Neutrophil chemotactic activity in antigen-induced late asthmatic reactions

KLF2 regulates neutrophil migration by modulating CXCR1 and CXCR2 in asthma

Neutrophils are key inflammatory cells in the immunopathogenesis of asthma. Neutrophil migration can be initiated through activation of the CXCR1 and CXCR2 receptors by CXC chemokines, such as IL-8. Although transcription factor KLF2 has been found to maintain T cell migration patterns through repression of several chemokine receptors, whether KLF2 can regulate neutrophil migration via modulation of CXCR1 and CXCR2 is unknown. Here, we aimed to explore the functions of KLF2, CXCR1 and CXCR2 in neutrophil migration in asthma and to establish a regulatory role of KLF2 for CXCR1/2. We demonstrate that with asthma aggravation, the percentages and migration rates of peripheral blood neutrophils gradually increased in asthmatic patients and the guinea pig asthma model. Correspondingly, both the KLF2 mRNA and protein levels in neutrophils were gradually reduced. While CXCR1 and CXCR2 expression was negatively correlated with KLF2. In vitro knockdown of KLF2 dramatically increased the migration of HL-60-drived neutrophil-like cells, which was accompanied by an increase in the CXCR1 and CXCR2 mRNA and protein expression levels. Taken together, our results indicate that decreased KLF2 aggravates asthma progression by promoting neutrophil migration, which is associated with the transcriptional upregulation of CXCR1 and CXCR2. The KLF2 and/or CXCR1/2 expression levels may represent an indicator of asthma severity.

Late Phase Eustachian Tube and Nasal Allergic Responses Associated with Inflammatory Mediator Elaboration

Previous work in our laboratories has documented an IgE-mediated functional obstruction of the nose and eustachian tube (ET) immediately after nasal allergen challenge. The goals of this study were to monitor changes in nasal, ET, and bronchial physiology during the 12 hours following nasal allergen challenge and to correlate these changes with the elaboration of inflammatory mediators (IM). Subjects with ragweed allergic rhinitis were challenged intranasally with 2.5 mg of ragweed/nostril, and responses were assessed by posterior rhinomanometry for the nasal airway, sonotubometry for the eustachian tube, and spirometry for the bronchial airway. Blood was obtained simultaneously for quantitating the elaboration of three functionally and metabolically distinct IM. Late nasal responses (3–12 hours postchallenge) were observed in 7 of 10 subjects, with an average decrease of 67 ± 5% in nasal conductance at an average onset time of 6.6 ± 0.8 hours postchallenge. Dual late nasal responses were observed in five subjects. Late ET responses were observed in 10 ears (50%). Two sequential late ET responses were observed in three subjects. Late bronchial responses were detected in three subjects, one of whom did not have an early response. Plasma elevations of one or more IM were detected in all late nasal responders during the late phase response period. Late nasal and ET responses in association with an allergic nasopharyngeal inflammatory process could provide an important insight into the relationship between nasal allergy and middle ear disease.

In Vitro and in Vivo Antigen-Induced Release of High-Molecular Weight Neutrophil Chemotactic Activity from Human Nasal Tissue

High molecular weight neutrophil chemotactic activity has been identified in resected human nasal polyps, inferior turbinates, and nasal secretions following antigen challenge. The estimated molecular weight, by gel filtration chromatography, was approximately 600,000. However, a heterogeneity of molecular weight in some patients was recognized. Our results suggest a possible role for high molecular weight-neutrophil chemotactic activity in the pathogenesis of hypersensitivity in the human nasal cavity.

Neutrophil extracellular traps: a walk on the wild side of exercise immunology

Intense exercise evokes a rapid and transient increase in circulating cell-free DNA (cf-DNA), a phenomenon that is commonly observed in a variety of acute and chronic inflammatory conditions. While the potential value of cf-DNA for the prediction of disease outcome and therapeutic response is well documented, the release mechanisms and biological relevance of cf-DNA have long remained enigmatic. The discovery of neutrophil extracellular traps (NETs) provided a novel mechanistic explanation for increased cf-DNA levels. Now there is increasing evidence that NETs may contribute to cf-DNA in diverse infectious, non-infectious and autoinflammatory conditions, as well as in response to acute exercise. NETs have now been firmly established as a fundamental immune mechanism used by neutrophils to respond to infection and tissue injury. On the other side, aberrant formation of NETs appears to be a driving force in the pathogenesis of autoimmunity and cardiovascular disease. Thus, the emergence of NETs in the 'exercising vasculature' raises important questions considering beneficial effects, as well as occasional adverse effects, of exercise on immune homeostasis. This review gives an overview of the current state of research into the mechanisms of how NETs are released, contribute to host defence and participate in inflammatory disorders. We discuss the impact of exercise-induced NETs, considering a potentially beneficial role in the prevention of lifestyle-related diseases, as well as putative detrimental effects that may arise in elite sports. Finally, we propose that exercise-induced cf-DNA responses could be exploited for diagnostic/prognostic purposes to identify individuals who are at increased risk of cardiovascular events or autoimmunity.

Protease-mediated house dust mite allergen-induced reactive oxygen species production by neutrophils

A growing body of evidence indicates that neutrophils may play an important role in the pathogenesis of asthma. However, the involvement of the house dust mite (HDM) in neutrophil activation associated with the pathogenesis of asthma is not fully understood yet. To address this situation, we harvested neutrophils isolated from 15 HDM-sensitized asthmatic subjects and 18 HDM-sensitized nonasthmatic subjects and measured the amounts of neutrophil reactive oxygen species (ROS) production in response to the major HDM allergens Der-f and Der-f1. Der-f and Der-f1 significantly increased ROS production in neutrophils isolated from asthmatic subjects versus nonasthmatic subjects. To assess the involvement of Der-f-specific IgE antibodies binding to their receptors in HDM allergen-induced ROS production, we examined whether neutrophils produce ROS by cross-linking of cell-bound IgE antibodies with anti-IgE. Treatment with anti-IgE antibodies did not induce ROS production by neutrophils isolated from 6 asthmatic subjects. On the other hand, pretreatment of Der-f with E-64, a cysteine protease inhibitor, eliminated Der-f-induced ROS production. These results suggest that HDM-allergen exposure may result in greater production of ROS in asthmatic patients and may be involved in the pathogenesis of asthma.

Induction of late airway response was involved in serum antigen-specific immunoglobulin G in rats

The antigen-induced immediate airway response (IAR) has been considered a form of bronchoconstriction mainly provoked by histamine and leukotriene C4/D4/E4, which are released by stimulation by antigen-specific IgE. However, the pathophysiological features of the antigen-induced late airway response (LAR) are not yet fully understood. In the present study, sensitized rats were repeatedly exposed to ovalbumin (OVA) to induce IAR and LAR, and the immunological profiles of IAR and LAR were examined. The first antigen inhalation induced only IAR but not LAR. However, the second antigen inhalation 7 days after IAR induced LAR but not IAR. Tumor necrosis factor (TNF)-alpha level in BALF in LAR was significantly higher than that in IAR, although there were no differences in histamine, leukotriene C4/D4/E4, interleukin (IL)-1beta, or IL-13 levels between IAR and LAR. Serum antigen-specific IgE titer was high in both IAR and LAR, but serum antigen-specific IgG, IgG1, and IgG2a titers were dramatically high in LAR but not IAR. There were significant correlations between antigen-specific IgG, IgG1, and IgG2a titers and LAR. Interestingly, LAR could be induced in normal rats by transfer of serum from LAR rats, which exhibited high antigen-specific IgG, IgG1, and IgG2a titers. In conclusion, these findings suggest that repeated antigen inhalation converts IAR to LAR, and that LAR is a reaction triggered by antigen-specific IgG and involving TNF-alpha. This is the first study to directly suggest the involvement of antigen-specific IgG in the induction of LAR.

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.

