Mite Allergen Exposure Research Articles

Lung pathogenic, P2RX7-dependent CD4 +T cell immune responses to influenza are exacerbated by co-exposure with lung allergens

Abstract Extracellular ATP (eATP) is a danger signal released by inflamed tissues, and can be sensed by immune cells via P2RX7. P2RX7 promotes lung pathology induced by influenza infection, by inducing exacerbated numbers of lung CD4 +T cells. In response to influenza, lung CD4 +T cells are comprised of a type 1 (Th1)-like population, and a subset resembling follicular helper (Tfh) CD4 +T cells; this subset is called tissue-resident helper (Trh). Trh cells amplify lung effector immune responses. Trh cells express high P2RX7 levels, and current research in our laboratory shows that P2RX7 is crucial for Trh cell establishment and subsequent lung damage. We have also found that the intensity of lung damage caused by influenza is positively correlated with P2RX7 +lung Trh cells. It is not clear, however, how concomitant exposure to influenza and type 2 immunity-inducing lung allergens (a common clinical occurrence in the United States) affect P2RX7 +lung Trh cells and their resultant tissue damage. We investigated this, using House Dust Mite (HDM) allergen exposure together with Influenza (PR8) infection. HDM/PR8 co-exposure induced worsening of lung inflammation, compared to single exposure to PR8. This inflammation had type 1 characteristics (i.e. parenchymal immune cell accumulation and absence of mucus). The increased lung damage generated by HDM/PR8 exacerbated the generation of influenza-specific P2RX7 +lung Trh cells. The accumulation of lung Trh cells (and subsequent tissue damage) caused by HDM/PR8 was abolished in T cell-specific P2RX7-knockout mice. Our results suggest that local inflammation, eATP release and sensing, and lung Trh cells together dictate the intensity of lung damage, regardless of the nature of the lung disease agent. R01AI170649

Role of ventilation and cleaning for controlling house dust mite allergen infestation: A study on associations of house dust mite allergen concentrations with home environment and life styles in Tianjin area, China.

House dust mites produce well-known allergens for asthma and allergy among children. To study house dust mite allergen exposure level in northeast China and characterize its association with indoor environmental factors and cleaning habits, we inspected 399 homes in Tianjin area and collected dust from mattresses. Dermatophagoides farinae (Der f) and Dermatophagoides pteronyssinus (Der p) were detected by the enzyme-linked immunosorbent assay (ELISA) method. The medians of total allergen concentrations for spring, summer, autumn, and winter were 524 ng/g, 351 ng/g, 1022 ng/g, and 1010 ng/g. High indoor air relative humidity (RH), low air change rate, indoor dampness, and frequent changing of quilt cover/bedsheet/pillow case were significantly associated with high house dust mite allergen concentration (relative risk [RR]: RH, 1.18-1.34; air change rate, 0.97-1.00; dampness, 2.92-3.83; changing quilt cover/bedsheet/pillow case, 0.66-0.75). The decrease in the absolute humidity gradient between indoors and outdoors that occurs with increased air change rate may explain why a high ventilation reduces house dust mite allergen concentration. The findings of this study show the importance of ventilation and cleaning for controlling house dust mite allergens. We found that the decrease in additional absolute humidity (e.g., humidity indoor -humidity outdoor ) with increased air change rate may be the main reason that a high ventilation rate reduces house dust mite allergen concentration. Ventilation and cleaning should be both considered for creating a healthy home environment.

Analytical study of inflammatory cytokines and immunoglobulin expression following dust mite allergen exposure in pregnant mice

