Physiologic, biochemical, and imaging characterization of acute lung injury in mice

The extracellular cyclophilin A-integrin β2 complex as a therapeutic target of viral pneumonia

The acute respiratory virus infection can induce uncontrolled inflammatory responses, such as cytokine storm and viral pneumonia, which are the major causes of death in clinical cases. Cyclophilin A (CypA) is mainly distributed in the cytoplasm of resting cells and released into the extracellular space in response to inflammatory stimuli. Extracellular CypA (eCypA) is upregulated and promotes inflammatory response in severe COVID-19 patients. However, how eCypA promotes virus-induced inflammatory response remains elusive. Here, we observe that eCypA is induced by influenza A and B viruses and SARS-CoV-2 in cells, mice, or patients. Anti-CypA mAb reduces pro-inflammatory cytokines production, leukocytes infiltration, and lung injury in virus-infected mice. Mechanistically, eCypA binding to integrin β2 triggers integrin activation, thereby facilitating leukocyte trafficking and cytokines production via the focal adhesion kinase (FAK)/GTPase and FAK/ERK/P65 pathways, respectively. These functions are suppressed by the anti-CypA mAb that specifically blocks eCypA-integrin β2 interaction. Overall, our findings reveal that eCypA-integrin β2 signaling mediates virus-induced inflammatory response, indicating that eCypA is a potential target for antibody therapy against viral pneumonia.

PROTAC targeting cyclophilin A controls virus-induced cytokine storm

Cytokine storms caused by viruses are associated with elevated cytokine levels and uncontrolled inflammatory responses that can lead to acute respiratory distress syndrome. Current antiviral therapies are not sufficient to prevent or treat these complications. Cyclophilin A (CypA) is a key factor that regulates the production of multiple cytokines and could be a potential therapeutic target for cytokine storms. Here, three proteolysis targeting chimeras (PROTACs) targeting CypA were designed. These PROTACs bind to CypA, enhance its ubiquitination, and promote its degradation in both cell lines and mouse organs. During influenza B virus (IBV) infection, PROTAC-mediated CypA depletion reduces P65 phosphorylation and NF-κB-mediated proinflammatory cytokine production in A549 cells. Moreover, Comp-K targeting CypA suppresses excessive secretion of proinflammatory cytokines in bronchoalveolar lavage fluid, reduces lung injury, and enhances survival rates of IBV-infected mice. Collectively, we provide PROTACs targeting CypA, which are potential candidates for the control of cytokine storms.

A long-lasting porcine model of ARDS caused by pneumonia and ventilator-induced lung injury

BACKGROUND

Animal models of acute respiratory distress syndrome (ARDS) do not completely resemble human ARDS, struggling translational research. We aimed to characterize a porcine model of ARDS induced by pneumonia-the most common risk factor in humans-and analyze the additional effect of ventilator-induced lung injury (VILI).

METHODS

Bronchoscopy-guided instillation of a multidrug-resistant Pseudomonas aeruginosa strain was performed in ten healthy pigs. In six animals (pneumonia-with-VILI group), pulmonary damage was further increased by VILI applied 3 h before instillation and until ARDS was diagnosed by PaO2/FiO2 < 150 mmHg. Four animals (pneumonia-without-VILI group) were protectively ventilated 3 h before inoculum and thereafter. Gas exchange, respiratory mechanics, hemodynamics, microbiological studies and inflammatory markers were analyzed during the 96-h experiment. During necropsy, lobar samples were also analyzed.

RESULTS

All animals from pneumonia-with-VILI group reached Berlin criteria for ARDS diagnosis until the end of experiment. The mean duration under ARDS diagnosis was 46.8 ± 7.7 h; the lowest PaO2/FiO2 was 83 ± 5.45 mmHg. The group of pigs that were not subjected to VILI did not meet ARDS criteria, even when presenting with bilateral pneumonia. Animals developing ARDS presented hemodynamic instability as well as severe hypercapnia despite high-minute ventilation. Unlike the pneumonia-without-VILI group, the ARDS animals presented lower static compliance (p = 0.011) and increased pulmonary permeability (p = 0.013). The highest burden of P. aeruginosa was found at pneumonia diagnosis in all animals, as well as a high inflammatory response shown by a release of interleukin (IL)-6 and IL-8. At histological examination, only animals comprising the pneumonia-with-VILI group presented signs consistent with diffuse alveolar damage.

CONCLUSIONS

In conclusion, we established an accurate pulmonary sepsis-induced ARDS model.

Antioxidants as Therapeutic Agents in Acute Respiratory Distress Syndrome (ARDS) Treatment-From Mice to Men

Acute respiratory distress syndrome (ARDS) is a major cause of patient mortality in intensive care units (ICUs) worldwide. Considering that no causative treatment but only symptomatic care is available, it is obvious that there is a high unmet medical need for a new therapeutic concept. One reason for a missing etiologic therapy strategy is the multifactorial origin of ARDS, which leads to a large heterogeneity of patients. This review summarizes the various kinds of ARDS onset with a special focus on the role of reactive oxygen species (ROS), which are generally linked to ARDS development and progression. Taking a closer look at the data which already have been established in mouse models, this review finally proposes the translation of these results on successful antioxidant use in a personalized approach to the ICU patient as a potential adjuvant to standard ARDS treatment.

Changes in TNF-α, IL-6, IL-10 and VEGF in rats with ARDS and the effects of dexamethasone

Changes in tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-10 and vascular endothelial growth factor (VEGF) in serum and bronchoalveolar lavage fluid (BALF) in rats with acute respiratory distress syndrome (ARDS) and the intervention effect of dexamethasone were observed to explore the theoretical basis of dexamethasone in the treatment of ARDS. Seventy-two rats were randomly divided into normal control group (group N, n=24), ARDS model group (group L, n=24) and dexamethasone group (group D, n=24). The ARDS rat model was established by jointly injecting oleic acid and lipopolysaccharide via the caudal vein, while rats in group D received intervention with dexamethasone. The wet/dry weight ratios of lung tissues were measured, and the levels of TNF-α, IL-6, IL-10 and VEGF in serum and BALF were measured via enzyme-linked immunosorbent assay. The wet/dry weight ratio of lung tissues of rats in group D was significantly decreased compared with that in group L (P<0.05 or P<0.01). The levels of TNF-α, IL-6 and VEGF in serum and BALF of rats in group L and D were obviously increased compared with those in group N at each time point (P<0.01). The levels of TNF-α, IL-6 and VEGF in serum and BALF of rats in group D were significantly decreased compared with those in group L (P<0.01). In conclusion, there is a serious imbalance between anti-inflammatory response and inflammatory response in rats with ARDS induced by oleic acid combined with lipopolysaccharide of Escherichia coli, whereas dexamethasone can alleviate lung injury through inhibiting expression levels of inflammatory factors and promoting expression levels of anti-inflammatory factors.

Novel imaging approaches for small animal models of lung disease (2017 Grover Conference series)

Imaging in small animal models of lung disease is challenging, as existing technologies are limited either by resolution or by the terminal nature of the imaging approach. Here, we describe the current state of small animal lung imaging, the technological advances of laboratory-sourced phase contrast X-ray imaging, and the application of this novel technology and its attendant image analysis techniques to the in vivo imaging of the large airways and pulmonary vasculature in murine models of lung health and disease.

