Acute lung injury and the acute respiratory distress syndrome: four decades of inquiry into pathogenesis and rational management

Maresin 1 Maintains the Permeability of Lung Epithelial Cells In Vitro and In Vivo

Previous reports showed that Maresin 1 (MaR1) possessed organ protection effects and could attenuate acute lung injury. Here, we aim to figure out whether MaR1 can maintain the permeability of lung epithelial cells by regulating the expression of tight junction protein during lung injury. Monolayer of murine lung epithelial cells was stimulated by lipopolysaccharide (LPS) with or without MaR1 and the permeability was evaluated. The expression of Claudin-1 and ZO-1 in lung epithelial cells was analyzed by immunofluorescence staining and western blotting. MaR1 was given to the mice after LPS induced acute lung injury. The permeability of lung was assessed by Evans Blue extravasation, lung wet/dry ratio and protein concentration in bronchoalveolar lavage fluid. Lung injury score was also evaluated. The expression of Claudin-1 and ZO-1 in the lung was analyzed by immunofluorescence staining. Results showed that MaR1 maintained the permeability of lung epithelial cells and upregulated the expression of Claudin-1 and ZO-1 after LPS stimulation. In acute lung injury mice, MaR1 upregulated the expression of Claudin-1 and ZO-1, decreased lung permeability, and reduced lung injury. In summary, this study suggests that MaR1 can maintain the permeability of lung epithelial cells by upregulating the expression of Claudin-1 and ZO-1 in acute lung injury.

Involvement of the Bufadienolides in the Detection and Therapy of the Acute Respiratory Distress Syndrome

PURPOSE

The acute respiratory distress syndrome (ARDS) represents a major challenge for clinicians as well as basic scientists. The mortality rate for ARDS has been maintained within the range of 40-52%. The authors have examined the involvement of the "cardiotonic steroids" in the pathogenesis and therapy of ARDS. We have studied the possible role of the bufadienolide, marinobufagenin (MBG), in the pathogenesis of ARDS in both a rat model of ARDS and in patients afflicted with that disorder. In addition, the potential therapeutic benefit of an antagonist of MBG, resibufogenin (RBG), in an animal model has been evaluated.

METHOD

A syndrome resembling human ARDS was produced in the rat by exposing the animals to 100% oxygen for 48 h. In other animals, RBG was administered to these "hyperoxic" rats, and the serum MBG was measured. In human ICU patients, urinary samples were examined for levels of MBG, and the values were compared to those obtained from other ICU patients admitted with diagnoses other than ARDS.

RESULTS

(1) Exposure of rats to hyperoxia produced a histologic picture which resembled that of human ARDS. (2) Serum levels of MBG in the "hyperoxic" rats substantially exceeded those obtained in animals exposed to ambient oxygen levels and were reduced to normal by RBG. (3) In ARDS patients, substantial elevations in urinary MBG were obtained compared to those in non-ARDS ICU patients.

CONCLUSIONS

MBG may serve as an important biomarker for the development of ARDS, and RBG may represent a preventative/therapy in this disorder.

Inflammation-induced caveolin-1 and BMPRII depletion promotes endothelial dysfunction and TGF-β-driven pulmonary vascular remodeling

Endothelial cell (EC) activation and vascular injury are hallmark features of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Caveolin-1 (Cav-1) is highly expressed in pulmonary microvascular ECs and plays a key role in maintaining vascular homeostasis. The aim of this study was to determine if the lung inflammatory response to Escherichia coli lipopolysaccharide (LPS) promotes priming of ECs via Cav-1 depletion and if this contributes to the onset of pulmonary vascular remodeling. To test the hypothesis that depletion of Cav-1 primes ECs to respond to profibrotic signals, C57BL6 wild-type (WT) mice (Tie2.Cre^-;Cav1^fl/fl ) were exposed to nebulized LPS (10 mg; 1 h daily for 4 days) and compared with EC-specific Cav1^-/- (Tie2.Cre⁺;Cav1^fl/fl ). After 96 h of LPS exposure, total lung Cav-1 and bone morphogenetic protein receptor type II (BMPRII) expression were reduced in WT mice. Moreover, plasma albumin leakage, infiltration of immune cells, and levels of IL-6/IL-6R and transforming growth factor-β (TGF-β) were elevated in both LPS-treated WT and EC-Cav1^-/- mice. Finally, EC-Cav1^-/- mice exhibited a modest increase in microvascular thickness basally and even more so on exposure to LPS (96 h). EC-Cav1^-/- mice and LPS-treated WT mice exhibited reduced BMPRII expression and endothelial nitric oxide synthase uncoupling, which along with increased TGF-β promoted TGFβRI-dependent SMAD-2/3 phosphorylation. Finally, human lung sections from patients with ARDS displayed reduced EC Cav-1 expression, elevated TGF-β levels, and severe pulmonary vascular remodeling. Thus EC Cav-1 depletion, oxidative stress-mediated reduction in BMPRII expression, and enhanced TGF-β-driven SMAD-2/3 signaling promote pulmonary vascular remodeling in inflamed lungs.

Protective Effects of Tyrosol against LPS-Induced Acute Lung Injury via Inhibiting NF-κB and AP-1 Activation and Activating the HO-1/Nrf2 Pathways

Tyrosol (Tyr) is a natural antioxidant that displays anti-oxidant and anti-inflammatory properties. The present study aimed to investigate the effect and mechanism of Tyr on lipopolysaccharide (LPS)-induced acute lung injury (ALI). In a mouse model, we found that pretreatment with Tyr significantly improved survival rate, attenuated lung permeability, ameliorated histopathological alterations, reduced expression of the inflammatory mediators and improved expression of the antioxidant enzyme. Further study revealed that Tyr markedly inhibited nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activation at both in vivo and in vitro levels. To investigate the underlying mechanism, we examined the impact of Tyr on the heme oxygenase (HO)-1/nuclear factor erythroid-2 related factor 2 (Nrf2) pathway in vivo and in vitro. The results showed that Tyr significantly improved the expression of HO-1 and the activation of Nrf2. This study offers novel evidence to support the efficacy of Tyr against ALI, which helps to clarify the underlying causes of the therapeutic effects behind Tyr.

Scutellaria baicalensis Ameliorates Acute Lung Injury by Suppressing Inflammation In Vitro and In Vivo

Scutellaria baicalensis has been widely used as both a dietary ingredient and traditional herbal medicine in Taiwan to treat inflammation, cancer, and bacterial and viral infections of the respiratory tract and gastrointestinal tract. This paper aims to investigate the in vitro and in vivo anti-inflammatory effects of S. baicalensis. In HPLC analysis, the fingerprint chromatogram of the water extract of S. baicalensis (WSB) was established. The anti-inflammatory effects of WSB were inverstigated using lipopolysaccharide (LPS)-stimulated mouse macrophage (RAW264.7) in vitro and LPS-induced lung injury in vivo. WSB attenuated the production of LPS-induced nitric oxide (NO), tumor necrosis factor-alpha (TNF-[Formula: see text], interleukin-[Formula: see text] (IL-1[Formula: see text], and IL-6 in vitro and in vivo. Pretreatment with WSB markedly reduced the LPS-induced histological alterations in lung tissues. Furthermore, WSB significantly reduced the number of total cells and the protein concentration levels in the BALF. WSB blocked protein expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), phosphorylation of I[Formula: see text]B-[Formula: see text] protein and MAPKs in LPS-stimulated RAW 264.7 cells and LPS-induce lung injury was also blocked. This study suggests that WSB possesses anti-inflammatory effects in vitro and in vivo, and the results suggested that WSB may be a potential therapeutic candidate for the treatment of inflammatory diseases.

