Additive effect between IL-13 polymorphism and cesarean section delivery/prenatal antibiotics use on atopic dermatitis: a birth cohort study (COCOA)

Association between gut microbiota and pan-dermatological diseases: a bidirectional Mendelian randomization research

Background

Gut microbiota has been associated with dermatological problems in earlier observational studies. However, it is unclear whether gut microbiota has a causal function in dermatological diseases.

Methods

Thirteen dermatological diseases were the subject of bidirectional Mendelian randomization (MR) research aimed at identifying potential causal links between gut microbiota and these diseases. Summary statistics for the Genome-Wide Association Study (GWAS) of gut microbiota and dermatological diseases were obtained from public datasets. With the goal of evaluating the causal estimates, five acknowledged MR approaches were utilized along with multiple testing corrections, with inverse variance weighted (IVW) regression serving as the main methodology. Regarding the taxa that were causally linked with dermatological diseases in the forward MR analysis, reverse MR was performed. A series of sensitivity analyses were conducted to test the robustness of the causal estimates.

Results

The combined results of the five MR methods and sensitivity analysis showed 94 suggestive and five significant causal relationships. In particular, the genus Eubacterium_fissicatena_group increased the risk of developing psoriasis vulgaris (odds ratio [OR] = 1.32, pFDR = 4.36 × 10-3), family Bacteroidaceae (OR = 2.25, pFDR = 4.39 × 10-3), genus Allisonella (OR = 1.42, pFDR = 1.29 × 10-2), and genus Bacteroides (OR = 2.25, pFDR = 1.29 × 10-2) increased the risk of developing acne; and the genus Intestinibacter increased the risk of urticaria (OR = 1.30, pFDR = 9.13 × 10-3). A reverse MR study revealed insufficient evidence for a significant causal relationship. In addition, there was no discernible horizontal pleiotropy or heterogeneity.

Conclusion

This study provides novel insights into the causality of gut microbiota in dermatological diseases and therapeutic or preventive paradigms for cutaneous conditions.

Allergy-associated biomarkers in early life identified by Omics techniques

The prevalence and severity of allergic diseases have increased over the last 30 years. Understanding the mechanisms responsible for these diseases is a major challenge in current allergology, as it is crucial for the transition towards precision medicine, which encompasses predictive, preventive, and personalized strategies. The urge to identify predictive biomarkers of allergy at early stages of life is crucial, especially in the context of major allergic diseases such as food allergy and atopic dermatitis. Identifying these biomarkers could enhance our understanding of the immature immune responses, improve allergy handling at early ages and pave the way for preventive and therapeutic approaches. This minireview aims to explore the relevance of three biomarker categories (proteome, microbiome, and metabolome) in early life. First, levels of some proteins emerge as potential indicators of mucosal health and metabolic status in certain allergic diseases. Second, bacterial taxonomy provides insight into the composition of the microbiota through high-throughput sequencing methods. Finally, metabolites, representing the end products of bacterial and host metabolic activity, serve as early indicators of changes in microbiota and host metabolism. This information could help to develop an extensive identification of biomarkers in AD and FA and their potential in translational personalized medicine in early life.

Effect of partially hydrolyzed synbiotic formula milk on weight gain of late preterm and term infants-a multicenter study

Introduction

Data on the effectiveness of hydrolyzed infant formula containing both pre- and probiotics (synbiotic formula) on the growth of infants is still scarce. This retrospective study was designed to evaluate the effect of a partially hydrolyzed synbiotic formula on growth parameters and the possible occurrence of major gastrointestinal adverse events or morbidities in infants born via cesarean section (C-section) delivery.

Methods

C-section-delivered term and late preterm infants who received either partially hydrolyzed synbiotic formula, standard formula, or maternal milk and followed at seven different hospitals from five different regions of Turkey, during a 1-year period with a minimum follow-up duration of 3 months were evaluated retrospectively. All the included infants were evaluated for their growth patterns and any kind of morbidity such as diarrhea, constipation, vomiting, infection, or history of hospitalization.

Results

A total of 198 infants (73 in the human milk group, 61 in the standard formula group, and 64 in the partially hydrolyzed synbiotic formula group) reached the final analysis. The groups were similar regarding their demographic and perinatal characteristics. No difference was observed between the three groups regarding gastrointestinal major side effects. Growth velocities of the infants in the human milk and partially hydrolyzed synbiotic formula groups during the first month of life were similar whereas the weight gain of infants in the standard formula group was significantly less than these two groups (p < 0.001). Growth velocities were similar among the three groups between 1st and 3rd months of age.

Discussion

A partially hydrolyzed synbiotic formula provided better weight gain in late-preterm and term infants who were delivered via C-section delivery compared to the standard formula during the first month of life. This weight gain was similar to the infants receiving exclusively human milk. This difference was not observed in length and head circumference gain. No difference was observed in any of the parameters during the 1st-3rd months of age. Specially formulated partially hydrolyzed synbiotic formulas may reverse at least some of the negative impacts of C-section delivery on the infant and help to provide better growth, especially during the early periods of life.

Maternal exposure to antibiotics and risk of atopic dermatitis in childhood: a systematic review and meta-analysis

Background

Although the association between maternal exposure to antibiotics and the risk of atopic dermatitis (AD) in childhood has been studied extensively, there still is a lack of clarity on the topic. The aim of this study was to summarize the published data and to examine if maternal exposure to antibiotics increases the risk of AD in childhood.

Methods

Systematic search was performed in PubMed, Scopus, Web of Science, and Embase for all types of studies on the review subject independent of any language restrictions and published up to 28th December 2022. Data was analyzed using random-effects model and presented as pooled odds ratio (OR) with 95% confidence intervals (CI).

Results

A total of 18 studies (5,354,282 mother-child pairs) were included. Maternal exposure to antibiotics was associated with an increased risk of AD in childhood (OR: 1.14, 95% CI: 1.06, 1.22, I²= 85%, p = 0.0003). The significance of the results was not affected by the location of the study (Asia or Europe). While subgroup analysis based on exposure assessment or diagnosis of AD demonstrated a tendency of increased risk of AD, the association was not statistically significant in multiple subgroups. Segregating data based on the timing of exposure did not affect the significance of the results for studies on all trimesters. However, there was no association between antibiotic exposure in the third trimester or just before delivery and the risk of childhood AD.

Conclusion

The results of this meta-analysis suggest that maternal exposure to antibiotics may lead to a modestly increased risk of AD in offspring. The evidence is limited by high interstudy heterogeneity and bias in exposure and outcome assessment. Future studies are needed to explore if the timing of exposure, the dose, the number of prescriptions, and the type of antibiotic affect this association.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023387233.

A cohort study of intrapartum group B streptococcus prophylaxis on atopic dermatitis in 2-year-old children

OBJECTIVE

To understand the occurrence of atopic dermatitis (AD) in children aged 2 years on exposure to maternal group B streptococcus (GBS) antibiotic prophylaxis (IAP).

DESIGN

Retrospective cohort study of 2909 mother-child pairs.

SETTING

Taixing People's Hospital in Eastern China.

PARTICIPANTS

Term infants born 2018-2019, followed longitudinally from birth to 2 years.

EXPOSURES

The GBS-IAP was defined as therapy with intravenous penicillin G or ampicillin or cefazolin ≥ 4 h prior to delivery to the mother. Reference infants were defined as born without or with other intrapartum antibiotic exposure.

