Model Of Acute Lung Inflammation Research Articles

Inhalable Solubilized Zileuton for Improved Lung Targeting in vitro and in vivo Analysis

Abstract: Background: Pulmonary diseases that affect the normal functioning of the lungs show airway symptoms ranging from change in airflow to bronchiectasis. Zileuton is an inhibitor of 5-lipoxygenase enzyme that catalyzes the synthesis of leukotrienes. Zileuton is used in the management of inflammatory conditions of the upper airways like obstructive pulmonary conditions and acute lung inflammation. Although a promising therapeutic, zileuton is poorly water-soluble and requires frequent administration to overcome bioavailability issues and maintain therapeutic levels that often lead to adverse reactions, especially to the non-targeted organs. Materials and Methods: Therefore, we designed a rapidly nanoemulsifying formulation of zileuton using Acrysol K150 as an oil, Cremophor EL as a surfactant, and Transcutol HP as a cosolvent. Results: This self-emulsifying composition exhibited showed a mean globule size of 133 ± 3.6 nm with a polydispersity index of 0.38. Scanning electron microscopy (SEM) images revealed the spherical shape of emulsion globules. In vitro lung deposition showed >80% delivery to the deep lung tissue. Mass median aerodynamic diameter of 2.05±0.98 μm for the aerosolized formulation. In vivo, pharmacokinetic studies in Wistar rats by inhalation route showed that the zileuton-loaded nanoemulsifying formulation had a significantly higher concentration in the lung compared to other non-target organs. The in vivo efficacy in the lipopolysaccharide-induced acute lung inflammation model in rats significantly impeded the protein accumulation and neutrophil infiltration in the lungs. Conclusion: The zileuton-loaded nanoemulsifying inhalable formulation successfully improved the therapeutic efficacy of zileuton specifically to the lung thereby minimizing the off-target organ side effects. Keywords: Self-emulsifying, Zileuton, Aerosols, Pharmacodynamics, in vivo, Lung targeting.

Modulation of low-dose ozone and LPS exposed acute mouse lung inflammation by IF1 mediated ATP hydrolysis inhibitor, BTB06584.

Ozone and bacterial lipopolysaccharide (LPS) are common air pollutants that are related to high hospital admissions due to airway hyperreactivity and increased susceptibility to infections, especially in children, older population and individuals with underlying conditions. We modeled acute lung inflammation (ALI) by exposing 6-8 week old male mice to 0.005 ppm ozone for 2h followed by 50 μg of intranasal LPS. We compared the immunomodulatory effects of single dose pre-treatment with CD61 blocking antibody (clone 2C9.G2), ATPase inhibitor BTB06584 against propranolol as the immune-stimulant and dexamethasone as the immune-suppressant in the ALI model. Ozone and LPS exposure induced lung neutrophil and eosinophil recruitment as measured by respective peroxidase (MPO and EPX) assays, systemic leukopenia, increased levels of lung vascular neutrophil regulatory chemokines such as CXCL5, SDF-1, CXCL13 and a decrease in immune-regulatory chemokines such as BAL IL-10 and CCL27. While CD61 blocking antibody and BTB06584 produced maximum increase in BAL leukocyte counts, protein content and BAL chemokines, these treatments induced moderate increase in lung MPO and EPX content. CD61 blocking antibody induced maximal BAL cell death, a markedly punctate distribution of NK1.1, CX3CR1, CD61. BTB06584 preserved BAL cell viability with cytosolic and membrane distribution of Gr1 and CX3CR1. Propranolol attenuated BAL protein, protected against BAL cell death, induced polarized distribution of NK1.1, CX3CR1 and CD61 but presented with high lung EPX. Dexamethasone induced sparse cell membrane distribution of CX3CR1 and CD61 on BAL cells and displayed very low lung MPO and EPX levels despite highest levels of BAL chemokines. Our study unravels ATPase inhibitor IF1 as a novel drug target for lung injury.

Discovery of Clinical Candidate ACT-777991, a Potent CXCR3 Antagonist for Antigen-Driven and Inflammatory Pathologies.

