Biomarkers in acute lung injury: insights into the pathogenesis of acute lung injury

Downregulation of miR-199a-3p mediated by the CtBP2-HDAC1-FOXP3 transcriptional complex contributes to acute lung injury by targeting NLRP1

Emerging evidence indicates that microRNAs (miRNAs) play fundamental roles in the pathogenesis of multiple diseases, including acute lung injury (ALI). Here, we discovered that miR-199a-3p was significantly downregulated in ALI lung tissues using a microarray analysis. In vitro lipopolysaccharide (LPS) treatment of the human epithelial cell line A549 and the human macrophage cell line U937 caused a decrease of miR-199a-3p. Mechanically, miR-199a-3p specifically bound to the 3'-untranslated region (3'-UTR) of NLRP1 (nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing protein 1), a critical member of inflammasomes. Ectopic overexpression or downregulation of miR-199a-3p resulted in the repression or induction of NLRP1, respectively, thereby downregulating or activating its downstream events. Moreover, transcription factor FOXP3 (forkhead box P3) was able to specifically bind to the promoter of miR-199a-3p. Knockdown or overexpression of FOXP3 resulted in a decrease or induction miR-199a-3p expression, respectively. Using immunoprecipitation (IP), mass spectrometry and co-IP assays, we found that FOXP3 formed a transcriptional complex with HDAC1 (histone deacetylase 1) and CtBP2 (C-terminal-binding protein 2). Collectively, our results suggested that the CtBP2-HDAC1-FOXP3 transcriptional complex (CHFTC) could specifically bind to the promoter of miR-199a-3p and repress its expression. Downregulation of miR-199a-3p eliminated its inhibition of NLRP1, causing activation of NLRP1 and cleavage of pro-IL-1β and pro-IL-18 mediated by Caspase-1. The secretion of IL-1β and IL-18 further aggravated the inflammatory response and resulted in the occurrence of ALI.

CXCR4 knockdown prevents inflammatory cytokine expression in macrophages by suppressing activation of MAPK and NF-κB signaling pathways

Background

Recent evidence has shown that C-X-C chemokine receptor type 4 (CXCR4) plays a crucial role in acute lung injury (ALI). Macrophages are key factors in the pathogenesis of ALI. The aim of this study was to investigate the role of CXCR4 in macrophages after lipopolysaccharide (LPS) stimulation and confirm that CXCR4 knockdown can inhibit inflammatory cytokines by suppressing mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathway activation.

Results

In this study, we found that CXCR4 expression in lung tissue of ALI was significantly increased using immunofluorescence. We also found that the expression of CXCR4 in macrophages sorted from bronchoalveolar lavage fluid (BALF) of ALI was obviously upregulated through RT-qPCR. After CXCR4 knockdown using siRNA, we found that the expression of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) was obviously down regulated in macrophages. Additionally, the phosphorylation of p38, Erk, and p65 was significantly decreased after CXCR4 knockdown through western blotting.

Conclusions

Taken together, the present study suggests that CXCR4 knockdown may inhibit inflammatory cytokine expression in macrophages by suppressing MAPK and NF-κB signaling pathway activation. Therefore, CXCR4 knockdown may have potential clinical value in treating ALI.

Anti-inflammatory Property of Imperatorin on Alveolar Macrophages and Inflammatory Lung Injury

Imperatorin is one of the furanocoumarin derivatives and exists in many medicinal herbs with anticancer, antiviral, antibacterial, and antihypertensive activities. In this study, we examined the anti-inflammatory effects of imperatorin on inflammation-associated lung diseases. Imperatorin reduced iNOS and COX-2 expression and also IL-6 and TNFα production enhanced by zymosan. Imperatorin also inhibited the signaling pathways of JAK/STAT and NF-κB. Moreover, in vivo study also revealed that zymosan-induced immune cell infiltration, pulmonary fibrosis, and edema were relieved by imperatorin in mice. We found that imperatorin exerts anti-inflammatory effects that are associated with amelioration of lung inflammation, edema, and rapid fibrosis. Studies on alveolar macrophages also reveal that imperatorin reduced the production of pro-inflammatory mediators and cytokines and inhibited pro-inflammatory JAK1/STAT3 and NF-κB signaling pathways. These results indicate that imperatorin may be a potential anti-inflammatory agent for inflammatory-associated lung diseases.

Glycyrrhizic acid ameliorates LPS-induced acute lung injury by regulating autophagy through the PI3K/AKT/mTOR pathway

Acute lung injury (ALI) is a major pathological issue characterized by serious inflammatory response, and a major clinically critical illness with high morbidity and mortality. Glycyrrhizic acid (GA) is a major bioactive constituent isolated from traditional Chinese herb licorice, which has been reported to have positive effects on inflammation. Nevertheless, the effects of GA on lipopolysaccharide (LPS)-treated ALI in mice have not been reported. The purpose of our study is to investigate the inhibitory effects of GA on ALI treated by LPS and to elucidate its possible mechanisms. We found that GA significantly attenuated lung injury and decreased the production of inflammatory factors TNF-α, IL-1β, and HMGB1 with LPS treatment. GA induced autophagy which was showed by enhanced number of autophagosomes through upregulating the protein levels of LC3-II/I and Beclin-1 and downregulating SQSTM1/P62. Moreover, pre-treatment of 3-Methyladenine (3-MA), an autophagy inhibitor, reversed the inhibiting effects of GA on the secretion of inflammatory factors in ALI. The PI3K/AKT/mTOR pathway was associated with GA-induced autophagy under ALI induced by LPS. In conclusion, this study indicated that GA inhibited the production of inflammatory factors in LPS-induced ALI by regulating the PI3K/AKT/mTOR pathway related autophagy, which may provide a novel therapeutic perspective of GA in ameliorating ALI.

Red Blood Cell Metabolic Responses to Torpor and Arousal in the Hibernator Arctic Ground Squirrel

Arctic ground squirrels provide a unique model to investigate metabolic responses to hibernation in mammals. During winter months these rodents are exposed to severe hypothermia, prolonged fasting, and hypoxemia. In the light of their role in oxygen transport/off-loading and owing to the absence of nuclei and organelles (and thus de novo protein synthesis capacity), mature red blood cells have evolved metabolic programs to counteract physiological or pathological hypoxemia. However, red blood cell metabolism in hibernation has not yet been investigated. Here we employed targeted and untargeted metabolomics approaches to investigate erythrocyte metabolism during entrance to torpor to arousal, with a high resolution of the intermediate time points. We report that torpor and arousal promote metabolism through glycolysis and pentose phosphate pathway, respectively, consistent with previous models of oxygen-dependent metabolic modulation in mature erythrocytes. Erythrocytes from hibernating squirrels showed up to 100-fold lower levels of biomarkers of reperfusion injury, such as the pro-inflammatory dicarboxylate succinate. Altered tryptophan metabolism during torpor was here correlated to the accumulation of potentially neurotoxic catabolites kynurenine, quinolinate, and picolinate. Arousal was accompanied by alterations of sulfur metabolism, including sudden spikes in a metabolite putatively identified as thiorphan (level 1 confidence)-a potent inhibitor of several metalloproteases that play a crucial role in nociception and inflammatory complication to reperfusion secondary to ischemia or hemorrhage. Preliminary studies in rats showed that intravenous injection of thiorphan prior to resuscitation mitigates metabolic and cytokine markers of reperfusion injury, etiological contributors to inflammatory complications after shock.

