Analysis of familial aggregation of atopic eczema and other atopic diseases by ODDS RATIO regression models

Recent Advances in Phytochemical-Based Topical Applications for the Management of Eczema: A Review

Eczema (atopic dermatitis, AD) is a skin disease characterized by skin barrier dysfunction due to various factors, including genetics, immune system abnormalities, and environmental triggers. Application of emollients and topical drugs such as corticosteroids and calcineurin inhibitors form the mainstay of treatments for this challenging condition. This review aims to summarize the recent advances made in phytochemical-based topical applications to treat AD and the different carriers that are being used. In this review, the clinical efficacy of several plant extracts and bioactive phytochemical compounds in treating AD are discussed. The anti-atopic effects of the herbs are evident through improvements in the Scoring Atopic Dermatitis (SCORAD) index, reduced epidermal thickness, decreased transepidermal water loss, and alleviated itching and dryness in individuals affected by AD as well as in AD mouse models. Histopathological studies and serum analyses conducted in AD mouse models demonstrated a reduction in key inflammatory factors, including thymic stromal lymphopoietin (TSLP), serum immunoglobulin E (IgE), and interleukins (IL). Additionally, there was an observed upregulation of the filaggrin (FLG) gene, which regulates the proteins constituting the stratum corneum, the outermost layer of the epidermis. Carriers play a crucial role in topical drug applications, influencing dose delivery, retention, and bioavailability. This discussion delves into the efficacy of various nanocarriers, including liposomes, ethosomes, nanoemulsions, micelles, nanocrystals, solid-lipid nanoparticles, and polymeric nanoparticles. Consequently, the potential long-term side effects such as atrophy, eruptions, lymphoma, pain, and allergic reactions that are associated with current topical treatments, including emollients, topical corticosteroids, topical calcineurin inhibitors, and crisaborole, can potentially be mitigated through the use of phytochemical-based natural topical treatments.

Mode of delivery and offspring atopic dermatitis in a Swedish nationwide study

BACKGROUND

Atopic dermatitis is a common chronic childhood disease associated with significant morbidity and healthcare costs. There is a known association between caesarean section and asthma, but the relationship between caesarean section and offspring atopic dermatitis remains uncertain.

METHODS

We conducted a register-based nationwide cohort study including children born in Sweden between January 2006 and December 2018. Data on health and socioeconomic variables were extracted from the national registers for children aged ≤5 years. Time-to-event analyses were used to calculate hazard ratios (HR) with 95% confidence intervals (CI) adjusting for confounders and familial factors.

RESULTS

1,399,406 children were included (6,029,542 person-years at risk). Atopic dermatitis was observed in 17.2% of the 1,150,896 children born by vaginal delivery and 18.3% of the 248,510 born by caesarean section. The mean age of onset of atopic dermatitis was 2.72 years (SD 1.8). Birth by caesarean section was associated with a higher risk of atopic dermatitis (adj-HR 1.12, 95% CI: 1.10-1.14). A higher risk of atopic dermatitis was found in children born by instrumental vaginal delivery (adj-HR 1.10, 1.07-1.13); emergency caesarean section (adj-HR 1.12, 1.10-1.15), and elective caesarean section (adj-HR 1.13, 1.10-1.16) than uncomplicated vaginal delivery in children <1 year of age. Similar hazards were observed in those ≥1 year of age. In sibling control analysis, greater risks remained in children aged <1 year but not in age ≥1 year.

CONCLUSIONS

In our study population, it was observed that children born by caesarean section or instrumental vaginal delivery were at higher risk of early childhood atopic dermatitis. Although familial confounding attenuates the risk in children aged ≥1 year, this was not observed in the first year of life.

Allergic rhinitis is associated with atmospheric SO2: Follow-up study of children from elementary schools in Ulsan, Korea

OBJECTIVES

The purpose of this study was to examine the association of allergic rhinitis with air pollutant concentrations using the follow-up data of elementary school children in Ulsan, Korea.

METHODS

All students of four elementary schools in Ulsan, South Korea were surveyed at two-year intervals. The survey used data collected five times, over a nine-year period from June 2009 to April 2018. The questionnaire used in the survey was a modified version of the ISAAC (International society of asthma and allergy of children) questionnaire. A skin prick test (SPT) was performed with 24 standard antigens. To estimate the levels of exposure to outdoor air pollution, the concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and particulate matter 10 μm or less in diameter (PM10) were used. As a dependent variable, a history of allergic rhinitis diagnosed by a doctor during the last 1-year was considered. Logistic regression analysis was used to select variables suitable for the statistical model. The selected variables were then used to assess their association with the dependent variable using the generalized estimation equation.

RESULTS

Among environmental factors, SO2 was associated with a high risk and PM10 was associated with a low risk of allergic rhinitis. The risk of allergic rhinitis from living in a house built within the last year was high, and the risk from living in a multi-family house or apartment was higher than that from living in a segregated house. History of allergic diseases in the family was a high-risk factor for allergic rhinitis. There was a relationship between a history of bronchiolitis at less than 2 years of age and a high risk of allergic rhinitis. Boys were at a higher risk than girls.

CONCLUSION

From the follow-up data of elementary school students in Ulsan, Korea, the concentration of SO2, which is an indicator of the degree of industrialization, was related to the prevalence of allergic rhinitis. Among all the risk factors, history of allergic disease in the parents was the most important factor, and the study reconfirmed the results of the previous studies.

