Role of environmental exposures and filaggrin mutations on associations of ethnic origin with risk of childhood eczema. The Generation R Study

Are There Ethnic Differences in Hand Eczema? A Review

Hand eczema is a common disease with economic and social ramifications. This study undertakes a review of certain existing literature to provide insight into contributory factors which may result in the varying prevalence and severity of hand eczema among different ethnic groups, particularly to identify modifiable risk factors, as well as to ascertain knowledge gaps for future research direction. The existing literature suggests that factors including (a) genes, (b) differing skin physiology, (c) cultural practices, (d) dietary habits and associated food preparation, (e) climate, (f) predominant occupations, (g) socioeconomic factors, and (h) dissimilar laws and regulations may account for the disparity in the risk of hand eczema among different ethnicities. Given that endogenous factors cannot be avoided, but certain exogenous aspects can be modified, especially as the environment plays an important role in hand eczema flares, it is helpful from a practical perspective to focus on addressing the modifiable risk factors. These factors pertain to unique cultural practices, customs, and food preparation methods. Healthcare professionals should be well-acquainted with such factors to tailor the treatment approach for patients of different ethnicities accordingly because, with globalization, physicians face increasingly diverse patient populations such that cultural customs no longer remain limited to particular geographic regions.

Atopic Dermatitis: Conventional and Integrative Medicine

Although Western medicine and ideas about atopic dermatitis (AD) have become popular in many Asian countries, local beliefs about the disease and its treatment often prevail. The multi- racial background of these countries as well as the influence of the diverse religions (such as Taoism and Ramadan) in these regions often lead to diverse belief systems about the causes of AD (such as the Chi concept, also known as the balance of yin and yang) and the types of treatment (e.g. herbal remedies, topical versus concoctions, and decoctions). In addition, many of the cultural practices are preserved among the Southeast Asian minorities residing in the United Kingdom and North America. Eastern treatments typically take a holistic approach to AD and emphasize the psychosomatic component of the disorder. This overview provides a summary of the difference between conventional, complementary, alternative, and integrative medicine in terms of epidemiology, aetiology, therapy, and prognosis in children with AD. There are a number of similarities in genetic and environmental factors in epidemiology and aetiology; however, differences exist in terms of the concept of management. Complementary and alternative medicine, traditional Chinese medicine, and integrative medicine usage are not only prevalent among the Asian population but are also becoming more popular and accepted in Western societies.

Increased Th22 cell numbers in a general pediatric population with filaggrin haploinsufficiency: The Generation R Study

BACKGROUND

Mutations in the filaggrin gene (FLG) affect epidermal barrier function and increase the risk of atopic dermatitis (AD). We hypothesized that FLG mutations affect immune cell composition in a general pediatric population. Therefore, we investigated whether school-aged children with and without FLG mutations have differences in T- and B-cell subsets.

METHODS

This study was embedded in a population-based prospective cohort study, the Generation R Study, and included 523 children of European genetic ancestry aged 10 years. The most common FLG mutations in the European population (R501X, S1085CfsX36, R2447X, and S3247X) were genotyped. Additionally, 11-color flow cytometry was performed on peripheral blood samples to determine helper T (Th), regulatory T (Treg), and CD27⁺ and CD27^- memory B cells. Subset analysis was performed in 358 non-AD and 102 AD cases, assessed by parental questionnaires.

RESULTS

FLG mutations were observed in 8.4% of the total population and in 15.7% of the AD cases. Children with any FLG mutation had higher Th22 cell numbers compared to FLG wild-type children in the general and non-AD population. Children with and without FLG mutations had no difference in Th1, Th2, Th17, Treg, or memory B-cell numbers. Furthermore, in children with AD, FLG mutation carriership was not associated with differences in T- and B-cell subsets.

CONCLUSIONS

School-aged children of a general population with FLG mutations have higher Th22 cell numbers, which reflects the immunological response to the skin barrier dysfunction. FLG mutations did not otherwise affect the composition of the adaptive immunity in this general pediatric population.

Can Mixed Strains of Lactobacillus and Bifidobacterium Reduce Eczema in Infants under Three Years of Age? A Meta-Analysis

