Biology, ecology, and prevalence of dust mites

Exosomes Derived from Dermatophagoides farinae Induce Allergic Airway Inflammation

House dust mites (HDMs) are a major source of indoor allergens that cause airway allergic disease. Dermatophagoides farinae, a predominant species of HDMs in China, has demonstrated pathogenic role in allergic disorders. Exosomes derived from human bronchoalveolar lavage fluid have been strongly associated with allergic respiratory diseases progression. However, the pathogenic role of D. farinae-derived exosomes in allergic airway inflammation has remained unclear until now. Here, D. farinae was stirred overnight in phosphate-buffered saline, and the supernatant was used to extract exosomes by ultracentrifugation. Then, shotgun liquid chromatography-tandem mass spectrometry and small RNA sequencing were performed to identify proteins and microRNAs contained in D. farinae exosomes. Immunoblotting, Western blotting, and enzyme-linked immunosorbent assay demonstrated the specific immunoreactivity of D. farinae-specific serum IgE antibody against D. farinae exosomes, and D. farinae exosomes were found to induce allergic airway inflammation in a mouse model. In addition, D. farinae exosomes invaded 16-HBE bronchial epithelial cells and NR8383 alveolar macrophages to release the inflammation-related cytokines interleukin-33 (IL-33), thymic stromal lymphopoietin, tumor necrosis factor alpha, and IL-6, and comparative transcriptomic analysis of 16-HBE and NR8383 cells revealed that immune pathways and immune cytokines/chemokines were involved in the sensitization of D. farinae exosomes. Taken together, our data demonstrate that D. farinae exosomes are immunogenic and may induce allergic airway inflammation via bronchial epithelial cells and alveolar macrophages. IMPORTANCE Dermatophagoides farinae, a predominant species of house dust mites in China, has displayed pathogenic role in allergic disorders, and exosomes derived from human bronchoalveolar lavage fluid have been strongly associated with allergic respiratory diseases progression. However, the pathogenic role of D. farinae-derived exosomes in allergic airway inflammation has remained unclear until now. This study, for the first time, extracted exosomes from D. farinae, and sequenced their protein cargo and microRNAs using shotgun liquid chromatography-tandem mass spectrometry and small RNA sequencing. D. farinae-derived exosomes trigger allergen-specific immune responses and present satisfactory immunogenicity, as revealed by immunoblotting, Western blotting, and enzyme-linked immunosorbent assay and may induce allergic airway inflammation via bronchial epithelial cells and alveolar macrophages. Our data provide insights into the mechanisms of allergic airway inflammation caused with D. farinae-derived exosomes and the treatment of house dust mite-induced allergic airway inflammation.

Identification of Glycycometus malaysiensis (for the first time in Brazil), Blomia tropicalis and Dermatophagoides pteronyssinus through multiplex PCR

Blomia tropicalis and Dermatophagoides pteronyssinus play an important role in triggering allergy. Glycycometus malaysiensis causes IgE reaction in sensitive people, but is rarely reported in domestic dust, because it is morphologically similar to B. tropicalis making the identification of these species difficult. The identification of mites is mostly based on morphology, a time-consuming and ambiguous approach. Herein, we describe a multiplex polymerase chain reaction (mPCR) assay based on ribosomal DNA capable to identify mixed cultures of B. tropicalis, D. pteronyssinus and G. malaysiensis, and/or to identify these species from environmental dust. For this, the internal transcribed spacer 2 (ITS2) regions, flanked by partial sequences of the 5.8S and 28S genes, were PCR-amplified, cloned and sequenced. The sequences obtained were aligned with co-specific sequences available in the GenBank database for primer design and phylogenetic studies. Three pairs of primers were chosen to compose the mPCR assay, which was used to verify the frequency of different mites in house dust samples (n = 20) from homes of Salvador, Brazil. Blomia tropicalis was the most frequent, found in 95% of the samples, followed by G. malaysiensis (70%) and D. pteronyssinus (60%). Besides reporting for the first time the occurrence of G. malaysiensis in Brazil, our results confirm the good resolution of the ITS2 region for mite identification. Furthermore, the mPCR assay proved to be a fast and reliable tool for identifying these mites in mixed cultures and could be applied in future epidemiological studies, and for quality control of mite extract production for general use.

Microbiome variation during culture growth of the European house dust mite, Dermatophagoides pteronyssinus

In culture, the house dust mite, Dermatophagoides pteronyssinus, shows different growth patterns, but the composition and changes in the associated microbial community during mite culture growth are poorly known. In this study, we analyzed temporal changes in microbial communities including 'internal' communities (inside mites, ingested) and 'environmental' communities (from culture environment). Microbial community structure was correlated with guanine content (a nitrogenous waste product of mites) and mite population density. Both internal and environmental microbial communities were remarkably consistent between biological replicates from the same culture age group and were composed of relatively few dominant taxa-11 bacterial and 3 fungal operational taxonomic units (OTUs). Significant changes over time in microbial community structure in the bulk culture environment and in internal mite samples were observed. The yeast, Saccharomyces cerevisiae, a main component of the mite diet, gradually disappeared during mite culture growth and was replaced by fungi from the genera Aspergillus and Candida in both 'internal' and 'environmental' samples. In environmental samples, bacteria from the genus Lactobacillus and S. cerevisiae were negatively correlated, and Aspergillus and Candida positively correlated, with guanine content. The relative abundance of bacteria from the genus Kocuria increased with mite density but declined with increasing guanine content. The relative abundance of bacteria from the genus Virgibacillus was negatively correlated with mite density in 'internal' samples. Gram-positive bacteria dominated bacterial microbiomes at all time points in our experiments, indicating a more limited possibility for vaccine contamination by bacterial endotoxins (heat-stable lipopolysaccharides produced mostly by Gram-negative bacteria) in our experimental cultures.

Evaluation of sensitization to the crude extract of Dermatophagoides farinae and its derived allergens, Der f 2 and Zen 1, in dogs with atopic dermatitis in Southern Brazil

BACKGROUND

Atopic dermatitis is associated with the production of IgE antibodies against environmental allergens and allergens of the house dust miteDermatophagoides farinae are frequently implicated in the disease.

OBJECTIVES

We aimed to observe the allergen-specific IgE against crudeD. farinae, Der f 2 and Zen 1 in dogs with atopic dermatitis and report if these dogs are in contact with material that could shelter mite allergens.

METHODS

100 dogs with clinical diagnosis of atopic dermatitis were included after exclusion of other forms of pruritic skin disease and dogs that already received specific or non-specific immunotherapy. These dogs were of different breeds and ages and they were presented at a veterinary teaching hospital and a private service of veterinary dermatology, both located in Curitiba, Southern Brazil. At the time of anamnesis, some questions were applied to know the possibility of these dogs having had contact with furniture and textile material which could shelter house dust mites. Sera samples were obtained and further analyzed by ELISA assay to measure serum IgE levels against these allergens with an established cut-off of 0.200 IgE optical density.

