Vedolizumab, a humanized monoclonal antibody approved for the treatment of adults with moderately to severely active ulcerative colitis or Crohn disease, targets α4β7 integrin and selectively blocks gut-specific lymphocyte trafficking. The potential effects of vedolizumab on development were assessed by standard preclinical toxicity studies in rabbits and cynomolgus monkeys. A single infusion of vedolizumab (0, 10, 30, or 100 mg/kg) was administered intravenously to pregnant rabbits on gestational day 7; rabbits were monitored to gestational day 29. Vedolizumab (0, 10, or 100 mg/kg) was administered intravenously every 2 weeks to pregnant cynomolgus monkeys beginning on gestational day 20 with the last dose on gestational day 132 (9 doses total). In rabbits, vedolizumab did not affect maternal net body weight or net gains, gravid uterine weights, or mean maternal food consumption, nor did it affect intrauterine growth or fetal survival. There were also no vedolizumab effects on embryo-fetal development compared to controls. In cynomolgus monkeys, there was no increase in prenatal loss/death or stillbirth and no maternal toxicity associated with vedolizumab. On day 28 postpartum, low levels of vedolizumab were detected in the breast milk of 3 of 11 monkeys in the 100 mg/kg group. No vedolizumab-related effects on the number of infants born, infant development, or animal hematology or clinical chemistry were noted. Administration of vedolizumab to pregnant rabbits and cynomolgus monkeys did not show any potential for maternal or developmental effects.

Vedolizumab (VDZ) is a gut-selective humanised monoclonal antibody targeting α4β7 integrin, approved for adults with moderate-to-severe ulcerative colitis and Crohn’s disease. The few publications reporting on VDZ use in pregnancy have not identified any incidence of maternal or foetal toxicity. The objective of this study was to evaluate the effects of VDZ on pregnancy, parturition and lactation in cynomolgus monkeys and on survival, growth and postnatal development of the offspring. Non-fasted pregnant cynomolgus monkeys were randomly assigned to receive 0 mg/kg (saline control), 10 mg/kg (human equivalent dose [HED]: 3.2 mg/kg) or 100 mg/kg (HED: 32.3 mg/kg) of VDZ (n = 12/group) every 2 weeks (total of nine intravenous infusions between gestational Days [GD] 20 and 140). Dams and infants were monitored for clinical signs, development, neurobehaviour and grip strength, then euthanised at 181 ± 1 days postpartum. Levels of VDZ and primate anti-human antibody (PAHA) were assessed by direct enzyme-linked immunosorbent assay (ELISA) in the serum at GD 20 and 132 and in the breast milk at 28 ± 1 days postpartum of the dams, and in the serum of the infants at postpartum Days 20 and 120. The number of pregnant females was similar across the three groups. There were no VDZ-related maternal deaths and no increase in the incidence of prenatal loss or stillbirth in any group. No VDZ-related effects on the number of infants born, clinical signs or infant development were noted. In the dams at GD 132, time to the maximum serum concentration of VDZ after administration was 3.4 ± 6.7 h in the 100 mg/kg group (Table 1). At necropsy, no VDZ-related maternal organ toxicity was found. Low levels of VDZ (0.16–0.27 μg/ml) were found in the breast milk of 3/11 monkeys in the 100 mg/kg group. No VDZ-related effects were found on grip strength, neurobehavioural or morphological assessments in the infants. In the 10 and 100 mg/kg groups, positive PAHA titres were detected in 9/12 dams (each group), and 2/7 and 1/9 infants, respectively. Neutralising effects on VDZ toxicokinetics and pharmacodynamics were strongest in pregnant monkeys dosed at 10 mg/kg. Administration of VDZ to pregnant monkeys resulted in no evidence of effects on teratogenicity, prenatal or postnatal neurobehavioural and overall development in infants up to 6 months of age. At the no-observed-adverse-effect-level of 100 mg/kg, the serum exposure was 346 times higher in monkeys than in humans dosed at VDZ 300 mg.