OUTCOMES

The logistic regression models were employed to analyze the effect of intrapartum GBS prophylaxis on AD in 2-year-old children during delivery. Analysis was a priori stratified according to the mode of delivery and adjusted for relevant covariates.

RESULTS

The cohorts showed that preventive GBS-IAP was potentially associated with increased incidence of AD in children delivered vaginally according to logistic regression models before and after covariate-adjusted treatment (OR: 6.719,95% CI: 4.730-9.544,P < 0.001;aOR: 6.562,95% CI: 4.302-10.008, P < 0.001).

CONCLUSION

Prophylactic treatment of intrapartum GBS may raise the risk of AD in vaginally delivered children. These findings highlight the need to better understand the risk between childhood AD and current GBS-IAP intervention strategies.

Grape seed and skin extract, a potential prebiotic with anti-obesity effect through gut microbiota modulation

Background

Obesity is a worldwide health problem and a significant risk factor for diabetes and cardiovascular diseases. Gut microbiota (GM) plays an essential role in obesity, and prebiotics such as polyphenols could be one way to improve microbial dysbiosis-induced obesity.

Objective

This study was designed to assess the effectiveness of grape seed and skin extract (GSSE), and/or orlistat on obese rats fed with high fat diet by targeting GM modulations. The impact of treatments was also studied in non-obese rats.

Material and methods

Rats were rendered obese or kept with a standard diet for three months. Then they were treated either with GSSE or orlistat or with the combined treatment (GSOR) during three months and then sacrificed. Adipose tissues, blood and faeces were collected and analyzed.

Results

In obese rats and to a lesser extent in non-obese rats, treatments decreased the weight of various adipose tissues and the serum levels of cholesterol, LDL, triglycerides, lipase, and CRP and increased HDL and adiponectin. GSOR treatment was even more efficient that orlistat. Obese rats had less GM diversity than non-obese rats and orlistat reduced it even more. However, diversity was restored with GSSE and GSOR treatments. Potential pathogenic Streptococcus alactolyticus/gallolyticus species were greatly increased in obese rats and drastically reduced with the treatments, as wells as other potential pathobionts.

Conclusions

GSSE exerts beneficial effects in obese rats and restores, at least partially, the observed dysbiosis. GSOR induced the highest beneficial effect. Moreover, the various treatments could also enhance physiological and GM modifications in non obese rats.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13099-022-00505-0.

D-galactose Intake Alleviates Atopic Dermatitis in Mice by Modulating Intestinal Microbiota

Atopic dermatitis (AD) is one of the most prevalent, chronic and persistent inflammatory skin diseases closely associated with intestinal microbiota. To evaluate the effect of D-galactose intake on AD, we orally administered D-galactose to BALB/c mice whose ears and skin were treated with 2,4-dinitrochlorobenzene (DNCB). D-galactose alleviated DNCB-induced AD-like phenotypes such as redness, scaling/dryness and excoriation. Ear thickness was also decreased by D-galactose administration. Histopathological analysis revealed decreased epidermal thickening, infiltration of immune cells, especially mast cells, in the dermis. Total levels of serum IgE representing the immunological response of AD were decreased by D-galactose administration. Microbiota analysis showed that D-galactose administration restored gut microbiota profiles, which were altered in AD mice, characterized by increased abundance of Bacteroidetes and decreased abundance of Firmicutes. The increased abundance of Bacteroides and the decreased abundance of Prevotella and Ruminococcus were reversed by D-galactose treatment, following improvement of AD. Our results suggest the possible use of D-galactose as a prebiotic to alleviate AD by altering gut microbiota.

Clinical efficacy of fecal microbial transplantation treatment in adults with moderate-to-severe atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a remitting relapsing chronic eczematous pruritic disease. Several studies suggest that gut microbiota may influence AD by immune system regulation.

METHODS

We performed the first in-human efficacy and safety assessment of fecal microbiota transplantation (FMT) for AD adult patients. All patients received 2 placebo transplantations followed by 4 FMTs each 2 weeks apart. AD severity and fecal microbiome profile were evaluated by the Scoring Atopic Dermatitis Score (SCORAD), the weekly frequency of topical corticosteroids usage, and gut microbiota metagenomic analysis, at the study beginning, before every FMT, and 1-8 months after the last FMT.

RESULTS

Nine patients completed the study protocol. There was no significant change in the SCORAD score following the two placebo transplants. The average SCORAD score significantly decreased from baseline at Weeks 4-12 (before and 2 weeks after 4 times of FMT) (59.2 ± 34.9%, Wilcoxon p = .011), 50% and 75% decrease was achieved by 7 (77%) and 4 (44%) patients, respectively. At Week 18 (8 weeks after the last FMT) the average SCORAD score decreased from baseline at Week 4 (85.5 ± 8.4%, Wilcoxon p = .018), 50% and 75% decrease was achieved by 7 (77%) and 6 (66.7%) patients respectively. Weekly topical corticosteroids usage was diminished during the study and follow-up period as well. Two patients had a quick relapse and were switched to a different treatment. Two patients developed exacerbations alleviated after an additional fifth FMT. Metagenomic analysis of the fecal microbiota of patients and donors showed bacterial strains transmission from donors to patients. No adverse events were recorded during the study and follow-up period.

CONCLUSIONS

FMT may be a safe and effective therapeutic intervention for AD patients, associated with transfer of specific microbial species from the donors to the patients. Further studies are required to reconfirm these results.

Effect of early-life antibiotic exposure and IL-13 polymorphism on atopic dermatitis phenotype

BACKGROUND

Although atopic dermatitis (AD) is associated with certain gene variants, the rapidly increasing incidence of AD suggests that environmental factors contribute to disease development. In this study, we investigated the association of AD incidence and phenotype with antibiotic exposure within 6 months of age, considering the dose administered and genetic risk.

METHODS

This study included 1637 children from the COCOA cohort. Pediatric allergists assessed the presence of AD at each visit and obtained information about antibiotic exposure for more than 3 days. IL-13 (rs20541) polymorphism was genotyped by the TaqMan method. We stratified the AD phenotypes into four groups and used multinomial logistic regression models for analysis.

RESULTS

Antibiotic exposure within 6 months of age was found to increase the risk of AD within 3 years of life (aOR = 1.40; 95% CI, 1.09-1.81) in dose-dependent manner. Antibiotic exposure more than twice increased the risk of the early-persistent AD phenotype (aOR = 2.50; 95% CI, 1.35-4.63). There was a weak interaction between genetic polymorphisms and environmental factors on the development of AD (p for interaction = 0.06). Children with the IL-13 (rs20541) GA + AA genotype have a higher risk of the early-persistent AD phenotype when exposed to antibiotics more than twice than those with the IL-13 (rs20541) GG genotype and without exposure to antibiotics (aOR = 4.73; 95% CI, 2.01-11.14).

CONCLUSION

Antibiotic exposure within 6 months was related to the incidence of early-persistent AD and a dose-dependent increase in the incidence of AD in childhood, whose effect was modified by the IL-13 (rs20541) genotype.