RESULTS

The allergen-specific IgE positivity against crudeD. farinae (92 %) and Zen 1 (77 %) was higher than Der f 2 (56 %). There was a correlation in sensitization to crude D. farinae and Zen 1 that was not observed between crude D. farinae and Der f 2 and Der f 2 and Zen 1. The sensitization to D. farinae and its allergens was associated with an unrestricted exposition to furniture and textile material. CONCLUSION & CLINICAL RELEVANCE: dogs with atopic dermatitis are frequently sensitized to D. farinae and its allergens, Der f 2 and Zen 1, may be considered major allergens in these dogs. Zen 1 may be the main allergen responsible for the sensitization to crude D. farinae.

Why despite the lower prevalence, is asthma more severe in the semiarid region?

INTRODUCTION AND OBJECTIVES

Asthma is a chronic inflammatory disease which is very prevalent throughout the world, and climatic factors, especially air humidity, have been considered fundamental to its development. This study aims to evaluate the relationship between the climate factor and the severity of asthma episodes in the semiarid region, comparing it to the coast and an intermediate climate region, considering the use of medication as an intervening factor.

MATERIALS AND METHODS

Ecological study in cities with different climatic conditions (semiarid, intermediate region and Coast). Prevailing data was obtained from the International Study of Asthma and Allergies in Childhood (ISAAC) protocol. We evaluated the temperature, humidity and use of drugs for asthma/100,000 inhabitants.

RESULTS

The prevalence of asthma was lower in the semiarid (14%; 95%CI=12.1-15.7) than the intermediate region (19.1%; 95%CI=17.7-20.6) and coast (17.9%; 95%CI=16.6-19.2). Episodes of severe asthma attacks were surprisingly higher in semiarid (10.4%; 95%CI=8.9-11.9) when compared to coast (4.1%; 95%CI=3.4-4.9) and intermediate region (5.0%; 95%CI=4.3-5.8). In the semiarid region, the humidity was lower and the temperature higher than the other cities evaluated. The dispensing of medications was lower in the semiarid region.

CONCLUSIONS

Temperature and humidity may have contributed to a lower prevalence and greater severity of asthma in the semiarid region. The dispensing of medications was lower in the semiarid region, indicating that access to both relief and control drugs was lower in this city. The possibility of lack of health care in the semiarid region can also be another explanatory factor associated.

lncRNA profiling in NCI-H292 cells after stimulation with Dermatophagoides farinae extracts

Airway epithelium cells are the first line of defense against airborne allergens. When cultured, epithelial cells can be exposed to various allergens, providing an ideal model to investigate allergic disorders. This study sought to characterize the profile of long noncoding (lnc) RNAs, which can regulate gene expression and exert functions in diverse cellular processes, in airway epithelial cells exposed to house dust mite allergens. NCI-H292 cells were exposed to house dust mite extract for 24 h. RNA expression was profiled in exposed and unexposed cells. There were 270 lncRNAs that were differentially expressed (fold change ≥ 2, P < 0.05) in NCI-H292 cells after stimulation with Dermatophagoides farinae (house dust mite) extracts. Furthermore, 119 lncRNAs and 22 messenger RNAs were co-expressed. Gene Ontology analysis showed that these under-regulated and up-regulated lncRNAs were associated with biological process, cellular component, and molecular function. After bioinformatic analysis of significantly regulated signaling pathways, we found these lncRNAs may target 16 gene pathways, including glycolysis, axon guidance, ErbB signaling, and mitogen-activated protein kinases (MAPK) signaling. The identification of differentially regulated lncRNAs in NCI-H292 cells after stimulation with Dermatophagoides farinae extracts, as well as their target gene pathways, can provide insight to the etiology and pathogenesis of allergy.

How clean is your house? A study of house dust mites, allergens and other contents of dust samples collected from households

Household dust contains an array of constituents, including house dust mites (HDM) and the HDM allergen, Der p 1, which can cause sensitivities such as asthma and eczema. Vacuuming can help alleviate symptoms, yet little is understood about cleaning behaviour in different households. This pilot study investigated the contents of dust from four household types (students; over 65 s; and families with and without pets). This was then related to cleaning behaviours and perceptions of cleanliness. Our investigation found that HDMs and Der p 1 were present in all households and sampling locations, including participants' cars. The median Der p 1 was greatest in the living room, though results varied. Demographic group was a determinant for the number of human and pet hairs present in dust. Surprisingly, vacuuming was the most disliked task overall. This information requires consideration when developing cleaning products and advising individuals with dust-related health issues.

Toxicity of Juniperus oxycedrus oil constituents and related compounds and the efficacy of oil spray formulations to Dermatophagoides farinae (Acari: Pyroglyphidae)

The American house dust mite (AHDM), Dermatophagoides farinae Hughes (Acari: Pyroglyphidae), is recognized as an important source of allergens in the domestic environment. This study was conducted to determine whether 19 constituents from essential oil of cade, Juniperus oxycedrus L. (Cupressaceae), eight structurally related compounds, and another 16 previously known cade oil constituents were toxic for adult AHDMs and to determine the route of acaricidal action of the test compounds, as well as to assess the control efficacy of four experimental spray formulations containing the oil (10-40 mg/L sprays). In a fabric-circle contact mortality bioassay, methyleugenol (LD₅₀, 5.82 µg/cm²) and guaiacol (8.24 µg/cm²) were the most toxic compounds against the mites, and the toxicity of these compounds and benzyl benzoate did not significantly differ. High toxicity was also observed with eugenol, m-cresol, and nerolidol (LD₅₀, 12.52-19.52 µg/cm²), and these compounds were significantly more toxic than N,N-diethyl-3-methylbenzamide (DEET) (LD₅₀, 37.67 µg/cm²). Cade applied as 30 or 40 mg/L experimental sprays provided 96 and 100% mortality against the mites, respectively, whereas permethrin (cis:trans, 25:75) 2.5 g/L spray treatment resulted in 17% mortality. In vapor-phase mortality tests, the compounds described were consistently more toxic in closed versus open containers, indicating that toxicity was achieved mainly through the action of vapor. Reasonable mite control in indoor environments can be achieved by spray formulation containing the 40 mg/L cade oil as potential contact-action fumigants.

Allergen homologs in the Euroglyphus maynei draft genome

Euroglyphus maynei is a house dust mite commonly found in homes worldwide and is the source of allergens that sensitize and induce allergic reactions in humans. It is the source of species-specific allergens as well as allergens that are cross-reactive with the allergens from house dust mites Dermatophagoides farinae and D. pteronyssinus, and the ectoparasitic scabies mite Sarcoptes scabiei. The genomics, proteomics and molecular biology of E. maynei and its allergens have not been as extensively investigated as those of D. farinae, D. pteronyssinus, and S. scabiei where natural and recombinant allergens from these species have been characterized. Until now, little was known about the genome of E. maynei and it allergens but this information will be important for producing recombinant allergens for diagnostic and therapeutic purposes and for understanding the allergic response mechanism by immune effector cells that mediate the allergic reaction. We sequenced and assembled the 59 Mb E. maynei genome to aid the identification of homologs for known allergenic proteins. The predicted proteome shared orthologs with D. farinae and S. scabiei, and included proteins with homology to more than 30 different groups of allergens. However, the majority of allergen candidates could not be assigned as clear orthologs to known mite allergens. The genomic sequence data, predicted proteome, and allergen homologs identified from E. maynei provide insight into the relationships among astigmatid mites and their allergens, which should allow for the development of improved diagnostics and immunotherapy.

