A review of pulmonary coagulopathy in acute lung injury, acute respiratory distress syndrome and pneumonia

COAGULOPATHY PARAMETERS PREDICTIVE OF OUTCOMES IN SEPSIS-INDUCED ACUTE RESPIRATORY DISTRESS SYNDROME: A SUBANALYSIS OF THE TWO PROSPECTIVE MULTICENTER COHORT STUDIES

ABSTRACT

Background: Although coagulopathy is often observed in acute respiratory distress syndrome (ARDS), its clinical impact remains poorly understood. Objectives: This study aimed to clarify the coagulopathy parameters that are clinically applicable for prognostication and to determine anticoagulant indications in sepsis-induced ARDS. Method: This study enrolled patients with sepsis-derived ARDS from two nationwide multicenter, prospective observational studies. We explored coagulopathy parameters that could predict outcomes in the Focused Outcome Research on Emergency Care for Acute Respiratory Distress Syndrome, Sepsis, and Trauma (FORECAST) cohort, and the defined coagulopathy criteria were validated in the Sepsis Prognostication in Intensive Care Unit and Emergency Room-Intensive Care Unit (SPICE-ICU) cohort. The correlation between anticoagulant use and outcomes was also evaluated. Results: A total of 181 patients with sepsis-derived ARDS in the FORECAST study and 61 patients in the SPICE-ICU study were included. In a preliminary study, we found the set of prothrombin time-international normalized ratio ≥1.4 and platelet count ≤12 × 10 4 /μL, and thrombocytopenia and elongated prothrombin time (TEP) coagulopathy as the best coagulopathy parameters and used it for further analysis; the odds ratio (OR) of TEP coagulopathy for in-hospital mortality adjusted for confounding was 3.84 (95% confidence interval [CI], 1.66-8.87; P = 0.005). In the validation cohort, the adjusted OR for in-hospital mortality was 32.99 (95% CI, 2.60-418.72; P = 0.002). Although patients without TEP coagulopathy showed significant improvements in oxygenation over the first 4 days, patients with TEP coagulopathy showed no significant improvement (ΔPaO 2 /FiO 2 ratio, 24 ± 20 vs. 90 ± 9; P = 0.026). Furthermore, anticoagulant use was significantly correlated with mortality and oxygenation recovery in patients with TEP coagulopathy but not in patients without TEP coagulopathy. Conclusion: Thrombocytopenia and elongated prothrombin time coagulopathy is closely associated with better outcomes and responses to anticoagulant therapy in sepsis-induced ARDS, and our coagulopathy criteria may be clinically useful.

Therapeutic potential of curcumin in ARDS and COVID-19

Curcumin is a safe, non-toxic, readily available and naturally occurring compound, an active constituent of Curcuma longa (turmeric). Curcumin could potentially treat diseases, but faces poor physicochemical and pharmacological characteristics. To overcome these limitations, we developed a stable, water-soluble formulation of curcumin called cyclodextrin-complexed curcumin (CDC). We have previously shown that direct delivery of CDC to the lung following lipopolysaccharides exposure reduces acute lung injury (ALI) and effectively reduces lung injury, inflammation and mortality in mice following Klebsiella pneumoniae. Recently, we found that administration of CDC led to a significant reduction in angiotensin-converting enzyme 2 and signal transducer and activator of transcription 3 expression in gene and protein levels following pneumonia, indicating its potential in treating coronavirus disease 2019 (COVID-19). In this review, we consider the clinical features of ALI and acute respiratory distress syndrome (ARDS) and the role of curcumin in modulating the pathogenesis of bacterial/viral-induced ARDS and COVID-19.

The favorable impacts of silibinin polyphenols as adjunctive therapy in reducing the complications of COVID-19: A review of research evidence and underlying mechanisms

The proceeding pandemic of coronavirus disease 2019 is the latest global challenge. Like most other infectious diseases, inflammation, oxidative stress, and immune system dysfunctions play a pivotal role in the pathogenesis of COVID-19. Furthermore, the quest of finding a potential pharmaceutical therapy for preventing and treating COVID-19 is still ongoing. Silymarin, a mixture of flavonolignans extracted from the milk thistle, has exhibited numerous therapeutic benefits. We reviewed the beneficial effects of silymarin on oxidative stress, inflammation, and the immune system, as primary factors involved in the pathogenesis of COVID-19. We searched PubMed/Medline, Web of Science, Scopus, and Science Direct databases up to April 2022 using the relevant keywords. In summary, the current review indicates that silymarin might exert therapeutic effects against COVID-19 by improving the antioxidant system, attenuating inflammatory response and respiratory distress, and enhancing immune system function. Silymarin can also bind to target proteins of SARS-CoV-2, including main protease, spike glycoprotein, and RNA-dependent RNA-polymerase, leading to the inhibition of viral replication. Although multiple lines of evidence suggest the possible promising impacts of silymarin in COVID-19, further clinical trials are encouraged.

