Exercise-induced late asthmatic reactions with neutrophil chemotactic activity

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.

Asthma control in adolescents: role of leukotriene inhibitors

Asthma is a chronic inflammatory disease of the airways and is a big burden worldwide. It affects both children and adults, but it is insufficiently studied in adolescents, although this age group has important peculiarities and is challenging to treat, due to, but not exclusively because of, lack of adherence to treatment instructions. Evidence-based guidelines for the treatment of asthma targeting specifically adolescents are lacking, due to the fact that most studies are conducted either on children or in adults. Exercise-induced asthma occurs commonly in adolescents, leading to impaired physical activity. This review describes current treatment options for asthma in adolescents, focusing on leukotriene receptor antagonists, both as a monotherapy and as an add-on therapy for optimal asthma control.

Exercise-induced bronchoconstriction: The effects of montelukast, a leukotriene receptor antagonist

Exercise-induced bronchoconstriction (EIB) is very common in both patients with asthma and those who are otherwise thought to be normal. The intensity of exercise as well as the type of exercise is important in producing symptoms. This may make some types of exercise such as swimming more suitable and extended running more difficult for patients with this condition. A better understanding of EIB will allow the physician to direct the patient towards a type of exercise and medications that can result in a more active lifestyle without the same concern for resulting symptoms. This is especially important for schoolchildren who are usually enrolled in physical education classes and elite athletes who may desire to participate in competitive sports. Fortunately several medications (short- and long-acting beta(2)-agonists, cromolyn, nedocromil, inhaled corticosteroids, and more recently leukotriene modifiers) have been shown to be effective in preventing or attenuating the effects of exercise in many patients. In addition, inhaled beta(2)-agonists have been shown to quickly reverse the airway obstruction that develops in patients and continue to be the reliever medications of choice. Inhaled corticosteroids are increasingly being recommended as regular therapy now that the role of inflammation and airway injury has been identified in EIB. With the discovery that there is a release of mediators such as histamine and leukotrienes from cells in the airway following exercise with resulting airway obstruction in susceptible individuals, interest has turned to attenuating their effects with mediator antagonists especially those that block the effects of leukotrienes. Studies with an oral leukotriene antagonist, montelukast, have shown beneficial effects in adults and children aged as young as 6 years with EIB. These effects can be demonstrated as soon as two hours and as long as 24 hours after administration without a demonstrated loss of a protective effect after months of treatment. The studies leading up to and resulting in an approval of montelukast for EIB for patients aged 15 years and older are reviewed in this paper.

Influx of neutrophils and persistence of cytokine expression in airways of horses after performing exercise while breathing cold air

OBJECTIVE

To determine effects of exercise performed while breathing cold air on expression of cytokines and influx of neutrophils in airways of horses.

ANIMALS

9 adult horses.

PROCEDURES

In a crossover study, bronchoalveolar lavage fluid (BALF) was obtained 24 and 48 hours after each of 2 submaximal exercise sessions performed by horses while breathing warm (25 degrees C) or cold (-5 degrees C) air. Total and differential nucleated cell counts were determined for each BALF sample. Relative mRNA expression of cytokines in BALF cells was quantified by use of a reverse transcription-PCR assay.

RESULTS

Horses had a modest but significant influx of neutrophils into the airways 24 hours after a single exercise session while breathing cold air. No other cell types were increased at 24 or 48 hours after exercising while breathing cold air. Continued increases in expression of cytokines interleukin (IL)-5 and-10 as well as proinflammatory cytokines IL-1, -6, and -8 were detected 24 hours after exercising while breathing cold air. Forty-eight hours after exercising while breathing cold air, expression of IL-10 was still higher than that for IL-10 after horses exercised while breathing warm air. Expression of tumor necrosis factor-alpha was significantly increased at 48 hours after exercising while breathing cold air.

CONCLUSIONS AND CLINICAL RELEVANCE

Exposure of intrapulmonary airways to cold air alters immunologic responses of horses for at least 48 hours. The increased expression of cytokines that suppress cell-mediated immunity may predispose athletes to viral infections of the respiratory tract following exercise in cold weather.

Exercise-Induced Asthma: An Update

Exercise-induced asthma (E.I.A) affects 12–16% of the general population and most of the patients affected by extrinsic or intrinsic asthma. Surprisingly, also a high percentage of professional and Olympic athletes are affected, showing that E.I.A. does not impair physical activity, whereas endurance sports bear a higher risk than the others. The mast cell role, late asthmatic responses, diagnosis, therapy, theories and data about immunological parameters in sports are taken into consideration in this review.

Concomitant chronic sinusitis treatment in children with mild asthma: the effect on bronchial hyperresponsiveness

STUDY OBJECTIVE

Previous studies have suggested that aggressive treatment of sinusitis can decrease bronchial hyperresponsiveness (BHR). However, there is still too little evidence to draw this conclusion, and the concept remains controversial.

DESIGN

A prospective, open-label study.

SETTING

University children's hospital allergy and immunology center and radiologic department.

PATIENTS

Sixty-one children with mild asthma and allergic rhinitis participated in the study. Forty-one of these 61 children had sinusitis, and the remainder had no sinusitis. Ten matched, nonatopic, healthy children were used as a control group.

