Effect of an air cleaner with electrostatic filter on the removal of airborne house dust mite allergens

Purpose

The effects of air cleaners on the removal of airborne indoor allergens, especially house dust mites (HDM), are still controversial. The objective of this study is to evaluate the effect of an air cleaner with an electrostatic filter on the removal of airborne mite allergens.

Materials and Methods

A dried HDM culture medium that contained mite body particles and excretions was dispersed in a chamber equipped with an electrostatic air cleaner. The number of airborne particles was recorded continuously by a dust spectrometer for 60 minutes. Airborne particles in the chamber were collected on a sampling filter at a flow rate of 10 L/min and the Der f 1 concentration in the filter extracts was measured by two-site ELISA.

Results

The air cleaner efficiently removed airborne HDM particles. The air cleaner removed airborne HDM particles (size 2-12.5 µm) 11.4 ± 2.9 fold (cleaner operating for 15 minutes), 5.4 ± 0.7 fold (cleaner operating for 30 minutes), and 2.4 ± 0.2 fold (cleaner operating for 60 minutes) more than the removal of HDM particles by natural settle down. Removal kinetics differed according to the particle size of the airborne particles. The air cleaner decreased the concentration of Der f 1 in the extraction of airborne particles collected on the air sampling filter by 60.3%.

Conclusion

The electrostatic air cleaner can remove airborne HDM allergens and may be useful as a supplementary environmental control tool for HDM sensitized respiratory allergic patients.     

Effects of house dust mite avoidance measures on Der p 1 concentrations and clinical condition of mild adult house dust mite-allergic asthmatic patients, using no inhaled steroids.

BACKGROUND: Exposure to house dust mite (HDM) allergens often results in worsening of asthma. Therefore, avoidance of exposure to HDM allergens is often proposed. Unfortunately, the most effective and feasible avoidance strategy is still not completely assessed. Consequently, we investigated the effects of a combined HDM avoidance strategy on HDM allergen concentrations and clinical condition of allergic, mild asthmatic, patients using no inhaled steroids. METHODS: Asthmatic patients, allergic to HDM, using no inhaled corticosteroids, were randomly allocated to an active (n = 76) or a placebo allergen-avoidance group (n = 81). Avoidance measures consisted of applying Acarosan(R) (placebo: water) to the living room and bedroom floors, and the use of HDM-impermeable covers for mattresses and bedding (placebo: cotton covers for mattresses only). Effects on allergen concentrations (Der p 1), FEV1, bronchial hyperresponsiveness, peak flow parameters and asthma symptom scores were studied during 20 weeks and controlled for the allergic status of the patients. RESULTS: The active covers reduced Der p 1 concentrations to 9.4% (P = 0.0001), and were always significant lower than in the placebo group (P = 0.0002). Acarosan(R) resulted in slight but significant decreases (twofold, P = 0.0001), both on living room and bedroom floors, but concentrations were never significantly lower than the placebo group. Although the combined avoidance strategy resulted in a considerable reduction in allergen load in the active group, no differences were seen between the two groups in any of the clinical parameters during the follow-up period in this group of allergic asthmatics, using no inhaled corticosteroids. Corrections for the allergic status did not alter these results. CONCLUSIONS: The combined avoidance strategy was effective in reducing HDM allergen concentration. This was especially achieved by the allergen-impermeable covers, while the effects of Acarosan(R) were only marginal. However, this allergen reduction was not reflected in a convincing improvement in clinical condition in this group of mild allergic asthmatics, using no inhaled steroids. Perhaps, a longer follow-up period would have resulted in more pronounced effects.     

Clinical benefits of treatment with SQ house dust mite sublingual tablet in house dust mite allergic rhinitis

Treatment with SQ (standardised quality) house dust mite sublingual tablet for 1 year resulted in a decreased probability of having an allergic rhinitis (AR) exacerbation day (from 11% [placebo] to 5% [SQ house dust mite sublingual tablet]) and an increased probability of having a mild AR day (from 16% [placebo] to 34% [SQ house dust mite sublingual tablet]).     

