Lung Inflammation In Rats Research Articles

Suppression of lung inflammation in rats by prevention of NF-kappaB activation in the liver.

Activation of NF-kappaB and production of NF-kappaB-dependent chemokines are thought to be involved in the pathogenesis of neutrophilic lung inflammation. Calpain-1 inhibitor (CI-1) blocks activation of NF-kappaB by preventing proteolysis of the inhibitory protein IkappaB-alpha by the ubiquitin/proteasome pathway. We hypothesized that inhibition of proteasome function with CI-1 would block NF-kappaB activation in vivo after intraperitoneal (i.p.) treatment with bacterial lipopolysaccharide (LPS), and that NF-kappaB inhibition would be associated with suppression of chemokine gene expression and attenuation of neutrophilic alveolitis. We treated rats with a single i.p. injection of CI-1 (10 mg/kg) two hours prior to i.p. LPS (7 mg/kg). Treatment with Cl-1 prevented degradation of IkappaB-alpha and activation of NF-kappaB in the liver in response to LPS; however, Cl-1 treatment had no detected effect on NF-kappaB activation in lung tissue. CI-1 treatment prior to LPS resulted in 40% lower MIP-2 concentration in lung lavage fluid compared to rats treated with vehicle prior to LPS (502 +/- 112 pg/ml vs. 859 +/-144 pg/ml, P < 0.05). In addition, CI-1 treatment substantially inhibited LPS-induced neutrophilic alveolitis (2.7+ /- 1.2 x 10(5) vs. 43.7 +/- 12.2 x 10(5) lung lavage neutrophils, P < 0.01). These data indicate that NF-kappaB inhibition in the liver can alter lung inflammation induced by systemic LPS treatment and suggest that a liver-lung interaction contributes to the inflammatory response of the lung.

Effect of Ozone on Diesel Exhaust Particle Toxicity in Rat Lung

Ambient particulate matter (PM) concentrations have been associated with mortality and morbidity. Diesel exhaust particles (DEP) are present in ambient urban air PM. Coexisting with DEP (and PM) is ozone (O3), which has the potential to react with some components of DEP. Some reports have shown increased lung injury in rats coexposed to PM and O3, but it is unclear whether this increased injury was due to direct interaction between the pollutants or via other mechanisms. To examine whether O3 can directly react with and affect PM bioactivity, we exposed DEP to O3 in a cell-free in vitro system and then examined the bioactivity of the resultant DEP in a rat model of lung injury. Standard Reference Material 2975 (diesel exhaust PM) was initially exposed to 0.1 ppm O3 for 48 h and then instilled intratracheally in Sprague–Dawley rats. Rat lung inflammation and injury was examined 24 h after instillation by lung lavage. The DEP exposed to 0.1 ppm O3 was more potent in increasing neutrophilia, lavage total protein, and LDH activity compared to unexposed DEP. The increased DEP activity induced by the O3 exposure was not attributable to alteration by air that was also present during the O3 exposure. Exposure of DEP to a higher O3 concentration (1.0 ppm) led to a decreased bioactivity of the particles. In contrast, carbon black particles, low in organic content relative to DEP, did not exhibit an increase in any of the bioactivities examined after exposure to 0.1 ppm O3. DEP incorporated O3 (labeled with 18O) in a linear fashion. These data suggest that ambient concentrations of O3 can increase the biological potency of DEP. The ozonized DEP may play a role in the induction of lung responses by ambient PM.

Activation of NF-κB by PM10 Occurs via an Iron-Mediated Mechanism in the Absence of IκB Degradation

