Probit analysis applied to the allergen dose-response curve: a method for epidemiologic surveys

Filaggrin null mutations are associated with increased asthma severity in children and young adults

BACKGROUND

Filaggrin is a key protein involved in skin barrier function. Filaggrin (FLG) null mutations are important genetic predisposing factors for atopic disease.

OBJECTIVE

To study the role of FLG null alleles in the clinical phenotype in children and young adults with asthma.

METHODS

FLG mutations R501X and 2282del4 were assayed in 874 subjects 3 to 22 years old with asthma from Tayside. Lung function and disease severity were also studied.

RESULTS

The filaggrin mutations were significantly associated with greater disease severity for asthma. Independent of eczema, mean FEV(1)/forced vital capacity of FLG wild-type individuals differed from those carrying either FLG null allele (0.89 vs 0.86; P = .012). Individuals bearing FLG null alleles were more likely to be prescribed increased medication (chi(2) = 10.3; P = .001), with the homozygote null individuals having an odds ratio of 6.68 (95% CI, 1.7-27.0; P = .008) for being prescribed long-acting beta-agonists in addition to inhaled steroids. FLG null alleles were also associated with increased rescue medication use (P = .004). Individuals with asthma and with FLG null alleles were more likely to have eczema, and individuals with eczema tended to have more severe asthma; however, the association of FLG null alleles with all markers of asthma disease severity was similar in children with and without eczema.

CONCLUSION

FLG mutations are associated not only with eczema-associated asthma susceptibility but also with asthma severity independent of eczema status.

CLINICAL IMPLICATIONS

FLG status influences controller and reliever medication requirements in children and young adults with asthma.

Prevalence of atopy in students from Málaga, Spain

BACKGROUND

Epidemiologic studies are necessary to determine the prevalence of allergic diseases. This varies widely depending on allergen preparations and patients studied.

OBJECTIVE

To investigate the prevalence of atopic disease, skin test reactivity, total and specific IgE to common allergens, and other variables in a sample of students from Málaga, southern Spain.

METHODS

Three hundred sixty-five students (age 17.9 +/- 1.18) were interviewed by an allergist. Skin prick tests were performed with Dermatophagoides pteronyssinus, Artemisia vulgaris, Plantago lanceolata, Chenopodium album, Olea europaea, Phleum pratense, Parietaria judaica, Cynodon dactylon, Alternaria tenuis, and cat dander. Total and specific IgE to D. pteronyssinus, Olea, and Parietaria were determined.

RESULTS

Of all subjects studied, 19.9% suffered from rhinoconjunctivitis, 4.1% rhinoconjunctivitis plus asthma, 3.1% asthma alone, and 0.8% atopic dermatitis; 46.4% had a positive skin test to at least one allergen (28.2% to D. pteronyssinus, 20.4% to Olea, 13.8% to Phleum); and 43% had total IgE > 100 kU/L and 44.7% a family history of atopy. Allergic symptoms were strongly associated with skin test positivities and family allergic history. Patients with asthma or skin prick test positive had higher total IgE values than others (P < .01). There was a significant correlation between specific IgE values and wheal size in skin test.

CONCLUSIONS

Our findings confirm the high prevalence of atopic diseases, and the close relationship of skin tests reactivity (or presence of specific IgE) to allergens with symptoms of asthma and rhinitis. The presence of a family history of allergic diseases influences the development of positive skin tests and atopic illness. Dermatophagoides pteronyssinus and pollen of Olea europaea were found to be the most common allergens.

Detection of cytokines and their cell sources in bronchial biopsy specimens from asthmatic patients. Relationship to atopic status, symptoms, and level of airway hyperresponsiveness

This study evaluated immunoreactivity for several cytokines in bronchial tissue of asthmatic patients and related this to the clinical and functional characteristics. Patients were allocated into two different groups on the basis of their atopic status (atopic and nonatopic), with two subgroups of symptomatic and asymptomatic subjects in each. Five healthy volunteers were tested as control subjects. After clinical and functional assessment, all of the subjects underwent bronchoscopy. Several biopsy specimens were obtained for immunohistochemical and immunoelectron microscopic evaluation. Symptomatic asthmatic subjects had increased expression of immunoreactive interleukin (IL) 1 beta, IL-2, IL-3, IL-5, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor alpha (TNF alpha) when compared to the asymptomatic patients or normal control subjects. The cell sources of IL-1 beta were monocytes and dendritic cells in atopic patients and monocytes alone in nonatopic asthmatic subjects. The CD4+ T lymphocytes from atopic asthmatic subjects predominantly expressed IL-3, IL-4, IL-5, and GM-CSF immunoreactivity, whereas CD4+ T cells from nonatopic patients predominantly expressed IL-2, IL-3, and IL-5, and GM-CSF immunoreactivity. Mast cells showed immunoreactivity for TNF alpha, IL-3, IL-5, and GM-CSF. Immunostaining for TNF alpha and GM-CSF was also detected in bronchial epithelial cells and monocytes. Tissue eosinophilia and the level of airway hyperresponsiveness more closely correlated with IL-5 immunoreactivity in atopic asthmatic subjects and with IL-2 and GM-CSF immunoreactivity in nonatopic patients.