Familial aggregation of atopic dermatitis and co-aggregation of allergic diseases in affected families in Taiwan

BACKGROUND

Atopic dermatitis (AD) is contributed from a result of genetic and environmental interaction. The evidence for familial aggregation in AD has been reported but population-based studies and co-aggregation with other allergic diseases are rarely reported.

OBJECTIVE

This study examined familial aggregation and heritability of atopic dermatitis (AD) and to estimate the relative risks (RRs) of other allergic diseases in individuals with relatives diagnosed with AD.

METHODS

We used Taiwan National Health Insurance Research Database to identify all registered beneficiaries (n = 26,525,074) in 2015; among them, 1,248,594 individuals had AD. We estimated familial risks of AD and other allergic diseases by using marginal Cox proportional models.

RESULTS

Prevalence of AD in individuals with relatives affected with atopic dermatitis was 3.1-fold higher than the general population (12.4 % vs. 4.0 %, respectively). The adjusted relative risks (RR) for individuals with an affected first-degree relative (FDR) was 2.25 (95 % CI, 2.25-2.26). The adjusted RRs for subjects with an affected parent, an affected offspring or an affected sibling was 2.39 (95 % CI, 2.37-2.41), 2.26 (95 % CI, 2.24-2.28) and 2.30 (95 % CI, 2.29-2.31) respectively. The RRs in individuals with an FDR with AD was 1.34 (95 %CI, 1.34 - 1.34) for asthma and 1.23 (95 %CI, 1.23-1.24) for allergic rhinitis.

CONCLUSION

This nationwide study ascertains that a family history of atopic dermatitis is a risk factor for atopic dermatitis. Individuals with relatives affected by atopic dermatitis have slightly higher risks of developing asthma and allergic rhinitis.

How does parental history of atopic disease predict the risk of atopic dermatitis in a child? A systematic review and meta-analysis

BACKGROUND

Parental history of atopic disease is a well-established risk factor for the development of atopic dermatitis (AD), but several aspects of this association remain unclear.

OBJECTIVE

We sought to determine the association of parental history of atopic disease with AD in offspring.

METHODS

We searched PubMed and EMBASE through June 2018 for relevant records and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled odds ratios (ORs) with 95% CI were calculated using random-effects models.

RESULTS

A total of 163 records covering 149 unique studies were included. Of these, 119 studies were included in the meta-analysis. Individuals with parental history of atopic disease had increased odds of AD (OR, 1.81; 95% CI, 1.65-1.99). Parental asthma (OR, 1.56; 95% CI, 1.18-2.05) and allergic rhinitis (OR, 1.68; 95% CI, 1.34-2.11) had a smaller effect than AD (OR, 3.30; 95% CI, 2.46-4.42). The effect of maternal and paternal history was comparable for all atopic diseases. An increase in odds was observed when comparing the effect of having 1 (OR, 1.30; 95% CI, 1.15-1.47) or 2 atopic parents (OR, 2.08; 95% CI, 1.83-2.36), as well as having a parent with 1 (OR, 1.49; 95% CI, 1.28-1.74) or more atopic diseases (OR, 2.32; 95% CI, 1.92-2.81).

CONCLUSIONS

This study provides evidence-based risk estimates that may guide physicians who counsel parents with a history of atopic disease about their children's risk of AD. This information is of particular importance for future efforts toward establishing prophylactic interventions for AD on a general population level.

Milk: an exosomal microRNA transmitter promoting thymic regulatory T cell maturation preventing the development of atopy?

Epidemiological evidence confirmed that raw cow's milk consumption in the first year of life protects against the development of atopic diseases and increases the number of regulatory T-cells (Tregs). However, milk's atopy-protective mode of action remains elusive.This review supported by translational research proposes that milk-derived microRNAs (miRs) may represent the missing candidates that promote long-term lineage commitment of Tregs downregulating IL-4/Th2-mediated atopic sensitization and effector immune responses. Milk transfers exosomal miRs including the ancient miR-155, which is important for the development of the immune system and controls pivotal target genes involved in the regulation of FoxP3 expression, IL-4 signaling, immunoglobulin class switching to IgE and FcϵRI expression. Boiling of milk abolishes milk's exosomal miR-mediated bioactivity. Infant formula in comparison to human breast- or cow's milk is deficient in bioactive exosomal miRs that may impair FoxP3 expression. The boost of milk-mediated miR may induce pivotal immunoregulatory and epigenetic modifications required for long-term thymic Treg lineage commitment explaining the atopy-protective effect of raw cow's milk consumption.The presented concept offers a new option for the prevention of atopic diseases by the addition of physiological amounts of miR-155-enriched exosomes to infant formula for mothers incapable of breastfeeding.

The effect of parental allergy on childhood allergic diseases depends on the sex of the child

BACKGROUND

The parent-of-origin effect is important in understanding the genetic basis of childhood allergic diseases and improving our ability to identify high-risk children.

OBJECTIVE

We sought to investigate the parent-of-origin effect in childhood allergic diseases.

METHODS

The Isle of Wight Birth Cohort (n= 1456) has been examined at 1, 2, 4, 10, and 18 years of age. Information on the prevalence of asthma, eczema, rhinitis, and environmental factors was obtained by using validated questionnaires. Skin prick tests were carried out at ages 4, 10, and 18 years, and total IgE measurement was carried out at 10 and 18 years. Parental history of allergic disease was assessed soon after the birth of the child, when maternal IgE levels were also measured. Prevalence ratios (PRs) and their 95% CIs were estimated, applying log-linear models adjusted for confounding variables.