Modulating the Biologic Activity of Mesenteric Lymph after Traumatic Shock Decreases Systemic Inflammation and End Organ Injury

Introduction

Trauma/hemorrhagic shock (T/HS) causes the release of pro-inflammatory mediators into the mesenteric lymph (ML), triggering a systemic inflammatory response and acute lung injury (ALI). Direct and pharmacologic vagal nerve stimulation prevents gut barrier failure and alters the biologic activity of ML after injury. We hypothesize that treatment with a pharmacologic vagal agonist after T/HS would attenuate the biologic activity of ML and prevent ALI.

Methods

ML was collected from male Sprague-Dawley rats after T/HS, trauma-sham shock (T/SS) or T/HS with administration of the pharmacologic vagal agonist CPSI-121. ML samples from each experimental group were injected into naïve mice to assess biologic activity. Blood samples were analyzed for changes in STAT3 phosphorylation (pSTAT3). Lung injury was characterized by histology, permeability and immune cell recruitment.

Results

T/HS lymph injected in naïve mice caused a systemic inflammatory response characterized by hypotension and increased circulating monocyte pSTAT3 activity. Injection of T/HS lymph also resulted in ALI, confirmed by histology, lung permeability and increased recruitment of pulmonary macrophages and neutrophils to lung parenchyma. CPSI-121 attenuated T/HS lymph-induced systemic inflammatory response and ALI with stable hemodynamics and similar monocyte pSTAT3 levels, lung histology, lung permeability and lung immune cell recruitment compared to animals injected with lymph from T/SS.

Conclusion

Treatment with CPSI-121 after T/HS attenuated the biologic activity of the ML and decreased ALI. Given the superior clinical feasibility of utilizing a pharmacologic approach to vagal nerve stimulation, CPSI-121 is a potential treatment strategy to limit end organ dysfunction after injury.

DIFFERENTIAL SUSCEPTIBILITY OF HUMAN SP-B GENETIC VARIANTS ON LUNG INJURY CAUSED BY BACTERIAL PNEUMONIA AND THE EFFECT OF A CHEMICALLY MODIFIED CURCUMIN

Staphylococcus aureus is a common cause of nosocomial pneumonia frequently resulting in acute respiratory distress syndrome (ARDS). Surfactant protein B (SP-B) gene expresses two proteins involved in lowering surface tension and host defense. Genotyping studies demonstrate a significant association between human SP-B genetic variants and ARDS. Curcumins have been shown to attenuate host inflammation in many sepsis models. Our hypothesis is that functional differences of SP-B variants and treatment with curcumin (CMC2.24) modulate lung injury in bacterial pneumonia. Humanized transgenic mice, expressing either SP-B T or C allele without mouse SP-B gene, were used. Bioluminescent labeled S. aureus Xen 36 (50 μL) was injected intratracheally to cause pneumonia. Infected mice received daily CMC2.24 (40 mg/kg) or vehicle alone by oral gavage. Dynamic changes of bacteria were monitored using in vivo imaging system. Histological, cellular, and molecular indices of lung injury were studied in infected mice 48 h after infection. In vivo imaging analysis revealed total flux (bacterial number) was higher in the lung of infected SP-B-C mice compared with infected SP-B-T mice (P < 0.05). Infected SP-B-C mice demonstrated increased mortality, lung injury, apoptosis, and NF-κB expression compared with infected SP-B-T mice. Compared with controls, CMC2.24 treatment significantly reduced the following: mortality, total bacterial flux and lung tissue apoptosis, inflammatory cells, NF-κB expression (P < 0.05), and MMPs-2, -9, -12 activities (P < 0.05). We conclude that mice with SP-B-C allele are more susceptible to S. aureus pneumonia than mice with SP-B-T allele, and that CMC2.24 attenuates lung injury thus reducing mortality.

Targeting Neutrophils to Prevent Malaria-Associated Acute Lung Injury/Acute Respiratory Distress Syndrome in Mice

Malaria remains one of the greatest burdens to global health, causing nearly 500,000 deaths in 2014. When manifesting in the lungs, severe malaria causes acute lung injury/acute respiratory distress syndrome (ALI/ARDS). We have previously shown that a proportion of DBA/2 mice infected with Plasmodium berghei ANKA (PbA) develop ALI/ARDS and that these mice recapitulate various aspects of the human syndrome, such as pulmonary edema, hemorrhaging, pleural effusion and hypoxemia. Herein, we investigated the role of neutrophils in the pathogenesis of malaria-associated ALI/ARDS. Mice developing ALI/ARDS showed greater neutrophil accumulation in the lungs compared with mice that did not develop pulmonary complications. In addition, mice with ALI/ARDS produced more neutrophil-attracting chemokines, myeloperoxidase and reactive oxygen species. We also observed that the parasites Plasmodium falciparum and PbA induced the formation of neutrophil extracellular traps (NETs) ex vivo, which were associated with inflammation and tissue injury. The depletion of neutrophils, treatment with AMD3100 (a CXCR4 antagonist), Pulmozyme (human recombinant DNase) or Sivelestat (inhibitor of neutrophil elastase) decreased the development of malaria-associated ALI/ARDS and significantly increased mouse survival. This study implicates neutrophils and NETs in the genesis of experimentally induced malaria-associated ALI/ARDS and proposes a new therapeutic approach to improve the prognosis of severe malaria.

Outcomes and survival prediction models for severe adult acute respiratory distress syndrome treated with extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory distress syndrome (ARDS) has known a growing interest over the last decades with promising results during the 2009 A(H1N1) influenza epidemic. Targeting populations that can most benefit from this therapy is now of major importance.

Survival has steadily improved for a decade, reaching up to 65% at hospital discharge in the most recent cohorts. However, ECMO is still marred by frequent and significant complications such as bleeding and nosocomial infections. In addition, physiological and psychological symptoms are commonly described in long-term follow-up of ECMO-treated ARDS survivors. Because this therapy is costly and exposes patients to significant complications, seven prediction models have been developed recently to help clinicians identify patients most likely to survive once ECMO has been initiated and to facilitate appropriate comparison of risk-adjusted outcomes between centres and over time. Higher age, immunocompromised status, associated extra-pulmonary organ dysfunction, low respiratory compliance and non-influenzae diagnosis seem to be the main determinants of poorer outcome.

