Domestic dog exposure at birth reduces the incidence of atopic dermatitis

Atopic and non-atopic effects of fish oil supplementation during pregnancy

BACKGROUND

We recently conducted a double-blinded randomised controlled trial showing that fish-oil supplementation during pregnancy reduced the risk of persistent wheeze or asthma in the child by 30%. Here, we explore the mechanisms of the intervention.

METHODS

736 pregnant women were given either placebo or n-3 long-chain polyunsaturated fatty acids (LCPUFAs) in the third trimester in a randomised controlled trial. Deep clinical follow-up of the 695 children in the trial was done at 12 visits until age 6 years, including assessment of genotype at the fatty acid desaturase (FADS) locus, plasma fatty acids, airway DNA methylation, gene expression, microbiome and metabolomics.

RESULTS

Supplementation with n-3 LCPUFA reduced the overall risk of non-atopic asthma by 73% at age 6 (relative risk (RR) 0.27 (95% CI 0.06 to 0.85), p=0.042). In contrast, there was no overall effect on asthma with atopic traits (RR 1.42 (95% CI 0.63 to 3.38), p=0.40), but this was significantly modified by maternal FADS genotype and LCPUFA blood levels (interaction p<0.05), and supplementation did reduce the risk of atopic asthma in the subgroup of mothers with FADS risk variants and/or low blood levels of n-3 LCPUFA before the intervention (RR 0.31 (95% CI 0.11 to 0.75), p=0.016). Furthermore, n-3 LCPUFA significantly reduced the number of infections (croup, gastroenteritis, tonsillitis, otitis media and pneumonia) by 16% (incidence rate ratio 0.84 (95% CI 0.74 to 0.96), p=0.009).

CONCLUSIONS

n-3 LCPUFA supplementation in pregnancy showed protective effects on non-atopic asthma and infections. Protective effects on atopic asthma depended on maternal FADS genotype and n-3 LCPUFA levels. This indicates that the fatty acid pathway is involved in multiple mechanisms affecting the risk of asthma subtypes and infections.

TRIAL REGISTRATION NUMBER

NCT00798226.

Novel Connections of Common Childhood Illnesses Based on More Than 5 Million Diary Registrations From Birth Until Age 3 Years

BACKGROUND

All children experience numerous episodes of illness during the first 3 years of life. Most episodes are mild and handled without medical attention but nevertheless burden the families and society. There is a large, and still unexplained, variation in the burden of illness between children.

OBJECTIVE

To describe and provide a better understanding of the disease burden of common childhood diseases through a data-driven approach investigating the communalities between symptom patterns and predefined variables on predispositions, pregnancy, birth, environment, and child development.

METHODS

The study is based on the prospectively followed clinical mother-child cohort COpenhagen Prospective Studies on Asthma in Childhood, which includes 700 children with daily symptom registration in the first 3 years of life, including symptoms of cough, breathlessness, wheeze, cold, pneumonia, sore throat, ear infections, gastrointestinal infections, fever, and eczema. First, we described the number of episodes of symptoms. Next, factor analysis models were used to describe the variation in symptom load in the second year of life (both based on n = 556, with >90% complete diary). Then we characterized patterns of similarity between symptoms using a graphical network model (based on n = 403, with a 3-year monthly compliance of >50%). Finally, predispositions and pregnancy, birth, environmental, and developmental factors were added to the network model.

RESULTS

The children experienced a median of 17 (interquartile range, 12-23) episodes of symptoms during the first 3 years of life, of which most were respiratory tract infections (median, 13; interquartile range, 9-18). The frequency of symptoms was the highest during the second year of life. Eczema symptoms were unrelated to the other symptoms. The strongest association to respiratory symptoms was found for maternal asthma, maternal smoking during the third trimester, prematurity, and CDHR3 genotype. This was in contrast to the lack of associations for the well-established asthma locus at 17q21.

CONCLUSIONS

Healthy young children are burdened by multiple episodes of symptoms during the first 3 years of life. Prematurity, maternal asthma, and CDHR3 genotype were among the strongest drivers of symptom burden.

Risk Factors and Age-Related Patterns of Asthma-Like Symptoms in Early Childhood

BACKGROUND

Episodes of asthma-like symptoms in young children are common, but little is known about risk factors and their patterns for the daily symptom burden.

OBJECTIVE

We investigated a variety of possible risk factors and their age-related impact on the number of asthma-like episodes during age 0 to 3 years.