Silymarin/curcumin loaded albumin nanoparticles coated by chitosan as muco-inhalable delivery system observing anti-inflammatory and anti COVID-19 characterizations in oleic acid triggered lung injury and in vitro COVID-19 experiment

Respiratory infected by COVID-19 represents a major global health problem at moment even after recovery from virus corona. Since, the lung lesions for infected patients are still sufferings from acute respiratory distress syndrome including alveolar septal edema, pneumonia, hyperplasia, and hyaline membranes Therefore, there is an urgent need to identify additional candidates having ability to overcome inflammatory process and can enhance efficacy in the treatment of COVID-19. The polypenolic extracts were integrated into moeties of bovine serum albumin (BSA) and then were coated by chitosan as a mucoadhesion polymer. The results of interleukin-6, and c-reactive protein showed significant reduction in group treated by Encap. SIL + CUR (64 ± 0.8 Pg/μL & 6 ± 0.5 μg/μL) compared to group treated by Cham. + CUR (102 ± 0.8 Pg/μL & 7 ± 0.5 μg/μL) respectively and free capsules (with no any drug inside) (148 ± 0.6 Pg/μL & 10 ± 0.6 μg/μL) respectively. Histopathology profile was improved completely. Additionally, encapsulating silymarin showed anti-viral activity in vitro COVID-19 experiment. It can be summarized that muco-inhalable delivery system (MIDS) loaded by silymarin can be used to overcome inflammation induced by oleic acid and to overcome COVID-19.

Mechanisms of Pulmonary Hypertension in Acute Respiratory Distress Syndrome (ARDS)

Background: Acute respiratory distress syndrome (ARDS) is a severe and often fatal disease. The causes that lead to ARDS are multiple and include inhalation of salt water, smoke particles, or as a result of damage caused by respiratory viruses. ARDS can also arise due to systemic complications such as blood transfusions, sepsis, or pancreatitis. Unfortunately, despite a high mortality rate of 40%, there are limited treatment options available for ARDS outside of last resort options such as mechanical ventilation and extracorporeal support strategies. Aim of review: A complication of ARDS is the development of pulmonary hypertension (PH); however, the mechanisms that lead to PH in ARDS are not fully understood. In this review, we summarize the known mechanisms that promote PH in ARDS. Key scientific concepts of review: (1) Provide an overview of acute respiratory distress syndrome; (2) delineate the mechanisms that contribute to the development of PH in ARDS; (3) address the implications of PH in the setting of coronavirus disease 2019 (COVID-19).

Aquaporin 4 Blockade Attenuates Acute Lung Injury Through Inhibition of Th17 Cell Proliferation in Mice

Acute lung injury (ALI) is a syndrome characterized by damage to the alveolar-capillary wall, pulmonary edema and recruitment of inflammatory cells. Previous studies have indicated that aquaporin 4 (AQP4) plays a key role in brain edema formation and resolution. However, the role of AQP4 in the development and progression of ALI is not clear and needs to be resolved. In our current study, mouse ALI was induced by intratracheal instillation of lipopolysaccharide (LPS) at a concentration of 30 mg/kg. For the inhibition of AQP4, 200 mg/kg of TGN-020 (Sigma, USA) was administered intraperitoneally every 6 h starting at 30 min before intratracheal instillation of LPS. The results of the present work indicate, for the first time, that mice treated with the AQP4 inhibitor TGN-020 had attenuated LPS-induced lung injury, reduced proinflammatory cytokine release (including IL-1α, IL-1β, IL-6, TNF-α, IL-23, and IL-17A), and an improved survival rate. Additionally, we found that the attenuated lung injury scores, increased survival rate, and decreased BALF total protein concentration in TGN-020-treated mice were all abrogated by rIL-17A administration. Furthermore, TGN-020 treatment downregulated the phosphorylation of PI3K and Akt, increased the expression of SOCS3, and decreased the expression of p-STAT3 and RORγt. In conclusion, inhibition of AQP4 by TGN-020 has a detectable protective effect against lung tissue injury induced by LPS, and this effect is associated with inhibition of IL-17A through the downregulation of the PI3K/Akt signaling pathway and upregulation of SOCS3 protein.

