IL-4 and IL-5 mRNA and protein in bronchial biopsies from patients with atopic and nonatopic asthma: evidence against "intrinsic" asthma being a distinct immunopathologic entity

Leukotriene B4 production in human mononuclear phagocytes is modulated by interleukin-4-induced 15-lipoxygenase

The aim of this study was to evaluate the consequences of interleukin (IL)-4-induced 15-lipoxygenase (15-LO) expression on leukotriene B4 (LTB4) synthesis in human monocytes. Human monocytes incubated for 24, 48, and 72 h with IL-4 (10 ng/ml) were stimulated with Ca2+-ionophore A23187 (calcimycin; 5 microM) or opsonized zymosan. 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE], LTB4, and arachidonic acid (AA) release were measured by high-performance liquid chromatography/radioimmunoassay, liquid chromatography/tandem mass spectrometry (LC/MS/MS), or gas chromatography/mass spectrometry. 15-LO activity was evaluated in AA-treated monocytes. 15-LO, 5-lipoxygenase (5-LO) and 5-LO activating protein (FLAP) expression were analyzed by reverse transcription-polymerase chain reaction. Neutrophil chemotactic activity was evaluated using a microtaxis chamber assay. A23187-induced synthesis of 15(S)-HETE was significantly increased after treatment with IL-4 (10 ng/ml) for 48 and 72 h (p < 0.001). Concomitant decrease of LTB4 release was observed after 72 h of incubation with IL-4 (p < 0.001). LC/MS/MS analysis confirmed the production of 15(S)-HETE and the significant inhibition of LTB4 synthesis in IL-4-treated monocyte after challenge with opsonized zymosan. IL-4 treatment induced 15-LO enzymatic activity as well as 15-LO mRNA, but did not affect either 5-LO or FLAP mRNA expression in monocytes. Supernatant from IL-4-treated monocytes showed significantly lower neutrophil chemotactic activity than controls. 15(S)-HETE significantly inhibited LTB4 production induced by A23187-stimulated human monocytes without affecting AA release. IL-4-induced expression of 15-LO in monocytes caused a significant reduction of LTB4 production. Whereas this effect did not reflect changes in 5-LO and FLAP mRNA expression, synthetic 15(S)-HETE was able to significantly inhibit the synthesis of LTB4, without affecting AA release.

Expression of activation markers and cytokine mRNA by peripheral blood CD4 and CD8 T cells in atopic and nonatopic childhood asthma: effect of inhaled glucocorticoid therapy

HYPOTHESIS

Activated CD8 as well as CD4 T cells contribute to the production of asthma-relevant cytokines in both atopic and nonatopic childhood asthma.

OBJECTIVES

To measure the percentages of peripheral blood CD4 and CD8 T cells expressing naïve/memory (CD45RA/CD45RO) and activation (HLA-DR, CD25) markers, as well as mRNA-encoding interleukin-4 (IL-4) and interleukin-5 (IL-5) in atopic and nonatopic childhood asthmatics and in nonasthmatic controls matched for age and atopic status; and to study the effects of inhaled glucocorticoid therapy of the asthmatics on these measurements.

METHODS

Peripheral blood mononuclear cells were isolated from 17 atopic and 8 nonatopic stable (not acutely ill) asthmatics aged 7 to 16 years with moderate-to-severe disease and from 15 nonasthmatic controls matched for age and atopic status. Activation markers on CD4 and CD8 T cells were measured by flow cytometry, and expression of cytokine mRNA by in situ hybridization with CD4 and CD8 T cells were isolated using magnetic beads. Measurements were repeated in 18 of the asthmatics 4 to 6 months after initiation or escalation of inhaled glucocorticoid therapy for inadequately controlled asthma.

RESULTS

The percentages of CD4 T cells expressing CD45RO but not CD45RA were elevated in both asthma groups as compared with the relevant controls and were reduced in association with de novo or augmented inhaled glucocorticoid therapy. The percentages of CD8 T cells expressing both markers were not elevated in asthmatics as compared with controls. The percentages of both CD4 and CD8 T lymphocytes expressing HLA-DR and CD25 were elevated in the asthmatics as compared with controls, and significantly reduced in association with de novo or augmented inhaled glucocorticoid therapy. Elevated percentages of CD4 T cells expressing mRNA encoding IL-4 and IL-5, and CD8 T lymphocytes expressing IL-5, were found in asthmatics as compared with the controls. De novo or augmented inhaled glucocorticoid therapy was associated with significant reductions in the percentages of CD4 T cells expressing IL-5 and IL-4 mRNA, as well as improvements in lung function, symptom scores, and bronchial hyperresponsiveness to metacholine (PD20) in both the atopic and nonatopic asthmatics.

CONCLUSIONS

The data are consistent with the hypothesis that both activated CD4 and CD8 T cells are associated with child asthma, and that CD4 T cells make a greater contribution to IL-4 and IL-5 synthesis. Increased dosages of inhaled glucocorticoid resulted in clinical improvement in the asthmatics along with reduced T-cell activation and cytokine mRNA expression, suggesting a possible causal association.

Chlamydia trachomatis infection inhibits airway eosinophilic inflammation induced by ragweed

While much progress has been achieved in controlling infectious diseases, there is a startling increase in the prevalence of allergic disorders in developed countries. Previous studies using experimental murine models of asthma have demonstrated that mycobacterial infections are capable of suppressing asthma-like reactions induced by ovalbumin (OVA). Using a different intracellular bacterium, Chlamydia trachomatis mouse pneumonitis (MoPn), we examined the effect of infection on the development of allergic responses to a common natural airborne allergen, ragweed (RW). The data showed that airway eosinophilia induced by ragweed sensitization/challenge was significantly reduced in MoPn-infected mice. MoPn-infected mice also exhibited significantly lower levels of allergen-driven Th2 cytokine production, namely IL-4, IL-5, IL-10, and IL-13, following ragweed exposure in comparison with those treated with ragweed only. Additionally, the production of eotaxin, a C-C chemokine for eosinophil chemoattraction following RW exposure, was significantly reduced in the lungs of MoPn-infected mice. However, MoPn infection did not reduce the levels of RW-specific IgE and IgG1 production in the sera, nor did it diminish the level of total serum IgE. These data provide evidence that the suppression of the allergic airway inflammation induced by a common environmental allergen is attainable through intracellular bacterial infection.

[Identification of new diagnostic categories within bronchial asthma and COPD. A review of traditional classifications]

The overlapping of function test results and clinical symptoms of airway diseases makes it difficult to differentiate sub-categories of diagnoses. Our aim was to identify "occult" categories within the traditional diagnostic labels for bronchial asthma and chronic bronchitis. We studied 211 patients with those diagnoses by lung function testing (spirometry), variability of obstruction (bronchodilator test, peak expiratory flow, and bronchial challenge testing), atopy (prick test, total serum IgE), biological parameters (eosinophil count), frequency of smoking and symptoms. Multivariant analysis was used to group the data (Quick Cluster) and reclassify the subjects based on the selected parametric clusters with factorial analysis of the principal components. This analysis allowed us to identify four types of patients by diagnosis (atopic asthma, asthmatic bronchitis, simple chronic bronchitis and hyperresponsive chronic bronchitis) which we consider to represent the diagnostic categories with clinical relevance and which would overlap and be partially overshadowed by the diagnoses of bronchial asthma and chronic bronchitis.

Interleukin-4 and interleukin-5 gene expression and inflammation in the mucus-secreting glands and subepithelial tissue of smokers with chronic bronchitis. Lack of relationship with CD8(+) cells

We wished to determine if the inflammatory cells surrounding the airway mucus-secreting glands in chronic bronchitis (CB) were associated with interleukin (IL)-4 and IL-5 mRNA expression and whether the CD8 T cell population expressed these cytokines. Digoxigenin-labeled IL-4 and IL-5 antisense RNA probes were used to detect gene expression in 11 asymptomic smokers (AS), 11 smokers with CB alone with normal lung function, and 10 smokers with chronic bronchitis and coexisting chronic obstructive pulmonary disease (CB+COPD; FEV(1)% of predicted of 43-77% and FEV(1)/ FVC of 51-68%). There were approximately three times as many IL-4 than IL-5 mRNA(+) cells. The highest number of IL-4 mRNA(+) cells were in the submucosal glands of the CB group with normal lung function (216/mm(2)), significantly higher than the values in either the AS (63/mm(2)) or the CB+COPD (87/mm(2)) groups, respectively (p < 0.01). There were similar group differences when the total numbers of inflammatory cells were compared. Accordingly, there was a positive correlation between the number of IL-4 mRNA(+) cells and the total number of inflammatory cells in both the subepithelium and glandular compartments (r = 0.60; p = 0.01 and r = 0.70; p = 0.02, respectively). There were no significant associations between the numbers of CD8(+) and IL-4 or IL-5 mRNA(+) cells. Of 1328 IL-4(+) and 1404 CD8(+) cells counted none was double labeled. Of 727 IL-5(+) and 1569 CD8(+) cells, none was double labeled. In contrast, as a positive control, 34% of tumor necrosis factor (TNF)-alpha(+) cells were also CD8(+) and 15% of CD8(+) cells were TNF-alpha positive. Thus, cells other than the CD8(+) phenotype produce IL-4 and IL-5 in CB. We conclude that there is increased inflammation and IL-4 gene expression in the mucus-secreting glands and the airway mucosa of smokers with bronchitis: both are lower in those with CB and coexisting COPD suggesting that airway inflammation in CB is reduced when airway obstruction develops.

