The Many Faces of Airway Inflammation

Utilization of health care services by patients with chronic obstructive pulmonary disease

In order to identify healthcare resource use patterns associated with chronic obstructive pulmonary disease (COPD), resource utilization (RU) data collection was integrated into a randomized, double-blind placebo-controlled study of Viozan (sibenadet HCl). This study enrolled patients with symptomatic, smoking-related COPD, randomized to receive sibenadet or placebo for a 52-week treatment period. A questionnaire establishing typical pre-trial, COPD-related RU was completed by each patient. Subsequent data were collected by means of an Interactive Voice Response System (IVRS) at 30-day intervals (14 time points) during the study and in the follow-up period. The IVRS system facilitated data collection and minimized inconvenience to the patient. Compliance with the requirement to record details of the healthcare services during the year-long study was high. No overall trend for lower RU was associated with sibenadet therapy, which correlates with the lack of sustained clinical effect seen in studies conducted concurrently. These data do, however, provide valuable information on RU associated with COPD and insights into adjustments associated with changes in disease course. Physicians were seen to be the most common source of care for patients with COPD and more of the patients with severe COPD (stage III) than mild (stage I) were seen to utilize the most expensive resources (e.g. inpatient hospital care). For those patients who experienced an exacerbation during the trial (irrespective of treatment group), resource use was increased during the periods when an exacerbation was reported when compared with the periods before or after an exacerbation. The proportion of cases attending the physician doubled and with a trip to the Emergency Room (ER) increased approximately ninefold during the reporting period in which the exacerbation occurred compared with the previous month. This study has shown that use of an IVRS, even in elderly patients, is an effective means of gathering RU data over long periods. The study findings suggest that the advent of effective therapeutic interventions, particularly any with the ability to minimize exacerbations and limit disease progression, could impact on the health care services used and potentially reduce associated costs.

Osmotic stimuli increase clearance of mucus in patients with mucociliary dysfunction

Mucociliary dysfunction results in mucus accumulation, airway obstruction, bacterial colonization, recurrent infective exacerbations, and an increase in morbidity and mortality. Studies in patients with cystic fibrosis, established that inhalation of hypertonic saline (HS) increases clearance of mucus acutely in a dose-dependent manner. Clearance over 90 min was 23.8 +/- 4.0% and 26.0 +/- 3.1% in response to 7% and 12% saline, which was significantly enhanced compared to 12.7 +/- 1.4% and 19.7 +/- 3.1% in response to 0.9% and 3% saline. Mannitol (approximately 300 mg) inhaled as a dry powder had a marked acute effect in patients with bronchiectasis. Clearance over 75 min was 34.0 +/- 5.0% with mannitol, 17.4 +/- 3.8% with control, and 11.7 +/- 4.4% at baseline. Further studies in patients with bronchiectasis showed that mannitol reduces the 24-h retention of radiolabeled mucus, suggesting that the effect of mannitol extends beyond the acute phase. Mannitol helped patients to clear mucus within 2 h that would have taken 24 h to clear without mannitol. A further study in CF patients showed that mannitol was equally effective as 6% HS at improving ciliary and cough clearance. The total clearance over 120 min with mannitol (27.6 +/- 3.7%) and with HS (31.0 +/- 5.5%) was significantly increased compared to their respective controls (18.6 +/- 3.8% and 20.9 +/- 3.6%). These preliminary results suggest that long-term treatment with HS or mannitol may benefit patients with mucociliary dysfunction.

Chronic obstructive pulmonary disease is associated with the -1055 IL-13 promoter polymorphism

IL-13 is strongly implicated in the development of asthma and chronic obstructive pulmonary disease (COPD). We previously identified an IL-13 promoter polymorphism (-1055 C to T) that is associated with allergic asthma. We now report an increased frequency of the -1055 T allele in COPD patients compared to healthy controls (P=0.002) and compared to a second control group consisting of smoking individuals with normal lung function (P=0.01). A closely linked IL-13 exon polymorphism is present at normal allelic frequencies (P=0.3 and 0.4, respectively). In addition, we observed a normal distribution of two IL-4 polymorphisms at positions -590 and +33 (P=0.2 and 0.9, respectively). These results could implicate a functional role for the IL-13 promoter polymorphism in the enhanced risk to develop COPD.

