Proinflammatory cytokines in acute asthma

Analogues of natural products yaequinolones as potential inflammatory inhibitors: Design, synthesis and biological evaluation

Inflammation is connected with a variety of diseases and there is still a need to develop more effective and safer anti-inflammatory drugs. Herein, we synthesized, resolved, and characterized eight enantiopure isomers of yaequinolone J1 (1), yaequinolone J2 (2), 4'-desmethoxyyaequinolone J1 (3), and 4'-desmethoxyyaequinolone J2 (4). The key synthetic steps were extended and 34 racemic analogues modified at the 4-aryl, the N-position, and the pyran ring were designed and synthesized. All the synthesized compounds were evaluated for their anti-inflammatory activities in RAW 264.7 cells of which 13 compounds showed significant inhibition of nitric oxide (NO) production at a concentration of 0.1 μM, which was more potent than that of indomethacin. Furthermore, compounds (-)-3, (-)-4, 5h, and 6g reduced the production of IL-6 in LPS-stimulated RAW 264.7 cells at a concentration of 50 nM. A preliminary SAR indicated that 3'-Br (5h), 4'-NO₂ (6g) on 4-phenyl and 3-bromobenzyl (7f) on the N-position were the most effective substituents. This is the first report of the anti-inflammatory yaequinolone alkaloids and the present study provided evidence for exploiting this series of highly efficacious derivatives for new anti-inflammatory agents.

Discovery, total syntheses and potent anti-inflammatory activity of pyrrolinone-fused benzoazepine alkaloids Asperazepanones A and B from Aspergillus candidus

Natural products are well established as an important resource and play an important role in drug discovery. Here, two pyrrolinone-fused benzoazepine alkaloids, (+)-asperazepanones A (1) and B (2) with a 6/7/5 ring system, together with the artifact (-)-asperazepanone A (1), were isolated from the coral-derived Aspergillus candidus fungus. Their structures including absolute configurations were elucidated by extensive spectroscopic methods, single crystal X-ray diffraction, and ECD calculations. Furthermore, total syntheses of (±)-1 and (±)-2 have been achieved starting from the commercially L-aspartic acid diethyl ester hydrochloride and monoethyl malonate in 7 and 8 steps, respectively. The key step in the syntheses was an intramolecular Friedel-Crafts reaction to build the unique tricyclic skeleton. Interestingly, (+)-2 not only showed obviously inhibitory activity against NO production, but also inhibited potent LPS-induced expression of TNF-α and IL-6 at the concentration of 0.1 μM. It thus represents a potentially promising lead for anti-inflammatory drug discovery.

Synthesis and Anti-inflammatory Evaluation of ( R)-, ( S)-, and (±)-Sanjuanolide Isolated from Dalea frutescens

The known chalcone (±)-sanjuanolide (1) can be isolated from Dalea frutescens. This study presents a convergent strategy for the first total synthesis of ( R)-, ( S)-, and (±)-sanjuanolide (1). The key step for synthesizing ( R)- and ( S)-1 was a Corey-Bakshi-Shibata enantioselective carbonyl reduction to construct the C-2″ configuration. ( R)-1 efficiently inhibited the lipopolysaccharides (LPS)-induced expression of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), while ( S)-1 produced no significant anti-inflammatory effect. ( R)-1 also effectively inhibited the mRNA expression of several inflammatory cytokines after the LPS challenge in vitro. The synthesis and biological properties of these compounds have confirmed ( R)-sanjuanolide and (±)-sanjuanolide as promising new leads for developing anti-inflammatory agents.

Detection of soluble interleukin-2 receptor and soluble intercellular adhesion molecule-1 in the effusion of otitis media with effusion

We measured sIL-2R, TNF-alpha and sICAM-1 in the sera and middle ear effusions (MEEs) of patients with otitis media with effusion (OME). Although there was no signmcant difference between the sIL-2R levels of the serous and mucoid MEEs, they were significantly higher than serum sIL-2R levels of OME patients and healthy controls. TNF-alpha levels of the mucoid MEEs were significantly higher than those of the serous type. However, TNF-alpha was rarely detected in the sera of OME patients or healthy controls. We observed significant differences between the serous and mucoid MEEs with respect to their sICAM-1 levels, which were also higher than serum slCAM-1 levels of OME patients and healthy controls. Our findings suggested that IL-2, TNF-alpha and ICAM-1 could be significantly involved in the pathogenesis of OME through the cytokine network.

Inhibitory effects of bisbenzylisoquinolines on synthesis of the inflammatory cytokines interleukin-1 and tumour necrosis factor-alpha

Synthesis of IL-1beta and TNFalpha by human monocytesmacrophages was significantly inhibited by eleven bisbenzylisoquinolines and one half-molecule (benzylisoquinoline), with IC(50) values in the muM range. The results indicate that these compounds may have value in the therapy of human diseases where these inflammatory cytokines have a central role in pathogenesis.

Release of tumour necrosis factor alpha into bronchial alveolar lavage fluid following antigen challenge in passively sensitized guinea-pigs

Five groups of ten female guinea-pigs were passively sensitized against ovalbumin (OA) (n = 9) or control guinea-pig serum (n = 1). 24 h later, they received mepyramine (0.5 mg/kg, i.p.) and 30 min later inhaled aerosols of: (A) OA (2 in 0.9% saline, 8 min, n = 4/9); (B) saline (40 min, n = 4/9); (C) LPS (40 min, Escherichia coli 0111:B4, 150 ng/kg in PBS, n = 1/9); and (D) the control animal was treated as in (C) (n = 1). Their tracheas were cannulated under pentobarbital anaesthesia and bronchial alveolar lavage (BAL) was performed with 2 x 5 ml PBS containing BSA (1%) (n = 1 group), or BSA (1%) and aprotinin (1000 KIU/ml) (n = 4 groups), at 30, 60, 90 or 120 min post-inhalations. BAL fluids recovered were centrifuged, the supernatants recovered and frozen until assayed for tumour necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) and interleukin-6 (IL-6). No TNF-alpha could be detected unless aprotinin was present in the lavaging solution. BAL fluid from OA-sensitized and control animals that had inhaled LPS contained high levels of TNF-alpha that peaked at 90 min. BAL fluid from OA sensitized animals that inhaled OA aerosols contained no detectable TNF-alpha at 30 min, but it was found in increasing amounts at 60, 90 and 120 min; TNF-alpha was not detected in fluid from any of the animals that inhaled saline. As BAL fluids were toxic to the cells used in the assays, neither IL-1 nor IL-6 could be measured. We conclude that the monokine TNF-alpha is released into BAL fluid following anaphylactic challenge of passively sensitized guinea-pigs. The presence of the antiprotease, aprotinin, in the lavaging solution is essential for the detection and measurement of TNF-alpha in BAL fluid.

Vitamin D3 correlates inversely with systemic dendritic cell numbers and bone erosion in chronic rhinosinusitis with nasal polyps and allergic fungal rhinosinusitis

Vitamin D(3) (VD(3) ) is a steroid hormone that regulates bone health and numerous aspects of immune function and may play a role in respiratory health. We hypothesized that T helper type 2 (Th2) disorders, chronic rhinosinusitis with nasal polyps (CRSwNP) and allergic fungal rhinosinusitis (AFRS) would have VD(3) deficiencies, resulting in increased mature dendritic cells (DCs) and bone erosion. We conducted a retrospective study examining VD(3) levels in patients with AFRS (n = 14), CRSwNP (n = 9), chronic rhinosinusitis without nasal polyps (CRSsNP) (n = 20) and cerebrospinal fluid leak repair (non-diseased controls) (n = 14) at time of surgery. Circulating immune cell levels were determined by immunostaining and flow cytometric analysis. Plasma VD(3) and immune regulatory factors (granulocyte-macrophage colony-stimulating factor and prostaglandin E(2) ) were measured by enzyme-linked immunosorbent assay. It was observed that CRSwNP and AFRS demonstrated increased circulating DCs, while chronic rhinosinusitis without nasal polyps displayed increased circulating macrophages. CRSwNP and AFRS were to found to have insufficient levels of VD(3) which correlated inversely with circulating numbers of mature DCs, DC regulatory factors and bone erosion. CRSsNP displayed no change in circulating DC numbers or VD(3) status compared to control, but did display increased numbers of circulating macrophages that was independent of VD(3) status. Lastly, VD(3) deficiency was associated with more severe bone erosion. Taken together, these results suggest support a role for VD(3) as a key player in the immunopathology of CRSwNP and AFRS.

