Revisiting the hygiene hypothesis for allergy and asthma

The role of epigenetics in the development of childhood asthma

Introduction: The development of childhood asthma is caused by a combination of genetic factors and environmental exposures. Epigenetics describes mechanisms of (heritable) regulation of gene expression that occur without changes in DNA sequence. Epigenetics is strongly related to aging, is cell-type specific, and includes DNA methylation, noncoding RNAs, and histone modifications.Areas covered: This review summarizes recent epigenetic studies of childhood asthma in humans, which mostly involve studies of DNA methylation published in the recent five years. Environmental exposures, in particular cigarette smoking, have significant impact on epigenetic changes, but few of these epigenetic signals are also associated with asthma. Several asthma-associated genetic variants relate to DNA methylation. Epigenetic signals can be better understood by studying their correlation with gene expression, which revealed higher presence and activation of blood eosinophils in asthma. Strong associations of nasal methylation signatures and atopic asthma were identified, which were replicable across different populations.Expert commentary: Epigenetic markers have been strongly associated with asthma, and might serve as biomarker of asthma. The causal and longitudinal relationships between epigenetics and disease, and between environmental exposures and epigenetic changes need to be further investigated. Efforts should be made to understand cell-type-specific epigenetic mechanisms in asthma.

Associations between evaporative cooling and dust-mite allergens, endotoxins, and β-(1 → 3)-d-glucans in house dust: A study of low-income homes

Recent work suggests that evaporative coolers increase the level and diversity of bioaerosols, but this association remains understudied in low-income homes. We conducted a cross-sectional study of metropolitan, low-income homes in Utah with evaporative coolers (n = 20) and central air conditioners (n = 28). Dust samples (N = 147) were collected from four locations in each home and analyzed for dust-mite allergens Der p1 and Der f1, endotoxins, and β-(1 → 3)-d-glucans. In all sample locations combined, Der p1 or Der f1 was significantly higher in evaporative cooler versus central air conditioning homes (OR = 2.29, 95% CI = 1.05-4.98). Endotoxin concentration was significantly higher in evaporative cooler versus central air conditioning homes in furniture (geometric mean (GM) = 8.05 vs 2.85 EU/mg, P < .01) and all samples combined (GM = 3.60 vs 1.29 EU/mg, P = .03). β-(1 → 3)-d-glucan concentration and surface loads were significantly higher in evaporative cooler versus central air conditioning homes in all four sample locations and all samples combined (P < .01). Our study suggests that low-income, evaporative cooled homes have higher levels of immunologically important bioaerosols than central air-conditioned homes in dry climates, warranting studies on health implications and other exposed populations.

Reducing Environmental Allergic Triggers: Policy Issues

The implementation of policies to reduce environmental allergic triggers can be an important adjunct to optimal patient care for allergic rhinitis and allergic asthma. Policies at the local level in schools and other public as well as private buildings can make an impact on disease morbidity. Occupational exposures for allergens have not yet been met with the same rigorous policy standards applied for exposures to toxicants by Occupational Safety and Health Administration. Further benefit may be obtained through policies by local, county, state, and national governments, and possibly through international cooperative agreements. The reduction of allergenic exposures can and should be affected by policies with strong scientific, evidence-based derivation. However, a judicious application of the precautionary principle may be needed in circumstances where the health effect of inaction could lead to more serious threats to vulnerable populations with allergic disease. This commentary covers the scientific basis, current implementation, knowledge gaps, and pro/con views on policy issues in reducing environmental allergic triggers.

Managing Younger Siblings of Food Allergic Children

Current guidelines state that there is insufficient evidence to recommend testing siblings of food allergic children before introduction of potential allergic foods, but the topic continues to remain controversial. Although the proportion of siblings who are sensitized to a food without clinical reactivity is high in comparison to those with a true food allergy, there is still a known increased risk amongst siblings of children with food allergies that has led to much apprehension about management. The appropriateness of testing and further steps for management of sensitization in the absence of history of clinical reactivity should be discussed with parents.

Critical roles of regulatory B and T cells in helminth parasite-induced protection against allergic airway inflammation

The prevalence of allergic asthma and incidences of helminth infections in humans are inversely correlated. Although experimental studies have established the causal relation between parasite infection and allergic asthma, the mechanism of the parasite-associated immunomodulation is not fully elucidated. Using a murine model of asthma and nematode parasite Heligmosomoides polygyrus, we investigated the roles of regulatory B cells (B_reg ) and T cells (T_reg ) in mediation of the protection against allergic asthma by parasite. H. polygyrus infection significantly suppressed ovalbumin (OVA)-induced allergic airway inflammation (AAI) evidenced by alleviated lung histopathology and reduced numbers of bronchoalveolar inflammatory cell infiltration, and induced significant responses of interleukin (IL)-10⁺ B_reg , IL-10⁺ T_reg and forkhead box protein 3 (FoxP3)⁺ T_reg in mesenteric lymph node and spleen of the mice. Adoptive transfer of IL-10⁺ B_reg and IL-10⁺ T_reg cell prevented the lung immunopathology in AAI mice. Depletion of FoxP3⁺ T_reg cells in FoxP3-diphtheria toxin (DT) receptor transgenic mice by diphtheria toxin (DT) treatment exacerbated airway inflammation in parasite-free AAI mice and partially abrogated the parasite-induced protection against AAI. IL-10⁺ B_reg cells were able to promote IL-10⁺ T_reg expansion and maintain FoxP3⁺ T_reg cell population. These two types of T_regs failed to induce CD19⁺ B cells to transform into IL-10⁺ B_reg cells. These results demonstrate that B_reg , IL-10⁺ T_reg and FoxP3⁺ T_reg cells contribute in A discrepant manner to the protection against allergic airway immunopathology by parasiteS. B_reg cell might be a key upstream regulatory cell that induces IL-10⁺ T_reg response and supports FoxP3⁺ T_reg cell population which, in turn, mediate the parasite-imposed immunosuppression of allergic airway inflammation. These results provide insight into the immunological relationship between parasite infection and allergic asthma.

Farm-like indoor microbiota in non-farm homes protects children from asthma development

Asthma prevalence has increased in epidemic proportions with urbanization, but growing up on traditional farms offers protection even today¹. The asthma-protective effect of farms appears to be associated with rich home dust microbiota^2,3, which could be used to model a health-promoting indoor microbiome. Here we show by modeling differences in house dust microbiota composition between farm and non-farm homes of Finnish birth cohorts⁴ that in children who grow up in non-farm homes, asthma risk decreases as the similarity of their home bacterial microbiota composition to that of farm homes increases. The protective microbiota had a low abundance of Streptococcaceae relative to outdoor-associated bacterial taxa. The protective effect was independent of richness and total bacterial load and was associated with reduced proinflammatory cytokine responses against bacterial cell wall components ex vivo. We were able to reproduce these findings in a study among rural German children² and showed that children living in German non-farm homes with an indoor microbiota more similar to Finnish farm homes have decreased asthma risk. The indoor dust microbiota composition appears to be a definable, reproducible predictor of asthma risk and a potential modifiable target for asthma prevention.

