Model Of Sepsis-induced Lung Injury Research Articles

Inhibiting caspase-3/GSDME-mediated pyroptosis ameliorates septic lung injury in mice model

Acute lung injury is one of the most serious complications of sepsis, which is a common critical illness in clinic. This study aims to investigate the role of caspase-3/ gasdermin-E (GSDME)-mediated pyroptosis in sepsis-induced lung injury in mice model. Cecal ligation (CLP) operation was used to establish mice sepsis-induced lung injury model. Lung coefficient, hematoxylin and eosin staining and transmission electron microscopy were used to observe the lung injury degree. In addition, caspase-3-specific inhibitor Z-DEVD-FMK and GSDME-derived inhibitor AC-DMLD-CMK were used in CLP model, caspase-3 activity, GSDME immunofluorescence, serum lactate dehydrogenase (LDH) and interleukin-6 (IL-6) levels, TUNEL staining, and the expression levels of GSDME related proteins were detected. The mice in CLP group showed the increased expressions of cleaved-caspase-3 and GSDME-N terminal, destruction of lung structure, and the increases of LDH, IL-6, IL-18 and IL-1β levels, which were improved in mice treated with Z-DEVD-FMK or AC-DMLD-CMK. In conclusion, caspase-3/GSDME mediated pyroptosis is involved in the occurrence of sepsis-induced lung injury in mice model, inhibiting caspase-3 or GSDME can both alleviate lung injury.

Regorafenib modulation of the angiopoietin/TIE2 axis in a mouse model of sepsis-induced lung injury.

Sepsis, often resulting from an immune response overreaction to microorganisms and their products, can lead to acute lung injury through inflammation mediated by excessive cytokines. This study aimed to investigate the effects of regorafenib on lung injury in mice following the induction of sepsis. We divided mice into four groups (n=6 each): a sham group (undergoing laparotomy without cecal ligation and puncture [CLP]), a CLP group, a vehicle group, and a regorafenib-treated group (30 mg/kg IP, administered one hour before CLP). TNF-α, IL-1β, VEGF, MPO, caspase-11, and Ang-2 levels were significantly increased (p<0.05) in the CLP group compared to the sham group, while the regorafenib group showed significant reductions in these markers versus the CLP group (p< 0.05). In contrast, Ang-1 levels, which were reduced in the CLP group (p<0.05) compared to the sham group, were elevated in the regorafenib group compared to the CLP group. Quantitative real-time PCR revealed a significant decrease in TIE2 and VE-cadherin mRNA expression in the lung tissue of the CLP group compared to the sham group. There were no significant differences in mRNA expression of the TIE2 gene between the regorafenib and CLP group. However, VE-cadherin significantly increased after regorafenib treatment. Regorafenib demonstrated lung-protective effects through its anti-inflammatory and antiangiogenic activities and its influence on lung tissue mRNA expression of the cadherin gene.

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.

Crosstalk of pyroptosis, ferroptosis, and mitochondrial aldehyde dehydrogenase 2-related mechanisms in sepsis-induced lung injury in a mouse model

ABSTRACT Acute lung injury (ALI) is a common complication of sepsis. Mitochondrial aldehyde dehydrogenase 2 (ALDH2), an enzyme involved in aldehyde metabolism, exerts a protective effect against sepsis. This study investigated the possible mechanisms underlying the roles of ALDH2, pyroptosis, and ferroptosis in sepsis-induced lung injury. A mouse model of sepsis-induced lung injury was established by cecal ligation and puncture (CLP); lung morphology was evaluated by calculation of lung coefficient, hematoxylin–eosin staining, and electron microscopy. Malondialdehyde (MDA), reactive oxygen species (ROS), and 4-hydroxy-2-nonenal (4-HNE) protein expression levels were used to detect the level of lipid oxidative stress. In addition, total iron was detected using an iron detection kit, and the expression of ferroptosis-related proteins (PTGS2, GPX4), pyroptosis-related proteins, and ALDH2 was examined using western blotting. To further examine the likely mechanisms, the ferroptosis inhibitor ferrostatin 1 (Fer-1), NLRP3 inflammasome inhibitor MCC950, and ALDH2 activator Alda-1 were added. CLP-treated mice exhibited destruction of lung tissue morphology, lipid peroxidation injury, iron content, and increased lung PTGS2 protein expression, accompanied by a decrease in GPX4 protein expression. CLP also downregulated ALDH2 expression and increased the expression of the NLRP3 inflammasome and pyroptosis-related proteins. These adverse effects of CLP were relieved by Alda-1, Fer-1, and MCC950 treatment. In conclusion, both pyroptosis and ferroptosis participate in CLP-induced ALI, and ALDH2 plays a protective role by reducing pyroptosis and ferroptosis. This study provides a scientific basis for the treatment of lung injury in sepsis.