Exhaled nitric oxide levels in non-allergic and allergic mono- or polysensitised children with asthma

BACKGROUND

Increased fractional exhaled NO concentrations (FENO) and blood/tissue eosinophilia are frequently reported in allergic children with mild asthma and are thought to reflect the intensity of the inflammation characterising the disease. The aim of this study was to investigate possible differences in FENO levels or in the intensity of the blood eosinophilia in allergic and non-allergic asthmatic children.

METHODS

112 children with stable, mild, intermittent asthma with a positive bronchial challenge to methacholine were consecutively enrolled in the study; 56 were skin prick test and RAST negative (non-sensitised) while 56 were sensitised to house dust mites (23 only to house dust mites (monosensitised) and 33 were sensitised to mites and at least another class of allergens (pollens, pet danders, or moulds)). Nineteen sex and age matched healthy children formed a control group.

RESULTS

Compared with non-allergic patients, allergic children had a significantly higher rate of blood eosinophilia (p=0.0001) with no differences between mono- and polysensitised individuals. Forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), forced expiratory flow at 25-75% of vital capacity (FEF(25-75%)), and the degree of bronchial reactivity to methacholine were similar in non-atopic and atopic children, with no differences between mono- and polysensitised individuals. FENO levels measured by chemiluminescence analyser were higher in asthmatic children (15.9 (14.3) ppb) than in the control group (7.6 (1.6) ppb, p=0.04) and higher in allergic patients (23.9 (2.1) ppb) than in non-allergic patients (7.9 (0.8) ppb, p=0.0001), but there were no differences between mono- and polysensitised individuals (p>0.1). Significant correlations between blood eosinophilia and FENO levels were seen only in allergic (r=0.35, p<0.01) and in polysensitised individuals (r=0.45, p<0.05).

CONCLUSIONS

In children with mild asthma, a similar degree of functional disease severity may be associated with a higher inflammatory component in allergic than in non-allergic subjects.

Exhaled nitric oxide in asthmatic and non-asthmatic children: influence of type of allergen sensitization and exposure to tobacco smoke

Asthmatic bronchial inflammation is associated with increased nitric oxide concentrations in exhaled air (eNO). Recent data suggest that this effect arises from atopy. Our aim in this study was to find out whether atopy and sensitization to particular allergens influences eNO levels. A total of 213 subjects (41 asthmatics and 172 controls) (96 boys and 117 girls, 7.3-14 years of age) were studied. Parents completed a questionnaire that sought information on their children's respiratory symptoms and exposure to tobacco smoke. Subjects underwent skin-prick tests for the following common allergens: Dermatophagoides pteronyssinus (Dpt), cat fur, Aspergillus fumigatus, Alternaria tenuis, mixed grass, mixed tree pollen, Parietaria officinalis, egg, and cow's milk. eNO was collected in 1-l mylar bags (exhaled pressure 10 cmH2O, flow 58 ml/s) and analyzed by using chemiluminescence. Atopic and non-atopic children without a history of chronic respiratory symptoms had a similar geometric mean eNO (atopics, n = 28, 11.2 p.p.b.; non-atopics, n = 96, 10.0 p.p.b.; mean ratio 1.1, 95% confidence interval [CI]: 0.7-1.6). Conversely, atopic asthmatic subjects had significantly higher eNO values than non-atopic asthmatic subjects (atopics, n = 25, 24.8 p.p.b.; non-atopics, n = 16, 11.4 p.p.b.; mean ratio 2.2, 95% CI: 1.2-3.9, p= 0.000). In children with rhinitis alone (n = 15) and those with lower respiratory symptoms other than asthma (n = 33), eNO increased slightly, but not significantly, with atopy. eNO levels correlated significantly with Dpt wheal size (r = 0.51) as well with the wheal size for cat, mixed grass, and Parietaria officinalis (r = 0.30-0.29), and with the sum of all wheals (r = 0.47) (p= 0.000). Subjects sensitized only for Dpt (but not those subjects sensitized only for grass pollen or other allergens) showed significantly higher eNO levels than non-atopic subjects (16.4 p.p.b. vs. 10.2 p.p.b., mean ratio 1.6, 95% CI: 1.1-2.3, p= 0.002). In asthmatic subjects, Dpt sensitization markedly increased eNO levels (Dpt-sensitized subjects: 28.0 p.p.b.; Dpt-unsensitized subjects: 12.2 p.p.b.; mean ratio 2.3, 95% CI: 1.5-3.5, p= 0.000). Non-asthmatic Dpt-sensitized subjects also had significantly higher eNO values than non-asthmatic, non-Dpt-sensitized subjects (14.2 p.p.b. vs. 10.1 p.p.b.; mean ratio 1.4, 95% CI: 1.1-1.9, p= 0.008). No difference was found between eNO levels in asthmatic subjects and control subjects exposed or unexposed to tobacco smoke. In conclusion, eNO concentrations are high in atopic asthmatic children and particularly high in atopic asthmatics who are sensitized to house-dust mite allergen.

Early interleukin 4-dependent response can induce airway hyperreactivity before development of airway inflammation in a mouse model of asthma

In experimental models of bronchial asthma with mice, airway inflammation and increase in airway hyperreactivity (AHR) are induced by a combination of systemic sensitization and airway challenge with allergens. In this report, we present another possibility: that systemic antigen-specific sensitization alone can induce AHR before the development of inflammation in the airway. Male BALB/c mice were sensitized with ovalbumin (OVA) by a combination of intraperitoneal injection and aerosol inhalation, and various parameters for airway inflammation and hyperreactivity were sequentially analyzed. Bronchial response measured by a noninvasive method (enhanced pause) and the eosinophil count and interleukin (IL)-5 concentration in bronchoalveolar lavage fluid (BALF) gradually increased following the sensitization, and significant increase was achieved after repeated OVA aerosol inhalation along with development of histologic changes of the airway. In contrast, AHR was already significantly increased by systemic sensitization alone, although airway inflammation hardly developed at that time point. BALF IL-4 concentration and the expression of IL-4 mRNA in the lung reached maximal values after the systemic sensitization, then subsequently decreased. Treatment of mice with anti-IL-4 neutralizing antibody during systemic sensitization significantly suppressed this early increase in AHR. In addition, IL-4 gene-targeted mice did not reveal this early increase in AHR by systemic sensitization. These results suggest that an immune response in the lung in an early stage of sensitization can induce airway hyperreactivity before development of an eosinophilic airway inflammation in BALB/c mice and that IL-4 plays an essential role in this process. If this early increase in AHR does occur in sensitized human infants, it could be another therapeutic target for early prevention of the future onset of asthma.

Proliferation and release of IL-5 and IFN-gamma by peripheral blood mononuclear cells from cat-allergic asthmatics and rhinitics, non-cat-allergic asthmatics, and normal controls to peptides derived from Fel d 1 chain 1

BACKGROUND

In general, T cells from normal, nonatopic individuals respond to aeroallergens with synthesis and release of IFN-gamma. In contrast, release of T(H)2-type cytokines by activated lymphocytes is a feature of allergic rhinitis and atopic asthma.

OBJECTIVE

The purpose of this study was to determine differences in T-cell recognition of epitopes within allergenic sequences, in terms of proliferation and cytokine production, in subjects with atopic asthma compared with subjects with allergic rhinitis and normal controls.