Protective effects of neurotensins on lipopolysaccaride-induced acute lung injury by blocking tachykinin mediated pathway

Neurotensin, a bioactive tridecapeptide, has been shown to regulate inflammatory process in lung tissues. However, the effect of neurotensin on LPS-induced lung injury and underlying detailed molecular mechanisms has not been studied. The aim of present study is to investigate the effect of neurotensin on LPS-induced acute lung injury in mice. Mice were treated with LPS intratracheally to induce acute lung injury. 1 hour after ALI induction, and then mice were treated with neurotensins (NTs) (20 mg/kg, 40 mg/kg, and 80 mg/kg) via tail vein injection. Next, the severity of lung injury, MPO activity, neutrophils infiltration, lung edema, protein and pro-inflammatory cytokines concentration in BALF were determined to evaluate the effect of Nts on ALI. Additionally, the expression of tachykinins receptors, including NK1, NK2, and NK3 and the production of IL-8, COX-2, and PGE₂ mediated by tachykinins-tachykinins receptors pathway were determined to investigate the blocking effect of Nts on tachykinins and its receptors pathway. Neurotensins treatment significantly decreased the lung edema and the infiltration of inflammatory cells into lung tissue caused by LPS induction. Meanwhile, the elevation of pro-inflammatory cytokines and chemokine in BALF was dramatically reduced by neurotensins treatment. Furthermore, neurotensins could interact with tachykinins receptors and block the inflammatory responses activated by tachykinins pathways. In summary, neurotensins has a potentially protective effect on LPS-induced acute lung injury through the interaction with tachykinins receptors and subsequently blocking the inflammatory responses induced by activation of tachykinins pathway.

Dual hit lipopolysaccharide & oleic acid combination induced rat model of acute lung injury/acute respiratory distress syndrome

Background & objectives:

Despite advances in therapy and overall medical care, acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) management remains a problem. Hence the objective of this study was to develop a rat model that mimics human ALI/ARDS.

Methods:

Four groups of Wistar rats, 48 per group were treated with (i) intratracheal (IT) lipopolysaccharide (LPS) (5 mg/kg) dissolved in normal saline (NS), (ii) intravenous (iv) oleic acid (OA) (250 μl/kg) suspension in bovine serum albumin (BSA), (iii) dual hit: IT LPS (2 mg/kg) dissolved in NS and iv OA (100 μl/kg) and (iv) control group: IT NS and iv BSA. From each group at set periods of time various investigations like chest X-rays, respiratory rate (RR), tidal volume (TV), total cell count, differential cell count, total protein count and cytokine levels in bronchoalveolar lavage fluid (BALF), lung wet/dry weight ratio and histopathological examination were done.

Results:

It was noted that the respiratory rate, and tumour necrosis factor-α (TNF-α) levels were significantly higher at 4 h in the dual hit group as compared to LPS, OA and control groups. Interleukin-6 (IL-6) levels were significantly higher in the dual hit group as compared to LPS at 8 and 24 h, OA at 8 h and control (at all time intervals) group. IL-1β levels were significantly higher in LPS and dual hit groups at all time intervals, but not in OA and control groups. The injury induced in dual hit group was earlier and more sustained as compared to LPS and OA alone.

Interpretation & conclusions:

The lung pathology and changes in respiration functions produced by the dual hit model were closer to the diagnostic criteria of ALI/ARDS in terms of clinical manifestations and pulmonary injury and the injury persisted longer as compared to LPS and OA single hit model. Therefore, the ARDS model produced by the dual hit method was closer to the diagnostic criteria of ARDS in terms of clinical manifestations and pulmonary injury.

PET/CT in nononcological lung diseases: current applications and future perspectives

Positron emission tomography (PET) combined with computed tomography (CT) is an established diagnostic modality that has become an essential imaging tool in oncological practice. However, thanks to its noninvasive nature and its capability to provide physiological information, the main applications of this technique have significantly expanded.(18)F-labelled fluorodeoxyglucose (FDG) is the most commonly used radiopharmaceutical for PET scanning and demonstrates metabolic activity in various tissues. Since activated inflammatory cells, like malignant cells, predominantly metabolise glucose as a source of energy and increase expression of glucose transporters when activated, FDG-PET/CT can be successfully used to detect and monitor a variety of lung diseases, such as infections and several inflammatory conditions.The added value of FDG-PET/CT as a molecular imaging technique relies on its capability to identify disease in very early stages, long before the appearance of structural changes detectable by conventional imaging. Furthermore, by detecting the active phase of infectious or inflammatory processes, disease progression and treatment efficacy can be monitored.This review will focus on the clinical use of FDG-PET/CT in nonmalignant pulmonary diseases.

Strong correlation between lung ultrasound and chest computerized tomography imaging for the detection of acute lung injury/acute respiratory distress syndrome in rats

BACKGROUND

Lung ultrasound (LUS) is a clinical imaging technique for diagnosing acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In humans and several large animals, LUS demonstrates similar specificity and sensitivity to computerized tomography (CT) scanning. Current study evaluated the degree of agreement between LUS and CT imaging in characterizing ALI/ARDS in rats.

METHODS

Thirty male Sprague-Dawley rats were imaged by LUS before randomization into three groups to receive intratracheal saline, 3 or 6 mg/kg LPS respectively (n=10). LUS and CT imaging was conducted 2 hours after instillation. Cross table analyses and kappa statistics were used to determine agreement levels between LUS and CT assessments of lung condition.

RESULTS

Before instillation, rats presented with a largely A-pattern in LUS images, however, a significantly increase B-lines were observed in all groups after instillation and showed dose response to LPS or to saline. One rat treated with 6 mg/kg lipopolysaccharide (LPS) presented with lung consolidation. The agreement between the LUS and the CT in detecting the main characteristics of ALI/ARDS in rat was strong (r=0.758, P<0.01, k=0.737).

CONCLUSIONS

In conclusion, LUS detects ALI/ARDS with high agreement with micro PET/CT scanning in a rat model, suggesting that LUS represents a positive refinement in rat ALI/ARDS disease models.

Rutin improves endotoxin-induced acute lung injury via inhibition of iNOS and VCAM-1 expression

Endotoxins exist anywhere including in water pools, dust, humidifier systems, and machining fluids. The major causal factor is endotoxins in many serious diseases, such as fever, sepsis, multi-organ failure, meningococcemia, and severe morbidities like neurologic disability, or hearing loss. Endotoxins are also called lipopolysaccharide (LPS) and are important pathogens of acute lung injury (ALI). Rutin has potential beneficial effects including anti-inflammation, antioxidation, anti-hyperlipidemia, and anti-platelet aggregation. Pre-treatment with rutin inhibited LPS-induced neutrophil infiltration in the lungs. LPS-induced expression of vascular cell adhesion molecule (VCAM)-1 and inducible nitric oxide synthase (iNOS) was suppressed by rutin, but there was no influence on expression of intercellular adhesion molecule-1 and cyclooxygenase-2. In addition, activation of the nuclear factor (NF)κB was reduced by rutin. Furthermore, we found that the inhibitory concentration of rutin on expression of VCAM-1 and iNOS was similar to NFκB activation. In conclusion, rutin is a potential protective agent for ALI via inhibition of neutrophil infiltration, expression of VCAM-1 and iNOS, and NFκB activation.

Glucocorticoids limit acute lung inflammation in concert with inflammatory stimuli by induction of SphK1

Acute lung injury (ALI) is a severe inflammatory disease for which no specific treatment exists. As glucocorticoids have potent immunosuppressive effects, their application in ALI is currently being tested in clinical trials. However, the benefits of this type of regimen remain unclear. Here we identify a mechanism of glucocorticoid action that challenges the long-standing dogma of cytokine repression by the glucocorticoid receptor. Contrarily, synergistic gene induction of sphingosine kinase 1 (SphK1) by glucocorticoids and pro-inflammatory stimuli via the glucocorticoid receptor in macrophages increases circulating sphingosine 1-phosphate levels, which proves essential for the inhibition of inflammation. Chemical or genetic inhibition of SphK1 abrogates the therapeutic effects of glucocorticoids. Inflammatory p38 MAPK- and mitogen- and stress-activated protein kinase 1 (MSK1)-dependent pathways cooperate with glucocorticoids to upregulate SphK1 expression. Our findings support a critical role for SphK1 induction in the suppression of lung inflammation by glucocorticoids, and therefore provide rationales for effective anti-inflammatory therapies.

