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

Association of Mite Molecular Sensitization Profiles with Respiratory Allergies and Asthma Control in Children from East China

Background

Allergic conditions, identified as a significant global health challenge, are profoundly influenced by indoor allergens, especially house dust mites (HDM). Yet the relationship between mite sensitized components and respiratory allergies and asthma control remains poorly understood.

Methods

A cohort of 96 children, either with allergic rhinitis (AR) or rhinitis with asthma syndrome (ARAS), was assessed. Protein microarray technology was deployed to quantify sIgE responses to the allergenic components of Der p and Der f.

Results

The study cohort comprised 18 AR and 78 ARAS patients; with 43 mild and 53 moderate-to-severe AR; with 28 uncontrolled, 21 partially controlled, and 29 well-controlled asthma. Sensitization prevalence for HDM components was highest with Der p (97.9%), Der f 2 (97.9%), Der p 2 (94.8%), Der f 1(94.8%), Der p 1 (93.8%), Der p 23 (57.3%). Notably, sIgE concentrations for Der f and Der f 2 were significantly greater in the ARAS compared to AR (P < 0.05). While sIgE levels varied between mild and moderate-to-severe AR, the differences were not statistically significant (P > 0.05). However, Der p 23 sIgE levels demonstrated a significant fluctuation across the asthma control strata (P < 0.05), with the well-controlled group exhibiting the lowest readings.

Conclusion

The sIgE levels to HDM allergens were higher in ARAS group compared to AR group, especially Der f and Der f 2, indicating an association between sIgE reactivity and the diagnosis of asthma. Reduced Der p 23 sIgE levels were indicative of enhanced asthma control.

The Influence of Indoor Environmental Factors on the Prevalence of House Dust Mites as Aeroallergens in Bandar Abbas Student Dormitories, South of Iran, 2019

This study was conducted to determine the influence of environmental factors on the prevalence of house dust mites in student dormitories of Bandar Abbas city. In this study, 64 dust samples were collected from seven randomly selected dormitories located in various areas of the Bandar Abbas. The collected mites were isolated and mounted in Hoyer's medium and identified using a morphological key. The associations between the environmental factors and the density of house dust mites were investigated. In total, 1,093 adult mites were collected and identified. They consisted of four species including Dermatophagoides pteronyssinus Trouessart (57.6%), Dermatophagoides farinae Hughes (24.3%) and Dermatophagoides evansi Fain (14.9%) (Acari: Pyroglyphidae), and Cheyletus malaccensis Oudemans (3.2%) (Acari: Cheyletidae). All of the dormitories were contaminated by more than one house dust mites species and the mean density of house dust mites in dormitories was 8.3 ± 0.2 mites/g of dust. There was a significant relationship between average house dust mites density and some of environmental factors such as relative humidity, temperature, floor covering type, and number of occupants (P < 0.05). Results of this study revealed that two major allergenic dust mites, D. pteronyssinus and D. farinae, were the most prevalent and collected from all of dormitories and some of indoor environmental factors found to influence mites' population.

Influence of storage conditions on the infestation of Tyrophagus putrescentiae and prevalence of mite hypersensitivity in Taiwan

Sensitization to mites is a considerable factor in the development of allergic diseases. Because of its abundance, Tyrophagus putrescentiae (Tp) is the predominant storage mite found in home storage rooms, kitchens, and bakeries. Patients allergic to mites might exhibit a severely hypersensitive reaction upon ingesting Tp-contaminated food. The objective of this study was to investigate the rates of Tp contamination in commercial storage products from various areas, storage conditions, and environments in Taiwan. A specific antibody against Tyr p 3, the allergen on Tp, could be used as an indicator to monitor the contamination condition in storage foods. The microscopic mite examination, allergen detection by ELISA and cultured mite chemotaxis were used to evaluate the prevalence of T. putrescentiae contamination. Moreover, the IgE responses of patients allergic to mites were examined. We found that pet food and mushrooms were commonly contaminated with Tp, and this was validated through Tyr p 3 concentration and chemotaxis experiments. Tp contamination rates decreased significantly when samples were sealed and stored at a low temperature (<  4 °C), low relative humidity (RH < 60%), or for longer periods at a low temperature. The results of the clinical study indicated that the mites that elicited major positive IgE responses in allergic subjects were Dermatophagoides pteronyssinus and D. farinae. Thus, people who are sensitized to D. pteronyssinus or D. farinae might be at risk of a second anaphylactic reaction due to cross-reactivity upon ingestion of Tp-contaminated food. Accordingly, Tp contamination can be prevented by keeping food packages sealed and stored at a low temperature. This prevents the severe allergic reaction caused by the inadvertent ingestion of contaminated food-borne Tp.

