Obesity is associated with neutrophil dysfunction and attenuation of murine acute lung injury

Although obesity is implicated in numerous health complications leading to increased mortality, the relationship between obesity and outcomes for critically ill patients appears paradoxical. Recent studies have reported better outcomes and lower levels of inflammatory cytokines in obese patients with acute lung injury (ALI)/acute respiratory distress syndrome, suggesting that obesity may ameliorate the effects of this disease. We investigated the effects of obesity in leptin-resistant db/db obese and diet-induced obese mice using an inhaled LPS model of ALI. Obesity-associated effects on neutrophil chemoattractant response were examined in bone marrow neutrophils using chemotaxis and adoptive transfer; neutrophil surface levels of chemokine receptor CXCR2 were determined by flow cytometry. Airspace neutrophilia, capillary leak, and plasma IL-6 were all decreased in obese relative to lean mice in established lung injury (24 h). No difference in airspace inflammatory cytokine levels was found between obese and lean mice in both obesity models during the early phase of neutrophil recruitment (2-6 h), but early airspace neutrophilia was reduced in db/db obese mice. Neutrophils from uninjured obese mice demonstrated diminished chemotaxis to the chemokine keratinocyte cytokine compared with lean control mice, and adoptive transfer of obese mouse neutrophils into injured lean mice revealed a defect in airspace migration of these cells. Possibly contributing to this defect, neutrophil CXCR2 expression was significantly lower in obese db/db mice, and a similar but nonsignificant decrease was seen in diet-induced obese mice. ALI is attenuated in obese mice, and this blunted response is in part attributable to an obesity-associated abnormal neutrophil chemoattractant response.     

The role of aquaporin-1 (AQP1) expression in a murine model of lipopolysaccharide-induced acute lung injury

A murine model of lipopolysaccharide (LPS)-induced acute lung injury (ALI) was used to evaluate whether aquaporin-1 (AQP1) is involved in lung inflammation and lung edema formation. Swiss strain mice (n = 122) had LPS (5 mg/kg) instilled intratracheally (IT), and were then treated with either 0.9 % saline or dexamethasone (5 mg/kg/day). Mice were euthanized at 2 days and 7 days after treatment. Inflammatory cytokines (TNF-alpha, IL-6), protein concentration in bronchoalveolar lavage (BAL) fluid, lung wet-to-dry weight ratio, histology, immunohistochemistry, and AQP1 Western blot were performed. Lung wet-to-dry weight ratio and lung vascular permeability were also measured in the AQP1 knockout mice (n = 9) that received IT LPS (5 mg/kg) at 2 days. Intratracheal instillation of LPS produced a severe lung injury at 2 days, characterized by elevation of TNF-alpha, IL-6 in the BAL fluid, and by histological changes consistent with increased lung vascular permeability and neutrophil infiltration. AQP1-immunoreactivity in the pulmonary capillary endothelium was reduced at 2 days and 7 days. Administration of dexamethasone improved LPS-induced ALI and retained expression of AQP1. However, depletion of AQP1 did not affect lung edema formation, lung vascular permeability, or lung histology. The results suggest that although AQP1 expression is decreased after lung injury, depletion of AQP1 does not alter lung inflammation and lung edema induced by LPS.     

Inhibition of nitric oxide restores surfactant gene expression following nickel-induced acute lung injury

The role of nitric oxide (NO) in acute lung injury remains controversial. Although inhaled NO increases oxygenation in clinical trials, inhibiting NO-synthase (NOS) can be protective. To examine the latter, nickel-exposed mice were treated with saline or NOS inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME). Initial microarray analysis of nickel-induced gene expression of saline-treated mice revealed increased inflammatory mediator, matrix injury-repair, and hypoxia-induced factor-mediated sequences and decreased lung-specific (e.g., surfactant-associated protein B and C) sequences. Compared with saline control, L-NAME-treated mice had enhanced survival with attenuated serum nitrate/nitrite, endothelial NOS activity, and lavage neutrophils and protein. Although initial cytokine (i.e., interferon-gamma, interleukins-1beta and -6, macrophage inflammatory protein-2, monocyte chemotactic protein-1, and tumor necrosis factor-alpha) gene expression was similar between groups, subsequent larger cytokine increases only occurred in saline-treated mice. Similarly, surfactant protein gene expression decreased initially in both groups yet was restored subsequently with L-NAME treatment. Interestingly, the role of inducible NOS (iNOS) in these responses seems minimal. iNOS gene expression was unaltered, iNOS activity and nitrotyrosine residues were undetectable, and an iNOS antagonist, aminoguanidine, failed to increase survival. Rather, systemic L-NAME treatment appears to attenuate pulmonary endothelial NOS activity, subsequent cytokine expression, inflammation, and protein permeability, and thereby restores surfactant gene expression and increases survival.     