Endothelial damage is a major component of acute lung injury pathogenesis. Here the authors show that in a mouse model of acute lung injury, glucocorticoids induce sphingosine kinase 1 production in macrophages, promoting endothelial barrier function and ameliorating the disease.

Characterization of spontaneous air space enlargement in mice lacking microfibrillar-associated protein 4

Microfibrillar-associated protein 4 (MFAP4) is localized to elastic fibers in blood vessels and the interalveolar septa of the lungs and is further present in bronchoalveolar lavage. Mfap4 has been previously suggested to be involved in elastogenesis in the lung. We tested this prediction and aimed to characterize the pulmonary function changes and emphysematous changes that occur in Mfap4-deficient (Mfap4(-/-)) mice. Significant changes included increases in total lung capacity and compliance, which were evident in Mfap4(-/-) mice at 6 and 8 mo but not at 3 mo of age. Using in vivo breath-hold gated microcomputed tomography (micro-CT) in 8-mo-old Mfap4(-/-) mice, we found that the mean density of the lung parenchyma was decreased, and the low-attenuation area (LAA) was significantly increased by 14% compared with Mfap4(+/+) mice. Transmission electron microscopy (TEM) did not reveal differences in the organization of elastic fibers, and there was no difference in elastin content, but a borderline significant increase in elastin mRNA expression in 3-mo-old mice. Stereological analysis showed that alveolar surface density in relation to the lung parenchyma and total alveolar surface area inside of the lung were both significantly decreased in Mfap4(-/-) mice by 25 and 15%, respectively. The data did not support an essential role of MFAP4 in pulmonary elastic fiber organization or content but indicated increased turnover in young Mfap4(-/-) mice. However, Mfap4(-/-) mice developed a spontaneous loss of lung function, which was evident at 6 mo of age, and moderate air space enlargement, with emphysema-like changes.

Protective effects of protocatechuic acid on acute lung injury induced by lipopolysaccharide in mice via p38MAPK and NF-κB signal pathways

The study aims to investigate the effects of protocatechuic acid (PCA) separated from Chinese herbs, on acute lung injury (ALI) induced by lipopolysaccharide (LPS) in mice. The mouse model was induced by intraperitoneal injection of LPS at the dose of 5mg/kg body weight. Three doses of PCA (30, 15, 5 mg/kg) were administered to mice with intraperitoneal injection one hour prior to LPS exposure. Six hours later after LPS administration, the effect of PCA on ALI mice was assessed via histopathological examination by HE staining, inflammatory cytokine production by ELISA assay and RT-PCR, p38MAPK and NF-κB activation by Western blot analysis. We found that PCA administration significantly ameliorated lung histopathological changes and decreased protein concentration in the bronchoalveolar lavage fluid. Furthermore, the overproduction of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) was reduced by PCA. Additionally, PCA at the dose of 30 mg/kg could block the activation of p38MAPK and NF-κB signal pathways induced by LPS. In conclusion, our findings demonstrate that PCA possesses a protective effect on LPS-induced ALI in mice via suppression of p38MAPK and NF-κB signal pathways. Therefore, PCA may be useful in the therapy of lung inflammatory diseases, especially for ALI.

The impact of pretreatment with bolus dose of enteral glutamine on acute lung injury induced by oleic acid in rats

PURPOSE

Both parenteral and enteral glutamine have shown beneficial effects in sepsis and ischemia/reperfusion-induced acute lung injury (ALI). Oleic acid (OA) has been used to induce ALI in experimental studies. In this study, we investigated the effects of pretreatment of a bolus dose of enteral glutamine on ALI induced by OA in rats.

METHODS

Twenty-eight adult female Sprague-Dawley rats weighing 240-300 g were divided into four groups, 7 in each. Group I and group II received normal saline for 30 days, group III and group IV received glutamine at a dose of 1 g/kg for 10 days by gavage, and in group II and group IV 100 mg/kg OA was administered i.v. Histopathological examination of the lung was performed with light and electron microscopy. Levels of protein carbonyl, malondialdehyde, superoxide dismutase, catalase, and glutathione peroxidase levels were measured in tissue samples. Levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, and total tissue oxidant status and total tissue antioxidant status were measured in serum samples.

RESULTS

Light microscopy showed that the total lung injury score of group IV was significantly lower than group II. Change in thickness of the fused basal lamina was not significantly different in groups II and IV under electron microscopy. TNF-α, IL-6, and IL-10 serum levels were higher in group II when compared to group I and significantly attenuated in group IV.

CONCLUSION

Pretreatment with a bolus dose of enteral glutamine minimized the extent of ALI induced by OA in rats.

Targeting toll-like receptors: promising therapeutic strategies for the management of sepsis-associated pathology and infectious diseases

Toll-like receptors (TLRs) are pattern recognition receptors playing a fundamental role in sensing microbial invasion and initiating innate and adaptive immune responses. TLRs are also triggered by danger signals released by injured or stressed cells during sepsis. Here we focus on studies developing TLR agonists and antagonists for the treatment of infectious diseases and sepsis. Positioned at the cell surface, TLR4 is essential for sensing lipopolysaccharide of Gram-negative bacteria, TLR2 is involved in the recognition of a large panel of microbial ligands, while TLR5 recognizes flagellin. Endosomal TLR3, TLR7, TLR8, TLR9 are specialized in the sensing of nucleic acids produced notably during viral infections. TLR4 and TLR2 are favorite targets for developing anti-sepsis drugs, and antagonistic compounds have shown efficient protection from septic shock in pre-clinical models. Results from clinical trials evaluating anti-TLR4 and anti-TLR2 approaches are presented, discussing the challenges of study design in sepsis and future exploitation of these agents in infectious diseases. We also report results from studies suggesting that the TLR5 agonist flagellin may protect from infections of the gastrointestinal tract and that agonists of endosomal TLRs are very promising for treating chronic viral infections. Altogether, TLR-targeted therapies have a strong potential for prevention and intervention in infectious diseases, notably sepsis.

Acute lung injury and pulmonary vascular permeability: use of transgenic models

Acute lung injury is a general term that describes injurious conditions that can range from mild interstitial edema to massive inflammatory tissue destruction. This review will cover theoretical considerations and quantitative and semi-quantitative methods for assessing edema formation and increased vascular permeability during lung injury. Pulmonary edema can be quantitated directly using gravimetric methods, or indirectly by descriptive microscopy, quantitative morphometric microscopy, altered lung mechanics, high-resolution computed tomography, magnetic resonance imaging, positron emission tomography, or x-ray films. Lung vascular permeability to fluid can be evaluated by measuring the filtration coefficient (Kf) and permeability to solutes evaluated from their blood to lung clearances. Albumin clearances can then be used to calculate specific permeability-surface area products (PS) and reflection coefficients (σ). These methods as applied to a wide variety of transgenic mice subjected to acute lung injury by hyperoxic exposure, sepsis, ischemia-reperfusion, acid aspiration, oleic acid infusion, repeated lung lavage, and bleomycin are reviewed. These commonly used animal models simulate features of the acute respiratory distress syndrome, and the preparation of genetically modified mice and their use for defining specific pathways in these disease models are outlined. Although the initiating events differ widely, many of the subsequent inflammatory processes causing lung injury and increased vascular permeability are surprisingly similar for many etiologies.

