anticoagulant treatment was evaluated. There were 449 COVID patients and 104 non-COVID patients enrolled into the study. The 28-day mortality in COVID group was approximately twofold of mortality in non-COVID group (29.8% vs. 15.4%, P = 0.003), COVID group were older (65.1 ± 12.0 vs. 58.4 ± 18.0, years, P < 0.001) and with higher platelet count (215 ± 100 vs. 188 ± 98, ×10⁹/L, P = 0.015), comparing to non-COVID group. The 28-day mortality of heparin users were lower than nonusers In COVID group with D-dimer > 3.0 μg/mL (32.8% vs. 52.4%, P = 0.017). Patients with severe pneumonia induced by SARS-CoV2 had higher platelet count than those induced by non-SARS-CoV2, and only the former with markedly elevated D-dimer may benefit from anticoagulant treatment.

Tissue factor promotes airway pathological features through epithelial-mesenchymal transition of bronchial epithelial cells in mice with house dust mite-induced asthma

It has recently been shown that expression levels of tissue factor (TF) are high in the serum and peripheral blood mononuclear cells of patients with asthma. However, whether TF impacts airway inflammation and remodelling in asthma remains unknown. The aim of this study was to investigate the effect of TF in asthma airway inflammation and remodelling using a house dust mite (HDM)-induced chronic asthma model and human bronchial epithelial (16HBE) cells. A chronic asthma model was constructed in BALB/c mice by the intranasal instillation of HDM. Mice were treated with short hairpin TF (shTF), and airway inflammation and remodelling features of asthma and epithelial-mesenchymal transition (EMT) were assessed. 16HBE cells were induced by transforming growth factor-β1 (TGF-β1) and HDM in the presence or absence of shTF; then, EMT markers and invasion and migration ability were determined. TF expression increased in the lung tissue and 16HBE cells when exposed to HDM. TF downregulation in the lung significantly reduced airway hyperresponsiveness, eosinophil inflammation, the EMT process, and levels of interleukin (IL)-4, IL-6, IL-13, and TGF-β1 in bronchoalveolar lavage fluid of asthmatic mice. Moreover, TF downregulation inhibited migration and incursion and decreased the expression levels of fibronectin 1 and TGF-β1, but increased the expression of E-cadherin in HDM- and TGF-β1-stimulated 16HBE cells. These results demonstrated that TF promoted airway pathological features by enhancing the EMT of bronchial epithelial cells both in vitro and in mice with house dust mite-induced asthma.

Pharmacological and clinical application of heparin progress: An essential drug for modern medicine

Heparin is the earliest and most widely used anticoagulant and antithrombotic drug that is still used in a variety of clinical indications. Since it was discovered in 1916, after more than a century of repeated exploration, heparin has not been replaced by other drugs, but a great progress has been made in its basic research and clinical application. Besides anticoagulant and antithrombotic effects, heparin also has antitumor, anti-inflammatory, antiviral, and other pharmacological activities. It is widely used clinically in cardiovascular and cerebrovascular diseases, lung diseases, kidney diseases, cancer, etc., as the first anticoagulant medicine in COVID-19 exerts anticoagulant, anti-inflammatory and antiviral effects. At the same time, however, it also leads to a lot of adverse reactions, such as bleeding, thrombocytopenia, elevated transaminase, allergic reactions, and others. This article comprehensively reviews the modern research progress of heparin compounds; discusses the structure, preparation, and adverse reactions of heparin; emphasizes the pharmacological activity and clinical application of heparin; reveals the possible mechanism of the therapeutic effect of heparin in related clinical applications; provides evidence support for the clinical application of heparin; and hints on the significance of exploring the wider application fields of heparin.

Coagulopathy in COVID-19

Hemostatic derangement is a hallmark in severe COVID-19. Markedly elevation of D-dimer and fibrinogen degradation product levels were observed in patients with severe COVID-19 higher and 71.4% of nonsurvivors met the International Society of Thrombosis and Haemostasis criteria of disseminated intravascular coagulation (DIC). Although the clinical and epidemiological features of COVID-19 have been well-described, the underlying mechanism influencing disease severity remains to be elucidated. Herein, the aim of this review article is to evaluate hemostasis in the pathogenesis of COVID-19 and its role in the management of this unprecedented pandemic.

Establishing Classifiers With Clinical Laboratory Indicators to Distinguish COVID-19 From Community-Acquired Pneumonia: Retrospective Cohort Study

Background

The initial symptoms of patients with COVID-19 are very much like those of patients with community-acquired pneumonia (CAP); it is difficult to distinguish COVID-19 from CAP with clinical symptoms and imaging examination.

Objective

The objective of our study was to construct an effective model for the early identification of COVID-19 that would also distinguish it from CAP.

Methods

The clinical laboratory indicators (CLIs) of 61 COVID-19 patients and 60 CAP patients were analyzed retrospectively. Random combinations of various CLIs (ie, CLI combinations) were utilized to establish COVID-19 versus CAP classifiers with machine learning algorithms, including random forest classifier (RFC), logistic regression classifier, and gradient boosting classifier (GBC). The performance of the classifiers was assessed by calculating the area under the receiver operating characteristic curve (AUROC) and recall rate in COVID-19 prediction using the test data set.

