Can inhaled corticosteroids influence the natural history of asthma?

Mechanisms underlying corticosteroid resistance in patients with asthma: a review of current knowledge

INTRODUCTION

Corticosteroids are the most cost-effective anti-inflammatory drugs available for the treatment of asthma. Despite their effectiveness, several asthmatic patients have corticosteroid resistance or insensitivity and exhibit a poor response. Corticosteroid insensitivity implies a poor prognosis due to challenges in finding alternative therapeutic options for asthma.

AREAS COVERED

In this review, we describe asthma phenotypes and endotypes, as well as their differential responsiveness to corticosteroids. In addition, we describe the mechanism of action of corticosteroids underlying their regulation of the expression of glucocorticoid receptors (GRs) and their anti-inflammatory effects. Furthermore, we summarize the mechanistic evidence underlying corticosteroid-insensitive asthma, which is mainly related to changes in GR gene expression, structure, and post-transcriptional modifications. Finally, various pharmacological strategies designed to reverse corticosteroid insensitivity are discussed.

EXPERT OPINION

Corticosteroid insensitivity is influenced by the asthma phenotype, endotype, and severity, and serves as an indication for biological therapy. The molecular mechanisms underlying corticosteroid-insensitive asthma have been used to develop targeted therapeutic strategies. However, the lack of clinical trials prevents the clinical application of these treatments.

Cardiac autonomic modulation assessed by heart rate variability in children with asthma

OBJECTIVE

To assess cardiac autonomic modulation, measured by short-term frequency domain analysis of heart rate variability (HRV), in children with asthma.

METHODS

We conducted an observational study at a tertiary care teaching hospital. The sample consisted of 119 children aged 7 to 15 years with asthma and 56 age-matched healthy controls. Frequency domain HRV measures included low-frequency (LF; 0.04-0.15 Hz), high-frequency (HF; 0.15-0.4 Hz), and LF/HF ratio. The LF and HF components were expressed in both absolute values of power (ms² ) and in normalized units (nu).

RESULTS

Compared with healthy controls, asthmatic children had significantly higher value of HF (nu) (mean ± standard deviation: 45.9 ± 14.6 vs 40.7 ± 13.6; P = .02), and lower values of LF (nu) (54.1 ± 14.6 vs 59.3 ± 13.6; P = .02) and LF/HF ratio (median, interquartile range: 1.12, 0.82-1.88 vs 1.59, 1.02-2.08; P = .03). We did not find significant differences between children with persistent and intermittent asthma, and between children with well-controlled and partially-controlled or uncontrolled asthma, in terms of HRV measures.

CONCLUSIONS

Children with stable chronic asthma may have a cardiac autonomic imbalance with a possible enhanced parasympathetic modulation, as assessed by short-term frequency domain analysis of HRV. Neither asthma severity nor asthma control was significantly associated with HRV measures, but the study did not have enough power to draw a firm conclusion on this point.

Biological mechanisms underlying the clinical effects of allergen-specific immunotherapy in asthmatic children

INTRODUCTION

Allergen-specific immunotherapy (AIT) is indicated for patients with allergic asthma and/or allergic rhinitis, and can be implemented by either subcutaneous injection (SCIT) or sublingual administration (SLIT). AIT reduces asthma symptoms, lowers the use of pharmacologic controller therapy, and decreases the need for rescue medications. SLIT appears to be safer than SCIT, but SCIT seems to be more efficacious and acts earlier in allergic asthmatic children.

AREAS COVERED

This review looks at the pathobiology of allergic asthma as well as the role of regulatory T and B cells in allergen tolerance. It also reviews the immunological mechanisms underlying the clinical effects induced by AIT in allergic asthmatic children.

EXPERT OPINION

AIT is very effective in allergic asthmatic children, who can significantly benefit from this particular type of immunotherapy in order to achieve a better control of their disease. AIT is also capable of modifying the natural history of allergic asthma. Furthermore, AIT can potentially represent a valuable therapeutic tool within the context of precision medicine, as recombinant allergen technology might allow the creation of targeted extracts able to be effective against specific proteins to which individual asthmatic children are allergic, thus helping to implement a personalized approach to treatment.