RESULTS

When stratified for sex of the child, maternal asthma was associated with asthma in girls (PR, 1.91; 95% CI, 1.34-2.72; P= .0003) but not in boys (PR, 1.29; 95% CI, 0.85-1.96; P= .23), whereas paternal asthma was associated with asthma in boys (PR, 1.99; 95% CI, 1.42-2.79; P< .0001) but not in girls (PR, 1.03; 95% CI, 0.59-1.80; P= .92). Maternal eczema increased the risk of eczema in girls (PR, 1.92; 95% CI, 1.37-2.68; P= .0001) only, whereas paternal eczema did the same for boys (PR, 2.07; 95% CI, 1.32-3.25; P = .002). Similar trends were observed when the effect of maternal and paternal allergic disease was assessed for childhood atopy and when maternal total IgE levels were related to total IgE levels in children at ages 10 and 18 years.

CONCLUSIONS

The current study indicates a sex-dependent association of parental allergic conditions with childhood allergies, with maternal allergy increasing the risk in girls and paternal allergy increasing the risk in boys. This has implications for childhood allergy prediction and prevention.

Exposure to gene-environment interactions before 1 year of age may favor the development of atopic dermatitis

BACKGROUND

The aims of this study were to determine (1) the prevalence of atopic dermatitis (AD) in Seoul, Korea, and (2) the influence of environmental and genetic factors on disease risk.

METHODS

A questionnaire survey was conducted in 5,036 primary school children and 4,607 middle school children in 2008. For each child, a modified version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and a questionnaire assessing exposure to environmental variables were completed.

RESULTS

In primary school children, the lifetime prevalence of itchy eczema was 24.3%, the 12-month prevalence of itchy flexural eczema was 18.0%, the lifetime prevalence of AD diagnosis was 31.3%, and the 12-month prevalence of AD treatment was 14.5%. In middle school children, the corresponding rates were 16.0, 10.8, 22.1, and 8.3%, respectively. These rates are significantly higher than those reported in similar studies conducted in 1995 and 2000. In both primary and middle school children, a parental history of allergic disease and a history of having moved into a newly built house before 1 year of age were independently associated with a risk for current AD. For current AD, the prevalence odds ratio was higher in the subgroup with both a genetic and a specific environmental risk factor than in the subgroup with no risk factor or subgroups with only one risk factor.

CONCLUSIONS

The prevalence of AD in primary and middle school children in Seoul has increased. Its development may be influenced by gene-environment interactions, particularly before 1 year of age.

Association between maternal allergic rhinitis and asthma on the prevalence of atopic disease in offspring

BACKGROUND

Asthma is a common co-morbidity of allergic rhinitis (AR). The prevalence of these two allergic diseases has increased in China and has been shown to cluster in families independently. This study evaluated the association between maternal AR (presenting with or without asthma) and the allergic conditions in offspring.

METHODS

Women (n = 592) diagnosed with AR were recruited for this study; 379 patients presented with AR and 213 presented with both AR and asthma. Total serum IgE levels and nasal eosinophil counts were analyzed and correlated with disease presentation.

RESULTS

The prevalence of allergic conditions in offspring of mothers diagnosed with AR and asthma was significantly higher than the prevalence observed in children born to mothers presenting with AR only. Maternal total serum IgE and eosinophil counts were predictive of atopy in offspring. Children born to mothers presenting with persistent moderate-to-severe AR had the highest risk of developing atopic conditions (OR 6.26, 95% CI 3.26-12.02). Maternal age of 25-30 years at delivery was also associated with a higher risk for the allergic disease in offspring compared to maternal age of 36-40 (OR 2.13, 95% CI 1.31-3.47).

CONCLUSIONS

The severity of maternal AR, asthma co-morbidity, elevated serum IgE levels and nasal eosinophilia were all associated with an increased risk of offspring developing allergic conditions. Children born to older mothers were protected against developing atopic disease.

Family eczema-history in 2-year-olds with eczema; a prospective, population-based study. The PACT-study, Norway

Background

A maternal line of inheritance regarding eczema has been described in several studies, whereas others find associations to both a maternal as well as a paternal line of inheritance. When studying family history of eczema symptoms, cohort studies including siblings are rare. Time point for assessing family eczema-history could be of importance when studying the associations between family eczema-history and children with eczema, as parents with unaffected children may not recall mild symptoms in other siblings or their own disease history. We therefore aimed to study the associations between reported eczema in mother, father and siblings and reported eczema in index child where information on family history was collected at two different ages of index child.

Methods

Parents/children participating in The Prevention of Allergy among Children in Trondheim (PACT) study were given questionnaires on reported eczema symptoms in mother, father and siblings at 6 weeks and 1 year. When index child was 2 years of age, a detailed questionnaire on different health issues with emphasize on different allergy related disorders were filled in.

Results

Both maternal and paternal reports on eczema were significantly associated with eczema in index child. Reporting family eczema-history at 1 year (N = 3087), "eczema sibling only" [adjusted odds ratio (aOR) = 3.13 (2.27-4.33)] as well as all other family-groups containing siblings with eczema were strongly associated with eczema 2 years. When family eczema-history was reported at 6 weeks (N = 2657), reporting of "eczema sibling only" was not associated to reported eczema at 2 years in index child [aOR = 1.31 (0.77-2.23)].