Neutrophils as a novel source of eosinophil cationic protein in IgE-mediated processes

The production of eosinophil cationic protein (ECP) in IgE-mediated diseases has been associated mainly with eosinophils, although no IgE-dependent ECP release has been observed in these cells. Because there is increasing evidence of neutrophil participation in allergic processes, we have examined whether human neutrophils from allergic patients were able to produce ECP by an IgE-dependent mechanism. After challenge with specific Ags to which the patients were sensitized, ECP release was detected in the culture medium. Furthermore, intracellular protein was detected by flow cytometry, immunofluorescence staining, and Western blotting. Expression at both mRNA and de novo protein synthesis were detected, respectively, by RT-PCR and radiolabeling with (35)S. Ag effect was mimicked by cell treatment with anti-IgE Abs or Abs against FcepsilonRI and galectin-3 (FcepsilonRI>galectin-3), but not against FcepsilonRII. These observations represent a novel view of neutrophils as possible source of ECP in IgE-dependent diseases.

L-selectin expression on neutrophils from allergic patients

BACKGROUND

L-selectin (CD62L) is an adhesion molecule involved in leucocyte attachment to endothelium at sites of inflammation, and it has been demonstrated that L-selectin is rapidly shed after neutrophil activation. Recently, it has been reported that there is increasing evidence of neutrophil participation in asthma and the allergic process.

OBJECTIVE

The present study was designed to determine whether an IgE-dependent mechanism can modulate L-selectin expression on the surface of neutrophils. Moreover, we analyse the potential implication of intracellular signal-transduction pathways and whether specific immunotherapy (IT), glucocorticoids and antihistamines might regulate this process.

METHODS

Peripheral blood neutrophils from three groups of donors (asthmatic group without IT treatment, IT-treated asthmatic group and healthy group) were used. Cells were challenged in vitro with the specific allergen that produced clinical symptoms in asthmatic patients and also with the allergen to which the patients were not sensitive. Neutrophils from healthy donors were also challenged with allergens. Expression of CD62L on the neutrophil surface was analysed by flow cytometry, and soluble CD62L (sCD62L) in culture supernatant by ELISA. In an attempt to discover which IgE receptor is involved, we also challenged the neutrophils with monoclonal antibody to FcepsilonRI, FcepsilonRII (CD23) and galectin-3 receptors.

RESULTS

When neutrophils from allergic patients were challenged with specific allergens that produce clinical allergy symptoms, L-selectin was down-regulated from the surface of those cells, accompanied by a concomitant up-regulation of soluble L-selectin in the supernatant. The challenge with antibodies against FCepsilonRI, FCepsilonRII (CD23) and galectin-3, induces down-modulation of L-selectin on the surface of the neutrophils in all three cases. Calphostin C, wortmannin and manoalide attenuated CD62L down-regulation, suggesting the potential implication of protein kinase C, phosphatidylinositol 3-kinase and phospholipase A(2) in the process. IT and glucocorticoids modulated allergen-dependent CD62L down-regulation, whereas antihistamines (terfenadine, loratadine and cetirizine) or nedocromil sodium did not affect the shedding of L-selectin.

CONCLUSIONS

We present evidence that the neutrophil surface expression of CD62L can be modulated by an allergen-dependent mechanism. The modulation of CD62L expression can be induced through the three receptors of IgE. This process can be affected by IT.

Comparison study between the mechanisms of allergic asthma amelioration by a cysteinyl-leukotriene type 1 receptor antagonist montelukast and methylprednisolone

We investigated the effects of cysteinyl-leukotriene (cysLT) type 1 receptor antagonist montelukast (MK) and compared them with those of methylprednisolone (MP) in an allergic asthma model. Rats sensitized to ovalbumin (OVA) received repeated intratracheal exposure to OVA for up to 3 consecutive days. Pretreatment with MK or MP before OVA exposure inhibited late airway response (LAR) and reduced cellular infiltration into the bronchial submucosa after the triple OVA. The amount of N-acetyl-leukotriene E(4) in the bile was significantly reduced by pretreatment with MK or MP, suggesting that both drugs reduced the production of cysLTs in the lungs. In the in vitro study, when the fragments of lungs that had been repeatedly pretreated with MK or MP and exposed to OVA were removed and incubated with OVA, the coaddition of either drug significantly reduced cysLT production. In contrast, the cysLT production following the addition of OVA to the lung fragments that had not received in vivo pretreatment with either drug was inhibited by MK but not by MP. These results indicate that MK and MP inhibit LAR by suppressing the infiltration of inflammatory cells into the bronchial submucosa, thereby inhibiting the production of cysLTs in the lungs, and that MK but not MP may inhibit cysLT production directly. The different effects on cysLT production between the two drugs may provide a rationale for the use of combination therapy with cysLT(1) receptor antagonists and steroids for the treatment of asthma.

Association of tumor necrosis factor polymorphisms with asthma and serum total IgE

Tumor necrosis factors (TNF; TNFA and TNFB) are major pro-inflammatory cytokines that are thought to be important in the pathogenesis of asthma. However, the functions of genetic polymorphisms in these cytokines have not been thoroughly examined in the context of asthma pathology. In an effort to discover polymorphism(s) in genes whose variant(s) have been implicated in asthma phenotypes, we examined the genetic effects of TNF (TNFA and TNFB) polymorphisms on asthma and total serum IgE level. Seven common single-nucleotide polymorphisms (SNP) in TNF genes were genotyped in a Korean asthma cohort (asthmatics n=550, normal controls n=171). Six common haplotypes could be constructed in the TNF gene cluster due to very strong LD between TNFA and TNFB, located 13 kb apart on chromosome 6p21. One SNP (TNFA-308G>A) showed a significant association with the risk of asthma (P=0.0004). The frequency of TNFA-308A allele-containing genotype in asthmatics (9.8%) was much lower than that in normal controls (22.9%). The protective effects of this polymorphism on asthma were also evident in separated subgroups by atopic status (P=0.05 in non-atopic subjects and P=0.003 in atopic subjects). The most common haplotype of the TNF gene (TNF-ht1[GGTCCGG]) was associated with total serum IgE (immunoglobulin E) levels in asthma patients, especially in non-atopic patients (P=0.004). Genetic variants of TNF might be involved in development of asthma and total serum IgE level in bronchial asthma patients. The results of this study could be helpful to understand the function of important TNF genes in asthma and IgE production.

Effects of inhaled tumour necrosis factor alpha in subjects with mild asthma

BACKGROUND

Inhaled tumour necrosis factor alpha (TNF alpha) has previously been shown to induce airway neutrophilia and increased airway reactivity in normal subjects. It was hypothesised that a similar challenge would increase airway reactivity in those with mild asthma, but that the inflammatory profile may differ.

METHODS

Ten mild asthmatic subjects were recruited on the basis of clinical asthma and either a sensitivity to methacholine within the range defined for asthma or a 20% improvement in forced expiratory volume (FEV(1)) after 200 micro g salbutamol. Subjects inhaled either vehicle control or 60 ng recombinant human (rh)TNF alpha and were studied at baseline, 6, 24, and 48 hours later. Variables included spirometric parameters, methacholine provocative concentration causing a 20% fall in FEV(1) (PC(20)), induced sputum differential cell count, relative sputum level of mRNA of interleukins (IL)-4, IL-5, IL-9, IL-14, IL-15 and TNF alpha, and the exhaled gaseous markers of inflammation, nitric oxide and carbon monoxide.

RESULTS

PC(20) showed an increase in sensitivity after TNF alpha compared with control (p<0.01). The mean percentage of neutrophils increased at 24-48 hours (24 hour control: 1.1 (95% CI 0.4 to 2.7) v 9.2 (95% CI 3.5 to 14.9), p<0.05), and there was also a rise in eosinophils (p=0.05). Relative levels of sputum mRNA suggested a rise in expression of TNF alpha, IL-14, and IL-15, but no change in IL-4 and IL-5. Spirometric parameters and exhaled gases showed no significant change.

CONCLUSION

The increase in airway responsiveness and sputum inflammatory cell influx in response to rhTNF alpha indicates that TNF alpha may contribute to the airway inflammation that characterises asthma.