Exposureto particulate air pollution (PM10) is associated with exacerbations of respiratory diseases and increased cardiopulmonary mortality. PM10 induces lung inflammation in rats, which has been attributed to many factors, including the ultrafine components of PM10, endotoxins, and transition metals. In this study, we investigated in alveolar epithelial (A549) cells whether PM10 could activate nuclear factor-kappa B (NF-κB), a transcription factor stimulated in response to many proinflammatory agents. Our results show that PM10 samples from various sites within the United Kingdom cause nuclear translocation, DNA-binding, and transcriptional activation of NF-κB in A549 cells. Furthermore, increased NF-κB activity was observed in the absence of IκB degradation. To evaluate the role of iron, A549 cells were exposed to PM10 previously treated with phosphate-buffered saline (PBS), deferoxamine mesylate, or deferoxamine plus ferrozine. PBS-treated and, to a lesser extent, deferoxamine-treated PM10 were able to activate NF-κB, whereas this response was completely abrogated in cells exposed to PM10 treated with both deferoxamine and ferrozine. Moreover, we studied the effects of soluble components of PM10 on NF-κB activation by exposing alveolar epithelial cells to soluble fractions from PM10 treated with PBS or the metal chelators. We found that, compared with fractions from PBS-treated PM10 which activated NF-κB, fractions from PM10 treated with deferoxamine and ferrozine did not stimulate NF-κB activity above background levels. Coincubation of polymixin B, an endotoxin-binding compound, and PM10 did not inhibit NF-κB. In summary, PM10 activates NF-κB in A549 cells by an iron-mediated mechanism in the absence of IκB degradation.

Role of P-selectin and ICAM-1 in pancreatitis-induced lung inflammation in rats: significance of oxidative stress.

To investigate the role of P-selectin and intercellular adhesion molecule-1 (ICAM-1) in the pathogenesis of lung injury associated with pancreatitis, and the relation between xanthine oxidase-derived oxidants and expression of these adhesion molecules. In acute pancreatitis, acute respiratory distress syndrome occurs in the early stages of disease. This process is mediated by neutrophil infiltration. Pancreatitis was induced in rats by intraductal administration of 5% sodium taurocholate. ICAM-1 and P-selectin expression was measured using radiolabeled monoclonal antibodies. Neutrophil infiltration and plasma levels of xanthine oxidase were also evaluated. Pancreatitis induces increases in P-selectin expression in lung, whereas ICAM-1 is unchanged from baseline levels. Immunoneutralization of either P-selectin or ICAM-1 prevents the infiltration of neutrophils into the lung. Xanthine and xanthine oxidase activity were increased after induction of pancreatitis. Xanthine oxidase inhibition prevents the upregulation of P-selectin in lung and neutrophil infiltration. During acute pancreatitis, P-selectin is upregulated in the pulmonary endothelium and is a key determinant of leukocyte recruitment. Constitutive ICAM-1 is also involved in the process of cell infiltration into the lung. The increased expression of P-selectin appears to be triggered by a mechanism dependent on free radicals generated by xanthine oxidase released by the damaged pancreas.

Appearance of cytokine-induced neutrophil chemoattractant isoforms and immunolocalization of them in lipopolysaccharide-induced acute lung inflammation in rats.

Recently, rat cytokine-induced neutrophil chemoattractant (CINC), which belongs to the interleukin-8 family, was grouped into four isoforms, CINC-1, CINC-2a, CINC-2beta, and CINC-3. To determine the major component and the source of CINC in airways, we investigated the change in appearance of CINC isoforms after exposure of rats to lipopolysaccharide. Male Sprague-Dawley rats, 8-10 weeks old, were used in the present study. Bronchoalveolar lavage (BAL) was performed at 1, 2, 4, 6, 12, and 24 h after lipopolysaccharide inhalation (4 mg/ml for 30 min). The concentrations of each specific rat CINC in the BAL supernatant were measured by use of commercially available kits. Furthermore, lung tissue was employed for immunohistochemical staining of CINCs (CINC-1, -2alpha,-2beta, and -3) using the streptavidin-biotin technique. Inhalation of lipopolysaccharide caused increases in CINC-1, CINC-2aalpha, and CINC-3 in BAL fluids, whereas CINC-2beta was not detected. The increases in CINC-2a and CINC-3 were less than the increase in CINC-1. Positive immunohistochemical staining for CINC-1 was detected in bronchial noncilliated cells and in certain neutrophils that had infiltrated into the submucosa. These findings suggest that CINC-1 is the major isoform among the four CINCs in lipopolysaccharide-induced acute lung inflammation in rats. Its sources are likely to be bronchial noncilliated cells and certain infiltrating neutrophils.

Eotaxin and eotaxin receptor (CCR3) expression in Sephadex particle-induced rat lung inflammation.

