Asthma variability in patients previously treated with beta2-agonists alone

BACKGROUND

According to national asthma guidelines, asthma severity can be classified as intermittent, mild, moderate, or severe on the basis of lung function, symptoms, nighttime awakenings, and exacerbations. Although it is widely believed that patients might not remain consistently in any given severity category over time, few studies have examined this directly.

OBJECTIVE

We sought to assess the variability in disease severity-control among patients with persistent asthma who have not yet received an asthma maintenance treatment.

METHODS

We performed an analysis of asthma severity-control over time in placebo-treated patients (n = 85) from 2 randomized, double-blind, 12-week clinical trials in patients with asthma previously receiving beta(2)-agonists alone. Asthma severity-control was assessed on the basis of morning percent predicted peak expiratory flow, albuterol use, and symptoms.

RESULTS

At baseline, all patients met the criteria for moderate or severe persistent asthma (mean FEV(1) of 64% of predicted value or albuterol use and symptoms on 4.7 and 6.0 days per week, respectively). The mean percentage of treatment weeks that patients met all criteria for intermittent, mild, moderate, and severe asthma were 9%, 14%, 71%, and 6%, respectively. On the basis of morning peak expiratory flow, patients were classified as having intermittent-mild, moderate, or severe disease on 52%, 41%, and 7% of days, respectively. With regard to days per week with albuterol use or asthma symptoms, patients spent 59% and 45% of weeks, respectively, in the intermittent and mild categories.

CONCLUSION

Asthma control cannot be adequately assessed in many patients by using discrete point-in-time assessments of lung function, short-acting beta-agonist use, or asthma symptoms. This might lead to underestimation of disease severity and contribute to inadequate therapy and, ultimately, asthma morbidity.

Low-dose carbon monoxide reduces airway hyperresponsiveness in mice

Carbon monoxide (CO) in expired gas has been shown to be elevated with asthma; however, its function is not known, and there is some potential that it may serve a bronchoprotective role to decrease airway hyperresponsiveness (AHR). Thus the ability of CO to reverse methacholine (MCh)-induced bronchoconstriction was evaluated in C57BL/6 (C57) and A/J mice with and without airway inflammation produced by ovalbumin (OVA). Acutely administered CO (1% in air, 10 min) reduced MCh-driven increases in lung resistance in OVA-challenged C57 mice by an average of 50% (from 14.5 to 7.1 cmH2O.ml-1.s-1), whereas no effect was observed in naïve C57 mice or OVA-challenged C57 mice inhaling air alone. Acutely inhaled CO (500 ppm = 0.05%, for 10 min) reduced MCh-induced airway reactivity (AR) by 20-60% in airway hyperresponsive naïve A/J mice, whereas repeated 10-min administrations of 500 ppm CO over a 5-day period decreased AR by 50%. Repeated administration of low-dose CO [250 (0.025%) and (0.05%) 500 ppm, 1 h/day, 5 days] to A/J mice with airway inflammation likewise resulted in a drop of AR by 50%, compared with those not receiving CO. Inhibition of guanylyl cyclase/guanosine 3',5'-cyclic monophosphothioate (cGMP) using 1H-[1,2,4] oxydiazolo[4,3-a]quinoxalin-1-one or a competitive inhibitor, Rp diastereomers of 8-bromo-cGMP, resulted in inhibition of the effect of CO on AHR, suggesting that the effects of CO were mediated through this mechanism. These results indicate that low-dose CO can effectively reverse AHR in the presence and absence of airway inflammation in mice and suggest a potential role for CO in the modulation of AHR.

Nocturnal asthma

Lung function in a healthy individual varies in a circadian rhythm, with peak lung function occurring near 4:00 PM (1600 hours) and minimal lung function occurring near 4:00 AM (0400 hours). An episode of nocturnal asthma is characterized by an exaggeration in this normal variation in lung function from daytime to nighttime, with diurnal changes in pulmonary function generally of > 15%. The occurrence of nocturnal asthma is associated with increased morbidity and inadequate asthma control, and has an important negative impact on quality of life (QOL). Newer data have shed light on physiologic and immunologic mechanisms that underlie the nocturnal development of airway obstruction. It remains controversial whether nocturnal asthma is a distinct entity or is a manifestation of more severe asthma. The current data do not resolve these two alternatives, as well-controlled studies have reached opposite conclusions. However, the clinical associations of gastroesophageal reflux disease and obesity appear to be strong. The treatment of asthma with effective controller agents can reduce nighttime symptoms, improve psychometric outcomes, and improve QOL.

Regulation of IL-1beta -induced GM-CSF production in human airway smooth muscle cells by carbon monoxide

Asthma, a chronic inflammatory disease of the airways, involves the increased expression of inflammatory mediators, including granulocyte-monocyte colony-stimulating factor (GM-CSF). Heme oxygenase-1 (HO-1), a stress-response protein, confers protection against oxidative stress. We hypothesized that carbon monoxide (CO), a byproduct of HO-1-dependent heme catabolism, regulates GM-CSF synthesis in human airway smooth muscle cells (HASMC). IL-1beta treatment induced a time-dependent induction of GM-CSF in HASMC. Furthermore, IL-1beta stimulated the major MAPK pathways, including ERK1/ERK2, JNK, and p38 MAPK. Exposure of HASMC to CO at low concentration (250 ppm) markedly inhibited IL-1beta-induced GM-CSF synthesis (>90%) compared with air-treated controls. CO treatment inhibited IL-1beta-induced ERK1/2 activation but did not inhibit JNK and p38 MAPK. Furthermore, CO increased cGMP levels in HASMC. Inhibition of guanylate cyclase by IH-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-1 (ODQ) abolished the inhibitory effects of CO on GM-CSF synthesis and ERK1/2 activation. Collectively, these data demonstrate that the inhibitory effect of CO on GM-CSF synthesis depends on ERK1/2 MAPK and guanylate cyclase/cGMP-dependent pathways.

Increased nitric oxide production by airway cells of sensitized and challenged IL-10 knockout mice

The anti-inflammatory cytokine interleukin (IL)-10 suppresses inducible nitric oxide synthase (iNOS); therefore, NO production should increase in the absence of IL-10. Production of NO (as nitrite) by bronchoalveolar lavage cells of IL-10 knockout ((-/-)) mice was assessed after ovalbumin sensitization and airway challenge (S/C) and was compared with the IL-10-sufficient, wild-type (WT) C57Bl6. Eosinophil recruitment occurred in S/C WT and IL-10(-/-) mice, suggesting allergic airway inflammation. Alveolar macrophages (per g mouse) were unchanged (approximately 3x10(4) cells) with the exception of a doubling in the S/C IL-10(-/-) mice (approximately 6x10(4) cells, P<0.05). NO production (per million cells) was doubled in cells from S/C IL-10(-/-) (15.3 microM) mice compared with WT (7.6 microM, P<0.05). Inhibition of iNOS by L-N(5)-(1-iminoethyl)-ornithine reduced NO production in all S/C mice, confirming that the increase was a result of up-regulation of iNOS. We conclude that IL-10 is a critical cytokine regulating iNOS in murine airway cells and that its absence can lead to up-regulation of iNOS and development of allergic airway inflammation.

