House dust mite sensitization, eczema, and wheeze increase risk of shellfish sensitization

Non peer reviewe

Environmental and genetic risk factors for food allergy in children with Asian ancestry

© 2019 Noor Hidayatul Aini Bte SuainiEpidemiological and genetic studies on food allergy to date have focused primarily on the Caucasian population. This is despite emerging evidence that food allergy appears to be rising in Asian countries, alongside the increasing Westernisation and urbanisation in these countries. Even less is known about Asian migrants living in Western countries. A population-based study on food allergy found the risk of food allergy to be three times higher in infants of East Asian ancestry than infants of Caucasian ancestry. It is thought that infants growing up in Australia are exposed to environmental agents that have a differential effect on the immune system depending on their genetic background. However, the influence of specific genetic and environmental risk factors is currently unknown. It is also unclear if the increased risk of food allergy translates to higher risk of other allergic diseases later in childhood. The main objective of this thesis is to identify specific environmental and genetic factors on the risk of food allergy in the Asian population living in Australia. This thesis aims to quantify the prevalence of, and identify risk factors for food allergy and allergic comorbidities in the Asian population. An additional aim is to identify genetic variants that increase the risk of food allergy in the East Asian population and compare this to the Caucasian population living in Australia. This thesis primarily used data and samples from the longitudinal HealthNuts study where 5,276 1-year-old infants attending council run vaccination sessions across Melbourne were recruited. Skin prick tests to a range of food were carried out on infants and those with a wheal size less than 1 mm underwent an oral food challenge. The 1-year-old infants were followed up again at age 6 years and data collected at this follow-up visit were also used for analyses in this thesis. Additionally, data collected from a Growing Up in Singapore Towards Healthy Outcomes (GUSTO) birth cohort was also used to compare the risk factors and prevalence of allergic diseases between East Asians living in Melbourne and East Asians living in Singapore. This thesis reports that Australian-born children with East Asian parents have a higher burden of allergic rhinitis, eczema and aeroallergen sensitisation but not asthma, in the first six years of life compared to children of Caucasian ancestry. Moreover, children with IgE-mediated food allergy and eczema in infancy were 3 times more likely to have asthma and 2 times more likely to have allergic rhinitis at age 6 years, irrespective of ancestry. Additionally, East Asian children living in Melbourne have a higher risk of food allergy compared to East Asian children living in Singapore. Despite delayed introduction of allergens into the diet compared to the Asian population in Melbourne, Asian children in Singapore had less food allergy. While eczema rates were lower in Singapore than in Melbourne, early onset eczema was associated with an increased risk of food allergy in both Singapore and Melbourne. In terms of genetic risk factors, a systematic review conducted as part of this thesis identified several genes of interest known to be involved in immune regulation, cell function and epidermal barrier function. However, studies were of varied quality and the reproducibility of findings for the same SNPs were minimal. Some of the highly re-producible genes identified from the literature include HLA, FLG and IL13. Additionally, there was also a paucity of studies carried out in the Asian population that were able to elucidate underlying mechanisms for the differential food allergy risks observed in the population. This highlighted the need for genetic studies focused in this population. This thesis found that HLA rs7192 minor allele was associated with increased risk of peanut allergy in the Caucasian population but not East Asian population. Among sensitised children with two East Asian born parents, those with the minor allele for rs231735, rs231804 or rs11571291 (all CTLA4) have a reduced risk of egg allergy. The findings of this thesis identify Asian children living in Australia as a high risk allergic group not just in infancy but throughout early childhood. As a multifactorial disease, both environmental and genetic factors are known to contribute to the pathogenesis of food allergy. Therefore, it may be that the increased risk of food allergy observed in genetically predisposed East Asian children living in Melbourne unmasked upon exposure to environmental risk factors

Impact of COVID-19 pandemic on adults and children with atopic dermatitis and food allergy: Systematic review

Background: The coronavirus disease 2019 (COVID-19) pandemic caused significant disruptions to health care services and health impacts on patients with atopic dermatitis (AD) and/or food allergy (FA). Objective: We evaluated the impact of the COVID-19 pandemic and disease on AD/FA patients. Methods: A comprehensive systematic literature search was conducted from December 2019 to 2022. Screening and data extraction were done following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, and the Mixed Methods Appraisal Tool, or MMAT, was used to assess risk of bias. Results: In total, 159 studies were included. Five of 7 studies reported no significant changes in overall incidence or prevalence of AD during the pandemic, although some studies noted an increase in the elderly and infants. Telehealth served as an effective alternative to face-to-face consultations, with mixed levels of patient and provider satisfaction. Dissatisfaction was most marked in patients with more severe disease, who thought that their disease was inadequately managed through telemedicine. Higher levels of general anxiety were recorded in both AD/FA patients and caregivers, and it was more pronounced in patients with severe disease. Most studies reported no significant differences in postvaccination adverse effects in AD patients; however, results were more varied in FA patients. Conclusion: Our review identified the impact of COVID-19 pandemic- and disease-driven changes on AD/FA patients. Telemedicine is uniquely suited to manage atopic diseases, and hybrid care may be a suitable approach even in the postpandemic era. COVID-19 vaccines and biologics can be safely administered to patients with atopic diseases, with appropriate patient education to ensure continued care for high-risk patients

House dust mite sensitization, eczema and wheeze increase risk of shellfish sensitization

Shellfish allergy is more prevalent in South‐East Asia (~5%1) than in Western populations (e.g. United States ~2‐3%.2). Typically commencing in late childhood, it is the leading cause of anaphylaxis in adolescents and adults in Asia. Cross‐sectional studies have demonstrated a high correlation between shellfish and house dust mite (HDM) sensitization in warm, humid climates and urban environments where HDM are ubiquitous. The major shellfish allergen, tropomyosin, shares ~80% structural homology with HDM tropomyosin, and primary sensitization to dust mite tropomyosin has been hypothesized to induce cross‐sensitization to shellfish