METHODS

Proliferative responses and IL-5/IFN-gamma release patterns from PBMCs from cat-allergic asthmatic, cat-allergic rhinitic, and non-cat-allergic asthmatic subjects and nonatopic normal controls were determined in primary cultures. Cells were challenged with 7 overlapping peptides spanning chain 1 of the major cat allergen, Fel d 1.

RESULTS

The 4 groups did not differ with respect to the ability to mount proliferative responses to Fel d 1 peptides. In all groups, the IFN-gamma responses were predominantly to the amino terminus peptides. Cat-allergic and non-cat-allergic asthmatic subjects (and not cat-allergic rhinitic subjects and normal controls) made IL-5 responses to most of the Fel d 1 peptides, the result being a mixed (T(H)0) cytokine response at the N-terminus and a restricted (T(H)2) response at the C-terminus.

CONCLUSION

Proliferative and IL-5/IFN-gamma responses of T cells from asthmatic and atopic rhinitic subjects and normal controls to allergen peptides can be dissociated. Furthermore, differing cytokine responses to peptides derived from a single antigen suggest that certain domains of the molecule might preferentially induce IL-5 rather than IFN-gamma and as a result could be more important in disease pathogenesis.

Interleukin-4 rapidly inhibits calcium transients in response to carbachol in bovine airway smooth muscle cells

To assess interleukin (IL)-4 effects on calcium signaling, bovine airway smooth-muscle (ASM) cells were loaded with fura-2 and cytosolic calcium ([Ca(2+)](i)) was measured in single cells by digital microscopy. Human recombinant IL-4 (50 ng/ml) caused small increases in [Ca(2+)](i). For single cells, carbachol-stimulated calcium transients were compared before (S1) and after (S2) exposure to IL-4 or IL-13. When cells were treated with IL-4 (50 ng/ml) for 20 min, the S2/S1 ratio was 0.17 +/- 0.04 (n = 7) even though IL-4 had been washed from the chamber for 10 min before the S2 response. In contrast, controls not treated with IL-4 had S2/S1 of 0.70 +/- 0.04 (n = 13, P < 0.01). Lower concentrations of IL-4 variably decreased transients and IL-13 had no effect. In other experiments, 5 min of IL-4 did not immediately decrease transients but did after a 25-min delay. Goat antihuman IL-4 antibody abolished the effect of IL-4. IL-4 (50 ng/ml) also inhibited responses to caffeine (S2/S1: 0.30 +/- 0.04 and 0.54 +/- 0.06 for IL-4-treated versus control). We conclude that IL-4 rapidly inhibited calcium transients. Because caffeine-stimulated transients were inhibited, IL-4 may act, at least in part, by depleting calcium stores. IL-4 inhibition of cholinergic signaling may be important for modulating ASM responses during inflammation.

Modelling the human immune response: can mice be trusted? Commentary

The mouse is now the animal of choice for laboratory-based medical research. Although its contribution to advancing understanding of our inner workings is indisputable, we should acknowledge that mice and humans are tangibly different. This article highlights, and attempts some rationale for, discrepancies between the two species' immune systems.

The effect of vaccination with DNA encoding murine T-cell epitopes on the Der p 1 and 2 induced immunoglobulin E synthesis

BACKGROUND

Immunization with naked plasmid DNA leads to strong and persistent cell-mediated and humoral immune response to plasmid encoded antigen. Vaccination of DNA encoded whole allergen has been tried, but little information is currently available on the efficacy of DNA encoding T-cell epitopes in allergic disease. The purpose of this study was to determine whether the vaccination of naked plasmid DNA encoding only T-cell epitopes suppresses the allergic reaction as effectively as naked DNA encoding whole segments of allergen.

METHODS

We immunized mice with a mixed naked plasmid DNA encoding the five classes of murine T-cell epitopes on Der p 1 and Der p 2 three times at weekly intervals via an intramuscular injection of BALB/c mice. Control mice were injected with the pcDNA 3.1 blank vector. After 3 weeks, the mice were actively sensitized twice and allowed to inhale the Der p extracts intranasally six times at weekly intervals.

RESULTS

The vaccinated mice showed a significant attenuated induction of Der p-specific immunoglobulin E synthesis compared to controls. In terms of the Der p-specific IgG2a antibody response, the vaccinated mice showed more prominent responses than the control mice group. In addition, analysis of the cytokine profile after Der p stimulation of the lymph-node cells revealed that the level of the mRNA expression of the interferon-gamma gene was higher in the vaccinated mice than in the controls. Histologic studies showed a much reduced infiltration of inflammatory cells in lung tissue of the gene-vaccinated mice in comparison with the controls.

CONCLUSIONS

These results suggest that vaccination with DNA encoding T-cell epitopes effectively inhibits allergen-induced IgE synthesis and reduces cell infiltration in lung tissue. Thus, gene therapy using T-cell epitope-encoding DNA presents an ideal way of combating allergic disease in the future.

Basophil recruitment and IL-4 production during human allergen-induced late asthma

BACKGROUND

Basophils represent an important source of inflammatory mediators and cytokines after IgE-dependent activation in human beings.

OBJECTIVE

To assess the role of basophils in allergic asthma, we measured the number of basophils in the bronchial mucosa and their capacity to express IL-4 mRNA and protein during allergen-induced late asthmatic responses.

METHODS

Fiberoptic bronchoscopic bronchial biopsies were obtained at 24 hours from sites of segmental bronchial allergen challenge and control sites in 19 patients with atopic asthma and 6 nonatopic healthy volunteers. Basophil numbers were assessed by immunohistochemistry through use of mAb 2D7. IL-4 mRNA--positive cells were detected through use of in situ hybridization and colocalized to basophils through use of sequential immunohistochemistry/in situ hybridization. IL-4 protein was detected and colocalized to basophils through use of dual immunohistochemistry.

RESULTS

After allergen challenge, there was an increase in the median number of 2D7-positive basophils per square millimeter in the bronchial mucosa in patients with asthma (0.9 cells/mm(2) at baseline to 8.8 cells/mm(2) after challenge; P =.002), which also was significantly higher than what was seen in nonasthmatic controls (P =.01). Similarly, IL-4 mRNA--positive cells were increased at 24 hours in patients with asthma (1.4 to 14) in comparison with controls (0 to 0; P =.02). Colocalization studies revealed that 15% and 41% of the basophil population in patients with asthma after allergen-challenge expressed, respectively, IL-4 mRNA and protein. Conversely, 19% of IL-4 mRNA-positive cells and 72% of IL-4 protein--positive cells were accounted for by basophils.

CONCLUSION

After allergen provocation in sensitive patients with atopic asthma, basophils are recruited to the bronchial mucosa and express IL-4 mRNA and protein, which might contribute to local IgE synthesis and/or tissue eosinophilia or other aspects of allergic inflammation during late responses and ongoing asthma.

Elevated soluble ST2 protein levels in sera of patients with asthma with an acute exacerbation

Previous studies have reported that ST2 is preferentially expressed on Th2 cells and plays a critical part in controlling airway inflammation in murine models of asthma. However, the clinical role of ST2 in patients with bronchial asthma remains unclear. In our study, we examined 56 patients with atopic asthma in a nonattack phase and 200 nonatopic normal volunteers for healthy control, and analyzed the relationship of their serum ST2 levels to asthma severity, pulmonary function, and laboratory data. Of the 56 patients with atopic asthma, 30 exhibited asthmatic exacerbation, and their serum ST2 levels were also analyzed. The serum ST2 levels were low, but a statistical difference was found between patients with nonattack asthma and the healthy control group (p < 0.05). We also found a differential rise of serum ST2 level that correlates well with the severity of asthma exacerbation. Furthermore, the serum ST2 levels during asthma exacerbation statistically correlated with the percentage of predicted peak expiratory flow (r = -0.634, p = 0.004) and Pa(CO(2)) (r = 0.516, p = 0.003). These results suggest that soluble human ST2 protein in sera may be related to Th2-mediated allergic inflammation inducing acute exacerbation in patients with atopic asthma.

The usefulness of competitive PCR: airway gene expression of IL-5, IL-4, IL-4δ2, IL-2, and IFNγ in asthma

BACKGROUND

Asthma has been described as an eosinophilic bronchitis driven by interleukin(IL)-4 and IL-5. The quantification of cytokine mRNA levels in airway samples has been confounded by housekeeping gene expression which differs between and within asthmatics and controls.

