Bronchoalveolar Lavage Fluid Concentrations Research Articles

Corticosteroid Treatment Prevents Lipopolysaccharide-Induced Increase of ACE2 and Reduces Fibrin Degradation Products in Bronchoalveolar Lavage Fluid

The assessment of systemic corticosteroid effects on intrapulmonary disease biomarkers is challenging. This retrospective evaluation of a human endotoxemia model quantified ACE2 and fibrin degradation product (FDP) concentrations in bronchoalveolar lavage fluid (BALF) samples from a randomized, double-blind, placebo-controlled study (NCT01714427). Twenty-four healthy volunteers received either 2 × 40 mg intravenous dexamethasone or placebo. These doses were administered 12 h apart prior to bronchoscopy-guided intrabronchial lipopolysaccharide (LPS) stimulation (control: saline into the contralateral lung segment). We quantified ACE2 concentration, the Angiotensin-II-to-Angiotensin-1-7 conversion rate as well as FDP in BALF 6 h after LPS instillation. In placebo-treated subjects, LPS instillation increased ACE2 concentrations compared to unstimulated lung segments [1,481 (IQR: 736–1,965) vs. 546 (413–988) pg/mL; p = 0.016]. Dexamethasone abolished the increase in ACE2 concentrations (p=0.13). Accordingly, LPS instillation increased the Angiotensin-II-to-Angiotensin-1-7 conversion capacity significantly in the placebo cohort, indicating increased enzymatic activity (p = 0.012). FDP increased following LPS-instillation [8.9 (2.7–12.2) vs. 6.6 (0.9–9.6) ng/mL, p = 0.025] in the placebo group, while dexamethasone caused a shut-down of fibrinolysis in both lung segments. LPS instillation increased ACE2 concentration, its enzymatic activity and FDP, which was mitigated by systemic dexamethasone treatment. Our results strengthen previously published findings regarding the efficiency of corticosteroids for the treatment of COVID-19-induced acute lung injury.

Taxifolin ameliorates sepsis-induced lung capillary leak through inhibiting the JAK/STAT3 pathway

As a systemic inflammatory reaction, sepsis is associated with various organ dysfunctions. The capillary leakage and the imbalance between T helper 17 and regulatory T (Th17/Treg) cells are associated with sepsis-induced lung injury. Taxifolin (TXL) has been found to play a vital role in regulating this diverse disease. However, the detailed functioning and mechanism of TXL in regulating sepsis-induced lung capillary leak remain elusive. Balb/c mice were used to establish sepsis-induced lung injury model through administration of lipopolysaccharide (LPS). The structure of lung tissues was observed by using hematoxylin & eosin staining. Protein level and total cells in bronchoalveolar lavage fluid (BALF) were measured by bicinchoninic acid (BCA) protein assay kit and hematimetry assay, respectively. Quantitative real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay were employed to detect the level of inflammatory cytokines. The content of Th17 and Treg cells were measured by flow cytometry analysis. Western blot assay was used to determine the protein level of retinoid-related orphan receptor-γt (RORγt), Forkhead box P3 (Foxp3), Janus kinase 2 (JAK2), phospho(p)-JAK2, signal transducer and activator of transcription 3 (STAT3), and phospho(p)-STAT3. Taxifolin effectively prolonged the survival period of sepsis mice and alleviated LPS-induced lung injury in a dose-dependent manner. Moreover, TXL reduced LPS-induced increase in protein levels and T cell content in BALF, and effectively restored the wet:dry ratio of lung tissue and tissue permeability. Treating with TXL notably inhibited the production of pro-inflammatory cytokines induced by sepsis and influenced the balance between Th17 and Treg cells. Furthermore, TXL treatment suppressed the activation of JAK/STAT3 signaling pathway in a dose-dependent manner. Our findings revealed that TXL alleviated sepsis-induced capillary leak in the lungs of mice by regulating JAK/STAT3 signaling pathway.

Taurine Alleviates LPS-Induced Acute Lung Injury by Suppressing TLR-4/NF-κB Pathway.