METHODS

The study population included 700 children from the Copenhagen Prospective Studies on Asthma in Childhood2010 mother-child cohort followed prospectively from birth. Asthma-like symptoms were recorded until age 3 by daily diaries. Risk factors were analyzed by quasi-Poisson regressions, and interaction with age was explored.

RESULTS

Diary data were available in 662 children. Male sex, maternal asthma, low birth weight, maternal antibiotic use, high asthma exacerbation polygenic risk score, and high airway immune score were associated with a higher number of episodes in a multivariable analysis. Maternal asthma, preterm birth, caesarean section, and low birth weight showed an increasing impact with age, whereas sibling(s) at birth showed a decreased association with age. The remaining risk factors had a stable pattern during age 0 to 3 years. For every additional clinical risk factor (male sex, low birth weight, and maternal asthma) a child had, we found 34% more episodes (incidence rate ratio: 1.34, 95% confidence interval: 1.21-1.48; P < .001).

CONCLUSION

Using unique day-to-day diary recordings, we identified risk factors for the burden of asthma-like symptoms in the first 3 years of life and described their unique age-related patterns. This provides novel insight into the origin of asthma-like symptoms in early childhood that potentially pave a path for personalized prognostics and treatment.

25 Years of translational research in the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC)

The Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) mother-child cohorts have provided a foundation of 25 years of research on the origins, prevention, and natural history of childhood asthma and related disorders. COPSAC's approach is characterized by clinical translational research with longitudinal deep phenotyping and exposure assessments from pregnancy, in combination with multi-omic data layers and embedded randomized controlled trials. One trial showed that fish oil supplementation during pregnancy prevented childhood asthma and identified pregnant women with the highest benefits from supplementation, thereby creating the potential for personalized prevention. COPSAC revealed that airway colonization with pathogenic bacteria in early life is associated with an increased risk of asthma. Further, airway bacteria were shown to be a trigger of acute asthma-like symptoms, with benefit from antibiotic treatment. COPSAC identified an immature gut microbiome in early life as a risk factor for asthma and allergy and further demonstrated that asthma can be predicted by infant lung function. At a molecular level, COPSAC has identified novel susceptibility genes, early immune deviations, and metabolomic alterations associated with childhood asthma. Thus, the COPSAC research program has enhanced our understanding of the processes causing childhood asthma and has suggested means of personalized prevention and treatment.

Associations between fetal or infancy pet exposure and food allergies: The Japan Environment and Children's Study

The hygiene hypothesis suggests that pet exposure is effective in preventing allergic disease, and some studies have reported the beneficial effects of dog exposure during fetal development or early infancy on food allergy. However, the effects of exposure to pets other than dogs on the kinds of food allergies remains unaddressed. This study aimed to explore the effect of exposure to various species of pets on the risk of food allergies. We obtained information on pet exposure and food allergy from the Japan Environment and Children's Study, a nationwide, prospective birth cohort study that included 97,413 mothers and their children. We examined the associations between exposure to various species of pets during fetal development or early infancy and the incidence risk of food allergies. We conducted logistic regression analysis for each pet species, causative food, and timing of exposure. Exposure to dogs or cats during fetal development or early infancy was estimated to reduce the incidence risk of food allergies until the age of 3 years. Dog exposure was estimated to reduce the incidence risk of egg, milk, and nut allergies, and cat exposure was estimated to reduce the incidence risk of egg, wheat, and soybean allergies. However, hamster exposure was estimated to increase the incidence risk of nut allergy. In conclusion, the association between pet exposure and food allergies might differ depending on the pet species and causative food. Continued dog and cat exposure from fetal development to infancy was estimated to reduce the incidence risk of food allergies. The findings of this study shall aid in the design of future studies.

European guideline (EuroGuiDerm) on atopic eczema - part II: non-systemic treatments and treatment recommendations for special AE patient populations

The evidence- and consensus-based guideline on atopic eczema was developed in accordance with the EuroGuiDerm Guideline and Consensus Statement Development Manual. Four consensus conferences were held between December 2020 and July 2021. Twenty-nine experts (including clinicians and patient representatives) from 12 European countries participated. This second part of the guideline includes recommendations and detailed information on basic therapy with emollients and moisturizers, topical anti-inflammatory treatment, antimicrobial and antipruritic treatment and UV phototherapy. Furthermore, this part of the guideline covers techniques for avoiding provocation factors, as well as dietary interventions, immunotherapy, complementary medicine and educational interventions for patients with atopic eczema and deals with occupational and psychodermatological aspects of the disease. It also contains guidance on treatment for paediatric and adolescent patients and pregnant or breastfeeding women, as well as considerations for patients who want to have a child. A chapter on the patient perspective is also provided. The first part of the guideline, published separately, contains recommendations and guidance on systemic treatment with conventional immunosuppressive drugs, biologics and janus kinase (JAK) inhibitors, as well as information on the scope and purpose of the guideline, and a section on guideline methodology.