Results

The classifiers that were constructed with three algorithms from 43 CLI combinations showed high performance (recall rate >0.9 and AUROC >0.85) in COVID-19 prediction for the test data set. Among the high-performance classifiers, several CLIs showed a high usage rate; these included procalcitonin (PCT), mean corpuscular hemoglobin concentration (MCHC), uric acid, albumin, albumin to globulin ratio (AGR), neutrophil count, red blood cell (RBC) count, monocyte count, basophil count, and white blood cell (WBC) count. They also had high feature importance except for basophil count. The feature combination (FC) of PCT, AGR, uric acid, WBC count, neutrophil count, basophil count, RBC count, and MCHC was the representative one among the nine FCs used to construct the classifiers with an AUROC equal to 1.0 when using the RFC or GBC algorithms. Replacing any CLI in these FCs would lead to a significant reduction in the performance of the classifiers that were built with them.

Conclusions

The classifiers constructed with only a few specific CLIs could efficiently distinguish COVID-19 from CAP, which could help clinicians perform early isolation and centralized management of COVID-19 patients.

Treatment of Diffuse Alveolar Hemorrhage: Controlling Inflammation and Obtaining Rapid and Effective Hemostasis

Diffuse alveolar hemorrhage (DAH) is a life-threatening pulmonary complication in patients with hematologic malignancies or systemic autoimmune disorders. Pathologic findings show pulmonary capillaritis, bland hemorrhage, diffuse alveolar damage, and hemosiderin-laden macrophages, but in the majority of cases, pathogenesis remains unclear. Despite the severity and high mortality, the current treatment options for DAH remain empirical. Systemic treatment to control inflammatory activity including high-dose corticosteroids, cyclophosphamide, and rituximab and supportive care have been applied, but largely unsuccessful in critical cases. Activated recombinant factor VII (FVIIa) can achieve rapid local hemostasis and has been administered either systemically or intrapulmonary for the treatment of DAH. However, there is no randomized controlled study to evaluate the efficacy and safety, and the use of FVIIa for DAH remains open to debate. This review discusses the pathogenesis, diverse etiologies causing DAH, diagnosis, and treatments focusing on hemostasis using FVIIa. In addition, the risks and benefits of the off-label use of FVIIa in pediatric patients will be discussed in detail.

Thrombosis and Haemostasis challenges in COVID-19 - Therapeutic perspectives of heparin and tissue-type plasminogen activator and potential toxicological reactions-a mini review

The coronavirus disease (COVID)-19 pandemic is a major challenge for the health systems worldwide. Acute respiratory distress syndrome (ARDS), is one of the most common complications of the COVID-19 infection. The activation of the coagulation system plays an important role in the pathogenesis of ARDS. The development of lung coagulopathy involves thrombin generation and fibrinolysis inhibition.

Unfractionated heparin and its recently introduced counterpart low molecular weight heparin (LMWH), are widely used anticoagulants with a variety of clinical indications allowing for limited and manageable physio-toxicologic side effects while the use of protamine sulfate, heparin's effective antidote, has made their use even safer. Tissue-type plasminogen activator (tPA) is approved as intravenous thrombolytic treatment. The present narrative review discusses the use of heparin and tPA in the treatment of COVID-19-induced ARDS and their related potential physio-toxicologic side effects. The article is a quick review of articles on anticoagulation in COVID infection and the potential toxicologic reactions associated with these drugs.

The HDL from septic-ARDS patients with composition changes exacerbates pulmonary endothelial dysfunction and acute lung injury induced by cecal ligation and puncture (CLP) in mice

Background

Septic-acute respiratory distress syndrome (ARDS), characterized by the acute lung injury (ALI) secondary to aberrant systemic inflammatory response, has high morbidity and mortality. Despite increased understanding of ALI pathogenesis, the therapies to prevent lung dysfunction underlying systemic inflammatory disorder remain elusive. The high density lipoprotein (HDL) has critical protective effects in sepsis and its dysfunction has a manifested contribution to septic organ failure. However, the adverse changes in HDL composition and function in septic-ARDS patients are large unknown.

Methods

To investigate HDL remodeling in septic-ARDS, we analyzed the changes of HDL composition from 40 patients with septic-ARDS (A-HDL) and 40 matched normal controls (N-HDL). To determine the deleterious functional remodeling of HDL, A-HDL or N-HDL was administrated to C57BL/6 and apoA-I knock-out (KO) mice after cecal ligation and puncture (CLP) procedure. Mouse lung microvascular endothelial cells (MLECs) were further treated by these HDLs to investigate whether the adverse effects of A-HDL were associated with endothelial dysfunction.

Results

Septic-ARDS patients showed significant changes of HDL composition, accompanied with significantly decreased HDL-C. We further indicated that A-HDL treatment aggravated CLP induced ALI. Intriguingly, these deleterious effects of A-HDL were associated with pulmonary endothelial dysfunction, rather than the increased plasma lipopolysaccharide (LPS). Further in vitro results demonstrated the direct effects of A-HDL on MLECs, including increased endothelial permeability, enhanced expressions of adhesion proteins and pro-inflammatory cytokines via activating NF-κB signaling and decreased junction protein expression.

Conclusions

Our results depicted the remodeling of HDL composition in sepsis, which predisposes lung to ARDS via inducing ECs dysfunction. These results also demonstrated the importance of circulating HDL in regulating alveolar homeostasis.

Management of the thrombotic risk associated with COVID-19: guidance for the hemostasis laboratory

Coronavirus disease 2019 (COVID-19) is associated with extreme inflammatory response, disordered hemostasis and high thrombotic risk. A high incidence of thromboembolic events has been reported despite thromboprophylaxis, raising the question of a more effective anticoagulation. First-line hemostasis tests such as activated partial thromboplastin time, prothrombin time, fibrinogen and D-dimers are proposed for assessing thrombotic risk and monitoring hemostasis, but are vulnerable to many drawbacks affecting their reliability and clinical relevance. Specialized hemostasis-related tests (soluble fibrin complexes, tests assessing fibrinolytic capacity, viscoelastic tests, thrombin generation) may have an interest to assess the thrombotic risk associated with COVID-19. Another challenge for the hemostasis laboratory is the monitoring of heparin treatment, especially unfractionated heparin in the setting of an extreme inflammatory response. This review aimed at evaluating the role of hemostasis tests in the management of COVID-19 and discussing their main limitations.