Antigen challenge increases adherence of circulating neutrophils in horses with chronic obstructive pulmonary disease

Activation of circulating neutrophils has been observed following challenge of horses with chronic obstructive pulmonary disease (COPD) and may facilitate the accumulation of these cells in the airways. In this study, no significant difference was observed between adherence to protein coated plastic of blood neutrophils from asymptomatic COPD-susceptible and normal horses stimulated by the mediators PAF, human recombinant (hr)IL-8 and hrC5a. Twenty-four hours after the start of a 7 h antigen challenge, adherence of unstimulated neutrophils from COPD-susceptible horses increased from 2.5 (0.5-4.1)% and 3.4 (0.6-6.6)% to 19.6 (16.9-20.3)% and 21.8 (10.6-23.1)% adherence for cells in medium containing 0.1% or 0.2% BSA, respectively; (median [range]; n = 4). Adherence of cells from normal horses remained unchanged. Addition of an anti-CD18 monoclonal antibody, H20A, inhibited the increase in adherence at 24 h by 96 (45-100)%, n = 3. The percentage of neutrophils in bronchoalveolar lavage fluid at 24 h increased from 1 (0-2) to 80 (65-94), (median (range), n = 4). These results suggest that antigen challenge results in exposure of circulating equine neutrophils to one or more factors that prime, or activate, these cells, which may enhance their recruitment to the lungs. Inhibition of circulating neutrophil activation may therefore represent a therapeutic target.

Contribution of anaphylatoxin C5a to late airway responses after repeated exposure of antigen to allergic rats

We attempted to elucidate the contribution of complement to allergic asthma. Rat sensitized to OVA received repeated intratracheal exposures to OVA for up to 3 consecutive days, and pulmonary resistance was then estimated for up to 6 h after the last exposure. Whereas the immediate airway response (IAR) in terms of R(L) tended to decrease in proportion to the number of OVA exposures, late airway response (LAR) became prominent only after three. Although premedication with two kinds of complement inhibitors, soluble complement receptor type 1 (sCR1) or nafamostat mesylate, resulted in inhibition of the IAR after either a single or a double exposure, the LAR was inhibited after the triple. Premedication with a C5a receptor antagonist (C5aRA) before every exposure to OVA also inhibited the LAR after three. Repeated OVA exposure resulted in eosinophil and neutrophil infiltration into the bronchial submucosa which was suppressed by premedication with sCR1 or C5aRA. Up-regulation of C5aR mRNA was shown in lungs after triple OVA exposure, but almost no up-regulation of C3aR. Pretreatment with sCR1 or C5aRA suppressed the up-regulation of C5aR expression as well as cytokine messages in the lungs. The suppression of LAR by pretreatment with sCR1 was reversed by intratracheal instillation of rat C5a desArg the action of which was inhibited by C5aRA. In contrast, rat C3a desArg or cytokine-induced neutrophil chemoattractant-1 induced cellular infiltration into the bronchial submucosa by costimulation with OVA, but these had no influence on the LAR. These differences might be explained by the fact that costimulation with OVA and C5a synergistically potentiated IAR, whereas that with OVA and either C3a or cytokine-induced neutrophil chemoattractant-1 did not. C5a generated by Ag-Ab complexes helps in the production of cytokines and contributes to the LAR after repeated exposure to Ag.

The effects of Ma-Xing-Gan-Shi-Tang on respiratory resistance and airway leukocyte infiltration in asthmatic guinea pigs

Ma-Xing-Gan-Shi-Tang (MXGST), a traditional Chinese medicine, has been used in treatment of the bronchial asthma for several centuries. However, the therapeutic mechanisms of this Chinese medicine are still far from clear. To understand the mechanism of anti-asthmatic property of MXGST, a guinea pig model of allergic asthma was used to investigate the effects of MXGST on Dermatophagoides pteronyssinus-induced early and late asthmatic responses and airway inflammation, and examine direct beta2-adrenoceptor agonist activity in guinea-pig isolated trachea. Administration of MXGST (10 g/kg) extracts significantly inhibited the antigen induced immediate asthmatic responses (IAR) in actively sensitized guinea pig. MXGST caused concentration-dependent relaxation in strips of guinea pig trachea contracted with carbachol, and ICI-118551, a selective beta2-adrenoceptor antagonist, significantly inhibit the relaxation caused by MXGST. Furthermore, examination of bronchoalveolar lavage fluid (BALF) revealed that MXGST significantly inhibited the increase in neutrophil in the airway at 1, 6 and 24 hr after antigen challenge. Histopathologic examination results showed that MXGST suppressed the neutrophil infiltration into lung tissue. In conclusion, we suggest that the anti-asthmatic effects of MXGST are mainly due to its stimulation of beta2-adrenoceptors on bronchial smooth muscle and its anti-inflammatory ability to inhibit the neutrophil into the airway. The precise mechanism of action of MXGST in asthma remains to be elucidated.

Tumour necrosis factor-alpha: the role of this multifunctional cytokine in asthma

Tumour necrosis factor-alpha (TNF-alpha) is recognized as an important mediator in many cytokine- dependent inflammatory events. It is known that TNF-alpha is released in allergic responses from both mast cells and macrophages via IgE-dependent mechanisms, and elevated levels have been demonstrated in the bronchoalveolar fluid (BALF) of asthmatic subjects undergoing allergen challenge. Inhaled TNF-alpha increases airway responsiveness to methacholine in normal and asthmatic subjects associated with a sputum neutrophilia. Additional data indicate that TNF-alpha can upregulate adhesion molecules, facilitate the immigration of inflammatory cells into the airway wall and activate pro-fibrotic mechanisms in the subepithelium. These data suggest that TNF-alpha plays a role in the initiation of allergic asthmatic airway inflammation and the generation of airway hyper-reactivity. In addition, polymorphisms of the TNF-alpha gene 5' untranslated region, particularly at -308 bp, have been described as being associated with asthma. This polymorphism is associated with increased levels of TNF-alpha, but as yet, no asthma studies have demonstrated a phenotypic difference between those individuals with the polymorphism and those with the wild type gene. The TNF receptors (TNF-R p55 and p75), also known as CD120a and b, have also been shown to be present in the lung, but their functional importance is only just emerging. In asthma, TNF may function as a pro-inflammatory cytokine that causes the recruitment of neutrophils and eosinophils. Treatment directed specifically at a reduction in TNF-alpha activity may conceivably be useful as a glucocorticosteroid-sparing asthma therapy.

Intratracheal administration of anaphylatoxin C5a potentiates antigen-induced pulmonary reactions through the prolonged production of cysteinyl-leukotrienes

The effects of intratracheal administration of anaphylatoxin C5a on airway inflammation have been studied using two sources of material, zymosan activated serum (ZAS) and purified rat C5a des Arg, in order to determine the influence of complement activation on allergic airway disorders.The intratracheal administration of ovalbumin (OA) to OA-sensitized rats generated two phases of airway response, an immediate airway response (IAR) occurring within 15 min and a late airway response (LAR) beginning 4-6 h after the allergen challenge. The simultaneous administration of ZAS and OA into the trachea generated a sustained elevation of airway resistance (Raw) following IAR, while that of OA or ZAS alone resulted in Raw returning nearly to the baseline just after the IAR. The elevation of Raw after the combined challenge of OA and ZAS was significantly inhibited by pretreatment with a CysLT(1) receptor antagonist, pranlukast 30 mg/kg, but after that OA or ZAS alone was not significantly inhibited by pranlukast. The intratracheal administration of purified C5a produced an airway response that was similar to, but higher than, that evoked by ZAS. Namely, the challenge with OA plus C5a resulted in a higher IAR than OA plus ZAS, and also caused an early animal death up to 6 h, which was prevented by a combined pretreatment with pranlukast and the H(1) receptor antagonist, diphenhydramine.A histological examination at 6 h after the OA challenge identified an infiltration of inflammatory cells into the bronchial submucosal tissue, with a predominance of neutrophils and fewer eosinophils. On the other hand, a histological examination after the OA and ZAS challenge showed more severe infiltration of granulocytes into the bronchial submucosal tissue than that with OA or ZAS alone. The challenge with OA plus C5a was associated with severe perivascular leakage in the lungs and the combined pretreatment with both the antagonists led to a marked reduction in perivascular leakage. The quantitation of N-acetyl-leukotriene E(4) (N-Ac-LTE(4)), a major metabolite of cysteinyl-leukotrienes (cysLTs), in the bile indicated a significantly greater and longer excretion of cysLTs, from 1 to 6 h after the combined challenge, than that after either OA or ZAS alone. This suggested a prolonged generation of cysLTs in the lung by the combined challenge.In conclusion, our findings suggest that anaphylatoxin C5a may mediate the airway inflammatory response induced by a specific antigen challenge partly through a prolonged production of cysLTs and the release of histamine.