Lower prevalence and greater severity of asthma in hot and dry climate

OBJECTIVE

To estimate asthma prevalence, severity, and associated factors in adolescents who live in a low relative humidity environment.

METHODS

In this cross-sectional study, adolescents aged 13-14 years from the city of Petrolina located in the Brazilian semiarid region answered the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. The possible explanatory variables of the study were gender, family income, mother's education, smokers in the household, parental history of asthma, personal history of allergic rhinitis or atopic dermatitis, and physical activity level. Poisson regression analysis was used to assess the association between asthma and the explanatory variables.

RESULTS

A total of 1591 adolescents participated in the study, of whom 49.7% were male. The prevalence of active asthma, severe asthma, and physician-diagnosed asthma were 14.0%, 10.4%, and 17.8%, respectively. Adolescents with asthma missed more school days than their peers (33 vs. 22 days/year; p<0.03). Associated factors that remained significant after adjustment were history of asthma in parents (PR=2.65, p<0.001) and personal diagnosis of allergic rhinitis (PR=1.96, p<0.001) and/or atopic dermatitis (PR=2.18, p<0.001).

CONCLUSION

Asthma prevalence in this low-humidity environment was lower, but more severe than those reported in other Brazilian cities. The dry climate might hamper disease control and this may have contributed to the higher school absenteeism observed. The association of asthma with allergic rhinitis and atopic dermatitis as well as a history of asthma in parents suggests that atopy is an important risk factor for asthma in this population.

Work-related allergies to storage mites in Parma (Italy) ham workers

OBJECTIVES

To investigate the role of storage mites in the development of allergic diseases among ham production workers, and to search for early alterations in lung function tests and early inflammation markers in exhaled air. Respiratory allergies due to storage mites have been reported in people with various occupations but, although such mites are unavoidable when curing ham, there are no published data concerning ham production workers.

SETTING

Secondary care.

DESIGN

Experimental cross-sectional study.

PARTICIPANTS

220 participants (110 ham production workers and 110 controls) were recruited.

PRIMARY AND SECONDARY OUTCOME MEASURES

Workers answered a medical questionnaire, and underwent spirometry and fraction of exhaled nitric oxide at 50 mL/s (FeNO₅₀) measurements. Those with allergic symptoms also underwent skin prick tests to determine their sensitisation to airborne allergens. A methacholine test was performed in symptomatic participants when spirometry was normal to assess airways hyper-responsiveness.

RESULTS

Symptomatic storage mite sensitisation was observed in 16 workers (14.5%) (rhinoconjunctivitis in 15 (63%) and asthma in (4%)) and 2 controls (1.8%; p=0.001). Higher FeNO₅₀ values in exposed symptomatic workers compared with healthy control participants (34.65±7.49 vs 13.29±4.29 ppb; p<0.001) suggested bronchial and nasal involvement, although their lung function parameters were normal. Regardless of exposure, a FeNO₅₀ value of 22.5 ppb seems to be 100% sensitive and 99.4% specific in distinguishing allergic and non-allergic participants. Multivariate analysis of FeNO₅₀ values in the symptomatic participants showed that they were positively influenced by IgE-mediated allergy (p=0.001) and reported symptom severity (p=0.041), and negatively by smoking status (p=0.049).

CONCLUSIONS

Ham processing workers, as well as workers involved in any meat processing work that includes curing, should be informed about the occupational risk of sensitisation to mites.

Diversity of House Dust Mite Species in Xishuangbanna Dai, a Tropical Rainforest Region in Southwest China

PURPOSE

To survey the species diversity of home dust mites (HDM) in Xishuangbanna, a tropical rainforest region in Southwest China.

METHODS

From August 2010 to January 2011, mite-allergic patients and healthy controls were invited to participate. Dust samples from the patients' homes were collected, and mites in the samples were isolated. Permanent slides were prepared for morphologically based species determination.

RESULTS

In total, 6316 mite specimens of morphologically identifiable species were found in 233 dust samples taken from 41 homes. The result shows that the mite family of Pyroglyphidae occupied the highest percentage of the total amount of mites collected, followed by Cheyletidae family. The most common adult Pyroglyphidae mites were Dermatophagoides (D.) farinae, D. pteronyssinus, and D. siboney. The most common mites found from other families were Blomia tropicalis, Tyrophagus putrescentiae, and Aleuroglyphus ovatus. Four main allergenic dust mite species D. farinae, D. pteronyssinus, D. siboney, and Blomia tropicalis were found to be coinhabiting in 6/41 homes.

CONCLUSION

The HDM population in homes in Xishuangbanna, a tropical rainforest region in Southwest China, has its own characteristics. It has rich dust mite species and the dust mite densities do not show significant variation across seasons.

Reproductive biology of Euroglyphus maynei with comparisons to Dermatophagoides farinae and D. pteronyssinus

The reproductive biology of the house dust mite, Euroglyphus maynei, is not well studied. This mite is usually less common in homes than Dermatophagoides farinae and D. pteronyssinus. When it is present, it usually co-inhabits with the Dermatophagoides spp. and is more restricted in geographical distribution. In this study, the duration of the life cycle (egg to adult) at 23 and 30 °C at 75% relative humidity (RH) and fecundity at 23 °C and 75% RH were determined for E. maynei and the data were compared to similar data for D. farinae and D. pteronyssinus. Adults hatched from eggs after 28 days at 23 °C and 20 days at 30 °C. Females produced 1.4 eggs/day during a reproductive period of 24 days at 23 °C. Euroglyphus maynei has a shorter life cycle than D. farinae and D. pteronyssinus at 23 °C but a longer life cycle at 30 °C. Euroglyphus maynei has a shorter reproductive period and produces fewer eggs than both D. farinae and D. pteronyssinus.