(1) Background: Whether early supplementation of probiotics to improve intestinal flora can effectively prevent eczema remains a controversial issue. We aimed to investigate the effect of a mixed strain of Lactobacillus and Bifidobacterium on eczema in infants under three years old at present; (2) Methods: We searched the databases of PubMed, Web of Science, and Cochrane Library, as well as National Knowledge Infrastructure (CNKI), WeiPu (VIP), and WanFang Data (WanFang) for randomized controlled trials (RCTs) of probiotics in the prevention of eczema in infants without language restriction. The main outcome was eczema incidence, while adverse events during the intervention constituted the secondary outcome. The random-/fixed-effects model was utilized to calculate the combined relative risk (RR) and 95% confidence interval (CI). The methodological quality of the study was evaluated using the Cochrane "bias risk" tool. According to the initial intervention time, subgroup analysis was carried out, follow-up time, family history, etc.; (3) Results: Nine articles were selected (2093 infants). The Lactobacillus and Bifidobacterium mixed strain could prevent eczema in infants under three years of age compared to the placebo (RR = 0.60; I² = 67%; p < 0.001). Subgroup analysis revealed that the mixture of two probiotic strains had preventive effects on both infants with positive (RR = 0.53; I² = 52%; p < 0.001) and negative (RR = 0.69; I² = 62%; p = 0.02) family history; The follow-up time for ≤12 months (RR = 0.65; I² = 12%; p = 0.01) and 12-24 months (RR = 0.60; I² = 79%; p = 0.003), daily dose of probiotics ≤ 1 × 10⁹ and > 1 × 10⁹ colony forming units all can be effective (p < 0.01); Compared with the intervention of infants alone (RR = 0.63; I² = 63%; p = 0.29), the effect of probiotics mixture at the beginning of pregnancy was more significant (RR = 0.59; I² = 71%; p < 0.001); Except for the mixture of Lactobacillus rhamnosusGG (LGG) and Bifidobacterium longum (B. longum) (p = 0.18), other subgroups of intervention group can play a preventive effect (p < 0.05); (4) Conclusions: The mixed strain of Lactobacillus and Bifidobacterium can effectively reduce the incidence of eczema in infants under three years old. However, further research is needed to fully understand the exact mechanism of their effect on infant eczema.

Ethnic differences in maternal diet in pregnancy and infant eczema

BACKGROUND

The global prevalence of childhood eczema has increased over the last few decades, with a marked increase in high-income countries. Differences in prevalence of childhood eczema between countries and ethnicities suggest that genetic and early modifiable environmental factors, such as dietary intake, may underlie this observation. To investigate the association between pregnancy diet and infant eczema in a consortium of prospective Canadian birth cohorts predominantly comprised of white Europeans and South Asians.

METHODS

We evaluated the association of maternal dietary patterns reported during pregnancy (assessed at 24-28 weeks gestation using a semi-quantitiative food-frequency questionnaire) with parent-reported physician-diagnosed infant eczema at 1-year from 2,160 mother-infant pairs. Using three dietary patterns ("Western", "plant-based", and "Balanced") previously derived in this cohort using principal component analysis, we used multivariable logistic regression to determine the association of these dietary patterns with infant eczema, adjusted for potential confounders.

RESULTS

We observed a lower odds of eczema in the full sample combining white Europeans and South Asians with greater adherence to a plant-based (OR = 0.65; 95% CI: 0.55, 0.76; <0.001) and Western dietary pattern (OR = 0.73; 95% CI: 0.60, 0.89; P<0.01), after adjusting for other known predictors of eczema, including ethnicity, which was not significant. No associations were observed for the balanced diet. An interaction between the Western diet and ethnicity was observed (P<0.001). Following stratification by ethnicity, a protective association between the plant-based diet and infant eczema was confirmed in both white Europeans (OR = 0.59; 95% CI: 0.47, 0.74; P<0.001) and South Asians (OR = 0.77; 95% CI: 0.61, 0.97; P = 0.025). In white Europeans only, a Western diet was associated with a lower odds of infant eczema (OR = 0.69; 95% CI: 0.56, 0.87; P = 0.001) while a balanced diet increased the odds of infant eczema (OR = 1.23; 95% CI: 1.02, 1.49; P = 0.03). Beyond a plant-based diet, no significant associations with other dietary patterns were observed in South Asians.

CONCLUSION

A plant-based diet during pregnancy is associated with a lowered odds of infant eczema at 1 year in all participants. Future studies of the components of plant-based diet which underlie the lower risk of eczema are needed.

Genetics and Epigenetics of Atopic Dermatitis: An Updated Systematic Review

BACKGROUND

Atopic dermatitis is a common inflammatory skin disorder that affects up to 15-20% of the population and is characterized by recurrent eczematous lesions with intense itching. As a heterogeneous disease, multiple factors have been suggested to explain the nature of atopic dermatitis (AD), and its high prevalence makes it necessary to periodically compile and update the new information available. In this systematic review, the focus is set at the genetic and epigenetic studies carried out in the last years.

METHODS

A systematic literature review was conducted in three scientific publication databases (PubMed, Cochrane Library, and Scopus). The search was restricted to publications indexed from July 2016 to December 2019, and keywords related to atopic dermatitis genetics and epigenetics were used.

RESULTS

A total of 73 original papers met the inclusion criteria established, including 9 epigenetic studies. A total of 62 genes and 5 intergenic regions were described as associated with AD.

CONCLUSION

Filaggrin (FLG) polymorphisms are confirmed as key genetic determinants for AD development, but also epigenetic regulation and other genes with functions mainly related to the immune system and extracellular matrix, reinforcing the notion of skin homeostasis breakage in AD.