examine the possibility that these mediators may account for some of the pathophysiologic alterations seen in the lung after ozone (03) exposure, human AM were collected by bronchoalveolar lavage of normal subjects, plated into tissue culture dishes, and the adherent cells were incubated with [H]AA or [H!lysoPAF. Human AM exposed to 1.0 ppm 03 for 2 hr released 65 ? 12% more tritium, derived from [3HJAA, than paired, air-exposed controls into media supernatants. In other studies using a similar O3 exposure protocol, there was also a significant increase in human AM prostaglandin E2 production (2.0 0.5-fold increase above air-exposure values, p < 001, n = 17). In additional studies, using a similar O3 exposure protocol (1.0 ppm for 1 hr), there was also a significant increase in human AM PAF content (1.7 ? 0.2-fold increase above air-exposure values, p < 0.02, n = 5). These potent lipid mediators, originally derived from human AM, may play an important role in the mechanisms of 03 lung toxicity.

STUDY OBJECTIVESThe clinical outcomes and health-care costs of a cohort of 413 patients with COPD are reported.DESIGNThis study was a retrospective pharmacoeconomic analysis.SETTINGUniversity teaching hospital and affiliated clinics.PATIENTSCOPD patients with an FEV(1) < 65% of predicted and an FEV(1)/FVC ratio < 70% were eligible to be included in this analysis.INTERVENTIONSHealth-care resource utilization and costs were identified through chart review and were stratified according to the severity of COPD using the American Thoracic Society stages I, II, and III. The pharmacoeconomic analysis was a cost-of-illness evaluation that included the acquisition costs of initially prescribed pulmonary drugs, acquisition cost of pulmonary drugs added during the follow-up period, oxygen therapy, laboratory and diagnostic test costs, clinic visit costs, and emergency department and hospital costs.RESULTSTotal treatment cost was highly correlated with disease severity, with stage I COPD having the lowest cost ($1,681 per patient per year), stage III COPD having the highest cost ($10, 812 per patient per year), and stage II COPD having a cost intermediate to stage I and stage III ($5,037 per patient per year). With the exception of add-on drug acquisition cost, all cost variables were the highest in stage III COPD, the lowest in stage I COPD, and intermediate in stage II COPD. Hospitalization was the most important cost variable for all three stages of COPD severity. When stratified by both disease severity and initial bronchodilator drug selection, ipratropium alone in stage I COPD patients and the combination of ipratropium plus a ss-agonist (with or without steroid therapy) in stage II and stage III COPD patients had the lowest total costs. Reasons for the lower total cost of the ipratropium and ipratropium plus ss-agonist treatment groups included lower add-on drug costs, fewer diagnostic and laboratory tests, and a lower utilization rate for clinic visits, emergency department visits, and hospitalizations.CONCLUSIONSOur study demonstrates a strong correlation between disease severity and total treatment cost in COPD. In addition, the type of bronchodilator therapy impacts total cost in COPD. In stage I COPD, ipratropium alone had the lowest total cost, while in stage II and stage III COPD, a combination of ipratropium plus a ss-agonist had the lowest total cost. These data support the concept that adherence to published treatment guidelines will result in lower health-care costs due to COPD.