Asthma, Airway Symptoms and Rhinitis in Office Workers in Malaysia: Associations with House Dust Mite (HDM) Allergy, Cat Allergy and Levels of House Dust Mite Allergens in Office Dust

A prevalence study was conducted among office workers in Malaysia (N= 695). The aim of this study was to examine associations between asthma, airway symptoms, rhinitis and house dust mites (HDM) and cat allergy and HDM levels in office dust. Medical data was collected by a questionnaire. Skin prick tests were performed for HDM allergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae) and cat allergen Felis domesticus. Indoor temperature and relative air humidity (RH) were measured in the offices and vacuumed dust samples were analyzed for HDM allergens. The prevalence of D. pteronyssinus, D. farinae and cat allergy were 50.3%, 49.0% and 25.5% respectively. Totally 9.6% had doctor-diagnosed asthma, 15.5% had current wheeze and 53.0% had current rhinitis. The Der p 1 (from D. pteronyssinus) and Der f 1 (from D. farinae) allergens levels in dust were 556 ng/g and 658 ng/g respectively. Statistical analysis was conducted by multilevel logistic regression, adjusting for age, gender, current smoking, HDM or cat allergy, home dampness and recent indoor painting at home. Office workers with HDM allergy had more wheeze (p= 0.035), any airway symptoms (p= 0.032), doctor-diagnosed asthma (p= 0.005), current asthma (p= 0.007), current rhinitis (p= 0.021) and rhinoconjuctivitis (p< 0.001). Cat allergy was associated with wheeze (p= 0.021), wheeze when not having a cold (p= 0.033), any airway symptoms (p= 0.034), doctor-diagnosed asthma (p= 0.010), current asthma (p= 0.020) and nasal allergy medication (p= 0.042). Der f 1 level in dust was associated with daytime breathlessness (p= 0.033) especially among those with HDM allergy. Der f 1 levels were correlated with indoor temperature (p< 0.001) and inversely correlated with RH (p< 0.001). In conclusion, HDM and cat allergies were common and independently associated with asthma, airway symptoms and rhinitis. Der f 1 allergen can be a risk factor for daytime breathlessness.

House dust mite allergy: environment evaluation and disease prevention

There are two groups of dust mites, house dust mites (HDMs) and storage mites (SMs), that have been identified in the household environment. Both could induce airway inflammation through activation of innate and adaptive immunity and lead to asthma. In order to monitor environmental dust mite infestation, different methods can be used to detect their presence, such as the use of floating methods, monoclonal antibodies, and nanostructured biosensor. SM could be identified in the storage room, mainly in contaminated food such as mushrooms and corn starch. In HDM-sensitive subjects and mice that were challenged with HDM or SM after sensitization, these mites could up-regulate IgE levels, T helper 2 associated cytokine production and airway hypersensitivity. Different age groups of subjects were sensitized by different species of mites. More subjects above 70 years were sensitized by SM and more subjects below the age of 40 years were sensitized to HDM. Different allergenic components of dust mite extracts, such as Der p 1, Der p 2, could activate innate immunity through activating pattern recognition receptor (PRR) and then lead to allergic inflammation. The best modality to treat HDM allergy is immunomodulation through Treg cells and IgA production. In the recent years, many studies indicated probiotics could increase IgA secretion and the number of Treg cells. However, some studies conducted in adults have contradictory effects in reducing allergic symptoms. Therefore, probiotics confer inconclusive benefits on the allergic symptoms.

Inactivation of dust mites, dust mite allergen, and mold from carpet

Carpet is known to be a reservoir for biological contaminants, such as dust mites, dust mite allergen, and mold, if it is not kept clean. The accumulation of these contaminants in carpet might trigger allergies or asthma symptoms in both children and adults. The purpose of this study is to compare methods for removal of dust mites, dust mite allergens, and mold from carpet. Carpets were artificially worn to simulate 1 to 2 years of wear in a four-person household. The worn carpets were inoculated together with a common indoor mold (Cladosporium species) and house dust mites and incubated for 6 weeks to allow time for dust mite growth on the carpet. The carpets were randomly assigned to one of the four treatment groups. Available treatment regimens for controlling carpet contaminants were evaluated through a literature review and experimentation. Four moderately low-hazard, nondestructive methods were selected as treatments: vacuuming, steam-vapor, Neem oil (a natural tree extract), and benzalkonium chloride (a quaternary ammonium compound). Steam vapor treatment demonstrated the greatest dust mite population reduction (p < 0.05) when compared to other methods. The two physical methods, steam vapor and vacuuming, have no statistically significant efficacy in inactivating dust mite allergens (p = 0.084), but have higher efficacy when compared to the chemical method on dust mite allergens (p = 0.002). There is no statistically significant difference in the efficacy for reducing mold in carpet (p > 0.05) for both physical and chemical methods. The steam-vapor treatment effectively killed dust mites and denatured dust mite allergen in the laboratory environment.

Population growth and allergen accumulation of Dermatophagoides farinae cultured at 20 and 25 °C

House dust mites are cultured to obtain mite allergen material to produce allergen extracts (vaccines) for diagnostic tests, immunotherapy, and research purposes. Research laboratories and manufacturers have their own culturing protocols to grow these mites and these may vary between manufacturers and between research laboratories. The temperature at which mites are cultured may influence the allergen composition, allergen ratio of Der 1: Der 2 and endotoxin levels in the extracts produced from these cultured mites. In order to produce standardized and uniform extracts, across the industry and in various research laboratories, the influence of culture conditions must be understood. Here we determined how temperature affects mite population growth rates, dynamics of allergen production, Der f 1: Der f 2 ratio and endotoxin levels in extracts made from Dermatophagoides farinae mites cultured at 20 and 25 °C. We found that Der f 1 and Der f 2 accumulated exponentially in the cultures with Der f 1 accumulating faster than Der f 2. When the live mite populations peaked, the ratios for Der f 1: Der f 2 were 4.1 and 4.7 for cultures reared at 20 and 25 °C, respectively. Most of the Der f 1 and Der f 2 allergen in whole cultures is not in mite bodies and is lost when the mite material is washed. Thus, if the ratio of Der f 1 and Der f 2 is an important consideration for commercial and research extracts, then the temperature at which the mites are cultured and the collection procedure are important considerations.

Species diversity of house dust mites in Beijing, China

Even though house dust mites are one of the most important allergens, there have been few studies in China for their identification and diversity. In this study, we reported that Dermatophagoides siboney was found for the first time in Beijing, China, in a temperate zone and it was also the first reported in Asia. This survey of mite prevalence was carried out in several districts of Beijing, a city of thirty million people. House dust samples were collected from 38 homes of mite-allergic patients who visited our Allergy Department from December 2008 to January 2010. Out of 345 house dust samples collected, 64% contained mites. Dermatophagoides farinae was the predominant species in the mite population found and Dermatophagoides pteronyssinus was second, and Dermatophagoides siboney was the third. The positive rates of samples were higher in single-story homes and lower buildings. The seasonal density distribution of house dust mites showed the highest mite concentration in September through October, followed by May through July, December to next January; and lowest in March and November.

Climatic factors correlate with innate immune response in children with Dermatophagoides farinae-induced allergic asthma

OBJECTIVE

To determine the effect of climatic factors on immune markers in children with Dermatophagoides farinae induced asthma.

METHODS

Serum concentrations of macrophage migration inhibitory factor (MIF), eosinophil cationic protein (ECP) and D. farinae-specific immunoglobulin E (DF-sIgE), together with peripheral blood eosinophil counts, were measured in children with D. farinae induced (n = 75) or non-D. farinae-induced asthma (n = 17), and in healthy controls (n = 30). Mean temperature and relative humidity in the month before enrolment were calculated from meteorological data.