The CXCR3 chemokine receptor is a G protein-coupled receptor mainly expressed on immune cells from the lymphoid lineage, including activated T cells. Binding of its inducible chemokine ligands CXCL9, CXCL10, and CXCL11 leads to downstream signaling events and the migration of activated T cells to sites of inflammation. Herein, we report the third part of our CXCR3 antagonist program in the field of autoimmunity, culminating in the discovery of the clinical compound ACT-777991 (8a). A previously disclosed advanced molecule was exclusively metabolized by the CYP2D6 enzyme, and options to address the issue are described. ACT-777991 is a highly potent, insurmountable, and selective CXCR3 antagonist that showed dose-dependent efficacy and target engagement in a mouse model of acute lung inflammation. The excellent properties and safety profile warranted progress in the clinics.

Duvelisib for Critically-Ill Patients with COVID-19 Disease: An Investigator-Initiated, Randomized, Placebo-Controlled Double-Blind Pilot Trial

Background: Severe and critical COVID-19, including acute respiratory distress syndrome (ARDS), cardiomyopathy, and shock, have been associated with a 28-day mortality exceeding 50%. While dexamethasone (dex) improves survival in such patients and highlights a role for anti-inflammatory therapy, mortality remains high especially in those who do not respond initially. Phase II/III studies of the PI3K-d/g inhibitor duvelisib in patients with chronic lymphocytic leukemia or follicular lymphoma have demonstrated that duvelisib significantly downregulates expression of inflammatory cytokines and chemokines (e.g. G-CSF, GM-CSF, macrophage inflammatory protein-1 α and β). These same inflammatory molecules are upregulated in ARDS and COVID-19. Several murine models of acute lung inflammation and sepsis have demonstrated improved markers of inflammation and survival of mice treated with PI3K inhibitors. The original SAR-CoV-1 coronavirus had demonstrated the ability to hijack the PI3K signaling machinery in order to persist within human airway cells. Additionally, in the context of neoplasia, duvelisib polarizes macrophages to the M1 phenotype which has antimicrobial effector functions in contrast to the pro-inflammatory M2 phenotype. In the context of chimeric antigen receptor T (CAR T) therapy, the DiPersio lab has identified duvelisib as a potent mediator of cytokine release syndrome (CRS) without T-cell inhibition, an overlapping concept with COVID-19. We hypothesized that duvelisib could attenuate COVID-19 ARDS and CRS through M1 macrophage polarization, reduction in cytokine signaling/production, and elimination of viral persistence. Methods: We conducted a multicenter, double-blind, placebo-controlled trial in which 28 patients were randomized 1:1 to duvelisib 25mg twice daily or placebo for 10 days. Eligible patients were 18 years or older hospitalized with a primary diagnosis of COVID-19 disease with either respiratory failure (≥ 50% lung involvement by imaging, invasive or non-invasive mechanical ventilation, or extracorporeal membrane oxygenation), new cardiomyopathy, and/or shock requiring vasopressor support. All patients were required to be receiving or have received dex 6mg daily or equivalent for at least 48 hours without improvement. All patients received prophylaxis for Pneumocystis jiroveci. We monitored viral load daily using quantitative RT-PCR to assess for changes in viral replication following initiation of therapy. Primary endpoint was 28-day survival. Secondary endpoints included: 60-day survival; duration on ventilator and vasopressors; hospital and ICU length of stay; viral kinetics; and adverse events. Correlatives included impact on cytokine expression measured by multiplex panel, viral kinetics by RT-PCR, and flow-cytometry to assess immune populations at various time points during therapy. Results: Baseline and disease characteristics were well-balanced with the exception of baseline renal replacement therapy (Table 1). At day 29, 67% of those in the duvelisib arm and 62% of those in the placebo arm were alive. Secondary efficacy endpoints were comparable between the two cohorts. There was a trend toward improved 60-day OS in the duvelisib arm (60% vs. 46%, p = 0.36, Figure 1) and some patients in the treatment arm were noted to have quick radiographic and clinical improvements. Of those on ECMO at initiation 3/5 (60%) in the duvelisib arm and 1/4 (25%) in the placebo arm were successfully weaned. Adverse events (AEs) occurred at similar rates between arms. Among AEs of special interest previously reported with the use of duvelisib, one patient developed colitis ultimately deemed to be stercoral colitis and unrelated to treatment. No CMV reactivation or Pneumocystis jiroveci pneumonia occurred. Eighty percent of overall deaths were due to respiratory failure from disease progression. In the placebo arm, one patient died of Pseudomonas pneumonia and one died of cholecystitis. Conclusion: In our pilot study, duvelisib did not show improvement in 28-day survival in a critically-ill, steroid-refractory population. However, there was a trend toward improved 60-day OS. No added toxicity was observed in those receiving duvelisib. Based on comparable safety, notable improvements in select patients, and a continued unmet need in this population, we believe larger studies are justified. Correlative data will also be presented. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Acteoside attenuates acute lung injury following administration of cobra venom factor to mice