Background Allergen tolerability due to allergic immune reactions could be transferred through the placenta from maternal to fetal circulation. Hence, a further investigation regarding the tolerability following mite allergen exposures is desirable.
 Objective To evaluate various doses of mite allergens and cytokines associated with Th1, Th2, and Treg cells with regards to possible allergic tolerance in neonatal mice.
 Methods This study used an experimental design with a post-test only control group, to assess the effect of mite allergens on pregnant BALB/C mice and their newborns. In this study female BALB/C mice aged 10 weeks were mated with male mice, then pregnant BALB/C mice were exposed to allergens at 4 weeks gestation. During pregnancy, pregnant females’ blood specimens were taken to measure cytokines and immunoglobulins. Meanwhile, neonatal blood specimens were taken at 2 weeks postnatally to measure cytokines and immunoglobulins. Blood specimens from pregnant BALB/C mice and their newborns were evaluated using ELISA kits for the following cytokines: interleukin (IL)-2, interferon (IFN)-γ, interleukin (IL)-4, IL-5, IL-10, TGF-β1, as well as immunoglobulins (Ig)G-1, IgG-2a, IgG-2b, IgG3 subclass, IgM, IgA, and IgE. The case group was the group that received high and low doses of exposure, while the control group did not get exposure.
 Results In response to low dose mite allergen exposure, there were significant increases of IL-2, IFN-y, and IL-4, IL-5, and TGF-β1 in mothers and neonates. Pregnant mices that received high doses of allergens, however, had significant increases in IL-5 and TGF-B1; results were likewise for their offspring. Mothers and neonates, had significantly increased expression of IgG subclasses after a low dose of dust mite allergen. Following a ten-fold increase in allergen dose, the mothers showed significant increases in IgA, IgM, IgE, and IgG subclasses, whereas in neonatal mice, those immunoglobulin levels were not significantly different from control mice.
 Conclusion Exposure to mite allergens can trigger regulatory functions of Th1, Th2, and Tregs cells to activate their cytokines, except IL-10. The regulatory function of Tregs is dominated by TGFβ in maternal and neonatal mice, at low and high doses. Th1 cytokines express cytokines during exposure only to low-dose allergens and Th2 cells regulate IL-5 levels to both low- and high-dose allergens.

Animal Allergens, Endotoxin, and β-(1,3)-Glucan in Small Animal Practices: Exposure Levels at Work and in Homes of Veterinary Staff

ObjectivesIn veterinary settings, high exposures to animal allergens and microbial agents can be expected. However, occupational exposure levels are largely unknown. The objective of this study was to estimate the allergen, endotoxin, and β-(1,3)-glucan concentrations in small animal practices and in the homes of practice employees.MethodsDust samples were collected using electrostatic dust fall collectors in diverse rooms of 36 small animal practices, as well as in employees’ homes. Major animal allergens (Fel d 1, Can f 1, Ory c 3, Cav p 1, Equ c 1, Bos d 2), domestic mite (DM) allergens, and β-(1,3)-glucan levels were measured using enzyme immunoassays. Endotoxin was determined using the Limulus amoebocyte lysate assay. Influences on exposure levels were analyzed using multilevel models.ResultsThe levels of Can f 1, Fel d 1, Ory c 3, and Cav p 1 were up to 30 times higher in practices compared with homes without animals, but significantly lower compared with the homes with the respective pet. Although horses were not treated in the practices, Equ c 1 was found in 87.5% of samples, with the highest concentrations measured in changing rooms. DM levels were significantly lower in practices than in all private homes, and endotoxin levels were similar to those in homes with pets. In the practice itself, exposure levels were significantly influenced by animal presence, type of the room, and area per employee; whereas, room volume and diverse cleaning measures had mostly no effect.ConclusionsExposure to animal allergens is high in veterinary practices, but it does not reach levels of households with pets. Domestic mite allergen and endotoxin exposure seem to be low for workers in veterinary practices. The high Equ c 1 detection rate strongly indicates dispersal of allergens, most likely through clothing and hair.

Multigenerational Epigenetic Regulation of Allergic Diseases: Utilizing an Experimental Dust Mite-Induced Asthma Model.