The association of sensitive systemic inflammation markers with bronchial asthma

BACKGROUND

Airway inflammation is a characteristic feature of bronchial asthma. Previous studies have shown an increased local inflammatory activity in the airway mucosa of asthma patients.

OBJECTIVES

To analyze the association of asthma with three sensitive markers of systemic inflammation, C-reactive protein, serum amyloid-A (SAA), and plasma fibrinogen.

METHODS

A cross-sectional, population-based study including 1,513 Finnish men aged 45 to 74 years, who participated in a chronic disease risk factor survey in 1997. Of the participating men, 97 were classified as asthma patients. The odds ratios of asthma were analyzed by quartile of each inflammation marker.

RESULTS

In logistic regression models the age-adjusted odds ratios (second, third, and fourth quartile as compared with the first quartile) of asthma increased gradually with increasing quartile of C-reactive protein (1.28, 1.19, 1.96, P for trend = 0.039), SAA (1.20, 3.00, 3.49, P for trend < 0.001), and fibrinogen (1.22, 1.79, 3.16, P for trend < 0.001). The associations were independent of smoking. Further adjustment for waist-to-hip ratio, a marker of central obesity, and symptoms of chronic bronchitis weakened the observed association, but the increasing trend in the association of SAA and fibrinogen with asthma remained highly significant.

CONCLUSIONS

Sensitive markers of systemic inflammation, particularly SAA and fibrinogen, were positively and significantly associated with asthma prevalence. These findings support the hypothesis that not only local, but also systemic, inflammation exist in bronchial asthma.

Respiratory and limb muscle weakness induced by tumor necrosis factor-alpha: involvement of muscle myofilaments

The respiratory and limb skeletal muscles become weakened in sepsis, congestive heart failure, and other inflammatory diseases. A potential mediator of muscle weakness is tumor necrosis factor (TNF)-alpha, a cytokine that can stimulate muscle wasting and also can induce contractile dysfunction without overt catabolism. This study addressed the latter process. Murine diaphragm and limb muscle (flexor digitorum brevis [FDB]) preparations were used to determine the relative sensitivities of these muscles to TNF-alpha. Intact muscle fibers were isolated from FDB and microinjected with indo-1 to measure changes in sarcoplasmic calcium regulation. We found that TNF-alpha depressed tetanic force of the diaphragm and FDB to comparable degrees across a range of stimulus frequencies. In isolated muscle fibers, TNF-alpha decreased tetanic force without altering tetanic calcium transients or resting calcium levels. We conclude that (1) TNF-alpha compromises contractile function of diaphragm and limb muscle similarly, and (2) TNF-alpha decreases force by blunting the response of muscle myofilaments to calcium activation.

Prevalence of self-reported respiratory symptoms in rural areas of Iran in 2000

OBJECTIVES

The aims of the present study were to measure the population prevalence of symptoms of asthma, chronic bronchitis, obstructive lung disease and non-specific respiratory symptoms in randomly selected rural communities in south-west Isfahan, Iran.

METHODOLOGY

Nine hundred and ninety-four subjects from a total of 1127 villagers (88.2% response rate) took part in a medical interview conducted by interns from the Isfahan Medical School.

RESULTS

The mean (+/-SD) age of the population surveyed was 25.21 +/- 17.55 years and the smoking rate was 7.2%. The self-reported prevalence rates for current asthma, chronic bronchitis, non-specific exercise-induced cough and night cough were 6.1, 4.4, 13.3 and 11.3%, respectively.

CONCLUSION

Asthma, chronic bronchitis and other respiratory disorders in rural Isfahan are more prevalent than expected for a young rural population with low smoking rates. The cause of this should be investigated.