Coagulopathy and thromboembolic events in patients with SARS-CoV-2 infection: pathogenesis and management strategies

In October 2019, a viral infectious disease appeared in the city of Wuhan in China. A new betacoronavirus, SARS-CoV-2, has been recognized as the responsible pathogen in this infection. Although coronavirus disease is principally expressed as a pulmonary infection, critical SARS-CoV-2 infection is frequently complicated with coagulopathy, and thromboembolic events are recognizable in several patients. Dehydration, acute inflammatory condition, protracted immobilization during disease, existence of multiple cardiovascular risk factors such as diabetes, obesity or hypertension, previous coronary artery disease, ischemic stroke, peripheral artery disease are frequent comorbidities in SARS-CoV-2 hospitalized subjects, which possibly augment thrombo-embolic risk. However, other causal factors can still be identified such as unrestricted angiotensin II action, the use of immunoglobulins, an increased production of adhesion molecules able to induce vascular inflammation and endothelial activation, complement stimulation, excessive production of neutrophil extracellular traps (NETs), and increased platelet count. Low-molecular-weight heparin should be chosen as early treatment because of its anti-inflammatory action and its ability to antagonize histones and so defend the endothelium. However, several therapeutic possibilities have also been proposed such as fibrinolytic treatment, drugs that target NETs, and complement inhibition. Nevertheless, although the violence of the pandemic may suggest the use of heroic treatments to reduce the frightening mortality that accompanies SARS-CoV-2 infection, we believe that experimental treatments should only be used within approved and controlled protocols, the only ones that can provide useful and specify information on the validity of the treatments.

Matrix metalloproteinases activation in Toxocara canis induced pulmonary pathogenesis

BACKGROUND

Toxocara canis, a source of visceral larva migrans, causes toxocariasis and induces respiratory symptoms. The reasons by which the pulmonary pathological alteration in the lungs infected with T. canis remain unclear.

METHODS

The involvement of the pulmonary pathological alteration by histology, enzyme activity, and Western blot analysis in the lungs of BALB/c mice after the infection of 2000 embryonated eggs.

RESULTS

The pathological effects gradually increased after the infection culminated in severe leukocyte infiltration and hemorrhage from days 4-14 post-inoculation. Gelatin zymography using substrate showed that the relative activity of matrix metalloproteinase (MMP) -9 and MMP-2 significantly increased in T. canis-infected mice. Western blot analysis indicated that the MMPs protein level of fibronectin monomer significantly increased in T. canis-infected mice compared with that in uninfected control. T. canis larvae mainly initiated leukocyte infiltration and hemorrhage in the lungs.

CONCLUSION

These phenomena subsequently induced the activities of MMPs in parallel with the pathological changes in early stage pulmonary inflammation. In conclusion, T. canis larval migration activated the MMPs and caused pulmonary pathogenesis.

Fibrinolytic abnormalities in acute respiratory distress syndrome (ARDS) and versatility of thrombolytic drugs to treat COVID-19

The global pandemic of coronavirus disease 2019 (COVID-19) is associated with the development of acute respiratory distress syndrome (ARDS), which requires ventilation in critically ill patients. The pathophysiology of ARDS results from acute inflammation within the alveolar space and prevention of normal gas exchange. The increase in proinflammatory cytokines within the lung leads to recruitment of leukocytes, further propagating the local inflammatory response. A consistent finding in ARDS is the deposition of fibrin in the air spaces and lung parenchyma. COVID-19 patients show elevated D-dimers and fibrinogen. Fibrin deposits are found in the lungs of patients due to the dysregulation of the coagulation and fibrinolytic systems. Tissue factor (TF) is exposed on damaged alveolar endothelial cells and on the surface of leukocytes promoting fibrin deposition, while significantly elevated levels of plasminogen activator inhibitor 1 (PAI-1) from lung epithelium and endothelial cells create a hypofibrinolytic state. Prophylaxis treatment of COVID-19 patients with low molecular weight heparin (LMWH) is important to limit coagulopathy. However, to degrade pre-existing fibrin in the lung it is essential to promote local fibrinolysis. In this review, we discuss the repurposing of fibrinolytic drugs, namely tissue-type plasminogen activator (tPA), to treat COVID-19 associated ARDS. tPA is an approved intravenous thrombolytic treatment, and the nebulizer form has been shown to be effective in plastic bronchitis and is currently in Phase II clinical trial. Nebulizer plasminogen activators may provide a targeted approach in COVID-19 patients to degrade fibrin and improving oxygenation in critically ill patients.

[The Agreed Experts' Position of the Eurasian Association of Therapists on Some new Mechanisms of COVID-19 Pathways: Focus on Hemostasis, Hemotransfusion Issues and Blood gas Exchange]

The article discusses pathogenesis and treatment of COVID-19. The authors presented state-of-the-art insight into hemostatic disorders in patients with COVID-19 and clinical recommendations on prevention of thrombosis and thromboembolism in patients infected with SARS-CoV-2. The article discussed in detail a new hypothesis proposed by Chinese physicians about a new component in the pathogenesis of COVID-19, namely, about the effect of SARS-CoV-2 virus on the hemoglobin beta-chain and the formation of a complex with porphyrin, which results in displacement of the iron ion. Thus, hemoglobin loses the capability for transporting oxygen, which aggravates hypoxia and worsens the prognosis. The article stated rules of hemotransfusion safety in the conditions of COVID-19 pandemic.