Environmental exposures have been linked to increased asthma risk, particularly during pregnancy and in early life. Here we use a mouse model of allergic lung disease to examine the effects of pre- and perinatal house dust mite (HDM) allergen exposure on offspring phenotypic and transcriptional outcomes in three generations. We show that maternal HDM exposure (F0) acts synergistically with adult HDM exposure, leading to enhanced airway hyperresponsiveness (AHR) and lung inflammation when compared to mice exposed solely in adulthood. Additionally, a subset of F1 males were not challenged in adulthood, and used to generate F2 progeny, which was then used to generate F3 progeny. Upon adult challenge to HDM, F2, and F3 males generated from the maternal HDM (F0) exposure lineage displayed increased airway reactivity and inflammation when compared to mice exposed solely in adulthood. These findings indicate that maternal allergen exposure is capable of enhancing either susceptibly to or severity of allergic airway disease. To examine the role of epigenetic inheritance of asthma susceptibility induced by maternal HDM exposure, we utilized a genome-wide MeDIP-seq and hMeDIP-seq analysis to identify genes differentially methylated (DMG) and hydroxymethylated (DHG), and their association with the enhanced AHR. In addition, we validated the relationship between DNA methylation and mRNA expression of the DMGs and DHGs in the male sub-generations (F1-F3). We found the expression of Kchn1, Nron, and Spag17 to be differentially hydroxymethylated and upregulated in the F1 exposed to HDM both in early life and in adulthood when compared to F1 mice exposed solely in adulthood. Kcnh1 remained upregulated in the F2 and F3 from the maternal HDM (F0) exposure lineage, when compared to F1 mice exposed solely in adulthood. In summary, we demonstrated that maternal HDM exposure in early life can alter the gene expression and phenotype of offspring upon adult HDM exposure, resulting in more severe disease. These effects persist at least two generations past the initial insult, transmitted along the paternal line.

Associations between Environmental dust composition and Atopic Dermatitis in urban and rural settings.

Environmental exposures are involved in the pathogenesis of the allergic phenotype and in determining which individual triggers a person becomes sensitized to. Atopic dermatitis (AD) may modulate these effects through increased penetration through the skin modifying the immune system and AD may be triggered or intensified by environmental exposures. These exposures and immune-modulating factors may differ in urban and rural environments. To compare house dust composition in urban and rural settings and correlate them with AD outcomes. Dust samples were collected from the beds of 156 children aged 6months to 3years. 42% of participants had atopic dermatitis. Samples were analyzed for bacterial endotoxin, fungal (β-1,3-glucan) levels, and house dust mite, cockroach, dog, cat, mouse, and peanut allergen. Exposures were compared in urban and rural environments and in participants with and without AD. Endotoxin but not fungal β-glucan exposure is higher in the environment of healthy controls than children with AD in both urban and rural settings. House dust mite allergen exposure is high in urban and rural settings with Dermatophagoides detected in 100% of samples. Cat and dog allergen exposure mirrors pet ownership patterns which differ slightly between groups and environments. Mouse allergen exposure is higher in urban homes. Environmental endotoxin may be protective against AD in both urban and rural settings. There are marked differences in allergen exposure in urban and rural settings, but these are unlikely to be important protective or risk factors.

Describing fluctuating indoor aerosol dust measurements with application to house dust mite allergens

Measuring house dust mite aeroallergen concentrations is essential in understanding mite allergen exposure. Physically, the aerolized house dust mite faeces are part of indoor particulate matter. We studied the statistical ways of summarizing measurements of fluctuating mite aeroallergen exposure inside homes through indoor particulate matter. To study emissions from beddings, we measured the time-related airborne dust concentration after shaking a duvet. Analysis was performed both by a method based on the estimated mean and by a non-linear model. Twenty-eight studies reported a sum of concentrations; only one also reported the peak. In our four experiments on shaking a duvet (245 to 275 measurements each), the peak value was two to four times higher than the mean. The mean-based and non-linear models both predicted the sum of concentrations exactly. A 1% upper prediction bound and the non-linear model predicted the peak emission rate moderately well (64 to 92%, and 63 to 93%, respectively). Mean levels of indoor particulate matter measurements differ substantially from peak concentrations. The use of the mean is only sufficient to predict the sum of concentrations. We suggest that, mite aeroallergen measurements should include information on the peak as well as the mean.