Biochemical and Ultrastructural Lung Damage Induced by Rhabdomyolysis in the Rat

Rhabdomyolysis-induced oxidative stress is associated with morphological and functional damage to the kidney and other organs, but applications of this model in the lung are still lacking. The aim of the present study was to determine the relationship between oxidative stress and the morphological changes occurring in the lungs of rats subjected to rhabdomyolysis. Rhabdomyolysis was induced by intramuscular glycerol injection (50% v/v, 10 ml/kg), and the control group was injected with saline vehicle. Arterial blood samples were drawn at 0, 2, 4, and 6 hrs for measurement of arterial gases, creatine kinase activity, and plasma free F2-isoprostane levels. Six hours later, the lungs were removed to determine the wet-to-dry weight ratio, reduced glutathione (GSH) and GSH disulfide (GSSG) levels, and activity of antioxidant enzymes (cataiase [CAT], superoxide dismutase [SOD], and GSH peroxidase [GSH-Px]). Protein carbonylation and lipid peroxidation were assessed in the lungs by measurement of carbonyl and malondialdehyde (MDA) production, respectively. Bronchoalveolar lavage, cell counts, and lung ultrastructural studies were also performed. Six hours after glycerol injection, arterial PO2 and PCO2 were 23% and 38% lower, respectively, and plasma free F2-isoprostane levels were 72% higher, compared with control values. In lungs, protein carbonyl and MDA production were 58% and 12% higher, respectively; the GSH:GSSG ratio and GSH-Px activity were 43% and 60% lower, respectively; and activities of CAT and SOD showed no significant differences compared with controls. Rhabdomyolysis-induced ultrastructural impairment of the lung showed Type II cell damage, extracytoplasmic lamellar bodies and lack of tubular myelin reorganization, endothelial cellular edema, and no disruption of the alveolar-capillary barrier. These results provide evidence that rhabdomyolysis could induce tissue injury associated with increased oxidative stress, suggesting the contribution of oxidative stress to the pathogenic mechanism of acute lung injury.

Prophylactic and therapeutic treatment with the flavonone sakuranetin ameliorates LPS-induced acute lung injury

Sakuranetin is the main isolate flavonoid from Baccharis retusa (Asteraceae) leaves and exhibits anti-inflammatory and antioxidative activities. Acute respiratory distress syndrome is an acute failure of the respiratory system for which effective treatment is urgently necessary. This study investigated the preventive and therapeutic effects of sakuranetin on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. Animals were treated with intranasal sakuranetin 30 min before or 6 h after instillation of LPS. Twenty-four hours after ALI was induced, lung function, inflammation, macrophages population markers, collagen fiber deposition, the extent of oxidative stress, and the expression of matrix metalloprotease-9 (MMP-9), tissue inhibitor of MMP-9 (TIMP-1) and NF-κB were evaluated. The animals began to show lung alterations 6 h after LPS instillation, and these changes persisted until 24 h after LPS administration. Preventive and therapeutic treatment with sakuranetin reduced the neutrophils in the peripheral blood and in the bronchial alveolar lavage. Sakuranetin treatment also reduced macrophage populations, particularly that of M1-like macrophages. In addition, sakurnaetin treatment reduced keratinocyte-derived chemokines (IL-8 homolog) and NF-κB levels, collagen fiber formation, MMM-9 and TIMP-1-positive cells, and oxidative stress in lung tissues compared with LPS animals treated with vehicle. Finally, sakuranetin treatment also reduced total protein, and the levels of TNF-α and IL-1β in the lung. This study shows that sakuranetin prevented and reduced pulmonary inflammation induced by LPS. Because sakuranetin modulates oxidative stress, the NF-κB pathway, and lung function, it may constitute a novel therapeutic candidate to prevent and treat ALI.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Association of Heme Oxygenase 1 with Lung Protection in Malaria-Associated ALI/ARDS

Malaria is a serious disease, caused by the parasite of the genus Plasmodium, which was responsible for 440,000 deaths in 2015. Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is one of the main clinical complications in severe malaria. The murine model DBA/2 reproduces the clinical signs of ALI/ARDS in humans, when infected with Plasmodium berghei ANKA. High levels of HO-1 were reported in cases of severe malaria. Our data indicated that the HO-1 mRNA and protein expression are increased in mice that develop malaria-associated ALI/ARDS (MA-ALI/ARDS). Additionally, the hemin, a HO-1 inducing drug, prevented mice from developing MA-ALI/ARDS when administered prior to the development of MA-ALI/ARDS in this model. Also, hemin treatment showed an amelioration of respiratory parameters in mice, high VEGF levels in the sera, and a decrease in vascular permeability in the lung, which are signs of ALI/ARDS. Therefore, the induction of HO-1 before the development of MA-ALI/ARDS could be protective. However, the increased expression of HO-1 on the onset of MA-ALI/ARDS development may represent an effort to revert the phenotype of this syndrome by the host. We therefore confirm that HO-1 inducing drugs could be used for prevention of MA-ALI/ARDS in humans.

A Novel Large Animal Model of Acute Respiratory Distress Syndrome Induced by Mitochondrial Products

OBJECTIVE

We aimed to create a reproducible lung injury model utilizing injection of mitochondrial damage-associated molecular products. Our goal was to characterize the pathophysiologic response to damage-associated molecular pattern mediated organ injury.

SUMMARY BACKGROUND DATA

There remain significant gaps in our understanding of acute respiratory distress syndrome, in part due to the lack of clinically applicable animal models of this disease. Animal models of noninfectious, tissue damage-induced lung injury are needed to understand the signals and responses associated with this injury.

METHODS

Ten pigs (35-45 kg) received an intravenous dose of disrupted mitochondrial products and were followed for 6 hours under general anesthesia. These animals were compared to a control group (n = 5) and a model of lung injury induced by bacterial products (lipopolysaccharide n = 5).

RESULTS

Heart rate and temperature were significantly elevated in the mitochondrial product (204 ± 12 and 41 ± 1) and lipopolysaccharide groups (178 ± 18 and 42 ± 0.5) compared with controls (100 ± 13 and 38 ± 0.5) (P <0.05). Lung oxygenation (PaO2/FiO2) was significantly lower 6 hours after injection in the mitochondrial products and lipopolysaccharide groups compared with controls (170 ± 39, 196 ± 27, and 564 ± 75 mm Hg respectively, P = 0.001). Lung injury scoring of histological sections was significantly worse in mitochondrial and lipopolysaccharide groups compared with controls (mitochondrial-64 ± 6, lipopolysaccharide-54 ± 8, control-14 ± 1.5, P= 0.002).

CONCLUSIONS

Our data demonstrated that the presence of mitochondrial products in the circulation leads to systemic inflammatory response and lung injury. In its acute phase lung injury induced by tissue or bacterial products is clinically indistinguishable.

Platelets in Pulmonary Immune Responses and Inflammatory Lung Diseases

Platelets are essential for physiological hemostasis and are central in pathological thrombosis. These are their traditional and best known activities in health and disease. In addition, however, platelets have specializations that broaden their functional repertoire considerably. These functional capabilities, some of which are recently discovered, include the ability to sense and respond to infectious and immune signals and to act as inflammatory effector cells. Human platelets and platelets from mice and other experimental animals can link the innate and adaptive limbs of the immune system and act across the immune continuum, often also linking immune and hemostatic functions. Traditional and newly recognized facets of the biology of platelets are relevant to defensive, physiological immune responses of the lungs and to inflammatory lung diseases. The emerging view of platelets as blood cells that are much more diverse and versatile than previously thought further predicts that additional features of the biology of platelets and of megakaryocytes, the precursors of platelets, will be discovered and that some of these will also influence pulmonary immune defenses and inflammatory injury.