KGFR promotes Na+ channel expression in a rat acute lung injury model

Background

Binding of keratinocyte growth factor (KGF) to the KGF receptor (KGFR) plays an important role in the recovery of alveolar epithelial cells from acute lung injury (ALI).

Objectives

To evaluate the effect of gene therapy via adenovirus gene transfer of KGFR on the treatment of ALI.

Methods

Sprague-Dawley rats were divided into four groups: normal controls, injury controls, normal adenovirus transduced group and injury adenovirus transduced group. The ALI model was induced by lipopolysaccharide (LPS) injection. Recombinant adenovirus (AdEasy-KGFR) was injected via the tail vein. Expression of the sodium (Na⁺) channel in rat alveolar type II (ATII) epithelial cells was determined by PCR, immunohistochemistry and immunoelectron microscopy of rat lung tissues.

Results

Gene expression of the Na⁺ channel and KGFR in ATII cells was higher in the normal adenovirus transduced group than the three other groups; expression of these two genes in the injury adenovirus transduced group was higher than the injury control group. Na⁺ channel protein expression was lower in the injury adenovirus transduced group but higher than the injury control group.

Conclusions

KGFR over-expression induced Na channel expression could potentially be beneficial for ALI therapy.     

Aspirin-triggered resolvin D1 reduces mucosal inflammation and promotes resolution in a murine model of acute lung injury

Acute lung injury (ALI) is a severe illness with excess mortality and no specific therapy. Protective actions were recently uncovered for docosahexaenoic acid-derived mediators, including D-series resolvins. Here, we used a murine self-limited model of hydrochloric acid-induced ALI to determine the effects of aspirin-triggered resolvin D1 (AT-RvD1; 7S,8R,17R-trihydroxy-4Z,9E,11E,13Z,15E,19Z-docosahexaenoic acid) on mucosal injury. RvD1 and its receptor ALX/FPR2 were identified in murine lung after ALI. AT-RvD1 (∼0.5–5 μg kg⁻¹) decreased peak inflammation, including bronchoalveolar lavage fluid (BALF) neutrophils by ∼75%. Animals treated with AT-RvD1 had improved epithelial and endothelial barrier integrity and decreased airway resistance concomitant with increased BALF epinephrine levels. AT-RvD1 inhibited neutrophil–platelet heterotypic interactions by downregulating both P-selectin and its ligand CD24. AT-RvD1 also significantly decreased levels of BALF pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6, Kupffer cells, and tumor necrosis factor-α, and decreased nuclear factor-κB-phosphorylated p65 nuclear translocation. Taken together, these findings indicate that AT-RvD1 displays potent mucosal protection and promotes catabasis after ALI.     

Progressive lung disease and surfactant dysfunction with a deletion in surfactant protein C gene

Mutations in the surfactant protein (SP)-C gene are responsible for familial and sporadic interstitial lung disease (ILD). The consequences of such mutations on pulmonary surfactant composition and function are poorly understood. To determine the effects of a mutation in the SP-C gene on surfactant, we obtained lung tissue at the time of transplantation from a 14-mo-old infant with progressive ILD. An in-frame 9-bp deletion spanning codons 91-93 in Exon 3 of the SP-C gene was present on one allele; neither parent carried this deletion. SP-C mRNA was present in normal size and amount. By immunofluorescence, proSP-C was aggregated within alveolar Type II cells in a compartment separate from SP-B. In airway surfactant, there was little or no mature SP-B or SP-C; SP-A content was increased. Minimum surface tension was increased (20 mN/m, normal < 5 mN/m). Type II cells contained normal and disorganized appearing lamellar bodies by electron microscopy. This spontaneous deletion on one allele of the SP-C gene was associated with sporadic ILD and abnormalities in surfactant composition and function. We propose that a dominant negative effect on surfactant protein metabolism and function results from aggregation of misfolded proSP-C and subsequent cell injury and inflammation.     