Bronchoconstrictive responses to inhaled ultrasonically nebulized distilled water and airway inflammation in asthma

Twenty-two asthmatic patients with a range of airway hyperresponsiveness to methacholine underwent a bronchial challenge with ultrasonically nebulized distilled water (UNDW). The presence of positive responses to this stimulus was related to the extent of airway inflammation, as assessed by histochemical and immunohistochemical evaluation of bronchial biopsy specimens. Twelve patients had airflow obstruction during distilled water inhalation and they showed more severe disease than subjects with no response, as demonstrated by the higher degree of nonspecific bronchial hyperresponsiveness (p < 0.01), higher variability of peak expiratory flow rates (p < 0.01), symptom scores (p < 0.01), and daily use of bronchodilators (p < 0.01). Those patients also had increased numbers of mast cells and eosinophils (p < 0.01) and increased percentage of bronchial epithelial cells expressing endothelin 1 immunoreactivity (p < 0.01). Thus, positive responses to inhaled UNDW reflect the bronchial hyperresponsiveness consistent with moderate to severe asthma and may be due to the release of mediators with bronchoconstrictive properties from inflammatory cells or activated resident cells or both.

Intraepithelial dendritic cells and selective activation of Th2-like lymphocytes in patients with atopic asthma

This study examines the distribution of intraepithelial dendritic cells in eight atopic patients with symptomatic asthma and their ability to induce activation of autologous T lymphocytes in vitro. All subjects were sensitized to Dermatophagoides pteronyssinus. The incubation of asthmatic epithelial cells and dendritic cells with autologous resting CD4-positive T cells and purified extracts of D pteronyssinus induced T cell activation and release of high levels of interleukin-4 (IL-4) and interleukin-5 (IL-5). The antigen-presenting activity of dendritic cells was potentiated by epithelial cell-derived granulocyte-macrophage colony-stimulating factor (GM-CSF), since an antibody against GM-CSF reduced it. Circulating monocytes of the two groups of donors were equally effective in promoting selective activation of IL-4- and IL-5-producing T cells. Thus, an interaction between dendritic cells and allergens may favor local activation of CD4-positive T cells with Th2-like function in atopic asthmatic subjects, thereby promoting the expression of the disease.

Cytokine mRNA profile and cell activation in bronchoalveolar lavage fluid from nonatopic patients with symptomatic asthma

Recent studies have indicated that airway inflammation in atopic asthma is characterized by T-cell activation and local eosinophilia, but it is unknown whether this also applies to nonatopic asthma. In this study, the cytokine mRNA profile and activation status of inflammatory cells in bronchoalveolar lavage fluid (BALF) of eight nonallergic patients with symptomatic asthma and eight nonallergic healthy controls were compared using the message amplification phenotyping (MAPPing) with the polymerase chain reaction (PCR) procedure and immunocytochemical evaluation. Asthmatics had an increasing number of inflammatory cells in BALF, including activated eosinophils (EG2-positive) (p less than 0.001) and activated T cells (CD25-positive) (p less than 0.001). Activated T cells from five of the eight asthmatic patients and from one control subject expressed high levels of interleukin 5 (IL-5) and granulocyte-macrophage colony-stimulating factor (GM-CSF). All the asthmatic patients had increased numbers of monocytes in their BALF (p less than 0.002) and those cells invariably showed increased expression of interleukin 1 beta (IL1 beta) transcripts. In five patients they also expressed appreciable levels of IL-6 and GM-CSF mRNA. IL-5 and GM-CSF can induce local activation of eosinophils, and IL-1 beta and IL-6 are known to promote T-cell activation and proliferation. Thus, there is an increased production of cytokines with inflammatory properties in the airways of patients with nonatopic symptomatic asthma, which may contribute to the persistence of inflammation, and monocytes and activated T cells are important sources of these cytokines.

Levels of endothelin in the bronchoalveolar lavage fluid of patients with symptomatic asthma and reversible airflow obstruction

We have previously demonstrated that human bronchial smooth muscle cells possess a single class of specific binding sites for the potent bronchoconstrictive peptide, endothelin 1, and that human bronchial epithelial cells constitutively release an endothelin-like material in culture, which binds to smooth muscle cell receptors with a kinetic analogous to that observed with the authentic peptide. To evaluate the potential role of endothelin in the pathogenesis of asthma, we examined in this study the release of endothelin in the airways of six patients with asthma, both at the time when they were symptomatic and had reversible airflow obstruction and during the remission phase of the disease induced by treatment. Five normal volunteers and five patients with chronic bronchitis and airflow obstruction unaffected by bronchodilators were tested as control subjects. The release of endothelin in airway mucosa was assessed by RIA with the bronchoalveolar lavage fluid recovered during bronchoscopy. Patients with asthma had increased amounts of immunoreactive endothelin in bronchoalveolar lavage fluid than normal control subjects or subjects with chronic bronchitis (p less than 0.05) in absence of any significant alteration in the levels of circulating peptide. Treatment of patients with asthma with oral corticosteroids and inhaled beta-agonists for 15 days resulted in improvement of airflow obstruction and in more than threefold reduction in the contents of endothelin in lavage fluid. Our findings indicate that the potent bronchoconstrictive substance, endothelin, may contribute to the pathogenesis of airflow obstruction in asthma.