INTERVENTION

Children with chronic sinusitis were placed into two groups. One group was treated with amoxicillin-clavulanate for 6 weeks and then with nasal saline solution irrigation for 6 weeks. For the other group, the treatment order was reversed. Children without chronic sinusitis received nasal saline solution irrigation for 12 weeks.

MEASUREMENTS

Clinical symptoms and signs of sinusitis, FEV(1), and BHR were analyzed in the patients before and after treatment.

RESULTS

The clinical symptoms and signs of sinusitis, but not FEV(1), showed a significant improvement after antibiotic treatment. After aggressive treatment for sinusitis, it was found that the provocative concentration of methacholine causing a 20% fall in FEV(1) of children with mild asthma and sinusitis was significantly higher after treatment.

CONCLUSION

The results suggest that every asthmatic patient needs to carefully evaluate to determine whether the patient has concomitant sinusitis. Respiratory infections that meet criteria for sinusitis, even if they do not exacerbate asthma, should be treated. It is suggested that sinusitis should always be kept in mind as a possible inducible factor for BHR, and that aggressive treatment of chronic sinusitis is indicated when dealing with an asthmatic patient who shows an unpredictable response to appropriate treatment. Moreover, the findings of this study provide more evidence for an association between sinusitis and asthma with respect to BHR.

Airway cooling and mucosal injury during cold weather exercise

In human subjects that exercise strenuously in cold weather, there is evidence that hyperventilation with cold air leads to peripheral airway cooling, desiccation and mucosal injury. Our hypothesis was that hyperventilation with cold air can result in penetration of unconditioned air (air that is not completely warmed and humidified) into the peripheral airways of exercising horses, resulting in peripheral airway mucosal injury. To test this hypothesis, a thermister-tipped catheter was inserted through the midcervical trachea and advanced into a sublobar bronchus in three horses that cantered on a treadmill at 6.6 m/s while breathing cold (5 degrees C) air. The mean (+/- s.e.) intra-airway temperature during cantering was 33.3 +/- 0.4 degrees C, a value comparable to the bronchial lumen temperatures measured in man during maximal exercise while breathing subfreezing dry air. In a second experiment, 6 fit Thoroughbred racehorses with satisfactory performance were used to determine whether strenuous exercise in cold conditions can produce airway injury. Horses were assigned to Exercise (E) or Control (C) groups in a random crossover design. Samples of bronchoalveolar lavage fluid (BALF) in the E treatment were recovered within 30 min of galloping exercise in 4 degrees C, 100% relative humidity (E), while in C BALF samples were obtained when the horses had not performed any exercise for at least 48 h prior. Ciliated epithelial cells in BALF were higher in E than in the C treatment. Similar results have been found in human athletes and laboratory animal models of cold weather exercise. These results support the hypothesis that, similar to man, horses that exercise in cold weather experience peripheral airway mucosal injury due to the penetration of unconditioned air. Furthermore, these results suggest that airway cooling and desiccation may be a factor in airway inflammation commonly found in equine athletes.

Modeling the acute- and late-phase responses to peripheral airway cooling and desiccation

Acute bronchoconstriction after isocapnic hyperpnea can be produced in most asthmatic individuals. However, the existence of a late-phase response is less certain. We used a canine model of isocapnic hyperpnea to test the hypothesis that this discrepancy is due to differences in the challenge threshold for the responses. Acute-phase and late-phase bronchoconstriction was measured in nine dogs after peripheral airway exposure to unconditioned air. Additionally, bronchoalveolar lavage fluid (BALF) was obtained during the late-phase response. The acute-phase response was a polynomial function with a decreasing slope at higher challenges, whereas the late-phase response suggested that a minimum threshold of challenge severity was needed to produce late-phase bronchoconstriction. BALF leukocyte and eicosanoid concentrations had linear relationships with challenge severity. Our data support the hypothesis that acute- and late-phase posthyperpnea responses have different dose-response relationships, a fact that may explain the frequent lack of a late-phase response. However, our data suggest that mild inflammation can be induced with relatively lower challenge severity.

Heparin inhibits hyperventilation-induced late-phase hyperreactivity in dogs

Inhalation of heparin attenuates hyperventilation-induced bronchoconstriction in humans and dogs. The purpose of this study was to determine whether heparin inhibits the late-phase response to hyperventilation, which is characterized by increased peripheral airway resistance (RP), eicosanoid mediator production, neutrophilic/ eosinophilic inflammation, and airway hyperreactivity (AHR) at 5 h after dry air challenge (DAC). Fiberoptic bronchoscopy was used to record RP and airway reactivity (DeltaRP) to aerosol and intravenous histamine before and 5 h after DAC. Bronchoalveolar lavage fluid (BALF) cells and eicosanoid mediators were also measured approximately 5 h after DAC. DAC of vehicle-treated bronchi resulted in late-phase airway obstruction (approximately 120% increase over baseline RP), inflammation, increased BALF concentrations of leukotriene (LT) C(4), LTD(4), and LTE(4) and prostaglandin (PG)D(2), and AHR. Pretreatment with aerosolized heparin attenuated late-phase airway obstruction by approximately 50%, inhibited eosinophil infiltration, reduced BALF concentrations of LTC(4), LTD(4), and LTE(4) and PGD(2), and abolished AHR. We conclude that heparin inhibits hyperventilation-induced late-phase changes in peripheral airway function, and does so in part via the inhibition of eosinophil migration and eicosanoid mediator production and release.

