House Dust Mite Allergy Under Changing Environments

Impact of climate change on aerobiology, rhinitis, and allergen immunotherapy: Work Group Report from the Aerobiology, Rhinitis, Rhinosinusitis & Ocular Allergy, and Immunotherapy, Allergen Standardization & Allergy Diagnostics Committees of the American Academy of Allergy, Asthma & Immunology

Climate change is imposing a profound effect on health conditions triggered by environmental exposures. Climate change has affected aeroallergens in numerous ways, including: (1) changes in the vegetation microbiome distribution, (2) increases in C4 grasses globally, (3) increased occurrence of acute weather events, (4) increases in ambient temperature that amplify fungal spore concentration and pollen season duration, and (5) increased allergenicity of pollen and fungi due to exposure to higher levels of carbon dioxide, ozone, and diesel exhaust particles. In addition, greenhouse gases and air pollutants disrupt the epithelial barrier, trigger eosinophilic inflammation, and serve as adjuvants that stimulate IgE-mediated responses. All of these factors have influenced the prevalence and morbidity of allergic rhinitis, nonallergic rhinitis, and chronic rhinosinusitis. Data regarding changes in aeroallergen exposures due to climate change are lacking, and longitudinal sensitization data are rarely available. Allergists need to adapt diagnostic and treatment strategies to limit aeroallergen and air pollutant exposure and facilitate desensitization. Steps needed to address these challenges include: (1) expanding local measurement of pollen and fungal spores, (2) increasing the intensity of allergen avoidance measures, (3) addressing supply chain issues, and (4) promoting collaboration between allergists, insurance companies, aeroallergen manufacturers, and regulatory agencies.

Climate Change and Allergens: Current and Future Impacts

Climate change will continue to impact allergic diseases in direct and indirect ways. Rising global temperatures are contributing to increased duration of pollen seasons, altered aeroallergen production and potency of allergens, and changes in the geographic distribution of allergenic plants that drive increased human exposure to aeroallergens and increased allergic disease morbidity. Climate change is inextricably linked with air pollution, the latter of which was shown to act as an adjuvant for allergic inflammatory processes promoting allergic sensitization. Pollutant exposure is also linked with higher prevalence of childhood asthma and exacerbation of existing asthma and allergic disease. Increased exposure, or co-exposure, to aeroallergens and air pollution as a result of climate change will result in higher rates of sensitization, and incident allergic disease remains uncertain. Vulnerable populations, including children, the elderly, and marginalized groups, are likely to be disproportionately affected. This review summarizes the current knowledge of the effects of climate change on aeroallergens, and by extension, allergic disease. Addressing these health challenges requires a comprehensive understanding of the interaction between climate change, allergens, pollution and public health, alongside proactive measures to mitigate these effects.

CMPK2 promotes NLRP3 inflammasome activation via mtDNA-STING pathway in house dust mite-induced allergic rhinitis

BACKGROUND

House dust mite (HDM) is the leading allergen for allergic rhinitis (AR). Although allergic sensitisation by inhaled allergens renders susceptible individuals prone to developing AR, the molecular mechanisms driving this process remain incompletely elucidated.

OBJECTIVE

This study aimed to elucidate the molecular mechanisms underlying HDM-induced AR.

METHODS

We examined the expression of cytidine/uridine monophosphate kinase 2 (CMPK2), STING and the NLRP3 inflammasome in both AR patients and mice. Additionally, we investigated the role of CMPK2 and STING in the activation of the NLRP3 inflammasome in AR.

RESULTS

The expression of CMPK2, STING and the NLRP3 inflammasome was significantly increased in the nasal mucosa of AR patients compared to non-AR controls. A positive correlation was found between CMPK2 expression and the levels of STING, NLRP3, ASC, CASP1 and IL-1β. HDM treatment up-regulated the expression of CMPK2, and CMPK2 overexpression enhanced NLRP3 inflammasome activation in human nasal epithelial cells (HNEPCs). Additionally, mitochondrial reactive oxygen species (mtROS) production following HDM exposure contributed to mitochondrial dysfunction and the release of mitochondrial DNA (mtDNA), which activated the cyclic GMP-AMP synthase (cGAS)-STING pathway. Remarkably, depletion of mtDNA or inhibition of STING signalling reduced HDM-induced NLRP3 inflammasome activation in HNEPCs. In vivo, genetic knockout of CMPK2 or STING alleviated NLRP3 inflammasome activation and ameliorated clinical symptoms of AR in mice.

CONCLUSIONS

Our results suggest that HDM promotes the activation of NLRP3 inflammasome through the up-regulation of CMPK2 and ensuing mtDNA-STING signalling pathway, hence revealing additional therapeutic target for AR.

KEY POINTS

Cytidine/uridine monophosphate kinase 2 (CMPK2) expression is up-regulated in the nasal mucosa of patients and mice with allergic rhinitis (AR). CMPK2 caused NLRP3 inflammasome activation via mitochondrial DNA (mtDNA)-STING pathway. Blocking CMPK2 or STING signalling significantly reduced the activation of NLRP3 in house dust mite (HDM)-challenged mice and human nasal epithelial cells (HNEPCs).

V Brazilian Consensus on Rhinitis - 2024

Since we published the "IV Brazilian Consensus on Rhinitis", in2017, several advances have been achieved and have enabled a further understanding of the different aspects of "Rhinitis". This new guideline, developed jointly by ASBAI, SBP and SBORL, represents a relevant milestone in the updated and integrated management of the different forms of the disease, and it aims to unify evidence-based approaches to improve the diagnosis and treatment of this common and often underestimated condition. The document covers a wide range of topics, including clear definitions of the different phenotypes and endotypes of rhinitis, risk factors, updated diagnostic criteria, and recommended methods for clinical and laboratory investigation. We stress the importance of detailed clinical history and objective assessment, as well as tools for control and assessing severity tools an accurate diagnostic approach to the disease. Regarding treatment, it emphasizes the treatment customization, considering the severity of symptoms, the presence of comorbidities and the impact on the patient's quality of life. We discuss different drug treatment, in addition to non-pharmacological measures, such as environmental control and specific immunotherapy; and the possible role of immunobiological agents. Furthermore, the consensus addresses issues related to patient education, prevention and management of special situations, such as rhinitis in children, in pregnant women and in the elderly. In short, the "V Brazilian Consensus on Rhinitis" represents a comprehensive and updated guide for healthcare professionals involved in the diagnosis and management of rhinitis, aiming to improve patients' quality of life through an integrated and evidence-based approach.

Molecular Signatures of Aeroallergen Sensitization in Respiratory Allergy: A Comparative Study Across Climate-Matched Populations

Climate change is significantly altering the dynamics of airborne allergens, affecting their seasonality, allergenicity, and geographic distribution, which correlates with increasing rates of allergic diseases. This study investigates aeroallergen sensitization among populations from Tenerife, Spain, and Lima, Peru-two regions with similar climates but distinct socio-economic conditions. Our findings reveal that Spanish individuals, particularly those with asthma, demonstrate higher sensitization levels to a broader range of allergens, especially mites, with 85% of participants reacting to at least one mite allergen. In contrast, Peruvian patients exhibit a narrower spectrum of sensitization. These results highlight the influence of environmental factors, such as pollution and socio-economic disparities, on allergen exposure and immune responses. Moreover, this study underscores the necessity for region-specific diagnostic and therapeutic strategies to effectively address these variations. By elucidating the intricate relationship between climate change, environmental factors, and allergen sensitization, this research offers insights into respiratory allergic conditions, advocating for tailored interventions to mitigate their impact across diverse populations.

