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Older asthmatic patients may develop fixed airway obstruction and clinical signs of chronic obstructive pulmonary disease (COPD). We investigated the added value of pathological evaluation of bronchial biopsies to help differentiate asthma from COPD, taking into account smoking, age, and inhaled corticosteroid (ICS) use. Asthma and COPD patients (24 of each category) were matched for ICS use, age, FEV(1), and smoking habits. Five pulmonary and five general pathologists examined bronchial biopsies using an interactive website, without knowing patient information. They were asked to diagnose asthma or COPD on biopsy findings in both a pairwise and randomly mixed order of cases during four different phases, with intervals of 4-6 weeks, covering a maximal period of 36 weeks. Clinically concordant diagnoses of asthma or COPD varied between 63 %-73 %, without important differences between pairwise vs randomly mixed examination or between general vs pulmonary pathologists. The highest percentage of concordant diagnoses was in young asthmatic patients without ICS use and in COPD patients with ICS use. In non ICS users with fixed airway obstruction, a COPD diagnosis was favored if abnormal presence of glands, squamous metaplasia, and submucosal infiltrate was present and an asthma diagnosis in case of abnormal presence of goblet cells. In ICS users with fixed airway obstruction, abnormal presence of submucosal infiltrates, basement membrane thickening, eosinophils, and glands was associated with asthma. Histological characteristics in bronchial biopsies are reproducibly recognized by pathologists, yet the differentiation by histopathology between asthma and COPD is difficult without information about ICS use.

Background: The extent of epithelial injury in asthma is reflected by expression of the epidermal growth factor receptor (EGFR), which is increased in proportion to disease severity and is corticosteroid refractory. Although the EGFR is involved in epithelial growth and differentiation, it is unknown whether it also contributes to the inflammatory response in asthma., Objectives: Because severe asthma is characterized by neutrophilic inflammation, we investigated the relationship between EGFR activation and production of IL-8 and macrophage inhibitory protein-1 alpha (MIP-1alpha) using in vitro culture models and examined the association between epithelial expression of IL-8 and EGFR in bronchial biopsies from asthmatic subjects., Methods: H292 or primary bronchial epithelial cells were exposed to EGF or H2O2 to achieve ligand-dependent and ligand-independent EGFR activation; IL-8 mRNA was measured by real-time PCR and IL-8 and MIP-1alpha protein measured by enzyme-linked immunosorbent assay (ELISA). Epithelial IL-8 and EGFR expression in bronchial biopsies from asthmatic subjects was examined by immunohistochemistry and quantified by image analysis., Results: Using H292 cells, EGF and H2O2 increased IL-8 gene expression and release and this was completely suppressed by the EGFR-selective tyrosine kinase inhibitor, AG1478, but only partially by dexamethasone. MIP-1alpha release was not stimulated by EGF, whereas H2O2 caused a 1.8-fold increase and this was insensitive to AG1478. EGF also significantly stimulated IL-8 release from asthmatic or normal primary epithelial cell cultures established from bronchial brushings. In bronchial biopsies, epithelial IL-8, MIP-1alpha, EGFR and submucosal neutrophils were all significantly increased in severe compared to mild disease and there was a strong correlation between EGFR and IL-8 expression (r = 0.70, P < 0.001)., Conclusions: These results suggest that in severe asthma, epithelial damage has the potential to contribute to neutrophilic inflammation through enhanced production of IL-8 via EGFR- dependent mechanisms.

Because the asthmatic bronchial epithelium is characterized by widespread damage, we postulated that this is associated with expression of cell cycle inhibitors that control proliferation. Using bronchial biopsies, the epithelium was the major site of expression of the cyclin-dependent kinase inhibitor, p21(waf). Immunostaining usually occurred in the cytoplasm of columnar cells; however, in severe asthma, nuclear staining was also evident in the proliferative, basal cell compartment. p21(waf) expression was significantly higher in asthmatic versus nonasthmatic epithelium and was unaffected by corticosteroid treatment; proliferating cell nuclear antigen was not significantly different in any group. p21(waf), but not p27(kip1), mRNA and protein were induced by treatment of bronchial epithelial cells in vitro with transforming growth factor (TGF)-beta or H2O2, but not by dexamethasone, which induced p57(kip2). TGF-beta and dexamethasone inhibited epidermal growth factor (EGF)-induced DNA synthesis, whereas low concentrations of H2O2 synergized with EGF; at higher doses, growth inhibition and induction of apoptosis occurred. TGF-beta caused p21(waf) to become nuclear, suggesting interaction with the replicative machinery; however, in oxidant-stressed cells, p21(waf) was predominantly cytoplasmic, where it has been linked to cell survival. We conclude that p21(waf) overexpression in asthma influences cell proliferation and survival. This may cause abnormal repair responses that contribute to airway inflammation and remodeling.

