Lung effects of inhaled corticosteroids in a rhesus monkey model of childhood asthma

BACKGROUND

The risks for infants and young children receiving inhaled corticosteroid (ICS) therapy are largely unknown. Recent clinical studies indicate that ICS therapy in pre-school children with symptoms of asthma result in decreased symptoms without influencing the clinical disease course, but potentially affect postnatal growth and development. The current study employs a primate experimental model to identify the risks posed by ICS therapy.

OBJECTIVE

To (1) establish whether ICS therapy in developing primate lungs reverses pulmonary pathobiology associated with allergic airway disease (AAD) and (2) define the impact of ICS on postnatal lung growth and development in primates.

METHODS

Infant rhesus monkeys were exposed, from 1 through 6 months, to filtered air (FA) with house dust mite allergen and ozone using a protocol that produces AAD (AAD monkeys), or to FA alone (Control monkeys). From three through 6 months, the monkeys were treated daily with ICS (budesonide) or saline.

RESULTS

Several AAD manifestations (airflow restrictions, lavage eosinophilia, basement membrane zone thickening, epithelial mucin composition) were reduced with ICS treatment, without adverse effects on body growth or adrenal function; however, airway branching abnormalities and intraepithelial innervation were not reduced. In addition, several indicators of postnatal lung growth and differentiation: vital capacity, inspiratory capacity, compliance, non-parenchymal lung volume and alveolarization, were increased in both AAD and Control monkeys that received ICS treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Incomplete prevention of pathobiological changes in the airways and disruption of postnatal growth and differentiation of airways and lung parenchyma in response to ICS pose risks for developing primate lungs. These responses also represent two mechanisms that could compromise ICS therapy's ability to alter clinical disease course in young children.

Airway generation-specific differences in the spatial distribution of immune cells and cytokines in allergen-challenged rhesus monkeys

BACKGROUND

Accumulation of immune cell populations and their cytokine products within tracheobronchial airways contributes to the pathogenesis of allergic asthma. It has been postulated that peripheral regions of the lung play a more significant role than proximal airways with regard to inflammatory events and airflow obstruction.

OBJECTIVE

To determine whether immune cell populations and associated cytokines are uniformly distributed throughout the conducting airway tree in a non-human primate model of allergic asthma.

METHODS

We used a stereologic approach with a stratified sampling scheme to measure the volume density of immune cells within the epithelium and interstitium of trachea and 4-5 intrapulmonary airway generations from house dust mite (HDM) (Dermatophagoides farinae)-challenged adult monkeys. In conjunction with immune cell distribution profiles, mRNA levels for 21 cytokines/chemokines and three chemokine receptors were evaluated at four different airway generations from microdissected lungs.

RESULTS

In HDM-challenged monkeys, the volume of CD1a+ dendritic cells, CD4+ T helper lymphocytes, CD25+ cells, IgE+ cells, eosinophils, and proliferating cells were significantly increased within airways. All five immune cell types accumulated within airways in unique patterns of distribution, suggesting compartmentalized responses with regard to trafficking. Although cytokine mRNA levels were elevated throughout the conducting airway tree of HDM-challenged animals, the distal airways (terminal and respiratory bronchioles) exhibited the most pronounced up-regulation.

CONCLUSION

These findings demonstrate that key effector immune cell populations and cytokines associated with asthma differentially accumulate within distinct regions and compartments of tracheobronchial airways from allergen-challenged primates.

Smooth muscle hypertrophy in distal airways of sensitized infant rhesus monkeys exposed to house dust mite allergen

BACKGROUND

Airway smooth muscle hypertrophy is closely associated with the pathophysiology of hyper-reactive airways in allergic asthma.

OBJECTIVE

To determine whether repeated exposure to allergens during postnatal lung development promotes remodelling of airway smooth muscle.

METHODS

Infant, male rhesus monkeys (30-day-old) were sensitized to house dust mite allergen (HDMA) and then exposed to HDMA aerosol periodically over 5 months. Smooth muscle mass and bundle size and abundance in conducting airways were measured and compared with age-matched control (filtered air-exposed) monkeys.

RESULTS

Total smooth muscle mass and average bundle size were significantly greater in the conducting airways of monkeys exposed to HDMA. Smooth muscle bundle abundance was not affected by exposure to HDMA.

CONCLUSION

Repeated cycles of allergen exposure alter postnatal morphogenesis of smooth muscle, affecting both total mass and bundle size, in conducting airways of infant monkeys.

Total number and mean size of alveoli in mammalian lung estimated using fractionator sampling and unbiased estimates of the Euler characteristic of alveolar openings

Estimation of alveolar number in the lung has traditionally been done by assuming a geometric shape and counting alveolar profiles in single, independent sections. In this study, we used the unbiased disector principle to estimate the Euler characteristic (and thereby the number) of alveolar openings in rat lungs and rhesus monkey lung lobes and to obtain robust estimates of average alveolar volume. The estimator of total alveolar number was based on systematic, uniformly random sampling using the fractionator sampling design. The number of alveoli in the rat lung ranged from 17.3 x 10(6) to 24.6 x 10(6), with a mean of 20.1 x 10(6). The average number of alveoli in the two left lung lobes in the monkey ranged from 48.8 x 10(6) to 67.1 x 10(6) with a mean of 57.7 x 10(6). The coefficient of error due to stereological sampling was of the order of 0.06 in both rats and monkeys and the biological variation (coefficient of variance between individuals) was 0.15 in rat and 0.13 in monkey (left lobe, only). Between subdivisions (left/right in rat and cranial/caudal in monkey) there was an increase in variation, most markedly in the rat. With age (2-13 years) the alveolar volume increased 3-fold (as did parenchymal volume) in monkeys, but the alveolar number was unchanged. This study illustrates that use of the Euler characteristic and fractionator sampling is a robust and efficient, unbiased principle for the estimation of total alveolar number in the lung or in well-defined parts of it.

The remodelled tracheal basement membrane zone of infant rhesus monkeys after 6 months of recovery

BACKGROUND

In previous studies, we showed that repeated exposure to (1) house dust mite allergen (HDMA) (Dermatophagoides farinae) caused thickening of the basement membrane zone (BMZ) and (2) HDMA+ozone (O3) caused depletion of BMZ perlecan and atypical development of BMZ collagen (irregular thin areas<2.0 microm in width).

OBJECTIVE

The purpose of this study was to determine if these remodelling changes were reversible after 6 months of recovery.

METHODS

Rhesus monkeys were exposed to a regimen of HDMA and or O3 or filtered air (FA) for 6 months. After the exposure protocol was completed FA and O3 groups were allowed to recover in FA for 6 months. The HDMA and HDMA+O3 exposure groups recovered in a modified environment. They were re-exposed to HDMA aerosol for 2 h at monthly intervals during recovery in order to maintain sensitization for pulmonary function testing. To detect structural changes in the BMZ, collagen I and perlecan immunoreactivity were measured and compared to data from the previous papers.

RESULTS

The remodelled HDMA group had a significantly thicker BMZ and after 6 months of recovery the width had not regressed. In the remodelled BMZ of the HDMA+O3 group, perlecan had returned to the BMZ after 6 months of the recovery protocol, and the thin, irregular, collagen BMZ had been resolved.

CONCLUSION

In summary, this study has shown that: (1) The width of the remodelled HDMA BMZ did not regress during a recovery protocol that included a sensitizing dose of HDMA. (2) The atypical collagen BMZ in the HDMA+O3 BMZ was resolved in the absence of O3. (3) Depletion of perlecan from the BMZ by O3 was reversed by recovery in the absence of O3.

Immune and airway effects of house dust mite aeroallergen exposures during postnatal development of the infant rhesus monkey

BACKGROUND

The effect of chronic environmental aeroallergen exposure on the immune system and airways has not been experimentally defined in very young children.

OBJECTIVE

The purpose of this study was to determine the immunophenotype of peripheral blood and airway leucocytes in the newborn rhesus macaque monkey, following recurrent aerosol exposure to house dust mite (HDM) (Dermatophagoides farinae).

METHODS

A regimen of HDM aerosolization was initiated for 2 h per day, three times per week, starting when rhesus macaque monkeys were 1 week of age. All monkeys were inoculated with diptheria, tetanus, and acellular pertussis vaccine at 5 weeks of age to simulate human infant vaccination schedules.

