The pulmonary physician in critical care * 6: The pathogenesis of ALI/ARDS

Reactive Oxygen Species and Strategies for Antioxidant Intervention in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening pulmonary condition characterized by the sudden onset of respiratory failure, pulmonary edema, dysfunction of endothelial and epithelial barriers, and the activation of inflammatory cascades. Despite the increasing number of deaths attributed to ARDS, a comprehensive therapeutic approach for managing patients with ARDS remains elusive. To elucidate the pathological mechanisms underlying ARDS, numerous studies have employed various preclinical models, often utilizing lipopolysaccharide as the ARDS inducer. Accumulating evidence emphasizes the pivotal role of reactive oxygen species (ROS) in the pathophysiology of ARDS. Both preclinical and clinical investigations have asserted the potential of antioxidants in ameliorating ARDS. This review focuses on various sources of ROS, including NADPH oxidase, uncoupled endothelial nitric oxide synthase, cytochrome P450, and xanthine oxidase, and provides a comprehensive overview of their roles in ARDS. Additionally, we discuss the potential of using antioxidants as a strategy for treating ARDS.

Synergistic Pulmonoprotective Effect of Natural Prolyl Oligopeptidase Inhibitors in In Vitro and In Vivo Models of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a highly morbid inflammatory lung disease with limited pharmacological interventions. The present study aims to evaluate and compare the potential pulmonoprotective effects of natural prolyl oligopeptidase (POP) inhibitors namely rosmarinic acid (RA), chicoric acid (CA), epigallocatechin-3-gallate (EGCG) and gallic acid (GA), against lipopolysaccharide (LPS)-induced ARDS. Cell viability and expression of pro-inflammatory mediators were measured in RAW264.7 cells and in primary murine lung epithelial and bone marrow cells. Nitric oxide (NO) production was also assessed in unstimulated and LPS-stimulated RAW264.7 cells. For subsequent in vivo experiments, the two natural products (NPs) with the most favorable effects, RA and GA, were selected. Protein, cell content and lipid peroxidation levels in bronchoalveolar lavage fluid (BALF), as well as histopathological changes and respiratory parameters were evaluated in LPS-challenged mice. Expression of key mediators involved in ARDS pathophysiology was detected by Western blotting. RA and GA favorably reduced gene expression of pro-inflammatory mediators in vitro, while GA decreased NO production in macrophages. In LPS-challenged mice, RA and GA co-administration improved respiratory parameters, reduced cell and protein content and malondialdehyde (MDA) levels in BALF, decreased vascular cell adhesion molecule-1 (VCAM-1) and the inducible nitric oxide synthase (iNOS) protein expression, activated anti-apoptotic mechanisms and down-regulated POP in the lung. Conclusively, these synergistic pulmonoprotective effects of RA and GA co-administration could render them a promising prophylactic/therapeutic pharmacological intervention against ARDS.

Nebulized Recombinant Tissue Plasminogen Activator (rt-PA) for Acute COVID-19-Induced Respiratory Failure: An Exploratory Proof-of-Concept Trial

Acute lung injury in COVID-19 results in diffuse alveolar damage with disruption of the alveolar-capillary barrier, coagulation activation, alveolar fibrin deposition and pulmonary capillary thrombi. Nebulized recombinant tissue plasminogen activator (rt-PA) has the potential to facilitate localized thrombolysis in the alveolar compartment and improve oxygenation. In this proof-of-concept safety study, adults with COVID-19-induced respiratory failure and a <300 mmHg PaO2/FiO2 (P/F) ratio requiring invasive mechanical ventilation (IMV) or non-invasive respiratory support (NIRS) received nebulized rt-PA in two cohorts (C1 and C2), alongside standard of care, between 23 April-30 July 2020 and 21 January-19 February 2021, respectively. Matched historical controls (MHC; n = 18) were used in C1 to explore efficacy. Safety co-primary endpoints were treatment-related bleeds and <1.0-1.5 g/L fibrinogen reduction. A variable dosing strategy with clinical efficacy endpoint and minimal safety concerns was determined in C1 for use in C2; patients were stratified by ventilation type to receive 40-60 mg rt-PA daily for ≤14 days. Nine patients in C1 (IMV, 6/9; NIRS, 3/9) and 26 in C2 (IMV, 12/26; NIRS, 14/26) received nebulized rt-PA for a mean (SD) of 6.7 (4.6) and 9.1(4.6) days, respectively. Four bleeds (one severe, three mild) in three patients were considered treatment related. There were no significant fibrinogen reductions. Greater improvements in mean P/F ratio from baseline to study end were observed in C1 compared with MHC (C1; 154 to 299 vs. MHC; 154 to 212). In C2, there was no difference in the baseline P/F ratio of NIRS and IMV patients. However, a larger improvement in the P/F ratio occurred in NIRS patients (NIRS; 126 to 240 vs. IMV; 120 to 188) and fewer treatment days were required (NIRS; 7.86 vs. IMV; 10.5). Nebulized rt-PA appears to be well-tolerated, with a trend towards improved oxygenation, particularly in the NIRS group. Randomized clinical trials are required to demonstrate the clinical effect significance and magnitude.

Single cell transcriptomics identifies distinct profiles in pediatric acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS), termed pediatric ARDS (pARDS) in children, is a severe form of acute respiratory failure (ARF). Pathologic immune responses are implicated in pARDS pathogenesis. Here, we present a description of microbial sequencing and single cell gene expression in tracheal aspirates (TAs) obtained longitudinally from infants with ARF. We show reduced interferon stimulated gene (ISG) expression, altered mononuclear phagocyte (MNP) transcriptional programs, and progressive airway neutrophilia associated with unique transcriptional profiles in patients with moderate to severe pARDS compared to those with no or mild pARDS. We additionally show that an innate immune cell product, Folate Receptor 3 (FOLR3), is enriched in moderate or severe pARDS. Our findings demonstrate distinct inflammatory responses in pARDS that are dependent upon etiology and severity and specifically implicate reduced ISG expression, altered macrophage repair-associated transcriptional programs, and accumulation of aged neutrophils in the pathogenesis of moderate to severe pARDS caused by RSV.

Right ventricular dysfunction in patients with acute respiratory distress syndrome receiving venovenous extracorporeal membrane oxygenation

Acute respiratory distress syndrome is characterized by non-cardiogenic pulmonary edema, decreased pulmonary compliance, and abnormalities in gas exchange, especially hypoxemia. Patients with acute respiratory distress syndrome (ARDS) who receive support with venovenous (V-V) extracorporeal membrane oxygenation (ECMO) usually have severe lung disease. Many patients with ARDS have associated pulmonary vascular injury which can result in elevated pulmonary vascular resistance and right heart dysfunction. Since V-V ECMO relies upon preserved cardiac function, right heart failure has important implications for patient evaluation, management, and outcomes. Worsening right heart function complicates ARDS and disease processes. Given the increasing use of ECMO to support patients with ARDS, an understanding of right ventricular-ECMO and cardiopulmonary interactions is essential for the clinician. A narrative review of the manifestations of right heart dysfunction, as well as diagnosis and management strategies for the patient with ARDS on ECMO, is provided.

SPP1 exacerbates ARDS via elevating Th17/Treg and M1/M2 ratios through suppression of ubiquitination-dependent HIF-1α degradation

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a severe inflammatory pulmonary condition that leads to respiratory failure. The imbalance of Th17/Treg and M1/M2 is implicated in ARDS. A better understanding of the regulation of the balance of Th17/Treg and M1/M2 may provide novel therapeutic targets for ARDS.

METHODS

Plasma and BALF samples were collected from ARDS patients. Inflammatory cytokines were examined by ELISA. Th17, Treg, M1 and M2 were identified via immunofluorescence staining of RORγt, Foxp3, iNOS and Arg-1. H&E and Masson's trichrome staining were applied for evaluating pulmonary damage and fibrosis. A mouse model of ARDS was established through LPS administration. HIF-1α was immunoprecipitated and subjected to ubiquitination analysis via western blotting. The expression of SPP1, VHL and HIF-1α was examined by RT-qPCR and western blotting.

RESULTS

ARDS patients showed elevated levels of inflammatory cytokines and ratios of Th17/Treg and M1/M2. SPP1 was upregulated in ARDS mice, and silencing of SPP1 alleviated lung injury and fibrosis. SPP1 inhibited VHL expression to reduce the ubiquitination and degradation of HIF-1α in ARDS. Overexpression of SPP1 facilitated Th17, Treg and M1 polarization but inhibited M2 polarization through upregulation of HIF-1α.