Combating Complement's Deleterious Effects on Nanomedicine by Conjugating Complement Regulatory Proteins to Nanoparticles.

Complement opsonization is among the biggest challenges facing nanomedicine. Nearly instantly after injection into blood, nanoparticles are opsonized by the complement protein C3, leading to clearance by phagocytes, fouling of targeting moieties, and release of anaphylatoxins. While surface polymers such as poly(ethylene glycol) (PEG) partially decrease complement opsonization, most nanoparticles still suffer from extensive complement opsonization, especially when linked to targeting moieties. To ameliorate the deleterious effects of complement, two of mammals' natural regulators of complement activation (RCAs), Factors H and I, are here conjugated to the surface of nanoparticles. In vitro, Factor H or I conjugation to PEG-coated nanoparticles decrease their C3 opsonization, and markedly reduce nanoparticle uptake by phagocytes. In an in vivo mouse model of sepsis-induced lung injury, Factor I conjugation abrogates nanoparticle uptake by intravascular phagocytes in the lungs, allowing the blood concentration of the nanoparticle to remain elevated much longer. For nanoparticles targeted to the lung's endothelium by conjugation to anti-ICAM antibodies, Factor I conjugation shifts the cell-type distribution away from phagocytes and toward endothelial cells. Finally, Factor I conjugation abrogates the severe anaphylactoid responses common to many nanoparticles, preventing systemic capillary leak and preserving blood flow to visceral organs and the brain. Thus, conjugation of RCAs, like Factor I, to nanoparticles is likely to help in nanomedicine's long battle against complement, improving several key parameters critical for clinical success.

Tissue Factor-Enriched Neutrophil Extracellular Traps Promote Immunothrombosis and Disease Progression in Sepsis-Induced Lung Injury.

BackgroundPatients with sepsis may progress to acute respiratory distress syndrome (ARDS). Evidence of neutrophil extracellular traps (NETs) in sepsis-induced lung injury has been reported. However, the role of circulating NETs in the progression and thrombotic tendency of sepsis-induced lung injury remains elusive. The aim of this study was to investigate the role of tissue factor-enriched NETs in the progression and immunothrombosis of sepsis-induced lung injury.MethodsHuman blood samples and an animal model of sepsis-induced lung injury were used to detect and evaluate NET formation in ARDS patients. Immunofluorescence imaging, ELISA, Western blotting, and qPCR were performed to evaluate in vitro NET formation and tissue factor (TF) delivery ability. DNase, an anti-TF antibody, and thrombin inhibitors were applied to evaluate the contribution of thrombin to TF-enriched NET formation and the contribution of TF-enriched NETs to immunothrombosis in ARDS patients.ResultsSignificantly increased levels of TF-enriched NETs were observed in ARDS patients and mice. Blockade of NETs in ARDS mice alleviated disease progression, indicating a reduced lung wet/dry ratio and PaO2 level. In vitro data demonstrated that thrombin-activated platelets were responsible for increased NET formation and related TF exposure and subsequent immunothrombosis in ARDS patients.ConclusionThe interaction of thrombin-activated platelets with PMNs in ARDS patients results in local NET formation and delivery of active TF. The notion that NETs represent a mechanism by which PMNs release thrombogenic signals during thrombosis may offer novel therapeutic targets.

PD-L1 Regulates Inflammation in LPS-Induced Lung Epithelial Cells and Vascular Endothelial Cells by Interacting with the HIF-1α Signaling Pathway.

