Children with difficult asthma: a practical approach

Diagnostic and Prognostic Risk Assessment of Heat Shock Protein HSPA1B rs2763979 Gene Variant in Asthma

Given the significant role the heat shock protein Hsp70 plays in modulating cellular homeostasis in several chronic inflammatory disorders, the genetic variation of the inducible HSP70 (HSPA1B) gene may impact protein expression and disease phenotype. The HSPA1B rs2763979 variant has been associated with multiple inflammatory scenarios, but no previous studies have explored its association with asthma. In this sense, this cross-sectional study enrolled 90 children with asthma and 218 age-/sex-matched healthy volunteers for rs2763979 variant genotyping by TaqMan allelic discrimination analysis. The results were investigated under several genetic models and associated with disease susceptibility and clinicolaboratory data. Overall analysis, including the 308 participants, revealed a higher C allele frequency among patients relative to controls (43.0% vs. 33%, p = 0.006). Furthermore, patients with the C variant initially had a higher risk of asthma under heterozygous (OR = 2.75, 95%CI = 1.46-5.18, p = 0.003), homozygous (OR = 3.35, 95%CI = 1.19-9.39, p = 0.008), dominant (OR = 2.83, 95%CI = 1.52-5.25, p < 0.001), and overdominant (OR = 2.12, 95%CI = 1.20-3.74, p = 0.008) models. However, after employing a 1:1 nearest propensity matching analysis, the studied variant showed only borderline significance with asthma under the dominant model in 71 matched cohorts. Interestingly, patients who carry the rs2763979 CC genotype showed favorable spirometric parameters in terms of better (mean ± SD) forced vital capacity (86.3 ± 7.4 vs. 77.7 ± 6.1 and 75.7 ± 7.2 for CT and TT, respectively, p = 0.021), forced expiratory volume in one second before bronchodilation (60.7 ± 12.9 vs. 54.9 ± 7.6 and 56.1 ± 7.5 for CT and TT, respectively, p = 0.021), and an improvement in peak expiratory flow rate after inhaled salbutamol bronchodilator (p = 0.044) relative to the counterpart genotypes. In conclusion, the HSPA1B rs2763979 variant might have prognostic utility as a genetic marker for asthma in our population. Further larger studies on different ethnicities are recommended to validate the results.

[News in childhood asthma therapy]

Research in the field of paediatric pulmonology, especially asthmology, has been intensified for the last couple of years. A large number of studies describe early wheezing episodes, risk factors, natural course of early childhood asthma. Besides this, literature shows a growing interest in epidemiology, genetics and virusology as predictive factors for development and clinical course of childhood asthma. In this paper, the authors are providing a review of recently published articles on asthma therapy based on phenotypes in terms of better understanding of asthma and asthma-like syndromes. Paediatric respiratory experts worldwide are equally positive in the following statements: real diagnosis leads to real therapy as soon as possible; inhaled corticosteroids are not recommended in very young infants especially if a positive effect is missing; long-term therapy with inhaled corticosteroids has to be scrutinized.

Diagnosis and treatment of asthma in childhood: a PRACTALL consensus report

Asthma is the leading chronic disease among children in most industrialized countries. However, the evidence base on specific aspects of pediatric asthma, including therapeutic strategies, is limited and no recent international guidelines have focused exclusively on pediatric asthma. As a result, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology nominated expert teams to find a consensus to serve as a guideline for clinical practice in Europe as well as in North America. This consensus report recommends strategies that include pharmacological treatment, allergen and trigger avoidance and asthma education. The report is part of the PRACTALL initiative, which is endorsed by both academies.

Airway inflammation in children with difficult asthma: relationships with airflow limitation and persistent symptoms

BACKGROUND

The effective management and development of new treatments for children with difficult asthma requires investigation of the underlying airway pathology and its relationships with persistent symptoms and airflow limitation.

METHODS

The density of immunologically distinct inflammatory cells and cells expressing interleukin (IL)-4, IL-5, and RANTES was determined in paraffin-embedded endobronchial biopsy specimens from 27 children with difficult asthma (6-16 years) following treatment with systemic corticosteroids. Eleven non-asthmatic children (7-16 years) acted as controls. Reticular basement membrane (RBM) thickness was also recorded and forced expiratory volume in 1 second (FEV(1)) and exhaled nitric oxide (FE(NO)) measured, the latter in asthmatic children only.