Conclusions

Having sibling(s) with eczema strengthened the associations between maternal and paternal reports on eczema with eczema in index child only when exposure was reported at 1 year. These findings indicate that results from questionnaires-based studies of family eczema-history depend on whether or not index child has yet developed eczema.

Trial registration

ISRCTN: ISRCTN28090297

An update on the genetics of atopic dermatitis: scratching the surface in 2009

A genetic basis for atopic dermatitis (AD) has long been recognized. Historic documents allude to family history of disease as a risk factor. Before characterization of the human genome, heritability studies combined with family-based linkage studies supported the definition of AD as a complex trait in that interactions between genes and environmental factors and the interplay between multiple genes contribute to disease manifestation. A summary of more than 100 published reports on genetic association studies through mid-2009 implicates 81 genes, in 46 of which at least 1 positive association with AD has been demonstrated. Of these, the gene encoding filaggrin (FLG) has been most consistently replicated. Most candidate gene studies to date have focused on adaptive and innate immune response genes, but there is increasing interest in skin barrier dysfunction genes. This review examines the methods that have been used to identify susceptibility genes for AD and how the underlying pathology of this disease has been used to select candidate genes. Current challenges and the potential effect of new technologies are discussed.

Maternal asthma, its control and severity in pregnancy, and the incidence of atopic dermatitis and allergic rhinitis in the offspring

OBJECTIVE

To evaluate the relationship between maternal asthma, its level of control and severity during pregnancy, and atopic dermatitis (AD) and allergic rhinitis (AR) incidence in children.

STUDY DESIGN

A cohort of 26 265 singletons born to mothers with and without asthma (1990-2002) was constituted by use of 3 Quebec databases. Mothers with asthma had to have received >or=1 diagnosis and >or=1 prescription for asthma 2 years before or during pregnancy. Asthma control and severity during pregnancy was based on validated indexes. ICD-9 codes 691 and 477 allowed us to identify cases of AD and AR.

RESULTS

Maternal asthma during pregnancy was associated with an increased AD risk (adjusted hazard ratio: 1.11, 95% confidence interval: 1.02-1.21), but not of AR (adjusted hazard ratio: 1.04, 95% confidence interval: 0.91-1.20) in children. Asthma control and severity were not associated with either outcome. Maternal AR and intranasal corticosteroid use during pregnancy increased the risk of childhood AR by 70% and 45%.

CONCLUSIONS

Children of mothers with asthma or AR during pregnancy should be closely monitored to diagnose and treat AD and AR as early as possible.

Impact of topical calcineurin inhibitors on quality of life in patients with atopic dermatitis

This review considers randomized trials of topical calcineurin inhibitors in atopic dermatitis that have included quality-of-life (QOL) data. Relatively few trials were identified and several different QOL measures have been used, partly because trial subjects included adults, children, and the parents of affected infants. Tacrolimus 0.1% and 0.03% ointment and pimecrolimus 1% cream were found to be superior to vehicle treatment in terms of QOL for active AD. In adults, tacrolimus 0.1% ointment provided a greater improvement in QOL than the 0.03% strength. Pimecrolimus 1% cream was superior to vehicle treatment for flare prevention in the studies that contained QOL outcomes but no data are available for tacrolimus ointment in this regard. QOL data comparing topical calcineurin inhibitors with other active treatments such as topical corticosteroids are sparse and it would be useful for future randomized trials to include QOL measures as a primary outcome.

The link between the epidemics of obesity and allergic diseases: does obesity induce decreased immune tolerance?

There is increasing epidemiological evidence that obesity increases the risk of asthma, atopic, and autoimmune diseases. We hypothesize that the increase in these diseases is caused, at least in part, by decreased immunological tolerance as a consequence of immunological changes induced by adipokines (e.g. leptin and adiponectin) and cytokines [e.g. interleukin 6 (IL6) and tumor necrosis factor alpha (TNFalpha)] secreted by white adipose tissue. The increasing body weight increases the levels of circulating IL6, leptin, and TNFalpha. IL6 and leptin down-regulate the activity of regulatory T-lymphocytes (Tregs). Additionally, adiponectin, which decreases with increasing obesity, down-regulates the secretion of IL10 from macrophages and adipocytes. These changes in IL6, leptin, and IL10 decrease the regulatory effect of Tregs resulting in decreased immunological tolerance to antigens. In pregnant women, these obesity-induced immunological changes might be transmitted to the fetus by epigenetic inheritance thereby increasing the risk of atopic disease. We propose that obesity results in immunological changes resulting in decreased immunological tolerance to antigens and skewing of the immune system towards a Th2 cytokine profile increasing the risk of allergy and other immune-mediated diseases. Furthermore, this hypothesis offers a unifying explanation for the observation that older siblings appear to confer protection against atopic diseases, preeclampsia, and certain autoimmune diseases. More studies are definitely needed to explore further the immunological effects of obesity and its possible effects on allergic disease.

A genealogical assessment of heritable predisposition to asthma mortality

RATIONALE

Asthma is a multifactorial disease; genetic factors have been suggested but have not been well defined.

OBJECTIVES

This study examined evidence for a heritable component to asthma mortality using a unique data resource consisting of Utah death certificates linked to a genealogy of Utah.