Nimbolide protects against endotoxin-induced acute respiratory distress syndrome by inhibiting TNF-α mediated NF-κB and HDAC-3 nuclear translocation

Acute respiratory distress syndrome (ARDS) is characterized by an excessive acute inflammatory response in lung parenchyma, which ultimately leads to refractory hypoxemia. One of the earliest abnormalities seen in lung injury is the elevated levels of inflammatory cytokines, among them, the soluble tumor necrosis factor (TNF-α) has a key role, which exerts cytotoxicity in epithelial and endothelial cells thus exacerbates edema. The bacterial lipopolysaccharide (LPS) was used both in vitro (RAW 264.7, THP-1, MLE-12, A549, and BEAS-2B) and in vivo (C57BL/6 mice), as it activates a plethora of overlapping inflammatory signaling pathways involved in ARDS. Nimbolide is a chemical constituent of Azadirachta indica, which contains multiple biological properties, while its role in ARDS is elusive. Herein, we have investigated the protective effects of nimbolide in abrogating the complications associated with ARDS. We showed that nimbolide markedly suppressed the nitrosative-oxidative stress, inflammatory cytokines, and chemokines expression by suppressing iNOS, myeloperoxidase, and nitrotyrosine expression. Moreover, nimbolide mitigated the migration of neutrophils and mast cells whilst normalizing the LPS-induced hypothermia. Also, nimbolide modulated the expression of epigenetic regulators with multiple HDAC inhibitory activity by suppressing the nuclear translocation of NF-κB and HDAC-3. We extended our studies using molecular docking studies, which demonstrated a strong interaction between nimbolide and TNF-α. Additionally, we showed that treatment with nimbolide increased GSH, Nrf-2, SOD-1, and HO-1 protein expression; concomitantly abrogated the LPS-triggered TNF-α, p38 MAPK, mTOR, and GSK-3β protein expression. Collectively, these results indicate that TNF-α-regulated NF-κB and HDAC-3 crosstalk was ameliorated by nimbolide with promising anti-nitrosative, antioxidant, and anti-inflammatory properties in LPS-induced ARDS.

Reduction of lung inflammation, oxidative stress and apoptosis by the PDE4 inhibitor roflumilast in experimental model of acute lung injury

Damage of alveolar-capillary barrier, inflammation, oxidative injury, and lung cell apoptosis represent the key features of acute lung injury (ALI). This study evaluated if selective phosphodiesterase (PDE)-4 inhibitor roflumilast can reduce the mentioned changes in lavage-induced model of ALI. Rabbits with ALI were divided into 2 groups: ALI without therapy (A group) and ALI treated with roflumilast i.v. (1 mg/kg; A+R group). One group of healthy animals without ALI served as ventilated controls (C group). All animals were oxygen-ventilated for further 4 h. At the end of experiment, total and differential counts of cells in bronchoalveolar lavage fluid (BALF) and total and differential counts of white blood cells were estimated. Lung edema formation was assessed from determination of protein content in BALF. Pro-inflammatory cytokines (TNFalpha, IL-6 and IL-8) and markers of oxidation (3-nitrotyrosine, thiobarbituric-acid reactive substances) were detected in the lung tissue and plasma. Apoptosis of lung cells was investigated immunohistochemically. Treatment with roflumilast reduced leak of cells, particularly of neutrophils, into the lung, decreased concentrations of cytokines and oxidative products in the lung and plasma, and reduced lung cell apoptosis and edema formation. Concluding, PDE4 inhibitor roflumilast showed potent anti-inflammatory actions in this model of ALI.

Transplantation of Endothelial Progenitor Cells Attenuates Lipopolysaccharide-Induced Lung Injury via Inhibiting the Inflammatory Secretion of Neutrophils in Rats

BACKGROUND

Endothelial progenitor cells (EPCs) are special types of stem cells and are a potential novel therapeutic approach in acute lung injury (ALI). Transplantation of EPCs can ameliorate the inflammatory state by reducing adhesion and exudation of inflammatory cells. However, the mechanism underlying the effect of EPCs on inflammatory response modulation remains unclear. The aim of the present study was to investigate the effect of EPCs on the modulation of neutrophils in vitro and in vivo.

MATERIALS AND METHODS

EPCs were cocultured with neutrophils after lipopolysaccharide stimulation in vitro or transplanted into ALI rats, and neutrophil inflammatory mediators including tumor necrosis factor-α, interleukin-1β, neutrophil elastase, myeloperoxidase and matrix metalloproteinases-9 were detected by enzyme-linked immunosorbent assay, an myeloperoxidase detection kits, reverse transcription-polymerase chain reaction and western blotting.

RESULTS

The results showed that EPCs significantly downregulated the expression of inflammatory mediators when cocultured with neutrophils in vitro or in vivo.

CONCLUSIONS

These findings demonstrated that EPCs contributed to lung injury in ALI rats by downregulating neutrophil inflammatory mediators.

Traumatic Brain Injury-Induced Acute Lung Injury: Evidence for Activation and Inhibition of a Neural-Respiratory-Inflammasome Axis

Approximately 20-25% of traumatic brain injury (TBI) subjects develop acute lung injury (ALI), but the pathomechanisms of TBI-induced ALI remain poorly defined. Our previous work has shown that the inflammasome plays a critical role in TBI-induced secondary pathophysiology and that inflammasome proteins are released in extracellular vesicles (EV) after TBI. Here we investigated whether EV-mediated inflammasome signaling contributed to the etiology of TBI-induced ALI. C57/BL6 male mice were subjected to controlled cortical impact (CCI), and the brains and lungs were examined for inflammasome activation and ALI at 4 and 24 h after TBI. We show that TBI releases EV containing inflammasome proteins into serum that target the lung to cause ALI, supporting activation of a neural-respiratory-inflammasome axis. Administration of a low-molecular-weight heparin (enoxaparin, a blocker of EV uptake) or treatment with a monoclonal antibody against apoptosis speck-like staining protein containing a caspase recruitment domain (anti-ASC) after adoptive transfer of EV isolated from TBI-injured mice significantly inhibited inflammasome activation in the lungs of recipient mice resulting in improved ALI scores.This axis constitutes an important arm of the innate inflammatory response in lung pathology after TBI and targeting this axis represents a novel therapeutic treatment for TBI-induced ALI.

Mild to Moderate to Severe: What Drives the Severity of ARDS in Trauma Patients?

Acute respiratory distress syndrome (ARDS) is a complex inflammatory process with multifactorial etiologies. Risk factors for its development have been extensively studied, but factors associated with worsening severity of disease, as defined by the Berlin criteria, are poorly understood. A retrospective chart and trauma registry review identified trauma patients in our surgical intensive care unit who developed ARDS, defined according to the Berlin definition, between 2010 and 2015. The primary outcome was development of mild, moderate, or severe ARDS. A logistic regression model identified risk factors associated with developing ARDS and with worsening severity of disease. Of 2704 total patients, 432 (16%) developed ARDS. Of those, 100 (23%) were categorized as mild, 176 (41%) as moderate, and 156 (36%) as severe. Two thousand two hundred and seventy-two patients who did not develop ARDS served as controls. Male gender, blunt trauma, severe head and chest injuries, and red blood cell as well as total blood product transfusions are independent risk factors associated with ARDS. Worsening severity of disease is associated with severe chest trauma and volume of plasma transfusion. Novel findings in our study include the association between plasma transfusions and specifically severe chest trauma with worsening severity of ARDS in trauma patients.