RESULTS

Following 8 weeks of HDM aeroallergen exposure, infant monkeys exhibited a significant reduction in the total peripheral blood lymphocyte numbers and a decreased frequency of peripheral blood CD4+ T lymphocytes with a CD45RA-'memory' immunophenotype. Lavage CD4+ T lymphocytes from HDM-exposed monkeys showed elevated expression of CD25, as well as an increase in CD45RA-/CD62L-/CD11ahigh immunophenotype. Eosinophils were more abundant within airways of HDM-exposed monkeys, accumulating maximally within the trachea.

CONCLUSION

These data demonstrate the development of immunological responses following chronic inhalation of a common environmental allergen during postnatal maturation in the non-human primate.

Production of polyclonal antisera against feline immunoglobulin E and its use in an ELISA in cats with experimentally induced asthma

Serum samples from six cats with experimentally induced asthma were used to purify feline IgE using gel filtration and affinity chromatography. The resultant IgE, evaluated for purity by immunoelectrophoresis (IEP) and reactivity by Prausnitz-Kustner (PK) testing, was used to develop polyclonal rabbit anti-feline IgE antisera. Using reverse cutaneous anaphylaxis (RCA), the antisera were determined to be specific for feline IgE. The polyclonal rabbit anti-feline IgE antiserum was then validated in an allergen-specific ELISA. Serum samples from an additional five asthmatic cats sensitized with Bermuda grass allergen (BGA) were evaluated prior to sensitization, after parenteral sensitization, and after aerosol sensitization and challenge. A significant increase in serum BGA-specific IgE was noted over time.

Allergen-specific IgG and IgA in serum and bronchoalveolar lavage fluid in a model of experimental feline asthma

Allergic asthma, a Th2 cell driven response to inhaled allergens, has classically been thought of as predominantly mediated by IgE antibodies. To investigate the role of other immunoglobulin classes (e.g., IgG and IgA) in the immunopathogenesis of allergic asthma, levels of these allergen-specific immunoglobulins were measured in serum and mucosal fluids. Bermuda grass allergen (BGA)-specific IgG and IgA ELISAs in serum and bronchoalveolar lavage fluid (BALF) were developed and optimized in an experimental model of BGA-induced feline asthma. Levels of BGA-specific IgG and IgA significantly increased over time in serum and BALF after allergen sensitization. Additionally, these elevated levels of BGA-specific IgG and IgA were seen in conjunction with the development of an asthmatic phenotype indicated by positive intradermal skin tests, enhanced airways hyperreactivity, and increased eosinophil percentages in the BALF.

Abrogation of bleomycin-induced lung fibrosis by nitric oxide synthase inhibitor, aminoguanidine in mice

The effects of aminoguanidine (AG), a specific inhibitor of inducible nitric oxide synthase, on the bleomycin (BL)-induced lung fibrosis was evaluated in mice. The animals were placed into five groups: saline (SA)-instilled drinking water (SA+H(2)O), saline-instilled drinking water containing 0.5%AG (SA+0.5%AG), BL-instilled drinking water (BL+H(2)O), BL-instilled drinking water containing 0.2%AG (BL+0.2%AG), and BL-instilled drinking water containing 0.5%AG (BL+0.5%AG). The mice had free access to H(2)O or H(2)O containing AG and lab chow ad lib 2 days prior to intratracheal (IT) instillation of BL (0.07U/mouse/100 microL) or an equivalent volume of sterile isotonic saline. The mice in the SA+0.5%AG group consumed the greatest amount of AG without any ill effects than the mice in any other group. There were no differences in any of the measured biochemical determinants between the SA+H(2)O and SA+0.5%AG control groups. The IT instillation of BL in the BL+H(2)O group caused significant increases in the lipid peroxidation, hydroxyproline content, and prolyl hydroxylase activity of lungs and influx of inflammatory cells in the broncheoalveolar lavage fluid (BALF) as compared to both control groups. The intake of aminoguanidine by mice in the BL+0.5%AG group caused significant reductions in the BL-induced increases in all measured biochemical indices of lung fibrosis without any effects on the influx of inflammatory cells in the BALF. In fact, AG in both BL-treated groups additionally increased the total cell counts in the BALF from mice in the BL+0.2%AG and BL+0.5%AG groups as compared to the BL+H(2)O group. Histopathological evaluation of the lungs revealed that the mice in the BL+0.5%AG group had markedly fewer fibrotic lesions than mice in the BL+H(2)O group. These results demonstrate that aminoguanidine minimizes the BL-induced lung fibrosis at both the biochemical and the morphological level and support our earlier hypothesis that the production of nitric oxide plays a significant role in the pathogenesis lung fibrosis caused by BL.

Effect of C-fiber-mediated, ozone-induced rapid shallow breathing on airway epithelial injury in rats

We examined the relationship between C-fiber-mediated, ozone-induced rapid shallow breathing and airway epithelial cell injury at different airway sites within the lower respiratory tract of conscious Wistar rats (n = 24). We combined an acute 8-h ozone inhalation with vagal perineural capsaicin treatment, a selective C-fiber conduction block, and 5-bromo-2'-deoxyuridine (BrdU) labeling as an index of epithelial injury. Vehicle-treated rats that inhaled ozone developed a rapid shallow breathing pattern during ozone inhalation, whereas the capsaicin-treated rats that inhaled ozone showed no changes in respiratory frequency. In vehicle-treated, ozone-exposed rats that developed rapid shallow breathing, a progressive increase in BrdU-labeling density (no. of BrdU-labeled cells/mm(2) airway) was observed starting at the bifurcation of the left main stem bronchi (central airway) and going down either a short or long airway path. In vehicle-treated, ozone-exposed rats, terminal bronchioles supplied by short and long airway paths had a similar degree of BrdU-labeling density that was significantly (P < 0.05) greater than the BrdU-labeling density of the proximal airways that supply them. In contrast, the attenuation of rapid shallow breathing produced by capsaicin treatment resulted in a significantly reduced BrdU-labeling density in the terminal bronchioles supplied by short airway paths compared with the terminal bronchioles supplied by long airway paths. Our data indicate that ozone-induced rapid shallow breathing protects large conducting airways while producing a more even distribution of injury to terminal bronchioles.

Mild and moderate asthma is associated with airway goblet cell hyperplasia and abnormalities in mucin gene expression

Excessive airway mucus is an important cause of morbidity and mortality in asthma, but the relationship between accumulation of mucus and goblet cell size, number, and function is incompletely understood. To address these questions, stored mucin in the epithelium and goblet cell size and number were measured morphometrically, and mucin gene expression was measured by polymerase chain reaction and immunohistochemistry in endobronchial biopsies from 13 subjects with mild and moderate asthma and from 12 healthy control subjects. Secreted mucin was measured in induced sputum. We found that stored mucin in the airway epithelium was three times higher than normal in the subjects with asthma (p < 0.005). Goblet cell size was similar in both groups, but goblet cell number was significantly higher in the subjects with asthma (93,043 +/- 15,824 versus 41,959 +/- 9,230/mm3, p < 0.05). In mild asthma (FEV1 > or = 80% pred, n = 7), the level of stored mucin was as high as in moderate asthma (FEV1 < 80% pred, n = 6), but the level of secreted mucin was significantly lower (28.4 +/- 6.3 versus 73.5 +/- 47.5 microg/ml, p < 0.05). Secreted mucin was inversely correlated with stored mucin for the whole asthma group (rs = -0.78, p = 0.007). MUC5AC was the predominant mucin gene expressed in healthy subjects and subjects with asthma, and MUC5AC protein was increased in the subjects with asthma. We conclude that even mild asthma is associated with goblet cell hyperplasia and increased stored mucin in the airway epithelium, whereas moderate asthma is associated with increased stored mucin and secreted mucin. These findings suggest that acute degranulation of hyperplastic goblet cells may represent a mechanism for asthma exacerbations in mild and moderate asthma and that chronic degranulation of goblet cells may contribute to chronic airway narrowing in moderate asthma.

Mechanism of dexamethasone-mediated interleukin-8 gene suppression in cultured airway epithelial cells

The effects of dexamethasone, a glucocorticoid analog, on interleukin 8 (IL-8) gene expression were studied in cultures of primary human tracheobronchial epithelial cells and an immortalized human bronchial epithelial cell line, HBE1 cells. Dexamethasone inhibited IL-8 mRNA and protein expression in a concentration- and time-dependent manner. The inhibition did not occur at the transcriptional level since both nuclear run-on activity and IL-8 promoter-reporter gene expression assay revealed no significant effect. Instead, there was a change in IL-8 mRNA stability in dexamethasone-treated cultures. Under actinomycin D treatment, IL-8 mRNA was quite stable in dexamethasone-depleted cultures, while in dexamethasone-pretreated cultures, IL-8 message was rapidly degraded within the first hour, then leveled off. When dexamethasone and actinomycin D were added simultaneously to dexamethasone-depleted cultures, IL-8 mRNA remained rather stable. When cycloheximide was used to inhibit new protein synthesis, dexamethasone-dependent inhibition was not observed. These results suggest that a posttranscriptional mechanism, which requires dexamethasone-dependent new protein synthesis, is involved in the regulation of IL-8 mRNA by dexamethasone in airway epithelial cells.