The footprint of TGF-β in airway remodeling of the mustard lung

Mustard lung is a major pulmonary complication in individuals exposed to sulfur mustard (SM) gas during the Iran-Iraq war. It shares common pathological and clinical features with some chronic inflammatory lung disorders, particularly chronic obstructive pulmonary disease (COPD). Airway remodeling, which is one of the main causes of lung dysfunction and the dominant phenomenon of chronic pulmonary diseases, is seen in the mustard lung. Among all mediators involved in the remodeling process, the transforming growth factor (TGF)-β plays a pivotal role in lung fibrosis and consequently in the airway remodeling. Regarding the high levels of this mediator detected in mustard lung patients, in the present study, we have discussed the possible roles of TGF-β in airway remodeling (including epithelial layer damage, subepithelial fibrosis and angiogenesis). Finally, based on TGF-β targeting, we have reviewed new airway remodeling therapeutic approaches.

Asthma

Asthma is the most common inflammatory disease of the lungs. The prevalence of asthma is increasing in many parts of the world that have adopted aspects of the Western lifestyle, and the disease poses a substantial global health and economic burden. Asthma involves both the large-conducting and the small-conducting airways, and is characterized by a combination of inflammation and structural remodelling that might begin in utero. Disease progression occurs in the context of a developmental background in which the postnatal acquisition of asthma is strongly linked with allergic sensitization. Most asthma cases follow a variable course, involving viral-induced wheezing and allergen sensitization, that is associated with various underlying mechanisms (or endotypes) that can differ between individuals. Each set of endotypes, in turn, produces specific asthma characteristics that evolve across the lifecourse of the patient. Strong genetic and environmental drivers of asthma interconnect through novel epigenetic mechanisms that operate prenatally and throughout childhood. Asthma can spontaneously remit or begin de novo in adulthood, and the factors that lead to the emergence and regression of asthma, irrespective of age, are poorly understood. Nonetheless, there is mounting evidence that supports a primary role for structural changes in the airways with asthma acquisition, on which altered innate immune mechanisms and microbiota interactions are superimposed. On the basis of the identification of new causative pathways, the subphenotyping of asthma across the lifecourse of patients is paving the way for more-personalized and precise pathway-specific approaches for the prevention and treatment of asthma, creating the real possibility of total prevention and cure for this chronic inflammatory disease.

Effects of exercise training on airway hyperreactivity in asthma: a systematic review and meta-analysis

BACKGROUND

Although physical exercise is recommended for asthmatics, evidence on the effects of exercise on clinical key factors is still missing.

OBJECTIVES

We performed a systematic review and meta-analysis to determine the effect of exercise training (EXT) on quality of life (QoL), bronchial hyperresponsiveness (BHR), exercise-induced bronchoconstriction (EIB), lung function and exercise capacity, plus the factors affecting changes in QoL and exercise capacity in asthmatics after a period of EXT.

DATA SOURCES

A computerized search was conducted in MEDLINE, EMBASE, and CINAHL (last search on 15 November 2012), without language restriction, and references of original studies and reviews were searched for further relevant studies.

STUDY SELECTION

Two independent investigators screened full-text studies with asthmatic subjects undertaking EXT (defined as training for ≥7 days, ≥2 times per week, ≥5 training sessions in total) that assessed at least one of the following outcomes: QoL, airway hyperreactivity, forced expiratory volume in one second (FEV₁), peak expiratory flow (PEF), inflammatory parameters, exercise capacity, or exercise endurance. Potentially relevant studies were excluded if only respiratory muscle training, breathing exercises or yoga was performed, if asthmatic subjects with co-morbidities were investigated, if only data of mixed patient groups without separate results for asthmatics were presented, if training regimens were not sufficiently specified, if no numerical outcome data were presented, and if new long-term medication was introduced in addition to physical training. Of 500 potentially relevant articles, 13.4 % (67 studies including 2,059 subjects) met the eligibility criteria and were included for further analyses.