Taurine has the function of immune regulation, relieving acute and chronic inflammation caused by various agents, and maintaining cell homeostasis. This investigation focused on the protective functions of taurine targeting acute lung injury (ALI) induced by LPS. Sixty male SD rats aged 6-7weeks were segregated at random: blank control group (C group), taurine control group (T group), ALI model group (LPS group), and taurine prevention groups (LPST1, LPST, LPST3 Groups). C group and LPS group were given normal drinking water, while T group and LPST group were given 2% taurine in drinking water. LPST1 group was given 1% taurine in drinking water while. LPST3 group was given 3% taurine in drinking water. On the 14th and 28th day, LPS group and LPST1, LPST, and LPST3 groups were subjected to injection of LPS (25 mg/kg) into the trachea of rats. Serum, peripheral blood, lung tissue, and bronchoalveolar lavage fluid (BALF) were collected at 6h post-LPS injection. The wet/dry ratio (W/D) of lung was measured by hot drying method. The population of white blood cells and the abundance of inflammatory-related cells within peripheral blood were counted by an automatic blood cell analyzer. The population of white blood cells within BALF was counted by a white blood cell counting plate combined with Swiss Giemsa staining, while the proportion of related white blood cells was calculated. BCA reagent was used to determine the protein concentration in BALF. The levels of pro-inflammatory factors (IL-1 β, IL-6, IL-18, TNF - α), anti-inflammation factors (IL-10, IL-4), and taurine within serum and lung tissue were detected by ELISA. Lung structural tissue alterations were observed through HE staining techniques. Myeloperoxidase (MPO) activities within lung tissue were detected through colorimetry. Protein expression levels of TLR4, MyD88, NF-κ Bp65, NF-κ Bp-p65, MCP-1, together with CD68 within lung tissue, were analyzed by Western blot (WB) and immunohistochemistry (IHC). The taurine pretreatment group contained significantly reduced W/D, MPO activity, and the number of inflammatory cells in BALF induced by LPS. In addition, compared with ALI model group, the taurine pretreatment group contained significantly reduced levels of pro-inflammatory factors in lung tissue, increased levels of anti-inflammatory factors, and decreased expression levels of key proteins in TLR-4/NF-κ B pathway. Taurine can protect rats from ALI by inhibiting the activation of neutrophils, macrophages, and TLR-4/NF-κ B signaling pathway.

Empagliflozin Protects against Pulmonary Ischemia/Reperfusion Injury via an Extracellular Signal-Regulated Kinases 1 and 2-Dependent Mechanism.

Ischemia/reperfusion (I/R) injury of the lung can lead to extensive pulmonary damage. Sodium-glucose cotransporter-2 (SGLT2) inhibitors are insulin-independent, oral antihyperglycemic agents used for treating type 2 diabetes mellitus (T2DM). Although their cardioprotective properties have been reported, their potential roles in pulmonary protection in vivo are poorly characterized. Here, we tested a hypothesis that empagliflozin, an SGLT2 inhibitor, can protect lungs in a mouse model of lung I/R injury induced by pulmonary hilum ligation in vivo. We assigned C57/BL6 mice to sham-operated, nonempagliflozin-treated control, or empagliflozin-treated groups. Pulmonary I/R injury was induced by 1-hour left hilum ligation followed by 2-hour reperfusion. Using quantitative polymerase chain reaction (q-PCR) and Western blot analysis, we demonstrate that SGLT2 is highly expressed in mouse kidney but is weakly expressed in mouse lung (n = 5-6 per group, P < 0.01 or P < 0.001). Empagliflozin improved respiratory function, attenuated I/R-induced lung edema, lessened structural damage, inhibited apoptosis, and reduced inflammatory cytokine production and protein concentration in bronchoalveolar lavage (BAL) fluid [P < 0.05 or P < 0.001 versus control group (CON)]. In addition, empagliflozin enhanced phosphorylation of pulmonary extracellular signal-regulated kinases 1 and 2 (ERK1/2) post-I/R injury in vivo (P < 0.001, versus CON, n = 5 per group). We further showed that pharmacological inhibition of ERK1/2 activity reversed these beneficial effects of empagliflozin. In conclusion, we showed that empagliflozin exerts strong lung protective effects against pulmonary I/R injury in vivo, at least in part via the ERK1/2-mediated signaling pathway. SIGNIFICANCE STATEMENT: Pulmonary ischemia-reperfusion (I/R) can exacerbate lung injury. Empagliflozin is a new antidiabetic agent for type 2 diabetes mellitus. This study shows that empagliflozin attenuates lung damage after pulmonary I/R injury in vivo. This protective phenomenon was mediated at least in part via the extracellular signal-regulated kinases 1 and 2-mediated signaling pathway. This opens a new avenue of research for sodium-glucose cotransporter-2 inhibitors in the treatment of reperfusion-induced acute pulmonary injury.

Seabuckthorn Berries Extract Attenuates Pulmonary Vascular Hyperpermeability in Lipopolysaccharide-Induced Acute Lung Injury in Mice.