BackgroundActeoside, a water-soluble active constituent of diverse valuable medicinal vegetation, has shown strong anti-inflammatory property. However, studies on the anti-inflammatory property of acteoside in complement-induced acute lung injury (ALI) are limited. Therefore, this study aims to evaluate the anti-inflammatory activity of acteoside in cobra venom factor (CVF)-stimulated human microvascular endothelial cells (HMEC) and in ALI mice model. MethodsIn this study, we investigated the effects of acteoside (20, 10, and 5 μg/mL) in vitro in CVF induced HMECs and the activity of acteoside (100, 50, and 20 mg/kg/day bodyweight) in vivo in CVF induced ALI mice. Each eight male mice were orally administered acteoside or the positive drug PDTC (100 mg/kg/day) for 7 days before CVF (35 μg/kg) injection. After injection for 1 h, the pharmacological effects of acteoside were investigated by spectrophotometry, pathological examination, enzyme-linked immunosorbent assay, and immunohistochemistry. ResultsIn vitro, acteoside (20, 10, and 5 μg/mL) reduced the protein expression of adhesion molecules and pro-inflammatory cytokines and transcriptional activity of NF-κB (P < 0.01). In vivo studies showed that acteoside dose-dependently alleviated lung histopathologic lesion, inhibited the production of the protein content of BALF, leukocyte cell number, lung MPO activity, and expression levels of IL-6, TNF-α, and ICAM-1, and suppressed the C5b-9 deposition and NF-κB activation in CVF-induced acute lung inflammation in mice (P < 0.05, 0.01). ConclusionThis study demonstrates that acteoside exerts strong anti-inflammatory activities in the CVF-induced acute lung inflammation model and suggests that acteoside is a potential therapeutic agent for complement-related inflammatory diseases.

Substrate-dependent modulation of the leukotriene A4 hydrolase aminopeptidase activity and effect in a murine model of acute lung inflammation.

The aminopeptidase activity (AP) of the leukotriene A4 hydrolase (LTA4H) enzyme has emerged as a therapeutic target to modulate host immunity. Initial reports focused on the benefits of augmenting the LTA4H AP activity and clearing its putative pro-inflammatory substrate Pro-Gly-Pro (PGP). However, recent reports have introduced substantial complexity disconnecting the LTA4H modulator 4-methoxydiphenylmethane (4MDM) from PGP as follows: (1) 4MDM inhibits PGP hydrolysis and subsequently inhibition of LTA4H AP activity, and (2) 4MDM activates the same enzyme target in the presence of alternative substrates. Differential modulation of LTA4H by 4MDM was probed in a murine model of acute lung inflammation, which showed that 4MDM modulates the host neutrophilic response independent of clearing PGP. X-ray crystallography showed that 4MDM and PGP bind at the zinc binding pocket and no allosteric binding was observed. We then determined that 4MDM modulation is not dependent on the allosteric binding of the ligand, but on the N-terminal side chain of the peptide. In conclusion, our study revealed that a peptidase therapeutic target can interact with its substrate and ligand in complex biochemical mechanisms. This raises an important consideration when ligands are designed to explain some of the unpredictable outcomes observed in therapeutic discovery targeting LTA4H.

C/EBPδ-induced epigenetic changes control the dynamic gene transcription of S100a8 and S100a9.