Sepsis-induced lung injury was the most common cause of death in patients. This study aimed to investigate whether PD-L1 regulates the inflammation in LPS-induced lung epithelial cells and vascular endothelial cells by interacting with the HIF-1α signaling pathway. Sepsis-induced lung injury mice were constructed by cecal ligation and puncture (CLP) procedure, and lipopolysaccharide (LPS)-induced lung epithelial cells and vascular endothelial cells simulate the sepsis-induced lung injury model in vitro. Hematoxylin-eosin (HE) staining detected the morphological changes of the lung tissues, and immunohistochemistry (IHC) detected the PD-L1 expression in lung tissues. Bicinchoninic acid (BCA) assay determined the protein concentration in bronchial alveolar lavage fluid (BALF). The number of PD-1 (+) cells in blood was detected by flow cytometry. The apoptosis in lung tissues and LPS-induced cells was analyzed by TUNEL assay. The inflammatory factor levels and HIF-1α in lung tissues and LPS-induced cells were analyzed by ELISA. The transfection effects of KD-PDL1 or KD-HIF1A in lung epithelial cells and vascular endothelial cells were confirmed by qRT-PCR analysis. The protein expression related to the PD-L1- and HIF-1α-related pathway was determined by Western blot analysis. As a result, LMT-28, as an IL-6 inhibitor, alleviated lung injury and suppressed the apoptosis and inflammation in lung tissues in BALF and the number of PD-1 (+) cells in blood. Sepsis-induced lung injury activated the PD-L1- and HIF-1α-related pathway, while LMT-28 could not completely inhibit the pathway. In addition, downregulation of PD-L1 or downregulation of HIF-1α suppressed the apoptosis and alleviated the inflammation in LPS-induced lung epithelial cells and vascular endothelial cells. Downregulation of PD-L1 had significant effects on lung epithelial cells but had greater effects on vascular endothelial cells. Downregulation of HIF-1α could decrease PD-L1 expression, and downregulation of PD-L1 could also suppress the protein expression of HIF-1α and related pathways. In conclusion, downregulation of PD-L1 alleviated the inflammation in LPS-induced lung epithelial cells and vascular endothelial cells by suppressing the HIF-1α signaling pathway.

RETRACTED: LncRNA NEAT1 inhibition upregulates miR-16-5p to restrain the progression of sepsis-induced lung injury via suppressing BRD4 in a mouse model

Long non-coding RNAs (lncRNAs) are known to sponge microRNAs (miRNAs) to regulate biological processes. However, the role of nuclear paraspeckle assembly transcript 1 (NEAT1) binding miR-16-5p in sepsis-induced lung injury remains largely unknown. We aim to explore the effect of NEAT1 sponging miR-16-5p on sepsis-induced lung injury via regulating bromodomain containing 4 (BRD4). A mouse model of sepsis-induced lung injury was established. Expression of NEAT1, miR-16-5p and BRD4 was determined. The pulmonary edema, myeloperoxidase (MPO) activity, pathological changes, levels of inflammatory factors, cell viability and apoptosis in mouse lung tissues were evaluated. The binding relationships between NEAT1 and miR-16-5p, and between miR-16-5p and BRD4 were confirmed. NEAT1 and BRD4 were upregulated while miR-16-5p was downregulated in sepsis-induced lung injury. NEAT1 inhibition or miR-16-5p elevation suppressed pulmonary edema, MPO activity, pathological changes, inflammation and apoptosis, and promoted cell viability in mouse lung tissues. NEAT1 bound with miR-16-5p and miR-16-5p targeted BRD4. NEAT1 inhibition upregulates miR-16-5p to repress the progression of sepsis-induced lung injury via downregulating BRD4.

Protective Effect of Zuojin Fang on Lung Injury Induced by Sepsis through Downregulating the JAK1/STAT3 Signaling Pathway.