Candidate Genes as Biomarkers in Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome Based on mRNA Expression Profile by Next-Generation RNA-Seq Analysis

Up until now, the regulation mechanism at the level of gene during lipopolysaccharide- (LPS-) induced acute respiratory distress syndrome (ARDS) remains unclear. The discovery of differentially expressed genes (DEGs) between LPS-induced ARDS rats and normal rats by next-generation RNA sequencing analysis is of particular interest for the current study. These DEGs may help clinical diagnosis of ARDS and facilitate the selection of the optimal treatment strategy. Randomly, 20 rats were equally divided into 2 groups, the control group and the LPS group. Three rats from each group were selected at random for RNA sequencing analysis. Sequence reads were obtained from Illumina HiSeq4000 and mapped onto the rat reference genome RN6 using Hisat2. We identified 5244 DEGs (Fold_Change > 1.5, and P < 0.05) in the lung tissues from LPS-treated rats compared with normal rats, including 1413 upregulated and 3831 downregulated expressed genes. Lots of chemokine family members were among the most upregulated genes in LPS group. Gene ontology (GO) analysis revealed that almost all of the most enriched and meaningful biological process terms were mainly involved in the functions like immune-inflammation response and the pathways like cytokine-cytokine receptor interaction. We also found that, as for GO molecular function terms, the enriched terms were mainly related to chemokines and cytokines. DEGs with fold change over 100 were verified by quantitative real-time polymerase chain reaction and reanalyzed by gene-gene coexpression network, and the results elucidated central roles of chemokines in LPS-induced ARDS. Our results revealed some new biomarkers for uncovering mechanisms and processes of ARDS.

The effects of hydroxyethyl starch and gelatine on pulmonary cytokine production and oedema formation

Recently, side effects of plasma expanders like hydroxyethyl starch and gelatine gained considerable attention. Most studies have focused on the kidneys; lungs remain unconsidered. Isolated mouse lungs were perfused for 4 hours with buffer solutions based on hydroxyethyl starch (HES) 130/0.4, HES 200/0.5 or gelatine and ventilated with low or high pressure under physiological pH and alkalosis. Outcome parameters were cytokine levels and the wet-to-dry ratio. For cytokine release, murine and human PCLS were incubated in three different buffers and time points.In lungs perfused with the gelatine based buffer IL-6, MIP-2 and KC increased when ventilated with high pressure. Wet-to-dry ratios increased stronger in lungs perfused with gelatine - compared to HES 130/0.4. Alkalotic perfusion resulted in higher cytokine levels but normal wet-to-dry ratio. Murine PCLS supernatants showed increased IL-6 and KC when incubated in gelatine based buffer, whereas in human PCLS IL-8 was elevated. In murine IPL HES 130/0.4 has lung protective effects in comparison to gelatine based infusion solutions, especially in the presence of high-pressure ventilation. Gelatine perfusion resulted in increased cytokine production. Our findings suggest that gelatine based solutions may have side effects in patients with lung injury or lung oedema.

Diosmetin Alleviates Lipopolysaccharide-Induced Acute Lung Injury through Activating the Nrf2 Pathway and Inhibiting the NLRP3 Inflammasome

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a common clinical syndrome of diffuse lung inflammation with high mortality rates and limited therapeutic methods. Diosmetin, an active component from Chinese herbs, has long been noticed because of its antioxidant and anti-inflammatory activities. The aim of this study was to evaluate the effects of diosmetin on LPS-induced ALI model and unveil the possible mechanisms. Our results revealed that pretreatment with diosmetin effectively alleviated lung histopathological changes, which were further evaluated by lung injury scores. Diosmetin also decreased lung wet/dry ratios, as well as total protein levels, inflammatory cell infiltration and proinflammatory cytokine (eg. TNF-α, IL-1β and IL-6) overproduction in bronchoalveolar lavage fluid (BALF). Additionally, increased MPO, MDA and ROS levels induced by LPS were also markly suppressed by diosmetin. Furthermore, diosmetin significantly increased the expression of Nrf2 along with its target gene HO-1 and blocked the activation of NLRP3 inflammasome in the lung tissues, which might be central to the protective effects of diosmetin. Further supporting these results, in vitro experiments also showed that diosmetin activated Nrf2 and HO-1, as well as inhibited the NLRP3 inflammasome in both RAW264.7 and A549 cells. The present study highlights the protective effects of diosmetin on LPS-induced ALI via activation of Nrf2 and inhibition of NLRP3 inflammasome, bringing up the hope of its application as a therapeutic drug towards LPS-induced ALI.

MicroRNAs as biomarkers of acute lung injury

Acute respiratory distress syndrome (ARDS) is a common and complex inflammatory lung diseases affecting critically ill patients requiring mechanical ventilation. MicroRNAs (miRNAs), a novel pathway of non-coding RNA molecules that regulate gene expression at the post-transcriptional level, have emerged as a novel class of gene expression, and can play important roles in inflammation or apoptosis, which are common manifestations of ARDS and diffuse alveolar damage (DAD). In the present review, we discuss the role of miRNAs as biomarkers of ARDS and DAD, and their potential use as therapeutic targets for this condition.

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

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

Metabolomics based predictive biomarker model of ARDS: A systemic measure of clinical hypoxemia

Despite advancements in ventilator technologies, lung supportive and rescue therapies, the outcome and prognostication in acute respiratory distress syndrome (ARDS) remains incremental and ambiguous. Metabolomics is a potential insightful measure to the diagnostic approaches practiced in critical disease settings. In our study patients diagnosed with mild and moderate/severe ARDS clinically governed by hypoxemic P/F ratio between 100-300 but with indistinct molecular phenotype were discriminated employing nuclear magnetic resonance (NMR) based metabolomics of mini bronchoalveolar lavage fluid (mBALF). Resulting biomarker prototype comprising six metabolites was substantiated highlighting ARDS susceptibility/recovery. Both the groups (mild and moderate/severe ARDS) showed distinct biochemical profile based on 83.3% classification by discriminant function analysis and cross validated accuracy of 91% using partial least squares discriminant analysis as major classifier. The predictive performance of narrowed down six metabolites were found analogous with chemometrics. The proposed biomarker model consisting of six metabolites proline, lysine/arginine, taurine, threonine and glutamate were found characteristic of ARDS sub-stages with aberrant metabolism observed mainly in arginine, proline metabolism, lysine synthesis and so forth correlating to diseased metabotype. Thus NMR based metabolomics has provided new insight into ARDS sub-stages and conclusively a precise biomarker model proposed, reflecting underlying metabolic dysfunction aiding prior clinical decision making.

Poly(ADP-Ribose)Polymerase-1 in Lung Inflammatory Disorders: A Review

Asthma, acute lung injury (ALI), and chronic obstructive pulmonary disease (COPD) are lung inflammatory disorders with a common outcome, that is, difficulty in breathing. Corticosteroids, a class of potent anti-inflammatory drugs, have shown less success in the treatment/management of these disorders, particularly ALI and COPD; thus, alternative therapies are needed. Poly(ADP-ribose)polymerases (PARPs) are the post-translational modifying enzymes with a primary role in DNA repair. During the last two decades, several studies have reported the critical role played by PARPs in a good of inflammatory disorders. In the current review, the studies that address the role of PARPs in asthma, ALI, and COPD have been discussed. Among the different members of the family, PARP-1 emerges as a key player in the orchestration of lung inflammation in asthma and ALI. In addition, PARP activation seems to be associated with the progression of COPD. Furthermore, PARP-14 seems to play a crucial role in asthma. STAT-6 and GATA-3 are reported to be central players in PARP-1-mediated eosinophilic inflammation in asthma. Interestingly, oxidative stress-PARP-1-NF-κB axis appears to be tightly linked with inflammatory response in all three-lung diseases despite their distinct pathophysiologies. The present review sheds light on PARP-1-regulated factors, which may be common or differential players in asthma/ALI/COPD and put forward our prospective for future studies.