Comparison of fluticasone propionate-salmeterol combination therapy and montelukast in patients who are symptomatic on short-acting beta(2)-agonists alone

The objective of this study was to determine whether initial maintenance therapy for the treatment of inflammation and bronchoconstriction associated with persistent asthma is more effective with a combination product (100 microg of fluticasone propionate and 50 microg of salmeterol [FSC]) administered twice daily through the Diskus device (GlaxoWellcome, Research Triangle Park, NC) or with montelukast at 10 mg once daily. A 12-wk, randomized, double-blind, double-dummy, multicenter study was conducted with 423 patients 15 yr of age and older with asthma and who were symptomatic while receiving short-acting beta(2)-agonists alone. At end point, FSC resulted in significantly greater increases in morning predose FEV(1) (0.54 +/- 0.03 vs. 0.27 +/- 0.03 L), morning peak expiratory flow (PEF) (89.9 +/- 6.7 vs. 34.2 +/- 4.7 L/min), evening PEF (69.9 +/- 5.8 vs. 31.1 +/- 4.5 L/min), the percentage of symptom-free days (48.9 +/- 2.9 vs. 21.7 +/- 2.5%), the percentage of rescue-free days (53.0 +/- 2.8 vs. 26.2 +/- 2.5%), and the percentage of nights with no awakenings (23.0 +/- 2.5 vs. 15.5+/-2.4%) compared with montelukast (p < or = 0.001, all comparisons). FSC significantly reduced asthma symptom scores (-1.0 +/- 0.1 vs. -0.6 +/- 0.1), rescue albuterol use (-3.3 +/- 0.2 vs. -1.9 +/- 0.2 puffs/d), and the number of exacerbations (0 vs. 11) compared with montelukast (p < 0.001). Both treatments were well tolerated. In summary, treatment of the two main components of asthma (inflammation and bronchoconstriction) with fluticasone propionate and salmeterol in a combination product was a more effective initial maintenance treatment strategy than treatment with montelukast, a single-mediator antagonist.

Anti-leukotrienes for asthma

The field of cysteinyl leukotriene research has moved forward considerably in the past two years. Significant recent advances have been made in three areas: genetic control of the cysteinyl leukotriene response, in which alterations in both the promoter region and in transcribed mRNA have been described; the mechanisms by which cysteinyl leukotrienes promote the development of inflammation; and extensions in the clinical arena that support broader positioning of leukotriene modifiers in the therapy of asthma and allergic diseases.

The effect of salmeterol on markers of airway inflammation following segmental allergen challenge

Inflammation is a critical component of asthma. Drugs that control asthma generally reduce the degree of airway inflammation. There is theoretical controversy surrounding the effects of beta(2)-agonists on airway inflammation, with some studies suggesting an anti-inflammatory effect, and others predicting a proinflammatory influence. We conducted a double-blind, placebo-controlled, crossover study of the effect of the long-acting beta(2)-agonist salmeterol on airway inflammation induced by segmental allergen challenge (SAC). We studied 13 allergic asthmatics controlled with as needed inhaled short-acting beta(2)-agonists alone, and used bronchoalveolar lavage 5 min and 48 h after SAC to assess airway inflammation, and the effects of salmeterol on this process. Salmeterol therapy improved FEV(1), but had no significant effect on the immediate or late cellular response to SAC. One measure of superoxide production was reduced, and interleukin-4 (IL-4) was reduced in baseline samples, but other indices of airway inflammation were unchanged by salmeterol therapy. We conclude that salmeterol therapy alone does not meaningfully reduce airway inflammation induced by SAC, but equally importantly, does not result in amplified inflammation.

Current outpatient management of asthma shows poor compliance with International Consensus Guidelines

STUDY OBJECTIVE

This study aimed to establish whether the outpatient management of patients presenting with an asthma exacerbation to the emergency department (ED) was in compliance with the 1992 guidelines of the "International Consensus Report on the Diagnosis and Management of Asthma."

DESIGN

Prospective, observational study using a researcher-administered questionnaire.

SETTING

University tertiary referral ED.

PATIENTS

Convenience sample of asthmatics (aged 18 to 54 years) presenting for asthma treatment between July 1, 1997, and June 30, 1998.

RESULTS

Eighty-five asthmatic patients were enrolled. Of these, 34 patients (40%) smoked, 53 patients (62%) were undertreated with medication when compared to the consensus guidelines, and 74 patients (87%) had no written "plan of action." During an asthma attack, 9 patients (11%) did not use a bronchodilator as first-line action and 76 patients (89%) did not commence or increase the use of an inhaled steroid. Forty-nine patients (58%) did not know that bronchospasm occurred in asthma, and 53 patients (62%) did not know that bronchial swelling occurred. Twenty-six patients (31%) thought short-acting bronchodilator drugs were asthma preventers. Sixty-two patients (73%) could not adequately define peak expiratory flow (PF), 41 patients (48%) did not own a PF meter, and only 8 patients (9%) determined their PF daily. Fifty-three patients (62%) were reviewed by a physician once a year or less, and 18 patients (21%) noted family and friends as their only source of asthma education.

CONCLUSIONS

The outpatient management of most asthma patients presenting to the ED did not comply with the consensus guidelines, and asthma knowledge was poor.

Differential effects of respiratory syncytial virus and adenovirus on mononuclear cell cytokine responses

Respiratory syncytial virus (RSV) and adenovirus (Advs) serotype 3 (Adv3) and 7h (Adv7h) are associated with mild to severe respiratory infection and are indistinguishable during the acute phases of the illnesses. However, outcome and long-term prognosis are different with both infections. RSV infection is associated with later development of asthma, and Adv, mainly Adv7h, with severe lung damage, bronchiectasis, and hyperlucent lung. We hypothesized that this difference could be partly due to different immune responses induced by these viruses. To test this hypothesis we quantified TCD4+, TCD8+, and BCD19+ expressing the interleukin-2 receptor-alpha chain (CD25) and interferon-gamma (IFN-gamma), interleukin (IL)-10, and IL-4 in the supernatant of peripheral blood mononuclear cells (PBMC) from school children infected in vitro with and without RSV, Adv7h, and Adv3 and after phytohemagglutinin (PHA) stimulation in the presence or absence of these viruses at a multiplicity of infection (MOI) of 1. PBMC from every child produced more IL-10 (p </= 0.05) when infected with RSV than with Advs and noninfected control, and Adv induced more (p </= 0.05) IFN-gamma than did RSV and control. The IL-10/IFN-gamma ratio was significantly higher (p </= 0.05) in RSV-infected and significantly lower (p </= 0.05) in Adv-infected PBMC, than in noninfected cells. PHA-stimulated BCD19+ RSV- infected cells expressed more (p </= 0.05) IL-2R than did Adv-infected cells. These results suggest that Advs induce a Th-1-type immune response that is not seen with RSV. These patterns persist despite intersubject variation in the absolute quantity of cytokine produced.

Asthma entities

Asthma is a syndrome characterized by variable airflow limitation, airway hyperresponsiveness and airway inflammation. Considering asthma in aggregate, it is clear that a number of distinct mechanisms underlie the development of this disorder. In some patients, the mechanistic distinctions can be clearly drawn, and important therapeutic insights can be gained. In other patients, several mechanisms may coexist, or it may be impossible to separate them with current methods and technology. To distinguish subsets of asthma is more than an academic exercise. For both clinicians and asthma researchers, it is valuable to distinguish asthma subtypes as clearly as possible. Clinicians strive to prescribe the most effective, most safe, and most cost effective therapy possible, and understanding asthma subsets and their underlying mechanistic differences can substantively facilitate achieving that objective. Asthma research is often limited by significant, and sometimes dramatic intersubject variability. It is likely that at least some of that variability may arise from the (unrecognized) mechanistic heterogeneity of asthma. Better definition and selection of more homogeneous subsets of asthma may then lead to greater statistical power, and more definitive conclusions from asthma investigations.