Evaluation of the anti-inflammatory effect of infliximab in a mouse model of acute asthma

BACKGROUND AND OBJECTIVE

To evaluate the potential role of anti-tumour necrosis factor (TNF)-alpha mAb (infliximab) on the inflammatory response in a mouse model of acute asthma.

METHODS

BALB/c mice received intraperitoneal (i.p.) ovalbumin (OVA) on days 0 and 14, 100 microg of OVA intranasally on day 14 and 50 microg of OVA intranasally on days 25, 26 and 27. The low-dose (2.5 mg/kg) and high-dose (6.25 mg/kg) infliximab groups received i.p. infliximab before each i.p. sensitization and on challenge days 1, 6, 13, 20 and 27. The control group received i.p. injections of normal saline with alum on days 0 and 14 and normal saline without alum on days 14, 25, 26 and 27.

RESULTS

There were statistically significant decreases in the numbers of BAL fluid (BALF) neutrophils, eosinophils, as well as lung eosinophils in both the low- and high-dose infliximab groups when compared with the control OVA sensitized/challenged group. The lower dose of infliximab did not alter lung neutrophil counts, but a marked decrease was seen with the high dose of infliximab. After treatment with low and high doses of infliximab, BALF levels of regulated on activation normal T cell expressed and secreted (RANTES), granulocyte macrophage-colony stimulating factor (GM-CSF), TNF-alpha, IL-6, macrophage inflammatory protein (MIP)-2, and levels of RANTES, IL-4, GM-CSF, TNF-alpha, IL-6 and MIP-2 in lung tissue were significantly decreased when compared with the control OVA sensitized/challenged group. There was a significant decrease in BALF IL-4 only in the high-dose infliximab group.

CONCLUSIONS

These results show that an anti-TNF-alpha mAb has a considerable anti-inflammatory effect on allergen-induced lung inflammation in an animal model of acute asthma.

The role of intrinsic efficacy in determining response to a beta2-agonist in acute severe asthma

BACKGROUND

Current guidelines recommend repeated doses of albuterol for the emergency treatment of acute asthma. However, approximately one-third of patients show little or no initial response to this partial beta(2)-agonist.

METHODS

We conducted a randomized, double-blind, proof-of-concept study to investigate whether a full beta(2)-agonist, isoproterenol, offers a therapeutic advantage in adults presenting with acute severe asthma (FEV(1)<50%) who fail to respond to an initial treatment of the partial beta(2)-agonist, albuterol. Study subjects were randomized to receive a 2-h continuous nebulization of either albuterol (7.5mg/h) (n=10, mean FEV(1)=37% predicted) or isoproterenol (7.5mg/h) (n=9, mean FEV(1)=33% predicted). Respiratory symptoms, vital signs and pulmonary function measures were collected.

RESULTS

Subjects from both treatment groups had similar baseline characteristics. The percent improvements from baseline FEV(1) at 60 and 120min were significantly higher in subjects receiving isoproterenol than those receiving albuterol (44 vs. 17% and 63 vs. 24%, respectively, P<0.05). The change in symptoms measured by the modified Borg score was also significantly greater in subjects receiving isoproterenol (P<0.01). Both treatments were well tolerated, though the mean increase in pulse rate at 60 and 120min (21 vs. 1 and 23 vs. 6beats/min, respectively, P<0.05) and the mean change in serum potassium at 120min (-0.52 vs. -0.07meq/L, P<0.05) from baseline were significantly greater in the isoproterenol group.

CONCLUSIONS

Our data suggest that in subjects presenting with acute severe asthma who fail to show an initial response to albuterol, the use of a beta(2)-agonist of higher intrinsic efficacy can be more effective in improving lung function and symptoms.

Activation of peroxisome proliferator-activated receptors in human airway smooth muscle cells has a superior anti-inflammatory profile to corticosteroids: relevance for chronic obstructive pulmonary disease therapy

Airway smooth muscle is actively involved in the inflammatory process in diseases such as chronic obstructive pulmonary disease and asthma by 1) contributing to airway narrowing through hyperplasia and hypertrophy and 2) the release of GM-CSF and G-CSF, which promotes the survival and activation of infiltrating leukocytes. Thus, the identification of novel anti-inflammatory pathways in airway smooth muscle will have important implications for the treatment of inflammatory airway disease. This study identifies such a pathway in the activation of peroxisome proliferator-activated receptors (PPARs). PPAR ligands are known therapeutic agents in the treatment of diabetes; however, their role in human airway disease is unknown. We demonstrate, for the first time, that human airway smooth muscle cells express PPAR alpha and -gamma subtypes. Activation of PPAR gamma by natural and synthetic ligands inhibits serum-induced cell growth more effectively than does the steroid dexamethasone, and induces apoptosis. Moreover, PPAR gamma activation, like dexamethasone, inhibits the release of GM-CSF. However, PPAR gamma ligands, but not dexamethasone, similarly inhibits G-CSF release. These results reveal a novel anti-inflammatory pathway in human airway smooth muscle, where PPAR gamma activation has additional anti-inflammatory effects to those of steroids. Hence, PPAR ligands might act as potential treatments in human respiratory diseases.

Serum cytokine levels, cigarette smoking and airway responsiveness among pregnant women

BACKGROUND

Five to twenty percent of healthy, nonasthmatic individuals exhibit airway hyperreactivity. Because cytokines are important intermediates in airway responses, we investigated the relationship between serum cytokines and airway responsiveness in a well-characterized population of pregnant women.

METHODS

We analyzed serum levels of interleukin-4 (IL-4), IL-5, IL-6, interferon-gamma (IFN-gamma), and granulocyte-macrophage colony-stimulating factor (GM-CSF) in frozen sera from 240 pregnant nonasthmatic subjects from a previous study of airway responsiveness and preterm labor for their relationship to methacholine challenge test results.

RESULTS

Serum IFN-gamma and GM-CSF levels were significantly related to levels of methacholine airway responsiveness among nonasthmatics in this population. Nonasthmatics with PD(20) <8 micromol (the highest level of airway responsiveness) had the highest mean serum levels of IFN-gamma and GM-CSF, those with 8 <or= PD(20) <or= >50 micromol had intermediate levels, and those with PD(20) >>50 mol had the lowest levels. Both serum IFN-gamma and GM-CSF levels were also significantly related to the log dose-response slope for methacholine responsiveness. These relationships were confirmed in a multiple linear regression analysis controlling for age, ethnic background, and cigarette smoking. Current smoking was uniformly associated with decreased cytokine levels.

CONCLUSION

IFN-gamma, GM-CSF, and other cytokines may be useful serum markers in population studies of airway responsiveness.