STUDY APPRAISAL AND SYNTHESIS METHODS

Data extraction and risk of bias assessment was performed according to the Cochrane Handbook for Systematic Reviews of Interventions. A meta-analysis of all randomized controlled trials (RCTs) was performed to determine the effect of EXT on asthma symptoms, BHR, EIB, FEV₁, exercise capacity and exercise endurance compared with control training. In addition, relative pre/post changes were analysed in all RCTs and controlled trials. Finally, multiple linear regression models were used to identify effects of relative changes in airway hyperreactivity (BHR or EIB), lung function (FEV₁ or PEF) and training hours on QoL and exercise performance.

RESULTS

In a total of 17 studies including 599 subjects, meta-analyses showed a significant improvement in days without asthma symptoms, FEV1 and exercise capacity while BHR only tended to improve. The analysis of relative within-group changes after EXT showed, however, significant improvements in QoL (17 %), BHR (53 %), EIB (9 %), and FEV1 (3 %) compared with control conditions. Multiple linear regression models revealed that changes in airway hyperreactivity and lung function significantly contributed to the change in QoL, while mainly the changes in airway hyperreactivity contributed to the change in exercise capacity.

CONCLUSION

EXT was shown to improve asthma symptoms, QoL, exercise capacity, BHR, EIB, and FEV1 in asthmatics and improvements in BHR explained part of the improvement in QoL and exercise capacity. Thus, physical activity should be recommended as a supplementary therapy to medication. However, more well controlled studies should be performed assessing the relationship of physical activity, QoL, airway hyperreactivity, lung function and especially airway inflammation as well as medication intake.

Changes in forced expiratory volume in 1 second over time in patients with controlled asthma at baseline

BACKGROUND

A predominant feature of asthma is an accelerated rate of decline in forced expiratory volume in 1 s (FEV1), but data on the variability and factors associated with this change in patients with controlled asthma are largely unknown.

METHODS

140 patients with controlled asthma were enrolled based on the Global Initiative for Asthma guidelines. We examined the data of a prospective analysis of the association between asthma control and change in FEV1 over time.

RESULTS

A 3-year follow-up assessment was completed in 128 patients. The mean rate of change in FEV1 was a decline of 22.2 mL yr(-1), with significant variation in the levels of change. The between patient standard deviation for the rate of decline was 34.1 mL yr(-1). We next classified the subjects of less than the 25th percentile as rapid decliners, and greater than the 25th percentile as non-rapid decliners. The decrease in the Asthma Control Test score over a 3-year period was higher for rapid decliners than that for non-rapid decliners (p < 0.001). The rapid decliner was more likely to be older, to have higher levels of FeNO, and to have had severe exacerbations during the study. Patients with severe exacerbations had a greater annual decline in FEV1 compared to patients with no exacerbations (-13.6 vs. -53.2 mL yr(-1), p < 0.0001).

CONCLUSIONS

Among patients with controlled asthma at baseline, the rate of change in FEV1 is highly variable. Severe exacerbations are strongly associated with a rapid loss of lung function.

Corticosteroids for acute and subacute cough following respiratory tract infection: a systematic review

BACKGROUND

Cough associated with acute respiratory tract infection (RTI) is one of the most common problems managed in primary care. Despite minimal evidence for the use of antibiotics, they continue to be prescribed at great cost and are a significant cause of emerging bacterial resistance.

OBJECTIVES

To carry out a systematic review of randomized controlled trials to evaluate the effect of corticosteroid therapy in otherwise-healthy adults with acute RTI.

METHODS

Seven electronic databases and five ongoing trial registers were searched. Studies were eligible if they compared the use of any corticosteroid treatment against a control group in adults with an acute (<3 weeks) or subacute (<8 weeks) cough associated with an RTI but no asthma. Primary outcomes were differences in mean cough and other symptom scores. Secondary outcomes included adverse effects, subsequent diagnosis of asthma and patient satisfaction.

RESULTS

Four trials (335 participants) investigating the effects of inhaled corticosteroids were identified. None investigated the use of oral corticosteroids. Results were mixed, with two reporting equivalence and two reporting benefits for mean cough score (P = 0.012) and cough frequency (P = 0.047). One reported additional benefits in non-smokers. Adverse events were rare and there were no data on patient satisfaction or the subsequent diagnosis of asthma. Most trials were of unclear risk of bias. Study outcomes were too heterogeneous to meta-analyse.