Ozone (O 3 ) is a major component of smog and an inhaled toxicant to the lung. O 3 rapidly reacts with the airway epithelial cell membrane phospholipids to generate lipid ozonation products (LOP). 1‐Hydroxy‐1‐hydroperoxynonane (HHP‐C9) is an important LOP, produced from the ozonation of 1‐palmitoyl‐2‐oleoyl‐sn‐glycerol‐3‐phosphatidylcholine. This LOP, at a biologically relevant concentration (100 μM), increases the activity of phospholipase C, nuclear factors‐κB (NF‐κB), and interleukin‐6 (NF‐IL‐6) and the expression of the inflammatory gene, interleukin‐8 (IL‐8) in a cultured human bronchial epithelial cell line (BEAS‐2B). The signaling pathways of ozone and its biologically‐active products are as yet undefined. In the present study, we report that the HHP LOP, HHP‐C9 (100 μM × 4 h), activated the expression of IL‐8 (218 ± 26% increase over control, n = 4, P < 0.01) through an apparent interaction between the two transcription factors, NF‐κB and NF‐IL‐6. Transfection studies using luciferase reporter assays demonstrated that HHP‐C9 induced a significant increase in NF‐κB‐DNA binding activity (37 ± 7% increase over control, n = 6, P < 0.05). Inhibition of NF‐κB showed a statistically significant but modest decrease in IL‐8 release, which suggested a role for another transcription factor, NF‐IL‐6. Exposure of BEAS‐2B cells to HHP‐C9 induced a significant increase in the DNA binding activity of NF‐IL‐6 (45 ± 11% increase over control, n = 6, P < 0.05). The results of the present study indicate that NF‐IL‐6 interacts with NF‐κB in regulating the expression of IL‐8 in cultured human airway epithelial cells exposed to LOP, the biological products of ozone in the lung. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 159–168, 2007.

RATIONALE: IL-16 has been shown to decrease Th2 cytokines in vitro by decreasing antigen driven activation and to decrease inflammation in an animal model. A 16 amino acid peptide from the C-terminus of IL-16 blocks IL-16 mediated CD4+ lymphocyte migration in vitro and has been shown to decrease airway hyperresponsiveness in an animal model. We hypothesized that expression of this IL-16 peptide in vivo would decrease inflammation and Th2 cytokines in a murine asthma model. METHODS: Transgenic (TG) mice expressing the IL-16 C-terminal peptide from the airway epithelial-specific Clara cell secretory protein promoter were generated. The IL-16 peptide was fused to a signal sequence and a FLAG epitope tag. Transgene expression was detected in the lungs by Northern blot analysis and FLAG immunohistochemistry. Untreated TG mice exhibited normal lung histology. TG mice and non-transgenic (NTG) controls were sensitized with ovalbumin (OVA) intraperitoneally and challenged with aerosolized OVA. RESULTS: Histological scores for tissue inflammation in OVA mice were significantly lower in TG mice compared to NTG mice (p<0.05). There was no significant difference in lavage fluid eosinophils between TG and NTG mice. IL-4 levels in lavage fluid were significantly lower from OVA TG mice compared to OVA NTG (p<0.05). IL-5 and IL-13 levels were not significantly different. Quantitation of PAS staining indicated that mucus production was significantly lower in the OVA TG mice compared with OVA NTG mice (p<0.01). CONCLUSIONS: Expression of IL-16 peptide in vivo inhibits allergic tissue inflammation, IL-4 production, and mucus production in a murine model of allergic inflammation.

Isocyanates are a common cause of occupational lung disease. Hexamethylene diisocyanate (HDI), a component of polyurethane spray paints, can induce respiratory symptoms, inflammation, lung function impairment, and isocyanate asthma. The predominant form of HDI in polyurethane paints is a nonvolatile polyisocyanate known as HDI biuret trimer (HDI-BT). Exposure of mice to aerosolized HDI-BT results in pathological effects, including pulmonary edema, lung inflammation, cellular proliferation, and fibrotic lesions, which occur with distinct time courses following exposure. To identify genes that mediate lung pathology in the distinct temporal phases after exposure, gene expression profiles in HDI-BT-exposed C57BL/6J mouse lungs were analyzed. RNase protection assay (RPA) of genes involved in apoptosis, cell survival, and inflammation revealed increased expression of IkappaBalpha, Fas, Bcl-X(L), TNFalpha, KC, MIP-2, IL-6, and GM-CSF following HDI-BT exposure. Microarray analysis of approximately 10000 genes was performed on lung RNA collected from mice 6, 18, and 90 h after HDI-BT exposure and from unexposed mice. Classes of genes whose expression was increased 6 h after exposure included those involved in stress responses (particularly oxidative stress and thiol redox balance), growth arrest, apoptosis, signal transduction, and inflammation. Types of genes whose expression was increased at 18 h included proteinases, anti-proteinases, cytoskeletal molecules, and inflammatory mediators. Transcripts increased at 90 h included extracellular matrix components, transcription factors, inflammatory mediators, and cell cycle regulators. This characterization of the gene expression profile in lungs exposed to HDI-BT will provide a basis for investigating injury and repair pathways that are operative during isocyanate-induced lung disease.