ObjectiveTo investigate the effect of seabuckthorn berries extract (SBE) on pulmonary vascular hyperpermeability in the mice model of acute lung injury (ALI) induced by lipopolysaccharide (LPS).MethodsSixty Kunming mice were allocated into 6 groups by a random number table, including control, LPS, dexamethasone (Dex, 1 mg/kg), and 120, 240 and 480 mg/kg SBE groups, 10 mice in each group. Except the control group, mice were pre-treated with Dex and SBE, respectively, for 7 days before LPS was intraperitoneally injected to induce ALI. Pulmonary vascular hyperpermeability was evaluated by histopathologic observation and transvascular leakage determination. Tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) levels in serum were measured using enzyme-linked immunosorbent assay. The expression of nuclear factor-kappa B (NF-κB) p65 in lung cells was determined by immunofluorescence analysis. The contents of cytoplasmic inhibitor of nuclear factor-κB kinase (IKK) and nuclear p65, as well as downstream proteins of E-selectin (CD62E) and intercellular adhesion molecule-1 (ICAM-1), were determined using Western blot analysis.ResultsHistopathological observation confirmed SBE treatment alleviated morphological lesion induced by LPS. Compared with the LPS group, 480 mg/kg SBE significantly decreased the water content of lung, Evans blue accumulation in lung tissue, and protein concentration and neutrophils count in bronchoalveolar lavage fluid (P<0.01); moreover, 480 mg/kg SBE significantly suppressed release of TNF-α and IL-6, and down-regulated expressions of IKK, nuclear p65, ICAM-1 and CD62E (P<0.01).ConclusionSBE maintained alveolar-capillary barrier integrity under endotoxin challenge in mice by suppressing the key factors in the pathogenesis of ALI.Electronic Supplementary MaterialSupplementary material (Appendix 1) is available in the online version of this article at 10.1007/s11655-021-3346-1.

Methyl p‑hydroxycinnamate exerts anti‑inflammatory effects in mouse models of lipopolysaccharide‑induced ARDS.

Methyl p-hydroxycinnamate (MH), an esterified derivative of p-Coumaric acid exerts anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Based on these effects, the present study investigated the protective role of MH in a mouse model of LPS-induced acute respiratory distress syndrome (ARDS). The results demonstrated that administration of LPS (5 mg/kg intranasally) markedly increased the neutrophil/macrophage numbers and levels of inflammatory molecules (TNF-α, IL-6, IL-1β and reactive oxygen species) in the bronchoalveolar lavage fluid (BALF) of mice. On histological examination, the presence of inflammatory cells was observed in the lungs of mice administered LPS. LPS also notably upregulated the secretion of monocyte chemoattractant protein-1 and protein content in BALF as well as expression of inducible nitric oxide synthase in the lungs of mice; it also caused activation of p38 mitogen-activated protein kinase (MAPK) and NF-κB signaling. However, MH treatment significantly suppressed LPS-induced upregulation of inflammatory cell recruitment, inflammatory molecule levels and p38MAPK/NF-κB activation, and also led to upregulation of heme oxygenase-1 (HO-1) expression in the lungs of mice. In addition, the ability of MH to induce HO-1 expression was confirmed in RAW264.7 macrophages. Taken together, the findings of the present study indicated that MH may exert protective effects against airway inflammation in ARDS mice by inhibiting inflammatory cell recruitment and the production of inflammatory molecules.

Intrapulmonary pharmacokinetics of high doses of tigecycline in patients with ventilator-associated pneumonia

Tigecycline is commonly used for infections by multidrug-resistant bacteria. However, it is not approved for ventilator-associated pneumonia (VAP) as increased mortality has been reported in VAP patients treated with conventional doses. The purpose of this study was to prospectively evaluate the intrapulmonary pharmacokinetics of off-label high-dose tigecycline in patients with VAP. Nine mechanically ventilated patients received tigecycline intravenously (loading dose 200 mg followed by 100 mg every 12 h). After ≥5 doses, two bronchoscopies were performed in each patient on consecutive days and eight blood samples were collected. Tigecycline concentrations in plasma and bronchoalveolar lavage fluid were determined by liquid chromatography. The urea dilution method was used to calculate epithelial lining fluid (ELF) concentrations. A two-compartmental pharmacokinetic (PK) model with linear elimination was used to estimate PK parameters. Mean patient age was 69 ± 11.86 years and mean APACHE II score was 21. The estimated population mean PK parameters (relative standard error) were: clearance, 11.64 L/h (54%); volume of distribution in central compartment, 79.01 L (37%); volume of distribution in peripheral compartment, 92.95 L (17%); intercompartmental clearance, 62.81 L/h (34%); and ELF penetration ratio, 2.41 (40%). Cmax, Cmin, plasma AUC0-12, plasma fAUC0-12 and ELF AUC0-12 were 1.99 ± 1.82 μg/mL, 0.81 ± 1.27 μg/mL, 12.89 ± 17.25 μg•h/mL, 3.24 ± 3.09 μg•h/mL and 7.13 ± 2.61 μg•h/mL, respectively. The increased plasma and ELF AUC0-12 achieved with a 200 mg daily tigecycline dose, combined with high ELF penetration, support the effectiveness of off-label high-dose tigecycline in VAP.

COVID-19 acute respiratory distress syndrome: A simulation study of the effects of combination therapy with tocilizumab and siltuximab.