Hydroxysafflor yellow A suppresses oleic acid-induced acute lung injury via protein kinase A

Inflammation response and oxidative stress play important roles in acute lung injury (ALI). Activation of the cAMP/protein kinase A (PKA) signaling pathway may attenuate ALI by suppressing immune responses and inhibiting the generation of reactive oxygen species (ROS). Hydroxysafflor yellow A (HSYA) is a natural flavonoid compound that reduces oxidative stress and inflammatory cytokine-mediated damage. In this study, we examined whether HSYA could protect the lungs from oleic acid (OA)-induced injury, which was used to mimic ALI, and determined the role of the cAMP/PKA signaling pathway in this process. Arterial oxygen tension (PaO2), carbon dioxide tension, pH, and the PaO2/fraction of inspired oxygen ratio in the blood were detected using a blood gas analyzer. We measured wet/dry lung weight ratio and evaluated tissue morphology. The protein and inflammatory cytokine levels in the bronchoalveolar lavage fluid and serum were determined using enzyme-linked immunoassay. The activities of superoxide dismutase, glutathione peroxidase, PKA, and nicotinamide adenine dinucleotide phosphate oxidase, and the concentrations of cAMP and malondialdehyde in the lung tissue were detected using assay kits. Bcl-2, Bax, caspase 3, and p22(phox) levels in the lung tissue were analyzed using Western blotting. OA increased the inflammatory cytokine and ROS levels and caused lung dysfunction by decreasing cAMP synthesis, inhibiting PKA activity, stimulating caspase 3, and reducing the Bcl-2/Bax ratio. H-89 increased these effects. HSYA significantly increased the activities of antioxidant enzymes, inhibited the inflammatory response via cAMP/PKA pathway activation, and attenuated OA-induced lung injury. Our results show that the cAMP/PKA signaling pathway is required for the protective effect of HSYA against ALI.

Efficacy of aerosolized celecoxib encapsulated nanostructured lipid carrier in non-small cell lung cancer in combination with docetaxel

PURPOSE

Evaluation of in-vivo anticancer activity of aerosolized Celecoxib encapsulated Nanolipidcarriers (Cxb-NLC) as a single therapeutic agent and combined with intravenously administered Docetaxel (Doc) against non-small cell lung cancer.

METHODS

Cxb-NLC were prepared by high-pressure homogenization and were characterized for its physicochemical characteristics. Metastatic A549 tumor model in Nu/Nu mice was used to evaluate response of aerosolized Cxb-NLC & Doc. Isolated lung tumor samples were analyzed for: a) DNA fragmentation and cleaved caspase-3 by immunohistochemistry, b) apoptotic and angiogenic protein markers by western blot, c) global proteomic alterations by an isobaric labeling quantitative proteomic method and d) toxicity studies of NLC.

RESULTS

The particle size of Cxb-NLC was 217 ± 20 nm, while entrapment efficiency was more than 90%. Cxb-NLC and Doc alone and in combination showed 25 ± 4%, 37 ± 5%, and 67 ± 4% reduction in tumor size respectively compared to control. Proteomic analysis with combination treatment further revealed significantly decreased expression of multiple pro-survival and pro-metastasis proteins as well as tumor invasion markers and the expression of S100 family proteins, such as S100A6 and S100P were decreased by 2.5 and 1.6 fold.

CONCLUSIONS

Combination therapy with Cxb-NLC and Doc showed significant reduction in tumor growth which was further confirmed by proteomic analysis.

Isoflurane induces learning impairment that is mediated by interleukin 1β in rodents

Postoperative cognitive decline is a clinical syndrome. Volatile anesthetics are commonly used during surgery. It is conceivable that volatile anesthetics may contribute to postoperative cognitive decline. Isoflurane can impair cognitive functions of animals under certain conditions. However, the mechanisms for this impairment are not clear. Here, male 18-month old Fisher 344 rats or 10-week old mice were exposed to 1.2 or 1.4% isoflurane for 2 h. Our studies showed that isoflurane impaired the cognitive functions of the rats in Barnes maze. Isoflurane-exposed rats had reduced freezing behavior during the training sessions in the fear conditioning test. This isoflurane effect was attenuated by lidocaine, a local anesthetic with anti-inflammatory property. Rats that had training sessions and were exposed to isoflurane 30 min later had freezing behavior similar to that of control animals. Isoflurane increased the expression of interleukin 1β (IL-1β), interleukin-6 and activated caspase 3 in the hippocampus of the 18-month old rats. IL-1β positive staining was co-localized with that of NeuN, a neuronal marker. The increase of IL-1β and activated caspase 3 but not interleukin-6 was attenuated by lidocaine. Isoflurane also impaired the cognitive functions of 10-week old C57BL/6J mice and increased IL-1β in their hippocampi. However, isoflurane did not affect the cognitive functions of IL-1β deficient mice. Our results suggest that isoflurane impairs the learning but may not affect the recall of the aged rats. IL-1β may play an important role in this isoflurane effect.

Time course of metabolic activity and cellular infiltration in a murine model of acid-induced lung injury

PURPOSE

This study investigates whether positron emission tomography (PET) can be used to monitor the inflammatory response and its correlation with the later fibroproliferative phase in an experimental model of acute lung injury.

METHODS

Hydrochloric acid (0.1 N, pH 1, 1.5 ml/kg) was instilled into the right bronchus of mice. A group of mice underwent a micro-computed tomography (CT) scan 1 h after lung injury and a series of 2-[(18)F]fluorine-2-deoxy-D: -glucose (FDG)-PET scans (6, 24 and 48 h and 7 days after surgery). After 21 days respiratory static compliance was assessed and lung tissue was collected in order to measure the hydroxy (OH)-proline content. Other groups of mice underwent micro-CT and micro-PET scans at the same time points, and then were immediately killed to assess arterial blood gases and histology.

RESULTS

Histological analysis showed the recruitment of neutrophils and macrophages into the damaged lung, reaching the peak at 24 and 48 h, respectively. The time course of the [(18)F]FDG signal, used as a marker of inflammation, correlated with that of recruited inflammatory cells. In mice killed 21 days after the surgery, a correlation was found between reduced respiratory static compliance and high PET signal 7 days after lung injury. The PET signal also correlated with the OH-proline content.

CONCLUSIONS

This study demonstrated that PET imaging is a valid means of tracking the inflammatory response, also in longitudinal studies. Moreover, a correlation was found between persistence of the inflammatory response and fibrotic evolution of the injury.

IL-33 is processed into mature bioactive forms by neutrophil elastase and cathepsin G

Interleukin-33 (IL-33) (NF-HEV) is a chromatin-associated nuclear cytokine from the IL-1 family, which has been linked to important diseases, including asthma, rheumatoid arthritis, ulcerative colitis, and cardiovascular diseases. IL-33 signals through the ST2 receptor and drives cytokine production in type 2 innate lymphoid cells (ILCs) (natural helper cells, nuocytes), T-helper (Th)2 lymphocytes, mast cells, basophils, eosinophils, invariant natural killer T (iNKT), and natural killer (NK) cells. We and others recently reported that, unlike IL-1β and IL-18, full-length IL-33 is biologically active independently of caspase-1 cleavage and that processing by caspases results in IL-33 inactivation. We suggested that IL-33, which is released upon cellular damage, may function as an endogenous danger signal or alarmin, similar to IL-1α or high-mobility group box 1 protein (HMGB1). Here, we investigated the possibility that IL-33 activity may be regulated by proteases released during inflammation. Using a combination of in vitro and in vivo approaches, we demonstrate that neutrophil serine proteases cathepsin G and elastase can cleave full-length human IL-33(1-270) and generate mature forms IL-33(95-270), IL-33(99-270), and IL-33(109-270). These forms are produced by activated human neutrophils ex vivo, are biologically active in vivo, and have a ~10-fold higher activity than full-length IL-33 in cellular assays. Murine IL-33 is also cleaved by neutrophil cathepsin G and elastase, and both full-length and cleaved endogenous IL-33 could be detected in the bronchoalveolar lavage fluid in an in vivo model of acute lung injury associated with neutrophil infiltration. We propose that the inflammatory microenvironment may exacerbate disease-associated functions of IL-33 through the generation of highly active mature forms.