METHODS

Cases were defined as individuals whose death certificate listed asthma as a cause of death in a registry of all Utah deaths since 1904 (n = 1,553). The genealogical index of familiality analysis was used to compare the average relatedness of asthma deaths to the expected relatedness in the Utah population. Relative risks for asthma death in relatives of individuals who died of asthma are provided for close and distant relatives.

MEASUREMENTS AND MAIN RESULTS

The genealogical index of familiality identified a significantly higher average relatedness in cases (P < 0.001), even when close relationships were ignored. In addition, a significantly increased risk of dying of asthma was observed in first-degree relatives of cases (relative risk = 1.69, P < 0.001) and in second-degree relatives of cases (relative risk = 1.34, P = 0.003).

CONCLUSIONS

These results support a heritable contribution to asthma mortality.

Atopic dermatitis

Atopic dermatitis is an especially common and frustrating condition, and the prevalence is increasing. The disease can adversely affect the quality of life of patients and caregivers. Significant advances in our understanding of the pathogenesis have led to improvements in therapy. Patient and caregiver education, avoidance of potential triggering factors, optimal skin care, and pharmacotherapy offer the potential for good control for most patients.

Oral and vulvar changes in pregnancy

The endocrinologic, immunological, and vascular changes that occur during pregnancy are far-reaching. These systemic factors produce profound local impact on the physiology and pathology of the oral cavity, vagina, and vulva. Physiological changes can be expected and tolerable or of such severity that they are viewed as pathological. Existing disease can be exacerbated and dermatoses specific to pregnancy can erupt. Each of these conditions can pose potentially challenging treatment considerations.

Therapeutic and prophylactic effects of PUVA photochemotherapy on atopic dermatitis-like lesions in NC/Nga mice

BACKGROUND

Psoralens and ultraviolet A radiation (PUVA) photochemotherapy has been used for severe cases of atopic dermatitis (AD). To understand the mechanisms of action is important for the choice of treatments. AD-like lesions can be induced experimentally in NC/Nga mice.

OBJECTIVES

To evaluate clinically and histologically the therapeutic and prophylactic effects of PUVA on AD-like dermatitis using NC/Nga mice.

METHODS

PUVA therapy was performed with intraperitoneal injection of 4 mg/kg of 8-methoxypsoralen (8-MOP) and 4 J/cm(2)-UVA irradiation before and after development of AD-like lesions in NC/Nga mice which had been maintained in a conventional room (Conv-NC/Nga mice). Clinical skin conditions were evaluated periodically by a clinical severity score defined. Lesions were histologically examined in haematoxylin-eosin or toluidine blue-stained sections. Plasma levels of total IgE were measured at various time points.

RESULTS

In Conv-NC/Nga mice infested with mite, AD-like lesions started to develop at 8 week of age and thereafter increased in severity score. PUVA therapy at lower does than minimal phototoxic dose suppressed the development of dermatitis and was also therapeutically effective against established lesions. Proliferation of dermal mast cells in AD-like lesions was suppressed, but IgE hyperproduction was not changed after PUVA.

CONCLUSIONS

These observations suggest that PUVA photochemotherapy reveals not only therapeutic but also prophylactic effects on human AD.

Correlation of serum total IgE, eosinophil granule cationic proteins, sensitized allergens and family aggregation in atopic dermatitis patients with or without rhinitis

Atopic dermatitis (AD) is a complex disease with both a genetic background and environmental interactions. Although multiple linkage-analyses about AD have been studied, there have been only a few family aggregation tests of AD or perennial allergic rhinitis (AR) to date. The association of allergen-specific IgE in AD and atopic dermatitis with allergic perennial rhinitis (ADR) have also been seldom discussed. The purpose of this study was to evaluate family aggregation and assess allergen-specific IgE in patients with AD and ADR. We also planned to investigate the effect of family history of AD on the prevalence of allergen-specific antibodies. The serum levels of IgE, eosinophil cationic protein (ECP) and major basic protein (MBP) were measured and compared in patients with AD and those with ADR. Proportional analysis compared allergen-specific IgE between AD and ADR. The family aggregation was conducted to estimate the odds ratio for various atopic diseases in different family members. Total IgE and allergen-specific antibodies in serum were compared between those patients who had AD with AR and those without. The result revealed that allergic rhinitis is the most common concomitant atopic disease associated with AD. The ADR group was more likely to have serum mite-, cockroach-, and feather-specific IgE. The positive rates for wheat, peanut and soybean were higher in those AD without rhinitis. In the family aggregation of AD, the odds ratio for siblings was higher than for parents, the ratios for brother and sister were 9.91 and 8.75, respectively. However, the odds ratio for parents of ADR was higher than siblings; the ratios for father and mother of ADR were 8.22 and 2.94, respectively. AD patients with family histories of AD were more likely to have mite-, soybean-, and peanut-specific antibodies in their serum. We concluded that aeroallergens are the most important allergens aggravating atopic diseases in Taiwan. Food plays an important role in the pathogenesis of AD. Measurement of serum total IgE combined with the MAST-CLA test could be helpful in the diagnosis of atopic diseases. The differential aggregation tendency for AD and ADR implicated the complexity of the gene-environment interaction in these atopic diseases.

