Effect of diesel exhaust generated by a city bus engine on stress responses and innate immunity in primary bronchial epithelial cell cultures

Harmful effects of diesel emissions can be investigated via exposures of human epithelial cells, but most of previous studies have largely focused on the use of diesel particles or emission sources that are poorly representative of engines used in current traffic. We studied the cellular response of primary bronchial epithelial cells (PBECs) at the air-liquid interface (ALI) to the exposure to whole diesel exhaust (DE) generated by a Euro V bus engine, followed by treatment with UV-inactivated non-typeable Haemophilus influenzae (NTHi) bacteria to mimic microbial exposure. The effect of prolonged exposures was investigated, as well as the difference in the responses of cells from COPD and control donors and the effect of emissions generated during a cold start. HMOX1 and NQO1 expression was transiently induced after DE exposure. DE inhibited the NTHi-induced expression of human beta-defensin-2 (DEFB4A) and of the chaperone HSPA5/BiP. In contrast, expression of the stress-induced PPP1R15A/GADD34 and the chemokine CXCL8 was increased in cells exposed to DE and NTHi. HMOX1 induction was significant in both COPD and controls, while inhibition of DEFB4A expression by DE was significant only in COPD cells. No significant differences were observed when comparing cellular responses to cold engine start and prewarmed engine emissions.

High-affinity immunoglobulin E receptor expression is increased in large and small airways in fatal asthma

BACKGROUND

IgE and its high-affinity receptor FcɛRI play an important role in allergy and asthma. The distribution of FcɛRI expression in the airways and within the airway wall, however, is largely unknown.

OBJECTIVE

In this study, we aimed to map the distribution of FcɛRI in different layers of large airways (LA) and small airways (SA) in lung tissue from non-smoking and smoking patients who died of asthma [fatal asthma (FA)] and non-smoking controls (CTR).

METHODS

Postmortem lung tissue from 24 cases of non-smoking FA, 13 smoking FA patients and from 19 subjects who died of non-pulmonary causes (CTR) was immunohistochemically stained for FcɛRI and AA1 (mast cell tryptase marker). The expression of these markers was analysed in inner, muscle, and outer layers of both LA and SA by image analysis.

RESULTS

FcɛRI expression was higher in non-smoking and smoking FA compared with CTR in the inner and outer layer of SA. In the outer layer of LA, FcɛRI expression was higher in non-smoking FA compared with CTR. AA1 was higher in non-smoking FA compared with smoking FA and CTR in the outer layer of the SA, which was correlated with FcɛRI in this layer.

CONCLUSION

Our results show that the expression of FcɛRI is higher in both LA and SA in FA compared with CTR. These differences are predominantly found in the outer layer where they can be attributed in part to the increased mast cell numbers. These results indicate an increased capacity to mount IgE-mediated reactions in FA, both in LA and SA.

Increased number of B-cells in bronchial biopsies in COPD

Recently, it has been shown that the accumulated volume of B-cells in small airways is increased in chronic obstructive pulmonary disease (COPD) Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 3 and 4. Little is known about the number of B-cells in central airways in COPD. The present authors hypothesised that the number of B-cells in bronchial biopsies of large airways is higher in patients with COPD than in controls without airflow limitation and higher in more severe COPD. Therefore, bronchial biopsies were collected from 114 COPD patients (postbronchodilator forced expiratory volume in one second (FEV1) 63+/-9 % predicted value, FEV1/inspiratory vital capacity (IVC) 48+/-9%) and 28 controls (postbronchodilator FEV1 108+/-12 % predicted value, FEV1/IVC 78+/-4%). Paraffin sections were stained for B-cells (CD20+) and their number was determined in the subepithelial area (excluding muscle, glands and vessels). B-cell numbers were higher in patients with COPD versus controls (8.5 versus 3.9 cells x mm(-2), respectively) and higher in patients with GOLD severity stage 3 (n = 11) than stage 2 (n = 103; 22.3 versus 7.8 cells x mm(-2)). No relationship was found between the number of B-cells and clinical characteristics within the chronic obstructive pulmonary disease group. The authors suggest that these increased B-cell numbers may have an important contribution to the pathogenesis of chronic obstructive pulmonary disease.

Human neutrophil defensins and secretory leukocyte proteinase inhibitor in squamous metaplastic epithelium of bronchial airways

OBJECTIVE

The aim of this study was to analyze a possible contribution of human neutrophil defensins and secretory leukocyte proteinase inhibitor (SLPI) to the induction of airway epithelial changes such as squamous cell metaplasia.