METHODS

The usefulness of competitive reverse transcriptase-polymerase chain reaction (RT-PCR) that is independent of housekeeping gene expression for quantitating the mRNA for interferon (IFN)γ, IL-2, IL-5, IL-4 and its receptor antagonist encoding splicing variant IL-4δ2 was determined in a cross sectional study of 45 normal control subjects and 111 with asthma.

RESULTS

Atopic controls and atopic asthmatic subjects expressed more IL-5 than non-atopic controls (p<0.02) in bronchoalveolar lavage (BAL) cells, but not in biopsy specimens. IL-5 mRNA expression in BAL cells from asthmatic subjects using inhaled corticosteroids (ICS) was significantly lower than those not receiving ICS (p=0.04). IL-2 mRNA levels differed with steroid use in biopsy specimens but not in BAL cells. IFNγ, IL-4, and IL-4δ2 mRNA levels did not differ between any groups and were not affected by steroid use. IL-4 and IL-4δ2 mRNA levels were positively correlated (p<0.0001), suggesting coordinated transcription.

CONCLUSIONS

While the signal differentiation of competitive PCR in asthma may rival that of in situ hybridisation and immunohistochemistry, the method is expensive and wasteful of material.

The usefulness of competitive PCR: airway gene expression of IL-5, IL-4, IL-4delta2, IL-2, and IFNgamma in asthma

BACKGROUND

Asthma has been described as an eosinophilic bronchitis driven by interleukin(IL)-4 and IL-5. The quantification of cytokine mRNA levels in airway samples has been confounded by housekeeping gene expression which differs between and within asthmatics and controls.

METHODS

The usefulness of competitive reverse transcriptase-polymerase chain reaction (RT-PCR) that is independent of housekeeping gene expression for quantitating the mRNA for interferon (IFN)gamma, IL-2, IL-5, IL-4 and its receptor antagonist encoding splicing variant IL-4delta2 was determined in a cross sectional study of 45 normal control subjects and 111 with asthma.

RESULTS

Atopic controls and atopic asthmatic subjects expressed more IL-5 than non-atopic controls (p<0.02) in bronchoalveolar lavage (BAL) cells, but not in biopsy specimens. IL-5 mRNA expression in BAL cells from asthmatic subjects using inhaled corticosteroids (ICS) was significantly lower than those not receiving ICS (p=0.04). IL-2 mRNA levels differed with steroid use in biopsy specimens but not in BAL cells. IFNgamma, IL-4, and IL-4delta2 mRNA levels did not differ between any groups and were not affected by steroid use. IL-4 and IL-4delta2 mRNA levels were positively correlated (p<0.0001), suggesting coordinated transcription.

CONCLUSIONS

While the signal differentiation of competitive PCR in asthma may rival that of in situ hybridisation and immunohistochemistry, the method is expensive and wasteful of material.

Cytokine profile of bronchoalveolar lavage-derived CD4(+), CD8(+), and gammadelta T cells in people with asthma after segmental allergen challenge

T cell-derived cytokines play an important role in the pathogenesis of allergic asthma, but little is known about the cytokine profile of their different subsets. The aim of the present study was to investigate the cytokine production potential of CD4(+), CD8(+), or gammadelta(+) T cells derived from the bronchoalveolar space of mild atopic asthmatic subjects (n = 11) and nonatopic control subjects (n = 9) before and 24 h after segmental allergen challenge. The cytokine production was determined using the technique of intracellular cytokine detection by flow cytometry. Comparing asthmatic with control subjects we found no difference in the percentage of CD4(+), CD8(+), or gammadelta T cells in the bronchoalveolar lavage fluid before and after allergen challenge. Before allergen challenge the proportion of cells producing the cytokines interferon (IFN)-gamma, interleukin (IL)-2, IL-4, IL-5, and IL-13 was not different in CD4(+) and CD8(+) cells. The major difference between the groups was an increased percentage of positive-staining cells for the T helper-(Th)2-cytokines IL-5 and IL-13 in the gammadelta T-cell subset. After allergen challenge, all T-cell subsets revealed a decreased proportion of cells producing the Th1-type cytokines IFN-gamma and IL-2. The percentage of IL-4- and IL-5-positive cells did not change in all subsets, and there was a decreased proportion of IL-13- positive cells in the CD4(+) subset. These findings indicate an increased Th2-cytokine profile in gammadelta T cells. After allergen challenge, the dysbalance between Th1 and Th2 cytokines was further accentuated by a reduction in Th1 cytokine-producing T cells.

Pathophysiological mechanisms of asthma. Application of cell and molecular biology techniques

Asthma is a common increasing and relapsing disease that is associated with genetic and environmental factors such as respiratory viruses and allergens. It causes significant morbidity and mortality. The changes occurring in the airways consist of a chronic eosinophilic and lymphocytic inflammation, together with epithelial and structural remodeling and proliferation, and altered matrix proteins, which underlie airway wall narrowing and bronchial hyperresponsiveness (BHR). Several inflammatory mediators released from inflammatory cells such as histamine and cysteinyl-leukotrienes induce bronchoconstriction, mucus production, plasma exudation, and BHR. Increased expression of T-helper 2 (Th2)-derived cytokines such as interleukin-4 and 5 (IL-4, 5) have been observed in the airway mucosa, and these may cause IgE production and terminal differentiation of eosinophils. Chemoattractant cytokines (chemokines) such as eotaxin may be responsible for the chemoattraction of eosinophils to the airways. The initiating events are unclear but may be genetically determined and may be linked to the development of a Th2-skewed allergen-specific immunological memory. The use of molecular biology techniques on tissues obtained from asthmatics is increasing our understanding of the pathophysiology of asthma. With the application of functional genomics and the ability to transfer or delete genes, important pathways underlying the cause if asthma will be unraveled. The important outcome of this is that new preventive and curative treatments may ensue.

Normally suppressing CD40 coregulatory signals delivered by airway macrophages to TH2 lymphocytes are defective in patients with atopic asthma

BACKGROUND

We have previously shown that airway macrophages (AMs) from atopic nonasthmatic subjects, but not atopic asthmatic subjects, inhibit T-cell IL-5 production during an allergen-dependent interaction. However, the mechanisms responsible for the IL-5-modulating effect of the AMs are less clear.

OBJECTIVES

The aim of the present study was to define the roles of B7 and CD40 costimulatory signals delivered by AMs in regulating T-cell IL-5 responses in an allergen-stimulated coculture system.

METHODS

Peripheral blood CD4(+) T cells and AMs were cocultured under different conditions.

RESULTS

Compared with those from well-matched atopic nonasthmatic subjects, AMs from atopic asthmatic subjects demonstrated a significantly lower expression of B7-1 and CD40, but not B7-2 and HLA-DR, after either fresh isolation or coculture with allergen-reactive CD4(+) T cells. Lower IL-12 production by the AMs from asthmatic subjects was also observed under the same conditions. Allergen-related T-cell IFN-gamma and IL-5 production was inhibited by the addition of either neutralizing B7-1 or B7-2 antibody to the cocultures in both atopic groups. In contrast, IL-5 production was significantly increased by the addition of blocking CD40 antibody, whereas IL-12 production by the AMs was inhibited. Anti-IL-12 mAb enhanced IL-5 production in the cocultures from atopic nonasthmatic subjects, whereas a dose-dependent suppressive effect of recombinant human IL-12 on IL-5 production was seen in atopic asthmatic subjects.

CONCLUSION

In this coculture model system, lower IL-12 production by AMs and higher IL-5 production by CD4(+) T cells in atopic asthmatic subjects compared with that found in atopic nonasthmatic subjects are related to the lower expression of CD40 rather than B7-1 signals on the AMs from these patients.

Local expression of epsilon germline gene transcripts and RNA for the epsilon heavy chain of IgE in the bronchial mucosa in atopic and nonatopic asthma

BACKGROUND

The demonstration of epsilon germline gene (Cepsilon) transcripts and mature mRNA for the epsilon heavy chain gene (Iepsilon) in the nasal mucosa suggested that IgE synthesis may occur in allergic rhinitis.

OBJECTIVE

In view of our previous demonstration of increases in IL-4 mRNA(+) cells in asthmatic subjects, we assessed whether local IgE synthesis may also be a feature of bronchial asthma.

METHODS

Fiberoptic bronchoscopic mucosa biopsy specimens were obtained from 9 atopic asthmatic subjects and 10 nonatopic normal (intrinsic) control subjects. To control for atopy, we also studied 9 nonatopic asthmatic subjects and 10 atopic nonasthmatic control subjects. Tissue was processed for immunohistochemistry for B cells (CD20) and in situ hybridization for Iepsilon and Cepsilon RNA(+) cells and IL-4 mRNA(+) cells.

