An Overview of Environmental Risk Factors for Food Allergy

Baked Egg Oral Immunotherapy: Current State in Pediatric Age

Hen's egg allergy is one of the most common food allergies in the Western world, with an increase in recent years. It affects about 9.5% of the pediatric population, and the onset most often occurs before the first year of life. The occurrence of spontaneous oral tolerance acquisition varies among studies, but it is generally high by school age. Nowadays, allergen immunotherapy may represent the only therapeutic strategy able to modify the natural history of hen's egg allergy. Specifically, many children with hen's egg allergy may tolerate baked eggs. Food processing, specifically high temperatures, alters the allergenicity of hen's egg proteins by causing conformational changes in allergen epitopes, which makes them less allergenic. This review aims to discuss the scientific evidence in the field of baked egg oral immunotherapy in hen's egg-allergic children, with a meticulous examination of the pertinent literature surrounding the subject matter.

The potential of orally exposed risk factors and constituents aggravating food allergy: Possible mechanism and target cells

Food allergy is a significant concern for the health of humans worldwide. In addition to dietary exposure of food allergens, genetic and environmental factors also play an important role in the development of food allergy. However, only the tip of the iceberg of risk factors in food allergy has been identified. The importance of food allergy caused by orally exposed risk factors and constituents, including veterinary drugs, pesticides, processed foods/derivatives, nanoparticles, microplastics, pathogens, toxins, food additives, dietary intake of salt/sugar/total fat, vitamin D, and therapeutic drugs, are highlighted and discussed in this review. Moreover, the epithelial barrier hypothesis, which is closely associated with the occurrence of food allergy, is also introduced. Additionally, several orally exposed risk factors and constituents that have been reported to disrupt the epithelial barrier are elucidated. Finally, the possible mechanisms and key immune cells of orally exposed risk factors and constituents in aggravating food allergy are overviewed. Further work should be conducted to define the specific mechanism by which these risk factors and constituents are driving food allergy, which will be of central importance to the targeted therapy of food allergy.

Children's food allergy: Effects of environmental influences and antibiotic use across critical developmental windows

BACKGROUND

Increasing studies linked outdoor air pollution (OAP), indoor environmental factors (IEFs), and antibiotics use (AU) with the first wave of allergies (i.e., asthma, allergic rhinitis, and eczema), yet the role of their exposures on children's second wave of allergy (i.e., food allergy) are unknown.

OBJECTIVES

To investigate the association between exposure to OAP and IEFs and childhood doctor-diagnosed food allergy (DFA) during the pre-pregnancy, prenatal, early postnatal, and current periods, and to further explore the effect of OAP and IEFs on DFA in children co-exposed to antibiotics.

METHODS

A retrospective cohort study involving 8689 preschoolers was carried out in Changsha, China. Data on the health outcomes, antibiotic use, and home environment of each child were collected through a questionnaire. Temperature and air pollutants data were obtained from 8 and 10 monitoring stations in Changsha, respectively. Exposure levels to temperature and air pollutants at individual home addresses were calculated by the inverse distance weighted (IDW) method. Multiple logistic regression models were employed to assess the associations of childhood DFA with exposure to OAP, IEF, and AU.

RESULTS

Childhood ever doctor-diagnosed food allergy (DFA) was linked to postnatal PM10 exposure with OR (95% CI) of 1.18 (1.03-1.36), especially for CO and O3 exposure during the first year with ORs (95% CI) = 1.08 (1.00-1.16) and 1.07 (1.00-1.14), as well as SO2 exposure during the previous year with OR (95% CI) of 1.13 (1.02-1.25). The role of postnatal air pollution is more important for the risk of egg, milk and other food allergies. Renovation-related IAP (new furniture) and dampness-related indoor allergens exposures throughout all time windows significantly increased the risk of childhood DFA, with ORs ranging from 1.23 (1.03-1.46) to 1.54 (1.29-1.83). Furthermore, smoke-related IAP (environmental tobacco smoke [ETS], parental and grandparental smoking) exposure during pregnancy, first year, and previous year was related to DFA. Additionally, exposure to pet-related indoor allergens (cats) during first year and total plant-related allergens (particularly nonflowering plants) during previous year were associated with DFA. Moreover, exposure to plant-related allergy during first and previous year was specifically associated with milk allergy, while keeping cats during first year increased the risk of fruits/vegetables allergy. Life-time and early-life AU was associated with the increased risk of childhood DFA with ORs (95% CI) = 1.57 (1.32-1.87) and 1.46 (1.27-1.67), including different types food allergies except fruit/vegetable allergy.