Fibrinolytic therapy for refractory COVID-19 acute respiratory distress syndrome: Scientific rationale and review

The coronavirus disease 2019 (COVID-19) pandemic has caused respiratory failure and associated mortality in numbers that have overwhelmed global health systems. Thrombotic coagulopathy is present in nearly three quarters of patients with COVID-19 admitted to the intensive care unit, and both the clinical picture and pathologic findings are consistent with microvascular occlusive phenomena being a major contributor to their unique form of respiratory failure. Numerous studies are ongoing focusing on anticytokine therapies, antibiotics, and antiviral agents, but none to date have focused on treating the underlying thrombotic coagulopathy in an effort to improve respiratory failure in COVID-19. There are animal data and a previous human trial demonstrating a survival advantage with fibrinolytic therapy to treat acute respiratory distress syndrome. Here, we review the extant and emerging literature on the relationship between thrombotic coagulopathy and pulmonary failure in the context of COVID-19 and present the scientific rationale for consideration of targeting the coagulation and fibrinolytic systems to improve pulmonary function in these patients.

Pneumococcal vaccination in adults at very high risk or with established cardiovascular disease: systematic review and meta-analysis

AIMS

There are several guidelines that recommend pneumococcal vaccination (PPSV23 and/or PCV13) in adults with a history of cardiovascular disease (established heart failure, coronary disease, and cerebrovascular disease) or at a very high risk of cardiovascular disease. However, there is no randomized controlled trial (RCT) systematic review that evaluates the impact of vaccination on all-cause mortality compared to no vaccination in this particular population. Our objective is to conduct a systematic review and meta-analysis of the impact of pneumococcal vaccination in the referred population.

METHODS AND RESULTS

We searched CENTRAL and MEDLINE for relevant RCTs and observational studies. Data were screened, extracted, and appraised by two independent reviewers. We pooled results using a random effects model, and used hazard ratios (HRs) with 95% confidence intervals (CIs) to assess measure of effect. The primary outcome was all-cause mortality and we assessed the confidence in the evidence using the GRADE framework. No RCTs were found. Seven observational studies were included for analyses. Pooled results from five studies enrolling a total of 163 756 participants showed a significant decrease in all-cause mortality (HR 0.78, 95% CI 0.73-0.83, very low confidence), without statistically significant heterogeneity (χ2 test P = 0.21; I2 = 32%).

CONCLUSIONS

Pneumococcal vaccination was associated with a 22% decrease of all-cause mortality in patients with cardiovascular disease or at a very high cardiovascular risk. However, limitations due to study design and the serious risk of bias in three of the included studies leads to a decreased level of result confidence.

Extracellular nucleic acid scavenging rescues rats from sulfur mustard analog-induced lung injury and mortality

Sulfur mustard (SM) is a highly toxic war chemical that causes significant morbidity and mortality and lacks any effective therapy. Rats exposed to aerosolized CEES (2-chloroethyl ethyl sulfide; 10% in ethanol), an analog of SM, developed acute respiratory distress syndrome (ARDS), which is characterized by increased inflammation, hypoxemia and impaired gas exchange. We observed elevated levels of extracellular nucleic acids (eNA) in the bronchoalveolar lavage fluid (BALF) of CEES-exposed animals. eNA can induce inflammation, coagulation and barrier dysfunction. Treatment with hexadimethrine bromide (HDMBr; 10 mg/kg), an eNA neutralizing agent, 2 h post-exposure, reduced lung injury, inhibited disruption of alveolar-capillary barrier, improved blood oxygenation (PaO₂/FiO₂ ratio), thus reversing ARDS symptoms. HDMBr treatment also reduced lung inflammation in the CEES-exposed animals by decreasing IL-6, IL-1A, CXCL-1 and CCL-2 mRNA levels in lung tissues and HMGB1 protein in BALF. Furthermore, HDMBr treatment also reduced levels of lung tissue factor and plasminogen activator inhibitor-1 indicating reduction in clot formation and increased fibrinolysis. Fibrin was reduced in BALF of the HDMBr-treated animals. This was further confirmed by histology that revealed diminished airway fibrin, epithelial sloughing and hyaline membrane in the lungs of HDMBr-treated animals. HDMBr completely rescued the CEES-associated mortality 12 h post-exposure when the survival rate in CEES-only group was just 50%. Experimental eNA treatment of cells caused increased inflammation that was reversed by HDMBr. These results demonstrate a role of eNA in the pathogenesis of CEES/SM-induced injury and that its neutralization can serve as a potential therapeutic approach in treating SM toxicity.

