Lipopolysaccharide-induced Lung Injury Model Research Articles

Analyzing small RNA sequences from canine stem cell-derived extracellular vesicles primed with TNF-α and IFN-γ and exploring their potential in lung repair.

Acute lung injury is an acute inflammation disorder that disrupts the lung endothelial and epithelial barriers. In this study, we investigated the extracellular vesicles (EVs) obtained via priming inflammatory cytokines such as tumor necrosis factor (TNF)-α and interferon (IFN)-γ on canine adipose mesenchymal stem cells in improving their anti-inflammatory and/or immunosuppressive potential, and/or their ability to alleviate lipopolysaccharide-induced lung injury in vitro. We also explored the correlation between epithelial-to-mesenchymal transition and the inflammatory repressive effect of primed EVs. Using small RNA-Seq, we confirmed that miR-16 and miR-502 significantly increased in EVs from TNF-α and IFN-γ-primed canine adipose mesenchymal stem cells. The pro and anti-inflammatory cytokines were analyzed in a lipopolysaccharide-induced lung injury model and we found that the EV anti-inflammatory effect improved on priming with inflammatory cytokines. EVs obtained from primed stem cells effectively suppress endothelial-to-mesenchymal transition in a lung injury model. Our results suggest a potential therapeutic approach utilizing EVs obtained from adipose mesenchymal stem cells primed with TNF-α and IFN-γ against lung inflammation and endothelial to mesenchymal transition.

The Interplay between Aquaporin-1 and the Hypoxia-Inducible Factor 1α in a Lipopolysaccharide-Induced Lung Injury Model in Human Pulmonary Microvascular Endothelial Cells.

Aquaporin-1 (AQP1), a water channel, and the hypoxia-inducible factor 1α (HIF1A) are implicated in acute lung injury responses, modulating among others pulmonary vascular leakage. We hypothesized that the AQP1 and HIF1A systems interact, affecting mRNA, protein levels and function of AQP1 in human pulmonary microvascular endothelial cells (HPMECs) exposed to lipopolysaccharide (LPS). Moreover, the role of AQP1 in apoptosis and wound healing progression was examined. Both AQP1 mRNA and protein expression levels were higher in HPMECs exposed to LPS compared to untreated HPMECs. However, in the LPS-exposed HIF1A-silenced cells, the mRNA and protein expression levels of AQP1 remained unaltered. In the permeability experiments, a statistically significant volume increase was observed at the 360 s time-point in the LPS-exposed HPMECs, while LPS-exposed HIF1A-silenced HPMECs did not exhibit cell swelling, implying a dysfunctional AQP1. AQP1 did not seem to affect cell apoptosis yet could interfere with endothelial migration and/or proliferation. Based on our results, it seems that HIF1A silencing negatively affects AQP1 mRNA and protein expression, as well as AQP1 function, in the setting of lung injury.

Comparison of pulmonary availability and anti-inflammatory effect of dehydroandrographolide succinate via intratracheal and intravenous administration

Dehydroandrographolide succinate (DAS) injection, which was approved in China for the treatment of viral pneumonia and upper respiratory tract infections, is often off-label used for nebulization therapy to avoid the adverse drug reactions associated with the injection. However, the aerodynamic properties and pulmonary fate of nebulized DAS was largely uninvestigated. In this study, the main objectives were to evaluate the in vitro aerodynamic deposition profiles of nebulizer generated aerosols and comparatively investigate the local drug availability and anti-inflammatory efficacy of DAS between intratracheal and intravenous dosing. The in vitro evaluation of aerodynamic characteristics and droplet size distribution showed more than 50% aerosol particles with size being <5 μm, allowing the aerosols to reach the lower respiratory tract. Following intratracheal administration, the drug underwent pulmonary absorption into the bloodstream, rendering an absolute bioavailability of 47.3%. Compared to the intravenous delivery, the intratracheal administration dramatically increased the drug availability in the lung tissue in rats by more than 80-fold, leading to an improved and prolonged local anti-inflammatory efficacy in a lipopolysaccharide induced lung injury model in mice. The present results demonstrated that inhalation delivery of DAS is a convenient and effective alternative to intravenous injections.