Blomia tropicalis: A 50-Year History

The genus Blomia tropicalis was described 50 years ago. Since then, great progress has been made on the clinical impact of this house dust mite (HDM). Blomia tropicalis is widely distributed in tropical and subtropical zones, where it induces IgE sensitization and clinical symptoms. The discovery of this mite not only provided additional support for the causal relationship between HDM sensitization and allergic respiratory symptoms, it changed the scope of the diagnosis and management of these diseases. There are now 26 officially accepted B tropicalis allergens, several of them with cross-reactivity with mites such as Dermatophagoides spp and some storage mites, which adds complexity to the diagnosis of sensitization and the choice of extracts for allergen specific immunotherapy. Fortunately, the discovery and characterization of molecules useful for component-resolved diagnostic testing provide the tools for this challenge. Immunotherapy with B tropicalis extract is successfully used in several countries of Latin America, Africa, and Asia; however, the availability of standardized extracts in subtropical regions remains limited. During the 50 years of research on B tropicalis, several groups have made contributions to allergen characterization, their mechanisms of action and clinical impact; the immunogenetics of sensitization; the possible effects of climate change; and the design and testing of new vaccines.

Minimizing Indoor Allergen Exposure: What Works?

PURPOSE OF REVIEW

Allergic rhinitis and asthma morbidity has been linked to indoor allergen exposure. Common indoor allergens include dust mites, cats, dogs, rodents, and cockroaches. These allergens are ubiquitous and often difficult to remove from the home, making long-lasting reduction strategies difficult to achieve. Identifying strategies for reducing the presence of indoor allergens in homes could be utilized to decrease allergic disease burden, improve symptomology, reduce healthcare costs, and improve patients' quality of life.

RECENT FINDINGS

Studies have yielded mixed results with regard to specific environmental control measures in reducing indoor allergen levels and in improving clinical outcomes of allergic disease. In this review, we assess the available evidence of the effectiveness of environmental control measures in reducing indoor allergens and the potential clinical impact of these measures.

Global change, climate change, and asthma in children: Direct and indirect effects - A WAO Pediatric Asthma Committee Report

The twenty-first century has seen a fundamental shift in disease epidemiology with anthropogenic environmental change emerging as the likely dominant factor affecting the distribution and severity of current and future human disease. This is especially true of allergic diseases and asthma with their intimate relationship with the natural environment. Climate change-related variables including increased ambient temperature, heat waves, extreme weather events, air pollution, and rainfall distribution, all can directly affect asthma in children, but each of these variables also indirectly affects asthma via alterations in pollen production and release, outdoor allergen exposure or the microbiome. Air pollution, with its many and varied respiratory consequences, is likely to have the greatest effect, as it has increased globally due to rapid increases in fossil fuel combustion, global population, crowding, and megacities, as well as forest burning and trees succumbing to an increasingly hostile environment. Human activities have also caused substantial deterioration of the global microbiome with reductions in biodiversity for molds, bacteria, and viruses. Reduced microbiome diversity has, in turn, been associated with increases in Th2 allergic responses and allergic disease. The collective effect of these changes has already shifted allergy and asthma disease patterns. Given that changes in climate have been relatively small to date, the unavoidable, much greater shifts in climate in the future are concerning. Determining the relative scale of the direct versus indirect effects of climate change variables is needed if effective avoidance and adaptive measures are to be implemented. This would also require much more basic, epidemiological, and clinical research to understand the causal mechanisms, the most relevant climate factors involved, the regions most affected and, most importantly, effective and actionable adaptation measures. We suggest that allergy and respiratory health workers should follow current guidance to reduce present risks related to climate change and watch for new recommendations to reduce future risks. Since the respiratory system is the one most affected by climate change, they also need to call for more research in this area and show strong leadership in advocating for urgent action to protect children by reducing or reversing factors that have led to our deteriorating climate.

House dust mite allergens, store-operated Ca2+ channels and asthma

The house dust mite is the principal source of aero-allergen worldwide. Exposure to mite-derived allergens is associated with the development of asthma in susceptible individuals, and the majority of asthmatics are allergic to the mite. Mite-derived allergens are functionally diverse and activate multiple cell types within the lung that result in chronic inflammation. Allergens activate store-operated Ca2+ release-activated Ca2+ (CRAC) channels, which are widely expressed in multiple cell types within the lung that are associated with the pathogenesis of asthma. Opening of CRAC channels stimulates Ca2+-dependent transcription factors, including nuclear factor of activated T cells and nuclear factor-κB, which drive expression of a plethora of pro-inflammatory cytokines and chemokines that help to sustain chronic inflammation. Here, I describe drivers of asthma, properties of mite-derived allergens, how the allergens are recognized by cells, the signalling pathways used by the receptors and how these are transduced into functional effects, with a focus on CRAC channels. In vivo experiments that demonstrate the effectiveness of targeting CRAC channels as a potential new therapy for treating mite-induced asthma are also discussed, in tandem with other possible approaches.

Mesenchymal stromal cells dampen trained immunity in house dust mite-primed macrophages expressing human macrophage migration inhibitory factor polymorphism

BACKGROUND

Trained immunity results in long-term immunological memory, provoking a faster and greater immune response when innate immune cells encounter a secondary, often heterologous, stimulus. We have previously shown that house dust mite (HDM)-induced innate training is amplified in mice expressing the human macrophage migration inhibitory factor (MIF) CATT7 functional polymorphism.

AIM

This study investigated the ability of mesenchymal stromal cells (MSCs) to modulate MIF-driven trained immunity both in vitro and in vivo.

METHODS

Compared with wild-type mice, in vivo HDM-primed bone marrow-derived macrophages (BMDMs) from CATT7 mice expressed significantly higher levels of M1-associated genes following lipopolysaccharide stimulation ex vivo. Co-cultures of CATT7 BMDMs with MSCs suppressed this HDM-primed effect, with tumor necrosis factor alpha (TNF-α) being significantly decreased in a cyclooxygenase 2 (COX-2)-dependent manner. Interestingly, interleukin 6 (IL-6) was suppressed by MSCs independently of COX-2. In an in vitro training assay, MSCs significantly abrogated the enhanced production of pro-inflammatory cytokines by HDM-trained CATT7 BMDMs when co-cultured at the time of HDM stimulus on day 0, displaying their therapeutic efficacy in modulating an overzealous human MIF-dependent immune response. Utilizing an in vivo model of HDM-induced trained immunity, MSCs administered systemically on day 10 and day 11 suppressed this trained phenomenon by significantly reducing TNF-α and reducing IL-6 and C-C motif chemokine ligand 17 (CCL17) production.

CONCLUSIONS

This novel study elucidates how MSCs can attenuate an MIF-driven, HDM-trained response in CATT7 mice in a model of allergic airway inflammation.

Discovery and demonstration of the temperature stress response functions of Dermatophagoides farinae proteins 1 and 2

BACKGROUND

Dermatophagoides farinae proteins (DFPs) are abundantly expressed in D. farinae; however, their functions remain unknown. Our previous transcriptome sequencing analyses revealed that the basal expression of DFP1 and DFP2 in D. farinae was high and, more importantly, upregulated under temperature stress. Therefore, DFPs were speculated to exert a temperature stress response function.

RESULTS

Real-time quantitative polymerase chain reaction detection revealed that both DFP1 and DFP2 were significantly upregulated under temperature stress. Particularly, DFP1 was upregulated under cold stress. Electrophoresis of D. farinae total proteins revealed an increased abundance of DFP1 and DFP2 (40-55 kDa bands) under temperature stress, which was corroborated by the mass spectrometry results. After silencing DFP1 and DFP2 further, temperature stress led to decreases in gene expression and survival rates. Moreover, DFP1 was identified as the upstream regulator of DFP2.

CONCLUSION

This study highlights the temperature stress response functions of DFP1 and DFP2 at the mRNA and protein levels. These results provide important insights for applying DFP1 and DFP2 as potential target genes for the molecular prevention and control of D. farinae to prevent allergic diseases. The newly established methods provide methodological guidance for the study of genes with unknown functions in mites.