Lung injury was the common and serious complication of sepsis, a systemic inflammatory response syndrome caused by severe infections. Chinese medicine had unique advantages in attenuating inflammatory response, such as Zuojinfang (ZJF). ZJF was a classical compound herb formula composed of Coptidis Rhizoma and Euodiae Fructus in a ratio of 6 : 1. In this paper, 15 ingredients in ZJF were identified and 8 of them absorbed into rat's serum were quantified by HPLC-MS/MS. Subsequently, sepsis-induced lung injury model was replicated in rats by cecal ligation and puncture. 60 SD rats were randomly divided into 6 groups (n = 10): control group (CON), sham group (Sham), model group (MOD), ZJF low-dose group (ZJF-L), ZJF high-dose group (ZJF-H), and prednisolone group (PNSL). Within the next 24 h, the levels of inflammatory factors, correlation between active ingredients and inflammatory cytokines, the pathological changes of lung tissue, and protein expression of the JAK1/STAT3 signaling pathways were analyzed one by one. Finally, the concentration order of components absorbed in rat serum was berberine > palmatine > jatrorrhizine > coptisine > evodin > chlorogenic acid > evodiamine. Compared with the MOD group, the TNF-α, IL-6, and IFN-γ in the ZJF-H group were significantly reduced (p < 0.05). Moreover, the TNF-α decreased significantly accompanied by the increase of berberine, chlorogenic acid, jatrorrhizine, palmatine, evodin, and evodiamine in serum (negative correlation, p < 0.05). Compared with the MOD, the area of lung injury, the expressions of JAK1, p-JAK1, STAT3, and p-STAT3 were significantly decreased under the treatment of ZJF (p < 0.05). Therefore, downregulating the JAK1/STAT3 signaling pathways was a potential avenue of ZJF in reversing lung injury induced by sepsis.

Effect of miR-132 on lung injury in sepsis rats via regulating Sirt1 expression.

The aim of this study was to explore the effects of the expressions of micro ribonucleic acid (miR)-132 and sirtuin1 (Sirt1) on lung injury in sepsis rats, and to elucidate the regulatory relation between miR-132 and Sirt1. The model of sepsis-induced lung injury was successfully established in rats via injection of lipopolysaccharide (LPS) into the caudal vein (model group). Before modeling, the rats were infused with miR-132 antagomir via the trachea (miR-132 antagomir group) or intraperitoneally injected with the Sirt1 activator (SRT1720) (SRT1720 group). Meanwhile, the rats injected with an equal volume of normal saline via the caudal vein were enrolled in the control group. The expressions of the inflammatory factors interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) were determined using enzyme-linked immunosorbent assay (ELISA). Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) and Western blotting were applied to detect gene and protein expressions in lung tissues, respectively. Targeted relationship between miR-132 and Sirt1 was explored using Luciferase reporter assay. In addition, tissue sections of the right lung were stained with hematoxylin-eosin (HE) to observe the degree of lung injury. The model of sepsis-induced lung injury was successfully established in rats by LPS. The results showed that the expressions of IL-6, IL-1β, TNF-α and miR-132 rose significantly in lung tissues (p<0.01), whereas the expression of Sirt1 significantly declined (p<0.01). Lung injury was alleviated by miR-132 antagomir and SRT1720. Both miR-132 antagomir and SRT1720 significantly reduced the expressions of miR-132, IL-6, IL-1β and TNF-α (p<0.01). However, the expression of Sirt1 was remarkably upregulated in rats with lung injury (p<0.01). Luciferase reporter gene assay indicated that miR-132 regulated Sirt1 in a targeted manner. MiR-132 may cause lung injury in sepsis rats by regulating the expression of Sirt1.

Maresin1 ameliorates acute lung injury induced by sepsis through regulating Th17/Treg balance

The disturbance of the immune homeostasis caused by infection is decisive for multiple organ dysfunction caused by sepsis. Both the th17 cell and the regulatory cell(Tregs) are important components of the immune system and play a crucial role in maintaining immune homeostasis. In this study, we explored the effect of Maresin1, an emerging specific pro-inflammatory mediator, on the balance of Th17/Treg in sepsis, and investigated the underlying mechanism. We used the male C57BL/6 mice to establish the model of sepsis-induced lung injury by cecal ligation and puncture to verify the protective effect of Maresin1. Our study showed that Maresin1 could significantly inhibit the excessive inflammatory response and promote the inflammation regression in the process of sepsis-induced acute lung injury, thereby reducing lung damage and improving lung function. These effects were accompanied with the regulation of Maresin1 on the Th17/Treg balance in the early stages of sepsis. We demonstrated that Maresin1 has a certain effect on increasing the number of Treg and decreasing the number of Th17 cells in the early stages of sepsis, which is consistent with its effect on STAT3/RORγt and STAT5/Foxp3 signal pathways. Our study elucidated for the first time the relationship between Maresin1 and Th17/Treg balance in sepsis-induced acute lung injury.