To examine the role of the bronchial microvasculature and adhesion molecule expression in severe asthma, the authors have performed an immunohistochemical study on bronchial biopsies comparing 15 glucocorticoid-dependent asthmatics, 15 mild asthmatics and eight control subjects. Serially cut glycol methacrylate-embedded sections were stained with monoclonal antibodies identifying the vessel marker EN-4, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, E- and P-selectin. Sections were also stained for lymphocyte function associated antigen (LFA)-1 and very late antigen (VLA)-4. By comparison with mild asthma and nonasthma, severe asthma was characterized by increased numbers of submucosal vessels (p=0.009) which was associated with increased numbers of vessels expressing ICAM-1 (p=0.005). A highly significant correlation was found between the total number of EN-4+ vessels and the vessels expressing ICAM-1 (r=0.85, p=0.01). In contrast, E-selectin expression was lower in severe as compared with mild asthma (p=0.01) but not different from normal. No differences were found between the three groups in the expression of VCAM-1 and P-selectin nor in numbers of LFA-1+ and VLA-4+ cells. The results of this study support the notion that mucosal neovascularization is an important feature of airways remodelling in severe asthma. This is associated with a relatively higher density of vessels expressing intercellular adhesion molecule-1, although the expression of this adhesion molecule per vessel was not raised.

The authors have investigated whether the steroid-sparing effect of methotrexate (MTX) in severe orally glucocorticoid-insensitive asthmatics may be accounted for by the ability of this drug to increase the T-cell responsiveness sensitivity to dexamethasone in vitro. In addition the authors have investigated whether low-dose MTX treatment is associated with anti-inflammatory effects in peripheral blood and the bronchial mucosa. In eight patients with severe atopic asthma, using > or =15 mg x day(-1) prednisolone, the inhibitory effect of dexamethasone on mitogen stimulated peripheral blood mononuclear cells (PBMC) in vitro was tested before and after 8 weeks of uncontrolled treatment with MTX. Endobronchial biopsies were taken before and after MTX therapy in seven subsequent patients, and analysed using immunohistochemistry. In eight patients, serum was drawn for measuring levels of free interleukin (IL)-8. The in vitro sensitivity of PBMC to dexamethasone (at 1.6 x 10(-9) and 3.2 x 10(-10) mol x L(-1)) was significantly lower in the asthmatics before treatment when compared with the control subjects (p=0.03 and =0.001) but increased significantly after MTX treatment (p=0.04 and =0.02) to normal responsiveness. This was not associated with a decrease in peripheral blood T-cell numbers or activation. Except for a significant increase in the numbers of CD3+ (p=0.04), no significant numerical changes in activated T-cells, eosinophils, or mast cells were found (p>0.05). However, MTX treatment was associated with a significant fall in serum levels of free IL-8 (p=0.03). It is hypothesized that the steroid-sparing effect of methotrexate originates from increased sensitivity of lymphocytes to the inhibitory effects of glucocorticoids. The absence of an inhibitory effect on inflammatory cells in blood and mucosa suggests that this effect is achieved by modulating cell function rather than cell number.