Familial susceptibility to severe respiratory infection in early life

Lower respiratory tract infections (LRTI) are common in the first year of life and are mostly caused by viruses. Severity of LRTI in infants is associated with early-life environmental factors. Genetic association studies also suggest a role of heredity in susceptibility to acute bronchiolitis. We designed a case control study to further investigate relative importance of familial influences in risk of LRTI in early childhood compared to environmental factors. From a hospital database, we selected 1,308 children (436 cases; 872 controls) living in Oxfordshire. Cases were children under age 5 years admitted to hospital with LRTI. Parental history and other exposures were recorded in cases and controls by postal questionnaire. Maternal history of asthma increased the risk of severe LRTI in the first year of life, independent of subsequent asthma in a child. History of maternal bronchiolitis also increased the risk of infant LRTI. These results further support the possibility that genetic factors play an important role in susceptibility to severe viral respiratory infections in early life, and suggest that this effect may be independent of subsequent childhood asthma.

Association of parental eczema, hayfever, and asthma with atopic dermatitis in infancy: birth cohort study

OBJECTIVE

To evaluate the association of parental history of atopic disease with childhood atopic dermatitis, and to examine the relative strength of associations with maternal and paternal disease.

DESIGN

Mothers were recruited to the Avon longitudinal study of parents and children (ALSPAC) from the eighth week of pregnancy. Before parturition, both parents were asked, separately, to report their lifetime history of eczema, asthma, and hayfever. Parents reported symptoms of atopic dermatitis in their children at ages 6, 18, 30, and 42 months.

RESULTS

Of 8530 children with complete information on rash at ages 6, 18, 30, and 42 months, 7969 had complete information on maternal atopic disease and 5658 on maternal and paternal atopic disease. There was a strong association between parental eczema and childhood atopic dermatitis: odds ratio 1.69 (95% confidence interval, 1.47 to 1.95) for maternal eczema only, 1.74 (1.44 to 2.09) for paternal eczema only, and 2.72 (2.09 to 3.53) for eczema in both parents. Associations with parental asthma or hayfever were attenuated after controlling for parental eczema. There was no evidence that associations with maternal atopy were stronger than with paternal.

CONCLUSIONS

Associations between parents' atopic disease and the risk of atopic dermatitis in offspring vary according to the type of atopic disease in the parents, but not according to parental sex. These results are at variance with previous studies reporting stronger associations with maternal than paternal atopy, and suggest that there is no "parent-of-origin" effect in atopic dermatitis. Parental eczema may be a better marker than parental asthma/hayfever in predisposing to childhood eczema.

Perinatal predictors of atopic dermatitis occurring in the first six months of life

OBJECTIVE

Previous studies of predictors of atopic dermatitis have had limited sample size, small numbers of variables, or retrospective data collection. The purpose of this prospective study was to investigate several perinatal predictors of atopic dermatitis occurring in the first 6 months of life.

DESIGN

We report findings from 1005 mothers and their infants participating in Project Viva, a US cohort study of pregnant women and their offspring. The main outcome measure was maternal report of a provider's diagnosis of eczema or atopic dermatitis in the first 6 months of life. We used multiple logistic regression models to assess the associations between several simultaneous predictors and incidence of atopic dermatitis.

RESULTS

Cumulative incidence of atopic dermatitis in the first 6 months of life was 17.1%. Compared with infants born to white mothers, the adjusted odds ratio (OR) for risk of atopic dermatitis among infants born to black mothers was 2.41 (95% confidence interval [CI]: 1.47, 3.94) and was 2.58 among infants born to Asian mothers (95% CI: 1.27, 5.24). Male infants had an OR of 1.76 (95% CI: 1.24, 2.51). Increased gestational age at birth was a predictor (OR: 1.14; 95% CI: 1.02, 1.27, for each 1-week increment), but birth weight for gestational age was not. Infants born to mothers with a history of eczema had an OR of 2.67 (95% CI: 1.74, 4.10); paternal history of eczema also was predictive, although maternal atopic history was more predictive than paternal history. Several other perinatal, social, feeding, and environmental variables were not related to risk of atopic dermatitis.

CONCLUSIONS

Black and Asian race/ethnicity, male gender, higher gestational age at birth, and family history of atopy, particularly maternal history of eczema, were associated with increased risk of atopic dermatitis in the first 6 months of life. These findings suggest that genetic and pre- and perinatal influences are important in the early presentation of this condition.

Family history and risk of atopic dermatitis in children up to 4 years

BACKGROUND

The aetiology of atopic dermatitis (AD) is presumably multi-factorial, with interactions between genetic and environmental factors.

OBJECTIVE

To investigate the relation between atopic family history and development of AD up to 4 years.

METHODS

Using annual questionnaires, we studied the cumulative incidence of AD in 0-4-year-olds in a prospective birth cohort of 4089. Atopic diseases in parents and siblings were recorded at birth. The occurrence of serum immunoglobulin E (IgE) antibodies to inhalant and food allergens was analysed in 2614 4-year-olds, and AD was divided into non-IgE-associated and IgE-associated.

RESULTS

Of the children without atopic parents, 27.1% developed AD; of those with single or double parental atopic history, 37.9% and 50.0%, respectively, did so. The effects of parental history of eczema and of atopic respiratory disease (ARD) did not differ significantly, nor did those of maternal and paternal history. Parental history of ARD increased the risk significantly more for IgE-associated AD than for non-IgE-associated AD (odds ratio (OR) 2.0; 95% confidence interval (CI) 1.5-2.8 vs. OR 1.3; 95% CI 1.0-1.8), whereas the two forms lacked major differences in the effect of parental eczema. A history of eczema in older siblings was a risk indicator for both forms of AD (OR 2.1; 95% CI 1.4-3.3 vs. OR 1.8; 95% CI 1.2-2.6).