Differences in Occurrence, Risk Factors and Severity of Early-onset Atopic Dermatitis among Preterm and Term Children

This prospective birth cohort followed 150 preterm and 300 term newborns during the first year of life to assess possible differences in risk factors, age at onset, anatomical location, and severity of atopic dermatitis. Atopic dermatitis was diagnosed clinically, and severity was assessed using Eczema Area Severity Index (EASI). DNA was analysed for filaggrin gene mutations. Parents were asked about environmental exposures and emollient use. Atopic dermatitis during the first year of life was observed in 21.2% of children and was more common in term children compared with preterm children (26.7% vs 11.7%, p < 0.001), with lower age of onset (4 vs 6 months, p < 0.05) and more severe disease at onset (EASI: 4.8 vs 0.4, p < 0.0005). Environmental risk factors for atopic dermatitis were essentially similar for preterm and term born children, apart from winter and autumn births. Filaggrin gene mutations were less common in preterm than term children (4.1% vs 9.2%, p = 0.06).

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.

Prenatal and Perinatal Environmental Influences Shaping the Neonatal Immune System: A Focus on Asthma and Allergy Origins

It is suggested that programming of the immune system starts before birth and is shaped by environmental influences acting during critical windows of susceptibility for human development. Prenatal and perinatal exposure to physiological, biological, physical, or chemical factors can trigger permanent, irreversible changes to the developing immune system, which may be reflected in cord blood of neonates. The aim of this narrative review is to summarize the evidence on the role of the prenatal and perinatal environment, including season of birth, mode of delivery, exposure to common allergens, a farming environment, pet ownership, and exposure to tobacco smoking and pollutants, in shaping the immune cell populations and cytokines at birth in humans. We also discuss how reported disruptions in the immune system at birth might contribute to the development of asthma and related allergic manifestations later in life.

Component-resolved diagnostics in pet allergy: Current perspectives and future directions

Furry mammals kept as pets are important allergen sources. The prevalence of sensitization to dander from various animals appears to be increasing worldwide. Several mammalian allergens from diverse species and distinct protein families have been characterized, and some are available for component-resolved diagnostics (CRD). This review presents an overview of mammalian aeroallergens, with a focus on cat, dog, and horse allergens. The potential of CRD in fine-tuning the diagnostic workup following traditional methods based on whole- allergen extracts and allergen immunotherapy is discussed. The review highlights the clinical utility of CRD, particularly as a marker/predictor of increased asthma risk and disease severity. Finally, several perspectives of the future implications of CRD are offered in the context of furry animal allergens.

Epigenetic landscape links upper airway microbiota in infancy with allergic rhinitis at 6 years of age

BACKGROUND

The upper airways present a barrier to inhaled allergens and microbes, which alter immune responses and subsequent risk for diseases, such as allergic rhinitis (AR).

OBJECTIVE

We tested the hypothesis that early-life microbial exposures leave a lasting signature in DNA methylation that ultimately influences the development of AR in children.

METHODS

We studied upper airway microbiota at 1 week, 1 month, and 3 months of life, and measured DNA methylation and gene expression profiles in upper airway mucosal cells and assessed AR at age 6 years in children in the Copenhagen Prospective Studies on Asthma in Childhood birth cohort.

RESULTS

We identified 956 AR-associated differentially methylated CpGs in upper airway mucosal cells at age 6 years, 792 of which formed 3 modules of correlated differentially methylated CpGs. The eigenvector of 1 module was correlated with the expression of genes enriched for lysosome and bacterial invasion of epithelial cell pathways. Early-life microbial diversity was lower at 1 week (richness P = .0079) in children with AR at age 6 years, and reduced diversity at 1 week was also correlated with the same module's eigenvector (ρ = -0.25; P = 3.3 × 10-5). We show that the effect of microbiota richness at 1 week on risk for AR at age 6 years was mediated in part by the epigenetic signature of this module.

CONCLUSIONS

Our results suggest that upper airway microbial composition in infancy contributes to the development of AR during childhood, and this trajectory is mediated, at least in part, through altered DNA methylation patterns in upper airway mucosal cells.