To improve our understanding of the inflammatory mechanisms underlying severe disease, a biopsy study was performed comparing 15 clinically unstable glucocorticoid-dependent asthmatics, 10 mild asthmatics, and 10 control subjects. Compared with mild asthma, severe asthma was characterized by reduced mucosal eosinophilia. Whilst no significant differences were found in the numbers of mast cells, neutrophils, CD3+ and CD4+ T-cells between the three groups, up to a 4-fold increase In the numbers of activated T-lymphocytes bearing the interleukin (IL)-2 receptor (IL-2R) was found in the mucosa in severe asthma compared to mild asthma (p = 0.03) and control subjects (p = 0.003). Compared to control subjects, the mucosa of severe asthmatics contained significantly (p = 0.02) higher numbers of IL-5+ cells, with no differences between mild and severe disease. In contrast, staining for the anti-IL-4 monoclonal antibody 3H4 revealed that biopsies from mild asthmatics contained more IL4+ cells than biopsies from severe asthmatics and control subjects (p = 0.0008). In the severe asthmatics, a close correlation (r(s) = 0.76, p = 0.005) was found between the numbers of IL-2R-bearing cells and the variability in peak expiratory flow. In conclusion, persistent T-cell activation is a prominent feature of severe asthma. These results also indicate that interleukin-5, and not interleukin-4, is upregulated in severe disease.

Preliminary observations of the clinical efficacy of intravenous immunoglobulin in two patients with severe corticosteroid insensitive asthma are reported. In both patients treatment with intravenous immunoglobulin resulted in clinical improvement and enabled a significant reduction in the dose of prednisolone. In one of the patients fibreoptic bronchoscopy with endobronchial biopsies was performed and peripheral blood was analysed by flow cytometry before and after treatment. Immunohistological analysis of the biopsy samples after treatment showed a decrease in the number of all cell types, especially CD3+ T cells, CD4+ T cells, and activated CD25+ T lymphocytes, which was associated with a reduction in peripheral blood T cell activation. Intravenous immunoglobulin may be a valid option for the treatment of corticosteroid insensitive asthma. To elucidate the role and mode of action of intravenous immunoglobulin further studies in larger groups of patients are needed.

We have tested the hypothesis that the expression of interleukin-8 (IL-8) is increased in bronchial tissue and circulating leukocytes of atopic asthmatics, indicating a role for this chemokine in asthma. The concentration of IL-8 in its free form and complexed with IgG or IgA was measured by ELISA in bronchial tissue, serum, and lysates of freshly isolated peripheral blood mononuclear cells and granulocytes from subjects with mild or severe asthma and nonatopic nonasthmatic subjects. Serum ECP was measured by fluorescent enzyme immunoassay. Free IL-8 was detected in the sera (n = 44) and bronchial tissue (n = 9) of all subjects with severe atopic asthma, but it was undetectable in normal subjects and subjects with mild atopic asthma, suggesting that free IL-8 is a marker of severe asthma. A positive correlation between free IL-8 and serum ECP levels found in severe disease suggests that IL-8 is associated with eosinophil activation. Complexes of IL-8 with IgA and IgG were detected in all serum and tissue samples. However, the levels of the IL-8-IgA complex were increased in the bronchial mucosa in asthma, and in blood were related to disease activity. Together, these results point to upregulation of IL-8 production in asthma and the induction of IL-8 binding immunoglobulins of the IgA class in the inflamed mucosa. We suggest a proinflammatory role for these complexes in lung tissue.

Severe asthma is characterized by persistent T-cell activation, as demonstrated in both peripheral blood and bronchial mucosa. Endobronchial biopsy specimens of patients with severe, corticosteroid-dependent asthma revealed increased expression of CD25+ on mucosal T cells. Increased immunoreactivity for IL-5 further supports the evidence that the inflammatory response is orchestrated by TH2-type T cells. Peripheral blood eosinophils and total serum IgE levels were increased in the absence of allergen and despite optimal treatment. The chemokine IL-8 may also be an aggravating factor in severe asthma; as well as being a potent chemotactic and activating factor for neutrophils, it may also be chemoattractant for eosinophils. We have recently detected increased levels of free IL-8 in the peripheral blood of patients with chronic severe asthma but not in healthy control subjects or in patients with mild asthma, even after allergen challenge. In patients with severe asthma there may be an imbalance between IL-8 production and the blocking capacity of IL-8 autoantibodies. Higher levels of IL-8 complexed to IgA autoantibody and increased numbers of activated T cells were also found in patients with unstable asthma compared with patients who had severe but stable disease. We conclude that IL-8 may provide an additional marker of asthma severity and corticosteroid responsiveness.