The beta chemokine eotaxin is a potent eosinophil activator and chemoattractant. We examined immunohistochemically eotaxin protein expression in a range of normal rat tissues and in rat lung during Sephadex particle-induced pulmonary inflammation. The time course of eotaxin expression in lung at various time points after Sephadex administration was related to the appearance of eosinophils in the bronchoalveolar lavage fluid and tissue distribution of eotaxin receptor (CCR3) positive cells. Results showed that eotaxin protein was constitutively expressed by both lung airway epithelial cells and gut epithelial cells in normal tissues in the absence of inflammation. During Sephadex induced pulmonary inflammation, eotaxin expression increased in alveolar macrophages prior to the major increase in eosinophil numbers which reached a peak at 72 h. The pattern of eotaxin pulmonary expression and the location of CCR3 receptor positive cells suggest a chemoattractant gradient resulting in migration firstly into the tissue and subsequently through the airway epithelium into the airways. Treatment of rats with the glucocorticoid dexamethasone or the immunosuppressant cyclosporin A reduced eosinophil entry into lung tissue and airways but had no apparent effect on eotaxin expression in vivo, indicating that both these drugs inhibit eosinophil recruitment either by an eotaxin-independent mechanism, or by targetting factors that synergise with eotaxin, or an event post eotaxin expression.

Cell injury and interstitial inflammation in rat lung after inhalation of ozone and urban particulates.

Coexposure of the lung to urban dust along with ozone appears to potentiate ozone-induced injury. This conclusion was derived from whole-lung studies involving tissue and lavaged cells, but we now speculate that the injury and inflammatory response at the main site of reactivity, the bronchoalveolar duct region, is underestimated by such whole-lung studies. We exposed rats to ozone at 0.8 ppm and urban particulates (EHC93) at 50 mg/m3 for 4 h. Animals were killed 33 h later with tritiated thymidine (3HT) injected 1.5 h before death. Lungs were fixed by vascular perfusion to avoid disturbing any epithelial cell changes or local inflammation and edema in the air spaces. Tissue was embedded from central and peripheral areas of the lung, then counts of labeled cells, polymorphonuclear leukocytes (PMN), and macrophages (MAC) were made separately on methacrylate sections. The results showed that epithelial cell injury and regeneration (% of 3HT-labeled cells) was greatest in the ozone plus dust group, and was three times higher in periductal areas than in whole-lung counts. Although some increase in inflammatory cells in the air spaces was found in the coexposure group, much higher numbers of PMN and MAC were counted in the lung tissue compartment, and counts were significantly higher than those found after ozone or dust alone. Values from the latter groups were also higher than those from air controls or samples of distal lung taken from any inhalation group. The results demonstrate that inhalation of an urban dust at a level that causes few lung effects when inhaled alone can potentiate ozone toxicity, particularly in the vicinity of the alveolar duct, where the accumulation of interstitial inflammatory cells may be an important factor in the development of any subsequent pathologic changes.

Regulatory Effects of Endogenous Protease Inhibitors in Acute Lung Inflammatory Injury

Inflammatory lung injury is probably regulated by the balance between proteases and protease inhibitors together with oxidants and antioxidants, and proinflammatory and anti-inflammatory cytokines. Rat tissue inhibitor of metalloprotease-2 (TIMP-2) and secreted leukoprotease inhibitor (SLPI) were cloned, expressed, and shown to be up-regulated at the levels of mRNA and protein during lung inflammation in rats induced by deposition of IgG immune complexes. Using immunoaffinity techniques, endogenous TIMP-2 in the inflamed lung was shown to exist as a complex with 72- and 92-kDa metalloproteinases (MMP-2 and MMP-9). In inflamed lung both TIMP-2 and SLPI appeared to exist as enzyme inhibitor complexes. Lung expression of both TIMP-2 and SLPI appeared to involve endothelial and epithelial cells as well as macrophages. To assess how these endogenous inhibitors might affect the lung inflammatory response, animals were treated with polyclonal rabbit Abs to rat TIMP-2 or SLPI. This intervention resulted in significant intensification of lung injury (as revealed by extravascular leak of albumin) and substantially increased neutrophil accumulation, as determined by cell content in bronchoalveolar lavage (BAL) fluids. These events were correlated with increased levels of C5a-related chemotactic activity in BAL fluids, while BAL levels of TNF-alpha and chemokines were not affected by treatment with anti-TIMP-2 or anti-SLPI. The data suggest that endogenous TIMP-2 and SLPI dynamically regulate the intensity of lung inflammatory injury, doing so at least in part by affecting the generation of the inflammatory mediator, C5a.

