Cytokines. 3. Cytokines in asthma

CREB regulates TNF-α-induced GM-CSF secretion via p38 MAPK in human lung fibroblasts

BACKGROUND

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine that mediates eosinophilic differentiation, migration and survival, causing respiratory tract inflammation. GM-CSF is also known to be secreted from respiratory tract structural cells. However, the mechanisms of GM-CSF secretion have not been well established.

METHODS

Human fetal lung fibroblasts and human primary asthmatic lung fibroblasts were used for the study of tumor necrosis factor alpha (TNF-α)-induced GM-CSF secretion. GM-CSF secretion and mRNA expression were measured by enzyme-linked immunosorbent assay and quantitative real-time reverse transcription polymerase chain reaction, respectively. Knockdown of cAMP response element-binding protein (CREB) in fibroblasts was carried out by using specific small interfering RNAs of CREB.

RESULTS

Among respiratory tract structural cells, pulmonary fibroblasts exhibited increased GM-CSF secretion and mRNA expression after stimulation with TNF-α in a concentration-dependent manner. Moreover, a p38 mitogen-activated protein kinase (MAPK) inhibitor controlled TNF-α-induced GM-CSF secretion, and roflumilast and rolipram, inhibitors of phosphodiesterase-4, suppressed TNF-α-induced GM-CSF secretion. Consistent with this, forskolin also completely blocked GM-CSF secretion, and similar results were observed in response to cAMP treatment, suggesting that cAMP signaling suppressed TNF-α-induced GM-CSF secretion in human lung fibroblasts. Furthermore, CREB was phosphorylated through p38 MAPK but not cAMP signaling after TNF-α stimulation, and GM-CSF secretion was inhibited by CREB knockdown. Finally, these effects were also demonstrated in human primary lung fibroblasts in a patient with asthma.

CONCLUSIONS

CREB signaled independent of cAMP signaling and was phosphorylated by p38 MAPK following TNF-α stimulation, playing a critical role in GM-CSF secretion in human lung fibroblasts.

Airway IFN-γ production during RSV bronchiolitis is associated with eosinophilic inflammation

STUDY OBJECTIVE

This study was designed to investigate the possible role of IFN-γ in eosinophil degranulation that occurs during respiratory syncytial virus (RSV) bronchiolitis.

METHODS

Sixty-seven infants, 2-24 months old and hospitalized with their first episode of acute RSV bronchiolitis, were selected for this study. Eosinophil-active cytokine and chemokine profiles in nasal lavage supernatants taken within the first 48 h of admission were determined by a multiplex bead array system (Luminex). Comparisons were made with control (Control group) subjects (n = 20).

RESULTS

Nasal IFN-γ levels were significantly higher (P < 0.0001) in RSV bronchiolitis (median = 4.4 pg/ml) infants compared to controls (0.0 pg/ml). IFN-γ levels correlated significantly with the levels of nasal eotaxin (r = 0.566, P < 0.0001), RANTES (r = 0.627, P < 0.0001), GM-CSF (r = 0.849, P < 0.0001), and EDN (r = 0.693, P < 0.001). Nasal interleukin (IL)-4, IL-5, and IL-13 were below sensitivity levels in most RSV bronchiolitis and control subjects.

CONCLUSION

These results suggest that IFN-γ may play an important role in eosinophilic inflammation in RSV bronchiolitis.

Adaptive cytokine production in early life differentially predicts total IgE levels and asthma through age 5 years

BACKGROUND

Although it has been postulated that allergic disease is associated with a predominance of T(H)2 cells, whether IgE levels and asthma might differ in their relation to early-life cytokine production is not known.

OBJECTIVE

We sought to assess the relationship between first-year adaptive immune cytokine production with asthma and total IgE levels through age 5 years in a nonselected birth cohort.

METHODS

Mitogen (concanavalin A/phorbol 12-myristate 13-acetate)-stimulated IL-4, IL-5, IL-13, and IFN-γ levels were measured in supernatants from cord blood mononuclear cells and PBMCs at birth, 3 months, and 12 months. Total serum IgE levels and physician-diagnosed active asthma were assessed at 1, 2, 3, and 5 years. Longitudinal models that adjust for both T(H)1 and T(H)2 cytokine production were used to determine relations of outcomes.

RESULTS

Relations of cytokines to total IgE levels and asthma were strikingly different. Total IgE levels through age 5 years were positively associated with 12-month IL-4 (P < .001), IL-5 (P < .001), and IL-13 (P = .02) levels when adjusted for IFN-γ levels and inversely associated with 12-month IFN-γ levels after IL-4 adjustment (P = .01). Active asthma through age 5 years was positively associated with 3-month IL-13 levels adjusted for IFN-γ (odds ratio, 2.6; P < .001) and inversely associated with 3-month IFN-γ levels adjusted for IL-13 (odds ratio, 0.5; P = .001). These relations were strongest for nonatopic asthma.

CONCLUSION

Total IgE levels and active asthma through age 5 years are associated with adaptive cytokine production in early life, although relations vary temporally and with regard to the relative importance of individual cytokines.

Inhibitory effect of kefiran on ovalbumin-induced lung inflammation in a murine model of asthma

Kefiran is a major component of kefir which is a microbial symbiont mixture that produces jelly-like grains. This study aimed to evaluate the therapeutic availability of kefiran on the ovalbumin-induced asthma mouse model in which airway inflammation and airway hyper-responsiveness were found in the lung. BALB/c mice sensitized and challenged to ovalbumin were treated intra-gastrically with kefiran 1 hour before the ovalbumin challenge. Kefiran significantly suppressed ovalbumin-induced airway hyper-responsiveness (AHR) to inhaled methacholine. Administration of kefiran significantly inhibited the release of both eosinophils and other inflammatory cells into bronchoalveolar lavage (BAL) fluid and lung tissue which was measured by Diff-Quik. Interleukin-4 (IL-4) and interleukin-5 (IL-5) were also reduced to normal levels after administration of kefiran in BAL fluid. Histological studies demonstrate that kefiran substantially inhibited ovalbumin-induced eosinophilia in lung tissue by H&E staining and goblet cell hyperplasia in the airway by PAS staining. Taken above data, kefiran may be useful for the treatment of inflammation of lung tissue and airway hyper-responsiveness in a murine model and may have therapeutic potential for the treatment of allergic bronchial asthma.

Anti-inflammatory effects of inhaled corticosteroids in chronic obstructive pulmonary disease: similarities and differences to asthma

Both chronic obstructive pulmonary disease (COPD) and asthma are characterised by the presence of airway inflammation. In the stable disease state, the predominant regulatory and effector cells, and the anatomic focus of the changes associated with airway inflammation, differ between COPD and asthma. However, during exacerbations, these patterns of inflammation become more similar. The benefit of anti-inflammatory therapy with inhaled corticosteroids (ICS) is well established in asthma, whereas the extent of the anti-inflammatory effects of ICS in COPD is debated. Understanding the distinctive and, in exacerbations, the changing patterns of inflammation in COPD and asthma allows a better appreciation of the potential for ICS to target the unique pathophysiology of COPD.

IL-17 and IL-17F modulate GM-CSF production by lung microvascular endothelial cells stimulated with IL-1beta and/or TNF-alpha

In this study, we investigated the roles of CD4 T cell cytokines IL-17 and IL-17F in GM-CSF production from lung microvascular endothelial cells (LMVECs). While a wide range of doses of IL-17 or IL-17F alone did not induce GM-CSF release from LMVECs, IL-17 had an enhancing effect on macrophage-derived IL-1beta- and TNF-alpha-induced GM-CSF mRNA expression and production, whereas IL-17F had an enhancing effect on IL-1beta-induced GM-CSF production, but a marked inhibitory effect on TNF-alpha-induced secretion. GM-CSF production was further enhanced with the combination of three cytokines IL-1beta, TNF-alpha and IL-17 or IL-17F. Additionally, when Th1 or Th2 cytokine was combined with IL-1beta or TNF-alpha, both Th1 and Th2 cytokines had a modest stimulatory effect on TNF-alpha-induced GM-CSF production, whereas IL-4 and IFN-gamma profoundly attenuated IL-1beta-induced secretion. Moreover, the regulation by IL-17 plus Th1 or Th2 cytokine of GM-CSF production from LMVECs treated with IL-1beta or TNF-alpha was dependent on the concentration of IL-17. Our findings indicate that IL-17 and IL-17F play a differential regulatory role in GM-CSF production by LMVECs stimulated with IL-1beta and/or TNF-alpha, which is sensitive to Th1 and Th2 cytokine modulation.