Myricetin attenuates LPS-induced inflammation in RAW 264.7 macrophages and mouse models.

Acute lung injury is a common clinical syndrome associated with significant morbidity. Myricetin has been demonstrated to inhibit inflammation in a variety of diseases. In this study, we aimed to investigate the protective effects of myricetin on inflammation in lipopolysaccharide-stimulated RAW 264.7 cells and lipopolysaccharide-induced lung injury model. Results/methodology: In this study, we detected the anti-inflammatory effects of myricetin by ELISA, RT-PCR and Western blot, respectively. Myricetin significantly inhibited the production of the proinflammatory cytokines in vitro and in vivo. It exerted an anti-inflammatory effect through suppressing the NF-κB p65 and AKT activation in NF-κB pathway and JNK, p-ERK and p38 in MAPK signaling pathway. Myricetin alleviated acute lung injury by inhibiting macrophage activation, and inhibited inflammation in vitro and in vivo. It may be a potential therapeutic candidate for the prevention of inflammatory diseases.

Ciclesonide and budesonide suspensions for nebulization delivery: An in vivo inhalation biopharmaceutics investigation

The pulmonary fate of inhaled poorly water-soluble drugs is not entirely clear. In this study, the main objective was to investigate the in vivo inhalation biopharmaceutics in the aspects of dissolution, mucociliary clearance, absorption and tissue binding using intratracheally administered budesonide and ciclesonide suspensions as model drugs. In doing so, this study first developed a method to differentiate between dissolved and undissolved ciclesonide in the lungs for evaluating in vivo dissolution. Following deposited in rat airways, the drug particles underwent rapid dissolution and mucociliary clearance, leading to the complete removal of drugs from the airways within 2 h and a limited absorption time less than 2 h. Upon dissolution, budesonide and ciclesonide were taken up and retained in the lung tissues for up to 12 h and 24 h, respectively. The in vivo dissolution profiles in the airways exhibited the sameness as the in vitro counterparts in a 0.5% sodium dodecyl sulfate solution as indicated by the similarity factor f2. The efficacy results in a lipopolysaccharide induced lung injury model showed that the duration of local anti-inflammatory was dependent on the drug levels in the lung tissues, but not on the in vitro/in vivo dissolution and plasma pharmacokinetics. The present results demonstrated that ciclesonide suspension has the potential to achieve once-daily dosing for nebulization therapy and the in vitro dissolution profile has limited usefulness in predicting in vitro–in vivo correlation.

Isoflurane promotes phagocytosis of apoptotic neutrophils through AMPK-mediated ADAM17/Mer signaling.

A patient’s recovery from lung inflammatory injury or development of multi-system organ failure is determined by the host’s ability to resolve inflammation and repair tissue damage, both of which require the clearance of apoptotic neutrophils by macrophages (efferocytosis). Here, we investigated the effects of isoflurane on macrophage efferocytosis and resolution of lung inflammatory injury. Treatment of murine bone marrow-derived macrophages (BMDMs) or alveolar macrophages with isoflurane dramatically enhanced phagocytosis of apoptotic neutrophils. Isoflurane significantly increased the surface expression of the receptor tyrosine kinase Mer in macrophages, but markedly decreased the levels of a soluble form of Mer protein in the medium. Isoflurane treatment also caused a decrease in a disintegrin and metalloproteinase 17 (ADAM17) on the cell surface and a concomitant increase in its cytoplasmic fraction. These responses induced by isoflurane were completely reversed by a pharmacological inhibitor or genetic deletion of AMP-activated protein kinase (AMPK). In a mouse model of lipopolysaccharide-induced lung injury, isoflurane accelerated the recovery of lung inflammation and injury that was coupled with an increase in the number of alveolar macrophages containing apoptotic bodies. In alveolar macrophage-depleted mice, administration of isoflurane-pretreated BMDMs facilitated resolution of lung inflammation following lipopolysaccharide challenge. Thus, isoflurane promoted resolution of lipopolysaccharide-induced lung inflammatory injury via enhancement of macrophage efferocytosis. Increased macrophage efferocytosis following isoflurane treatment correlates with upregulation of Mer surface expression through AMPK-mediated blockade of ADAM17 trafficking to the cell membrane.