CONCLUSIONS

We found no difference between the effects of maternal and paternal atopic history. Parental eczema was a risk factor for AD irrespective of its association with IgE, but parental history of ARD mainly increased the risk of IgE-associated AD.

The epidemiology of atopic dermatitis in Italian schoolchildren

BACKGROUND

Atopic dermatitis (AD) is common in children in industrialized countries. Only one large population study on its prevalence has been conducted in Italy, based on self-report questionnaire. The present study was designed to estimate the prevalence of AD in schoolchildren in Italy by dermatologists' assessment and by UK Working Party criteria, and to investigate associated symptoms and factors.

METHODS

Cross-sectional survey on a random sample of 9-year-old schoolchildren from seven Italian cities. Children were examined by experienced dermatologists. Parents and teachers answered standardized questionnaires.

RESULTS

Of the 1369 children examined, 88 had a diagnosis of AD, with an estimated point prevalence of 5.8% (95% CI 4.5-7.1) in the reference population. The reported lifetime prevalence was 15.2 (95% CI 12.2-18.2) for AD, 11.9% (95% CI 9.0-14.8) for asthma, and 17.6% (95% CI 14.6-20.7) for rhino-conjunctivitis. The strongest associated factor was the presence of AD in at least one parent. No association of AD with maternal smoking during pregnancy, birth weight, maternal age at the time of the child birth and breast-feeding was observed. The environmental characteristics of the house and the school did not correlate with the prevalence of AD. Episodes of lower respiratory tract infections were associated with asthma, and to a lower extent also with AD and rhinitis.

CONCLUSIONS

The prevalence of doctor-diagnosed AD in Italian schoolchildren is comparable to those reported for other developed countries. Family history of atopy was the single most important associated factor, while the complex interplay of environmental factors remains to be elucidated.

Resident skin-specific gammadelta T cells provide local, nonredundant regulation of cutaneous inflammation

The function of the intraepithelial lymphocyte (IEL) network of T cell receptor (TCR) gammadelta(+) (Vgamma5(+)) dendritic epidermal T cells (DETC) was evaluated by examining several mouse strains genetically deficient in gammadelta T cells (delta(-/-) mice), and in delta(-/-) mice reconstituted with DETC or with different gammadelta cell subpopulations. NOD.delta(-/-) and FVB.delta(-/-) mice spontaneously developed localized, chronic dermatitis, whereas interestingly, the commonly used C57BL/6.delta(-/-) strain did not. Genetic analyses indicated a single autosomal recessive gene controlled the dermatitis susceptibility of NOD.delta(-/-) mice. Furthermore, allergic and irritant contact dermatitis reactions were exaggerated in FVB.delta(-/-), but not in C57BL/6.delta(-/-) mice. Neither spontaneous nor augmented irritant dermatitis was observed in FVB.beta(-/-) delta(-/-) mice lacking all T cells, indicating that alphabeta T cell-mediated inflammation is the target for gammadelta-mediated down-regulation. Reconstitution studies demonstrated that both spontaneous and augmented irritant dermatitis in FVB.delta(-/-) mice were down-regulated by Vgamma5(+) DETC, but not by epidermal T cells expressing other gammadelta TCRs. This study demonstrates that functional impairment at an epithelial interface can be specifically attributed to absence of the local TCR-gammadelta(+) IEL subset and suggests that systemic inflammatory reactions may more generally be subject to substantial regulation by local IELs.

The prevalence and descriptive epidemiology of atopic dermatitis in Singapore school children

BACKGROUND

Atopic dermatitis is a common disease that appears to be increasing in frequency during recent decades. Most of the studies are based on the Western population, and there are few data in the Asian population.

OBJECTIVES

To determine the prevalence and descriptive epidemiology of atopic dermatitis among school children in the general community in Singapore.

METHODS

This is a questionnaire study of 12 323 students done over a 1-year period, comprising 7 year olds (4605), 12 year olds (3940) and 16 year olds (3778) from 19 primary and 17 secondary schools randomly selected in Singapore. All children had a complete cutaneous examination. The diagnosis of atopic dermatitis was based on the U.K. Working Party diagnostic criteria. The questionnaire was translated into Chinese and both the English and Chinese versions were issued simultaneously to the students.

RESULTS

The 1-year period prevalence of atopic dermatitis was 20.8%. Atopic dermatitis was present in 22.7% of 7 year olds, 17.9% of 12 year olds and 21.5% of 16 year olds. The overall sex ratio was equal. There were slightly more boys with atopic dermatitis among the younger children (6 and 12 year olds, 1.18 : 1 and 1.19 : 1, respectively) but more girls were affected (1.57 : 1) among the 16 year olds. Atopic dermatitis was more common among the Chinese (21.6%) and Malays (19.8%) compared with the Indians (16%) and other races (14%). The onset of the disease occurred before the age of 10 years in 49.5% of the 16 year olds. "Pure" atopic dermatitis without concomitant respiratory allergies was noted in 788 respondents (30.7%); 1775 (69.3%) suffered from a "mixed" type, with 34.3% having allergic rhinitis, 9.5% having asthma and 25.5% having both asthma and allergic rhinitis. More boys had atopic dermatitis and concomitant respiratory allergies whereas more girls were affected with "pure" atopic dermatitis alone (1.4 : 1). At least one first-degree family member with atopy was noted in 1435 children (56%): atopic dermatitis (70%), asthma (62%) and allergic rhinitis (68%). Among siblings with one parent with atopic dermatitis, 37% had either a father or a mother with atopic dermatitis. Common aggravating factors reported included exercise, heat and sweating, grass intolerance, thick clothing and stress. Pityriasis alba was noted in 25% of the study population, keratosis pilaris in 13% and ichthyosis vulgaris in 8%. Most respondents had mild to moderate atopic dermatitis that could be controlled with a fairly simple regimen of moisturizers, topical steroids, antihistamines and antibiotics.