Bronchoalveolar lavage cytokine profiles in acute asthma and acute bronchiolitis

BACKGROUND

The pathogenetic basis for the relationship between acute bronchiolitis and asthma has not yet been completely elucidated.

OBJECTIVE

The aim of this study was to compare these 2 diseases in terms of their patterns of airway cytokine response (T(H)1 or T(H)2).

METHODS

By using a bronchoalveolar lavage (BAL) technique, this study investigated the cytokine levels of BAL fluid in children with acute asthma who had no identifiable respiratory syncytial virus (RSV) infection (n = 18) and in infants with acute bronchiolitis caused by RSV (n = 22). Comparisons were made with normal control subjects (n = 14). IFN-gamma (T(H)1) and IL-4 and IL-5 (T(H)2) levels were measured in concentrated BAL fluids by means of ELISA.

RESULTS

The IL-5 level (P <.001) and IL-5/IFN-gamma ratio (P <.001) were significantly increased in the asthmatic group with no identifiable RSV infection and in the RSV-induced bronchiolitis group compared with values in the control group. When infants in the bronchiolitis group were divided into eosinophil-positive and eosinophil-negative subgroups, the eosinophil-positive subgroup had significantly increased IL-5 levels (P <.001) and IL-5/IFN-gamma ratios (P <.01) compared with those in the control group, but similar cytokine responses were not induced in the eosinophil-negative subgroup. The percentage of BAL eosinophils correlated significantly with levels of BAL IL-5 in both the asthma group (r = 0.80, P =.000) and the bronchiolitis group (r = 0.82, P =.000).

CONCLUSIONS

These findings suggest that a subgroup of the RSV-induced bronchiolitis group results in a T(H)2-type response, and this could provide a valuable framework to explain the link between RSV-induced bronchiolitis and asthma.

Enhancement of gelatinase activity during development of subepithelial fibrosis in a murine model of asthma

BACKGROUND

Chronic asthma is characterized by inflammatory cell infiltration and tissue remodelling leading to subepithelial fibrosis. Metalloproteinases (MMPs) are involved in degradation of extracellular matrix in most chronic inflammatory diseases.

OBJECTIVE

The aim of this study was to investigate the expression of MMPs in the development of inflammatory processes associated or not with the concomitant development of subepithelial fibrosis in an experimental model of asthma.

METHODS

Sensitized BP2 mice were challenged with ovalbumin (OA) every 2 weeks during 8 months. Several mice were removed once a month and bronchoalveolar lavages (BAL) or lung biopsies were performed.

RESULTS

Lung sections stained with picrosirius and hydroxyproline measurements showed a significant collagen deposition after 16 weeks of OA challenge, demonstrating the development of subepithelial fibrosis. Pulmonary inflammation was present from the first OA challenge and was consistent throughout the 8 months of the study. Moreover, an up-regulation and activation of MMP-9 and, to a less extent, MMP-2 were observed in BAL fluid from challenged mice. The level of tissue inhibitor of metalloproteinases (TIMP)-1 increased after 12 weeks of OA challenge vs. control mice.

CONCLUSION

This study reveals that a decrease in the activation of the MMP-9 due to the increase in TIMP-1, could contribute to excessive collagen deposition following repeated antigen challenge in sensitized mice.

Altered intracellular expression of the chemokines MIP-1alpha, MIP-1beta and IL-8 by peripheral blood CD4+ and CD8+ T cells in mild allergic asthma

BACKGROUND

The ability of chemokines to regulate Th1 and Th2 responses suggests a role in the pathogenesis of atopic disorders such as allergic asthma where Th2 response dominance has been observed. Although the impact of allergic asthma on local chemokine production in the lung has been the subject of investigation, little is know about the influence of disease progression on peripheral chemokine production. We now report use of whole blood culture and flow cytometry to assess the influence of mild allergic asthma on peripheral T-cell chemokine expression.

METHODS

Study participants included patients with mild allergic asthma (n = 7) and nonasthmatic controls (n = 7). Following in vitro stimulation of peripheral venous blood with phorbol 12-myristate acetate (PMA) and ionomycin, flow cytometry was used to estimate the percentage of CD4+ and CD8+ T cells producing a number of chemokines, including macrophage inflammatory proteins MIP-1alpha and MIP-1beta, RANTES (regulated on activation, T-cell expressed and secreted), monocytic chemotactic protein-1 (MCP)-1, and interleukin (IL)-8, or the cytokines interferon (IFN)-gamma and IL-4. Serum levels of MIP-1alpha, MIP-1beta, RANTES, MCP-1, IL-8, IFN-gamma and IL-4 were also assessed by quantitative ELISA.

RESULTS

Intracellular expression of MIP-1beta by CD4+ and CD8+ T cells from allergic asthmatics was significantly reduced in comparison to that observed for nonasthmatics (median = 2.29% (1.75-3.50) vs 4.57% (3.38-6.64), P = 0.05; 14.20% (13.18-17.88) vs 44.10% (30.38-48.70), P = 0.01). Similarly, intracellular expression of MIP-1alpha by CD8+ T cells from allergic asthmatics was also significantly lower (3.67% (1.17-5.42) vs 17.10% (4.97-20.43), P = 0.05). Conversely, IL-8 expression by both CD4+ and CD8+ T cells from allergic asthmatics demonstrated significant enhancement (9.93% (7.77-11.28) vs 4.14% (3.61-7.11), P = 0.05; 8.40% (6.97-10.04) vs 4.98% (3.37-6.08), P = 0.05). Examination of intracellular IFN-gamma and IL-4 revealed no significant difference in the expression of either cytokine by CD4+ T-cells from allergic asthmatics and nonasthmatics. In contrast, expression of IFN-gamma was significantly reduced in CD8+ T-cells from allergic asthmatics (24.60% (21.08-32.50) vs 48.40% (41.50-55.28), P = 0.01).

CONCLUSIONS

The occurrence in mild allergic asthma of peripheral T-cell chemokine expression suggestive of a diminished Th1 response, coinciding with marginal change in cytokine profiles indicative of a Th2 response bias, confirms the importance of chemokine involvement in the etiology of allergic asthma. The ability to use whole blood culture to estimate chemokine expression in T cell subsets may ultimately provide a practical means to evaluate disease status and to monitor early intervention therapies which target chemokines.

Persistence of bronchopulmonary hyper-reactivity and eosinophilic lung inflammation after anti-IL-5 or -IL-13 treatment in allergic BALB/c and IL-4Ralpha knockout mice

BACKGROUND

Antigen-induced bronchopulmonary hyper-reactivity (BHR) is generally associated with eosinophilia. It involves cytokines produced by Th2 lymphocytes, including IL-4, IL-5 and IL-13, which are implicated in IgE production, eosinophil differentiation and attraction, and related events relevant to allergic inflammation, whose mechanisms remain unclear.

OBJECTIVE

To investigate the mechanisms by which Th2 cytokines mediate eosinophilia and subsequent BHR using ovalbumin (OVA)-immunized and OVA-challenged IL-4Ralpha-/- and IL-4-/- mice, which fail to transduce and/or to produce IL-4 and IgE as compared with wild type (WT) mice, and specific neutralizing antibodies.

METHODS

On days 0 and 7, mice were immunized subcutaneously (s.c.) with OVA. At day 14, anti-IL-5 or anti-IL-13 antibodies were administered intranasally and/or intravenously before allergenic challenge. Different functional and cellular parameters were studied in vivo and cytokine production was followed with a newly described ex vivo procedure using lung explants.