Cellular and cytokine immunoregulation in patients with chronic obstructive pulmonary disease and bronchial asthma

BACKGROUND

Different forms of chronic airway inflammation may involve diverse pathogenic elements. In general, deficient defence response is a feature of chronic obstructive pulmonary disease (COPD), whereas distorted immunoregulatory mechanisms lead to development of asthmatic symptoms. In addition to diverse effector mechanisms, the cellular and humoral elements participating in the development of immune response may appear to be different in COPD and bronchial asthma (BA) patients.

AIMS

To evaluate the immunoregulatory properties of T cells and monocytes in cultures of peripheral blood mononuclear cells (PBMC) and to determine the chosen cytokine profiles in COPD and BA patients.

METHODS

The microcultures of PBMC from COPD and BA patients were assessed for the T-cell response to mitogens, saturation of interleukin (IL)-2 receptors, T-cell suppressive activity and monokine influence on lymphocyte proliferation. Concomitantly, the cytokine (IL-1beta, interleukin-1 receptor antagonist, tumour necrosis factor-alpha, IL-4, IL-6, IL-8) concentrations were determined in the serum, the broncho-alveolar lavage fluid and in the culture supernatants.

RESULTS

The T-lymphocyte reactions (response to phytohaemagglutinin, IL-2 receptor saturation, suppressive activity) were lower in BA patients than in COPD patients. Reversely, the immunogenic activity of monocytes (IL-1beta versus IL-1ra production) was higher in BA patients than in COPD patients. The highest values of cytokine concentrations were found in the culture supernatants. The concentrations of tumour necrosis factor-alpha, IL-4, IL-6 and IL-8 were significantly higher and the concentration of IL-1ra was lower in BA patients than in COPD patients.

CONCLUSION

The assessments of cellular immunoregulatory properties and cytokine profiles in the cultures of blood mononuclear cells may prove helpful for diagnostic and therapeutic discrimination between BA and COPD patients.

Comparison of effects of anti-IL-3, IL-5 and GM-CSF treatments on eosinophilopoiesis and airway eosinophilia induced by allergen

Allergic inflammation is dominated by eosinophils. IL-3, IL-5, and GM-CSF are involved in production and activation of eosinophils. IL-5 has been reported to be crucial for the induction of airway eosinophilia. However, the contribution of IL-3 and GM-CSF to allergic airway inflammation remains to be determined. To address this issue, ovalbumin-sensitized Balb/c mice were repeatedly exposed to allergen via airway route. Animals were pretreated intraperitoneally with neutralising anti-IL-3, anti-IL-5 and/or anti-GM-CSF antibodies. Newly produced inflammatory cells were pulse-labelled with the thymidine analogue 5-bromo-2'-deoxyuridine (BrdU), which is incorporated into DNA during the cell mitosis. BAL and bone marrow cells were collected 24 h after the last allergen exposure, and differential cell counts and immunocytochemical detection of BrdU-labelled cells were performed. Anti-IL-5 strongly reduced both BAL and bone marrow eosinophilia, as well as the number of BrdU-positive BAL-granulocytes. In contrast, anti-IL-3 and anti-GM-CSF alone had little and no inhibitory effect on these responses, respectively. Even the combined treatment with anti-IL-3 and anti-GM-CSF showed only a non-significant tendency to attenuate these responses. These data suggest that the efficacy of treatments with anti-IL-3 and anti-GM-CSF is much weaker than that with anti-IL-5. IL-5 may be the preferred target to block eosinophilia in allergic diseases.

Measurement of inflammatory mediators of eosinophils and lymphocytes in blood in acute asthma: serum levels of ECP influence the bronchodilator response

The aim of this study was to assess the relevance of immunoinflammatory markers on the response to short acting beta(2)-agonist in acute asthma exacerbation. Thus, we measured serum eosinophil cationic protein (ECP) levels and sIL-2R at acute exacerbation in 52 adult patients with atopic asthma, and assessed forced expiratory volume in 1 s (FEV(1)) before and after the administration of aerosolized salbutamol. After a cumulative dose of salbutamol causing a 10% improvement in FEV(1) from baseline [CD10, i.e. cumulative doses of salbutamol (800 microg) causing an improvement in FEV(1) from baseline to 10%] the patients were divided into two groups: group A with CD <10 and group B with CD >10. The bronchodilator response, as defined by a DeltaFEV(1) (percentage of predictive value of FEV(1)) of > or =10 predictive value, was shown by 40% of the patients. After 200, 400 and 800 microg of salbutamol, significant differences of FEV(1) with respect to baseline values were, respectively, p = 0.049, 0.0039 and 0.0014. In contrast, no significant difference of the means of FEV(1) between the doses of salbutamol was observed. Significant differences of DeltaFEV(1) between 200 and 400 microg (p = 0.0002) and between 200 and 800 microg (p < 0.0001) were observed, but not between 400 and 800 microg of salbutamol. There were significant correlations between baseline values of predictive FEV(1) and serum ECP levels (rho = -0.60, p < 0.0001) and sIL-2R levels (rho = -0.35, p = 0.01) respectively. Besides, a correlation between DeltaFEV(1) and serum ECP levels (rho = -0.53, p < 0.0001) was observed, whereas no correlation was found between DeltaFEV(1) and sIL-2R. By analyzing differences between the two groups (A and B) for serum ECP levels, sIL-2R and blood eosinophil count, a significant difference was found for serum ECP levels. We conclude that subjects with acute exacerbation of asthma show high serum levels of ECP and sIL-2R and, more interestingly, that the response to brochodilator was higher in patients with lower serum ECP levels.

Suppression of granulocyte/macrophage colony-stimulating factor release from human monocytes by cyclic AMP-elevating drugs: role of interleukin-10

1. Granulocyte/macrophage colony-stimulating factor (GM-CSF) is a pro-inflammatory cytokine secreted by cells of the monocyte/macrophage lineage and has been implicated in the pathogenesis of bronchitis and asthma. 2. In the present study we have evaluated the effect of several cyclic AMP-elevating agents on lipopolysaccharide (LPS)-induced GM-CSF release from human monocytes and the extent to which the anti-inflammatory cytokine, interleukin (IL)-10, is involved. 3. LPS evoked a concentration-dependent generation of GM-CSF from human monocytes that was inhibited, at the mRNA and protein level, by 8-Br-cyclic AMP, cholera toxin, prostaglandin E2 (PGE2) and a number of structurally dissimilar phosphodiesterase (PDE) 4 inhibitors. 4. Pre-treatment of monocytes with a concentration of an anti-IL-10 monoclonal antibody that abolished the inhibitory action of a maximally effective concentration of exogenous human recombinant IL-10, significantly augmented LPS-induced GM-CSF generation. This effect was associated with a parallel upwards displacement of the concentration-response curves that described the inhibition of GM-CSF by PGE2, 8-Br-cyclic AMP and the PDE4 inhibitor, rolipram, without significantly changing the potency of any drug. Consequently, the maximum percentage inhibition of GM-CSF release was reduced. Further experiments established that the reduction in the maximum inhibition of GM-CSF release seen in anti-IL-10-treated cells was not due to functional antagonism as rolipram, PGE2 and 8-Br-cyclic AMP were equi-effective at all concentrations of LPS studied. 5. These data indicate that cyclic AMP-elevating drugs attenuate the elaboration of GM-CSF from LPS-stimulated human monocytes by a mechanism that is not mediated via IL-10. Suppression of GM-CSF from monocytes may explain, at least in part, the efficacy of PDE4 inhibitors in clinical trials of chronic obstructive pulmonary disease.

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.

Soluble interleukin-2 receptor and interleukin-4 in sera of asthmatic children before and after a prednisolone course

BACKGROUND

Cytokine-mediated interactions among inflammatory cells may play a role in the pathogenesis of bronchial asthma.