Symptom burden of atopic dermatitis in early childhood assessed from daily monitoring of symptoms and topical steroid use

BACKGROUND

To our knowledge, disease burden of atopic dermatitis (AD) as number of days with symptoms and medical treatment has never been studied as measure of severity.

OBJECTIVES

To investigate risk factors for AD burden in the first 3 years of life.

METHODS

The Copenhagen Prospective Studies on Asthma in Childhood₂₀₁₀ included 700 children. AD burden was assessed by daily diary entries with information on AD and steroid days measuring 18 possible heritable, prenatal, and postnatal environmental exposures.

RESULTS

The children with AD had a median (interquartile range) of 136 symptom days (61-294 days) and 72 steroid days (27-145 days) during the first 3 years of life, with the highest disease burden in the second year of life. The multivariable risk factor analysis showed that maternal AD and childhood allergic sensitization were associated with a higher number of AD days and maternal AD, filaggrin mutation, and allergic sensitization were associated with a higher number of steroid days.

LIMITATIONS

Participants with a personal interest in atopic diseases could be more likely to participate.

CONCLUSION

Children's burden of AD, assessed quantitatively as AD and steroid days, demonstrated positive associations with maternal AD, filaggrin mutation, and early-life allergic sensitization, with the highest disease burden in the second year of life.

Dog keeping at home before and during pregnancy decreased the risk of food allergy in 1-year-old children

Introduction

The relationship between allergen exposure to animals in pregnancy and the development of allergic symptoms is not clear.

Aim

To evaluate the association between prenatal and postnatal exposure to pet ownership and development of atopic dermatitis, food allergy and wheezing in children at the age of 1 and 2.

Material and methods

The mother-child pairs included in this study were part of the Polish Mother and Child Cohort. Mothers in each trimester of pregnancy and 1 year after childbirth have completed a questionnaire on animal exposure. Children's health status was assessed at around one year and two years of age.

Results

Keeping a dog at home before and during pregnancy (every trimester) decreased the risk of food allergy in the first year of life. On the other hand, keeping any animal other than a dog (cat, hamster, guinea pig, rabbit) before pregnancy and during each trimester separately increased the risk of food allergy in the first year of life of children. Keeping a guinea pig in the first trimester of pregnancy increased the risk of wheezing in the first year of life. The analysis did not show any significant associations between keeping animals at home before and during pregnancy and the occurrence of atopic dermatitis in the second year of life.

Conclusions

Keeping a dog at home before and during pregnancy decreased the risk of food allergy in 1-year-old children. This effect was eliminated in case of having a cat, hamster, guinea pig, or rabbit.

Markers of microbial exposure lower the incidence of atopic dermatitis

BACKGROUND

The hygiene hypothesis proposes that reduced exposure to infectious agents in early life would explain the increase of allergic and autoimmune diseases observed over the past decades in high-income countries.

METHODS

We conducted a matched case-control study on incident atopic dermatitis (AD). Cases were 426 outpatient children with a first diagnosis of incident AD. Controls were 426 children attending a pediatric/dermatological visit for nonatopic disorders matched to cases (1:1). Particular attention was paid to the time elapsed between the markers of microbial exposure and disease onset, and we considered for controls the same time window of exposures from birth as his/her matched case. Odds ratios (ORs) were computed using multivariable conditional logistic regression models, according to center, sex, age, and period of enrollment, and including as potential confounders a family history of any allergy in parents, type of delivery, having siblings, keeping pets, age at weaning, and having had ≥4 infections.

RESULTS

The OR of AD first occurrence was 0.35 (P-value = .039) for children who had experienced ≥4 infections compared with those with no infections. A decreasing trend in risk was observed with increasing number of siblings (P-value = .023), the protective effect reaching about 40% for children with 2 or more siblings (OR = 0.62; P-value = .048). Pet keeping, in particular daily contact with dogs, was inversely associated with AD risk (OR = 0.40; P-value = .004).

CONCLUSIONS

These results support the hygiene hypothesis in its broad sense. Early-life environmental exposures, including pathogens and commensals, act as "microbes contact carriers" influencing immune system balance early in life.

Asthma prevalence, but not allergic rhinitis nor atopic dermatitis, is associated to exposure to dogs in adolescents

BACKGROUND

Exposure to pets can be a predisposing factor in the development of certain diseases, including allergic diseases.

OBJECTIVE

We analyzed the role that exposure to indoor dogs and cats plays in the prevalence of allergic diseases.

