Analysis of the inflammatory response induced by rhMMP-12 catalytic domain instilled in mouse airways

Macrophage elastase (MMP-12) is a metalloproteinase able to degrade extracellular matrix components such as elastin. As many MMPs, MMP-12 is involved in acute and chronic lung injury. However, its role in the inflammatory process of the lung parenchyma is not clearly understood. In this study, we have investigated the effects of airway instillation of rhMMP-12 on inflammatory cell recruitment, cytokine release and gelatinase expression in bronchoalveolar lavage fluid (BALF) or in lung homogenate supernatants in mice. Numbers of total and individual cell types were examined in BALF during the first 72 h following rhMMP-12 instillation. A marked recruitment of neutrophils was observed with a maximum increase at 18 h. This cellular recruitment was associated with a very transient increase in IL-6, TNF-alpha MIP-1alpha, MCP-1 and KC levels and gelatinase expression in BALF and in lung homogenate supernatants. From days 4 to 15, performing the same analyses, we observed an important and stable recruitment of macrophages in BALF in absence of the other studied inflammatory markers. These results demonstrate that rhMMP-12 itself is able to induce an early inflammatory response characterized by neutrophil infiltration, cytokine release and gelatinase activation followed by a later response composed mainly of macrophage recruitment.     

Effects of depletion of neutrophils or macrophages on the inflammatory response induced by metalloelastase (MMP-12) in mice airways

Macrophage elastase (recombinant human matrix metalloproteinase-12, rhMMP-12), was instilled in mouse airways, inducing an early inflammatory response characterized by neutrophil recruitment and cytokine release in the bronchoalveolar lavage (BAL) fluids, followed by a delayed macrophage recruitment. We investigated the role played by alveolar macrophages and neutrophils in the delayed macrophage influx induced by rhMMP-12 (8 x 10(-3) U/mouse) in A/J mice. Mice depleted of circulating neutrophils, using a cytotoxic antibody, did not present an increase in neutrophil numbers in bronchoalveolar lavage fluids, 4 h and 24 h after rhMMP-12 instillation but the macrophage recruitment was not modified as compared to control mice at 7 days. Similar results were obtained using mice when the gene for neutrophil elastase was knocked out. Intranasal instillation of clodronate liposomes, 72 h prior to rhMMP-12 instillation, induced macrophage depletion which did not modify the macrophage recruitment at 7 days. Moreover, the stimulation of mouse macrophages by rhMMP-12 did not elicit the release of cytokines in culture supernatants. These results indicate that resident alveolar macrophages and recruited neutrophils do not play a role in the delayed macrophage recruitment induced by rhMMP-12.     

Effects of diesel exhaust on lung inflammation related to bacterial endotoxin in mice

We have previously shown that intratracheal instillation of diesel exhaust particles enhances lung inflammation and lung expression of proinflammatory cytokines and chemokines related to bacterial endotoxin (lipopolysaccharide) in mice. The present study was designed to elucidate the effects of inhalation of diesel exhaust on lung inflammation related to lipopolysaccharide. ICR mice were exposed for 12 hr to clean air or diesel exhaust at a soot concentration of 0.3, 1.0, or 3.0 mg/m(3) after intratracheal challenge with 125 microg/kg of lipopolysaccharide. Lung inflammation and lung expression of proinflammatory chemokines such as macrophage chemoattractant protein-1 and keratinocyte chemoattractant were evaluated 24 hr after intratracheal administration. Diesel exhaust inhalation decreased lipopolysaccharide-elicited inflammatory cell recruitment into the bronchoalveolar lavage fluid as compared with clean air inhalation. Histological study demonstrated that exposure to diesel exhaust did not affect lipopolysaccharide-enhanced neutrophil recruitment into the lung parenchyma. Lipopolysaccharide instillation elevated lung expression of macrophage chemoattractant protein-1 and keratinocyte chemoattractant under clean air or diesel exhaust inhalation. However, diesel exhaust exposure did not influence but rather did suppress these levels in the presence of lipopolysaccharide. These results suggest that short-term exposure to diesel exhaust did not exacerbate lung inflammation related to bacterial endotoxin.     