Clinical Validation of House Dust Mite Allergen Exposure in the Environmental Exposure Unit

Clinical Validation of House Dust Mite Allergen Exposure in the Environmental Exposure Unit

Asthma as an outcome: Exploring multiple definitions of asthma across birth cohorts in the Environmental influences on Child Health Outcomes Children's Respiratory and Environmental Workgroup

Asthma definitions vary widely across research studies and feature a trade-off between inclusivity and precision. Harmonizing definitions across multiple asthma birth cohort studies highlights these challenges.

Cerium dioxide nanoparticles exacerbate house dust mite induced type II airway inflammation

BackgroundNanomaterial inhalation represents a potential hazard for respiratory conditions such as asthma. Cerium dioxide nanoparticles (CeO2NPs) have the ability to modify disease outcome but have not been investigated for their effect on models of asthma and inflammatory lung disease. The aim of this study was to examine the impact of CeO2NPs in a house dust mite (HDM) induced murine model of asthma.ResultsRepeated intranasal instillation of CeO2NPs in the presence of HDM caused the induction of a type II inflammatory response, characterised by increased bronchoalveolar lavage eosinophils, mast cells, total plasma IgE and goblet cell metaplasia. This was accompanied by increases in IL-4, CCL11 and MCPT1 gene expression together with increases in the mucin and inflammatory regulators CLCA1 and SLC26A4. CLCA1 and SLC26A4 were also induced by CeO2NPs + HDM co-exposure in air liquid interface cultures of human primary bronchial epithelial cells. HDM induced airway hyperresponsiveness and airway remodelling in mice were not altered with CeO2NPs co-exposure. Repeated HMD instillations followed by a single exposure to CeO2NPs failed to produce changes in type II inflammatory endpoints but did result in alterations in the neutrophil marker CD177. Treatment of mice with CeO2NPs in the absence of HDM did not have any significant effects. RNA-SEQ was used to explore early effects 24 h after single treatment exposures. Changes in SAA3 expression paralleled increased neutrophil BAL levels, while no changes in eosinophil or lymphocyte levels were observed. HDM resulted in a strong induction of type I interferon and IRF3 dependent gene expression, which was inhibited with CeO2NPs co-exposure. Changes in the expression of genes including CCL20, CXCL10, NLRC5, IRF7 and CLEC10A suggest regulation of dendritic cells, macrophage functionality and IRF3 modulation as key early events in how CeO2NPs may guide pulmonary responses to HDM towards type II inflammation.ConclusionsCeO2NPs were observed to modulate the murine pulmonary response to house dust mite allergen exposure towards a type II inflammatory environment. As this type of response is present within asthmatic endotypes this finding may have implications for how occupational or incidental exposure to CeO2NPs should be considered for those susceptible to disease.

Home Environmental Interventions for House Dust Mite

It has been 50 years since the dust mite was first appreciated to be a major source of allergen in house dust, and by extension a key trigger of allergic respiratory disease. Since that time a number of protein allergens have been identified and characterized, mainly from mite feces, and standardized mite extracts and IgE assays have been developed. Insights into the lifecycle of dust mites and aspects of mite allergen biology have shed light on the mechanisms that lead to respiratory disease and to the development of interventions that can minimize dust mite allergen exposure. It is now clear that dust mite allergy is a key contributor to asthma in many parts of the world, and that long-term avoidance can be effective for preventing sensitization and minimizing the development and severity of respiratory disease. Here, we discuss the evidence linking dust mites with respiratory disease, outline studies that support the efficacy of home environmental interventions, and highlight practical methods that have been shown to be effective as part of a multifaceted approach to dust mite avoidance.