CONCLUSIONS

Postnatal OAP, life-time and early-life IEFs and AU exposure played a vital role in the development of DFA, supporting the "fetal origin of childhood FA" hypothesis.

Interactions between toll-like receptors signaling pathway and gut microbiota in host homeostasis

BACKGROUND

Toll-like receptors (TLRs) are a family of fundamental pattern recognition receptors in the innate immune system, constituting the first line of defense against endogenous and exogenous antigens. The gut microbiota, a collection of commensal microorganisms in the intestine, is a major source of exogenous antigens. The components and metabolites of the gut microbiota interact with specific TLRs to contribute to whole-body immune and metabolic homeostasis.

OBJECTIVE

This review aims to summarize the interaction between the gut microbiota and TLR signaling pathways and to enumerate the role of microbiota dysbiosis-induced TLR signaling pathways in obesity, inflammatory bowel disease (IBD), and colorectal cancer (CRC).

RESULTS

Through the recognition of TLRs, the microbiota facilitates the development of both the innate and adaptive immune systems, while the immune system monitors dynamic changes in the commensal bacteria to maintain the balance of the host-microorganism symbiosis. Dysbiosis of the gut microbiota can induce a cascade of inflammatory and metabolic responses mediated by TLR signaling pathways, potentially resulting in various metabolic and inflammatory diseases.

CONCLUSION

Understanding the crosstalk between TLRs and the gut microbiota contributes to potential therapeutic applications in related diseases, offering new avenues for treatment strategies in conditions like obesity, IBD, and CRC.

HLA variants and their association with IgE-Mediated banana allergy: A cross-sectional study

Background

Banana allergy is on the rise in tropical regions. Advances in genomics and candidate gene identification have increased interest in genetic factors in food allergies. However, the genetic basis of IgE-mediated banana allergy is underexplored.

Objective

To characterize HLA variants and their association with IgE-mediated banana allergy.

Methods

This cross-sectional study recruited banana-allergic adults, confirmed by allergology tests, with non-allergic individuals as controls. Genomic DNA extraction and sequencing BAM files for HLA typing were conducted. Allele frequency was calculated using the direct counting method, and odds ratio (OR) with 95 % confidence interval (CI) were determined. Fisher's exact or chi-square tests were used to assess associations with Bonferroni's correction for multiple tests. The allele frequency of the Thai population from The Allele Frequency Net Database was used to compute the allele enrichment ratio (ER).

Results

A total of 59 cases and 64 controls were recruited. HLA genotyping indicated potential associations of HLA-B*15:25 (OR 11.872; p-value 0.027), HLA-C*04:03 (OR 7.636; p-value 0.033), and HLA-DQB1*06:09 (OR 11.558; p-value 0.039) with banana allergy. However, after Bonferroni correction, none of these associations reached statistical significance. Comparing allele frequency with the general population from The Allele Frequency Net Database, our ER analysis revealed a higher prevalence in the banana allergy group for B*15:25 (ER 1.849), C*04:03 (ER 1.332), and DQB1*06:09 (ER 6.602) alleles.

Conclusions

This study provides initial genetic insights into banana allergy, suggesting potential links with specific HLA alleles. Despite 12 initially identifying alleles, none were statistically significant after multiple testing correction. Larger studies are needed to detect possible significant correlations.

Understanding the burden of food allergy among urban and rural school children from north India

Background

There is paucity of reliable epidemiological data regarding the burden of food allergy in most developing countries, including India.

Objective

To provide current estimates of the prevalence and distribution of food allergy among urban and rural school children aged 6-14 years in Delhi and the National Capital Region (NCR) of Khekra in India.