Elastase inhibition reduced death associated with acid aspiration-induced lung injury in hamsters

This study examined whether the specific inhibition of neutrophil elastase by sivelestat sodium hydrate (sivelestat) reduced deaths associated with severe acute lung injury after hydrochloric acid (HCl) aspiration in hamsters. Animals that received a single intratracheal instillation of HCl (0.2 N, 200 microL) time-dependently died by occlusion of their trachea with inflammatory exudate. In a time course study, these animals developed severe lung injury, peaking 12 to 24 h after HCl instillation, as indicated by hemorrhage and a massive increase in the protein concentration of bronchoalveolar lavage fluid. These changes were closely correlated with neutrophil elastase activity in bronchoalveolar lavage fluid. Sivelestat (0.01, 0.1 and 1 mg/kg/h), when intravenously infused during the first 48 h post-HCl instillation, dose-dependently reduced death in HCl-instilled hamsters. In a separate experiment, analysis of bronchoalveolar lavage fluid parameters and partial pressure of arterial oxygen (PaO(2)) 8 h post-HCl instillation showed that sivelestat at 1 mg/kg/h, i.v. significantly improved both bronchoalveolar lavage fluid parameters and PaO(2) levels with evidence of the inhibition of neutrophil elastase activity in bronchoalveolar lavage fluid. These results suggest that neutrophil elastase plays a significant role in this type of severe acute lung injury that leads to death by respiratory failure.     

Treatment with N-methyl-D-aspartate receptor antagonist (MK-801) protects against oxidative stress in lipopolysaccharide-induced acute lung injury in the rat

Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) are common syndromes that affect both clinical and surgical patients. This study describes the effects of a potent and specific N-methyl-d-aspartate receptor antagonist (MK-801) against oxidative stress in acute lung injury induced by intratracheal lipopolysaccharide (LPS) injection. This study was performed using male Wistar rats weighing 200-250g. Rats were randomly divided into four groups: control with isotonic saline instillation (n=6); LPS (100μg/100g of body weight) treated with saline (n=6); LPS treated with MK-801 (0.3mg/kg, intraperitoneally; n=6); LPS treated with MK-801 (0.3mg/kg, intratracheally; n=6). Twelve hours after the LPS instillation, rats were anesthetized and a bronchoalveolar lavage (BAL) was performed in order to determine the alveolar-capillary membrane alterations and the inflammatory infiltrate level. Blood and lung samples were isolated and assayed for oxidative stress variables and histopathologic analysis. The use of MK-801 decreased bronchoalveolar lavage fluid protein, LDH activity and inflammatory cells. Indeed, the treatment with MK-801 significantly attenuated lung oxidative damage and histopathologic alterations after LPS instillation. Our data provide the first experimental demonstration that MK-801 decreases oxidative stress and limits inflammatory response and alveolar disarray in lipopolysaccharide-induced acute lung injury.     

Inhibitory effects of flavonoids extracted from licorice on lipopolysaccharide-induced acute pulmonary inflammation in mice

Airway inflammation plays important roles in the pathogenesis of acute respiratory distress syndrome (ARDS), asthma and chronic obstructive pulmonary disease (COPD), and anti-inflammatory treatment effectively improves the symptoms of these diseases. To develop the potentially therapeutic compounds for the treatment of pulmonary inflammation, we investigated the effects of licorice flavonoids (LF) extracted from the roots of Glycyrrhiza uralensis (licorice) on lipopolysaccharide (LPS)-induced acute pulmonary inflammation in mice. Acute pulmonary inflammation was induced by intracheal instillation with LPS, treatment with LF at dosages of 3, 10 and 30 mg/kg significantly reduced the LPS-induced inflammatory cells, including neutrophils, macrophages and lymphocytes accumulation in bronchoalveolar lavage fluids (BALF), among these inflammatory cells, LF predominately inhibited neutrophil infiltration, and the maximal effect (30 mg/kg) was as comparable as dexamethasone treatment at 1 mg/kg. Consistent with its effects on neutrophil infiltration, LF treatment significantly increased LPS-induced BALF superoxide dismutase activity, and significantly decreased lung myeloperoxidase activity as well. Furthermore, treatment with LF at 30 mg/kg significantly reduced LPS-induced lung TNFα and IL-1β mRNA expression at 6 h and 24 h after LPS instillation, respectively. Finally, LF at different dosages not only significantly decreased the elevation of lung water content, but also markedly attenuated LPS-induced histological alteration. Therefore, we suggest that LF effectively attenuates LPS-induced pulmonary inflammation through inhibition of inflammatory cells infiltration and inflammatory mediator release which subsequently reduces neutrophil recruitment into lung and neutrophil-mediated oxidative injury, and this study provides with the potential rationale for development of anti-inflammatory compounds from flavonoid extracts of licorice.     