Down-regulation of lncRNA CASC9 aggravates sepsis-induced acute lung injury by regulating miR-195-5p/PDK4 axis.

Long non-coding RNA (lncRNA) cancer susceptibility candidate 9 (CASC9) is reported to be linked to cancers. This research aims to explore the role and possible mechanism of CASC9 in lung injury induced by sepsis. Lipopolysaccharide (LPS) induced human small airway epithelial cells (HSAECs) were established in vitro to mimic sepsis-induced lung injury. The effects of CASC9 and miR-195-5p on HSAECs viability were studied by CCK-8 assay. Interactions between CASC9 and miR-195-5p were determined by bioinformatics analysis, RT-PCR, dual luciferase reporter assay, and RNA immunoprecipitation assay. Pyruvate dehydrogenase kinase 4 (PDK4) and apoptosis-related molecules including Bcl2 and Bad were detected by western blot. Additionally, sepsis-induced lung injury model in rats was established by intraperitoneal injection of LPS in vivo to validate the demonstrations of in vitro studies. CASC9 was markedly down-regulated while miR-195-5p was significantly up-regulated in HSAECs treated by LPS and lung tissues of rats with sepsis. CASC9 interacted with miR-195-5p, and negatively regulated its expression level. Overexpression of CASC9 or transfection of miR-195-5p inhibitors significantly promoted the viability of HSAECs. The transfection of miR-195-5p mimics effected oppositely. For mechanism, miR-195-5p targeted the 3'UTR of pyruvate dehydrogenase kinase 4 (PDK4) gene and depressed the protein level, and PDK4 was regulated indirectly by CASC9. Restoration of CASC9 in the lung tissues of rats with sepsis ameliorated lung injury. CASC9 protects lung epithelial cells from sepsis-induced injury via regulating miR-195-5p/PDK4 axis.

The Effects of Dexmedetomidine in a Rat Model of Sepsis-Induced Lung Injury are Mediated Through the Adenosine Monophosphate-Activated Protein Kinase (AMPK)/Silent Information Regulator 1 (SIRT1) Pathway.

BackgroundThis study aimed to investigate the effects of dexmedetomidine in a rat model of sepsis-induced lung injury and the role of the adenosine monophosphate-activated protein kinase (AMPK) gene and silent information regulator 1 (SIRT1) gene signaling pathway.Material/MethodsSixty 28-week-old healthy male Sprague-Dawley rats were randomly divided into three groups, the sham group, the model group, and the dexmedetomidine-treated group. The rat model of sepsis-induced lung injury was developed by surgical cecal ligation and puncture. Lung tissues examined histologically in the three study groups. Cell apoptosis was measured using the TUNEL assay, and the expression of inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-10 were measured in rat lung tissue by enzyme-linked immunosorbent assay (ELISA). Apoptosis-associated proteins and AMPK/SIRT1 pathway-associated protein expression levels were detected using Western blot.ResultsDexmedetomidine significantly increased the survival rate and reduced the body temperature of rats in the model group with sepsis-induced lung injury, reduced lung injury, significantly reduced apoptosis in lung tissues, and reduced the expression levels of TNF-α, and IL-1β, and increased the levels of IL-10. Dexmedetomidine significantly reduced the expression of caspase-3 in the rat lung tissue (P<0.01), and significantly increased the expression of Bcl-2/Bax and the phosphorylation levels of AMPK, SIRT1, nuclear factor-κB (NF-κB), and forkhead box class O 3a (FOXO3a).ConclusionsIn a rat model of sepsis-induced lung injury, dexmedetomidine reduced lung damage by activating the AMPK/SIRT1 signaling pathway and reduced the expression of inflammatory cytokines and cell apoptosis.

Mitochondrial DNA plays an important role in lung injury induced by sepsis.