Expression of the beta6 integrin subunit is associated with sites of neutrophil influx in lung epithelium

Inhalation of ozone by Rhesus monkeys results in epithelial injury and granulocyte influx in both conducting airways and respiratory bronchioles. We have reported that ozone-induced neutrophil recruitment and subsequent epithelial repair can be inhibited in vivo with a CD18 antibody. The antibody-mediated effect is abrogated by local instillation of C5a (a CD18-independent neutrophil chemoattractant), thereby demonstrating a role for neutrophils in lung epithelial repair processes. As an extension of this study, we examined the effect of ozone and neutrophil influx on epithelial expression of the beta6 integrin, an adhesion molecule associated with proliferation and repair. Expression of beta6 integrin was determined by immunohistochemistry for ozone-exposed monkeys treated with either control immunoglobulins or a CD18 antibody. The tracheal epithelium of ozone-exposed monkeys treated with control immunglobulins expressed the beta6 integrin. In contrast, the tracheal epithelium of ozone-exposed monkeys treated with CD18 antibody exhibited very low to undetectable expression of beta6 integrin. In association with C5a instillation and neutrophil influx, beta6 integrin was also observed in respiratory bronchiolar epithelium from both control and ozone-exposed animals. These findings cumulatively suggest that lung epithelial cell expression of beta6 integrin is associated with sites of neutrophil recruitment.

Effect of antibody against integrin alpha4 on bleomycin-induced pulmonary fibrosis in mice

Integrins are a family of transmembrane glycoproteins that can interact with components of the extracellular matrix. The alpha4beta1 and alpha4beta7 integrins are heterodimeric leukocyte cell surface molecules critical to their cell and matrix adhesive interactions. Evidence for a central role for the alpha4 integrins in leukocyte pathophysiology in the lung is well documented. In this study, we tested the hypothesis that neutralizing antibody for integrin alpha4 (PS2) may reduce bleomycin (BL)-induced lung fibrosis in vivo. Male C57BL/6 mice were injected intratracheally with saline (SA) or BL (0.08 U/mouse) followed by intraperitoneal injection of SA, isotype control antibody (1E6), or PS2 (100 microg) three times a week. Twenty-one days after the intratracheal instillation, mice were killed for bronchoalveolar lavage (BAL), biochemical, histopathological, and immunohistological analyses. Treatment with PS2 significantly reduced BL-induced increases in lung lipid peroxidation and hydroxyproline content. Lung histopathology also showed reduced fibrotic lesions in the BL-treated lungs by treatment with PS2. BL-treated mouse lungs also showed induction of cells with the myofibroblast phenotype, as indicated by the increased expression of alpha-smooth muscle actin (alphaSMA), whereas treatment with PS2 minimized the BL-induced alphaSMA expression. Furthermore, treatment with PS2 reduced the BL-induced increase in the BAL total cell number, and attenuated the BL-induced increase in the BAL protein level. It is concluded that integrin alpha4 may play an important role in BL-induced pulmonary fibrosis, and the use of anti-alpha4 antibody offers therapeutic antifibrotic potential in vivo.

Epithelial desquamation in asthma: artifact or pathology?

To determine whether the denudation of the bronchial epithelium observed in endobronchial biopsies from asthmatic subjects is a true pathologic feature or an artifact of tissue sampling, we analyzed epithelial integrity in bronchial biopsies from 14 subjects with mild and moderate asthma and 12 healthy subjects. In each subject, 4 to 8 bronchial biopsies were taken from large airways during bronchoscopy, fixed in 4% paraformaldehyde, embedded in glycomethacrylate, cut into 2-microM sections, and stained with toluidine blue. A x4 image of each biopsy was copied to a computer file using a video camera, and lines were drawn and measured along the basement membrane underlying areas completely denuded of overlying epithelium, areas covered by a single layer of basal cells, and areas of intact epithelium. We found that the percentage of basement membrane that was denuded of epithelium was similar in the healthy and asthmatic subjects (14.8 +/- 11.8 versus 11.4 +/- 9.8% respectively, p = 0.38); the percentage of basement membrane that was covered by a single layer of basal cells was also similar in the two groups (46.4 +/- 11.0 versus 54.5 +/- 9.8%, respectively, p = 0. 11). In the asthmatic subjects, we found no significant correlation between the percentage of basement membrane covered by denuded epithelium or by a single layer of basal cells and the FEV(1) percentage of predicted or the PC(20) methacholine. We conclude that denudation of bronchial epithelium in endobronchial biopsies from asthmatic subjects with stable mild and moderate disease is an artifact of tissue sampling and is not a true pathologic feature of the disease, and that the extent of airway epithelial denudation is not correlated with the severity of airway narrowing or the severity of bronchial hyperresponsiveness.

Effect of respiratory pattern on ozone injury to the airways of isolated rat lungs

Ozone stimulates the "defensive" C-fibers in the lungs, changing breathing pattern to rapid and shallow. We hypothesized that when ozone is administered to the isolated lung with a rapid shallow breathing pattern rather than a slow deep pattern, relatively less airway epithelial damage would occur. Four groups of isolated buffer perfused rat lungs were exposed to ozone (1 ppm) or to filtered air for 90 min with either a slow deep (SDB, tidal volume 2.4 ml, frequency 40 breaths/min) or a rapid shallow breathing pattern (RSB, tidal volume 1.2 ml, frequency 80 breaths/min), resulting in an equivalent inspired dose. The absorbed dose of ozone did not differ between the exposed groups. Ethidium homodimer-1 was then instilled into the trachea to identify injured airway epithelial cells. The lungs were fixed, the airways were microdissected, and the airway epithelial cells were counterstained with YPRO-1 prior to evaluation with confocal microscopy. Ozone-induced airway epithelial cell injury occurred to a lesser overall degree when lungs were exposed by the RSB pattern (p = 0.003). The relative reduction in injury was greater (p < 0.05) in the proximal axial airway than in its adjacent airway branch and terminal bronchioles. Ozone induced an increase in pulmonary resistance with the SDB pattern but not with the RSB pattern. Thus, at an equivalent dose of inspired ozone, a RSB pattern resulted in less total damage than a SDB pattern and the distribution of protection was heterogeneous with proximal axial airways displaying the greatest relative reductions in epithelial damage.

Differential regulation of the expression of cytokine-induced neutrophil chemoattractant by mouse macrophages

The production of cytokine-induced neutrophil chemoattractant (CINC) by functionally diverse mouse bone-marrow-derived macrophages was determined. Studies showed that beta1,3-glucan, IL-beta, TNFalpha and IFNgamma/TNFalpha induced expression and production of CINC in macrophages while neither IFNgamma nor TGFbeta alone induced detectable CINC expression. Pretreatment or simultaneous treatment of macrophages with TGFbeta resulted in suppression of CINC protein production. These studies demonstrate that IFNgamma and TNFalpha, found early during the inflammatory response, induce production of CINC, as well as induce macrophages into a cytocidal state that are capable of killing transformed cells, parasites and bacteria, and recruiting neutrophils. In contrast, TGFbeta, found during reparative stages of the inflammatory response, suppressed production of CINC, while inducing the development of inflammatory macrophages that are capable of producing lysosomal enzymes, enhanced endocytosis and ingestion of particulate matter and function to scavenge debris, debride tissue and stimulate repair.