A review on the pathophysiology of asthma remission

Asthma is a chronic respiratory condition, which is highly prevalent worldwide. Although no cure is currently available, it is well recognized that some asthma patients can spontaneously enter remission of the disease later in life. Asthma remission is characterized by absence of symptoms and lack of asthma-medication use. Subjects in asthma remission can be divided into two groups: those in clinical remission and those in complete remission. In clinical asthma remission, subjects still have a degree of lung functional impairment or bronchial hyperresponsiveness, while in complete asthma remission, these features are no longer present. Over longer periods, the latter group is less likely to relapse. This remission group is of great scientific interest due to the higher potential to find biomarkers or biological pathways that elicit or are associated with asthma remission. Despite the fact that the definition of asthma remission varies between studies, some factors are reproducibly observed to be associated with remitted asthma. Among these are lower levels of inflammatory markers, which are lowest in complete remission. Additionally, in both groups some degree of airway remodeling is present. Still, the pathological disease state of asthma remission has been poorly investigated. Future research should focus on at least two aspects: further characterisation of the small airways and airway walls in order to determine histologically true remission, and more thorough biological pathway analyses to explore triggers that elicit this phenomenon. Ultimately, this will result in pharmacological targets that provide the potential to steer the course of asthma towards remission.

Dendritic Cell-Mediated Th2 Immunity and Immune Disorders

Dendritic cells (DCs) are the professional antigen-presenting cells that recognize and present antigens to naïve T cells to induce antigen-specific adaptive immunity. Among the T-cell subsets, T helper type 2 (Th2) cells produce the humoral immune responses required for protection against helminthic disease by activating B cells. DCs induce a Th2 immune response at a certain immune environment. Basophil, eosinophil, mast cells, and type 2 innate lymphoid cells also induce Th2 immunity. However, in the case of DCs, controversy remains regarding which subsets of DCs induce Th2 immunity, which genes in DCs are directly or indirectly involved in inducing Th2 immunity, and the detailed mechanisms underlying induction, regulation, or maintenance of the DC-mediated Th2 immunity against allergic environments and parasite infection. A recent study has shown that a genetic defect in DCs causes an enhanced Th2 immunity leading to severe atopic dermatitis. We summarize the Th2 immune-inducing DC subsets, the genetic and environmental factors involved in DC-mediated Th2 immunity, and current therapeutic approaches for Th2-mediated immune disorders. This review is to provide an improved understanding of DC-mediated Th2 immunity and Th1/Th2 immune balancing, leading to control over their adverse consequences.

Effect of Early-Life Geohelminth Infections on the Development of Wheezing at 5 Years of Age

RATIONALE

Exposures to geohelminths during gestation or early childhood may reduce risk of wheezing illness/asthma and atopy during childhood in tropical regions.

OBJECTIVES

To investigate the effect of maternal and early childhood geohelminths on development of wheeze/asthma and atopy during the first 5 years of life.

METHODS

A cohort of 2,404 neonates was followed to 5 years of age in a rural district in coastal Ecuador. Data on wheeze were collected by questionnaire and atopy was measured by allergen skin prick test reactivity to 10 allergens at 5 years. Stool samples from mothers and children were examined for geohelminths by microscopy.

MEASUREMENTS AND MAIN RESULTS

A total of 2,090 (86.9%) children were evaluated at 5 years. Geohelminths were observed in 45.5% of mothers and in 34.1% of children by 3 years. Wheeze and asthma were reported for 12.6% and 5.7% of children, respectively, whereas 14.0% had skin test reactivity at 5 years. Maternal geohelminths were associated with an increased risk of wheeze (adjusted odds ratio, 1.41; 95% confidence interval, 1.06-1.88), whereas childhood geohelminths over the first 3 years of life were associated with reduced risk of wheeze (adjusted odds ratio, 0.70; 95% confidence interval, 0.52-0.96) and asthma (adjusted odds ratio, 0.60; 95% confidence interval, 0.38-0.94) but not skin prick test reactivity. The effects on wheeze/asthma were greatest with later age of first infection, were observed only in skin test-negative children, but were not associated with parasite burden or specific geohelminths.

CONCLUSIONS

Although maternal exposures to geohelminths may increase childhood wheeze, childhood geohelminths during the first 3 years may provide protection through a nonallergic mechanism. Registered as an observational study (ISRCTN41239086).

Association between greenhouse working exposure and bronchial asthma: A pilot, cross-sectional survey of 5,420 greenhouse farmers from northeast China

Long-term exposure to greenhouse environments exposes greenhouse workers to inhalation of antigens that can cause respiratory diseases. This study was conducted to investigate the prevalence and potential risk factors for bronchial asthma among the Chinese greenhouse workers based on questionnaire and spirometry data. This was an observational cross-sectional study, performed via stratified-cluster-random sampling. It was conducted in Liaoning Province from the northeast of People's Republic of China, using a population-based sample of 5,880 workers at 835 plastic film greenhouses. All subjects were interviewed using a standardized questionnaire and underwent pulmonary function tests. Multiple logistic regression analysis was conducted to assess associations between self-reported factors of greenhouse worker exposure and bronchial asthma and to identify potential risk factors for this disease. A total of 5,420 questionnaires were completed. The overall prevalence of asthma in greenhouse workers was 19.2% (1040/5420). Multiple logistic regression analysis revealed that the use of multiple pesticides (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.03-1.49), bad odors in the greenhouse (OR = 1.26, 95% CI = 1.07-1.49), and report of the onset of cough when entering the greenhouse (OR = 1.25, 95% CI = 1.09-1.44) were associated with the development of asthma. In contrast, a higher body mass index (BMI >18.5 kg/m^2, OR = 0.93, 95% CI = 0.90-0.95), planting flowers (OR = 0.92, 95% CI = 0.87-0.98), open sidewall to outside (natural ventilation) for at least 30 min per event (OR = 0.82, 95% CI = 0.69-0.96), living in greenhouse (OR = 0.85, 95% CI = 0.73-0.99), and experiencing cough before 14 years old (OR = 0.61, 95% CI = 0.43-0.84) were protective factors to the presentation of asthma among greenhouse workers. Our results suggest that asthma is a major public health problem among Chinese greenhouse workers and more attention should be devoted to preventive measures and management of this disease.

Rhinoviruses in infancy and risk of immunoglobulin E sensitization

Previous data about the role of viruses in the development of allergic immunoglobulin E (IgE) sensitization are contradictory. The aim of this study was to determine the possible associations between exposure to different viruses (rhinovirus, enterovirus, norovirus, and parechovirus) during the first year of life and IgE sensitization. Viruses were analyzed from stool samples collected monthly from infants participating in a prospective birth cohort study. From that study, 244 IgE sensitized case children and 244 nonsensitized control children were identified based on their allergen-specific IgE antibody levels at the age of 6, 18, and 36 months. Stool samples (n = 4576) from the case and control children were screened for the presence of rhinovirus, enterovirus, norovirus, and parechovirus RNA by reverse transcription quantitative polymerase chain reaction. The study showed that rhinovirus was the most prevalent virus detected, present in 921 (20%) samples. None of the viruses were associated with IgE sensitization in the full cohort but after stratifying by sex, the number of rhinovirus positive samples was inversely associated with IgE sensitization in boys (odds ratio [OR]: 0.81; 95% confidence interval [CI]: 0.69-0.94; P = 0.006). There was also a temporal relation between rhinoviruses and IgE sensitization, as rhinovirus exposure during the first 6 months of life was associated with a reduced risk of subsequent IgE sensitization in boys (OR: 0.76; 95% CI: 0.6-0.94; P = 0.016). In conclusion, early exposure to rhinoviruses was inversely associated with IgE sensitization but this protective association was restricted to boys.