Eczema phenotypes and risk of allergic and respiratory conditions in school age children

Background

Eczema phenotypes based on eczema onset and persistence might better identify groups prone to allergic and respiratory conditions than a binary definition of eczema. We examined the associations of childhood eczema phenotypes with allergic sensitization, allergy, asthma and lung function at school age.

Methods

This study among 4277 children was embedded in a multi-ethnic population-based prospective cohort study. Five eczema phenotypes (never, early transient, mid-transient, late transient, persistent) based on parental-reported physician-diagnosed eczema from age 6 months until 10 years were identified. At age 10 years, allergic sensitization was measured by skin prick tests, physician-diagnosed allergy and asthma by parent-reported questionnaires, and lung function by spirometry. Adjusted linear, logistic and multinomial regression models were applied.

Results

Compared with never eczema, all eczema phenotypes were associated with increased risks of asthma (odds ratios (OR) range (95% confidence interval): 2.68 (1.58, 4.57) to 11.53 (6.65, 20.01)), food and inhalant allergic sensitization (1.72 (1.25, 2.36) to 12.64 (7.20, 22.18)), and physician-diagnosed inhalant allergy (1.92 (1.34, 2.74) to 11.91 (7.52, 18.86)). Strongest effect estimates were observed of early and persistent eczema with the risk of physician-diagnosed food allergy (OR 6.95 (3.76, 12.84) and 35.05 (18.33, 70.00), respectively) and combined asthma and physician-diagnosed allergy (7.11 (4.33, 11.67) and 29.03 (15.27, 55.22), respectively). Eczema phenotypes were not associated with lung function measures.

Conclusion

Eczema phenotypes were differentially associated with risks of respiratory and allergic conditions in school-aged children. Children with early transient and persistent eczema might benefit from more intense follow-up for early identification and treatment of asthma and allergies.

Most associations of early-life environmental exposures and genetic risk factors poorly differentiate between eczema phenotypes: the Generation R Study

Background

Childhood eczema is variable in onset and persistence.

Objectives

To identify eczema phenotypes during childhood, and their associations with early‐life environmental and genetic factors.

Methods

In this study of 5297 children from a multiethnic population‐based prospective cohort study, phenotypes based on parent‐reported physician‐diagnosed eczema from age 6 months to 10 years were identified using latent class growth analysis. Information on environmental factors was obtained using postal questionnaires. Four filaggrin mutations were genotyped and a risk score was calculated based on 30 genetic variants. Weighted adjusted multinomial models were used for association analyses.

Results

We identified the following five eczema phenotypes: never (76%), early transient (8%), mid‐transient (6%) and late transient (8%) and persistent eczema (2%). Early transient and persistent eczema were most common in first‐born children, those with a parental history of eczema, allergy or asthma and those with persistent wheezing [range of odds ratio (OR): 1.37, 95% confidence interval (CI) 1.07–1.74 and OR 3.38, 95%CI 1.95–5.85]. Early transient eczema was most common in male children only (OR 1·49, 95% CI 1·18–1·89). Children with late transient or persistent eczema were more often of Asian ethnicity (OR 2·04, 95% CI 1·14–3·65 and OR 3·08, 95% CI 1·34–7·10, respectively). Children with early, late transient and persistent eczema more often had a filaggrin mutation or additional risk alleles (range OR: 1.07, 95%CI 1.02–1.12 and OR 2.21, 95%CI 1.39–3.50). Eczema phenotypes were not associated with maternal education, breastfeeding, day care attendance and pet exposure.

Conclusions

Five eczema phenotypes were identified in a multiethnic paediatric population with limited differences in risk profiles, except for sex and ethnicity.

What's already known about this topic?

Two previous studies in longitudinal birth cohorts identified four and six different eczema phenotypes, predominantly in children of European ethnicity.

What does this study add?

Five eczema phenotypes were identified in a multiethnic paediatric population using latent class growth analysis.

Children with early transient and persistent eczema were most often first‐born children and had persistent wheezing, filaggrin mutation or additional risk alleles.

Previously known eczema risk factors had limited differentiating capabilities for eczema phenotypes, except for the association of early transient eczema with male children, and late transient and persistent eczema with Asian ethnicity.

https://doi.org/10.1111/bjd.18575 available online

https://www.bjdonline.com/article/most-associations-of-early-life-environmental-exposures-and-genetic-risk-factors-poorly-differentiate-between-eczema-phenotypes-the-generation-r-study/

Prediction and prevention of allergy and asthma in EAACI journals (2016)

The European Academy of Allergy and Clinical Immunology (EAACI) owns three journals: Allergy, Pediatric Allergy and Immunology and Clinical and Translational Allergy. One of the major goals of EAACI is to support health promotion in which prevention of allergy and asthma plays a critical role and to disseminate the knowledge of allergy to all stakeholders including the EAACI junior members.