Biomarker profiles of coagulopathy and alveolar epithelial injury in acute respiratory distress syndrome with idiopathic/immune-related disease or common direct risk factors

BACKGROUND

Altered coagulation and alveolar injury are the hallmarks of acute respiratory distress syndrome (ARDS). However, whether the biomarkers that reflect pathophysiology differ depending on the etiology of ARDS has not been examined. This study aimed to investigate the biomarker profiles of coagulopathy and alveolar epithelial injury in two subtypes of ARDS: patients with direct common risk factors (dARDS) and those with idiopathic or immune-related diseases (iARDS), which are classified as "ARDS without common risk factors" based on the Berlin definition.

METHODS

This retrospective, observational study included adult patients who were admitted to the intensive care unit (ICU) at a university hospital with a diagnosis of ARDS with no indirect risk factors. Plasma biomarkers (thrombin-antithrombin complex [TAT], plasminogen activator inhibitor [PAI]-1, protein C [PC] activity, procalcitonin [PCT], surfactant protein [SP]-D, and KL-6) were routinely measured during the first 5 days of the patient's ICU stay.

RESULTS

Among 138 eligible patients with ARDS, 51 were excluded based on the exclusion criteria (n = 41) or other causes of ARDS (n = 10). Of the remaining 87 patients, 56 were identified as having dARDS and 31 as having iARDS. Among the iARDS patients, TAT (marker of thrombin generation) and PAI-1 (marker of inhibited fibrinolysis) were increased, and PC activity was above normal. In contrast, PC activity was significantly decreased, and TAT or PAI-1 was present at much higher levels in dARDS compared with iARDS patients. Significant differences were also observed in PCT, SP-D, and KL-6 between patients with dARDS and iARDS. The receiver operating characteristic (ROC) analysis showed that areas under the ROC curve for PC activity, PAI-1, PCT, SP-D, and KL-6 were similarly high for distinguishing between dARDS and iARDS (PC 0.86, P = 0.33; PAI-1 0.89, P = 0.95; PCT 0.89, P = 0.66; and SP-D 0.88, P = 0.16 vs. KL-6 0.90, respectively).

CONCLUSIONS

Coagulopathy and alveolar epithelial injury were observed in both patients with dARDS and with iARDS. However, their biomarker profiles were significantly different between the two groups. The different patterns of PAI-1, PC activity, SP-D, and KL-6 may help in differentiating between these ARDS subtypes.

Role of miR-214 in modulating proliferation and invasion of human colon cancer SW620 cells

This study investigated the role of miR-214 in modulating proliferation and invasion of human colon cancer SW620 cells. Fifty-five patients with colon cancer who were treated in China-Japan Union Hospital of Jilin University from March 2014 to March 2015 were enrolled into this study. Their cancer and corresponding paracancerous tissues were collected and the expression levels of miR-214 were determined by RT-qPCR. A miR-214 expression vector was constructed. SW620 cells were transfected with the miR-214 expression vector and a blank vector. Cells transfected with the miR-214 expression vector were assigned to the miR-214 positive group and cells transfected with the blank vector were assigned to the miR-214 negative group. Cell proliferation, invasion and apoptosis were assessed by MTT assay, Transwell migration assay and TUNEL apoptosis assay, respectively. The RT-qPCR results showed that the expression level of miR-214 in colon cancer tissue, as well as in miR-214 negative cells, was significantly lower than that in paracancerous tissue (P<0.05 for both). In cell comparison, the expression level of miR-214 in the miR-214 positive group was significantly higher than that in the miR-214 negative group (0.483±0.001 vs. 0.172±0.001; P<0.05). The proliferation level of SW620 cells in the miR-214 positive group was lower than that in the miR-214 negative group (P<0.05). The Transwell migration assay indicated that there were less cells penetrating the membrane in the miR-214 positive group than in the miR-214 negative group (P<0.05). In addition, The apoptosis rate of cells in the miR-214 negative group was significantly lower than that in the miR-214 positive group (P<0.05). Finally, the low expression of miR-214 was found in colon cancer, indicating that miR-214 is a cancer suppressor playing an opposing role in colon cancer onset and progression. Therefore, miR-214 can promote apoptosis of colon cancer cells SW620 by inhibiting their proliferation and invasion.