Eicosanoids modulate hyperpnea-induced late phase airway obstruction and hyperreactivity in dogs

A canine model of exercise-induced asthma was used to test the hypothesis that the development of a late phase response to hyperventilation depends on the acute production of pro-inflammatory mediators. Peripheral airway resistance, reactivity to hypocapnia and aerosol histamine, and bronchoalveolar lavage fluid (BALF) cell and eicosanoid content were measured in dogs approximately 5 h after dry air challenge (DAC). DAC resulted in late phase obstruction, hyperreactivity to histamine, and neutrophilic inflammation. Both cyclooxygenase and lipoxygenase inhibitors administered in separate experiments attenuated the late phase airway obstruction and hyperreactivity to histamine. Neither drug affected the late phase inflammation nor the concentrations of eicosanoids in the BALF obtained 5 h after DAC. This study confirms that hyperventilation of peripheral airways with unconditioned air causes late phase neutrophilia, airway obstruction, and hyperreactivity. The late phase changes in airway mechanics are related to the hyperventilation-induced release of both prostaglandins and leukotrienes, and appear to be independent of the late phase infiltration of inflammatory cells.

The role of interleukin-8 and its receptors in inflammatory lung disease: implications for therapy

Neutrophils have been implicated in the pathogenesis of many inflammatory lung diseases, including the acute respiratory distress syndrome, chronic obstructive pulmonary disease and asthma. The CXC chemokine interleukin (IL)-8, is a potent neutrophil recruiting and activating factor and the detection of IL-8 in clinical samples from patients with these diseases has led clinicians to believe that antagonism of IL-8 may be a practicable therapeutic strategy for disease management. Work over the last decade has concentrated on both the molecular mechanisms by which IL-8 is produced in the inflammatory setting and also on the manner in which IL-8 activates the neutrophil. Expression of the IL-8 gene appears to be controlled by several components of the inflammatory milieu. Whilst lipopolysaccharide, IL-1beta and tumor necrosis factor-alpha are capable of augmenting IL-8 production, IL-10 is a potent inhibitor of IL-8 synthesis and appears to play an auto-regulatory role. Regulation of the IL-8 gene is under the control of nuclear factor kappaB which appears to be a primary target for corticosteroid-mediated repression of IL-8 production. IL-8 exerts is effects on neutrophils by binding with high affinity to two receptors on its cell surface, the chemokine receptors CXCR1 and CXCR2. These closely related receptors belong to the superfamily of G-protein coupled receptors, proteins that historically have proved amenable to antagonism by small molecules. The recent descriptions in the literature of highly potent small molecule antagonists of CXCR2 and their success in blocking in vivo trafficking of neutrophils suggest that antagonism of IL-8 at the receptor level is a viable therapeutic strategy. Clinical trials of such compounds will ultimately provide crucial information currently lacking and will define whether or not IL-8 blockade provides future therapy in pulmonary disease.

Histamine stimulates alveolar macrophages to release neutrophil and monocyte chemotactic activity

Histamine and serotonin are important inflammatory mediators in the pathophysiology of asthma, and asthmatic patients have higher plasma histamine and serotonin levels than non-asthmatic control subjects. Alveolar macrophages (AMs) synthesize and secrete a large number of substances that play a key role in acute and chronic inflammation including asthma. We postulated that AMs might release chemotactic activity for neutrophils and monocytes in response to histamine or serotonin. To test this hypothesis, bovine AMs were cultured, and the supernatant fluids were evaluated for neutrophil chemotactic activity (NCA) and monocyte chemotactic activity (MCA) by a blind well chamber technique. AMs released chemotactic activity in response to histamine and serotonin in a dose- and time-dependent manner (P <.05). Partial characterization and molecular sieve column chromatography revealed that low-molecular-weight lipid-soluble activity was predominant. Lipoxygenase inhibitors significantly blocked the release of chemotactic activity. Leukotriene B(4) receptor antagonists blocked the chemotactic activity. Immunoreactive leukotriene B(4) significantly increased in supernatant fluids in response to histamine and serotonin. The receptor responsible for the release of chemotactic activity in response to histamine was the H2 receptor. These data demonstrate that AMs release NCA and MCA in response to histamine or serotonin (or both) and may modulate the inflammatory cell recruitment into the lung.

Sinusitis and asthma: associated airway diseases

Sinusitis and asthma often coexist in patients. In fact, these airways disorders are similar histologically, with tissue eosinophils, increased glandular tissue, and edema. Medical or surgical therapy for sinusitis often greatly improves asthma, suggesting that sinusitis may exacerbate asthma. Possible mechanisms by which asthma could be worsened by sinus disease include neural reflex pathways and interference with the important nasal functions of heating, humidification, and filtration. Health professionals treating asthmatic patients should consider sinusitis as a possible underlying cause, in addition to other triggers (e.g., allergic rhinitis and gastroesophageal reflux disease).

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.