Increased interleukin-10 and macrophage inflammatoryprotein-1α release from blood monocytes ex vivo duringlate-phase response to allergen in asthma

BACKGROUND

We determined the effect of late-phase responses to allergen challenge of mildly allergic asthmatic patients on the expression and release of the cytokines IL-10 and MIP-1α from peripheral blood monocytes.

METHODS

Sixteen mildly allergic asthmatics were exposed to increasing concentrations of allergen aerosol. Nine demonstrated an early response alone (single responders), while seven had an early followed by a late response (dual responders). Monocytes were isolated from venous blood before and 24 h after allergen challenge, and placed in short-term culture for determination ofIL-10 mRNA expression by reverse-transcription polymerase chain reactionand protein release. MIP-1α protein release was measured byradioimmunoassay.

RESULTS

IL-10 mRNA expression was significantly higher in dual responders than early responders alone, for unstimulated monocytes or for monocytes exposed to lipopolysaccharide or IL-1β. In addition, the release of IL-10 and MIP-1α from monocytes of dual responders was also enhanced.

CONCLUSIONS

Circulating monocytes are primed to release more of the cytokines, IL-10 and MIP-1α, in dual but not in single responders, at 24 h afterallergen. They may contribute to allergen-induced inflammatory responsesin the airways.

Effect of San-Ao-Tang on immediate and late airway response and leukocyte infiltration in asthmatic guinea pigs

San-Ao-Tang (SAT), a traditional Chinese medicines, has been used to treat patients with the bronchial asthma for several centuries. However, the therapeutic mechanisms of this Chinese medicine are still far from clear. To understand the mechanism of antiasthmatic property of SAT, a guinea pig model of allergic asthma was used to investigate the effects of SAT on Dermatophagoides pteronyssinus-induced immediate and late asthmatic responses and airway inflammation. Our results showed that administration of SAT (10 g/kg) extracts significantly inhibited the antigen induced immediate asthmatic responses (IAR) in actively sensitized guinea pig. Examination of bronchoalveolar lavage fluid (BALF) revealed that SAT significantly inhibited the increase in neutrophil in the airway at 1, 2, 4, 6, 8 hr after antigen challenge. Histopathologic examination showed SAT suppressed the neutrophil infiltration into lung tissue. These results suggest that the antiasthmatic effect of SAT be mainly due to its bronchodilator effect and its ability to inhibit the neutrophil into the airway. The precise mechanism of action of SAT in asthma remains to be elucidated.

Neutrophil activation following TDI bronchial challenges to the airway secretion from subjects with TDI-induced asthma

BACKGROUND

The immunopathological mechanism for occupational asthma induced by toluene diisocyanate (TDI) remains to be further clarified. There have been few reports suggesting involvement of neutrophils in inducing bronchoconstriction after TDI inhalation.

OBJECTIVES

To further understand the role of neutrophils in the pathogenesis of TDI-induced asthma.

MATERIALS AND METHODS

Eight TDI-induced asthmatic subjects were classified as group I, and five exposed workers who had complained of work-related symptoms and worked in the same workplace, but showed negative bronchial challenges were enrolled as controls (group II). Serum neutrophil chemotactic activity during TDI bronchial challenge test was measured by the Boyden chamber method. Induced sputum was collected before and after the TDI bronchial challenge test. The myeloperoxidase (MPO) and interleukin (IL) -8 levels in the sputum were measured using RIA and ELISA.

RESULT

Serum neutrophil chemotactic activity significantly increased at 10 min (P = 0.01), then decreased at 60 min (P = 0.02) and remained unchanged for up to 420 min (P = 0.07) in group I subjects, while no significant changes were found in group II subjects (P > 0.05). MPO and IL-8 were abundantly present in the sputum of all the TDI-induced asthmatic subjects and they increased significantly at 420 min after the bronchial challenges (P = 0.02, P = 0.03, respectively), while no significant changes were noted in group II subjects (P > 0.05).

CONCLUSION

These findings support the view that activated neutrophils may contribute to bronchoconstriction induced by TDI which may be associated with IL-8 release.

Nasal response to a single antigen challenge in patients with allergic rhinitis - inflammatory cell recruitment persists up to 48 hours

BACKGROUND

Allergen challenge in some patients with respiratory allergy is followed by an early and a late reaction.

OBJECTIVE

To evaluate the duration of mediator release and inflammatory cell recruitment during the late antigen-induced nasal response.

METHODS

Eight patients with seasonal allergic rhinitis due to grass pollen underwent local challenge with the relevant allergen, a non-relevant allergen (Parietaria judaica), and nebulized saline solution. Nasal lavages were performed at baseline and 6, 24, 48, 72 h after challenge. Eosinophil cationic protein (ECP), leukotriene C4 (LTC4), leukotriene B4 (LTB4) myeloperoxidase (MPO) and prostaglandin D2 (PGD2) levels were radioimmunoassayed and histamine concentration was measured by an automated fluorometric method.

RESULTS

Nasal challenge with the relevant antigen induced a response 6 h after stimulation, which subsided within 24 h. Eosinophilia, observed in the nasal lavages collected from 6 to 24 h after this challenge, was accompanied by ECP release. Neutrophilia were found in the nasal lavages collected from 6 to 24 h after challenge. The increase in neutrophil number correlated with MPO levels and LTB4 concentrations, but not with the intensity of nasal obstruction. Antigen challenge also induced significant recruitment of mononuclear cells 48 h after provocation. The challenge significantly raised histamine, but not PGD2, levels in the nasal lavages collected 6 h after provocation. A trend towards an increase in LTC4 levels in the nasal lavages collected 6 h after specific antigen challenge was also found. Nasal challenge with a non-relevant allergen or with saline solution did not cause either inflammatory cell recruitment or mediator release.

CONCLUSION

Nasal challenge with the relevant antigen can induce a late response characterized by local accumulation of eosinophils, neutrophils and mononuclear cells persisting for 48 h and accompanied by release of ECP, MPO, LTB4 and histamine. These results indicate that a single antigen challenge in patients with allergic rhinitis causes prolonged inflammatory alterations which may contribute to the development of airway hyperreactivity.

Bronchoalveolar cell profiles in children with asthma, infantile wheeze, chronic cough, or cystic fibrosis

Differential cell counts of bronchoalveolar lavage (BAL) have been reported in normal children but few data on cellular profiles in bronchial diseases in childhood are available. We determined the BAL cell profiles of 72 children divided into 5 groups: asthma (n = 14), chronic cough (n = 12), infantile wheeze (n = 26), cystic fibrosis (n = 10), and control (n = 10). The highest total cell, eosinophil, and neutrophil counts were found in children with cystic fibrosis. The cell profile of children with chronic cough was similar to that of control children. Asthma and infantile wheeze were characterized by a high median ratio of eosinophils (3%) and neutrophils (12%), respectively. In both diseases, epithelial shedding was suggested by an elevated epithelial cell count, 13.5 and 12%, respectively. Lymphocyte subset analysis showed a higher proportion of CD8 cells (58 versus 40%) and therefore a lower CD4/CD8 ratio (0.266 versus 0. 455) in children with asthma compared with infantile wheezers (p = 0. 02). Irrespective of the presence or absence of radiological abnormalities, a proportion of neutrophils > 10%, was found in one-third of the children with asthma and in half of the infantile wheezers, and was related to symptom severity. We suggest that neutrophil-mediated inflammation, with or without bacterial infection, may contribute to symptoms of asthma in childhood. Chronic cough, however, is not associated with the cell profiles suggestive of asthma and in isolation should not be treated with prophylactic antiasthma drugs.