[Environmental risk factors for asthma developement]

The prevalence of asthma has increased rapidly since the early 1970s, and only changes in exposure to environmental factors; which go together with changes in lifestyle, are likely to explain such a rapid increase. Exposure to allergens is a risk factor for allergic sensitization, and allergic sensitization is a risk factor for allergic asthma. However, apart from indoor mold exposure as a risk factor for childhood asthma, there is insufficient evidence to conclude that the associations between allergen exposure and asthma development are causal. A new challenge for research is to analyze the huge amount of data derived from the metagenomic characterization of the environmental and human microbiome, to understand the role of interactions between viruses, bacteria and allergens in the development of asthma. It is recognized that prenatal and postnatal exposure to air pollution and maternal smoking increase the risk of developing asthma in children. In adults, the data are scarce and the results remain controversial as regards these exposures and asthma incidence. Further research is needed to appraise the effect of exposure to phenols, phthalates and perfluorinated compounds, which are widespread in the environment and may be associated with asthma, especially in children. Frequent use of chemicals for home cleaning especially in the form of sprays - which is a common practice at the population level - is a risk factor for the development of adult asthma. The domestic use of cleaning products might also be a risk factor for asthma in children exposed at home. The chemicals involved in these relationships are still to be identified. Occupational asthma is a major phenotype of adult asthma. A significant part of these asthma cases might relate to occupational exposure to cleaning products. While there is evidence of associations between diet during pregnancy or during childhood and the risk of developing asthma in children, the data in adults are insufficient. Beyond genetic factors, body composition is influenced by dietary choices and physical activity. Further research is needed to clarify the complex interplay between these nutritional factors and asthma development. The new challenge for research is to decipher the role of all the environmental factors to which the individual is exposed since conception ("exposome") in the development of asthma, using a holistic approach.

Effect of Residential Greenness and Nearby Parks on Respiratory and Allergic Diseases among Middle School Adolescents in a Chinese City

Research on the health impacts of green environments has mainly been conducted in developed countries. Differences in the urban forms between China and Western countries make it essential to understand the role of greenspace in Chinese settings. From 2014 to 2015, middle school students (n = 5643) in Suzhou, China were enrolled in a study on the health effect of residential greenness. The normalized difference vegetation index (NDVI) and distance to the nearest park were calculated for each home address. Logistic regression was performed to test associations between exposure and self-reported doctor diagnoses of asthma, pneumonia, rhinitis, and eczema, adjusting for important confounders. No statistically significant associations were observed for any seasonal NDVI-based measures. However, the proximity of the participants’ residences to the closest park showed an inverse relationship to reported symptoms. The odds ratios for the furthest quartile compared to the closest quartile based on the distance to the nearest park were 0.58 (95% CI: 0.35, 0.99), 0.70 (95% CI: 0.50, 0.96), 0.92 (95% CI: 0.74, 1.15), 0.97 (95% CI: 0.76, 1.24), 0.86 (95% CI: 0.68, 1.10) for current asthma, ever asthma, ever pneumonia, ever rhinitis, and ever eczema, respectively. These findings focused on a single Chinese city and suggest that exposure to natural vegetation in urban areas may affect health through various pathways.

Germ-Free Mice Exhibit Mast Cells With Impaired Functionality and Gut Homing and Do Not Develop Food Allergy

Background: Mucosal mast cells (MC) are key players in IgE-mediated food allergy (FA). The evidence on the interaction between gut microbiota, MC and susceptibility to FA is contradictory.

Objective: We tested the hypothesis that commensal bacteria are essential for MC migration to the gut and their maturation impacting the susceptibility to FA.

Methods: The development and severity of FA symptoms was studied in sensitized germ-free (GF), conventional (CV), and mice mono-colonized with L. plantarum WCFS1 or co-housed with CV mice. MC were phenotypically and functionally characterized.

Results: Systemic sensitization and oral challenge of GF mice with ovalbumin led to increased levels of specific IgE in serum compared to CV mice. Remarkably, despite the high levels of sensitization, GF mice did not develop diarrhea or anaphylactic hypothermia, common symptoms of FA. In the gut, GF mice expressed low levels of the MC tissue-homing markers CXCL1 and CXCL2, and harbored fewer MC which exhibited lower levels of MC protease-1 after challenge. Additionally, MC in GF mice were less mature as confirmed by flow-cytometry and their functionality was impaired as shown by reduced edema formation after injection of degranulation-provoking compound 48/80. Co-housing of GF mice with CV mice fully restored their susceptibility to develop FA. However, this did not occur when mice were mono-colonized with L. plantarum.

Conclusion: Our results demonstrate that microbiota-induced maturation and gut-homing of MC is a critical step for the development of symptoms of experimental FA. This new mechanistic insight into microbiota-MC-FA axis can be exploited in the prevention and treatment of FA in humans.

Environmental exposures and mechanisms in allergy and asthma development

Environmental exposures interplay with human host factors to promote the development and progression of allergic diseases. The worldwide prevalence of allergic disease is rising as a result of complex gene-environment interactions that shape the immune system and host response. Research shows an association between the rise of allergic diseases and increasingly modern Westernized lifestyles, which are characterized by increased urbanization, time spent indoors, and antibiotic usage. These environmental changes result in increased exposure to air and traffic pollution, fungi, infectious agents, tobacco smoke, and other early-life and lifelong risk factors for the development and exacerbation of asthma and allergic diseases. It is increasingly recognized that the timing, load, and route of allergen exposure affect allergic disease phenotypes and development. Still, our ability to prevent allergic diseases is hindered by gaps in understanding of the underlying mechanisms and interaction of environmental, viral, and allergen exposures with immune pathways that impact disease development. This Review highlights epidemiologic and mechanistic evidence linking environmental exposures to the development and exacerbation of allergic airway responses.

Seeing the wood for the trees: A new way to view the human intestinal microbiome and its connection with non-communicable disease

Our paper briefly reviews the connection of the intestinal microbiome to the rise in non-communicable conditions related to atopic disease, obesity and mental health. We consider that the microbiome is best treated as if it were a single entity and have borrowed the terms semiochemical, allomone and kairomone (5) to describe interspecies relationship between the microbiome and ourselves (Fig. 1). We use the term dysbiosis to describe the breakdown of these relationships leading to disease (Fig. 2). As a result of this analysis we tentatively suggest that components of the microbiome assess microbial antigens in our food and pass this information back to our immune system via as yet undescribed chemical messengers: kairomones. We call these hypothetical microbial agents Sentinel Cells. Our suggestion is that atopic disease arises partly as a result of consuming processed food that has insufficient antigens to activate this kairomone feedback mechanism, which atrophies as a result. We note that this is potentially similar to the Old Friends concept of Rook and his co-workers (16). We suggest that obesity is a consequence of dysbiosis-induced waning of the output of allomone-like psychotropic compounds (including the known microbial metabolites dopamine and serotonin) leading to the weakening of the gut-brain axis and a negative effect on mental health. Although dysbiosis can occur in other ways, including antibiotic use and sterile caesarian section, we believe that all these problems can be overcome to provide a future free of these non-communicable diseases.