CONCLUSIONS

There is insufficient evidence to recommend the routine use of inhaled corticosteroids for acute RTI in adults. However, some trials have shown benefits, suggesting the need for further high-quality, adequately powered trials.

Fluticasone Induces Epithelial Injury and Alters Barrier Function in Normal Subjects

Objective

The airway epithelium has a number of roles pivotal to the pathogenesis of asthma, including provision of a physical and immune barrier to the inhaled environment. Dysregulated injury and repair responses in asthma result in loss of airway epithelial integrity. Inhaled corticosteroids are a corner stone of asthma treatment. While effective in controlling asthma symptoms, they fail to prevent airway remodeling. Direct cytopathic effects on the airway epithelium may contribute to this.

Methods

This study examined the effects of a 4-week treatment regimen of inhaled fluticasone 500 μg twice daily in healthy human subjects. Induced sputum was collected for cell counts and markers of inflammation. Barrier function was examined by diethylenetriaminepentacetic acid (DTPA) clearance measured by nuclear scintillation scan, and albumin concentration in induced sputum.

Results

Steroid exposure resulted in epithelial injury as measured by a significant increase in the number of airway epithelial cells in induced sputum. There was no change in airway inflammation by induced sputum inflammatory cell counts or cytokine levels. Epithelial shedding was associated with an increase in barrier function, as measured by both a decrease in DTPA clearance and decreased albumin in induced sputum. This likely reflects the normal repair response.

Conclusion

Inhaled corticosteroids cause injury to normal airway epithelium. These effects warrant further evaluation in asthma, where the dysregulated repair response may contribute to airway remodeling.

Cross-roads in the lung: immune cells and tissue interactions as determinants of allergic asthma

Allergic asthma is a chronic disease of the lung characterized by underlying Th2- and IgE-mediated inflammation, structural alterations of the bronchial wall, and airway hyperresponsiveness. Initial allergic sensitization and later development of chronic disease are determined by close interactions between lung structural cells and the resident and migratory immune cells in the lung. Epithelial cells play a crucial role in allergic sensitization by directly influencing dendritic cells induction of tolerant or effector T cells and production of type 2 cytokines by innate immune cells. During chronic disease, the bronchial epithelium, stroma, and smooth muscle become structurally and functionally altered, contributing to the perpetuation of tissue remodeling. Thus, targeting tissue-driven pathology in addition to inflammation may increase the effectiveness of asthma treatment.

Untangling asthma phenotypes and endotypes

Asthma phenotypes have been developed to address the complexities of the disease. However, owing to a lack of longitudinal studies, little is known about the onset as well as the stability of phenotypes. Distinguishing phenotypes with regard to the severity or duration of the disease is essential. A phenotype covers the clinically relevant properties of the disease, but does not show the direct relationship to disease etiology and pathophysiology. Different pathogenetic mechanisms might cause similar asthma symptoms and might be operant in a certain phenotype. These putative mechanisms are addressed by the term 'endotype'. Classification of asthma based on endotypes provides advantages for epidemiological, genetic, and drug-related studies. A successful definition of endotypes should link key pathogenic mechanisms with the asthma phenotype. Thus, the identification of corresponding molecular biomarkers for individual pathogenic mechanism underlying phenotypes or subgroups within a phenotype is important. Whether newly defined asthma endotypes predict the individual course of asthma has to be validated in longitudinal studies. The accurate endotyping reflects natural history of asthma and should help to predict treatment response. Thus, understanding asthma endotypes might be useful in clinical practice.