Knockdown of TFPI-Anchored Endothelial Cells Exacerbates Lipopolysaccharide-Induced Acute Lung Injury Via NF-κB Signaling Pathway

As activation of the coagulation system is both a consequence and contributor to acute lung injury (ALI), pulmonary coagulopathy has become a potential target for therapeutic intervention in ALI patients. We investigated the effects and possible mechanisms of endothelial cell (EC)-anchored tissue factor pathway inhibitor (TFPI) on lipopolysaccharide (LPS)-induced ALI in mice. To assess the effect of EC-anchored TFPI deletion on ALI indices, TFPI knockout (cKO) mice were generated. Mice were instilled by direct intratracheal injection LPS for the preparation of an ALI model. Evans blue dye (EBD) was injected intravenously 2 h prior to animal sacrifice (48 h post-LPS). Lungs were fixed for histopathology and the prepared tissue was homogenized or used to extract bronchoalveolar lavage fluid (BALF) or detect EBD concentration. TFPI knockdown mice with ALI were compared to wild-type (WT) mice with ALI to assess the effect of TFPI on endothelial barrier function and inflammation. TFPI deletion markedly exacerbated LPS histopathological changes in lung, and the LPS changes in protein, EBD extravasation, proinflammatory cytokines TNF-α, IL-1β, and IL-6 in BALF in lung. The number and infiltration of white blood cells (WBCs) from BALF and lung tissue of TFPI cKO mice with LPS-challenged ALI was increased compared to WT mice with LPS-challenged ALI. We also found further increased toll-like receptor 4 and nuclear factor kappa-light-chain-enhancer of activated B cells activation and additional expression of vascular cell adhesion molecule 1 and reduction of angiotensin converting enzyme 2 expression in TFPI cKO+LPS mice compared with WT+LPS mice. Endothelial-specific TFPI deficiency promoted LPS-induced pulmonary inflammation and endothelial barrier permeability possibly via toll-like receptor 4-mediated nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway activation.

Recombinant Human-Soluble Thrombomodulin Contributes to Reduced Mortality in Sepsis Patients With Severe Respiratory Failure: A Retrospective Observational Study Using a Multicenter Dataset

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Background:

Recombinant human-soluble thrombomodulin (rhTM) is a novel class therapeutic agent for managing disseminated intravascular coagulation. The progression of severe respiratory failure may be related to intra-alveolar coagulation/fibrinolytic disorders. We aimed to determine the efficacy of rhTM in treating sepsis patients with severe respiratory failure.

Methods:

We performed a retrospective observational study using an existing dataset collected from 42 intensive care units (ICUs) in Japan. Of 3,195 patients with severe sepsis or septic shock from the dataset, we selected sepsis patients with severe respiratory failure, and compared patient outcomes based on the administration of rhTM (rhTM group and no rhTM group). Propensity score analysis was performed between the two groups. Outcomes of interest were ICU mortality, hospital mortality, and ventilator-free days (VFDs).

Results:

In this study, 1,180 patients (rhTM, n = 356; no rhTM, n = 824) were analyzed. After adjusting for baseline imbalances with propensity score matching, the survival-time analysis revealed a significant difference between the two groups (hazard ratio, 0.654; 95% confidence interval, 0.439–0.974, P = 0.03). ICU mortality was lower in the rhTM group (rhTM: 22.1% [33/149] vs. no rhTM: 36.2% [54/149], P = 0.01). Hospital mortality was also lower in the rhTM group (35.6% [53/149] vs. 49.7% [74/149], P = 0.02). VFDs trended to be higher in the rhTM group than the no rhTM group (12.8 ± 10.1 days vs. 10.6 ± 10.6 days, P = 0.09).

Conclusions:

Administration of rhTM was positively correlated with a reduction in mortality in sepsis patients with severe respiratory failure.

Effects of nebulized antithrombin and heparin on inflammatory and coagulation alterations in an acute lung injury model in rats

BACKGROUND

During acute respiratory distress syndrome, proinflammatory mediators inhibit natural anticoagulant factors, which alter the normal balance between coagulation and fibrinolysis leading to a procoagulant state. We hypothesize that pulmonary administration of anticoagulants might be beneficial to treat acute respiratory distress syndrome for their anticoagulant and antiinflammatory effects and reduce the risk of systemic bleeding.

OBJECTIVES

Our aim is to study the effects of nebulized antithrombin (AT) and combined AT and heparin in an animal model of acute lung injury.

METHODS

Acute lung injury was induced in rats by the intratracheal administration of hydrochloric acid and lipopolysaccharide. AT alone (500 IU/kg body weight) or combined with heparin (1000 IU/kg body weight) were nebulized after the injury. Control groups received saline instead. Blood, lung tissue, bronchoalveolar lavage, and alveolar macrophages (AM) isolated from bronchoalveolar lavage were collected after 48 hours and analyzed.

RESULTS

Nebulized anticoagulant treatments reduced protein concentration in the lungs and decreased injury-mediated coagulation factors (tissue factor, plasminogen activator inhibitor-1, plasminogen, and fibrinogen degradation product) and inflammation (tumor necrosis factor α and interleukin 1β) in the alveolar space without affecting systemic coagulation and no bleeding. AT alone reduced fibrin deposition and edema in the lungs. Heparin did not potentiate AT coagulant effect but promoted the reduction of macrophages infiltration into the alveolar compartment. Anticoagulants reduced nuclear factor-kB downstream effectors in AM.

CONCLUSIONS

Nebulized AT and heparin attenuate lung injury through decreasing coagulation and inflammation without altering systemic coagulation and no bleeding. However, combined AT and heparin did not produce a synergistic effect.

Antithrombin plus alpha-1 protease inhibitor does not affect coagulation and inflammation in two murine models of acute lung injury

Background

In acute respiratory distress syndrome (ARDS), uncontrolled production of activators of coagulation and proinflammatory mediators results in a shift from an adequate local innate immune response to hypercoagulability and inflammation. This study aimed to investigate whether the protease inhibitors antithrombin (AT) and alpha-1 protease inhibitor (A1PI) may attenuate an exaggerated pulmonary immune response.

