Blood eosinophils, eosinophil-derived proteins, and leukotriene C4 generation in relation to bronchial hyperreactivity in children with atopic dermatitis

Blood eosinophils as a marker of likely corticosteroid response in children with preschool wheeze: time for an eosinophil guided clinical trial?

Childhood wheezing is common particularly in children under the age of 6 years and in this age group is generally referred to as preschool wheezing. Particular diagnostic and treatment uncertainties exist in these young children due to the difficulty in obtaining objective evidence of reversible airways narrowing and inflammation. A diagnosis of asthma depends on the presence of relevant clinical signs and symptoms and the demonstration of reversible airways narrowing on lung function testing, which is difficult to perform in young children. Few treatments are available and inhaled corticosteroids are the recommended preventer treatment in most international asthma guidelines. There is, however, considerable controversy about its effectiveness in children with preschool wheeze and a corticosteroid responder phenotype has not been established. These diagnostic and treatment uncertainties in conjunction with the knowledge of corticosteroid side effects, in particular the reduction of growth velocity, have resulted in a variable approach to inhaled corticosteroid prescribing by medical practitioners and a reluctance in carers to regularly administer the treatment. Identifying children who are likely responders to corticosteroid therapy would be a major benefit in the management of this condition. Eosinophils have emerged as a promising biomarker of corticosteroid responsive airways disease, and evaluation of this biomarker in sputum has successfully been employed to direct management in adults with asthma. Obtaining sputum from young children is time consuming and difficult, and it is hard to justify more invasive procedures such as a bronchoscopy in young children routinely. Recently, in children, interest has shifted to assessing the value of less invasive biomarkers of likely corticosteroid response and the biomarker 'blood eosinophils' has emerged as an attractive candidate. The aim of this review was to summarize the evidence for blood eosinophils as a predictive biomarker for corticosteroid responsive disease with a particular focus on the difficult area of preschool wheeze.

Local and systemic immunological parameters associated with remission of asthma symptoms in children

The immunological and clinical parameters that are associated with asthma remission are poorly understood. The cytokine and local mediator changes associated with the resolution of asthma symptoms were examined in three groups of subjects 12-18 years of age (n = 15 in each group): (a) continuing asthma group (CA) who had persistent symptoms since early childhood, (b) an age, sex and atopic status-matched group who had persistent symptoms in early childhood but in whom these had resolved (RA), and (c) a non-atopic, non-asthmatic control group. Clinical parameters, sputum cell counts, peripheral blood mononuclear cell (PBMC) cytokine production and activation marker expression were determined. All of the CA had methacholine airway hyperresponsiveness compared with only half of the RA subjects. The CA showed elevated numbers of eosinophils and increased ECP and IL-5 in sputum, which were not observed in the RA. PBMC cytokine studies revealed increased production of the type 1 cytokines IL-12, IFN-γ and TNF-α in the CA group compared with the RA group, under a range of activation conditions, however, the production of IL-4 and IL-5 were unchanged. These findings suggest that decreased type 1 cytokine expression as well as decreased eosinophilic inflammation is associated with the resolution of asthma symptoms.

Therapeutic Hotline: Cysteinyl leukotriene receptor antagonist montelukast in the treatment of atopic dermatitis

Leukotrienes are potent proinflammatory mediators derived from arachidonic acid through the 5-lipoxygenase pathway. Experimental data suggest a role for cysteinyl leukotrienes in the pathogenesis of atopy giving a rationale for its use in asthma, allergic rhinitis, and chronic urticaria management. A few clinical observations and small trials suggest that montelukast may be used in an adjunctive manner as an effective therapeutic option for all age categories affected by moderate-to-severe atopic dermatitis. Our own observations proved that montelukast as a prospective corticosteroid-sparing option in the complex therapeutic strategy of corticosteroid-dependent atopic dermatitis patients, even in the severe erythrodermic cases.

A double-blind, placebo-controlled trial of montelukast in adult atopic eczema

BACKGROUND

Montelukast is an antagonist of cys-leukotriene receptors used mainly in the treatment of asthma- and seasonal-allergic rhinitis. Initial reports concerning the use of montelukast in atopic dermatitis (AD) have been encouraging, although not consistent.

OBJECTIVES

We have undertaken a randomized, double-blind, parallel-group, placebo-controlled trial to investigate further the efficacy of montelukast in the treatment of atopic eczema.

