Hajime Katsumata

Serum measurement of thymus and activation-regulated chemokine/CCL17 in children with atopic dermatitis: elevated normal levels in infancy and age-specific analysis in atopic dermatitis

Elevated blood levels of thymus and activation‐regulated chemokine (TARC)/CCL17 have been observed in atopic dermatitis (AD) and may serve as a new biomarker for AD. However, the normal levels, especially in children, have not been well determined. We sought to establish an efficient enzyme‐linked immunosorbent assay (ELISA) with a wide range of detection that would be suitable for measurement of serum TARC/CCL17 and to determine the normal ranges of this chemokine in different age groups and its diagnostic usefulness for AD. A sensitive specific ELISA for TARC/CCL17, which we previously reported, was modified to accommodate the wide range of TARC/CCL17 values often found in sera. Twenty‐seven children with AD under 6 yr of age and 25 age‐matched normal non‐atopic controls, and 18 patients with AD and 27 controls who were 6 yr and older were enrolled. The severity of AD was evaluated using the SCORAD index. The serum levels of TARC/CCL17 were measured with the ELISA, and the serum levels of IP‐10/CXCL10 were also measured. With the novel ELISA system, the assayable range of TARC/CCL17 was 14–8000 pg/ml, and the coefficient of variation at various concentrations ranged from 2.3% to 5.0%. The serum levels of TARC/CCL17 in normal individuals were significantly higher in young children, especially in the age group of 0–1 yr. The cut‐off values of TARC/CCL17 for the diagnosis of AD were 1431 pg/ml for 0–1 yr group, 803 pg/ml for 2–5 yr group and 510 pg/ml for the 6 yr and older group, with high sensitivity and specificity of 0.83 and 0.93, 0.83 and 0.92, 0.85 and 0.96, respectively. The magnitude of the decrease in the SCORAD index after treatment with topical steroids correlated significantly with the decrease in serum TARC/CCL17. There was no difference in the serum levels of IP‐10/CXCL10 between AD and the controls. The TARC/CCL17:IP‐10/CXCL10 ratio tended to be higher in the control children aged 0–1 yr than in those aged 2–5 yr. The serum level of TARC/CCL17 reflects the severity and therapeutic response in AD. The high normal levels in infants should be taken into account when assaying TARC/CCL17.

High prevalence and young onset of allergic rhinitis in children with bronchial asthma

Bronchial asthma and allergic rhinitis often co‐exist, and rhinitis is a major risk factor for the development of asthma. However, the reported incidence of allergic rhinitis in asthmatic children varies widely. The aim of this study was to elucidate the incidence of allergic rhinitis, the onset age of chronic upper and lower airway symptoms, and the correlation of these two symptoms in asthmatic children. A cohort of 130 consecutive children (ages 2–10) with asthma was evaluated. A questionnaire regarding upper and lower airway symptoms was filled out by the parents. Objective diagnosis of allergic rhinitis was also made on the basis of rhinoscopy, nasal cytology, nasal challenge, and specific serum IgE (CAP‐RAST). Persistent nasal symptoms were present in 83.8% of the asthmatic children. The incidence of allergic rhinitis was 77.7% based on the objective findings. The mean onset age of asthma was 2.8 yr, and that of rhinitis was 2.9 yr. Nasal symptoms started as early as the first year of life in 8.9% of the children. In children with comorbid asthma and allergic rhinitis, rhinitis preceded in 33.7%, asthma preceded in 31.7%, and both started in the same year in 26.7%. In 7.9%, rhinitis was asymptomatic. Concomitant exacerbation of the upper and lower airways occurred in 34.6% of the total 130 children. These results demonstrate that allergic rhinitis manifested early in life in the majority of the asthmatic children. Persistent nasal symptoms in infancy may point to subsequent development of asthma and possible early intervention.

House dust mite extract induces interleukin-9 expression in human eosinophils.

BACKGROUND Eosinophils play a pivotal role in allergic inflammation. Recent evidence suggests that they not only function as terminal effector cells but have potential to interact with allergen and initiate immune responses. We investigated cytokine production from eosinophils through direct interaction with a major allergen, house dust mite (HDM) . METHODS Purified eosinophils from HDM-sensitized or non-sensitized donors were cultured with HDM extract or lipopolysaccharide (LPS) for 18 or 40 h. A panel of cytokine gene expression in eosinophils was examined by means of real-time RT-PCR. Released cytokines in the culture supernatants were assessed with a specific ELISA. In some experiments, HDM was pretreated with protease inhibitors, then added to the culture. Cytokines tested for gene expression were interleukin (IL)-2, 4, 6, 7, 8, 9, 10, 11, 12, 13, 16,17, 18, TGF-beta1 and GM-CSF,. RESULTS LPS induced small enhancement of GM-CSF gene expression at 18 h. At 40 h, HDM induced about 60-fold enhancement of IL-9 gene expression. IL-9 protein was also detected in the culture supernatants at 60 h. Those reactions were observed regardless of HDM sensitization status of the donors. HDM-induced IL-9 expression was completely inhibited with a serine protease inhibitor, AEBSF, not with a cysteine protease inhibitor, E-64. CONCLUSIONS Accumulated eosinophils in the airways in asthma may directly react with HDM and produce IL-9 to further promote Th2-type immune responses. Protease-activated receptor 2, a ligand for serine proteases, which contained in HDM, may be involved in the reaction.

Leukotriene D4 induces production of transforming growth factor-β1 by eosinophils

Eosinophils may play an important role in the pathogenesis of airway remodeling in asthma through the production of various fibrogenic cytokines such as transforming growth factor-β1 (TGF-β1). Cysteinyl leukotrienes are also suggested to be involved in remodeling with their potential to induce proliferation of airway smooth muscle cells. Since massive eosinophil infiltration and the release of cysteinyl leukotrienes in airway secretions are often seen in asthma, we hypothesized that cysteinyl leukotrienes may be involved in airway remodeling through induction of TGF-β1 from eosinophils. Peripheral blood eosinophils were cultured with leukotriene D4 (LTD4) and/or interleukin-5 (IL-5) or granulocyte colony-stimulating factor (GM-CSF) for 16 h and gene expression of TGF-β1 was quantified with real-time PCR. A combination of LTD4 and IL-5 or LTD4 and GM-CSF synergistically induced TGF-β1 expression in eosinophils although stimulation with single factor, LTD4, IL-5 or GM-CSF did not induce the gene expression. LTD4 also induced significant gene expression in eosinophils cultured in an intercellular adhesion molecule-1-coated plate. The results suggested that CysLTs stimulate eosinophils to induce TGF-β1 production in allergic inflammation where IL-5 and GM-CSF are abundant and may be involved in the pathogenesis of airway remodeling.