Grape seed extract attenuates lung parenchyma pathology in ovalbumin-induced mouse asthma model: an ultrastructural study

Due to the growing incidence of asthma and because of the non-specificity and side effects of the conventional drugs, the development of novel agents for the treatment of asthma has become considerably important. Natural plant products offer promising alternatives for the development of effective and safe treatments. Grape seed extract (GSE) is one such phytochemical supplement that has been shown to have potent antioxidant and anti-inflammatory effects. Thus, the present study aimed to investigate the effect of GSE to suppress lung parenchyma pathology and inflammation in ovalbumin-induced murine asthma model. Ovalbumin exposure was associated with many pathological and morphometric alterations in the lungs of asthmatic mice. The alterations involved alveolar size reduction, alveolar wall thickening, cellular infiltration and blood capillary congestion, as well as significant increase in the number of type II pneumocytes and lamellar bodies. However, GSE significantly ameliorated of the pathological changes of ovalbumin-induced asthma. The results support the possibility of GSE as an effective, safe anti-inflammatory dietary supplement to attenuate the pathogenicity of asthma. While these preliminary results appear promising, further studies are required to elucidate the precise mechanism of the modulatory effect of GSE on asthma remodeling.

Microbial influences on epithelial integrity and immune function as a basis for inflammatory diseases

Certain autoimmune diseases as well as asthma have increased in recent decades, particularly in developed countries. The hygiene hypothesis has been the prevailing model to account for this increase; however, epidemiology studies also support the contribution of diet and obesity to inflammatory diseases. Diet affects the composition of the gut microbiota, and recent studies have identified various molecules and mechanisms that connect diet, the gut microbiota, and immune responses. Herein, we discuss the effects of microbial metabolites, such as short chain fatty acids, on epithelial integrity as well as immune cell function. We propose that dysbiosis contributes to compromised epithelial integrity and disrupted immune tolerance. In addition, dietary molecules affect the function of immune cells directly, particularly through lipid G-protein coupled receptors such as GPR43.

The course of asthma activity: a population study

BACKGROUND

Unlike most chronic diseases, which tend to progress over time, asthma is known to persist, possibly resolve, and/or present with any combination of remissions and relapses. As a result, its course has been difficult to characterize and its prognosis difficult to predict.

OBJECTIVE

To quantify the proportion of individuals with asthma who have active disease and, of those, the proportion who experience significant gaps in their asthma activity; and to determine factors associated with asthma activity.

METHODS

Universal population health administrative databases were used to identify all individuals with asthma living in Ontario, Canada, in 1993 and follow them for 15 years. Active asthma was indicated by 1 or more physician claims for asthma.

RESULTS

Of 613,394 individuals with asthma in 1993, 504,851 (82.3%) had active disease in subsequent years. Of those who had complete follow-up, 74.6% experienced a gap of 2 or more years in their asthma activity. Previous asthma claims, older and younger age, and a codiagnosis of chronic obstructive pulmonary disease correlated with greater asthma activity.

CONCLUSION

Over 15 years, most individuals with asthma in Ontario, Canada, had active disease that was interspersed by periods of inactivity when they did not require medical attention and were likely in remission. These analyses offer insight into the natural course of asthma activity that may help improve the ability to predict an individual's course of disease.

Apoptosis and the airway epithelium

The airway epithelium functions as a barrier and front line of host defense in the lung. Apoptosis or programmed cell death can be elicited in the epithelium as a response to viral infection, exposure to allergen or to environmental toxins, or to drugs. While apoptosis can be induced via activation of death receptors on the cell surface or by disruption of mitochondrial polarity, epithelial cells compared to inflammatory cells are more resistant to apoptotic stimuli. This paper focuses on the response of airway epithelium to apoptosis in the normal state, apoptosis as a potential regulator of the number and types of epithelial cells in the airway, and the contribution of epithelial cell apoptosis in important airways diseases.

New perspectives in pharmacological treatment of mild persistent asthma

Until the relationship between symptoms, lung function tests, airway inflammation, airway hyper-responsiveness (AHR), exacerbations and remodelling is clarified, regular treatment seems to enable a greater disease control than on-demand therapy in most patients with mild persistent asthma. Current guideline classification based on disease severity remains a cornerstone in asthma management. However, the heterogeneity of asthma, the growing emphasis on subphenotypes, including molecular phenotypes identified by -omics technologies, and their possible implications in terms of different asthma severity, progression and therapeutic response, are changing current asthma treatment mainly based on disease severity classification to a pharmacological strategy more focused on the individual patient.