The effects and mechanisms of mitochondrial DNA (mtDNA) in the development of sepsis-induced lung injury is not well understood. In our present study, we studied the mtDNA effects in sepsis-induced lung injury model,in vitro and in vivo. Compared with the Normal group, the lung histopathological score, the number of positive apoptosis cell, wet/dry (W/D) ratio and TNF-α, IL-1β, and IL-6 concentrations of lipopolysaccharides (LPSs) and mtDNA groups were significantly increased (P < 0.001, respectively). Meanwhile, the lung histopathological score, positive W/D ratio, number of apoptosis cell and tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 concentrations of LPS + mtDNA and small interfering RNA (siRNA)-NC + LPS + mtDNA groups were significantly upregulated compared with those of LPS group (P < 0.05, respectively). However, the lung histopathological score, the number of positive apoptosis cell, W/D ratio and TNF-α, IL-1β, and IL-6 concentrations were significantly improved within the toll-like receptor (TLR9)siRNA + LPS + mtDNA group compared with the LPS group (P < 0.01, respectively). The TLR9, MyD88, and NF-κB proteins or gene expressions of the LPS group and mtDNA group were significantly upregulated compared with those of Normal group by Western blot analysis or immunohistochemistry assay (P < 0.01, respectively), and the TLR9, MyD88, and NF-κB proteins or gene expressions of LPS + mtDNA and siRNA-NC + LPS + mtDNA groups were significantly enhanced compared with those of LPS group (P < 0.05, respectively). However, the TLR9, MyD88, and NF-κB proteins or gene expressions of TLR9siRNA + LPS + mtDNA group were significantly suppressed compared with those of the LPS group (P < 0.01, respectively). In conclusion, mtDNA could provoke lung injury induced by sepsis via regulation of TLR9/MyD88/NF-κB pathway in vitro and in vivo.

In vivo lung perfusion rehabilitates sepsis-induced lung injury

BackgroundSepsis is the leading cause of lung injury in adults and can lead to acute respiratory distress syndrome (ARDS). Using a novel technique of isolated in vivo lung perfusion (IVLP), we hypothesized that normothermic IVLP will improve oxygenation and compliance in a porcine model of sepsis-induced lung injury. MethodsMature adult swine (n = 8) were administered lipopolysaccharide (LPS; 50 μg/kg over 2 hours) via the external jugular vein, followed by sternotomy and central extracorporeal membrane oxygenation (ECMO) cannulation (right atrium to ascending aorta). The left pulmonary artery (inflow) and left superior and inferior pulmonary veins (outflow) were dissected out and cannulated to deliver isolated perfusion to the left lung. After 4 hours of normothermic IVLP with Steen solution, the left lung then underwent 4 hours of reperfusion after IVLP decannulation. Airway pressures and lung-specific pulmonary vein blood gases from the right lung (LPS control) and left lung (LPS + IVLP) of the same animal were compared. ResultsAll animals demonstrated a significant reduction in the ratio of partial pressure of oxygen in arterial blood (PaO2)/fraction of inspired oxygen (FiO2) (P/F ratio) and total lung compliance at 2 hours after the start of LPS infusion (mean, 469 ± 19.7 mm Hg vs 222.2 ± 21.4 mm Hg; P < .0001). After reperfusion, 6 animals (75%) exhibited improved lung function, allowing for ECMO decannulation. Lung-specific oxygenation was superior in the left lung after 4 hours of reperfusion (mean, 310.5 ± 54.7 mm Hg vs 201.1 ± 21.7 mm Hg; P = .01). Similarly, total lung compliance improved after IVLP of the left lung. The lung wet weight to dry weight ratio demonstrated reduced edema in rehabilitated left lungs (mean, 6.5 ± 0.3 vs 7.5 ± 0.4; P = .04). ConclusionsIVLP successfully rehabilitated LPS-injured lungs compared to ECMO support alone in this preclinical porcine model.

XOR inhibition with febuxostat accelerates pulmonary endothelial barrier recovery and improves survival in lipopolysaccharide-induced murine sepsis.