Anti-Inflammatory Effects of OxPAPC Involve Endothelial Cell-Mediated Generation of LXA4.

Oxidation of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC) generates a group of bioactive oxidized phospholipid products with a broad range of biological activities. Barrier-enhancing and anti-inflammatory effects of OxPAPC on pulmonary endothelial cells are critical for prevention of acute lung injury caused by bacterial pathogens or excessive mechanical ventilation. Anti-inflammatory properties of OxPAPC are associated with its antagonistic effects on Toll-like receptors and suppression of RhoA GTPase signaling. Because OxPAPC exhibits long-lasting anti-inflammatory and lung-protective effects even after single administration in vivo, we tested the hypothesis that these effects may be mediated by additional mechanisms, such as OxPAPC-dependent production of anti-inflammatory and proresolving lipid mediator, lipoxin A4 (LXA4). Mass spectrometry and ELISA assays detected significant accumulation of LXA4 in the lungs of OxPAPC-treated mice and in conditioned medium of OxPAPC-exposed pulmonary endothelial cells. Administration of LXA4 reproduced anti-inflammatory effect of OxPAPC against tumor necrosis factor-α in vitro and in the animal model of lipopolysaccharide-induced lung injury. The potent barrier-protective and anti-inflammatory effects of OxPAPC against tumor necrosis factor-α and lipopolysaccharide challenge were suppressed in human pulmonary endothelial cells with small interfering RNA-induced knockdown of LXA4 formyl peptide receptor-2 (FPR2/ALX) and in mFPR2-/- (mouse formyl peptide receptor 2) mice lacking the mouse homolog of human FPR2/ALX. This is the first demonstration that inflammation- and injury-associated phospholipid oxidation triggers production of anti-inflammatory and proresolution molecules, such as LXA4. This lipid mediator switch represents a novel mechanism of OxPAPC-assisted recovery of inflamed lung endothelium.

Soluble form of the receptor for advanced glycation end-products attenuates inflammatory pathogenesis in a rat model of lipopolysaccharide-induced lung injury

Acute respiratory distress syndrome (ARDS) is a severe respiratory failure caused by acute lung inflammation. Recently, the receptor for advanced glycation end-products (RAGE) has attracted attention in the lung inflammatory response. However, the function of soluble form of RAGE (sRAGE), which is composed of an extracellular domain of RAGE, in ARDS remains elusive. Therefore, we investigated the dynamics of pulmonary sRAGE and the effects of exogenous recombinant human sRAGE (rsRAGE) under intratracheal lipopolysaccharide (LPS)-induced lung inflammation. Our result revealed that RAGE was highly expressed on the alveolar type I epithelial cells in the healthy rat lung including sRAGE isoform sized 45 kDa. Under LPS-induced injured lung, the release of sRAGE into the alveolar space was increased, whereas the expression of RAGE was decreased with alveolar disruption. Treatment of the injured lung with rsRAGE significantly suppressed the lung edema, the neutrophils infiltration, the release of high mobility group box-1 (HMGB1), and the expressions of TNF-α, IL-1β and iNOS. These results suggest that the alveolar release of sRAGE may play a protective role against HMGB1 as well as exogenous pathogen-associated molecular patterns. Supplementary therapy with sRAGE may be an effective therapeutic strategy for ARDS.

Anti-inflammatory effects of methanol extract of Canarium lyi C.D. Dai & Yakovlev in RAW 264.7 macrophages and a murine model of lipopolysaccharide-induced lung injury.