RESULTS

B-cell numbers in the bronchial mucosa were similar for asthmatic subjects compared with control subjects, whereas significantly higher numbers of Iepsilon RNA(+) (P =.02 and P =.04, respectively), Cepsilon RNA(+) (P =.01 and P =.03, respectively), and IL-4 mRNA(+) (P =.001 and P =.001, respectively) cells were observed in atopic asthmatic subjects and nonatopic asthmatic subjects, respectively, but not in atopic control subjects compared with nonatopic control subjects. In asthmatic subjects there were significant correlations between Iepsilon RNA(+) cells (r = 0.54, P =.02) and Cepsilon RNA(+) cells (r = 0.48, P =.05) when compared with the number of IL-4 mRNA(+) cells.

CONCLUSION

Increases in Iepsilon and Cepsilon RNA(+) cells, but not B-cell numbers, in the bronchial mucosa provide evidence for local IgE synthesis in both atopic and nonatopic asthma. These changes appear to relate to asthma rather than atopy per se and, at least in part, may be under the regulation of IL-4.

Regulated production of the T helper 2-type T-cell chemoattractant TARC by human bronchial epithelial cells in vitro and in human lung xenografts

The chemokine TARC is a ligand for the chemokine receptor CCR4 expressed on T helper (Th)2-type CD4 T cells. Allergic airway inflammation is characterized by a local increase in cells secreting Th2-type cytokines. We hypothesized that bronchial epithelial cells may be a source of chemokines known to chemoattract Th2 cells. Regulated TARC expression was studied using normal human bronchial epithelial cells and a human lung xenograft model. TARC expression was increased in normal human bronchial epithelial cells in response to tumor necrosis factor-alpha stimulation, and further upregulation of TARC was observed with interferon (IFN)-gamma but not interleukin (IL)-4 costimulation. TARC functions as a nuclear factor (NF)-kappa B target gene, as shown by the abrogation of TARC expression in response to proinflammatory stimuli when NF-kappa B activation is inhibited. In an in vivo model, minimal constitutive TARC expression was observed in human lung xenografts. Consistent with our findings in vitro, TARC messenger RNA (mRNA) expression was upregulated in the xenografts in response to IL-1, and costimulation with IFN-gamma but not IL-4 further increased TARC mRNA and protein expression. In addition, bronchoalveolar lavage fluid from asthmatic subjects after allergen challenge contained significantly increased levels of TARC, suggesting that TARC production by bronchial epithelial cells may play a role in the pathogenesis of allergic asthma.

TH2 cytokine-associated transcription factors in atopic and nonatopic asthma: evidence for differential signal transducer and activator of transcription 6 expression

BACKGROUND

The expression of IL-4 and IL-5 is increased in patients with atopic asthma compared with control subjects and correlates with indices of pulmonary function. In nonatopic asthma the expression of IL-4, unlike IL-5, fails to correlate with pulmonary function, and compared with their atopic counterparts, these patients have fewer cells expressing IL-4 receptor (IL-4R). As such, a deficiency in the IL-4 signaling pathway may be implicated in nonatopic asthma. The transcription factors GATA-3 and cMAF mediate IL-4 and IL-5 synthesis, whereas signal transducer and activator of transcription 6 (STAT-6) is critical for IL-4R signaling.

OBJECTIVE

This study examines the expression profile of these transcription factors in asthma, according to atopic status.

METHODS

With immunocytochemistry, the expression of GATA-3, cMAF, and STAT-6 protein was determined in sections of bronchial biopsy specimens from patients with atopic asthma (n = 7), patients with nonatopic asthma (n = 8), and control subjects (n = 8).

RESULTS

Higher numbers of cells expressing GATA-3 and cMAF were observed in patients with atopic and those with nonatopic asthma than in control subjects and patients with tuberculosis (P <.001). There were also more STAT-6-immunoreactive cells in patients with atopic and those with nonatopic asthma than in control subjects (P <.0001, P <.05). Notably, however, fewer cells expressing STAT-6 protein were observed in nonatopic versus atopic asthma (P <.0001).

CONCLUSIONS

These results demonstrate the upregulation of GATA-3 and cMAF in both variants of asthma and indicate that reduced IL-4R signaling, because of lower STAT-6 expression, may be a feature of nonatopic asthma.

Persistent airflow limitation in adult-onset nonatopic asthma is associated with serologic evidence of Chlamydia pneumoniae infection

BACKGROUND

Persistent airflow limitation may develop in patients with asthma, particularly in adults with nonatopic (intrinsic) disease. Although the underlying mechanisms are still unknown, respiratory infections might be involved.

OBJECTIVE

We investigated the annual loss of lung function in relation to seropositivity to Chlamydia pneumoniae in different subgroups of patients with severe asthma according to age at onset of asthma and atopic status.

METHODS

One hundred one nonsmoking outpatients with a pulmonologist's diagnosis of severe asthma (32 men and 69 women; mean age, 46.0 years; range, 18-75 years) were included in a cross-sectional study. C pneumoniae-specific serum IgG and IgA were measured by means of ELISA. The estimated decline in lung function was calculated from the relationship between postbronchodilator FEV(1)/vital capacity (percent predicted) and the duration of asthma and expressed as the slope of the regression line.

RESULTS

Patients with adult-onset nonatopic asthma and positive IgG antibodies to C pneumoniae had a significantly steeper slope of the regression line compared with the other subgroups of asthmatic patients (P =.001), being indicative of a 4-fold greater estimated decline in postbronchodilator FEV(1)/vital capacity (2.3% vs 0.5% predicted per year of asthma duration).

CONCLUSION

These results suggest that C pneumoniae infection might promote the development of persistent airflow limitation in patients with nonatopic adult-onset asthma. It remains to be established whether viable pathogens that are accessible for therapeutic intervention are still present in the lower airways.

New anti-asthma therapies: suppression of the effect of interleukin (IL)-4 and IL-5

Asthma is currently defined as a chronic inflammatory disorder of the airways. The central role of allergen-specific Th2 cells in the regulation of this mucosal airway inflammation has been highlighted. Hence, there is large interest in the therapeutic potential of an anti-Th2 cell approach. One of the strategies which has been developed, is to inhibit the effect of interleukin (IL)-4 or IL-5, two main Th2 cell derived cytokines. Interleukin-4 is pivotal in the pathogenesis of allergic disorders through its wide range of effects. An important observation, especially during secondary antigen exposure, is the possible redundancy with IL-13. Both cytokines share common elements in their receptor and intracellular signalling pathway. As a result, compounds can be developed that selectively inhibit the effect of either IL-4 or IL-13, or alternatively, by interfering with the common pathway, inhibit the effect of both cytokines. Eosinophils are generally seen as a particularly harmful element in the allergic inflammation. The importance of IL-5 on eosinophil biology has clearly been established. Conversely, in man, the biological effects of IL-5 are largely limited to eosinophil function. Therefore, IL-5 antagonists offer the unique opportunity of selectively neutralizing the effect of eosinophils. Several strategies have now been developed that successfully inhibit the biological effect of interleukin-4 or interleukin-5. Some of these compounds have proven to be biologically active in man. The challenge now is to establish their therapeutic role in asthma.

Chemokine-induced cutaneous inflammatory cell infiltration in a model of Hu-PBMC-SCID mice grafted with human skin

Recently, certain chemokines and chemokine receptors have been preferentially associated with the selective recruitment in vitro of type 1 T cells, such as IP-10 and its receptor CXCR3, or type 2 T cells such as monocyte-derived chemokine (MDC) and eotaxin and their receptors CCR4 and CCR3. Very few models have provided confirmation of these findings in vivo. Taking advantage of the humanized SCID mouse model grafted with autologous human skin, the ability of the chemokines IP-10, MDC, eotaxin, and RANTES to stimulate cell recruitment was investigated. Intradermal IP-10 injection resulted in an influx of CD4+ T lymphocytes but also surprisingly in the recruitment of dendritic cells. MDC recruited mainly CD8+ T lymphocytes, and had little effect on eosinophils. As predicted, eotaxin was a potent inducer of eosinophil and basophil migration, also recruiting CD4+ T cells. RANTES, a ubiquitous chemokine associated with both type 1 and type 2 profiles, was able to recruit all cell types. CXCR3-positive cells were preferentially recruited by IP-10, whereas CCR3- and CCR4-positive cells were predominantly found after injection of eotaxin and MDC. Thus, in a human environment in vivo, some chemokines have the ability to recruit cells expressing chemokine receptors preferentially expressed on type 1 or type 2 cells. Further investigations revealed that MDC and eotaxin induced the recruitment of type 2, but not type 1, cytokine-producing cells. RANTES, on the other hand, induced the migration of both type 1 and type 2 cytokine-secreting cells, whereas IP-10 did not induce the recruitment of either subtype. These studies provide detailed information on the properties of MDC, eotaxin, IP-10, and RANTES as chemotactic molecules in skin in vivo. The use of the humanized SCID mouse model grafted with human skin is validated as a useful model for the evaluation of chemokine function in the inflammatory reaction, and suggests that therapeutic targeting of certain chemokines might be of interest in diseases associated preferentially with a type 1 or type 2 profile.