Assessing the role of neutrophil apoptosis in the resolution of particle-induced pulmonary inflammation

Following inflammatory-cell recruitment in the lung, neutrophil apoptosis and subsequent engulfment by macrophages are regarded as important components in the resolution of pulmonary inflammation. The goal of this study was to further investigate the role of apoptosis and its influence, if any, on the pulmonary inflammatory process following exposures to the following particulate types: amorphous (AMO) or crystalline silica (Si), lipopolysaccharide (LPS), or pigment-grade titanium dioxide (TiO2). Rats were intratracheally instilled either with TiO2, AMO, or Si particles at doses of 1 or 5 mg/kg or 6 microg LPS. Following exposures, bronchoalveolar lavage fluids and lung tissues were collected and evaluated at 12, 24, 48, or 168 h (i.e., 1 wk). At the 1 mg/kg dose, AMO instillation produced the highest pulmonary inflammatory response, concomitant with a rise in apoptotic cells that mirrored temporally the transient nature of the inflammatory response. At 5 mg/kg, amorphous silica and crystalline silica particles induced substantial pulmonary inflammation [approximately 50-60% neutrophils (PMNs)] at 12 h postexposure (pe). A fundamental difference between the two inflammatory patterns, however, was the subsequent reversibility of inflammation in the AMO-exposed rats at 168 h postexposure and the sustained inflammatory effect in the Si-exposed animals measured through 168 h pe (approximately 40% PMNs). Pulmonary apoptotic responses in AMO-exposed rats mirrored temporally and correlated with the time-course reduction of inflammatory responses, leading to resolution. In the Si-exposed rats, apoptotic levels remained elevated, concomitant with sustained inflammation measured through 168 h pe. High doses of TiO2 particles produced transient lung inflammation, but with low levels of apoptosis. In addition, instillation of LPS produced a transient inflammatory response which mirrored the time course of apoptosis levels and was resolved by 168 h pe. cDNA microarray methods demonstrated that gene expression was altered for several apoptosis-related genes in AMO-, Si-, and LPS-exposed animals at 24 h pe. The results of these studies demonstrate that, following exposures, the resolution of lung inflammation correlated temporally with apoptotic levels of neutrophils in AMO- and LPS-exposed rats. Alternatively, instillation of crystalline silica resulted in sustained pulmonary inflammation and measurable apoptosis at 1 wk postexposure, but the apoptotic cell processes were not effective in resolving the inflammatory response. The findings suggest that the coordination between the resolution of inflammation and inflammatory cell apoptosis in the lung is dependent on the particle-type and that other factors, such as particle cytotoxicity, may also be important.     

地塞米松对重症胎粪吸入新生兔环氧化酶水平的影响

目的 观察地塞米松对重症胎粪吸入新生兔环氧化酶水平的影响.方法 将24只新生兔完全随机分为空白组、生理盐水组、地塞米松组,每组8只.空白组气管插管后不灌胎粪;后2组气管插管后注入胎粪混合物,地塞米松组在胎粪灌入后1和3 h静脉注射地塞米松,生理盐水组在同时间静脉注射等量生理盐水.3组均比例辅助通气模式机械通气,以维持正常潮气量、正常血氧饱和度及正常血气值,8 h后处死,取肺泡灌洗液,制备肺组织匀浆,用酶联免疫吸附法检测环氧化酶的含量.结果 3组间肺泡灌洗液和肺组织匀浆中环氧化酶I含量比较,差异均无统计学意义(均P＞0.05).空白组、生理盐水组、地塞米松组动物,肺泡灌洗液中环氧化酶2含量分别为(1.07±0.84)、(3.98±0.54)、(2.58±0.43)μg/L,肺组织匀浆中分别为(1.22±0.77)、(6.14±0.18)、(5.33±0.57)μg/L,3组间两两比较,差异亦均有统计学意义(均P＜0.05).结论 地塞米松可抑制环氧化酶2的表达,减轻胎粪吸入导致的肺部炎症反应.