RESULTS

MIF, ECP and eosinophil counts were significantly higher in children with D. farinae-induced asthma than in controls, but comparable with non-D. farinae-induced asthma. Children with D. farinae-induced asthma in a low temperature (< 16 °C) or low relative humidity (< 70%) climate had significantly lower DF-sIgE, MIF, ECP and eosinophil counts than those in a high temperature or high humidity climate. DF-sIgE correlated positively with MIF, ECP and eosinophil count in D. farinae-induced asthma.

CONCLUSIONS

Temperature and humidity influenced MIF, ECP, eosinophil count and DF-sIgE in D. farinae-induced asthma. Understanding this relationship may provide new strategies for asthma prevention and treatment.

Interference in foraging behaviour of European and American house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae (Acari: Pyroglyphidae) by catmint, Nepeta cataria (Lamiaceae)

The European and American house dust mites, Dermatophagoides pteronyssinus and D. farinae, have a huge impact upon human health worldwide due to being the most important indoor trigger of atopic diseases such as asthma, rhinitis and atopic dermatitis. Preceding studies have shown that the behavioural response of house dust mites towards volatile chemicals from food sources can be assessed using a Y-tube olfactometer assay. In the current study, we used this assay to investigate, for the first time, the ability of the essential oil of the catmint plant, Nepeta cataria (Lamiaceae), known to repel other ectoparasites affecting human and animal health, to interfere with the attraction of D. pteronyssinus and D. farinae towards a standard food source (fish flakes). Two distinct chemotypes (A and B), enriched in the iridoid compounds (4aS,7S,7aR)-nepetalactone and (4aS,7S,7aS)-nepetalactone, and the sesquiterpene (E)-(1R,9S)-caryophyllene, were used. Initial assays with a hexane extract of fish flakes (FF extract) confirmed attraction of mites to this positive control (P < 0.001 and P < 0.05 for D. pteronyssinus and D. farinae respectively), but when presented in combination with either N. cataria chemotype, tested across a range of doses (10, 1, 0.1 and 0.01 μg), decreasing attraction of mites to their food source was observed as the dose augmented. Our study shows that N. cataria, enriched in iridoid nepetalactones and (E)-(1R,9S)-caryophyllene, exhibits potent repellent activity for house dust mites, and has the potential for deployment in control programmes based on interference with normal house dust mite behaviour.

Detection and identification of species-specific bacteria associated with synanthropic mites

Internal bacterial communities of synanthropic mites Acarus siro, Dermatophagoides farinae, Lepidoglyphus destructor, and Tyrophagus putrescentiae (Acari: Astigmata) were analyzed by culturing and culture-independent approaches from specimens obtained from laboratory colonies. Homogenates of surface-sterilized mites were used for cultivation on non-selective agar and DNA extraction. Isolated bacteria were identified by sequencing of the 16S rRNA gene. PCR amplified 16S rRNA genes were analyzed by terminal restriction fragment length polymorphism analysis (T-RFLP) and cloning sequencing. Fluorescence in situ hybridization using universal bacterial probes was used for direct bacterial localization. T-RFLP analysis of 16S rRNA gene revealed distinct species-specific bacterial communities. The results were further confirmed by cloning and sequencing (284 clones). L. destructor and D. farinae showed more diverse communities then A. siro and T. putrescentiae. In the cultivated part of the community, the mean CFUs from four mite species ranged from 5.2 × 10(2) to 1.4 × 10(3) per mite. D. farinae had significantly higher CFUs than the other species. Bacteria were located in the digestive and reproductive tract, parenchymatical tissue, and in bacteriocytes. Among the clones, Bartonella-like bacteria occurring in A. siro and T. putresecentiae represented a distinct group related to Bartonellaceae and to Bartonella-like symbionts of ants. The clones of high similarity to Xenorhabdus cabanillasii were found in L. destructor and D. farinae, and one clone related to Photorhabdus temperata in A. siro. Members of Sphingobacteriales cloned from D. farinae and A. siro clustered with the sequences of "Candidatus Cardinium hertigii" and as a separate novel cluster.

Prevalence of sensitization to Blomia tropicalis among young adults in a temperate climate

BACKGROUND

There are no previous population-based studies assessing the prevalence of Blomia tropicalis (BT). This investigation analyzes the prevalence of sensitization to BT and its contribution to asthma and related diseases among young adults in the Canary Islands.

MATERIAL AND METHODS

From a random sample of 9506 adults, aged between 20 and 44, who had previously answered a short respiratory questionnaire, a further 20% random sample was drawn. All participants filled in an extensive questionnaire, and they underwent spirometry and bronchial hyperresponsiveness (BHR) test and skin testing to several allergens as well as the determination of total IgE and specific IgE.

RESULTS

The prevalence of positive skin tests to BT was 13.8% (95% confidence interval [CI] 10.6-17.9%) and that of BT-specific IgE 17.9% (95% CI 14.2-24.5%). Sensitization to BT (positive skin tests or positive specific IgE) was 20.9% (95% CI 16.9-25.5%). Most of the subjects sensitized to BT were also sensitized to Dermatophagoides pteronissimus; however, only 7% displayed monosensitization to BT. Among subjects who exhibited BHR, sensitization to BT reached 46.7% (95% CI 32.7-60.9%), among those with asthma 50% (95% CI 26.8-73.2%), in subjects with rhinitis 37.2% (95% CI 28.1-47.6%), and in those suffering from dermatitis 25.9% (95% CI 18.7-34.5%). A strong association of BT sensitization with BHR and asthma before and after 15 years was found.

CONCLUSION

The prevalence of sensitization to BT among young adults in the Canary Islands is high, and it displays a close relationship with allergic respiratory diseases and dermatitis.

Mother to child transfer of IgG and IgA antibodies against Dermatophagoides pteronyssinus

There is strong evidence from animal models that placental and/or breast milk-mediated transfer of maternal allergen-specific IgG prevents allergic immune responses in the progeny. Both human and animal data also point to IgA as having an important regulatory role. In contrast, little is known about maternal transfer of IgG and IgA specific for respiratory allergens in humans. Dermatophagoides pteronyssinus (Der p) is an indoor allergen that is a major cause of asthma worldwide. We analysed maternal to child Der p-specific IgG and IgA transfer in a cohort of 77 paired maternal and child samples. We found Der p-specific IgG and its IgG1, IgG2 and IgG4 subclasses in all cord blood samples. Except for IgG1, cord levels were higher in newborns from atopic mothers (n = 29) compared to non-atopic mothers (n = 48). Der p-specific IgA was found in all colostrum samples and levels were independent of maternal atopic status. Notably, anti-Der p IgG was also found in colostrum and levels were higher in atopic mothers. We believe that our work is a critical first step in the identification of early factors that may impact asthma development and should guide the development of clinical studies that assess whether Der p-specific IgG and IgA protect children from allergy as demonstrated in animal models.