AimsTo assess the potential of interleukin‐6 (IL‐6) signalling blockade in the lung to treat SARS‐CoV‐2 infection via model‐based simulation by exploring soluble IL‐6 receptor (sIL‐6R) sequestration by tocilizumab (TCZ) and IL‐6 sequestration by siltuximab (SIL).MethodsLiterature values of IL‐6, IL‐6 antagonist SIL, sIL‐6R, IL‐6R antagonist TCZ and their respective binding constants were used to develop a model to predict the impact of treatment on IL‐6 signalling. Models were used to generate simulated bronchoalveolar lavage fluid concentrations for normal subjects, subjects at risk of developing acute respiratory distress syndrome (ARDS), and subjects with ARDS under 4 conditions: without treatment; treatment with TCZ; treatment with SIL; and treatment with TCZ + SIL.ResultsWith TCZ intervention, IL‐6 levels are unaffected and sIL‐6R is reduced somewhat below the Normal case. IL‐6:sIL‐6R complex only slightly decreased relative to the no‐intervention case. With SIL intervention, sIL‐6R levels are unaffected and IL‐6 is greatly reduced below the Normal case. IL‐6:sIL‐6R complex is greatly decreased relative to the no‐intervention case. With TCZ + SIL intervention, IL‐6 and sIL‐6R levels are reduced below the Normal case and achieve suppression equivalent to monotherapy results for their respective targets. IL‐6:sIL‐6R complex reduction is predicted to be greater than that achieved with monotherapy. This reflects sequestration of both components of the complex and the nonlinear binding equilibrium.ConclusionCoadministration of both IL‐6 and IL‐6R sequestering products such as SIL and TCZ may be necessary to effectively treat COVID‐19 patients who have or are at risk of developing ARDS.

Chicken bone marrow mesenchymal stem cells improve lung and distal organ injury

Mesenchymal stem cells (MSCs) are associated with pulmonary protection and longevity. We separated chicken bone marrow-derived mesenchymal stem cells (BM-MSCs); investigated whether BM-MSCs can improve lipopolysaccharide (LPS)-induced lung and distal organ injury; and explored the underlying mechanisms. Ninety-six male ICR (6 weeks old) mice were randomly divided into three groups: Sham, LPS, and LPS + MSC groups. The mice were intratracheally injected with 5 mg/kg LPS to induce acute lung injury (ALI). The histopathological severity of injury to the lung, liver, kidney, heart, and aortic tissues was detected. Wet/dry ratio, protein concentrations in bronchoalveolar lavage fluid (BALF), BALF cell counts, inflammatory cytokine levels in serum, inflammatory cytokine gene expression, and oxidative stress-related indicators were detected. In addition, a survival analysis was performed in sixty male ICR mice (6 weeks old, 18–20 g). This study used chicken BM-MSCs, which are easier to obtain and more convenient than other animal or human MSCs, and have MSC-associated properties, such as a colony forming ability, multilineage differentiation potential, and certain phenotypes. BM-MSCs administration significantly improved the survival rate, systemic inflammation, and the histopathological severity of lung, liver, kidney, and aortic injury during ALI. BM-MSCs administration reduced the levels of inflammatory factors in BALF, the infiltration of neutrophils, and oxidative stress injury in lung tissue. In addition, BM-MSCs administration reduced TRL4 and Mdy88 mRNA expression during ALI. Chicken BM-MSCs serve as a potential alternative resource for stem cell therapy and exert a prominent effect on LPS-induced ALI and extrapulmonary injury, in part through TRL4/Mdy88 signaling and inhibition of neutrophil inflammation and oxidative stress injury.

Auricular Vagus Nerve Stimulation Attenuates Lipopolysaccharide-Induced Acute Lung Injury by Inhibiting Neutrophil Infiltration and Neutrophil Extracellular Traps Formation.

Vagus nerve stimulation has been shown to exert anti-inflammation activities in sepsis. However, surgical implantation of stimulation devices is performed under general anesthesia, which limits its clinical application. Auricular vagus nerve stimulation (AVNS) is a minimal invasive technique that delivers electrical currents to the auricular branch of the vagus nerve. The purpose of this study was to determine the effects of AVNS on systemic inflammation, lung injury, neutrophil infiltration, and neutrophil extracellular traps (NETs) formation in the lung. In a LPS challenge lung-injury mice model, AVNS was applied to bilateral ears. Twelve hours after LPS administration, samples of blood, bronchoalveolar lavage fluid (BALF), and lung tissues were processed for investigations. We found that the treatment with AVNS significantly attenuated histopathological changes and neutrophil infiltration in the lung tissue, inhibited inflammatory cytokine elevations in serum and BALF, and decreased protein concentrations in BALF. Besides, AVNS decreased leukocyte and neutrophil accounts in BALF. Furthermore, colocalization of citrullination of histone H3 and myeloperoxidase expressions (highly specific marker of NETs) was reduced in AVNS mice. In conclusion, AVNS reduced systemic inflammation, attenuated lung edema, and inhibited neutrophil infiltration and NETs formation in the lung in LPS mice.