METHODS

We examined the cross-sectional data of 1056 women and 936 men aged 15 to 18 years; these individuals were selected through stratified and cluster random sampling. We asked all participants about their exposure to indoor dogs and cats during the year that preceded our study. The prevalence of allergic diseases was determined through core questions taken from The International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS

The prevalence was 12.7% (95% CI: 11.3%-14.2%) for asthma, 9.0% (95% CI: 7.8%-10.4%) for allergic rhinitis, and 5.2% (95% CI: 4.3%-6.2%) for atopic dermatitis. The multivariate analyses showed that exposure to indoor dogs, but not indoor cats, was associated with asthma prevalence (aOR 1.37; 95% CI: 1.03-1.83), as was male sex (aOR=1.42; 95% CI: 1.08-1.86), a personal history of allergic rhinitis (aOR=3.24; 95% CI: 2.25-4.66), and a maternal history of asthma (aOR=3.06; 95% CI: 1.89-4.98). The population attributable risk for exposure to indoor dogs was 18%. Notably, neither allergic rhinitis nor atopic dermatitis was found to be associated with dog or cat exposure (p> 0.05).

CONCLUSION

Exposure to dogs in late adolescence is a factor associated with asthma, although its contribution to the development of asthma should be investigated in new studies.

Early Life Domestic Pet Ownership, and the Risk of Pet Sensitization and Atopic Dermatitis in Preschool Children: A Prospective Birth Cohort in Shanghai

Background: Although domestic pet ownership is on the rise, the impact of early life pet ownership on children's pet sensitization and atopic dermatitis (AD) remains controversial. Methods: Shanghai Allergy Cohort is an ongoing prospective study followed up to the age of 5 years. Pregnant mothers were recruited and their offspring were followed up every year by a group of pediatricians. Information on furred pet ownership was collected by the questionnaire. AD was diagnosed by dermatologists according to disease history and Williams criteria at 5 years ± 1 months. Skin prick test (SPT) was performed to determine sensitization to specific allergens. Multiple logistic regression models were used to evaluate the associations between pet ownership and AD, dog/cat sensitization. Results: In the 538 children at preschool age, 112 (20.82%) were diagnosed with AD. Dermatophagoides pteronyssinus and Dermatophagoides farina were the most common allergens, and almost 10% of children were positive to dog and cat. The percentage of positive SPT reactors at 5-year old was 65.28% in the group of children with AD, higher than that in non-AD group (44.57%). Domestic pet ownership at both infant and preschool period was positively associated with an increased risk of sensitization to dog (OR _adjusted = 2.85 [95% CI: 1.08-7.50 for infant exposure], OR _adjusted = 2.73 [95% CI: 1.33-5.61] for preschool exposure), and interestingly, pet ownership at infant period negatively associated with higher risk of AD at 5-year old (OR adjusted = 0.33 [95% CI: 0.12-0.88]). Conclusion: This is the first prospective birth cohort study in Shanghai that found half of preschool children had positive allergen sensitization even in the non-AD children. Although early life exposure to dog may increase the risk of dog sensitization, it significantly decreased the risk of AD. The underlying mechanisms warrant further investigations.

Children with Asthma Have Fixed Airway Obstruction through Childhood Unaffected by Exacerbations

BACKGROUND

Children with asthma may have a disease course with or without exacerbations, but the relationship between exacerbations and lung function development is poorly understood.

OBJECTIVE

To compare lung function trajectories from birth till adolescence in asthmatic children with and without exacerbations.

METHODS

Children with asthma from the Copenhagen Prospective Studies on Asthma in Childhood₂₀₀₀ (COPSAC₂₀₀₀) birth cohort had lung function and bronchial reactivity assessed repeatedly from 1 month to 13 years. Exacerbations were diagnosed at the COPSAC clinic defined as symptoms requiring hospitalization, oral or high-dose inhaled corticosteroid treatment. Mixed models were applied to analyze lung function trajectories.

RESULTS

Children with asthma with exacerbations (N = 50) had a trajectory of increased, fixed airway obstruction compared with children without exacerbations (N = 47): z-score difference in airway resistance (sRaw_z) (95% confidence interval [CI]): +0.34 (+0.03; +0.66), P = .03, and maximal mid-expiratory flow (MMEF_z): -0.41 (-0.69; -0.13), P = .004, but no differences in forced expiratory volume (FEV_z): -0.14 (-0.41; +0.13), P = .29, or bronchial reactivity to methacholine (PD_z): +0.08 (-0.26; +0.42), P = .65. This did not change comparing lung function trajectories before and after exacerbations: z-score difference (95% CI) sRaw_z: -0.04 (-0.35; 0.27), P = .80; MMEF_z: 0.01 (-0.02; 0.04), P = .55; FEV_z: 0.02 (-0.02; 0.05), P = .42; and PD_z: -0.01 (-0.06; 0.05), P = .88.