Regulation of Acute Lung Inflammatory Injury by Endogenous IL-13

Using IgG immune complex deposition to trigger acute lung inflammation in rats, we have previously shown that exogenously administered IL-13 suppresses the acute inflammatory response. In the same model, expression of both mRNA and protein for IL-13 has now been detected. Treatment of rats with Ab to IL-13 accentuated the inflammatory response, with significant increases in lung vascular permeability and in the number of neutrophils in bronchoalveolar lavage fluids. In the presence of anti-IL-13, activation of the transcription factor, NF-kappaB, was significantly increased in lung. In addition, anti-IL-13 caused significant increases in bronchoalveolar lavage levels of TNF-alpha, macrophage inflammatory protein-2, and cytokine-inducible neutrophil chemoattractant but no changes in lung vascular ICAM-1. These data suggest that during lung inflammation endogenous IL-13 regulates NF-kappaB activation and related cytokine/chemokine generation, all of which determines the intensity of the lung inflammatory response.

Effects of interleukin-10 and modulators of cyclic AMP formation on endotoxin-induced inflammation in rat lung.

The aim of this study was to investigate the effects of IL-10, a cell permeable analogue of cyclic AMP, dibutyryl-cAMP (db-cAMP), modulators of intracellular cyclic AMP such as phosphodiesterase (PDE) inhibitors and a beta 2-adrenoceptor agonist, salmeterol, on pulmonary inflammation following acute lung injury induced by endotoxin exposure in rats. Pulmonary inflammation was induced in adult Wistar rats by a 60-min exposure to endotoxin (lipopolysaccharide, LPS, 100 micrograms/mL). 4 h later bronchoalveolar lavage (BAL) was performed. The PDE inhibitors, rolipram (3 and 5 mg/kg) and theophylline (30 and 100 mg/kg) inhibited neutrophil recruitment, TNF-alpha release and cellular activation in BAL. Salmeterol (0.5 mg/mL) and IL-10 (0.1 microgram) only inhibit TNF-alpha increase in the BAL fluid and db-AMPc (2.5 micrograms/rat) was ineffective. The present data show that the selective PDE4 inhibitor, rolipram, and the non-selective PDE inhibitor, theophylline, markedly reduced the pulmonary inflammation associated with acute lung injury in the rat. These effects may be mediated in part by IL-10 rather than by cyclic AMP, as demonstrated by the potent inhibitory activity of exogenous IL-10 on the increase in TNF-alpha release in BAL fluid of rats exposed to LPS.

ACUTE BIOLOGICAL EFFECTS OF INTRATRACHEALLY INSTILLED TITANIUM DIOXIDE WHISKERS COMPARED WITH NONFIBROUS TITANIUM DIOXIDE AND AMOSITE IN RATS

The dimensions of man-made mineral fiber whiskers are similar to those of some kinds of asbestos. Thus these mineral fibers raise the concern for potential health hazard for workers exposed in the occupational environments. This study was designed to define acute biological effects of intratracheally administered titanium dioxide whiskers (TO1) compared with nonfibrous titanium dioxide (TOP) and UICC amosite (Ams), and their relations to acute lung inflammation in rats. The observed geometric mean length (mum) and width (mum) and geometric standard deviation are: TO1(2.1[2.0], 0.14[1.53]); Ams (4.3[3.3], 0.31[1.9]); and TOP (50 nm, 1-2 mum aggregates). Ten-week-old Wistar-Jcl male rats received a single tracheal injection of test materials at doses between 0.05 and 1.0 mg/rat. Control animals were injected with the same volume of saline. Lung tissue and bronchoalveolar lavage (BAL) fluid were collected from rats on days 1, 3, and 7 after administration. In the group injected with TO1, total protein, cytokine-induced neutrophil chemoattractant (CINC)/growth-regulated gene product (GRO), interleukin (IL) 1, and tumor necrosis factor (TNF) increased on day 1. Subsequently, total elastolytic activity and fucose levels in BAL increased by day 3. All parameters, except for fucose in BAL, recovered to the normal levels. Animals in the Ams group showed increased total protein and CINC/GRO and decreased total elastolytic activity in a dose-dependent manner on day 1. The fucose level increased on day 3 in the Ams group. All parameters returned to their control levels on day 7. Animals in the TOP group did not show significant changes any of parameters during the experimental period. Gene expression of TNF- and mono cyte chemoattractant protein (MCP) 3 in the lung increased dose-dependently in the animals treated with the three materials. The mRNAs for eotaxin and MIP-1 were overexpressed in the lung of animals treated with Ams and TO1, while RANTES mRNA was overexpressed dose-dependently in the lung of animals treated with Ams on day 1. Onset of inflammatory response was more rapid in the Ams group than the TO1 group. Recovery of the fucose level in BAL was slower in the TO1 group than in the Ams group, though we observed similar histopathological changes in the lung of animals with TO1 or Ams. We conclude that whisker-induced acute biological effects in the lung may be related to the shape of the whiskers and not to their chemical composition or surface crystal structure, showing biological effects similar to those of UICC amosite.