Enhanced basophil histamine release and neutrophil chemotactic activity predispose grain dust-induced airway obstruction

BACKGROUND

The pathogenic mechanism of grain dust (GD)-induced occupational asthma (OA) remains unclear.

OBJECTIVE

To understand further the mechanism of GD-induced OA.

METHODS

Fifteen employees working in a same GD industry, complaining of work-related respiratory symptoms, were enrolled and were divided into two groups according to the GD-bronchoprovocation test (BPT) result: six positive responders were grouped as group III, nine negative responders as group II and five healthy controls as group I. Serum GD-specific immunoglobulin (Ig)E (sIgE), specific IgG (sIgG) and specific IgG4 (sIgG4) antibodies were detected by enzyme-linked immunosorbent assay. Basophil histamine release was measured by the autofluorometric method, and changes of serum neutrophil chemotactic activity were observed by the Boyden chamber method.

RESULTS

For clinical parameters such as degree of airway hyperresponsiveness to methacholine, duration of respiratory symptoms, exposure duration, and prevalences of serum sIgE, sIgG and sIgG4 antibodies, there were no significant differences between group II and III (P > 0.05, respectively). Serum neutrophil chemotactic activity increased significantly at 30 min and decreased at 240 min after the GD-BPT in group III subjects (P < 0.05, respectively), while no significant changes were noted in group II subjects (P > 0.05). Basophil histamine release induced by GD was significantly higher in group III than those of group I or group II (P < 0.05, respectively), while minimal release of anti-IgG4 antibodies was noted in all three groups.

CONCLUSIONS

These results suggest that enhanced basophil histamine release and serum neutrophil chemotactic activity might contribute to the development of GD-induced occupational asthma.

Immunohistochemical characterization of cellular infiltrate in nasal polyp from aspirin-sensitive asthmatic patients

BACKGROUND

The immunopathologic mechanism of nasal polyp in aspirin-sensitive asthma remains to be further defined.

OBJECTIVE

To characterize the features of the inflammatory cellular infiltrate in the nasal polyp tissue from aspirin-sensitive asthmatic patients.

METHODS

We have taken nasal polyp tissue during nasal polyp resection from 13 aspirin-sensitive asthma, 6 allergic, and 12 non-allergic subjects. Immunohistochemistry was employed to stain and enumerate the individual inflammatory cell types using monoclonal antibodies against tryptase (AA1) to identify mast cells, against secreted forms of eosinophil cationic protein (EG2), to identify activated eosinophils, against neutrophil elastase (NE) for neutrophils and against T cell surface markers (CD3) to identify total T cells.

RESULTS

There were no significant differences in AA1 + cells among three groups (P>.05). EG2 + cells tended to be higher in ASA-sensitive asthmatic patients than in allergic and non-allergic subjects, but no statistical significance was observed. NE+ cells were found in most subjects of the three groups and their numbers were significantly higher in allergic subjects than in aspirin-sensitive asthma (P<.05). Some patients had CD3+ cells with no statistical significance among the three groups. Significant correlation was found in numbers between NE+ cell and AA1+ cell (r=.44, P=.01), and between NE+ cell and EG2+ cell (r=.40, P=.02).

CONCLUSION

These findings suggested that major effector cells such as mast cells and eosinophils might be placed in the center of the inflammatory response of nasal polyps, regardless of their association with aspirin sensitivity.

Effect of TYB-2285 on early and late bronchial responses and airway hyperreactivity in actively sensitized guinea pigs

1. The effect of a new antiasthmatic drug, TYB-2285 [3,5-bis (acetoxyacetylamino)-4-chlorobenzonitrile], on dual bronchoconstriction and airway hyperreactivity in actively sensitized guinea pigs was investigated. 2. Immediate and late bronchial responses were induced at 1-10 min and 4-7 hr after antigen inhalation, respectively. Guinea pigs were pretreated with TYB-2285 (300 mg kg(-1) PO, as a single dose or consecutively for 7 days). 3. The immediate bronchial response was inhibited only by a multiple administration of TYB-2285. Late bronchial response was inhibited by both administration methods. 4. The numbers of eosinophils, neutrophils and macrophages, but not lymphocytes, in the bronchoalveolar lavage fluid were increased at 4 hr after antigen inhalation. TYB-2285, given singly and consecutively, decreased the numbers of total cells, eosinophils, neutrophils and macrophages. 5. Sensitized guinea pigs showed significant airway hyperreactivity to inhaled histamine. This airway hyperresponsiveness was reversed by a single administration of TYB-2285. 6. Luminol-dependent chemiluminescence of airway-infiltrated cells was slightly inhibited by TYB-2285 (20 microg ml(-1)). 7. The present study shows that TYB-2285 inhibits late asthmatic response and airway hyperresponsiveness, presumably by inhibiting the accumulation and activation of eosinophils and other inflammatory cells.

Enhanced neutrophil chemotactic activity after bronchial challenge in subjects with grain dust-induced asthma

BACKGROUND

There have been few reports suggesting involvement of neutrophils in induction of bronchoconstriction after inhalation of grain dust.

OBJECTIVES

To understand the role of neutrophils in pathogenesis of grain dust-induced asthma.

MATERIALS AND METHODS

We observed serum neutrophil chemotactic activity during grain dust-bronchoprovocation tests in six asthmatic subjects with positive bronchial challenges (group I). They were compared with those of six symptomatic subjects from the same workplace with negative bronchial challenges (group II).

RESULTS

After grain dust inhalation, serum neutrophil chemotactic activity significantly increased at 30 minutes (P = .028), and then decreased to baseline level at 240 minutes (P = .028) in five subjects of group I having isolated early asthmatic responses. Enhanced neutrophil chemotactic activity was persistent for up to 240 minutes in one asthmatic subject having both early and late asthmatic responses. There was, however, no significant change in serum neutrophil chemotactic activity during bronchial challenges in subjects of group II. Pre-incubation of sera with anti-interleukin-8 (IL-8) antibody did not affect the neutrophil chemotactic activity results of group I subjects.

CONCLUSION

These results suggest that enhanced neutrophil chemotactic activity distinct from IL-8 may contribute to significant bronchoconstriction induced by grain dust.

Lactoferrin, a potent tryptase inhibitor, abolishes late-phase airway responses in allergic sheep

Tryptase, a serine protease released exclusively from activated mast cells, has been implicated as a potential causative agent in asthma. Enzymatically active tryptase is comprised of four subunits, and heparin stabilizes the associated tetramer. Lactoferrin, a cationic protein released from activated neutrophils, binds tightly to heparin, therefore we investigated lactoferrin as an inhibitor of tryptase and found that it is both a potent (Ki' is 24 nM) and selective inhibitor. Size exclusion chromatography studies revealed that lactoferrin disrupted the quaternary structure of active tryptase. Lactoferrin was tested in an allergic sheep model of asthma; aerosolized lactoferrin (10 mg in 3 ml phosphate-buffered saline, 0.5 h before as well as 4 and 24 h after inhalation challenge by Ascaris suum) abolished both late-phase bronchoconstriction (no significant increase in specific lung resistance 4 to 8 h following provocation, p < 0.05 versus vehicle treatment) and airway hyperresponsiveness (no detectable increase in airway sensitivity to carbachol challenge 24 h after antigen challenge, p < 0.05 versus vehicle). These data suggest tryptase involvement in both late-phase bronchoconstriction and airway hyperreactivity and furthermore suggest that a physiological function of neutrophil lactoferrin is the inhibition of tryptase released from mast cells.