Update on effects of cleaning agents on allergy and asthma

Background: Cleaning and disinfecting agents are widely used in modern life, in homes, schools, public places, and workplaces as well as in recreational facilities such as swimming pools. Use has been for sanitizing purposes and to assist in reduction of infection as well as for deodorizing purposes. However, adverse respiratory effects have been associated with use of cleaning products ranging from effects in infancy and early childhood up to adults at home and work.

Methods: This review summarizes recent published literature on the effects of cleaning agents used pre-natally, in childhood and adult life, at home, work, and in swimming pools.

Results: Several studies have indicated that there is an increased risk of developing asthma among adults with frequent exposure to cleaning products at work and in the home. Potential mechanisms include sensitization and respiratory irritant effects. Exposure to irritant chlorine by-products from swimming pools have also been associated with respiratory effects and increased risk of asthma. Potential effects from maternal exposures to cleaning products on infants, and effects on early childhood atopy are less clear.

Conclusions: Exposure to cleaning agents increases relative risks of asthma among workers, and adults using these agents in the home. Risks are also increased with exposure to chlorinated by-products from swimming pools, both in adults and children. Further studies are needed to understand the mechanisms of these associations.

Prevalence and treatment of allergies in rural areas of Bavaria, Germany: a cross-sectional study

BACKGROUND

There is a high prevalence of allergies in Germany, with approximately 20% of the population having at least one allergy and only about 10% of these being treated adequately. We conducted a cross-sectional study in a rural area of Bavaria (Southern Germany) to evaluate the prevalence of allergies and their treatment, because research regarding this topic is currently limited.

METHODS

Data were collected in 10 offices of non-dermatological doctors using a self-filled questionnaire to ask participants about allergies and treatment.

RESULTS

A total of 641 questionnaires were appropriate for analysis. The prevalence of allergies in the Bavarian countryside was higher than that reported for Germany (37.3% vs. 20.0%). Furthermore, almost a third (30.4%) of allergies were not treated at all. The most frequently consulted therapist was found to be a general practitioner.

CONCLUSIONS

Based on the study results, there is a need for prevention programs and establishment of treatments for certain allergies to minimize long-term health effects. Moreover, more studies are needed to analyze the prevalence of allergies in farmers who had a higher prevalence of allergies compared to previously reported prevalence in literature reviews.

TRIAL REGISTRATIONS

The study was approved by the ethical review committee of the Technical University Munich (EC number 548/16S).

Perinatal antibiotic exposure alters composition of murine gut microbiota and may influence later responses to peanut antigen

Background

Accumulating evidence suggests that the gut microbiota shapes developmental processes within the immune system. Early life antibiotic use is one factor which may contribute to immune dysfunction and the recent surge in allergies by virtue of its effects on gut microbiota.

Objective and methods

As a first step towards determining whether a relationship exists between perinatal antibiotic induced changes in the gut microbiota and the later development of a peanut allergy, we exposed newborn mice to either the broad-spectrum antibiotic vancomycin or to a vehicle for 6 weeks and then used a novel murine model of peanut allergy.

Results

Early-life treatment with vancomycin resulted in a significant shift in the gut microbiota community characterized by a reduction in the abundance of firmicutes and preponderance of inflammatory proteobacteria. Mice with an antibiotic-altered microbiota, showed a localized allergic-like response characterized by ear swelling and scratching following intra-dermal peanut antigen challenge. Likewise, circulating IgE levels were increased in antibiotic-treated mice, but no evidence of a systemic allergic or anaphylactic-like response was observed. Importantly, we utilized the naturally occurring pro-inflammatory cytokine, tumor necrosis factor-α (TNF-α), rather than the more commonly used cholera toxin, as an adjuvant together with the peanut antigen.

Conclusion

Our data suggest that early antibiotic exposure promotes a shift in the gut microbiota community that may in turn, influence how mice later respond to a TNF-α + antigen challenge. However, further studies verifying the capacity of microbiota restoration to protect against allergic responses will be needed to confirm a causal role of antibiotic-induced microbiota variations in promoting allergic disease phenotypes.

Environmental risk factors for asthma in 13-14 year old African children

Background Asthma prevalence in African children is high. Factors driving the prevalence or disease severity are poorly understood. This study aims to investigate environmental factors associated with asthma and severity in African children. Methods Population based cross-sectional study of children aged 13-14 years from 10 African centers who participated in ISAAC III. Self-reported environmental exposures included engaging in physical exercise, television watching, various biomass and ETS exposure, consumption of paracetamol, large family sizes and having pets in the home. Univariable and multivariable analyses were done adjusting for center variations. Prevalences, odds ratio and 95% confidence intervals (CI) were calculated. Results There were 258 267 children recruited among the 13-14-year-old participants. Of these, 28,391 respondents from 232 schools completed both the written questionnaire (WQ) and environmental questionnaire (EQ). The prevalence of asthma and severe asthma were 12.8% (CI 12.4-13.2), and 8.7% (CI 8.4-8.0) respectively. Factors strongly associated with asthma were maternal smoking (OR = 1.41; 95%CI: 1.23-1.64), open fire heating (OR = 1.28; 95%CI: 1.08-1.51) electric heating (OR = 1.13; 95%CI: 1.01-1.28), physical exercise (OR = 1.29; 95%CI: 1.11-1.50), monthly paracetamol use (OR 1.23; 95%CI 1.13-1.33), having an elder sibling (OR = 0.87; 95%CI 0.77-0.98). Factors associated with severe asthma were maternal smoking (OR = 1.61; 95%CI: 1.38-1.89), cat pet (OR = 1.14; 95%CI: 1.04-1.25), frequent physical exercise (OR = 1.42; 95%CI: 1.23-1.64) and monthly paracetamol use (OR = 1.20; 95%CI 1.07, 1.34). Conclusion Several environmental exposures were associated with asthma and severe disease.

The interplay between risk and preventive factors explains why some children develop allergies to certain foods and others show tolerance

AIM

A number of studies have clarified the tolerance mechanisms and risk factors for food allergies. Our aim was to explore food allergy symptoms by target organs, together with the risk factors and how to prevent food allergies and induce tolerance.

METHODS

We carried out a thorough review of studies on paediatric food allergies published in the last decade.

RESULTS

Food allergy symptoms may affect the skin, nasal and oral mucosa, conjunctivae, gastrointestinal tract or, in severe cases, the respiratory tract and cardiovascular organs. Immunoglobulin E (IgE)-mediated symptoms appear rapidly after exposure to the offending allergen, whereas non-IgE-mediated symptoms are typically delayed. The immunological processes involved in non-IgE-mediated allergic reactions are poorly understood, but T-cell activation is probably involved. There are several factors that influence the food sensitisation process: genetic predisposition, disruption of oral tolerance development, impaired skin barriers in atopic eczema and the influence of microbiomes.

CONCLUSION

The symptoms and intensity of reactions vary considerably with regard to food allergies, and these depend on the individual's concomitant immunological and regulatory mechanisms. There is strong evidence that dietary diversity is important for children, even when they come from families with high allergy risks.

Bedroom Allergen Exposure Beyond House Dust Mites

PURPOSE OF REVIEW

The review provides insight into recent findings on bedroom allergen exposures, primarily focusing on pet, pest, and fungal exposures.