The role of oxidative stress in the prolonged inhibitory effect of ultrafine carbon black on epithelial cell function

Respired ultrafine particles induce a greater inflammation in rat lungs than fine particles; we have hypothesized that this is due to their comparatively huge number and surface area for the production of free radicals. We tested this hypothesis by studying the effects of fine and ultrafine (uf) carbon black (CB) particles in comparison with quartz on A549 human type II alveolar epithelial cells, particularly with respect to the oxidative properties of these particles. Treatment with fine CB (diameter 260 nm), and quartz (up to 0.78 μg/mm 2) for 24 hours significantly ( P<0.05) decreased the A549 cells metabolic competence, as measured by the ability to reduce MTT to a formazan product. The inhibitory effects of uf CB only became significantly different ( P<0.05) relative to the control at 48 hours, by which time the effects of fine CB and quartz were no longer significant. The inhibition of MTT reduction by uf CB was prevented by the hydroxyl radical scavenger mannitol (2 m m). In addition, measurement of reactive oxygen species production using supercoiled plasmid DNA showed that uf CB exhibited significantly more free radical activity than fine CB ( P<0.05). In the absence of serum, uf CB depleted reduced glutathione at 6 hours ( P<0.008). In contrast, CB did not significantly alter reduced or oxidized glutathione. Hence, compared with fine CB, uf CB exhibited greater free radical activity, greater inhibition of the reduction of MTT at 48 hours (prevented by mannitol) and a depletion of reduced glutathione. These results suggest that uf CB induces a greater oxidative stress than fine CB, and that this may play a role in the toxicological effects of this ultrafine particle.

Vitamin A Inhibits Radiation-Induced Pneumonitis in Rats

Radiation-induced lung injury frequently limits the total dose of thoracic radiotherapy that can be delivered, and the determinants of host susceptibility are poorly understood. To test the hypothesis that vitamin A status may be an important, modifiable host determinant of radiation-induced lung injury, we determined the effect of altered vitamin A status on radiation-induced lung inflammation in rats. WAG-Rij Y rats were fed a diet deficient in or supplemented with vitamin A (0 units/kg or 80,000 units/kg diet). After 5 wk of consuming the prescribed diet, rats were irradiated with 15 Gy of 250 kV X-rays to the whole thorax. At 4-5 wk post-irradiation, there were significantly fewer neutrophils on bronchoalveolar lavage in rats fed the vitamin A–supplemented diet (8.8 ± 1.2% neutrophils) compared with those fed the vitamin A–deficient diet (20.8 ± 3.4% neutrophils, P < 0.01). At the termination of the experiment, 4–5 wk postradiation, lung retinol levels of the vitamin A–supplemented group were 19.6 ± 1.8 nmol/g, whereas those in the vitamin A–deficient group were significantly lower, 1.7 ± 0.5 nmol/g (P < 0.01). These findings suggest that supplemental vitamin A may reduce lung inflammation after thoracic radiation and be an important modifiable radioprotective agent in the lung.

Freshly generated stainless steel welding fume induces greater lung inflammation in rats as compared to aged fume