Zafirlukast improves asthma symptoms and quality of life in patients with moderate reversible airflow obstruction

BACKGROUND

Previous trials demonstrated the effectiveness of the leukotriene receptor antagonist zafirlukast in patients with mild-to-moderate asthma.

OBJECTIVES

We sought to assess the efficacy and safety of zafirlukast and its effect on patients' quality of life (QOL) during a 13-week, double-blind, placebo-controlled, multicenter trial in adults and adolescents with moderate reversible airflow obstruction.

METHODS

Patients (age range, 12 to 68 years) with total daytime asthma symptoms scores of 10 or greater over 7 consecutive days (maximum, 21/wk), FEV1 45% or greater but less than or equal to 80% of predicted value (>/=6 hours after beta2 -agonist), and reversible airway disease were randomized to 20 mg zafirlukast twice daily (nZ = 231) or placebo twice daily (nP = 223). Efficacy was assessed from changes in daytime and nocturnal symptoms, beta2 -agonist use, nasal congestion score, and pulmonary function. QOL was evaluated with a disease-specific Asthma Quality of Life Questionnaire. Safety was determined from adverse event information and clinical laboratory test results.

RESULTS

Zafirlukast was significantly (P <.001) more effective than placebo, with reductions from baseline in the daytime asthma symptoms score (-23%), nighttime awakenings with asthma (-19%), and beta2 -agonist use (-24%) and improvements from baseline in morning (+25 L/min) and evening (+18 L/min) peak expiratory flow rates. Compared with placebo, zafirlukast significantly (P </=.018) improved scores for QOL domains (activity limitations, symptoms, emotional function, and exposure to environmental stimuli) and overall QOL, with a significantly greater proportion of zafirlukast-treated patients demonstrating clinically meaningful improvements (>/=0.5-unit change from baseline; P </=.037). The safety profile of zafirlukast was clinically indistinguishable from that of placebo.

CONCLUSIONS

Zafirlukast is effective and well tolerated and improves QOL in the long-term treatment of patients with moderate reversible airflow obstruction.

Summary of clinical trials with zafirlukast

Zafirlukast is an orally active and selective cysteinyl leukotriene (cysLT) receptor antagonist. In humans, zafirlukast antagonized the effects of exogenously administered LTD4 and cysLTs released endogenously in response to physical and chemical stimuli. Zafirlukast antagonized LTD4-induced bronchoconstriction, with effects still evident 12 h after drug administration. In clinical models of asthma, zafirlukast inhibited bronchospasm after allergen or exercise challenge in patients with asthma. In multicenter trials in patients with chronic, stable asthma, zafirlukast reduced asthma symptoms, decreased as-needed beta-agonist use, and improved pulmonary function without increasing the number of adverse events. Zafirlukast also exhibited evidence of an anti-inflammatory effect in the lung in preliminary studies involving segmental antigen challenge. The results from these clinical trials demonstrate that zafirlukast is effective and safe for the prophylactic treatment of asthma.

Effect of zafirlukast (Accolate) on cellular mediators of inflammation: bronchoalveolar lavage fluid findings after segmental antigen challenge

The effect of zafirlukast (Z) to alter the inflammatory response to segmental antigen challenge (SAC) was assessed by bronchoalveolar lavage (BAL) in this double-blind, placebo-controlled, two-period, crossover trial in 11 allergic asthmatic patients. Patients with asthma and positive skin tests to antigen received 7 d of treatment with Z (20 mg twice daily) or placebo (P) during two trial periods 14 to 21 d apart. At steady state (Day 5), patients underwent SAC followed by BAL immediately after challenge and 48 h later. Purified alveolar macrophages were analyzed ex vivo for phorbol myristate acetate (PMA)-driven superoxide release. Results were analyzed by analysis of variance (ANOVA). Forty-eight hours after SAC, Z therapy was associated with significantly reduced BAL lymphocytes and alcian blue-positive cells (presumably basophils) compared with P (p < 0.01), with a trend toward reduced numbers of alveolar macrophages (p = 0.06). PMA-driven superoxide release by purified alveolar macrophages was significantly reduced 48 h after SAC in the Z versus P arms (p < 0.05). Reduction of basophil influx, mediator release, and cellular activation may be important in attenuating the late phase of asthma. Collectively, the data suggest that zafirlukast therapy alters cellular infiltration and activation associated with antigen challenge.

Investigative use of bronchoscopy in asthma

The incorporation of bronchoscopy and bronchoscopic procedures into the investigation of asthma mechanisms, treatment, and in particular, the role of airway inflammation has contributed significantly to the enhanced understanding of this disease. Carefully drafted guidelines have allowed the gradual inclusion of subjects with more severe disease in studies utilizing bronchoscopic investigative tools. Many more questions remained unanswered, including the importance of persistence of airway inflammation in asymptomatic asthma, the specific antiinflammatory effects of new (and old) asthma therapies, the contribution of airway structural changes (subepithelial fibrosis) to nonreversible obstruction, the role of antiinflammatory versus proinflammatory cytokines in the pathogenesis of airway inflammation and the heterogeneity of disease expression in various groups of subjects. We are confident that current and future meticulously designed and executed research studies utilizing bronchoscopic techniques will significantly add to our knowledge of disease mechanisms and lead us to new and improved treatments for asthma.

Respiratory syncytial virus infection in infants is associated with predominant Th-2-like response

Viral infections have been associated with cellular immune responses and production of Th-1 cytokines. Respiratory syncytial virus (RSV), however, induces virus-specific IgE, which might be a consequence of a Th-2-like activation. To test this hypothesis we quantified interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in the supernatant of peripheral blood mononuclear cells cultured for 24 and 48 h in the presence or absence of phytohemaglutinin and pokeweed mitogen and the lymphocyte phenotypes to analyze subsets and their activation markers, from 15 hospitalized infants during an acute lower respiratory infection caused by RSV and 17 healthy control infants from 1 to 15 mo of age. Compared with the control infants, those infected with RSV had an increase in the number of B-cells (p < 0.02) and decreases in both CD8+ T-cells (p < 0.01) and activated CD8+/CD25+ suppressor/ cytotoxic T-cells (p < 0.007). In RSV-infected infants, IFN-gamma production was subtotally suppressed, whereas IL-4 production was decreased to a lesser degree, giving significantly (p < 0.001) increased IL-4/IFN-gamma ratio compared with that in the control infants. These findings suggest a predominant Th-z-like response in RSV-infected infants, which could explain some aspects of the immunopathogenesis of RSV infection and the RSV-specific and nonspecific IgE antibody responses observed.

The immediate and late allergic response to segmental bronchopulmonary provocation in asthma

The response to antigen is an important factor in the development of airway inflammation. Segmental bronchoprovocation (SBP) with antigen and subsequent bronchoalveolar lavage (BAL) have provided valuable insight into the mechanisms of allergic inflammation. To determine the features of allergic airway response in asthma, 19 subjects with mild asthma underwent antigen SBP in a dose-dependent manner. The amount of antigen used in SBP was 0 (saline), and 1, 5, or 20% of the antigen dose required to drop the FEV1 by 20% (APD20). BAL was done at 5 min and 48 h after SBP. BAL histamine levels increased modestly 5 min after antigen SBP. At 48 h, there was a marked increase in eosinophils and IL-5 concentration even in airway segments where the release of histamine was small. Moreover, eosinophils correlated with IL-5 levels at 48 h (r = 0.63; p < 0.001), but not with BAL histamine concentrations at 5 min. GM-CSF levels did not increase after antigen SBP and did not correlate with eosinophils. These observations indicate that asthmatic subjects can develop a dose-dependent response to antigen SBP that is characterized by a modest increase in histamine immediately after antigen exposure, and marked eosinophilia, which appears proportionately greater than the histamine response and relatively greater than what is seen in allergic nonasthmatic subjects. This feature might be important to the eventual development of airway inflammation in asthma.