Canarium lyi C.D. Dai & Yakovlev (CL) is a member of the Anacardiaceae family. To the best of our knowledge, no studies on its anti-inflammatory effects have yet been reported. In the present study, we investigated the protective effects of CL on inflammation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and LPS-induced acute lung injury (ALI) mice. CL attenuated the production of LPS-stimulated inflammatory mediators such as tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and interleukin-6 (IL-6). Furthermore, CL suppressed phosphorylation of the inhibitor κB-α (IκB-α), p38, c-Jun terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), as well as the translocation of the nuclear factor-κB (NF-κB) p65 subunit into the nucleus. For the in vivo efficacy, the effect of CL on a mouse model of LPS-induced acute lung injury was assessed. CL treatment of the mice significantly inhibited the inflammatory cell recruitment and pro-inflammatory cytokine production in bronchoalveolar lavage fluids (BALF). CL-treated mice also showed a marked inhibition of cyclooxygenase-2 (COX-2) and phosphorylation of IκB and p65. In addition, CL attenuated lung histopathological changes in LPS-induced ALI mice. In conclusion, our results suggest that CL is a potential therapeutic candidate for the treatment of inflammatory diseases, including pneumonia.

Linalool: a novel natural anti-inflammatory agent?: Commentary on “Anti-inflammatory effects of linalool in RAW 264.7 macrophages and lipopolysaccharide-induced lung injury model”

DOI of original article: 10.1016/j.jss.2012.1 * Corresponding author. Department of Surg Tel.: þ1 513 558 8467; fax: þ1 513 558 3474. E-mail address: prittsta@ucmail.uc.edu (T 0022-4804/$ e see front matter a 2013 Elsev http://dx.doi.org/10.1016/j.jss.2013.02.014 Proinflammatory states are widely implicated in both acute and chronic disease processes. Severe acute systemic inflammation is at least partially responsible for shock and acute lung injury, and therapeutic options to curb the proinflammatory responses are limited. Sustained release of proinflammatory mediators by macrophages and other leukocyte subtypes is the hallmark of autoimmune illnesses. In addition to nonspecific immunosuppressants, targeted therapies to reduce inflammation via inhibition of cytokine release are available for some of these illnesses, including Crohn disease and rheumatoid arthritis. However, the subsequent risk of infection with these medications is significant, which limits their clinical use. Linalool is a terpene alcohol that occurs naturally in several edible plant species. It is used in soaps, oils, and other topical products, but has not been evaluated previously as a therapeutic. Its role as an inflammatory mediator is unknown. Based on the antimicrobial and anxiolytic properties of

Anti-inflammatory effects of linalool in RAW 264.7 macrophages and lipopolysaccharide-induced lung injury model

BackgroundInflammation, characterized by redness, swelling, pain and a sensation of heat, is one of the body’s self-defense systems. Although the inflammation response has an important role in host survival, it also leads to chronic inflammatory diseases. Linalool is a natural compound of the essential oils in several aromatic plants species. It possesses anti-inflammatory, antinociceptive, and other bioactive properties. In the present study, we investigated the protective effects of linalool on inflammation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and an LPS-induced in vivo lung injury model. MethodsWe evaluated the effects of linalool on LPS-induced production of inflammatory mediators in Raw 264.7 murine macrophages by enzyme-linked immunosorbent assay and Western blot. To confirm the anti-inflammatory activity of linalool in vivo, we induced an acute lung injury in an LPS-induced mouse model. ResultsLinalool attenuated the production of LPS-induced tumor necrosis-α and interleukin-6 both in vitro and in vivo. Furthermore, phosphorylation of IκBα protein, p38, c-Jun terminal kinase, and extracellular signal-regulated kinase in LPS-stimulated RAW 264.7 cells was blocked by linalool. Our in vivo study also found that linalool attenuated lung histopathologic changes in mouse models. ConclusionsThe results suggest that linalool inhibits inflammation both in vitro and in vivo, and may be a potential therapeutic candidate for the treatment of inflammatory diseases.