MATERIALS AND METHODS

The presence of these molecules and the number of proliferating (Ki-67-positive) epithelial cells was analyzed by immunohistochemistry in bronchial epithelium from subjects with (n = 15) or without (n = 14) chronic obstructive pulmonary disease (COPD).

RESULTS

Our data demonstrate higher numbers of defensin-positive (p = 0.0001), elastase-positive (p = 0.0001) and Ki-67-positive (p = 0.0001) cells in areas with squamous cell metaplasia as compared to areas with intact or damaged epithelium, while the reverse was observed for SLPI expression (p = 0.002). No differences were observed between subjects with or without COPD, nor between current smokers and those that had stopped smoking.

CONCLUSIONS

These data are in line with a role of defensins in the hyperproliferative phenotype of squamous metaplastic lesions in the airways. This role does not seem to be restricted to patients with COPD.

Proliferation and inflammation in bronchial epithelium after allergen in atopic asthmatics

BACKGROUND

The mechanisms that regulate epithelial integrity and repair in asthma are poorly understood. We hypothesized that allergen exposure could alter epithelial inflammation, damage and proliferation in atopic asthma.

OBJECTIVE

We studied epithelial cell infiltration, shedding, expression of the proliferation marker Ki-67 and the epithelial cell-cell adhesion molecules Ep-CAM and E-cadherin in bronchial biopsies of 10 atopic mild asthmatics 48 h after experimental diluent (D) and allergen (A) challenge in a cross-over design.

METHODS

Epithelial shedding, expressed as percentage of not intact epithelium, Ki-67+, eosinophil/EG-2+, CD4+ and CD8+ cells were quantified by image analysis in bronchial epithelium, and adhesion molecules were analysed semi-quantitatively.

RESULTS

Epithelial shedding was not altered by A (D: 88.1+/-3.1% vs. A: 89.2+/-3.7%; P=0.63). The numbers of Ki-67+ epithelial (D: 10.2+/-0.2 vs. A: 19.9+/-0.3 cells/mm; P=0.03), EG-2+ (D: 4.3+/-0.5 vs. A: 27+/-0.3 cells/mm; P=0.04) and CD4+ cells (D: 1.7+/-1.2 vs. A: 12.3+/-0.6 cells/mm; P=0.04) were significantly increased after A, whilst CD8+ numbers were not significantly changed (P>0.05). E-cadherin and Ep-CAM epithelial staining showed a similar intensity after D and A (P>0.05). We found a positive correlation between EG-2+ and Ki-67+ cells in the epithelium (Rs: 0.63; P=0.02).

CONCLUSION

Our study indicates that allergen challenge increases epithelial proliferation in conjunction with inflammation at 2 days after exposure. This favours the hypothesis that long-lasting epithelial restitution is involved in the pathogenesis of asthma.

Allergen-induced impairment of bronchoprotective nitric oxide synthesis in asthma

BACKGROUND

Endogenous nitric oxide protects against airway hyperresponsiveness (AHR) to bradykinin in mild asthma, whereas AHR to bradykinin is enhanced by inhaled allergens.

OBJECTIVE

Hypothesizing that allergen exposure impairs bronchoprotective nitric oxide within the airways, we studied the effect of the inhaled nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on AHR to bradykinin before and after allergen challenge in 10 subjects with atopic asthma.

METHODS

The study consisted of 3 periods (1 diluent and 2 allergen challenges). AHR to bradykinin (PD(20)BK) was examined before and 48 hours after allergen challenge, both after double-blinded pretreatment with L-NMMA or placebo. The accompanying expression of the various NOS isoforms (ecNOS, nNOS, and iNOS) was examined by means of immunohistochemistry in bronchial biopsies obtained after diluent and allergen challenge.

RESULTS

After placebo, AHR to BK worsened after allergen challenge in comparison with before allergen challenge (PD(20)BK, 70.8 nmol [range, 6.3-331] and 257 nmol [35.5-2041], respectively; P =.0004). After L-NMMA, preallergen and postallergen PD(20)BK values (50.1 nmol [1.8-200] vs 52.5 nmol [6.9-204]; P =.88) were similarly reduced (P <.01) and not different from the postplacebo/postallergen value (P >.05). After allergen challenge, the intensity of staining in bronchial epithelium decreased for ecNOS (P =.03) and increased for iNOS (P =.009). These changes in immunostaining were correlated with the accompanying worsening in AHR to BK (R(s) = -0.66 and 0.71; P <.04).