Protective role of lung surfactant protein D in a murine model of invasive pulmonary aspergillosis

The protective effects of intranasal administration of amphotericin B (AmB), human SP-A, SP-D and a 60-kDa fragment of SP-D (rSP-D) were examined in a murine model of invasive pulmonary aspergillosis (IPA). The untreated group of IPA mice showed no survival at 7 days postinfection. Treatment with AmB, SP-D, and rSP-D increased the survival rate to 80, 60, and 80%, respectively, suggesting that SP-D (and rSP-D) can protect immunosuppressed mice from an otherwise fatal challenge with Aspergillus fumigatus conidia.     

猪肺表面活性物质对大鼠早期脂多糖性急性肺损伤的治疗作用

 目的： 观察猪肺表面活性物质（PPS）混悬液对大鼠早期脂多糖(LPS)性急性肺损伤（ALI）的治疗作用。方法： SD大鼠随机分为4组：生理盐水组、低、中、高3个不同剂量PPS给药组，各组动物均气道内滴注LPS 1.5 mg·kg-1,30 min后分别经气管滴注100 mg·kg^-1、150 mg·kg^-1、200 mg·kg-1PPS（PPS组）或等量生理盐水（对照组）。之后观察6 h，监测大鼠的PaO2和PaCO₂，计算各组大鼠存活率。大鼠处死后检测肺系数（LI），肺泡灌洗液（BALF）中总蛋白(TP)含量，白细胞（WBC）数和肿瘤坏死因子(TNF)-α的浓度，并观察肺病理组织学改变。结果： 与生理盐水组相比，LPS损伤大鼠早期气道内滴入外源性PPS可提高PaO₂，降低PaCO₂，提高存活率，减轻肺水肿及肺毛细血管膜的通透性，PPS150组、PPS200组的治疗效果优于PPS100组。结论： PPS早期给药对LPS气道内滴注致ALI具有明显的治疗作用。     

慢性阻塞性肺疾病大鼠肺组织中肺表面活性物质蛋白-C表达下降

目的探讨肺表面活性物质蛋白-C(SP-C)在慢性阻塞性肺疾病(COPD)大鼠肺组织中的作用。方法将大鼠随机分为对照组、香烟烟雾暴露组、脂多糖组和COPD组,每组10只。测定各组大鼠的PaO_2和PaCO_2的水平;透射电镜观察肺组织的细胞微观结构;ELISA检测支气管肺泡灌洗液(BALF)和肺组织SP-C蛋白;RT-q PCR检测肺组织SP-C mRNA的表达。结果与其他组相比,COPD大鼠的PaO_2最低,而PaCO_2最高;肺泡Ⅱ型上皮细胞表面微绒毛明显减少(P<0.01);BALF和肺组织中SP-C蛋白表达下降(P<0.01);肺组织中的SP-C mRNA表达下降(P<0.01)。结论 SP-C在COPD大鼠肺组织中表达下调,这种下调可能引起肺通气和肺换气功能障碍。     

Effect of acute lung injury on structure and function of pulmonary surfactant films

The structural and functional alterations in pulmonary surfactant that occur during acute lung injury were studied using rat lung surfactant large aggregates (LA) isolated from normal nonventilated lungs (N), and from standard ventilated (V) and injuriously ventilated (IV) excised lungs. N lungs inflated significantly better than IV lungs, with V lungs intermediate. Although IV LA phosphatidylcholine levels were unchanged, cholesterol and protein were elevated. V LA exhibited PC/cholesterol and PC/protein ratios intermediate between N and IV. In contrast to total cholesterol and protein levels, these ratios were not significantly different from IV LA. N and V LA, but not IV LA, adsorbed rapidly and were able to generate surface pressures (pi) near 70 mN/m during surface area reduction at 37 degrees C on a captive bubble tensiometer. Langmuir-Wilhelmy surface balance studies at 23 degrees C showed N LA films consistently attained pi approaching 70 mN/m during ten compression-expansion cycles. IV films were less effective and failed to achieve high pi consistently after the sixth cycle. V films were intermediate. Epifluorescence studies revealed compression of adsorbed N LA films formed well-defined liquid-condensed (LC) domains, but fewer, smaller domains were observed with IV films and, to a lesser extent, V films. Atomic force microscopy on Langmuir-Blodgett N films transferred at pi = 30 mN/m showed high, well-defined LC domains. IV films showed thinner, intermediate height, possibly fluid domains, which contain large numbers of small higher domains with heights corresponding to LC domains. V films were intermediate. We conclude that acute lung injury induced by hyperventilation, and to a lesser extent standard ventilation, of excised lungs alters surfactant surface activity and the ability of natural surfactant to form surface structures at the air-water interface.     