CONCLUSION

SPP1 elevates Th17/Treg and M1/M2 ratio by suppressing VHL expression and ubiquitination-dependent HIF-1α degradation, thus exacerbating ARDS. Our study provides novel mechanistic insights into ARDS pathogenesis and promising therapeutic targets.

Specific upregulation of extracellular miR-6238 in particulate matter-induced acute lung injury and its immunomodulation

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are life-threatening diseases characterized by a severe inflammatory response and the destruction of alveolar epithelium and endothelium. ALI/ARDS is caused by pathogens and toxic environmental stimuli, such as particulate matter (PM). However, the general symptoms of ALI/ARDS are similar, and determining the cause of lung injury is often challenging. In this study, we investigated whether there is a critical miRNA that characterizes PM-induced ALI. We found that the expression of miR-6238 is specifically upregulated in lung tissue and lung-derived extracellular vesicles (EVs) in response to PM exposure. Notably, bacterial endotoxin (Lipopolysaccharide; LPS or peptidoglycan; PTG) does not induce the expression of miR-6238 in the lung. Instead, the expression of miR-155 is dramatically increased in LPS-induced ALI. We further demonstrated that human lung epithelial cells and macrophages predominantly produce miR-6238 and miR-155, respectively. Mechanistically, EV-miR-6238 is effectively internalized into alveolar macrophages (AMs) and regulates inflammatory responses in vivo. CXCL3 is a main target of miR-6238 in AMs and modulates neutrophil infiltration into the lung alveoli. Collectively, our findings suggest that miR-6238 is a novel regulator of pulmonary inflammation and a putative biomarker that distinguishes PM-induced ALI from endotoxin (LPS/PTG)-mediated ALI.

Tumor Progression Locus 2 Protects against Acute Respiratory Distress Syndrome in Influenza A Virus-Infected Mice

Excessive inflammation in patients with severe influenza disease may lead to acute lung injury that results in acute respiratory distress syndrome (ARDS). ARDS is associated with alveolar damage and pulmonary edema that severely impair gas exchange, leading to hypoxia. With no existing FDA-approved treatment for ARDS, it is important to understand the factors that lead to virus-induced ARDS development to improve prevention, diagnosis, and treatment. We have previously shown that mice deficient in the serine-threonine mitogen-activated protein kinase, Tpl2 (MAP3K8 or COT), succumb to infection with a typically low-pathogenicity strain of influenza A virus (IAV; HKX31, H3N2 [x31]). The goal of the current study was to evaluate influenza A virus-infected Tpl2-/- mice clinically and histopathologically to gain insight into the disease mechanism. We hypothesized that Tpl2-/- mice succumb to IAV infection due to development of ARDS-like disease and pulmonary dysfunction. We observed prominent signs of alveolar septal necrosis, hyaline membranes, pleuritis, edema, and higher lactate dehydrogenase (LDH) levels in the lungs of IAV-infected Tpl2-/- mice compared to wild-type (WT) mice from 7 to 9 days postinfection (dpi). Notably, WT mice showed signs of regenerating epithelium, indicative of repair and recovery, that were reduced in Tpl2-/- mice. Furthermore, biomarkers associated with human ARDS cases were upregulated in Tpl2-/- mice at 7 dpi, demonstrating an ARDS-like phenotype in Tpl2-/- mice in response to IAV infection. IMPORTANCE This study demonstrates the protective role of the serine-threonine mitogen-activated protein kinase, Tpl2, in influenza virus pathogenesis and reveals that host Tpl2 deficiency is sufficient to convert a low-pathogenicity influenza A virus infection into severe influenza disease that resembles ARDS, both histopathologically and transcriptionally. The IAV-infected Tpl2-/- mouse thereby represents a novel murine model for studying ARDS-like disease that could improve our understanding of this aggressive disease and assist in the design of better diagnostics and treatments.

Role of metabolic reprogramming in pro-inflammatory cytokine secretion from LPS or silica-activated macrophages

In the lungs, macrophages constitute the first line of defense against pathogens and foreign bodies and play a fundamental role in maintaining tissue homeostasis. Activated macrophages show altered immunometabolism and metabolic changes governing immune effector mechanisms, such as cytokine secretion characterizing their classic (M1) or alternative (M2) activation. Lipopolysaccharide (LPS)-stimulated macrophages demonstrate enhanced glycolysis, blocked succinate dehydrogenase (SDH), and increased secretion of interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). Glycolysis suppression using 2 deoxyglucose in LPS-stimulated macrophages inhibits IL-1β secretion, but not TNF-α, indicating metabolic pathway specificity that determines cytokine production. In contrast to LPS, the nature of the immunometabolic responses induced by non-organic particles, such as silica, in macrophages, its contribution to cytokine specification, and disease pathogenesis are not well understood. Silica-stimulated macrophages activate pattern recognition receptors (PRRs) and NLRP3 inflammasome and release IL-1β, TNF-α, and interferons, which are the key mediators of silicosis pathogenesis. In contrast to bacteria, silica particles cannot be degraded, and the persistent macrophage activation results in an increased NADPH oxidase (Phox) activation and mitochondrial reactive oxygen species (ROS) production, ultimately leading to macrophage death and release of silica particles that perpetuate inflammation. In this manuscript, we reviewed the effects of silica on macrophage mitochondrial respiration and central carbon metabolism determining cytokine specification responsible for the sustained inflammatory responses in the lungs.

SRC3 deficiency exacerbates lipopolysaccharide-induced acute respiratory distress syndrome in mice

Acute respiratory distress syndrome (ARDS) is a severe disease. Inflammation is the key element implicated in ARDS. Steroid receptor coactivator 3 (SRC3), a coactivator protein for transcription, is involved in regulation of inflammatory response. Here we explored the potential roles of SRC3 in ARDS. We utilized the SRC3 deficient (SRC3^-/-) mice and established the lipopolysaccharides (LPS)-induced ARDS model. The mortality, lung injury, leucocytes infiltration and inflammatory cytokine production were compared between wild type (WT) and SRC3^-/- mice. The NF-κB activation in lung of WT and SRC3^-/- mice was measured. After LPS treatment, SRC3^-/- mice had higher mortality and more severe lung damage than WT mice. LPS-treated SRC3^-/- mice had more leucocytes infiltration and upregulated inflammatory cytokine production. LPS-treated SRC3^-/- mice had elevated NF-κB activation. SRC3^-/- mice had exacerbated ARDS in LPS-treated mice.

Natural therapeutics and nutraceuticals for lung diseases: Traditional significance, phytochemistry, and pharmacology

BACKGROUND

Lung diseases including chronic obstructive pulmonary disease (COPD), infections like influenza, acute respiratory distress syndrome (ARDS), asthma and pneumonia lung cancer (LC) are common causes of sickness and death worldwide due to their remoteness, cold and harsh climatic conditions, and inaccessible health care facilities.

PURPOSE

Many drugs have already been proposed for the treatment of lung diseases. Few of them are in clinical trials and have the potential to cure infectious diseases. Plant extracts or herbal products have been extensively used as Traditional Chinese Medicine (TCM) and Indian Ayurveda. Moreover, it has been involved in the inhibition of certain genes/protiens effects to promote regulation of signaling pathways. Natural remedies have been scientifically proven with remarkable bioactivities and are considered a cheap and safe source for lung disease.

METHODS

This comprehensive review highlighted the literature about traditional plants and their metabolites with their applications for the treatment of lung diseases through experimental models in humans. Natural drugs information and mode of mechanism have been studied through the literature retrieved by Google Scholar, ScienceDirect, SciFinder, Scopus and Medline PubMed resources against lung diseases.

RESULTS

In vitro, in vivo and computational studies have been explained for natural metabolites derived from plants (like flavonoids, alkaloids, and terpenoids) against different types of lung diseases. Probiotics have also been biologically active therapeutics against cancer, anti-inflammation, antiplatelet, antiviral, and antioxidants associated with lung diseases.

CONCLUSION

The results of the mentioned natural metabolites repurposed for different lung diseases especially for SARS-CoV-2 should be evaluated more by advance computational applications, experimental models in the biological system, also need to be validated by clinical trials so that we may be able to retrieve potential drugs for most challenging lung diseases especially SARS-CoV-2.