Anti-inflammatory effect of pirfenidone in the bleomycin-hamster model of lung inflammation

We have previously reported the antifibrotic effects of pirfenidone (PD) in the bleomycin (BL)-hamster model of lung fibrosis. Since the development of fibrosis is generally preceded by acute lung inflammation, the present study was conducted to find out if dietary intake of PD (0.5%) has any effects on BL-induced lung inflammation. In this regard, we evaluated the effects of PD on BL-induced increased pulmonary vascular permeability, increased influx of inflammatory cells and increased levels of TGF-beta in the bronchoalveolar lavage fluid (BALF). Hamsters were intratracheally (IT) instilled with saline (SA) or BL (5.5 units/kg/5 ml). The animals were fed the control diet (CD) or the same diet containing 0.5% PD 2 days prior to IT instillation and throughout the study. The bronchoalveolar lavage was carried out at different times after IT instillation. Lavage fluid was used for total and differential cell counts and BALF-supernatant for measurement of total protein and TGF-beta. IT instillation of BL caused significant increases in total cells, neutrophils, macrophages and lymphocytes and in the levels of total protein and TGF-beta in BALF from hamsters in the BL + CD groups as compared to the corresponding SA + CD control groups. In contrast, treatment with pirfenidone in general, suppressed the BL-induced increases in the levels of proteins and TGF-beta and in the influx of neutrophils, macrophages and lymphocytes in BALF at the early time points in BL + PD groups. Based on the data reported in this study, we conclude that the anti-inflammatory effects of pirfenidone as evident by suppressions of BL-induced increased pulmonary vascular permeability and increased influx of inflammatory cells in the lung contribute additionally to its inherent anti-fibrotic effect.

Ozone-induced epithelial injury in the ferret is similar to nonhuman primates

Extrapolation to humans from rodent ozone exposure is limited by the anatomic differences between the species. Ferrets have similar pulmonary structures to humans, with well developed respiratory bronchioles and submucosal glands. We exposed adult ferrets, monkeys, and rats to 1 ppm ozone (O(3)) or filtered air for 8 h followed by 1 h in filtered air. Bronchoalveolar lavage (BAL) analysis, histopathology, and confocal microscopy were used to evaluate ozone-induced epithelial injury and inflammation. BAL showed significantly increased numbers of neutrophils in ozone-exposed as compared with filtered air ferrets, monkeys, and rats. However, there were 3- to 4-fold more neutrophils in monkeys and ferrets per milliliter of BAL than in rats. Ozone-exposed lungs showed a severe, acute infiltration of neutrophils in regions with necrotic epithelial cells, especially in the centriacinar region that was more severe in ferrets and monkeys than rats. We conclude that acute ozone exposure in ferrets induce severe epithelial necrosis and inflammation, results in similar epithelial injury compared with monkeys, and represents a better model of humans than rodents.

Regulation of cytokine-induced neutrophil chemoattractant in rat bone marrow-derived macrophages by inflammatory mediators

During the course of inflammation, macrophages are highly influenced by their local environment and changes in the cytokine milieu. Exposure of macrophages to various factors during different phases of the inflammatory response may have a strong influence on the pattern of gene expression, which a macrophage exhibits. We examined how these mediators affect the regulation of the expression and production of cytokine-induced neutrophil chemoattractant (CINC). Our study demonstrates that CINC can be induced in bone marrow-derived macrophages by lipopolysaccharide, interleukin-1 beta, tumor necrosis factor-alpha (TNFalpha), and interferon-gamma/TNF alpha. These mediators are factors which a macrophage would be expected to encounter early in an inflammatory process. In contrast, transforming growth factor-beta (TGFbeta), which is expressed late in the inflammatory process during mesenchymal cell proliferation and tissue repair, did not induce detectable amounts of CINC and functioned to suppress CINC production stimulated by early inflammatory mediators. Suppression of CINC production occurred whether TGF beta was added simultaneously, 12 or 24 h prior to the stimulus.

Trafficking of neutrophils across airway epithelium is dependent upon both thioredoxin- and pertussis toxin-sensitive signaling mechanisms

Leukocyte recruitment from the circulation into the airways is a multi-step process, involving both chemotactic and adhesive mechanisms. Using an in vitro model of leukocyte transepithelial trafficking, we show that movement of human peripheral blood neutrophils (PMN) across airway epithelium in the optimal basolateral-to-apical surface direction is partially blocked by pertussis toxin, an inhibitor of G(alphai)-protein-linked receptors. A neutralizing monoclonal antibody against interleukin-8 (IL-8; constitutively expressed by airway epithelium) did not inhibit PMN transepithelial migration, suggesting that alternative pertussis toxin-sensitive signaling mechanisms are involved in this process. However, a neutralizing antibody against thioredoxin, a redox enzyme with pertussis toxin-insensitive chemoattractant activity, did reduce PMN migration across airway epithelium. We conclude that trafficking of PMN across airway epithelium is mediated by both thioredoxin- and pertussis toxin-sensitive signaling mechanisms that are independent of IL-8.

A novel mechanism of retinoic acid-enhanced interleukin-8 gene expression in airway epithelium

A 3- to 8-fold stimulation of interleukin (IL)-8 gene expression by all-trans-retinoic acid (ATRA) was demonstrated in primary cultures of human and monkey tracheobronchial epithelial cells and BEAS-2B serum-sensitive cell line. The effect of ATRA on IL-8 gene expression is dose- and time-dependent. Using cycloheximide, it was observed that new protein synthesis was required for the stimulation. ATRA had no effect on IL-8 messenger RNA stability. A difference in nuclear run-on activity suggests that a transcriptional mechanism is involved in ATRA-enhanced IL-8 gene expression. Promoter-reporter gene transfection studies demonstrated ATRA enhanced IL-8 promoter activity, especially when cells were cotransfected with retinoic acid nuclear receptor-alpha expression vector. Deletion and site-directed mutagenesis analysis revealed the involvement of nuclear factor (NF)-kappaB binding site of the IL-8 gene in ATRA-enhanced promoter activity. Electrophoretic mobility shift assay (EMSA) demonstrated that ATRA enhanced DNA-NF-kappaB complex formation, especially with the p65 subunit. Western blot analysis demonstrated that ATRA did not enhance the protein amount of both the p50 and the p65 subunits in the nuclei. Because ATRA also enhances thioredoxin (TRX) gene expression, the effect of TRX on IL-8 gene expression was examined. IL-8 promoter activity was enhanced in transfected cells by the addition of TRX protein. Treatment of nuclear extracts with TRX also enhanced DNA- NF-kappaB complex formation as observed by EMSA, particularly the p65 subunit. Taking these data together, a novel mechanism is proposed in which ATRA activates promoter activity of IL-8 gene through TRX-dependent NF-kappaB activation.

Three-dimensional mapping of ozone-induced acute cytotoxicity in tracheobronchial airways of isolated perfused rat lung

Acute lung injury induced by reactive oxygen gases such as ozone (O(3)) is focal and site-selective. To define patterns of acute epithelial injury along intrapulmonary airways, we developed a new analytic approach incorporating labeling of permeable cells, airway microdissection, and laser scanning confocal microscopy, and applied it to isolated perfused rat lungs where ventilation and breathing pattern could be controlled. After exposure to O(3) (0, 0.25, 0.5, or 1.0 ppm), lungs were lavaged to assess lactate dehydrogenase (LDH) and protein, or infused with the permeability marker ethidium homodimer-1 (EthD-1) via tracheal cannula, gently lavaged, and fixed by airway infusion. The airway tree of the right middle lobe was exposed by microdissection of the axial pathway down to the terminal bronchioles; the dissection was incubated with a second nuclear dye, YOPRO-1, to label all nuclei; and whole mounts were examined by confocal microscopy. Abundance of EthD-1-positive (injured) cells was estimated as the number per epithelial volume using stereology on Z-series of projected images. For ozone concentrations of 1.0 ppm, lavage fluid LDH and total protein did not increase over controls. Exposure produced a concentration- dependent but nonhomogeneous increase in the abundance of EthD-1-labeled cells in proximal and distal conducting airways both in the main pathway, including terminal bronchioles, and in side branches. Overall, the highest EthD-1 labeling occurred in the side branches of the most proximal part of the airway tree at 1 ppm with the adjacent axial pathway airway having approximately one-third the labeling density. Density of EthD-1-labeled cells was lowest in terminal bronchioles at all O(3) doses. For the model we used, identification of injured epithelial cells by differential permeability and laser confocal microscopy appeared to be highly sensitive and permitted mapping of acute cytotoxicity throughout the airway tree and quantitative comparisons of sites with different branching histories and potential dosimetry rates.

Neutrophils enhance clearance of necrotic epithelial cells in ozone-induced lung injury in rhesus monkeys

To test the hypothesis that neutrophil influx is important for the removal of necrotic airway epithelial cells, rhesus monkeys were treated with a function-blocking monoclonal antibody (MAb) against CD18 followed by exposure to ozone or filtered air. CD18 MAb-treated, ozone-exposed monkeys showed a significant inhibition of neutrophil emigration and an accumulation of necrotic airway epithelial cells. In a subsequent experiment, monkeys were given CD18 MAb or an isotype control immunoglobulin before ozone or filtered-air exposure. Complement 5a was instilled into lobes of the right lung at the end of the exposure. Lavage neutrophils were significantly elevated in the right lobes compared with those in the contralateral left lobes; consequently, there were significantly fewer necrotic cells in the airways of the right lung, whereas large aggregations of necrotic cells were observed in the contralateral airways of the left lung. These data indicate that neutrophil influx in ozone-induced injury in primates is CD18 dependent and that neutrophils contribute to the repair of airway epithelium by removal of injured epithelial cells.