Macrophages play a fundamental role in silicosis in part by removing silica particles and producing inflammatory mediators in response to silica. Tumor necrosis factor alpha (TNFalpha) is a prominent mediator in silicosis. Silica induction of apoptosis in macrophages might be mediated by TNFalpha. However, TNFalpha also activates signal transduction pathways (NF-kappaB and AP-1) that rescue cells from apoptosis. Therefore, we studied the TNFalpha-mediated mechanisms that confer macrophage protection against the pro-apoptotic effects of silica. We will show that exposure to silica induced TNFalpha production by RAW 264.7 cells, but not by IC-21. Silica-induced activation of NF-kappaB and AP-1 was only observed in RAW 264.7 macrophages. ERK activation in response to silica exposure was only observed in RAW 264.7 macrophages, whereas activation of p38 phosphorylation was predominantly observed in IC-21 macrophages. No changes in JNK activity were observed in either cell line in response to silica exposure. Silica induced apoptosis in both macrophage cell lines, but the induction of apoptosis was significantly larger in IC-21 cells. Protection against apoptosis in RAW 264.7 cells in response to silica was mediated by enhanced NF-kappaB activation and ERK-mediated phosphorylation of the p55 TNFalpha receptor. Inhibition of these two protective mechanisms by specific pharmacological inhibitors or transfection of dominant negative mutants that inhibit IkappaBalpha or ERK phosphorylation significantly increased silica-induced apoptosis in RAW 264.7 macrophages. These data suggest that NF-kappaB activation and ERK-mediated phosphorylation of the p55 TNF receptor are important cell survival mechanisms in the macrophage response to silica exposure.

The gene encoding the p53 tumor suppressor protein is commonly mutated in many human cancers, including lung cancer, 1 Greenblatt MS Bennett WP Hollstein M et al. Mutations in the p53 tumor suppressor gene: clues to cancer etiology and molecular pathogenesis. Cancer Res. 1994; 54: 4855-4878 PubMed Google Scholar but p53 mutations are relatively rare in murine lung tumors induced by carcinogen exposures. 2 Dragani TA Manenti G Pierotti MA Genetics of murine lung tumors. Adv Cancer Res. 1995; 67: 83-112 Crossref PubMed Scopus (59) Google Scholar To model the pathogenesis of human lung cancers in mice, we disrupted wild-type p53 activities by transgenically expressing a dominant-negative form of p53 specifically in the lung epithelium using the human surfactant protein C (SPC) promoter, SPC-DNp53 mice. 3 Morris GF Hoyle GW Athas GB et al. Lung-specific expression in mice of a dominant negative mutant form of the p53 tumor suppressor protein. J La State Med Soc. 1998; 150: 179-185 PubMed Google Scholar Distinct responses to fibrogenic agents have indicated that the transgene has altered the phenotype of SPC-DNp53 mice. 4 Ghosh S Mendoza T Ortiz LA et al. Bleomycin sensitivity of mice expressing dominant negative p53 in the lung epithelium. Am J Respir Crit Care Med. 2002; 166: 890-897 Crossref PubMed Scopus (35) Google Scholar However, the low incidence and delayed onset of lung tumor development in unexposed SPC-DNp53 mice imply that the oncogenic p53 transgene requires additional activities to complete the process of neoplastic conversion. Inhaled asbestos activates p53 expression at the sites of fiber deposition, 5 Mishra A Liu JY Brody AR et al. Inhaled asbestos fibers induce p53 expression in the rat lung. Am J Respir Cell Mol Biol. 1997; 16: 479-485 Crossref PubMed Scopus (40) Google Scholar and epidemiologic evidence indicates that exposure to asbestos increases the risk of lung cancer about fivefold. 6 Selikoff IJ Hammond EC Seidman H Mortality experience of insulation workers in the United States and Canada, 1943–1976. Ann N Y Acad Sci. 1979; 330: 473-490 Crossref Scopus (409) Google Scholar We postulate that the p53-mediated response to asbestos protects against the development of lung tumors. In accord with this postulate, a single exposure to an aerosol of asbestos for 5 h produced a significantly higher incidence of lung tumors in SPC-DNp53 transgenic mice than in simultaneously exposed nontransgenic littermates. These data indicate that compromised p53 function in the lung epithelium cooperates with asbestos in lung tumorigenesis.