Nebulization of Single-Chain Tissue-Type and Single-Chain Urokinase Plasminogen Activator for Treatment of Inhalational Smoke-Induced Acute Lung Injury

Single-chain tissue-type plasminogen activator (sctPA) and single-chain urokinase plasminogen activator (scuPA) have attracted interest as enzymes for the treatment of inhalational smoke-induced acute lung injury (ISALI). In this study, the pulmonary delivery of commercial human sctPA and lyophilized scuPA and their reconstituted solution forms were demonstrated using vibrating mesh nebulizers (Aeroneb® Pro (active) and EZ Breathe® (passive)). Both the Aeroneb® Pro and EZ Breathe® vibrating mesh nebulizers produced atomized droplets of protein solution of similar size of less than about 5 μm, which is appropriate for pulmonary delivery. Enzymatic activities of scuPA and of sctPA were determined after nebulization and both remained stable (88.0% and 93.9%). Additionally, the enzymatic activities of sctPA and tcuPA were not significantly affected by excipients, lyophilization or reconstitution conditions. The results of these studies support further development of inhaled formulations of fibrinolysins for delivery to the lungs following smoke-induced acute pulmonary injury.

Anti-Semaphorin-7A single chain antibody demonstrates beneficial effects on pulmonary inflammation during acute lung injury

Pulmonary inflammation is a primary characteristic of lung injury initiated by the accession of immune cells into the alveolar space. Neutrophil migration serves an important role in pulmonary inflammation mediated by the migration of neutrophils into hypoxic tissue sites. The elimination of pulmonary inflammation is directly associated with rehabilitation in patients with lung injury. Anti-inflammatory treatment is essential following lung injury and ultimately determines patient outcomes. Semaphorin-7A (SEMA-7A) is a member of the Semaphorin family that influences the migration of neutrophils into hypoxic tissue sites, thus promoting inflammation. However, understanding of the role of SEMA-7A serves during lung injury is limited and the immunological function of SEMA-7A during the migration of neutrophils into acute injury sites remains unknown. The present study investigated SEMA-7A expression and constructed a single chain antibody for SEMA-7A (Anti-SEMA-7A) to study its therapeutic efficacy against pulmonary inflammation in a mouse model of acute injury sites. The data indicated that the expression of SEMA-7A was upregulated due to induction by pro-inflammatory cytokines and demonstrated that Anti-SEMA-7A inhibited SEMA-7A expression in vitro and in vivo. The current study also indicated that the production of pro-inflammatory cytokines induced by SEMA-7A in endothelial and epithelial cells enhanced pulmonary inflammation. Anti-SEMA-7A suppressed the transendothelial migration of neutrophils mediated by SEMA-7A. Anti-SEMA-7A treatment neutralized SEMA-7A expression and reduced signs of pulmonary inflammation, leading to the elimination of pulmonary inflammation in rat with acute lung injury. The current study identified Anti-SEMA-7A as a potential agent to interfere with the inflammatory pathway during acute lung injury, which may be the basis for anti-inflammatory strategies to treat lung injuries in the future.

Pulmonary endothelial activation caused by extracellular histones contributes to neutrophil activation in acute respiratory distress syndrome

BACKGROUND

During the acute respiratory distress syndrome (ARDS), neutrophils play a central role in the pathogenesis, and their activation requires interaction with the endothelium. Extracellular histones have been recognized as pivotal inflammatory mediators. This study was to investigate the role of pulmonary endothelial activation during the extracellular histone-induced inflammatory response in ARDS.

METHODS

ARDS was induced in male C57BL/6 mice by intravenous injection with lipopolysaccharide (LPS) or exogenous histones. Concurrent with LPS administration, anti-histone H4 antibody (anti-H4) or non-specific IgG was administered to study the role of extracellular histones. The circulating von Willebrand factor (vWF) and soluble thrombomodulin (sTM) were measured with ELISA kits at the preset time points. Myeloperoxidase (MPO) activity in lung tissue was measured with a MPO detection kit. The translocation of P-selectin and neutrophil infiltration were measured by immunohistochemical detection. For in vitro studies, histone H4 in the supernatant of mouse lung vascular endothelial cells (MLVECs) was measured by Western blot. The binding of extracellular histones with endothelial membrane was examined by confocal laser microscopy. Endothelial P-selectin translocation was measured by cell surface ELISA. Adhesion of neutrophils to MLVECs was assessed with a color video digital camera.