Principles of Allergen Immunotherapy and Its Clinical Application in China: Contrasts and Comparisons with the USA

Allergen immunotherapy (AIT) for allergic rhinitis (AR), asthma, and other allergic diseases has developed quickly. House dust mite (HDM), Artemisia (wormwood), Humulus japonicus (Japanese hop), Alternaria alternata, and Cladosporium herbarum are the five most common inhalant allergens in China. AIT has been performed in China for over 60 years. With the support of the Chinese Medical Association (CMA) and the Chinese Medical Doctors Association (CMDA), the Chinese College of Allergy and Asthma (CCAA) was established in 2016 as a specialized branch of CDMA and is the main certification authority for AIT. Chinese allergists and scientists have made tremendous progress in the development of AIT. There have been many publications by Chinese allergists and scientists worldwide encompassing original research studies, systematic reviews, case studies, and clinical trials. Currently, conventional subcutaneous immunotherapy (SCIT) is the preferred AIT in China, but sublingual immunotherapy (SLIT) is beginning to gain recognition. An increasing number of clinical trials have been conducted to investigate the clinical efficacy and side effects of SLIT and SCIT. In China, HDM is the only commercial standardized allergen extracts in clinical use, whereas the others are crude allergen extracts. Besides standardized allergen extracts, other forms of hypoallergenic extracts are still being investigated and developed in China. Immunotherapy in China is similar to that in the USA in which allergen extracts can be mixed for SCIT. However, allergen extracts cannot be mixed for SCIT in Europe.

Detection and identification of dust mite allergens in the air conditioning filters in Chandigarh, India

Modern lifestyle with the increasing use of air conditioner (AC) has been linked with breathing difficulties, irritation, dryness, and other symptoms. Hence, dust mites were isolated from AC filters, which causes allergic diseases. A total of 95 dust samples were collected from AC filters from hospitals, guest house, office, school, and homes in Chandigarh, India. The highest concentration of dust mites was detected from hospitals (9/g), offices (7/g), households (6/g), guest houses (3/g), and schools (0/g). Based on the morphology of dust mites observed under a light microscope, Dermatophagoides and Acarus species were found most common. Indoor air quality was also monitored to find out their relation with dust mites present in AC filters. Further, the respiratory health status of indoor facility users was also assessed using a standard questionnaire as a study tool. It was seen that 55.3% of male among the total respondents were having an allergy and only 44.7% of the females had an allergy. The allergy among the male respondents (55.3%) was significantly more (p < 0.05) in comparison with female respondents (44.7%). Some of the respondents also reported a family history of rhinitis (31.9%), asthma (12.8%), recurrent urticaria (6.4%), and conjunctivitis (6.4%). Interestingly, 23.4% of study participants reported that they get disturbed by the use of AC and house dust was found to be the most triggering factor in enhancing the symptoms of allergy. Thus, it is recommended that air conditioner filters should be cleaned regularly to prevent the accumulation of the dust mites and related allergens on filter dust.

House dust mites among allergic patients at the Allergy and Immunology Unit, Zagazig University: an immunologic and serologic study

In the twenty-first century, the occurrence of allergic diseases has increased. Prevention and control of house dust mites (HDMs) are required as they play a major role in allergic conditions. The present work aimed to detect HDM allergy (Dermatophagoides pteronyssinus and Dermatophagoides farinae) among allergic patients attending the Allergy and Immunology Unit, Zagazig University. Ninety-six patients with a history of allergic diseases were included in this study. They were examined for allergy to D. pteronyssinus and D. farinae using different diagnostic tools: the skin prick test (SPT) and measurement of specific IgE antibodies to HDM allergen extracts. Ninety-six allergic patients were recruited in this study [60 females (62.5%) and 36 males (37.5%) aged between 5-60 years]. SPT (81.2 and 79.2%) and IgE (70.9 and 75%) gave positive results for both D. pteronyssinus and D. pteronyssinus, respectively. The common risk factors were use of cotton bedding > 10 years old, older homes > 20 years, crowded homes, family history, home dampness and homes at the ground floor. It was concluded that allergies to D. pteronyssinus and D. farinae contribute to allergic diseases in Zagazig City. Use of the SPT and IgE level is a promising diagnostic tool in the diagnosis of D. pteronyssinus and D. farinae.

[Blomia tropicalis: A house dust mite in the tropics]

INTRODUCTION

Blomia tropicalis is a mite that belongs to the superfamily of Glycyphagidae. Initially described as a storage mite, it is now considered as a house dust mite of tropical and sub-tropical areas.

STATE OF THE ART

Sensitization to this mite is very common in South America and Southeast Asia. Epidemiological studies have also found sensitization to this mite in Africa and Central America. Blo t 5 is the major allergen of B. tropicalis. Co-sensitization to other house dust mites such as Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) is very common. Cross-reactivity has been described but recombinant allergens revealed by molecular biology techniques do not explain this cross-reactivity. Sensitization to B. tropicalis seems to begin at the age of 36 months, the incidence increases until adulthood, and decreases from the age of 50. The involvement of B. tropicalis in allergic rhinitis and asthma is well described. It is also implicated in other allergic diseases. Few studies have assessed the therapeutic strategies available against this mite but immunotherapy is widely used.