Endocan as an early biomarker of severity in patients with acute respiratory distress syndrome

Background

Plasma concentrations of endocan, a proteoglycan preferentially expressed in the pulmonary vasculature, may represent a biomarker of lung (dys)function. We sought to determine whether the measurement of plasma endocan levels early in the course of acute respiratory distress syndrome (ARDS) could help predict risk of death or of prolonged ventilation.

Methods

All patients present in the department of intensive care during a 150-day period were screened for ARDS (using the Berlin definition). Endocan concentrations were measured at the moment of ARDS diagnosis (T0) and the following morning (T1). We compared data from survivors and non-survivors and data from survivors with less than 10 days of ventilator support (good evolution) and those who died or needed more than 10 days of mechanical ventilation (poor evolution). Results are presented as numbers (percentages), mean ± standard deviation or medians (percentile 25–75).

Results

Ninety-six consecutive patients were included [median APACHE II score of 21 (17–27) and SOFA score of 9 (6–12), PaO₂/FiO₂ ratio 155 (113–206)]; 64 (67%) had sepsis and 51 (53%) were receiving norepinephrine. Non-survivors were older (66 ± 15 vs. 59 ± 18 years, p = 0.045) and had higher APACHE II scores [27 (22–30) vs. 20 (15–24), p < 0.001] and blood lactate concentrations at study inclusion [2.1 (1.3–4.0) vs. 1.5 (0.9–2.6) mmol/L, p = 0.024] than survivors, but PaO₂/FiO₂ ratios [150 (116–207) vs. 158 (110–206), p = 0.95] were similar in the two groups. Endocan concentrations on the day after ARDS diagnosis were significantly higher in patients with poor evolution than in those with good evolution [12.0 (6.8–18.6) vs. 7.2 (5.4–12.5), p < 0.01].

Conclusion

Blood endocan concentrations early in the evolution of ARDS may be a useful marker of disease severity.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-017-0311-4) contains supplementary material, which is available to authorized users.

Radiation Mitigating Properties of Intranasally Administered KL4 Surfactant in a Murine Model of Radiation-Induced Lung Damage

The threat of exposure to ionizing radiation from a nuclear reactor accident or deliberate terrorist actions is a significant public health concern. The lung is particularly susceptible to radiation-induced injury from external sources or inhalation of radioactive particles from radioactive fallout. Radiation-induced lung disease can manifest with an acute radiation pneumonitis and/or delayed effects leading to pulmonary fibrosis. As prior warning of radiation exposure is unlikely, medical countermeasures (MCMs) to mitigate radiation-induced lung disease that can be given in mass-casualty situations many hours or days postirradiation are needed to prevent both early and late lung damage. In this study, KL₄ surfactant (lucinactant) was evaluated as a radiation mitigator in a well-characterized mouse model of targeted thoracic radiation exposure, for its effect on both early (several weeks) and late (18 weeks) lung damage. Here, 120 mg/kg total phospholipid of KL₄ surfactant was administered twice daily intranasally, (enabling intrapulmonary inhalation of drug) to C57BL/6 mice 24 h after a single 13.5 Gy dose of thoracic irradiation (LD₅₀ dose). Both early and chronic phase (2 and 4 weeks and 18 weeks postirradiation, respectively) assessments were performed. Mice were evaluated for evidence of reduced arterial blood oxygenation and early and chronic lung and systemic inflammation, lung fibrosis and oxidative stress. Analysis was done by performing lung function/respiration dynamics and measuring cellular protein content of bronchoalveolar lavage fluid (BALF), and levels of cytokines, 8-iso-prostaglandin F2α, hydroxyproline in lung and plasma, along with evaluating lung histology. The results of this study showed that intranasal delivery of KL₄ surfactant was able to preserve lung function as evidenced by adequate arterial oxygen saturation and reduced lung inflammation and oxidative stress; total white count and absolute neutrophil count was decreased in BALF, as were plasma pro-inflammatory cytokine levels and biomarker of oxidative stress. KL₄ surfactant is a promising MCM for mitigation of lung tissue damage after targeted, thoracic irradiation and has the potential to be developed as a broad-spectrum, multi-use MCM against chemical, biological, radiological or nuclear threat agents with potential to cause lung injury.

Myocardial ischemic post-conditioning protects the lung against myocardial ischemia/reperfusion-induced damage by activating GSK-3β

Purpose:

To investigate whether modulating GSK-3β could attenuate myocardial ischemia reperfusion injury (MIRI) induced acute lung injury (ALI) and analyze the underlying mechanism.

Methods:

Male SD rats were subjected to MIRI with or without myocardial ischemic post-conditioning in the presence or absence of GSK-3β inhibitor. GSK-3β inhibitor was injected peritoneally 10min before MIRI. Lung W/D weight ratio, MPO, PMNs, histopathological changes, TUNEL, Bax, Bcl-2, IL-6, IL-8, IL-10, GSK-3β, and caspase-3 were evaluated in the lung tissues of all rats.

Results:

After MIRI, lung injury was significantly increased manifested as significant morphological changes and increased leukocytes in the interstitial capillaries, Lung W/D ratio, MPO, and PMN in BALF, which was associated with enhanced inflammation evidenced by increased expressions of IL-6, IL-8 and reduced expression of IL-10. MIRI significantly increased cell apoptosis in the lung as increased levels of apoptotosis, Bax, cleaved caspase-3, and reduced expression of Bcl-2 was observed, which was concomitant with reduced p-GSK-3β. All these changes were reversed/prevented by ischemic post-conditioning, while these beneficial effects of ischemic post-conditioning were abolished by GSK-3β inhibition.

Conclusion:

Myocardial ischemia reperfusion injury induces acute lung injury by induction of inflammation and cell apoptosis. Ischemic post-conditioning protects the lung from ALI following MIRI by increasing p-GSK-3β.

The natural product bergenin ameliorates lipopolysaccharide-induced acute lung injury by inhibiting NF-kappaB activition

ETHNOPHARMACOLOGICAL RELEVANCE

Bergenin, an active constituent of the plants of the genus Bergenia, was reported to have anti-inflammatory effects in the treatment of chronic bronchitis and chronic gastritis clinically. However, its therapeutic effect on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and its potential mechanisms of actions were still unknown.

AIM OF THIS STUDY

To evaluate the effect of bergenin on murine model of acute lung injury induced by LPS and also to explore its potential mechanisms.

MATERIALS AND METHODS

Half an hour and 12h after an intranasal inhalation of LPS, male BALB/c mice were treated with bergenin (50,100 and 200mg/kg) or dexamethasone (DEX, 5mg/kg) by gavage. Twenty-four hours after LPS exposure, the lung wet/dry ratio, histological changes, myeloperoxidase (MPO) in lung tissues, inflammatory cells (in BALF) and cytokines (in BALF and serum) were detected. Meanwhile, the protein expression of MyD88 and the phosphorylation of NF-κB p65 in lung tissue were analyzed using immunoblot analysis. Moreover, the nuclear translocation and the phosphorylation of NF-κB p65 in Raw264.7 cells were also analyzed. The viability of Raw264.7 cells was determined by MTT assay.

RESULTS

Results showed that bergenin significantly decreased pulmonary edema, improved histological changes and reduced MPO activity in lung tissues. Moreover, bergenin obviously decreased inflammatory cells, IL-1β and IL-6 production in BALF, as well as IL-1β, TNF-α and IL-6 production in serum of LPS-induced ALI mice. Furthermore, bergenin markedly inhibited LPS-induced NF-κB p65 phosphorylation, as well as the expression of MyD88 but not the expression of NF-κB p65 in lung tissues. Additionally, bergenin also significantly inhibited the nuclear translocation and the phosphorylation of NF-κB p65 stimulated by LPS in Raw264.7 cells.