Molecular characterization of Der p 10: a diagnostic marker for broad sensitization in house dust mite allergy

Background Tropomyosins represent clinically relevant seafood allergens but the role of mite tropomyosin, Der p 10, in house dust mite (HDM) allergy has not been studied in detail. Objective To express and purify a recombinant Der p 10 with equivalent IgE reactivity as natural Der p 10 and to evaluate its IgE reactivity and allergenic activity in HDM‐allergic patients. Methods rDer p 10 was expressed in Escherichia coli, purified and characterized by mass spectrometry and circular dichroism. It was tested for IgE reactivity in 1322 HDM‐allergic patients. Detailed IgE‐reactivity profiles to six HDM allergens (Der p 1, 2, 5, 7, 10, 21) were established for subgroups of Der p 10‐positive and ‐negative patients. The allergenic activity of rDer p 10 was evaluated in basophil degranulation experiments. Results rDer p 10 is an α‐helical protein sharing IgE epitopes with nDer p 10. It is recognized by 15.2% of HDM‐allergic patients. Der p 10‐negative patients were primarily sensitized to Der p 1 and/or Der p 2, whereas Der p 10‐positive patients reacted to several other HDM allergens besides the major allergens (Der p 1, Der p 2) or showed a rather selective Der p 10 reactivity. The allergenic activity of Der p 10 was generally low but patients could be identified who suffered from clinically relevant HDM allergy due to Der p 10 sensitization. Conclusion and Clinical Relevance Der p 10 may be a diagnostic marker for HDM‐allergic patients with additional sensitization to allergens other than Der p 1 and Der p 2. Such patients may require attention when allergen‐specific immunotherapy is considered. Cite this as: Y. Resch, M. Weghofer, S. Seiberler, F. Horak, S. Scheiblhofer, B. Linhart, I. Swoboda, W. R. Thomas, J. Thalhamer, R. Valenta and S. Vrtala, Clinical & Experimental Allergy, 2011 (41) 1468–1477.     

The role of house dust mite elimination in the management of childhood asthma: an unresolved issue

Indoor allergens are likely to be direct environmental causes of asthma and mite exposure, and sensitization is the most important environmental risk factor for childhood asthma in temperate zones. Analagous to occupational asthma, allergen avoidance in asthmatic children sensitized and exposed to mite allergens is associated with a reduction in airway hyperresponsiveness and symptoms associated with improvement in lung function. The long-term effect of this strategy needs to be prospectively evaluated considering both the timing and duration of exposure, as well as the timing and duration of removal. In order to be successful, it is important to achieve and maintain a major reduction on allergen levels, for a long period of time.     

Constitutive nitric oxide synthase gene polymorphisms and house dust mite respiratory allergy in an Algerian patient group

Genetic polymorphisms in neuronal nitric oxide synthase (NOS1) and calmodulin-dependent endothelial NOS (NOS3) genes are known to influence the course of allergic respiratory disorders. We investigated the role of NOS1 -84 G-->A and NOS3 -786 T-->C, 894 G-->T and 27 base pair (bp) repeat polymorphisms in 125 patients suffering from asthma and/or rhinitis and monosensitized against Dermatophagoides pteronyssinus (Dpter) and 111 controls from Algeria. We found a higher frequency of the -786 C NOS3 allele in patients than in controls [corrected P value (Pc) = 0.04], especially in female cases (Pc = 0.02) and that the 'ab' genotype of the 27-bp polymorphism was significantly associated with specific immunoglobulin E production against Dpter (P = 0.006). This study brings further support for the participation of NOS3 gene polymorphism in the pathogenesis of respiratory allergic disorders.     