The bacterial microbiome and resistome of house dust mites in Irish homes

Dust samples were collected from Irish homes. House Dust Mite and storage mites were separated from the dust. The microbiome and resistome of mites and originating dust were assessed using a culture-independent approach. The bacterial microbiome of mites and dust were predominantly populated by Staphylococci. There was a highly significant (P = 0.005; Spearman's rank test) correlation between the bacterial microbiome of mites and the dust. One-hundred and eighteen antimicrobial resistance genes (ARGs) were associated with mites and 176 with dust. Both contained ARGs encoding resistance for multi drug resistances, macrolide-lincosamide-streptogramin B, mobile genetic elements, Beta-lactam, Tetracycline and Aminoglycosides. By contrast, 15 ARGs were found for a laboratory-grown strain of Dermatophagoides pteronyssinus. A significant difference (P = 0.03; t test) was found in means between the resistome of mites and the household dust from which they emanated. No significant correlations (P = 0.23 and P = 0.22; Mantel test) were observed between the microbiome and resistome of mite and dust samples. There was not a significant difference (P = 0.54; t-test) between the means of ARGs for homes with and without a history of antibiotic use.

Climate change from the Asia-Pacific perspective: What an allergist needs to know and do

Allergic diseases such as asthma, atopic dermatitis, and food allergies are a burgeoning health challenge in the Asia-Pacific region. Compounding this, the region has become increasingly susceptible to the impacts of climate change. The region has weathered extreme precipitation, intense heat waves, and dust storms over the recent decades. While the effects of environmental and genetic factors on allergic diseases are well understood, prevailing gaps in understanding the complex interactions between climate change and these factors remain. We aim to provide insights into the various pathways by which climate change influences allergic diseases in the Asia-Pacific population. We outline practical steps that allergists can take to reduce the carbon footprint of their practice on both a systemic and patient-specific level. We recommend that allergists optimize disease control to reduce the resources required for each patient's care, which contributes to reducing greenhouse gas emissions. We encourage the responsible prescription of metered dose inhalers by promoting the switch to dry powder inhalers for certain patients, at each clinician's discretion. We also recommend the utilization of virtual consultations to reduce patient travel while ensuring that evidence-based guidelines for rational allergy management are closely adhered to. Finally, eliminating unnecessary testing and medications will also reduce greenhouse gas emissions in many areas of medical care.

Recent prevalence of allergic rhinitis caused by house dust mites among the pediatric population in Fukui, Japan

Background

Allergic rhinitis (AR) is an IgE-mediated type I allergic chronic nasal disease common among all age groups, including the pediatric population. House dust mites (HDMs) are globally ubiquitous and the most important indoor aeroallergen. However, the recent prevalence of HDM-caused AR (AR-HDM) in Japan remains unknown, especially after the COVID-19 pandemic.

Objective

The objective of this study was to investigate the current prevalence of AR-HDM, its clinical features, and the current status of medical examinations in elementary school students.

Methods

A survey of 41,000 elementary school students was conducted during July 2021 in Fukui Prefecture, Japan. Parents were asked to complete a questionnaire that examined allergic disease history and clinical background.

Results

A total of 17,974 subjects were analyzed in the study. The results showed that the current prevalence of AR-HDM in elementary school children is 18.8%. We found that AR-HDM had already developed before entrance into elementary school in 68.3% of affected subjects. Among these subjects, 82.3% had received some form of treatment, such as prescription medications, whereas 4.2% were treated by allergen immunotherapy. Multiple logistic regression analysis of the onset of AR-HDM revealed that male sex, being the first-born child, comorbidity of bronchial asthma, atopic dermatitis, food allergy, and allergic conjunctivitis are associated with development of AR-HDM.

Conclusions

The present study revealed the prevalence of AR-HDM in elementary school children. The results emphasize the importance of appropriate diagnosis and treatment from infancy through early childhood.

Association Between Clinical Remission of Infantile-Onset Allergic Rhinitis During the School-Age Period and the Type of Housing: A Longitudinal Population-Based Japanese Study

This study investigated the association between housing type and clinical remission of infantile-onset allergic rhinitis (AR) in 53,575 children born in 2001 in Japan. Infantile-onset AR was defined as the presence of AR symptoms reported between ages 1.5 and 4.5 years, and remission was assessed between ages 10 and 12. The type of housing was categorized into detached houses and multi-unit residential buildings with 1-2, 3-5, or ≥6 floors. Among the 4,352 infantile-onset AR, 42.9% experienced remission. Notably, living in multi-unit residential buildings, particularly those with 1-2 and ≥6 floors, was positively associated with AR remission.

Tyrosine nitration enhances the allergenic potential of house dust mite allergen Der p 2

Nitration of allergenic proteins caused by atmospheric pollutants O3 and NO2 may enhance their allergenic potential. In the study, the influence of nitration was investigated on the allergenicity of Der p 2, which is a main allergen from house dust mites and plays an important role in allergenic rhinitis and asthma. The results reveal that nitrated Der p 2 enhanced the IgE-binding capacity, upregulated the mRNA expression and release of IL-6 and IL-8 from bronchial epithelial cells, and induced higher levels of specific-IgE, TH2 cytokines and white blood cells in mice. Besides, nitrated Der p 2 caused more severe oxidative stress and allergenic symptoms in mice. It is concluded that nitration enhanced the allergenicity of Der p 2 through not only directly inducing higher amount of specific-IgE and stronger responses of TH2 cytokines, but also indirectly aggravating allergic symptoms by oxidative stress and adjuvant-like activation airway epithelial cells. The study suggests that the contribution of nitration to the promotion in allergenicity should not be ignored when precisely assessing the risk of house dust mite allergens in real environment.

Up-regulation of HSP90α in HDM-induced asthma causes pyroptosis of airway epithelial cells by activating the cGAS-STING-ER stress pathway

Heat Shock protein 90 α (HSP90α), an main subtype of chaperone protein HSP90, involves important biological functions such as DNA damage repair, protein modification, innate immunity. However, the potential role of HSP90α in asthma occurrence and development is still unclear. This study aimed to elucidate the underlying mechanism of HSP90α in asthma by focusing on the cGAS-STING-Endoplasmic Reticulum stress pathway in inflammatory airway epithelial cell death (i.e., pyroptosis; inflammatory cell death). To accomplish that, we modeled allergen exposure in C57/6BL mice and bronchial epithelial cells with house dust mite. Protein technologies and immunofluorescence utilized to study the expression of HSP90α, activation of cGAS-STING pathway and pyroptosis. The effect of inhibitors on HDM-exposed mice detected by histological techniques and examination of bronchoalveolar lavage fluid. Results showed that HSP90α promotes asthma inflammation via pyroptosis and activation of the cGAS-STING-ER stress pathway. Treatment with the HSP90 inhibitor tanespimycin (17-AAG) significantly relieved airway inflammation and abrogated the effect of HSP90α on pyroptosis and cGAS-STING-ER stress in vitro and in vivo models of HDM. Further data indicated that up-regulation of HSP90α stabilized STING through interaction, which increased localization of STING on the ER. Activation of STING triggered ER stress and leaded to pyroptosis-related airway inflammation. The finding showed the potential role of pyroptosis caused by dysregulation of HSP90α on airway epithelial cells in allergic inflammation, suggested that targeting HSP90α in airway epithelial cells might prove to be a potential additional treatment strategy for asthma.

The Prevention of House Dust Mite Allergies in Pediatric Asthma

This review provides a concise overview of preventive measures against dust mite allergies in pediatric populations, emphasizing the need for a comprehensive and evolving approach. Dust mites, ubiquitous microscopic arachnids, pose a significant threat to children's health, triggering allergies and asthma. Traditional preventive strategies such as regular cleaning, mattress covers, and humidity control are essential but warrant refinement. Empowering children through personalized hygiene education and exploring innovative bedding solutions showcase a forward-thinking paradigm. Collaboration with healthcare professionals and embracing technology-driven solutions ensures a holistic and adaptable approach to safeguarding pediatric health against dust mite-related ailments. This abstract underscores the importance of continually reassessing and innovating preventive measures to create resilient and health-conscious living environments for children.

Heterogeneity of sensitization profiles and clinical phenotypes among patients with seasonal allergic rhinitis in Southern European countries-The @IT.2020 multicenter study

BACKGROUND

Pollen allergy poses a significant health and economic burden in Europe. Disease patterns are relatively homogeneous within Central and Northern European countries. However, no study broadly assessed the features of seasonal allergic rhinitis (SAR) across different Southern European countries with a standardized approach.

OBJECTIVE

To describe sensitization profiles and clinical phenotypes of pollen allergic patients in nine Southern European cities with a uniform methodological approach.