Reduction of bleomycin induced lung fibrosis by transforming growth factor beta soluble receptor in hamsters

BACKGROUND

Transforming growth factor beta (TGF-beta) is a key mediator of collagen synthesis in the development of lung fibrosis. It has previously been shown that the administration of TGF-beta antibody and TGF-beta binding proteoglycan, decorin, reduced bleomycin (BL) induced lung fibrosis in animals. The present study was carried out to investigate whether intratracheal instillation of TGF-beta soluble receptor (TR) would minimise the BL induced lung fibrosis in hamsters.

METHODS

The effect of a recombinant TR (TGFbetaRII) on the lung collagen accumulation was evaluated in a BL hamster model of pulmonary fibrosis. Animals were divided into four groups and intratracheally injected with saline or BL at 6.5 U/4 ml/kg followed by intratracheal instillation of phosphate buffered saline (PBS) or 4 nmol TR in 0.3 ml twice a week. Twenty days after the first intratracheal instillation the hamsters were killed for bronchoalveolar lavage (BAL) fluid, biochemical, and histopathological analyses.

RESULTS

Treatment of hamsters with TR after intratracheal instillation of BL significantly reduced BL induced lung fibrosis as shown by decreases in the lung hydroxyproline level and prolyl hydroxylase activity, although they were still significantly higher than those of the saline control. Histopathological examination showed a considerable decrease in BL induced fibrotic lesions by TR treatment. However, TR did not prevent the BL induced increases in total cells and protein in the BAL fluid.

CONCLUSIONS

These results suggest that TR has antifibrotic potential in vivo and may be useful in the treatment of fibrotic diseases where increased TGF-beta is associated with excess collagen accumulation.

Substance P primes the formation of hydrogen peroxide and nitric oxide in human neutrophils

Substance P (SP), a neurotransmitter of the central and peripheral nervous system, has been implicated as a mediator of the pulmonary inflammatory response through its stimulatory effects on neutrophils. We investigated the role of SP in priming the production of reactive oxygen species by human neutrophils with the cytochrome c reduction assay and by flow cytometry using the intracellular oxidizable probe dichlorofluorescein. We also investigated SP-induced formation of nitrite and nitrate as an index of nitric oxide (NO) production. Our results indicate that SP primes two distinct pathways with respect to the induction of reactive oxygen species in the human neutrophil: the production of superoxide anion and hydrogen peroxide by the calmodulin-dependent NADPH oxidase, and the generation of NO by a constitutive NO synthase. Preincubation of neutrophils with inhibitors of calmodulin and NO synthase diminished the oxidative response in an additive fashion. These results give insight into distinct signal transduction pathways in the SP-primed neutrophil with respect to the formation of superoxide anion, hydrogen peroxide, and NO.

Cutting edge: protective response to pulmonary injury requires gamma delta T lymphocytes

Gamma delta intraepithelial lymphocytes are thought to coordinate responses to pathogens that penetrate the epithelial barrier. To directly test this, mice were inoculated with Nocardia asteroides. At doses that were nonlethal for control mice, gamma delta-deficient mice became severely ill and died within 14 days. Histologic examination of these lungs demonstrated the presence of severe tissue damage and unimpeded bacterial growth in the gamma delta-deficient mice compared with neutrophilic lesions and clearance of the organism in control mice. Interestingly, ozone exposure that targets a comparable lung region also resulted in diffuse epithelial necrosis associated with a similar lack of neutrophil recruitment in gamma delta-deficient mice. These data demonstrate that gamma delta intraepithelial lymphocytes can protect the host from pathogenic and nonpathogenic insults by targeting the inflammatory response to epithelial necrosis.

Breathing pattern response and epithelial labeling in ozone-induced airway injury in neutrophil-depleted rats

To test the hypothesis that neutrophils enhance the repair of ozone (O3)-injured airway epithelium, we investigated breathing pattern responses and airway epithelial injury and repair in rats depleted of neutrophils using rabbit antirat neutrophil serum (ANS) and control rats treated with normal rabbit serum (NRS). Thirty-seven Wistar rats were exposed to O3 (1 ppm) or filtered air (FA) for 8 h followed by 8 h in FA. O3-exposed NRS- and ANS-treated rats showed similar progressive decreases in tidal volume and increase in breathing frequency, with maximal changes occurring at 8 h of exposure, whereas FA-exposed rats showed no significant changes. O3-exposed ANS-treated rats showed more epithelial necrosis in the nasal cavity, bronchi, and distal airways than did O3-exposed NRS-treated rats. Incorporation of 5-bromo-2-deoxyuridine (BrdU), a measure of cellular proliferation, was assessed using an optical disector to count BrdU- labeled terminal bronchiolar epithelial cells. O3-exposed ANS-treated rats had significantly less BrdU- labeled epithelial cells than did O3-exposed NRS-treated rats. We conclude that neutrophils contribute to the repair process by enhancing the proliferation of O3-injured airway epithelial cells.

Capsaicin-sensitive C-fiber-mediated protective responses in ozone inhalation in rats

To assess the role of lung sensory C fibers during and after inhalation of 1 part/million ozone for 8 h, we compared breathing pattern responses and epithelial injury-inflammation-repair in rats depleted of C fibers by systemic administration of capsaicin as neonates and in vehicle-treated control animals. Capsaicin-treated rats did not develop ozone-induced rapid, shallow breathing. Capsaicin-treated rats showed more severe necrosis in the nasal cavity and greater inflammation throughout the respiratory tract than did control rats exposed to ozone. Incorporation of 5-bromo-2'-deoxyuridine (a marker of DNA synthesis associated with proliferation) into terminal bronchiolar epithelial cells was not significantly affected by capsaicin treatment in rats exposed to ozone. However, when normalized to the degree of epithelial necrosis present in each rat studied, there was less 5-bromo-2'-deoxyuridine labeling in the terminal bronchioles of capsaicin-treated rats. These observations suggest that the ozone-induced release of neuropeptides does not measurably contribute to airway inflammation but may play a role in modulating basal and reparative airway epithelial cell proliferation.

IL-8 is one of the major chemokines produced by monkey airway epithelium after ozone-induced injury

A rhesus monkey interleukin (IL)-8 cDNA clone with >94% homology to the human IL-8 gene was isolated by differential hybridization from a cDNA library of distal airways after ozone inhalation. In situ hybridization and immunohistochemistry showed increased IL-8 mRNA and protein levels in epithelial cells at 1 h but not at 24 h after inhalation of ozone. The appearance of IL-8 in airway epithelial cells correlated well with neutrophil influx into airway epithelia and lumens. Air-liquid interface cultures of tracheobronchial epithelial cells were exposed to ozone in vitro. We observed a transient increase in IL-8 secretion in culture medium immediately after ozone exposure and a dose-dependent increase in IL-8 secretion and mRNA production. In vitro neutrophil chemotaxis showed a parallel dose and time profile to epithelial cell secretion of IL-8. Treatment with anti-IL-8 neutralizing antibody blocked >80% of the neutrophil chemotaxis in vitro. These results suggest that IL-8 is a key chemokine in acute ozone-induced airway inflammation in primates.

Lung fibrosis is ameliorated by pirfenidone fed in diet after the second dose in a three-dose bleomycin-hamster model

Interstitial lung fibrosis (ILF) is a life-threatening disease which has no known drug for prevention and cure. In the present study, we evaluated the antifibrotic potential of pirfenidone (PD) (5-methyl-1-phenyl-2-(1H)-pyridone) in a three-dose bleomycin (BL)-hamster model of lung fibrosis. Hamsters were intratracheally (IT) instilled with three consecutive doses of bleomycin sulfate (2.5 U/kg/5mL, 2.0 U/kg/5mL, 1.5 U/kg/3.75 mL) or an equivalent volume of saline at weekly intervals. Hamsters were fed a diet after the second dose of BL containing 0.5% PD and hamsters in the control groups were fed the same diet without the drug. The four groups were saline-instilled fed control diet (SCD); saline-instilled fed the same diet containing PD (SPD); BL-instilled fed control diet (BCD); and BL-instilled fed the diet containing PD (BPD). Hamsters were sacrificed at 28 days after IT instillation of last dose of saline or BL and their lungs processed for various assays. Lung hydroxyproline, an index of fibrosis, in SCD, SPD, BCD and BPD were 830, 804, 1609, 1235 micrograms/lung, respectively. Lung prolyl hydroxylase activities in the SPD, BCD and BPD groups were 103%, 313%, 157% of the control SCD group (5.99 x 10(4) dpm/lung/30 min) respectively. Malondialdehyde equivalent levels and superoxide dismutase activity in the corresponding groups were 99, 79, 240 and 145 nmoles/lung and 412, 433, 538 and 410 units/lung respectively. Lung myeloperoxidase activities in the corresponding groups were 56%, 179%, and 116% of the control group (0.44 units/lung). It is concluded that PD is a novel antifibrotic drug that has therapeutic potential in arresting the progression of an ongoing fibrotic process in the lung.