Methods

Lung injury was induced either by single intranasal administration of lipopolysaccharide (LPS) (5 mg/kg) in BALB/c mice or by combination of an intravenous injection of LPS (10 mg/kg) with subsequent injurious ventilation using high tidal volumes (12–15 ml/kg) for 4 h in RccHan Wistar rats. Animals received either a single bolus of AT (250 IU/kg) or A1PI (60 mg/kg) alone or in combination, with or without intravenous low-dose heparin (100 U/kg). Control animals received saline. Additional controls received neither LPS, nor ventilation, nor treatment. Endpoints were local and systemic markers of coagulation, e.g., thrombin–antithrombin complexes (TATc), and inflammation, e.g., interleukin-6.

Results

Both lung injury models resulted in a pronounced immune response within the pulmonary compartment shown by elevated levels of markers of coagulation and inflammation. The two-hit lung injury model also induced profound systemic coagulopathy and inflammation. Monotherapy with AT or A1PI did not reduce pulmonary coagulopathy or inflammation in any lung injury model. Nor did combination therapy with AT and A1PI result in a decrease of coagulation or inflammatory parameters. AT markedly reduced systemic levels of TATc in the two-hit lung injury model. Systemic inflammation was not affected by the different interventions. Additional administration of heparin did not lead to macroscopic bleeding incidences.

Conclusions

In two different murine models of acute lung injury, neither single therapy with AT or A1PI nor combination of both agents attenuates the pronounced pulmonary coagulation or inflammatory response.

Acute infection as a trigger for incident venous thromboembolism: Results from a population-based case-crossover study

BACKGROUND

A bidirectional relation exists between acute infection and immobilization, and both are triggers for venous thromboembolism (VTE). To what extent the association between infection and VTE-risk is explained by immobilization is unknown.

AIMS

To investigate the impact of hospitalization with acute infection on the VTE-risk in patients with and without concomitant immobilization, and to explore the differential impact of respiratory- (RTI) and urinary- (UTI) tract infections on the risk of deep vein thrombosis (DVT) and pulmonary embolism (PE).

METHODS

We conducted a case-crossover study of VTE-patients (n = 707) recruited from a general population. Hospitalizations and VTE-triggers were registered during the 90 days before a VTE (hazard period) and in four preceding 90-day control periods. Conditional logistic regression was used to estimate odds ratios (ORs) for VTE according to triggers.

RESULTS

Acute infection was registered in 267 (37.8%) of the hazard periods and in 107 (3.8%) of the control periods, corresponding to a high VTE-risk after infection (OR 24.2, 95% CI 17.2-34.0), that was attenuated to 15-fold increased after adjustment for immobilization. The risk was 20-fold increased after infection without concomitant immobilization, 73-fold increased after immobilization without infection, and 141-fold increased with the two combined. The risk of PE was apparently higher after RTIs (OR 48.3, 95% CI 19.4-120.0) than UTIs (OR 12.6, 95% CI 6.4-24.7), but diminished in sensitivity analyses excluding uncertain RTI diagnoses.

CONCLUSIONS

Our findings suggest that hospitalization with infection is a strong VTE-trigger also in non-immobilized patients. Infection and immobilization had a synergistic effect on the VTE-risk.

Coagulation factor XI improves host defence during murine pneumonia-derived sepsis independent of factor XII activation

Bacterial pneumonia, the most common cause of sepsis, is associated with activation of coagulation. Factor XI (FXI), the key component of the intrinsic pathway, can be activated via factor XII (FXII), part of the contact system, or via thrombin. To determine whether intrinsic coagulation is involved in host defence during pneumonia and whether this is dependent on FXII activation, we infected in parallel wild-type (WT), FXI knockout (KO) and FXII KO mice with two different clinically relevant pathogens, the Gram-positive bacterium Streptococcus pneumoniae and the Gram-negative bacterium Klebsiella pneumoniae, via the airways. FXI deficiency worsened survival and enhanced bacterial outgrowth in both pneumonia models. This was accompanied with enhanced inflammatory responses in FXI KO mice. FXII KO mice were comparable with WT mice in Streptococcus pneumoniae pneumonia. On the contrary, FXII deficiency improved survival and reduced bacterial outgrowth following infection with Klebsiella pneumoniae. In both pneumonia models, local coagulation was not impaired in either FXI KO or FXII KO mice. The capacity to phagocytose bacteria was impaired in FXI KO neutrophils and in human neutrophils where activation of FXI was inhibited. Deficiency for FXII or blocking activation of FXI via FXIIa had no effect on phagocytosis. Taken together, these data suggest that FXI protects against sepsis derived from Streptococcus pneumoniae or Klebsiella pneumoniae pneumonia at least in part by enhancing the phagocytic capacity of neutrophils by a mechanism that is independent of activation via FXIIa.

Rho-kinase inhibitor treatment prevents pulmonary inflammation and coagulation in lipopolysaccharide-induced lung injury

INTRODUCTION

In the pathogenesis of sepsis-induced acute lung injury (ALI), the crosstalk between inflammation and coagulation plays a pivotal role. The aim of this study was to investigate the role of Rho kinase (ROCK) inhibitor in alleviating pulmonary inflammation and coagulation in lipopolysaccharide (LPS)-induced acute lung injury (ALI) models.

METHODS

In the in vivo study, mice were randomized to four different groups: Control, Y-27632 (Y), LPS, and LPS+Y-27632 (LPS+Y). ALI was induced by intranasally administering LPS (10μg in 50μL PBS). Y-27632 (10mg/kg body weight,) was injected intraperitoneally at 18h and 1h before LPS challenge. Mice were euthanized at 3h or 8h post LPS challenge (N=8 per group). In the in vitro study, human pulmonary microvascular endothelial cells (HPMECs) were incubated with LPS alone (1μg/mL) or in combination with 10μM Y-27632 or 50μM BAY11-7082. Cells were pretreated with the inhibitors 30min before exposure to LPS. Three hours later, cells were isolated for subsequent analysis.