We wanted to determine whether changes in bronchial hyperresponsiveness (BHR) following allergen challenge show a time relationship with inflammatory events in the airways of allergic asthmatic subjects. Lavage was performed and endobronchial biopsies were taken via the fiberoptic bronchoscope, before, and 3 and 24 h after, allergen challenge, on separate occasions, in nine dual asthmatic responders. The numbers of activated eosinophils, identified by immunohistochemistry, using the monoclonal anti-eosinophil cationic protein antibody, EG2, were significantly increased both at 3 h and at 24 h in the submucosa and bronchial lavage. A significant negative correlation was found between the number of EG2+ cells in the submucosa and in the bronchial lavage 24 h after the allergen challenge (r = -0.70). At 24 h, the amount of eosinophil cationic protein (ECP) was increased in the bronchial lavage. A significant correlation was observed between the amount of ECP at 3 h and the log provocative dose of house dust mite producing a 20% fall in forced expiratory volume in one second (PD20 HDM) (r = -0.63). The results suggest a recruitment of activated eosinophils to the submucosa and, further, to the epithelial lining, followed by degranulation. This process has already started 3 h after allergen challenge, and lasts for at least 24 h, which may result in mucosal damage and subsequent allergen-induced increase in BHR, before and after the late asthmatic reaction.

To determine whether a link exists between the recruitment of inflammatory cells in the airways on a bronchial and bronchoalveolar level and the development of allergen-induced increase in bronchial hyperresponsiveness after allergen challenge, we used bronchial lavage and bronchoalveolar lavage to assess the airway responses to allergen. Twelve symptomatic atopic asthmatics were studied. In all patients bronchial and bronchoalveolar lavage was performed before, 3 h, and 24 h after allergen challenge. Monoclonal antibodies were used directed against T cells (CD3, CD4, CD8) and the eosinophil cationic protein (EG2). Eight patients showed a dual asthmatic response; four patients showed only an early asthmatic reaction after allergen challenge. Clear differences were found between bronchial and bronchoalveolar lavage. Activated eosinophils (EG2) were significantly increased both at 3 h (p = 0.01) and 24 h (p = 0.005). The number of activated eosinophils was significantly higher in the dual responders. A correlation was observed between the severity of the late asthmatic reaction (LAR) and the number of epithelial cells in the bronchial recovery at 3 h, but not at 24 h, in patients who clinically developed a LAR. No significant changes in the number of CD3, CD4, and CD8 cells 3 and 24 h after the challenge both in the bronchial and bronchoalveolar recovery were observed. We conclude that the number of activated eosinophils in bronchial lavage is associated with the development of the LAR and allergen-induced increase in bronchial hyperresponsiveness.

The phenotypic cellular profile of bronchial lavage (BL) and bronchoalveolar lavage (BAL) was studied in 7 single early (SR) and 10 dual asthmatic responders (DR). Lavage was performed, after previously having determined bronchial hyperresponsiveness to histamine and the response to house dust mite (HDM) challenge. The recovered lavage fluid was separated in two fractions, BL and BAL. Total fluid recovery and cell number from the BL and BAL were comparable in both patient groups. Differential cell counting and immunocytochemistry were performed. DR had a significantly higher number of eosinophils and EG2+ cells in BL but not in their BAL. No differences could be found in CD4+, CD8+, and HLA-DR+ cells. A strong correlation was found between eosinophils in the BL+ and EG2+ cells in the BL (r = 0.79, p < 0.001) and between eosinophils in the BL and peripheral blood eosinophils (r = 0.70, p < 0.0025). The number of EG2+ cells and the number of epithelial cells in both BL and BAL showed a correlation (r = 0.55, p < 0.05). Dual responders had a higher total IgE (p < 0.01), and total serum IgE correlated well with the eosinophils in the BL (r = 0.85, p < 0.0001). Our observations demonstrate cellular differences in the lung on mainly a bronchial level between single early and dual asthmatic responders. A bronchial lavage eosinophil and EG2+ cell count and higher blood total IgE level are associated with the tendency to develop a dual asthmatic response.