Control of airway function during and after exercise in asthmatics

Control of airway function during and after exercise in asthmatics. Med. Sci. Sports Exerc., Vol. 31, No. 1 (Suppl.), pp. S4-S11, 1999. In asthmatics, airway function can be quite variable during exercise depending on the level of exercise intensity, the duration of exercise, and whether the exercise is at constant load or variable in intensity. Airway diameter can be affected by activity of parasympathetic and sympathetic nerves, by systemic mediators such as catecholamines, and by local mediators such as histamine or leukotrienes. Asthmatic airways are populated with more inflammatory cells than normal airways, and bronchoconstrictor mediator release from these cells is probably caused by drying of the mucosa during and after periods of increased ventilation. There are a few bronchodilating mediators present in both asthmatic and normal airways that could protect against this bronchoconstriction, including prostaglandin PGE2 and nitric oxide. Although it is clear that many of the inflammatory mediators play a role in causing bronchoconstriction after exercise, the role of either bronchoconstrictor or bronchodilator mediators in controlling airway function during exercise has yet to be resolved. In addition, the mechanical interaction between lung parenchyma and airways may provide a bronchodilating influence. In conclusion, the variability in airway function during exercise in asthmatics could be caused by balance among various bronchodilator and bronchoconstrictor mediators, but it may also reflect a mechanical effect of varying levels of ventilation.

Prevalence and characteristics of exercise-induced asthma in children

We have evaluated the prevalence and the characteristics of exercise-induced asthma (EIA) in a group of 71 patients with a prior history of mild, moderate or severe asthma (42 males and 29 females), aged 6-16 years-old. Measurements of the forced expiratory volume in 1 second (FEV1) were obtained before and at regular intervals up to 8 hours following exercise. As a control, the same patients were evaluated at similar time intervals on another day when they had not been submitted to an exercise challenge. Using pre-exercise FEV1 values as the reference, 32 patients (45.1%) had a positive exercise challenge, defined as a fall in FEV1 value equal to or greater than 15% from baseline following exercise. Among the patients with a positive exercise challenge, the majority (23/32, 71.8%) had an immediate response alone, with no significant changes in FEV1 within the 8-hour follow-up. However, a subgroup of patients (9/32, 28.1%) had both an immediate and a late-phase response to exercise. During the control day, no significant fall in FEV1 were observed. In keeping with previous investigations, no correlation was found between a history of EIA and a positive exercise challenge in the present study. Positive exercise challenges were found more frequently among patients with moderate and severe asthma than patients with mild asthma.

The occurrence of late asthmatic response to exercise after allergen challenge

BACKGROUND

The determinants of late asthmatic responses to exercise remain unknown. It has been reported that they may develop in some adult subjects with asthma following a late asthmatic response to allergen.

OBJECTIVE

We intended to corroborate this finding in children with asthma and to investigate which aspect of airway responses to allergen is associated with late asthmatic responses to exercise.

METHODS

We studied 17 children with allergic asthma, who showed late asthmatic responses to inhaled allergen (Dermatophagoides pteronyssinus). Each underwent an exercise challenge test two days before (pre-allergen) and two days after (postallergen) an allergen inhalation challenge. FEV1 was measured at regular intervals up to ten hours after each challenge. Methacholine PC20 was measured before the allergen challenge and before the postallergen exercise challenge.

RESULTS

After the pre-allergen exercise test, all the subjects showed isolated early asthmatic responses. After the postallergen exercise test, seven showed dual responses (early and late asthmatic responses) (group I) and the remaining ten showed isolated early asthmatic responses (group II). Bronchial responses to pre-allergen exercise or inhaled allergen and the severity of early asthmatic responses to postallergen exercise were similar in groups I and II. Neither before allergen inhalation nor before the postallergen exercise was methacholine PC20 different between the two groups. Methacholine dose shift caused by allergen challenge, however, was significantly greater in group I than in group II (-2.00+/-0.39 versus -1.36+/-0.53 doubling doses; P < .05). There was significant correlation between the dose shift and the magnitude of late response to the postallergen exercise in the whole group (r = 0.51, P < .05).

CONCLUSION

Late asthmatic responses to exercise may develop in some children with asthma following a late asthmatic response to allergen. This phenomenon was related neither to the baseline nor to postallergen methacholine PC20 but to the extent of increased sensitivity to methacholine caused by allergen challenge.

Late asthmatic response in exercise-induced asthma

BACKGROUND

There is a controversy over the occurrence of a late asthmatic response during exercise-induced asthma. While some workers have documented such a response as a genuine phenomenon, others have attributed this to drug withdrawal.

OBJECTIVES

We carried out the present study to investigate whether a late asthmatic response occurs during exercise-induced asthma as a genuine event and, if so, what are the factors which determine its occurrence.

METHODS

Sixteen, clinically stable asthmatic patients with laboratory-proven exercise-induced asthma underwent a standardized exercise challenge on a bicycle ergometer. The airway response to exercise was studied by spirometry to measure FEV1. Spirometry was carried out before the exercise, at 4, 8, 15, 30, and 60 minutes, and then hourly for the next 7 hours. Spirometry was also done repeatedly as above on a non-exercise control day, four to seven days earlier.

RESULTS

Eight (50%) subjects developed a second fall of greater than 10% in FEV1, three to eight hours after recovery from the early response. The late fall in FEV1 after exercise was significantly greater than the spontaneous decay of lung function at the corresponding clocktime on the non-exercise control day. The dual responders did not differ from those with isolated early responses with respect to age, duration and severity of asthma, treatment requirements, peripheral blood eosinophilia, and atopic status. Baseline FEV1 and maximum fall in FEV1 during the early response, and the rate of its development and recovery from it were also similar. Among the dual responders, the late response was not related to the baseline FEV1 or to the intensity of the early response.