Antifibrotic effect of decorin in a bleomycin hamster model of lung fibrosis

We reported previously that treatment with antibody to transforming growth factor-beta (TGF-beta) caused a marked attenuation of bleomycin (BL)-induced lung fibrosis (LF) in mice. Decorin (DC), a proteoglycan, binds TGF-beta and thereby down-regulates all of its biological activities. In the present study, we evaluated the antifibrotic potential of DC in a three-dose BL-hamster model of lung fibrosis. Hamsters were placed in the following groups: (1) saline (SA) + phosphate-buffered saline (PBS) (SA + PBS); (2) SA + DC; (3) BL + PBS; and (4) BL + DC. Under pentobarbital anesthesia, SA (4 mL/kg) or BL was instilled intratracheally in three consecutive doses (2.5, 2.0, 1.5 units/kg/4 mL) at weekly intervals. DC (1 mg/mL) or PBS was instilled intratracheally in 0.4 mL/hamster on days 3 and 5 following instillation of each dose of SA or BL. In week 4, hamsters received three doses of either DC or PBS every other day. The hamsters were killed at 30 days following the first instillation, and their lungs were appropriately processed. Lung hydroxyproline levels in SA + PBS, SA + DC, BL + PBS, and BL + DC groups were 965, 829, 1854, and 1387 microg/lung, respectively. Prolyl hydroxylase activities were 103, 289, and 193% of SA + PBS control in SA + DC, BL + PBS, and BL + DC groups, respectively. The myeloperoxidase activities in the corresponding groups were 222, 890, and 274% of control (0.525 units/lung). Intratracheal instillation of BL caused significant increases in these biochemical markers, and instillation of DC diminished these increases in the BL + DC group. DC treatment also caused a significant reduction in the infiltration of neutrophils in the bronchoalveolar lavage fluid (BALF) of hamsters in the BL + DC group. However, DC treatment had little effect on BL-induced increases in lung superoxide dismutase activity and lipid peroxidation and leakage of plasma proteins in the BALF of the BL + DC group. Hamsters in the BL + PBS group showed severe multifocal fibrosis and accumulation of mononuclear inflammatory cells and granulocytes. In contrast, hamsters in the BL + DC group showed mild multifocal septal thickening with aggregations of mononuclear inflammatory cells. Hamsters in both control groups (SA + PBS and SA + DC) showed normal lung structure. Frozen lung sections following immunohistochemical staining revealed an intense staining for EDA-fibronectin and collagen type I in the BL + PBS group as compared with all other groups. It was concluded that DC potentially offers a novel pharmacological intervention that may be useful in treating pulmonary fibrosis.

Metronidazole resistance reduces efficacy of triple therapy and leads to secondary clarithromycin resistance

There has been a significant increase in the prevalence of H. pylori resistance to metronidazole in recent years, while clarithromycin resistance is still relatively rare. In this study we assessed: (1) the effect of primary H. pylori resistance to metronidazole and clarithromycin on the clinical efficacy of a one-week regimen consisting of omeprazole, metronidazole, and clarithromycin; and (2) the rate of acquisition of secondary antimicrobial resistance after treatment failure. Eighty-seven patients with duodenal ulceration or nonulcer dyspepsia were included in the study. The primary metronidazole and clarithromycin resistance rates were 35.6% and 3.4%, respectively (all three pretreatment clarithromycin resistant strains had concurrent metronidazole resistance). H. pylori was eradicated in 81.6% of patients. The eradication rate for fully sensitive isolates was 98.2% (55/56) but was significantly reduced to 57.1% (16/28) for isolates that were resistant to metronidazole alone and 0% (0/3) in cases of dual resistance (P < 0.001). Secondary resistance to clarithromycin was acquired in 58.3% of cases of treatment failure. In areas of high prevalence of primary metronidazole resistance, this is a significant cause of treatment failure with this triple therapy regimen. This leads to the selection of strains with dual resistance that are difficult to eradicate and may contribute to an increase in the prevalence of clarithromycin resistance. In such areas an alternative first-line treatment should be prescribed.

Pulmonary vagal reflexes and breathing pattern are not altered in elastase-induced emphysema in rats

The role of nonmyelinated and myelinated vagal afferents in pulmonary reflexes and breathing pattern was examined in elastase-treated emphysemic rats. Fourteen to 17 days after intratracheal instillation of 1 IU/gm of porcine pancreatic elastase or 0.5 mL of saline, elastase-treated rats had a decreased alveolar surface area to volume of parenchyma (Sv) (42.44 +/- 1.7 vs. 31.51 +/- 1.1 mm2/mm3), increased quasistatic compliance (QSC) (1.05 +/- 0.06 vs. 1.25 +/- 0.09 mL/cm H2O), functional residual capacity (FRC) (4.31 +/- 0.10 vs. 5.88 +/- 0.37 mL), residual volume (RV) (3.02 +/- 0.14 vs. 4.27 +/- 0.31 mL), and total lung capacity (TLC) (14.04 +/- 0.28 vs. 15.58 +/- 0.54 mL). There were no changes in the strength of the pulmonary chemoreflex, the strength of the Hering-Breuer inflation reflex, or breathing pattern before or after vagal perineural capsaicin treatment (VPCT) or vagotomy. There were, however, significant negative correlations between Sv and TLC, FRC and RV, and a near significant (p < .09) negative correlation between Sv and QSC, but no significant correlations between Sv and indices of either the pulmonary chemoreflex or Hering-Breuer inflation reflex. The results indicate that pulmonary vagal nonmyelinated and myelinated reflex activity and breathing pattern are not affected by elastase-induced emphysema in rats.

gamma-Linolenic acid-containing diet attenuates bleomycin-induced lung fibrosis in hamsters

Although bleomycin (BLM), an antineoplastic drug, is used in the treatment of a variety of tumors, the mechanism(s) that contribute to its induced lung injury and fibrosis are not fully elucidated. Since alterations in the levels of certain fatty acid metabolites have been associated with BLM-induced lung injury, we tested the effects of dietary gamma-linolenic acid (GLA)-containing evening primrose oil on BLM-induced morphological alterations in the hamster lung, the marked elevation of tissue hydroxyproline (a marker for collagen synthesis), and elevated generation of arachidonic acid metabolites (marker of inflammatory mediators). Our data revealed that after 14 d of dietary GLA-containing oil (i) BLM-induced elevation of lung hydroxyproline was suppressed (P < 0.05), (ii) the marked BLM-induced elevation of lung leukotriene B4 (LTB4) (a marker of polymorphanuclear generation of proinflammatory LTB4) was significantly suppressed (P < 0.05). The decrease in LTB4 was accompanied by marked elevations (P < 0.05) of lung prostaglandin E1 (PGE1) and 15-hydroxyeicosatrienoic acid (15-HETrE), both with known antiinflammatory properties. Taken together, data from these studies suggest that dietary GLA-containing oil contributes to tissue elevation of PGE1 and 15-HETrE, which in vivo may attenuate lung inflammation and fibrosis.

Contribution of vagal afferents to breathing pattern in rats with lung fibrosis

In anesthestized male Wistar rats with bleomycin-induced lung fibrosis we examined the influence of lung vagal non-myelinated and myelinated afferents in setting breathing pattern. Fourteen days after intratracheal instillation of bleomycin, lung compliance, total lung capacity (TLC) and inspiratory capacity were reduced while functional residual capacity and residual volume were increased. Baseline tidal volume (VT) was decreased and frequency (fR) increased in the bleomycin treated rats compared with controls. Selective vagal C-fiber blockade did not affect fR or VT in any group. Vagotomy resulted in an increase in VT and decrease in fR in both groups with the percent increase in VT/TLC and decrease in fR being significantly greater in the bleomycin rats compared with controls. Vagotomy also attenuated the significantly elevated PCO2 in the bleomycin treated rats suggesting that bleomycin-induced alterations in breathing pattern contribute to blood gas abnormalities. We conclude that vagal myelinated afferents contribute to the rapid shallow breathing in bleomycin treated rats.