RESULTS

The results showed that during LPS-induced ARDS extracellular histones caused endothelial and neutrophil activation, as seen by P-selectin translocation, release of vWF, an increase of circulating sTM, lung neutrophil infiltration and increased MPO activity. Extracellular histones directly bound and activated MLVECs in a dose-dependent manner. On the contrary, the direct stimulatory effect of exogenous histones on neutrophils was very limited, as measured by neutrophil adhesion and MPO activity. With the contribution of activated endothelium, extracellular histones could effectively activating neutrophils. Both inhibiting the endothelial activation with an anti-toll like receptor (TLR) antibody and inhibiting the interaction of the endothelium with neutrophil using an anti-P-selectin antibody decreased the degree of neutrophil activation.

CONCLUSIONS

Extracellular histones are pro-inflammatory mediators in LPS-induced ARDS in mice. In addition to direct action to neutrophils, extracellular histones promote neutrophil adhesion and subsequent activation by first activating the pulmonary endothelium via TLR signaling. Thus, endothelial activation is important for extracellular histone-induced inflammatory injury.

Thymic Stromal Lymphopoietin Promotes Fibrosis and Activates Mitogen-Activated Protein Kinases in MRC-5 Cells

BACKGROUND Acute lung injury (ALI) is a life-threatening hypoxemic respiratory disorder with high incidence and mortality. ALI usually manifests as widespread inflammation and lung fibrosis with the accumulation of pro-inflammatory and pro-fibrotic factors and collagen. Thymic stromal lymphopoietin (TSLP) has a significant role in regulation of inflammation but little is known about its roles in lung fibrosis or ALI. This study aimed to define the role and possible regulatory mechanism of TSLP in lung fibrosis. MATERIAL AND METHODS We cultured human lung fibroblast MRC-5 cells and overexpressed or inhibited TSLP by the vector or small interfering RNA transfection. Then, the pro-fibrotic factors skeletal muscle actin alpha (α-SMA) and collagen I, and the 4 mitogen-activated protein kinases (MAPKs) - MAPK7, p38, extracellular signal-regulated kinase 1 (ERK1), and c-Jun N-terminal kinase 1 (JNK1) - were detected by Western blot. RESULTS Results showed that TSLP promoted the production of α-SMA and collagen I (P<0.001), suggesting that it can accelerate MRC-5 cell fibrosis. It also activated the expression of MAPK7, p-p38, p-ERK1, and p-JNK1, but the total MAPK7, p-38, ERK1, and JNK1 protein levels were mostly unchanged, indicating the activated MAPK pathways that might contribute to the promotion of cell fibrosis. CONCLUSIONS This study shows the pro-fibrotic role of TSLP in MRC-5 cells, suggesting TSLP is a potential therapeutic target for treating lung fibrosis in ALI. It possibly functions via activating MAPKs. These findings add to our understanding of the mechanism of fibrosis.

Possible mechanisms of Pseudomonas aeruginosa-associated lung disease

Pseudomonas aeruginosa is an opportunistic bacterium causing lung injury in immunocompromised patients correlated with high morbidity and mortality. Many bacteria, including P. aeruginosa, use extracellular signals to synchronize group behaviors, a process known as quorum sensing (QS). In the P. aeruginosa complex QS system controls expression of over 300 genes, including many involved in host colonization and disease. P. aeruginosa infection elicits a complex immune response due to a large number of immunogenic factors present in the bacteria or released during infection. Here, we focused on the mechanisms by which P. aeruginosa triggers lung injury and inflammation, debating the possible ways that P. aeruginosa evades the host immune system, which leads to immune suppression and resistance.

Acute Respiratory Distress Syndrome: Role of Oleic Acid-Triggered Lung Injury and Inflammation

Lung injury especially acute respiratory distress syndrome (ARDS) can be triggered by diverse stimuli, including fatty acids and microbes. ARDS affects thousands of people worldwide each year, presenting high mortality rate and having an economic impact. One of the hallmarks of lung injury is edema formation with alveoli flooding. Animal models are used to study lung injury. Oleic acid-induced lung injury is a widely used model resembling the human disease. The oleic acid has been linked to metabolic and inflammatory diseases; here we focus on lung injury. Firstly, we briefly discuss ARDS and secondly we address the mechanisms by which oleic acid triggers lung injury and inflammation.