Lipopolysaccharide promotes pulmonary fibrosis in acute respiratory distress syndrome (ARDS) via lincRNA-p21 induced inhibition of Thy-1 expression

Acute respiratory distress syndrome (ARDS) is a common clinical disorder characterized by pulmonary edema leading to acute lung damage and arterial hypoxemia. Pulmonary fibrosis is a progressive, fibrotic lung disorder, whose pathogenesis in ARDS remains speculative. LincRNA-p21 was a novel regulator of cell proliferation, apoptosis and DNA damage response. This study aims to investigate the effects and mechanism of lincRNA-p21 on pulmonary fibrosis in ARDS. Purified 10 mg/kg LPS was dropped into airways of C57BL/6 mice. Expression levels of lincRNA-p21 and Thy-1 were measured by real-time PCR or western blotting. Proliferation of lung fibroblasts was analyzed by BrdU incorporation assay. Lung and BAL collagen contents were estimated using colorimetric Sircol assay. LincRNA-p21 expression was time-dependently increased and Thy-1 expression was time-dependently reduced in a mouse model of ARDS and in LPS-treated lung fibroblasts. Meanwhile, lung fibroblast proliferation was also time-dependently elevated in LPS-treated lung fibroblasts. In addition, lung fibroblast proliferation could be promoted by lincRNA-p21 overexpression and LPS treatment, however, the elevated lung fibroblast proliferation was further abrogated by Thy-1 overexpression or lincRNA-p21 interference. And Thy-1 interference could elevate cell viability of lung fibroblasts and rescue the reduction of lung fibroblast proliferation induced by lincRNA-p21 interference. Moreover, lincRNA-p21 overexpression dramatically inhibited acetylation of H3 and H4 at the Thy-1 promoter and Thy-1 expression levels in HLF1 cells. Finally, lincRNA-p21 interference rescued LPS-induced increase of lung and BAL collagen contents. LincRNA-p21 could lead to pulmonary fibrosis in ARDS by inhibition of the expression of Thy-1.

PPAR-α activation reduced LPS-induced inflammation in alveolar epithelial cells

PURPOSE OF THE STUDY

Acute respiratory distress syndrome (ARDS) represents a major cause of mortality in intensive care patients. Activation of peroxisome proliferator-activated receptor-α (PPAR-α) by fibrates, such as WY-14643 (WY), has been described to beneficially influence inflammation and experimental lung injury. The impact of PPAR-α activation on alveolar epithelial cells (AEC) has not been studied yet.

MATERIALS AND METHODS

To investigate the effect of PPAR-α activator WY in wild-type (WT) and in PPAR-α knockout (PPAR-α(-/-)) animals, mice were treated in different regimes: mice received chow enriched with or without WY for 14 days prior AEC isolation (in-vivo treatment). Furthermore, isolated AEC from both groups were subsequently cultured with or without WY (in-vitro treatment). AEC were stimulated with lipopolysaccharide (LPS). Cell culture supernatant and cell lysate were used for analysis of pro-inflammatory mediators.

RESULTS

AEC challenged with LPS showed a significantly increased generation of pro-inflammatory mediators. After in-vivo WY-exposure, AEC displayed significantly reduced concentration of TNF-α, MIP-2, and TxB2 after LPS stimulation. This beneficial effect was abrogated in PPAR-α(-/-) animals. Interestingly, sole in-vitro application of WY-14643 failed to reduce levels of pro-inflammatory mediators whereas we found an additive effect of a combined in-vivo and in-vitro PPAR-α activation. PGE2 concentration remained high after LPS challenge and was unaffected by WY treatment.

CONCLUSION

PPAR-α activation by in-vivo exposure to fibrates reduced the inflammatory response in isolated AEC. These findings may facilitate further studies investigating the translation of pharmacological PPAR-α activation into clinical therapy of ARDS.

Recombinant human brain natriuretic peptide attenuates LPS-induced cellular injury in human fetal lung fibroblasts via inhibiting MAPK and NF-κB pathway activation

Inflammatory responses are vital in lung injury diseases, particularly acute respiratory distress syndrome (ARDS). Recombinant human brain natriuretic peptide (rhBNP) has been shown to exhibit anti‑inflammatory effects in vivo in our previous studies. The present study aimed to investigate the mechanisms underlying the anti‑inflammatory effects of rhBNP on lipopolysaccharide (LPS)-induced human fetal lung fibroblasts (HFL-1). The results showed that LPS induced a significant increase in the leakage of lactate dehydrogenase and the secretion of interleukin (IL)‑1β. Activation of p38, extracellular-signal regulated kinase (ERK) 1/2, c‑Jun NH2-terminal kinase (JNK) mitogen‑activated protein kinases (MAPK)s, and nuclear factor (NF)‑κB in HFL‑1 cells was also observed following treatment with LPS. Treatment with rhBNP (0.1 µM) reduced the production of IL‑1β at the protein and mRNA levels. Moreover, rhBNP decreased the phosphorylation of p38, ERK1/2 and JNK induced by LPS. However, the JNK inhibitor, SP600125, significantly inhibited LPS‑induced IL‑1β production. These results indicate that the inhibition of IL‑1β by may dependent upon the JNK signaling pathway. The LPS‑induced NF‑κB activation was also suppressed by rhBNP, and IL‑1β production was inhibited by the NF‑κB inhibitor. Furthermore, NF‑κB activation was attenuated by the JNK inhibitor, indicating that NF‑κB activation was dependent on the JNK signaling pathway. The present study suggests that rhBNP exhibits an anti‑inflammatory effect on LPS‑induced HFL‑1 cell injury via the inhibition of MAPK and NF‑κB signaling pathways and may exhibit therapeutic potential for acute lung injury and ARDS.

Expression and role of connexin-based gap junctions in pulmonary inflammatory diseases

Connexins are transmembrane proteins that can generate intercellular communication channels known as gap junctions. They contribute to the direct movement of ions and larger cytoplasmic solutes between various cell types. In the lung, connexins participate in a variety of physiological functions, such as tissue homeostasis and host defence. In addition, emerging evidence supports a role for connexins in various pulmonary inflammatory diseases, such as asthma, pulmonary hypertension, acute lung injury, lung fibrosis or cystic fibrosis. In these diseases, the altered expression of connexins leads to disruption of normal intercellular communication pathways, thus contributing to various pathophysiological aspects, such as inflammation or tissue altered reactivity and remodeling. The present review describes connexin structure and organization in gap junctions. It focuses on connexins in the lung, including pulmonary bronchial and arterial beds, by looking at their expression, regulation and physiological functions. This work also addresses the issue of connexin expression alteration in various pulmonary inflammatory diseases and describes how targeting connexin-based gap junctions with pharmacological tools, synthetic blocking peptides or genetic approaches, may open new therapeutic perspectives in the treatment of these diseases.

Neonatal Type II Alveolar Epithelial Cell Transplant Facilitates Lung Reparation in Piglets With Acute Lung Injury and Extracorporeal Life Support

OBJECTIVES

Type II alveolar epithelial cells have potential for lung growth and reparation. Extracorporeal membrane oxygenation is used as life support for lung impairment resulting from acute respiratory distress syndrome. We hypothesized that intratracheal transplantation of isogeneic primary type II alveolar epithelial cells in combination with extracorporeal membrane oxygenation may facilitate lung reparation for acute lung injury (ALI).

DESIGN

A randomized, controlled experiment.

SETTING

An animal laboratory in a university pediatric center.