Effect of nedocromil sodium pretreatment on the immediate and late responses of the airway to segmental antigen challenge

In many patients with asthma, exposure to allergen results in worsening symptoms, pulmonary dysfunction, and increased airway inflammation. In this study, segmental allergen challenge and bronchoalveolar lavage were used to evaluate the airway responses at 5 minutes and 48 hours and to study the extent of inhibition of the response by pretreatment with nedocromil sodium in eight subjects with allergic asthma in a double-blind, placebo-controlled trial. At 5 minutes after challenge, nedocromil sodium pretreatment significantly reduced histamine concentrations, with a trend toward a concomitant reduction in tryptase levels. Nedocromil sodium did not affect the increase in total protein, total cell counts, or cell concentrations that occurred 48 hours after challenge, but it did significantly reduce eosinophil recruitment. Eosinophil activation, assessed as release of granule proteins, was unaffected. A significant positive correlation was shown between the degree of histamine reduction at 5 minutes and the degree of reduction of eosinophil influx at 48 hours, raising the possibility that eosinophil influx into the airway may depend on mediators or cytokines released during the immediate response to allergen.

Elevated TNF-alpha production by peripheral blood monocytes of weight-losing COPD patients

The inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1 beta), have been associated with accelerated metabolism and protein turnover following exogenous administration in normal humans. We hypothesized that these inflammatory cytokines might contribute to the weight-losing process in patients with chronic obstructive pulmonary disease (COPD). COPD patients were identified prospectively as "weight losers" (WL; n = 10) if they reported > 5% weight loss during the preceding year or as "weight stable" (WS; n = 10) if their body weight fluctuated < or = 5%. Age-matched healthy volunteers were selected as the control group (C; n = 13). Monocytes were isolated from a peripheral blood sample, cultured, and exposed to lipopolysaccharide (LPS). The concentration of TNF-alpha and IL-1 beta in the monocyte supernatant was measured using a four layer enhanced ELISA. No significant difference in LPS-stimulated IL-1 beta production was found in the three study populations. However, LPS-stimulated TNF-alpha production (mean [range] ng/ml) by monocytes was significantly higher in the WL COPD patients (20.2 [6.3 to 44.8]), compared with WS patients (6.9 [1.5 to 16.6]), and C subjects (5.7 [0 to 61.8]). This difference was not maintained at 6 mo follow-up in the absence of ongoing weight loss. Definition of a causal relationship between TNF-alpha production and weight loss will require further understanding of the relationship between energy metabolism and TNF-alpha production in these patients.

Effect of interleukin-5 and granulocyte-macrophage colony stimulating factor on in vitro eosinophil function: comparison with airway eosinophils

Eosinophils are hypothesized to be crucial in the development of allergic airway inflammation; however, the actual mechanisms that determine their inflammatory activity are still largely undefined. To investigate the factors that regulate eosinophil function in allergic airway disease, we have previously used segmental bronchoprovocation with allergen to study ex vivo eosinophil function. To determine whether the functional changes associated with airway eosinophils obtained by bronchoalveolar lavage 48 hours after antigen challenge are caused by exposure to airway-generated cytokines, normodense blood eosinophils were cultured in vitro with recombinant human interleukin-5 (IL-5) or granulocyte-macrophage colony stimulating factor (GM-CSF). The effect of cytokine exposure was then evaluated on selected cell functions. In vitro incubation with these cytokines for 24 hours significantly increased eosinophil membrane expression of CD18 and CD11b compared with culture in medium alone or eosinophils obtained by bronchoalveolar lavage. N-formyl-methionyl-leucyl-phenylalanine-stimulated superoxide anion generation was slightly but significantly enhanced by incubation with IL-5 but not with GM-CSF. In addition, spontaneous adhesion to human umbilical vein endothelial cell monolayers was increased after exposure to both IL-5 and GM-CSF. However, activated adhesion was enhanced only by culture with IL-5 and stimulation with N-formyl-methionyl-leucyl-phenylalanine. The magnitude of functional changes after in vitro preincubation of eosinophils with these cytokines did not achieve levels of superoxide anion and adhesion noted with airway eosinophils obtained after segmental bronchoprovocation with allergen. These observations raise the possibility that the contribution of IL-5 and GM-CSF to phenotypic changes of airway eosinophils is principally to enhance survival and expression of adhesion proteins. These data also suggest that, in addition to the generation of proinflammatory cytokines, other factors contribute to phenotypic changes in eosinophils as they migrate from the blood to the airway.

A common cold virus, rhinovirus 16, potentiates airway inflammation after segmental antigen bronchoprovocation in allergic subjects

Many patients with asthma have increased wheezing with colds. We hypothesized that rhinovirus colds might increase asthma by augmenting airway allergic responses (histamine release and eosinophil influx) after antigen challenge. Seven allergic rhinitis patients and five normal volunteers were infected with rhinovirus type 16 (RV16) and evaluated by segmental bronchoprovocation and bronchoalveolar lavage. Segmental challenge with saline and antigen was performed 1 mo before infection, during the acute infection, and 1 mo after infection. Lavage was performed immediately and 48 h after antigen challenge. Data were analyzed by two-way analysis of variance, and a P value of < or = 0.05 was considered to be significant. All volunteers inoculated with RV16 developed an acute respiratory infection. BAL fluid obtained from allergic rhinitis subjects during the acute viral infection, and 1 mo after infection, showed the following significant RV16-associated changes after antigen challenge: (a) an enhanced release of histamine immediately after local antigen challenge; (b) persistent histamine leak 48 h afterwards; and (c) a greater recruitment of eosinophils to the airway 48 h after challenge. These changes were not seen in non-allergic volunteers infected with RV16 and challenged with antigen, nor in allergic volunteers repetitively challenged with antigen but not infected with RV16, nor in RV16 infected allergic volunteers sham challenged with saline. We conclude that rhinovirus upper respiratory infection significantly augments immediate and late allergic responses in the airways of allergic individuals after local antigen challenge. These data suggest that one mechanism of increased asthma during a cold is an accentuation of allergic responses in the airway which may then contribute to bronchial inflammation.

Enhanced production of oxygen radicals in asthma

Oxygen radicals have been implicated in a variety of disease processes including asthma. In this study we investigated the production of superoxide by airspace cells in 56 patients with asthma as compared with 49 normal controls. We found that with patients with asthma with a forced expiratory vital capacity in the 1st second (FEV1) of less than 80% (n = 13) had higher spontaneous superoxide (SO) production when compared with normal subjects (3.6 +/- 1.0 versus 1.9 +/- 0.2 nmol/5 x 10(5) cells/hour, p < 0.01), whereas those with FEV1 > 80% (n = 40) were similar to normal subjects in superoxide generation (2.1 +/- 0.3 nmol/5 x 10(5) cells/hour). Airspace cells from patients with mild asthma and those with moderate asthma had higher phorbol myristate acetate (PMA)-stimulated SO production when compared with those from normal subjects (8.9 +/- 0.7, 11.1 +/- 2.4, and 6.5 +/- 0.4 nmol/5 x 10(5) cells/hour respectively, p < 0.005, r = -0.35, both comparisons). However, PMA-stimulated SO production was similar in both asthmatic subgroups. Finally, spontaneous generation of SO inversely correlated with FEV1% prediction (r = 0.35, p < 0.01) in the asthma group. We conclude that worsening of airway obstruction in asthma is associated with increased spontaneous generation of SO by airspace leukocytes.