Beclomethasone, budesonide and fluticasone propionate inhibit human neutrophil apoptosis

Inhaled glucocorticoids are widely used to treat chronic obstructive pulmonary disease without much evidence of efficiency in this disease where neutrophils may contribute to the pathophysiology. This prompted us to test the effects of several currently used inhaled and systemic glucocorticoids on human neutrophil apoptosis. Beclomethasone, budesonide, dexamethasone, fluticasone propionate, hydrocortisone and prednisolone inhibited apoptosis in a concentration-dependent manner as assessed by flow cytometric analysis, annexin-V binding and morphological analysis. The maximal inhibition of apoptosis was 50-60%. The order of potency was fluticasone propionate (EC(50) 0.6+/-0.2 nM) approximately equal to budesonide (EC(50) 0.8+/-0.2 nM)> dexamethasone approximately equal to prednisolone approximately equal to beclomethasone approximately equal to hydrocortisone. The inhibitory effects of glucocorticoids were reversed by mifepristone. Moreover, glucocorticoids slightly enhanced the inhibitory effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on neutrophil apoptosis. The present data suggests that budesonide and fluticasone propionate prolong human neutrophil survival by inhibiting apoptosis at clinically relevant drug concentrations via an effect on glucocorticoid receptor.

Acute exacerbation of chronic bronchitis: disease-specific issues that influence the cost-effectiveness of antimicrobial therapy

BACKGROUND

Acute exacerbation of chronic bronchitis (AECB) is a common condition, with substantial associated costs and morbidity. Research efforts have focused on innovations that will reduce the morbidity associated with AECB. Health care payers increasingly expect that the results of evidence-based economic evaluations will guide practitioners in their choice of cost-effective interventions.

OBJECTIVES

To provide a framework on which to base effective and efficient antimicrobial therapy for AECB, we present a concise clinical review of AECB, followed by an assessment of the available data on the economic impact of this disease. We then address several AECB-specific issues that must be considered in cost-effectiveness analyses of AECB antimicrobial interventions.

METHODS

Published literature on the clinical and economic impact of AECB was identified using MEDLINE, pre-MEDLINE, HealthSTAR, CINAHL, Current Contents/All Editions, EMBASE, and International Pharmaceutical Abstracts databases. Other potential sources were identified by searching for references in retrieved articles, review articles, consensus statements, and articles written by selected authorities.

RESULTS

In evaluating cost-effectiveness analyses of AECB antimicrobial therapy it is critical to (1) use the disease-free interval as an outcome measure, (2) evaluate the sequence of multiple therapies, (3) address the impact of both current and future antibiotic resistance, and (4) measure all appropriate AECB-associated costs, both direct and indirect.

CONCLUSIONS

Incorporating these approaches in economic analyses of AECB antimicrobial therapy can help health care organizations make evidence-based decisions regarding the cost-effective management of AECB.

Relation between exhaled carbon monoxide levels and clinical severity of asthma

Carbon monoxide (CO) can be detected in exhaled air and is increased in asthmatic patients not treated with corticosteroids. However, it is uncertain whether exhaled CO is related to severity of asthma. To study whether exhaled CO is related to severity of asthma in clinical courses, exhaled CO concentrations were measured on a CO monitor by vital capacity manoeuvre in 20 mild asthmatics treated with inhaled beta2-agonists alone, 20 moderate asthmatics treated with inhaled corticosteroids, and 15 stable asthmatics treated with high dose inhaled corticosteroids and oral corticosteroids once a month over 1 years. Exhaled CO concentrations were also measured in 16 unstable severe asthmatics who visited the hospital every 7 or 14 days for treatment with high dose inhaled corticosteroids and oral corticosteroids. The mean values of exhaled CO in severe asthma over 1 year were 6.7 +/- 9.5 p.p.m. (n = 31, mean +/- SD) and significantly higher than those of non-smoking control subjects (1.2 +/- 0.9 p.p.m., n = 20, P < 0.01). Exhaled CO concentrations in unstable severe asthmatics were significantly higher than those in stable severe asthmatics. However, exhaled CO concentrations in mild and moderate asthmatics did not differ significantly from those in non-smoking control subjects (P > 0.20). There was a significant relationship between the exhaled CO concentrations and forced expiratory volume in one second in all asthmatic patients. These findings suggest that exhaled CO concentrations may relate to the severity of asthma and measurements of exhaled CO concentrations may be a useful means of monitoring airway inflammation in asthma.