Methods

A cross-sectional study was conducted from January 2022 to February 2023 to enroll school children, 6-14 years, from select urban and rural schools in Delhi and NCR. A questionnaire consisting of questions focused on household environment, early life factors, and pediatric food allergy characteristics was administered by a trained medical researcher to collect parent-proxy data. Univariate statistics were used to describe frequencies, percentages, and 95% confidence intervals for survey items.

Results

The estimated prevalence of parent-reported food allergy was 0.8% (95% CI: 0.4-1.5; urban: 0.4%, 95% CI: 0.1-1.1; rural: 1.7%, 95% CI: 0.7-3.5). Fruits such as mango (0.3%, 95% CI: 0.1-0.9), strawberry (0.1%, 95% CI: 0.0-0.7), orange (0.1%, 95% CI: 0.0-0.7), and custard apple (0.1%, 95% CI: 0.0-0.7) were reported only by urban children, while rural children reported yogurt (0.6%, 95% CI: 0.1-1.8) and wheat (0.3%, 95% CI: 0.0-1.3). Both groups reported brinjal (also known as eggplant) and banana, 0.1% (95% CI: 0.0-0.7) of urban and 0.3% (95% CI: 0.0-1.3) of rural, respectively. Overall, commonly reported clinical symptoms were diarrhea and/or vomiting (100%, 95% CI: 76.2-100), abdominal pain (88.9%, 95% CI: 58.6-98.8), and rash/itchy skin (66.7%, 95% CI: 34.8-89.6). Among children with parent reported food allergy, 66.7% (95% CI: 34.8-89.6) of food allergies were physician diagnosed, of which 33.3% were diagnosed via history alone (95% CI:7.7-71.4) while 66.7% (95% CI: 28.6-92.3) were confirmed via skin prick test and/or blood test.

Conclusion

The overall prevalence of food allergy is very low in Delhi and Khekra, India. Future work should focus on elucidating the complex interplay of early-life, environmental, genetic, and lifestyle factors to understand the reasons for India's low food allergy burden and improve epidemiological clues to prevention for the nations with higher disease burden.

Examining allergy related diseases in Africa: A scoping review protocol

During recent decades, allergy related diseases have emerged as a growing area of concern in developing regions of the world, including Africa. Worldwide prevalence of allergic diseases has grown to an estimated 262 million for asthma, 400 million for allergic rhinitis (or hay fever), 171 million with atopic dermatitis (or eczema), and over 200 million for food allergy. In Africa, considerable variability exists in the data surrounding prevalence at the continent-wide, regional, and study site levels. Furthermore, research conducted in many rural areas and underdeveloped countries in Africa remains limited, and presently, little has been done to characterize and map the extremely heterogeneous body of literature which confounds research efforts. This scoping review will seek to identify studies examining the prevalence, management strategies, outcomes, and associated risk factors for allergy related diseases in Africa. The Joanna Briggs Institute's scoping review methods will be followed, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Review (PRISMA-ScR) was used for writing the protocol. Four databases (Embase, Global Health, PubMed, African Journals Online) will be searched for literature published from 2003 to 2023 in any language. Title and abstract screening and full-text screening will be completed by two independent reviewers using Covidence; conflicts resolved by a third reviewer. Data will be extracted using Covidence by two reviewers independently. To report the results, we will follow the PRISMA-ScR checklist and report descriptive statistics and a narrative summary.

Climate Change and Food Allergy

The role of environmental factors including climate change and consequent influences of air pollution on food allergy remains less explored compared with impacts on allergic rhinitis and asthma. In this review, we discuss the epithelial barrier hypothesis as a proposed mechanism of food allergy development that may be relevant in this context. We also discuss existing studies that provide insight into the intricate relationship between food allergy and climate-related environmental factors.

Different airborne particulates trigger distinct immune pathways leading to peanut allergy in a mouse model

BACKGROUND

Environmental exposure to peanut through non-oral routes is a risk factor for peanut allergy. Early-life exposure to air pollutants, including particulate matter (PM), is associated with sensitization to foods through unknown mechanisms. We investigated whether PM promotes sensitization to environmental peanut and the development of peanut allergy in a mouse model.