Abstract：

Objective To observe the effect of dexamethasone on Cyclooxygenase in newborn rabbits with severe meconium aspiration syndrome. Methods Twenty four newborn rabbits were divided randomly into control group, saline group and dexamethasone group. Meconium solutions were injected into the endotracheal tube by 4 ml/kg in the two groups. Dexamethasone group intravenous injection of dexamethasone 0. 5 mg/kg at two doses 1h and 3h after meconium solutions instilled, Saline group received an equal volume of saline at the same points of time. All rabbits of three groups used proportional assist ventilation in order to maintain normal range of tidal volume (4-10mi/kg) and normal oxygen saturation (85% or more), The rabbits were killed at 8h after meconium instillation,lungs and trachea were excised. The Cyclooxygenase was tested by enzyme-link immunosorbent assay(ELISA) which in bronchoalveolar lavage fluid(BALF) and lung homogenate, and compared among three groups. Results Among the three groups, there was no statistically significant difference in bronchoalveolar lavage fluid and lung homogenate ( P ＞ 0. 05 ) levels of cyclooxygenase-1. Compared the levels of cyclooxygenase-2 in control group, saline group and dexamethasone group, in bronchoalveolar lavage fluid[( 1.07 ±0. 84) μg/L, (3.98 +0.54) μg/L, (2.58 +0.43)μg/L] the differences were significant ( P ＜ 0.05 ), in lung homogenate [( 1.22 ± 0. 77) μg/L, (6. 14 + 0. 18) μg/L,(5.33 + 0. 57) μg/L], the differences were significant ( P ＜ 0.05 ). Conclusion Dexamethasone inhibites the expression of COX-2, alleviates the lungs inflammation which is caused by meconium aspiration.     

Anti-asthmatic action of quercetin and rutin in conscious guinea-pigs challenged with aerosolized ovalbumin

The effects of quercetin and rutin on the asthmatic responses were studied in ovalbumin (OA)-sensitized conscious guinea pigs challenged with aerosolized-OA. We measured the specific airway resistance (sRaw) in the double-chambered plethysmograph during the immediate-phase response (IAR) and late-phase response (LAR) at 3 approximately 10 min and 24 hr after OA challenge, respectively. We counted leukocytes in bronchoalveolar lavage fluid (BALF) using Wright's stain, as well as in lung tissue fixed with 10% formalin and stained with H & E stain. Quercetin and rutin (7.5 mg/kg, p.o.) significantly and dose-dependently inhibited both sRaw on IAR (31.60 and 26.44%) and LAR (29.87 and 28.69%) but with less efficacy than dexamethasone (3 mg/kg) and salbutamol (0.3 mg/kg), which inhibited IAR by 36.71 and 69.45%, and LAR by 67.23 and 0%, respectively, Quercetin and rutin (15 mg/kg) also inhibited production of histamine, PLA2, and EPO, and recruitment of leukocytes, particularly neutrophils and eosinophils, during LAR. respectively. Dexamethasone (3 mg/kg) also significantly reduced the recruitment of neutrophils, eosinophils, and lymphocytes in BALF, and salbutamol (0.3 mg/kg) reduced neutrophils and eosinophils with lower activity than dexamethasone. These results indicate that quercetin and rutin may be useful in the treatment of IAR and LAR in asthma via inhibition of histamine release, PLA2, and EPO, and reduced recruitment of neutrophils and eosinophils into the lung.     

Neotuberostemonine attenuates bleomycin-induced pulmonary fibrosis by suppressing the recruitment and activation of macrophages

Neotuberostemonine (NTS) is one of the main antitussive alkaloids in the root of Stemona tuberosa Lour. This study aimed to investigate the effects of NTS on bleomycin (BLM)-induced pulmonary fibrosis in mice and the underlying mechanism. After BLM administration, NTS were orally administered to mice at 20 and 40 mg/kg per day from days 8 to 21, with nintedanib as a positive control. The effect of NTS on BLM-induced mice was assessed via histopathological examination by HE and Masson's trichrome staining, TGF-β1 level and macrophage recruitment by immunohistochemical staining, expression of profibrotic media and M1/M2 polarization by western blot. RAW 264.7 cells were used to evaluate whether NTS (1, 10, 100 μM) directly affected macrophages. The results revealed that NTS treatment significantly ameliorated lung histopathological changes and decreased inflammatory cell counts in the bronchoalveolar lavage fluid. The over-expression of collagen, α-SMA and TGF-β1 was reduced by NTS. Furthermore, NTS markedly lowered the expression of MMP-2 and TIMP-1 while raised the expression of MMP-9. A further analysis showed that NTS was able to decrease the recruitment of macrophages and to inhibit the M2 polarization in mice lung tissues. The experiment in vitro showed that NTS significantly reduced the arginase-1 (marker for M2) expression in a dose-dependent manner but down-regulated the iNOS (marker for M1) expression only at 100 μM. In conclusion, our study demonstrated for the first time that NTS has a significant protective effect on BLM-induced pulmonary fibrosis through suppressing the recruitment and M2 polarization of macrophages.     