Pharmacotherapy of patients with mild persistent asthma: strategies and unresolved issues

In studies comparing regular versus on-demand treatment for patients with mild persistent asthma, on-demand treatment seems to have a similar efficacy on clinical and functional outcomes, but it does not suppress chronic airway inflammation or airway hyper-responsiveness (AHR) associated with asthma. Data on the efficacy of a continuous treatment with inhaled corticosteroids (ICS) in preventing the progression of asthma are conflicting. There is the possibility that patients without a regular treatment with ICS may develop a more severe asthma associated with airway structural changes (remodeling) and a progressive loss of lung function. However, the possible clinical and functional consequences of persistent, not controlled, airway inflammation in patients with asthma have to be established. Assessment of asthma control should include inflammatory outcomes, such as fraction of exhaled nitric oxide and sputum eosinophil counts. Until the relationships between symptoms, lung function tests, AHR, airway inflammation, exacerbations, and airway remodeling are clarified, regular treatment seems to be generally more appropriate than on-demand treatment to warrant a greater control of asthma. Select subgroups of patients with mild asthma who are well controlled by regular treatment might adopt the on-demand treatment plan as an intermediate step toward the suspension of controller medication. The increasing evidence for heterogeneity of asthma, the growing emphasis on asthma subphenotypes, including molecular phenotypes identified by omics technologies, and their possible implications for different asthma severity and progression and therapeutic response, are changing the paradigm of treating patients with asthma only based on classification of their disease severity to a pharmacological strategy more focused on the individual asthmatic patient. Pharmacological treatment of asthma is going toward a personalized approach.

The persistence of allergen exposure favors pulmonary function decline in workers with allergic occupational asthma

BACKGROUND

In asthmatics, a rapid decline in pulmonary function is observed, likely as a consequence of airways remodeling. Persistence of allergen exposure in patients with occupational asthma (OA) maintains chronic bronchial inflammation, resulting in a more severe lung function decline. Few studies were performed on the effects of allergen exposure cessation.

OBJECTIVE

This study aims at evaluating the influence of allergen exposure cessation on respiratory decline in allergic asthmatic workers.

METHODS

Two groups of workers with allergic OA were selected. The first group (30 workers) changed job after the diagnosis and was no more exposed to sensitizing allergens, and the second group (28 subjects) did not and, as a consequence of preventive measures in the work place, was exposed to a lower level of allergens. All were treated with conventional therapy, according to GINA protocols. FEV1 changes during a 12-year period were evaluated.

RESULTS

Despite pharmacological therapy, the pulmonary function decay slope was steeper in workers continuously exposed to the sensitizing agent (even at reduced level) than in those with a complete cessation of exposure: final FEV1 loss was 512.5 ± 180 ml versus 332.5 ± 108 ml, respectively. The difference became significant after 4 years from the cessation of the exposure.

CONCLUSIONS

The study shows that the cessation of the exposure to allergen in the work place appears the most effective measure in limiting pulmonary function decline in asthmatic workers and underlines the importance of allergic risk assessment and control in the management of occupational asthma.

Pulmonary remodeling in asthma

The inflammatory and immunologic processes responsible for asthma can produce permanently fixed obstructive lung disease unresponsive to medical therapy. This can be manifested clinically by the failure of a childhood asthmatic to reach full expected lung capacity at adulthood and by an accelerated decline in pulmonary capacity in adults. Recent studies have furthered our insight into the pathologic processes underlying these changes and the potential effects of therapy to prevent them.

Pathological airway remodelling in inflammation

INTRODUCTION

Airway remodelling refers to a wide pattern of pathophysiological mechanisms involving smooth muscle cell hyperplasia, increase of activated fibroblasts and myofibroblasts with deposition of extracellular matrix. In asthma, it includes alterations of the epithelial cell layer with goblet cell hyperplasia, thickening of basement membranes, peri-bronchial and peri-bronchoalveolar fibrosis. Moreover, airway remodelling occurs not only in asthma but also in several pulmonary disorders such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis and systemic sclerosis. Asthma treatment with inhaled corticosteroids does not fully prevent airway remodelling and thus have restricted influence on the natural course of the disease.

OBJECTIVES

This review highlights the role of different fibroblast phenotypes and potential origins of these cells in airway remodelling.