Sepsis is a leading cause of death among patients in the intensive care unit, resulting from multi‐organ failure. Activity of xanthine oxidoreductase (XOR), a reactive oxygen species (ROS) producing enzyme, is known to be elevated in nonsurvivors of sepsis compared to survivors. We have previously demonstrated that XOR is critical for ventilator‐induced lung injury. Using febuxostat, a novel nonpurine inhibitor of XOR, we sought to determine the role of XOR inhibition in a murine model of sepsis‐induced lung injury and mortality. C57BL/6J mice were subjected to intravenous (IV) lipopolysaccharide (LPS) for various time points, and lungs were harvested for analyses. Subsets of mice were treated with febuxostat, pre or post LPS exposure, or vehicle. Separate groups of mice were followed up for mortality after LPS exposure. After 24 hr of IV LPS , mice exhibited an increase in XOR activity in lung tissue and a significant increase in pulmonary endothelial barrier disruption. Pretreatment of animals with febuxostat before exposure to LPS, or treatment 4 h after LPS, resulted in complete abrogation of XOR activity. Inhibition of XOR with febuxostat did not prevent LPS‐induced pulmonary vascular permeability at 24 h, however, it accelerated recovery of the pulmonary endothelial barrier integrity in response to LPS exposure. Furthermore, treatment with febuxostat resulted in significant reduction in mortality. Inhibition of XOR with febuxostat accelerates recovery of the pulmonary endothelial barrier and prevents LPS‐induced mortality, whether given before or after exposure to LPS.

Ex Vivo Lung Perfusion Rehabilitates Sepsis-Induced Lung Injury

Sepsis is the number one cause of lung injury in adults. Exvivo lung perfusion (EVLP) is gaining clinical acceptance for donor lung evaluation and rehabilitation and may expand the use of marginal organs for transplantation. We hypothesized that 4 hours of normothermic EVLP would improve compliance and oxygenation in a porcine model of sepsis-induced lung injury. We used intravenous lipopolysaccharide (LPS) to induce a systemic inflammatory response in a porcine model of lung injury. Two groups of 4 animals each received a 2-hour infusion of LPS through the external jugular vein. Serial measurements of blood gases were performed every 30 minutes until the partial pressure of oxygen/fraction of inspired oxygen ratio dropped below 150 on two consecutive readings. Lungs were then randomized to treatment with 4 hours of normothermic EVLP with STEEN Solution (XVIVO Perfusion Inc, Englewood, CO) or 4 additional hours of invivo perfusion (control). Airway pressures and blood gases were recorded for calculation of dynamic lung compliance and partial pressure of oxygen/fraction of inspired oxygen ratios. EVLP was performed with hourly recruitment maneuvers and oxygen challenge. All animals reached a partial pressure of oxygen/fraction of inspired oxygen ratio of less than 150 mm Hg within 3 hours after start of the LPS infusion. Oxygenation and compliance in the control animals continued to decline during the 4-hour invivo perfusion period, and 3 of the 4 animals died of severe hypoxia within 4 hours. The EVLP group demonstrated significant improvements hour 1 to hour 4 in oxygenation (365.8 ± 53.0 vs 584.4 ± 21.0 mm Hg, p= 0.02) and dynamic compliance (9.0 ± 2.8 vs 15.0 ± 3.6, p= 0.02 mL/cm H2O). EVLP successfully rehabilitated LPS-induced lung injury in this preclinical porcine model and may thus provide a means to rehabilitate many types of acute lung injury.

Nicotinamide Adenine Dinucleotide Phosphate Oxidase 2 Regulates LPS-Induced Inflammation and Alveolar Remodeling in the Developing Lung.