A murine model of acute lung injury identifies growth factors to promote tissue repair and their biomarkers

Type II alveolar epithelial cells (AEC2s) play a crucial role in the regeneration of type I AECs after acute lung injury. The mechanisms underlying the regeneration of AEC2s are not fully understood. To address this issue, here, we investigated a murine model of acute lung injury using mice expressing human Diphtheria Toxin Receptor (DTR) under the control of Lysozyme M promoter (LysM‐DTR). DT injection induced the depletion of AEC2s, alveolar macrophages, and bone marrow (BM)‐derived myeloid cells in LysM‐DTR mice, and the mice died within 6 days after DT injection. Apoptotic AEC2s and bronchiolar epithelial cells appeared at 24 hr, whereas Ki67‐positive proliferating cells appeared in the alveoli and bronchioles in the lung of LysM‐DTR mice at 72–96 hr after DT injection. Transfer of wild‐type BM cells into LysM‐DTR mice accelerated the regeneration of AEC2s along with the up‐regulation of several growth factors. Moreover, several metabolites were significantly decreased in the sera of LysM‐DTR mice compared with WT mice after DT injection, suggesting that these metabolites might be biomarkers to predict AEC2s injury. Together, LysM‐DTR mice might be useful to identify growth factors to promote lung repair and the metabolites to predict the severity of lung injury.     

NF-κB在大鼠急性肺损伤模型肺组织中的表达及N-乙酰半胱氨酸的影响

目的 :检测NF κB在LPS诱导的急性肺损伤 (ALI)肺组织中的表达 ,以及N 乙酰半胱氨酸 (NAC)对ALI的抑制作用。方法 :采用免疫组化染色 (ABC法 )和Westernblot,检测NF κB在急性肺损伤大鼠气道和肺组织中的表达 ,以及NAC干预后活性NF κB表达的变化。结果 :正常对照组大鼠气道黏膜上皮和肺间质中 ,仅见少量散在的NF κB核阳性细胞 ;而LPS诱导ALI后 ,气道黏膜、肺间质、肺泡腔及血管内皮细胞中NF κB核阳性的细胞明显增多 (P <0 .0 1)。NF κB核阳性反应细胞主要为气道黏膜上皮细胞、浸润的炎症细胞、肺泡上皮细胞和血管内皮细胞。NAC治疗组NF κB核阳性细胞较LPS诱导的ALI组及对照组均明显减少 (P <0 .0 1)。Westernblot的结果显示 ,LPS诱导的ALI后不同时间点 ,NF κB的表达不同 ,于急性肺损伤 3h达高峰。各时间点NF κB的表达均较正常对照组高。结论 :LPS诱发的大鼠急性肺损伤的气道和肺组织内NF κB的表达增加 ,肺组织内的多数细胞参与了NF κB的激活。NAC可通过抑制NF κB的激活减轻急性肺损伤的炎症程度     

Analysis of regional compliance in a porcine model of acute lung injury

Lung protective ventilation in Acute Lung Injury (ALI) focuses on using low tidal volumes and adequate levels of positive end-expiratory pressure (PEEP). Identifying optimal pressure is difficult because pressure-volume (PV) relations differ regionally. Precise analysis demands local measurements of pressures and related alveolar morphologies. In a porcine model of surfactant depletion (n=24), we combined measuring static pressures with endoscopic microscopy and electrical impedance tomography (EIT) to examine regional PV loops and morphologic heterogeneities between healthy (control group; CON) and ALI lungs ventilated with low (LVT) or high tidal volumes (HVT). Quantification included indices for microscopy (Volume Air Index (VAI), Heterogeneity and Circularity Index), EIT analysis and calculation of regional compliances due to generated PV loops. We found that: (1) VAI decreased in lower lobe after ALI, (2) electrical impedance decreased in dorsal regions and (3) PV loops differed regionally. Further studies should prove the potentials of these techniques on individual respiratory settings and clinical outcome.     