CONCLUSIONS

A late asthmatic response is a genuine phenomenon in exercise-induced asthma. Its occurrence cannot however be predicted by any clinical or physiologic factors.

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.

BAL neutrophilia in asthmatic patients. A by-product of eosinophil recruitment?

Although neutrophil number may be increased in the airways of patients with asthma, its pathogenetic role in this disorder remains unclear. We evaluated BAL of 8 normal control subjects, 30 +/- 2 years of age, and 24 patients with mild asthma: 17 patients with allergic asthma, 24 +/- 1 years of age, and 7 patients with nonallergic asthma, 30 +/- 1 years of age. The BAL of asthmatic patients showed increased numbers of neutrophils (p < 0.01), eosinophils (p < 0.01), and ciliated epithelial cells (p < 0.05) and increased concentrations of myeloperoxidase (MPO) (p < 0.01) compared with control subjects. Positive correlations were observed between the number of BAL neutrophils and eosinophils (Rs = 0.780, p < 0.0001) and between BAL neutrophil numbers and BAL MPO levels (Rs = 0.40, p < 0.05). No correlations were found between the following: (1) BAL eosinophils or neutrophils and BAL epithelial cells (p > 0.05, each comparison); (2) BAL neutrophils or eosinophils and log Pd15 methacholine (MCh) (p > 0.05, each comparison); or (3) BAL epithelial cells or log Pd15 MCh and BAL MPO (p > 0.05, each comparison). Dividing the patient population into two groups, allergic asthmatics and nonallergic asthmatics, similar BAL neutrophil, eosinophil, and epithelial cell numbers and similar MPO levels were found (p > 0.05, each comparison). In addition, the correlations between BAL neutrophils and eosinophils showed similar significance in the two patient subgroups (p > 0.05, each comparison). These results suggest that, both in allergic and nonallergic asthma, airway recruitment and activation of neutrophils occur as does parallel eosinophil migration. However, airway neutrophils do not seem to contribute significantly to epithelial cell injury or to airway hyperresponsiveness in the steady state.

Comparison between allergen-induced and exercise-induced asthma with respect to the late asthmatic response, airway responsiveness, and Creola bodies in sputum

BACKGROUND

The difference between allergen-induced asthma and exercise-induced asthma with respect to the late asthmatic response and airway responsiveness has not been well elucidated.

OBJECTIVE

We compared the incidence of late asthmatic response, the changes in airway responsiveness, the degree of epithelial desquamation, and the activation of eosinophils in the airways after induction of allergen-induced asthma and exercise-induced asthma.

METHODS

Allergen-induced asthma or exercise-induced asthma was provoked in asthmatic patients, and sputum was collected before challenge and at the immediate asthmatic response and the late asthmatic response. Clusters of columnar epithelial cells in sputum (Creola bodies) were detected to evaluate respiratory epithelial damage, and the sputum eosinophil cationic protein (ECP) concentration was measured to evaluate eosinophil activation in the airways. Airway responsiveness was measured before and 48 hours after the challenge.

RESULTS

The maximal % fall in FEV1 with the late asthmatic response was significantly higher after induction of allergen-induced asthma than after exercise-induced asthma, even though the maximal % fall in FEV1 with the immediate asthmatic response was similar. Airway responsiveness increased significantly at 48 hours after allergen-induced asthma, while it did not change after exercise-induced asthma. The increase in airway responsiveness was not correlated with the maximal % fall in FEV1 with the late asthmatic response, but was correlated with the degree of epithelial damage evaluated by observation of Creola bodies. The sputum ECP concentration and the percentage of sputum eosinophils increased significantly with the late asthmatic response after allergen-induced asthma, but did not change after exercise-induced asthma.

CONCLUSIONS

We conclude that less airway inflammation was provoked by exercise-induced asthma resulting in less epithelial damage and no increase of airway responsiveness in contrast to allergen-induced asthma.

Hyperventilation during exercise: independence on exercise-induced bronchoconstriction in mild asthma

Ventilatory gas exchange during exercise was compared in patients with mild asthma (11 females and 11 males), hyperventilation syndrome (HVS, 11 females), and healthy subjects (11 females and 11 males) in order to assess hyperventilation during exercise and its association with exercise-induced bronchoconstriction. The asthmatics showed decreased working capacity and decreased maximal oxygen consumption, with no evidence of limitation due to impairment of ventilatory capacity. Ventilatory equivalents for CO2 and O2 (VE/VCO2 and VE/VO2) at rest did not differ between the controls and asthmatics, but they were significantly elevated in HVS. In female asthmatics, ventilatory equivalents during exercise were significantly (P < 0.05) elevated compared with those of healthy subjects; in female controls, VE/VCO2 was 30.1 +/- 3.3 at low exercise and 27.4 +/- 6.5 at maximal exercise. In female asthmatics, the corresponding figures were 34.9 +/- 6.1 and 36.7 +/- 5.3. Furthermore, VE/VCO2 individually related to percent of maximal oxygen consumption (VO2max) was significantly increased in female asthmatics both at low and high VO2. The highest ventilatory equivalents were obtained in HVS, 41.7 +/- 6.7 and 43.9 +/- 0.9, respectively. Significant exercise-induced bronchoconstriction (decrease of FEV1 > 15%) was found in 50% of the asthmatics. The ventilatory equivalents did not correlate with exercise-induced changes in FEV1 (r2 < 0.3). Mild exercise-induced hyperventilation which was observed in mild female asthmatics, did not appear to be related to exercise-induced bronchoconstriction.