METHODS

C57BL/6J mice were co-exposed to peanut and either urban particulate matter (UPM) or diesel exhaust particles (DEP) via the airways and assessed for peanut sensitization and development of anaphylaxis following peanut challenge. Peanut-specific CD4+ T helper (Th) cell responses were characterized by flow cytometry and Th cytokine production. Mice lacking select innate immune signaling genes were used to study mechanisms of PM-induced peanut allergy.

RESULTS

Airway co-exposure to peanut and either UPM- or DEP-induced systemic sensitization to peanut and anaphylaxis following peanut challenge. Exposure to UPM or DEP triggered activation and migration of lung dendritic cells to draining lymph nodes and induction of peanut-specific CD4+ Th cells. UPM- and DEP-induced distinct Th responses, but both stimulated expansion of T follicular helper (Tfh) cells essential for peanut allergy development. MyD88 signaling was critical for UPM- and DEP-induced peanut allergy, whereas TLR4 signaling was dispensable. DEP-induced peanut allergy and Tfh-cell differentiation depended on IL-1 but not IL-33 signaling, whereas neither cytokine alone was necessary for UPM-mediated sensitization.

CONCLUSION

Environmental co-exposure to peanut and PM induces peanut-specific Tfh cells and peanut allergy in mice.

Directed acyclic graph for epidemiological studies in childhood food allergy: Construction, user's guide, and application

Understanding modifiable prenatal and early life causal determinants of food allergy is important for the prevention of the disease. Randomized clinical trials studying environmental and dietary determinants of food allergy may not always be feasible. Identifying risk/protective factors for early-life food allergy often relies on observational studies, which may be affected by confounding bias. The directed acyclic graph (DAG) is a causal diagram useful to guide causal inference from observational epidemiological research. To date, research on food allergy has made little use of this promising method. We performed a literature review of existing evidence with a systematic search, synthesized 32 known risk/protective factors, and constructed a comprehensive DAG for early-life food allergy development. We present an easy-to-use online tool for researchers to re-construct, amend, and modify the DAG along with a user's guide to minimize confounding bias. We estimated that adjustment strategies in 57% of previous observational studies on modifiable factors of childhood food allergy could be improved if the researchers determined their adjustment sets by DAG. Future researchers who are interested in the causal inference of food allergy development in early life can apply the DAG to identify covariates that should and should not be controlled in observational studies.

The epithelial barrier: The gateway to allergic, autoimmune, and metabolic diseases and chronic neuropsychiatric conditions

Since the 1960 s, our health has been compromised by exposure to over 350,000 newly introduced toxic substances, contributing to the current pandemic in allergic, autoimmune and metabolic diseases. The "Epithelial Barrier Theory" postulates that these diseases are exacerbated by persistent periepithelial inflammation (epithelitis) triggered by exposure to a wide range of epithelial barrier-damaging substances as well as genetic susceptibility. The epithelial barrier serves as the body's primary physical, chemical, and immunological barrier against external stimuli. A leaky epithelial barrier facilitates the translocation of the microbiome from the surface of the afflicted tissues to interepithelial and even deeper subepithelial locations. In turn, opportunistic bacterial colonization, microbiota dysbiosis, local inflammation and impaired tissue regeneration and remodelling follow. Migration of inflammatory cells to susceptible tissues contributes to damage and inflammation, initiating and aggravating many chronic inflammatory diseases. The objective of this review is to highlight and evaluate recent studies on epithelial physiology and its role in the pathogenesis of chronic diseases in light of the epithelial barrier theory.

Promises and Remaining Challenges for Further Integration of Basophil Activation Test in Allergy-Related Research and Clinical Practice

More than 20 years after having been initially proposed, the relevance and usefulness of basophil activation test (BAT) for the field of allergy research and testing were demonstrated on many occasions. Leveraging the fully open format of a flexible, whole blood-based functional assay, BAT has been shown to be equally important for fundamental research, clinical research, and diagnosis. Regardless of whether the focus of a study is on the characterization of the allergenic moiety, on the patient side, or on the study of the fundamental processes involved in the allergic disease or its treatment, BAT enables the gathering of very important insights. In spite of this, its full capabilities have yet to be leveraged. Various bottlenecks, including but not limited to assay logistics, robustness, flow cytometry access, and/or expertise, have indeed been limiting its development beyond experts and long-term users. Now, various initiatives, aiming at resolving these bottlenecks, have been launched. If successful, a broader use of BAT could then be contemplated. In such a situation, its more thorough integration in clinical practice has the potential to significantly change the allergic patient's journey.