RESULTS

IL-4Ralpha-/- and IL-4-/- mice developed BHR and pulmonary eosinophilia, even though eosinophil recruitment to the bronchoalveolar liquid lavage (BALF) was reduced. In vivo, IL-4-/- and IL-4Ralpha-/- mice produced, respectively, no or reduced amounts of IL-5 in the BALF/serum as compared with WT mice, whereas no IL-13 in the BALF was detected. By contrast, ex vivo, surviving lung explants from WT and IL-4-/- or IL-4Ralpha-/- mice produced IL-13 and large amounts of IL-5. The neutralization of IL-5 in vivo (BALF and serum) and ex vivo (from lung explant) in IL-4Ralpha-/- and WT mice failed to suppress BHR and lung eosinophilia, and to modify IL-13 production ex vivo. In addition, neutralization of IL-13 in vivo from lung explant also failed to abrogate BHR and lung eosinophilia, whereas IL-5 was unchanged.

CONCLUSION

Antigen-induced BHR can develop independently from IL-4, IL-5 or IL-13 and from the IL-4alpha receptor chain, suggesting a possible novel IL-4, IL-5 and IL-13-independent pathway for the development of BHR in allergic BALB/c mice. The failure of IL-5 or IL-13 antibodies to prevent BHR in IL-4Ralpha-/- mice suggests that neither is indispensable for BHR but does not exclude a role for lung tissue eosinophilia.

Relationship between changes in interferon-gamma production by peripheral blood T cells and changes in peak expiratory flow rate in patients with chronic stable asthma

BACKGROUND

Cytokines production by T helper lymphocytes (Th cells), which orchestrate the interplay of the different cells involved in airway inflammation of asthma, may be reflected in peripheral blood. Some studies have suggested that the Th cell cytokines by peripheral blood T cells correlate with asthma severity.

OBJECTIVE

To investigate the relationship between changes in IFN-gamma production by peripheral blood T cells and changes in lung function in chronic stable asthmatics.

METHODS

Sixteen patients with chronic stable moderate asthma aged 35-65 years (nine women) were recruited. Morning and evening peak expiratory flow rates (PEFR) monitoring and blood sampling for peripheral blood T cell culture, total IgE and blood eosinophils were performed at baseline and week 12. Levels of IFN-gamma, IL-4 and IL-5 in culture supernatants of peripheral blood T cell were determined by using enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

Patients with increased IFN-gamma changes from baseline showed significantly increased changes in morning (P = 0.02) and evening (P < 0.05) PEFR compared with those with decreased IFN-gamma changes. The changes in IFN-gamma production and IFN-gamma: IL-4 ratio significantly correlated with the changes in morning PEFR (Rs = 0.59, P < 0.02; Rs = 0.63, P < 0.01, respectively) and tended to correlate with the changes in evening PEFR (Rs = 0.45, P = 0.08; Rs = 0.5, P = 0.05, respectively). The changes in IL-4 and IL-5 did not correlate with the changes in IgE and blood eosinophils, respectively.

CONCLUSIONS

These findings suggest that IFN-gamma may be associated with the alteration of lung function in asthmatics and play a role in the pathophysiology of chronic stable asthma.

Ragweed-induced expression of GATA-3, IL-4, and IL-5 by eosinophils in the lungs of allergic C57BL/6J mice

Allergen-induced recruitment of T lymphocytes and eosinophils to the airways is associated with increased expression of the transcription factor GATA-3. In this study, the relationship between airway inflammation and GATA-3 expression in the lungs was investigated using ragweed-sensitized C57BL/6J mice. Intratracheal ragweed challenge increased both the number of GATA-3-expressing cells in the perivascular and peribronchial regions and the amount of expression per cell. Interleukin (IL)-4 and IL-5 levels in bronchoalveolar lavage fluid were upregulated in parallel with GATA-3 expression. GATA-3 mRNA and protein colocalized to eosinophils. Eosinophils isolated from the lungs and stimulated with phorbol 12-myristate 13-acetate and/or A-23187 released IL-5. The release was inhibited by actinomycin D, which indicates that de novo synthesis of the cytokine was involved. Western blot analysis of proteins from isolated eosinophils demonstrated expression of the p50 subunit of nuclear factor-kappaB, a transcription factor that is implicated in control of GATA-3 expression. These data provide evidence that allergen challenge increases GATA-3 and proinflammatory cytokine expression by pulmonary eosinophils, which could provide positive feedback for the inflammatory response.

Immuno-regulatory cytokines in asthma: IL-15 and IL-13 in induced sputum

BACKGROUND

The importance of Th2-type lymphocyte function in asthmatic airway inflammation is well recognized, but less is known about the factors which regulate the function of these lymphocytes in asthma. The macrophage-derived cytokine, interleukin (IL)-15 has a number of T cell regulatory properties which might be of relevance to asthma and its treatment.

OBJECTIVE

The aims were to identify and quantify the T cell regulatory cytokine IL-15 in induced sputum samples from asthmatic patients, in comparison with IL-13, and to relate the levels of these cytokines to treatment with inhaled steroids.

METHODS

Induced sputum was collected from 16 asthmatics (eight steroid and eight non-steroid treated) and eight normal controls. IL-15 and IL-13 levels were measured by enzyme-linked immunoassay (ELISA) in sputum. IL-15 levels were also measured in sputum cell culture supernatants and localized to specific sputum cells by immuno-cytochemistry.

RESULTS

IL-15 levels were increased and IL-13 levels were decreased in sputum fluid from steroid-treated compared with non-steroid-treated asthmatics. IL-15 was localized specifically to macrophages and the proportion of these cells expressing IL-15 correlated with sputum fluid IL-15 and IL-15 levels in cell culture supernatants, and all were higher in the steroid-treated asthmatics.

CONCLUSION

IL-15 and IL-13 production appears to be reciprocally regulated by steroid therapy in asthma patients. The steroid-associated increase in IL-15 may regulate a fundamental shift away from an inflammatory Th2-type environment in asthma and may be an essential component of the cytokine modulation underlying the therapeutic benefit of corticosteroids in this condition.

Assessing the evidence for remodelling of the airway in asthma

Asthma is now described as being characterized by reversible airflow obstruction, with bronchial inflammation and tissue remodelling of the airway wall. The description of remodelling has been usefully invoked to account for a component of airflow obstruction that is unresponsive to usual bronchodilator therapy. It is crucial to examine critically the evidence for this view, particularly the quantitation of specific changes in the epithelium, mucus glands, cell infiltrate, collagen, vessels and smooth muscle of the bronchial wall. The useful tools of immunohistochemistry and molecular biology combined with airway biopsy and well-designed clinical trials will be essential to determine the specific roles of cells and cytokines in airway remodelling in asthma.

Nitrogen dioxide exposure from domestic gas cooking and airway response in asthmatic women

BACKGROUND

Previous studies have not found a consistent association between exposure to domestic cooking using gas appliances and exacerbation of asthma. We investigated the immediate airflow response to acute exposure from single episodes of gas cooking, and peak airflow variability from continued exposure to repeated episodes of gas cooking in a group of non-smoking asthmatic women.

METHODS

Sixteen adult non-smoking women with mild to severe persistent asthma were studied. The acute short term level of nitrogen dioxide (NO2) during gas cooking episodes and the mean exposure to NO2 from repeated gas cooking episodes were measured over a 2 week period, as well as proxy measures of frequency of cooking on each day and the length of time spent cooking each day. Their asthma status was monitored using peak expiratory flow rates (PEFR) before and after cooking, 2 week self-recorded serial readings of PEFR, respiratory symptom severity score, and use of rescue bronchodilators for acute asthma attacks.

RESULTS

Cooking was significantly associated with an immediate mean fall in PEFR of 3.4% (p=0.015, paired t test). The acute short term NO2 level during cooking was significantly correlated with the fall in PEFR (r=–0.579; p=0.019). The frequency of cooking over a 2 week period was positively correlated with the mean exposure to NO2(r=0.529; p=0.042). Continued exposure to NO2 over a 2 week period was associated significantly with increased frequency of rescue bronchodilator usage for asthma attacks (r=0.597; p=0.031). However, it was negatively associated with PEFR variability (r=–0.512; p=0.051) and respiratory symptom severity score (r= –0.567; p=0.043), probably due to the masking effects of bronchodilator treatment.

CONCLUSIONS

Acute short term exposure to NO2 from single episodes of gas cooking is associated with immediate airflow limitation. Continued exposure from repeated episodes of gas cooking in asthmatic women is associated with greater use of rescue bronchodilators.