The proinflammatory alarmins S100A8 and S100A9 are among the most abundant proteins in neutrophils and monocytes but are completely silenced after differentiation to macrophages. The molecular mechanisms of the extraordinarily dynamic transcriptional regulation of S100a8 and S100a9 genes, however, are only barely understood. Using an unbiased genome-wide CRISPR/Cas9 knockout (KO)-based screening approach in immortalized murine monocytes, we identified the transcription factor C/EBPδ as a central regulator of S100a8 and S100a9 expression. We showed that S100A8/A9 expression and thereby neutrophil recruitment and cytokine release were decreased in C/EBPδ KO mice in a mouse model of acute lung inflammation. S100a8 and S100a9 expression was further controlled by the C/EBPδ antagonists ATF3 and FBXW7. We confirmed the clinical relevance of this regulatory network in subpopulations of human monocytes in a clinical cohort of cardiovascular patients. Moreover, we identified specific C/EBPδ-binding sites within S100a8 and S100a9 promoter regions, and demonstrated that C/EBPδ-dependent JMJD3-mediated demethylation of H3K27me3 is indispensable for their expression. Overall, our work uncovered C/EBPδ as a novel regulator of S100a8 and S100a9 expression. Therefore, C/EBPδ represents a promising target for modulation of inflammatory conditions that are characterized by S100a8 and S100a9 overexpression.

Bioactive phenolics fraction of Hedera helix L. (Common Ivy Leaf) standardized extract ameliorates LPS-induced acute lung injury in the mouse model through the inhibition of proinflammatory cytokines and oxidative stress

Hedera helix L. (family Araliaceae) is classified as a conventional plant used as a medicinal product in the cure and prevention of upper respiratory tract inflammation and infection due to its secretolytic and broncholytic effects. Our research was conducted to authenticate the anti-inflammatory effect of ivy leaves extract in the prevention of acute lung injury (ALI) caused by intranasal administration of lipopolysaccharides (LPS). In-vitro antimicrobial, anti-inflammatory, and anti-oxidant were evaluated, in addition to the in-vivo acute lung inflammation model induced by LPS in mice. The animals were divided into seven groups randomly (each group containing 10 mice): control negative (saline only), control positive (LPS group), standard (Dexamethasone 2 mg/kg), ethanolic ivy leaves extract (EIE, 100 mg/kg), ethanolic ivy leaves extract (EIE, 200 mg/kg), saponin rich fraction (SRF, 100 mg/kg) and phenolic rich fraction (PRF, 100 mg/kg). Right lungs were homogenized to determine the levels of SOD, MDA, catalase, IL-10, TNF-α, NO, IL-1β, IL-6, PGE2, and MPO. Left lungs were excised for histopathology and histomorphometry. Immunohistochemistry of Cox-2 and TNF-α levels were measured. Additionally, Western blotting was used to determine the levels of phosphorylated MAPK. Also, the ethanolic extract was also standardized through HPLC analysis for its content of rutin.The data showed that the oral supplementation with EIE, 200 mg/kg significantly (P < 0.05) decreased the pro-inflammatory mediators, and oxidative stress biomarkers induced by LPS. Interestingly, the phenolics showed promising activity, therefore they are responsible for the action. In conclusion, the standardized ivy leaf extract could be advised for acute lung injury for its antimicrobial, anti-oxidant, and anti-inflammatory activities.

Effects in vitro and in vivo of hesperidin administration in an experimental model of acute lung inflammation

Mechanical ventilation (MV) is a tool used in critical patient care. However, it can trigger inflammatory and oxidative processes capable of causing or aggravating lung injuries, which is known as ventilator-induced lung injury (VILI). Hesperidin is a flavonoid with antioxidant and anti-inflammatory properties in various diseases. The role of hesperidin in the process triggered by MV is poorly studied. Thus, we hypothesize hesperidin could protect the lung of mice submitted to mechanical ventilation. For that, we evaluated cell viability and reactive oxygen species (ROS) formation in macrophages using different hesperidin concentrations. We observed hesperidin did not reduce cell viability, however; it attenuated the production of intracellular ROS in cells stimulated with lipopolysaccharide (LPS). We further evaluated the effects of hesperidin in vivo in animals submitted to MV. In the bronchoalveolar lavage fluid, there were higher levels of macrophage, lymphocyte and neutrophil counts in animals submitted to MV, indicating an inflammatory process. In the lung tissue, MV induced oxidative damage and increased myeloperoxidase activity, though the antioxidant enzyme activity decreased. MV also induced the production of the inflammatory mediators CCL-2, TNF-α and IL-12. Pretreatment with hesperidin resulted in less recruitment of inflammatory cells to the airways and less oxidative damage. Also, it reduced the formation of CCL-2 and IL-12. Our results show pretreatment with hesperidin can protect the lungs of mice submitted to mechanical ventilation by modulating the inflammatory response and redox imbalance and may act to prevent MV injury.