CONCLUSIONS

The high prevalence of atopic dermatitis in Singapore is similar to that observed in developed countries, suggesting that environmental factors may be important in determining the expression of the disease.

Connections among parent and child atopic illnesses

This study investigated parent-child connections for the atopic illnesses of asthma, eczema, food allergies, and hay fever, in a sample of 325 families. Parents reported whether they or their children currently had each condition and rated the frequency and intensity of its episodes; these ratings were combined to estimate illness severity. The data revealed five main findings. First, chi-square parent-child concordance analyses indicated that children of parents with any of the atopic illnesses studied were significantly more likely to develop that same disease than were children of parents without the illness. Second, children were progressively more likely to have at least one atopic illness when the number of their parents who were atopic increased from zero to two. Third, the number of atopic illnesses in the children was associated with the number of atopic illnesses in the parents. These three findings augment the evidence for genetic factors in the development of atopic illnesses and suggest that the atopies of each parent may contribute to an aggregate, generalized risk for their children. Fourth, maternal atopy was more strongly related to the children's asthma and hay fever than paternal atopy. Fifth, the severity of the children's specific atopic illnesses was not affected by the number of their parents who had the same condition and was not strongly related to the severity of their parents' condition.

Does allergy in parents depend on allergy in their children? Recall bias in parental questioning of atopic diseases. Multicenter Allergy Study Group

BACKGROUND

A positive atopic family history has proved to be one important risk factor for the development of atopic diseases in offspring. However, many epidemiologists are concerned about the accuracy and reliability of data because responses to questionnaires can be biased for many reasons.

OBJECTIVE

The study investigated whether responses of parents questioned about their atopic diseases change depending on the development of atopic symptoms in their children.

METHODS

During a prospective birth cohort study on atopy in children (the Multicenter Allergy Study) parents filled out questionnaires twice within 2 years about their atopic diseases. Differences between the 2 responses were examined by log-linear and logistic regression models depending on the diagnosed atopy status of the study children.

RESULTS

Mothers tended to report more atopic diseases in the second questioning than in the first, indicating a nondifferential misclassification. Fathers were influenced by the development of atopic diseases in their children: they reported significantly more atopic diseases if the child developed atopic illness with atopic dermatitis.

CONCLUSION

In parental questioning about atopic diseases, a recall bias must be considered for the association of atopic family history and atopy in children. Especially in case-control and cross-sectional studies, such misclassifications can result in biased estimates of prognosis and risk factors.

Genetics of allergy and asthma

LEARNING OBJECTIVES

This article summarizes the latest information regarding the role of genetic influences in the development of allergic disorders and asthma and reviews our current information on some of the most likely genes responsible for these conditions. After reading this article, the reader will have a better understanding of the current molecular biologic techniques that are being used to understand complex genetic disorders such as allergies and asthma. The reader should understand the value of how this genetic insight will lead to the recognition of the presence of specific subtypes of these disorders that require unique therapeutic interventions. This information can also be used to identify genetically at risk children and thereby offer earlier intervention. Finally, understanding the genetic causes of allergies and asthma will lead to the development of the next--hopefully curative--generation of asthma and allergy therapeutics.

DATA SOURCES

A detailed literature search was conducted. Studies considered relevant, well performed, and appropriately controlled were used. Only human studies are included and only the English language literature was reviewed. Some of the information presented is based on the author's own research experience.

STUDY SELECTION

Material was only taken from peer-reviewed journals and appropriate reviews.

RESULTS AND CONCLUSIONS

Asthma and allergic diseases are examples of disorders having an unmistakable genetic predisposition, but in the absence of a classic Mendelian inheritance pattern. These "complex" genetic disorders are caused by the interactions of multiple interacting genes some having protective value and some contributing to disease development and with each gene having its own variable tendency to be expressed. In addition, these disorders require the presence of appropriate environmental triggers for their expression. One approach to identifying the genetic basis for these conditions is to perform a genome-wide search in which the location of the disease-causing gene on a human chromosome is identified and nearby genes that may be responsible are subsequently identified. An alternative approach to identifying heritable components to asthma and allergy is to evaluate disordered structure or regulation within genes known to be involved in these disorders. Using these approaches, studies have suggested that genes within the cytokine gene cluster on chromosome 5 (including interleukins-3, -4, -5, -9, and -13), chromosome 11 (the beta chain of the high affinity IgE receptor), chromosome 16 (the IL-4 receptor), and chromosome 12 (stem cell factor, interferon-gamma, insulin growth factor, and Stat 6 [IL-4 Stat]) may contribute to asthma and allergy development. In addition, data support involvement of genes involved in antigen-presentation (MHC class II genes) and T cell responses (the T cell receptor alpha chain). Finally, disease-contributing alleles may be present on genes for the beta-adrenergic receptor, 5-lipoxygenase, and leukotriene C4 synthase.