The anti-inflammatory effects of leukotriene-modifying drugs and their use in asthma

Asthma is a chronic inflammatory disease of the airways. Anti-inflammatory drug therapy, primarily using corticosteroids, is now considered the first-line treatment in the management of all grades of asthma severity. Although corticosteroids are believed to be the most potent anti-inflammatory agents available, they do not suppress all inflammatory mediators involved in the asthmatic response. Leukotrienes, which are lipid mediators generated from the metabolism of arachidonic acid, play an important role in the pathogenesis of asthma. They produce bronchospasm, increase bronchial hyperresponsiveness, mucus production, and mucosal edema, and enhance airway smooth muscle cell proliferation and eosinophil recruitment into the airways, and their synthesis or release is unaffected by corticosteroid administration. The use of leukotriene synthesis inhibitors or leukotriene receptor antagonists as anti-inflammatory therapies in asthma has therefore been investigated. Beneficial effects of leukotriene-modifying drugs have been demonstrated in the management of all grades of asthma severity, and there is evidence that certain patient groups (such as those with exercise-induced asthma or aspirin-induced asthma) may be particularly suitable for such therapy.

Correlation between eosinophilia induced by CD4(+) T cells and bronchial hyper-responsiveness

The relationship between CD4(+) T cell-mediated airway eosinophilic inflammation and bronchial hyper-responsiveness (BHR) was investigated. Ovalbumin-reactive T(h)0 clones were adoptively transferred to unprimed BALB/c mice and then the mice were challenged by inhalation of the relevant antigen. Upon antigen provocation, infused T(h) clones infiltrated into the airways, followed by the accumulation and degranulation of eosinophils, goblet cell hyperplasia, edema and increase in bronchial responsiveness to acetylcholine. Transfer of several clones that differed in the levels of IL-5 production revealed that the magnitude of in vivo eosinophilia strongly correlated with the IL-5-producing capacity of the infused T(h) clones. Administration of anti-IL-5 mAb almost completely suppressed antigen-induced eosinophilic inflammation and BHR. Administration of anti-IL-4 mAb or anti-IFN-gamma mAb enhanced the eosinophilia and BHR, whereas anti-IL-2 mAb did not affect them. The number of accumulated eosinophils significantly correlated with the intensity of BHR. Our present results clearly demonstrated that CD4(+) T cells induced BHR as a result of eosinophilic inflammation. IL-5 totally regulated both responses.

Effects of prostaglandin E2 and cAMP elevating drugs on GM-CSF release by cultured human airway smooth muscle cells. Relevance to asthma therapy

Human airway smooth muscle (HASM) cells release granulocyte macrophage-colony stimulating factor (GM-CSF) and express cyclooxygenase (COX)-2 (resulting in the release of prostaglandin [PG] E2) after stimulation with cytokines. Because COX-2 activity can regulate a number of inflammatory processes, we have assessed its effects, as well as those of agents that modulate cyclic adenosine monophosphate (cAMP), on GM-CSF release by HASM cells. Cells stimulated with a combination of proinflammatory cytokines (interleukin-1beta and tumor necrosis factor-alpha each at 10 ng/ml) for 24 h released significant amounts of PGE2 (measured by radioimmunoassay) and GM-CSF (measured by enzyme-linked immunosorbent assay). Indomethacin and other COX-1/COX-2 inhibitors caused concentration-dependent inhibitions of PGE2 concomitantly with increases in GM-CSF formation. Addition of exogenous PGE2 or the beta2-agonist fenoterol, which increase cAMP, to cytokine-treated HASM cells had no effect on GM-CSF release unless COX activity was first blocked with indomethacin. The type 4 phosphodiesterase inhibitors rolipram and SB 207499 both caused concentration-dependent reductions in GM-CSF production. Thus, when HASM cells are activated with cytokines they release PGE2, which acts as a "braking mechanism" to limit the coproduction of GM-CSF. Moreover, agents that elevate cAMP also reduce GM-CSF formation by these cells.

A unique mRNA initiated within a middle intron of WHSC1/MMSET encodes a DNA binding protein that suppresses human IL-5 transcription

Human interleukin (IL)-5 gene transcription is regulated by several transcription factor binding sites, including CLE 0, GATA, and a region from position -123 to -92 known as response element (RE)-II. By expression cloning, a partial protein was identified that bound to concatamers of RE-II. Recombinant protein derived from this initial complementary DNA (cDNA) encoding the partial protein specifically bound to RE-II-containing oligonucleotides in electromobility shift assays. The complete sequence (3,649 bp) was determined by 5' rapid amplification of cDNA ends and comparisons to existing ESTs, and found to be identical to the 3' half of Wolf-Hirschhorn syndrome candidate 1, (WHSC1; also known as Multiple Myeloma SET domain [MMSET]). The full-length protein contains an SET domain and two plant homeodomain-type zinc fingers. Transcription initiation of RE-II binding protein (RE-IIBP) messenger RNA (mRNA) uniquely occurred within the middle of WHSC1 near a region that exhibits complex mRNA splicing. RE-IIBP reactive polyclonal antisera identified proteins in human T-cell nuclear protein extracts of 62 and 66 kD that were consistent with the length of the longest open reading frame in RE-IIBP. In contrast, WHSC1 is predicted to encode a protein of 136 kD. In activated human Jurkat and murine D10.G4.1 T cells, expression of full-length and truncated forms of RE-IIBP repressed RE-II promoter activity of a 5X-RE-II luciferase reporter construct by as much as 75%. In addition, RE-IIBP expressed in activated D10.G4.1 T cells inhibited endogenous murine IL-5 production. The repressor activity of RE-IIBP is consistent with the presence of an SET domain that is found in other proteins that act as gene silencers.

Exhaled nitric oxide as an indicator of severity of asthmatic inflammation

Traditional assessment of severity of asthma relies on an evaluation of signs and symptoms and pulmonary function tests. These pulmonary function tests, such as peak expiratory flow rates, forced vital capacity, and forced expiratory flow rates, are indirect measures of airway caliber only, and not inflammation. Since asthma is an inflammatory disease, a measure of the degree of inflammation would be helpful in quantitating severity and titrating of anti-inflammatory therapy. A noninvasive method for measuring pulmonary inflammation would therefore be helpful to assist the emergency physician in initial treatment and assist in titration of anti-inflammatory therapy during repeat visits. Exhaled nitric oxide (NO) assays are convenient and practical and may fulfill this role. In this review, we discuss the role of NO in asthmatic inflammation and the role that exhaled NO values may play in the emergency management of asthma.

Integrated signals between IL-13, IL-4, and IL-5 regulate airways hyperreactivity

In this investigation, we have examined the integrated relationship between IL-13, IL-4, and IL-5 for the development of airways hyperreactivity (AHR) in a model of asthma in BALB/c mice. Sensitization and aeroallergen challenge of both wild-type (WT) and IL-13 gene-targeted (IL-13-/-) mice induced allergic disease that was characterized by pulmonary eosinophilia and AHR to beta-methacholine. Although these responses in IL-13-/- mice were heightened compared with WT, they could be reduced to the level in nonallergic mice by the concomitant neutralization of IL-4. Mice in which both IL-4 and IL-13 were depleted displayed a marked reduction in tissue eosinophils, despite the development of a blood eosinophilia. Similar neutralization of IL-4 in WT mice only partially reduced AHR with no effect on tissue eosinophilia. In addition, neutralization of IL-5 in IL-13-/- mice, but not in WT mice, inhibited AHR, suggesting that tissue eosinophilia is linked to the mechanism underlying AHR only in the absence of IL-13. Additionally, mucus hypersecretion was attenuated in IL-13-/- mice, despite the persistence of AHR. Taken together, our data suggest both a modulatory role for IL-13 during sensitization and a proinflammatory role during aeroallergen challenge. The latter process appears redundant with respect to IL-4.

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.

The differential diagnosis of eosinophilic esophagitis

Eosinophilic esophagitis is a morphologic finding that may result from a wide spectrum of clinical conditions. The distinctive histological features accompanying eosinophilic esophagitis may facilitate the diagnosis of the underlying disease entity. Unfortunately, there are no pathognomonic histologic characteristics associated with eosinophilic esophagitis. Clinical signs and symptoms, immunological markers, endoscopic findings, and response to therapy may help establish or confirm the diagnosis of a clinical condition that results in eosinophilic esophagitis. The following discussion outlines the causes of eosinophilia in an esophageal biopsy sample.