Genome-wide interaction study of dust mite allergen on lung function in children with asthma

Childhood asthma is likely the result of gene-by-environment (G×E) interactions. Dust mite is a known risk factor for asthma morbidity. Yet, there have been no genome-wide G×E studies of dust mite allergen on asthma-related phenotypes. We sought to identify genetic variants whose effects on lung function in children with asthma are modified by the level of dust mite allergen exposure. A genome-wide interaction analysis of dust mite allergen level and lung function was performed in a cohort of Puerto Rican children with asthma (Puerto Rico Genetics of Asthma and Lifestyle [PRGOAL]). Replication was attempted in 2 independent cohorts, the Childhood Asthma Management Program (CAMP) and the Genetics of Asthma in Costa Rica Study. Single nucleotide polymorphism (SNP) rs117902240 showed a significant interaction effect on FEV1 with dust mite allergen level in PRGOAL (interaction P=3.1×10-8), and replicated in the same direction in CAMP white children and CAMP Hispanic children (combined interaction P=.0065 for replication cohorts and 7.4×10-9 for all cohorts). Rs117902240 was positively associated with FEV1 in children exposed to low dust mite allergen levels, but negatively associated with FEV1 in children exposed to high levels. This SNP is on chromosome 8q24, adjacent to a binding site for CCAAT/enhancer-binding protein beta, a transcription factor that forms part of the IL-17 signaling pathway. None of the SNPs identified for FEV1/forced vital capacity replicated in the independent cohorts. Dust mite allergen exposure modifies the estimated effect of rs117902240 on FEV1 in children with asthma. Analysis of existing data suggests that this SNP may have transcription factor regulatory functions.

Rhinoviruses significantly affect day-to-day respiratory symptoms of children with asthma

BackgroundViruses are frequently associated with acute exacerbations of asthma, but the extent to which they contribute to the level of day-to-day symptom control is less clear.ObjectiveWe sought to explore the relationship between viral infections, host and environmental factors, and respiratory symptoms in children.MethodsSixty-seven asthmatic children collected samples twice weekly for an average of 10 weeks. These included nasal wash fluid and exhaled breath for PCR-based detection of viral RNA, lung function measurements, and records of medication use and asthma and respiratory symptoms in the previous 3 days. Atopy, mite allergen exposure, and vitamin D levels were also measured. Mixed-model regression analyses were performed.ResultsHuman rhinoviruses (hRVs) were detected in 25.5% of 1232 nasal samples and 11.5% of breath samples. Non-hRV viruses were detected in less than 3% of samples. hRV in nasal samples was associated with asthma symptoms (cough and phlegm: odds ratio = 2.0; 95% CI = 1.4-2.86, P = .0001; wheeze and chest tightness: odds ratio = 2.34, 95% CI = 1.55-3.52, P < .0001) and with cold symptoms, as reported concurrently with sampling and 3 to 4 days later. No differences were found between the 3 hRV genotypes (hRV-A, hRV-B, and hRV-C) in symptom risk. A history of inhaled corticosteroid use, but not atopic status, mite allergen exposure, or vitamin D levels, modified the association between viruses and asthma symptoms.ConclusionThe detection of nasal hRV was associated with a significantly increased risk of day-to-day asthma symptoms in children. Host, virus genotype, and environmental factors each had only a small or no effect on the relationship of viral infections to asthma symptoms.

House Dust Mite Allergen Exposure in Adults Is Associated with Strong Specific Sensitization But Not with Clinical and Functional Respiratory Health Outcomes

Background: Exposure to house dust has been associated with asthma in adults, and this is commonly interpreted as a direct immunological response to dust mite allergens in those who are IgE sensitised to house dust mite (HDM). Objectives: The aim of this analysis is to utilise information collected as part of a large international observational multicentre study in order to explore, in adults, associations of respiratory symptoms, including severity of symptoms with mattress house dust mite allergen levels. Methods: Mattress house dust mite concentrations were measured in a population based sample of 2890 adults aged between 27 and 56 years living in 22 centres in 10 countries. Generalized linear mixed models were employed to explore the association of respiratory symptoms with house dust mite concentrations, adjusting for individual and household confounders. Results: There was no overall association of respiratory outcomes with measured house dust mite concentrations, even in those who reported they had symptoms on exposure to dust and those who had physician diagnosed asthma. There was an association of high serum specific IgE levels to HDM (&gt; 3.5 kUA/L) with mattress house dust mite concentrations. Conclusions: In conclusion, in a large international cross-sectional survey of adults there was evidence of an association of house dust mite concentrations with high levels of serum specific IgE to HDM, but not with clinical and functional respiratory health outcomes.