Sildenafil improves the beneficial hemodynamic effects exerted by atorvastatin during acute pulmonary thromboembolism

We investigated whether atorvastatin has beneficial hemodynamic effects during acute pulmonary thromboembolism (APT) and whether sildenafil improves these effects. We studied the involvement of oxidative stress, matrix metalloproteinases (MMPs), and neutrophil activation. APT was induced with autologous blood clots (500 mg/kg) in anesthetized male lambs pretreated with atorvastatin (10 mg/kg/day, subcutaneously; 1 week) or vehicle (dimethyl sulfoxide 10% subcutaneously). Sildenafil (0.7 mg/kg intravenously) or saline infusions were performed 60 min after APT induction. Non-embolized control animals received saline. APT significantly increased pulmonary vascular resistance index (PVRI) and mean pulmonary artery pressure (MPAP) by approximately 310% and 258% respectively. While atorvastatin pretreatment attenuated these increases (~150% and 153%, respectively; P < 0.05), its combination with sildenafil was associated with lower increases in PVRI and MPAP (~32% and 36%, respectively). Gelatin zymography showed increased MMP-9 and MMP-2 levels in the bronchoalveolar lavage, and increased MMP-9 levels in plasma from embolized animals. Atorvastatin pretreatment attenuated bronchoalveolar lavage MMP-2 increases. The combination of drugs blunted the MMPs increases in bronchoalveolar lavage and plasma (P < 0.05). Neutrophils accumulated in bronchoalveolar lavage after APT, and atorvastatin pretreatment combined with sildenafil (but not atorvastatin alone) attenuated this effect (P < 0.05). APT increased lung lipid peroxidation and total protein concentrations in bronchoalveolar lavage, thus indicating oxidative stress and alveolar-capillary barrier damage, respectively. Both increases were attenuated by atorvastatin pretreatment alone or combined with sildenafil (P < 0.05). We conclude that pretreatment with atorvastatin protects against the pulmonary hypertension associated with APT and that sildenafil improves this response. These findings may reflect antioxidant effects and inhibited neutrophils/MMPs activation.     

Pulmonary toxicity screening studies in male rats with M5 respirable fibers and particulates