Lacticaseibacillus rhamnosus modulates the inflammatory response and the subsequent lung damage in a murine model of acute lung inflammation

ObjectiveThe present study investigated the anti-inflammatory effect of the probiotic Lacticaseibacillus rhamnosus (Lr) on lung inflammation induced by Lipopolysaccharide (LPS) of Escherichia coli in C57BL/6 mice. MethodsC57BL/6 mice were divided into four groups: control, LPS, Lr (1 day) + LPS, and Lr (14 days) + LPS. Total and differential cells from Bronchoalveolar Lavage Fluid (BALF) were counted in a Neubauer 40X chamber, and pro-and anti-inflammatory cytokines (IL-1β, IL-6, CXCL-1, TNF-α, TGF-β, and IL-10) were measured by ELISA assay. The analysis of whole leukocytes in blood was performed using the automated system Sysmex 800i. Morphometry of pulmonary tissue evaluated alveolar hemorrhage, alveolar collapse, and inflammatory cells. Pulmonary vascular permeability was assessed by Evans blue dye extravasation, and bronchoconstriction was evaluated in a tissue bath station. The transcription factor NF-kB was evaluated by ELISA, and its gene expression and TLR-2, TLR-4, MMP-9, MMP-12, and TIMP by PCR. ResultsThe probiotic Lr had a protective effect against the inflammatory responses induced by LPS. Lr significantly reduced pro-inflammatory cells in the airways, lung parenchyma, and blood leukocytes. Furthermore, Lr reduced the production of pro-inflammatory cytokines and chemokines in BALF and the expression of TLRs, MMPs, and NF-kB in lung tissue and maintained the expression of TIMP in treated animals promoting a protective effect on lung tissue. ConclusionsThe results of the study indicate that pre-treatment with the probiotic Lr may be a promising way to mitigate lung inflammation in endotoxemia.

Inorganic polyphosphate from the immunobiotic Lactobacillus rhamnosus CRL1505 prevents inflammatory response in the respiratory tract.

Lactobacillus (L.) rhamnosus CRL1505 accumulates inorganic polyphosphate (polyP) in its cytoplasm in response to environmental stress. The aim of this study was to evaluate the potential effects of polyP from the immunobiotic CRL1505 on an acute respiratory inflammation murine animal model induced by lipopolysaccharide (LPS).First, the presence of polyP granules in the cytoplasm of CRL1505 strain was evidenced by specific staining. Then, it was demonstrated in the intracellular extracts (ICE) of CRL1505 that polyP chain length is greater than 45 phosphate residues. In addition, the functionality of the genes involved in the polyP metabolism (ppk, ppx1 and ppx2) was corroborated by RT-PCR. Finally, the possible effect of the ICE of CRL1505 strain containing polyP and a synthetic polyP was evaluated in vivo using a murine model of acute lung inflammation. It was observed that the level of cytokines pro-inflammatory (IL-17, IL-6, IL-2, IL-4, INF-γ) in serum was normalized in mice treated with ICE, which would indicate that polyP prevents the local inflammatory response in the respiratory tract. The potential application of ICE from L. rhamnosus CRL1505 as a novel bioproduct for the treatment of respiratory diseases is one of the projections of this work.

2-Methoxyestradiol Protects Against Lung Ischemia/Reperfusion Injury by Upregulating Annexin A1 Protein Expression.

Background: 2-Methoxyestradiol (2ME), a natural 17-β estradiol metabolite, is a potent anti-inflammatory agent, but its effect on ischemia/reperfusion (IR)-induced acute lung inflammation remains unknown. Annexin A1 (AnxA1), a glucocorticoid-regulated protein, is effective at inhibiting neutrophil transendothelial migration by binding the formyl peptide receptors (FPRs). We aimed to investigate whether 2ME upregulates the expression of AnxA1 and protects against IR-induced lung damage.Methods: IR-mediated acute lung inflammation was induced by ischemia for 40 min followed by reperfusion for 60 min in an isolated, perfused rat lung model. The rat lungs were randomly treated with vehicle or 2ME, and the functional relevance of AnxA1 was determined using an anti-AnxA1 antibody or BOC2 (a pan-receptor antagonist of the FPR). In vitro, human primary alveolar epithelial cells (HPAECs) and rat neutrophils were pretreated with 2ME and an AnxA1 siRNA or anti-AnxA1 antibody and subjected to hypoxia-reoxygenation (HR).Results: 2ME significantly decreased all lung edema parameters, neutrophil infiltration, oxidative stress, proinflammatory cytokine production, lung cell apoptosis, tight junction protein disruption, and lung tissue injury in the IR-induced acute lung inflammation model. 2ME also increased the expression of the AnxA1 mRNA and protein and suppressed the activation of nuclear factor-κB (NF-κB). In vitro, 2ME attenuated HR-triggered NF-κB activation and interleukin-8 production in HPAECs, decreased transendothelial migration, tumor necrosis factor-α production, and increased apoptosis in neutrophils exposed to HR. These protective effects of 2ME were significantly abrogated by BOC2, the anti-AnxA1 antibody, or AnxA1 siRNA.Conclusions: 2ME ameliorates IR-induced acute lung inflammation by increasing AnxA1 expression. Based on these results, 2ME may be a promising agent for attenuating IR-induced lung injury.