Background: Healthcare costs for chronic obstructive pulmonary disease (COPD) have continued to increase with the increasing prevalence of the disease. New interventions that can reduce the medical costs of COPD are needed. Tiotropium bromide, a once-daily inhaled anticholinergic, has been evaluated in patients with COPD enrolled in two 1-year randomised, double-blind, placebo-controlled (usual care) trials which showed the drug reduced exacerbations and improved spirometry, dyspnoea, and health status.

PURPOSE:Akt is a signal transduction protein that plays a central role in inhibiting apoptosis in a variety of cell types including human cancer cells. In cell lines derived from human non-small cell lung cancers (NSCLCs), Akt has been shown to confer chemoresistance by inhibition of apoptosis in response to different chemotherapeutic agents including platinum-based agents, which are often the first-line therapy for NSCLCs. Only 20% to 30% of patients with NSCLC treated with chemotherapy have clinical evidence of response. The purpose of this study is to determine whether or not overexpression of activated Akt [i.e., phosphorylated Akt (pAkt)] is correlated with survival.EXPERIMENTAL DESIGN:We studied tumors from 61 patients with NSCLC in three tissue microarrays. All patients were followed for a period of 10 years or until death. The arrays were studied immunohistochemically with antibodies against pAkt, p53, and Ki-67.RESULTS:There was a statistically significant difference in survival between the 14 patients with strong pAkt staining and the 47 patients with weak to absent pAkt staining both by log-rank (P = 0.0416) and Breslow analysis (P = 0.0446). Difference in survival time with respect to pAkt status was also statistically significant even after accounting for stage at diagnosis (P = 0.004). Neither p53 nor Ki-67 was a statistically significant prognostic factor.CONCLUSIONS:Overexpression of pAkt is an independent prognostic factor. Additional studies of human NSCLCs are warranted to drive the development of targeted tumor-specific antineoplastic therapies.

OBJECTIVE To evaluate the safety and efficacy of bronchoscopic balloon dilation (BBD) without fluoroscopy for relief of tracheobronchial obstruction. METHODS We performed a retrospective study of all adult patients who underwent BBD without fluoroscopy at the Tulane University Hospital and Clinic between July 1, 1997, and June 30, 2002. RESULTS Twenty-four patients (mean [+/- SD] age, 58 +/- 14 years; 80% men) underwent 59 BBD procedures without fluoroscopy for the following conditions: iatrogenic tracheal stenosis (80%); saber-sheath trachea (4%); bronchial stenosis resulting from lung transplantation (4%); sarcoidosis (4%); Wegener granulomatosis (4%); and idiopathic stenosis (4%). All BBD procedures were performed via a rigid bronchoscope (61%) or a flexible bronchoscope (39%) without fluoroscopy. BBD was often combined with mechanical debridement (64%), stent placement (47%), or laser photoresection (19%), although in 26% of cases BBD was the only intervention. During the 59 procedures, 71 different balloon catheters were deployed a total of 112 times (deployment was defined as any use of balloon dilation in a different location, for a different purpose, or to a different inflation diameter). These 112 deployments were performed for primary dilation (49%), dilation prior to stent placement (28%), and stent seating (22%). Improvement in stenosis was achieved immediately postprocedure in all 59 procedures (100%). One balloon ruptured during inflation without clinically significant effect, and no other complications occurred. CONCLUSION BBD without fluoroscopy for the relief of nonmalignant tracheobronchial obstruction can be safely performed through a rigid or flexible bronchoscope. It can be used alone or as an adjunct to other therapeutic modalities. In this series, 100% of airway obstructions were improved, and there were no clinically significant complications. BBD of a tracheobronchial obstruction without fluoroscopy is safe, efficacious, and cost-effective.