CONCLUSIONS

These findings suggested that bergenin had a therapeutic effect on LPS-induced ALI by inhibiting NF-κB activition.

CXCL10/IP-10 Neutralization Can Ameliorate Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome in Rats

The role of C-X-C motif chemokine 10 (CXCL10), a pro-inflammatory factor, in the development of acute respiratory distress syndrome (ARDS) remains unclear. In this study, we explored the role of CXCL10 and the effect of CXCL10 neutralization in lipopolysaccharide (LPS)-induced ARDS in rats. The expression of CXCL10 and its receptor chemokine receptor 3(CXCR3) increased after LPS induction. Moreover, neutralization of CXCL10 ameliorated the severity of ARDS by reducing pulmonary edema, inhibiting the release of inflammatory mediators (IFN-γ, IL-6 and ICAM-1) and limiting inflammatory cells (neutrophils, macrophages, CD8+ T cells) influx into the lung, with a reduction in CXCR3 expression in neutrophils and macrophages. Therefore, CXCL10 could be a potential therapeutic target in LPS-induced ARDS.

Desflurane inhalation before ischemia increases ischemia-reperfusion-induced vascular leakage in isolated rabbit lungs

BACKGROUND

Isoflurane and sevoflurane protect lungs with ischemia-reperfusion (IR) injury. We examined the influence of desflurane on IR lung injury using isolated rabbit lungs perfused with a physiological salt solution.

METHODS

The isolated lungs were divided into three groups: IR, desflurane-treated ischemia-reperfusion (DES-IR), and ventilation/perfusion-continued control (Cont) groups (n = 6 per group). In the DES-IR group, inhalation of desflurane at 1 minimum alveolar concentration (MAC) was conducted in a stable 30-min phase. In the IR and DES-IR groups, ventilation/perfusion was stopped for 75 min after the stable phase. Subsequently, they were resumed. Each lung was placed on a balance, and weighed. Weight changes were measured serially throughout this experiment. The coefficient of filtration (K_fc) was determined immediately before ischemia and 60 min after reperfusion. Furthermore, bronchoalveolar lavage fluid (BALF) was collected from the right bronchus at the completion of the experiment. After the completion of the experiment, the left lung was dried, and the lung wet-to-dry weight ratio (W/D) was calculated.

RESULTS

The K_fc values at 60 min after perfusion were 0.40 ± 0.13 ml/min/mmHg/100 g in the DES-IR group, 0.26 ± 0.07 ml/min/mmHg/100 g in the IR group, and 0.22 ± 0.08 (mean ± SD) ml/mmHg/100 g in the Cont group. In the DES-IR group, the K_fc at 60 min after the start of reperfusion was significantly higher than in the other groups. In the DES-IR group, W/D was significantly higher than in the Cont group. In the DES-IR group, the BALF concentrations of nitric oxide metabolites were significantly higher than in the other groups. In the DES-IR group, the total amount of vascular endothelial growth factor in BALF was significantly higher than in the Cont group.

CONCLUSIONS

The pre-inhalation of desflurane at 1 MAC exacerbates pulmonary IR injury in isolated/perfused rabbit lungs.

Curcumin inhibits paraquat induced lung inflammation and fibrosis by extracellular matrix modifications in mouse model

OBJECTIVE

Paraquat (PQ), a potent herbicide can cause severe toxicity. We report here that fibroproliferation phase of acute lung injury (ALI) is initiated much earlier (within 48 h) after PQ intoxication than previously reported (after 2 weeks) and we aimed to study the protective effects of intranasal curcumin as new therapeutic strategy in mouse model.

METHODS

Mice (Park's strain) were divided into five experimental groups (I) control, received only saline (0.9 % NaCl) (II) PQ, mice intoxicated with PQ (50 mg/kg, i.p., single dose); (III) curcumin, treated with curcumin (5 mg/kg, i.n) an hour before PQ administration; (IV)Veh, DMSO (equal volume to curcumin) given an hour before PQ exposure; (V) DEXA, mice treated with dexamethasone (1 mg/kg, i.p) before an hour of PQ intoxication. After 48 h of the PQ exposure, all mice were sacrificed and samples were analyzed.

RESULTS

Pretreatment with intranasal curcumin (5 mg/kg) could modify the PQ-intoxication (50 mg/kg, i.p) induced structural remodeling of lung parenchyma at an early phase of acute lung injury. Significant increase in inflammatory cell count, reactive oxygen species and hydroxyproline levels were decreased after curcumin pretreatment (all p < 0.05). Histological examination and zymography results were also found consistent.

CONCLUSION

Our results show that curcumin pretreatment decreased the expression of alpha smooth muscle actin (α-SMA), matrix metalloproteinases-9 (MMP-9) and changed the expression of tissue inhibitors of metalloproteinase (TIMP-1) after PQ intoxication. Single toxic dose of PQ has initiated fibroproliferation within 48 h and intranasal curcumin may prove as new therapeutic strategy for PQ induced ALI and fibroproliferation.

Pulmonary surfactant metabolism in the alveolar airspace: Biogenesis, extracellular conversions, recycling

Pulmonary surfactant is a lipid-protein complex that lines and stabilizes the respiratory interface in the alveoli, allowing for gas exchange during the breathing cycle. At the same time, surfactant constitutes the first line of lung defense against pathogens. This review presents an updated view on the processes involved in biogenesis and intracellular processing of newly synthesized and recycled surfactant components, as well as on the extracellular surfactant transformations before and after the formation of the surface active film at the air-water interface. Special attention is paid to the crucial regulation of surfactant homeostasis, because its disruption is associated with several lung pathologies.

Microvascular reactivity is altered early in patients with acute respiratory distress syndrome

BACKGROUND

Acute respiratory distress syndrome (ARDS) is associated with vascular endothelial dysfunction. The resultant microvascular reactivity can be assessed non-invasively using near-infrared spectroscopy (NIRS) and a vascular occlusion test (VOT) and changes have been correlated with severity of organ dysfunction and mortality in other critically ill populations. We used NIRS to study the presence of microcirculatory alterations in patients with ARDS.

METHODS

We studied 27 healthy volunteers and 32 ARDS patients admitted to our intensive care department. NIRS measurements were performed within 24 h after diagnosis (Berlin definition). VOTs were performed by inflating an arm-cuff to a pressure greater than the systolic pressure for 3 min, followed by rapid deflation. The descending (Desc) and ascending (Asc) thenar muscle oxygen saturation (StO2) slopes were calculated. We compared data from volunteers with those from ARDS patients, from ARDS survivors and non-survivors, and from ARDS survivors who required <7 days ventilatory support (good evolution) with those who required >7 days support or died (poor evolution).

RESULTS

ARDS patients had lower StO2 values [75(67-80) vs 79(76-81) %, p = 0.04] and Asc slopes [185(115-233) vs 258(216-306) %/min, p < 0.01] than healthy volunteers, but Desc slopes were similar. The Asc slope was lower in the patients with a poor evolution than in the other patients [121(90-209) vs 222(170-293) %/min, p < 0.01], and in the non-survivors than in the survivors [95(73-120) vs 212(165-252) %/min, p < 0.01].

CONCLUSIONS

In ARDS patients, microvascular reactivity is altered early, and the changes are directly related to the severity of the disease. The ascending slope is the best determinant of outcome.