Luteolin Suppresses Inflammatory Mediator Expression by Blocking the Akt/NFκB Pathway in Acute Lung Injury Induced by Lipopolysaccharide in Mice

Acute lung injury (ALI), instilled by lipopolysaccharide (LPS), is a severe illness with excessive mortality and has no specific treatment strategy. Luteolin is an anti-inflammatory flavonoid and widely distributed in the plants. Pretreatment with luteolin inhibited LPS-induced histological changes of ALI and lung tissue edema. In addition, LPS-induced inflammatory responses, including increased vascular permeability, tumor necrosis factor (TNF)-α and interleukin (IL)-6 production, and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), were also reduced by luteolin in a concentration-dependent manner. Furthermore, luteolin suppressed activation of NFκB and its upstream molecular factor, Akt. These results suggest that the protection mechanism of luteolin is by inhibition of NFκB activation possibly via Akt.

Resolution of acute lung injury and inflammation: a translational mouse model

Previous animal models of acute lung injury (ALI) are limited as they only reproduce part of the complex pathobiology of clinical ALI. Here we develop a translational mouse model of ALI, which not only reflects the major clinical and pathological features but also enables investigation into ALI resolution. Anaesthetised mice underwent orotracheal instillation of hydrochloric acid. During the immediate period after instillation, mice were carefully maintained with supplemental oxygen to avoid mortality. At specified time-points, lung injury was assessed by analysis of blood gases, respiratory mechanics, bronchoalveolar lavage fluid, alveolar fluid clearance and lung histology. Animals exhibited significant weight loss, decreased oxygenation, increased respiratory elastance and pulmonary inflammation (intra-alveolar leukocyte influx/cytokine levels and histological injury scores). Moreover, mice displayed alveolar-capillary barrier dysfunction/epithelial injury as reflected by increased alveolar protein, lung wet/dry weight ratio and soluble receptor for advanced glycation end-products, as well as reduced alveolar fluid clearance. These injury parameters peaked between days 1 and 3, followed by almost complete recovery over days 5-10. Histology showed evidence of fibrosis on day 10. The results indicate that this resolving model of acid aspiration represents a powerful experimental tool to investigate the injurious, inflammatory, fibrotic, and resolving and reparative processes of ALI.

The monocrotaline model of pulmonary hypertension in perspective

Severe forms of pulmonary arterial hypertension (PAH) are characterized by various degrees of remodeling of the pulmonary arterial vessels, which increases the pulmonary vascular resistance and right ventricular afterload, thus contributing to the development of right ventricle dysfunction and failure. Recent years have seen advances in the understanding of the pathobiology of PAH; however, many important questions remain unanswered. Elucidating the pathobiology of PAH continues to be critical to design new effective therapeutic strategies, and appropriate animal models of PAH are necessary to achieve the task. Although the monocrotaline rat model of PAH has contributed to a better understanding of vascular remodeling in pulmonary hypertension, we question the validity of this model as a preclinically relevant model of severe plexogenic PAH. Here we review pertinent publications that either have been forgotten or ignored, and we reexamine the monocrotaline model in the context of human forms of PAH.

Eritoran tetrasodium (E5564) treatment for sepsis: review of preclinical and clinical studies

INTRODUCTION

Sepsis remains a leading cause of death worldwide. Despite years of extensive research, effective drugs that inhibit the pro-inflammatory effects of lipopolysaccharide (LPS) and improve outcome when added to conventional sepsis treatments are lacking. Eritoran tetrasodium (E5564) is a promising candidate therapy for sepsis belonging to a new class of such drugs which inhibit LPS-induced inflammation by blocking toll-like receptor 4.

AREAS COVERED

This review focuses on the rationale for the use of eritoran tetrasodium in sepsis as well as on its pharmacokinetics, pharmacodynamics, efficacy and safety. Preclinical and clinical studies from a MEDLINE/PubMed literature search in August 2010 with the search terms 'eritoran' and 'E5564' are discussed.

EXPERT OPINION

Preclinical in vitro and in vivo studies of eritoran tetrasodium indicate it can limit excessive inflammatory mediator release associated with LPS and improve survival in sepsis models. While early clinical results are promising, its efficacy and safety for treating patients with sepsis are currently under investigation. Even if the ongoing Phase III clinical trial enrolling patients with severe sepsis and increased risk of death shows benefit from eritoran, questions remain and confirmatory studies would be necessary to define its clinical usage.

Lung regional metabolic activity and gas volume changes induced by tidal ventilation in patients with acute lung injury

RATIONALE

During acute lung injury (ALI), mechanical ventilation can aggravate inflammation by promoting alveolar distension and cyclic recruitment-derecruitment. As an estimate of the intensity of inflammation, metabolic activity can be measured by positron emission tomography imaging of [(18)F]fluoro-2-deoxy-D-glucose.

OBJECTIVES

To assess the relationship between gas volume changes induced by tidal ventilation and pulmonary metabolic activity in patients with ALI.

METHODS

In 13 mechanically ventilated patients with ALI and relatively high positive end-expiratory pressure, we performed a positron emission tomography scan of the chest and three computed tomography scans: at mean airway pressure, end-expiration, and end-inspiration. Metabolic activity was measured from the [(18)F]fluoro-2-deoxy-D-glucose uptake rate. The computed tomography scans were used to classify lung regions as derecruited throughout the respiratory cycle, undergoing recruitment-derecruitment, and normally aerated.

MEASUREMENTS AND MAIN RESULTS

Metabolic activity of normally aerated lung was positively correlated both with plateau pressure, showing a pronounced increase above 26 to 27 cm H(2)O, and with regional Vt normalized by end-expiratory lung gas volume. This relationship did not appear to be caused by a higher underlying parenchymal metabolic activity in patients with higher plateau pressure. Regions undergoing cyclic recruitment-derecruitment did not have higher metabolic activity than those collapsed throughout the respiratory cycle.

CONCLUSIONS

In patients with ALI managed with relatively high end-expiratory pressure, metabolic activity of aerated regions was associated with both plateau pressure and regional Vt normalized by end-expiratory lung gas volume, whereas no association was found between cyclic recruitment-derecruitment and increased metabolic activity.