N-Acetylcysteine counteracts erythrocyte alterations occurring in chronic obstructive pulmonary disease

A key role has been proposed for reactive oxygen species (ROS) in chronic obstructive pulmonary disease (COPD). Aim of the present work was to evaluate possible implications of ROS in the integrity and function of the cell type mainly involved in oxygen uptake and delivery to the peripheral tissues: the erythrocyte. Red blood cells (RBCs) were thus collected from blood samples from COPD patients. Furthermore, blood samples from the same patients treated with the antioxidizing drug of widespread use in such disease i.e., N-acetylcysteine (NAC), were also considered. Morphometric and analytical cytology studies were then conducted. We report herein that: (i) alterations of RBC ultrastructure were detectable in RBCs from COPD patients, that (ii) relevant changes of spectrin cytoskeleton and glycophorin expression were also found and that (iii) NAC treatment was capable of significantly counteracting these changes. These results are consistent with a reappraisal of the role of RBCs in this disease.

Controlled short-term trial of fluticasone propionate in ventilator-dependent patients with COPD

BACKGROUND

There is no agreement about the efficacy of systemic corticosteroids in patients with COPD, but corticosteroids often are employed during exacerbations of the disease. The use of systemic or inhaled corticosteroids in patients in stable condition is even more controversial, even though the more severely affected patients seem to respond better. Unfortunately, in this subset of patients, the use of forced expiratory maneuvers frequently fails to detect significant functional response.

STUDY OBJECTIVES

We evaluated the short-term effects of an inhaled corticosteroid, fluticasone propionate (FP), on FEV(1) and on the mechanical properties of patients in stable condition with severe COPD and chronic hypercapnic respiratory failure who were receiving long-term ventilatory support. This allowed us to measure respiratory mechanics (RM) passively, thereby avoiding any problems linked with voluntary maneuvers.

DESIGN

Randomized, placebo-controlled, crossover study.

SETTING

A respiratory ICU.

PATIENTS

Twelve hypercapnic COPD patients (mean [+/- SD] PaCO(2), 60+/-11 mm Hg; mean FEV(1), 13+/-5% predicted; and mean FEV(1)/FVC, 31 +/- 7%) were enrolled.

INTERVENTIONS

A daily dose of 2,000 microg FP or placebo was administered via metered-dose inhaler during mechanical ventilation for 5 consecutive days. A washout of 72 h was allowed between regimens.

MEASUREMENTS

End-expiratory and end-inspiratory airway occlusions were performed to assess static intrinsic positive end-expiratory pressure (PEEPi,st), static compliance of the respiratory system (Cst,rs), maximal respiratory resistance (Rmax, rs), and minimal respiratory resistance (Rmin,rs). The bronchodilator response also was assessed by FEV(1) level.

RESULTS

No significant changes were found in RM after administration of the placebo. By day 6, FP had induced the following significant decreases: PEEPi,st, 4.3+/-2.4 to 3.1+/-1.7 cm H(2)O (p<0.01); Rmax,rs, 19.0+/-6.5 to 14.6+/-6 cm H(2)O/L/s (p<0.001); and Rmin,rs, 14.8+/-4.2 to 10.5+/-3.4 cm H(2)O/L/s (p<0.001). The Cst,rs and the effective additional resistance of the respiratory system did not change significantly, the latter suggesting that the major effect of FP was on the airway caliber (Rmin,rs). FEV(1) changes significantly (p<0.01) underestimated the bronchodilator response, as compared with changes in Rmin,rs.

CONCLUSIONS

We conclude that in patients in stable condition with severe COPD and chronic hypercapnic respiratory failure, a brief trial of FP may induce a bronchodilator response, mainly related to a reduction in airway resistances, that is not detected by the usual pulmonary function tests.