In vitro and vivo study of tranilast protects from acute respiratory distress syndrome and early pulmonary fibrosis induced by smoke inhalation

BACKGROUND

Tranilast (N-[3＇,4＇-dimethoxycinnamoyl]-anthranilic acid) is an analog of a tryptophan metabolite. It was identified with anti-inflammatory and antifibrotic activities, and used in the treatment of a variety of diseases, such as anti - allergy, bronchial asthma, and hypertrophic scars. As a drug with few adverse reactions, tranilast has attracted great attention, but its application is limited due to the uncertainty of dosages and mechanisms. In this study, the protection effects of different doses of tranilast on smoke inhalation mediated lung injury on rats, and on the damage of three kinds of lung cells in vitro were investigated.

METHOD

In vivo, Sprague-Dawley rats were randomly divided into sham group, smoke group (rats were exposed to pine sawdust smoke three times, each time for 5 min), different doses of tranilast treatment group (doses were 100 mg/kg, 200 mg/kg and 300 mg/kg, ip.) and placebo group. After 1, 3 and 7 days, pulmonary function, pathologic injury by HE staining, cytokines and oxidative stress level by kits were determined. At 7days, lung fibrosis was assessed by Masson's trichrome staining and the level of hydroxyproline (HYP). In vitro, three kinds of lung cells from normal rats were isolated: type II alveolar epithelial cells (AT-II), pulmonary microvascular endothelial cells (PMVECs) and pulmonary fibroblasts (PFs). To investigate the potential effects of tranilast on cell proliferation, cell cycle and cytokine production of three kinds of lung cells exposed to smoke.

RESULTS

Compared with smoke group and placebo group, tranilast treatment significantly reduced histopathological changes (such as pulmonary hemorrhage, edema and inflammatory cell infiltration, etc.), significantly reduced histopathological score (p < 0.05), increased arterial oxygen partial pressure, and decreased the levels of IL-1β, TNF-α, TGF-β1 (p < 0.05), oxidative stress and the expression of nuclear transcription factor κB (NF-κB) smoke exposed rats (p < 0.01). In particular, the effect of 200 mg/kg dose was more prominent. In vitro, smoke induced AT-II and PMVECs apoptosis, improved PFs proliferation (p < 0.01), activity of SOD and decreased the content of MDA (p < 0.01). However, tranilast seems to be turning this trend well. The inflammatory factor IL-11β, TNF-α and TGF-β1, and the expression of NF-κB were significantly lower in the tranilast treatment than in the smoke group (p < 0.01).

CONCLUSION

This study indicates that tranilast had a protective effect on acute respiratory distress syndrome and early pulmonary fibrosis of rats in vivo. In addition, tranilast promotes proliferation of AT-II and PMVECs but inhibits PFs proliferation, down-regulates secretion of inflammatory cytokines and alleviates oxidative stress of AT-II, PMVECs and PFs after smoke stimuli in vitro.

E-Cigarette (E-Cig) Liquid Composition and Operational Voltage Define the In Vitro Toxicity of Δ8Tetrahydrocannabinol/Vitamin E Acetate (Δ8THC/VEA) E-Cig Aerosols

The 2019 United States outbreak of E-cigarette (e-cig), or Vaping, Associated Acute Lung Injury (EVALI) has been linked to presence of vitamin E acetate (VEA) in Δ8tetrahydrocannabinol (Δ8THC)-containing e-liquids, as supported by VEA detection in patient biological samples. However, the pathogenesis of EVALI and the complex physicochemical properties of e-cig emissions remain unclear, raising concerns on health risks of vaping. This study investigates the effect of Δ8THC/VEA e-liquids and e-cig operational voltage on in vitro toxicity of e-cig aerosols. A novel E-cigExposure Generation System platform was used to generate and characterize e-cig aerosols from a panel of Δ8THC/VEA or nicotine-based e-liquids at 3.7 or 5 V. Human lung Calu-3 cells and THP-1 monocytes were exposed to cell culture media conditioned with collected e-cig aerosol condensate at doses of 85 and 257 puffs/m2 lung surface for 24 h, whereafter specific toxicological endpoints were assessed (including cytotoxicity, metabolic activity, reactive oxygen species generation, apoptosis, and inflammatory cytokines). Higher concentrations of gaseous volatile organic compounds were emitted from Δ8THC/VEA compared with nicotine-based e-liquids, especially at 5 V. Emitted PM2.5 concentrations in aerosol were higher for Δ8THC/VEA at 5 V and averagely for nicotine-based e-liquids at 3.7 V. Overall, aerosols from nicotine-based e-liquids showed higher bioactivity than Δ8THC/VEA aerosols in THP-1 cells, with no apparent differences in Calu-3 cells. Importantly, presence of VEA in Δ8THC and menthol flavoring in nicotine-based e-liquids increased cytotoxicity of aerosols across both cell lines, especially at 5 V. This study systematically investigates the physicochemical and toxicological properties of a model of Δ8THC/VEA and nicotine e-cigarette condensate exposure demonstrating that pyrolysis of these mixtures can generate hazardous toxicants whose synergistic actions potentially drive acute lung injury upon inhalation.

Stellate Ganglion Block Combined with Dexmedetomidine Protects Obese Rats from Lipopolysaccharide-Induced Acute Lung Injury

Objective

To investigate the effect and mechanism of combined stellate ganglion block (SGB) and dexmedetomidine (Dex) in obesity-related acute lung injury.

Methods

Thirty-six 4-week-old male Wistar rats were randomly divided into 6 groups, each with 6 rats: blank group (Control), high-fat diet group (HFD), high-fat + lipopolysaccharide (LPS)-induced acute lung injury group (HFD + LPS), SGB group, Dex group, and SGB + Dex group. H&E staining detected the pathological structure of rat lung tissue. TUNEL staining was used to examine cell apoptosis in lung tissue. Oxidative factors were accessed by biochemical reagents. ELISA was employed to measure the levels of TNF-α, IL-1β, and MCP1 in rat alveolar lavage fluid. Western blot detected the protein expression of glucose-regulated Protein 78 (GRP78), C/EBP homologous protein (CHOP), protein kinase R-like endoplasmic reticulum kinase (PERK), and p-PERK in lung tissue.

Results

The body weight of rats in the HFD group was higher than that in the control group. The use of SGB or Dex alone could significantly reduce the rate of pulmonary edema and lung cell apoptosis in HFD-induced obese rats and reduce MPO, TNF-α, IL-1β, and MCP1 levels, increasing the activity of SOD and GSH-Px. In addition, using SGB or Dex alone can also significantly reduce the protein expression levels of GRP78, CHOP, and p-PERK. The combined use of SGB and Dex can enhance the above effects.

Conclusion

The combined use of SGB and Dex can protect against obesity-related acute lung injury and is more effective than using SGB or Dex alone.

E-cigarette vaping associated acute lung injury (EVALI): state of science and future research needs

"E-Cigarette (e-cig) Vaping-Associated Acute Lung Injury" (EVALI) has been linked to vitamin-E-acetate (VEA) and Δ-9-tetrahydrocannabinol (THC), due to their presence in patients' e-cigs and biological samples. Lacking standardized methodologies for patients' data collection and comprehensive physicochemical/toxicological studies using real-world-vapor exposures, very little data are available, thus the underlying pathophysiological mechanism of EVALI is still unknown. This review aims to provide a comprehensive and critical appraisal of existing literature on clinical/epidemiological features and physicochemical-toxicological characterization of vaping emissions associated with EVALI. The literature review of 161 medical case reports revealed that the predominant demographic pattern was healthy white male, adolescent, or young adult, vaping illicit/informal THC-containing e-cigs. The main histopathologic pattern consisted of diffuse alveolar damage with bilateral ground-glass-opacities at chest radiograph/CT, and increased number of macrophages or neutrophils and foamy-macrophages in the bronchoalveolar lavage. The chemical analysis of THC/VEA e-cig vapors showed a chemical difference between THC/VEA and the single THC or VEA. The chemical characterization of vapors from counterfeit THC-based e-cigs or in-house-prepared e-liquids using either cannabidiol (CBD), VEA, or medium-chain triglycerides (MCT), identified many toxicants, such as carbonyls, volatile organic compounds, terpenes, silicon compounds, hydrocarbons, heavy metals, pesticides and various industrial/manufacturing/automotive-related chemicals. There is very scarce published toxicological data on emissions from THC/VEA e-liquids. However, CBD, MCT, and VEA emissions exert varying degrees of cytotoxicity, inflammation, and lung damage, depending on puffing topography and cell line. Major knowledge gaps were identified, including the need for more systematic-standardized epidemiological surveys, comprehensive physicochemical characterization of real-world e-cig emissions, and mechanistic studies linking emission properties to specific toxicological outcomes.