Gene expression profiles characterize inflammation stages in the acute lung injury in mice

Acute Lung Injury (ALI) carries about 50 percent mortality and is frequently associated with an infection (sepsis). Life-support treatment with mechanical ventilation rescues many patients, although superimposed infection or multiple organ failure can result in death. The outcome of a patient developing sepsis depends on two factors: the infection and the pre-existing inflammation. In this study, we described each stage of the inflammation process using a transcriptional approach and an animal model. Female C57BL6/J mice received an intravenous oleic acid injection to induce an acute lung injury (ALI). Lung expression patterns were analyzed using a 9900 cDNA mouse microarray (MUSV29K). Our gene-expression analysis revealed marked changes in the immune and inflammatory response metabolic pathways, notably lipid metabolism and transcription. The early stage (1 hour–1.5 hours) is characterized by a pro-inflammatory immune response. Later (3 hours–4 hours), the immune cells migrate into inflamed tissues through interaction with vascular endothelial cells. Finally, at late stages of lung inflammation (18 hours–24 hours), metabolism is deeply disturbed. Highly expressed pro-inflammatory cytokines activate transcription of many genes and lipid metabolism. In this study, we described a global overview of critical events occurring during lung inflammation which is essential to understand infectious pathologies such as sepsis where inflammation and infection are intertwined. Based on these data, it becomes possible to isolate the impact of a pathogen at the transcriptional level from the global gene expression modifications resulting from the infection associated with the inflammation.

Safety of prolonged, repeated administration of a pulmonary formulation of tissue plasminogen activator in mice

BACKGROUND

Disruption of fibrinolytic homeostasis participates in the pathogenesis of severe lung diseases like acute respiratory distress syndrome (ARDS), idiopathic pulmonary fibrosis (IPF) and plastic bronchitis. We have developed a pulmonary formulation of tissue plasminogen activator (pf-tPA) that withstands nebulization and reaches the lower airways.

OBJECTIVE

Since treatment of ARDS, IPF and plastic bronchitis will require repeated administration of pf-tPA, the purpose of this study was to determine the safety of prolonged, repeated administration of pf-mouse tPA (pf-mtPA) to the lungs of healthy mice.

METHODS

Male and female B6C3F1 mice received one of two intratracheal (IT) doses of either nebulized pf-mtPA or sterile saline twice daily for 28 days. Weekly blood samples were collected to estimate hematocrit. Following the dosing period, animals were sacrificed for gross necropsy, the acquisition of bronchoalveolar lavage fluid (BALF), and histological assessment of the lungs and other major organs.

RESULTS

The low dose of pf-mtPA was well tolerated by both female and male mice. However, female and male mice that received the high dose experienced a 16% and 8% incidence, respectively, of fatal pulmonary hemorrhage. Although male mice had a lower incidence of bleeding, these events occurred at lower mean (+/-S.E.) doses (1.06+/-0.02mg/kg/d) of pf-mtPA compared with females (1.48+/-0.03mg/kg/d, p<0.001). In addition, male mice had higher BALF mtPA concentrations. Bleeding occurred six and 12 days in male and female mice, respectively, after the initiation of dosing suggesting that mtPA accumulated in the lungs.

CONCLUSION

This study established a safe dose range and demonstrated the feasibility of prolonged, repeated dosing of pf-tPA. High doses (> or =1mg/kg/d) were associated with pulmonary hemorrhage that may be due, in part, to accumulation of drug in the lungs.

Inhibition of the phosphatase PTEN protects mice against oleic acid-induced acute lung injury

BACKGROUND AND PURPOSE

Injury to the lung parenchyma is a constitutional feature shared by many lung diseases. The protein, phosphatase and tensin homologue deleted on chromosome Ten (PTEN) is a major suppressor of phosphoinositide-3 kinase/Akt signalling, a vital survival pathway in lung parenchymal cells. Based on this, we hypothesized that PTEN inhibition in vivo would enhance cell tolerance to stress thereby preventing acute lung injury.

EXPERIMENTAL APPROACH

We evaluated the ability of a PTEN inhibitor, potassium bisperoxo (1,10-phenanthroline) oxovanadate [bpV(phen)], to prevent acute lung injury induced by oleic acid (OA) in adult C57BL/6 mice. Lung assessments included bronchoalveolar lavage, tissue morphology, immunostaining for markers of cell death, cell identity, phospho-Akt and phospho-ERK levels and oximetry.

KEY RESULTS

OA induced acute lung injury in a dose- and time-dependent manner. No injury was observed in the vehicle control or bpV(phen) treatment groups. PTEN inhibition by bpV(phen) increased lung tissue levels of phospho-Akt and ERK and but not focal adhesion kinase. This occurred in conjunction with a statistically significant reduction in protein content, lactate dehydrogenase, as well as tumour necrosis factor-alpha and chemokines in bronchoalveolar lavage fluid when compared with OA treatment alone. The incidence of alveolar lesions, consistent with acute lung injury, and terminal uridine deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)-positive cells was also significantly reduced. Importantly, PTEN suppression maintained pulmonary function.

CONCLUSIONS AND IMPLICATIONS

Treatment with bpV(phen) significantly reduced the severity of acute lung injury in mice indicating that additional investigation is warranted to understand the important role that this phosphatase may play in the lung.

Characterization of a murine model of monocrotaline pyrrole-induced acute lung injury

Background

New animal models of chronic pulmonary hypertension in mice are needed. The injection of monocrotaline is an established model of pulmonary hypertension in rats. The aim of this study was to establish a murine model of pulmonary hypertension by injection of the active metabolite, monocrotaline pyrrole.

Methods

Survival studies, computed tomographic scanning, histology, bronchoalveolar lavage were performed, and arterial blood gases and hemodynamics were measured in animals which received an intravenous injection of different doses of monocrotaline pyrrole.

Results

Monocrotaline pyrrole induced pulmonary hypertension in Sprague Dawley rats. When injected into mice, monocrotaline pyrrole induced dose-dependant mortality in C57Bl6/N and BALB/c mice (dose range 6–15 mg/kg bodyweight). At a dose of 10 mg/kg bodyweight, mice developed a typical early-phase acute lung injury, characterized by lung edema, neutrophil influx, hypoxemia and reduced lung compliance. In the late phase, monocrotaline pyrrole injection resulted in limited lung fibrosis and no obvious pulmonary hypertension.

Conclusion

Monocrotaline and monocrotaline pyrrole pneumotoxicity substantially differs between the animal species.

Inhibition of corneal inflammation by the TLR4 antagonist Eritoran tetrasodium (E5564)

PURPOSE

To investigate the role of the TLR4/MD-2 antagonist eritoran tetrasodium in a murine model of contact lens-associated corneal infiltrates.

METHODS

C57BL/6 mouse corneas were abraded and treated with eritoran tetrasodium or placebo, either before or after stimulation with either LPS, the TLR2 ligand Pam(3)Cys, or antibiotic-killed Pseudomonas aeruginosa. A 2-mm punch from a silicon hydrogel contact lens was used to cover the corneal surface throughout the inhibition and stimulation period. Corneal infiltrates were detected by in vivo confocal microscopy and by immunohistochemistry for neutrophils. The effect of eritoran tetrasodium on stimulated human corneal epithelial cells (HCECs), macrophages, and neutrophils was also assessed.

RESULTS

Eritoran tetrasodium significantly inhibited CXC chemokine production in the cornea and development of corneal infiltrates, specifically neutrophils, in response to stimulation with LPS (TLR4), but not Pam(3)Cys (TLR2). When the antagonist was applied after LPS stimulation, neutrophil infiltration was also inhibited, although a higher concentration was needed. Furthermore, IL-8 production by TLR4- but not TLR2-stimulated HCECs, macrophages and neutrophils was also significantly reduced. Corneal inflammation induced by P. aeruginosa in the presence of tobramycin was found to be dependent on expression of TLR4 and MD-2 and is inhibited by eritoran tetrasodium.

CONCLUSIONS

Eritoran tetrasodium is a highly effective antagonist of TLR4/MD-2-dependent corneal inflammation.