Increased airway inflammation with segmental versus aerosol antigen challenge

Airway inflammation is increasingly recognized as a pivotal component of asthma. Because allergens provoke bronchial constriction and inflammation in allergic subjects, bronchial antigen challenge has emerged as a powerful technique for evaluating mechanisms involved in this process. In this study, we compare whole lung antigen challenge (WLAC) with segmental bronchoprovocation (SBP) in eight allergic, non-asthmatic, non-smoking subjects, and evaluated the response by bronchoalveolar lavage (BAL) prior to, and 48 h after antigen challenge. Both challenge techniques evoked airway inflammation, manifest as an increase in total cells and eosinophils recovered by BAL, an increase in total protein concentration, and enhanced production of superoxide anion by airspace cells. The degree to which these changes occurred was significantly greater with SBP than WLAC, and only SBP evoked persistent measurable change in alveolar macrophage density and eosinophil granule protein concentrations. Moreover, although both techniques were associated with a comparable immediate fall in FEV1, only WLAC resulted in statistically significant persistent physiologic changes 48 h afterwards. We conclude that, as anticipated, SBP produces more intense airway inflammation in allergic subjects, does not result in late airway obstruction, and offers specific advantages in studying allergen-driven airway inflammation.

Increased protein kinase C activity in low density eosinophils

Eosinophil heterogeneity is expressed in cell density, membrane receptors and function. It has been observed that increases in some functional activities correlate with decreased sedimentation density in human eosinophils. However, the cellular mechanisms to explain the up-regulation of eosinophil function have not been fully explored. Protein kinase C (PKC) is an important family of enzymes mediating signal transduction for a wide variety of functions in many different cell types. Changes in the activity of PKC could explain some of the observed differences in function. In these experiments, PKC activity of human granulocyte lysate supernatants was measured as the phosphatidyl serine-dependent transfer of 32P from [gamma-32P]ATP to a protein substrate under conditions of maximal stimulation; a measure of activatable PKC concentration. We observed that the activity present in eosinophils (87.2 +/- 8.4 pmol PO4 incorporated into histone per minute per 10(6) cells, n = 30) was not significantly different from that of neutrophils assayed under the same conditions (91.5 +/- 5.6 U, n = 31) but the percent of total activity that was phosphatidyl serine dependent was greater in eosinophils (97 +/- 1% vs 81 +/- 1% for neutrophils, p = 0.001). Blood eosinophils isolated from low density Percoll fractions had a higher activity (120 +/- 16 U) than that found in the higher density cells from the same subjects (81 +/- 19 U, n = 9, p = 0.011). When eosinophils recovered from bronchoalveolar lavage (BAL) fluid after segmental Ag challenges were assayed, the PKC activity of BAL eosinophils was similar to that of blood-derived eosinophils of equal density and low density BAL eosinophil PKC tended to be equal to or greater than higher density cells. The beta isozyme of PKC but not the alpha or gamma was detected in eosinophils by Western blotting with isozyme-specific mAb. These data indicate that eosinophil PKC activity is primarily caused by the beta-isozyme, is related to cell density in blood-derived cells, and may have a relationship to cell function.

Increased protein kinase C activity in low density eosinophils

Eosinophil heterogeneity is expressed in cell density, membrane receptors and function. It has been observed that increases in some functional activities correlate with decreased sedimentation density in human eosinophils. However, the cellular mechanisms to explain the up-regulation of eosinophil function have not been fully explored. Protein kinase C (PKC) is an important family of enzymes mediating signal transduction for a wide variety of functions in many different cell types. Changes in the activity of PKC could explain some of the observed differences in function. In these experiments, PKC activity of human granulocyte lysate supernatants was measured as the phosphatidyl serine-dependent transfer of 32P from [gamma-32P]ATP to a protein substrate under conditions of maximal stimulation; a measure of activatable PKC concentration. We observed that the activity present in eosinophils (87.2 +/- 8.4 pmol PO4 incorporated into histone per minute per 10(6) cells, n = 30) was not significantly different from that of neutrophils assayed under the same conditions (91.5 +/- 5.6 U, n = 31) but the percent of total activity that was phosphatidyl serine dependent was greater in eosinophils (97 +/- 1% vs 81 +/- 1% for neutrophils, p = 0.001). Blood eosinophils isolated from low density Percoll fractions had a higher activity (120 +/- 16 U) than that found in the higher density cells from the same subjects (81 +/- 19 U, n = 9, p = 0.011). When eosinophils recovered from bronchoalveolar lavage (BAL) fluid after segmental Ag challenges were assayed, the PKC activity of BAL eosinophils was similar to that of blood-derived eosinophils of equal density and low density BAL eosinophil PKC tended to be equal to or greater than higher density cells. The beta isozyme of PKC but not the alpha or gamma was detected in eosinophils by Western blotting with isozyme-specific mAb. These data indicate that eosinophil PKC activity is primarily caused by the beta-isozyme, is related to cell density in blood-derived cells, and may have a relationship to cell function.

IL-5 is the predominant eosinophil-active cytokine in the antigen-induced pulmonary late-phase reaction

The mechanism of airway eosinophilia during antigen-induced inflammation was investigated by measurement of eosinophil-active cytokines utilizing an eosinophil survival assay. In the first study, 4 patients with allergic rhinitis underwent segmental bronchoprovocation (SBP) with low, medium, and high doses of ragweed extract instilled into different bronchial subsegments; bronchoalveolar lavage (BAL) fluids were collected from each segment 12 min and 48 h after challenge. Eosinophil granule proteins and eosinophil survival activity were significantly elevated in the 48-h (late-phase) BAL fluids from these segments. Correlations were observed between the concentrations of eosinophil granule proteins and eosinophil survival activity (rs = 0.717 to 0.880, p < 0.001) in BAL fluids. Eosinophil survival activity was completely neutralized by anti-IL-5 monoclonal antibody in five of the seven 48-h samples tested representing three of the 4 patients. In the two remaining samples, eosinophil survival activity was only partially neutralized by either anti-IL-5 antibody or anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) but was completely neutralized by anti-IL-5 and anti-GM-CSF in combination. Subsequently, in the second study, 10 patients with allergic rhinitis were challenged by SBP with ragweed extract. Eosinophil survival activity was significantly elevated in the 48-h BAL fluids; this activity was partially neutralized by anti-IL-5 antibody about (48%) and completely neutralized by the combination of anti-IL-5 and anti-GM-CSF antibodies. These findings suggest that the eosinophil survival activity in the late inflammatory lesions following SBP with allergen is mainly associated with IL-5, with small contributions from GM-CSF.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of airway and blood eosinophil function after in vivo antigen challenge

Eosinophils (EOS) are important effector cells in allergic diseases and asthma. However, functional characteristics of the EOS have been derived primarily from studies of blood cells, and it is unlikely that such assessments reflect events occurring in tissues or airways. To establish more precisely the function of airway EOS, segmental Ag challenge was used to elicit and isolate large numbers of these cells. Airway, as well as blood, EOS were isolated from allergic patients 48 h after segmental Ag challenge. Both blood and bronchoalveolar lavage (BAL) EOS were fractionated over Percoll density gradients; by using this protocol, three density-distinct populations of pure (>90%) EOS were obtained from BAL fluid (1.100, 1.095, and 1.090 g/ml) and one from blood (1.100 g/ml). The functions of these various populations were compared by measuring superoxide generation, adherence to collagen and endothelial cell monolayers, cell surface receptors, and in vitro survival. BAL EOS of all three densities had greater superoxide generation and adherence with FMLP activation than did corresponding blood EOS. In contrast, blood and airway EOS responded similarly to PMA. BAL EOS also had increased expression of CD11b/CD18 and HLA-DR. The intracellular calcium concentration ([Ca2+]i) was measured with the fluorescent marker indo-1/acetoxymethyl ester. FMLP caused a greater and more sustained increase in [Ca2+]i with BAL than blood EOS. EGTA blocked the sustained component of the [Ca2+]i response to FMLP. Our findings indicate that BAL EOS have an enhanced [Ca2+]i response to activation that may contribute to their functional up-regulation.