SUBJECTS

Twenty-eight 4- to 6-week young piglets, weighing 7-8 kg.

INTERVENTIONS

Type II alveolar epithelial cells from neonatal male piglet lungs were isolated, purified, cultured, and labeled with chemical stain PKH26. After 3-6 hours of induction of ALI by IV endotoxin and mechanical ventilation (MV), young female piglets were allocated to five groups (n = 5): ALI-MV, ALI treated with MV; ALI-EC, ALI treated with both MV and venovenous extracorporeal membrane oxygenation; ALI-EC-T, ALI-EC protocol plus intratracheal type II alveolar epithelial cell transplant; CON-MV, healthy animals treated with MV; and CON-EC-T, healthy animals treated with venovenous extracorporeal membrane oxygenation. After 24 hours, animals were weaned from treatment for recovery in the ensuing 14 days, with their lungs assessed for injury and reparation.

MEASUREMENTS AND MAIN RESULTS

Lung injury for animals in ALI-MV was moderate to severe, whereas much milder injuries in ALI-EC-T and ALI-EC were found. More PKH26-labeled type II alveolar epithelial cells were detected by fluorescence in the lungs of ALI-EC-T than in CON-EC-T as further verified by the expression of messenger RNA of sex-determining region of Y chromosome. Electromicroscopically intact type II alveolar epithelial cells and prominent lattice-like tubular myelin were also found in ALI-EC-T and CON-MV but not in ALI-EC. The hydroxyproline level in lung tissue was significantly lower in ALI-EC-T than in ALI-EC and ALI-MV, with most of the lung histopathologic and pathobiologic manifestations in favor of ALI-EC-T.

CONCLUSIONS

The preliminary data suggested that type II alveolar epithelial cell transplant facilitated lung reparation for ALI in this model.

Clausena anisata-mediated protection against lipopolysaccharide-induced acute lung injury in mice

Clausena anisata (Willd.) Hook.f. ex Benth. (CA), which is widely used in traditional medicine, reportedly exerts antitumor, anti-inflammatory and other important therapeutic effects. The aim of the present study was to investigate the potential therapeutic effects of CA in a mouse model of lipopolysaccharide (LPS)-induced acute lung injury (ALI) and in LPS-stimulated RAW 264.7 cells. Male C57BL/6 mice were administered treatments for 3 days by oral gavage. On day 3, the mice were instilled intranasally with LPS or PBS followed 3 h later by oral CA (30 mg/kg) or vehicle administration. In vitro, CA decreased nitric oxide (NO) production and pro-inflammatory cytokines, such as interleukin (IL)-6 and prostaglandin E2 (PGE2), in LPS-stimulated RAW 264.7 cells. CA also reduced the expression of pro-inflammatory mediators, such as cyclooxygenase-2. In vivo, CA administration significantly reduced inflammatory cell numbers in the bronchoalveolar lavage fluid (BALF) and suppressed pro-inflammatory cytokine levels, including tumor necrosis factor-α (TNF-α), IL-6, and IL-1β, as well as reactive oxygen species production in the BALF. CA also effectively reduced airway inflammation in mouse lung tissue of an LPS-induced ALI mouse model, in addition to decreasing inhibitor κB (IκB) and nuclear factor-κB (NF-κB) p65 phosphorylation. Taken together, the findings demonstrated that CA inhibited inflammatory responses in a mouse model of LPS-induced ALI and in LPS-stimulated RAW 264.7 cells. Thus, CA is a potential candidate for development as an adjunctive treatment for inflammatory disorders, such as ALI.

Febuxostat protects rats against lipopolysaccharide-induced lung inflammation in a dose-dependent manner

The aim of the present work was to investigate possible protective effects of febuxostat, a highly potent xanthine oxidase inhibitor, against acute lung injury (ALI) induced by lipopolysaccharide (LPS) in rats. Male Sprague Dawley rats were randomly divided into six groups, as follows: (i) vehicle control group; (ii) and (iii) febuxostat 10 and febuxostat 15 groups, drug-treated controls; (iv) LPS group, receiving an intraperitoneal injection of LPS (7.5 mg/kg); (v) and (vi) febuxostat 10-LPS and febuxostat 15-LPS groups, receiving oral treatment of febuxostat (10 and 15 mg/kg/day, respectively) for 7 days before LPS. After 18 h administration of LPS, blood was collected for C-reactive protein (CRP) measurement. Bronchoalveolar lavage fluid (BALF) was examined for leukocyte infiltration, lactate dehydrogenase (LDH) activity, protein content, and total nitrate/nitrite. Lung weight gain was determined, and lung tissue homogenate was prepared and evaluated for oxidative stress. Tumor necrosis factor-α (TNF-α) was assessed in BALF and lung homogenate. Moreover, histological changes of lung tissues were evaluated. LPS elicited lung injury characterized by increased lung water content (by 1.2 fold), leukocyte infiltration (by 13 fold), inflammation and oxidative stress (indicated by increased malondialdehyde (MDA), by 3.4 fold), and reduced superoxide dismutase (SOD) activity (by 34 %). Febuxostat dose-dependently decreased LPS-induced lung edema and elevations in BALF protein content, infiltration of leukocytes, and LDH activity. Moreover, the elevated levels of TNF-α in BALF and lung tissue of LPS-treated rats were attenuated by febuxostat pretreatment. Febuxostat also displayed a potent antioxidant activity by decreasing lung tissue levels of MDA and enhancing SOD activity. Histological analysis of lung tissue further demonstrated that febuxostat dose-dependently reversed LPS-induced histopathological changes. These findings demonstrate a significant dose-dependent protection by febuxostat against LPS-induced lung inflammation in rats.

C1P Attenuates Lipopolysaccharide-Induced Acute Lung Injury by Preventing NF-κB Activation in Neutrophils

Recently, ceramide-1-phosphate (C1P) has been shown to modulate acute inflammatory events. Acute lung injury (Arnalich et al. 2000. Infect. Immun. 68: 1942-1945) is characterized by rapid alveolar injury, lung inflammation, induced cytokine production, neutrophil accumulation, and vascular leakage leading to lung edema. The aim of this study was to investigate the role of C1P during LPS-induced acute lung injury in mice. To evaluate the effect of C1P, we used a prophylactic and therapeutic LPS-induced ALI model in C57BL/6 male mice. Our studies revealed that intrapulmonary application of C1P before (prophylactic) or 24 h after (therapeutic) LPS instillation decreased neutrophil trafficking to the lung, proinflammatory cytokine levels in bronchoalveolar lavage, and alveolar capillary leakage. Mechanistically, C1P inhibited the LPS-triggered NF-κB levels in lung tissue in vivo. In addition, ex vivo experiments revealed that C1P also attenuates LPS-induced NF-κB phosphorylation and IL-8 production in human neutrophils. These results indicate C1P playing a role in dampening LPS-induced acute lung inflammation and suggest that C1P could be a valuable candidate for treatment of ALI.