Maternal antibiotic exposure during pregnancy and the risk of allergic diseases in childhood: A meta-analysis

BACKGROUND

Increasing studies suggest that antibiotic exposure during pregnancy may increase the risk of childhood allergic diseases; however, controversy still exists. Thus, we conducted this meta-analysis to evaluate the association between antibiotic use during pregnancy and childhood asthma/wheeze, eczema/atopic dermatitis, and food allergy.

METHODS

CENTRAL, EMBASE, and PubMed were searched for studies up to July 20, 2020. Cohort studies and case-control studies that estimated the association of antibiotic exposure in pregnancy with the risk of childhood asthma/wheeze, eczema/atopic dermatitis, and food allergy were included. A random-effects model or fixed-effects model was used to calculate the pooled estimates. The quality of the included studies was assessed by the Newcastle-Ottawa Scale (NOS). Stata12.0 software was used to analyze the association through a meta-analysis.

RESULTS

A total of 26 studies were included in the meta-analysis. The results showed that maternal antibiotic exposure in pregnancy and the summary OR for the risk of childhood asthma/wheeze was 1.29 (95% CI = 1.16-1.43), the summary OR for eczema/atopic dermatitis was 1.62 (95% CI = 1.16-2.27), and the pooled OR for food allergy was 1.36 (95% CI = 0.94-1.96).

CONCLUSIONS

Our results indicated that maternal antibiotic use during pregnancy might increase the risk of asthma/wheeze and eczema/atopic dermatitis but not food allergy in children. Further studies with larger sample size and robust multivariable adjustment are needed to confirm our findings. Nevertheless, the appropriate use of antibiotics during pregnancy is incredibly important, and healthcare professionals should be selective when prescribing antibiotics for pregnant women.

Comprehensive Analysis of the Effect of Probiotic Intake by the Mother on Human Breast Milk and Infant Fecal Microbiota

BACKGROUND

Human breast milk (HBM) contains optimal nutrients for infant growth. Probiotics are used to prevent disease and, when taken by the mother, they may affect infant microbiome as well as HBM. However, few studies have specifically investigated the effect of probiotic intake by the mother on HBM and infant microbiota at genus/species level. Therefore, we present a comprehensive analysis of paired HBM and infant feces (IF) microbiome samples before and after probiotic intake by HBM-producing mothers.

METHODS

Lactating mothers were administered with Lactobacillus rhamnosus (n = 9) or Saccharomyces boulardii capsules (n = 9), for 2 months; or no probiotic (n = 7). Paired HBM and IF samples were collected before and after treatment and analyzed by next-generation sequencing.

RESULTS

Forty-three HBM and 49 IF samples were collected and sequenced. Overall, in 43 HBM samples, 1,190 microbial species belonging to 684 genera, 245 families, 117 orders, and 56 classes were detected. In 49 IF samples, 372 microbial species belonging to 195 genera, 79 families, 42 orders, and 18 classes were identified. Eight of 20 most abundant genera in both HBM and IF samples overlapped: Streptococcus (14.42%), Lactobacillus, Staphylococcus, and Veillonella, which were highly abundant in the HBM samples; and Bifidobacterium (27.397%), Bacteroides, and Faecalibacterium, which were highly abundant in the IF samples. Several major bacterial genera and species were detected in the HBM and IF samples after probiotic treatment, illustrating complex changes in the microbiomes upon treatment.

CONCLUSION

This is the first Korean microbiome study in which the effect of different probiotic intake by the mother on the microbiota in HBM and IF samples was investigated. This study provides a cornerstone to further the understanding of the effect of probiotics on the mother and infant microbiomes.

Interactions Between IL-17 Variants and Streptococcus in the Gut Contribute to the Development of Atopic Dermatitis in Infancy

Purpose

Interleukin (IL)-17 variants and perturbations in the gut microbiota may influence the development of atopic dermatitis (AD). However, unifying principles for variants of host and microbe interaction remains unclear. We sought to investigate whether IL-17 variants and gut microbiota affect the development of AD in infancy.

Methods

Composition of the gut microbiota was analyzed in fecal samples from 99 normal healthy and 61 AD infants at 6 months of age. The associations between total immunoglobulin E (IgE), the scoring atopic dermatitis (SCORAD), short-chain fatty acids, transcriptome and functional profile of the gut measured in these subjects and Streptococcus were analyzed. IL-6 and IL-8 in the human intestinal epithelial cell line (HIEC-6) were measured after stimulation of IL-17 and Streptococcus mitis.

Results

In this study, Streptococcus was enriched in infants with AD and was higher in those with the GA + AA of IL-17 (rs2275913) variant. Streptococcus was positively correlated with IgE and SCORAD in infants with AD and GA + AA of IL-17. Butyrate and valerate were negatively correlated with Streptococcus and were decreased in infants with AD and GA + AA. Bacterial genes for oxidative phosphorylation induced by reduced colonization of Clostridium were decreased compared with normal and GG. In transcriptome analysis, lactate dehydrogenase A-like 6B was higher in infants with AD compared with healthy infants. IL-6 and IL-8 were increased in IL-17 and/or S. mitis-stimulated HIEC-6 cells.

Conclusions

These findings suggest that increased Streptococcus and A allele of IL-17 (rs2275913) may contribute to the pathogenesis of AD via modulation of the immune system in infancy.

Maternal exposures and the infant gut microbiome: a systematic review with meta-analysis

Early life, including the establishment of the intestinal microbiome, represents a critical window of growth and development. Postnatal factors affecting the microbiome, including mode of delivery, feeding type, and antibiotic exposure have been widely investigated, but questions remain regarding the influence of exposures in utero on infant gut microbiome assembly. This systematic review aimed to synthesize evidence on exposures before birth, which affect the early intestinal microbiome. Five databases were searched in August 2019 for studies exploring pre-pregnancy or pregnancy 'exposure' data in relation to the infant microbiome. Of 1,441 publications identified, 76 were included. Factors reported influencing microbiome composition and diversity included maternal antibiotic and probiotic uses, dietary intake, pre-pregnancy body mass index (BMI), gestational weight gain (GWG), diabetes, mood, and others. Eleven studies contributed to three meta-analyses quantifying associations between maternal intrapartum antibiotic exposure (IAP), BMI and GWG, and infant microbiome alpha diversity (Shannon Index). IAP, maternal overweight/obesity and excessive GWG were all associated with reduced diversity. Most studies were observational, few included early recruitment or longitudinal follow-up, and the timing, frequency, and methodologies related to stool sampling and analysis were variable. Standardization and collaboration are imperative to enhance understanding in this complex and rapidly evolving area.

Effect of a Short-Time Probiotic Supplementation on the Abundance of the Main Constituents of the Gut Microbiota of Term Newborns Delivered by Cesarean Section-A Randomized, Prospective, Controlled Clinical Trial

The gut microbiota plays a pivotal role in the maintenance of human health. Numerous factors, including the mode of delivery, impact early gut colonization in newborns. Recent research focuses on the use of probiotics in the prevention of gut dysbiosis in newborns delivered by cesarean section (CS). The objective of this study was to determine whether a probiotic supplement given to newborns delivered by CS during their stay in the maternity ward alters the pattern of early gut colonization by lactic acid bacteria versus potential pathogens. A prospective, randomized trial was conducted. In total, 150 newborns, born at 38–40 weeks gestational age and delivered by CS, were included in the study. They were randomized into the intervention group, supplemented orally with a probiotic containing Bifidobacterium breve PB04 and Lactobacillus rhamnosus KL53A, and the control group. Stool samples were obtained on days 5 and 6 of life and after one month of life and were analyzed for the presence and abundance of the main groups of bacteria. An application of two probiotic bacteria during the first days of life after CS resulted in quick and abundant colonization by days 5 and 6, with high populations of L. rhamnosus and B. breve. The applied bacterial strains were present in the majority of neonates one month after. The supplementation of term neonates delivered by cesarean section immediately after birth with a mixture of L. rhamnosus and B. breve enriched the gut microbiota composition with lactic acid bacteria.