Blood markers of early and late airway responses to allergen in asthmatic subjects. Relationship with functional findings

We evaluated the relationship between blood markers of mast-cell (plasma histamine and serum level of heat-stable neutrophil chemotactic activity [NCA]) and eosinophil (serum eosinophil cationic protein [ECP]) activation during early airway response (EAR) and late airway response (LAR) to allergen inhalation in 24 asthmatic subjects. After EAR, 14 subjects showed significant LAR (FEV1 fall: > or = 25%), while 10 subjects showed equivocal LAR (FEV1 fall: 15-20%). A significant increase from baseline value was observed in plasma histamine and in serum NCA during both EAR and LAR, while serum ECP significantly increased only during LAR. The sensitivity of different markers to detect significant FEV1 fall during EAR and LAR was low, except for NCA. Changes in blood mediators were similar in both groups with significant and equivocal LAR. There was a significant relationship between the increase in NCA during EAR and the severity of LAR. Stepwise regression between changes in different blood markers showed a significant relationship between histamine increase during EAR and ECP increase during LAR. Thus, serum NCA is a more sensitive marker of EAR and LAR than plasma histamine and serum ECP, and its increase during EAR seems predictive of the severity of the subsequent LAR.

Enhancement of Antigen-specific functional responses by neutrophils from allergic patients

It has been demonstrated that neutrophils from healthy donors or from patients with inflammatory disorders can bind immunoglobulin (Ig) E proteins through binding to Mac-2/epsilon bp. Functional responses to allergens were assessed by measuring the respiratory burst and intracellular Ca2+ levels, and binding of allergens to neutrophils was assessed by flow cytometry analysis and fluorescence microscopy. In this article, we demonstrate that neutrophils sensitized to specific allergens (from allergic patients), but not from healthy donors, are sensitive to allergens of the same type as those that produce clinical allergic symptoms. The activation of neutrophils was analyzed by the induction of a respiratory burst that was detected with luminol-dependent chemiluminescence. Intracellular Ca2+ levels increased parallel to those of the inducing allergens. In addition, the specific binding of allergens on the cell surface was revealed by flow cytometry and allergen-FITC-labeled staining analyses. The present data suggest a restricted recognition of allergen by sensitive neutrophils, probably associated with the specific binding of the allergen to its corresponding IgE molecule, which is bound to the Mac-2/epsilon bp structure. These findings demonstrate a functional role of allergen-associated neutrophils during the allergic state.

Role of macrophages in pulmonary late-phase reaction in guinea pigs

To examine the role of macrophages in pulmonary late-phase reaction (LPR), macrophages were reduced in sensitized guinea pigs by an intravenous injection of liposome-encapsulated dichloromethylene diphosphonate (Cl2MDP). Macrophage reduction was evaluated by bronchoalveolar lavage (BAL) fluid analysis. In Cl2MDP liposome-treated animals, the number of macrophages in BAL fluid significantly decreased by 56% compared with PBS liposome-treated animals (1.6 +/- 0.1 vs. 3.6 +/- 0.4 x 10(6) cells, p < 0.01). The number of neutrophils, eosinophils, or lymphocytes in BAL fluid showed no significant changes in these two groups. Both PBS and Cl2MDP liposome-treated sensitized guinea pigs were challenged with an inhalation of antigen, and respiratory resistance (Rrs) was measured. PBS liposome-treated animals (control) exhibited both immediate (IPR) and late (LPR) increases in Rrs. The maximal increases in Rrs at IPR and LPR were 217 +/- 19 and 187 +/- 20% of baseline values, respectively (n = 9). On the other hand, Cl2MDP liposome-treated animals showed an immediate increase in Rrs (IPR); however, the late increase in Rrs (LPR) was significantly suppressed (p < 0.05). The maximal increases in Rrs at IPR and LPR were 200 +/- 13 and 134 +/- 11% of baseline values, respectively (n = 8). In Cl2MDP liposome-treated animals, the numbers of macrophages and neutrophils in BAL fluid 4 hr after antigen challenge decreased by 45% and 54%, respectively, compared with PBS liposome-treated animals (p < 0.05). In Cl2MDP liposome-treated animals, neutrophil chemotactic activity in BAL fluid 4 hr after antigen challenge decreased by 59% compared with PBS liposome-treated animals (p < 0.05). These results suggest that macrophages play an important role in the development of pulmonary LPR through the induction of neutrophil accumulation in the airways.

Leukotriene B4 production by blood neutrophils in allergic rhinitis--effects of cetirizine

BACKGROUND

Mucosal inflammatory processes in late phase of allergic diseases involve cytokine production, cell adhesion molecule overexpression and release of inflammatory mediators with chemotactic activity, such as leukotriene B4 (LTB4). We had previously observed increased production of LTB4 by neutrophils in patients with allergic rhinitis and discussed the role of granulocyte macrophage-colony stimulating factor (GM-CSF) priming. Some antihistaminic compounds were shown to diminish the production of leukotrienes by neutrophils.

OBJECTIVES

In a first step, we evaluated in ex vivo and in vitro studies, the effects of cetirizine on LTB4 production by blood neutrophils from allergic and healthy subjects. In a second step, we studied the in vitro effect of cetirizine on LTB4 production by neutrophils from healthy subjects during GM-CSF priming of these cells.

METHODS

Neutrophils from both populations were purified from venous blood and LTB4 production was measured using high performance liquid cromatography (HPLC) method.

RESULTS

In ex vivo studies, cetirizine treatment induced a decreased LTB4 production by neutrophils in allergic rhinitis. This effect of decreased LTB4 production was reproduced in vitro with 10(-8)-10(-6)M cetirizine. Nevertheless, this anti-H1 compound had no effect on neutrophil priming with GM-CSF.

CONCLUSION

As LTB4 is an important chemotactic factor, Cetirizine could act on inflammatory cell recruitment by inhibiting LTB4 production by neutrophils.

Adenosine, methacholine, and exercise challenges in children with asthma or paediatric chronic obstructive pulmonary disease

BACKGROUND

Bronchial hyperreactivity to methacholine is present in children with asthma and other types of paediatric chronic obstructive pulmonary disease (COPD), while hyperreactivity to exercise is more specific for asthma. Adenosine 5'-monophosphate (AMP) is a potent bronchoconstrictor and, like exercise, may provoke asthma by activating mast cells. This study investigated the suitability of AMP as a specific challenge for asthma in children.

METHODS

Bronchial provocation challenges with methacholine and AMP were performed in a double blind fashion using tidal breathing in 51 children with asthma, 21 with paediatric COPD of various types, and in 19 control children. Each subject also underwent a standardised exercise challenge after inhalation challenges were completed. Sensitivity and specificity curves were constructed and the intersection point of sensitivity and specificity for each type of challenge was determined.

RESULTS

When the asthmatic patients were compared with the children with COPD, the intersection points for AMP, exercise and methacholine were 90%, 85%, and 50%, respectively. When compared with the controls the same intersection points were 98%, 84%, and 92%, and when children with paediatric COPD were compared with controls they were 55%, 50%, and 82%.

CONCLUSIONS

Methacholine distinguishes both asthma and paediatric COPD from controls with a sensitivity of 82-92%, but does not distinguish between asthma and paediatric COPD; exercise and AMP distinguish asthma from controls with a sensitivity and specificity of 84-98% but they also distinguish asthma from paediatric COPD with a sensitivity and specificity of 85-90%. AMP inhalation is a practical aid for diagnosing asthma and distinguishing it from COPD in children of all ages.

The effect of TYB-2285 on dual phase bronchoconstriction and airway hypersensitivity in guinea-pigs actively sensitized with ovalbumin

The effect of a new anti-asthmatic drug, TYB-2285 (3,5-bis(acetoxyacetylamino)-4-chlorobenzonitrile), was investigated in ovalbumin-sensitized guinea-pigs. When guinea-pigs were pretreated with TYB-2285 (300 mg kg-1, p.o., single dose or consecutively for 7 days), the immediate asthmatic response was inhibited as demonstrated by diminished cyanosis, but not the bronchoconstriction. TYB-2285, given singly or consecutively, inhibited the appearance of late asthmatic response and the infiltration of inflammatory cells, such as eosinophils, into the airway. Additionally, airway hyper-responsiveness was also reversed by the single administration of TYB-2285. Luminol-dependent chemiluminescence of airway-infiltrated cells stimulated with A23187 was inhibited by TYB-2285 in a dose-dependent manner. The present study suggests that TYB-2285 inhibits late asthmatic response and airway hyperresponsiveness by inhibiting the accumulation of eosinophils and other inflammatory cells into the airway, and also by inhibiting the production of oxygen radicals from airway-infiltrated cells.