METHODS

Within the @IT.2020 multicenter observational study, pediatric and adult patients suffering from SAR were recruited in nine urban study centers located in seven countries. Clinical questionnaires, skin prick tests (SPT) and specific IgE (sIgE) tests with a customized multiplex assay (Euroimmun Labordiagnostika, Lübeck, Germany) were performed.

RESULTS

Three hundred forty-eight children (mean age 13.1 years, SD: 2.4 years) and 467 adults (mean age 35.7 years SD: 10.0 years) with a predominantly moderate to severe, persistent phenotype of SAR were recruited. Grass pollen major allergenic molecules (Phl p 1 and/or Phl p 5) ranged among the top three sensitizers in all study centers. Sensitization profiles were very heterogeneous, considering that patients in Rome were highly poly-sensitized (sIgE to 3.8 major allergenic molecules per patient), while mono-sensitization was prominent and heterogeneous in other cities, such as Marseille (sIgE to Cup a 1: n = 55/80, 68.8%) and Messina (sIgE to Par j 2: n = 47/82, 57.3%). Co-sensitization to perennial allergens, as well as allergic comorbidities also broadly varied between study centers.

CONCLUSIONS

In Southern European countries, pollen allergy is heterogeneous in terms of sensitization profiles and clinical manifestations. Despite the complexity, a unique molecular, multiplex, and customized in-vitro IgE test detected relevant sensitization in all study centers. Nevertheless, this geographical diversity in pollen allergic patients imposes localized clinical guidelines and study protocols for clinical trials of SAR in this climatically complex region.

Impact of climate change on paediatric respiratory health: pollutants and aeroallergens

Paediatric populations are particularly vulnerable to respiratory diseases caused and exacerbated by aeroallergens, pollutants and infectious agents. Worsening climate change is expected to increase the prevalence of pollutants and aeroallergens while amplifying disease severity and causing disproportionate effects in under-resourced areas. The purpose of this narrative review is to summarise the role of anthropogenic climate change in the literature examining the future impact of aeroallergens, pollutants and infectious agents on paediatric respiratory diseases with a focus on equitable disease mitigation. The aeroallergens selected for discussion include pollen, dust mites and mould as these are prevalent triggers of paediatric asthma worldwide. Human rhinovirus and respiratory syncytial virus are key viruses interacting with climate change and pollution and are primary causal agents of viral respiratory disease. Within this review, we present the propensity for aeroallergens, climate change and pollution to synergistically exacerbate paediatric respiratory disease and outline measures that can ameliorate the expected increase in morbidity and severity of disease through a health equity lens. We support shifting from fossil fuels to renewable energy worldwide, across sectors, as a primary means of reducing increases in morbidity.

Multiplexed transcriptional profiling of Dermatophagoides house dust mites allergens in human epithelium cells

Allergic asthma, a chronic disease characterized by airway inflammation, poses a significant public health concern. It is well-established that house dust mites (HDMs) are common inducers of allergic responses in individuals, particularly children. In central Taiwan, our research team observed that over 80% of allergic children exhibited sensitization to various HDMs species. This investigation aims to bridge the gap between these observations and a better understanding of the early fundamental mechanisms for preventing allergic diseases. Specifically, our study delves into the impact of crude extracts of HDMs on human epithelial BEAS-2B cells. Our findings, based on RNA sequencing (RNA-seq) analysis, shed light on how three major Dermatophagoides HDMs allergens activate a common Toll-like receptor signaling pathway in human epithelial cells within a 4-h treatment. During this process, the nuclear transcription factor NF-κB translocated into the cell nucleus within 30 min of allergen stimulation, triggering the expression of pro-inflammatory genes such as IL-6 and IL-8 over 4 h. Additionally, when the cells were treated with specific Dermatophagoides microceras (Der m) allergens, it resulted in the upregulation of genes that regulate type 1 diabetes mellitus (T1DM) signaling pathways. This led to the mediation of IL-12A inflammation. Furthermore, there was an increase in gene sets associated with cilia function and the microtubule cytoskeleton in human epithelial cells after treatment with a combination of Der m allergens and Dexamethasone. Additionally, OMICs analysis was conducted to examine the effects of HDMs allergenic stimulation on human epidermal cells. We aimed to improve our understanding of the molecular mechanisms within cells and identify potential targets and natural products in the treatment of asthma caused by HDMs allergens.

Effects of household vectors on child health and its determinants in southwest, Ethiopia correspondence analysis

Background

Household vectors transmit pathogens from one child to another. This study aimed to investigate the prevalence and determinants of household vectors on child health.

Methods

A community-based cross-sectional study design was conducted, during which a total of 846 household data were collected using a pretested questionnaire and simple random sampling technique. The data was entered into EpiData3.4 and then exported to Stata 14 software for analysis. A multivariable logistic regression analysis was conducted to identify significant factors associated with household vectors that contribute child health problems. The correspondence analysis was used to determine statistically significant effects or associations between household vectors and child health problems, that was explained by the percentage of variance.

Results

This study revealed that the prevalence of household vector effects among children was 35.5% suchas itching, allergies, nuisances and aesthetically displeasing factors. Households with no formal education were significantly 36% less likely to be affected compared to their counterparts (AOR 0.64, 95% CI 0.41, 0.99). Housewives are significantly 2.21 times more likely to be bexposed to household vectors compared to government workers (AOR 2.21, 95% CI 1.23, 3.70). Caregivers who had limited awareness of household vectors were 98.6% less likely to be affected compared to their counterparts (AOR 0.014; 95% CI 0.01-0.04). Similarly, children from households that consumed less than 20 liters of water per individual were 1.45 times more likely to be at risk compared to children from households that consumed more water (AOR 1.45, 95% CI 1.02, 2.07). The infestations of household vectors were found to be statistically significant and were associated with the occurrence of child health problems. This significant association accounted for 86.8 percent of the explained variance.

Conclusion

Addressing the high burden of household vectors on child health requires interventions that target informal education, limited access to information, and inadequate access to safe water. Implementing effective vector control measures is crucial to reduce the incidence of vector-borne diseases among children.

Plant and Arthropod IgE-Binding Papain-like Cysteine Proteases: Multiple Contributions to Allergenicity

Papain-like cysteine proteases are widespread and can be detected in all domains of life. They share structural and enzymatic properties with the group's namesake member, papain. They show a broad range of protein substrates and are involved in several biological processes. These proteases are widely exploited for food, pharmaceutical, chemical and cosmetic biotechnological applications. However, some of them are known to cause allergic reactions. In this context, the objective of this review is to report an overview of some general properties of papain-like cysteine proteases and to highlight their contributions to allergy reactions observed in humans. For instance, the literature shows that their proteolytic activity can cause an increase in tissue permeability, which favours the crossing of allergens through the skin, intestinal and respiratory barriers. The observation that allergy to PLCPs is mostly detected for inhaled proteins is in line with the reports describing mite homologs, such as Der p 1 and Der f 1, as major allergens showing a frequent correlation between sensitisation and clinical allergic reactions. In contrast, the plant food homologs are often digested in the gastrointestinal tract. Therefore, they only rarely can cause allergic reactions in humans. Accordingly, they are reported mainly as a cause of occupational diseases.

Tropical high altitude and severe asthma in adults: house dust mite sensitization and phenotypic distribution

BACKGROUND

There is a lack of information on house dust mite (HDM) sensitization and phenotype distribution in patients with severe asthma (SA) living permanently at high-altitude (HA) in tropical regions, which may be different.

OBJECTIVE

The aim of this study was to characterize adults with SA in a tropical high altitude city (2,640 m): Bogotá, Colombia.

MATERIAL AND METHODS

This observational cross-sectional study included severe asthmatic outpatients (n = 129) referred to the ASMAIRE program of the Fundación Neumológica Colombiana in Bogotá (2,640 m). Clinical history, spirometry, total IgE, blood eosinophils, and skin prick test (SPT), including HDM allergens, were performed. Phenotype definitions: Allergic/atopic (AA): IgE ≥100 IU/mL and/or at least one positive SPT; eosinophilic (EOS): blood eosinophils ≥300 cells/µL; type 2-high: AA and/or EOS phenotype; type 2-low: non-AA/non-EOS phenotype (IgE <100 IU/mL, negative SPT, and blood eosinophils <300 cells/µL).