OBJECTIVE

To understand the role of soluble interleukin-2 receptor (sIL-2R) and interleukin-4 (IL-4) in the disease activity of acute asthma, changes in serum concentrations of sIL-2R and IL-4 elaborated by activated T-lymphocyte before and after prednisolone therapy with clinical improvement were determined in the present study.

METHODS

Circulating levels of sIL-2R and IL-4 in sera from 15 normal control subjects and in sera from 20 allergic asthmatic children with acute exacerbation and in a stable condition were determined by using commercially available ELISA kits.

RESULTS

The mean concentration of serum sIL-2R was significantly higher in acute exacerbation than in children with stable asthma (368.9 +/- 395.4 pg/mL vs 291.2 +/- 361.0 pg/mL; P < .01) or in control subjects (124.6 +/- 17.8 pg/mL; P < .001). The mean concentration of serum IL-4 was higher in acute exacerbation (5.82 +/- 1.10 pg/mL) and in stable asthmatic patients (6.73 +/- 2.83 pg/mL) versus control group subjects (5.54 +/- 1.20 pg/mL). However, the difference was not statistically significant among the three study groups.

CONCLUSIONS

This study provides further evidence that changes in serum IL-2R may serve as an objective indicator for clinical outcome of allergic asthmatic patients.

p38 MAP kinase and MKK-1 co-operate in the generation of GM-CSF from LPS-stimulated human monocytes by an NF-kappa B-independent mechanism

1. The extent to which the p38 mitogen-activated protein (MAP) kinase and MAP kinase kinase (MKK)-1-signalling pathways regulate the expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) from LPS-stimulated human monocytes has been investigated and compared to the well studied cytokine tumour necrosis factor-alpha (TNF alpha). 2. Lipopolysaccharide (LPS) evoked a concentration-dependent generation of GM-CSF from human monocytes. Temporally, this effect was preceded by an increase in GM-CSF mRNA transcripts and abolished by actinomycin D and cycloheximide. 3. LPS-induced GM-CSF release and mRNA expression were associated with a rapid and time-dependent activation of p38 MAP kinase, ERK-1 and ERK-2. 4. The respective MKK-1 and p38 MAP kinase inhibitors, PD 098059 and SB 203580, maximally suppressed LPS-induced GM-CSF generation by >90%, indicating that both of these signalling cascades co-operate in the generation of this cytokine. 5. Electrophoretic mobility shift assays demonstrated that LPS increased nuclear factor kappa B (NF-kappa B) : DNA binding. SN50, an inhibitor of NF-kappa B translocation, abolished LPS-induced NF-kappaB : DNA binding and the elaboration of TNFalpha, a cytokine known to be regulated by NF-kappaB in monocytes. In contrast, SN50 failed to affect the release of GM-CSF from the same monocyte cultures. 6. Collectively, these results suggest that the generation of GM-CSF by LPS-stimulated human monocytes is regulated in a co-operative fashion by p38 MAP kinase- and MKK-1-dependent signalling pathways independently of the activation of NF-kappa B.

Secretion of adrenocorticotropic hormone induced by allergen inhalation in patients with atopic asthma

Allergen inhalation in atopic patients results in cytokines production or release of preformed cytokines, some of which are known to induce adrenocorticotropic hormone (ACTH) secretion in experimental conditions. We examined whether allergen inhalation can induce ACTH secretion in vivo. A significant elevation of ACTH levels was observed in 2 and 24 hr after allergen inhalation challenge. However, methacholine challenge with the same degree of airflow limitation did not induce ACTH elevation, indicating that this may not be due to bronchoconstriction per se. Our results indicate that allergen inhalation can trigger ACTH secretion in patients with atopic asthma.

Eosinophil-adhesion-inducing activity produced by antigen-stimulated mononuclear cells involves GM-CSF

BACKGROUND

The initial step of eosinophil accumulation in allergic inflammation is adhesion of circulating eosinophils to vascular endothelial cells (EC). There is evidence that the adhesive property of circulating eosinophils is upregulated following antigen exposure. Although the exact mechanism remains to be established, cytokine(s) produced by antigen-stimulated mononuclear cells is (are) likely key factor(s).

OBJECTIVE

The objective of this study was to examine the factor(s) responsible for eosinophil adhesion and migration induced by the antigen-stimulated mononuclear cells obtained from atopic asthmatics.

METHODS

Peripheral blood mononuclear cells (PBMC) isolated from house-dust-mite-sensitive bronchial asthmatics were cultured for 96 h in the presence or absence of 1 microg/ml Dermatophagoides farinae (Df) antigen. Eosinophils were isolated from peripheral blood of healthy subjects. Eosinophil-adhesion-inducing activity in the culture supernatants of PBMC was examined by the ability to modify the adhesion of eosinophils to human pulmonary microvascular endothelial cells (HPMEC) in the presence or absence of anti-cytokine/chemokine antibodies. Eosinophil migration induced by the supernatants was also examined.

RESULTS

Eosinophil adhesion to HPMEC was significantly augmented by the supernatants of Df-stimulated PBMC, which was significantly inhibited by anti-GM-CSF, but not by anti-IL-5, anti-RANTES, or isotype-matched controls. On the other hand, eosinophil migration induced by the supernatants was inhibited by anti-GM-CSF and partly by anti-RANTES.

CONCLUSION

Both eosinophil adhesion and migration induced by the antigen-stimulated PBMC involve GM-CSF. In contrast, RANTES is involved only in the eosinophil migration. These molecules may participate in the development of eosinophil accumulation at the allergic inflammation sites.

Exposure to systemic prednisolone for 4 hours reduces ex vivo synthesis of GM-CSF by bronchoalveolar lavage cells and blood mononuclear cells of mild allergic asthmatics

BACKGROUND

In acute severe asthma, the earliest clinical effects of glucocorticosteroids occur from 4 to 5 h after systemic administration, but the mechanisms are unclear. In persistent asthma, corticosteroids are thought to suppress airway inflammation by modulating the expression of adhesion molecules, enzymes, and leucotactic cytokines, including granulocyte-macrophage colony stimulating factor (GM-CSF). GM-CSF is also overexpressed in the airways of symptomatic asthmatics.

OBJECTIVES

To examine the early effects of systemic corticosteroids on cytokine expression, we investigated whether ex vivo synthesis of GM-CSF is suppressed in the bronchoalveolar lavage (BAL) cells and peripheral blood mononuclear cells (PBMCs) of normal and mild allergic asthmatic subjects obtained 4 h after a single intravenous dose of prednisolone.

METHODS

In a randomized, double-blind, placebo-controlled study, BAL cells and PBMCs were obtained from mild atopic asthmatic patients (n = 9) and normal subjects (n = 9) 4 h after an intravenous bolus dose of 80 mg prednisolone, and cultured for 0-18 h in the presence or absence of lipopolysaccharide (LPS; 10 microg/mL). Enzyme immunoassay was used to assess GM-CSF levels in BAL cell and PBMC culture supernatants, and in BAL fluid.

RESULTS

After placebo, GM-CSF synthesis tended to be higher in BAL cells from asthmatics than in normals. LPS stimulation significantly increased median (interquartile range) GM-CSF synthesis by BAL cells ex vivo from 16.4 (23 to 74) to 35.8 (3-148) pg/106 cells in normals (P < 0.05), and from 59 (9 to 204) to 134 (24-288) pg/106 cells in asthmatics (P < 0.01). After intravenous prednisolone, the rise in GM-CSF production induced in BAL cells by LPS was completely abolished in both subject groups. In PBMCs of placebo-treated asthmatics (but not normals), LPS stimulated median GM-CSF synthesis from 164 (110 to 300) to 314 (235-485) pg/106 cells (P = 0.02), and this was blocked by intravenous prednisolone.