As the fourth leading cause of death in the United States, chronic obstructive pulmonary disease (COPD) is receiving increased attention from medical researchers. The Global Initiative for Chronic Obstructive Lung Disease now defines COPD as a progressive disease state characterized by chronic respiratory tract inflammation as well as airflow limitation that is partially reversible with appropriate treatment. The inflammatory pathway associated with COPD, although not well studied in the past, is also receiving more attention as medical researchers attempt to elucidate the cellular and molecular pathogenetic mechanisms that result in the development of COPD. Understanding the pathogenetic mechanisms will lead to new therapeutic strategies. The purpose of this review is to identify the known major therapeutic targets and the agents available to treat this devastating disease and some of the new agents that are being developed.

An exposure system that allows large-scale exposure of animals to 1,6-hexamethylene diisocyanate (HDI)-based polyisocyanates at a stable concentration and aerosol size distribution was developed. The HDI polyisocyanate aerosol is generated by nebulizing a solution of a commercial polyisocyanate product dissolved in acetone. The aerosol is delivered with a constant airflow into a horizontal flow chamber. Complete mixing of aerosol in the chamber is ensured by a circulating fan. This method has been used to generate atmospheres containing HDI polyisocyanates at a concentration of 10.46+/-0.23 mg/m(3) over a 5-hour period. The overall mass median aerodynamic equivalent diameter was found to be 1.42 microm with a geometric standard deviation of 1.26. The HDI monomer concentration was 0.15+/-0.04 mg/m(3). The average chamber acetone concentration was determined to be 2481+/-222 ppm (mean+/-standard deviation). Different HDI polyisocyanate concentrations in the chamber can be achieved by altering the concentration of the commercial polyisocyanate product in acetone and the chamber flow rate. The described exposure system will be useful for performing toxicological studies involving HDI polyisocyanates.

The acute pulmonary response of male C57BL/6 mice exposed to respirable polymeric hexamethylene diisocyanate biuret trimer aerosol (HDI-BT), a component of polyurethane spray paints, was examined. Mice were exposed to concentrations of 1 and 10 mg/m3 HDI-BT for 5 h and were evaluated 6, 18, 42, 90, 186, and 378 h after the end of exposure. Mice exposed to 1 or 10 mg/m3 HDI-BT exhibited dose-dependent lung function impairment, edema, neutrophilic inflammation, cellular proliferation, and histologic lesions in terminal bronchioles and alveolar ducts. Impairment of pulmonary function, indicated by decreased frequency and increased enhanced pause (Penh), was maximal immediately after exposure and progressively recovered at later time points. Lung weight and lavage fluid protein content peaked at 6 and 18 h after exposure, respectively. Total cells and macrophages recovered in lavage fluid peaked 90 h after exposure. Neutrophils recovered in lavage fluid peaked between 18 and 42 h after exposure. Proliferative lesions, as identified histologically and by bromodeoxyuridine incorporation, were maximal 90 h after exposure. In contrast, no inflammatory cell influx, protein leakage, or lung pathology were observed in mice exposed to 360 ppb HDI monomer vapor. This model will be useful for investigating molecular mechanisms by which HDI-BT causes lung injury, which is known to occur in humans exposed occupationally to this pulmonary toxicant.