Basophil histamine release in the diagnosis of house dust mite and dander allergy of asthmatic children

The aim of the study is to compare the glass fibre-based basophil histamine release test with skin test (Phazet), RAST (Phadebas) and bronchial provocation test in children with allergic asthma. The study comprised 68 selected children with a case history of extrinsic allergic asthma to danders (cat and dog) and house-dust mite. Skin prick test, RAST, and histamine release were performed in all children and the bronchial provocation test was used as a reference of "true allergic asthma". A total of 81 allergen bronchial challenges were performed and 44 children experienced 49 positive provocations. In 2.9% (2/68) of the children histamine release could not be performed due to technical difficulties (low histamine release with anti-IgE). Concordances in the range 76-87% were observed with no significant difference between the tests. The highest concordance (87%) was found between histamine release and bronchial provocation test followed by skin prick test vs bronchial provocation (84%) and RAST vs bronchial provocation (80%). The sensitivity and specificity were calculated for each test. All tests showed sensitivities in the range 90-94% and no significant difference between them was observed. The specificity of histamine release, skin prick test, and RAST was 0.78, 0.69, and 0.63, respectively. The specificity of histamine release was better than RAST demonstrated by 95% confidence intervals. In conclusion, it was found that the histamine release test is a convenient diagnostic method and the study indicates a diagnostic value comparable to the common diagnostic methods in clinical allergy.     

Clinical improvement and immunological changes in atopic dermatitis patients undergoing subcutaneous immunotherapy with a house dust mite allergoid: a pilot study

BACKGROUND: House dust mites (HDMs) represent significant indoor allergen sources for patients with atopic dermatitis (AD). Subcutaneous allergen-specific immunotherapy (SCIT) has been shown to be successful in patients with allergic rhinitis and mild asthma and might represent an attractive therapeutic option for the long-term treatment of HDM sensitizations in AD patients. However, only a few studies have been conducted on the effectiveness of HDM SCIT in AD, resulting in controversial clinical results. Data on immunological changes induced by SCIT in AD patients are rare. OBJECTIVES: We performed an open pilot study to assess clinical changes and objective laboratory parameters and evaluate the benefit of HDM SCIT in 25 AD patients with IgE-mediated sensitization against HDM. METHODS: The severity of AD was evaluated by the severity scoring of atopic dermatitis system (SCORAD). Specific IgE and IgG4 against HDM and serum levels of TARC/CCL17, MDC/CCL22, IL-16, IL-4, IFN-gamma, IL-10 and TGF-beta1 were measured during SCIT. RESULTS: Subjective and objective SCORAD improved significantly within only 4 weeks of treatment. The level of the tolerogenic cytokine IL-10 increased, whereas CCL17 and IL-16 decreased in the sera of the patients during SCIT. Allergen specific IgE decreased, while IgG4 increased during SCIT. CONCLUSION: In this open-label pilot study, SCIT with an HDM extract in patients with AD led to a significant improvement of AD mirrored by a reduction of SCORAD as well as serological and immunological changes, which might serve as valuable parameters to estimate the therapeutic effect of SCIT.     

Prevalence and severity of allergic rhinitis in house dust mite-allergic patients with bronchial asthma or atopic dermatitis

BACKGROUND: Allergic rhinitis, asthma and atopic dermatitis are closely associated. Although population-based studies report a high prevalence of rhinitis among asthma patients, less is known of the association between rhinitis and atopic dermatitis and the severity of concomitant rhinitis. OBJECTIVES: We aimed to determine the prevalence and severity of allergic rhinitis among asthmatics and patients with atopic dermatitis and assessed whether age and comorbidity influence the severity of rhinitis signs and symptoms. METHODS: Three hundred and twenty-five patients recruited for a multicentre trial to study the effect of encasings of mattresses, pillows and duvets on signs and symptoms of allergic rhinitis and/or asthma and/or atopic dermatitis recorded visual analogue scores (VAS) and daily symptom scores and underwent nasal challenge tests with house dust mite (HDM). RESULTS: Based on history and clinical symptoms 92% of the 164 asthmatic patients and 85% of the 86 patients with atopic dermatitis could be diagnosed as having rhinitis. Inclusion of a positive provocation to HDM did not result in a substantial lower prevalence of rhinitis. Subjects reported moderate symptoms, with mean rhinitis VAS scores ranging from 40.0 to 55.0. Presence of atopic dermatitis was associated with lower rhinitis VAS and symptoms scores, whereas in multivariate analysis the presence of asthma was positively associated with nasal responsiveness to HDM. CONCLUSION: The prevalence of nasal symptoms in patients with bronchial asthma or atopic dermatitis and sensitized to house dust mites is high. Although the majority of patients experience mild to moderate symptoms, the presence of nasal disease needs to be examined in all patients with atopic disorders.     