Pulmonary clearance of 99mTc--DTPA and 99mTc-albumin in rabbits with surfactant dysfunction and lung injury.

We measured the pulmonary clearance of inhaled 99mTc-DTPA and 99mTc-albumin in rabbits with surfactant dysfunction induced by dioctyl sodium sulphosuccinate and in rabbits with lung injury induced by oleic acid. The animals were tracheotomized and mechanically ventilated. After inhalation of 99mTc-albumin in ten animals, clearance of the tracer from the lungs was monitored for 90 min. The first 30 min was a control period. Dioctyl sodium sulphosuccinate was then administered in aerosol and after another 30 min oleic acid was injected intravenously. Ten other rabbits were given 99mTc-DTPA, and clearance was externally recorded for 60 min. Five animals inhaled detergent aerosol and five animals were given oleic acid intravenously after 30 min. Airway pressures, tidal volume, and arterial blood gases were measured before and after each intervention. The half-life of 99mTc-albumin in the lung was 442 +/- 123 min during the control period, 363 +/- 52 min after detergent administration, and 134 +/- 18 min after oleic acid administration (P less than 0.05 compared to control and P less than 0.01 compared to the period after detergent). The half-life of 99mTc-DTPA was 94 +/- 16 min before and 10 +/- 0.6 min (P less than 0.01) after detergent administration and 75 +/- 12 min before and 18 +/- 1.8 min (P less than 0.01) after oleic acid administration. Gas exchange was not affected by administration of dioctyl sodium sulphosuccinate but markedly impaired after injection of oleic acid. Compliance of the respiratory system remained unaffected by detergent but decreased after injection of oleic acid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Heparin-binding EGF-like growth factor attenuates lung inflammation and injury in a murine model of pulmonary emphysema

Pulmonary inflammation and progressive lung destruction are the major causes of chronic obstructive pulmonary disease (COPD), resulting in emphysema and irreversible pulmonary dysfunction. Heparin-binding EGF-like growth factor (HB-EGF), is known to play a protective role in the process of various inflammatory diseases. However, its effect on COPD is poorly understood. This study was designed to determine the effect of HB-EGF on lung inflammation and injury in a murine model of pulmonary emphysema. HB-EGF promoted percent survival and body weight, attenuated lung injury, inflammatory cells, and cytokines infiltration, and prevented lung function decline. Additionally, treatment of rHB-EGF suppressed the nuclear translocation of nuclear factor κB (NF-κB)/p65, decreased TUNEL-positive cells and the expression of caspase 3, and increased the expression of PCNA, HB-EGF, and EGF receptor (EGFR). We conclude that HB-EGF attenuates lung inflammation and injury, probably through the activation of EGFR, followed by suppression of NF-ΚB signalling, promotion of cell proliferation, and inhibition of apoptosis.     

Comparison of different inhalational perfluorocarbons in a rabbit model of acute lung injury