Early life microbial exposures and allergy risks: opportunities for prevention

Allergies, including asthma, food allergy and atopic dermatitis, are increasing in prevalence, particularly in westernized countries. Although a detailed mechanistic explanation for this increase is lacking, recent evidence indicates that, in addition to genetic predisposition, lifestyle changes owing to modernization have an important role. Such changes include increased rates of birth by caesarean delivery, increased early use of antibiotics, a westernized diet and the associated development of obesity, and changes in indoor and outdoor lifestyle and activity patterns. Most of these factors directly and indirectly impact the formation of a diverse microbiota, which includes bacterial, viral and fungal components; the microbiota has a leading role in shaping (early) immune responses. This default programme is markedly disturbed under the influence of environmental and lifestyle risk factors. Here, we review the most important allergy risk factors associated with changes in our exposure to the microbial world and the application of this knowledge to allergy prevention strategies.

Association of IL13 genetic polymorphisms with atopic dermatitis: Fine mapping and haplotype analysis

BACKGROUND

Although previous studies had reported an important role of interleukin 13 (IL13) and its genetic polymorphisms in atopic dermatitis (AD), many of these previous reports focused on the missense variant rs20541 (Gln144Arg) without fine mapping of the gene region.

OBJECTIVE

To analyze the potential associations of other IL13 variants and their haplotypes with AD and assess total serum immunoglobulin E (IgE) levels.

METHODS

We performed fine mapping of single-nucleotide polymorphisms (SNPs) within the IL13 gene in a pilot study of 495 children with AD and 444 healthy controls. Then, we conducted a replication study of 757 children with AD and 1620 healthy controls to evaluate the association between the rs20541 variant of IL13 and AD.

RESULTS

In the pilot study, the rs20541 and rs1295685 SNPs in the 3'-untranslated region of IL13 had significant associations with AD (P < .001 and .01, respectively). In addition, 2 haplotypes (BL2_ht1 and BL2_ht2), which harbored the significant rs20541 and rs1295685 SNPs, had an association with AD (minimum P = .006). BL2_ht1 and BL2_ht2 had nominal signals associated with the total serum IgE levels (P < .05) but not with the severity of AD (P > .05). In the replication study, rs20541 was associated with the total serum IgE levels but not with the severity of AD.

CONCLUSION

An additional IL13 gene SNP, rs1295685, has a strong linkage disequilibrium with rs20541, and its haplotypes are associated with AD and the total serum IgE levels.

Biotherapeutic Approaches in Atopic Dermatitis

The skin microbiome plays a central role in inflammatory skin disorders such as atopic dermatitis (AD). In AD patients, an imbalance between pathogenic Staphylococcus aureus (S. aureus) and resident skin symbionts creates a state of dysbiosis which induces immune dysregulation and impairs skin barrier function. There are now exciting new prospects for microbiome-based interventions for AD prevention. In the hopes of achieving sustained control and management of disease in AD patients, current emerging biotherapeutic strategies aim to harness the skin microbiome associated with health by restoring a more diverse symbiotic skin microbiome, while selectively removing pathogenic S. aureus. Examples of such strategies are demonstrated in skin microbiome transplants, phage-derived anti-S. aureus endolysins, monoclonal antibodies, and quorum sensing (QS) inhibitors. However, further understanding of the skin microbiome and its role in AD pathogenesis is still needed to understand how these biotherapeutics alter the dynamics of the microbiome community; to optimize patient selection, drug delivery, and treatment duration; overcome rapid recolonization upon treatment cessation; and improve efficacy to allow these therapeutic options to eventually reach routine clinical practice.

Maternal exposure to antibiotics increases the risk of infant eczema before one year of life: a meta-analysis of observational studies

BACKGROUND

There are some conflicting evidences showing that maternal exposure to antibiotics may increase the risk of infant eczema. The present study aims to estimate the effect of prenatal antibiotics administration on infant eczema.

METHODS

According to the established inclusion criteria, eligible observational studies were collected by comprehensive database search. The qualities of the included studies were assessed using the Newcastle-Ottawa Scale. Effect sizes that were adjusted by multivariable models were extracted and combined. Publication bias was evaluated by visual inspection of funnel plot.

RESULTS

A total of seven observational studies were included. The qualities of the included studies were at moderate or high level. Prenatal antibiotics use was positively associated with eczema before one year of age [odds ratio (OR) = 1.93, 95% confidence interval (CI) 1.35-2.76]. In addition, antibiotics exposure in utero was likely to be related to eczema after one year of age (OR 1.21, 95% CI 0.98-1.49). The exposure to antibiotics during third trimester was not associated with infant eczema (OR 0.97, 95% CI 0.86-1.09).

CONCLUSIONS

Maternal exposure to antibiotics is associated with eczema by one-year age and may have a prolonged effect on eczema after 1-year age. The influence of timing of antibiotics exposure during pregnancy needs more studies to clarify.

Childhood inflammatory and metabolic disease following exposure to antibiotics in pregnancy, antenatally, intrapartum and neonatally

Background: There are concerns that the use of antibiotics before, during or immediately after pregnancy may have adverse effects on the neonatal gut microbiome and adversely affect the development of the infant immune system, leading to the development of childhood allergy, asthma, atopic disease and obesity. Methods: In this narrative review, we have explored a number of hypotheses, including the "Barker hypothesis", the "hygiene hypothesis", the link between inflammation and metabolic disease, and the influence of the neonatal gut microbiota on the development of the immune system in infants. Results: We found evidence to link the use of antibiotics before, during or immediately after pregnancy with an increased risk of childhood allergy, asthma, atopy and obesity. Conclusions: Although we found robust evidence to link antibiotic use in pregnancy with obesity and an "allergic triad" of asthma, eczema and hay fever, care must be taken when interpreting the findings because of the lack of adjustment for confounding variables in published studies. These may be (i) whether or not the mother had the same outcome variable (for example, asthma) as the infant, for which the mother may have received the antibiotics; (ii) the indication, timing or number of antibiotic courses given; (iii) the use of broad-spectrum or narrow-range antibiotics; (iv) the dose-dependent nature of the effector; and (v) the class of antibiotics used.

Antibiotics-Induced Dysbiosis of Intestinal Microbiota Aggravates Atopic Dermatitis in Mice by Altered Short-Chain Fatty Acids

PURPOSE

Alterations in the intestinal microbiota in early life affects the development of atopic dermatitis (AD) in humans. This study aimed to further investigate the effects of gut dysbiosis in early life in an ovalbumin (OVA)-induced mouse model of AD.