Bronchial biopsy evidence for leukocyte infiltration and upregulation of leukocyte-endothelial cell adhesion molecules 6 hours after local allergen challenge of sensitized asthmatic airways

We have examined the mucosal changes occurring in bronchial biopsies from six atopic asthmatics 5-6 h after local endobronchial allergen challenge and compared them with biopsies from saline-challenged segments from the same subjects at the same time point. All the subjects developed localized bronchoconstriction in the allergen-challenged segment and had a decrease in forced expiratory volume in 1 s (FEV1) (P < 0.01) and a decrease in their methacholine provocative concentration of agonist required to reduce FEV1 from baseline by 20% (P < 0.05) 24 h postchallenge. At 6 h we observed an increase in neutrophils (P = 0.03), eosinophils (P = 0.025), mast cells (P = 0.03), and CD3+ lymphocytes (P = 0.025), but not in CD4+ or CD8+ lymphocyte counts. We also detected an increase in endothelial intercellular adhesion molecule type 1 (P < 0.05) and E-selectin (P < 0.005), but not vascular cell adhesion molecule type 1 expression with a correlative increase in submucosal and epithelial LFA+ leucocytes (P < 0.01). Thus, in sensitized asthmatics, local endobronchial allergen instillation leads to an increased inflammatory cell infiltrate of the airway mucosa that involves upregulation of specific adhesion molecules expressed on the microvasculature.

Effects of nedocromil sodium on bronchospasm and HS-NCA release induced by allergen inhalation in asthmatic patients

The aim of this study was to assess the ability of nedocromil sodium (NS) to prevent the immediate asthmatic reaction and the increase in the serum level of heat stable neutrophil chemotactic activity (HS-NCA) induced by antigen inhalation. In a double-blind, cross-over study, 13 atopic subjects affected with seasonal asthma underwent a bronchial provocation test with a preselected dose of grass pollen allergen (enough to cause a decrease of > or = 20% in FEV1:FEV1 PD20) after pre-treatment with 4 mg NS or placebo. Serum samples were withdrawn from 11 subjects for HS-NCA determination. After NS administration the decrease in FEV1 was significantly less than after placebo administration at all time points after challenge (2 min P = 0.0004; 7 min, P = 0.0005; 17 min P = 0.0002 and 27 min P = 0.0005). The percentage increase in HS-NCA was significantly higher after placebo than after NS inhalation, both 10 (P = 0.0048) and 20 (P = 0.0068) min after challenge. Our study confirms previous investigations, showing that NS inhibits the immediate asthmatic response to allergen inhalation in atopic, asthmatic subjects and moreover it shows that this drug prevents in vivo the increase of the serum HS-NCA. This last finding has not been previously reported.

Neutrophil chemotactic activity (NCA) in nasal secretions from atopic and nonatopic subjects. Effect of antigen challenge

In order to elucidate the mechanism responsible for infiltration of nasal mucosa by granulocytes, we tested neutrophil chemotactic activity (NCA) in nasal lavages, by the modified Boyden chamber method, in 16 patients with perennial allergic rhinitis (AR), six ASA-sensitive patients with chronic rhinosinusitis (CRS), and seven normal, nonatopic control subjects (NC). Nasal secretions from all three groups showed significant NCA (mean 157.1 +/- 54.0, 62.2 +/- 20.7, and 39.4 +/- 11.4% of FMLP chemotactic activity for AR, CRS, and NC subjects, respectively). Nasal secretions from patients with AR expressed significantly higher NCA (P < 0.02) than did secretions from NA patients. NCA was unchanged by heating at 56 degrees C for 60 min and was not susceptible to degradation by trypsin. Nasal challenge with Dermatophagoides pteronyssinus antigen induced clinical symptoms and resulted in significant increases in total protein and albumin concentrations in nasal lavages in AR patients, but failed to change the mean NCA activity for up to 40 min after the challenge. These results indicate that nasal secretions from both atopic and nonatopic patients express NCA, but its relation to allergic inflammation remains to be established.

Quantification of histamine in plasma and pulmonary fluids from horses with chronic obstructive pulmonary disease, before and after 'natural (hay and straw) challenges'

A commercial radioimmunoassay kit was used to quantify histamine concentrations of plasma, bronchoalveolar lavage fluid (BALF) and pulmonary epithelial lining fluid (PELF) of normal horses and horses with chronic obstructive pulmonary disease (COPD), before and after 'natural (hay and straw) challenge' (NC). There were no significant changes in the concentrations of histamine in plasma or BALF at 0.5 or 5 h after NC, but the PELF histamine concentration of COPD affected horses was significantly increased at 5 h, but not at 0.5 h, following NC. As the histamine concentrations of whole BALF lysates were significantly correlated with the numbers of metachromatically staining cells, presumed to be mast cells and/or basophils, these findings support involvement of a late phase, IgE mediated, hypersensitivity reaction in the pathogenesis of equine COPD.

Increases in activated T lymphocytes, eosinophils, and cytokine mRNA expression for interleukin-5 and granulocyte/macrophage colony-stimulating factor in bronchial biopsies after allergen inhalation challenge in atopic asthmatics

Immunohistology and in situ hybridization were used to evaluate the presence, activation status, and cytokine mRNA profile of cells in the bronchial mucosa during human allergen-induced asthma. Fifteen atopic asthmatic subjects underwent inhalation challenge with allergen and with allergen diluent, performed in random order separated by an interval of at least 3 wk. Bronchial biopsies were obtained 24 h after challenge. Immunostaining revealed increases in the numbers of secreting eosinophils (EG2+; P < 0.05) and in interleukin-2 receptor (IL-2R)-positive cells (CD25+; P < 0.01) after allergen compared with diluent challenge. No differences were observed in the numbers of total leukocytes (CD45+), T lymphocytes (CD3+, CD4+, and CD8+), elastase-positive neutrophils, macrophages (CD68+), or mast cell subtypes (MCT+ or MCTC+). In situ hybridization revealed significant increases in the numbers of cells expressing mRNA for IL-5 (P < 0.02) and granulocyte/macrophage colony-stimulating factor (P < 0.01) after allergen compared with diluent challenge. A significant inverse relationship was observed between the number of cells expressing mRNA for IL-4 and for interferon-gamma (r = -0.75, P < 0.02). The results support the view that cytokines possibly from activated T lymphocytes may contribute to local eosinophil accumulation during allergen-induced asthma.

Allergic inflammation

A greater understanding of the basic mechanisms of allergic inflammation is pertinent to the development of new treatments. Previous studies have focused on the role of mediators of hypersensitivity and effector cells, including mast cells and eosinophils. Recent evidence suggests that IgE-dependent activation and tissue eosinophilia are under the local regulation of distinct cytokines. Originally described as products from T lymphocytes, these peptide messengers are produced by alternative cells, including mast cells, eosinophils and the respiratory epithelium. In vitro studies in murine models and using cloned human T lymphocytes indicate the preferential production of "Th2-type" cytokines, including interleukin-4 (IL-4) and IL-5. This review considers the evidence from in vivo studies in humans that "Th2-type" cytokines have a primary role in orchestrating both IgE-dependent events and local tissue eosinophilia. Novel therapeutic approaches might include a broad strategy directed against T lymphocytes, including the use of immunosuppressive agents or anti CD4 antibodies or more precise targeting of IL-4 and/or IL-5.

Asthma

There is an active inflammatory process in the airways of patients with asthma, even when the patients are asymptomatic. Some of the types of cells involved in this process possess the necessary biologic activities to produce many of the pathophysiologic features of asthma, but the underlying mechanisms have not yet been elucidated. Reducing the severity of the inflammatory process appears to be a reasonable goal of therapy, with potential long-range implications for the morbidity of asthma. Whether this theoretical benefit will be realized awaits further observation.