The purpose of this study was to investigate the influence of different inhaled perfluorocarbons (PFC) upon pulmonary mechanics and gas exchange in a saline lavage model of acute lung injury. A randomized, controlled animal trial was conducted at the university hospital laboratory. Pulmonary gas exchange (pGE), static compliance (Cst), and basic hemodynamics (heart rate [HR], arterial [AP] and central venous pressures [CVP]) were compared. After induction of lung injury by repeated pulmonary lavage with saline solution, 35 New Zealand rabbits (3 +/- 0.2 kg) were randomized into five groups with seven animals each: 1) conventional ventilated control, 2) perfluorooctane (octane), 3) Perflubron (perfluorooctylbromide [PFOB]), 4) Perfluoro-1,3,5-trimethylcyclohexane (PP 4), and 5) perfluorohexane (hexane). Consecutively, PFC groups were subjected to a 120 minute study period applying mechanical ventilation (tidal volume of 7 ml/kg) in conjunction with PFC performed by a modified halothane vaporizer. Amount of vaporization was controlled by weighing the vaporizer at approximately 25 ml/h/kg body-weight PFC. Controls remained gas ventilated. After injury, PaO2 was control = 53 +/- 13 mbar, octane = 55 +/- 24 mbar, perflubron = 57 +/- 18 mbar, PP4 = 68 +/- 25 mbar, and hexane = 51 +/- 16 mbar. Within the 120 minute period, PaO2 was control = 51 +/- 19 mbar, octane = 42 +/- 6 mbar, perflubron = 40 +/- 11 mbar, PP4 = 47 +/- 10 mbar, and hexane = 60 +/- 8 mbar, respectively. At baseline, after injury, and throughout the study period, pGE and Cst, as well as HR, AP, and CVP, did not significantly differ when compared with octane, PP4, PFOB, and controls (p > 0.05), whereas hexane significantly improved pGE and Cst (p < 0.05). From four different inhaled perfluorocarbons, only perfluorohexane has measureable impact upon gas exchange and lung mechanics when compared with a conventional lung protective ventilation mode.     

Nonionic surfactant attenuates acute lung injury by restoring epithelial integrity and alveolar fluid clearance

Introduction: Acute lung injury (ALI) has a great impact and a high mortality rate in intensive care units (ICUs). Excessive air may enter the lungs, causing pulmonary air embolism (AE)-induced ALI. Some invasive iatrogenic procedures cause pulmonary AE-induced ALI, with the presentation of severe inflammatory reactions, hypoxia, and pulmonary hypertension. Pulmonary surfactants are vital in the lungs to reduce the surface tension and inflammation. Nonionic surfactants (NIS) are a kind of surfactants without electric charge on their hydrophilic parts. Studies on NIS in AE-induced ALI are limited. We aimed to study the protective effects and mechanisms of NIS in AE-induced ALI.Materials and methods: Five different groups (n = 6 in each group) were created: sham, AE, AE + NIS pretreatment (0.5 mg/kg), AE + NIS pretreatment (1 mg/kg), and AE + post-AE NIS (1 mg/kg). AE-induced ALI was introduced by the infusion of air via the pulmonary artery. Aerosolized NIS were administered via tracheostomy.Results: Pulmonary AE-induced ALI showed destruction of the alveolar cell integrity with increased pulmonary microvascular permeability, pulmonary vascular resistance, pulmonary edema, and lung inflammation. The activation of nuclear factor-κB (NF-κB) increased the expression of pro-inflammatory cytokines, and sodium-potassium-chloride co-transporter isoform 1 (NKCC1). The pretreatment with NIS (1 mg/kg) prominently maintained the integrity of the epithelial lining and suppressed the expression of NF-κB, pro-inflammatory cytokines, and NKCC1, subsequently reducing AE-induced ALI.Conclusions: NIS maintained the integrity of the epithelial lining and suppressed the expression of NF-κB, pro-inflammatory cytokines, and NKCC1, thereby reducing hyperpermeability, pulmonary edema, and inflammation in ALI.     

Comparison of gene expression and DNA copy number changes in a murine model of lung cancer

Activation of oncogenic Kras in murine lung leads to the development of numerous small adenomas, only some of which progress over time to overt adenocarcinoma. Thus, although Kras is the initiating oncogene, it is likely that secondary genetic events are required for progression from adenoma to adenocarcinoma. Some of these secondary events may also be important in human lung adenocarcinoma. By comparing gene expression profiles with DNA copy number changes, we sought to identify genes that play key roles in tumor progression in this model. Gene expression profiling revealed significant heterogeneity among the tumor samples. In 27% of the tumors analyzed, whole- or sub-chromosome duplications or deletions in one or more chromosomes were seen. Recurrent duplications were seen on chromosomes 6, 8, 16, and 19, whereas chromosomes 4, 11, and 17 were frequently lost. Notably, focal amplifications or deletions were not seen. Despite the lack of focal amplification, we showed that chromosome duplication has a measurable effect on gene expression that is not uniform across the genome. We identified a group of genes whose gene expression was highly correlated with changes in DNA copy number. These highly correlated genes were enriched for gene ontology categories involved in the DNA damage response and telomere maintenance.