RESULTS

During inflammatory conditions, such as asthma, fibroblasts can differentiate into an active, more contractile phenotype termed myofibroblast, with expression of stress fibres and alpha-smooth muscle actin. The origin of myofibroblasts has lately been debated, and three sources have been identified: recruitment and differentiation of resident tissue fibroblasts; fibrocytes - circulating progenitor cells; and epithelial-mesenchymal transition.

CONCLUSION

It is clear that airway mesenchymal cells, including fibroblasts/myofibroblasts, are more dynamic in terms of differentiation and origin than has previously been recognised. Considering that these cells are key players in the remodelling process, it is of utmost importance to characterise specific markers for the various fibroblast phenotypes and to explore factors that drive the differentiation to develop future diagnostic and therapeutic tools for asthma patients.

Montelukast in the treatment of asthma and beyond

Asthma is a chronic inflammatory disease affecting over 300 million people worldwide. The common association with allergic rhinitis and the presence of proinflammatory cells and mediators in the circulation of patients qualify asthma as a systemic disease. This characteristic and the fact that the gold-standard therapy for persistent asthma, inhaled corticosteroids, cannot suppress all components of airway inflammation and fail to adequately penetrate into the small airways, warrant the quest for effective systemic anti-asthma therapies. This review describes the most important controlled studies of montelukast, a once-daily leukotriene receptor antagonist, in asthma and allergic rhinitis in both adults and children. Montelukast is a systemically active drug with a targeted, dual mechanism of action, acting both as a bronchodilator and anti-inflammatory. In patients of all ages, montelukast has shown a favorable safety profile and was well-tolerated. Both as monotherapy or in combination with inhaled corticosteroids, montelukast produced clinically relevant improvements in asthma-related parameters, including symptoms, lung function parameters, quality of life and the number of asthma exacerbations. Furthermore, bronchoprotective effects have been reported both against specific and nonspecific bronchoactive stimuli. Similarly, in patients with allergic rhinitis, montelukast produced substantial improvements in symptoms and quality of life. Long-term studies aimed to determine its effects on airway remodeling are still lacking.

Growing old with asthma: what are the changes and challenges?

Asthma is a disease that affects approximately 7% of adults residing in the USA; the prevalence is even greater in children and approaches 10%. The CDC has reported that the overall prevalence of lifetime asthma is 10.5%. New-onset asthma is most often seen in children and is associated with atopy; however, the majority of patients will experience a remission during adolescence. Many former asthmatics will have a reoccurrence of their disease in adulthood and asthma may persist thereafter for a lifetime. New-onset asthma may also begin later in life and remission is uncommon. The burden of asthma is therefore high in the geriatric population and healthcare utilization and mortality from asthma is excessive in this age group. There are many differences with asthma occurring in older adults when compared with younger asthmatics. This includes the frequency of medical comorbidities, the presence in many patients of fixed airflow obstruction that resembles chronic obstructive pulmonary disease, and the lack of perception of dyspnea that may delay effective medical care. Despite these and other differences, the pathophysiology and clinical presentation of asthma in the elderly is similar to that in younger asthmatics and attention to the unique features of aging can lead to improved outcomes in this age group.

Anti-inflammatory treatment of asthma: differentiation and trial-and-error

The relative lack of evidence for anti-inflammatory treatment of some phenotypes of asthma in children has been highlighted in recent guidelines and consensus reports specifically aiming at the paediatric population. Consequently, we are left with a need for defining treatment strategies in the clinical setting. The decision to initiate antiinflammatory treatment should be based on assessments of the individual child's age, the type of asthma, severity, heredity and atopic condition, adherence factors and sensitivity to systemic adverse effects of treatment options. Inhaled corticosteroids are potent anti-inflammatory agents that are effective in the whole spectrum of asthma in school age children. In toddlers with viral wheeze and in children with mild asthma oral leukotriene receptor antagonists or inhaled corticosteroids may be given on a trial-and-error basis.

CONCLUSION

To treat all children with asthma equally effectively from infancy through adolescence does not mean that they should be treated identically and in some types of asthma a trial-and-error approach may be warranted.