RESULTS

A total of 129 adults with SA were included, 79.8% female. Phenotype distribution: AA: 61.2%; EOS: 37.2%; type 2-high: 72.1%; type 2-low: 27.9%. Among AA patients, HDM sensitization was present in 87% and 34.9% were non-eosinophilic. There was a significant overlap between the phenotypes.

CONCLUSIONS

In contrast to non-tropical high-altitude regions, we found a high frequency of HDM sensitization in patients with AA phenotype living in a tropical high-altitude city. We also found a discrete lower frequency of EOS phenotype with no other significant differences in the phenotypic distribution compared to that described at low altitudes. We propose that tropical location may modify the effect of high altitude on HDM concentrations and allergenicity.

Correlation of Blomia tropicalis-specific immunoglobulin epsilon profiles with family history of atopy in a Filipino population

Background

House dust mites are the major source of indoor allergens in the tropical and subtropical regions with Blomia tropicalis (Bt) allergens as one of the leading causative agents of sensitization among patients from the tropics. Despite the clinical importance of Bt in various populations, its allergenicity remains unclear among Filipino allergic patients.

Objective

This study determined the sensitization profiles of allergic Filipinos against Bt allergens and its correlation with atopy.

Methods

Total immunoglobulin epsilon (IgE) (n = 960), Bt-specific IgE (n = 247), and Blomia tropicalis 5 (Blo t 5)-specific IgE (n = 87) profiles of allergic and nonallergic subjects were measured through enzyme-linked immunosorbent assay (ELISA). Point-biserial correlation coefficient was used to determine the association between Bt-specific IgE levels and selected demographics. Inhibition ELISA was performed to measure the inhibition capacity of recombinant Blo t 5 (rBlo t 5) against Bt allergen extracts.

Results

Mean total IgE levels of allergic cases (n = 171) were significantly higher (P < 0.001) compared to the mean IgE levels of nonallergic controls (n = 76). Among allergic subjects, 58% were sensitized to Blo t extract and 80% of which were sensitized to rBlo t 5 allergen. A positive correlation was observed between Bt-specific IgE and family history of atopic disease (P = 0.031). Inhibition assay revealed that 54% mean reactivity of 7 plasma samples was caused by rBlo t 5, validating that rBlo t 5 is a major allergen in Bt.

Conclusions

This study has shown the importance of Bt as an allergen source that sensitizes atopic Filipino subjects. Hence, inclusion of Bt allergen extract and rBlo t 5 in the panel for allergy diagnosis and immunotherapy in Filipino populations is strongly recommended.

Residual profiles and health risk of indoor allergens in China

Exposure to indoor allergens is a principal risk factor for allergic diseases. However, most of the previous studies on indoor allergens focused on very limited kinds of allergens in China. Knowledge of the simultaneous exposure to multiple allergens is still lacking. In this study, the residual profiles of 8 allergens were investigated in 166 dust samples from 11 cities in China. The house dust mite allergens including Der p 1, Der f 1, and Der 2 were detected in the range of <0.02-283.83 μg/g dust. The concentrations of dog allergen Can f 1 and cat allergen Fel d 1 varied widely, from <0.84-22,896.46 μg/g dust for Can f 1 and from <0.02-6298.96 μg/g dust for Fel d 1. Cockroach allergen Bla g 2 was detected in 68% of the samples but at a low level with a maximum of 9.44 μg/g dust. Comparatively low detection frequencies were found for mouse allergen Mus m 1 as 37% and for fungi allergen Asp f 2 as 24%. The frequency of cleaning sheets/bedding was negatively correlated to the levels of house dust mite allergens. The presence of pets indoors was associated with higher levels of pet allergens and lower levels of house dust mite allergens and cockroach allergen. Risk evaluation reveals that at least 4 allergens were found in more than 80% of the rooms and more than 2 allergens with median/high risk were detected in 42% of the rooms, indicating that simultaneous exposure to multiple allergens is prevalent in China.

Climate Change, Exposome Change, and Allergy: A Review

Climate change is a major threat to human respiratory health and associated allergic disorders given its broad impact on the exposome. Climate change can affect exposure to allergens, such as pollen, dust mites, molds, as well as other factors such as temperature, air pollution, and nutritional factors, which synergistically impact the immune response to these allergens. Exposome change can differentially exacerbate allergic reactions across subgroups of populations, especially those who are more vulnerable to environmental stressors. Understanding links between climate change and health impacts can help inform how to protect individuals and vulnerable populations from adverse health effects.

House dust mite allergy in Malaysia: review of research gaps in the current scenario and the way forward

The prevalence of house dust mite (HDM) allergy, especially in Asian countries with rapid urbanization, has been increasing. House dust mites thrive in places with relatively high humidity. With the combination of climate change, naturally high humidity, and urbanization, tropical countries like Malaysia are becoming a hotspot for HDM allergy fast. With a previously reported sensitization rate of between 60 and 80%, it is a worrying trend for Malaysia. However, due to incomplete and out-of-date data, as seen by the limited study coverage in the past, these numbers do not paint a complete picture of the true HDM allergy scene in Malaysia. This review briefly discusses the HDM fauna, the HDM sensitization rate, the common diagnosis and therapeutic tools for HDM allergy in Malaysia, and makes suggestions for possible improvements in the future. This review also highlights the need of more comprehensive population-based prevalence studies to be done in Malaysia, encompassing the three main HDMs-Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Blomia tropicalis-as the lack of up-to-date studies failed to give a clearer picture on the current scenario of HDM allergy in Malaysia. Future studies will be beneficial to the nation in preparing a better blueprint for the management and treatment of HDM allergy.

The meteorological contrast index in the context of climate change and public health

In the context of climate change, extreme weather events and sudden shifts in weather patterns are becoming increasingly frequent. The atmosphere is considered a source of meteorological and climatic risks for human beings and living organisms. Numerous studies have examined the correlation between meteorological variables and human morbidity and mortality. However, only a few authors have investigated the impact of environmental changes on human health and, to our knowledge, there are no meteorological indices proposing a methodology for assessing changes in atmospheric conditions. Under the hypothesis that meteorological disruptions have an impact on human health, this article proposes a method to calculate a new index, the Meteorological Contrast Index (MCI), based on weather changes. This index takes into account three variables: i) categorization based on the type of atmospheric process, ii) changes in these categories over a specific time period, and iii) the level of stress associated with these changes, considering the severity of the transition from one category to another. If the predictive value of this index is proven for a specific meteorological variable and disease, it could be valuable in defining biometeorological early warning systems for the prevention and management of healthcare resources.•The Meteorological Contrast Index is the first index that proposes a method to assess changes in atmospheric conditions.•Atmospheric changes are a significant source of biometeorological distress, which can be quantitatively defined using the Meteorological Contrast Index.•Certain diseases are sensitive to the weather, and their incidence may increase under specific sequences of weather types.

Association between living habits, indoor humidity, ventilation and asthma among residents in the tropical regions of China

OBJECTIVE

Asthma is a major public health problem that affects both children and adults, and its prevalence varies among people with different climatic characteristics and living habits. However, few studies have investigated the prevalence and risk factors for asthma among tropical residents in China. Therefore, this study aims to investigate the correlation between individuals' living environment and daily habits in Hainan Province, and the occurrence of asthma.

METHODS

This cross-sectional study collected data from 1021 participants in three regions of the Hainan Province. A questionnaire derived from the European Community Respiratory Health Survey was used to collect data on demographics, living habits, self-reported asthma, and respiratory system-related symptoms. Logistic regression was used for univariate and multivariate analyses to screen for relative risk factors associated with asthma.

RESULTS

Among the 1,021 subjects investigated, the prevalence rate of self-reported asthma was 18.6%. Significant risk factors for asthma include hair dyeing, longer living time in Hainan, higher BMI, and living in a damp and musty room. Protective factors included fruit intake, years of higher education, and indoor timing of natural ventilation.