Age-dependent neutrophil and blood flow responsiveness in acute pulmonary inflammation in rabbits

Diminished ability of neonatal neutrophils to orient and move in a chemotactic gradient has been linked to compromised pulmonary host defense. We investigated whether deficiency of neonatal neutrophil function in vitro was evident in acute pulmonary inflammation. Analysis of neutrophils in vitro showed impaired chemotaxis in 4-wk-old compared with adult rabbits. In vivo-directed migration of labeled neutrophils into the alveolar space of adult rabbits in response to C5f instillation was significantly less for neutrophils donated from 4-wk-old rabbits compared with those from adults. In contrast, there were no differences in the alveolar accumulation of 4-wk-old and adult labeled neutrophils in 4-wk-old rabbits in response to C5f instillation, although the response showed a shorter time course than seen in adult rabbits. Adult rabbits diverted 46% of the blood away from the right cranial lung lobe, whereas 4-wk-old rabbits showed no change in blood flow after C5f instillation. Megakaryocytes (a source of blood flow mediators) were 3.2-fold greater in adult compared with 4-wk-old lung. These data suggest that the lack of blood flow diversion from inflamed neonatal lung increases neutrophil migration into alveoli, allowing for preservation of an inflammatory response despite neutrophil deficiencies in chemotaxis.

Effect of treatment with erythromycin on bronchoalveolar lavage fluid cell populations in foals

OBJECTIVE

To determine whether oral administration of erythromycin alters the inflammatory response to bronchoalveolar lavage (BAL) in young horses.

ANIMALS

12 healthy, unweaned, mixed-breed foals of either sex, between 2 and 4 months old.

PROCEDURE

BAL was performed; 250 ml of phosphate-buffered saline solution (300 mOsm, pH 7.4) was administered in 50-ml aliquots. Foals were carefully monitored for 4 days, then erythromycin base (25 mg/kg of body weight, PO, q 12 h) was given to foals of the treated group. After 4 days, foals were reanesthetized, and the same lung was relavaged. Cytologic examination was performed on BAL fluid (BALF) samples from both groups of foals. At 12 hours after administration of the final dose, erythromycin A and anhydroerythromycin A concentrations were determined in plasma of treated foals.

RESULTS

In the second BALF sample from the same lung of control foals, percentage of neutrophils was significantly increased (53 +/- 38.0%) [corrected], compared with that from erythromycin-treated foals (4.88 +/- 3.66%, P < 0.05), and was associated with apparent decrease in the ability of BALF cells from erythromycin-treated foals to migrate toward a chemoattractant source. Significantly fewer BALF cells adhered to a cell culture substratum after erythromycin treatment of foals. Erythromycin A was not detected in plasma of any treated foal at the time of the second BAL; anhydroerythromycin A, a degradation product of erythromycin, was detected in plasma of 5 of 6 foals (mean concentration, 0.2 +/- 0.06 micrograms/ml).

CONCLUSION AND CLINICAL RELEVANCE

Bal induces neutrophilic inflammation, which persists for at least 4 days in the lungs of young horses. Erythromycin [corrected] (25 mg/kg, PO q 12 h) diminishes this inflammatory response through a mechanism that may involve alteration of BALF cell function. Degradation of erythromycin to biologically active products or presence of parent drug in pulmonary secretions may be responsible for alterations in pulmonary lavage cell chemotaxis and adherence. Erythromycin administered orally to foals at clinically relevant doses appears to have nonantimicrobial effects that may interfere with host cell metabolism and decrease inflammatory responses in airways.

Dose-related effects of Ampligen (poly(I).poly(C12U)), a mismatched double-stranded RNA, in a bleomycin-mouse model of pulmonary fibrosis

The antifibrotic effect of the mismatched double-stranded RNA, Ampligen (poly(I).poly(C12U)), was evaluated in a bleomycin-mouse model of pulmonary fibrosis. Mice received a single intratracheal dose of bleomycin (0.125 U/mouse) or saline (50 microL) at the beginning of the experiment, followed by 5 or 6 intraperitoneal injections of Ampligen (1.0, 5.0, 10.0, 15.0, or 25.0 mg/kg) or saline at regular intervals for 2 weeks. Ampligen did not produce increased mortality or weight loss by itself. However, it produced varying degrees of mortality in combination with bleomycin. Five injections of 10 mg/kg Ampligen or three injections of 25 mg/kg Ampligen plus three injections of 10 mg/kg Ampligen in combination with bleomycin .produced significant reductions in lung collagen accumulation as indicated by lung hydroxyproline content compared to the bleomycin control group. Animals receiving bleomycin plus Ampligen at all dosages had significantly reduced prolyl hydroxylase activity compared to the bleomycin control group. Lipid peroxidation and bronchoalveolar lavage fluid (BALF)-supernatant protein content for the groups receiving bleomycin plus Ampligen were not reduced compared to the bleomycin control group. In the BALF-supernatant, the activity of acid phosphatase, a lysosomal enzyme produced by neutrophils, monocytes, and macrophages, was significantly decreased in the group receiving bleomycin plus 10 mg/kg Ampligen. Also, selected BALF differential immune cell counts were reduced in some of the groups receiving bleomycin plus Ampligen, but not in a consistent or dose-dependent manner. The results of this study indicate that Ampligen can significantly reduce the bleomycin-induced increased collagen accumulation and may be therapeutically useful in the management of lung fibrosis in humans.

Recombinant tumour necrosis factor-alpha and platelet-activating factor synergistically increase intercellular adhesion molecule-1 and E-selectin-dependent neutrophil adherence to endothelium in vitro

Neutrophil adhesion to microvascular endothelium at sites of acute inflammation is regulated by both chemotactic peptides and lipid-derived mediators. Tumour necrosis factor-alpha (TNF-alpha) is a pro-inflammatory peptide that up-regulates endothelial expression of intercellular adhesion molecule-1 (ICAM-1) and endothelial leucocyte adhesion molecule-1 (E-selectin), while platelet-activating factor (PAF) is a potent lipid mediator that induces vascular changes via an unknown mechanism. Both have been shown to increase leucocyte-endothelial adhesion in various in vitro models of acute inflammation; however, the combined effects of recombinant TNF-alpha (rTNF-alpha) and PAF on neutrophil-endothelium adhesion have not been well described. In this study, we found rTNF-alpha at 0.5 ng/ml and PAF at 10 microM acted synergistically to increase neutrophil adherence to cultured umbilical vein endothelial cells 4 hr after stimulation. This increased neutrophil-endothelial adhesion was, in part, dependent on up-regulated expression of ICAM-1 and E-selectin since application of anti-ICAM1 and anti-E-selectin F(ab')2 fragments markedly diminished adhesion. Cultures stimulated with rTNF-alpha (0.5 ng/ml) or PAF (10 microM) alone did not show a significant increase in neutrophil adhesion, and neither ICAM-1 nor E-selectin expression was up-regulated as determined by flow cytometric analysis of endothelial cells. These results indicate that rTNF-alpha and PAF act synergistically to increase neutrophil-endothelial adhesion by stimulating endothelial expression of ICAM-1 and E-selectin and, thus, may play important roles in the onset and severity of acute inflammatory reactions.

Neonatal capsaicin treatment increases the severity of ozone-induced lung injury

To test the hypothesis that lung sensory C fibers protect the small distal airways and alveoli from oxidant injury, we compared the effects of inhalation of ozone (1 ppm) or filtered air for 8 h on lung injury and lung inflammation in four groups of rats: (1) normal rats exposed to filtered air; (2) normal rats exposed to ozone; (3) rats treated as neonates with capsaicin (50 mg/kg, intraperitoneally) and subsequently exposed to filtered air; and (4) rats treated as neonates with capsaicin and subsequently exposed to ozone. All rats were allowed to recover in filtered air for 0, 4, 16, and 40 h before necropsy. Rats exposed to filtered air (Groups 1 and 3) showed normal airway and parenchyma structure. Normal untreated rats exposed to ozone showed a random distribution of mild, interstitial inflammatory changes and epithelial necrosis of bronchi and bronchiolar epithelium. However, rats treated with capsaicin and subsequently exposed to ozone demonstrated severe acute interstitial inflammation and epithelial coagulate necrosis in all airways, especially in small, peripheral airways and parenchyma; all of these changes were statistically significant. These findings support our hypothesis that lung sensory C fibers protect the distal airways from oxidant injury during acute ozone inhalation.