Mucosally induced immunoglobulin E-associated inflammation in the respiratory tract

The purpose of the present study was to determine the immunologic responses, particularly immunopathologic reactions, associated with nasal immunization with the mucosal adjuvant, cholera toxin (CT). BALB/c mice were nasally immunized with tetanus toxoid (TT) combined with CT, and the responses of these mice were determined. After nasal immunization, mice produce a serum antibody response, primarily of the immunoglobulin G (IgG) isotype of predominantly IgG1 subclass, against both TT and CT. Along with the antibody responses, we also found that inflammatory reactions, which could be potentially fatal, developed within the lung. Furthermore, IgE responses were also induced after nasal immunization, and these responses were associated with the detection of interleukin 5 in the serum. Thus, nasal immunization with TT plus CT likely results in the activation of Th2 cells, which may contribute to serious immunopathologic reactions in the lung.

Low levels of interferon-gamma in nasal fluid accompany raised levels of T-helper 2 cytokines in children with ongoing allergic rhinitis

The T-helper 2 (Th2) cytokines interleukin-(IL-) 4, IL-5, IL-6, IL-10 and the Th1 cytokine IFN-gamma and their associations with eosinophil, eosinophil cationic protein (ECP) and immunoglobulin (Ig) E were studied in nasal lavage fluid from 60 school children with allergic seasonal rhinitis and 36 nonatopic healthy controls, before and during the pollen season. Eosinophil differential counts and IgE increased significantly in the patients during the pollen season. The eosinophil differential counts, ECP and IgE were all significantly higher during the season than in specimens simultaneously obtained from the nonatopic controls. Before season, the levels of ECP and IgE, but not eosinophils, were significantly higher in the patients than in the controls. During the season the nasal lavage fluid levels of IFN-gamma were significantly lower and the IL-4/IFN-gamma quotients significantly higher in the allergic than in the control children. In the allergic children, but not in the controls, the nasal fluid levels of the Th2 cytokines IL-4, IL-5 and IL-10 increased during the season, and together with IL-6, were correlated with the differential counts of eosinophils, and with the levels of ECP and IgE. These findings are compatible with the hypothesis that a deficient release of the Th1 cytokine IFN-gamma plays an important role in the pathogenesis of allergic inflammation. Regardless of whether the defective IFN-gamma secretion is primary or a consequence of suppression by other cytokines, it will in the atopic subjects enhance the release of Th2 cytokines, which in turn will facilitate the development of allergic inflammation.

Fas-induced death of a murine pulmonary epithelial cell line: modulation by inflammatory cytokines

Here we report that a murine pulmonary epithelial cell line (LA-4) expresses Fas (CD95) under resting conditions. Exposure of untreated cells to an anti-Fas monoclonal antibody induces apoptosis in a time- and dose-dependent fashion as revealed by cell viability and by propidium iodide staining followed by FACS analysis. Fas surface expression was increased, in a time-dependent fashion, by the inflammatory cytokines IL-1beta and TNF-alpha. Other inflammatory mediators such as IFN-gamma or endothelin-1 were without any effect. This increase in Fas expression was associated with an increase in sensitivity to anti-Fas-induced apoptosis of LA-4 cells. IL-4, which is known to induce CD95 resistance in other cell types, did not protect LA-4 cells against anti-CD95-induced cell death. These results suggest that Fas-induced apoptosis of epithelial cells may contribute to the epithelial shedding observed in asthmatic airways.

Immunohistochemical localization of cytokines and cell adhesion molecules in maxillary sinus mucosa in chronic sinusitis

OBJECTIVE

Chronic sinusitis is a common disease characterized by persistent inflammation of the nasal and paranasal sinus mucosa. Accumulating evidence supports the importance of proinflammatory cytokines and endothelial cell adhesion molecule (CAM) expression as an initiating process in tissue inflammation. This study was conducted to investigate the localization of major cytokines and CAMs in the maxillary sinus mucosa from patients with chronic sinusitis and from normal subjects.

METHODS

Maxillary sinus mucosal specimens from patients with chronic sinusitis (n = 10) and from normal subjects (n = 6) were immunostained with specific antibodies directed against the cytokines (IL-1alpha, IL-1beta, IL-6, IL-8 and TNF-alpha) and the CAMs (intercellular adhesion molecule-1, ICAM-1 and vascular CAM-1, VCAM-1).

RESULTS

The number of immunoreactive cells for IL-1alpha, IL-1beta, IL-6, IL-8, and TNF-alpha was increased significantly in patients with chronic sinusitis compared with normal controls. Immunoreactivity for ICAM-1 was also increased significantly in patients with chronic sinusitis compared with normal controls, whereas VCAM-1 is only minimally expressed or is absent in both groups.

CONCLUSION

These findings indicate that bacterial and/or viral infection may induce functional and morphologic changes in the maxillary sinus mucosa in chronic sinusitis through enhanced generation of specific cytokines in conjunction with CAMs.

Eotaxin and impaired lung function in asthma

We performed an association study of plasma eotaxin levels, eosinophil counts, total IgE levels, asthma diagnosis, and lung function in an ethnically diverse and geographically dispersed population. We studied 515 asthmatic and 519 normal subjects, none of whom was taking inhaled or oral corticosteroids. Logistic regression analysis demonstrated a direct relationship between asthma diagnosis and eotaxin levels (p < 0.0001). The odds of an asthma diagnosis increased with eotaxin quartile, with the highest quartile having an odds ratio of 5.4 (95% CI 3.2 to 9.2, p < 0.001) compared with the lowest eotaxin quartile. Eotaxin levels were inversely related to lung function (p < 0.001), with the mean percent predicted FEV(1) in the highest eotaxin quartile being 13.5 percentage points (SEM 2.1, p < 0.001) less than that in the lowest quartile. Plasma eotaxin levels were associated with asthma and inversely related to lung function independent of age, race, sex, or smoking status. When combined with eosinophil counts and IgE levels, eotaxin levels contributed to the odds of an asthma diagnosis and of impaired lung function. Our results are the first to associate eotaxin levels with asthma diagnosis and compromised lung function in a large geographically and ethnically diverse population.

Inflammatory markers in acute exacerbations of obstructive pulmonary disease: predictive value in relation to smoking history

The aim of this study was to investigate the relationship between the effect of emergency treatment and inflammatory markers in patients with acute exacerbations of obstructive pulmonary disease, especially with respect to smoking history. We investigated 50 unselected patients with acute bronchial obstruction. Blood, urine and sputum samples were taken and analysed for eosinophil and neutrophil markers. The patients were observed for at least 2 h and recordings of forced expiratory volume in 1 s (FEV1) were taken. They were re-examined after 1 and 4 weeks. The absolute levels of inflammatory markers did not differ significantly between non- or short-term smokers (< or = 5 pack-years) and long-term smokers (> 5 pack-years) with the exception of myeloperoxidase in serum (S-MPO), which was higher in long-term smokers. The patients with higher levels of eosinophil markers before emergency treatment experienced a greater improvement in lung function. In non- or short-term smokers this relationship was found in blood and urine, whereas in long-term smokers it was seen in sputum. No correlation was found between neutrophil markers and changes in lung function. We conclude that patients with obstructive pulmonary disease with acute exacerbations and high levels of eosinophil markers respond well to treatment.

Exhaled nitric oxide and its relationship to airway responsiveness and atopy in asthma. BHR-Study Group

Exhaled nitric oxide (NO) has attracted increasing interest as a non-invasive marker of airway inflammation. The purpose of this study was to determine whether exhaled nitric oxide in subjects with asthma varied according to their atopic status and to examine its correlation with airway hyperresponsiveness and lung function measurements. Forty patients with asthma and 13 controls participated in the study. Nitric oxide was measured on three occasions with intervals of at least 3 days, using a chemiluminescence method. Airway responsiveness was assessed with methacholine challenge and lung function measurements were made. All subjects recorded peak expiratory flow and kept a symptom diary during a 17-day period. There was no significant difference in lung function measurements, peak expiratory flow or symptom score between the two asthma groups. Atopic patients with asthma had a significantly higher mean amount of exhaled NO than non-atopic subjects with asthma (162 +/- 68 vs. 113 +/- 55 nl min-1; P = 0.03) and the control group (88 +/- 52 nl min-1; P = 0.004). No significant difference was found in the amount of exhaled NO between non-atopic patients with asthma and the controls. In atopic subjects with asthma the mean exhaled NO was significantly correlated to the dose-response slope for methacholine (r = -0.52; P = 0.02), while no such correlation was found in the non-atopic group. In conclusion; in this study, atopic subjects with asthma had higher levels of exhaled NO than non-atopic subjects. Atopic status should be taken into account when measuring levels of exhaled NO in subjects with asthma.