M5 fiber is a high-strength, high-performance organic fiber type that is a rigid rod material and composed of heterocyclic polymer fibers of type PIPD. The aim of this study was to evaluate the acute lung toxicity of intratracheally instilled M5 respirable fibers and particulates in rats. Using a pulmonary bioassay and bridging methodology, the acute lung toxicity of intratracheally instilled M5 particulates and that of its fibers were compared with a positive control particle type, quartz, as well as a negative control particle type, carbonyl iron particles. Moreover, the results of these instillation studies were bridged with data previously generated from inhalation studies with quartz and carbonyl iron particles, using the quartz and iron particles as the inhalation/instillation bridge material. For the bioassay experimental design, in the bronchoalveolar lavage studies, the lungs of rats were intratracheally instilled with 0.5 or 0.75 mg/kg of M5 particulate or 1 or 5 mg/kg of the following control or particle types: (1) M5 long fiber preparation, (2) silica-quartz particles, and (3) carbonyl iron particles. Phosphate-buffered saline (PBS)-instilled rats served as additional controls. Following exposures, the lungs of PBS and particle-exposed rats were assessed using bronchoalveolar lavage (BAL) fluid biomarkers, cell proliferation methods, and histopathological evaluation of lung tissue at 24 h, 1 wk, 1 mo and 3 mo post instillation exposure. The bronchoalveolar lavage results demonstrated that lung exposures to quartz particles, at both concentrations but particularly at the higher dose, produced significant increases vs. controls in pulmonary inflammation and cytotoxicity indices. Exposures to M5 particulate and M5 long fiber preparation produced transient inflammatory and cell injury effects at 24 h postexposure (pe) as well as at 24 h and 1 wk pe, respectively, but these effects were not sustained when compared to quartz-silica effects. Exposures to carbonyl iron particles and PBS resulted in only minor short-term and reversible lung inflammation, likely related to the effects of the instillation procedure. Histopathological analyses of lung tissues revealed that pulmonary exposures to M5 particulate and in particular, the M5 long fiber preparation in rats produced some inflammatory responses, observed up to 1 wk postexposure. These responses were often associated with the presence of M5 long fiber in the airways or in the proximal alveolar regions but appeared to be reversible at 1 and 3 mo postexposure. In contrast, pulmonary exposures to silica-quartz particles in rats produced a dose-dependent lung inflammatory response characterized by neutrophils and foamy (lipid-containing) alveolar macrophage accumulation and evidence of early lung tissue thickening consistent with the development of pulmonary fibrosis. Based on our results, we conclude the following: (1) It was very difficult to produce M5 fibers into a respirable fibrous form; these findings suggest that aerosol exposure concentrations of respirable fibrous M5 in the workplace are likely to be rather low. (2) The particulate and long fiber preparations of M5 that were tested produced a moderate amount of pulmonary inflammatory activity, more active than our negative control, carbonyl iron particles, but substantially less active in terms of inflammation, cytotoxicity, and fibrogenic effects than the positive control particle type, silica-quartz particles. Thus, based on the results of this study, we would expect that inhaled M5 respirable fibers have a low risk potential for producing adverse pulmonary effects.     

Acute Pulmonary Inflammation Induced by Lung Overloading with Selenium Particles: Leukocyte Response and In Situ Detection of Selenium at High Resolution

The kinetics of the acute inflammatory response of the lung was triggered in CD-1 mice by a single intratracheal instillation of a large amount of Se (10 mg); it was studied by quantitative cytology of bronchoalveolar lavage samples, light microscopy, and scanning electron microscopy coupled with x-ray elemental microanalysis. Bronchoalveolar lavage leukocytes were mostly neutrophils and increased from 12 to 24 h of Se treatment and decreased at 72 h. Only less than half of the granulocytes showed ingested Se particles; in contrast, virtually all BAL macrophages contained Se particles. Scanning electron microscopy coupled with X-ray elemental microanalysis revealed that the intracellular Se particles were heterogeneous in size (diameters from 0.4 and up to 14 μm), and that Se inclusions were sometimes accumulated at a pole of the cell. At 72 h after instillation of the particles, Se-loaded alveolar macrophages were migrated in the interstitial space of the alveoli. Se-positive regions had a focal distribution in the lung; accumulation of inflammatory cells erased the alveolar architecture of these areas of the deep lung. Our data indicates that Se overloading of the lung results in: (1) an acute inflammatory response that is dominated by neutrophils; (2) early removal of Se done mostly by alveolar macrophages, and (3) formation of focal areas of invasion of the lung parenchyma by inflammatory infiltrates.     

Dexamethasone reduces lung eosinophilia,and VCAM-1 and ICAM-1 expression induced by Sephadex beads in rats

Airway eosinophilia is one of the key pathophysiologic features in asthma. The endothelial adhesion molecules, vascular cell adhesion molecule (VCAM-1) and intercellular adhesion molecule (ICAM-1), have previously been shown to play a crucial role in eosinophil recruitment into the inflamed airway. We have investigated the effects of dexamethasone on eosinophilia into the bronchoalveolar lavage fluid, and the upregulation of VCAM-1 and ICAM-1 expression, measured by immunoblotting, induced by i.v. injection of Sephadex beads into rats. The beads significantly increased the lung eosinophilia, and expression of VCAM-1 and ICAM-1 in the lung. Pretreatment with dexamethasone (0.1 to 2 mg/kg i.p.) strongly inhibited all the airway inflammatory events in a dose-dependent manner. In conclusion, glucocorticoids may be potent inhibitors of lung eosinophilia, at least in part, due to the prevention of the upregulation of VCAM-1 and ICAM-1 expression.     