METHODS

The AD mouse model was developed by serial OVA sensitization and mice were treated with an antibiotic cocktail in their drinking water for 2 weeks before primary sensitization. Probiotics (Lactobacillus rhamnosus, 1 × 10⁹ CFU) or 100 μL of fresh fecal supernatant were orally administered daily from 1 week before the first sensitization until the end of the study.

RESULTS

The AD mice which received antibiotics had significantly aggravated phenotypes, including clinical score, transepidermal water loss, and histopathology, compared to those treated with healthy feces or probiotics. Total systemic immunoglobulin E production and skin interleukin (IL) 4 levels were significantly increased in the antibiotic-treated mice compared to the other groups. Antibiotic treatment also increased the levels of IL17 and group 3 innate lymphoid cells (ILC3) in the gut and significantly suppressed the production of short-chain fatty acids (SCFAs) and decreased the number FOXP3⁺ cells.

CONCLUSIONS

Our results suggest that the status of the gut microbiota in early life in the mouse may play a crucial role in AD development through intestinal SCFA production through regulate the numbers of CD4⁺IL17⁺/CD4⁺FOXP3⁺ regulatory T cells and ILC3s.

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.

Effects on developmental outcomes after cesarean birth versus vaginal birth in Chinese children aged 1-59 months: a cross-sectional community-based survey

OBJECTIVE

It is controversial whether the mode of delivery is associated with developmental outcome, and little was known about growth and development of cesarean children in poor rural areas in China. We aim to measure the development of both cesarean and vaginal-delivered children by Ages and Stages Questionnaires (ASQ) and explore the association between mode of delivery and developmental outcome in poor rural areas in China.

METHODS

Data were collected from a cross-sectional community-based survey, which recruited 1,755 vaginal delivered and cesarean children ages 1 to 59 months in eight counties of China. Caregivers of those children completed the Chinese version of ASQ-3 (ASQ-C) while physical examination andquestionnaires on socio-demographic and neonatal characteristics were conducted. Multivariate logistic regressions were used to measure the association between developmental delay and mode of delivery as well as each socio-demographic factor, respectively, after adjusting other socio-demographic characteristics.

RESULTS

The prevalence of suspected overall developmental delay was 23.4% in the cesarean group, compared with 21.3% in the vaginal delivered group, yet without statistical difference (p < 0.05). Developmental delay was also not significantly different between cesarean and vaginal delivered group in five ASQ domains of communication (7.7% vs. 7.8%, p = 0.949), fine motor (7.0% vs. 6.1%, p = 0.538), gross motor (8.5% vs. 6.4%, p = 0.154), problem solving (7.2% vs. 6.7%, p = 0.722) and personal social (8.0% vs. 7.9%, p = 0.960).

CONCLUSIONS

Our findings suggest that cesarean delivery does not increase or decrease the risk of suspected developmental in children delay as compared with vaginal delivery.

Neonatal oral fluid as a transmission route for bifidobacteria to the infant gut immediately after birth

Bifidobacteria are one of the most abundant bacterial groups in the infant gut microbiota and are closely associated with infant health and can potentially affect health in later life. However, the details regarding the source of bifidobacteria have yet to be completely elucidated. This study aimed to assess neonatal oral fluid (OF) as a transmission route for bifidobacteria to the infant gut during delivery. Neonatal OF and infant feces (IF) were collected immediately and one month after birth from 15 healthy vaginally delivered newborns. Bifidobacterium strains were isolated from OF and IF samples, and the similarity of strains between the OF-IF pairs was evaluated based on the average nucleotide identity (ANI) value. The 16S rRNA gene sequencing results revealed the presence of Bifidobacteriaceae at >1% relative abundance in all OF samples. Bifidobacterium strains were isolated from OF (9/15) and IF (11/15) samples, and those sharing high genomic homology (ANI values >99.5%) between the neonatal OF and IF samples were present in one-third of the OF-IF pairs. The results of this study indicate that viable bifidobacteria are present in neonatal OF and that OF at birth is a possible transmission route of bifidobacteria to the infant gut.

Clinical Characteristics and Genetic Variations in Early-Onset Atopic Dermatitis Patients

Background

Hereditary factors contribute to atopic dermatitis (AD) development. We developed the reverse blot hybridization assay (REBA) kit to simultaneously detect variations in skin barrier- and immune response-related genes prevalent in Korean AD patients.

Objective

To identify genetic variations and clinical characteristics that could predict early AD development.

Methods

We compared AD-related genetic variations between early-onset AD subjects and non-AD controls, and clinical characteristics and genetic variations between early- and late-onset AD subjects. We compared 28 early-onset AD subjects and 57 non-AD controls from a birth cohort and 108 early- (age ≤3 years) and 90 late-onset AD subjects and 189 non-AD controls from a university hospital. Genetic variations were detected via REBA.

Results

There were no differences in AD-related genetic variation between early-onset AD subjects and non-AD controls in the birth cohort. When the birth cohort and hospital populations were combined, early-onset AD subjects and non-AD controls showed different frequencies of genetic variations of KLK7, SPINK5 1156, DEFB1, IL5RA, IL12RB1a, and IL12RB1b. No differences in the frequency of genetic variations were observed between early- and late-onset AD subjects. Immunoglobulin E positivity for house dust mites was prevalent in late-onset AD subjects. A family history of atopic diseases was associated with early-onset AD.

Conclusion

No AD-related genetic variations could predict early AD development in Koreans, even though neonates with a family history of atopic diseases are likely to develop AD at ≤3 years of age. Environmental exposure may be more important than genetic variation in determining the onset age of AD.

Maternal Perinatal Dietary Patterns Affect Food Allergy Development in Susceptible Infants

BACKGROUND

The increasing incidence of food allergy (FA) can be attributed to interactions between genes and the environment, but these interactions are not yet fully clear.

OBJECTIVE

We aimed to evaluate the interaction between infant genetic variations and maternal dietary patterns to identify risk factors in the development of FA.

METHODS

We used the Cohort for Childhood Origin of Asthma and allergic diseases birth cohort of 1628 infants, born between 2007 and 2015. Maternal dietary intakes were assessed at 26 weeks of pregnancy using a food frequency questionnaire and grouped according to 5 dietary patterns. Infant cord blood samples were genotyped at 12 loci.

RESULTS

Among 1628 infants, 147 (9.0%) were diagnosed with FA based on history. A maternal confectionery diet characterized by a higher intake of baked and sugary products during pregnancy was associated with a higher prevalence of FA (adjusted odds ratio [OR] = 1.517, P = .02); this dietary pattern tended to be higher in trans fat (r = 0.498, P < .001). Development of FA was associated with longer periods of breastfeeding (adjusted OR = 1.792, P = .03), and this dietary pattern was more significantly related to the development of FA in infants with the homozygous TT genotype of CD14 (rs2569190) and more than 1 copy of GSTM1 and GSTT1.

CONCLUSIONS

A maternal confectionery diet during pregnancy that majorly consists of baked and sugary products, combined with a longer ensuing period of breastfeeding, may lead to the development of FA, suggesting a harmful effect of trans fats in the infant. Polymorphisms in CD14 and GST in the infant influence FA susceptibility.

The role of antimicrobial treatment during pregnancy on the neonatal gut microbiome and the development of atopy, asthma, allergy and obesity in childhood

INTRODUCTION

The use of antibiotics prenatally, during pregnancy, or neonatally may have adverse effects on the neonatal gut microbiome, and adversely affect the development of the infant immune system, leading to childhood atopy, asthma, allergy and obesity.