Clinical effectiveness of Tyrophagus putrescentiae allergy by local nasal immunotherapy using strips of Dermatophagoides pteronyssinus

BACKGROUND

House dust mites are a major source of aeroallergens for patients with allergic rhinitis and asthma. Most patients with allergic rhinitis are simultaneously sensitized by Dermatophagoides pteronyssinus (Dp) and Tyrophagus putrescentiae (Tp). Dp and Tp allergy in allergic rhinitis can be caused by cross-reactivity, and the group 2 mite allergens appear to be the major cross-reactive allergens in mites. We previously demonstrated that local nasal immunotherapy (LNIT) with Dp-coated strips could modulate the serum levels of Dp-specific IgE. The aim of this study was to investigate whether Tp allergy could be modulated by LNIT with Dp.

METHODS

Both Tyr p2-specific IgE in the sera and its effect on Tyr p2-triggered basophil histamine release (BHR) were measured to evaluate the Tp-mediated allergic reaction before and after LNIT.

RESULTS

The results showed that not only was Tyr p2-specific IgE reduced, but also Tyr p2-triggered histamine release in the sera after LNIT with Dp allergen strips. There was a significant reduction of Tyr p2-specific IgG1 and upregulation of IgG4 after LNIT with Dp allergen strips. When the amounts of histamine were compared between the two groups, rDer p2-triggering or rTyr p2-triggering histamine release was significantly reduced in the Dp treatment group compared with the normal saline treatment group. No matter in the rDer p2-triggering or rTyr p2-triggering histamine release, differences between before LNIT and after LNIT were statistically significant in the Dp group.

CONCLUSION

Our study demonstrated that not only was Tyr p2-specific IgE reduced in the sera, but also its biological activity of Tyr p2-triggered BHR after LNIT with Dp strips. It is conceivable that the clinical effectiveness of Tp allergy by LNIT with Dp allergen strips may exist.

Molecular identification of house dust mites and storage mites

Mites are known causes of allergic diseases. Currently, identification of mites based on morphology is difficult if only one mite is isolated from a (dust) sample, or when only one gender is found, or when the specimen is not intact especially with the loss of the legs. The purpose of this study was to use polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the ITS2 gene, to complement the morphological data for the identification of mites to the species level. For this, six species were cultured: Dermatophagoides pteronyssinus, D. farinae, Blomia tropicalis, Tyrophagus putrescentiae, Aleuroglyphus ovatus and Glycycometus malaysiensis. Genomic DNA of the mites was extracted, quantified, amplified and digested individually with restriction enzymes. Hinf I and Ple I differentiated the restriction patterns of D. pteronyssinus and D. farinae. Bfa I and Alu I enzymes differentiated B. tropicalis and G. malaysiensis. Ple I enzyme was useful for the differentiation between T. putrescentiae and A. ovatus. Bfa I was useful for the differentiation of G. malaysiensis from the rest of the species. In conclusion, different species of mites can be differentiated using PCR-RFLP of ITS2 region. With the established PCR-RFLP method in this study, identification of these mites to the species level is possible even if complete and intact adult specimens of both sexes are not available. As no study to date has reported PCR-RFLP method for the identification of domestic mites, the established method should be validated for the identification of other species of mites that were not included in this study.

House dust and storage mite contamination of dry dog food stored in open bags and sealed boxes in 10 domestic households

Dry pet food is a potential source of exposure to house dust and storage mite allergens in canine atopic dermatitis. This study evaluated contamination of house dust and dry dog food stored in paper bags, sealable plastic bags and sealable plastic boxes in 10 households for 90 days using Acarex(®) tests for guanine, a Der p 1 ELISA and mite flotation. Acarex(®) tests were negative in all the food samples but positive in all the house dust samples. The Der p 1 levels and mite numbers significantly increased in food from paper bags (P = 0.0073 and P = 0.02, respectively), but not plastic bags or boxes. Mite numbers and Der p 1 levels were 10-1000 times higher in house dust than the corresponding food samples (P < 0.0001). There were significant correlations between Der p 1 in house dust and food from the paper (P < 0.0001) and plastic bags (P = 0.003), and mite numbers in house dust and food from the paper bags (P = 0.0007). Bedding and carpets were significantly associated with Der p 1 levels in house dust (P = 0.015 and P = 0.01, respectively), and food from the paper (both P = 0.02) and plastic bags (P = 0.03 and P = 0.04, respectively). Mites were identified in six of 10 paper bag, three of 10 plastic bag, one of 10 plastic box and nine of 10 house dust samples. These comprised Dermatophagoides (54%), Tyrophagus (10%; all from food) and unidentified mites (36%). Storage of food in sealable plastic boxes largely prevented contamination for 3 months. Exposure to mites and mite proteins in all the stored food, however, appeared to be trivial compared with house dust.

Comparison of the skin-prick test and Phadia ImmunoCAP as tools to diagnose house-dust mite allergy

BACKGROUND

When the skin-prick test (SPT) and in vitro test such as ImmunoCAP assay are performed simultaneously, results do not always coincide in some patients. Our objectives, therefore, were (1) to assess differences in allergic test results according to age group and (2) to establish appropriate guidelines for diagnosing mite allergy according to age.

METHODS

A total of 692 participants complaining of allergic rhinitis symptoms participated. Patients were divided according to age; the mean age was 32 years (range, 8-76 years). The SPT and ImmunoCAP assays were performed to detect allergies to house-dust mites (Dermatophagoides pteronyssinus and Dermatophagoides farinae). The association between age and the result of each allergy test were examined, and a cutoff age for proper application of each test was than estimated.

RESULTS

Three hundred thirty-six patients (48.6%) were allergic to D. pteronyssinus and 350 patients (50.6%) were allergic to D. farinae. In the case of D. pteronyssinus, SPT was proved to be more useful in detecting allergy for subjects <50 years old (p < 0.0001). However in case of D. farinae, ImmunoCAP was useful for all age groups, but SPT showed decreased ratio of positive result for subjects >30 years old (p < 0.0001).

CONCLUSION

This study was the first to compare results of allergy tests according to age using true allergens. For patients >50 years of age, the ImmunoCAP was found to be the preferred method for detecting allergy to house-dust mites and for patients <30 years old, SPT is the recommended first choice.

Dermatophagoides pteronyssinus and Tyrophagus putrescentiae allergy in allergic rhinitis caused by cross-reactivity not dual-sensitization