Pulmonary vascular inflammation with fatal coronavirus disease 2019 (COVID-19): possible role for the NLRP3 inflammasome

Background

Pulmonary hyperinflammation is a key event with SARS-CoV-2 infection. Acute respiratory distress syndrome (ARDS) that often accompanies COVID-19 appears to have worse outcomes than ARDS from other causes. To date, numerous lung histological studies in cases of COVID-19 have shown extensive inflammation and injury, but the extent to which these are a COVID-19 specific, or are an ARDS and/or mechanical ventilation (MV) related phenomenon is not clear. Furthermore, while lung hyperinflammation with ARDS (COVID-19 or from other causes) has been well studied, there is scarce documentation of vascular inflammation in COVID-19 lungs.

Methods

Lung sections from 8 COVID-19 affected and 11 non-COVID-19 subjects, of which 8 were acute respiratory disease syndrome (ARDS) affected (non-COVID-19 ARDS) and 3 were from subjects with non-respiratory diseases (non-COVID-19 non-ARDS) were H&E stained to ascertain histopathological features. Inflammation along the vessel wall was also monitored by expression of NLRP3 and caspase 1.

Results

In lungs from COVID-19 affected subjects, vascular changes in the form of microthrombi in small vessels, arterial thrombosis, and organization were extensive as compared to lungs from non-COVID-19 (i.e., non-COVID-19 ARDS and non-COVID-19 non-ARDS) affected subjects. The expression of NLRP3 pathway components was higher in lungs from COVID-19 ARDS subjects as compared to non-COVID-19 non-ARDS cases. No differences were observed between COVID-19 ARDS and non-COVID-19 ARDS lungs.

Conclusion

Vascular changes as well as NLRP3 inflammasome pathway activation were not different between COVID-19 and non-COVID-19 ARDS suggesting that these responses are not a COVID-19 specific phenomenon and are possibly more related to respiratory distress and associated strategies (such as MV) for treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01944-8.

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Inflammation plays an important role in the development of acute lung injury (ALI). Severe pulmonary inflammation can cause acute respiratory distress syndrome (ARDS) or even death. Expression of proinflammatory interleukin-‍1β (IL-‍1β) and inducible nitric oxide synthase (iNOS) in the process of pulmonary inflammation will further exacerbate the severity of ALI. The purpose of this study was to explore the effect of Palrnatine (Pa) on lipopolysaccharide (LPS)-induced mouse ALI and its underlying mechanism. Pa, a natural product, has a wide range of pharmacological activities with the potential to protect against lung injury. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) assays were performed to detect the expression and translation of inflammatory genes and proteins in vitro and in vivo. Immunoprecipitation was used to detect the degree of P65 translocation into the nucleus. We also used molecular modeling to further clarify the mechanism of action. The results showed that Pa pretreatment could significantly inhibit the expression and secretion of the inflammatory cytokine IL-1β, and significantly reduce the protein level of the proinflammatory protease iNOS, in both in vivo and in vitro models induced by LPS. Further mechanism studies showed that Pa could significantly inhibit the activation of the protein kinase B (Akt)/nuclear factor-κB (NF-κB) signaling pathway in the LPS-induced ALI mode and in LPS-induced RAW264.7 cells. Through molecular dynamics simulation, we observed that Pa was bound to the catalytic pocket of Akt and effectively inhibited the biological activity of Akt. These results indicated that Pa significantly relieves LPS-induced ALI by activating the Akt/NF-κB signaling pathway.

Role of lungs in the hemostasis system (review of literature)

The lung tissue contains various hemostatic system elements, which can be released from the lungs, both under physiological and pathological conditions. The COVID-19 pandemic has led to an increase in the number of patients with acute respiratory distress syndrome (ARDS) in intensive care units worldwide. When the lungs are damaged, coagulation disorders are mediated by tissue factor (TF) - factor VIIa (F VIIa), and inhibition of this pathway completely eliminates intrapulmonary fibrin deposition. A tissue factor pathway inhibitor TFPI also contributes to pulmonary coagulationdisturbance in ARDS. Pulmonary coagulationdisturbance caused by pneumonia can worsen the damage to the lungs and thus contribute to the progression of the disease. Cytokines are the main linking factors between inflammation and changes in blood clotting and fibrinolysis. The sources of proinflammatory cytokines in the lungs are probably alveolar macrophages. The activation of alveolar macrophages occurs through the nuclear factor kappa-bi (NF-κB), which controls thetranscription of the expression of immune response genes, cell apoptosis, which leads to the development of inflammation and autoimmune diseases as a result of direct stimulation of TF activation. Conversely,coagulation itself can affect bronchoalveolar inflammation. Coagulation leads to the formation of proteases that interact with specific cellular receptors, activating intracellular signaling pathways. The use of anticoagulant therapy, which also has an anti-inflammatory effect, perhaps one of the therapeutic targets for coronavirus infection.The difficulty here is that it seems appropriate to study anticoagulant interventions' influence on clinically significant cardio-respiratory parameters.

Atelectasis in primary graft dysfunction survivors after lung transplantation

BACKGROUND

Primary graft dysfunction (PGD) is an important contributor to early mortality in lung transplant recipients and is associated with impaired lung function. The radiographic sequelae of PGD on computed tomography (CT) have not been characterized.

METHODS

We studied adult double lung transplant recipients from 2010 to 2016 for whom protocol 3-month post-transplant CT scans were available. We assessed CTs for changes including pleural effusions, ground glass opacification, atelectasis, centrilobular nodularity, consolidation, interlobular septal thickening, air trapping and fibrosis, and their relationship to prior post-transplant PGD, future lung function, post-transplant baseline lung allograft dysfunction (BLAD), and chronic lung allograft dysfunction (CLAD).

RESULTS

Of 237 patients studied, 50 (21%) developed grade 3 PGD (PGD3) at 48 or 72 h. PGD3 was associated with increased interlobular septal thickening (p = .0389) and atelectasis (p = .0001) at 3 months, but only atelectasis remained associated after correction for multiple testing. Atelectasis severity was associated with lower peak forced expiratory volume in 1 s (FEV1) and increased risk of BLAD (p = .0014) but not with future CLAD onset (p = .7789).

CONCLUSIONS

Severe PGD was associated with atelectasis on 3-month post-transplant CT in our cohort. Atelectasis on routine CT may be an intermediary identifiable stage between PGD and future poor lung function.

Chrysin prevents lipopolysaccharide-induced acute lung injury in mice by suppressing the IRE1α/TXNIP/NLRP3 pathway

Acute lung injury (ALI) remains a serious challenge in the intensive care unit. Inflammation plays a key role in the progression of ALI. Chrysin (CHR) is a natural flavonoid with anti-inflammatory functions. We investigated the anti-inflammatory effects in a mouse model of ALI induced by lipopolysaccharide (LPS), and identified the underlying mechanisms of its action. Following CHR administration, mice were challenged with LPS intratracheally for 6 h to induce ALI. Compared to mice challenged with LPS alone, the presence of CHR showed a reduction in the development of lung injuries, as confirmed by histopathological observation. Pre-treatment with CHR attenuated inflammation by reducing the production of myeloperosidase (MPO), and pro-inflammatory cytokine levels in the lung and bronchoalveolar lavage fluid (BALF). Furthermore, CHR improved lung edema by reducing the vascular permeability, as demonstrated by less evans blue staining in the lung tissue and low levels of protein in BALF. In addition, our results proved that CHR improved the antioxidant capacity by increasing the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the lung tissue. Results of western blot assays suggested that CHR suppressed the LPS-induced expression of glucose-regulated protein 78 (GRP78) and phosphorylated inositol-requiring enzyme 1α (p-IRE1α). We also found that CHR suppressed the expression of thioredoxin interaction protein (TXNIP), nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) and cleaved caspase-1. In conclusion, CHR improved vascular permeability and mitigated the inflammatory response of lung tissue by suppressing the IRE1α/TXNIP/NLRP3 pathway, thereby alleviating LPS-induced ALI in the lungs of mice.

A Review of Acute Respiratory Distress Syndrome Management and Treatment

BACKGROUND

Acute respiratory distress syndrome (ARDS) was first described in 1967, but its definition has evolved considerably since then. ARDS is defined as the onset of hypoxemia, tachypnea, and loss of lung compliance due to some stimulus. In the United States, the incidence of ARDS has been growing because it is being increasingly recognized. The incidence of ARDS has also gone up recently due to the COVID-19 pandemic.

AREAS OF UNCERTAINTY

To date, there is no known one treatment for ARDS. Multiple studies have looked into various causes of ARDS, pathophysiology, and ventilation and management strategies. However, there is still considerable variability in the treatment and management of these patients from institution to institution.