Th type 1-stimulating activity of lung macrophages inhibits Th2-mediated allergic airway inflammation by an IFN-gamma-dependent mechanism

In the mucosal immune system, resident dendritic cells are specialized for priming Th2-polarized immunity, whereas the Ag-presenting activity of macrophages has been linked with the development of Th1 phenotype. As an immune switch toward Th1 can protect against Th2-mediated allergic response, this study investigated the capacity of lung macrophages to stimulate Th1 responses during the secondary exposure to inhaled allergen, thereby suppressing Th2-mediated allergic airway inflammation in a murine model of allergic asthma. Following airway macrophage depletion in OVA-sensitized mice, lung T cells defaulted to a phenotype that produced less Th1 (IFN-gamma) and more Th2 (IL-4 and IL-5) cytokines, leading to more severe airway hyperreactivity and inflammation after intranasal Ag challenge. After OVA pulsing and adoptive transfer, lung macrophages selectively promoted a Th1 response in Ag-sensitized recipients and did not induce pulmonary eosinophilia. By contrast, OVA pulsing and adoptive transfer of a lung cell preparation, consisting of dendritic cells, B cells, and macrophages, promoted a Th2 response with an associated inflammatory response that was suppressed when macrophages were present and pretreated with IFN-gamma, but exacerbated when macrophages were depleted before IFN-gamma treatment. In addition, Th1-promoting activity of lung macrophages was not related to the autocrine production of IL-12p40. These results suggest that the Th1-promoting APC activity may be an inherent property of the lung macrophage population, and may play an important role, upon stimulation by IFN-gamma, in antagonizing an ongoing Th2 immunity and Th2-dependent allergic responses.

Cytokine production from peripheral whole blood in atopic and nonatopic asthmatics: relationship with blood and sputum eosinophilia and serum IgE levels

BACKGROUND

The cytokine network is thought to be essential in orchestrating airway inflammation in asthma. Although evidence has accumulated to suggest that atopic asthma is a Th2 disease, much less is known about nonatopic asthma.

METHODS

We have compared the production of IL-4, IL-6, IFN-gamma, and TNF-alpha from peripheral blood leukocytes between atopic (n=21) and nonatopic (n=22) asthmatics and healthy nonatopic subjects (n=20). Peripheral blood was incubated for 24 h either without stimulus or with LPS or PHA. Cytokines were measured by the immunotrapping technique (Dynamic Immunoassay).

RESULTS

When compared to healthy nonatopic subjects, both atopic and nonatopic asthmatics showed increased blood and sputum eosinophilia associated with raised total serum IgE levels. Similarly, both asthma groups displayed spontaneous, endotoxin-induced overproduction of IL-6. Enhanced spontaneous, endotoxin-induced release of IL-4 combined with reduced spontaneous IFN-gamma production was seen only in atopic asthma. In this group of patients, the production of IL-4 was related to the extent of blood and sputum eosinophilia. In nonatopic asthmatics, serum levels of IgE were inversely related to the production of IFN-gamma.

CONCLUSIONS

Both atopic and intrinsic asthma display raised blood and airway eosinophilia, raised total serum IgE, and overproduction of IL-6 from peripheral blood. Atopic asthma is also characterized by impaired spontaneous release of IFN-gamma and increased production of IL-4 that correlates with the magnitude of eosinophilic inflammation.

Inflammation and structural changes in the airways of patients with atopic and nonatopic asthma. BHR Group

The aim of the present study was to compare the cellular pattern and structural changes in the airway walls of atopic and nonatopic patients with asthma. Bronchial biopsy specimens were obtained from 13 atopic subjects with asthma, nine nonatopic patients with asthma, and seven healthy control subjects and investigated using immunohistochemical methods. The number of eosinophils increased in both asthma groups, but significantly more in the atopic group. The number of mast cells increased similarly in the two asthma groups, whereas the number of neutrophils increased only in the nonatopic asthma group. The number of T-lymphocytes (CD3-, CD4-, CD8-, CD-25-positive cells) was higher in patients with atopic asthma compared with nonatopic asthma. Interleukin-4 (IL-4) and IL-5-positive cells were more frequently found in the atopic asthma group, whereas cells staining for IL-8 were more frequent in the nonatopic group. The degree of epithelial damage was significantly higher in the atopic asthma group compared with the control subjects and the nonatopic asthmatics. The tenascin and laminin layer was significantly thicker in the atopic group compared with the group of nonatopic asthmatics. In the atopic group, there was a significant negative correlation between epithelial integrity (defined as the relative length of intact epithelium) and the eosinophil count and also between the number of CD25-positive cells and epithelial integrity. The number of mast cells correlated positively with the thickness of tenascin- and laminin-positive layers. In conclusion, we provide evidence of different patterns of involvement of inflammatory cells in atopic and nonatopic patients with asthma. There were also structural differences in the bronchial mucous membrane between atopic asthma and nonatopic asthma. This suggests that there are differences in the extent of the immunopathologic response of these clinically distinct forms of asthma.

Prostaglandin E2 selectively enhances the IgE-mediated production of IL-6 and granulocyte-macrophage colony-stimulating factor by mast cells through an EP1/EP3-dependent mechanism

PGE(2) is an endogenously synthesized inflammatory mediator that is over-produced in chronic inflammatory disorders such as allergic asthma. In this study, we investigated the regulatory effects of PGE(2) on mast cell degranulation and the production of cytokines relevant to allergic disease. Murine bone marrow-derived mast cells (BMMC) were treated with PGE(2) alone or in the context of IgE-mediated activation. PGE(2) treatment alone specifically enhanced IL-6 production, and neither induced nor inhibited degranulation and the release of other mast cell cytokines, including IL-4, IL-10, IFN-gamma, and GM-CSF. IgE/Ag-mediated activation of BMMC induced the secretion of IL-4, IL-6, and GM-CSF, and concurrent PGE(2) stimulation synergistically increased mast cell degranulation and IL-6 and GM-CSF, but not IL-4, production. A similar potentiation of degranulation and IL-6 production by PGE(2), in the context of IgE-directed activation, was observed in the well-established IL-3-dependent murine mast cell line, MC/9. RT-PCR analysis of unstimulated MC/9 cells revealed the expression of EP(1), EP(3), and EP(4) PGE receptor subtypes, including a novel splice variant of the EP(1) receptor. Pharmacological studies using PGE receptor subtype-selective analogs showed that the potentiation of IgE/Ag-induced degranulation and IL-6 production by PGE(2) is mediated through EP(1) and/or EP(3) receptors. Our results suggest that PGE(2) may profoundly alter the nature of the mast cell degranulation and cytokine responses at sites of allergic inflammation through an EP(1)/EP(3)-dependent mechanism.

Expression of eotaxin in induced sputum of atopic and nonatopic asthmatics

BACKGROUND

The chemokine eotaxin has been implicated in airway eosinophilia in atopic asthma. We have compared airway eosinophils and eotaxin expression in induced sputum from well-matched atopic and nonatopic asthmatics.

METHODS

Eosinophil numbers, eosinophil cationic protein (ECP), and the expression of eotaxin were examined in induced sputum from atopic asthmatics (AA = 11), nonatopic asthmatics (NAA = 11), and atopic (AC = 12) and normal (NC = 10) controls. Slides were prepared for differential cell counts by Romanowsky stain, and ECP levels were measured by RIA. Eotaxin expression was detected by in situ hybridization, with 35S-labelled riboprobes and immunocytochemistry.