Tyrophagus putrescentiae and Dermatophagoides pteronyssinus are causative factors for the development of airway hypersensitivity. The main objective in this study was to identify the cross-reactive allergens between T. putrescentiae and D. pteronyssinus and investigate their sensitization in patients with allergic rhinitis. The prevalence of sensitization to mites was determined by skin prick tests and histamine release assays. Both immunoblot and ELISA inhibition assays were performed by using the recombinant allergens of T. putrescentiae and D. pteronyssinus. The cross-reactive allergens were identified by using IgE-binding inhibition analysis. The correlations of specific IgE between T. putrescentiae and D. pteronyssinus to group 2 and group 3 mite allergens were compared. A total of 117 allergic rhinitis patients, aged between 16 and 40 years old were recruited to be included in this study. The results showed that 70% (82/117) of allergic rhinitis subjects had skin test positive reactions to D. pteronyssinus or T. putrescentiae. Among these mite-sensitive subjects, there were 81 subjects (81/82) sensitive to D. pteronyssinus and 34 subjects (34/82) sensitive to T. putrescentiae. Among the T. putrescentiae hypersensitive subjects, 97% (33/34) were also sensitized to D. pteronyssinus. In the IgE-binding inhibition analysis, 59% (13/22) subjects had IgE-binding activity of T. putrescentiae that was completely absorbed by D. pteronyssinus, especially components with MW at 16 kDa. In ELISA inhibition testing, 69% of IgE-binding was inhibited by rTyr p 2, and 45% inhibited by rTyr p 3. The titers of IgE antibodies to rTyr p 2 and rDer p 2 were well correlated, but not rTyr p 3 and rDer p 3. In conclusion, most T. putrescentiae sensitized subjects were also sensitized to D. pteronyssinus in young adult allergic rhinitis patients. The complete absorption of IgE binding activity by D. pteronyssinus indicates that T. putrescentiae hypersensitivity might be due to the cross-reactivity, not dual-sensitization of D. pteronyssinus and T. putrescentiae. The IgE-binding titers of group 2 allergens were well correlated and the binding activity of Tyr p 2 could be absorbed by Der p 2, suggesting that group 2 allergens are the major cross-reactive allergen of D. pteronyssinus and T. putrescentiae.

Group 1 and 2 Dermatophagoides house dust mite allergens in the microenvironment of cats

House dust mite allergens (HDMAs) are some of the most common allergens associated with allergic diseases in humans and dogs. The purpose of this study was to determine whether HDMAs could be detected in cat-associated household microenvironments. From 50 cat-only households with 95 cats, dust samples were collected by vacuuming for 2 min m(-2) from three areas where cats slept or rested regularly from September to October 2006. Relative humidity and temperature were measured in each household using a data logger. Each owner completed a questionnaire on potential factors that might influence the prevalence of house dust mites (HDMs). Dust samples were analysed utilizing an ELISA for Der p 1, Der f 1 and HDM group 2 allergens. In 38 of 50 households there was greater than 2 microg g(-1) of dust for at least one HDMA. Using stepwise logistic regression, factors associated with increased HDMA levels included: free-standing houses, number of humans in household, longhaired cats and age of the cat. Factors associated with decreased HDMA concentrations included: forced air heating and central air conditioning, less than 50% carpeting of the home, use of flea control, cats suffering from dermatological disease and the average temperature of the household. Many sleeping/resting areas utilized by cats contain sufficiently high levels of HDMAs to be potential sources of sensitization. This finding should lead to further determination of the role of HDMs in cats suffering from putative allergic conditions such as atopic dermatitis or asthma.

Monitoring and reducing exposure of infants to pollutants in house dust

The health risks to babies from pollutants in house dust may be 100 times greater than for adults. The young ingest more dust and are up to ten times more vulnerable to such exposures. House dust is the main exposure source for infants to allergens, lead, and PBDEs, as well as a major source of exposure to pesticides, PAHs, Gram-negative bacteria, arsenic, cadmium, chromium, phthalates, phenols, and other EDCs, mutagens, and carcinogens. Median or upper percentile concentrations in house dust of lead and several pesticides and PAHs may exceed health-based standards in North America. Early contact with pollutants among the very young is associated with higher rates of chronic illness such as asthma, loss of intelligence, ADHD, and cancer in children and adults. The potential of infants, who live in areas with soil contaminated by automotive and industrial emissions, can be given more protection by improved home cleaning and hand washing. Babies who live in houses built before 1978 have a prospective need for protection against lead exposures; homes built before 1940 have even higher lead exposure risks. The concentration of pollutants in house dust may be 2-32 times higher than that found in the soil near a house. Reducing infant exposures, at this critical time in their development, may reduce lifetime health costs, improve early learning, and increase adult productivity. Some interventions show a very rapid payback. Two large studies provide evidence that home visits to reduce the exposure of children with poorly controlled asthma triggers may return more than 100% on investment in 1 yr in reduced health costs. The tools provided to families during home visits, designed to reduce dust exposures, included vacuum cleaners with dirt finders and HEPA filtration, allergy control bedding covers, high-quality door mats, and HEPA air filters. Infants receive their highest exposure to pollutants in dust at home, where they spend the most time, and where the family has the most mitigation control. Normal vacuum cleaning allows deep dust to build up in carpets where it can be brought to the surface and become airborne as a result of activity on the carpet. Vacuums with dirt finders allow families to use the three-spot test to monitor deep dust, which can reinforce good cleaning habits. Motivated families that receive home visits from trained outreach workers can monitor and reduce dust exposures by 90% or more in 1 wk. The cost of such visits is low considering the reduction of risks achieved. Improved home cleaning is one of the first results observed among families who receive home visits from MHEs and CHWs. We believe that proven intervention methods can reduce the exposure of infants to pollutants in house dust, while recognizing that much remains to be learned about improving the effectiveness of such methods.

Dust mites: using data from an intervention study to suggest future research needs and directions

Dermatophagoides farinae (Der f 1; referred as Der f hereafter) and D. pteronyssinus (Der p 1; referred as Der p hereafter) are common allergy-causing mites found in homes worldwide. Mites are more prevalent in humid climates, but are rare or absent in drier climates. Levels of dust mite sensitivity have been reported between 48% and 63% for asthmatic children. Dose-response relations between levels of dust-mite exposure and sensitivity have been reported; yet, relatively high levels of dust mite sensitivity (50%-60%) have been found in populations exposed to concentrations below the proposed cut-point sensitization concentration of 2 microg dust mite per gram of dust. A meta-analysis of 49 trials involving 2733 patients found that interventions for dust mite-control did not result in any clinical benefit to mite-sensitive asthmatics. We assessed the impact of replacing old mattresses with dust-mite resistant mattresses on dust-mite levels, and to a more limited extent, on health outcomes. Replacement mattresses were provided to 44 asthmatic children residing in public housing in inner city Boston, Massachusetts. At baseline, we found concentrations to exceed the cut point of 2 microg g(-1) in only 9% of beds for Der p and 16% for Der f. Only 7% of beds for Der f and 5% for Der p exceeded 10 microg g(-1). Dust-mite allergy levels were high in these asthmatic children (54% for Der f and 62% for Der p) despite low baseline mattress levels. Our intervention reduced Der p (p = 0.026) and Der f (p < 0.001) below their low starting levels. Investigations are needed that (1) evaluate the reduction of dust-mite levels below the suggested cutpoints for sensitization and exacerbation; (2) assess the impact of reduction of multiple antigens; (3) assess exposure to dust mites outside of the home; and (4) test bundled interventions.

House dust and forage mite allergens and their role in human and canine atopic dermatitis

This article reviews the literature regarding the role of house dust and forage mite allergens in canine atopic dermatitis. The presence of immunoglobulin E (IgE) to these mites, especially to Dermatophagoides farinae, is common in both normal and atopic dogs. Exposure of dogs to the different mites is described both in the direct environment and in the coat of animals for house dust mites and in the food for forage mites. Allergens causing allergic disease in dogs seem to be different from those in humans. Dogs seem to react to high molecular weight allergens, compared to the low molecular weight group 1 and group 2 proteases that are commonly implicated in humans with atopic diseases. Despite numerous published studies dealing with this subject, a number of questions still need to be addressed to better understand the exact role of these mites in the pathogenesis of canine atopic dermatitis and to improve the quality of the allergens used in practice.