RECENT FINDINGS

Large-scale studies and improved exposure assessment technologies, including measurement of airborne allergens and of multiple allergens simultaneously, have extended our understanding of indoor allergen exposures and their impact on allergic disease. Practical, streamlined methods for exposure reduction have shown promise in some settings, and potential protective effects of early-life exposures have been further elucidated through the investigation of specific bacterial taxa. Advances in molecular allergology have yielded novel data on sensitization profiles and cross-reactivity. The role of indoor allergen exposures in allergic disease is complex and remains incompletely understood. Advancing our knowledge of various co-exposures, including the environmental and host microbiome, that interact with allergens in early life will be crucial for the development of efficacious interventions to reduce the substantial economic and social burden of allergic diseases including asthma.

It's not just the food you eat: Environmental factors in the development of food allergies

The dramatic rise in the prevalence of food allergy and food allergy-associated anaphylaxis in the past few decades has fueled investigative interest into understanding this puzzling trend. Here, we review the question as to whether important external environmental determinants beyond dietary habits and exposure to food allergens are involved. This review will summarize our current understanding of these environment determinants, derived from the latest experimental and epidemiological research. Specifically, we will review the role of exposures that affect skin barrier function, development of a diverse microbiome, and food processing. Additional exposures of concern are insufficient sunlight, endocrine disrupting chemicals and pesticides, and use of specific pharmaceutical agents that may drive or modify the risk for food allergy. Despite limitations in the quantity and quality of research to date, many new epidemiological associations and experimental data in support of this paradigm have emerged.

Clinical Applications of Sublingual Immunotherapy

Sublingual immunotherapy (SLIT) is effective for the treatment of allergic rhinitis and allergic asthma in adults and children. In a limited number of studies, SLIT efficacy has been demonstrated for the treatment of food allergy. SLIT has a higher safety profile versus subcutaneous immunotherapy, although some systemic reactions have been reported. Appropriate patient selection, meticulous patient education, and routine follow-up are key for the safe and effective administration of SLIT. With organization and attention to detail, adding SLIT to one's practice can provide a highly valued patient service.

The Rise and Rise of Eosinophilic Gut Diseases Including Eosinophilic Esophagitis Is Probably Not Explained by the Disappearance of Helicobacter pylori, so Who or What's to Blame?

A dramatic increase in eosinophilic esophagitis (EoE) and atopic disease and a dramatic decline in Helicobacter pylori infection has been observed in the last few decades. Previously, it was speculated that the immune response to H. pylori may protect against allergic diseases including EoE, but this study by Molina-Infante et al. shows no clear relationship, and suggests that any correlation is not causal. In truth it is likely that a combination of many factors, including a changing microbiome with increasing hygiene and alterations in early life such as antibiotic exposure, changing diet and other lifestyle factors drive increasing atopic diseases including food allergies and EoE.

Environmental factors and eosinophilic esophagitis

The incidence and prevalence of eosinophilic esophagitis (EoE) have markedly increased over the past 2 decades, outpacing increased detection of the disease. Although genetic susceptibility markers for EoE have begun to be elucidated, the rate at which EoE has increased in incidence suggests environmental factors predominate. Despite many advances in understanding of the pathogenesis of EoE, the cause of EoE is unknown. This article reviews the emerging data related to environmental risk factors for EoE. Many of these environmental factors are rooted in the theoretical framework of the hygiene hypothesis, specifically mediation of disease development through dysbiosis. Other hypotheses are based on associations that have been observed in studies of non-EoE allergic disease. We describe the evidence that early-life exposures, including antibiotic use, acid suppression, and cesarean delivery, can increase the risk of disease. We also describe the evidence that infectious agents, such as Helicobacter pylori, are inversely associated with disease. Current evidence on geographic risk factors, such as population density, climate zone, and seasonality, is reviewed. We also describe behavioral factors that have been evaluated. Limitations of the existing research are discussed, and recommendations for future areas of research, including assessment of gene-environment interaction, are presented.

Alopecia areata and the gut-the link opens up for novel therapeutic interventions

INTRODUCTION

This review aims to raise the potential of the modern society's impact on gut integrity often leading to increased intestinal permeability, as a cause or driver of Alopecia Areata (AA) in genetically susceptible people. With the increasing rate of T cell-driven autoimmunity, we hypothesize that there is a common root cause of these diseases that originates from chronic inflammation, and that the gut is the most commonly exposed area with our modern lifestyle. Areas covered: We will discuss the complexity in the induction of AA and its potential link to increased intestinal permeability. Our main focus will be on the gut microbiome and mechanisms involved in the interplay with the immune system that may lead to local and/or peripheral inflammation and finally, tissue destruction. Expert opinion: We have seen a link between AA and a dysfunctional gastrointestinal system which raised the hypothesis that an underlying intestinal inflammation drives the priming and dysregulation of immune cells that lead to hair follicle destruction. While it is still important to resolve local inflammation and restore the IP around the hair follicles, we believe that the root cause needs to be eradicated by long-term interventions to extinguish the fire driving the disease.

The Virome and Its Major Component, Anellovirus, a Convoluted System Molding Human Immune Defenses and Possibly Affecting the Development of Asthma and Respiratory Diseases in Childhood

The microbiome, a thriving and complex microbial community colonizing the human body, has a broad impact on human health. Colonization is a continuous process that starts very early in life and occurs thanks to shrewd strategies microbes have evolved to tackle a convoluted array of anatomical, physiological, and functional barriers of the human body. Cumulative evidence shows that viruses are part of the microbiome. This part, called virome, has a dynamic composition that reflects what we eat, how and where we live, what we do, our genetic background, and other unpredictable variables. Thus, the virome plays a chief role in shaping innate and adaptive host immune defenses. Imbalance of normal microbial flora is thought to trigger or exacerbate many acute and chronic disorders. A compelling example can be found in the respiratory apparatus, where early-life viral infections are major determinants for the development of allergic diseases, like asthma, and other non-transmissible diseases. In this review, we focus on the virome and, particularly, on Anelloviridae, a recently discovered virus family. Anelloviruses are major components of the virome, present in most, if not all, human beings, where they are acquired early in life and replicate persistently without causing apparent disease. We will discuss how modulation of innate and adaptive immune systems by Anelloviruses can influence the development of respiratory diseases in childhood and provide evidence for the use of Anelloviruses as useful and practical molecular markers to monitor inflammatory processes and immune system competence.

Finding a needle in a haystack: Bacteroides fragilis polysaccharide A as the archetypical symbiosis factor

Starting from birth, all animals develop a symbiotic relationship with their resident microorganisms that benefits both the microbe and the host. Recent advances in technology have substantially improved our ability to direct research toward the identification of important microbial species that affect host physiology. The identification of specific commensal molecules from these microbes and their mechanisms of action is still in its early stages. Polysaccharide A (PSA) of Bacteroides fragilis is the archetypical example of a commensal molecule that can modulate the host immune system in health and disease. This zwitterionic polysaccharide has a critical impact on the development of the mammalian immune system and also on the stimulation of interleukin 10-producing CD4⁺ T cells; consequently, PSA confers benefits to the host with regard to experimental autoimmune, inflammatory, and infectious diseases. In this review, we summarize the current understanding of the immunomodulatory effects of B. fragilis PSA and discuss these effects as a novel immunological paradigm. In particular, we discuss recent advances in our understanding of the unique functional mechanisms of this molecule and its therapeutic potential, and we review the recent literature in the field of microbiome research aimed at discovering new commensal products and their immunomodulatory potential.