It has been previously reported that both short- and long-lived reactive oxygen species (ROS) are present on the surface of freshly generated fumes. The objective of this study was to determine if freshly formed welding fume induces greater lung inflammation and injury in rats due to the presence of reactive oxygen species than aged welding fume. Fume was collected during gas metal arc welding using a stainless steel consumable electrode and found to be of respirable size with a mean diameter of 0.77 μm±0.48. Male CD/VAF rats were dosed intratracheally with the welding fume 30 min (fresh) and 1 and 7 days (aged) after fume collection at a dose of 1.0 mg/100 g b wt. Bronchoalveolar lavage (BAL) was performed 24 h post-instillation. Lung injury and inflammation were assessed by measuring the concentration of neutrophils, albumin, lactate dehydrogenase (LDH), and glucosaminidase (GLU) in the recovered BAL fluid. More neutrophils and enhanced GLU activity were observed for the ‘fresh’ group as compared to both ‘aged’ groups ( P<0.05). Slight, but not significant, elevations were seen in albumin content and LDH activity for the ‘fresh’ group as compared to the ‘aged’ groups. No significant differences were observed for any of the parameters when fume aged for 1 and 7 days were compared. When the ‘fresh’ and ‘aged’ fumes (12.5, 25, and 50 μg/ml) were suspended in dichlorofluorescin (15 μM), a probe which becomes fluorescent when oxidized, the concentration-dependent increases in fluorescence were greater for the ‘fresh’ fume versus the ‘aged’ fumes. We have demonstrated that freshly generated stainless steel welding fume induces greater lung inflammation than ‘aged’ fume. This is likely due to a higher concentration of ROS on fresh fume surfaces.

Dietary restriction mitigates ozone-induced lung inflammation in rats: a role for endogenous antioxidants.

Studies were undertaken to determine whether dietary restriction protects against acute pulmonary oxidant challenge. Male F344 rats were fed NIH-31 diet either ad libitum or at restricted levels equal to 75% that of ad libitum intake. After 3 wk of dietary adaptation, animals were exposed by inhalation to 2.0 ppm ozone (O3) for 2 h or chamber air and evaluated for cellular and biochemical indices of pulmonary toxicity. Compared to air controls, bronchoalveolar lavage fluid (BALF) from O3 exposed ad libitum fed rats contained increased protein (145 versus 380 microg/ml), PMN infiltration (0 versus 11%) and fibronectin (45 versus 607 U/ml). Diet restriction abrogated these indicators of pulmonary inflammation induced by ozone. Binding of 18O3 to BALF protein and cells was significantly decreased in diet restricted rats while BALF ascorbate and glutathione levels, but not alpha-tocopherol or urate, were elevated compared to ad libitum fed rats. Taken together, these results indicate that dietary restriction affords protection against O3-induced oxidant toxicity. Protection is mediated partially by increases in ascorbate in the fluid bathing the lung surface, thereby providing an antioxidant sink which minimizes the ability of O3 to reach biological targets.

Indium phosphide and lung inflammation in rats

Indium phosphide and lung inflammation in rats

The Protective Effect of Inhaled NO on Hyperoxic Lung Inflammation is Associated with an Inhibition of P-Selectin Expression in Lung Tissue. • 1508

Pulmonary hypertension in newborns is commonly treated with a combination of inhaled nitric oxide (NO) and high concentrations of supplemental oxygen. Hyperoxia-induced lung injury is associated with inflammation, which in a variety of animal models is associated with upregulation of adhesion molecules crucial for the development of inflammation such as intercellular adhesion molecule-1 (ICAM-1), P-selectin and E-selectin. We have previously shown that inhaled NO at 100 ppm reduces hyperoxia-induced lung inflammation in rats. Others have found that NO inhibits leukocyte adhesion through its inhibition of endothelial adhesion molecule expression. We therefore hypothesized that NO would inhibit the upregulation of the adhesion molecules ICAM-1, E-selectin and P-selectin in rats exposed to >95% O2. Lung tissue was obtained at 24, 48, 60 h from adult male Sprague-Dawley rats exposed to either >95%+ 100 ppm of inhaled NO or >95% oxygen alone. Lung samples were also taken from airbreathing rats and used as controls. Inflammatory cells were identified by staining with myeloperoxidase, and adhesion molecule expression was determined by Western blotting. We found an increase in lung interstitial neutrophils over time in hyperoxia (p<0.05), and a significant decrease in interstitial neutrophils at 48 (p<0.001), and at 60 (p<0.001) h of exposure to hyperoxia with NO. In the same lungs there was increased P-selectin, E-selectin, and ICAM-1 expression as a function of hyperoxia-exposure time (p<0.05), while inhaled NO led to a decrease in P-selectin upregulation (p<0.002) at 60 h. Inhaled NO had no statistically significant effect on E-selectin or ICAM-1 expression. In conclusion, inhaled NO may reduce hyperoxia-induced lung inflammation by decreasing the upregulation of P-selectin in lung tissue, and may exert a beneficial effect by modulating lung inflammation and adhesion molecule expression in hyperoxia-exposed lungs.Supported by NIH grant 5 P30 HD27823-04

Role of complement, chemokines, and regulatory cytokines in acute lung injury.