CONCLUSION

Higher frequency of hair dyeing, higher body mass index (BMI), longer living in Hainan, lower frequency of fruit intake, fewer years of education, a damp and musty room, and no indoor timing natural ventilation were associated with an increased risk of asthma.

A novel dose-adjustment protocol for interrupted subcutaneous immunotherapy for allergic rhinitis

Background: This study aimed to develop a novel dose strategy for subcutaneous immunotherapy to reduce medical waste and financial burdens for patients who are required to restart subcutaneous immunotherapy. Patients & methods: A prospective, nonrandomized concurrent controlled trial was performed to assess the safety and advantages of the novel dose-adjustment protocol compared with the conventional one. 76 subjects were grouped to receive novel or conventional dose-adjustment protocols. Results: The injections, visits and time needed to reach the pre-established dose with the novel regimen were decreased. Furthermore, there were no differences in side reactions between the two groups. Conclusion: The novel protocol seemed safe and well tolerated, offering the advantages of time efficiency and reduced healthcare costs.

TFOS Lifestyle Report: Impact of environmental conditions on the ocular surface

Environmental risk factors that have an impact on the ocular surface were reviewed and associations with age and sex, race/ethnicity, geographical area, seasonality, prevalence and possible interactions between risk factors are reviewed. Environmental factors can be (a) climate-related: temperature, humidity, wind speed, altitude, dew point, ultraviolet light, and allergen or (b) outdoor and indoor pollution: gases, particulate matter, and other sources of airborne pollutants. Temperature affects ocular surface homeostasis directly and indirectly, precipitating ocular surface diseases and/or symptoms, including trachoma. Humidity is negatively associated with dry eye disease. There is little data on wind speed and dewpoint. High altitude and ultraviolet light exposure are associated with pterygium, ocular surface degenerations and neoplastic disease. Pollution is associated with dry eye disease and conjunctivitis. Primary Sjögren syndrome is associated with exposure to chemical solvents. Living within a potential zone of active volcanic eruption is associated with eye irritation. Indoor pollution, "sick" building or house can also be associated with eye irritation. Most ocular surface conditions are multifactorial, and several environmental factors may contribute to specific diseases. A systematic review was conducted to answer the following research question: "What are the associations between outdoor environment pollution and signs or symptoms of dry eye disease in humans?" Dry eye disease is associated with air pollution (from NO2) and soil pollution (from chromium), but not from air pollution from CO or PM10. Future research should adequately account for confounders, follow up over time, and report results separately for ocular surface findings, including signs and symptoms.

Factors associated with allergic rhinitis and combined allergic rhinitis and asthma syndrome (CARAS) in adults undergoing immunotherapy in a tropical country: Is ISAAC-III questionnaire useful in adult populations?

BACKGROUND

Allergic diseases affect about 10-30% of the population in low- or middle-income tropical countries. Few studies describe the factors associated with allergic diseases in adult patients undergoing immunotherapy in Latin American countries.

OBJECTIVE

This study aimed to determine the factors associated with allergic rhinitis (AR) and AR in comorbidity with asthma (CARAS) in adults treated with immunotherapy in two allergy referral centers in Bogotá (Colombia).

MATERIAL AND METHODS

Observational, cross-sectional study conducted between January 2018 and January 2019. ISAAC-III and sociodemographic questionnaires were applied to determine the factors associated with AR and CARAS in adults treated with immunotherapy who attended the allergy consult at the Fundación Santa Fe de Bogotá and Unimeq-Orl.

RESULTS

Among 416 adults aged 18-68 years, 71.4% (n = 297) were women. Regarding the sensitization results obtained by skin prick test, the most frequent allergens were house dust mites (64.18%): 49.03% were positive for both Dermatophagoides pteronyssinus and Dermatophagoides farinae, while 28.61% were positive for Blomia tropicalis. Excluding house dust mites, the most frequent allergens were dog hair (31.01%), cat hair (15.1%), grasses (15.9%), and food (15.9%). The main factor associated with exclusive AR was regular acetaminophen use more than four times a year: Prevalence ratio (PR) = 1.77 (95% CI: 1.12-2.25). The main factor associated with CARAS was cesarean delivery PR: 1.44 (95% CI: 1.09-1.78).

CONCLUSION

The main factor associated with AR was regular acetaminophen use, while that associated with CARAS was cesarean delivery. The ISAAC-III questionnaire can be a useful low-cost tool to assess the factors associated with allergic diseases in adults in tropical countries.

The Relationship of Parasite Allergens to Allergic Diseases

PURPOSE OF REVIEW

Helminth infections modify the natural history of allergic diseases, by either decreasing or increasing their symptoms. Several helminth components are involved in the increasing of the allergic response and symptoms, overcoming the concomitant immunosuppression of helminthiases. However, the role of individual IgE-binding molecules in this process remains to be defined.

RECENT FINDINGS

We updated the list of helminth allergens and IgE-binding molecules, their effects on asthma presentation, and their impact on allergy diagnosis. Data from genetic and epigenetic studies of ascariasis are analyzed. A new species-specific A. lumbricoides allergen has been discovered, with potential use in molecular diagnosis. Most helminth IgE-binding components are not officially classified as allergens in the WHO/IUIS database, although there is evidence of their influence increasing allergic manifestations. Further immunological characterization of these components is needed to better understand their mechanisms of action and evaluate the ways in which they can influence the diagnosis of allergy.

Molecular Mapping of Allergen Exposome among Different Atopic Phenotypes

Climate change and exposure to environmental pollutants play a key role in the onset and aggravation of allergic diseases. As different climate-dependent patterns of molecular immunoglobulin E (IgE) reactivity have been regionally described, we sought to investigate the evolving allergen exposome in distinctive allergic phenotypes and subtropical weather conditions through a Precision Allergy Molecular Diagnosis (PAMD@) model. Concurrent sensitization to several house dust mites (HDM) and storage mite molecules were broadly dominant in the investigated cohort, followed by the major cat allergen Fel d 1, and regardless of the basal allergic disease. Although a complex repertoire of allergens was recognized, a steadily increasing number of IgE binding molecules was associated with the complexity of the underlying atopic disease. Besides the highly prevalent IgE responses to major HDM allergens, Der p 21, Der p 5, and Der p 7 also showed up as serodominant molecules, especially in subjects bothered by asthma and atopic dermatitis. The accurate characterization of the external exposome at the molecular level and their putative role as clinically relevant allergens is essential to elucidate the phenotypic diversity of atopic disease in terms of personalized diagnosis and therapy.

Site-specific tyrosine nitration of group 1 allergens of house dust mite Dermatophagoides farinae (der f 1) and Dermatophagoides pteronyssinus (der p 1) in indoor dusts

Nitration can enhance the allergenicity of proteins. The nitration status of house dust mite (HDM) allergens in indoor dusts, however, remains to be elucidated. In the study, site-specific tyrosine nitration degrees of the two important HDM allergens Der f 1 and Der p 1 in indoor dust samples were investigated by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The measured concentrations of native and nitrated allergens in the dusts were in the range of 0.86-29 μg g^-1 for Der f 1 and from below the detection limit to 29 μg g^-1 for Der p 1. Site-specific analysis revealed that all ten tyrosine residues in Der f 1 and Der p 1 were nitrated to different degrees in the investigated samples. The preferred nitration sites were Y₅₆ in Der f 1 and Y₃₇ in Der p 1 with the nitration degrees of 7.6-84% and 17-96% among the detected tyrosine residues, respectively. The measurements reveal high site-specific nitration degrees for tyrosine in Der f 1 and Der p 1 detected in the indoor dust samples. Further investigations are required to find out if the nitration really aggravates the health effects of HDM allergens and if the effects are tyrosine site-dependent.

[Geographical variation of asthma prevalence among Mexican children during the COVID-19 pandemic]

OBJECTIVE

The purpose of this study was to analyze the geographic variation in the prevalence of asthma in children, according to their place of residence in Mexico.