RESULTS

The numbers of eosinophils and ECP concentration were increased in the sputum of AA and NAA compared with AC and NC (P < 0.05). The numbers of eotaxin mRNA+ and immunoreactive cells were increased in NAA, but not AA, when compared with controls (P < 0.05). Eotaxin immunoreactive cells in NAA were significantly higher than in AA (P < 0.05). Eotaxin was expressed predominantly by macrophages, eosinophils, and epithelial cells. In NAA, but not AA, the numbers of eotaxin mRNA+ cells were correlated with histamine PC20 (r = -0.81, P < 0.01) and eosinophil numbers in sputum (r = 0.7, P < 0.05).

CONCLUSIONS

Eotaxin production by macrophages, eosinophils, and epithelial cells may play a more pronounced role in airway eosinophilia in nonatopic than in atopic asthma.

Reduced production of interleukin 12 by interferon gamma primed alveolar macrophages from atopic asthmatic subjects

BACKGROUND

Asthma is characterised pathologically by an inflammatory pulmonary infiltrate rich in T helper (Th) 2 cells and eosinophils. Interleukin (IL)-12 is a heterodimeric cytokine critical for driving the development of uncommitted Th cells to express a Th 1 phenotype. Reduced pulmonary production of IL-12 may therefore play a role in the pathogenesis of asthma by contributing to the pulmonary cytokine imbalance seen in asthma.

METHODS

IL-12 p70 protein levels in bronchoalveolar lavage fluid and p70 protein levels and IL-12 messenger RNA in alveolar macrophage cultures from normal and atopic asthmatic subjects were measured.

RESULTS

There was a significant difference between the mean IL-12 p70 protein level in the bronchoalveolar lavage fluid from asthmatic subjects (37.5 pg/ml) and from normal subjects (131 pg/ml, p = 0.04). Alveolar macrophages from asthmatic subjects produced significantly less IL-12 protein (30 pg/ml) and messenger RNA than those from normal subjects (69.5 pg/ml, p<0.005). These differences were not caused by inhibition of IL-12 production by IL-10 nor to generalised hyporesponsiveness of asthmatic alveolar macrophages from subjects to the effects of interferon (IFN)-gamma.

CONCLUSIONS

Pulmonary IL-12 production is lower in asthmatic subjects. This reduction is not the result of generalised hyporesponsiveness to IFN-gamma. Reduced IL-12 levels may contribute to the development of asthmatic pulmonary inflammation through dysregulation of Th cell development.

Macrophage subpopulations and macrophage-derived cytokines in sputum of atopic and nonatopic asthmatic subjects and atopic and normal control subjects

BACKGROUND

Previous studies have shown a prominent macrophage signal in the bronchial mucosa from nonatopic (intrinsic) compared with atopic (extrinsic) asthmatic subjects. This observation might have represented an expansion of a proinflammatory macrophage population or a homeostatic mechanism to decrease T(H)2-type inflammation.

OBJECTIVE

The aim of the study was to investigate the numbers of macrophages and macrophage subpopulations and the expression of IL-10 and IL-12 in sputum from asthmatic and control subjects.

METHODS

Eight atopic asthmatic (AA) subjects, 10 nonatopic asthmatic (NAA) subjects, 6 atopic control (AC) subjects, and 7 normal control (NC) subjects underwent sputum induction. Macrophages were enumerated by using Romanowsky stain and immunocytochemistry (CD68). RFD1 (interdigitating cell marker) and RFD7 (mature phagocyte marker) mAbs were used for immunocytochemical phenotyping, whereas IL-10 and IL-12 messenger (m)RNA was examined with in situ hybridization by using (35)S-labeled riboprobes. The phenotype of cells expressing IL-10 or IL-12 mRNA was examined by simultaneous in situ hybridization and immunostaining.

RESULTS

No differences in the numbers of CD68(+) macrophages and RFD1(+), RFD7(+), and RFD1(+)/RFD7(+) subpopulations were found between AA, NAA, AC, and NC subjects. However, the numbers of IL-10 and IL-12 mRNA(+) cells were increased in AA subjects compared with NAA, AC, and NC subjects (P <.05). No other differences were found among the groups. Most of the IL-10 and IL-12 mRNA(+) cells in sputum from asthmatic subjects were macrophages (>80%), with less than 10% of mRNA colocalizing to epithelial cells.

CONCLUSIONS

Sputum macrophage numbers, unlike tissue macrophages, as previously reported, were not elevated in NAA subjects. Increased IL-10 and IL-12 expression in atopic asthma may indicate the existence of a homeostatic mechanism to decrease lung inflammation. The lack of such cytokines in intrinsic asthma may predispose to bronchial inflammation in these subjects.

Cytokine profile in minor salivary glands from patients with bronchial asthma

BACKGROUND

T lymphocytes are important components of the bronchial inflammatory cell infiltrate in asthma. Because lymphocytes activated in the respiratory tract recirculate to remote glandular and mucosal sites, we previously studied the histologic features of minor salivary glands (MSGs) in bronchial asthma and found an airway-like inflammation with T-lymphocyte infiltration, the presence of mast cells that were often degranulated, and basement membrane thickening but no eosinophil infiltration.

OBJECTIVE

We sought to investigate the cellular infiltration and cytokine profile in MSGs from untreated asthmatic subjects, steroid-treated asthmatic subjects, and control subjects and to compare these values with those found in bronchial biopsy specimens.

METHODS

The cellular infiltration was studied by using immunohistochemistry. Cytokine messenger (m)RNA expression for IL-4, IL-5, and IFN-gamma was determined by using in situ hybridization and cytokine immunoreactivity with immunohistochemistry.

RESULTS

A significant increase in CD4 and IL-4 mRNA(+) cells was observed in MSGs from asthmatic patients (both untreated and steroid-treated subjects) when compared with control subjects, which correlated with the clinical severity of asthma (FEV(1) and Aas score). In contrast to the bronchi, no IL-5 mRNA expression was observed in MSGs, and no difference was observed for MSG IFN-gamma mRNA between the groups. At the level of MSG protein expression, the 3 cytokines were seen, with a significant increase in IL-4 protein expression in steroid-treated asthmatic subjects compared with untreated asthmatic subjects and control subjects, but there were no differences between the groups in IL-5 and IFN-gamma protein expression.

CONCLUSION

The cytokine mRNA expression pattern observed in the MSGs of asthmatic subjects was different from that found in the bronchi, suggesting a different local immune regulation.

Macrophage migration inhibitory factor (MIF) in bronchial asthma

BACKGROUND

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine favouring the secretion of TNFalpha and IL-8 and counteracts anti-inflammatory effects of corticosteroids. Airways inflammation is a central feature of bronchial asthma and is characterized by the accumulation of eosinophils.

OBJECTIVE

The aim of this study was to investigate whether MIF is related to asthma symptoms and eosinophil accumulation in the airways.

METHODS

Serum MIF levels were measured by an enzyme-linked immunosorbent assay in 44 healthy subjects and 44 asthmatics. Levels of MIF in induced sputum were measured in 10 healthy subjects and 15 asthmatics. Levels of eosinophil cationic protein (ECP) in induced sputum were measured by a radioimmunosorbent assay. Fluorescence double immunostaining was conducted to examine cellular source and localization of MIF.

RESULTS

Serum MIF levels were significantly increased in asthmatic patients compared with age and sex-matched control subjects. Symptomatic patients had a higher MIF level than asymptomatic patients. Induced sputum obtained from asthmatics contained higher levels of MIF than those from control subjects. MIF levels in induced sputum were correlated with ECP levels in induced sputum. MIF was colocalized with eosinophil peroxidase staining in the cytoplasm of sputum cells.

CONCLUSION

Increased MIF levels are associated with asthma symptoms and one of the cellular sources of MIF in the airways are eosinophils.