Microparticles as biomarkers of lung disease: enumeration in biological fluids using lipid bilayer microspheres

Extracellular vesicles, specifically microparticles (MPs), are rapidly gaining attention for their capacity to act as biomarkers for diagnosis, prognosis, or responsiveness to therapy in lung disease, in keeping with the concept of precision medicine. However, MP analysis by high-sensitivity flow cytometry (FCM) is complicated by a lack of accurate means for MP enumeration. To address this gap, we report here an enhanced FCM MP gating and enumeration technique based on the use of novel engineered lipid bilayer microspheres (LBMs). By comparison of LBM-based MP enumeration with conventional bead- or fluorescent-based FCM enumeration techniques and a gravimetric consumption gold standard, we found LBMs to be superior to commercial bead preparations, showing the smallest fixed bias and limits of agreement in Bland Altman analyses. LBMs had simultaneous capacity to aid FCM enumeration of MPs in plasma, BAL, and cell culture supernatants. LBM enumeration detected differences in MP counts in mice exposed to intraperitoneal lipopolysaccharide or saline. LBMs provided for 1) higher sensitivity for gating MPs populations, 2) reduced background within MP gates, 3) more appropriate size, and 4) an inexpensive alternative amenable to different fluorescent tags. LBM-based MP enumeration was useful for a series of different FCM systems assessed, whereas LBM gating benefited high- but not low-sensitivity FCM systems compared with fluorescence gating. By offering exclusive advantages over current means of gating and enumerating MPs, LBMs are uniquely suited to realizing the potential of MPs as biomarkers in biological lung fluids and facilitating precision medicine in lung disease.

Protective effects of thoracic epidural anesthesia on hypoxia-induced acute lung injury in rabbits

The mechanism underlying the effect of thoracic epidural anesthesia (TEA) on hypoxia-induced acute lung injury (ALI) is currently unknown. In the present study, a rabbit acute lung injury model was established to investigate the effects of TEA on inflammatory factors, pulmonary surfactant and ultrastructure. A total of 56 rabbits were randomly assigned to four groups (n=14 per group): Control group (Group C), hypoxia group (Group H), sevoflurane group (Group S) and combined sevoflurane-epidural anesthesia group (Group ES). The ALI model was considered to have been successfully induced when the ratio of arterial oxygen partial pressure to fractional inspired oxygen was <300. The correct placement of a catheter for TEA was confirmed using epidurography. ALI was maintained for 3 h. Arterial blood samples were collected from all groups during spontaneous breathing (T₀) and at 3 h after ALI induction (T₅) in order to evaluate the serum levels of interleukin (IL)-6, IL-8 and IL-10. Bronchoalveolar lavage fluid was harvested to determine the total phospholipid, saturated phosphatidylcholine and total protein levels. Furthermore, the dry/wet weight ratio and the mRNA expression levels of IL-6, IL-8 and IL-10 in the lung tissue were determined using ELISA. In addition, light and transmission electron microscopy and histological techniques were used to examine the morphology of alveolar type II cells in the rat lung tissue. The results indicate that changes of serum IL-6, IL-8 and IL-10 levels following ALI were consistent with the changes in the mRNA expression levels of IL-6, IL-8 and IL-10 in the lung tissue. TEA attenuated these changes and thus reduced the severity of the ALI. In addition, TEA improved the alveolar structure, reduced the number of polymorphonuclear cells and mitigated the damage of lamellar bodies. In summary, the results of the present study indicate that TEA reduces lung tissue damage by inhibiting systemic and local inflammation, decreasing the inactivation of pulmonary surfactant and improving the alveolar ultrastructure following ALI.

Significance of Serum mtDNA Concentration in Lung Injury Induced by Hip Fracture

Acute lung injury is the most serious and fatal complication of the elderly patients with hip fracture, but the mechanisms are unknown. Recent studies demonstrated the mitochondrial DNA (mtDNA) release was associated with lung injury after trauma. This study aimed to examine the differential release of mtDNA between younger and elderly rats suffering from hip fracture and to investigate the possible mechanism of mtDNA in the lung injury induced by hip fracture. In the first part of the study, we investigated the effects of hip fracture on the rats. The elderly and younger rats, respectively, received hip fracture operations. The degree of lung injury was evaluated, toll-like receptor 9 (TLR9) and nuclear factor kappa B (NF-κB) were determined using Western blot, and mtDNA were analyzed by fluorescent quantitative polymerase chain reaction. In the second part of the study, we investigated the effects of mtDNA on the rats. The elderly and younger rats directly received intravenous injections with mtDNA. After 24 h, the specimens were collected and detected as the first part. Hip fracture resulted in significant mtDNA release, TLR9 and NF-κB p65 expression, and lung injury in the rats. Meanwhile, the mtDNA injection could indirectly induce lung injury. Compared to the younger ones, the elderly rats suffered more serious lung injury after hip fracture and mtDNA injection. These results suggest that the lung injury induced by hip fracture may be involved with the mtDNA release and its TLR9/NF-κB pathway.

MicroRNAs: Novel regulatory molecules in acute lung injury/acute respiratory distress syndrome

Acute lung injury (ALI) and the more severe acute respiratory distress syndrome (ARDS) are common and complex inflammatory lung diseases. MicroRNAs (miRNAs), a type of non-coding RNA molecule that regulate gene expression at the post-transcriptional level, have emerged as a novel class of gene regulators, which have critical roles in a wide range of human disorders and diseases, including ALI. Certain types of miRNAs are abnormally expressed in response to lung injury. miRNAs can regulate inflammation pathways by targeting specific molecules and modulate immune response in the process of lung injury and repair. The regulation of miRNA can relieve injury response and promote the recovery of ALI/ARDS. Therefore, miRNAs may serve as novel therapeutic targets in ALI/ARDS.

A Pathophysiologic Approach to Biomarkers in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is an acute-onset hypoxic condition with radiographic bilateral lung infiltration. It is characterized by an acute exudative phase combining diffuse alveolar damage and lung edema followed by a later fibroproliferative phase. Despite an improved understanding of ARDS pathobiology, our ability to predict the development of ARDS and risk-stratify patients with the disease remains limited. Biomarkers may help to identify patients at the highest risk of developing ARDS, assess response to therapy, predict outcome, and optimize enrollment in clinical trials. After a short description of ARDS pathobiology, here, we review the scientific evidence that supports the value of various ARDS biomarkers with regard to their major biological roles in ARDS-associated lung injury and/or repair. Ongoing research aims at identifying and characterizing novel biomarkers, in order to highlight relevant mechanistic explorations of lung injury and repair, and to ultimately develop innovative therapeutic approaches for ARDS patients. This review will focus on the pathophysiologic, diagnostic, and therapeutic implications of biomarkers in ARDS and on their utility to ultimately improve patient care.

Impact of mechanical ventilation on the pathophysiology of progressive acute lung injury

The earliest description of what is now known as the acute respiratory distress syndrome (ARDS) was a highly lethal double pneumonia. Ashbaugh and colleagues (Ashbaugh DG, Bigelow DB, Petty TL, Levine BE Lancet 2: 319-323, 1967) correctly identified the disease as ARDS in 1967. Their initial study showing the positive effect of mechanical ventilation with positive end-expiratory pressure (PEEP) on ARDS mortality was dampened when it was discovered that improperly used mechanical ventilation can cause a secondary ventilator-induced lung injury (VILI), thereby greatly exacerbating ARDS mortality. This Synthesis Report will review the pathophysiology of ARDS and VILI from a mechanical stress-strain perspective. Although inflammation is also an important component of VILI pathology, it is secondary to the mechanical damage caused by excessive strain. The mechanical breath will be deconstructed to show that multiple parameters that comprise the breath-airway pressure, flows, volumes, and the duration during which they are applied to each breath-are critical to lung injury and protection. Specifically, the mechanisms by which a properly set mechanical breath can reduce the development of excessive fluid flux and pulmonary edema, which are a hallmark of ARDS pathology, are reviewed. Using our knowledge of how multiple parameters in the mechanical breath affect lung physiology, the optimal combination of pressures, volumes, flows, and durations that should offer maximum lung protection are postulated.