Environmental Exposure to Foods as a Risk Factor for Food Allergy

PURPOSE OF REVIEW

Many factors have been reported to contribute to the development of food allergy. Here, we summarize the role of environmental exposure to foods as a major risk factor for developing food allergy.

RECENT FINDINGS

Peanut proteins are detectable and biologically active in household environments, where infants spend a majority of their time, providing an environmental source of allergen exposure. Recent evidence from clinical studies and mouse models suggests both the airway and skin are routes of exposure that lead to peanut sensitization. Environmental exposure to peanut has been clearly associated with the development of peanut allergy, although other factors such as genetic predisposition, microbial exposures, and timing of oral feeding of allergens also likely contribute. Future studies should more comprehensively assess the contributions of each of these factors for a variety of food allergens to provide more clear targets for prevention of food allergy.

Antioxidant potential of the diet in Italian children with food allergies

A reduced fruit and vegetable consumption, which implies a decreased intake of antioxidant compounds, seems to play a role in allergic diseases onset. Data on the antioxidant capacity of diet in children with food allergies, who are on an avoidance diet, are still lacking. This pilot study aims to assess the antioxidant potential of diet in Italian children with food allergies, compared to healthy children, using the oxygen radical absorbance capacity (ORAC) method. 95 children (54 with confirmed food allergies and 41 controls), with a median age of 7.8 years, were enrolled and underwent a nutritional assessment. Mean nutrient intakes were compared using the Mann–Whitney test. ORAC resulted significantly lower in allergic children (median 2,908, IQR: 1450;4,716) compared to control children (median 4,392, IQR: 2523;5,836; p = 0.049). Among micronutrients with antioxidant properties, vitamin A intakes were significantly higher in controls than in allergic children. Using Spearman’s correlation, a moderate-to-strong correlation between ORAC and vitamin C, potassium and magnesium was observed (ρ = 0.648, p < 0.001; ρ = 0.645, p < 0.001; ρ = 0.500, p < 0.001, respectively). Iron, phosphorus, vitamin E and vitamin A intakes were also moderately-to-low correlated with ORAC values (ρ = 0.351, p < 0.001; ρ = 0.367, p < 0.001; ρ = 0.346, p < 0.001; and ρ = 0.295, p = 0.004, respectively). We hypothesize that the reduced antioxidant potential of the diet might be related to a reduced variety of the diet in children with food allergies. Our study suggests that the diet of children with food allergies has a lower antioxidant potential (expressed as ORAC value) compared to the diet of healthy children, regardless of the allergenic food excluded from the diet. This issue should be further investigated in prospective, powered studies.

Vitamin D and Omega-3 (Fatty Acid) Supplementation in Pregnancy for the Primary Prevention of Food Allergy in Children-Literature Review

During the last decades the prevalence of food allergy (FA), an adverse immune response to a specific food antigen, has risen, with negative effects on the quality of life (QoL) of many children and their families. The pathogenesis of FA is complex, involving both genetic and environmental factors. SPINK5, STAT6, HLA and FOXP3 are some of the genes that are reported to be implicated in FA development. Regarding environmental factors, particular interest has been focused on modification of the dietary habits of pregnant women for the primary prevention of FA. Specifically, Vitamin D and omega-3 (Ω-3) fatty acid supplementation during pregnancy may influence the development of FA in the offspring. Vitamin D is a hormone with various actions, including mediation of the immune system, reducing the production of inflammatory cytokines and promoting tolerance. Vitamin D deficiency in pregnancy suppresses T-regulatory cells in the fetus, and Vitamin D supplementation might protect against FA development. Dietary Ω-3 fatty acids are found mainly in fish and vegetable oils. They are beneficial for human health, playing a role in the immune system as anti-inflammatory agents, and providing cell membrane stabilization with inhibition of antigen presentation. It is documented that maternal supplementation with Ω-3 during pregnancy may protect from allergic sensitization in the children. The aim of this literature review was to explore the potential preventive role of maternal supplementation during pregnancy with Vitamin D and Ω-3 in the development of FA in the offspring. With the prevalence of FA rising, all the possible protective mechanisms and measures for FA prevention need to be explored, starting with those that can be modified.