DATA SOURCES

A literature search was conducted through PubMed and Google Scholar. Publications describing the epidemiology, diagnostic criteria, pathophysiology, and treatment were included in this review.

RESULTS

The definition of ARDS has evolved over the years. The most recent and agreed upon diagnostic criteria are based on the Berlin criteria for ARDS. Management of patients with ARDS includes low tidal volume ventilation, prone ventilation, paralysis in certain patient populations, and perhaps extracorporeal membrane oxygenation (ECMO). This also applies to patients with ARDS due to COVID-19.

CONCLUSIONS

Patients with ARDS have a high mortality due to the incredibly complex disease process. Because of the complexity of ARDS, the management and treatment is equally as difficult. This article reviews some of the strategies used to date, including the role of ECMO, and includes some society recommendations. Further research must be done into which methods best guide lung ventilation in severe ARDS and patients on ECMO.

Transcription factor-mediated signaling pathways' contribution to the pathology of acute lung injury and acute respiratory distress syndrome

The 2019 novel coronavirus (2019-nCoV) is still spreading rapidly around the world, and one cause of lethality for patients infected with 2019-nCoV is acute respiratory distress syndrome (ARDS). ARDS is a severe syndrome of acute lung injury (ALI) that is predominantly triggered by inflammation and results in a sudden loss of, or damage to, kidney function. Emerging studies reveal that multiple transcription factor-associated signaling pathways are activated in the pathology of ALI/ARDS. Of these pathways, the activation of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells), AP-1 (activator protein 1), IRFs (interferon regulatory factors), STATs (signal transducer and activator of transcription), Wnt/β-catenin-TCF/LEF (T-cell factor/lymphoid enhancer-binding factor), and CtBP2 (C-Terminal binding protein 2)-associated transcriptional complex contributes to ALI/ARDS pathology through diverse mechanisms, such as inducing proinflammatory cytokine levels and mediating macrophage polarization. In this review, we present an updated summary of the mechanisms underlying these signaling activations and regulations, as well as their contribution to the pathogenesis of ALI/ARDS. We aim to develop a better understanding of how ALI/ARDS occurs and improve ALI/ARDS therapy.

Lessons learned from the mechanisms of posttraumatic inflammation extrapolated to the inflammatory response in COVID-19: a review

Up to 20% of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) patients develop severe inflammatory complications with diffuse pulmonary inflammation, reflecting acute respiratory distress syndrome (ARDS). A similar clinical profile occurs in severe trauma cases. This review compares pathophysiological and therapeutic principles of severely injured trauma patients and severe coronavirus disease 2019 (COVID-19). The development of sequential organ failure in trauma parallels deterioration seen in severe COVID-19. Based on established pathophysiological models in the field of trauma, two complementary pathways of disease progression into severe COVID-19 have been identified. Furthermore, the transition from local contained disease into systemic and remote inflammation has been addressed. More specifically, the traumatology concept of sequential insults ('hits') resulting in immune dysregulation, is applied to COVID-19 disease progression modelling. Finally, similarities in post-insult humoral and cellular immune responses to severe trauma and severe COVID-19 are described. To minimize additional 'hits' to COVID-19 patients, we suggest postponing all elective surgery in endemic areas. Based on traumatology experience, we propose that immunoprotective protocols including lung protective ventilation, optimal thrombosis prophylaxis, secondary infection prevention and calculated antibiotic therapy are likely also beneficial in the treatment of SARS-CoV-2 infections. Finally, rising SARS-CoV-2 infection and mortality rates mandate exploration of out-of-the box treatment concepts, including experimental therapies designed for trauma care.

Thrombosis and coagulopathy in COVID-19: An illustrated review

This illustrated review discusses the haemostatic changes seen in patients with severe coronavirus disease 2019 (COVID-19) infection and their possible causes. We discuss the crosstalk between inflammation and coagulation resulting in high levels of acute-phase proteins, very high levels of D-dimers, and absence of disseminated intravascular coagulation seen in patients with severe COVID-19. There appear to be high rates of venous thromboembolism and also, what has been poorly described before in acute lung injury, a high rate of pulmonary immunothrombosis (thrombosis secondary to inflammation).

Pathological Findings of Postmortem Biopsies From Lung, Heart, and Liver of 7 Deceased COVID-19 Patients

Background. A novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been affecting almost all nations around the world. Most infected patients who have been admitted to intensive care units show SARS signs. In this study, we aimed to achieve a better understanding of pathological alterations that take place during the novel coronavirus infection in most presumed affected organs. Methods. We performed postmortem core needle biopsies from lung, heart, and liver on 7 deceased patients who had died of coronavirus disease 2019. Prepared tissue sections were observed by 2 expert pathologists. Results. Diffuse alveolar damage was the main pathologic finding in the lung tissue samples. Patients with hospitalization durations of more than 10 days showed evidence of organization. Multinucleated cells in alveolar spaces and alveolar walls, atypical enlarged cells, accumulation of macrophages in alveolar spaces, and congestion of vascular channels were the other histopathologic alteration of the lung. None of our heart biopsy samples met the criteria for myocarditis. Liver biopsies showed congestion, micro- and macro-vesicular changes, and minimal to mild portal inflammation, in the majority of cases. Conclusions. Similar to the previous coronavirus infection in 2003, the main pathologic finding in the lung was diffuse alveolar damage with a pattern of organization in prolonged cases. The SARS-CoV-2 infection does not cause myocarditis, and the ischemia of myocardium is the most probable justification of the observed pathologic changes in the heart. Liver tissue sections mostly showed nonspecific findings; however, ischemia of the liver can be identified in some cases.

Pretreatment with dexmedetomidine alleviates lung injury in a rat model of intestinal ischemia reperfusion

The aim of the present study was to investigate the antioxidant mechanisms of dexmedetomidine against lung injury during intestinal ischemia reperfusion (IIR) in rats. The model of IIR-induced acute lung injury was established by occluding the superior mesenteric artery (SMA) for 1 h and reperfusing for 2 h using Sprague-Dawley rats. Pathological examination was used to assess the extent of the lung injury. Oxidative stress was evaluated by measuring malondialdehyde, myeloperoxidase and superoxide dismutase in the lung and plasma. The proinflammatory cytokines tumor necrosis factor-α and interleukin-6 were determined via an enzyme-linked immunosorbent assay. The mRNA and protein expression of nuclear factor-erythroid 2 related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) were determined using a reverse transcription-quantitative polymerase chain reaction and western blotting. Pretreatment with dexmedetomidine significantly inhibited the oxidative stress response and proinflammatory factor release caused by IIR compared with the normal saline group (MDA and SOD in lung and plasma, P<0.05; MPO, IL-1β and TNF-α in lung and plasma, P<0.05). Dexmedetomidine improved pulmonary pathological changes in IIR rats compared with the normal saline group. Investigations into the molecular mechanism revealed that dexmedetomidine increased the expression levels of Nrf2 and HO-1 via activating α2 adrenergic receptors compared with the normal saline group. The antagonism of α2 adrenergic receptors may reverse the protective effect of dexmedetomidine on lung injury during IIR, including decreasing the expression levels of Nrf2 and HO-1, elevating the oxidative stress response and increasing the proinflammatory factor release. In conclusion, pretreatment with dexmedetomidine demonstrated protective effects against lung injury during IIR via α2 adrenergic receptors. The Nrf2/HO-1 signaling pathway may serve a function in the protective effect of dexmedetomidine.

Acute Respiratory Distress Syndrome in Cancer Patients

Acute respiratory distress syndrome (ARDS) is a heterogeneous form of acute, diffuse lung injury that is characterized by dysregulated inflammation, increased alveolar-capillary interface permeability, and non-cardiogenic pulmonary edema. In the general population, the incidence and mortality associated with ARDS over the last two decades have steadily declined in parallel with optimized approaches to pneumonia and other underlying causes of ARDS as well as increased utilization of multimodal treatment strategies that include lung-protective ventilation. In the cancer settings, significant declines in the incidence and mortality of ARDS over the past two decades have also been reported, although these rates remain significantly higher than those in the general population. Epidemiologic studies identify infection, including disseminated fungal pneumonias, as a major underlying cause of ARDS in the cancer setting. More than half of cancer patients who develop ARDS will not survive to hospital discharge. Those who do survive often face a protracted and often incomplete recovery, resulting in significant long-term physical, psychological, and cognitive sequelae. The residual organ dysfunction and poor functional status after ARDS may delay or preclude subsequent cancer treatments. As such, close collaboration between the critical care physicians and oncology team is essential in identifying and reversing the underlying causes and optimizing treatments for cancer patients with ARDS. This chapter reviews the diagnosis and common causes of ARDS in cancer and gives an update on the general management principles for cancer patients with ARDS in the ICU.