CONCLUSIONS

LPS-stimulated GM-CSF synthesis ex vivo is abolished in BAL cells of mild asthmatic and normal subjects, and in PBMCs of asthmatics, obtained 4 h after a single intravenous dose of prednisolone. Suppression of GM-CSF synthesis in airway and blood leucocytes may contribute to the early clinical efficacy of systemic glucocorticoids in acute allergic asthma.

IL-5 Increases Expression of 5-Lipoxygenase-Activating Protein and Translocates 5-Lipoxygenase to the Nucleus in Human Blood Eosinophils

Cysteinyl-leukotrienes are potent bronchoconstrictor mediators synthesized by the 5-lipoxygenase (5-LO) pathway. Eosinophilopoietic cytokines such as IL-5 enhance cysteinyl-leukotriene synthesis in eosinophils in vitro, mimicking changes in eosinophils from asthmatic patients, but the mechanism is unknown. We hypothesized that IL-5 induces the expression of 5-LO and/or its activating protein FLAP in eosinophils, and that this might be modulated by anti-inflammatory corticosteroids. Compared with control cultures, IL-5 increased the proportion of normal blood eosinophils immunostaining for FLAP (65 ± 4 vs 34 ± 4%; p &lt; 0.0001), enhanced immunoblot levels of FLAP by 51 ± 14% (p = 0.03), and quadrupled ionophore-stimulated leukotriene C4 synthesis from 5.7 to 20.8 ng/106 cells (p &lt; 0.02). IL-5 effects persisted for 24 h and were abolished by cycloheximide and actinomycin D. The proportion of FLAP+ eosinophils was also increased by dexamethasone (p &lt; 0.0001). Neither IL-5 nor dexamethasone altered 5-LO expression, but IL-5 significantly increased 5-LO immunofluorescence localizing to eosinophil nuclei. Compared with normal subjects, allergic asthmatic patients had a greater proportion of circulating FLAP+ eosinophils (46 ± 6 vs 27 ± 3%; p &lt; 0.03) and a smaller IL-5-induced increase in FLAP immunoreactivity (p &lt; 0.05). Thus, IL-5 increases FLAP expression and translocates 5-LO to the nucleus in normal blood eosinophils in vitro. This is associated with an enhanced capacity for cysteinyl-leukotriene synthesis and mimics in vivo increases in FLAP expression in eosinophils from allergic asthmatics.

Non-invasive biomarkers of asthma

Several non-invasive biomarkers of inflammation in asthma such as exhaled NO and eosinophil numbers in induced sputum have been developed. Their usefulness in experimental asthma models has been validated but there is less experience in their use in clinical practice. Because specific cooperation may be needed from the patient in producing samples from the airways for assay of biomarkers, younger children may not be suitable. Specific experience in these age groups is required. There remains a need to examine these biomarkers in patients from the mild asymptomatic to the more symptomatic difficult asthmatic in longitudinal studies. Is it useful to monitor these biomarkers as a response to treatment rather than the more conventional measures of symptoms and lung function measurements for prevention of exacerbations and long-term reduction in lung function? Answers to such issues will be crucial in adopting the routine measurement of certain biomarkers from the airways in the assessment of asthma severity and control.

Alterations of T-lymphocyte subsets, soluble IL-2 receptor, and IgE in peripheral blood of children with acute asthma attacks

BACKGROUND

T-cell activation and alteration of cytokines are involved in the pathogenesis of atopic asthma. However, the profile of circulating T-lymphocyte subsets, related cytokines, and plasma IgE during acute asthma attacks is still unclear.

OBJECTIVE

In an attempt to illustrate the dynamics of these parameters in asthma attacks, we investigated the changes of T-cell subsets, lymphocyte activation, soluble IL-2R, and IgE in peripheral blood in children during and after acute asthma attacks.

METHODS

This study was carried out in a cohort of Chinese children (n = 59) with acute asthma attacks. Immunoassays were performed when the patients had acute attacks before treatment, and the patients were reexamined in the 4 weeks after the resolution of acute attacks with therapy. Paired t tests were used for the statistical analysis of these patients to compare the data obtained during and after the acute attacks. Twenty healthy, age-matched subjects were used as normal control subjects. Nine children with long-term stable asthma were used as control subjects with stable asthma.

RESULTS

CD3+, CD4+, CD8+, and IL-2R+ (CD25+) cells; plasma soluble IL-2 receptor; and IgE were significantly higher in patients with acute attacks than in control subjects. (P <.05, P <.05, P <.001, P <.05, P <.0001, and P <.0001, respectively). Immunoelectron microscopy exhibited an increased expression of IL-2R on lymphocytes in acute attacks as compared to control subjects. The abnormalities returned to normal, with the exception of IgE, when clinical remission was achieved after treatment. Correlation analyses revealed a positive relationship between plasma IgE and soluble IL-2R in asthma attacks (r = 0.83, P =.0001). Plasma IgE and soluble IL-2R of those who were in remission positively correlated with their production in acute attacks (r = 0.58, P =.001 and r = 0.71, P =.0001, respectively).

CONCLUSION

This study suggests that (1) the percentage of CD4+, CD8+, or IL-2R+ lymphocytes in peripheral blood was significantly elevated during acute attacks and returned to normal ranges after complete remission was achieved; (2) plasma soluble IL-2R is a sensitive marker for asthma activity; and (3) atopic asthmatic children seem to have a hereditary predisposition of having higher levels of soluble IL-2R in asthma attacks, coinherited with the trait of IgE.

Serum levels of soluble interleukin-2 receptor at acute asthma exacerbation: relationship with severity of exacerbation and bronchodilator response

BACKGROUND

T lymphocytes play a central role in the regulation of airway inflammation in asthma, and T cell activation appears to be a characteristic feature of acute asthma. It is not clear, however, whether this is proportional to the severity of acute asthma and is directly related to airway inflammation relevant to airflow obstruction during acute asthma. It is presumed that the extent to which bronchoconstriction or inflammation contributes to airflow obstruction in acute asthma may determine responsiveness to bronchodilator therapy.

METHODS

Fifty asthmatic children who visited the emergency room due to acute exacerbation were studied. Serum levels of soluble interleukin-2 receptor (sIL-2R), a marker of T cell activation, were measured at the time of acute exacerbation and of clinical remission. At acute exacerbation, FEV1 was assessed before and after the administration of aerosolized salbutamol.

RESULTS

The mean (+/-SD) serum level of sIL-2R at acute exacerbation (854+/-248 U/ml) was significantly higher (p<0.01) than at clinical remission (676+/-211 U/ml). It correlated positively with the severity of exacerbation (r = 0.47, p<0.01), but showed no significant relationship with bronchodilator response (r = -0.17, p = 0.20).

CONCLUSION

A higher serum level of sIL-2R at acute exacerbation was associated with more severe exacerbation but not with lower bronchodilator response. These findings suggest that in the context of acute asthma, T cell activation is proportional to disease activity, but its relationship to airway inflammation relevant to the genesis of airflow obstruction remains obscure.