Bioorthogonal supramolecular cell-conjugation for targeted hitchhiking drug delivery

Cells possess inherent advantages to facilitate targeted payload delivery. Current strategies to conjugate payload carriers to the surface of cells are either via covalent bonds that not only involve complicated synthetic process but also often impair cellular functions, or via biological ligand-receptor interactions that are only specific to particular types of cells. Herein, we report a facile, bioorthogonal supramolecular conjugation strategy to prepare targeted cell-hitchhiking delivery systems, mediated via artificial host–guest interactions between β-cyclodextrin and adamantane, respectively anchored (via insertion) on the surfaces of live cells and payload carriers. In a paw swelling inflammation mouse model, supramolecularly conjugated macrophage-carriers (either cell–cell or cell-nanoparticle systems) were efficiently delivered hand-in-hand to the swelling paw, driven by the inflammatory tropism of macrophage. Furthermore, in an acute lung inflammation model of mouse, supramolecular conjugation of peritoneal macrophage and quercetin-loaded liposomes significantly improved targeting efficiency of the liposomes, and effectively alleviated the lung inflammation through the anti-inflammatory and anti-oxidative effects of quercetin. The cell-friendly, facile, host–guest interactions mediated cellular conjugation may provide the very first general strategy for preparing various cell-hitchhiking delivery systems to meet the needs of diverse biomedical applications.

Attenuation of pristimerin on TNF-α-induced endothelial inflammation

ObjectivePristimerin is known to have anti-cancer and anti-inflammatory activities; however, its therapeutic mechanism has not been described. In this study, to investigate the therapeutic mechanism of pristimerin, we examined the effect of pristimerin on TNF-α-induced endothelial inflammatory response both in vitro and in vivo. MethodsLeukocyte-endothelium Adhesion Assay was use to evaluate the endothelial cell-monocyte interaction. Western blotting was used to confirm protein expression. NF-κB p65 nuclear translocation in endothelial cells was detected using immunofluorescent microscopy. In vivo leukocyte infiltration was evaluated using acute lung inflammation model. ResultsPristimerin profoundly inhibited TNF-α-induced adhesion of monocytes to human endothelial cells and the leukocyte transmigration. Pristimerin dramatically inhibited the expression of TNF-α-induced endothelial adhesion molecules (intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1)) and the pro-inflammatory cytokine (IL-6, IL-8 and monocyte chemoattractant protein-1 (MCP-1)). Pristimerin suppressed the penetration of the leukocyte in the acute lung injury mice model. Furthermore, pristimerin also suppressed the TNF-α-activated Nuclear factor kappa B (NF-κB) activation. ConclusionsPristimerin has the anti-inflammatory properties in endothelial cells, at least in part, through the suppression of NF-κB activation, which may have a potential therapeutic effects for inflammatory vascular diseases.