Comparison of airway and blood eosinophil function after in vivo antigen challenge

Eosinophils (EOS) are important effector cells in allergic diseases and asthma. However, functional characteristics of the EOS have been derived primarily from studies of blood cells, and it is unlikely that such assessments reflect events occurring in tissues or airways. To establish more precisely the function of airway EOS, segmental Ag challenge was used to elicit and isolate large numbers of these cells. Airway, as well as blood, EOS were isolated from allergic patients 48 h after segmental Ag challenge. Both blood and bronchoalveolar lavage (BAL) EOS were fractionated over Percoll density gradients; by using this protocol, three density-distinct populations of pure (&gt;90%) EOS were obtained from BAL fluid (1.100, 1.095, and 1.090 g/ml) and one from blood (1.100 g/ml). The functions of these various populations were compared by measuring superoxide generation, adherence to collagen and endothelial cell monolayers, cell surface receptors, and in vitro survival. BAL EOS of all three densities had greater superoxide generation and adherence with FMLP activation than did corresponding blood EOS. In contrast, blood and airway EOS responded similarly to PMA. BAL EOS also had increased expression of CD11b/CD18 and HLA-DR. The intracellular calcium concentration ([Ca2+]i) was measured with the fluorescent marker indo-1/acetoxymethyl ester. FMLP caused a greater and more sustained increase in [Ca2+]i with BAL than blood EOS. EGTA blocked the sustained component of the [Ca2+]i response to FMLP. Our findings indicate that BAL EOS have an enhanced [Ca2+]i response to activation that may contribute to their functional up-regulation.

Enhanced production of oxygen radicals in nocturnal asthma

Although the mechanisms of nocturnal worsening of pulmonary function in asthmatics have not been entirely established, airway inflammation is felt to be a major factor in disease severity. Consequently, to determine whether changes in bronchoalveolar lavage (BAL) fluid cellular components and their functions are related to nocturnal airway obstruction, we performed BAL at 4:00 A.M. and at 4:00 P.M. in asthma subjects with (n = 5) and without (n = 10) nocturnal asthma. No significant changes were observed from 4:00 P.M. to 4:00 A.M. in the concentration of total cells or the percentage or concentration of eosinophils or neutrophils in BAL fluid from subjects with or without nocturnal asthma. However, superoxide anion generation by air-space cells from subjects with nocturnal asthma was significantly greater at 4:00 A.M. than at 4:00 P.M. (6.9 +/- 1.7 versus 1.8 +/- 0.5 nmol/500K cells/h, p less than 0.05). Moreover, superoxide production at 4:00 A.M. was greater in subjects with than in those without nocturnal asthma (6.9 +/- 1.7 versus 2.2 +/- 0.6, p less than 0.02). Furthermore, in our group of asthmatics, the change in generation of superoxide anion from 4:00 P.M. to 4:00 A.M. was significantly correlated with the change in FEV1 (r = -0.71, p less than 0.01). We conclude that the development of nocturnal airway obstruction in asthma is associated with enhanced production of oxygen radicals by air-space cells. Because oxygen radicals can cause airway injury and thus enhance bronchial obstruction, it is possible that the release of these reactive compounds is causally associated with nocturnal asthma.

Characteristics of peripheral blood eosinophils in patients with nocturnal asthma

A number of mechanisms have been proposed to explain nocturnal exacerbations of asthma including circadian patterns in circulating cortisol and catecholamines. These factors may influence airway smooth muscle tone and circulating eosinophil characteristics and function. Because recent evidence has indicated that eosinophils contribute to airway inflammation and the severity of asthma, we evaluated the relationship among peripheral blood eosinophils, their density distribution, and the appearance of nocturnal asthma. Fifteen patients with asthma were evaluated. Spirometry (FEV1 and FVC) was determined at 0400 and 1600, and the number and density distribution of peripheral blood eosinophils were determined. Five patients had nocturnal asthma, defined as a 15% or greater fall in FEV1 at 0400 versus 1600. The patients with nocturnal asthma had greater numbers of eosinophils (cells x 10(6)/ml) at 0400 (0.845 +/- 0.13 versus 0.351 +/- 0.03) and 1600 (0.651 +/- 0.18 versus 0.319 +/- 0.07) and a greater circadian variation with peak eosinophilia at 0400. Furthermore, we found a significant circadian increase in low-density eosinophils (as determined by Percoll density gradient centrifugation) at 0400, but only in patients with nocturnal asthma. These observations suggest that a circadian variation in low density eosinophils may contribute to nocturnal exacerbations of asthma.

Enhanced superoxide production by alveolar macrophages and air-space cells, airway inflammation, and alveolar macrophage density changes after segmental antigen bronchoprovocation in allergic subjects

Airway inflammation is a principal determinant of airway responsiveness and function in asthma and allergic diseases. Alveolar macrophages (AM) may contribute to inflammation in multiple ways, including release of reactive oxygen species such as superoxide (SO) anion. We hypothesized that SO production by AM increases after segmental bronchoprovocation (SBP) with relevant antigen and contributes to airway injury. Eight ragweed-sensitive subjects with allergic rhinitis were studied by bronchoalveolar lavage and ragweed SBP to determine the SO production and characteristics of cells recruited after antigen challenge. No significant changes in cell numbers or total protein concentration were observed immediately after antigen challenge. Purification (to greater than 94%) of AM on discontinuous gradients of Percoll revealed significantly increased spontaneous and opsonized-zymosan-driven SO production immediately after antigen challenge. Forty-eight hours later, total air-space cells, AM, eosinophils, and total protein concentration were significantly increased in relationship to antigen dose given. Furthermore, both unfractionated air-space cells and purified AM obtained 48 h after antigen challenge released increased amounts of SO anion in response to activator compared with either cells obtained immediately after SBP or those obtained 48 h after saline challenge. In addition, significant increases in high density AM were also seen 48 h after antigen challenge. These data suggest that AM activation occurs immediately after antigen challenge, and that the late airway response to antigen is characterized by the appearance of high density AM, which have potentiated SO release. The increased oxidative burden thereby produced may contribute to increased airway injury.

Exercise-induced asthma is not associated with mast cell activation or airway inflammation

Exercise-induced asthma (EIA) may affect up to 90% of patients with asthma. Hyperpnea associated with exercise leads to increased airway water and heat loss, which contributes to the development of EIA. Measurement of circulating mediators has suggested that mast cells may participate in the development of EIA via release of histamine and neutrophil chemotactic factor. To evaluate further the contribution of pulmonary mast cell-mediator release in the pathogenesis of EIA and to determine whether EIA is associated with enhancement of airway inflammation, we studied 11 subjects with mild stable asthma (FEV1, 93% +/- 3% predicted; mean +/- SEM) with significant EIA (after exercise fall in FEV1, 41% +/- 5%). Bronchoalveolar lavage (BAL) was performed immediately (less than 1 hour) after exercise challenge (EC) and repeated 24 hours later (exercise studies). On another occasion, paired BALs were done 24 hours apart (control studies). A minimum of 2 weeks separated the exercise and control pairs. No changes were observed in BAL cell counts, differentials, or reactive oxygen species metabolism after EC. Neither BAL histamine nor BAL tryptase levels increased, either shortly (less than 1 hour) or 24 hours after EC. We conclude that EC in subjects with asthma is not associated with cellular influx to airspace and that mechanisms other than histamine release by pulmonary mast cells may be responsible for EIA.