Effects of basic drugs on prognosis of acute lung injury in mice

The aim of this study was to investigate the effects of basic drugs that alkalizes blood, on prognosis of acute lung injury in mice. Mice were randomized into three groups: Group normal saline, Group THAM, injected with 3.64% tri-(hydroxymethyl) methylamine (THAM), and Group NaHCO3, injected with 5% NaHCO3 (n=26, each group). The acute lung injury model was established by intraperitoneal injection of lipopolysaccharide (LPS; 50 mg/kg), followed by infusion of varying concentrations of the above solution into tail vein at the rate of 0.5 ml/h (controlled by micro pump) for over 2 h. Thirty minutes later, 6 mice from each group were randomly selected for blood gas analysis; then, the mice were killed and their lung tissues were sampled for detection of relative indicators, and the remaining mice were observed for signs of mortality for 72 h. Arterial pH, bicarbonate (HCO3 (-)), and BE and mortality of group THAM and NaHCO3 increased significantly compared to the corresponding parameters of the group normal saline (P<0.05); compared to the group normal saline, group NaHCO3 had increased blood [Na(+)] and decreased [K(+)] and [Ca(2+)] (P<0.05). Blood [Na(+)] of group THAM decreased while the lactic acid concentration increased (P<0.05) compared to the corresponding values of the group normal saline. Malondialdehyde (MDA) and myeloperoxidase (MPO) activity and wet-to-dry lung weight ratio (W/D) of group THAM and NaHCO3 increased significantly relative to group normal saline (P<0.05). Compared with the biopsy results of (A), pathological biopsy of (B) and (C) clearly revealed alveolar wall thickening, edema of alveolar epithelial cells, and infiltration of large neutrophils. Alkalizing blood could neither inhibit inflammatory reactions in LPS mouse model nor reduce the mortality rate of mice with acute lung injury, while excessive alkalization of blood could increase mice mortality.

RAGE/NF-κB signaling mediates lipopolysaccharide induced acute lung injury in neonate rat model

Lipopolysaccharide (LPS) is known to induce acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Accumulating data suggest the crucial role of RAGE in the pathogenesis of ALI/ARDS. However, the mechanism by which RAGE mediates inflammatory lung injury in the neonates remains elusive. In this study we established LPS-induced ALI model in neonate rats, and investigated the role of RAGE/NF-κB signaling in mediating ALI. We found that RAGE antibody or bortezomib reduced LPS-induced histopathological abnormalities in the lung and lung damage score. RAGE antibody or bortezomib also reduced TNF-α level in both serum and BALF of the rats. Furthermore, RAGE antibody or bortezomib significantly reduced LPS-induced upregulation of RAGE and NF-κB expression in the lung. In conclusion, we established ALI model in neonate rats to demonstrate that LPS induced inflammatory lung injury via RAGE/NF-κB signaling. Interference with RAGE/NF-κB signaling is a potential approach to prevent and treat sepsis-related ALI/ARDS.

Smart imaging of acute lung injury: exploration of myeloperoxidase activity using in vivo endoscopic confocal fluorescence microscopy

The pathophysiology of acute lung injury (ALI) is well characterized, but its real-time assessment at bedside remains a challenge. When patients do not improve after 1 wk despite supportive therapies, physicians have to consider open lung biopsy (OLB) to identify the process(es) at play. Sustained inflammation and inadequate repair are often observed in this context. OLB is neither easy to perform in a critical setting nor exempt from complications. Herein, we explore intravital endoscopic confocal fluorescence microscopy (ECFM) of the lung in vivo combined with the use of fluorescent smart probe(s) activated by myeloperoxidase (MPO). MPO is a granular enzyme expressed by polymorphonuclear neutrophils (PMNs) and alveolar macrophages (AMs), catalyzing the synthesis of hypoclorous acid, a by-product of hydrogen peroxide. Activation of these probes was first validated in vitro in relevant cells (i.e., AMs and PMNs) and on MPO-non-expressing cells (as negative controls) and then tested in vivo using three rat models of ALI and real-time intravital imaging with ECFM. Semiquantitative image analyses revealed that in vivo probe-related cellular/background fluorescence was associated with corresponding enhanced lung enzymatic activity and was partly prevented by specific MPO inhibition. Additional ex vivo phenotyping was performed, confirming that fluorescent cells were neutrophil elastase(+) (PMNs) or CD68(+) (AMs). This work is a first step toward "virtual biopsy" of ALI without OLB.

The Immediate Intramedullary Nailing Surgery Increased the Mitochondrial DNA Release That Aggravated Systemic Inflammatory Response and Lung Injury Induced by Elderly Hip Fracture

Conventional concept suggests that immediate surgery is the optimal choice for elderly hip fracture patients; however, few studies focus on the adverse effect of immediate surgery. This study aims to examine the adverse effect of immediate surgery, as well as to explore the meaning of mtDNA release after trauma. In the experiment, elderly rats, respectively, received hip fracture operations or hip fracture plus intramedullary nail surgery. After fracture operations, the serum mtDNA levels as well as the related indicators of systemic inflammatory response and lung injury significantly increased in the rats. After immediate surgery, the above variables were further increased. The serum mtDNA levels were significantly related with the serum cytokine (TNF-α and IL-10) levels and pulmonary histological score. In order to identify the meaning of mtDNA release following hip fracture, the elderly rats received injections with mtDNA. After treatment, the related indicators of systemic inflammatory response and lung injury significantly increased in the rats. These results demonstrated that the immediate surgery increased the mtDNA release that could aggravate systemic inflammatory response and lung injury induced by elderly hip fracture; serum mtDNA might serve as a potential biomarker of systemic inflammatory response and lung injury following elderly hip fracture.

Adenovirus-mediated transfer of the SOCS-1 gene to mouse lung confers protection against hyperoxic acute lung injury

Suppressor of cytokine signaling-1 (SOCS-1) is a member of the suppressor of cytokine signaling family of proteins and an inhibitor of interleukin-6 (IL-6) signaling. SOCS-1 has been shown to protect cells from cellular damage and apoptosis induced by tumor necrosis factor (TNF), lipopolysaccharide (LPS), and interferon gamma (IL-γ). However, it is not known whether increased SOCS-1 is protective during pulmonary oxidative stress. Therefore, we hypothesized that increased SOCS-1 in the lungs of mice would be protective in the setting of hyperoxic lung injury. We administered SOCS-1 adenovirus (Ad-SOCS-1) intratracheally into the lungs and exposed the mice to 100% O2. Mice infected with GFP adenovirus (Ad-GFP) were used as controls. Mice treated with Ad-SOCS-1 had enhanced survival in 100% oxygen compared to Ad-GFP-administered mice. After 3 days of hyperoxia, Ad-GFP mice were ill and tachypnic and died after 4 days. In contrast, all Ad-SOCS-1-treated mice survived for at least 6 days in hyperoxia and 80% survived beyond 7 days. Ad-SOCS-1 transfection protected mouse lungs from injury as indicated by lower lung wet/dry weight, alveolar-capillary protein leakage, reduced infiltration of inflammatory cells, and lower content of thiobarbituric acid-reactive substances in lung homogenate. Our results also indicated that Ad-SOCS-1 significantly inhibits hyperoxia-induced ASK-1 (apoptosis signal-regulating kinase 1) expression. Taken together, these findings show that increased expression of adenovirus-mediated SOCS-1 in the lungs of mice significantly protects against hyperoxic lung injury.