Cytokine-induced neutrophil chemoattractant production by primary rat alveolar type II cells

This study was designed to determine the production of the chemokine cytokine-induced neutrophil chemoattractant (CINC) by primary rat alveolar type II (ATII) cells upon stimulation with exogenous and endogenous proinflammatory factors. Cultures of primary rat ATII cells were exposed to lipopolysaccharide (LPS), interleukin-1 beta (IL-1 beta) or tumor necrosis factor-alpha (TNF alpha) over a 16 hour period and the production of CINC both apically and basolaterally was measured by ELISA. Compared to unstimulated (UNS) cultures, LPS, IL-1 beta and TNF alpha were found to significantly increase the level of CINC detected in culture by two, four and sixteen hours post stimulation, respectively. ATII cells also demonstrated a polar secretion of CINC. The accumulation of CINC basolaterally was significantly more than apically; 133%, 45%, 117% and 123% for UNS, IL-1 beta, LPS and TNF alpha respectively. We demonstrated that primary rat ATII cells may participate in the chemokine network during inflammation by the production of CINC upon stimulation with endogenous and exogenous factors.

Neutrophils enhance removal of ozone-injured alveolar epithelial cells in vitro

After acute exposure to oxidant gases in vivo, migration and accumulation of inflammatory cells in pulmonary epithelium coincides with epithelial cell necrosis. The present study was designed to test quantitatively the hypothesis that quiescent neutrophils enhance the removal of oxidant-injured pulmonary epithelial cells after exposure to ozone in vitro. Primary isolated rat alveolar type II cells were cultured as monolayers, using serum-free medium. After exposure to 0.1-0.5 ppm ozone for 0.5 h, apical sides of monolayers were administered either fresh nutrient medium only or medium containing quiescent human neutrophils. Monolayer bioelectric properties and cellular uptake of vital dye were recorded from 5 to 48 h after ozone exposure. Ozone dose-dependent increases in monolayer permeability were associated with proportionally higher numbers of injured epithelial cells. However, the direction and magnitude of neutrophil effects on monolayer permeability after ozone exposure were dependent on ozone concentration. Furthermore, neutrophil-treated monolayers exposed to 0.1 ppm ozone had significantly fewer attached cells positive for uptake of vital dye relative to monolayers exposed to the low level of ozone only; this effect was ablated with increasing ozone concentration. These data suggest that at high levels of ozone neutrophils may exacerbate injury to oxidant-impaired epithelial cells, whereas the presence of neutrophils after exposure to ambient concentrations of ozone may expedite the restoration of epithelial barrier function. We conclude that, by enhancing the removal of injured cells, neutrophils may facilitate the repair of centriacinar epithelium after ozone exposure in vivo.

Quantitation of fibroblast population growth rate in situ using computerized image analysis

The development of computer-assisted image analysis has provided the technology to rapidly determine the population size of cultured cell monolayers in situ. We have adapted this technology to determine the population growth rate of cultured fibroblasts for use in a high-replicate format. Human lung fibroblasts were seeded into 1/2 A 96-well plates that had one-half the culture area of standard 96-well plates. The cells were cultured in medium supplemented with different concentrations of FBS and on days 0, 1, 2, 3, 5, and 7, and their nuclei were stained with propidium iodide. A microscopic field representing one-quarter of a well of fluorescent nuclear images was captured onto a Macintosh computer, and the number of nuclei were counted using an image analysis software program. There were no significant differences between the number of nuclei counted manually and the number counted using computer-assisted software, until day 7 where the cells were multilayered (P < 0.05). This image analysis method was compared to other assays typically used to estimate cell proliferation or population size, namely hemocytometer counting, a rapid colorimetric staining assay using naphthol blue-black, and [3H]-thymidine incorporation. The growth rates derived using image analysis were in close agreement with results derived from hemocytometer counts and [3H]-thymidine incorporation. However, the growth rates of cells grown in high concentrations of FBS as determined using naphthol blue-black were substantially lower than results from image analysis. We conclude that this adaptation of computer-assisted image analysis provides a method to derive accurate growth curves by directly counting the number of cells in a large number of replicates.

Dietary intake of pirfenidone ameliorates bleomycin-induced lung fibrosis in hamsters

There are no clinically efficacious drugs available for preventing the development of pulmonary fibrosis (PF). In the present study, we tested the antifibrotic potential of pirfenidone (PD) in the bleomycin (BL) hamster model of PF. Hamsters were intratracheally instilled with isotonic saline solution or BL (7.5 U/kg/5 ml). The animals were fed control diet containing 0.5% PD or the same diet without the drug 2 days before and throughout the study. The four groups were as follows: saline-instilled and fed the control diet (SCD); saline-instilled and fed the same diet containing PD (SPD); BL-instilled and fed the control diet (BCD); and BL-instilled and fed the same diet containing PD (BPD). The animals were killed at 21 days after intratracheal instillation and their lungs processed for various assays. The lung hydroxyproline levels, an index of PF, in SCD, SPD, BCD, and BPD groups were 949, 970, 1759, and 990 micrograms/lung, respectively. The SOD activity and malondialdehyde equivalent levels in the corresponding groups were 443, 524, 612, and 499 units/lung and 56, 49, 108, and 63 nmol/lung, respectively. The lung prolyl hydroxylase activities in the SPD, BCD, and BPD groups were 87%, 147%, and 93% of the control (SCD) group (4.2 x 10(4) dpm/lung/30 minutes), respectively. The lung myeloperoxidase activities were 97%, 236%, and 159% of the control group (0.73 units/lung), respectively. BL alone caused significant increases in all the biochemical markers of lung toxicity, and dietary intake of PD minimized the BL toxicity as reflected by significant decreases in all the above markers.(ABSTRACT TRUNCATED AT 250 WORDS)

Amelioration of bleomycin-induced lung fibrosis by treatment with the platelet activating factor receptor antagonist WEB 2086 in hamsters

Therapeutic use of bleomycin, an antineoplastic drug, is complicated by the development of a dose-dependent lung toxicity leading to fibrosis. This study tested the effectiveness of a platelet activating factor (PAF) receptor antagonist, WEB 2086, against bleomycin (BLEO)-induced lung fibrosis in hamsters. The animals were assigned to four groups: (1) saline (SA) + SA, (2) WEB 2086 (WEB) + SA, (3) SA + BLEO, and (4) WEB + BLEO. Sterile isotonic saline or WEB 2086 (10 mg/kg IP) was administered daily for the duration of the study starting 2 days prior to intratracheal (IT) instillation of saline or bleomycin (2.5, 2.0, and 1.5 units/kg 5 mL-1) in three consecutive doses at weekly intervals. The animals were killed at 21 days after the last IT instillation and their lungs were processed for various studies. The lung hydroxyproline levels in SA + SA, WEB + SA, SA + BLEO, and WEB + BLEO groups were 932 +/- 31, 943 +/- 48, 1302 +/- 72, and 964 +/- 63 micrograms/lung, respectively. The lung myeloperoxidase (MPO) activity and malondialdehyde equivalent, an index of lipid peroxidation, in the corresponding groups were 10 +/- 2, 8 +/- 2, 14 +/- 3, and 5 +/- 1 units/lung and 93 +/- 7, 77 +/- 5, 102 +/- 8, and 75 +/- 6 nmol/lung, respectively. The lung prolyl hydroxylase activity in the WEB + SA, SA + BLEO, and WEB + BLEO groups was 130.1 +/- 7.7, 236.2 +/- 12.8, and 138.1 +/- 7.0% of the SA + SA control group (8.3 x 10(4) dpm/lung 30 min-1), respectively. Daily treatment with WEB 2086 caused significant (p < or = .05) reductions in the BLEO-induced increases in the lung hydroxyproline content, prolyl hydroxylase and MPO activities, lipid peroxidation, and acid phosphatase activity of the BALF supernatant. Although daily treatment with WEB 2086 reduced the bleomycin-induced increases in the BALF total and neutrophil cell counts, BALF supernatant protein, and morphometric estimates of the lesions, these parameters were not significantly different from those of the SA-BLEO group. Histopathologic studies revealed that there were no lesions of alveolar consolidation and fibrosis in the lungs of WEB + BLEO group as compared with the SA + BLEO group. The results suggest that PAF is involved in the BLEO-induced lung fibrosis and that PAF-receptor antagonist may therefore be potentially useful in the attenuation of lung fibrosis caused by bleomycin.