Experimental rhinovirus 16 infection potentiates histamine release after antigen bronchoprovocation in allergic subjects

Viral respiratory infections exacerbate asthma in many patients. We hypothesized that one mechanism by which this effect occurs may include potentiated or altered mediator release by mast cells and/or basophils to favor the development of late-phase asthmatic reaction (LAR). Therefore, we studied eight subjects with allergic rhinitis before and during an experimentally induced rhinovirus 16 (RV16) infection. We determined levels of plasma histamine and tryptase, and we observed the associated patterns of airway obstruction that developed following inhaled antigen challenge. Bronchial responsiveness to histamine, methacholine, and antigen were all significantly increased during the RV16 illness. Further, the incidence of LAR was significantly higher (five of eight) during the infection than before (one of eight; p = 0.014). In addition, in those patients whose pattern of response following antigen challenge converted from an immediate response only before infection to a dual response (immediate + late phase) during infection, plasma histamine concentrations after challenge were significantly greater than in those whose pattern of response did not change. We conclude that one mechanism by which RV16 infection increases the likelihood of LAR could include enhanced mediator release from pulmonary mast cells or from circulating or recruited basophils.

Immediate and late airway response of allergic rhinitis patients to segmental antigen challenge. Characterization of eosinophil and mast cell mediators

Segmental antigen bronchoprovocation was used to define the nature of the inflammatory process in allergic airway disease. Bronchoalveolar lavage fluid obtained from allergic rhinitis patients 12 min after segmental antigen instillation (immediate response) revealed a significant increase in histamine and tryptase, but no cellular response. Repeat segmental lavage 48 h later (late response) showed marked and significant increases in both low and normal density eosinophils as well as striking elevations of eosinophil granular protein levels (major basic protein, eosinophil-derived neurotoxin, eosinophil cationic protein, and eosinophil peroxidase). Leukotriene C4, but not tryptase, concentrations were also consistently elevated in late lavage samples. Further, the late lavage samples showed a significant increase in interleukin-5 concentrations that correlated with the presence of eosinophils and eosinophil granular proteins. Neither eosinophils nor soluble mediators of eosinophils increased when normal subjects were similarly challenged with antigen. These data suggest that eosinophils are attracted to the airway during the late-phase allergic reaction and that IL-5 may produce changes in airway eosinophil density and promote the release of granular proteins to cause airway injury.

Human neutrophil elastase and elastase/alpha 1-antiprotease complex in cystic fibrosis. Comparison with interstitial lung disease and evaluation of the effect of intravenously administered antibiotic therapy

In cystic fibrosis (CF), extracellular lung matrix is progressively damaged, neutrophils invade the air spaces, and activated neutrophils may release large amounts of neutrophil elastase (NE). Although alpha 1-antiprotease (alpha 1-AP) binds and inactivates NE and is the major antielastase of the lower respiratory tract, antielastase defenses may be overwhelmed in CF, leading to progressive lung damage. To determine whether the ability of alpha 1-AP to neutralize NE is impaired in CF, we compared NE activity in bronchoalveolar lavage (BAL) fluid and human neutrophil elastase/alpha 1-antiprotease (NE/alpha 1-AP) complex in both BAL fluid and peripheral blood serum from patients with CF, normal volunteers, and patients with interstitial lung disease. We detected a considerable amount of NE activity in BAL fluid from all but one patient with CF but none in that from normal volunteers or from patients with interstitial lung disease. Although in interstitial lung disease there was a significant correlation between increased NE/alpha 1-AP complex in BAL or peripheral blood and the degree of neutrophil influx, NE/alpha 1-AP complex was disproportionately low in CF BAL compared with significantly elevated values in serum. These data suggest that in CF, alpha 1-AP-mediated defense against free NE in the lower respiratory tract is significantly impaired, and high levels of uncomplexed, enzymatically active, NE are present in CF respiratory secretions. To determine whether intravenously administered antipseudomonal antibiotic therapy for exacerbations of CF lung disease diminished the amount of free NE in respiratory secretions, we used BAL to investigate the effect of such therapy on neutrophils and NE in patients with CF colonized with pseudomonads.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of eosinophils in the pathophysiology of asthma

From current information, a number of conclusions can be drawn. Antigen activation of the allergic reaction in the airways is associated with an immediate rise in mast cell derived mediators, including histamine and tryptase. Associated with antigen activation of the allergic reaction is recruitment of eosinophils to the airways. This can best be seen in the airway lavage 48 hours after challenge with antigen. An increased presence of eosinophils suggests that they are an important contributor to the late allergic reaction and may be one of the major constituents in the development of bronchial inflammation. Although many factors participate in the late allergic inflammatory response, eosinophil-derived proteins are known to cause airway injury. Regulation of eosinophils in this process is not clearly established; however, our findings of increased IL-5 in relationship to the presence of eosinophils and their granular proteins suggests that this cytokine may be an important modulator of eosinophil function and activation following allergen challenge. However, much remains unknown in understanding bronchial inflammation and the eosinophil's role in the process. In conclusion, the eosinophil is a major cellular participant in late phase allergic airway disease. Its presence and known functions suggest that the eosinophil is a significant cellular factor in the development of allergic airways disease in asthma. Further advances in this area will follow continued studies, particularly those which involve biopsy and correlation with airway physiology.

Elevated bronchoalveolar lavage fluid histamine levels in allergic asthmatics are associated with increased airway obstruction

Bronchoalveolar lavage (BAL) fluid was evaluated for histamine and tryptase levels in 61 samples (46 samples from 24 atopic asthmatics, seven samples from seven patients with allergic rhinitis, and eight samples from eight normal volunteers). Asthmatics and patients with allergic rhinitis had significantly higher BAL histamine than did normal subjects (169 +/- 22, 141 +/- 23, 42 +/- 6 pg/ml, respectively; p less than 0.05, both comparisons). BAL fluid tryptase levels were also higher in asthmatics and patients with allergic rhinitis than in normal subjects (0.36 +/- 0.03, 0.38 +/- 0.05, 0.23 +/- 0.04 ng/ml, respectively; p less than 0.05, both comparisons); however, levels of tryptase and histamine in BAL were not correlated (r = -0.03 in the group as a whole, r = -0.12 in the asthmatic group). BAL concentration of histamine correlated inversely with FEV1 percent predicted in the asthmatic group (r = -0.44, p less than 0.005). Asthmatics with high BAL fluid histamine (greater than or equal to 100 pg/ml, n = 23) had lower FEV1 percent predicted (80 +/- 3% versus 96 +/- 3%, p = 0.0005), lower FEV1/FVC ratio (72 +/- 1% versus 77 +/- 2%, p less than 0.05), higher percentage of BAL eosinophils (2.2 +/- 0.4% versus 0.6 +/- 0.1%, p less than 0.002), and greater airway responsiveness (lower PD20 [13.1 +/- 3.4 versus 41.5 +/- 13.7 cumulative breath units, p less than 0.05]) compared with asthmatics with low BAL fluid histamine (less than 100 pg/ml, n = 23).(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced reactive oxygen species metabolism of air space cells in hypersensitivity pneumonitis