Physiologically Based Pharmacokinetic Modelling of Inhaled Nemiralisib: Mechanistic Components for Pulmonary Absorption, Systemic Distribution, and Oral Absorption.

Background and ObjectivesPhysiologically based pharmacokinetic (PBPK) modelling has evolved to accommodate different routes of drug administration and enables prediction of drug concentrations in tissues as well as plasma. The inhalation route of administration has proven successful in treating respiratory diseases but can also be used for rapid systemic delivery, holding great promise for treatment of diseases requiring systemic exposure. The objective of this work was to develop a PBPK model that predicts plasma and tissue concentrations following inhalation administration of the PI3Kδ inhibitor nemiralisib.MethodsA PBPK model was built in GastroPlus® that includes a complete mechanistic description of pulmonary absorption, systemic distribution and oral absorption following inhalation administration of nemiralisib. The availability of clinical data obtained after intravenous, oral and inhalation administration enabled validation of the model with observed data and accurate assessment of pulmonary drug absorption. The PBPK model described in this study incorporates novel use of key parameters such as lung systemic absorption rate constants derived from human physiological lung blood flows, and implementation of the specific permeability-surface area product per millilitre of tissue cell volume (SpecPStc) to predict tissue distribution.ResultsThe inhaled PBPK model was verified using plasma and bronchoalveolar lavage fluid concentration data obtained in human subjects. Prediction of tissue concentrations using the permeability-limited systemic disposition tissue model was further validated using tissue concentration data obtained in the rat following intravenous infusion administration to steady state.ConclusionsFully mechanistic inhaled PBPK models such as the model described herein could be applied for cross molecule assessments with respect to lung retention and systemic exposure, both in terms of pharmacology and toxicology, and may facilitate clinical indication selection.

Pravastatin attenuates sepsis-induced acute lung injury through decreasing pulmonary microvascular permeability via inhibition of Cav-1/eNOS pathway

BackgroundDisruption of alveolar endothelial barrier caused by inflammation drives the progression of septic acute lung injury (ALI). Pravastatin, an inhibitor of HMG Co-A reductase, has potent anti-inflammatory effects. In the present study, we aim to explore the beneficial role of pravastatin in sepsis‐induced ALI and its related mechanisms. MethodsA septic ALI model was established by cecal ligation and puncture (CLP) in mice. The pulmonary microvascular endothelial cells (PMVECs) were challenged with lipopolysaccharide (LPS). The pathological changes in lung tissues were examined by HE staining. The pulmonary microvascular permeability was determined by lung wet-to-dry (W/D) weight ratio and Evans blue staining. The total protein concentration in bronchoalveolar lavage fluid (BALF) was detected by BCA assay. The levels of TNF-α, IL-1β, and IL-6 were assessed by qRT-PCR and ELISA. Apoptosis was determined by flow cytometry and TUNEL. Western blotting was performed for detection of target protein levels. The expression of VE-Cadherin in lung tissues was evaluated by immunohistochemical staining. ResultsPravastatin improved survival rate, attenuated lung pathological changes and reduced pulmonary microvascular permeability in septic mice. In addition, pravastatin restrained sepsis-induced inflammatory response and apoptosis in the lung tissues and PMVECs. Moreover, pravastatin up-regulated the levels of junction proteins ZO-1, JAM-C, and VE-Cadherin. Finally, pravastatin suppressed inflammation, apoptosis and enhanced the expression of junction proteins via regulating Cav-1/eNOS signaling pathway in LPS-exposed PMVECs. ConclusionPravastatin ameliorates sepsis-induced ALI through improving alveolar endothelial barrier disruption via modulating Cav-1/eNOS pathway, which may be an effective candidate for treating septic ALI.

Role of diabetes in lung injury from acute exposure to electronic cigarette, heated tobacco product, and combustible cigarette aerosols in an animal model.

BackgroundPatients with diabetes are more vulnerable to the detrimental respiratory effects of combustible cigarette smoke (CS) when compared to the general population. Electronic cigarettes (ECIG) and heated tobacco products (HTP) are marketed as less harmful alternatives to CS. In this study, we compared the effects of acute ECIG, HTP and CS exposure on the lungs of type II diabetes versus non-diabetic mice in an animal model.MethodsType II Diabetic (Diab) and Non-Diabetic (Non-Diab) mice were divided into Control, ECIG, HTP and CS groups. Animals were exposed for 6 hrs./day to either air, ECIG, HTP or CS for seven days. Lung injury was determined by a) histopathology, b) wet to dry ratio, c) albumin concentration in bronchoalveolar lavage fluid, d) expression of TNF-α, IL-6, and IL-1 β, e) reactive oxygen species production (ROS), and f) assessment of cellular apoptosis.ResultsLung histology revealed increased edema and inflammatory cells in diabetic mice exposed to ECIG, HTP and CS. The expression of Inflammatory mediators was, in general, more significant in the Diabetic groups as well. TNF-α expression, for example, was upregulated in Diab + ECIG but not in Non-Diab + ECIG. ROS was significantly increased in Diab + CS, less in Non-Diab + CS and weakly noted in ECIG + Diab. Significant albumin leak was observed in Diab and Non-Diab HTP-exposed animals. CS exposure worsened lung injury in Diab when compared to Non-Diab mice.ConclusionComorbid medical conditions like diabetes may amplify ill effects of CS, ECIG or HTP exposure.