Effects of vascular flow and PEEP in a multiple hit model of lung injury in isolated perfused rabbit lungs

BACKGROUND

High vascular flow aggravates lung damage in animal models of ventilator-induced lung injury. Positive end-expiratory pressure (PEEP) can attenuate ventilator-induced lung injury, but its continued effectiveness in the setting of antecedent lung injury is unclear. The objective of the present study was to evaluate whether the application of PEEP diminishes lung injury induced by concurrent high vascular flow and high alveolar pressures in normal lungs and in a preinjury lung model.

METHODS

Two series of experiments were performed. Fifteen sets of isolated rabbit lungs were randomized into three groups (n = 5): low vascular flow/low PEEP; high vascular flow/low PEEP, and high vascular flow/high PEEP. Subsequently, the same protocol was applied in an additional 15 sets of isolated rabbit lungs in which oleic acid was added to the vascular perfusate to produce mild to moderate lung injury. All lungs were ventilated with peak airway pressure of 30 cm H2O for 30 minutes. Outcome measures included frequency of gross structural failure, pulmonary hemorrhage, edema formation, changes in static compliance, pulmonary vascular resistance, and pulmonary ultrafiltration coefficient.

RESULTS

In the context of high vascular flow, application of a moderate level of PEEP reduced pulmonary rupture, edema formation, and lung hemorrhage. The protective effects of PEEP were not observed in lungs concurrently injured with oleic acid.

CONCLUSIONS

Under these experimental conditions, PEEP attenuates lung injury in the setting of high vascular flow. The protective effect of PEEP is lost in a two-hit model of lung injury.

Utility of magnetic resonance imaging and nuclear magnetic resonance-based metabolomics for quantification of inflammatory lung injury

Magnetic resonance imaging (MRI) and metabolic nuclear magnetic resonance (NMR) spectroscopy are clinically available but have had little application in the quantification of experimental lung injury. There is a growing and unfulfilled need for predictive animal models that can improve our understanding of disease pathogenesis and therapeutic intervention. Integration of MRI and NMR could extend the application of experimental data into the clinical setting. This study investigated the ability of MRI and metabolic NMR to detect and quantify inflammation-mediated lung injury. Pulmonary inflammation was induced in male B6C3F1 mice by intratracheal administration of IL-1beta and TNF-alpha under isoflurane anesthesia. Mice underwent MRI at 2, 4, 6, and 24 h after dosing. At 6 and 24 h lungs were harvested for metabolic NMR analysis. Data acquired from IL-1beta+TNF-alpha-treated animals were compared with saline-treated control mice. The hyperintense-to-total lung volume (HTLV) ratio derived from MRI was higher in IL-1beta+TNF-alpha-treated mice compared with control at 2, 4, and 6 h but returned to control levels by 24 h. The ability of MRI to detect pulmonary inflammation was confirmed by the association between HTLV ratio and histological and pathological end points. Principal component analysis of NMR-detectable metabolites also showed a temporal pattern for which energy metabolism-based biomarkers were identified. These data demonstrate that both MRI and metabolic NMR have utility in the detection and quantification of inflammation-mediated lung injury. Integration of these clinically available techniques into experimental models of lung injury could improve the translation of basic science knowledge and information to the clinic.

Lung production of platelet-activating factor acetylhydrolase in oleic acid-induced acute lung injury

Platelet-activating factor (PAF) is a proinflammatory mediator that plays a central role in acute lung injury (ALI). PAF- acetylhydrolases (PAF-AHs) terminate PAF's signals and regulate inflammation. In this study, we describe the kinetics of plasma and bronchoalveolar lavage (BAL) PAF-AH in the early phase of ALI. Six pigs with oleic acid induced ALI and two healthy controls were studied. Plasma and BAL samples were collected every 2h and immunohistochemical analysis of PAF-AH was performed in lung tissues. PAF-AH activity in BAL was increased at the end of the experiment (BAL PAF-AH Time 0=0.001+/-0.001 nmol/ml/min/g vs Time 6=0.031+/-0.018 nmol/ml/min/g, p=0.04) while plasma activity was not altered. We observed increased PAF-AH staining of macrophages and epithelial cells in the lungs of animals with ALI but not in healthy controls. Our data suggest that increases in PAF-AH levels are, in part, a result of alveolar production. PAF-AH may represent a modulatory strategy to counteract the excessive pro-inflammatory effects of PAF and PAF-like lipids in lung inflammation.

Anti-KC autoantibody:KC complexes cause severe lung inflammation in mice via IgG receptors

We have shown previously that high concentrations of IL-8 associated with anti-IL-8 autoantibodies (anti-IL-8:IL-8 complexes) are present in lung fluids from patients with the acute respiratory distress syndrome (ARDS), and correlate both with the development and outcome of ARDS. We also detected deposition of these complexes in lung tissues from patients with ARDS but not in control tissues. Moreover, we determined that IgG receptors (FcgammaRs) mediate activity of anti-IL-8:IL-8 complexes. In the current study, we generated anti-KC (KC = chemokine (CXC motif) ligand 1 (CXCL1)) autoantibody:KC immune complexes (KC-functional IL-8) in lungs of mice to develop a mouse model of autoimmune complex-induced lung inflammation. Both wild-type (WT) and gamma-chain-deficient mice that lack receptors for immune complexes (FcgammaRs) were studied. First, the mice were immunized with KC to induce anti-KC autoantibodies. Then, KC was administered intratracheally to generate anti-KC:KC complexes in the lung. Presence of anti-KC:KC complexes was associated with development of severe pulmonary inflammation that was, however, dramatically suppressed in gamma-chain-deficient mice. Second, because sepsis is considered the major risk factor for development of ARDS, we evaluated LPS-treated WT as well as gamma-chain-deficient mice for the presence of anti-KC:KC complexes and pulmonary inflammatory responses. We detected complexes between anti-KC autoantibodies and KC in lung lavages and tissues of mice treated with LPS. Moreover, gamma-chain-deficient mice that lack receptors for immune complexes were protected from LPS-induced pulmonary inflammation. Our results suggest that immune complexes containing autoantibodies contribute to development of lung inflammation in LPS-treated mice.

Lactobacillus plantarum for oral peptide delivery

AIMS

To evaluate strains of lactobacilli for their ability to persist and secrete heterologous protein in the oral cavity.

METHODS AND RESULTS

Four different strains of common oral lactobacilli, Lactobacillus brevis, Lactobacillus johnsonii, Lactobacillus murinus and Lactobacillus plantarum, were transformed with the plasmid pKTH2121, which contains a secretion cassette for beta-lactamase. Lactobacilli isolated from the mouth of host mice were also transformed with pKTH2121 for later feeding. Lactococcus lactis, transformed with pKTH2121, was also fed to mice as a negative control. All transformed isolates were fed to C57Black mice in varying schedules. The number of transformed bacteria persisting in the mouth was reported as a percentage of total oral bacteria recovered by swabbing.

CONCLUSIONS

The transformed L. lactis, L. brevis, L. johnsonii, L. murinus, and the endogenous murine lactobacillus strain failed to persist in the mouth. Transformed L. plantarum, however, persisted in the mouth and comprised up to 25% of the total lactobacilli at 18 h and 10% at 24 h after feeding. L. plantarum recovered after feeding retained its ability to secrete beta-lactamase into culture medium efficiently. Beta-lactamase activity could be detected in oral secretions at 8 h after feedings. After repeated feedings, however, the L. plantarum containing pKTH2121 gradually lost its ability to persist after feedings. This experiment demonstrates that L. plantarum can transiently colonize the oral mucosa in large numbers, while continuously secreting foreign proteins, raising the possibility of using lactobacilli as a vector for delivery of oral mucosal peptides.