Time to abandon the hygiene hypothesis: new perspectives on allergic disease, the human microbiome, infectious disease prevention and the role of targeted hygiene

Aims:

To review the burden of allergic and infectious diseases and the evidence for a link to microbial exposure, the human microbiome and immune system, and to assess whether we could develop lifestyles which reconnect us with exposures which could reduce the risk of allergic disease while also protecting against infectious disease.

Methods:

Using methodology based on the Delphi technique, six experts in infectious and allergic disease were surveyed to allow for elicitation of group judgement and consensus view on issues pertinent to the aim.

Results:

Key themes emerged where evidence shows that interaction with microbes that inhabit the natural environment and human microbiome plays an essential role in immune regulation. Changes in lifestyle and environmental exposure, rapid urbanisation, altered diet and antibiotic use have had profound effects on the human microbiome, leading to failure of immunotolerance and increased risk of allergic disease. Although evidence supports the concept of immune regulation driven by microbe–host interactions, the term ‘hygiene hypothesis’ is a misleading misnomer. There is no good evidence that hygiene, as the public understands, is responsible for the clinically relevant changes to microbial exposures.

Conclusion:

Evidence suggests a combination of strategies, including natural childbirth, breast feeding, increased social exposure through sport, other outdoor activities, less time spent indoors, diet and appropriate antibiotic use, may help restore the microbiome and perhaps reduce risks of allergic disease. Preventive efforts must focus on early life. The term ‘hygiene hypothesis’ must be abandoned. Promotion of a risk assessment approach (targeted hygiene) provides a framework for maximising protection against pathogen exposure while allowing spread of essential microbes between family members. To build on these findings, we must change public, public health and professional perceptions about the microbiome and about hygiene. We need to restore public understanding of hygiene as a means to prevent infectious disease.

Different functional genes of upper airway microbiome associated with natural course of childhood asthma

BACKGROUND

Microbial colonization of the airway plays a role in the pathogenesis of asthma; however, the effect of the upper airway microbiome on childhood asthma is not fully understood. We analyzed the metagenome of airway microbiome to understand the associated role of upper airway microbiome with the natural course of childhood asthma.

METHODS

Nasopharyngeal swabs were collected from children with asthma, those in asthma remission, and control groups. High-throughput sequencing was used to examine the structure and functional dynamics of the airway microbiome with respect to asthma phenotypes.

RESULTS

The composition of microbiota differed among healthy control, asthma, and remission groups. The relative abundance of Streptococcus was negatively associated with FEV_1% predicted (P = .023) and that of Staphylococcus was negatively associated with methacholine PC₂₀ (P = .013). Genes related to arachidonic acid metabolites, lysine residues, and glycosaminoglycans in the microbiome could be associated with airway inflammation. In particular, genes related to synthesis of anti-inflammatory prostaglandin E₂ (PGE₂ ) were not detected from the airway microbiome in the asthma group.

CONCLUSIONS

These data suggest that alterations in the composition and function of the upper airway microbiome could be related with the natural course of asthma in children.

Respiratory Viruses and Asthma

Asthma remains the most prevalent chronic respiratory disorder, affecting people of all ages. The relationship between respiratory virus infection and asthma has long been recognized, though remains incompletely understood. In this article, we will address key issues around this relationship. These will include the crucial role virus infection plays in early life, as a potential risk factor for the development of asthma and lung disease. We will assess the impact that virus infection has on those with established asthma as a trigger for acute disease and how this may influence asthma throughout life. Finally, we will explore the complex interaction that occurs between the airway and the immune responses that make those with asthma so susceptible to the effects of virus infection.

Immunological Tolerance, Pregnancy, and Preeclampsia: The Roles of Semen Microbes and the Father

Although it is widely considered, in many cases, to involve two separable stages (poor placentation followed by oxidative stress/inflammation), the precise originating causes of preeclampsia (PE) remain elusive. We have previously brought together some of the considerable evidence that a (dormant) microbial component is commonly a significant part of its etiology. However, apart from recognizing, consistent with this view, that the many inflammatory markers of PE are also increased in infection, we had little to say about immunity, whether innate or adaptive. In addition, we focused on the gut, oral and female urinary tract microbiomes as the main sources of the infection. We here marshall further evidence for an infectious component in PE, focusing on the immunological tolerance characteristic of pregnancy, and the well-established fact that increased exposure to the father's semen assists this immunological tolerance. As well as these benefits, however, semen is not sterile, microbial tolerance mechanisms may exist, and we also review the evidence that semen may be responsible for inoculating the developing conceptus (and maybe the placenta) with microbes, not all of which are benign. It is suggested that when they are not, this may be a significant cause of PE. A variety of epidemiological and other evidence is entirely consistent with this, not least correlations between semen infection, infertility and PE. Our view also leads to a series of other, testable predictions. Overall, we argue for a significant paternal role in the development of PE through microbial infection of the mother via insemination.

Effects of Antibiotics on the Development of Asthma and Other Allergic Diseases in Children and Adolescents

Purpose

Our aim was to explore whether antibiotic exposure in children and adolescents is associated with the later development of allergic diseases, using nationwide population-based claims data.

Methods

We collected information from the National Health Insurance Service (2006–2015) database. A total of 5,626,328 children and adolescents were eligible for the study. We explored whether exposure to antibiotics over the prior 7 years affects the later development of allergic diseases. We ran 3 analytical models after adjusting for confounding factors including age, sex, the number of visits to healthcare providers, income, and the place of residence (urban/rural).

Results

Allergic diseases were most common in male children and those aged < 10 years (atopic dermatitis, asthma and allergic rhinitis; all P < 0.01). Also, urban residents with higher incomes were more likely to develop allergic diseases (all P < 0.01). The annual number of days on which antibiotics were prescribed differed significantly between subjects with each allergic disease studied and a comparison group (all P < 0.01). Multiple logistic regression showed that as the duration of antibiotic exposure increased, the incidences of atopic dermatitis, asthma, and allergic rhinitis trended upward, even after adjusting for confounding factors (P for trend < 0.01).

Conclusions

Antibiotic use early in life is associated with an increased risk of allergic disease, especially in young children; the risk increases as the duration of antibiotic therapy rises. Moreover, urban residence was more strongly associated with a longer duration of antibiotic use than was rural residence.

Differential effects of air conditioning type on residential endotoxin levels in a semi-arid climate

Residential endotoxin exposure is associated with protective and pathogenic health outcomes. Evaporative coolers, an energy-efficient type of air conditioner used in dry climates, are a potential source of indoor endotoxins; however, this association is largely unstudied. We collected settled dust biannually from four locations in homes with evaporative coolers (n=18) and central air conditioners (n=22) in Utah County, Utah (USA), during winter (Jan-Apr) and summer (Aug-Sept), 2014. Dust samples (n=281) were analyzed by the Limulus amebocyte lysate test. Housing factors were measured by survey, and indoor temperature and relative humidity measures were collected during both seasons. Endotoxin concentrations (EU/mg) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons. Endotoxin surface loads (EU/m² ) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons and in upholstered furniture during winter. For the nine significant season-by-location comparisons, EU/mg and EU/m² were approximately three to six times greater in homes using evaporative coolers. A plausible explanation for these findings is that evaporative coolers serve as a reservoir and distribution system for Gram-negative bacteria or their cell wall components in homes.