Multiple House Dust Mite Allergen- Sensitization Profiles in Children with Allergic Asthma

Background: Allergic asthma is a common chronic inflammatory disorder which affects populations, with increasing prevalence among children. The risk of developing asthma is uncertain but depends on the interaction of environmental and genetic factors. The role of house dust mite (HDM) allergen exposure in the development of sensitization and asthma remains unclear. Objective: This study determined the sensitization profiles of common HDM species in a population of asthmatic children, which is essential in the development of highly specific and accurate diagnostic and therapeutic strategies for asthma in children. Methods: The immunoglobulin E-binding activity of allergens from the HDM species Blomia tropicalis (Bt), Dermatophagoides farina (Df), and Dermatopahagoides pteronyssinus (Dp) were determined in 250 age- and sexmatched paediatric allergic asthma and non-atopic Filipino subjects using Enzyme-linked immunosorbent assay and western blot analysis. Results: Majority of the allergic asthma patients tested were sensitized with multiple allergens from different HDM species where 33% exhibited sensitizations to any two HDM species and 26% were sensitized with allergens from three HDMs. HDM allergens of different molecular weights bind to IgE in allergic asthma patients tested. In addition a significant correlation was observed between total IgE and HDM-specific IgE level among allergic asthma patients (Bt p-value=0.038; Df p-value=0.045; Dp p-value=0.003), suggesting a significant contribution of dust mite allergens in the up-regulation of total serum IgE levels of allergic asthma patients. Conclusion: The results obtained in this study suggest that the HDM species Bt, Dp, and Df are important sources of allergens that trigger multiple sensitization in children with allergic asthma in the Filipino population. The incorporation of Bt, Dp, and Df allergens in the panel of diagnostic allergens for HDM allergy and allergic asthma is highly recommended.

Analysis of mite allergic patients in a diverse territory by improved diagnostic tools

There are few studies comparing the sensitization with mite allergens from different mite species which could potentially be the cause of allergy. To improve the diagnosis of mite allergic patients from a diverse territory in which D. pteronyssinus/D. farinae mites together with storage mites could be present in the environment. Four hundred and seventy-seven patients (both children and adults) from different regions, covering the main mite prevalent areas of Spain, were recruited. sIgE to eight allergens was measured together with SPT to whole mite extracts, level of mite allergen exposure, and specific IgG(4) . BAT and CAST was performed in a subgroup of patients. D. pteronyssinus and L. destructor were more prevalent in Atlantic areas, whereas D. farinae predominate in Mediterranean areas. About 90% of patients were sensitized to group 1 and/or group 2 allergens. Group 2 was the most prevalent, and the IgE response/intensity of sensitization in BAT was higher. sIgE to Der p 2/Der f 2 was almost fully cross-reactive, but no cross-reactivity was detected with Lep d 2. Group 1 allergens were also cross-reactive, but in some patients a species-specific response was observed. sIgE to Lep d 2 was associated with SPT results to storage mites. Sensitization to Der p 1 was more frequent in children, whereas Lep d 2 sensitization was more frequent in adults. A higher ratio IgE/IgG(4) to Der p 2 was associated with the presence of allergic asthma. An improved diagnosis algorithm has been established. Group 2 allergens seem to have a leading role in mite allergy, but as group 1 sensitization could be species-specific in some patients and its prevalence is higher in children, an adequate balance on major mite species and major allergens must be consider in the design of mite allergy vaccines.

Die Leitlinie Allergieprävention auf dem Prüfstand

The recommendations of the revised guideline Primary Allergy Prevention published in 2009 are summarized and discussed. The updated guidelines do not further recommend reducing house dust mite allergen exposure as a measure of primary prevention. New suggestions include the avoidance of overweight, and reduction of the exposure to indoor and/or outdoor air pollutants. In line with the current guidelines, there is no scientific evidence that prolonged introduction of solid food is an allergy-preventive measure. Consequently, even children with a family history of atopy can introduce solid foods at the beginning of the 5th month. The recommendations on avoiding environmental tobacco smoke, breast feeding over 4 months, avoiding a mold-promoting indoor climate, vaccination according to current recommendations, and avoidance of furry pets (especially cats) in risk babies have remained unchanged.