In vivo characterization of lung morphology and function in anesthetized free-breathing mice using micro-computed tomography

Lung morphology and function in human subjects can be monitored with computed tomography (CT). Because many human respiratory diseases are routinely modeled in rodents, a means of monitoring the changes in the structure and function of the rodent lung is desired. High-resolution images of the rodent lung can be attained with specialized micro-CT equipment, which provides a means of monitoring rodent models of lung disease noninvasively with a clinically relevant method. Previous studies have shown respiratory-gated images of intubated and respirated mice. Although the image quality and resolution are sufficient in these studies to make quantitative measurements, these measurements of lung structure will depend on the settings of the ventilator and not on the respiratory mechanics of the individual animals. In addition, intubation and ventilation can have unnatural effects on the respiratory dynamics of the animal, because the airway pressure, tidal volume, and respiratory rate are selected by the operator. In these experiments, important information about the symptoms of the respiratory disease being studied may be missed because the respiration is forced to conform to the ventilator settings. In this study, we implement a method of respiratory-gated micro-CT for use with anesthetized free-breathing rodents. From the micro-CT images, quantitative analysis of the structure of the lungs of healthy unconscious mice was performed to obtain airway diameters, lung and airway volumes, and CT densities at end expiration and during inspiration. Because the animals were free breathing, we were able to calculate tidal volume (0.09 +/- 0.03 ml) and functional residual capacity (0.16 +/- 0.03 ml).

Regulation of lipopolysaccharide-induced increases in neutrophil glucose uptake

The pathogenesis of many lung diseases involves neutrophilic inflammation. Neutrophil functions, in turn, are critically dependent on glucose uptake and glycolysis to supply the necessary energy to meet these functions. In this study, we determined the effects of p38 mitogen-activated protein kinase and hypoxia-inducible factor (HIF)-1, as well as their potential interaction, on the expression of membrane glucose transporters and on glucose uptake in murine neutrophils. Neutrophils were harvested and purified from C57BL/6 mice and stimulated with lipopolysaccharide (LPS) in the presence or absence of specific p38 and HIF-1 inhibitors. Glucose uptake was measured as the rate of [3H]deoxyglucose (DG) uptake. We identified GLUT-1 in mouse neutrophils, but neither GLUT-3 nor GLUT-4 were detected using Western blot analysis, even after LPS stimulation. LPS stimulation did not increase GLUT-1 protein levels but did cause translocation of GLUT-1 from the cell interior to the cell surface, together with a dose-dependent increase in [3H]DG uptake, indicating that glucose uptake is regulated in these cells. LPS also activated both p38 and the HIF-1 pathway. Inhibitors of p38 and HIF-1 blocked GLUT-1 translocation and [3H]DG uptake. These data suggest that LPS-induced increases in neutrophil glucose uptake are mediated by GLUT-1 translocation to the cell surface in response to sequential activation of neutrophil p38 and HIF-1alpha in neutrophils. Given that neutrophil function and glucose metabolism are closely linked, control of the latter may represent a new target to ameliorate the deleterious effects of neutrophils on the lungs.

FDG-PET imaging of pulmonary inflammation in healthy volunteers after airway instillation of endotoxin

Recent studies indicate that a focal, limited, inflammatory response can be safely elicited after direct bronchial instillation of small doses of endotoxin into a single lung segment. Because the radiotracer [18F]fluorodeoxyglucose ([18F]FDG) is taken up at accelerated rates within inflamed tissues, we hypothesized that we could detect and quantify this regional inflammatory response with positron emission tomography (PET). We imaged 18 normal volunteers in a dose-escalation study with 3 endotoxin dosing groups ( n = 6 in each group): 1 ng/kg, 2 ng/kg, and 4 ng/kg. Endotoxin was instilled by bronchoscopy into a segment of the right middle lobe, with imaging performed ∼24 h later, followed by bronchoalveolar lavage (BAL). A “subtraction imaging analysis” was performed in the highest dose cohort to identify the area of inflammation, using the preendotoxin scan as a baseline. BAL neutrophil counts were significantly higher in the highest dose group compared with the other two groups (1,413 ± 625 vs. 511 ± 396 and 395 ± 400 cells/mm3; P < 0.05). Autoradiography performed on cells harvested by BAL showed specific [3H]deoxyglucose ([3H]DG) uptake limited to neutrophils. In vitro [3H]DG uptake in BAL neutrophils in the 4 ng/kg dose group (but not in the 2 ng/kg group) was statistically greater than in peripheral blood neutrophils obtained before endotoxin instillation. The rate of [18F]FDG uptake was greatest in the 4 ng/kg group, with a consistent, statistically significant increase in the rate of uptake after endotoxin instillation compared with baseline. We conclude that the inflammatory response to low-dose endotoxin in a single lung segment can be visualized and quantified by imaging with FDG-PET.

Quantifying pulmonary inflammation in cystic fibrosis with positron emission tomography

RATIONALE

Although infection contributes to morbidity in patients with cystic fibrosis (CF), the host inflammatory response is also an important cause of progressive pulmonary function deterioration. Quantifying the inflammatory burden in these patients is challenging and often requires invasive procedures. Positron emission tomographic imaging with [18F]fluorodeoxyglucose ([18FDG]) could be used as a noninvasive alternative to quantify lung inflammation.

OBJECTIVE

To determine the relationships among lung [18F]FDG uptake, bronchoalveolar lavage (BAL) neutrophil concentrations, and pulmonary function in patients with CF.

METHODS

Twenty patients and seven healthy volunteers were studied. A subset of seven patients also consented to undergo BAL. The uptake of [18F]FDG by the lungs was measured as the net influx rate constant Ki. Patients were stratified by rate of decline in pulmonary function into stable, intermediate, and rapidly declining groups. Ki was compared among groups and was correlated against neutrophil concentrations in BAL fluid.

RESULTS

Ki was significantly elevated (p<0.05) among patients with CF as a whole compared with healthy control subjects (0.0015+/-0.0009 versus 0.0007+/-0.0002 ml blood/ml lung/min) but especially in patients with rapidly declining pulmonary function (0.0022+/-0.0011 ml blood/ml lung/min). Ki correlated positively with the number of neutrophils present in BAL fluid.

CONCLUSION

Imaging with [18F]fluorodeoxyglucose and positron emission tomography can be used to assess inflammatory burden in patients with CF. Elevations in Ki may be able to identify patients with more aggressive disease and may be useful in monitoring changes in inflammatory burden in response to novel treatments.

Novel method to calculate pulmonary compliance images in rodents from computed tomography acquired at constant pressures

Our goal was to develop a method for generating high-resolution three-dimensional pulmonary compliance images in rodents from computed tomography (CT) images acquired at a series of constant pressures in ventilated animals. One rat and one mouse were used to demonstrate this technique. A pre-clinical GE flat panel CT scanner (maximum 31 line-pairs cm(-1) resolution) was utilized for image acquisition. The thorax of each animal was imaged with breath-holds at 2, 6, 10, 14 and 18 cm H2O pressure in triplicate. A deformable image registration algorithm was applied to each pair of CT images to map corresponding tissue elements. Pulmonary compliance was calculated on a voxel by voxel basis using adjacent pairs of CT images. Triplicate imaging was used to estimate the measurement error of this technique. The 3D pulmonary compliance images revealed regional heterogeneity of compliance. The maximum total lung compliance measured 0.080 (+/-0.007) ml air per cm H2O per ml of lung and 0.039 (+/-0.004) ml air per cm H2O per ml of lung for the rat and mouse, respectively. In this study, we have demonstrated a unique method of quantifying regional lung compliance from 4 to 16 cm H2O pressure with sub-millimetre spatial resolution in rodents.