RESULTS

RBM thickness was greater in the asthmatic than the control group (median (range) 7.4 (3.1-11.1) v 5.1 (3.5-7.5) microm, p = 0.02). No other significant tissue difference was seen, nor was there a difference between asthmatic subjects with daily symptoms after systemic corticosteroids and those who became asymptomatic. CD4+ T lymphocyte density was higher in asthmatic subjects with persistent airflow limitation (post-bronchodilator FEV(1)<80% predicted) than in those without (9.1 (5.5-13.6) v 3.5 (0.6-34.9)%, p = 0.027). Analysing all asthmatic subjects together, there were negative correlations between CD4+ T lymphocytes and both pre-bronchodilator FEV(1) (r = -0.57 (95% CI -0.79 to -0.23), p = 0.002) and post-bronchodilator FEV(1) (r = -0.61 (95% CI -0.81 to -0.29), p<0.001). There were no significant correlations between FE(NO) and inflammatory cells of any type.

CONCLUSION

In children with difficult asthma treated with systemic corticosteroids, persistent airflow limitation is associated with a greater density of CD4+ T lymphocytes in endobronchial biopsy specimens.

Phenotype-specific treatment of difficult asthma in children

Most children with asthma can be treated successfully with low-to-moderate doses of inhaled corticosteroid and long-acting beta-2 agonist. Those that fail to respond are a heterogeneous group. We propose that the nature and type of any steroid-resistant inflammation, the extent of any persistent airflow limitation and the extent of bronchial hyper-reactivity should be determined separately to allow a rational treatment approach to these children, rather than the haphazard advice of many current guidelines. Reasons for persistent difficult asthma include persistent eosinophilic inflammation, non-eosinophilic inflammation, airway reactivity without residual inflammation and persistent airflow limitation. We propose a protocol that uses non-invasive and invasive (bronchoscopic) methods to document the response to systemic steroids (depot triamcinolone). The aim of the protocol is to determine an individualised treatment plan; for example, cyclosporin for persistent eosinophilic inflammation, azithromycin for persistent neutrophilic inflammation and continuous subcutaneous terbutaline if there is airway reactivity without residual inflammation. Multi-centre studies are required to test the utility of this approach.

The need for pediatric studies of allergy and asthma medications

For many years, clinicians have accepted the fact that most medications do not have dosing guidelines for children younger than 12 years of age. Recently, there has been a great effort to correct this deficiency. With the introduction of the 1997 Food and Drug Administration Modernization Act, a provision was established to grant additional market exclusivity to pharmaceutical firms that performed the required studies that would lead to improved labeling of medications for children. This effort has resulted in a significant advance for the management of asthma and allergic disorders in children. Several allergy and asthma medications are now approved for use in children as young as 1 year of age, with studies currently being conducted in younger age groups. In this review, we discuss the background for this effort and the continuing impact it will have on the future management of allergy and asthma in children.

Clinical and biological heterogeneity in children with moderate asthma

To evaluate the relationship between inflammatory markers and severity of asthma in children, the amount of interleukin-8 (IL-8) and granulocyte/macrophage colony-stimulating factor (GM-CSF) released by peripheral blood mononuclear cells, exhaled nitric oxide (FE NO) levels, p65 nuclear factor-kappaB subunit, and phosphorylated IkBalpha expression by peripheral blood mononuclear cells were assessed in six control subjects, 12 steroid-naives subjects with intermittent asthma, and 17 children with moderate asthma. To investigate their predictive value, biomarker levels were correlated with the number of exacerbations during a 18-month follow-up period. We found that GM-CSF release was higher in moderate and intermittent asthmatics than in control subjects, whereas IL-8 release was higher in moderate than in intermittent asthmatics and control subjects. FE NO levels were similar among study groups. In moderate asthmatics, IL-8, GM-CSF, and FE NO significantly correlated with the exacerbation numbers. Moreover, p65 and phosphorylated IkBalpha levels were greater in moderate than in intermittent asthmatics and control subjects. According to GM-CSF, IL-8, and FE NO levels, two distinct subgroups of moderate asthmatics (low and high producers) were identified. High producers experienced more exacerbations than low producers. This study shows ongoing inflammation associated with biological and clinical heterogeneity in moderate asthmatics despite regular treatment and proposes that large prospective studies confirm the importance of biomarkers to assess inflammation and asthma control in children with asthma.

Identifying the child in need of asthma therapy

Based on the results of the long-term CAMP clinical trial in childhood asthma, the benefits of continuous long-term use of inhaled glucocorticoid on asthma control are clear. Studies are in progress to evaluate whether early intervention with inhaled glucocorticoids can alter the natural history of asthma. Indicators are now being defined to identify the patient at risk for persistent asthma and thus to identify candidates for early intervention. Given the right medication and the patient profile, it may be possible to induce remission or even a cure. Patients with severe asthma have low pulmonary function that is difficult to improve, however. It will be important to recognize patients at risk for severe asthma and to intervene more effectively to prevent asthma progression. None of these advances will be possible without a comprehensive approach to asthma care including the ready access to health care. Although it seems that the rise in asthma mortality and morbidity has reached a plateau, there are significant racial and ethic disparities in asthma health care use and mortality. The goal should now be to strive for a reduction in asthma morbidity and mortality. A high proportion of asthma morbidity among inner-city children may be related to nonadherence; therefore targeting management approaches to improve adherence could prove effective in reducing morbidity. Recommendations have been made to integrate available resources in the United States to improve overall asthma outcomes for children.