CONCLUSIONS

These data indicate that allergen exposure in asthma induces increased airway hyperresponsiveness to bradykinin through impaired release of bronchoprotective nitric oxide associated with downregulation of ecNOS. This suggests that new therapeutic strategies towards restoring the balance among the NOS isoforms during asthma exacerbations are warranted.

Monocyte chemoattractant protein 1, interleukin 8, and chronic airways inflammation in COPD

Chronic obstructive pulmonary disease (COPD) is one of the most common causes of death, with cigarette smoking among the main risk factors. Hallmarks of COPD include chronic airflow obstruction and chronic inflammation in the airway walls or alveolar septa. An earlier study reported elevated numbers of macrophages and mast cells within the bronchiolar epithelium in smokers with COPD, compared with smokers without. Since specific chemokines may be involved in this influx, the in situ protein and mRNA expression of monocyte chemoattractant protein 1 (MCP-1) and of interleukin 8 (IL-8) were studied in tumour-free peripheral lung tissue resected for lung cancer of current or ex-smokers with COPD (FEV(1)<75%; n=14) and without COPD (FEV(1)>84; n=14). MCP-1 was expressed by macrophages, T cells, and endothelial and epithelial cells. Its receptor, CCR2, is expressed by macrophages, mast cells, and epithelial cells. IL-8 was found in neutrophils, epithelial cells, and macrophages. In subjects with COPD, semi-quantitative analysis revealed 1.5-fold higher levels of MCP-1 mRNA and IL-8 mRNA and protein in bronchiolar epithelium (p<0.01) and 1.4-fold higher levels of CCR2 in macrophages (p=0.014) than in subjects without COPD. The bronchiolar epithelial MCP-1 mRNA expression correlated with both CCR2 expression on macrophages and mast cells (p<0.05) and the numbers of intra-epithelial macrophages and mast cells (p<0.04). The epithelial IL-8 expression did not correlate with the numbers of neutrophils, macrophages, CD45RO+, CD8+, or mast cells. These data suggest that MCP-1 and CCR2 are involved in the recruitment of macrophages and mast cells into the airway epithelium in COPD.

Transforming growth factor beta1 and recruitment of macrophages and mast cells in airways in chronic obstructive pulmonary disease

Chronic airways inflammation is one of the features of chronic obstructive pulmonary disease (COPD). We demonstrated previously that bronchiolar epithelium in COPD contains increased numbers of macrophages and mast cells. Transforming growth factor beta1 (TGF-beta1) may be involved in this influx because it has chemotactic activity for macrophages and mast cells. In this study, we examined expression patterns of TGF-beta1, TGF-beta receptors type I and II (TGF-betaRI and TGF-betaRII) by immunohistochemistry and mRNA in situ hybridization in peripheral lung tissue of 14 current or ex-smokers with COPD (FEV1 < 75%) and 14 without COPD (FEV1 > 84%). In both groups, TGF-beta1 and its receptors are present in airway and alveolar epithelial cells, airway and vascular smooth muscle cells, and tissue and alveolar CD68(+) cells (considered herein to be macrophages). In subjects with COPD, a semiquantitative analysis revealed approximately twofold higher levels of TGF-beta1 mRNA and protein in bronchiolar and alveolar epithelium (p < 0.02) as compared with subjects without COPD. With regard to bronchiolar epithelial cells, we found a significant correlation between TGF-beta1 mRNA and protein expression (r = 0.62; p < 0.002), and between the FEV1 of all subjects together and TGF-beta1 protein (r = -0.60; p < 0.0002) and mRNA (r = -0.67; p < 0. 002) levels. The epithelial expression of TGF-beta1 mRNA and TGF-beta1 protein correlates with the number of intraepithelial macrophages (both: r = 0.44; p < 0.03) whereas intraepithelial mast cell numbers correlate with epithelial TGF-beta1 mRNA expression. These data suggest a role for TGF-beta1 in recruiting macrophages into the airway epithelium in COPD.

A comparison of the detection sensitivity of lymphocyte membrane antigens using fluorescein and phosphor immunoconjugates

In this study we compared the sensitivity of immunocytochemical procedures, using conventional and time-resolved fluorescent dyes, in a model system consisting of paraformaldehyde-fixed human lymphocytes. The lymphocytes were stained for the presence of the CD4 epitope by indirect immunofluorescence using FITC as label or by using time-resolved luminescent immunophosphors. These immunophosphors were primarily developed for use under time-resolved fluorescence conditions, but they are also very well suited for use in conventional fluorescence microscopes. The differently labeled cells were first examined visually with a conventional fluorescence microscope in a double-blind study. The fluorescence was also measured with a CCD camera mounted on a specially constructed time-resolved fluorescence microscope which allows the suppression of the fast decaying fluorescence, thereby permitting visualization of the specific, slowing decaying luminescence of the phosphor label. With this microscope FITC and immunophosphor labeled lymphocytes were compared under normal conditions (i.e., continuous excitation) and under conditions of time-resolved registration. Conventional fluorescence microscopy revealed a better sensitivity in favor of the phosphor conjugates. This difference became more prominent when the preparations were quantitatively assessed with the CCD-time-resolved microscope. Time-resolved microscopy permitted a suppression of fast decaying fluorescence better than 1 to 10(6).