CONCLUSION

Children with asthma with exacerbations compared with children with asthma without exacerbations are characterized by increased airway obstruction since infancy through childhood. The airway obstruction is a fixed trajectory without progression due to exacerbations, suggesting that exacerbations are a consequence rather than a cause of diminished airway caliber in childhood.

Genetic, Clinical, and Environmental Factors Associated With Persistent Atopic Dermatitis in Childhood

Importance

Knowledge about factors associated with persistence of atopic dermatitis (AD) during childhood is sparse.

Objective

To explore heritable, environmental, and clinical factors associated with persistent AD based on 13 years' follow-up of an at-risk birth cohort.

Design, Setting, and Participants

In the Copenhagen Prospective Study on Asthma in Childhood 2000 (COPSAC2000) clinical birth cohort study, 411 children born to mothers with asthma were followed up until the age of 13 years at a clinical research unit in Copenhagen, Denmark, from August 1998 to June 2015. Atopic dermatitis was diagnosed prospectively during close clinical follow-up according to the criteria of Hanifin and Rajka. Data were gathered on parental history, social circumstances, and environmental factors through parent interviews. The cohort was followed up with biannual visits to the clinic until the age of 7 years and were seen again at age 13 years. Data were analyzed from August 2015 to January 2018.

Main Outcomes and Measures

Atopic dermatitis was diagnosed using Hanifin and Rajka major and minor criteria, and severity was determined by Scoring Atopic Dermatitis (SCORAD) index, with possible scores from 0 to 83, with higher scores indicating more severe AD.

Results

Of the 411 children in the cohort, 203 (49.4%) were male and 186 (45.3%) were diagnosed with AD before the age of 13 years; 40 of 166 children (24.1%) had persistent AD at the age of 13 years, and 126 (76.0%) experienced remission. Factors associated with persistent AD to age 13 years included heritability, environmental exposures, asthma and allergic sensitization, clinical presentation at the time of diagnosis, the composition of Hanifin and Rajka diagnostic minor criteria, and AD severity according to SCORAD. A higher AD genetic risk score was associated with an increased the risk for persistent AD (multivariable odds ratio [OR], 1.8; 95% CI, 1.1-2.9; P = .02), together with paternal asthma (multivariable OR, 3.7; 95% CI, 1.2-11.5; P = .02); paternal AD (multivariable OR, 6.2; 95% CI, 1.17-23.2; P = .007), and higher social circumstances (multivariable OR, 1.6; 95% CI, 1.0-2.5; P = .05). Particular clinical presentations at time of diagnosis were also associated with specific minor criteria of Hanifin and Rajka (Dennie-Morgan and anterior neck folds, white dermographism, intolerance to wool, itching when sweating, tendency to skin infection, food intolerance, and food allergy) (OR, 2.6; 95% CI, 1.1-6.2; P = .03) as well as increased severity at diagnosis (OR, 1.1; 95% CI, 1.0-1.1; P = .007).

Conclusions and Relevance

In a birth cohort of children at risk for asthma who received close clinical follow-up to age 13 years, known genetic AD risk variants, paternal asthma and AD, high social circumstances, diagnostic minor criteria, and disease severity at onset were associated with persistent AD at age 13 years. These findings may be applied in clinical practice to evaluate the likely disease course for individual patients.

The role of filaggrin in atopic dermatitis and allergic disease

OBJECTIVE

To provide an overview of filaggrin biology and the role of filaggrin variants in atopic dermatitis (AD) and allergic disease.

DATA SOURCES

We performed a PubMed literature review consisting mainly of studies relating to filaggrin in the last 5 years.

STUDY SELECTIONS

We selected articles that were found in PubMed using the search terms filaggrin, atopic dermatitis, skin barrier, and atopy.

RESULTS

Filaggrin plays an important role in the development of AD and allergic disease. Novel methods in measuring filaggrin expression and identifying filaggrin mutations aid in stratifying this patient cohort. We review new insights into understanding the role of filaggrin in AD and allergic disease.