Vaping-associated acute respiratory distress syndrome

Vaping-associated lung injury via the use of electronic nicotine delivery systems (ENDS) is currently being evaluated as a potential source of pulmonary injury with uncertain etiology as the use of tetrahydrocannabinol (THC) is increasing throughout the USA. ENDS are marketed to be unlike traditional cigarette smoking in that they are purported to contain only propylene glycol, vegetable glycerine, nicotine, and flavorants compared with the > 60 carcinogenic ingredients in cigarettes. The New England Journal of Medicine (NEJM) currently reports four imaging patterns correlated with vaping-attributed pathology including acute eosinophilic pneumonia, diffuse alveolar damage, organizing pneumonia, and lipoid pneumonia. The incidence and extent of lung disease in otherwise young healthy patients with a history of vaping has not however been definitively recognized within the field of radiology. We present a case of vaping-associated acute respiratory distress syndrome (ARDS) in a young patient with no additional past medical history. The immediate radiologic recognition of vaping as a risk factor for ARDS in the emergency setting is pivotal so that appropriate medical management and respiratory support can be initiated without delay.

Microphysiological systems modeling acute respiratory distress syndrome that capture mechanical force-induced injury-inflammation-repair

Complex in vitro models of the tissue microenvironment, termed microphysiological systems, have enormous potential to transform the process of discovering drugs and disease mechanisms. Such a paradigm shift is urgently needed in acute respiratory distress syndrome (ARDS), an acute lung condition with no successful therapies and a 40% mortality rate. Here, we consider how microphysiological systems could improve understanding of biological mechanisms driving ARDS and ultimately improve the success of therapies in clinical trials. We first discuss how microphysiological systems could explain the biological mechanisms underlying the segregation of ARDS patients into two clinically distinct phenotypes. Then, we contend that ARDS-mimetic microphysiological systems should recapitulate three critical aspects of the distal airway microenvironment, namely, mechanical force, inflammation, and fibrosis, and we review models that incorporate each of these aspects. Finally, we recognize the substantial challenges associated with combining inflammation, fibrosis, and/or mechanical force in microphysiological systems. Nevertheless, complex in vitro models are a novel paradigm for studying ARDS, and they could ultimately improve patient care.

Cell therapy for ARDS: efficacy of endobronchial versus intravenous administration and biodistribution of MAPCs in a large animal model

Introduction

Bone marrow-derived multipotent adult progenitor cells (MAPCs) are adult allogeneic adherent stem cells currently investigated clinically for use in acute respiratory distress syndrome (ARDS). To date, there is no agreement on which is the best method for stem cells delivery in ARDS. Here, we compared the efficacy of two different methods of administration and biodistribution of MAPC for the treatment of ARDS in a sheep model.

Methods

MAPC were labelled with [¹⁸F] fluoro-29-deoxy-D-glucose and delivered by endobronchial (EB) or intravenous route 1 hour after lipopolysaccharide infusion in sheep mechanically ventilated. PET/CT images were acquired to determine the biodistribution and retention of the cells at 1 and 5 hours of administration.

Results

The distribution and retention of the MAPC was dependent on the method of cell administration. By EB route, PET images showed that MAPC remained at the site of administration and no changes were observed after 5 hours, whereas with intravenous route, the cells had broad biodistribution to different organs, being the lung the main organ of retention at 1 and 5 hours. MAPC demonstrated an equal effect on arterial oxygenation recovery by either route of administration.

Conclusion

The EB or intravenous routes of administration of MAPC are both effective for the treatment of ARDS in an acute sheep model, and the effect of MAPC therapy is not dependent of parenchymal integration or systemic biodistribution.

Cold-inducible RNA-binding protein-derived peptide C23 attenuates inflammation and tissue injury in a murine model of intestinal ischemia-reperfusion

BACKGROUND

Cold-inducible RNA-binding protein is a novel damage-associated molecular pattern that causes inflammation. C23, a short peptide derived from cold-inducible RNA-binding protein, has been found to have efficacy in blocking cold-inducible RNA-binding protein's activity. We hypothesized that C23 reduces inflammation and tissue injury induced by intestinal ischemia-reperfusion.

METHODS

Male C57BL/6 mice were subjected to 60 minutes of intestinal ischemia by clamping the superior mesenteric artery. Immediately after reperfusion, either normal saline (vehicle) or C23 peptide (8 mg/kg body weight) was injected intraperitoneally. Four hours after reperfusion, blood, intestinal, and lung tissues were collected for analysis of inflammatory and tissue injury parameters.

RESULTS

Cold-inducible RNA-binding protein levels in the intestinal tissues were significantly increased following intestinal ischemia-reperfusion. Histologic examination of the intestine revealed a significant reduction in injury score in the C23 group by 48% as compared with the vehicles after intestinal ischemia-reperfusion. The serum levels of lactate dehydrogenase and aspartate aminotransferase were increased in animals that underwent vehicle-treated intestinal ischemia-reperfusion, whereas C23-treated animals exhibited significant reductions by 48% and 53%, respectively. The serum and intestinal tissue levels of tumor necrosis factor α were elevated in vehicle-treated intestinal ischemia-reperfusion mice but decreased by 72% and 69%, respectively, in C23-treated mice. Interleukin-6 mRNA levels in the lungs were reduced by 86% in the C23-treated group in comparison to the vehicle-treated group after intestinal ischemia-reperfusion. Expression of macrophage inflammatory protein 2 and level of myeloperoxidase activity in the lungs were dramatically increased after intestinal ischemia-reperfusion and significantly reduced by 91% and 25%, respectively, in the C23-treated group.

CONCLUSION

C23 has potential to be developed into a possible therapy for reperfusion injury after mesenteric ischemia and reperfusion.

Knockdown of TNF‑α alleviates acute lung injury in rats with intestinal ischemia and reperfusion injury by upregulating IL‑10 expression

Intestinal ischemia and reperfusion (II/R) injury often triggers severe injury in remote organs, with the lungs being considered the main target. Excessive elevation of proinflammatory cytokines is a major contributor in the occurrence and development of II/R-induced acute lung injury (ALI). Therefore, the present study aimed to investigate whether blocking tumor necrosis factor-α (TNF-α) expression could protect the lungs from injury following II/R, and to explore the possible underlying mechanism involving interleukin-10 (IL-10). Briefly, II/R was induced in rats by 40 min occlusion of the superior mesenteric artery and celiac artery, followed by 8, 16 or 24 h of reperfusion. Subsequently, lentiviral vectors containing TNF-α short hairpin (sh)RNA were injected into the right lung tissues, in order to induce TNF-α knockdown. The severity of ALI was determined according to lung injury scores and lung edema (lung wet/dry weight ratio). The expression levels of TNF-α were analyzed by quantitative polymerase chain reaction (qPCR), western blotting and immunofluorescence (IF) staining. IL-10 expression, in response to TNF-α knockdown, was detected in lung tissues by qPCR and IF. The results detected marked inflammatory responses, and increased levels of lung wet/dry weight ratio and TNF-α expression, in the lungs of II/R rats. Conversely, treatment with TNF-α shRNA significantly alleviated the severity of ALI and upregulated the expression levels of IL-10 in lung tissues. These findings suggested that TNF-α RNA interference may exert a protective effect on II/R-induced ALI via the upregulation of IL-10. Therefore, TNF-α knockdown may be considered a potential strategy for the prevention or treatment of ALI induced by II/R in future clinical trials.

Right ventricular dysfunction during acute respiratory distress syndrome and veno-venous extracorporeal membrane oxygenation

Severe ARDS can be complicated by right ventricular (RV) failure. The etiology of RV failure in ARDS is multifactorial. Vascular alterations, hypoxia, hypercapnia and effects of mechanical ventilation may play a role. Echocardiography has an important role in diagnosing RV failure in ARDS patients. Once extracorporeal membrane oxygenation (ECMO) is indicated in these patients, the right ECMO modus needs to be chosen. In this review, the etiology, diagnosis and management of RV failure in ARDS will be briefly outlined. The beneficial effect of veno-venous (VV) ECMO on RV function in these patients will be illustrated. Based on this, we will give recommendations regarding choice of ECMO modus and provide an algorithm for management of RV failure in VV ECMO supported patients.