Protectin D1 protects against lipopolysaccharide-induced acute lung injury through inhibition of neutrophil infiltration and the formation of neutrophil extracellular traps in lung tissue.

Protectin D1 (PD1), a DHA-derived lipid mediator, has recently been shown to possess anti-inflammatory and pro-resolving properties. To date, little is known about the effect of PD1 on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. The aim of the present study was to investigate the therapeutic effects of PD1 on LPS-induced ALI and its potential mechanisms of action. ALI was induced via an intraperitoneal injection of LPS, where PD1 (2 ng/mouse) was administered intravenously 30 min after LPS challenge. Mice were sacrificed 24 h after modeling. Lung histopathological changes were assessed using hematoxylin and eosin staining and myeloperoxidase (MPO) activity was tested using immunohistochemistry. Tumor necrosis-α and interleukin-6 levels in the bronchoalveolar lavage fluid (BALF) and serum were measured using ELISA. To detect neutrophil extracellular traps produced by infiltrated neutrophils in the lung tissue, immunofluorescence staining was performed using anti-MPO and anti-histone H3 antibodies. The results indicated that PD1 significantly attenuated histological damage and neutrophil infiltration in lung tissue, reduced the lung wet/dry weight ratio, protein concentration and proinflammatory cytokine levels in BALF and decreased proinflammatory cytokine levels in serum. Moreover, neutrophil citrullinated histone H3 (CitH3) expression was also reduced after PD1 administration. In conclusion, PD1 attenuated LPS-induced ALI in mice via inhibition of neutrophil extracellular trap formation in lung tissue. Therefore, PD1 administration may serve to be a new strategy for treating ALI.

Oxidative stress following acute kidney injury causes disruption of lung cell cilia and their release into the bronchoaveolar lavage fluid and lung injury, which are exacerbated by Idh2 deletion

Acute kidney injury (AKI) induces distant organ injury, which is a serious concern in patients with AKI. Recent studies have demonstrated that distant organ injury is associated with oxidative stress of organ and damage of cilium, an axoneme-based cellular organelle. However, the role of oxidative stress and cilia damage in AKI-induced lung injury remains to be defined. Here, we investigated whether AKI-induced lung injury is associated with mitochondrial oxidative stress and cilia disruption in lung cells. AKI was induced in isocitrate dehydrogenase 2 (Idh2, a mitochondrial antioxidant enzyme)-deleted (Idh2−/−) and wild-type (Idh2+/+) mice by kidney ischemia-reperfusion (IR). A group of mice were treated with Mito-TEMPO, a mitochondria-specific antioxidant. Kidney IR caused lung injuries, including alveolar septal thickening, alveolar damage, and neutrophil accumulation in the lung, and increased protein concentration and total cell number in bronchoalveolar lavage fluid (BALF). In addition, kidney IR caused fragmentation of lung epithelial cell cilia and the release of fragments into BALF. Kidney IR also increased the production of superoxide, lipid peroxidation, and mitochondrial and nuclei DNA oxidation in lungs and decreased IDH2 expression. Lung oxidative stress and injury relied on the degree of kidney injury. Idh2 deletion exacerbated kidney IR-induced lung injuries. Treatment with Mito-TEMPO attenuated kidney IR-induced lung injuries, with greater attenuation in Idh2−/− than Idh2+/+ mice. Our data demonstrate that AKI induces the disruption of cilia and damages cells via oxidative stress in lung epithelial cells, which leads to the release of disrupted ciliary fragments into BALF.

Mechanical Ventilation Exacerbates Poly (I:C) Induced Acute Lung Injury: Central Role for Caspase-11 and Gut-Lung Axis.