Medium-chain Acyl-CoA dehydrogenase deficiency presenting with neonatal pulmonary haemorrhage

Background

Medium-chain Acyl-CoA dehydrogenase deficiency (MCADD) is the most common inherited disorder of fatty acid beta-oxidation. Signs and symptoms of MCADD typically appear during infancy or early childhood and include vomiting, lethargy, and hypoglycemia. Pulmonary haemorrhage has previously been described in patients with MCADD, but has always been considered a pre-terminal complication caused by heart failure.

Case presentation

We report on a newborn term infant that presented on the second day of life with signs of encephalopathy, followed by hypovolemia and respiratory distress caused by a severe pulmonary haemorrhage. Fluid resuscitation and mechanical ventilation were initiated and the coagulopathy was corrected by the administration of fresh frozen plasma. Echocardiography revealed a normal cardiac function. After 6 days of full intensive care, the patient survived without sequellae. The clinical presentation in absence of signs of infection raised a strong suspicion for a metabolic disorder and genetic testing revealed MCADD due to a homozygous A985G mutation.

Conclusion

The key towards successful management of severe pulmonary haemorrhage in newborns with a coagulopathy and suspicion of an underlying metabolic disorder consists of adequate mechanical ventilation and aggressive use of fresh frozen plasma, while treating the metabolic decompensation and initiating an early diagnostic work-up. MCADD can lead to acute decompensation and present with complications such as pulmonary haemorrhage independent of cardiac function. Hence, in the context of MCADD, pulmonary haemorrhage should not be considered a pre-terminal complication caused by heart failure, and rather than withdrawing care, intensive treatment must be initiated.

Oleic acid induces lung injury in mice through activation of the ERK pathway

Oleic acid (OA) can induce acute lung injury in experimental models. In the present work, we used intratracheal OA injection to show augmented oedema formation, cell migration and activation, lipid mediator, and cytokine productions in the bronchoalveolar fluids of Swiss Webster mice. We also demonstrated that OA-induced pulmonary injury is dependent on ERK1/2 activation, since U0126, an inhibitor of ERK1/2 phosphorylation, blocked neutrophil migration, oedema, and lipid body formation as well as IL-6, but not IL-1β production. Using a mice strain carrying a null mutation for the TLR4 receptor, we proved that increased inflammatory parameters after OA challenges were not due to the activation of the TLR4 receptor. With OA being a Na/K-ATPase inhibitor, we suggest the possible involvement of this enzyme as an OA target triggering lung inflammation.

Leptospira and inflammation

Leptospirosis is an important zoonosis and has a worldwide impact on public health. This paper will discuss both the role of immunogenic and pathogenic molecules during leptospirosis infection and possible new targets for immunotherapy against leptospira components. Leptospira, possess a wide variety of mechanisms that allow them to evade the host immune system and cause infection. Many molecules contribute to the ability of Leptospira to adhere, invade, and colonize. The recent sequencing of the Leptospira genome has increased our knowledge about this pathogen. Although the virulence factors, molecular targets, mechanisms of inflammation, and signaling pathways triggered by leptospiral antigens have been studied, some questions are still unanswered. Toll-like receptors (TLRs) are the primary sensors of invading pathogens. TLRs recognize conserved microbial pattern molecules and activate signaling pathways that are pivotal to innate and adaptive immune responses. Recently, a new molecular target has emerged—the Na/K-ATPase—which may contribute to inflammatory and metabolic alteration in this syndrome. Na/K-ATPase is a target for specific fatty acids of host origin and for bacterial components such as the glycolipoprotein fraction (GLP) that may lead to inflammasome activation. We propose that in addition to TLRs, Na/K-ATPase may play a role in the innate response to leptospirosis infection.

Enhanced thrombin generation and depressed anticoagulant function in children with pneumonia

AIMS

To clarify the status of the coagulation system in children with community-acquired pneumonia.

METHODS

Coagulation activation markers (prothrombin fragment F1 + 2, thrombin-antithrombin complexes, D-dimer), the natural anticoagulants (antithrombin, protein C and S) and tissue factor were measured in 28 consecutive children with pneumonia on admission to the hospital. Patients were divided into those with either bacterial-type pneumonia (at least two of the following three criteria: plasma C-reactive protein (CRP) >80 mg/L, white blood cell count >15 × 10(9) /L and alveolar infiltrates on the chest radiograph) or viral-type pneumonia.