Allergic sensitization to foods in India and other Low-Middle-income countries

Food allergy is an important cause of morbidity, significantly affecting the quality of life of the sufferer. Most food allergy research has been undertaken in high-income countries. Here, we summarize literature regarding food allergy in India and other low-middle-income countries (LMIC). We provide summaries of self-reported adverse food reactions and food sensitization in these regions by reviewing published community-based studies of prevalence, burden, and risk factors. We identified 2 community-based studies of food allergy prevalence in Karnataka, India, which estimate that food allergy affects just 0.14% of children and 1.2% of adults. The overall prevalence of allergic sensitization to 'any' food was 26.5% in adults and 19.1% in children by serum-specific IgE; but only 4.48% in children by skin prick test. We identified a further 28 studies in other LMICs, mainly from China but also Turkey, South Africa, Ghana, Mexico, Brazil, Thailand, Philippines, and Korea. The overall prevalence of allergic sensitization to 'any' food ranged from 0.11% to 16.8% in children using serum-specific IgE and 0.14% to 9.6% in children by skin prick test. The questionnaires and skin prick testing materials used and number of allergens tested varied significantly between studies. Other than Karnataka, there is no information on prevalence of food sensitization and probable food allergy in the community in India. Similar lack of information is noted among the majority of the 136 LMICs. Where community-based studies have been undertaken, there is wide variation in the prevalence and patterns of food sensitization across different LMICs, at least partly due to variations in study methodology. International collaboration is required in order to formally assess food allergy prevalence and burden across representative samples from multiple LMICs.

Epicutaneous Sensitization and Food Allergy: Preventive Strategies Targeting Skin Barrier Repair-Facts and Challenges

Food allergy represents a growing public health and socio-economic problem with an increasing prevalence over the last two decades. Despite its substantial impact on the quality of life, current treatment options for food allergy are limited to strict allergen avoidance and emergency management, creating an urgent need for effective preventive strategies. Advances in the understanding of the food allergy pathogenesis allow to develop more precise approaches targeting specific pathophysiological pathways. Recently, the skin has become an important target for food allergy prevention strategies, as it has been hypothesized that allergen exposure through the impaired skin barrier might induce an immune response resulting in subsequent development of food allergy. This review aims to discuss current evidence supporting this complex interplay between the skin barrier dysfunction and food allergy by highlighting the crucial role of epicutaneous sensitization in the causality pathway leading to food allergen sensitization and progression to clinical food allergy. We also summarize recently studied prophylactic and therapeutic interventions targeting the skin barrier repair as an emerging food allergy prevention strategy and discuss current evidence controversies and future challenges. Further studies are needed before these promising strategies can be routinely implemented as prevention advice for the general population.

Exposure to ambient ultrafine particles and allergic sensitization in children up to 16 years

BACKGROUND

Few epidemiological studies so far have investigated the role of long-term exposure to ultrafine particles (UFP) in inhalant and food allergy development.

OBJECTIVES

The purpose of this study was to assess the association between UFP exposure and allergic sensitization to inhalant and food allergens in children up to 16 years old in the Netherlands.

METHODS

2295 participants of a prospective birth cohort with IgE measurements to common inhalant and food allergens at ages 4, 8, 12 and/or 16 were included in the study. Annual average UFP concentrations were estimated for the home addresses at birth and at the time of the IgE measurements using land-use regression models. Generalized estimating equations were used for the assessment of overall and age-specific associations between UFP exposure and allergic sensitization. Additionally, single- and two-pollutant models with NO₂, PM_2.5, PM_2.5 absorbance and PM₁₀ were assessed.

RESULTS

We found no significant associations between UFP exposure and allergic sensitization to inhalant and food allergens (OR (95% CI) ranging from 1.02 (0.95-1.10) to 1.05 (0.98-1.12), per IQR increment). NO₂, PM_2.5, PM_2.5 absorbance and PM₁₀ showed significant associations with sensitization to food allergens (OR (95% CI) ranging from 1.09 (1.00-1.20) to 1.23 (1.06-1.43) per IQR increment). NO₂, PM_2.5, PM_2.5 absorbance and PM₁₀ were not associated with sensitization to inhalant allergens. For NO₂, PM_2.5 and PM_2.5 absorbance, the associations with sensitization to food allergens persisted in two-pollutant models with UFP.