Autocrine cytokine signaling mediates effects of rhinovirus on airway responsiveness

The airway responses to allergen exposure in allergic asthma are qualitatively similar to those elicited by specific viral respiratory pathogens, most notably rhinovirus (RV), suggesting that the altered airway responsiveness seen in allergic asthma and that elicited by viral respiratory tract infection may share a common underlying mechanism. To the extent that T helper cell type 2 (Th2) cytokines have been implicated in the pathogenesis of allergic asthma, this study examined the potential role(s) of Th2-type cytokines in mediating pro-asthmatic-like changes in airway smooth muscle (ASM) responsiveness after inoculation of naive ASM with human RV. Isolated rabbit ASM tissues and cultured human ASM cells were exposed to RV (serotype 16) for 24 h in the absence and presence of monoclonal blocking antibodies (MAbs) or antagonists directed against either the Th2-type cytokines interleukin (IL)-4 and IL-5, intercellular adhesion molecule (ICAM)-1 (the endogenous host receptor for most RVs), or the pleiotropic proinflammatory cytokine IL-1beta. Relative to control (vehicle-treated) tissues, RV-exposed ASM exhibited significantly enhanced isometric contractility to acetylcholine and impaired relaxation to isoproterenol. These pro-asthmatic-like changes in ASM responsiveness were ablated by pretreating the RV-exposed tissues with either IL-5-receptor-alpha blocking antibody or human recombinant IL-1-receptor antagonist, whereas IL-4 neutralizing antibody had no effect. Extended studies further demonstrated that inoculation of ASM cells with RV elicited 1) an increased mRNA expression and release of IL-5 protein, which was inhibited in the presence of anti-ICAM-1 MAb, and 2) an enhanced release of IL-1beta protein, which was inhibited in the presence of IL-5 receptor-alpha antibody. Collectively, these observations provide new evidence demonstrating that RV-induced changes in ASM responsiveness are largely attributed to ICAM-1-dependent activation of a cooperative autocrine signaling mechanism involving upregulated IL-5-mediated release of IL-1beta by the RV-exposed ASM itself.

Assessment of the Th1/Th2 paradigm in whole blood in atopy and asthma. Increased IFN-gamma-producing CD8(+) T cells in asthma

Atopy is characterized by an immune system that is biased to T helper cell, type 2 (Th2) activation. This condition predisposes to asthma, a disease in which a Th2 activation was found in blood and lungs. However, most blood studies have considered purified cells, which might give an incomplete view of immune reactions. In this study, we assessed in whole blood cultures the Th1/Th2 paradigm in atopy and asthma. Sixty-nine subjects (31 atopic asthmatics, six nonatopic asthmatics, 13 atopic nonasthmatics, and 19 control subjects) were included in this study. Interleukin-4 (IL-4), interferon gamma (IFN-gamma), and IL-12 were assayed in stimulated whole blood culture supernatants by using a flow cytometer microsphere-based assay. Intracellular IL-4 and IFN-gamma were detected in T cells and CD8(+) T cells by flow cytometry. Atopy was characterized by a higher production of IL-4, which was correlated to total IgE levels, and by an impairment of the T-cell capacity to produce IFN-gamma. This impairment was correlated to the number of positive skin tests. In asthma, the overproduction of IL-4 was still found if atopy was present. Unexpectedly, an overproduction of IFN-gamma was found, which was related to an increased capacity of CD8(+) T cells to produce IFN-gamma. The number of IFN-gamma-producing CD8(+) T cells was related to asthma severity, to bronchial hyperresponsiveness, and to blood eosinophilia. In addition, this number was correlated to IL-12 production. These results show that in addition to the well-known Th2 inflammation in asthma, there are IFN-gamma-producing CD8(+) T cells in the blood, possibly controlled by IL-12.

Advances in immunopharmacology of asthma

Asthma is a chronic inflammatory disease characterized by airway hyperresponsiveness and recurrent reversible airway obstruction. As there appears to be a preponderance of T-helper 2 (Th2) cells over Th1 cells in asthma, more attention has been focused on the role of Th2-derived cytokines such as interleukin (IL)-4 and IL-5 and their corresponding signaling pathways in the pathophysiology of the disease. These complex pathways may involve the activation of signal transducers and activators of transcription (STATs) and nuclear factor-kappaB (NF-kappaB). On the other hand, immunoglobulin (Ig) E-mediated mechanisms and the protein tyrosine kinase signaling cascade are important in triggering the release of mediators from inflammatory cells. In spite of all of these, host regulatory mechanisms exist to limit the inflammation. An increase in the 3', 5'-cyclic adenosine monophosphate (cAMP) level generally suppresses the activities of immune and inflammatory cells, and the level of cAMP is closely regulated by a family of phosphodiesterases (PDEs). Heparin, a glycosaminoglycan released exclusively from mast cells, also is believed to possess anti-inflammatory actions. Many new therapeutic agents have been developed either to attenuate the pro-inflammatory processes in asthma or to augment the host anti-inflammatory mechanisms. In this article, we discuss the immunopharmacology of several of these agents, which include heparin and inhibitors of PDEs, tyrosine kinases, and NF-kappaB, as well as antibodies and soluble receptors directed against IgE, IL-4, and IL-5.

The pathology of chronic asthma

Our understanding of the pathophysiology of asthma has undergone great advances in the past decade, particularly with the recognition of cytokines and the roles they may take in orchestrating the local immune response. With this information, it has been possible to target new therapeutic entities such as cytokine or chemokine receptors. Eosinophils and T lymphocytes have a special place in the inflammatory and structural alterations contributing to the asthmatic diathesis. It is possible that phenotype subsets of these cells exist and they hold the key to perpetuation of immunologic and physiologic abnormalities in asthma.

Comparison of the structural and inflammatory features of COPD and asthma. Giles F. Filley Lecture

At least three conditions contribute to COPD. (1) Chronic bronchitis (mucous hypersecretion) is an inflammatory condition in which CD8+ T-lymphocytes, neutrophils, and CD68+ monocytes/macrophages predominate. The condition is defined clinically by the presence of chronic cough and recurrent increases in bronchial secretions sufficient to cause expectoration. There is enlargement of mucus-secreting glands and goblet cell hyperplasia, which can occur in the absence of airflow limitation. (2) Adult chronic bronchiolitis (small or peripheral airways disease) is an inflammatory condition of small bronchi and bronchioli in which there are predominantly CD8+ and pigmented macrophages. The functional defect is difficult to detect clinically but may be recognized by sophisticated tests of small airway function. There is mucous metaplasia, enlargement of the mass of bronchiolar smooth muscle, and loss of alveolar attachments. (3) Emphysema is an inflammatory condition of the alveoli in which T-lymphocytes, neutrophils, and pigmented alveolar macrophages are involved, associated with the release of excessive amounts of elastases. It is defined anatomically by permanent, destructive enlargement of airspaces distal to terminal bronchioli without obvious fibrosis. In contrast, asthma is a clinical syndrome characterized by allergic inflammation of bronchi and bronchioli in which CD4+ (helper) T-lymphocytes and eosinophils predominate. There is increased production and release of interleukin (IL)-4 and IL-5, which is referred to as a Th2-type response. There is usually increased tracheobronchial responsiveness to a variety of stimuli, and the condition is usually manifest as variable airflow obstruction. While differences between COPD and asthma have been highlighted, new data are emerging that indicate there may also be similarities.

Eosinophils are a feature of upper and lower airway pathology in non-atopic asthma, irrespective of the presence of rhinitis

BACKGROUND

Asthma and rhinitis often co-exist and there are data to suggest that they may be two ends of the same disease spectrum. Immunohistochemical studies have shown that eosinophilia in the airways is a feature of rhinitic patients without asthma.

OBJECTIVE

The aim of our study was to examine whether cellular infiltration exists in the nasal mucosa of asthmatics even in the absence of symptoms and signs of rhinitis.

METHODS

Nasal mucosa biopsies were taken from 27 non-atopic subjects and comprised nine asthmatic rhinitic patients (AR), eight asthmatic non-rhinitic patients (ANR) and 10 healthy control subjects (N). Bronchial mucosa biopsies were also taken simultaneously from some of the patients (n = 10) to determine whether there was an association between cellular infiltration in the nose and the lungs. The alkaline phosphatase-anti-alkaline phosphatase (APAAP) method was used on 6 microm thick cryostat sections using monoclonal antibodies against T cells (CD4, CD8), eosinophils (EG2) and mast cells (mast cell tryptase). Slides were counted blind and results expressed as cells per field.

RESULTS

The results showed that eosinophil counts were higher in both asthma groups compared with control nasal biopsies (median values AR 8.3, ANR 9.2, N 2.1 cells per field, P < 0.01). Furthermore, there was a significant correlation between eosinophil cell counts in the nose and the airways (r = 0.851 P < 0.001). No differences in eosinophil numbers were detected between the two groups of asthmatics. Also, no differences were noted for any other cell type (i.e. CD4, CD8, tryptase) among the three study groups.

CONCLUSIONS

These results show that eosinophil infiltration was present in the nasal mucosa of asthmatic patients even in the absence of rhinitis, and add further support to the hypothesis that asthma and rhinitis are clinical expressions of the same disease entity.