Immunochemical detection of proteins and nucleic acids on filters using small luminescent inorganic crystals as markers

A new luminescent marker for the immunochemical detection of proteins and nucleic acids on filters is reported. The label consists of inorganic crystals, generally called phosphors, with a particle size of 0.1-0.3 microns, stabilized in suspension with polycarboxylic acids and subsequently conjugated to immunoreactive macromolecules. Immunophosphor conjugates exhibit slowly decaying fluorescence that is strong and practically nonfading and not sensitive to quenching by water molecules. They are therefore suited for conventional fluorescence detection as well as for time-resolved detection. The lifetime of the phosphors was in the micro/milliseconds range upon excitation with ultraviolet light. Proteins or nucleic acids immobilized on nitrocellulose filters were detected immunochemically or by hybridization, using haptenized nucleic acid probes followed by immunochemical detection, respectively. The ultimate detection limit of proteins, using phosphor-labeled macromolecules including an immunochemical amplification step, was found to be 10 fg. The detection limit of nucleic acids was 300 fg for demonstration of hapten-labeled probes and 10 pg in hybridization formats with hapten-labeled probes. The sensitivity of methods using phosphor-labeled macromolecules was in all cases as good as or better than that of methods using alkaline phosphatase developed to NBT/BCIP. The use of immunophosphors for detection of proteins and nucleic acids on Western and Southern blots is demonstrated. Finally, the use of multiple phosphors with different kinetic and spectral characteristics for multiparameter studies is indicated.

Preparation and microscopic visualization of multicolor luminescent immunophosphors

The preparation of charge-stabilized suspensions of small phosphor particles (0.1-0.3 micron) and their coupling with antibodies to immunoreactive conjugates is described. Phosphor particles consisting of yttriumoxisulfide activated with europium served as a model system in the evaluation of the stabilizing properties of several polycarboxylic acids. The optimal reagents were then applied to other phosphors which differ in spectral characteristics as well as in luminescence lifetime. These phosphors were ground to a size of 0.1-0.3 micron and proteins or other macromolecules were adsorbed to the phosphor particles to prepare conjugates of different physico-chemical properties. A time-resolved microscope, suitable for real time visualization of the time-delayed luminescence of the immunophosphors by the human eye, is described in detail. Since most phosphors require excitation with far UV light, a special fluorescence microscope allowing far UV excitation was developed for conventional visualization of the luminescence emitted by the phosphor. The possibility of multiple color labeling using various phosphor conjugates was demonstrated in a model system consisting of haptenized latex beads.

Inorganic phosphors as new luminescent labels for immunocytochemistry and time-resolved microscopy

A new strongly luminescent marker consisting of inorganic crystals is described for time-resolved microscopy. These crystals, known as phosphors, show delayed luminescence, unlike prompt fluorescent labels such as FITC, TRITC and phycobiliproteins, and are therefore potentially suitable for time-resolved microscopy. The luminescence of these phosphors is strong and non-fading in comparison to FITC/TRITC, and not significantly influenced by pH or temperature. The phosphor yttriumoxisulfide activated with europium emits maximally at 620 nm with a typical half life-time of approximately 700 musec, upon excitation with near ultraviolet light (360 nm). Phosphors for immunocytochemical staining were made by ball milling and were stabilized in suspension with polycarboxylic acids. Proteins such as avidin, protein A or immunoglobulins were allowed to adsorb to the surface of the phosphors. The immunocytochemical properties of the conjugates were evaluated in a model system of latex beads with defined surface antigens and in a cellular system containing fixed human lymphocytes or erythrocytes. Specific cytochemical staining was observed in suspension as well as on glass slides. A specially constructed time-resolved microscope was used to suppress the fast decaying fluorescence, thereby permitting visualization of the specific, slowly decaying luminescence of the phosphor label without the necessity of integration. Finally, the use of multiple phosphors with different kinetic and spectral characteristics for multiparameter studies is indicated.