Impaired microcirculatory perfusion in a rat model of cardiopulmonary bypass: the role of hemodilution

Although hemodilution is attributed as the main cause of microcirculatory impairment during cardiopulmonary bypass (CPB), this relationship has never been investigated. We investigated the distinct effects of hemodilution with or without CPB on microvascular perfusion and subsequent renal tissue injury in a rat model. Male Wistar rats (375–425 g) were anesthetized, prepared for cremaster muscle intravital microscopy, and subjected to CPB ( n = 9), hemodilution alone ( n = 9), or a sham procedure ( n = 6). Microcirculatory recordings were performed at multiple time points and analyzed for perfusion characteristics. Kidney and lung tissue were investigated for mRNA expression for genes regulating inflammation and endothelial adhesion molecule expression. Renal injury was assessed with immunohistochemistry. Hematocrit levels dropped to 0.24 ± 0.03 l/l and 0.22 ± 0.02 l/l after onset of hemodilution with or without CPB. Microcirculatory perfusion remained unaltered in sham rats. Hemodilution alone induced a 13% decrease in perfused capillaries, after which recovery was observed. Onset of CPB reduced the perfused capillaries by 40% (9.2 ± 0.9 to 5.5 ± 1.5 perfused capillaries per microscope field; P < 0.001), and this reduction persisted throughout the experiment. Endothelial and inflammatory activation and renal histological injury were increased after CPB compared with hemodilution or sham procedure. Hemodilution leads to minor and transient disturbances in microcirculatory perfusion, which cannot fully explain impaired microcirculation following cardiopulmonary bypass. CPB led to increased renal injury and endothelial adhesion molecule expression in the kidney and lung compared with hemodilution. Our findings suggest that microcirculatory impairment during CPB may play a role in the development of kidney injury.

Gadolinium chloride modulates bradykinin-induced pulmonary vasoconstriction and hypoxic pulmonary vasoconstriction during polymicrobial abdominal sepsis in rats

BACKGROUND

Macrophages importantly contribute to sepsis-induced lung injury. As their impact on pulmonary endothelial injury and dysregulation of hypoxic pulmonary vasoconstriction (HPV) remains unclear, we assessed pulmonary endothelial dysfunction and HPV by macrophage inhibition via gadolinium chloride (GC) pre-treatment in rats with peritonitis (cecal ligation and puncture [CLP]).

METHODS

The following four study groups were made: Group I: SHAM and group II: SHAM + GC (pre-treatment with NaCl 0.9% or GC 14 mg/kg body weight (b.w.) intravenously 24 hours prior to sham laparotomy); group III: CLP and group IV: CLP + GC (pre-treatment with NaCl 0.9% or GC 14 mg/kg b.w. 24 hours prior to induction of peritonitis). Exhaled nitric oxide (exNO), bradykinin-induced pulmonary vasoconstriction (=surrogate marker of endothelial dysfunction) and HPV were investigated in isolated and perfused lungs (n = 40). Using the same protocol wet to dry lung weight ratio and myeloperoxidase (MPO) activity were investigated in separate rats (n = 28). In additional rats (n = 12) of groups III and IV nitrite levels in alveolar macrophages (AM) were measured.

RESULTS

In sepsis, GC pre-treatment significantly attenuated exNO levels, AM-derived nitrite levels, lung MPO activity, and restored blunted HPV, but severely enhanced endothelial dysfunction in healthy and septic animals.

CONCLUSION

Macrophages exhibit a controversial role in sepsis-induced lung injury. The GC-induced restoration of inflammation parameters to sham levels is clearly limited by the negative impact on CLP-induced endothelial injury in this setting. The exact link between the GC-associated modulation of the NO pathway demonstrated and septic lung injury needs to be determined in future studies.

Exogenous Glutamine in Respiratory Diseases: Myth or Reality?

Several respiratory diseases feature increased inflammatory response and catabolic activity, which are associated with glutamine depletion; thus, the benefits of exogenous glutamine administration have been evaluated in clinical trials and models of different respiratory diseases. Recent reviews and meta-analyses have focused on the effects and mechanisms of action of glutamine in a general population of critical care patients or in different models of injury. However, little information is available about the role of glutamine in respiratory diseases. The aim of the present review is to discuss the evidence of glutamine depletion in cystic fibrosis (CF), asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), and lung cancer, as well as the results of exogenous glutamine administration in experimental and clinical studies. Exogenous glutamine administration might be beneficial in ARDS, asthma, and during lung cancer treatment, thus representing a potential therapeutic tool in these conditions. Further experimental and large randomized clinical trials focusing on the development and progression of respiratory diseases are necessary to elucidate the effects and possible therapeutic role of glutamine in this setting.

Predictors of Outcomes in Traumatic Brain Injury

INTRODUCTION

The purpose of this study was to retrospectively evaluate patients treated for traumatic brain injuries (TBI) to determine how multiple organ trauma (MOT) and lung injuries sustained at the time of initial injury affect outcome.

METHODS

A single institution retrospective review of all patients diagnosed with TBI at a level I trauma center from 2000 to 2014 was conducted. Clinical outcome was based on Glasgow Outcome Scale at hospital discharge. Lung injury was defined as the presence of pulmonary contusions, pneumothorax, hemothorax, rib fractures, or diaphragmatic rupture proven by x-ray or computed tomography scan. MOT was defined as trauma to one body region with an Abbreviated Injury Scale (AIS) score ≥3 plus trauma to 2 additional body regions with AIS scores ≥1. Regression analysis was conducted with SPSS 21.

RESULTS

There were 409 patients reviewed. The majority of patients were male (73%), average age was 46 years (range, 16-94 years), average Glasgow Coma Scale (GCS) score was 7, and 71% had a severe TBI (GCS ≤8). Thirty percent of patients had poor outcome (Glasgow Outcome Scale = 1-2) Regression analysis indicated age (odds ratio [OR] 1.03, P < 0.001), initial GCS (OR 0.88, P < 0.001), Injury Severity Score (OR 1.03, P = 0.021), and head AIS ≥5 (OR 0.55, P = 0.019) were significant independent predictors of poor outcome. Sex, MOT, lung injury, and lung injury severity were not significant predictors of outcome.

CONCLUSIONS

Age, GCS, Injury Severity Score, and critical head injuries (AIS ≥5) were significant tools in predicting outcome in this patient cohort. MOT and traumatic lung injury may cause significant damage to a patient suffering from a severe TBI, but these injuries do not predict mortality in this patient population.

Protective effects of patchouli alcohol isolated from Pogostemon cablin on lipopolysaccharide-induced acute lung injury in mice

Patchouli alcohol (PA) is a tricyclic sesquiterpene isolated from Pogostemon cablin, which exerts anti-inflammatory, anti-influenza and cognitive-enhancing bioactivities. The present study aimed to investigate the protective effects of PA on acute lung injury (ALI) induced by intratracheal instillation of lipopolysaccharide (LPS) in mice. Dexamethasone was used as a positive drug for protection against LPS-induced ALI. The results of the present study demonstrated that pretreatment with PA significantly increased survival rate, attenuated histopathologic damage and lung edema, and decreased the protein content in the bronchoalveolar lavage fluid (BALF) of mice with ALI. Furthermore, PA significantly inhibited the expression levels of proinflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin (IL)-6 in the BALF, downregulated the levels of myeloperoxidase and malondialdehyde, and upregulated the activity levels of superoxide dismutase and glutathione peroxidase in lung tissue. These results indicated that PA may exert potent protective effects against LPS-induced ALI in mice, the mechanisms of which are possibly associated with the anti-inflammatory and antioxidative activities of PA.