Compartmentalized transgene expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) in mouse lung enhances allergic airways inflammation

To investigate the role of GM-CSF in asthmatic airways inflammation, we have targeted GM-CSF transgene to the airway cells in a mouse model of ovalbumin (OVA)-induced allergic airways inflammation, a model in which there is marked induction of endogenous IL-5 and IL-4 but not GM-CSF. Following intranasal delivery of a replication-deficient adenoviral gene transfer vector (Ad), transgene expression was found localized primarily to the respiratory epithelial cells. Intranasal delivery of 0.03 x 10(9) plaque-forming units (PFU) of AdGM-CSF into naive BALB/c mice resulted in prolonged and compartmentalized release of GM-CSF transgene protein with a peak concentration of approximately 80 pg/ml detected in bronchoalveolar lavage fluid (BALF) at day 7, but little in serum. These levels of local GM-CSF expression per se resulted in no eosinophilia and only a minimum of tissue inflammatory responses in the lung of naive mice, similar to those induced by the control vector. However, such GM-CSF expression in the airways of OVA-sensitized mice resulted in a much greater and sustained accumulation of various inflammatory cell types, most noticeably eosinophils, both in BALF and airway tissues for 15-21 days post-OVA aerosol challenge, at which times airways inflammation had largely resolved in control mice. While the levels of IL-5 and IL-4 in BALF and the rate of eosinophil apoptosis were found similar between different treatments, there was an increased number of proliferative leucocytes in the lung receiving GM-CSF gene transfer. Our results thus provide direct experimental evidence that GM-CSF can significantly contribute to the development of allergic airways inflammation through potentiating and prolonging inflammatory infiltration induced by cytokines such as IL-5 and IL-4.

Granulocyte macrophage colony-stimulating factor augments ICAM-1 and VCAM-1 activation of eosinophil function

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are members of the immunoglobulin superfamily adhesion molecules on vascular endothelium and important in the development of eosinophil (EOS) accumulation in allergic inflammation. To define the role of these adhesion proteins in EOS inflammation, peripheral blood EOS from allergic donors were incubated in either buffer (control)-, recombinant human (rh)-VCAM-1-, or rh-ICAM-1-coated plates, and the effects of these adhesion proteins on EOS effector functions were determined. VCAM-1 induced spontaneous EOS adhesion whereas EOS adhesion to ICAM-1 required a second signal, such as granulocyte macrophage colony-stimulating factor (GM-CSF). Although only VCAM-1 stimulated EOS superoxide anion (O2-) generation, the addition of GM-CSF (100 pM) to the reactions resulted in a greater and equivalent production of O2- with VCAM-1 and ICAM-1. In the presence of GM-CSF, ICAM-1 and VCAM-1 caused significant release of EOS-derived neurotoxin (EDN). Moreover, only ICAM-1 (no GM-CSF) promoted calcium ionophore A23187 (0.2 microM)-induced EOS leukotriene C4 (LTC4). Enhanced O2- generation, EDN release, and LTC4 generation observed with ICAM-1 and VCAM-1 were significantly inhibited by anti-beta2-integrin antibody. These results suggest that ICAM-1 and VCAM-1 are important in determining the eventual function of airway EOS.

Albuterol does not antagonize the inhibitory effect of dexamethasone on monocyte cytokine release

Beta2-adrenoceptor agonists given by the inhaled route are the most effective bronchodilators known, yet high doses of these drugs may be associated with an increase in asthma mortality and morbidity. One theory for this paradox is that chronic use of beta2-adrenoceptor agonists compromises the anti-inflammatory action of glucocorticosteroids. This hypothesis derives from the ability of albuterol and fenoterol to inhibit the interaction of the glucocorticosteroid receptor (GR) with proinflammatory transcriptional activators acting on the promoter region of certain target genes that encode cytokines such as tumor necrosis factor-alpha (TNF alpha) and granulocyte/macrophage colony-stimulating factor (GM-CSF). However, the functional relevance of these results has not been formally investigated. We have tested the hypothesis that albuterol reduces the ability of dexamethasone to inhibit the generation of TNF alpha and GM-CSF from lipopolysaccharide (LPS)-stimulated human monocytes. Pretreatment of human monocytes with albuterol (1 and 100 microM) for 5 and for 180 min inhibited maximally TNF alpha generation by approximately 25%. However, regardless of the concentration of albuterol, or the time of preincubation, the inhibitory effect of dexamethasone was not significantly affected with respect to the EC50 or the maximal effect produced. Qualitatively identical data were obtained when GM-CSF release was used as an index of monocyte activation. We conclude that high concentrations of albuterol do not compromise the ability of dexamethasone to suppress the generation of TNF alpha and GM-CSF from LPS-stimulated human monocytes.

Circulating levels of soluble interleukin-6 receptor in patients with bronchial asthma

In the search for markers of airway inflammation, we investigated the role of soluble interleukin-6 receptor (sIL-6R) in patients with bronchial asthma. Serum levels of sIL-6R were measured in 20 patients with stable asthma and in 18 healthy control subjects by means of a sandwich enzyme-linked immunosorbent assay. Such levels were also evaluated during a spontaneous attack of asthma (n = 10) as well as that after allergen inhalation (n = 7). Results were compared with those observed during the stable state and after the inhalation of methacholine. Serum levels of sIL-6R in asthmatic patients (132 +/- 31 ng/ml) significantly exceeded those of control subjects (111 +/- 16 ng/ml) (p < 0.05). These levels showed no correlation with such clinical variables as nonspecific bronchial hyperreactivity, atopic status, or serum concentration of IgE. Serum sIL-6R levels observed during an asthmatic attack versus those during the stable state (4 wk later) differed significantly. After a severe attack of asthma, such levels were significantly elevated on the second and third days, but not on Day 5. After challenge, circulating levels of sIL-6R were significantly increased 24 h after the inhalation of allergen but not of methacholine. Results suggest that serum levels of sIL-6R are increased in patients with asthma and are further increased during a spontaneous attack or that provoked by the inhalation of allergen. Thus, serum sIL-6R may reflect inflammation of the airway. Further studies are indicated to determine the clinical significance and the application of serum levels of sIL-6R in evaluating asthmatic patients.

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.

Molecular events in allergic inflammation: experimental models and possible modulation

In recent years, a complex molecular network involving cytokines kinins and adhesion molecules has been demonstrated to operate in allergic inflammation. In particular, the adhesion machinery plays a crucial role for the recruitment and locomotion of the inflammatory cells and the Intercellular Adhesion Molecule 1 (ICAM-1) is a hallmark of the allergic inflammatory process. The role and possible modulation of ICAM-1 can be investigated using both eye and nose experimental models. Conjunctival and nasal epithelium are easy to study either under natural allergen exposure or after specific/aspecific provocation tests; furthermore the nasal/conjunctival challenge is well tolerated by the patients. These experimental models have allowed us to investigate in vivo the antiallergic properties of several compounds. Many of the new antihistamines, but also deflazacort and local nasal immunotherapy, were demonstrated capable of reducing both inflammatory infiltration and ICAM-1 expression on epithelia. Because of the central role of adhesion molecules in allergic inflammation, their pharmacological modulation can be regarded as a promising therapeutic approach.

Serum levels of soluble interleukin-2 receptor in patients with perennial allergic rhinitis before and after immunotherapy

BACKGROUND

Interleukin-2 receptor (IL-2R) exists in soluble form in sera, and the rate of release of the soluble form of IL-2R (soluble IL-2R) reflects T cell activation in vivo. Since T lymphocytes play a central role in respiratory allergic disorders, the measurement of serum levels of soluble IL-2R may be useful in analyzing the disease state of allergic disorders.

OBJECTIVE

To investigate the serum concentrations of soluble IL-2R in 48 patients with perennial allergic rhinitis and 14 nonatopic healthy controls, with special reference to the possible changes following long-term immunotherapy.

METHODS

This retrospective study included 48 patients who had had variable periods of long-term immunotherapy with Dermatophagoides farinae extracts. The duration of immunotherapy ranged from 5 to 15 years. Serum samples were collected twice from each patient, before the initiation of immunotherapy and at the time of clinical assessment of immunotherapy. All the serum samples were simultaneously used for determination of soluble IL-2R concentrations, by the use of an enzyme-linked immunosorbent assay. To serve as controls, 14 nonallergic subjects of the same age range and sex were chosen.