Correlation between early-life regulation of the immune system by microbiota and allergy development

Early postnatal life is a key time for development of the immune system and colonization of the host by microbiota. Recent studies have shown that specific limbs of the immune system can be regulated by microbiota in a time-restricted period during early life. Studies in mouse models have shown that perturbations of the microbiota during early life can cause immune effects that can persist into adulthood and create increased host susceptibility to certain diseases. Here we discuss the role of early-life regulation of the immune system by the microbiota and how it can be related to allergy development.

When is allergen immunotherapy effective?

Allergen immunotherapy is used to treat allergic symptoms such as rhinitis and itchy eyes in Japanese patients with cedar pollen allergy (JCPA). Administration of small amounts of pollen over several years may suppress severe allergic symptoms when these patients are later exposed to large amounts of pollen in the environment. Herein, we developed a simple mathematical model to identify conditions in which allergen immunotherapy is effective. We considered the dynamics of type 2 T helper cells (Th2) and regulatory T cells (Treg), both of which differentiate from naive T cells. Therapy was considered successful under the following three conditions: (1) Without therapy patients develop allergic symptoms upon exposure to environmental pollen, (2) with therapy patients do not develop symptoms upon exposure, and (3) patients do not develop allergic symptoms to the therapy itself. We defined scores for therapeutic success and identified ranges of parameters in which allergen immunotherapy is likely to be successful. Treg cells have a longer lifespan than Th2 cells, allowing accumulation over many years. In accordance, therapy with linear dose increases (rather than constant doses) reduced the risk of allergies to the therapy itself, and led to stronger accumulation of resistance to pollen exposure.

Advances in asthma 2015: Across the lifespan

In 2015, progress in understanding asthma ranged from insights to asthma inception, exacerbations, and severity to advancements that will improve disease management throughout the lifespan. 2015's insights to asthma inception included how the intestinal microbiome affects asthma expression with the identification of specific gastrointestinal bacterial taxa in early infancy associated with less asthma risk, possibly by promoting regulatory immune development at a critical early age. The relevance of epigenetic mechanisms in regulating asthma-related gene expression was strengthened. Predicting and preventing exacerbations throughout life might help to reduce progressive lung function decrease and disease severity in adulthood. Although allergy has long been linked to asthma exacerbations, a mechanism through which IgE impairs rhinovirus immunity and underlies asthma exacerbations was demonstrated and improved by anti-IgE therapy (omalizumab). Other key molecular pathways underlying asthma exacerbations, such as cadherin-related family member 3 (CDHR3) and orosomucoid like 3 (ORMDL3), were elucidated. New anti-IL-5 therapeutics, mepolizumab and reslizumab, were US Food and Drug Administration approved for the treatment of patients with severe eosinophilic asthma. In a clinical trial the novel therapeutic inhaled GATA3 mRNA-specific DNAzyme attenuated early- and late-phase allergic responses to inhaled allergen. These current findings are significant steps toward addressing unmet needs in asthma prevention, severity modification, disparities, and lifespan outcomes.

Household pet exposure, allergic sensitization, and rhinitis in the U.S. population

BACKGROUND

The effect of animal dander exposure on allergic sensitization may be age-dependent. A comparison between the association of the levels of exposure to pet allergen with rhinitis symptoms and allergic sensitization in children and adults is yet to be performed in the U.S.

POPULATION

METHODS

Cross-sectional study of 3034 adults (age, 20 to 85 years) and 2104 children (age, 6 to 19 years) in the National Health and Nutrition Examination Survey, 2005-2006. Samples of household dust were collected to measure the amounts of indoor allergens in the participants' homes. Self-reported rhinitis was based on symptoms during the past 12 months, and allergen sensitization was defined as a positive response to any of the 19 specific immunoglobulin E (IgE) antigens tested.

RESULTS

Higher levels of exposure to dog dander were associated with a higher prevalence of any allergic sensitization in adults (prevalence ratio [PR] 1.19; 95% confidence interval [CI], 1.01 to 1.39), but a lower prevalence in children (PR 0.84; 95% CI, 0.73 to 0.096), p-interaction by age group 0.02. Cat exposure was associated with an increased prevalence of rhinitis symptoms in adults (PR for the 3rd vs lowest tertile of cat dander concentrations: 1.14; 95% CI, 1.05 to 1.23) but not in children (PR for the 3rd vs lowest tertile of cat dander IgE concentrations: 0.86; 95% CI, 0.70 to 1.07), p-interaction 0.01.

CONCLUSION

Allergic sensitization and symptomatic response to pet dander exposure may vary based on age. Further studies are necessary to assess the mechanisms for these apparent differences.

Meat Intake and the Dose of Vitamin B3 - Nicotinamide: Cause of the Causes of Disease Transitions, Health Divides, and Health Futures?

Meat and vitamin B3 - nicotinamide - intake was high during hunter-gatherer times. Intake then fell and variances increased during and after the Neolithic agricultural revolution. Health, height, and IQ deteriorated. Low dietary doses are buffered by 'welcoming' gut symbionts and tuberculosis that can supply nicotinamide, but this co-evolved homeostatic metagenomic strategy risks dysbioses and impaired resistance to pathogens. Vitamin B3 deficiency may now be common among the poor billions on a low-meat diet. Disease transitions to non-communicable inflammatory disorders (but longer lives) may be driven by positive 'meat transitions'. High doses of nicotinamide lead to reduced regulatory T cells and immune intolerance. Loss of no longer needed symbiotic 'old friends' compounds immunological over-reactivity to cause allergic and auto-immune diseases. Inhibition of nicotinamide adenine dinucleotide consumers and loss of methyl groups or production of toxins may cause cancers, metabolic toxicity, or neurodegeneration. An optimal dosage of vitamin B3 could lead to better health, but such a preventive approach needs more equitable meat distribution. Some people may require personalised doses depending on genetic make-up or, temporarily, when under stress.

The role of dietary interventions in the prevention of IgE-mediated food allergy in children

Over the last 30 years, the prevalence of food allergy has been on the rise and remains a disease that can have a significant impact on the quality of life of children and their families. There are several hypotheses that have been suggested to account for the increasing prevalence, but this review will focus on the impact that dietary factors have on food allergy development. In the past food allergy, prevalence has largely focused on allergen avoidance; however, there is increasing evidence from interventional studies that have shown that early introduction to potential food allergens may have a beneficial role in allergy prevention. This review aims to look at the evidence in support of early introduction of allergens into infant diets to prevent against the development of food allergy.

How French general practitioners manage and prevent recurrent respiratory tract infections in children: the SOURIRRE survey

BACKGROUND

Recurrent respiratory tract infections (RRTIs) are the most common reason for children's visits to primary care physicians in France; however, little is known about general practitioners' (GPs) opinions and expectations concerning the management and prevention of these common and recurrent pathologies.

PURPOSE

To describe French GPs' daily practice in the management of respiratory infections and the prevention of their recurrence in children.

METHODS

A sample group of French GPs answered a structured questionnaire on risk factors, RRTI management, antibiotic use and prevention measures.

RESULTS

A total of 358 GPs participated in the survey. Rhinopharyngitis, the most frequent respiratory infection, was considered to be recurrent if six or more episodes occurred in a year. Four risk factors were acknowledged as substantial: living in communities, passive smoking, pollution and allergies. Around 63% of GPs said that RRTIs are too often treated with antibiotics. More than 85% thought that prevention of RRTIs is possible. Smoking cessation, vaccination, allergen avoidance and hygiene were identified as the main preventive measures. A large majority of GPs (84%) prescribed products for prevention and ~90% would prescribe a product stimulating immunity if the efficacy and tolerability of these agents was proven and confirmed in their daily practice.