NOVEL THERAPEUTIC APPROACHES FOR ALLERGIC RHINITIS

The last 2 decades have witnessed enormous changes in our understanding of allergic rhinitis. As we have begun to unravel the complex underlying immunologic and inflammatory pathophysiology of the disease, new therapeutic strategies as well as specific molecular and cellular constituents have emerged as potential targets for clinical intervention. These efforts also have shed light on the mechanisms by which current antiallergy medications act—or sometimes fail to be effective.7, 31, 51, 89 The similar pathophysiologic basis for allergic rhinitis and the often comorbid condition, asthma, was underscored in the recently published American Thoracic Society Workshop Summary on the Immunobiology of Asthma and Rhinitis: Pathogenic Factors and Therapeutic Options.¹⁸ In his conclusion, workshop chair, Thomas Casale,¹⁸ counsels readers to consider that “…allergic asthma and rhinitis represent a systemic disease affecting two organs, the lung and the nose. Asthma and allergic rhinitis share many of the same pathogenic factors, but they operate in different parts of the airway. Inflammatory cells and mediators are often the same, and there may be common alterations that occur in the immune system.” Thus, therapeutic strategies and potential therapeutic agents found to be beneficial in the treatment of one airway target may show similar effects in the other. For this reason, and because many of the therapies now being developed are at early stages in their evolution, physicians interested in rhinitis therapy also must examine what is known about these agents in asthma.

One avenue of active research has been the role of leukotrienes and other mediators in the pathophysiology of asthma and rhinitis. Three leukotriene modifiers now have been approved for the treatment of asthma in the United States; their potential use in the treatment of rhinitis has been a focus of considerable speculation and investigation. An early “day in the park” study showed that with antileukotriene therapy, patients with rhinitis had demonstrable improvements in their rhinitic symptoms.²⁹ Roquet et al⁸³ reported that in the treatment of asthma, there was a synergistic effect when an antileukotriene agent and an antihistamine were used, compared with either drug alone. A product combining an antileukotriene with an antihistamine is currently under development.

The most exciting developments, however, may be in the immunology arena. As described by Baraniuk elsewhere in this issue, the pathophysiology of allergic rhinitis is highly complex. Multiple interacting, interdependent, and redundant pathways and molecular and cellular constituents are involved in the pathogenesis of allergic rhinitis.

Briefly, exposure of the nasal mucosa to allergen in a sensitized individual leads to the release and further production of inflammatory mediators and the release of cytokines.⁵ These released cytokines activate endothelial cells, thereby inducing expression of adhesion receptors on the cell surface and initiating a cascade of events that facilitates transendothelial migration of inflammatory cells. T lymphocytes also are activated by these cytokines. Within a given tissue, specific patterns of cytokines are released, dependent on the dominant subset of local T lymphocytes. These, in turn, lead to the preferential activation and recruitment of specific inflammatory cells and the characteristic cellular inflammation observed in allergic rhinitis.

Differential diagnosis of chronic airflow obstruction

Chronic obstructive pulmonary disease is a syndrome including illnesses such as asthma, chronic bronchitis, and emphysema. Although these diseases share a common obstructive component, their optimal treatment and prognosis differ. This article examines the salient features of the history, physical exam, pulmonary function tests, and radiological evaluation which may allow the clinician to differentiate the various diseases that make up COPD; thus allowing the clinician to better target the multiple therapeutic modalities available.

Smoking and chronic obstructive pulmonary disease

Smoking is overwhelmingly the major cause of chronic bronchitis and emphysema worldwide. Additional risk factors for developing COPD are presented, along with the variables that govern cigarette smoke deposition in the lung. Major paradigms for the pathogenesis of COPD, including the protease-antiprotease and oxidant-antioxidant theories are described, and evidence for impaired reparative mechanisms in the causation of emphysema is noted. A description of the natural history of declining lung function in smokers and in the susceptible subset of smokers that ultimately develop smoking-induced COPD is accompanied by a discussion of the effects of smoking cessation on preservation of lung health. The disordered ventilation and gas-exchange physiology in the cigarette smoke-damaged lung is explained on the basis of the observed morphological changes.