RESULTS

The myeloperoxidase (MPO) activity and fibrinogen deposits in the lung tissue significantly decreased and the lung damage in ALI mouse was attenuated. Pretreatment with Y-27632 markedly reduced the LPS-induced expression of interleukins 1β and 6, and the activation of nuclear factor (NF)-κB. Furthermore, ROCK inhibitor treatment antagonized the expression of tissue factor (TF) and plasminogen activator inhibitor (PAI)-1 in lung tissue and HPMECs.

CONCLUSIONS

ROCK inhibition protects against the endotoxin-induced pulmonary inflammation and coagulation via NF-kappaB pathway modulation.

Nebulized Recombinant Human Tissue Factor Pathway Inhibitor Attenuates Coagulation and Exerts Modest Anti-inflammatory Effects in Rat Models of Lung Injury

BACKGROUND

Critically ill patients are at a constant risk of direct (e.g., by pneumonia) or indirect lung injury (e.g., by sepsis). Excessive alveolar fibrin deposition is a prominent feature of lung injury, undermining pulmonary integrity and function.

METHODS

We examined the effect of local administration of recombinant human tissue factor pathway inhibitor (rh-TFPI), a natural anticoagulant, in two well-established models of lung injury in rats. Rats received intratracheal instillation of Pseudomonas aeruginosa, causing direct lung injury, or they received an intravenous injection of Escherichia coli lipopolysaccharide (LPS), causing indirect lung injury. Rats were randomized to local treatment with rh-TFPI or placebo through repeated nebulization.

RESULTS

Challenge with P. aeruginosa or LPS was associated with increased coagulation and decreased fibrinolysis in bronchoalveolar lavage fluid (BALF) and plasma. Rh-TFPI levels in BALF increased after nebulization, whereas plasma rh-TFPI levels remained low and systemic TFPI activity was not affected. Nebulization of rh-TFPI attenuated pulmonary and systemic coagulation in both models, without affecting fibrinolysis. Nebulization of rh-TFPI modestly reduced the inflammatory response and bacterial growth of P. aeruginosa in the alveolar compartment.

CONCLUSIONS

Local treatment with rh-TFPI does not alter systemic TFPI activity; however, it attenuates both pulmonary and systemic coagulopathy. Furthermore, nebulized rh-TFPI modestly reduces the pulmonary inflammatory response and allows increased bacterial clearance in rats with direct lung injury caused by P. aeruginosa.

Efficacy of azithromycin in sepsis-associated acute respiratory distress syndrome: a retrospective study and propensity score analysis

Purpose

Acute respiratory distress syndrome is a life-threatening form of respiratory failure without an established pharmacological treatment. Recently, macrolides have been found to be beneficial in cases of acute lung injury, but evidence is limited.

Materials and methods

This single-centre retrospective cohort evaluation of hospitalized patients with sepsis-associated acute respiratory distress syndrome aimed to assess the impact of azithromycin on clinical outcomes by using a propensity score analysis. All data were collected prospectively as part of ongoing research on high-resolution computed tomography of acute respiratory distress syndrome. The primary outcome was 60-day mortality; the secondary outcome was the number of ventilator-free days.

Results

Twenty-nine of 125 patients with sepsis-associated acute respiratory distress syndrome (23.2 %) received azithromycin within 24 h after acute respiratory distress syndrome diagnosis. After adjusting for potentially confounding covariates, azithromycin use was associated with lower 60-day mortality (hazard ratio, 0.31; 95 % confidence interval, 0.11–082; P = 0.02) and a shorter time to successful discontinuation of mechanical ventilation.

Conclusions

Azithromycin use was associated with decreased mortality and ventilator dependency in patients with sepsis-associated acute respiratory distress syndrome. Further well-designed prospective studies are needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-016-2866-1) contains supplementary material, which is available to authorized users.

Emerging targets for treating sulfur mustard-induced injuries

Sulfur mustard (SM; bis-(2-chlororethyl) sulfide) is a highly reactive, potent warfare agent that has recently reemerged as a major threat to military and civilians. Exposure to SM is often fatal, primarily due to pulmonary injuries and complications caused by its inhalation. Profound inflammation, hypercoagulation, and oxidative stress are the hallmarks that define SM-induced pulmonary toxicities. Despite advances, effective therapies are still limited. This current review focuses on inflammatory and coagulation pathways that influence the airway pathophysiology of SM poisoning and highlights the complexity of developing an effective therapeutic target.

α-Enolase Causes Proinflammatory Activation of Pulmonary Microvascular Endothelial Cells and Primes Neutrophils Through Plasmin Activation of Protease-Activated Receptor 2

Proinflammatory activation of vascular endothelium leading to increased surface expression of adhesion molecules and neutrophil (PMN) sequestration and subsequent activation is paramount in the development of acute lung injury and organ injury in injured patients. We hypothesize that α-enolase, which accumulates in injured patients, primes PMNs and causes proinflammatory activation of endothelial cells leading to PMN-mediated cytotoxicity.