Maximal airway narrowing on the dose-response curve to methacholine is increased after exercise-induced bronchoconstriction

The changes in airway responsiveness between before and after exercise in asthma are not well defined. We investigated the effect of exercise on PC20 (bronchial sensitivity) and maximal airway narrowing (MAN) on the dose-response curve to methacholine in 56 mildly asthmatic children. High-dose methacholine inhalation tests were performed before and 7 hr after exercise challenge. Methacholine PC20 was not changed by exercise, irrespective of exercise-induced bronchoconstriction (EIB). However, the subjects with (+)EIB displayed increased MAN after exercise, whereas those with (+/-)EIB or (-)EIB did not. The results showed that EIB may be followed by increased MAN but not by the change of bronchial sensitivity.

Exercise- and cold-induced asthma

Exercise- and cold-induced asthma are commonly recognized respiratory disorders. The asthmatic response includes several factors contributing to airway narrowing, and thus increased airway resistance. These include airway smooth muscle contraction, mucus accumulation, and bronchial vascular congestion as well as epithelial damage and vascular leakage. The etiology for these disorders is nonantigenic. The primary stimulus is probably a combination of airway cooling and drying (leading to hypertonicity of airway lining fluid). Symptoms generally do not occur during the stimulus period (e.g., exercise) itself. This protection may in part be due to increased catecholamine levels during exercise. The early phase response, which occurs 5 to 15 min poststimulus, may be mediated through a combination of (a) direct influences, (b) vagal reflexes triggered by airway sensory receptors, or (c) responses to mediator release. Spontaneous recovery occurs within 30 min to 2 hrs. There is usually a refractory period of about 1 to 2 hrs during which responses to further stimuli are attenuated. This may be due to depletion of histamine and other mediators. As well, prostaglandin release (mediated via LTD4 which is released during exercise) inhibits further airway narrowing. A late phase response has been reported 4 to 10 hrs poststimulus in some patients. These reactions are accompanied by a second release of histamine and other mediators that cause inflammatory responses and epithelial damage. However, the exercise dependence of this response is debated.

Airway responsiveness to allergen is increased 24 hours after exercise challenge

Although exercise is one of the most ubiquitous triggers of acute bouts of asthma, the changes in airway responsiveness before and after exercise are not well defined. Specifically, the effect of the changes in airway responsiveness induced by exercise has not been studied on subsequent allergen exposure. To test whether the reactivity to allergen is altered by preceding exercise and to define possible factors determining it, we subjected 24 children with atopic asthma to the relevant allergen challenge on two occasions: one as a control without a preceding procedure and the other 24 hours after exercise challenge. Mean postallergen maximal percent falls in forced expiratory volume in 1 second from baseline (delta FEV1) of the whole group were higher after the exercise challenge compared with those of control in both early (< 1 hour) and late (3 to 10 hours) phases. The changes of postallergen maximal delta FEV1 between the control and post-exercise allergen challenges were not related to the early bronchial response to the preceding exercise challenge. Late asthmatic responses to exercise developed in six children, and the changes in both early and late phases were significantly higher in these children, compared with those without late asthmatic responses. Furthermore, the changes were well correlated with the magnitude of the late-phase response to preceding exercise in the group as a whole. It is concluded that an increased airway responsiveness to allergen occurs 24 hours after exercise in some patients with asthma. As the changes are related to a late bronchial response to exercise, late asthmatic response to exercise, when it occurs, may be associated with increased asthmatic symptoms for as long as 24 hours after exercise.

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.

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.

Reproducibility of late phase pulmonary response to exercise and its relationship to bronchial hyperreactivity in children with chronic asthma

To determine the reproducibility of the delayed response to exercise and its effect on bronchial hyperreactivity, we had 26 asthmatic children perform treadmill exercise challenge on two occasions 1 week apart. Both challenges were preceded by 2 control days and 1 histamine challenge day, and were followed by another histamine challenge day. Peak expiratory flow rate (PEFR) was measured hourly for 12 hours on each control day and for 12 hours after each exercise or histamine challenge. During the first week, five patients showed a late reaction (PEFR change > 15%) after exercise, which was present in only two of them the following week. These two patients, however, also showed a spontaneous fall > 15% of PEFR from baseline during the other control study days. A similar pattern was seen in two other patients who had a late response during the second exercise challenge but not during the first. No significant change occurred in histamine PC-20 FEV1 between before and after the exercise challenges. An apparent late asthmatic response after exercise challenge may represent a within-day fluctuation in pulmonary mechanics that develops spontaneously in children with asthma.