Ectodomain cleavage and shedding of the type III transforming growth factor-beta receptor in lung membranes effect of temperature, ligand binding and membrane solubilization

Previous studies from our laboratory [Philip, A. & O'Connor-McCourt, M. D. (1991) J. Biol. Chem. 266, 22290--22296] have shown that the lung exhibited the highest uptake of circulating [125I]-transforming growth factor-beta1 (TGF-beta1) on a per gram basis. This observation, together with the lack of information on TGF-beta receptor expression in the lung, prompted us to attempt to characterize TGF-beta receptors in this tissue. In the present report we show that the type III TGF-beta receptor is the most abundant TGF-beta binding protein in rat lung membranes and that it exhibits a 10-fold higher affinity for TGF-beta2 than for TGF-beta1. We observed that the majority of the type III receptor population in lung membranes is cleaved at a site in the central portion of the ectodomain, the resulting two fragments (95 kDa and 58 kDa) being held together by disulfide bonds. Furthermore, we demonstrate that a soluble form of the ectodomain of the type III receptor is shed from rat lung membranes in an efficient manner, with protease cleavage occurring at a site close to the transmembrane domain. This shedding is controllable by temperature, thus providing a system to study the mechanism of ectodomain release. Using this system, we show that the shedding is inhibited by prior ligand binding and by membrane solubilization. The identification of a membrane preparation which exhibits controllable and quantitative release of the type III receptor ectodomain provides a unique cell-free system for further studies of the mechanism of shedding of the type III TGF-beta receptor ectodomain.

Asthma, atopy and Chlamydia pneumoniae antibodies in adults

BACKGROUND

Factors involved in the development of inflammation and asthma in nonatopic subjects have remained largely obscure, although there is some evidence to suggest that certain infections may play a role.

OBJECTIVE

We investigated the association between serological evidence of Chlamydia pneumoniae infection and asthma in adults, and the possible modifying effect of the patients' atopic status on this association.

METHODS

Four hundred and thirty consecutive patients who attended the hospital between 1992 and 1993 with symptoms suggestive of asthma, rhinitis or allergy were enrolled. Diagnostic procedures including lung function measurements and skin-prick tests were performed in all patients. The patients with established asthma (n = 332) were divided into those with recent asthma (n = 224, onset 1985 onward) and longstanding asthma (n = 108, onset before 1985). The controls (n = 98) comprised all subjects who did not meet the criteria of asthma. Serum immunoglobulin (Ig)G, IgA and IgM antibodies to C. pneumoniae were measured by the microimmunofluorescence test.

RESULTS

In women, the prevalences of elevated IgG (a titre of >/= 128) and IgA (>/= 32) antibody levels and the age-adjusted geometric mean titres (GMT) of IgG and IgA antibodies were invariably highest among subjects with nonatopic longstanding asthma. Elevated IgG titres in women occurred in 11% of controls, in 28% of nonatopic recent onset asthmatics, and in 43% of asthmatics with nonatopic longstanding disease; for men the respective figures were 33, 50 and 64%. Logistic regression analysis controlling for age, sex and smoking showed that asthma was significantly associated with elevated IgG antibody levels to C. pneumoniae (odds ratio 3.3, 1.6-6.8 for longstanding asthma, 2.3, 1. 2-4.4 for recent asthma, and among women only 4.2, 1.6-10.9 for longstanding asthma, and 3.0, 1.3-7.2 for recent asthma). When the atopics and nonatopics were analysed separately, an even stronger relationship in the nonatopics was obtained for longstanding asthma (6.0,2.1-17.1). In contrast, the relationship between atopic asthma, either recent or longstanding, and elevated IgG titres was not significant, indicating that asthma per se does not predispose to C. pneumoniae infection.

CONCLUSIONS

Asthma was significantly associated with elevated IgG antibody levels to C. pneumoniae, and this association was strongest for nonatopic longstanding asthma.

Interleukin-8 inhalation directly provokes bronchoconstriction in guinea pigs

BACKGROUND

Although it has been reported that the concentration of interleukin (IL)-8 in nasal lavage fluid and sputum and its production in bronchial epithelium were increased in asthmatic subjects, the direct effects of IL-8 on the airways in vivo is unclear.

METHODS

We examined bronchoconstriction in response to IL-8 inhalation through an endotracheal cannula in anesthetized, artificially ventilated guinea pigs.

RESULTS

Inhalation of IL-8 at concentrations of 1 and 10 microg/ml caused significant bronchoconstriction, as revealed by the elevation of pressure at the airway opening. Moreover, the bronchoconstriction induced by IL-8 was significantly inhibited by the antihistamines diphenhydramine and terfenadine, suggesting the involvement of histamine release in the IL-8-induced bronchoconstriction. No significant leukocyte infiltration was observed in the bronchoalveolar lavage fluid or histologic findings 25 min after the first IL-8 inhalation.

CONCLUSIONS

IL-8 provokes bronchoconstriction without leukocyte accumulation in the airways, mediated in part by histamine release, in guinea pigs.

Effects of chronic anti-interleukin-5 monoclonal antibody treatment in a murine model of pulmonary inflammation

The maturation of eosinophils in bone marrow, their migration to pulmonary tissue, and their subsequent degranulation and release of toxic granule proteins contributes to the pathophysiology observed in asthma. Interleukin-5 (IL-5) is essential for these processes to occur. Therefore, much emphasis has been placed on attempts to inhibit the production or activity of IL-5 in order to attenuate the inflammatory aspect of asthma. In this report, the immunological consequences of long-term exposure to an antibody recognizing IL-5 (TRFK-5) were studied in a murine pulmonary inflammation model. A single dose of TRFK-5 (1 mg/ kg, intraperitoneally) reversibly inhibited antigen-dependent lung eosinophilia in mice for at least 12 wk and inhibited the release of eosinophils from bone marrow for at least 8 wk. Normal responses to aerosol challenge were attained after 24 wk. In mice treated acutely with antibody (2 h before challenge), 50% inhibition of pulmonary eosinophilia occurred when 0. 06 mg/kg TRFK-5 was administered (intraperitoneally; ED50), resulting in 230 ng/ml (IC50) in serum. In mice treated with one dose of TRFK-5 (1 mg/kg) and rested before challenge, the antibody exhibited a half-life of 2.4 wk. After 18 to 19 wk, antigen challenge-induced eosinophilia was inhibited by 50% and serum levels of TRFK-5 were 25 ng/ml. TRFK-5 remaining in mice 8 wk after a single injection of TRFK-5 was sufficient to inhibit at least 50% of the eosinophilia induced in blood 3 h after injection of recombinant murine IL-5 (10 microg/kg, intravenously). To assess the biologic effect of long-term exposure of mice to antibody, several parameters of immune-cell function were measured. Throughout the extended period of activity of TRFK-5 (>/= 12 wk) there were no gross effects on antigen-dependent increases in T-cell recruitment into bronchoalveolar fluid (BALF), in IL-4 and IL-5 steady-state mRNA levels in lung tissue, or in immunoglobulin E (IgE) and IgG levels in serum. There was a small increase in IL-5 steady-state mRNA production in TRFK-5-treated mice after 2 h or 2 wk, but this was not observed at other times examined. In untreated mice, IL-5 steady-state mRNA production in response to antigen challenge decreased > 6-fold with age, although at all time points there was an increase in mRNA levels following challenge. Therefore, at later times, 25 ng/ml rather than 230 ng/ml of TRFK-5 inhibited BALF eosinophilia, probably because of reduced IL-5 levels. Twenty-four weeks after treatment with TRFK-5, when challenge-induced eosinophilia was restored, there was an excess of CD4(+) T cells in BALF from challenged mice. However, these T cells had no measurable effects on other responses to challenge, including cytokine production, B-cell accumulation, and immunoglobulin production in serum. Thus, the biologic duration of TRFK-5 was several months, and its activity was due to the presence of antibody above a therapeutic threshold rather than to any profound effect on the immune system.