Induction of atopic eczema/dermatitis syndrome-like skin lesions by repeated topical application of a crude extract of Dermatophagoides pteronyssinus in NC/Nga mice

Mite antigen has been considered to play important roles in the development of atopic eczema/dermatitis syndrome (AEDS). In the present study, we attempted to induce an AEDS-like skin lesion in mice using Dermatophagoides pteronyssinus crude extract (DPE) as an antigen and performed pathophysiological evaluations. Ears of mice were tape-stripped and DPE was painted 3 times a week. Eczematous skin lesion and ear swelling were apparent in NC/Nga mice treated with DPE after 2 weeks, whereas neither skin lesion nor ear swelling were observed in BALB/c mice even after 30 days. Histological evaluation demonstrated that edema, epidermal hyperplasia and the accumulation of inflammatory cells were apparent in the ears of DPE-treated NC/Nga mice. In contrast to skin lesion and ear swelling, total serum IgE levels were increased in both NC/Nga and BALB/c mice. Treatment with DPE also increased auricular lymph node weight in both NC/Nga mice and BALB/c mice. To further characterize, we analyzed cytokine mRNA expression in ears and lymph nodes of DPE-treated NC/Nga mice. Increased expression of IL-4 and TNF-alpha mRNA was observed in both ears and lymph nodes of NC/Nga mice treated with DPE. Additionally, there was no change in the responsiveness of BALB/c mice to DPE treatment by adaptive transfer of serum from DPE-treated NC/Nga mice to BALB/c mice. Taken together, our results indicate that eczematous skin lesion and ear swelling caused by repeated application of DPE in NC/Nga mice has a Th2-dominant background and that inflammation is involved in this process. The animal model of AEDS established in this report may be used to investigate the pathogenesis of AEDS and evaluate the potential therapeutic agents for AEDS.

Production and Proteomic Characterization of Pharmaceutical-Grade Dermatophagoides pteronyssinus and Dermatophagoides farinae Extracts for Allergy Vaccines

BACKGROUND

House dust mites (HDM) such as Dermatophagoides pteronyssinus and Dermatophagoides farinae represent a major cause of type 1 allergies worldwide. Hence large quantities of well-characterized HDM extracts are needed to prepare pharmaceutical-grade allergy vaccines. To this aim, the present study was undertaken to define optimal conditions for large-scale cultures.

METHODS

D. pteronyssinus and D. farinae were grown on different media combining various proportions of wheat germ, yeast and synthetic amino acids (the latter resembling the composition of the human stratum corneum). Extracts thus obtained were analyzed for their total allergenic activity, as well as major allergen and protein contents, using immunosorbent assays, HPLC, immunoblotting, two-dimensional electrophoresis and peptide mass fingerprinting.

RESULTS

An optimal culture medium (Stalmite APF) based on wheat germ, yeast and amino acids in defined proportion (42, 42 and 15% w/w, respectively) was selected to grow various HDM species with high yields. A detailed proteomic analysis revealed that D. pteronyssinus extracts generated under such conditions did not contain allergens originating from culture medium components and that major prevalent HDM allergens (i.e. groups 1, 2, 7, 10, 13 and 20) are found among the most abundant proteins in the D. pteronyssinus extract. Semiquantitative dot-blot assays confirmed the presence of Der p 3-10 as well as Der p 13 and 14 allergens within the extracts.

CONCLUSIONS

We developed a well-defined medium allowing to grow various HDM species at an industrial scale in a highly reproducible manner. Extracts from mites produced under such pharmaceutical conditions contain all the relevant allergens for desensitization purposes and in vivo diagnosis.

Prevalence of the group 1 Dermatophagoides allergens Der p 1 and Der f 1 in homes with no dogs, healthy dogs and Dermatophagoides-sensitized atopic dogs in Liverpool

Dermatophagoides farinae is a frequent allergen in canine atopic dermatitis despite its reported scarcity in the UK, and the aim of this study was to determine whether dogs were uniquely exposed to this species. Der f 1 and Der p 1 in dust collected from living room carpets, bedroom carpets and dog beds of 13 houses with no dogs, 13 with healthy dogs, and 16 with Dermatophagoides-sensitized atopic dogs were quantified by ELISA. Der p 1 levels (microg g(-1) house dust) were significantly higher than Der f 1 in living rooms (Der p 1 median = 1.9, 95% CI = 2.05-6.32, n = 42; Der f 1 median = 0.07, 95% CI = 0.01-0.06, n = 42), bedrooms (Der p 1 median = 4.35, SD = 5.52; Der f 1 median = 0.01, 95% CI = 0.001-0.1, n = 42) and dog beds (Der p 1 median = 1.04, 95% CI = 1.4-8.1, n = 29; Der f 1 median = 0.008, 95% CI = 0.01-0.04, n = 29) (P < 0.0001). Living rooms in houses without dogs had significantly greater Der p 1 levels (median = 7.0, 95% CI = 3.53-15.8, n = 13) than houses with healthy (median = 1.19, 95% CI = 0.44-3.49, n = 13) or atopic dogs (median = 0.78, 95% CI = 0.63-2.42, n = 16) (P = 0.0004). Environmental flea control in living rooms and washing dog beds was associated with significantly reduced Der p 1 levels. This confirms that D. pteronyssinus is common but D. farinae is rare in the sampling area. Apparent sensitization to D. farinae is probably due to cross-reaction. A combination of environmental measures could reduce allergen exposure.

Arthropods in dermatology

Arthropods are important in medicine for a multitude of reasons. Their bites and stings may induce allergic reactions, ranging from annoying to life-threatening. Many arthropod products are also capable of inciting allergic responses in sensitized persons. In recent years, bites and stings have gained greater attention owing to increased concern about disease transmission. A common hypersensitivity response to arthropod bites, stings, and products is papular urticaria. This eruption occurs primarily in children, who eventually "outgrow" this disease, probably through desensitization after multiple arthropod exposures. Papular urticaria is most often caused by fleas or bedbugs, but virtually any arthropod is capable of inducing such a reaction. Two arthropod classes of medical importance are the Arachnida (spiders, scorpions, ticks, and mites) and the Insecta (lice, fleas, bedbugs, flies, bees, and ants). Animals in these two classes are probably responsible for more morbidity and mortality worldwide than are any other group of venomous creatures. In general, the diagnosis of arthropod bites and stings is dependent on maintenance of a high index of suspicion and familiarity with the arthropod fauna not only in one's region of practice, but also in the travel regions of one's patients. Learning objective At the completion of this learning activity, participants should be familiar with the clinical manifestations caused by a variety of arthropods as well as the treatment and possible sequelae of arthropod attacks.