RESULTS

Patients with allergic rhinitis before immunotherapy had significantly higher serum levels of soluble IL-2R than nonatopic subjects. Elevated serum levels of soluble IL-2R decreased significantly following immunotherapy and the serum levels of soluble IL-2R in patients with allergic rhinitis after immunotherapy were not statistically different from those of nonatopic subjects. In addition, the percent decrease in serum soluble IL-2R correlated significantly with the duration of immunotherapy.

CONCLUSIONS

Hyperactivity of helper T cells of atopic patients is altered after long-term immunotherapy, and such immunoregulatory changes could be theoretically involved in the mechanisms of immunotherapy.

Interleukin-5 messenger RNA expression in peripheral blood CD4+ cells in asthma

BACKGROUND

IL-5 has been implicated in the pathogenesis of asthma through its regulatory role on eosinophil survival, proliferation, and effector function.

OBJECTIVE

The study was designed to investigate the relationships between IL-5 messenger RNA expression in circulating CD4+ cells and serum concentrations of eosinophil cationic protein (ECP), a marker of eosinophil activation, and disease activity in asthma.

METHODS

IL-5 gene expression was assessed semiquantitatively in ex vivo stimulated CD4+ cells by reverse transcription-polymerase chain reaction and serum ECP concentration measured from venous blood samples collected from patients with acute severe asthma before the commencement of systemic steroid therapy (day 1) and on day 7 and from patients with stable asthma and healthy volunteers.

RESULTS

IL-5 gene expression was significantly higher in patients with acute asthma before steroid treatment than in those with stable disease and healthy subjects (p < 0.0001). Similar results were obtained with serum ECP levels: levels in patients with acute asthma were highest (20.30 +/- 5.31 micrograms/L), followed by levels in patients with stable asthma (2.76 +/- 0.65 micrograms/L) and levels in normal control subjects (1.37 +/- 0.06 micrograms/L; p < 0.01 for all comparisons). Significant falls in both IL-5 expression and serum ECP level were seen on day 7 (p < 0.001) and coincided with a significant improvement in peak expiratory flow (p < 0.0001). Significant correlations were observed between IL-5 expression and ECP level (rho = 0.39, p < 0.01), IL-5 expression and peak expiratory flow (rho = -0.55, p < 0.0002), and peak expiratory flow and ECP level (rho = -0.32, p < 0.04).

CONCLUSION

Our data therefore support an important regulatory role of IL-5 on eosinophil function in human asthma in vivo.

Transfer of granulocyte-macrophage colony-stimulating factor gene to rat lung induces eosinophilia, monocytosis, and fibrotic reactions

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic cytokine whose expression is increased in numerous respiratory diseases, particularly in asthma. However, the role of GM-CSF in the pathogenesis of these conditions in vivo remains unclear. Here, we report the functional activities of GM-CSF highly expressed in rat lung after intrapulmonary transfer of the gene coding for murine GM-CSF by using an adenoviral vector. This high, transient expression of GM-CSF led to the sustained but self-limiting accumulation of eosinophils and macrophages associated with tissue injury in the lung followed by varying degrees of irreversible fibrotic reactions observed in later stages. These results suggest that GM-CSF plays a previously unrealized role in the development of respiratory conditions characterized by eosinophilia, granuloma and/or fibrosis and provide the rationale for targeting this molecule in these diseases.

Gene expression of interleukin-3 and granulocyte macrophage colony-stimulating factor in circulating CD4+ T cells in acute severe asthma

BACKGROUND

Interleukin (IL)-3 and granulocyte macrophage colony-stimulating factor (GM-CSF) may influence the inflammatory process in asthma through their regulatory role on eosinophil survival, differentiation and effector function.

OBJECTIVE

To examine the relationships between IL-3 and GM-CSF messenger (m) ribonucleic acid (RNA) expression in peripheral blood CD4+ cells and serum levels of eosinophil cationic protein (ECP), a marker of eosinophil activation, and disease activity in asthma.

METHODS

Venous blood was drawn from patients with acute severe asthma prior to the commencement of systemic steroid therapy (day 1) and 7 days afterwards (day 7), patients with stable disease and normal healthy volunteers. The capacity for expression of IL-3 and GM-CSF in ex vivo stimulated circulating CD4+ cells was assessed semi-quantitatively by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

We found that the capacity for expression of IL-3 and GM-CSF was significantly higher in acute asthmatics prior to steroid treatment (n = 24) than those in stable disease (n = 38) and healthy subjects (n = 32, P < 0.001 for IL-3 and < 0.05 for GM-CSF), but no difference was observed between the latter two groups. Further assessment made in 15 of the 24 acute asthmatics 7 days after systemic steroid treatment revealed a significant reduction in GM-CSF expression (P < 0.05) but not for IL-3. At the same time, PEF also improved significantly from 30.4 +/- 3.5% of predicted value to 72.9 +/- 7.2% (P < 0.0001) and serum ECP concentration also fell from 19.9 +/- 5.9 micrograms/L to 4.3 +/- 2.0 micrograms/L (n = 10, P < 0.01).

CONCLUSION

Our data suggest both IL-3 and GM-CSF may be important in the pathogenesis of acute severe asthma.

Cytokine expression in normal, atopic, and asthmatic subjects using the combination of sputum induction and the polymerase chain reaction

BACKGROUND

The importance of cytokines in the asthmatic inflammatory response is becoming apparent. The aim of this study was to determine whether the non-invasive method of induced sputum combined with the polymerase chain reaction would allow the detection of messenger RNA (mRNA) encoding a range of cytokines on a qualitative basis.

METHODS

Four groups were studied comprising 10 normal subjects, six atopic, 10 mild and five moderately severe asthmatic subjects. Sputum was induced by the inhalation of nebulised 3.5% saline and total RNA extracted from the expectorated cells. Expression of cytokine message within induced sputum was examined by reverse transcription and the polymerase chain reaction (PCR) using primers specific for a range of cytokines (IL-1 alpha, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, RANTES, TNF alpha, IFN alpha, IFN gamma). Presence or absence of the signal was determined at 35 and 70 cycles of PCR by electrophoretic size fractionation on ethidium bromide stained agarose gels.

RESULTS

Cytokine message was detectable in sputum by this method. All samples showed a positive result for actin control. Analysis of signal for the cytokines in all subjects showed that, at 70 cycles, IL-1, IL-5, IL-8, and TNF alpha were detected in more subjects than would be expected by chance. IL-5 mRNA was detected in more of the asthmatic patients (moderate 80%, mild 40%) than in the atopic subjects (33%), who in turn showed expression of this cytokine in more individuals than nonatopic subjects (10%).

CONCLUSIONS

The combination of sputum induction and PCR appears to be a useful, non-invasive tool to explore the chronic inflammation of asthma and possibly other lung disorders. It should enable differences between normal and asthmatic subjects to be identified for future confirmation by quantitative techniques.

Interleukin-2 receptor positive T and B cells in children with acute severe asthmatic attack

Subpopulations of interleukin-2 receptor (IL-2R)-positive CD4 and CD8 T cells and IL-2R+CD20 B cells in the peripheral blood lymphocytes as well as serum concentrations of soluble IL-2R (sIL2R) were measured in children aged 1-7 years who suffered acute severe asthmatic attack. Subpopulations of CD4+IL-2R+ cells, CD8+IL-2R+ cells and CD20+IL-2R+ cells in the peripheral blood lymphocytes at acute severe asthmatic attack phase were significantly higher than those at non-asthmatic attack phase (P < 0.02, P < 0.03 and P < 0.02, respectively). Subpopulations of CD20+IL-2R+ cells in the peripheral blood lymphocytes significantly decreased 5-10 days after acute severe asthmatic attack (at recovery phase, P < 0.02) and were significantly correlated with clinical severity of asthmatic attack (P < 0.05). These results indicated that activation of both T cells and B cells was important in the pathogenesis of acute asthmatic attack in young children.