CONCLUSIONS

French GPs are well aware of the health and socioeconomic burdens resulting from RRTIs, as well as the risk of antibiotic overuse. They have a prevention-oriented approach, implement preventive measures when possible and prescribe products for prevention.

The gut microbiome and microbial translocation in multiple sclerosis

Individuals with multiple sclerosis (MS) have a distinct intestinal microbial community (microbiota) and increased low-grade translocation of bacteria from the intestines into the circulation. The observed change of intestinal bacteria in MS patients regulate immune functions involved in MS pathogenesis. These functions include: systemic and central nervous system (CNS) immunity (including peripheral regulatory T cell function), the blood-brain barrier (BBB) permeability and CNS-resident cell activity. This review discusses the MS intestinal microbiota implication on MS systemic- and CNS-immunopathology. We introduce the possible contributions of MS low-grade microbial translocation (LG-MT) to the development of MS, and end on a discussion on microbiota therapies for MS patients.

Bifidobacterium mixture (B longum BB536, B infantis M-63, B breve M-16V) treatment in children with seasonal allergic rhinitis and intermittent asthma

BACKGROUND

Allergic rhinitis (AR) and allergic asthma are caused by an IgE-mediated inflammatory reaction. Probiotics may exert anti-inflammatory and immune-modulatory activity. Thus, this study aimed at investigating whether a Bifidobacteria mixture could be able to relieve nasal symptoms, and affect quality of life (QoL) in children with AR and intermittent asthma due to Parietaria allergy.

MATERIALS AND METHODS

The present study was conducted as placebo-controlled, double-blinded, and randomized. Globally, 40 children (18 males; mean age 9 ± 2.2 years) were enrolled. They were treated with probiotics or placebo: 1 sachet/day for 4 weeks. AR symptoms, and QoL were assessed at baseline and after treatment. Use of rescue medications, such as cetirizine syrup and salbutamol spray, was also permitted and recorded.

RESULTS

Children treated with probiotic mixture achieved a significant improvement of symptoms (p < 0.005), and QoL ((p < 0.001). Placebo group had worsening of symptoms (p < 0.005) and QoL (p < 0.001). The use of rescue medications was overlapping in the two groups. The intergroup analysis showed that probiotic mixture was significantly superior than placebo for all parameters.

CONCLUSIONS

The current study demonstrated that a Bifidobacteria mixture was able of significantly improving AR symptoms and QoL in children with pollen-induced AR and intermittent asthma.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov ID NCT02807064 .

The role of indoleamine 2,3-dioxygenase-aryl hydrocarbon receptor pathway in the TLR4-induced tolerogenic phenotype in human DCs

A controlled inflammatory response is required for protection against infection, but persistent inflammation causes tissue damage. Dendritic cells (DCs) have a unique capacity to promote both inflammatory and anti-inflammatory processes. One key mechanism involved in DC-mediated immunosuppression is the expression of tryptophan-metabolizing enzyme indoleamine 2,3-dioxygenase (IDO). IDO has been implicated in diverse processes in health and disease but its role in endotoxin tolerance in human DCs is still controversial. Here we investigated the role of IDO in shaping DCs phenotype and function under endotoxin tolerance conditions. Our data show that TLR4 ligation in LPS-primed DCs, induced higher levels of both IDO isoforms together with the transcription factor aryl-hydrocarbon receptor (AhR), compared to unprimed controls. Additionally, LPS conditioning induced an anti-inflammatory phenotype in DCs - with an increase in IL-10 and higher expression of programmed death ligand (PD-L)1 and PD-L2 - which were partially dependent on IDO. Furthermore, we demonstrated that the AhR-IDO pathway was responsible for the preferential activation of non-canonical NF-κB pathway in LPS-conditioned DCs. These data provide new insight into the mechanisms of the TLR4-induced tolerogenic phenotype in human DCs, which can help the better understanding of processes involved in induction and resolution of chronic inflammation and tolerance.

Prenatal Maternal Distress and Allergic Diseases in Offspring: Review of Evidence and Possible Pathways

Recent studies have suggested a close association between prenatal maternal distress and allergic diseases in the offspring. We selected relevant birth-cohort or national registry studies using a keyword search of the PubMed database and summarized current evidence on the impact of prenatal maternal distress on the development of offspring's allergic diseases. Moreover, we postulated possible pathways linking prenatal distress and allergic diseases based on relevant human and animal studies. Both dysregulated hypothalamic-pituitary-adrenal axis and increased oxidative stress may cause structural (altered brain/lung development) and functional (skewed immune development) changes, which may predispose the fetus to developing allergic diseases during childhood. Although many facts are yet to be discovered, changes in the placental response and epigenetic modification are presumed to mediate the whole process from maternal distress to allergic diseases. Maternal prenatal distress can also interact with other physical or environmental factors, including familial or physical factors, indoor and outdoor pollutants, and early childhood psychological distress. The gut-microbiome-brain axis and the role of the microbiome as an immune modulator should be considered when investigating the stress-allergy relationship and exploring potential intervention modalities. Further research is needed, and particular attention should be given to defining the most vulnerable subjects and critical time periods. To this end, studies exploring relevant biomarkers are warranted, which can enable us to explore adequate intervention strategies.

Extensively hydrolyzed casein formula containing Lactobacillus rhamnosus GG reduces the occurrence of other allergic manifestations in children with cow's milk allergy: 3-year randomized controlled trial

BACKGROUND

Children with cow's milk allergy (CMA) have an increased risk of other allergic manifestations (AMs).

OBJECTIVE

We performed a parallel-arm randomized controlled trial to test whether administration of an extensively hydrolyzed casein formula (EHCF) containing the probiotic Lactobacillus rhamnosus GG (LGG) can reduce the occurrence of other AMs in children with CMA.

METHODS

Children with IgE-mediated CMA were randomly allocated to the EHCF or EHCF+LGG groups and followed for 36 months. The main outcome was occurrence of at least 1 AM (eczema, urticaria, asthma, and rhinoconjunctivitis). The secondary outcome was tolerance acquisition, which was defined as the negativization of a double-blind food challenge results at 12, 24, and 36 months. AMs were diagnosed according to standardized criteria. Tolerance acquisition was evaluated every 12 months.

RESULTS

A total of 220 children (147 boys [67%]) with a median age of 5.0 months (interquartile range, 3.0-8.0 months) were randomized; 110 children were placed in the EHCF group, and 110 children were placed in the EHCF+LGG group. In the complete case analysis the absolute risk difference for the occurrence of at least 1 AM over 36 months was -0.23 (95% CI, -0.36 to -0.10; P < .001), and the absolute risk difference for the acquisition of cow's milk tolerance was 0.20 (95% CI, 0.05-0.35; P < .01) at 12 months, 0.24 (95% CI, 0.08-0.41; P < .01) at 24 months, and 0.27 (95% CI, 0.11-0.43; P < .001) at 36 months. In the sensitivity analysis the effect size of the main outcome was virtually unchanged when the occurrence of AMs was assigned to all 27 missing children.

CONCLUSIONS

EHCF+LGG reduces the incidence of other AMs and hastens the development of oral tolerance in children with IgE-mediated CMA.