Neither Dust Mite nor Cat Allergen Exposure Is Associated with Lung Function or Asthma Morbidity in Sensitized Baltimore City Children

RationaleAlthough pest allergen exposures are associated with asthma morbidity in sensitized Baltimore City children, the effects of dust mite (DM) and cat allergen (Ct) exposures on asthma in this population are unclear.Methods144 children (5-17y) with asthma were skin prick tested (SPT) at baseline. Lung function, health care utilization data, and bedroom dust samples were collected at baseline, 3, 6, 9, and 12 months. Der f 1 and Fel d 1 content in dust samples was quantified by ELISA. +SPT was defined as a net wheal >3mm. Exposure was defined as bedroom DM>2 μg/g and bedroom Ct> 8 μg/g. Analyses were adjusted for age, gender, type of insurance, total IgE, and sensitization and exposure to mouse and cockroach.ResultsParticipants were predominantly African American (91%), had public health insurance (85%), and had ≥1 +SPT (90%). FEV1/FVC% did not significantly differ between cat sensitized and exposed (S+E+) and non-cat-sensitized or non-cat-exposed (S-E-) participants (predicted% [95% CI]: (81.3[78.8-83.7]) and 80.7[79.4-82.0], respectively; p=0.6). This was also true for DM (S+E+: 81.8[78.8-84.8]; S-E-: 80.8[79.5-82.1], p=0.5). Acute asthma visits were similar for the Ct S+E+ and Ct S-E- groups (OR[95%CI]: 1.13[0.61-2.12]). The same trend held for DM S+E+ vs DM S-E- participants (0.41[0.16-1.03]). These findings were similar across various exposure cutpoints and with or without adjustment for pest allergen exposure and sensitization.ConclusionsDM and Ct allergen exposures are not major contributors to asthma morbidity in Baltimore City children. Public health initiatives in Baltimore should focus on pest allergens, which are known to contribute to asthma morbidity. RationaleAlthough pest allergen exposures are associated with asthma morbidity in sensitized Baltimore City children, the effects of dust mite (DM) and cat allergen (Ct) exposures on asthma in this population are unclear. Although pest allergen exposures are associated with asthma morbidity in sensitized Baltimore City children, the effects of dust mite (DM) and cat allergen (Ct) exposures on asthma in this population are unclear. Methods144 children (5-17y) with asthma were skin prick tested (SPT) at baseline. Lung function, health care utilization data, and bedroom dust samples were collected at baseline, 3, 6, 9, and 12 months. Der f 1 and Fel d 1 content in dust samples was quantified by ELISA. +SPT was defined as a net wheal >3mm. Exposure was defined as bedroom DM>2 μg/g and bedroom Ct> 8 μg/g. Analyses were adjusted for age, gender, type of insurance, total IgE, and sensitization and exposure to mouse and cockroach. 144 children (5-17y) with asthma were skin prick tested (SPT) at baseline. Lung function, health care utilization data, and bedroom dust samples were collected at baseline, 3, 6, 9, and 12 months. Der f 1 and Fel d 1 content in dust samples was quantified by ELISA. +SPT was defined as a net wheal >3mm. Exposure was defined as bedroom DM>2 μg/g and bedroom Ct> 8 μg/g. Analyses were adjusted for age, gender, type of insurance, total IgE, and sensitization and exposure to mouse and cockroach. ResultsParticipants were predominantly African American (91%), had public health insurance (85%), and had ≥1 +SPT (90%). FEV1/FVC% did not significantly differ between cat sensitized and exposed (S+E+) and non-cat-sensitized or non-cat-exposed (S-E-) participants (predicted% [95% CI]: (81.3[78.8-83.7]) and 80.7[79.4-82.0], respectively; p=0.6). This was also true for DM (S+E+: 81.8[78.8-84.8]; S-E-: 80.8[79.5-82.1], p=0.5). Acute asthma visits were similar for the Ct S+E+ and Ct S-E- groups (OR[95%CI]: 1.13[0.61-2.12]). The same trend held for DM S+E+ vs DM S-E- participants (0.41[0.16-1.03]). These findings were similar across various exposure cutpoints and with or without adjustment for pest allergen exposure and sensitization. Participants were predominantly African American (91%), had public health insurance (85%), and had ≥1 +SPT (90%). FEV1/FVC% did not significantly differ between cat sensitized and exposed (S+E+) and non-cat-sensitized or non-cat-exposed (S-E-) participants (predicted% [95% CI]: (81.3[78.8-83.7]) and 80.7[79.4-82.0], respectively; p=0.6). This was also true for DM (S+E+: 81.8[78.8-84.8]; S-E-: 80.8[79.5-82.1], p=0.5). Acute asthma visits were similar for the Ct S+E+ and Ct S-E- groups (OR[95%CI]: 1.13[0.61-2.12]). The same trend held for DM S+E+ vs DM S-E- participants (0.41[0.16-1.03]). These findings were similar across various exposure cutpoints and with or without adjustment for pest allergen exposure and sensitization. ConclusionsDM and Ct allergen exposures are not major contributors to asthma morbidity in Baltimore City children. Public health initiatives in Baltimore should focus on pest allergens, which are known to contribute to asthma morbidity. DM and Ct allergen exposures are not major contributors to asthma morbidity in Baltimore City children. Public health initiatives in Baltimore should focus on pest allergens, which are known to contribute to asthma morbidity.