RESULTS

The majority of the patients (79%) showed elevation of at least one of the three coagulation activation markers. Plasma CRP concentration correlated with F1 + 2 (R = 0.44, p < 0.05) and D-dimer (R = 0.71, p < 0.0001). Patients with bacterial-type pneumonia (n = 17) had higher D-dimer levels (p < 0.05) and lower levels of antithrombin (p = 0.005) and protein C (p = 0.08) than the patients with viral-type pneumonia.

CONCLUSIONS

Children with community-acquired bacterial-type pneumonia show distinctive changes in their coagulation system. The finding of coagulation system activation and depressed function of natural anticoagulants in uncomplicated pneumonia helps to understand the rapid and unpredictable changes observed in the coagulation status in patients with more severe forms of disease.

The role of purinergic signaling on deformation induced injury and repair responses of alveolar epithelial cells

Cell wounding is an important driver of the innate immune response of ventilator-injured lungs. We had previously shown that the majority of wounded alveolus resident cells repair and survive deformation induced insults. This is important insofar as wounded and repaired cells may contribute to injurious deformation responses commonly referred to as biotrauma. The central hypothesis of this communication states that extracellular adenosine-5′ triphosphate (ATP) promotes the repair of wounded alveolus resident cells by a P2Y2-Receptor dependent mechanism. Using primary type 1 alveolar epithelial rat cell models subjected to micropuncture injury and/or deforming stress we show that 1) stretch causes a dose dependent increase in cell injury and ATP media concentrations; 2) enzymatic depletion of extracellular ATP reduces the probability of stretch induced wound repair; 3) enriching extracellular ATP concentrations facilitates wound repair; 4) purinergic effects on cell repair are mediated by ATP and not by one of its metabolites; and 5) ATP mediated cell salvage depends at least in part on P2Y2-R activation. While rescuing cells from wounding induced death may seem appealing, it is possible that survivors of membrane wounding become governors of a sustained pro-inflammatory state and thereby perpetuate and worsen organ function in the early stages of lung injury syndromes. Means to uncouple P2Y2-R mediated cytoprotection from P2Y2-R mediated inflammation and to test the preclinical efficacy of such an undertaking deserve to be explored.

Lung endothelial barrier protection by iloprost in the 2-hit models of ventilator-induced lung injury (VILI) involves inhibition of Rho signaling

Mechanical ventilation at high tidal volume (HTV) may cause pulmonary capillary leakage and acute lung inflammation culminating in ventilator-induced lung injury. Iloprost is a stable, synthetic analog of prostaglandin I(2) used to treat pulmonary hypertension, which also showed endothelium-dependent antiedemagenic effects in the models of lung injury. To test the hypothesis that iloprost may attenuate lung inflammation and lung endothelial barrier disruption caused by pathologic lung distension and coagulation system component thrombin, we used cell and animal 2-hit models of ventilator-induced lung injury. Mice received a triple injection of iloprost (2 microg/kg, intravenous instillation) at 0, 40, and 80 min after the onset of HTV mechanical ventilation (30 mL/kg, 4h), combined with the administration of a thrombin receptor-activating peptide 6 (TRAP6, 3 x 10(-7)mol/mouse, intratracheal instillation). After 4h of ventilation, bronchoalveolar lavage (BAL), histologic analysis, and measurements of Evans blue accumulation in the lung tissue were performed. The effects of iloprost on endothelial barrier dysfunction were subsequently assessed in pulmonary endothelial cells (ECs) exposed to thrombin and pathologic (18%) cyclic stretch. The combination of HTV and TRAP6 enhanced the accumulation of neutrophils in BAL fluid and lung parenchyma, as well as increased the BAL protein content and endothelial permeability judged by Evans blue extravasation in the lung tissue. These effects were markedly attenuated by iloprost. The application of 18% cyclic stretch to pulmonary ECs enhanced the thrombin-induced EC paracellular gap formation and Rho-GTPase-mediated phosphorylation of regulatory myosin light chains and myosin phosphatase. Iloprost markedly inhibited the Rho-kinase-mediated site-specific phosphorylation of myosin phosphatase, and it prevented cyclic stretch- and thrombin-induced endothelial monolayer disruption. This study characterizes for the first time the protective effects of iloprost in the in vitro and in vivo 2-hit models of VILI and supports consideration of iloprost as a new therapeutic treatment of VILI.