The roles of complement, proinflammatory cytokines and regulatory cytokines in lung inflammatory injury are becoming defined. Like the proinflammatory cytokines (TNF alpha and IL-1), complement activation products (C5a and/or the membrane attack complex, C5b-9) can directly activate endothelial cells to cause upregulation of adhesion molecules (P-selectin) or can function in a synergistic manner with TNF alpha to cause enhanced upregulation of ICAM-1 and E-selectin. The beta chemokine, MIP-1 alpha, appears to function in vivo as an autocrine activator, enhancing TNF alpha production by pulmonary macrophages, which, in turn, enhances the inflammatory response. Finally, IL-4 and IL-10 have strong regulatory effects by suppressing in vivo production of TNF alpha. There is now compelling evidence to suggest that, in IgG immune-complex-induced lung inflammation in rats, endogenous IL-10 is produced and regulates the intensity of the inflammatory response. Blocking of endogenous IL-10 substantially increases lung TNF alpha production, the recruitment of neutrophils, and the intensity of lung inflammatory injury. Accordingly, the network of cytokines carefully regulates lung inflammatory responses.

Reactive oxygen intermediates as regulators of TNF-alpha production in rat lung inflammation induced by silica.

Abstract Exposure to mineral dusts such as silica has been associated with progressive pulmonary inflammation and fibrosis. There is evidence that the release of reactive oxygen intermediates (ROI) and cytokines by alveolar macrophages (AM) is involved in lung injury associated with silica exposure. However, the chronology and relationship between these two mediators are poorly understood. In this study, an animal model of silicosis has been used, allowing simultaneous follow-up of lung histopathologic state, AM TNF-alpha production at the protein (biologic assay) and mRNA (reverse transcriptase-PCR) levels, and the release of ROI (luminol-dependent chemiluminescence), after bronchoalveolar lavages. In particular, it has been shown that intratracheal instillation of silica (50 mg/kg) in rats led to fibrosis characterized by cellular interstitial infiltrates with granulomas, and in AM, it led to 1) an early and continuous increase in 12-O-tetradecanoylphorbol-13-acetate- or zymosan-triggered ROI production (days 1, 3, 14, and 28 post-treatment), and 2) a rise of TNF-alpha mRNA expression and protein secretion on days 3 and 14. A free radical scavenger pretreatment (N-ter-butyl-alpha-phenylnitrone) reversed lung histopathologic changes and decreased AM ROI production and TNF-alpha expression at the level of mRNA. These findings suggest that ROI production is an important primary event determining the silica-induced inflammatory process. ROI may act in an autocrine or paracrine manner and regulate TNF-alpha production by a mechanism promoting gene expression. The critical role of this cytokine in the pathogenesis of silicosis was confirmed by anti-TNF-alpha Ab treatment.

Anti-inflammatory 17beta-thioalkyl-16alpha,17alpha-ketal and -acetal androstanes: a new class of airway selective steroids for the treatment of asthma.

The synthesis and anti-inflammatory potencies of a new class of 17beta-thioalkyl-16alpha,17alpha-ketal and -acetal androstanes are described. This new class of steroids was made by fragmentation of 2-thioxo-1,2-dihydropyrid-1-yl esters of the corresponding 17-acids to the 17-radical. The radical generated was trapped using a variety of radicophilic disulfides, giving a steroidal D-ring having acetal or ketal functionality at C-16 and C-17, together with a sulfide link at C-17. Compounds from this series bind to the glucocorticoid receptor with high potency and are functional agonists as measured by their ability to induce tyrosine aminotransferase activity in a rat hepatic cell line in vitro. These 17beta-thioalkyl androstanes potently inhibit Sephadex-induced rat lung inflammation when administered directly into the airways. The high topical potency, together with a low propensity to induce systemic glucocorticoid-like side effects (rat thymus involution), provides the present compounds with a high degree of airway selectivity compared with currently available inhaled glucocorticoids. The presently described 17beta-thioalkyl-16alpha,17alpha-ketal androstanes may be useful for therapies for inflammatory diseases such as asthma.