PERSPECTIVES

Studies are needed to better understand the role of B. tropicalis in human diseases and to develop specific treatments.

Semi-depot house-dust mite allergen extract for Chinese with allergic rhinitis and asthma

BACKGROUND

Real-world data of the subcutaneous immunotherapy (SCIT) with semi-depot house-dust mite (HDM) allergen extract (a HDM allergen extract that contains a 50%-50% mixture of Dermatophagoides pteronyssinus and Dermatophagoides farina) for allergic rhinitis and asthma was unavailable in China until recently.

AIM

To investigate the effectiveness and safety of a HDM-SCIT for allergic rhinitis and asthma in Chinese patients.

METHODS

A multicenter, single-arm, open-label, self-controlled study. Chinese patients with allergic rhinitis or allergic asthma and with a history of symptoms from HDM exposure were included and received allergen-specific immunotherapy for 1 year by subcutaneous injection of HDM-SCIT. The primary outcome measure was the percentage of patients with an improvement in symptom severity assessed at 12 months after initiation of the treatment. The occurrence of adverse events and compliance of treatment were also evaluated.

RESULTS

A total of 272 outpatients were included for effectiveness analysis. The subject-evaluated improvement rate in the visual analog scale (VAS) was 76.1% and 71.3% at 6 and 12 months, respectively; corresponding values for investigator-evaluated VAS were 77.9% and 71.7%, respectively (p < 0.0001). Symptom score changes were -2.43 and -3.79 at 6 and 12 months, respectively (both p < 0.0001); the VAS improvement rate and symptom score change did not differ significantly between children and adolescents and/or adults. Good injection schedule adherence was found in 98.8% of the patients. No study drug-related serious adverse events or serious systemic allergic reactions occurred.

CONCLUSION

HDM-SCIT was safe and effective in the treatment of allergic rhinitis and asthma in a Chinese population, with good compliance.

Neonatal Immune State Is Influenced by Maternal Allergic Rhinitis and Associated With Regulatory T cells

Purpose

Maternal influences contribute to the origin of allergic diseases, but the mechanisms are not clear. The current literature prompted the role of epigenetics in the development of allergic diseases. We sought to investigate the roles of regulatory T (Treg) cells and Forkhead box p3 (Foxp3) DNA methylation in the process of maternal transmission of allergic rhinitis (AR) susceptibility.

Methods

BALB/c female mice (AR mother) were sensitized by intraperitoneal injection of Dermatophagoides pteronyssinus (Der p) 1 on day 1 and 7. Then they mated with normal male mice on day 8. From day 21 to 28, the female mice were intranasal challenged with Der p 1 continuously. The normal controls were given with normal saline in the same way. On postnatal day 3, Female mice and their offspring were sacrificed to detect their histopathology in nasal mucosae, cytokines in sera of mother and spleen homogenates of offspring, Treg cells count, Foxp3 mRNA expressions, and Foxp3 DNA methylation levels in spleens.

Results

Compared with the normal controls, neonatal offspring of Der p 1-stimulated female mice (AR offspring) showed the elevation of interleukin (IL)-4 (P<0.01) and IL-17 (P<0.01), the submission of IL-10 (P<0.01) in spleen homogenates. Further, Treg cells count in AR offspring decreased remarkably compared with the normal offspring (P<0.01). Though the difference of Foxp3 DNA methylation level between AR offspring and normal control offspring was not obvious, correlation analysis demonstrated that there was significantly positive correlation between Foxp3 DNA methylation level of mother and that of offspring (r=0.803, P<0.01).

Conclusions

Under the influence of Maternal AR, their neonatal offspring develop into T-helper type 2 (Th2) dominant immune state, which is closely associated with the recession of Treg cells. Foxp3 DNA methylation may be a mechanism responsible for that maternal effect but still need more studies to ensure.

Particularities of allergy in the Tropics

Allergic diseases are distributed worldwide and their risk factors and triggers vary according to geographical and socioeconomic conditions. Allergies are frequent in the Tropics but aspects of their prevalence, natural history, risk factors, sensitizers and triggers are not well defined and some are expected to be different from those in temperate zone countries. The aim of this review is to investigate if allergic diseases in the Tropics have particularities that deserve special attention for research and clinical practice. Such information will help to form a better understanding of the pathogenesis, diagnosis and management of allergic diseases in the Tropics. As expected, we found particularities in the Tropics that merit further study because they strongly affect the natural history of common allergic diseases; most of them related to climate conditions that favor permanent exposure to mite allergens, helminth infections and stinging insects. In addition, we detected several unmet needs in important areas which should be investigated and solved by collaborative efforts led by the emergent research groups on allergy from tropical countries.