AREAS COVERED

Vaginal eubiosis and dysbiosis from molecular-based, cultivation-independent techniques, and how this affects the neonatal gut microbiome and early development of the immune system, the association between maternal antibiotics and the beneficial role of vitamin D in the development of atopy, asthma, allergy and obesity, efforts to reduce the use of antibiotics in pregnancy and therapeutic interventions such as vaginal 'seeding', probiotics, breastfeeding and neonatal dietary supplementation.

EXPERT OPINION

Currently available research gives insufficient attention to confounding variables. There remains uncertainty as to whether it is relevant that the mother suffered from the same condition as the purported infant outcome variable, for which she may have received antibiotics. In most studies, there is a lack of control for the number of antibiotic courses administered, the timing of use, the use of broad spectrum or narrow range antibiotics, the indication for antibiotics, the dose-dependent nature of the effect, the class of antibiotics used, or a varying degree of risk.

Microbiome and Allergic Diseases

Allergic diseases, such as respiratory, cutaneous, and food allergy, have dramatically increased in prevalence over the last few decades. Recent research points to a central role of the microbiome, which is highly influenced by multiple environmental and dietary factors. It is well established that the microbiome can modulate the immune response, from cellular development to organ and tissue formation exerting its effects through multiple interactions with both the innate and acquired branches of the immune system. It has been described at some extent changes in environment and nutrition produce dysbiosis in the gut but also in the skin, and lung microbiome, inducing qualitative and quantitative changes in composition and metabolic activity. Here, we review the potential role of the skin, respiratory, and gastrointestinal tract (GIT) microbiomes in allergic diseases. In the GIT, the microbiome has been proven to be important in developing either effector or tolerant responses to different antigens by balancing the activities of Th1 and Th2 cells. In the lung, the microbiome may play a role in driving asthma endotype polarization, by adjusting the balance between Th2 and Th17 patterns. Bacterial dysbiosis is associated with chronic inflammatory disorders of the skin, such as atopic dermatitis and psoriasis. Thus, the microbiome can be considered a therapeutical target for treating inflammatory diseases, such as allergy. Despite some limitations, interventions with probiotics, prebiotics, and/or synbiotics seem promising for the development of a preventive therapy by restoring altered microbiome functionality, or as an adjuvant in specific immunotherapy.

Of genes and microbes: solving the intricacies in host genomes

Microbiome research is a quickly developing field in biomedical research, and we have witnessed its potential in understanding the physiology, metabolism and immunology, its critical role in understanding the health and disease of the host, and its vast capacity in disease prediction, intervention and treatment. However, many of the fundamental questions still need to be addressed, including the shaping forces of microbial diversity between individuals and across time. Microbiome research falls into the classical nature vs. nurture scenario, such that host genetics shape part of the microbiome, while environmental influences change the original course of microbiome development. In this review, we focus on the nature, i.e., the genetic part of the equation, and summarize the recent efforts in understanding which parts of the genome, especially the human and mouse genome, play important roles in determining the composition and functions of microbial communities, primarily in the gut but also on the skin. We aim to present an overview of different approaches in studying the intricate relationships between host genetic variations and microbes, its underlying philosophy and methodology, and we aim to highlight a few key discoveries along this exploration, as well as current pitfalls. More evidence and results will surely appear in upcoming studies, and the accumulating knowledge will lead to a deeper understanding of what we could finally term a "hologenome", that is, the organized, closely interacting genome of the host and the microbiome.

Simultaneous detection of barrier- and immune-related gene variations in patients with atopic dermatitis by reverse blot hybridization assay

BACKGROUND

Hereditary factors are involved in the pathogenesis of atopic dermatitis (AD). However, AD-related gene variations are significantly different across ethnicities.

AIM

To identify mutations and single-nucleotide polymorphisms (SNPs) in barrier- or immune-related genes from Korean patients with AD and compare the variations with those observed in nonatopic healthy controls (HCs), and to use novel reverse blot hybridization assay (REBA) for AD-related gene variants.

METHODS

We carried out REBA to simultaneously detect variations in genes related to barrier or immune function, namely, FLG, SPINK5, KLK7, DEFB1, TNFα, KDR, FCER1A, IL4, IL5,IL5RA, IL9, IL10, IL12, IL12R, IL13 and IL18, from Korean patients with AD, and compared the variation to that in nonatopic healthy controls.

RESULTS

The homozygous mutants of KLK7 and SPINK5-2475, and the heterozygous mutants of FLG 3321delA, SPINK5-1156, DEFB1, KDR, IL5RA, IL9 and IL12RB1 were significantly more frequent in AD. It has been predicted that the larger the number of gene variants, the higher the odds ratio of AD prevalence; however, we did not find any significant correlation between the number of gene variants and AD severity.

CONCLUSION

Using REBA, we identified more genetic variants that can predict AD occurrence. We also verified that REBA can be used to easily and accurately detect multiple AD-related gene variants simultaneously. In addition, we identified a correlation between KLK7 mutation and AD in Koreans, which is the first such report, to our knowledge.

Microbiome in the Gut-Skin Axis in Atopic Dermatitis

The microbiome is vital for immune system development and homeostasis. Changes in microbial composition and function, termed dysbiosis, in the skin and the gut have recently been linked to alterations in immune responses and to the development of skin diseases, such as atopic dermatitis (AD). In this review, we summarize the recent findings on the gut and skin microbiome, highlighting the roles of major commensals in modulating skin and systemic immunity in AD. Although our understanding of the gut-skin axis is only beginning, emerging evidence indicates that the gut and skin microbiome could be manipulated to treat AD.

Differences in Genetic Variations Between Treatable and Recalcitrant Atopic Dermatitis in Korean

Purpose

Variations in barrier- or immune response-related genes are closely related to the development of atopic dermatitis (AD). This study was designed to identify genetic variations and clinical features to predict ‘recalcitrant AD.’

Methods

AD patients were classified as treatable and recalcitrant. Treatable AD patients showed satisfactory clinical improvement with basic and topical treatments. Recalcitrant AD patients used systemic immune-suppressants for over 4 weeks as they had not shown clinical improvement with basic and topical treatments. The frequency of gene variations in barrier- (FLG 3321delA, FLG K4022X, KLK7, SPINK 1156, SPINK 1188, SPINK 2475) and immune response- (DEFB1, KDR, IL-5RA, IL-9, and IL-12RB1a, b) related genes were compared between each AD group and the controls.

Results

Of all, 249 treatable AD and 32 recalcitrant AD were identified. Heterozygous mutations (Hetero) in KLK7 was more frequent in recalcitrant AD patients than treatable AD, without statistical significance. Hetero in DEFB1 was more frequent in treatable AD patients. However, no other significant genetic differences between treatable and recalcitrant AD was observed. Instead, higher initial Eczema Area Severity Index (EASI) score, serum immunoglobulin E (IgE) level, allergen specific IgE for house dust mites, and family history of atopic diseases were associated with recalcitrant AD with statistical significance.

Conclusions

According to our study, no genetic variation to predict recalcitrant AD was identified, suggesting that clinical manifestation, rather than genetic variations of AD patients is more likely to be an important factor in predicting the prognosis of AD. Further large-scale studies on the correlation between genetic variation and recalcitrant AD are needed.