Evaluation of an intranasal house dust mite provocation model as a tool in clinical research

BACKGROUND: As a result of the all-year-round exposure to house dust mite (HDM), perennial rhinitis patients never have a clear symptom-free period. In this study, we investigated whether, despite these symptoms, we can still use nasal HDM provocations to study perennial allergic rhinitis and the effects of treatment. METHODS: In a parallel-group study, after 1 week treatment with either fluticasone propionate aqueous nasal spray (FPANS) or placebo, 20 patients, allergic to HDM, registered symptoms (nasal obstruction, rhinorrhoea, sneezing, pruritus and eye symptoms) using three different scoring methods [Lebel, categorical and visual analogue scale (VAS)] and peak nasal inspiratory flow (PNIF) after HDM provocations. Provocations were performed with 1000 biological units/ml and 24 h later with 10,000 biological units/ml of HDM. Before and after the provocations, nasal mucosa biopsies were taken for immunohistochemical staining to determine the number of eosinophils. RESULTS: House dust mite provocations resulted in an increase in symptoms and a decrease in PNIF. Even at high-dose provocation, the FPANS group registered significantly lower symptoms than the placebo group for nasal blockage, sneezing, eye symptoms, and PNIF in both early and late phases. FPANS also suppressed rhinorrhoea during the late phase and the influx of eosinophils in the lamina propria. CONCLUSION: Despite the high background of symptoms, allergic responses can be induced in this perennial rhinitis model. The VAS score seems most suited to detect these changes and the suppression of symptoms by 7 days of FPANS treatment. Epithelial eosinophilia at baseline was correlated positively with the severity of the reaction after the first provocation.     

The respiratory effects of reduction of mite allergen in the bedrooms of asthmatic children — a double-blind controlled trial

Background Inhalation of house dust mite (HDM) allergen may provoke attacks of asthma. Objective We investigated whether a double-blind placebo-controlled community-based study aimed at reducing the HDM allergens in the bedrooms of HDM sensitive asthmatic children using the best methods available would prove beneficial to the children's health. Methods The children (mean age 9.9 years, 34 boys) were recruited by a questionnaire submitted to 7386 families in a geographically-defined area of the UK. Subjects were chosen to take part in the double-blind placebo-controlled trial if they were asthmatic, skin sensitive to mites, and had mite allergen in their mattresses. Seventy children were randomly allocated to groups. In the active group, the children's bedrooms were treated with an acaricide (Acarosan) and the mattresses, pillows and duvets were encased in exclusion covers. The control group received placebo treatments. Results Forty-nine complete data sets were obtained. Applying bedding covers and Acarosan led to a median reduction of 480 ng (100%) in mite allergen on the mattress vs 215 ng (53%) reduction in placebo-treated group by 6 weeks. No evidence was found that the acaricide reduced mite allergen level. A change in bronchial reactivity to histamine was observed in the children after 6 weeks. This was not associated with any change in thrice-daily records of peak expiratory flow rate. By 24 weeks, the actively-treated children had improved forced expiratory volume in 1s (FEV₁) and fewer required bronchodilator therapy or reported asthmatic symptoms than did the controls. Conclusions The results suggest that mite removal procedures may modestly improve mite-sensitive asthmatics and could perhaps be of value in exceptionally mite-sensitive and/or highly mite-exposed individuals whose response to the attempted removal should be measured.     