It’s time to rethink mite allergen avoidance

The role of allergen exposure in the etiology of allergic sensitization and asthma is complex. Advice on strategies to avoid domestic allergens remains contentious because trials of interventions aimed to prevent asthma or reduce symptoms have often failed to demonstrate benefits. Asthma management guidelines differ widely in their recommendations, while Web-based information often claims benefits associated with products. In this rostrum we argue that although many factors have a role in both the etiology and the exacerbation of asthma, allergen exposure probably remains an important contributor to the manifestations of the disease. Currently, there is no evidence-based framework for effective domestic allergen avoidance interventions to reduce chronic aeroallergen exposure. The development of an effective approach to allergen avoidance requires a better understanding of (a) the physical nature of chronic aeroallergen exposure and methods for measuring and reducing this, (b) the interaction between allergen exposure and innate immune modulators at different disease stages, and (c) markers enabling the identification of individuals who would benefit from this. The strategic risk of overemphasizing other novel mechanisms and approaches to asthma management is that we will prematurely abandon and fail to improve an existing approach that could have a significant impact on the development, progression, and symptoms of the disease.

The hammock: a reservoir of allergens

INTRODUCTION:Asthma affects approximately 10% of the world's population. Sensitization to allergens is an important risk factor, and exposure to allergens is associated with disease severity.METHODS:We performed skin tests to evaluate allergen sensitization to mites, cockroaches, cats, dogs, and molds in 73 asthmatic patients. Enzyme Linked Immunosorbent Assay was used to assay the mite and cockroach allergens found in dust from the bedding, hammocks, bedroom floors, living rooms, and kitchens of 29 patients and 14 controls.RESULTS:Fifty patients (68.5%) had positive skin test responses. There were positive responses to D. pteronyssinus (52.0%), B. tropicalis (53.4%), T. putrescentiae (15.0%), E. maynei (12.3%), L. destructor (8.2%), B. germanica (20.5%), P. americana (21.9%), Felis catus (10.9%), C. herbarium (2.7%), A. alternata (4.1%), and P. notatun (1.3%). The exposure to mite and cockroach allergens was similar in the patients and the controls. The Dermatophagoides pteronyssinus Group 1 levels were highest in the beds and hammocks. The Blattella germanica Group 1 levels were highest in the kitchens, living rooms and hammocks.DISCUSSION:The positive skin tests to mites, cockroaches and cats were consistent with previous studies. D pteronyssinus was the most prevalent home dust mite, and hammocks were a source of allergens. To improve asthma prophylaxis, it is important to determine its association with mite allergen exposure in hammocks.