Skin Colonization by Staphylococcus aureus Precedes the Clinical Diagnosis of Atopic Dermatitis in Infancy

Atopic dermatitis (AD) has a well-established association with skin colonization or infection by Staphylococcus aureus, which can exacerbate the disease. However, a causal relationship between specific changes in skin colonization during the first years of life and AD development still remains unclear. In this prospective birth cohort study, we aimed to characterize the association between skin colonization and AD development in 149 white infants with or without a family history of atopy. We assessed infants clinically and collected axillary and antecubital fossa skin swabs for culture-based analysis at birth and at seven time points over the first 2 years of life. We found that at age 3 months, S. aureus was more prevalent on the skin of infants who developed AD later on. S. aureus prevalence was increased on infants' skin at the time of AD onset and also 2 months before it, when compared with age-matched, unaffected infants. Furthermore, at AD onset, infants testing positive for S. aureus were younger than uncolonized subjects. In conclusion, our results suggest that specific changes in early-life skin colonization may actively contribute to clinical AD onset in infancy.

Influence of antibiotic use in early childhood on asthma and allergic diseases at age 5

BACKGROUND

In the past few decades, the prevalence of allergic diseases has increased rapidly worldwide. At the same time, the overuse of antibiotics has been observed, especially in Japan.

OBJECTIVE

To elucidate the association of early childhood antibiotic use with allergic diseases in later childhood at 5 years of age.

METHODS

Relevant data were extracted from the hospital-based birth cohort study, the Tokyo Children's Health, Illness and Development Study. To identify signs of asthma and allergic diseases in children, the International Study of Asthma and Allergies in Childhood questionnaire was used. Logistic regression models were applied to estimate the effect of antibiotic use on outcomes in later life.

RESULTS

Antibiotic exposure in children within the first 2 years of life was associated with current asthma (adjusted odds ratio [aOR] 1.72, 95% confidence interval [CI] 1.10-2.70), current atopic dermatitis (aOR 1.40, 95% CI 1.01-1.94), and current allergic rhinitis (aOR 1.65, 95% CI 1. 05-2.58) at 5 years of age. Analysis of the associations by type of antibiotics showed that cephem was associated with current asthma (aOR 1.97, 95% CI 1.23-3.16) and current rhinitis (aOR 1.82, 95% CI 1.12-2.93), and macrolide was associated with current atopic dermatitis (aOR 1.58, 95% CI 1.07-2.33).

CONCLUSION

Our findings suggest that antibiotic use within the first 2 years of life was a risk factor for current asthma, current atopic dermatitis, and current allergic rhinitis in 5-year-old children.

Effect of Synbiotic on the Gut Microbiota of Cesarean Delivered Infants: A Randomized, Double-blind, Multicenter Study

We determined the effect of short-chain galacto-oligosaccharides (scGOS), long-chain fructo-oligosaccharides (lcFOS) and Bifidobacterium breve M-16V on the gut microbiota of cesarean-born infants. Infants were randomized to receive a standard formula (control), the same with scGOS/lcFOS and B. breve M-16V (synbiotic), or with scGOS/lcFOS (prebiotic) from birth until week 16, 30 subjects born vaginally were included as a reference group. Synbiotic supplementation resulted in a higher bifidobacteria proportion from day 3/5 (P < 0.0001) until week 8 (P = 0.041), a reduction of Enterobacteriaceae from day 3/5 (P = 0.002) till week 12 (P = 0.016) compared to controls. This was accompanied with a lower fecal pH and higher acetate. In the synbiotic group, B. breve M-16V was detected 6 weeks postintervention in 38.7% of the infants. This synbiotic concept supported the early modulation of Bifidobacterium in C-section born infants that was associated with the emulation of the gut physiological environment observed in vaginally delivered infants.

The microbiome in asthma

PURPOSE OF REVIEW

Asthma is a complex and heterogeneous disease with strong genetic and environmental components that manifests within a variety of clinical features and diverse patterns of immune responses. Asthma prevalence has dramatically increased over the last decade in Westernized societies, thereby suggesting a key function of environmental factors in disease promotion and development.

RECENT FINDINGS

'Early-life' microbial exposure and bacterial colonization are crucial for the maturation and the education of the immune system. The commensal flora is also critical in order to maintain immune homeostasis at the mucosal surfaces and may consequently play an important function in allergic disease development. Recent evidence demonstrates that asthma influences and is also impacted by the composition and function of the human intestinal and respiratory microbiome.

SUMMARY

In this review, we summarize the most recent findings on how asthma development is connected with respiratory and intestinal microbial dysbiosis. We highlight and discuss recent research that reveals the existence of a 'gut-lung' microbial axis and its impact on asthma development. We also analyze how 'early-life' microbial exposure affects the immune response and the consequences for asthma development.

Trying to understand the genetics of atopic dermatitis

Atopic dermatitis (AD) is a common and complex skin disease associated with both genetic and environmental factors. Loss-of-function mutations in the filaggrin gene, encoding a structural protein with an important role in epidermal barrier function, constitutes a well recognised susceptibility locus for AD. Further, genome-wide association studies (GWAS), including large meta-analyses, have discovered 38 additional susceptibility loci with genome-wide significance. However, the reported variations only explain a fraction of the overall heritability of AD. Here, we summarize the current knowledge of the role of filaggrin and the epidermal differentiation complex as well as the results of GWAS, with an emphasis on novel findings and observations made in the past two years. Additionally, we present first results of exome sequencing for AD and discuss novel therapeutic strategies.

The Microbiome, Timing, and Barrier Function in the Context of Allergic Disease

Allergic disease affects millions. Despite many advances in our understanding of the immune system in the past century, the physiologic underpinning for the existence of allergy remains largely mysterious. Food allergies, in particular, have increased dramatically in recent years, adding a new sense of urgency to unraveling this mystery. The concurrence of significant lifestyle changes in Western societies with increasing disease prevalence implies a causal link. Demographic variables that influence the composition and function of the commensal microbiota early in life seem to be most important. Identifying the evolutionary and physiologic foundations of allergic disease and defining what about our modern environment is responsible for its increased incidence will provide insights critical to the development of new approaches to prevention and treatment.

Dynamics of Gut Microbiota According to the Delivery Mode in Healthy Korean Infants

Microbial colonization of the infant gut is unstable and shows a wide range of diversity between individuals. Gut microbiota play an important role in the development of the immune system, and an imbalance in these organisms can affect health, including an increased risk of allergic diseases. Microbial colonization of young infants is affected by the delivery mode at birth and the consequent alterations of gut microbiota in early life affect the development of allergic diseases. We investigated the effects of the delivery mode on the temporal dynamics of gut microbiota in healthy Korean infants. Fecal samples were collected at 1-3 days, 1 month, and 6 months after birth in six healthy infants. Microbiota were characterized by 16S rRNA shotgun sequencing. At the first and third days of life, infants born by vaginal delivery showed a higher richness and diversity of gut microbiota compared with those born by cesarean section. However, these differences disappeared with age. The Bacteroides genus and Bacteroidetes phylum were abundant in infants born by vaginal delivery, whereas Bacilli and Clostridium g4 were increased in infants born by cesarean section. The Firmicutes phylum and Bacteroides genus showed convergent dynamics with age. This study demonstrated the effect of delivery mode on the dynamics of gut microbiota profiles in healthy Korean infants.