CONCLUSION

Filaggrin remains a very important player in the pathogenesis of atopic dermatitis and allergic disease. This review looks at recent studies that aid our understanding of this crucial epidermal protein.

[Atopic eczema and microbiome]

BACKGROUND

Atopic eczema is a chronic inflammatory skin disease characterized by skin barrier disruption, inflammation and dysbiosis. Furthermore, atopic eczema is associated with other diseases of the atopic group, such as allergies, rhinoconjunctivitis and asthma. The skin microbiome consists of bacteria, viruses and fungi. Patients suffering from atopic eczema often show an imbalance (dysbiosis) of the microbiome.

OBJECTIVE

It is not yet completely clarified what influence dysbiosis and the cutaneous microbiome have on the development and severity of atopic eczema. Modern sequencing methods will be used to investigate the role of the skin microbiome in the pathogenesis of atopic eczema in the future.

MATERIAL AND METHODS

This article presents and discusses the results of current basic research.

RESULTS

The human skin microbiome differs according to body region, age and gender. It interacts with the skin barrier and the cutaneous immune system. Patients suffering from atopic eczema develop dysbiosis consisting of an increased load of Staphylococcus aureus and a reduction of commensal skin bacteria. The altered skin microbiome in patients suffering from atopic eczema may also affect skin barrier function and inflammatory reactions.

CONCLUSION

Knowledge of the skin microbiome has improved in recent years. This will certainly improve the understanding of the pathogenesis causing atopic eczema. These findings may also form the foundation of new treatment and prevention strategies for atopic eczema in the future.

The Role of the Environmental Risk Factors in the Pathogenesis and Clinical Outcome of Atopic Dermatitis

Atopic dermatitis (AD) prevalence is rising worldwide. Literature data suggest the incidence of AD in developing countries is gradually getting close to that of developed ones, in which AD affects 20% of the paediatric population. Such an increment, associated with significant variations in prevalence among the various countries, underlines the importance of environmental factors in the disease onset. Among these, great importance is given to hygiene, intestinal microbiota, exposure to bacterial endotoxins, outdoor living with contact to animals, atmospheric pollution, weather, and diet. Genetic (alteration of the skin barrier function) as well as immunologic factors concur with the environmental ones. Only the systematical study of all these elements can best elucidate AD epidemiology.

Recent developments and highlights in mechanisms of allergic diseases: Microbiome

All body surfaces are exposed to a wide variety of microbes, which significantly influence immune reactivity within the host. This review provides an update on some of the critical novel findings that have been published on the influence of the microbiome on atopic dermatitis, food allergy and asthma. Microbial dysbiosis has consistently been observed in the skin, gut and lungs of patients with atopic dermatitis, food allergy and asthma, respectively, and the role of specific microbes in allergic disorders is being intensively investigated. However, many of these discoveries have yet to be translated into routine clinical practice.

Consensus-based European guidelines for treatment of atopic eczema (atopic dermatitis) in adults and children: part I

This guideline was developed as a joint interdisciplinary European project, including physicians from all relevant disciplines as well as patients. It is a consensus-based guideline, taking available evidence from other guidelines, systematic reviews and published studies into account. This first part of the guideline covers methods, patient perspective, general measures and avoidance strategies, basic emollient treatment and bathing, dietary intervention, topical anti-inflammatory therapy, phototherapy and antipruritic therapy, whereas the second part covers antimicrobial therapy, systemic treatment, allergen-specific immunotherapy, complementary medicine, psychosomatic counselling and educational interventions. Management of AE must consider the individual clinical variability of the disease; highly standardized treatment rules are not recommended. Basic therapy is focused on treatment of disturbed barrier function by hydrating and lubricating topical treatment, besides further avoidance of specific and unspecific provocation factors. Topical anti-inflammatory treatment based on glucocorticosteroids and calcineurin inhibitors is used for flare management and for proactive therapy for long-term control. Topical corticosteroids remain the mainstay of therapy, whereas tacrolimus and pimecrolimus are preferred in sensitive skin areas and for long-term use. Topical phosphodiesterase inhibitors may be a treatment alternative when available. Adjuvant therapy includes UV irradiation, preferably with UVB 311 nm or UVA1. Pruritus is targeted with the majority of the recommended therapies, but some patients may need additional antipruritic therapy. Antimicrobial therapy, systemic anti-inflammatory treatment, immunotherapy, complementary medicine and educational intervention will be addressed in part II of the guideline.