Acute Lung Injury

A wide variety of insults can produce acute lung damage, inclusive of those that injure the lungs directly. The clinical syndrome of acute onset respiratory distress, dyspnea, and bilateral infiltrates is referred to as acute respiratory distress syndrome. The histologic counterpart of acute respiratory distress syndrome is diffuse alveolar damage, classically characterized by hyaline membranes. Other histologic features of acute lung injury include intraalveolar fibrin, organization, interstitial edema, and reactive pneumocytes. Diffuse alveolar damage and other histologic features of acute lung injury are nonspecific as to etiology, and once identified require the pathologist to search the biopsy for further features that may help identify a specific etiology. This chapter reviews the temporal sequence of acute lung injury and explores the large variety of specific etiologic causes with emphasis on helpful histologic features to identify.

Candida albicans and Pseudomonas aeruginosa Interact To Enhance Virulence of Mucosal Infection in Transparent Zebrafish

Polymicrobial infections often include both fungi and bacteria and can complicate patient treatment and resolution of infection. Cross-kingdom interactions among bacteria, fungi, and/or the immune system during infection can enhance or block virulence mechanisms and influence disease progression. The fungus Candida albicans and the bacterium Pseudomonas aeruginosa are coisolated in the context of polymicrobial infection at a variety of sites throughout the body, including mucosal tissues such as the lung. In vitro, C. albicans and P. aeruginosa have a bidirectional and largely antagonistic relationship. Their interactions in vivo remain poorly understood, specifically regarding host responses in mediating infection. In this study, we examine trikingdom interactions using a transparent juvenile zebrafish to model mucosal lung infection and show that C. albicans and P. aeruginosa are synergistically virulent. We find that high C. albicans burden, fungal epithelial invasion, swimbladder edema, and epithelial extrusion events serve as predictive factors for mortality in our infection model. Longitudinal analyses of fungal, bacterial, and immune dynamics during coinfection suggest that enhanced morbidity is associated with exacerbated C. albicans pathogenesis and elevated inflammation. The P. aeruginosa quorum-sensing-deficient ΔlasR mutant also enhances C. albicans pathogenicity in coinfection and induces extrusion of the swimbladder. Together, these observations suggest that C. albicans-P. aeruginosa cross talk in vivo can benefit both organisms to the detriment of the host.

Lower airways inflammation in patients with ARDS measured using endotracheal aspirates: a pilot study

Introduction

Our knowledge of acute respiratory distress syndrome (ARDS) pathogenesis is incomplete. The goal of this pilot study is to investigate the feasibility of measuring lower airways inflammation in patients with ARDS using repeated endotracheal aspirates (ETAs).

Methods

ETAs were obtained within 24 hours by intensive care unit admission from 25 mechanically ventilated patients with ARDS and 10 of them underwent a second ETA within 96 hours after the first sampling. In each sample, cell viability was assessed using trypan blue exclusion method and the total and differential cell counts were measured using Neubauer-improved cell counting chamber and cytospins stained with Diff-Quik.

Results

The median cell viability was 89 (IQR 80–93)%, with a median total cell count of 305 (IQR 130–1270)×10³/mL and a median macrophage, neutrophil, lymphocyte and eosinophil count, respectively, of 19.8 (IQR 5.4–71.6)×10³/mL; 279 (IQR 109–1213)×10³/mL; 0 (IQR 0–0.188)×10³/mL; 0 (IQR 0–1.050)×10³/mL. Eosinophil count in the ETA correlated with the number of blood eosinophils (r=0.4840, p=0.0142). Cell viability and total and differential cell counts were neither significantly different in the second ETA compared with the first ETA nor were unaffected by the presence or absence of bacteria in the blood and/or ETA, or by the ARDS aetiology, apart from the macrophage count which was significantly increased in patients with ARDS associated with acute pancreatitis compared with those associated with pneumonia (p=0.0143).

Conclusions

ETA can be used to investigate the cellularity of the lower airways in patients with ARDS and it is an easy-to-perform and non-invasive procedure. Eosinophil counts in ETA and blood are significantly correlated. The number of macrophages in ETA may be affected by the aetiology of the ARDS.

Mitigation of sepsis-induced inflammatory responses and organ injury through targeting Wnt/β-catenin signaling

The Wnt/β-catenin pathway has been involved in regulating inflammation in various infectious and inflammatory diseases. Sepsis is a life-threatening condition caused by dysregulated inflammatory response to infection with no effective therapy available. Recently elevated Wnt/β-catenin signaling has been detected in sepsis. However, its contribution to sepsis-associated inflammatory response remains to be explored. In this study, we show that inhibition of Wnt/β-catenin signaling reduces inflammation and mitigates sepsis-induced organ injury. Using in vitro LPS-stimulated RAW264.7 macrophages, we demonstrate that a small-molecule inhibitor of β-catenin responsive transcription, iCRT3, significantly reduces the LPS-induced Wnt/β-catenin activity and also inhibits TNF-α production and IκB degradation in a dose-dependent manner. Intraperitoneal administration of iCRT3 to C57BL/6 mice, subjected to cecal ligation and puncture-induced sepsis, decreases the plasma levels of proinflammatory cytokines and organ injury markers in a dose-dependent manner. The histological integrity of the lungs is improved with iCRT3 treatment, along with reduced lung collagen deposition and apoptosis. In addition, iCRT3 treatment also decreases the expression of the cytokines, neutrophil chemoattractants, as well as the MPO activity in the lungs of septic mice. Based on these findings we conclude that targeting the Wnt/β-Catenin pathway may provide a potential therapeutic approach for treatment of sepsis.

Corticosteroids in ARDS: The Never-Ending Story

This feature examines the impact of pharmacologic interventions on the treatment of the critically ill patient — an area of health care that has become increasingly complex. Recent advances in drug therapy (including evolving and controversial data) for adult intensive-care-unit patients will be reviewed and assessed in terms of clinical, humanistic, and economic outcomes.

Lung surfactant metabolism: early in life, early in disease and target in cell therapy

Lung surfactant is a complex mixture of lipids and proteins lining the alveolar epithelium. At the air-liquid interface, surfactant lowers surface tension, avoiding alveolar collapse and reducing the work of breathing. The essential role of lung surfactant in breathing and therefore in life, is highlighted by surfactant deficiency in premature neonates, which causes neonatal respiratory distress syndrome and results in early death after birth. In addition, defects in surfactant metabolism alter lung homeostasis and lead to disease. Special attention should be paid to two important key cells responsible for surfactant metabolism: alveolar epithelial type II cells (AE2C) and alveolar macrophages (AM). On the one hand, surfactant deficiency coming from abnormal AE2C function results in high surface tension, promoting alveolar collapse and mechanical stress in the epithelium. This epithelial injury contributes to tissue remodeling and lung fibrosis. On the other hand, impaired surfactant catabolism by AM leads to accumulation of surfactant in air spaces and the associated altered lung function in pulmonary alveolar proteinosis (PAP). We review here two recent cell therapies that aim to recover the activity of AE2C or AM, respectively, therefore targeting the restoring of surfactant metabolism and lung homeostasis. Applied therapies successfully show either transplantation of healthy AE2C in fibrotic lungs, to replace injured AE2C cells and surfactant, or transplantation of bone marrow-derived macrophages to counteract accumulation of surfactant lipid and proteinaceous material in the alveolar spaces leading to PAP. These therapies introduce an alternative treatment with great potential for patients suffering from lung diseases.

Protective effect of suppressing STAT3 activity in LPS-induced acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are diseases with high mortality. Macrophages and neutrophils are responsible for inflammatory responses in ALI and ARDS, which are characterized by excessive production of proinflammatory mediators in bronchoalveolar lavage fluid (BALF) and plasma. Aberrant activation of the JAK/STAT pathway is critical for persistent inflammation in many conditions such as infection and autoimmunity. Given the importance of the STAT3 transcription factor in activating macrophages and neutrophils and augmenting inflammation, we investigated the therapeutic potential of inhibiting STAT3 activity using the small-molecule STAT3 inhibitor, LLL12. Our results demonstrate that LPS induces STAT3 activation in macrophages in vitro and in CD45⁺CD11b⁺ cells from BALF in the LPS-induced ALI model in vivo. LLL12 treatment inhibits LPS-induced lung inflammation in the ALI model, which is accompanied by suppression of LPS-induced STAT3 activation and an inhibition of macrophage and inflammatory cell infiltration in lung and BALF. LLL12 treatment also suppresses expression of proinflammatory genes including IL-1β, IL-6, TNF-α, iNOS, CCL2, and MHC class II in macrophages and inflammatory cells from BALF and serum as determined by ELISA. Furthermore, hyperactivation of STAT3 in LysMCre-SOCS3^fl/fl mice accelerates the severity of inflammation in the ALI model. Both pre- and post-LPS treatment with LLL12 decrease LPS-induced inflammatory responses in mice with ALI. Importantly, LLL12 treatment attenuates STAT3 phosphorylation in human peripheral blood mononuclear cells induced by plasma from patients with ARDS, which suggests the feasibility of targeting the STAT3 pathway therapeutically for patients with ALI and ARDS.