METHODS

Following a screening visit, subjects received placebo treatment for 2 weeks in a single-blind phase, followed after visit 2 by an 8-week, double-blind period of treatment with montelukast 10 mg daily or placebo. Subjects were patients aged 16-60 years under our care for treatment of AD of moderate severity, defined by a six-area, six-sign atopic dermatitis (SASSAD) score in the range 12-50. Response to treatment was assessed by investigators and by subjects using a seven-point scale, with response defined as marked improvement or better. In addition, the SASSAD score was used to monitor the severity of clinical signs. The proportion of skin involved was estimated and visual analogue scales were used to record the severity of pruritus and sleep disturbance. Topical corticosteroid usage was recorded using a five-point scale. Adverse events were recorded.

RESULTS

Sixty subjects were recruited and 54 completed the study. The treatment groups were well matched for disease severity at baseline (SASSAD scores were 25 and 29 in the montelukast and placebo groups, respectively). There were no significant differences between the treatment groups in any of the parameters used to assess treatment response. The improvement in mean SASSAD score from baseline (visit 2) to the end of treatment was marginally superior in the placebo group, 1.41 points on montelukast vs. 1.76 on placebo, a difference of 0.35 (95% confidence interval -6.1 to 6.8). Adverse events were generally of a mild nature except for a brief septicaemic illness in one subject receiving montelukast.

CONCLUSIONS

The data do not support previous reports of efficacy of montelukast in treatment of AD.

Increased levels of urinary leukotriene E4 in children with severe atopic eczema/dermatitis syndrome

BACKGROUND

Leukotrienes are thought to play a role in the pathogenesis of atopic eczema/dermatitis syndrome (AEDS). Urinary leukotriene E4 (U-LTE4) is a marker of whole-body cysteinyl-leukotriene production.

AIMS OF THE STUDY

To evaluate the role of leukotrienes in children with AEDS by measuring levels of U-LTE4, and to evaluate whether levels of U-LTE4 may reflect disease activity and allergic sensitization in AEDS.

METHODS

U-LTE4 was measured by enzyme-linked immunosorbent assay in 87 children with mild (n=32), moderate (n=34) and severe (n=21) AEDS, as well as in 72 nonatopic healthy controls. Fifty-eight of the children with AEDS were sensitized to common allergens, and 29 were not.

RESULTS

Levels of U-LTE4 were higher in children with severe AEDS (140; 66-166 microg/mmol creatinine, median; quartiles) than in controls (52; 30-90, P <0.05), whereas levels of U-LTE4 in moderate and mild disease were similar to controls. U-LTE4 levels were similar in children with or without sensitization to common allergens, but severe AEDS children with sensitization had higher levels of U-LTE4 than those without sensitization.

CONCLUSION

The results suggest a role for leukotrienes in the pathogenesis of severe AEDS, and may support a role for leukotriene-antagonists in the treatment of this disorder. Levels of U-LTE4 may reflect the disease severity and sensitization to allergens in AEDS.

Eosinophils and atopic dermatitis

In spite of the progress regarding the description of immunological phenomena associated with atopic dermatitis (AD), the pathogenesis of this disease still remains unclear. The presence of eosinophils in the inflammatory infiltrate of AD has long been established. Eosinophil numbers as well as eosinophil granule protein levels in peripheral blood are elevated in most AD patients and appear to correlate with disease activity. Moreover, eosinophil granule proteins, which possess cytotoxic activity, are deposited in the skin lesions. These observations indicate a role of eosinophils in the pathogenesis of AD. Furthermore, AD is associated with increased production of T helper 2 cytokines including interleukin (IL)-5, which specifically acts on eosinophils, resulting in accelerated eosinophilopoiesis, chemotaxis, cell activation, and delayed apoptosis. Therefore, IL-5 is an interesting target for experimental therapy in this inflammatory disorder of the skin. Such studies might result in new insights into the pathogenetic role of eosinophils in AD.

Urinary leukotriene levels are increased during exacerbation of atopic eczema/dermatitis syndrome. Relation to clinical status

BACKGROUND

Leukotrienes are potent mediators of allergic inflammation and their role in the pathogenesis of allergic disorders, particularly asthma, is well established. Their importance in the pathogenesis of atopic eczema/dermatitis syndrome (AEDS) is still unclear. We aimed to compare urinary cysteinyl leukotriene (Cys-LT) levels during exacerbation and remission of AEDS in relation to clinical status, IgE levels, and eosinophil counts.

METHODS

Urinary Cys-LTs were measured by direct enzyme immunoassay in 17 adult patients with AEDS and in 17 healthy controls in whom atopy had been excluded. Cys-LTs were compared during exacerbation and remission of AEDS in relation to the clinical status measured by SCORAD. Total IgE levels were measured by enzyme-linked immunoassay (ELISA).