Fractalkine Is Linked with the Necrosome Pathway in Acute Pulmonary Inflammation

Background: Acute pulmonary inflammation affects more than 10% of ICU admissions and is associated with a high mortality. The chemokine fractalkine (CX3CL1) and its receptor CX3CR1 have been shown to influence pulmonary inflammation. Methods: In a murine model of acute lung inflammation, we determined the LPS-induced PMN infiltration and particular the accumulation of necroptotic PMNs in the lung tissue and alveolar space of wild type (WT) and CX3CR1-/- animals by flow cytometry. Chemokines and damage-associated molecular patterns (DAMPs) were detected by ELISA and RT-PCR. The activation of necrosome-related proteins receptor-interacting serine/threonine-protein kinase (RIPK) 1 and 3, and mixed lineage kinase domain-like protein (MLKL) in WT and CX3CR1-/- mice were evaluated by western blots. Findings: Acute pulmonary inflammation was significantly enhanced in CX3CR1-/- compared to WT-mice concerning neutrophil migration and microvascular permeability. Furthermore, CX3CR1 deficiency revealed an increase of necroptotic PMN counts and an augmented activation of RIPK1 and RIPK3. Both kinases enhanced the phosphorylation of MLKL, leading to membrane rupture and the release of DAMPs. DAMPs were significantly higher in CX3CR1-/- mice, explaining the increased inflammation in CX3CR1-/- mice. The necrosome led to activation of the signaling cascade AKT, ERK1/2, and NFκB, resulting in an increase of chemo- and cytokines. Pharmacologic inhibition of RIPK3 and MLKL improved the inflammatory response. In vitro studies confirmed our in vivo findings. Interpretation: In conclusion, we linked for the first time CX3CL1 with necroptosis in pulmonary inflammation and demonstrated a pivotal role of the necrosome complex in human PMNs. Funding Statement: This work was supported by the Else Kroner-Fresenius-Stiftung 2014_A148 (to FK), the Fortuene Program F1211382 (to FK), and the German Research Foundation Grant KO4280/2-1 (to FK). We acknowledge support by Open Access Publishing Fund of University of Tubingen. Declaration of Interests: There are no competing interests for any of the authors. Ethics Approval Statement: All animal protocols were approved by the Animal Care and Use Committee of the University of Tuebingen.

Molecular Dynamics of Lipopolysaccharide-Induced Lung Injury in Rodents.

Acute respiratory distress syndrome (ARDS) is a common disease entity in critical care medicine and is still associated with a high mortality. Because of the heterogeneous character of ARDS, animal models are an insturment to study pathology in relatively standardized conditions. Rodent models can bridge the gap from in vitro investigations to large animal and clinical trials by facilitating large sample sizes under physiological conditions at comparatively low costs. One of the most commonly used rodent models of acute lung inflammation and ARDS is administration of lipopolysaccharide (LPS), either into the airways (direct, pulmonary insult) or systemically (indirect, extra-pulmonary insult). This narrative review discusses the dynamics of important pathophysiological pathways contributing to the physiological response to LPS-induced injury. Pathophysiological pathways of LPS-induced lung injury are not only influenced by the type of the primary insult (e.g., pulmonary or extra-pulmonary) and presence of additional stimuli (e.g., mechanical ventilation), but also by time. As such, findings in animal models of LPS-induced lung injury may depend on the time point at which samples are obtained and physiological data are captured. This review summarizes the current evidence and highlights uncertainties on the molecular dynamics of LPS-induced lung injury in rodent models, encouraging researchers to take accurate timing of LPS-induced injury into account when designing experimental trials.

Effect of Intratracheal Instillation of ZnO Nanoparticles on Acute Lung Inflammation Induced by Lipopolysaccharides in Mice.

Although studies have shown toxic effects of zinc oxide (ZnO) particles following inhalation, additional effects on injured lungs, which are characterized by dysfunction of the alveolar-capillary barriers, remain uncharacterized. To explore these additional effects, nano-sized ZnO (nZnO) and bulk-sized ZnO were applied to lipopolysaccharide (LPS)-challenged mouse lungs, which were used as a disease model of acute lung inflammation. An elevated Zn2+ concentration was detected in lung tissue after LPS plus nZnO exposure. Exposure to nZnO in LPS-challenged mice resulted in higher total cell number, proportion of neutrophils, and total protein level in bronchoalveolar lavage fluid. Intratracheal instillation of nZnO intensively aggravated LPS-induced lung inflammation that was accompanied by enhanced expression of interleukin-1β, interleukin-6, monocyte chemotactic protein-1α, and granulocyte-macrophage colony stimulating factor. Catalase, glutathione, and total superoxide dismutase levels were significantly decreased, and the malondialdehyde level was obviously increased in the LPS plus nZnO group. 8-Hydroxyguanosine, a marker for DNA damage, was highly concentrated in the lungs from the LPS plus nZnO group. Furthermore, nZnO increased lung apoptosis in an acute lung inflammation model. Taken together, this evidence indicates that nZnO aggravates lung inflammation related to LPS. This enhancement effect may be mediated via oxidative stress, which can lead to DNA damage and apoptosis. This work is important because of the ever-increasing exposure of people to ZnO nanoparticles in industry. The identification of the toxic effects of nZnO and possible mechanisms revealed in this study provide valuable information for future studies.