CONCLUSION

This study found no association between annual average exposure to UFP and allergic sensitization in children up to 16 years of age. NO₂, PM_2.5, PM_2.5 absorbance and PM₁₀ were associated with sensitization to food allergens.

Environmental Exposures may Hold the Key; Impact of Air Pollution, Greenness, and Rural/Farm Lifestyle on Allergic Outcomes

PURPOSE OF REVIEW

There has been an increased prevalence of allergy. Due to this relatively rapid rise, changes in environmental exposures are likely the main contributor. In this review, we highlight literature from the last 3 years pertaining to the role of air pollution, greenness, and the rural/farm lifestyle and their association with the development of allergic sensitization, atopic dermatitis, food allergy, and allergic rhinitis in infancy and childhood. Because asthma has a more complex pathophysiology, it was excluded from this review.

RECENT FINDINGS

Recent studies support a role for air pollution, greenness, and rural/farming lifestyle influencing atopic outcomes that continue to be defined. While many studies have examined singular environmental exposures, the interconnectedness of these exposures and others points to a need for future work to consider an individual's whole exposure. Environmental exposures' influence on atopic disease development remains an ongoing and important area of study.

Reactivity of nasal cavity mucosa in the nasal cow's milk allergen provocation test

Introduction

The nasal allergen provocation test plays an important role in differential diagnostics of rhinitis. Due to its informative potential, the test is also becoming increasingly used in other areas of diagnostics, including the diagnostics of food allergies.

Aim

To assess the reactivity of nasal mucosa to the cow's milk protein allergens (as being widely used in powdered form in the food industry).

Material and methods

The study material consisted of a group of 31 healthy subjects not sensitized to environmental allergens including cow's milk protein allergens. The study method involved an incremental nasal provocation test with cow's milk protein evaluated using the visual analog scale and acoustic rhinometry.

Results

A total of 29 out of 31 volunteers presented with a significant decrease in nasal patency (control solution: 1.112 ±0.161 vs. local allergen application 1.005 ±0.157; p < 0.004) as measured by acoustic rhinometry following the allergen dose of 12.5 μg. Slight changes in complaints were observed using the visual analog scale. Exposure to the widespread food allergens (including powdered cow's milk allergens) presents a potential risk of positive response in non-sensitized individuals.

Conclusions

Further studies on dose standardization are necessary in the study area.

Advances in the Study of Probiotics for Immunomodulation and Intervention in Food Allergy

Food allergies are a serious food safety and public health issue. Soybean, dairy, aquatic, poultry, and nut products are common allergens inducing allergic reactions and adverse symptoms such as atopic dermatitis, allergic eczema, allergic asthma, and allergic rhinitis. Probiotics are assumed as an essential ingredient in maintaining intestinal microorganisms' composition. They have unique physiological roles and therapeutic effects in maintaining the mucosal barrier, immune function, and gastrointestinal tract, inhibiting the invasion of pathogenic bacteria, and preventing diarrhea and food allergies. Multiple pieces of evidence reveal a significant disruptive effect of probiotics on food allergy pathology and progression mechanisms. Thus, this review describes the allergenic proteins as an entry point and briefly describes the application of probiotics in allergenic foods. Then, the role of probiotics in preventing and curing allergic diseases by regulating human immunity through intestinal flora and intestinal barrier, modulating host immune active cells, and improving host amino acid metabolism are described in detail. The anti-allergic role of probiotics in the function and metabolism of the gastrointestinal tract has been comprehensively explored to furnish insights for relieving food allergy symptoms and preventing food allergy.

Early-life exposure to air pollution associated with food allergy in children: Implications for 'one allergy' concept

BACKGROUND

The rapid increase of food allergy (FA) has become the "second wave" of allergy epidemic and is now a major global public health concern. Mounting evidence indicates that early life exposure to air pollution is associated with the "first wave" of allergy epidemic (including asthma, allergic rhinitis and eczema) in children, but little is known about its association with FA.