Treatment with dexamethasone or liposome-encapsuled vitamin E provides beneficial effects after chemical-induced lung injury

The pathogenesis of lung injury by exposure to highly toxic sulfur and nitrogen mustards involves alkylating damage of the respiratory epithelium followed by an acute inflammatory response and lung edema. The acute phase is followed by long-term respiratory complications characterized by bronchitis, lung fibrosis, and airway hyperreactivity. In this study, we utilized a mouse model for airway inflammation induced by inhalation exposure to the alkylating nitrogen mustard melphalan, in order to investigate possible beneficial treatment effects by the corticosteroid dexamethasone. In addition, we investigated therapeutic efficacy of liposome-encapsuled vitamin E, an antioxidant formulation previously shown to be efficient in counteracting inflammatory conditions. Influx of inflammatory cells to airways, edema formation, and expression of different cytokines were analyzed 6 and 18 hours after exposure to melphalan. In order to evaluate long-term lung effects, we also investigated collagen deposition and accumulation of lymphocytes at 2 and 4 weeks after exposure. A single intraperitoneal injection of dexamethasone (10?mg/kg body weight) 1 hour after melphalan exposure significantly reduced interleukin (IL)-1 and IL-6 in bronchoalveolar lavage fluid (BALF) and diminished the acute airway inflammation. Our results also indicate that early single-dose treatment with dexamethasone protects against long-term effects observed 2–4 weeks after melphalan exposure, as indicated by reduced lymphocytic response in airways and decreased collagen deposition. Furthermore, our results indicate that also vitamin E (50?mg/kg) reduces acute inflammatory cell influx, and suppresses collagen formation in lung tissue, indicating that this drug could be used in combination with corticosteroids for protection against chemical-induced lung injury.     

Acute pulmonary inflammation induced by lung overloading with selenium particles: leukocyte response and in situ detection of selenium at high resolution

The kinetics of the acute inflammatory response of the lung was triggered in CD-1 mice by a single intratracheal instillation of a large amount of Se (10 mg); it was studied by quantitative cytology of bronchoalveolar lavage samples, light microscopy, and scanning electron microscopy coupled with x-ray elemental microanalysis. Bronchoalveolar lavage leukocytes were mostly neutrophils and increased from 12 to 24 h of Se treatment and decreased at 72 h. Only less than half of the granulocytes showed ingested Se particles; in contrast, virtually all BAL macrophages contained Se particles. Scanning electron microscopy coupled with X-ray elemental microanalysis revealed that the intracellular Se particles were heterogeneous in size (diameters from 0.4 and up to 14 microm), and that Se inclusions were sometimes accumulated at a pole of the cell. At 72 h after instillation of the particles, Se-loaded alveolar macrophages were migrated in the interstitial space of the alveoli. Se-positive regions had a focal distribution in the lung; accumulation of inflammatory cells erased the alveolar architecture of these areas of the deep lung. Our data indicates that Se overloading of the lung results in: (1) an acute inflammatory response that is dominated by neutrophils; (2) early removal of Se done mostly by alveolar macrophages, and (3) formation of focal areas of invasion of the lung parenchyma by inflammatory infiltrates.     

Effects of isoenzyme selective phosphodiesterase inhibitors on bacterial lipopolysaccharide-induced bronchial hyperreactivity in guinea pigs

• 1.1. Effects of cilostazol and vesnarinone (selective PDE III inhibitors), rolipram (selective PDE IV inhibitor) and theophylline (nonselective PDE inhibitor) on LPS-induced bronchial hyperreactivity were investigated in guinea pigs.
• 2.2. Cilostazol (50 mg/kg PO), vesnarinone (100 mg/kg PO), rolipram (20 mg/kg PO), and theophylline (50 mg/kg PO), significantly inhibited bronchial hyperreactivity to acetylcholine (Ach) and TNF release into bronchoalveolar lavage fluid following LPS exposure. None of these compounds influenced neutrophil influx into bronchoalveolar lavage fluid.
• 3.3. Rolipram and theophylline antagonized Ach-induced bronchoconstriction in normal guinea pigs.

     

Acute inflammatory reaction in rats after intratracheal instillation of material collected from a nylon flocking plant.