METHODS

Proteomic analyses of field plasma samples from injured versus healthy patients were used for protein identification. Human pulmonary microvascular endothelial cells (HMVECs) were incubated with α-enolase or thrombin, and intercellular adhesion molecule-1 surface expression was measured by flow cytometry. A two-event in vitro model of PMN cytotoxicity HMVECs activated with α-enolase, thrombin, or buffer was used as targets for lysophosphatidylcholine-primed or buffer-treated PMNs. The PMN priming activity of α-enolase was completed, and lysates from both PMNs and HMVECs were immunoblotted for protease-activated receptor 1 (PAR-1) and PAR-2 and coprecipitation of α-enolase with PAR-2 and plasminogen/plasmin.

RESULTS

α-Enolase increased 10.8-fold in injured patients (P < 0.05). Thrombin and α-enolase significantly increased intercellular adhesion molecule-1 surface expression on HMVECs, which was inhibited by antiproteases, induced PMN adherence, and served as the first event in the two-event model of PMN cytotoxicity. α-Enolase coprecipitated with PAR-2 and plasminogen/plasmin on HMVECs and PMNs and induced PMN priming, which was inhibited by tranexamic acid, and enzymatic activity was not required.

CONCLUSIONS

α-Enolase increases after injury and may activate pulmonary endothelial cells and prime PMNs through plasmin activity and PAR-2 activation. Such proinflammatory endothelial activation may predispose to PMN-mediated organ injury.

Diffuse alveolar hemorrhage and recombinant factor VIIa treatment in pediatric patients

Diffuse alveolar hemorrhage (DAH) is a life-threatening pulmonary complication in patients with hematologic malignancies or autoimmune disorders. The current treatment options, which include corticosteroids, transfusions, extracorporeal membrane oxygenation (ECMO), and immunosuppressants, have been limited and largely unsuccessful. Recombinant activated factor VII (rFVIIa) has been successfully administered, either systemically or bronchoscopically, to adults for the treatment of DAH, but there are few data on its use in pediatric patients. The current literature in the PubMed database was reviewed to evaluate the efficacy and risk of rFVIIa treatment for DAH in pediatric patients. This review discusses the diagnosis and treatment of DAH, as well as a new treatment paradigm that includes rFVIIa. Additionally, the risks and benefits of off-label use of rFVIIa in pediatric patients are discussed.

Lung inhomogeneities, inflation and [18F]2-fluoro-2-deoxy-D-glucose uptake rate in acute respiratory distress syndrome

The aim of the study was to determine the size and location of homogeneous inflamed/noninflamed and inhomogeneous inflamed/noninflamed lung compartments and their association with acute respiratory distress syndrome (ARDS) severity.

In total, 20 ARDS patients underwent 5 and 45 cmH2O computed tomography (CT) scans to measure lung recruitability. [18F]2-fluoro-2-deoxy-d-glucose ([18F]FDG) uptake and lung inhomogeneities were quantified with a positron emission tomography-CT scan at 10 cmH2O. We defined four compartments with normal/abnormal [18F]FDG uptake and lung homogeneity.

The homogeneous compartment with normal [18F]FDG uptake was primarily composed of well-inflated tissue (80±16%), double-sized in nondependent lung (32±27% versus 16±17%, p<0.0001) and decreased in size from mild, moderate to severe ARDS (33±14%, 26±20% and 5±9% of the total lung volume, respectively, p=0.05). The homogeneous compartment with high [18F]FDG uptake was similarly distributed between the dependent and nondependent lung. The inhomogeneous compartment with normal [18F]FDG uptake represented 4% of the lung volume. The inhomogeneous compartment with high [18F]FDG uptake was preferentially located in the dependent lung (21±10% versus 12±10%, p<0.0001), mostly at the open/closed interfaces and related to recruitability (r2=0.53, p<0.001).

The homogeneous lung compartment with normal inflation and [18F]FDG uptake decreases with ARDS severity, while the inhomogeneous poorly/not inflated compartment increases. Most of the lung inhomogeneities are inflamed. A minor fraction of healthy tissue remains in severe ARDS.

Pathobiology of acute respiratory distress syndrome

The unique characteristics of pulmonary circulation and alveolar-epithelial capillary-endothelial barrier allow for maintenance of the air-filled, fluid-free status of the alveoli essential for facilitating gas exchange, maintaining alveolar stability, and defending the lung against inhaled pathogens. The hallmark of pathophysiology in acute respiratory distress syndrome is the loss of the alveolar capillary permeability barrier and the presence of protein-rich edema fluid in the alveoli. This alteration in permeability and accumulation of fluid in the alveoli accompanies damage to the lung epithelium and vascular endothelium along with dysregulated inflammation and inappropriate activity of leukocytes and platelets. In addition, there is uncontrolled activation of coagulation along with suppression of fibrinolysis and loss of surfactant. These pathophysiological changes result in the clinical manifestations of acute respiratory distress syndrome, which include hypoxemia, radiographic opacities, decreased functional residual capacity, increased physiologic deadspace, and decreased lung compliance. Resolution of acute respiratory distress syndrome involves the migration of cells to the site of injury and re-establishment of the epithelium and endothelium with or without the development of fibrosis. Most of the data related to acute respiratory distress syndrome, however, originate from studies in adults or in mature animals with very few studies performed in children or juvenile animals. The lack of studies in children is particularly problematic because the lungs and immune system are still developing during childhood and consequently the pathophysiology of pediatric acute respiratory distress syndrome may differ in significant ways from that seen in acute respiratory distress syndrome in adults. This article describes what is known of the pathophysiologic processes of pediatric acute respiratory distress syndrome as we know it today while also presenting the much greater body of evidence on these processes as elucidated by adult and animal studies. It is also our expressed intent to generate enthusiasm for larger and more in-depth investigations of the mechanisms of disease and repair specific to children in the years to come.