Serum levels of soluble interleukin-2 receptor in asthma patients

We measured the serum concentration of soluble interleukin-2 receptor (sIL-2R) in asthma patients and healthy controls to evaluate T-lymphocyte activation in this disease. The SIL-2R concentrations in patients with asthma irrespective of presence of acute attacks were significantly higher than those of the controls (p < 0.001). Although the sIL-2R concentrations were similar in the patients with acute asthma and those in remission, levels in patients with moderate and severe asthma attacks were significantly higher than levels for patients in remission (p < 0.001). These results suggest that T-lymphocyte activation occurs in asthma patients and becomes more prominent during moderate and severe acute attacks.

Allergic models and cytokines

Cytokines are proinflammatory protein mediators produced by many cells, including mast cells, T lymphocytes, eosinophils, airway epithelial cells, and macrophages. There are numerous in vitro and in vivo animal and human studies showing that cytokines are released as a result of allergic reactions. Cytokines mediate allergic inflammation by activating eosinophils, promoting mast cell development, regulating immunoglobulin isotype switching to immunoglobulin E, modulating adhesion molecule regulation, and promoting both neutrophil and eosinophil chemotaxis. Furthermore, there are data that show the pro-inflammatory effects of cytokines may be blocked by cytokine antagonists. This report reviews the in vitro and in vivo animal and human studies of allergic models of cytokine production and regulation. It also discusses the specific roles of cytokines in the allergic inflammatory response and asthma.

Cellular and immunological markers of allergic and intrinsic bronchial asthma

Based on a growing body of evidence, allergic as well as intrinsic bronchial asthma have recently been defined as chronic persistent inflammatory disorders. Agreement has been reached that asthma can no longer be equated with bronchospasm only, and that the absence of reversibility of airflow obstruction does not exclude bronchial asthma. Bronchial hyperreactivity, on the other hand, although common to the vast majority of asthmatics, is not specific for bronchial asthma and provocation tests to measure bronchial hyperreactivity are not suited for routine monitoring of bronchial asthma. The clinical features of asthma are related to cellular as well as to soluble parameters of bronchial inflammation. Therefore, means of assessing and monitoring asthmatic inflammation have been investigated. Since eosinophils, T lymphocytes, mast cells, macrophages, neutrophils, epithelial cells, and structural cells, as well as various proinflammatory mediators and proteins, have been implicated in the pathogenesis of bronchial asthma, it has been anticipated that several of these cells or mediators might be either diagnostic of bronchial asthma or could serve as markers to monitor the underlying bronchial inflammation. Currently there is no diagnostic marker of bronchial asthma, which, on its own, either confirms or excludes bronchial asthma with appropriate sensitivity and specificity. Clinically the most reliable feature of bronchial asthma that seems to be related closely to the symptomatology still is the presence of eosinophils in peripheral blood, and especially in sputum. Eosinophil-derived products, particularly eosinophil granule proteins, have been investigated as markers of eosinophil participation in the pathogenesis of asthma and, comparable to eosinophil numbers themselves, are possible predictors of impending exacerbations of allergic, as well as intrinsic bronchial asthma. However, clinically their precise value in diagnosing and monitoring of bronchial asthma has not been documented convincingly and requires further investigation. Increasing data suggest that the regulation of eosinophilia is largely conveyed by interleukin-5 (IL-5) released from activated T-helper lymphocytes and possibly other cells. Therefore, T-lymphocyte activation, and especially assessment of systemic and local IL-5 levels, might be of diagnostic value and possibly useful in monitoring of inflammation in bronchial asthma in the future. A possible role and future applications for other markers of inflammation not related to eosinophils in monitoring or diagnosing bronchial asthma need to be established.

Evidence of intercellular adhesion molecule-1 expression on nasal epithelial cells in acute rhinoconjunctivitis caused by pollen exposure

Rhinoconjunctivitis caused by pollen allergy is characterized by typical signs and symptoms and mucosal infiltration by inflammatory cells during pollen season. It has been recently demonstrated that the adhesion molecule system is deeply involved in cell-to-cell interaction during inflammatory response consequent to allergic reactions. The aim of this study was to evaluate the expression of intercellular adhesion molecule-1 (ICAM-1 or CD54) on nasal epithelial cells, before and during natural seasonal exposure, in 10 allergic patients (Parietaria judaica-sensitized) and in 10 healthy volunteers, correlating this parameter with clinical and cytologic involvement. Nasal epithelial cells of allergic subjects showed a significant expression of CD54 during pollen season (p < 0.001). On the contrary, no CD54 expression was observed out of pollen season. In healthy volunteers no CD54 expression was observed both before and during pollen season. Cytologic evaluation demonstrated an infiltration by eosinophils (mainly activated [EG2+]), (p < 0.001), neutrophils (p < 0.001), and metachromatic cells (p < 0.001) during pollen season only in allergic subjects. Therefore results indicate that seasonal allergic rhinitis is characterized by an infiltration of inflammatory cells correlated with CD54 expression on nasal epithelial cells. This phenomenon is specific, being restricted only to allergic patients during pollen season.

LCB 2183 inhibits the inflammation associated with oxazolone-induced contact sensitivity

LCB 2183, an anti-allergic and potential anti-asthma compound, has been investigated for its ability to inhibit contact sensitivity in the mouse. The delayed response to epicutaneous hapten challenge in this model is a classical T-cell-mediated inflammatory reaction which is dependent on an early initiation phase. Both the early and late components of oxazolone-induced contact sensitivity were inhibited by oral administration of LCB 2183 in a dose-dependent manner. The drug appears to act on the efferent limb of the response since administration before hapten challenge was effective, while administration before the initial sensitization was not. LCB 2183 acts early in the cascade of events leading to inflammation, since the initiation phase of the response was inhibited; nonetheless, an effect of the drug on the late acting inflammatory cells cannot be ruled out. In comparison with oral prednisolone, which was also able to inhibit both the early and late components of the response, LCB 2183 was less active. Sodium cromoglycate and nedocromil sodium, which are poorly absorbed from the gastrointestinal tract, were tested by intraperitoneal administration. Neither of these agents significantly altered the delayed response and only nedocromil sodium had a limited inhibitory effect on the early initiation phase. Thus, in this model, LCB 2183 demonstrated more anti-inflammatory potential and resembled prednisolone more closely than either nedocromil sodium or sodium cromoglycate. The possible relevance of these effects in relation to the inflammation which characterizes human asthma is considered.

Endogenous production and peripheral blood levels of granulocyte-macrophage (GM-) and granulocyte (G-) colony-stimulating factors

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) are two important granulopoietic growth factors. This review will focus on the endogenous production of human GM-CSF and human G-CSF and its possible reflection in circulating levels in peripheral blood. When adequately stimulated a variety of cell-types such as monocytes/macrophages. T-lymphocytes, endothelial cells and fibroblasts can produce CSFs in vitro. G-CSF can increase to detectable levels in peripheral blood when there is a demand for granulocyte production such as acute neutropenic in conjunction with hematological disorders, chronic neutropenic conditions and acute infectious diseases in patients with or without underlying hematological disorders. G-CSF in peripheral blood is detected more often and in higher concentrations than GM-CSF. An independent regulation of GM-CSF and G-CSF secretion, quantitative differences in production and/or differences in elimination or distribution might be of importance.