The chemotherapeutic drug bleomycin causes DNA damage and apoptosis in the lungs of mice within hours of endotracheal instillation followed by inflammation and fibrosis weeks later. The p53 tumor suppressor protein mediates cellular responses to DNA damage, including induction of apoptosis, but the effects of p53 activation in the various cell types of the lung during bleomycin-induced pulmonary fibrosis remain unclear. We show here that a transgene with a dominant-negative mutant form of human p53 expressed from the surfactant protein C promoter sensitizes mice to bleomycin-induced lung injury. The bleomycin-exposed transgenic animals display more severe lung pathology with associated collagen deposition and more pronounced lung eosinophilia than simultaneously exposed nontransgenic littermates. These observations suggest that compromising p53 function in the alveolar epithelium impairs recovery of the lung from bleomycin-induced injury.

Alveolar macrophages play a critical role in silica-induced lung fibrosis. Silica exposure induces tumor necrosis factor (TNF)-alpha release and nuclear factor (NF)-kappaB activation, and apoptotic mechanisms have been implicated in silica-induced pathogenesis. To characterize potential relationships between these signaling events, we studied their induction in two murine macrophage cell lines. The RAW 264.7 macrophage cell line was more sensitive, and the IC-21 macrophage cell line more tolerant to silica exposure (0.2 or 1 mg/ml for 6 h) as evidenced by significantly higher apoptotic responses in RAW 264.7 (P < 0.05). RAW 264.7 macrophages exhibited enhanced TNF-alpha production and NF-kappaB activation in response to silica, whereas IC-21 macrophages did not produce TNF-alpha in response to silica and did not induce NF-kappaB nuclear binding. Inhibition of NF-kappaB in RAW 264.7 cells with BAY11-7082 significantly increased apoptosis while inhibiting TNF-alpha release. In addition, TNF-alpha and NF-kappaB activation, but not apoptosis, were induced by lipopolysaccharide (LPS) in both cell lines, and NF-kappaB inhibition reduced LPS-induced TNF-alpha release. These data suggest that TNF-alpha induction is dependent on NF-kappaB activation in both cell lines. However, silica can induce apoptosis in murine macrophages, independently of TNF-alpha stimulation, as in IC-21 macrophages. Furthermore, NF-kappaB activation in macrophages may play dual roles, both pro- and antiapoptotic during silica injury.

The present study was undertaken to investigate the effects of treatment with the angiotensin-converting enzyme (ACE) inhibitor enalapril in a mouse model of pulmonary hypertension induced by bleomycin. Bleomycin-induced lung injury in mice is mediated by enhanced tumor necrosis factor-alpha (TNF) expression in the lung, which determines the murine strain sensitivity to bleomycin, and murine strains are sensitive (C57BL/6) or resistant (BALB/c). Bleomycin induced significant pulmonary hypertension in C57BL/6, but not in BALB/c, mice; average pulmonary arterial pressure (PAP) was 26.4 +/- 2.5 mmHg (P < 0.05) vs. 15.2 +/- 3 mmHg, respectively. Bleomycin treatment induced activation of nuclear factor (NF)-kappaB and activator protein (AP)-1 and enhanced collagen and TNF mRNA expression in the lung of C57BL/6 but not in BALB/c mice. Double TNF receptor-deficient mice (in a C57BL/6 background) that do not activate NF-kappaB or AP-1 in response to bleomycin did not develop bleomycin-induced pulmonary hypertension (PAP 14 +/- 3 mmHg). Treatment of C57BL/6 mice with enalapril significantly (P < 0.05) inhibited the development of pulmonary hypertension after bleomycin exposure. Enalapril treatment inhibited NF-kappaB and AP-1 activation, the enhanced TNF and collagen mRNA expression, and the deposition of collagen in bleomycin-exposed C57BL/6 mice. These results suggest that ACE inhibitor treatment decreases lung injury and the development of pulmonary hypertension in bleomycin-treated mice.