BackgroundThe mechanisms by which moderate tidal volume ventilation (MTV) exacerbates preexisting lung injury are unclear. We hypothesized that systemic endotoxemia via the gut-lung axis would lead to non-canonical and canonical inflammasome activation and pyroptosis in a two-hit model involving polyinosinic-polycytidylic acid (Poly(I:C)), a synthetic analog of dsRNA and MTV and that this would associate with acute lung injury (ALI).MethodsAnesthetized mice were administered Poly(I:C) intratracheally and then 6 h later, they were mechanically ventilated for 4 h with otherwise non-injurious MTV (10ml/kg). Changes in intestinal and alveolar capillary permeability were measured. Further documentation of ALI was assessed by evans blue albumin permeability, protein and IL-1 family concentration in bronchoalveolar lavage fluid (BALF) or plasma, and histopathology in cohorts of wildtype (WT), whole body genetically ablated caspase-11 (caspase-11-/-), caspase-1/caspase-11 double knockout (caspase-1/11-/-), gasdermin D (GSDMD)-/-, nucleotide-binding domain leucine-rich repeat-containing protein 3 (NLRP3)-/- and advanced glycosylation end product-specific receptor (RAGE) -/- mice.ResultsNon-injurious MTV exacerbated the mild lung injury associated with Poly(I:C) administration. This included the disruption of alveolar-capillary barrier and increased levels of interleukin (IL)-6, high mobility group proteins 1 (HMGB-1), IL-1β in BALF and IL-18 in plasma. Combined (Poly(I:C)-MTV) injury was associated with increase in gastrointestinal permeability and endotoxin in plasma and BALF. Poly(I:C)-MTV injury was sensitive to caspase-11 deletion with no further contribution of caspase-1 except for maturation and release of IL-18 (that itself was sensitive to deletion of NLRP3). Combined injury led to large increases in caspase-1 and caspase-11. Genetic ablation of GSDMD attenuated alveolar-capillary disruption and release of cytokines in combined injury model.ConclusionsThe previously noted exacerbation of mild Poly(I:C)-induced ALI by otherwise non-injurious MTV is associated with an increase in gut permeability resulting in systemic endotoxemia. The gut-lung axis resulted in activation of pulmonary non-canonical (cytosolic mediated caspase-11 activation) and canonical (caspase-1) inflammasome (NLRP3) mediated ALI in this two-hit model resulting in GSDMD sensitive alveolar capillary barrier disruption, pyroptosis (alveolar macrophages) and cytokine maturation and release (IL-1β; IL-18). Pharmacologic strategies aimed at disrupting communication between gut and lung, inhibition of inflammasomes or GSDMD in pyroptosis may be useful in ALI.

Smoking and Human Immunodeficiency Virus 1 Infection Promote Retention of CD8+ T Cells in the Airway Mucosa.

Smoking and human immunodeficiency virus 1 (HIV-1) infection are risk factors for chronic obstructive pulmonary disease (COPD), which is among the most common comorbid conditions in people living with HIV-1. HIV-1 infection leads to persistent expansion of CD8+ T cells, and CD8+ T cell-mediated inflammation has been implicated in COPD pathogenesis. In this study, we investigated the effects of HIV-1 infection and smoking on T-cell dynamics in patients at risk of COPD. BAL fluid, endobronchial brushings, and blood from HIV-1 infected and uninfected nonsmokers and smokers were analyzed by flow cytometry, and lungs were imaged by computed tomography. Chemokines were measured in BAL fluid, and CD8+ T-cell chemotaxis in the presence of cigarette smoke extract was assessed invitro. HIV-1 infection increased CD8+ T cells in the BAL fluid, but this increase was abrogated by smoking. Smokers had reduced BAL fluid concentrations of the T cell-recruiting chemokines CXCL10 and CCL5, and cigarette smoke extract inhibited CXCL10 and CCL5 production by macrophages and CD8+ T-cell transmigration invitro. In contrast to the T cells in BAL fluid, CD8+ T cells in endobronchial brushings were increased in HIV-1-infected smokers, which was driven by an accumulation of effector memory T cells in the airway mucosa and an increase in tissue-resident memory T cells. Mucosal CD8+ T-cell numbers inversely correlated with lung aeration, suggesting an association with inflammation and remodeling. HIV-1 infection and smoking lead to retention of CD8+ T cells within the airway mucosa.

The SARS-CoV-2 spike protein subunit S1 induces COVID-19-like acute lung injury in Κ18-hACE2 transgenic mice and barrier dysfunction in human endothelial cells.

Acute lung injury (ALI) leading to acute respiratory distress syndrome is the major cause of COVID-19 lethality. Cell entry of SARS-CoV-2 occurs via the interaction between its surface spike protein (SP) and angiotensin-converting enzyme-2 (ACE2). It is unknown if the viral spike protein alone is capable of altering lung vascular permeability in the lungs or producing lung injury in vivo. To that end, we intratracheally instilled the S1 subunit of SARS-CoV-2 spike protein (S1SP) in K18-hACE2 transgenic mice that overexpress human ACE2 and examined signs of COVID-19-associated lung injury 72 h later. Controls included K18-hACE2 mice that received saline or the intact SP and wild-type (WT) mice that received S1SP. K18-hACE2 mice instilled with S1SP exhibited a decline in body weight, dramatically increased white blood cells and protein concentrations in bronchoalveolar lavage fluid (BALF), upregulation of multiple inflammatory cytokines in BALF and serum, histological evidence of lung injury, and activation of signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways in the lung. K18-hACE2 mice that received either saline or SP exhibited little or no evidence of lung injury. WT mice that received S1SP exhibited a milder form of COVID-19 symptoms, compared with the K18-hACE2 mice. Furthermore, S1SP, but not SP, decreased cultured human pulmonary microvascular transendothelial resistance (TER) and barrier function. This is the first demonstration of a COVID-19-like response by an essential virus-encoded protein by SARS-CoV-2 in vivo. This model of COVID-19-induced ALI may assist in the investigation of new therapeutic approaches for the management of COVID-19 and other coronaviruses.