Several cases of interstitial lung disease have been diagnosed among workers at a nylon flock plant, but the etiologic agent for the disease outbreak was unknown. The results of a medical survey and industrial hygiene study indicated that the dust present in the plant may be responsible. Thus, airborne dust collected at the plant was examined for its inflammatory potential in rat lungs. The endpoints measured were: (1) breathing rates, (2) differential cell counts of bronchoalveolar lavage cells, (3) alveolar macrophage (AM) chemiluminescence, (4) albumin concentration and matrix metalloprotease activities in the acellular fluid from the initial bronchoalveolar lavage, and (5) pulmonary histopathology. In the first study, rats received a single dose of the airborne dust sample (10 mg/kg body weight) by intratracheal (IT) instillation. At 1 d post-IT, all inflammatory endpoints were significantly increased versus controls, but by 29 d post-IT they did not differ significantly from controls. Histopathology demonstrated mild to moderate, multifocal, suppurative pneumonia, usually centered around bronchioles, at 1 d post-IT. At 29 d post-IT, pulmonary inflammation was minimal to mild and characterized by alveolar histocytosis usually restricted to the immediate area of retained bire-fringent fibers. In subsequent experiments, airborne dust was extracted with water and the dust (washed airborne dust) and water extract (soluble fraction) were separated by centrifugation for further study. Nylon tow dust was prepared in the laboratory by milling uncut nylon strands (called tow) that had not been treated with the finish or dyes that are commonly used in the flock plants. Rats were administered a single dose of a dust sample (10 mg/kg body weight) or the soluble fraction (1.3 ml/kg body weight) by IT administration and the same endpoints were measured at 1 d post-IT. The dust samples caused significant increases in all of the inflammatory endpoints; however, the soluble fraction was much less active. Histological analysis of the lungs 1 d post-IT confirmed lung inflammation was occurring and tended to center around bronchioles. The results suggest that: (1) nylon flocking generates particles of respirable size that can interact with AM in the lung and can be detected in the lung 29 d after exposure, (2) the dust samples examined cause an inflammatory response, (3) water-extractable agent(s) from airborne dust contribute only minimally to the inflammatory response, and (4) the acute inflammatory response to these dusts is substantial when compared to other pathologic occupational dusts previously examined in our laboratory.     

ACUTE INFLAMMATORY REACTION IN RATS AFTER INTRATRACHEAL INSTILLATION OF MATERIAL COLLECTED FROM A NYLON FLOCKING PLANT

Several cases of interstitial lung disease have been diagnosed among workers at a nylon flock plant, but the etiologic agent for the disease outbreak was unknown. The results of a medical survey and industrial hygiene study indicated that the dust present in the plant may be responsible. Thus, airborne dust collected at the plant was examined for its inflammatory potential in rat lungs. The endpoints measured were: (1) breathing rates, (2) differential cell counts of bronchoalveolar lavage cells, (3) alveolar macrophage (AM) chemiluminescence, (4) albumin concentration and matrix metalloprotease activities in the acellular fluid from the initial bronchoalveolar lavage, and (5) pulmonary histopathology. In the first study, rats received a single dose of the airborne dust sample (10 mg/kg body weight) by intratracheal (IT) instillation. At 1 d post-IT, all inflammatory endpoints were significantly increased versus controls, but by 29 d post-IT they did not differ significantly from controls. Histopathology demonstrated mild to moderate, multifocal, suppurative pneumonia, usually centered around bronchioles, at 1 d post-IT. At 29 d post-IT, pulmonary inflammation was minimal to mild and characterized by alveolar histocytosis usually restricted to the immediate area of retained birefringent fibers. In subsequent experiments, airborne dust was extracted with water and the dust (washed airborne dust) and water extract (soluble fraction) were separated by centrifugation for further study. Nylon tow dust was prepared in the laboratory by milling uncut nylon strands (called tow) that had not been treated with the finish or dyes that are commonly used in the flock plants. Rats were administered a single dose of a dust sample (10 mg/kg body weight) or the soluble fraction (1.3 ml/ kg body weight) by IT administration and the same endpoints were measured at 1 d post-IT. The dust samples caused significant increases in all of the inflammatory endpoints; however, the soluble fraction was much less active. Histological analysis of the lungs 1 d post-IT confirmed lung inflammation was occurring and tended to center around bronchioles. The results suggest that: (1) nylon flocking generates particles of respirable size that can interact with AM in the lung and can be detected in the lung 29 d after exposure, ( 2) the dust samples examined cause an inflammatory response, (3) water-extractable agent(s) from airborne dust contribute only minimally to the inflammatory response, and (4) the acute inflammatory response to these dusts is substantial when compared to other pathologic occupational dusts previously examined in our laboratory.