Cesarean section delivery and development of food allergy and atopic dermatitis in early childhood

BACKGROUND

Delivery by Cesarean section (CS) may predispose to allergic disorders, presumably due to alterations in the establishment of normal gut microbiota in early infancy. In this study, we sought to investigate the association between CS and physician-diagnosed food allergy and atopic dermatitis during the first 3 years of life, using data from a homogeneous, population-based, birth cohort.

METHODS

A total of 459 children born and cared for in the same tertiary maternity unit were examined at birth and followed up at 1, 6, 12, 18, 24, 30 and 36 months of age. Participants with symptoms suggestive of food allergy or atopic dermatitis were evaluated by a pediatric allergy specialist to confirm the diagnosis based on well-defined criteria.

RESULTS

The rate of CS was 50.8% (n = 233). Food allergy was diagnosed in 24 participants (5.2%) while atopic dermatitis was diagnosed in 62 children (13.5%). Cesarean section (OR 3.15; 95% CI 1.14-8.70), atopic dermatitis of the child (OR 3.01; 95% CI 1.18-7.80), parental atopy (OR 4.33; 95% CI 1.73-12.1), and gestational age (OR 1.57; 95% CI 1.07-2.37) were significant and independent predictors of food allergy. Children with at least one allergic parent delivered by CS had higher probability of developing food allergy compared with vaginally delivered children of non-allergic parents (OR 10.0; 95% CI 3.06-32.7). Conversely, the effect of CS on atopic dermatitis was not significant (OR 1.35; 95% CI 0.74-2.47).

CONCLUSIONS

Delivery by CS predisposes to the development of food allergy but not atopic dermatitis in early childhood. Cesarean section delivery seems to upregulate the immune response to food allergens, especially in children with allergic predisposition.

Prevalence of and risk factors for atopic dermatitis: A birth cohort study of infants in southeast Turkey

BACKGROUND

Atopic dermatitis (AD) is most common in the first year of life. The aim of this study was to determine the prevalence of and risk factors for AD in a birth cohort of infants from southeast Turkey.

METHODS

Adana Paediatric Allergy Research (ADAPAR) birth cohort study was derived from 1377 infants who were born in Cukurova University, Medical Hospital, Adana, Turkey between February 2010 and February 2011. At birth, a physical examination was performed, cord blood samples were taken, and the mother completed a baseline questionnaire that provided data on gestational conditions, family history of allergic diseases and environmental exposures. Follow-up visits scheduled at 3, 6, and 12 months included an infant physical examination and an extended questionnaire. Skin prick test was performed and food-specific IgE levels were measured at 6 and 12 months. Atopic dermatitis was diagnosed based on confirmatory examination by a physician.

RESULTS

Of the 1377 infants enrolled, 59 (4.3%) were diagnosed with AD as of 12 months. Maternal allergic disease (ORs 6.28, 95% CI 1.03-38.30; p=0.046), maternal infection during gestation (ORs 3.73, 95% CI 1.25-11.09; p=0.018), and presence of food allergy (ORs 13.7, 95% CI 3.07-61.0; p=0.001) were identified as risk factors for AD. Breastfeeding and cord blood IgE levels were not identified as risk factors.

CONCLUSIONS

In this cohort we found prevalence of AD as 4.3% during the first year of life. Positive family history of atopic diseases, prenatal infections and presence of food allergy are the risk factors for early presentation of AD.

Delivery Mode, Duration of Labor, and Cord Blood Adiponectin, Leptin, and C-Reactive Protein: Results of the Population-Based Ulm Birth Cohort Studies

Background

Numerous studies have reported associations between delivery mode and health outcomes in infancy and later life. Previous smaller studies indicated a relationship between delivery mode and newborn inflammation potentially constituting a mediating factor. We aimed to determine the influence of delivery mode and duration of labor on cord blood concentrations of adiponectin, leptin, and high-sensitivity C-reactive protein (hs-CRP).

Methods

In the Ulm SPATZ Health Study, 934 singleton newborns and their mothers were recruited during their hospital stay in the University Medical Center Ulm, Southern Germany, from 04/2012-05/2013. Inflammatory biomarkers were measured by ELISAs (n = 836). Delivery mode was analyzed categorically (elective cesarean (reference), active labor delivery: emergency cesarean, assisted vaginal, and spontaneous vaginal); duration of labor continuously. Following log-transformation, linear regression was used to estimate geometric means ratios (GMR) adjusted for potential confounders for the effects of delivery mode and duration of labor on each biomarker separately. Independent replication was sought in the similarly conducted Ulm Birth Cohort Study recruited from 11/2000-11/2001.

Results

Individually, active labor delivery modes as well as increasing duration of labor were associated with higher leptin and hs-CRP concentrations. After mutual adjustment, the associations with delivery modes were attenuated but those for duration of labor remained statistically significant (GMR (95%CI) 1.10 (1.00; 1.21) and 1.15 (1.04; 1.27) for leptin and hs-CRP per hour of labor, respectively). No significant adjusted associations were observed between delivery modes and adiponectin concentrations. These findings were replicated in an independent birth cohort study.

Conclusions

Cord blood leptin and hs-CRP concentrations were associated with duration of labor rather than delivery mode. Further research is warranted to investigate these associations with additional cytokines involved in inflammatory response to delineate the inflammatory profile. Subsequently, research on determinants of these associations and their role in development of chronic disease is needed.

How informative is the mouse for human gut microbiota research?

The microbiota of the human gut is gaining broad attention owing to its association with a wide range of diseases, ranging from metabolic disorders (e.g. obesity and type 2 diabetes) to autoimmune diseases (such as inflammatory bowel disease and type 1 diabetes), cancer and even neurodevelopmental disorders (e.g. autism). Having been increasingly used in biomedical research, mice have become the model of choice for most studies in this emerging field. Mouse models allow perturbations in gut microbiota to be studied in a controlled experimental setup, and thus help in assessing causality of the complex host-microbiota interactions and in developing mechanistic hypotheses. However, pitfalls should be considered when translating gut microbiome research results from mouse models to humans. In this Special Article, we discuss the intrinsic similarities and differences that exist between the two systems, and compare the human and murine core gut microbiota based on a meta-analysis of currently available datasets. Finally, we discuss the external factors that influence the capability of mouse models to recapitulate the gut microbiota shifts associated with human diseases, and investigate which alternative model systems exist for gut microbiota research.

Recent advances in epidemiology and prevention of atopic eczema

Atopic dermatitis (AD), named also atopic eczema, is a chronic relapsing inflammatory skin disease with a considerable social and economic burden. The primum movens of AD is in most cases a genetic and/or immune-supported defect of the skin barrier, facilitating penetration and sensitization to food or airborne allergens, as well as infections by Staphylococcus aureus, herpes simplex virus, or other microbes. New pathogenetic concepts have generated new approaches to prevention and therapy of AD. In particular, the daily use of emollients in newborns at high risk of AD has shown interesting results, with a reduction in the cumulative incidence of AD ranging from 32% to 50% of the treated infants. On the other hand, the AD preventive efficacy of food and/or inhalant allergen avoidance has been questioned, and supplementation strategies (vitamin D, probiotics, or other compounds) need to be further investigated.