OBJECTIVES

We hypothesize FA has triple exposure pathways, gut-skin-airway, and investigate the effects of airway exposure to outdoor and indoor air pollution on childhood FA.

METHODS

A cohort study of 2598 preschool children aged 3-6 years old was conducted in Changsha, China. The prevalence of FA was surveyed using a standard questionnaire by International Study of Asthma and Allergies in Childhood (ISAAC). Exposure to indoor air pollution was assessed by four indicators: new furniture, redecoration, mold or dampness, and window condensation. Exposure to outdoor air pollution was evaluated by the concentrations of PM10, SO2 and NO2, which were obtained from the monitored stations. Both prenatal and postnatal exposure windows were considered. The association between exposure to outdoor/indoor air pollution and childhood FA was estimated by multiple logistic regression models using odds ratio (OR) and a 95% confidence interval (CI).

RESULTS

A total of 14.9% children reported FA. The prevalence was significantly associated with exposure to indoor air pollution, OR (95% CI) = 1.93 (1.35-2.75) for prenatal exposure to mold/dampness and 1.49 (1.07-2.10) and 1.41 (1.04-1.89) respectively for postnatal exposure to new furniture and window condensation. The prevalence of FA was also associated with prenatal and postnatal exposure to outdoor air pollution, particularly the traffic-related air pollutant NO2, with adjusted ORs (95% Cls) respectively 1.24 (1.00-1.54) and 1.38 (1.03-1.85) per interquartile range (IQR) increase. Sensitivity analysis showed that the association between outdoor/indoor air pollution and childhood FA was significant only in young children aged 3-4 years.

CONCLUSION

Early-life exposure to high levels of outdoor and indoor air pollution in China due to the rapid economic growth and fast urbanization in the past decades may contribute to the rapid increase of food allergy (FA) in children. Our study indicates that, in addition to gut and skin, airway may be a new route of food sensitization. Air pollution leads to the first and second waves of allergy epidemics, suggesting a concept of 'one allergy' disease.

Research Progress on the Correlation between the Intestinal Microbiota and Food Allergy

The increasing incidence of food allergy is becoming a substantial public health concern. Increasing evidence suggests that alterations in the composition of the intestinal microbiota play a part in the development of food allergy. Additionally, the application of probiotics to correct gut microbiota imbalances and regulate food allergy has become a research hotspot. However, the mechanism by which the gut microbiota regulates food allergy and the efficacy of probiotics are still in the preliminary exploration stage, and there are no clear and specific conclusions. The aim of this review is to provide information regarding the immune mechanism underlying food allergy, the correlation between the intestinal microbiota and food allergy, a detailed description of causation, and mechanisms by which the intestinal microbiota regulates food allergy. Subsequently, we highlight how probiotics modulate the gut microbiome–immune axis to alleviate food allergy. This study will contribute to the dovetailing of bacterial therapeutics with immune system in allergic individuals to prevent food allergy and ameliorate food allergy symptoms.

Nutrition during Pregnancy and Lactation: Epigenetic Effects on Infants’ Immune System in Food Allergy

Food allergies are an increasing health problem worldwide. They are multifactorial diseases, in which the genome alone does not explain the development of the disease, but a genetic predisposition and various environmental factors contribute to their onset. Environmental factors, in particular nutritional factors, in the early stages of life are recognized as key elements in the etiology of food allergies. There is growing evidence advising that nutrition can affect the risk of developing food allergies through epigenetic mechanisms elicited by the nutritional factors themselves or by modulating the gut microbiota and its functional products. Gut microbiota and postbiotics can in turn influence the risk of food allergy development through epigenetic mechanisms. Epigenetic programming accounts not only for the short-term effects on the individual’s health status, but also for those observed in adulthood. The first thousand days of life represent an important window of susceptibility in which environmental factors, including nutritional ones, can influence the risk of developing allergies through epigenetic mechanisms. From this point of view, it represents an interesting window of opportunity and intervention. This review reports the main nutritional factors that in the early stages of life can influence immune oral tolerance through the modulation of epigenetic mechanisms.