Effect of intranasal fluticasone proprionate on the immediate and late allergic reaction and nasal hyperreactivity in patients with a house dust mite allergy

Background Patients with perennial allergic rhinitis develop nasal symptoms not only after allergen exposure, but generally also after non-specific stimuli. Objective To evaluate the effect of 2 week's treatment with fluticasone propionate aqueous nasal spray (FPANS) on the nasal clinical response, inflammatory mediators and nasal hyperreactivity. Methods Twenty-four rhinitis patients allergic to house dust mite (HDM). participated in a douhle-blind. placebo-controlled crossover study. After 2 week's treatment with placebo or 200 μg FPANS twice daily, patients were challenged with HDM extract. Symptoms were recorded and nasal lavages were collected for up to 9.5 h after challenge. Nasal hyperreaclivity was determined by histamine challenge 24 h later. Results Because of a carry-over effect for the immediate symptom score, for this variable only the data from the first treatment period were used. FPANS treatment resulted in a significant decrease of nasal symptoms with 70%. 69% and 63% after 100. 1000 and 10000 Biological Units (BU)/mL of HDM extract respectively. Active treatment resulted in a 76% decrease of the late-phase symptoms. FPANS treatment significantly reduced albumin influx after HDM 1000 BU/mL with 62% and tended to reduce tryptase release after HDM 1000 BU ml. (P 0.0629). During the late phase FPANS treatment reduced albumin influx with 67% and eosinophil cationic protein (ECP) release with 83%. No effect of FPANS was seen on histamine levels. FPANS significantly decreased histamine-induced symptom score with 34%, secretion with 32%, and sneezes with 41%. Conclusion FPANS significantly inhibits the immediate and late allergic response, and nasal hyperreactivity, probably by suppressing mast cells and eosinophils in the nasal mucosa.     

Comparison of a generic and a rhinitis-specific quality-of-life (QOL) instrument in patients with house dust mite allergy: relationship between the SF-36 and Rhinitis QOL Questionnaire

BACKGROUND: Generic and disease-specific quality-of-life (QOL) questionnaires are commonly used in subjects with allergic rhinitis (AR). AR, however, is closely associated with other disorders such as bronchial asthma and atopic dermatitis (AD). These co-morbid associations may have an effect on the inter-relation of generic and disease-specific QOL outcomes and the behaviour of this inter-relation in time. OBJECTIVE: To unravel the inter-relationships between the outcome of a generic instrument (SF-36) and a disease-specific instrument (Rhinitis QOL Questionnaire (RQLQ)). MATERIALS AND METHODS: In the framework of a randomized clinical trial with respect to the efficacy of impermeable bedding covers in house dust mite (HDM) allergy, SF-36 and RQLQ were administered to 224 adults with AR and/or allergic asthma and/or AD at baseline and after 12 months of intervention. Regression analysis and canonical correlation were used to estimate overlap. RESULTS: Overlap between SF-36 and RQLQ domains in terms of explained variance ranged from 6% to 56%. Canonical correlation yielded low coefficients (0.16-0.27). Moreover, both SF-36 and RQLQ scores did not change significantly during the intervention. CONCLUSION: In patients with HDM allergy characterized by co-morbid associations, SF-36 and RQLQ cover different aspects in QOL. It is advocated to use both simultaneously in performing QOL studies.     

Long-lasting effect of sublingual immunotherapy in children with asthma due to house dust mite: a 10-year prospective study

BACKGROUND: Subcutaneous immunotherapy for respiratory allergy has shown a long-lasting efficacy after its discontinuation, whereas this evidence is still lacking for sublingual immunotherapy, despite the fact that it is widely used. OBJECTIVE: We aimed to evaluate whether a long-lasting effect of SLIT occurs, in a prospective parallel group controlled study. METHODS: Sixty children (mean age 8.5 years) suffering from allergic asthma/rhinitis due to mites were subdivided into two matched groups: 35 underwent a 4- to 5-year course of SLIT with standardized extract and 25 received only drug therapy. The patients were evaluated at three time points (baseline, end of SLIT and 4 to 5 years after SLIT discontinuation) regarding presence of asthma, use of anti-asthma drugs, skin prick tests and specific IgE. RESULTS: We found that in the SLIT group there was a significant difference vs. baseline for the presence of asthma (P 相似文献