Early and late-phase asthmatic reactions: a hypothesis

Why might a foreign particle, exercise or fog inhalation precipitate two asthmatic reactions? It is reasonable to suspect that asthmatic patients develop two reactions because healthy subjects may also develop two physiological responses to the same stimuli. This suggestion is supported by the observation that living things have developed adaptative systems to confront either sudden or persistent changes in the environment or within the internal milieu. The results of several studies suggest that the early phase response (EPR) usually involves cells which are normal residents of the respiratory epithelium (mast cells) and pre-formed substances (histamine), whereas cells participating in the late phase reaction (LPR) are recruited from the circulation (eosinophils, basophils and T cells). Up to now most of the studies of the EPR and LPR have been addressed to detecting a cell or metabolite abnormality. This simplistic approach would probably not improve the knowledge of the mechanisms involved in asthmatic responses. Since the presence of isolated or dual responses seems to depend on the intensity and duration of the stimuli it is reasonable to suspect that EPR and LPR are the result of an excessive adaptative response of the bodies of asthmatics to sudden and prolonged/strong stimuli, respectively.

Attenuation of exercise induced asthma by local hyperthermia

BACKGROUND

Prior treatment with local hyperthermia has been shown to prevent mast cell degranulation and leucocyte histamine release, and to reduce mortality and cellular infiltrates in a model of acute lung injury. Local hyperthermia is effective in reducing the symptoms of the common cold and perennial and seasonal allergic rhinitis, nasal patency also being improved in rhinitis. It is possible that these effects are mediated by common anti-inflammatory mechanisms, and that this treatment may be effective in the treatment of asthma. The effect of prior local hyperthermia on the response to exercise challenge and histamine bronchoprovocation was therefore examined.

METHODS

In a randomised, double blind, placebo controlled, crossover study, 10 asthmatic subjects with exercise induced asthma used machines delivering 40 1/minute of fully humidified air at either 42 degrees C (active treatment) or 31 degrees C (placebo treatment) for 30 minutes' tidal breathing. For each pretreatment, at two week intervals they underwent exercise challenges starting one and 24 hours after starting the inhalations. After a further two weeks the protocol was repeated with histamine substituted for the exercise challenges.

RESULTS

The mean (SE) maximum percentage fall in forced expiratory volume in one second (FEV1) was significantly lower one hour after treatment with air at 42 degrees C (30.8% (3.1%)) than after treatment with air at 31 degrees C (22.3% (2.9%)). There was no significant effect on exercise challenge at 24 hours, or on histamine challenge at either time point, though there were nonsignificant trends towards protection with exercise at 24 hours and with histamine at one hour.

CONCLUSION

In asthmatic subjects the response to exercise challenge is significantly attenuated one hour after treatment with local hyperthermia. This treatment warrants further investigation in the treatment of clinical asthma and other inflammatory disorders.

Exercise-induced bronchospasm. Achieving control in asthmatic patients

Exercise-induced bronchospasm is a common complication of asthma. Aggressive treatment of this conditions permits patients to maintain full activity despite their illness. Since most asthmatic patients are healthy except for an intermittent respiratory problem, providing them the opportunity to exercise in all weather conditions affords a clear improvement in their quality of life. Conceptualizing exercise-induced bronchospasm as a hyperreactive airway response to rapid inhalation of cool, dry air leads logically to the primary methods used to treat this disorder.

Exercise response in 404 young men with asthma: no evidence for a late asthmatic reaction

As the existence of a late reaction in exercise induced asthma is controversial, peak expiratory flow (PEF) was measured for up to 13 hours after a running test in 404 consecutive young male army conscripts undergoing assessment of their asthma. In 294 subjects (73%) the immediate post-exercise fall in PEF was 10% or more; the mean (SD) fall in PEF in this group was 27% (15%). Nine patients with exercise induced asthma had a fall in PEF of 20% or more 4-13 hours after the exercise test. In these possible "late responders," however, the change in PEF 4-13 hours after exercise was similar to the change in PEF on control days before and after the exercise day, and the lowest PEF during this period was similar to the lowest measurements on the control days. These nine subjects showed pre-exercise bronchodilatation. Their pre-exercise PEF, from which the percentage fall in PEF was calculated, was 24% (9%) higher than the mean PEF level on control days. This study supports the view that what appears to be a "late asthmatic reaction" after exercise is an artefact. Spontaneous within day fluctuation in pulmonary function, pre-exercise bronchodilatation, and the fact that airflow obstruction persists after the early postexercise response may give a false impression of an exercise induced late asthmatic response in patients with labile airways.

The significance of late responses in asthma

There is good evidence to suggest that the late response is a valid clinical model of asthma. The factors which predict late responses in individual subjects are unknown although recent studies suggest that the level of IgE sensitivity and allergen dose are two important variables. Recent placebo-controlled pharmacological studies support earlier work and vindicate the use of late responses as a preclinical screening test in the evaluation of new therapeutic agents. In addition to putative pro-inflammatory mechanisms we should evaluate possible protective mechanisms which might prevent the development of late responses in individual subjects. In this regard, altered adrenal responses as reflected by serum cortisol concentrations did not appear to play a role, protective or otherwise in the development of late asthmatic responses. In conclusion, the development of symptomatic late responses and associated increased bronchial responsiveness are relevant to day-to-day asthma. As suggested by Cockcroft, repeated allergen exposure may result in a vicious cycle of ongoing bronchial inflammation. This emphasizes the importance of allergen avoidance and the need for earlier intervention in mild to moderate asthma with effective prophylactic agents which are known to inhibit late responses.