METHODS

A cross-sectional analysis of the epidemiological surveillance system dataset for respiratory diseases in Mexico carried on. From 27 February to 5 November 2020, a total of 1,048,576 subjects were screened for SARS-CoV2 infection, of which 35,899 were children under 18 years of age. The strength of the association was estimated by odds ratio (OR).

RESULTS

Of 1,048,576 patients who attended for SARS-CoV2 infection detection, 35,899 corresponded to pediatric patients who met the study criteria. The estimated national prevalence of asthma was 3.9% (95% CI: 3.7-4.1%). The nationwide prevalence of asthma was 3.9% (95% CI: 3.7% - 4.1%); the minimum was 2.8% (Southeast region) and the maximum 6.8% (Southeast region). Compared to the South-West Region that presented the minimum prevalence at the national level, the Northwest (OR = 2.41) and Southeast (OR = 1.33) regions showed the highest risk of asthma in pediatric population.

CONCLUSIONS

The prevalence of asthma in children differed markedly among the different regions of Mexico; two regions, Northwest and Southeast, stood out. This study puts into context the role of the environment on the prevalence of asthma in children.

The HDM allergen orchestra and its cysteine protease maestro: Stimulators of kaleidoscopic innate immune responses

House dust mite (HDM) encloses an explosive cocktail of allergenic proteins sensitizing hundreds of millions of people worldwide. To date, the innate cellular and molecular mechanism(s) orchestrating the HDM-induced allergic inflammation remains partially deciphered. Understanding the kaleidoscope of HDM-induced innate immune responses is hampered by (1) the large complexity of the HDM allergome with very diverse functional bioreactivities, (2) the perpetual presence of microbial compounds (at least LPS, β-glucan, chitin) promoting as well pro-Th2 innate signaling pathways and (3) multiple cross-talks involving structural, neuronal and immune cells. The present review provides an update on the innate immune properties, identified so far, of multiple HDM allergen groups. Experimental evidence highlights the importance of HDM allergens displaying protease or lipid-binding activities on the initiation of the allergic responses. Specifically, group 1 HDM cysteine proteases are considered as the key initiators of the allergic response through their capacities to impair the epithelial barrier integrity, to stimulate the release of pro-Th2 danger-associated molecular patterns (DAMPs) in epithelial cells, to produce super-active forms of IL-33 alarmin and to mature thrombin leading to Toll-like receptor 4 (TLR4) activation. Remarkably, the recently evidenced primary sensing of cysteine protease allergens by nociceptive neurons confirms the critical role of this HDM allergen group in the early events leading to Th2 differentiation.

Effect of indoor house dust mite concentration on canine atopic dermatitis

Introduction

House dust mites (HDM) are regarded as essential environmental allergens not only in human, but also in canine atopic dermatitis (CAD), however, there are only a few studies on the influence of indoor HDM concentration on the disease.

Methods

Our study analyzed the correlation between the indoor HDM concentration, the severity of CAD, and the residential environments in client-owned 35 AD and 13 healthy dogs. We measured the extent of CAD and severity index-04 (CADESI-04), pruritus visual analog scale (PVAS), and transepidermal water loss (TEWL), indoor relative humidity (RH) and analyzed the residential environment questionnaires to evaluate AD severity.

Results

The Der f 1 concentration had an inverse association with TEWL, and no association with CADESI-04 and PVAS. The Der f 1 concentration was significantly high in the group living near the green area and 40% or higher RH.

Discussion

Our results suggest two possibilities: (1) Living around green areas and maintaining an appropriate indoor climate may help to improve CAD clinical symptoms. (2) The HDM may contain endotoxin and when present in high concentrations in CAD, they play a preventive role by enhancing the skin barrier function. Further studies with a larger number of dogs may help further elucidate an association between CAD and Der f 1.

House dust mite allergens and nitrated products: Identification and risk assessment in indoor dust

Air pollutants can potentially lead to nitration of allergic proteins, thus promoting sensitization of these allergens. However, little is currently known about the nitration status of house dust mite (HDM) allergens. We identified the occurrence of nitrated products of two major HDM allergens Der f 1 and Der p 1 in dust samples collected from college dormitories in eastern China and assessed their associated health risk. The results showed that both non-nitrated and nitrated forms of the two allergens were detected in the dust in the range of non-detected (ND)-10.6, 1.44-15.4, ND-22.4, ND-7.28 µg/g for non-nitrated Der f 1, nitrated Der f 1, non-nitrated Der p 1 and nitrated Der p 1, respectively. The median rates of nitration were determined as 74.0% for Der f 1 and 20.4% for Der p 1 at consideration of one nitration site. Further analysis reveals that the levels of HDM allergens and their nitrated products were found to be generally higher during winter, in dormitories of lower altitude and with female occupants. Furthermore, the calculated risk indexes were at considerably high levels. Our findings suggest that nitrated HDM allergens have already accumulated in the environment at such significant levels and their associated health risk calls for our immediate attention.

Beyond allergic progression: From molecules to microbes as barrier modulators in the gut-lung axis functionality

The "epithelial barrier hypothesis" states that a barrier dysfunction can result in allergy development due to tolerance breakdown. This barrier alteration may come from the direct contact of epithelial and immune cells with the allergens, and indirectly, through deleterious effects caused by environmental changes triggered by industrialization, pollution, and changes in the lifestyle. Apart from their protective role, epithelial cells can respond to external factors secreting IL-25 IL-33, and TSLP, provoking the activation of ILC2 cells and a Th2-biased response. Several environmental agents that influence epithelial barrier function, such as allergenic proteases, food additives or certain xenobiotics are reviewed in this paper. In addition, dietary factors that influence the allergenic response in a positive or negative way will be also described here. Finally, we discuss how the gut microbiota, its composition, and microbe-derived metabolites, such as short-chain fatty acids, alter not only the gut but also the integrity of distant epithelial barriers, focusing this review on the gut-lung axis.

Toll-like receptor 2 mediates Acanthamoeba-induced allergic airway inflammatory response in mice

BACKGROUND

Repeated intranasal exposure to Acanthamoeba has been revealed to induce allergic airway inflammatory responses in mice. Based on the role of toll-like receptors (TLRs) in the pathogenesis of allergic asthma, TLRs form a link between innate and adaptive immune responses, and play an important role in the activation of various cells in the innate immune system.

METHODOLOGY/PRINCIPAL FINDINGS

To determine the TLRs that are related to these immune responses, we assessed the expression levels of inflammation-related genes in mouse lung epithelial (MLE)-12 cells treated with excretory-secretory proteins (ES-P) of the Acanthamoeba strain (KA/E2) with or without the TLR antagonists. The expression levels of inflammation-related genes, such as eotaxin, TARC, macrophage-derived chemokine (MDC), and TSLP, in the TLR2 and TLR9 antagonist treatment groups were decreased, compared to those in the ES-P alone or other TLR antagonist treatment groups. In particular, a greater decrease in the relevant gene expression levels was found in the TLR2 antagonist treatment group than in the TLR9 antagonist treatment group. Allergic airway inflammation was evaluated in the wild-type (WT) and TLR2 knockout (KO) groups following KA/E2 exposure. Based on the results, allergic airway inflammatory responses (airway resistance value, inflammatory cell infiltration, Th2-related cytokine expression, mucin production, and metaplasia of lung epithelial cells and goblet cells) by KA/E2 were reduced in the TLR2 KO groups. In addition, TLR2 knockout BMDCs displayed lower activation of surface markers owing to ES-P stimulation than normal BMDCs, and KA/E2 ES-P-treated TLR2-depleted BMDCs produced fewer Th2 cytokine-expressing cells from naïve T cells than WT BMDCs. When ES-P was administered after primary lung cells were obtained from WT and TLR2 KO mice, the expression levels of inflammation-related genes were found to be significantly decreased in TLR2 KO cells compared to those in WT cells.

CONCLUSIONS

These results suggest that TLR2 is involved in lung inflammatory response activation in KA/E2 intranasal infection, especially in airway tissue.