Diaphragm neurostimulation during mechanical ventilation reduces atelectasis and transpulmonary plateau pressure, preserving lung homogeneity and [Formula: see text]/[Formula: see text

Tidal volume delivered by mechanical ventilation to a sedated patient is distributed in a nonphysiological pattern, causing atelectasis (underinflation) and overdistension (overinflation). Activation of the diaphragm during controlled mechanical ventilation in these sedated patients may provide a method to reduce atelectasis and alveolar inhomogeneity, protecting the lungs from ventilator-induced lung injury while also protecting the diaphragm by preventing ventilator-induced diaphragm dysfunction. We studied the hypothesis that diaphragm contractions elicited by transvenous phrenic nerve stimulation, delivered in synchrony with volume-control ventilation, would reduce atelectasis and lung inhomogeneity in a healthy, normal lung pig model. Twenty-five large pigs were ventilated for 50 h with lung-protective volume-control ventilation combined with synchronous transvenous phrenic-nerve neurostimulation on every breath, or every second breath. This was compared to lung-protective ventilation alone. Lung mechanics and ventilation pressures were measured using esophageal pressure manometry and electrical impedance tomography. Alveolar homogeneity was measured using alveolar chord length of preserved lung tissue. Lung injury was measured using inflammatory cytokine concentration in bronchoalveolar lavage fluid and serum. We found that diaphragm neurostimulation on every breath preserved [Formula: see text]/[Formula: see text] and significantly reduced the loss of end-expiratory lung volume after 50 h of mechanical ventilation. Neurostimulation on every breath reduced plateau and driving pressures, improved both static and dynamic compliance and resulted in less alveolar inhomogeneity. These findings support that temporary transvenous diaphragm neurostimulation during volume-controlled, lung-protective ventilation may offer a potential method to provide both lung- and diaphragm-protective ventilation.NEW & NOTEWORTHY Temporary transvenous diaphragm neurostimulation has been shown to mitigate diaphragm atrophy in a preclinical model. This study contributes to this work by demonstrating that diaphragm neurostimulation can also offer lung protection from ventilator injury, providing a potential solution to the dilemma of lung- versus diaphragm-protective ventilation. Our findings show that neurostimulation on every breath preserved [Formula: see text]/[Formula: see text], end-expiratory lung volume, alveolar homogeneity, and required lower pressures than lung-protective ventilation over 50 h in healthy pigs.

Blocking SphK1/S1P/S1PR1 Signaling Pathway Alleviates Lung Injury Caused by Sepsis in Acute Ethanol Intoxication Mice.

Acute ethanol intoxication increases the risk of sepsis and aggravates the symptoms of sepsis and lung injury. Therefore, this study aimed to explore whether sphingosine kinase 1 (SphK1)/sphingosine-1-phosphate (S1P)/S1P receptor 1 (S1PR1) signaling pathway functions in lung injury caused by acute ethanol intoxication-enhanced sepsis, as well as its underlying mechanism. The acute ethanol intoxication model was simulated by intraperitoneally administering mice with 32% ethanol solution, and cecal ligation and puncture (CLP) was used to construct the sepsis model. The lung tissue damage was observed by hematoxylin-eosin (H&E) staining, and the wet-to-dry (W/D) ratio was used to evaluate the degree of pulmonary edema. Inflammatory cell counting and protein concentration in bronchoalveolar lavage fluid (BALF) were, respectively, detected by hemocytometer and bicinchoninic acid (BCA) method. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, and IL-18 in BALF were detected by their commercial enzyme-linked immunosorbent assay (ELISA) kits. The myeloperoxidase (MPO) activity and expression of apoptosis-related proteins and SphK1/S1P/S1PR1 pathway-related proteins were, respectively, analyzed by MPO ELISA kit and Western blot analysis. The cell apoptosis in lung tissues was observed by TUNEL assay. Acute ethanol intoxication (EtOH) decreased the survival rate of mice and exacerbated the lung injury caused by sepsis through increasing pulmonary vascular permeability, neutrophil infiltration, release of inflammatory factors, and cell apoptosis. In addition, EtOH could activate the SphK1/S1P/S1PR1 pathway in CLP mice. However, PF-543, as a specific inhibitor of SphK1, could partially reverse the deleterious effects on lung injury of CLP mice. PF-543 alleviated lung injury caused by sepsis in acute ethanol intoxication rats by suppressing the SphK1/S1P/S1PR1 signaling pathway.