Geniposide, from Gardenia jasminoides Ellis, inhibits the inflammatory response in the primary mouse macrophages and mouse models

Geniposide, a main iridoid glucoside component of gardenia fruit, has been known to exhibit antibacterial, anti-inflammatory and other important therapeutic activities. The objective of this study was to investigate the protective effects of geniposide on inflammation in lipopolysaccharide (LPS) stimulated primary mouse macrophages in vitro and LPS induced lung injury model in vivo. The expression of pro-inflammatory cytokines was determined by enzyme-linked immunosorbent assay (ELISA). Nuclear factor-kappa B (NF-κB), inhibitory kappa B (IκBα) protein, p38, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and Toll-like receptor 4 (TLR4) were determined by Western blot. Further analysis was carried out in mTLR4 and mMD-2 co-transfected HEK293 cells. The results showed that geniposide markedly inhibited the LPS-induced TNF-α, IL-6 and IL-1β production both in vitro and in vivo. Geniposide blocked the phosphorylation of IκBα, p65, p38, ERK and JNK in LPS stimulated primary mouse macrophages. Furthermore, geniposide inhibited the expression of TLR4 in LPS stimulated primary mouse macrophages and inhibited the LPS-induced IL-8 production in HEK293-mTLR4/MD-2 cells. In vivo study, it was also observed that geniposide attenuated lung histopathologic changes in the mouse models. These results suggest that geniposide exerts an anti-inflammatory property by down-regulating the expression of TLR4 up-regulated by LPS. Geniposide is highly effective in inhibiting acute lung injury and may be a promising potential therapeutic reagent for acute lung injury treatment.

Dobutamine Enhances Alveolar Fluid Clearance in a Rat Model of Acute Lung Injury

Acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome (ARDS), remain leading factors for morbidity and mortality in critically ill patients. A significant aspect of ALI and ARDS is impaired alveolar fluid clearance (AFC). Improvements in therapies for these types of respiratory illnesses will require an understanding of the mechanisms that control AFC. The present study was designed to determine whether the administration of dobutamine decreases pulmonary edema and stimulates AFC in a rat model of lipopolysaccharide-induced lung injury. Adult male Sprague-Dawley rats were randomly divided into three groups: control, lipopolysaccharide, and lipopolysaccharide + dobutamine. The effect of dobutamine on AFC and the expression of aquaporin-1 and aquaporin-5 were examined. Lipopolysaccharide administration results in significant lung injury with impaired AFC, while dobutamine improves alveolar fluid reabsorption with elevation of aquaporin-1 and aquaporin-5. Our study indicates that dobutamine may enhance alveolar fluid reabsorption by increasing the expression of aquaporin-1 and aquaporin-5.

Oxidized phospholipids reduce ventilator-induced vascular leak and inflammation in vivo

BackgroundMechanical ventilation at high tidal volume (HTV) may cause pulmonary capillary leakage and acute lung inflammation resulting in ventilator-induced lung injury. Besides blunting the Toll-like receptor-4-induced inflammatory cascade and lung dysfunction in a model of lipopolysaccharide-induced lung injury, oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC) exerts direct barrier-protective effects on pulmonary endothelial cells in vitro via activation of the small GTPases Rac and Cdc42. To test the hypothesis that OxPAPC may attenuate lung inflammation and barrier disruption caused by pathologic lung distension, we used a rodent model of ventilator-induced lung injury and an in vitro model of pulmonary endothelial cells exposed to pathologic mechanochemical stimulation.MethodsRats received a single intravenous injection of OxPAPC (1.5 mg/kg) followed by mechanical ventilation at low tidal volume (LTV) (7 mL/kg) or HTV (20 mL/kg). Bronchoalveolar lavage was performed and lung tissue was stained for histological analysis. In vitro, the effects of OxPAPC on endothelial barrier dysfunction and GTPase activation were assessed in cells exposed to thrombin and pathologic (18%) cyclic stretch.ResultsHTV induced profound increases in bronchoalveolar lavage and tissue neutrophils and in lavage protein. Intravenous OxPAPC markedly attenuated HTV-induced protein and inflammatory cell accumulation in bronchoalveolar lavage fluid and lung tissue. In vitro, high-magnitude stretch enhanced thrombin-induced endothelial paracellular gap formation associated with Rho activation. These effects were dramatically attenuated by OxPAPC and were associated with OxPAPC-induced activation of Rac.ConclusionOxPAPC exhibits protective effects in these models of ventilator-induced lung injury.