Trauma and acute lung injury

Acute lung injury is a serious complication of major trauma occurring as a direct consequence of trauma to the lung or, more commonly, arising indirectly as a consequence of trauma elsewhere to the body. A spectrum of severity exists with acute respiratory distress syndrome (ARDS) defined as the most severe form of injury. The frequency of ARDS with severe trauma is unclear but is believed to occur in approximately 15- 25% of cases, although this is confused by the effects of multiple transfusions and associated injuries including burns and head injury. ARDS from all causes is estimated to occur with a frequency of two to 10 cases per 100 000 population. It causes a huge social and financial impact, with many survivors requiring a prolonged critical care stay and a significant number having a persisting poor quality of life a year after the injury. The mortality is, however, decreasing and stands at approximately 40%. A number of approaches are now recognized that can improve oxygenation and large trials have identified best critical care practice, leading to a reduction in ventilator-induced injury, with associated improvements in outcome.

Evidences of Herbal Medicine-Derived Natural Products Effects in Inflammatory Lung Diseases

Pulmonary inflammation is a hallmark of many respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory syndrome distress (ARDS). Most of these diseases are treated with anti-inflammatory therapy in order to prevent or to reduce the pulmonary inflammation. Herbal medicine-derived natural products have been used in folk medicine and scientific studies to evaluate the value of these compounds have grown in recent years. Many substances derived from plants have the biological effects in vitro and in vivo, such as flavonoids, alkaloids, and terpenoids. Among the biological activities of natural products derived from plants can be pointed out the anti-inflammatory, antiviral, antiplatelet, antitumor anti-allergic activities, and antioxidant. Although many reports have evaluated the effects of these compounds in experimental models, studies evaluating clinical trials are scarce in the literature. This review aims to emphasize the effects of these different natural products in pulmonary diseases in experimental models and in humans and pointing out some possible mechanisms of action.

Pulmonary manifestations of malaria : recognition and management

Lung involvement in malaria has been recognized for more than 200 hundred years, yet our knowledge of its pathogenesis and management is limited. Pulmonary edema is the most severe form of lung involvement. Increased alveolar capillary permeability leading to intravascular fluid loss into the lungs is the main pathophysiologic mechanism. This defines malaria as another cause of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).Pulmonary edema has been described most often in non-immune individuals with Plasmodium falciparum infections as part of a severe systemic illness or as the main feature of acute malaria. P.vivax and P.ovale have also rarely caused pulmonary edema.Clinically, patients usually present with acute breathlessness that can rapidly progress to respiratory failure either at disease presentation or, interestingly, after treatment when clinical improvement is taking place and the parasitemia is falling. Pregnant women are particularly prone to developing pulmonary edema. Optimal management of malaria-induced ALI/ARDS includes early recognition and diagnosis. Malaria must always be suspected in a returning traveler or a visitor from a malaria-endemic country with an acute febrile illness. Slide microscopy and/or the use of rapid antigen tests are standard diagnostic tools. Malaria must be treated with effective drugs, but current choices are few: e.g. parenteral artemisinins, intravenous quinine or quinidine (in the US only). A recent trial in adults has shown that intravenous artesunate reduces severe malaria mortality by a third compared with adults treated with intravenous quinine. Respiratory compromise should be managed on its merits and may require mechanical ventilation.Patients should be managed in an intensive care unit and particular attention should be paid to the energetic management of other severe malaria complications, notably coma and acute renal failure. ALI/ARDS may also be related to a coincidental bacterial sepsis that may not be clinically obvious. Clinicians should employ a low threshold for starting broad spectrum antibacterials in such patients, after taking pertinent microbiologic specimens. Despite optimal management, the prognosis of severe malaria with ARDS is poor.ALI/ARDS in pediatric malaria appears to be rare. However, falciparum malaria with severe metabolic acidosis or acute pulmonary edema may present with a clinical picture of pneumonia, i.e. with tachypnea, intercostal recession, wheeze or inspiratory crepitations. This results in diagnostic confusion and suboptimal treatment. Whilst this is increasingly being recognized in malaria-endemic countries, clinicians in temperate zones should be aware that malaria may be a possible cause of 'pneumonia' in a visiting or returning child.

Increased Plasma Levels of Heparin-Binding Protein on Admission to Intensive Care Are Associated with Respiratory and Circulatory Failure

Purpose

Heparin-binding protein (HBP) is released by granulocytes and has been shown to increase vascular permeability in experimental investigations. Increased vascular permeability in the lungs can lead to fluid accumulation in alveoli and respiratory failure. A generalized increase in vascular permeability leads to loss of circulating blood volume and circulatory failure. We hypothesized that plasma concentrations of HBP on admission to the intensive care unit (ICU) would be associated with decreased oxygenation or circulatory failure.

Methods

This is a prospective, observational study in a mixed 8-bed ICU. We investigated concentrations of HBP in plasma at admission to the ICU from 278 patients. Simplified acute physiology score (SAPS) 3 was recorded on admission. Sequential organ failure assessment (SOFA) scores were recorded daily for three days.

Results

Median SAPS 3 was 58.8 (48–70) and 30-day mortality 64/278 (23%). There was an association between high plasma concentrations of HBP on admission with decreased oxygenation (p<0.001) as well as with circulatory failure (p<0.001), after 48–72 hours in the ICU. There was an association between concentrations of HBP on admission and 30-day mortality (p = 0.002). ROC curves showed areas under the curve of 0,62 for decreased oxygenation, 0,65 for circulatory failure and 0,64 for mortality.

Conclusions

A high concentration of HBP in plasma on admission to the ICU is associated with respiratory and circulatory failure later during the ICU care period. It is also associated with increased 30-day mortality. Despite being an interesting biomarker for the composite ICU population it´s predictive value at the individual patient level is low.

Tanshinone IIA therapeutically reduces LPS-induced acute lung injury by inhibiting inflammation and apoptosis in mice

AIM

To study the effects of tanshinone IIA (TIIA) on lipopolysaccharide (LPS)-induced acute lung injury in mice and the underlying mechanisms.

METHODS

Mice were injected with LPS (10 mg/kg, i.p.), then treated with TIIA (10 mg/kg, i.p.). Seven hours after LPS injection, the lungs were collected for histological study. Protein, LDH, TNF-α and IL-1β levels in bronchoalveolar lavage fluid (BALF) and myeloperoxidase (MPO) activity in lungs were measured. Cell apoptosis and Bcl-2, caspase-3, NF-κB and HIF-1α expression in lungs were assayed.

RESULTS

LPS caused marked histological changes in lungs, accompanied by significantly increased lung W/D ratio, protein content and LDH level in BALF, and Evans blue leakage. LPS markedly increased neutrophil infiltration in lungs and inflammatory cytokines in BALF. Furthermore, LPS induced cell apoptosis in lungs, as evidenced by increased TUNEL-positive cells, decreased Bcl-2 content and increased cleaved caspase-3 content. Moreover, LPS significantly increased the expression of NF-κB and HIF-1α in lungs. Treatment of LPS-injected mice with TIIA significantly alleviated these pathological changes in lungs.

CONCLUSION

TIIA alleviates LPS-induced acute lung injury in mice by suppressing inflammatory responses and apoptosis, which is mediated via inhibition of the NF-κB and HIF-1α pathways.

[Formula: see text]evidence of neuropsychological dysfunction in Stevens-Johnson Syndrome and toxic epidermal necrolysis: case report

Stevens-Johnson Syndrome (SJS) and toxic epidermal necrolysis (TEN) is a potentially life-threatening critical illness affecting multiple organ systems including the peripheral and central nervous system. This case report involves a young man who was diagnosed with SJS/TEN at age 16 and underwent neuropsychological assessment at age 21. Results indicate a diffuse pattern of cerebral compromise and represent a decline from premorbid level of functioning. The etiology of the cognitive impairment in this patient is likely multifactorial with possible pathophysiologic mechanisms including hypoxemia, metabolic acid-base perturbations, hyperglycemia, and delirium, as well as sepsis and inflammation.