Effect of fluticasone propionate aqueous nasal spray on allergen-induced inflammatory changes in the nasal airways of allergic rhinitics following exposure to nitrogen dioxide

BACKGROUND

The authors have recently demonstrated that prior exposure for 6 h to 400 p.p.b. nitrogen dioxide significantly enhances the early phase response of eosinophils in the nasal airways of allergic rhinitics to subsequent allergen provocation.

OBJECTIVE

To investigate whether treatment with fluticasone propionate aqueous nasal spray (FP) can alter the inflammatory response in the nasal airways under these conditions.

METHODS

Sixteen allergic, rhinitic patients were recruited for this double-blind, randomized, cross-over study and received either topical FP 200 microg once daily or matched placebo for 4 weeks. At the end of treatment, all underwent nasal lavage followed by a 6 h exposure to 400 p.p.b. NO2. Following exposure to NO2, nasal allergen challenge was performed and nasal lavage repeated. After a 4 week washout period, patients were given alternate treatment and tested as above.

RESULTS

Analysis of eosinophil cationic protein (ECP) in lavage samples from patients treated with placebo, demonstrated that this was significantly increased from a median value of 2.3 ng/mL (range: 1.0-7.1) to 15.1 ng/mL (range: 1.5-40.0; P = 0.001) following exposure to NO2 and allergen challenge. However, in patients treated with FP, ECP concentrations only increased from 3.3 ng/mL (range: 0.2-9.2) to 5.1 ng/mL (range: 0.3-20.0; P = 0.034) following exposure to NO2 and allergen challenge. The difference of the changes in ECP concentration between the placebo and the FP-treated group was significant (P = 0.003). Similarly, there was a significant increase in the number of eosinophils in nasal lavage after exposure to NO2 and allergen challenge in the placebo group, and this increase was inhibited in FP group (P = 0.002).

CONCLUSION

These results suggest that FP influences NO2- and allergen-induced changes in eosinophil function, as well as eosinophil number in the nasal airway of allergic rhinitics.

Inflammation in asthma: the cornerstone of the disease and target of therapy

Asthma is a chronic disease associated with variable levels of airflow obstruction. Considerable evidence has been obtained to show that airway inflammation is a major factor in the pathogenesis of asthma in associated bronchial hyperresponsiveness, and in the level of disease severity. The inflammatory pattern in asthma is multicellular in nature, with mast cells, neutrophils, eosinophils, T lymphocytes, and epithelial cells participating in the response. Furthermore, it is known that mediators, cytokines, and chemokines from these cells contribute to the orchestration of the inflammatory process. Because airway inflammation appears to be a critical etiologic feature of asthma, it has become the target of therapy. In this review the features of airway inflammation will be examined, and the effect of therapeutic agents on markers of airway injury will be discussed. Establishing, understanding, and finally controlling the features of airway inflammation have given insight to disease pathogenesis and the effectiveness of various treatments. The integral role of inhaled corticosteroids in modifying the complex inflammatory component of asthma will be explored, with special focus on the high degree of efficacy associated with this treatment--vis-á-vis other therapeutic agents--in preventing or blocking specific proinflammatory markers.

Circulating, but not local lung, IL-5 is required for the development of antigen-induced airways eosinophilia

IL-5 is induced locally in the lung and systemically in the circulation during allergic airways eosinophilic inflammation both in humans and experimental animals. However, the precise role of local and systemic IL-5 in the development of allergic airways eosinophilia remains to be elucidated. In our current study, we demonstrate that compared with their IL-5(+/+) counterparts, IL-5(-/-) mice lacked an IL-5 response both in the lung and peripheral blood, yet they released similar amounts of IL-4, eotaxin, and MIP-1alpha in the lung after ovalbumin (OVA) sensitization and challenge. At cellular levels, these mice failed to develop peripheral blood and airways eosinophilia while the responses of lymphocytes, neutrophils, and macrophages remained similar to those in IL-5(+/+) mice. To dissect the relative role of local and systemic IL-5 in this model, we constructed a gene transfer vector expressing murine IL-5. Intramuscular IL-5 gene transfer to OVA-sensitized IL-5(-/-) mice led to raised levels of IL-5 compartmentalized to the circulation and completely reconstituted airways eosinophilia upon OVA challenge, which was associated with reconstitution of eosinophilia in the bone marrow and peripheral blood. Significant airways eosinophilia was observed for at least 7 d in these mice. In contrast, intranasal IL-5 gene transfer, when rendered to give rise to a significant but compartmentalized level of transgene protein IL-5 in the lung, was unable to reconstitute airways eosinophilia in OVA-sensitized IL-5(-/-) mice upon OVA-challenge, which was associated with a lack of eosinophilic responses in bone marrow and peripheral blood. Our findings thus provide unequivocal evidence that circulating but not local lung IL-5 is critically required for the development of allergic airways eosinophilia. These findings also provide the rationale for developing strategies to target circulating IL-5 and/or its receptors in bone marrow to effectively control asthmatic airways eosinophilia.

Dysregulation of monocyte differentiation in asthmatic subjects is reversed by IL-10

BACKGROUND

IL-10 can modulate the differentiation of normal monocytes to macrophages, increasing the proportion of maturing cells with a phenotype consistent with T cell suppressive activity. Analysis of the immunopathology in endobronchial biopsies from asthmatic subjects has revealed significantly reduced proportions of suppressive macrophage populations associated with chronic T-cell mediated inflammation.

OBJECTIVE

This study investigates whether the altered homeostasis within the lung macrophage populations in asthma is reflected in aberrant differentiation of peripheral blood monocytes and whether this differentiation may be influenced by IL-10.

METHODS

Monocytes from 14 normal individuals and 14 atopic asthmatics were grown in culture for 7 days in the presence or absence of IL-10, added on day 5. Double immunofluoresence studies were performed on cytospins of the differentiated macrophages using the monoclonal antibodies RFD1 and RFD7 to distinguish inductive and suppressive macrophages by their respective phenotypes. HLADR expression was quantified using the monoclonal antibody RFDR1. Macrophage function was determined by quantifying allostimulation in a mixed leucocyte reaction and by measuring TNFalpha and TGFbeta production.

RESULTS

With no cytokine addition the proportion of maturing macrophages with a suppressive phenotype (D1+D7+) at day 7 was lower in the asthmatic samples (18%) compared with normals (25%). IL-10 increased the proportion of suppressive cells in cultures of both asthmatic and normal monocytes with the increase in the asthmatic subjects (94% increase) being significantly greater than that in normal subjects (32% increase) (P<0.01). Asthmatic monocytes had a greater effect in stimulating MLR than normals (P < 0.05) but the addition of IL-10 reduced T cell proliferation in an MLR to a equivalent level in both groups.

CONCLUSIONS

These results suggest that a fundamental problem may exist in the differentiation of monocytes in asthma which may be reversed by IL-10.

A novel transforming growth factor beta2 antisense transcript in mammalian lung

Transforming growth factor (TGF) beta2 gene expression was examined in murine, rat and human lung by in situ hybridization with riboprobes. Hybridization signal was observed in a variety of cells with the sense probe, and Northern-blot analysis with this probe demonstrated the presence of a novel 3.5 kb transcript. This first report suggesting the existance of a natural TGFbeta2 antisense transcript raises the possibility that such a transcript may play a role in regulating TGFbeta2 production.