Cold air challenge for measuring airway reactivity in children: lack of a late asthmatic reaction

Cold air challenge (CACh) for measuring airway reactivity uses respiratory heat or water loss as a bronchoconstrictor stimulus; this stimulus is also important for the development of exercise-induced asthma, for which late asthmatic reactions (LARs) have been described. At 1200 hr on day 1, 22 children with asthma started to record their peak expiratory flow rate (PEFR) in 3 hr intervals until 0900 hr on day 2. At 1000 hr, they underwent a standardized 4 min CACh. Children then inhaled salbutamol and continued to record PEFR until 0900 hr on day 3. As a bronchodilator effect, PEFR measurements were significantly higher 2, 5, and 8 hr after CACh, but subsequently did not differ significantly from pre-CACh values. At 5 hr after CACh, individual values ranged from 95 to 137% of the corresponding pre-CACh measurements, at 8 hr from 94 to 150%, and at 11 hr from 80 to 121%. This random sample of children with asthma demonstrated no LAR after CACh.

Allergen dose response and late symptoms in a human model of ocular allergy

Eleven ryegrass-sensitive patients were challenged weekly for 4 weeks with incremental doses of ryegrass allergen applied topically to one eye; a buffer was applied to the other eye. A clinical examination and tear-fluid cytology were performed before challenge and at 20 minutes, 1 hour, and 6 hours after challenge. A significant clinical reaction and neutrophil accumulation in the tear film occurred at 20 minutes. At 1 hour, a clinical response and tear cytologic reaction were present only at higher antigen concentrations. Six hours after antigen challenge, only the highest allergen concentration (320,000 BU/ml) produced a clinical late-phase reaction (LPR) (p less than 0.01) and tear cytologic change (presence of eosinophils and lymphocytes). Five nonryegrass-sensitive control subjects were unresponsive to a similar challenge. These results indicate that a conjunctival response to allergen challenge is dose dependent, that is, the higher the dose, the more likely an LPR will occur and that an LPR correlates with significant numbers of inflammatory cells in the tear film.

Real and pseudo late asthmatic reactions after submaximal exercise challenge in patients with bronchial asthma. A new definition for late asthmatic responses after exercise challenge

The late asthmatic reaction after exercise challenge remains a controversial issue. In this study, 21 patients recorded peak expiratory flow rate (PEFR) on two control days without performing exercise. There was no difference between both control days when PEFR at 1 h was compared with baseline PEFR and when PEFR at 4 to 13 hours was compared with baseline PEFR. After analyzing variation coefficients of baseline PEFR on a control day and exercise day, PEFR was not allowed to differ more than 15.3 percent in the same patient when comparing exercise day and control day for the late fall in PEFR in the study. In 17 of 81 patients, a late asthmatic reaction after exercise challenge was present when PEFR fall was greater than or equal to 20 percent compared with baseline PEFR value. In eight of the 17 patients, a real late asthmatic reaction to exercise challenge was present with a PEFR fall greater than or equal to 20 percent on at least three successive time points and who had a PEFR fall greater than or equal to 20 percent compared with corresponding clocktime on a control day. The late asthmatic reaction to exercise challenge is characterized not as a nonspecific epiphenomenon, but as a fall in PEFR of greater than or equal to 20 percent compared with baseline PEFR value and with corresponding clocktime on a control day on at least three successive time points. Graphic illustration of airway responses following exercises may facilitate the detection of a late asthmatic response.

Chemical mediators in hypersensitivity reactions

The study of chemical mediators is essential in clarifying the mechanism of hypersensitivity reactions. Recent advances in this field have been made particularly with the arachidonic acid metabolites, several of which strongly contract smooth muscle, attract granulocytes to inflammatory foci and lead to increased vascular permeability. These functions play a crucial role in allergic reactions. Furthermore these mediators might work to modulate the intracellular network which mediates the complicated inflammatory process of hypersensitivity reactions.

Exercise-induced asthma and the generation of neutrophil chemotactic activity

Heat-stable neutrophil chemotactic activity (HS NCA) has been demonstrated in serum of subjects with asthma after exercise and after allergen inhalation challenge. Heat-labile neutrophil chemotactic activity (HL NCA) has been investigated only after allergen inhalation challenge. In this study, we have measured HS NCA and HL NCA after exercise of 22 adult patients with asthma, 13 of whom had exercise-induced asthma (EIA). In the 13 patients, the effect of pharmacologic pretreatment on the generation of HS NCA and EIA was evaluated in a double-blind study with inhalation of either disodium cromoglycate, terbutaline, or budesonide 15 minutes before exercise. Additionally, the effect of 4 weeks of treatment with budesonide aerosol was evaluated in an open study. A significant increase (p less than 0.01) in HS NCA was found in the patients with EIA with peak activities 15 minutes after exercise. In patients without EIA, the activity of HS NCA was variable. No HL NCA was detectable after exercise. EIA was inhibited by disodium chromoglycate, terbutaline, and 4 weeks of treatment with budesonide. The generation of HS NCA was more or less inhibited by all three drugs with 4 weeks of treatment with budesonide as the most potent regimen. No late-phase asthmatic reactions to exercise were found. It is concluded that only HS NCA is generated after exercise of subjects with asthma and that this production is controlled by antiasthmatic drugs. However, the generation of HS NCA occurs irrespective of EIA.