Indoor exposure assessment for levels of dust mite and total volatile organic compounds (TVOCs) in living houses

The purpose of this study is to measure the levels of dust mites (Dermatophagoides farina group 1 [Der f1] and Dermatophagoides pteronyssinus group 1 [Der p1]) and total volatile organic compounds (TVOCs) in the resident environments with living conditions such as the number of ventilation; the number of window, floor, and temperature; and relative humidity (RH) from vulnerable class in South Korea. Information on residents is designed to be prepared by residents on their general characteristics (daily residence time, heating and cooking type, and cleaning on the day of sampling). Dust mites levels ranged from 24.0 to 1087.5 ng/g with a mean of 215.4 ng/g for Der f1 and from 0.6 to 489.9 ng/g with a mean of 489.9 ng/g for Der p1. Total TVOC levels ranged from 15.3 to 1642.1 μg/m³ with a mean of 219.7 μg/m³. The correlation analysis showed a positive association between Der f1 levels and xylene levels in fall (r = 0.49, r < 0.05) of this study.

Profile of aeroallergen sensitizations in allergic patients living in southern Vietnam

Background

Climatic and geographical characteristics may alter the plant distribution and thereby the patterns of allergens.

Objective

To evaluate the profile of allergen sensitization in patients in southern Vietnam and its association with allergic diseases.

Methods

We collected data of 423 patients who visited the Unit of Allergy and Clinical Immunology, University Medical Center, Vietnam from 2014 to 2021, from their medical records. Patients underwent skin prick tests to the 12 most common aeroallergens. Clinical evaluation and diagnosis of allergic diseases was done in consert with their allergen sensitization status.

Results

Mites and cockroach were the most prevalent sensitizing allergens, with the sensitization prevalences as followed: Dermatophagoides farinae (Df) (59.8%), Dermatophagoides pteronyssinus (Dp) (50.4%), Blomica tropicalis (Bt) (49.6%), storage mites mix (10.4%), and cockroach (10.2%). Sensitization to Df was more predominant in males than in females (66% vs 54.1%). Dp-sensitized patients were younger than non-sensitized patients (29.01 ± 13.60 vs. 32.17 ± 14.89) whereas storage mites-sensitized patients were older than the non-sensitized groups (36.25 ± 13.53 vs. 28.76 ± 13.39) (p < 0.05 for all). A considerable proportion of patients with urticaria, allergic rhinitis, and atopic dermatitis were sensitized to mites. Polysensitization to different species of house dust mites (Dp, Df) and storage mites (Bt) was prevalent among patients sensitized to any kind of mites.

Conclusions

Among people living in southern Vietnam, HDM mites, and cockroach were the predominant allergens. Further studies on the factors regulating the association between allergen sensitization with allergic diseases and polysensitization are crucial.

Asthma triggered by extreme temperatures: From epidemiological evidence to biological plausibility

BACKGROUND

There is rapidly growing evidence indicating that extreme temperature is a crucial trigger and potential activator of asthma; however, the effects of extreme temperature on asthma are inconsistently reported and the its potential mechanisms remain undefined.

OBJECTIVES

This review aims to estimate the impacts of extreme heat, extreme cold, and temperature variations on asthma by systematically summarizing the existing studies from epidemiological evidence to biological plausibility.

METHODS

We conducted a systematic search in PubMed, Embase, and Web of Science from inception to June 30, 2022, and we retrieved articles of epidemiology and biological studies which assessed associations between extreme temperatures and asthma. This protocol was registered with PROSPERO (CRD42021273613).

RESULTS

From 12,435 identified records, 111 eligible studies were included in the qualitative synthesis, and 37 articles were included in the meta-analysis (20 for extreme heat, 16 for extreme cold, and 15 for temperature variations). For epidemiological evidence, we found that the synergistic effects of extreme temperatures, indoor/outdoor environments, and individual vulnerabilities are important triggers for asthma attacks, especially when there is extreme heat or cold. Meta-analysis further confirmed the associations, and the pooled relative risks for asthma attacks in extreme heat and extreme cold were 1.07 (95%CI: 1.03-1.12) and 1.20 (95%CI: 1.12-1.29), respectively. Additionally, this review discussed the potential inflammatory mechanisms behind the associations between extreme temperatures and asthma exacerbation, and highlighted the regulatory role of immunological pathways and transient receptor potential ion channels in asthma triggered by extreme temperatures.

CONCLUSIONS

We concluded that both extreme heat and cold could significantly increase the risk of asthma. Additionally, we proposed a potential mechanistic framework, which is important for understanding the disease pathogenesis that uncovers the complex mechanisms of asthma triggered by extreme temperatures and protects the sensitive individuals from impacts of extreme weather events and climate change.

Validated allergen exposure chamber is plausible tool for the assessment of house dust mite-triggered allergic rhinitis

BACKGROUND

Allergen exposure chamber (AEC) is a clinical facility that allows exposure to allergenic airborne particles in controlled environment. Although AECs offer stable levels of airborne allergens, the validation of symptoms and other endpoints induced by allergen challenge is key for their recommendation as a plausible tool for the assessment of patients, especially in clinical research. This study aimed to demonstrate the reproducibility of defined clinical endpoints after AEC house dust mite (HDM) challenge under optimal conditions in patients with allergic rhinitis (AR).

METHOD

HDM was distributed at different concentrations. The assessment was subjective by the patients: total nasal symptom score (TNSS), visual analog scale (VAS), and objective by the investigator: acoustic rhinometry, peak nasal inspiratory flow (PNIF), and nasal secretion weight. Safety was assessed clinically and by peak expiratory flow rate (PEFR) and forced expiratory volume in the first second (FEV₁ ).

RESULTS

Constant environment: temperature, humidity, and carbon dioxide (CO₂ ) concentration were maintained during all challenges. The concentration of HDM on average remained stable within the targeted values: 1000, 3000, 5000, 7000 particles (p)/m³ . Most symptoms were observed at concentrations 3000 p/m³ or higher. The symptoms severity and other endpoints results were reproducible. 5000 p/m³ , and challenge duration of 120 min were found optimal. The procedure was safe with no lung function abnormalities due to challenge.

CONCLUSION

HDM challenge in ALL-MED AEC offers a safe and reliable method for inducing symptoms in AR patients for the use in controlled clinical studies including allergen immunotherapy.

DNA metabarcoding-based study on bacteria and fungi associated with house dust mites (Dermatophagoides spp.) in settled house dust

House dust mites (HDMs) including Dermatophagoides spp. are an important cause of respiratory allergies. However, their relationship with microorganisms in house dust has not been fully elucidated. Here, we characterized bacteria and fungi associated with HDMs in house dust samples collected in 107 homes in Korea by using DNA barcode sequencing of bacterial 16S rRNA gene, fungal internal transcribed spacer 2 (ITS2) region, and arthropod cytochrome c oxidase I (COI) gene. Our inter-kingdom co-occurrence network analysis and/or indicator species analysis identified that HDMs were positively related with a xerophilic fungus Wallemia, mycoparasitic fungi such as Cystobasidium, and some human skin-related bacterial and fungal genera, and they were negatively related with the hygrophilous fungus Cephalotrichum. Overall, our study has succeeded in adding novel insights into HDM-related bacteria and fungi in the house dust ecosystem, and in confirming the historically recognized fact that HDMs are associated with xerophilic fungi such as Wallemia. Understanding the microbial ecology in house dust is thought to be important for elucidating the etiology of human diseases including allergies, and our study revealed baseline information of house dust ecology in relation to HDMs. The findings could be useful from a perspective of human health.

Climatotherapy for asthma: Research progress and prospect

Asthma affects over 300 million people globally and is a cause of substantial burden of disease, including both premature death and reduced quality of life in people of all ages. Although both genetic and environmental factors play an important role in the pathogenesis of asthma, the rising trend of asthma and other allergic diseases over recent decades is thought to be largely caused by alteration in environmental conditions. Thus, a considerable amount of attention has been paid to environmental modification for the treatment and management of asthma, including household allergen reduction and/or irritant removal. More advanced environmental modification strategies (e.g., health resort medical rehabilitation, high-altitude climate therapy and multiple-hit interventions) have also been suggested. Research advances have been made over the past decades, but major challenges and opportunities coexist in this emerging field. Concerted efforts are required to tackle these formidable challenges.