Embelia ribes ameliorates lipopolysaccharide-induced acute respiratory distress syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Embelia ribes Burm. f. (Fam. Myrsinaceae) locally known as Vidanga have been used for treating tumors, ascites, bronchitis, jaundice, diseases of the heart and brain in traditional Indian medicine. However, no scientific studies providing new insights in its pharmacological properties with respect to acute respiratory distress syndrome have been investigated.

AIM

The present investigation aimed to elucidate the effectiveness of Embelin isolated from Embelia ribes seeds on attenuation of LPS-induced acute respiratory distress syndrome in murine models.

METHODS

Embelin (5, 10 and 20 mg/kg/day, i.p.) and Roflumilast (1 mg/kg/day, p.o.) were administered for four days and prior to LPS in rats (i.t.). Four hour after LPS challenge animals were anesthesized and bronchoalveolar lavage was done with ice-cold phosphate buffer. Assessment of BAL fluid was done for albumin, total protein, total cell and neutrophil count, TNF-α levels, nitrosoative stress. Superior lobe of right lung was used for histopathologic evaluation. Inferior lobe of right lung was used to obtain lung edema. Left lung was used for myeloperoxidase estimation. Arterial blood was collected immediately and analyzed for pH, pO2 and pCO2 were estimated.

RESULTS

Pretreatment with embelin (5, 10 and 20 mg/kg, i.p.) decreased lung edema, mononucleated cellular infiltration, nitrate/nitrite, total protein, albumin concentrations, TNF-α in the bronchoalveolar lavage fluid and myeloperoxidase activity in lung homogenate. Embelin markedly prevented pO2 down-regulation and pCO2 augmentation. Additionally, it attenuated lung histopathological changes in acute respiratory distress syndrome model.

CONCLUSION

The study demonstrates the effectiveness of Embelia ribes Burm. f. (Fam. Myrsinaceae) seeds in acute respiratory distress syndrome possibly related to its anti-inflammatory and protective effect against LPS induced airway inflammation by reducing nitrosative stress, reducing physiological parameters of blood gas change, TNF-α and mononucleated cellular infiltration indicating it as a potential therapeutic agent for acute respiratory distress syndrome.

Pycnogenol, a compound isolated from the bark of pinus maritime mill, attenuates ventilator-induced lung injury through inhibiting NF-κB-mediated inflammatory response

BACKGROUND

During mechanical ventilation, high end-inspiratory lung volume results in a permeability type pulmonary oedema, called ventilator-induced lung injury (VILI). The pathophysiology of ventilator-induced lung injury involves multiple mechanisms, such as excessive inflammation. And pycnogenol is a mixture of flavonoid compounds extracted from pine tree bark that have anti-inflammatory activity.

OBJECTIVE

We investigated the effects of pyncogenol on ventilator-induced lung injury in rats.

METHODS

Rats were orally administrated with pycnogenol once (30 mg/kg) 2 days before lung injury induction with mechanical ventilation, then the rats were divided into three groups: lung-protective ventilation (LV group, n = 20), injurious ventilation (HV group, n = 20), HV + pycnogenol group (HV + Pyc group, n = 20). Lung specimens and the bronchoalveolar lavage fluid (BALF) were isolated for histopathological examinations and biochemical analyses.

RESULTS

Pretreatment with pycnogenol could markedly decrease lung wet/dry ratio, lower myeloperoxidase (MPO) activity and total protein concentration and reduce the production of TNF-α, IL-6, IL-1β and MIP-2 in the BALF in ventilator-induced lung injury rats. Additionally, pycnogenol improved the histology of the lung and significantly inhibited the phosphorylation of NF-κB p65 and the degradation of IκB-α.

CONCLUSION

Pycnogenol treatment could attenuate ventilator-induced lung injury in rats, at least in part, through its ability to reduce the production of inflammatory cytokines via inhibiting the activation of NF-κB, indicating it as a potential therapeutic candidate for ventilator-induced lung injury.

Heterogeneous phenotypes of acute respiratory distress syndrome after major trauma

RATIONALE

Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome that can develop at various times after major trauma.

OBJECTIVES

To identify and characterize distinct phenotypes of ARDS after trauma, based on timing of syndrome onset.

METHODS

Latent class analyses were used to identify patterns of ARDS onset in a cohort of critically ill trauma patients. Identified patterns were tested for associations with known ARDS risk factors and associations were externally validated at a separate institution. Eleven plasma biomarkers representing pathophysiologic domains were compared between identified patterns in the validation cohort.

MEASUREMENTS AND MAIN RESULTS

Three patterns of ARDS were identified; class I (52%) early onset on Day 1 or 2, class II (40%) onset on Days 3 and 4, and class III (8%) later onset on Days 4 and 5. Early-onset ARDS was associated with higher Abbreviated Injury Scale scores for the thorax (P < 0.001), lower lowest systolic blood pressure before intensive care unit admission (P = 0.003), and a greater red blood cell transfusion requirement during resuscitation (P = 0.030). In the external validation cohort, early-onset ARDS was also associated with a higher Abbreviated Injury Scale score for the thorax (P = 0.001) and a lower lowest systolic blood pressure before intensive care unit enrollment (P = 0.006). In addition, the early-onset phenotype demonstrated higher plasma levels of soluble receptor for advanced glycation end-products and angiopoietin-2.

CONCLUSIONS

Degree of hemorrhagic shock and severity of thoracic trauma are associated with an early-onset phenotype of ARDS after major trauma. Lung injury biomarkers suggest a dominant alveolar-capillary barrier injury pattern in this phenotype.

Protective effects of intratracheally administered quercetin on lipopolysaccharide-induced acute lung injury

Background

Acute respiratory distress syndrome (ARDS) can result in a life-threatening form of respiratory failure, and established, effective pharmacotherapies are therefore urgently required. Quercetin is one of the most common flavonoids found in fruits and vegetables, and has potent anti-inflammatory and anti-oxidant activities. Quercetin has been demonstrated to exhibit cytoprotective effects through the induction of heme oxygenase (HO)-1. Here, we investigated whether the intratracheal administration of quercetin could suppress lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice as well as the involvement of HO-1 in quercetin’s suppressive effects.

Methods

Mouse model of ALI were established by challenging intratracheally LPS. The wet lung-to-body weight ratio, matrix metalloproteinase (MMP)-9 activities, and pro-inflammatory cytokine productions, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in bronchoalveolar lavage fluid (BALF) were examined in ALI mice with or without quercetin pretreatment. We also examined the effects of quercetin on LPS stimulation in the mouse alveolar macrophage cell line, AMJ2-C11 cells.

Results

Intratracheal administration of quercetin decreased the wet lung-to-body weight ratio. Moreover, quercetin decreased MMP-9 activity and the production of pro-inflammatory cytokines in BALF cells activated by LPS in advance. We determined the expression of quercetin-induced HO-1 in mouse lung, e.g., alveolar macrophages (AMs), alveolar and bronchial epithelial cells. When AMJ2-C11 cells were cultured with quercetin, a marked suppression of LPS-induced pro-inflammatory cytokine production was observed. The cytoprotective effects were attenuated by the addition of the HO-1 inhibitor SnPP. These results indicated that quercetin suppressed LPS-induced lung inflammation, and that an HO-1-dependent pathway mediated these cytoprotective effects.

Conclusions

Our findings indicated that quercetin suppressed LPS-induced lung inflammation, and that an HO-1-dependent pathway mediated these cytoprotective effects. Intratracheal administration of quercetin will lead to new supportive strategies for cytoprotection in these serious lung conditions.