Endocan regulates acute lung inflammation through control of leukocyte diapedesis.

Acute respiratory distress syndrome is a severe form of respiratory failure, occurring in up to 20% of patients admitted to the intensive care unit with sepsis. Dysregulated leukocyte diapedesis is a major contributor to acute respiratory distress syndrome. Endocan is a circulating proteoglycan that binds to the leukocyte integrin leukocyte functional antigen-1 and blocks its interaction with its endothelial ligand, ICAM-1. The objective of this study was to evaluate the role of endocan in the control of acute lung inflammation. In vitro, endocan inhibited human leukocyte transendothelial migration as well as ICAM-1-dependent migration but had a very mild effect on ICAM-1-dependent adhesion. Endocan also acted as an inhibitor of transendothelial migration of mouse leukocytes. The effect of systemic administration of recombinant human endocan was assessed in a model of acute lung inflammation in BALB/c mice. Treatment with endocan 1 h after intratracheal LPS challenge reduced the alveolar inflammatory response, diminished histological features of acute lung injury, and improved respiratory function. These results highlight the anti-inflammatory role of human endocan and its protective effect against acute lung injury.NEW & NOTEWORTHY We show here that endocan inhibits ICAM-1-dependent human leukocyte transendothelial migration and ICAM-1-dependent adhesion. We also found that in BALB/c mice with tracheal LPS-induced acute lung injury treatment with recombinant human endocan reduces lung inflammation, notably through reduction of neutrophilic recruitment, and restores normal lung function. These results confirm the hypothesis that human endocan may have a protective effect against acute lung inflammation.

Using Klebsiella pneumoniae to Model Acute Lung Inflammation in Mice.

Lung infections caused by bacteria can induce a spectrum of immune responses, which is in part determined by the level of exposure and the degree of the host response. The host response involves pattern recognition receptors (PRRs) which sense pathogen and damage associated molecular patterns. Therefore, models of acute lung inflammation are necessary for further understanding the role of the innate immune system during bacterial infection in humans. Mice are a widely used model organism for studying important aspects of human lung pathogenesis, including acute and chronic inflammatory diseases. Klebsiella pneumoniae is a gram-negative bacterium that is commonly associated with respiratory infections, especially in a hospital setting. In this protocol, we describe a model of bacteria-mediated lung inflammation using K. pneumoniae. After a single intratracheal administration of K. pneumoniae, mice showed a strong level of Th1-mediated immune activation in the lungs. The model described here, while optimized for K. pneumonia, can be performed using other bacteria, fungi, and viruses as well.

Lipoxin A4 ameliorates renal ischaemia-reperfusion-induced acute lung injury in rats.

Lipoxin A4 (LA4), a bioactive product of arachidonic acid, has been shown to exert strong anti-inflammatory activity. By contrast, the anti-inflammatory action of LA4 in a renal ischaemia-reperfusion (RIR)-mediated acute lung inflammation (ALI) model and the potential pathogenesis of the condition is still unclear. The aim of the current research was to investigate the effect of LA4 on RIR-induced ALI. The rat ALI model was induced by RIR. LA4 was injected via the tail vein immediately after RIR. The results indicate that LA4 markedly inhibits inflammatory cells infiltration, attenuates myeloperoxidase activity, and reduces the concentration of inflammatory mediators and Toll-like receptor 4 (TLR4) in RIR-induced ALI. Furthermore, LA4 suppressed nuclear factor kappa B (NF-κB) p65 and mitogen-activated protein kinase (MAPK) activation. The protective effect of LA4 in RIR-stimulated ALI was reversed by BOC-2 (an antagonist of the LA4 receptor). These results indicate that LA4 exerts powerful anti-inflammatory functions in RIR-induced ALI by attenuating TLR4 expression via MAPK and NF-κB signalling. Accordingly, LA4 might be an underlying treatment drug for RIR-induced ALI.