Exposure to dogs but not cats is associated to a decrease in the prevalence in atopic dermatitis amongst school-children

INTRODUCTION

The association regarding the exposure to pets, especially cats and dogs, and the prevalence of allergic diseases is inconsistent.

OBJECTIVE

We analyzed the role played by early exposure to dogs or cats in the prevalence of allergic diseases amongst school-aged children.

METHOD

Through a cross-sectional study, we examined 756 children, aged 6-7; these candidates were selected through cluster sampling. We inquired about the exposure that these children had had to dogs and cats, and whether these pets spent most of their time indoors or outdoors during the first year of the child's life. In order to identify the prevalence of allergic diseases and their symptoms, each child's parent completed the International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS

Exposure to outdoor dogs was associated to nocturnal coughing, odds ratio (OR) 0.64, with a confidence interval of 95% (95% CI) 0.43-0.95 and with atopic dermatitis (OR: 0.39; 95% CI: 0.20-0.76). Interestingly, exposure to outdoor cats was associated to nocturnal coughing (OR: 0.51; 95% CI: 0.32-0.83) and current rhinitis symptoms (OR: 0.59; 95% CI 0.36-0.97). After carrying out the multivariate analyses, only exposure to dogs, both indoor and outdoor, was significantly associated to a decrease in the prevalence of atopic dermatitis OR 0.40 (95% CI: 0.20-0.79) and OR 0.38 (95% CI: 0.18-0.83), respectively.

CONCLUSION

Our findings suggest that exposure to dogs, whether they be indoor or outdoor pets, is associated to a decreased prevalence in atopic dermatitis.

Molecular aspects of allergens in atopic dermatitis

PURPOSE OF REVIEW

Molecular allergology uses pure, mainly recombinant and structurally defined allergen molecules and allergen-derived epitopes to study mechanisms of IgE-associated allergy, to diagnose, and even predict the development of allergic manifestations and to treat and prevent IgE-associated allergies. Atopic dermatitis, a chronic inflammatory skin disease is almost always associated with IgE sensitization to allergens. However, also non-IgE-mediated pathomechanisms seem to be operative in atopic dermatitis and it is often difficult to identify the disease-causing allergens. Here we review recent work showing the usefulness of molecular allergology to study mechanisms of atopic dermatitis, for diagnosis and eventually for treatment and prevention of atopic dermatitis.

RECENT FINDINGS

IgE sensitization to airborne, food-derived, microbial allergens, and autoallergens has been found to be associated with atopic dermatitis. Using defined allergen molecules and non-IgE-reactive allergen derivatives, evidence could be provided for the existence of IgE- and non-IgE-mediated mechanisms of inflammation in atopic dermatitis. Furthermore, effects of epicutaneous allergen administration on systemic allergen-specific immune responses have been studied. Multi-allergen tests containing micro-arrayed allergen molecules have been shown to be useful for the identification of culprit allergens in atopic dermatitis and may improve the management of atopic dermatitis by allergen-specific immunotherapy, allergen avoidance, and IgE-targeting therapies in a personalized medicine approach.

SUMMARY

Molecular allergology allows for dissection of the pathomechanisms of atopic dermatitis, provides new forms of allergy diagnosis for identification of disease-causing allergens, and opens the door to new forms of management by allergen-specific and T cells-targeting or IgE-targeting interventions in a personalized medicine approach.

The skin microbiome: impact of modern environments on skin ecology, barrier integrity, and systemic immune programming

Skin barrier structure and function is essential to human health. Hitherto unrecognized functions of epidermal keratinocytes show that the skin plays an important role in adapting whole-body physiology to changing environments, including the capacity to produce a wide variety of hormones, neurotransmitters and cytokine that can potentially influence whole-body states, and quite possibly, even emotions. Skin microbiota play an integral role in the maturation and homeostatic regulation of keratinocytes and host immune networks with systemic implications. As our primary interface with the external environment, the biodiversity of skin habitats is heavily influenced by the biodiversity of the ecosystems in which we reside. Thus, factors which alter the establishment and health of the skin microbiome have the potential to predispose to not only cutaneous disease, but also other inflammatory non-communicable diseases (NCDs). Indeed, disturbances of the stratum corneum have been noted in allergic diseases (eczema and food allergy), psoriasis, rosacea, acne vulgaris and with the skin aging process. The built environment, global biodiversity losses and declining nature relatedness are contributing to erosion of diversity at a micro-ecological level, including our own microbial habitats. This emphasises the importance of ecological perspectives in overcoming the factors that drive dysbiosis and the risk of inflammatory diseases across the life course.