Reactive oxygen species (ROS) are produced by phagocytic cells as part of host defense mechanisms, but these same products released by air space cells have been shown to contribute to pulmonary inflammation in interstitial lung diseases and likely represent a general mechanism of lung injury. However, the possible contribution of these compounds to lung inflammation in hypersensitivity pneumonitis (HP) has yet to be reported. We performed 11 bronchoalveolar lavage (BAL) studies in six patients with HP and compared the results with results from studies in 21 healthy normal volunteers. In patients with HP, spontaneous and stimulated measures of ROS metabolism by air space cells were significantly higher than those seen in normal volunteers. When alveolar macrophages were purified by depleting neutrophils and eosinophils on density gradients of Percoll (specific gravity 1.075 gm/ml), ROS metabolism remained elevated when compared with that in cells obtained from healthy controls, confirming that alveolar macrophage ROS metabolism is enhanced in patients with HP. Further, we found significant elevations in BAL total protein, lymphocytes, eosinophils, and neutrophils in patients with HP when they were compared with normal volunteers, with an increased proportion of BAL T lymphocytes expressing CD8 and natural killer surface antigens, consistent with previous work. Lavage samples from patients with HP with clinically active disease had higher proportions of BAL eosinophils and concentrations of total protein, lower forced expiratory volume in 1 second, lower forced vital capacity, and lower arterial oxygen tensions, and higher indices of ROS metabolism than samples from patients with HP with inactive disease. HP is associated with evidence of air space inflammation, to which alveolar macrophage-derived ROS may contribute.

Modulation of superoxide production of alveolar macrophages and peripheral blood mononuclear cells by beta-agonists and theophylline

Reactive oxygen species, including superoxide anion, have attracted increasing attention for their possible role in promoting inflammation in a variety of pulmonary diseases including asthma. However, reactive oxygen species metabolism of phagocytic cells may be substantially modified by therapeutic agents used for asthma. Peripheral blood mononuclear cells and alveolar macrophages from 15 normal subjects, and blood mononuclear cells from an additional 17 normal subjects, were studied to assess the effects of beta-receptor agonists and theophylline on phagocytic cell superoxide release. Isoproterenol produced a biphasic effect on spontaneous and phorbol ester stimulated alveolar macrophage and mononuclear cell superoxide production, augmenting release at 10(-5)M, and inhibiting release at 10(-4)M. These effects on spontaneous function in mononuclear cells were inhibited by 10(-5)M propranolol. Under conditions of phorbol ester-stimulation the enhancing effect of 10(-5)M isoproterenol on blood mononuclear cells was blocked by propranolol, but the inhibitory effect of 10(-4)M isoproterenol was not. Albuterol at equimolar concentrations with isoproterenol was not associated with altered spontaneous or stimulated superoxide release by alveolar macrophages or mononuclear cells. Further, spontaneous superoxide release by alveolar macrophages and mononuclear cells was significantly reduced by therapeutically achievable concentrations of theophylline (greater than 5 micrograms/ml). We conclude that the medication history must be controlled in studies of cell function in asthma, and that albuterol may be preferable to isoproterenol as a premedication for bronchoscopy when superoxide production of airspace cells is studied.

Enhanced reactive oxygen species metabolism of airspace cells and airway inflammation follow antigen challenge in human asthma

Airflow limitation and airway inflammation follow antigen bronchoprovocation in sensitized individuals. Inflammation likely results from the interplay of several previously demonstrated factors, but the participation and persistence of enhanced reactive oxygen species (ROS) metabolism of airspace cells after antigen challenge have received more limited attention. We studied nine subjects with mild asthma by bronchoalveolar lavage before and 48 (one subject) to 72 (eight subjects) hours after antigen bronchoprovocation and compared airspace cell numbers and types, cell function, and bronchoalveolar lavage fluid protein, albumin, and immunoglobulins. Mild, but significant, airflow limitation persisted at the time of the second lavage. Eosinophil influx was a notable component of the increased airspace cells in postchallenge lavages. Airspace cells demonstrated significantly enhanced ROS metabolism, and total protein, albumin, and IgM levels were higher in postchallenge lavage specimens. Antigen bronchial challenge produces airspace inflammation, which may develop, in part, as a consequence of enhanced ROS metabolism of airspace cells.

Bronchoalveolar lavage in stable asthmatics does not cause pulmonary inflammation

Bronchoalveolar lavage (BAL) has become an important tool for evaluating changes in airway cells and fluid in asthma, and it may give insights into mechanisms of bronchial inflammation. Many factors contribute to airway inflammation in asthma including, possibly, airway instrumentation. To establish whether BAL leads to diffuse airway inflammation in stable asthmatics, we performed paired BAL studies (24 h apart) in eight subjects with mild asthma whose prebronchoscopy spirometric results were similar on both days. Airflow limitation did not occur in any subject after bronchoscopy. We observed no significant changes in BAL volume return, cell differential, lymphocyte subsets, reactive oxygen species metabolism by air-space cells, or BAL total protein. There was a slight increase in second-day BAL total cell return. We conclude that bronchoscopy and BAL in stable asthmatics with mild disease is not associated with evidence of diffuse airway inflammation.

Modulation of human peripheral blood monocyte superoxide release by interferon-gamma and lipopolysaccharide

Reactive oxygen species (ROS) have generated increasing interest for their possible role in a wide variety of diseases. Interferon-gamma (IFN-gamma), a potent immunoregulatory lymphokine, is likely involved in control of ROS metabolism. In this study, the superoxide release of cultured human peripheral blood monocytes (PBM) after exposure to IFN-gamma and lipopolysaccharide (LPS) was examined. Compared with controls, adherent monocytes cultured with 80 units of IFN-gamma for 48 hours demonstrated fourfold increased spontaneous and twofold increased PMA stimulated release of superoxide anion. In addition, the enhanced superoxide release was both dose and time dependent. Further experiments showed that bacterial LPS in concentrations as low as 4 ng/mL markedly reduced monocyte superoxide release and abrogated the enhancing effects of IFN-gamma.

Heterogeneity in cell recovery and superoxide production in buoyant, density-defined subpopulations of human alveolar macrophages from healthy volunteers and sarcoidosis patients

Reactive oxygen species (ROS) are ubiquitous compounds produced by phagocytes with important roles in both host defense and pulmonary inflammation. Enhanced ROS metabolism by alveolar macrophages (AM) has been previously demonstrated in various interstitial lung diseases including sarcoidosis. We studied 17 healthy, nonsmoking volunteers and 10 patients with sarcoidosis by bronchoalveolar lavage, and separated AM on discontinuous Percoll gradients to determine patterns of airspace cell recovery and the corresponding ROS metabolism of density-defined AM subpopulations. AM subpopulations were largely purified from contaminating granulocytes, thereby allowing more accurate estimation of ROS metabolism by AM. In bronchoalveolar lavage material from sarcoidosis patients, increased recovery of cells of high (1.075 gm/ml) density was found, which contrasted with the pattern seen in the volunteers in whom cells of lowest density (1.045 gm/ml) predominated. In addition, dense cells from sarcoidosis patients exhibited enhanced stimulated ROS metabolism compared with cells of similar density obtained from the volunteers or with sarcoid cells of lower density. At least three mechanisms may contribute to increased lung oxidative burden in sarcoidosis. The combination of increased bronchoalveolar lavage cell counts, increased cell recovery at high density, and increased cell function produced substantial increases in the total oxidative burden imposed on the lungs of sarcoidosis patients by airspace cells. We conclude that AM metabolism of ROS is dependent on the density and, by implication, the maturity of the cells and that regulation of AM ROS metabolism differs markedly between sarcoidosis patients and healthy volunteers.