Effect of interleukin-2 on the airway response to antigen in the rat

To evaluate the hypothesis that lymphocyte stimulation can modify the bronchoconstrictive response to inhalational challenge with an allergen, we administered interleukin-2 (IL-2), an important lymphokine in lymphocyte activation and proliferation, to actively sensitized rats. Brown Norway rats received either human recombinant IL-2 (n = 8) or its vehicle (n = 7) twice a day from the ninth to the fourteenth day after active sensitization to ovalbumin (OA) and were challenged with an aerosol of OA. Lung resistance (RL) during the early response increased to a maximum of 698 +/- 230% and 180 +/- 26% of baseline values in the animals receiving IL-2 and vehicle, respectively (p less than 0.025). The late response was threefold greater in IL-2-treated than in vehicle-treated animals (p = 0.01). IL-2 increased OA-specific IgG levels in the serum, but it did not significantly affect total or specific IgE levels. IL-2 caused an inflammatory infiltrate around the airways with significant increases in eosinophils, lymphocytes, and mast cells prior to antigen challenge. Our results indicate that stimulation of cell-mediated immunity can affect airway responsiveness to antigen.

Inflammation and the allergic response

The atopic diseases--allergic rhinitis, asthma, and atopic dermatitis--are chronic inflammatory diseases characterized by an exacerbating and remitting course and can only rarely be associated causally with allergen exposure. The challenge to ascribe an allergic basis to these diseases is derived from the apparent inability to reconcile these chronic inflammatory features with a process thought to be initiated by the rapid release of mediators after the interaction of allergen with IgE-coated mast cells. The traditional understanding has been that mast cell activation results in the release of a series of preformed and rapidly synthesized substances that mediate the immediate onset of vasodilatation, vascular leakage, smooth muscle contraction, and irritant nerve receptor stimulation. These mediators, however, are rapidly degraded and are not thought to be associated with a significant inflammatory component. Recent studies, however, have established that the interaction of allergen with the immune system is, in fact, far more complex (Fig. 4). In addition to mast cell activation, allergen can interact with and activate T-lymphocytes and mononuclear phagocytic cells, leading to the secretion of cytokines and other inflammatory substances. Furthermore, the interaction of allergen with the mast cell may be far more complex, with the potential to stimulate the delayed release of newly synthesized cytokines. The interaction of allergen with the immune system also promotes the secondary release of inflammatory neuropeptides. Thus, the known spectrum of mediators released after allergen exposure has vastly been expanded. These include numerous still uncharacterized chemotactic and activating peptides; eicosanoids such as 5-HETE, 12-HETE, and leukotriene B4; platelet-activating factor; several proteases; neuropeptides and, most importantly, the cytokines. These mediators recruit and activate neutrophils, monocytes, basophils, and eosinophils, attract additional lymphocytes and mononuclear phagocytic cells, and induce mast cell proliferation with further mast cell degranulation. A vicious cycle subsequently develops, with further inflammation and tissue destruction. Thus, the interaction of allergen with the immune system has become a complex cascade capable of producing the chronic inflammatory changes characteristic of allergic diseases.

The pathobiology of bronchial asthma

Early studies of patients dying from status asthmaticus revealed marked inflammation of the bronchial tree. Subsequent histological studies of the airways and examination of bronchoalveolar lavage fluid of subjects with mild asthma have confirmed the presence of airway inflammation in life. There is epithelial edema and desquamation, subepithelial deposition of collagen and fibronectin, and an inflammatory cell infiltrate in the mucosa. There are increased numbers of activated eosinophils, CD25-positive T lymphocytes, and immature macrophages with the phenotypic characteristics of blood monocytes. An increased expression of HLA class II is present on epithelium, macrophages, and other infiltrating cells. The severity of clinical asthma correlates with several measurements of the severity of the inflammatory response, suggesting a crucial role for airway inflammation in the pathophysiology of the disease. There is considerable interest and research into the mechanisms underlying the pathogenesis and maintenance of the inflammatory response in asthma. The development and maintenance of the inflammatory response in asthma is likely to be a consequence of a complicated interaction between various cells and the mediators they generate. The characterization of an ever-increasing number of cytokines is of particular interest. Interleukin-3, interleukin-5, and granulocyte-macrophage colony-stimulating factor are hematopoietic growth factors that increase the survival of eosinophils in culture and enhance certain eosinophil functions, such as mediator generation and toxicity. Alveolar macrophages derived from asthmatic subjects produce twofold to threefold more GM-CSF than do those from normal control subjects. Using in situ hybridization, the presence of IL-5 mRNA has been demonstrated in bronchial biopsies from asthmatic subjects. Thus IL-3, IL-5, and GM-CSF influence eosinophil function and survival, and may be generated by T lymphocytes and/or alveolar macrophages within the airways in asthma. In addition to these three cytokines, IL-4 and interferon-gamma may be crucial to the regulation of IgE biosynthesis. TNF-alpha and IL-1 are potentially important in the up-regulation of endothelial adhesion molecules. An important step in the recruitment of leukocytes to an inflammatory focus is margination to the vascular endothelium. Our understanding of the molecular events involved in migration of leukocytes to an inflammatory focus has been advanced by the discovery and characterization of a variety of cell adhesion molecules. The potential role of ELAM-1 and ICAM-1 in allergic inflammation is suggested by their up-regulation on vascular endothelium in association with late cutaneous responses to allergen and by their role in certain primate models of asthma.(ABSTRACT TRUNCATED AT 400 WORDS)

Basophil-bound and serum immunoglobulin E directed against Helicobacter pylori in patients with chronic gastritis

The immunoglobulin (Ig) E immune response in patients with Helicobacter pylori-associated chronic gastritis has been evaluated. Of 26 patients with H. pylori infection, 22 (84%) tested positive for basophil-bound specific IgE (determined by the histamine release test) and 18 (69%) for serum specific IgE (determined by an enzyme-linked immunosorbent assay). In contrast, only 1 of 17 persons in whom the bacterium was not detected presented cell-bound and serum specific IgE. In the 4 histamine release test--positive but enzyme-linked immunosorbent assay--negative patients, removal of antibody from the basophil surface by acid elution showed that histamine release occurred through an IgE-dependent mechanism. When normal basophils, passively sensitized with serum from IgE-positive patients, were exposed to the H. pylori antigen, a significant release was observed, confirming the class specificity of the response. Inhibition experiments with bacteria other than H. pylori showed that the IgE antibody was specifically directed against this organism. The percentage of antigen-induced histamine release did not correlate with serum specific IgE level. However, the response of basophils to antigenic challenge was proportional to IgE-dependent cellular releasability. This finding suggests that target cell sensitivity may be the most important factor in determining the entity of biological response to the antigenic challenge. The ability of H. pylori to induce a specific IgE immune response could answer key questions regarding the mechanisms inducing gastric inflammation.

Immediate and late inflammatory responses to ragweed antigen challenge of the peripheral airways in allergic asthmatics. Cellular, mediator, and permeability changes

Asthma may represent the clinical manifestations of a unique form of chronic airway inflammation and is often associated with allergy. To better define the components of allergic inflammation in the lung, fluids obtained by bronchoalveolar lavage (BAL) were examined for cells, inflammatory mediators, and markers of airway permeability 5 min and 19 h following instillation of ragweed antigen directly into an airway segment of allergic asthmatic subjects. The 5-min response to antigen challenge (n = 10) was characterized by 17- to 208-fold increases in histamine, prostaglandin D2 (PGD2), and its metabolite, 9 alpha,11 beta-PGF2, thromboxane B2, and 6-keto-PGF1 alpha compared with a saline-challenged segment (0.004 less than p less than 0.017). The increases in most of these mediators were significantly correlated with each other (0.0001 less than p less than or equal to 0.01), and the magnitude of all significant mediator increases was directly correlated with skin test sensitivity to ragweed antigen (0.007 less than or equal to p less than or equal to 0.05). There was also a slight increase in kinins (p = 0.04). Changes in cells and airway permeability were not detected. In contrast, the 19-h response to antigen challenge (n = 9) was characterized by a 13-fold increase in total cells recovered by BAL. Eosinophils, basophils, and lymphocytes were significantly increased and comprised 38, 1, and 9% of total cells, respectively. A neutrophil influx was also observed but was not specific for antigen challenge since a similar change was observed in a sham, saline-challenged site.(ABSTRACT TRUNCATED AT 250 WORDS)