In premature infants, sepsis is associated with alveolar simplification manifesting as bronchopulmonary dysplasia. The redox-dependent mechanisms underlying sepsis-induced inflammation and alveolar remodeling in the immature lung remain unclear. We developed a neonatal mouse model of sepsis-induced lung injury to investigate whether nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) regulates Toll-like receptor (TLR)-mediated inflammation and alveolar remodeling. Six-day-old NOX2+/+ and NOX2-/- mice were injected with intraperitoneal LPS to induce sepsis. Lung inflammation and canonical TLR signaling were assessed 24 hours after LPS. Alveolar development was examined in 15-day-old mice after LPS on Day 6. The in vivo efficacy of a NOX2 inhibitor (NOX2-I) on NOX2 complex assembly and sepsis-induced lung inflammation were examined. Lung cytokine expression and neutrophil influx induced with sepsis in NOX2+/+ mice was decreased by >50% in NOX2-/- mice. LPS-induced TLR4 signaling evident by inhibitor of NF-κB kinase-β and mitogen-activated protein kinase phosphorylation, and nuclear factor-κB/AP-1 translocation were attenuated in NOX2-/- mice. LPS increased matrix metalloproteinase 9 while decreasing elastin and keratinocyte growth factor levels in NOX2+/+ mice. An LPS-induced increase in matrix metalloproteinase 9 and decrease in fibroblast growth factor 7 and elastin were not evident in NOX2-/- mice. An LPS-induced reduction in radial alveolar counts and increased mean linear intercepts were attenuated in NOX2-/- mice. LPS-induced NOX2 assembly evident by p67phox/gp91phox coimmunoprecipitation was disrupted with NOX2-I. NOX2-I also mitigated LPS-induced cytokine expression, TLR pathway signaling, and alveolar simplification. In a mouse model of neonatal sepsis, NOX2 regulates proinflammatory TLR signaling and alveolar remodeling induced by a single dose of LPS. Our results provide mechanistic insight into the regulation of sepsis-induced alveolar remodeling in the developing lung.

Vitamin D deficiency and bacterial load in a murine model of sepsis-induced lung injury

BackgroundWe have previously shown that patients with acute lung injury are severely vitamin D deficient. Several studies have reported a high prevalence of vitamin D deficiency in critically ill patients with sepsis, associated with increased morbidity and mortality, but whether this association is cause or effect is unknown. Bacteraemic sepsis is more common in the winter months when serum vitamin D concentrations are lowest. The purpose of this study was to investigate the local and systemic effects of vitamin D deficiency in a murine model of sepsis-induced lung injury where we can predictably time the initiating insult. MethodsWe fed eight wild-type C57BL/6 mice a diet completely devoid of vitamin D for 6 weeks to induce severe vitamin D deficiency (serum concentration 9 nmol/L) and compared them with seven mice fed a vitamin D sufficient diet (42 nmol/L). We used caecal ligation and puncture (CLP) to establish sepsis. Animals were culled 16 h after CLP, and blood, peritoneal lavage fluid (PLF), and bronchoalveloar lavage fluid (BALF) were collected. Cell infiltrates were assessed by flow cytometry. Fluid protein concentrations were measured, and tissue protein permeability index was calculated as the ratio between fluid and serum protein. Bacterial load was evaluated as colony-forming units (CFU) per ml after 24 h incubation on appropriate media. Statistical analysis was done with Minitab 16 statistical software. FindingsVitamin D deficient mice had significantly increased bacterial load compared with dietary sufficient mice in BALF, blood, and PLF (BALF median 2·51 × 103 CFU per mL [IQR 0·65 × 103–1097 ×103] vs 0·51 ×103 [0·0–1·15 × 103], p=0·038; blood 66·1 × 103 [1·93 × 103–175 × 103] vs 0·56 × 103 [0·0–5·56 × 103], p=0·042; and PLF 336 × 103 [52 × 103–115 × 105] vs 8·22 × 103 [1·54 ×103–20·6 × 103], p=0·005). BALF protein permeability index was higher in deficient mice than in sufficient mice (median 3·3 [IQR 2·61–4·64] vs 1·8 [1·22–2·09], p=0·0003) but there was no difference in cell numbers recruited to the lung. PLF protein permeability index was also higher in the deficient group than in sufficient mice (46·8 [28·1–59·3] vs 27·2 [14·2–37·3], p=0·05), with an associated increase in neutrophils recruited to the peritoneum (p=0·04). InterpretationVitamin D deficiency significantly increased the bacterial load systemically, locally, and within the lung in a murine model of peritonitis. This increase was associated with a rise in tissue permeability locally and within the lung. These data support pre-existing vitamin D deficiency as a determinant of the severity of bacteraemic sepsis and might account for some of the seasonal variations observed in the incidence of sepsis. FundingUK Medical Research Council.

S98 Vitamin D deficiency increases bacterial load in a murine model of sepsis-induced lung injury

IntroductionWe have previously shown that patients with Acute Lung Injury (ALI) are severely vitamin D deficient. Several studies have reported a high prevalence of vitamin D deficiency in critically ill...