RESULTS

Mean clinical score during the exacerbation was 64.3 +/- 3.1 and during remission 22.4 +/- 4 (P < 0.01). Cys-LTs levels were significantly higher during the exacerbation of AEDS than in the control group (230.9 +/- 20.8 vs 123.2 +/- 9.9 pg/mg creatinine; P < 0.005). During the remission, the difference between AEDS patients and the control group was not significant (96.3 +/- 8.7 vs 123.2 +/- 9.9 pg/mg creatinine; P = 0.8). During AEDS exacerbation Cys-LTs levels were significantly correlated with the clinical status (rS = 0.73, P < 0.01) and with eosinophil counts (r = 0.86; P < 0.01) but not with the duration of the disease, age of patients, or IgE levels.

CONCLUSIONS

Our results point to enhanced biosynthesis of Cys-LTs during the AEDS exacerbations. Inflammatory cells, e.g. eosinophils are the most probable source of Cys-LTs. A strong correlation between Cys-LT levels and clinical status may in part explain preliminary clinical observations of efficacy of leukotriene antagonists in alleviating symptoms of AEDS.

Allergen sensitization through the skin induces systemic allergic responses

The skin is a unique immunologic organ that acts as an interface between the external environment and the systemic immune response. As such, it may react directly with allergens that are applied epicutaneously, thereby influencing the systemic allergic response. It is well known that atopic dermatitis (frequently in association with food allergy) predates the development of asthma and allergic rhinitis by several years. The possibility that atopic dermatitis may influence the course of asthma is suggested by several interesting observations. First, children with atopic dermatitis and positive skin tests to allergens frequently have more severe asthma than asthmatic children without atopic dermatitis. Second, because total serum IgE is strongly associated with the prevalence of asthma, it raises the interesting question of whether allergen sensitization through the skin predisposes to more severe and persistent respiratory disease because of its effects on the systemic allergic response. Indeed, epicutaneous sensitization of mice to a protein antigen induces both a localized allergic dermatitis and hyperresponsiveness to methacholine, which suggests that epicutaneous exposure to antigen in atopic dermatitis may enhance the development of asthma. Finally, systemic immune activation in atopic dermatitis is supported by the observation that these patients have increased numbers of circulating activated T(H)2 cells, eosinophils, macrophages, and IgE. Many of the markers of leukocyte activation have been shown to correlate with the severity of atopic dermatitis disease. This systemic activation might facilitate local infiltration of primed T cells, eosinophils, and macrophages into the respiratory mucosa after inhalation of allergen in genetically predisposed hosts. The systemic aspects of atopic dermatitis, with an emphasis on respiratory effects, are summarized.

Urinary eosinophil protein X and serum eosinophil cationic protein in infants and young children with atopic dermatitis: correlation with disease activity

BACKGROUND

Eosinophil cationic protein (ECP) and eosinophil protein X (EPX) or eosinophil-derived neurotoxin (EDN) are released by eosinophil granulocytes in allergic diseases. Serum ECP (s-ECP) levels have been correlated with disease activity in atopic dermatitis (AD) in adults and young patients, and high urinary EPX (u-EPX) levels in asthmatic patients seem to reflect active disease. A relationship between AD severity and u-EPX concentration in young children has not been previously studied.

OBJECTIVE

This study was performed to evaluate whether the severity of AD in infants and young children was correlated with s-ECP and u-EPX levels.

METHODS

Fifty-four infants and children (mean age, 17.7 months; range, 4-48 months) with AD and without other allergic conditions were evaluated. The severity of AD was measured by using the SCORAD index. S-ECP, serum total IgE, serum-specific IgE for common allergens, and peripheral blood eosinophil counts (PBECs) were determined. In forty-two children u-EPX was also measured. Seven age-matched control patients underwent the same determinations.

RESULTS

S-ECP and u-EPX were significantly higher in children with AD than in control children (mean, 23.9 vs 3.5 microg/dL [P <.001] and 57.7 vs 6.0 microg/mmol creatinine [P <.001]). A significant correlation was found between SCORAD and s-ECP (P =.002), u-EPX (P =.01), and PBECs (P =.01) and between symptom index and uEPX (P =.0004). PBECs were strongly correlated to s-ECP and u-EPX (P <.0001). However, 5 patients with moderate and severe AD (11.9%) showed low levels of s-ECP, u-EPX, and PBECs.

CONCLUSION

S-ECP and u-EPX were useful markers of AD activity in infants and young children. When taken together, the two determinations could give more information about the clinical course of the illness. Some patients seemed to have clinical exacerbations without an involvement of eosinophils and their products.