Chronic Ethanol Exposure: Pathogenesis of Pulmonary Disease and Dysfunction

Ethanol (EtOH) is the world’s most commonly used drug, and has been widely recognized as a risk factor for developing lung disorders. Chronic EtOH exposure affects all of the organ systems in the body and increases the risk of developing pulmonary diseases such as acute lung injury and pneumonia, while exacerbating the symptoms and resulting in increased mortality in many other lung disorders. EtOH and its metabolites inhibit the immune response of alveolar macrophages (AMs), increase airway leakage, produce damaging reactive oxygen species (ROS), and disrupt the balance of antioxidants/oxidants within the lungs. In this article, we review the role of EtOH exposure in the pathogenesis and progression of pulmonary disease.

The Immunomodulatory and Therapeutic Effects of Mesenchymal Stromal Cells for Acute Lung Injury and Sepsis

It is increasingly recognized that immunomodulation represents an important mechanism underlying the benefits of many stem cell therapies, rather than the classical paradigm of transdifferentiation and cell replacement. In the former paradigm, the beneficial effects of cell therapy result from paracrine mechanism(s) and/or cell-cell interaction as opposed to direct engraftment and repair of diseased tissue and/or dysfunctional organs. Depending on the cell type used, components of the secretome, including microRNA (miRNA) and extracellular vesicles, may be able to either activate or suppress the immune system even without direct immune cell contact. Mesenchymal stromal cells (MSCs), also referred to as mesenchymal stem cells, are found not only in the bone marrow, but also in a wide variety of organs and tissues. In addition to any direct stem cell activities, MSCs were the first stem cells recognized to modulate immune response, and therefore they will be the focus of this review. Specifically, MSCs appear to be able to effectively attenuate acute and protracted inflammation via interactions with components of both innate and adaptive immune systems. To date, this capacity has been exploited in a large number of preclinical studies and MSC immunomodulatory therapy has been attempted with various degrees of success in a relatively large number of clinical trials. Here, we will explore the various mechanism employed by MSCs to effect immunosuppression as well as review the current status of its use to treat excessive inflammation in the context of acute lung injury (ALI) and sepsis in both preclinical and clinical settings.

Lipid emulsions for parenteral nutrition in critical illness

Critical illness is a life-threatening multisystem process that can result in significant morbidity and mortality. In most patients, critical illness is preceded by a physiological deterioration, characterized by a catabolic state and intense metabolic changes, resulting in malnutrition and impaired immune functions. In this context, parenteral lipid emulsions may modulate inflammatory and immune reactions, depending on their fatty acid composition. These effects appear to be based on complex modifications in the composition and structure of cell membranes, through eicosanoid and cytokine synthesis and by modulation of gene expression. The pathophysiological mechanisms underlying these fatty acid-induced immune function alterations in critical ill patients are however complex and partially understood. Indeed, despite a very abundant literature, experimental and clinical data remain contradictory. The optimization of lipid emulsion composition thus represents a major challenge for clinical medicine, to adequately modulate the inflammatory pathways. In the present review, we first address the metabolic response to aggression, the effects of parenteral lipid emulsions on inflammation and immunity, and finally the controversial place of these lipid emulsions during critical illness. The analysis furthermore highlights the pathophysiological mechanisms underlying the differential effects of lipid emulsions and their potential for improving the handling of critically ill patients.

Acanthopanax trifoliatus inhibits lipopolysaccharide-induced inflammatory response in vitro and in vivo

Acanthopanax trifoliatus is a well-known herb that is used for the treatment of bruising, neuralgia, impotence, and gout in Taiwan. This herb exhibits multifunctional activities, including anticancer, anti-inflammation, and antioxidant effects. This paper investigated the in vitro and in vivo anti-inflammatory effect of A. trifoliatus. High-performance liquid chromatography analysis established the fingerprint chromatogram of the ethyl acetate fraction of A. trifoliatus (EAAT). The anti-inflammatory effect of EAAT was detected using lipopolysaccharide (LPS) stimulation of the mouse macrophage cell line RAW264.7 in vitro and LPS-induced lung injury in vivo. The effects of EAAT on LPS-induced production of inflammatory mediators in RAW264.7 murine macrophages and the mouse model were measured using enzyme-linked immunosorbent assay and Western blot. EAAT attenuated the production of LPS-induced nitric oxide (NO), tumor necrosis factor-alpha, interleukin-1β (IL-1β), and IL-6 in vitro and in vivo. Pretreatment with EAAT markedly reduced LPS-induced histological alterations in lung tissues. Furthermore, EAAT significantly reduced the number of total cells and protein concentration levels in the bronchoalveolar lavage fluid. Western blotting test results revealed that EAAT blocked protein expression of inducible NO synthase, cyclooxygenase-2, phosphorylation of Nuclear factor-kappa-B Inhibitor alpha (IκB-α) protein, and mitogen-activated protein kinases in LPS-stimulated RAW264.7 cells as well as LPS-induced lung injury. This study suggests that A. trifoliatus may be a potential therapeutic candidate for the treatment of inflammatory diseases.

Resolvins Decrease Oxidative Stress Mediated Macrophage and Epithelial Cell Interaction through Decreased Cytokine Secretion

Background

Inflammation is a key hallmark of ALI and is mediated through ungoverned cytokine signaling. One such cytokine, interleukin-1beta (IL-1β) has been demonstrated to be the most bioactive cytokine in ALI patients. Macrophages are the key players responsible for IL-1β secretion into the alveolar space. Following the binding of IL-1β to its receptor, “activated” alveolar epithelial cells show enhanced barrier dysfunction, adhesion molecule expression, cytokine secretion, and leukocyte attachment. More importantly, it is an important communication molecule between the macrophage and alveolar epithelium. While the molecular determinants of this inflammatory event have been well documented, endogenous resolution processes that decrease IL-1β secretion and resolve alveolar epithelial cell activation and tissue inflammation have not been well characterized. Lipid mediator Aspirin-Triggered Resolvin D1 (AT-RvD1) has demonstrated potent pro-resolutionary effects in vivo models of lung injury; however, the contribution of the alveoli to the protective benefits of this molecule has not been well documented. In this study, we demonstrate that AT-RvD1 treatment lead to a significant decrease in oxidant induced macrophage IL-1β secretion and production, IL-1β-mediated cytokine secretion, adhesion molecule expression, leukocyte adhesion and inflammatory signaling.

Methods

THP-1 macrophages were treated with hydrogen peroxide and extracellular ATP in the presence or absence of AT-RvD1 (1000–0.1 nM). A549 alveolar-like epithelial cells were treated with IL-1β (10 ng/mL) in the presence or absence of AT-RvD1 (0.1 μM). Following treatment, cell lysate and cell culture supernatants were collected for Western blot, qPCR and ELISA analysis of pro-inflammatory molecules. Functional consequences of IL-1β induced alveolar epithelial cell and macrophage activation were also measured following treatment with IL-1β ± AT-RvD1.

Results

Results demonstrate that macrophages exposed to H₂O₂ and ATP in the presence of resolvins show decreased IL-1β production and activity. A549 cells treated with IL-1β in the presence of AT-RvD1 show a reduced level of proinflammatory cytokines IL-6 and IL-8. Further, IL-1β-mediated adhesion molecule expression was also reduced with AT-RvD1 treatment, which was correlated with decreased leukocyte adhesion. AT-RvD1 treatment demonstrated reduced MAP-Kinase signaling. Taken together, our results demonstrate AT-RvD1 treatment reduced IL-1β-mediated alveolar epithelial cell activation. This is a key step in unraveling the protective effects of resolvins, especially AT-RvD1, during injury.