Advances in childhood asthma: hygiene hypothesis, natural history, and management

There is significant interest in early identification and intervention in childhood asthma. Current asthma guidelines identify inhaled corticosteroids (ICS) as the preferred initial long-term control therapy even in young children. ICS clearly improve asthma control in children with mild to moderate persistent asthma, but it is not clear that they can alter the natu-ral history and progression of asthma. New insights regarding the origins of asthma and allergy and their natural history will continue to stimulate questions regarding the appropriate time for intervention and will stimulate the design of new treatment strategies and the discovery of new medications.

[Difficult asthma in children]

Difficult asthma in children is defined as the persistence of exacerbations or frequent symptoms requiring rescue bronchodilator, or persistent airway obstruction in spite of treatment with inhaled steroid >/= 800 microg/d beclomethasone or equivalent and beta-2 long acting agonist. Management of difficult asthma in children first requires to identify conditions that may mimic asthma, asthma with bad compliance to treatment, and difficult asthma in relation with avoidable factors that worsen symptoms. The pathological bases of genuine difficult asthma remain unknown. Different patterns have been described according to the cells that are involved (eosinophil, neutrophil), the degree of airway remodeling, or the distal localization of the lesions. Difficult asthma requires specialized management including airway inflammation evaluation. Studies on bronchoalveolar lavage and bronchial mucosa biopsies will perhaps help to better understand the pathophysiology and to improve the management.

Treatment of severe small airways disease in children with cystic fibrosis: alternatives to corticosteroids

A group of patients with cystic fibrosis (CF) have severe small airways disease characterized by wheeze, chest tightness and limited sputum production, often with deteriorating lung function. Suggested mechanisms include mucosal edema secondary to infection and inflammation, smooth muscle contraction caused by inflammatory mediators, and collapse of bronchiectatic airways. While treatment with long-term oral corticosteroids may result in symptomatic improvement, adverse effects often make them intolerable. Inhaled corticosteroids are used in many centers despite the lack of conclusive evidence of their efficacy. Therapeutic alternatives to corticosteroids are aimed at reversing bronchoconstriction and reducing inflammation. Many patients with CF are treated with short- and long-term inhaled bronchodilators, but data to support their use are inconclusive. Other attempted routes of administration for short-acting bronchodilators include the subcutaneous and intravenous routes, but clinical data are again lacking. Sodium cromoglycate (cromolyn sodium) has been studied, with little evidence of benefit. Theophyllines have also been studied, both intravenously and orally, with some effect, but are not often used in clinical practice. Nonsteroidal anti-inflammatory therapies include ibuprofen, macrolide antibiotics, intravenous immunoglobulin, cyclosporine, and leukotriene antagonists. Ibuprofen has been shown to be useful in patients with mild CF disease, but concerns about potential adverse effects have limited its use. The results of various macrolide studies are awaited, but to date there are no long-term studies published. While there is great interest in the potential of intravenous immunoglobulin, cyclosporine and leukotriene antagonists, the evidence for their effectiveness comes from anecdotal reports, thus there is currently insufficient data to support their use. Since this is a small group of patients, it is unlikely that sufficient numbers will ever be recruited for these studies; thus it is probable that drugs will be tried on an individual patient basis. The order in which they are attempted is unclear, but it would be sensible to try the least invasive medication with the least adverse effects first, moving on to more potent, but more toxic drugs if that treatment fails.

"CF asthma": what is it and what do we do about it?

The diagnosis of "CF asthma" is problematic and it is difficult to determine which patients have a combination of CF and asthma and which have asthma like symptoms caused by inflammation of the CF lung. This may not matter, however; the relevance lies in the possible approaches to treatment.

Subcutaneous terbutaline in children with chronic severe asthma

A continuous subcutaneous infusion of terbutaline (CSIT) was used to treat 8 children with chronic severe asthma who continued to experience frequent symptoms, despite treatment with regular oral prednisolone. Five patients experienced a symptomatic improvement from CSIT, leading to a reduction in regular medication. Three patients did not experience any lasting benefit from CSIT. The most common side effects were related to the infusion site (bruising and local infection). CSIT may lead to an improvement in symptoms and a reduction in oral steroid dose in selected children with chronic severe asthma. These initial findings support the need for further controlled studies to evaluate the use of CSIT in severe childhood asthma.