Protein kinase A inhibitors reverse histamine-mediated regulation of IL-5 secretion

Histamine and IL-5 are important autacoid mediators involved in the etiology of allergic diseases. IL-5 is the main factor of eosinophilic reactions in allergy. It has been suggested that the protein kinase A-dependent (PKA) pathway of signal transduction may play the main role in histamine-induced elevation of interleukin-5 production. This study was designed to investigate the effects of the inhibitors of regulatory and catalytic subunits of PKA on histamine-mediated elevation of IL-5 production. In our study, histamine at a concentration range of 10(-4)-10(-6) M enhanced IL-5 production in D10.G4.1 cells, a mouse Th2 helper cell line. Pretreatment of this cell line with histamine at a concentration of 10(-4) M for 6-9 h had the maximum stimulatory effects (226-420%) on IL-5 production. Other cAMP-elevating agents including forskolin and Bt2-cAMP produced similar effects. The PKA inhibitors N-[2-(methylaminoethyl]-5-isoquinoline-sulfonamide (H-8) and Rp-diastereomer of adenosine cyclic 3',5'-phosphorothioate (Rp-cAMPS) were used for the inhibition of catalytic and regulatory subunits of PKA, respectively. Pretreatment of D10.G4.1 cells with H-8 at a concentration of 10(-5) M completely prevented the effects of histamine at a concentration range of 10(-6)-10(-4) M. Rp-cAMPS at 10(-5) M also prevented histamine-induced stimulation. Neither inhibitor affected IL-5 production when tested alone. These observations suggest a role for PKA in histamine-mediated increase in IL-5 production.

Airway eosinophils, T cells, Th2-type cytokine mRNA, and hyperreactivity in response to aerosol challenge of allergic mice with previously established pulmonary inflammation

Asthma is characterized by acute episodes of nonspecific airway hyperreactivity and chronic pulmonary inflammation exacerbated by stimuli including allergen exposure. In order to reproduce the physiologic and immunologic responses that occur in asthmatic patients, we have characterized a model of antigen-induced inflammation in which allergic mice (B6D2F1) that had been challenged once with aerosolized ovalbumin and had developed a pulmonary cellular infiltrate were rechallenged 1 wk later. Pulmonary inflammation in rechallenged mice was substantially greater than that in single-challenged mice. Eosinophils and activated-memory T cells (CD44+, CD45RBlo) in bronchoalveolar lavage (BAL) fluid accumulated to higher levels and with faster kinetics in response to the second challenge than in response to the first challenge. Eosinophils in lung tissue also accumulated to higher levels but with similar kinetics in response to the second challenge than in response to the first challenge. Similarly, interleukin (IL)-4 and IL-5 steady-state mRNA levels in lung tissue increased after the second challenge and were higher than those measured after a single challenge. Furthermore, treatment of mice with an anti-IL-5 monoclonal antibody 2 h prior to rechallenge inhibited antigen induced eosinophil accumulation in the lungs. In mice challenged twice, peak in vivo bronchoconstrictor responsiveness to acetylcholine was increased following the second challenge compared with that observed following the initial challenge. In contrast, ex vivo tracheal smooth muscle contractile responsiveness to acetylcholine was not altered. Although mucus accumulation and epithelial damage in pulmonary tissue were evident in mice challenged twice, these parameters were slightly reduced compared with those seen at similar times in mice challenged once. Therefore, although these mice exhibit only slight bronchial epithelial damage, the presence of significant inflammation and airway hyperreactivity to acetylcholine as well as slightly increased baseline reactivity demonstrate important similarities with the pathophysiology of asthma.

Effect of thromboxane A2 antagonists on bronchial hyperresponsiveness induced immediately after interleukin-8 inhalation in guinea-pigs

1. Although repeated intranasal administration of interleukin-8 (IL-8) causes bronchial hyperresponsiveness (BHR) mediated via thromboxane A2 (TXA2) and airway neutrophil accumulation in guinea-pigs, the acute effect of inhaled IL-8 is unclear. We performed this study to clarify the acute effect of IL-8 on bronchial responsiveness and the role of TXA2. 2. The effects of inhaled IL-8 on bronchial responsiveness and of the TXA2 antagonists, S-1452 (0.01 and 0.1 mg kg-1) and ONO-NT-126 (1.0 or 10 micrograms kg-1), on IL-8-induced BHR were examined by use of a modified Konzett-Rössler method in guinea-pigs. 3. Inhaled IL-8 at 100 ng ml-1, which failed to induce significant changes in Pao (pressure at the airway opening), enhanced an increase in Pao induced by subsequent inhalations of ascending doses (50-200 micrograms ml-1) of methacholine and histamine, suggesting the potentiating effect of IL-8 on bronchial responsiveness. No significant leukocyte infiltration was observed histologically sixteen minutes after the IL-8 inhalation. Both S-1452 and ONO-NT-126 reduced the IL-8-induced BHR. 4. In conclusion, IL-8 rapidly causes BHR via TXA2 release in guinea-pigs.

Factors predicting food allergy

Prediction of food allergies has not been addressed systematically and to date studies have concentrated on prediction of allergic disorders in a general fashion. The current available data suggests that possibly the best predictor is the combined approach of taking into account the family history together with elevated cord blood IgE. Other indicators, such as cord blood lymphocyte responses and γ-interferon production at birth, are also discussed. Although preliminary studies seem to be promising, only studies of an unselected population with long term follow-ups will be able to show whether or not these possible predictors are of value.

Full thickness eosinophilia in oesophageal leiomyomatosis and idiopathic eosinophilic oesophagitis. A common allergic inflammatory profile?

Oesophageal leiomyomatosis and idiopathic eosinophilic oesophagitis are both extremely rare. The former is a diffuse proliferation of smooth muscle in the muscularis propria, whilst the latter is an idiopathic inflammatory condition, thought to be associated with background atopy and characterized by an infiltrate of eosinophils throughout the full thickness of the oesophagus. However, two recent cases of oesophageal leiomyomatosis showed similar full thickness infiltration of the oesophageal wall by eosinophils and this inflammatory cell infiltrate was investigated in conjunction with one case of idiopathic eosinophilic oesophagitis. All three had a similar allergic profile characterized by CD45RO-positive primed T-lymphocytes, EG2-positive (i.e., activated) eosinophils, and tryptasepositive mast cells, together with gene expression for interleukin 4. Previous descriptions of leiomyomatosis describe an association with systemic mastocytosis and urticaria and the possibility that there is a common underlying allergic component to both disorders is raised.

Does the mast cell still have a key role in asthma?

In recent years, the emerging concept of bronchial inflammation as a prominent histopathologic characteristic of asthma has profoundly modified the view of the role of the mast cell, which was traditionally thought to be linked to the release of soluble chemical mediators substantially involved in the genesis of acute, immediate bronchospasm. The finding that the production of proinflammatory cytokines by mast cells in asthmatic airways is comparable, in some circumstances, to that of T-cell origin, has led to the hypothesis that mast cells, along with T lymphocytes and eosinophils, may also contribute to the genesis of chronic, persistent asthma. This hypothesis is further supported by the finding that mast cells are able to functionally interact with B cells (promoting IgE synthesis) and T lymphocytes (acting as antigen presenting cells), thus taking part in the immune network. Moreover, mast cells produce an exclusive family of proteases (tryptases and chymases) that exert many biological actions relevant to airways inflammation and remodeling. Future studies will better explain the role of mast cells in asthma and, more specifically, the links with bone marrow-where mast cell progenitors originate-and the airways, where mast cells develop, differentiate, and assume the functions of mature cells. This article reviews recent data available on these topics.

Effect of interleukin-4 on allergen-induced arachidonic acid metabolism of rat peritoneal macrophages during immediate hypersensitivity reactions

The aim of this study was to investigate the [3H]arachidonic acid metabolism of rat peritoneal macrophages, induced by allergen (ovalbumin) and the impact of interleukin-4 on this process. We established that ovalbumin induces an increase of [3H]arachidonic acid mobilisation from membrane lipids and of [3H]arachidonic acid catabolism, principally by the 5-lipoxygenase pathway, when the macrophages are sensitized and when serum is present. The allergen effect is not modified by the presence of interleukin-4 in the culture medium of macrophages 15 h before the allergen challenge. We also showed that, whereas the basal [3H]arachidonic acid metabolism of macrophages from control and actively sensitized rats is not different, interleukin-4 increases the [3H]arachidonic acid mobilisation and catabolism by cyclooxygenase and 5-lipoxygenase pathways in macrophages from control rats although it does not in macrophages from actively sensitized rats. In macrophages from control rats, the interleukin-4 effect is diminished by the addition of IgEs to their culture medium. In summary, interleukin-4 has an enhancer effect on the macrophage arachidonic acid catabolism that depends on the sensitization condition of the cell but that has no consequences on the further increased arachidonic acid metabolism induced by the allergen.