SH2 domain-containing protein tyrosine phosphatase 2 and focal adhesion kinase protein interactions regulate pulmonary endothelium barrier function

Enhanced protein tyrosine phosphorylation is associated with changes in vascular permeability through formation and dissolution of adherens junctions and regulation of stress fiber formation. Inhibition of the protein tyrosine phosphorylase SH2 domain-containing protein tyrosine phosphatase 2 (SHP2) increases tyrosine phosphorylation of vascular endothelial cadherin and β-catenin, resulting in disruption of the endothelial monolayer and edema formation in the pulmonary endothelium. Vascular permeability is a hallmark of acute lung injury (ALI); thus, enhanced SHP2 activity offers potential therapeutic value for the pulmonary vasculature in diseases such as ALI, but this has not been characterized. To assess whether SHP2 activity mediates protection against edema in the endothelium, we assessed the effect of molecular activation of SHP2 on lung endothelial barrier function in response to the edemagenic agents LPS and thrombin. Both LPS and thrombin reduced SHP2 activity, correlated with decreased focal adhesion kinase (FAK) phosphorylation (Y(397) and Y(925)) and diminished SHP2 protein-protein associations with FAK. Overexpression of constitutively active SHP2 (SHP2(D61A)) enhanced baseline endothelial monolayer resistance and completely blocked LPS- and thrombin-induced permeability in vitro and significantly blunted pulmonary edema formation induced by either endotoxin (LPS) or Pseudomonas aeruginosa exposure in vivo. Chemical inhibition of FAK decreased SHP2 protein-protein interactions with FAK concomitant with increased permeability; however, overexpression of SHP2(D61A) rescued the endothelium and maintained FAK activity and FAK-SHP2 protein interactions. Our data suggest that SHP2 activation offers the pulmonary endothelium protection against barrier permeability mediators downstream of the FAK signaling pathway. We postulate that further studies into the promotion of SHP2 activation in the pulmonary endothelium may offer a therapeutic approach for patients suffering from ALI.

Carnosine markedly ameliorates H9N2 swine influenza virus-induced acute lung injury

Oxidative stress injury is an important pathogenesis of influenza virus in critically ill patients. The present study investigated the efficacy of carnosine, an antioxidant and free radical scavenger, on a model of acute lung injury (ALI) induced by H9N2 swine influenza virus. Female specific-pathogen-free BALB/c mice were randomized into four groups and treated as follows: (1) H9N2 group, (2) mock control group, (3) H9N2+carnosine group and (4) carnosine control group. The H9N2 group mice were inoculated intranasally with A/Swine/Hebei/012/2008/ (H9N2) virus (100 μl) in allantoic fluid (AF), whilst mock-infected animals were intranasally inoculated with non-infectious AF. Carnosine [10 mg (kg body mass)- 1] was administered orally (100 μl) for 7 days consecutively. The survival rate, lung water content, TNF-α and IL-1β levels, lung histopathology, myeloperoxidase (MPO) activity, and Toll-like receptor (TLR)-4 levels were determined at 2, 4, 6, 8 and 14 days after inoculation. Carnosine treatment effectively decreased the mortality (43 versus 75 %, P < 0.05), significantly ameliorated pathological lesions in lungs and decreased the lung wet/dry mass ratio (P < 0.05). It also inhibited MPO activity, suppressed TNF-α and IL-1β release, decreased the H9N2 viral titre, and markedly inhibited levels of TLR-4 mRNA and protein in the lungs of infected mice (P < 0.05), which supported the use of carnosine for managing severe influenza cases.

FG-4497: a new target for acute respiratory distress syndrome?

The morbidity and mortality rates associated with acute respiratory distress syndrome (ARDS) remain high and the development of new therapeutic strategies is urgently required. Some pharmacological treatments, proposed or under evaluation for ARDS, seek to protect the endothelium and consequently mitigate fluid extravasation into the alveolar space. FG-4497 is a new compound which acts as a prolyl hydroxylase domain 2 inhibitor and mimics hypoxia in the activation of hypoxia-inducible factor-2α signaling, decreasing VE-cadherin phosphorylation and thus promoting integrity of adherens junctions. In this special report, we discuss the pharmacological characteristics of FG-4497, its effect on lung parenchyma and other organs and future perspectives in ARDS. In short, FG-4497 may be considered a novel pharmacological option targeting endothelial cell repair in lung diseases such as ARDS. Further experimental and clinical studies are warranted to better understand the mechanisms of action of FG-4497 in different types of lung injury.

Pretreatment with andrographolide pills(®) attenuates lipopolysaccharide-induced pulmonary microcirculatory disturbance and acute lung injury in rats

OBJECTIVE

The purpose of this study was to explore the protective effect of AP on LPS-induced PMD and ALI.

METHODS

Male SD rats were continuously infused with LPS (5 mg/kg/h) for one hour to induce PMD and ALI. AP was administrated orally one hour before LPS exposure. Arterial blood pressure and HR were monitored. Blood gas analysis, histological observation, cytokines in plasma, leukocyte recruitment, pulmonary oxidative stress, microvessel permeability, edema, and related proteins were evaluated six hours after LPS challenge.

RESULTS

Rats receiving LPS exhibited significant alterations, including hypotension, tachycardia, increase in cytokines, neutrophil adhesion and infiltration, oxidative stress, and microvessel hyperpermeability, resulting in pulmonary injury and dysfunction. AP (0.18 g/kg or 1.8 g/kg) improved rat survival rate, and significantly attenuated all aforementioned insults, and inhibited LPS-induced increase in adhesion molecules, up-regulation of Cav-1 and Src kinase and NADPH oxidase subunits (p47(phox) and p67(phox) ) membrane translocation in lung tissue, and preserved JAM-1 and claudin-5.

CONCLUSIONS

The results demonstrated the protective effect of AP on LPS-induced PMD and ALI, suggesting the potential of AP as a prophylactic strategy for LPS-induced ALI.

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.

Remifentanil attenuates lipopolysaccharide-induced acute lung injury by downregulating the NF-κB signaling pathway

Remifentanil significantly represses cell immune responses and influences neutrophil migration through endothelial cell monolayers. The present study determines the beneficial effects of remifentanil and the mechanisms by which it attenuates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Rats were intratracheally instilled with 2 mg/kg LPS to induce ALI. Results showed that remifentanil could resolve lung injury, as evidenced by remarkable decreases in lung edema (wet-to-dry weight ratio), neutrophil infiltration (myeloperoxidase activity), and pulmonary permeability [total number of cells and protein concentrations in bronchoalveolar lavage fluid (BALF)]. Remifentanil also attenuated the concentrations of proinflammatory cytokines tumor necrosis factor alpha, interleukin-1β, and interleukin-6 in BALF, as well as effectively repressed the activation of nuclear factor-kappaB (NF-κB), which has been associated with the inhibition of IκBα degradation.These results suggest that remifentanil may be a suitable treatment for LPS-induced ALI. Remifentanil exerts beneficial effects on the inhibition of proinflammatory cytokine production by downregulating the NF-κB pathway.