Presymptomatic differences in Toll-like receptor function in infants who have allergy

Cytokine production by newborns: influence of sex and season of birth

BACKGROUND

Immune signatures at birth could be associated with clinical outcomes and will improve our understanding of immunity prenatal programming.

METHODS

Data come from 235 newborns from the cohort study NELA. Production of cytokines was determined using Luminex technology. Associations between cytokine concentrations with sex and season of birth were examined by multivariate regression models.

RESULTS

Umbilical cord blood cells produced high levels of inflammatory cytokines, moderate levels of Th1/Th2/Tr-related cytokines, and low levels of Th17 cytokines. Compared to females, male newborn cells secreted higher levels of Th2 (peptidoglycan-stimulated IL-13, odds ratio [OR] = 2.26; 95% CI 1.18, 4.31, p value = 0.013) and Th17 (polyinosinic:polycytidylic acid-stimulated IL-23, OR = 1.82, 95% CI 1.01, 3.27, p value = 0.046) and lower levels of Th1 (olive-stimulated IL-2, OR = 0.56, 95% CI 0.31, 0.99, p value = 0.047) cytokines. Also, children born during warm seasons showed decreased innate cytokine response to peptidoglycan (IL-6, OR = 0.28, 95% CI 0.15, 0.52, p value < 0.001) compared to those born in cold seasons; meanwhile, adaptive immunity cytokines were more frequently secreted by children born during warm seasons in response to allergen extracts (IL-10, OR = 2.11, 95% CI 1.12, 3.96, p value = 0.020; IL-17F, OR = 3.31, 95% CI 1.83, 5.99, p value < 0.001).

CONCLUSION

Newborns showed specific cytokines signatures influenced by sex and season of birth.

IMPACT

There is a limited number of population-based studies on the immune status at birth and the influence of prenatal and perinatal factors on it. Characterization of cytokine signatures at birth related to the prenatal environment could improve our understanding of immunity prenatal programming. Newborns exhibit specific unstimulated and stimulated cytokine signatures influenced by sex and season of birth. Unstimulated and stimulated cytokine signatures in newborns may be associated with the development of related clinical outcomes later in life.

A role for metabolism in determining neonatal immune function

Immune responses of neonates differ markedly to those of adults, with skewed cytokine phenotypes, reduced inflammatory properties and drastically diminished memory function. Recent research efforts have started to unravel the role of cellular metabolism in determining immune cell fate and function. For studies in humans, much of the work on metabolic mechanisms underpinning innate and adaptive immune responses by different haematopoietic cell types is in adults. Studies investigating the contribution of metabolic adaptation in the unique setting of early life are just emerging, and much more work is needed to elucidate the contribution of metabolism to neonatal immune responses. Here, we discuss our current understanding of neonatal immune responses, examine some of the latest developments in neonatal immunometabolism and consider the possible role of altered metabolism to the distinctive immune phenotype of the neonate. Understanding the role of metabolism in regulating immune function at this critical stage in life has direct benefit for the child by affording opportunities to maximize immediate and long-term health. Additionally, gaining insight into the diversity of human immune function and naturally evolved immunometabolic strategies that modulate immune function could be harnessed for a wide range of opportunities including new therapeutic approaches.

Innate immune regulates cutaneous sensory IL-13 receptor alpha 2 to promote atopic dermatitis

The clinical significance and regulators of IL-13Rα2 in itch and atopic dermatitis (AD) remain unclear. To identify disease-driven regulatory circuits of IL-13Rα2, transcriptomic/pathological analysis was performed in skin from patients with AD, psoriasis, healthy subjects, and murine AD model. Functionality was investigated in sensory neurons, keratinocytes and animal model, by using knockdown (KD), calcium imaging, RNA-seq, cytokine arrays, pharmacological assays, and behavioural investigations. In our study, an upregulated IL-13Rα2 expression was revealed in skin of AD patients, but not psoriasis, in a disease activity-dependent manner. In cultured human keratinocytes, IL-13 increased IL-13Rα2 transcription levels, and this were downregulated by IL-13Rα1KD. IL-13Rα2KD reduced transcription levels of EDNRA, CCL20, CCL26. In contrast, sensory neuron-derived IL-13Rα2 was upregulated by TLR2 heterodimer agonists, Pam3CSK4 and FSL-1. In a mouse cheek model, pre-administration of Pam3CSK4 and FSL-1 enhanced IL-13-elicited scratching behaviour. Consistently, in cultured sensory neurons Pam3CSK4 enhanced IL-13-elicted calcium transients, increased number of responders, and orchestrated chemerin, CCL17 and CCL22 release. These release was inhibited by IL-13Rα2KD. Collectively, IL-13 regulates keratinocyte-derived IL-13Rα2 and TLR2 to modulate neuronal IL-13Rα2, thereby promoting neurogenic inflammation and exacerbating AD and itch. Thus, the cutaneous IL-13-IL-13Rα2 and neuronal TLR2-IL-13Rα2 pathway represent important targets to treat AD and itch.

Potential Biomarkers, Risk Factors and their Associations with IgE-mediated Food Allergy in Early Life: A Narrative Review

Food allergy affects the quality of life of millions of people worldwide and presents a significant psychological and financial burden for both national and international public health. In the past few decades, the prevalence of allergic disease has been on the rise worldwide. Identified risk factors for food allergy include family history, mode of delivery, variations in infant feeding practices, prior diagnosis of other atopic diseases such as eczema, and social economic status. Identifying reliable biomarkers which predict the risk of developing food allergy in early life would be valuable in both preventing morbidity and mortality and by making current interventions available at the earliest opportunity. There is also the potential to identify new therapeutic targets. This narrative review provides details on the genetic, epigenetic, dietary and microbiome influences upon the development of food allergy and synthesizes the currently available data indicating potential biomarkers. While there is a large body of research evidence available within each field of potential risk factors, there are very limited number of studies which span multiple methodological fields, for example including immunology, microbiome, genetic/epigenetic factors and dietary assessment. We recommend that further collaborative research with detailed cohort phenotyping is required to identify biomarkers, and whether these vary between at-risk populations and the wider population. The low incidence of oral food challenge confirmed food allergy in the general population, and the complexities of designing nutritional intervention studies will provide challenges for researchers to address in generating high quality, reliable and reproducible research findings.

STATEMENT OF SIGNIFICANCE

Food allergy affects the quality of life of millions of people worldwide and presents a significant psychological and financial burden for both national and international public health. Identifying reliable biomarkers which predict the risk of developing food allergy would be valuable in both preventing morbidity and mortality and by making current interventions available at the earliest opportunity. This review provides details on the genetic, epigenetic, dietary and microbiome influences upon the development of food allergy. This helps in identifying reliable biomarkers to predict the risk of developing food allergy, which could be valuable in both preventing morbidity and mortality and by making interventions available at the earliest opportunity.

Prenatal exposure to bisphenol - A is associated with dysregulated perinatal innate cytokine response and elevated cord IgE level: A population-based birth cohort study

BACKGROUND

Reports on the relationship between prenatal exposure to bisphenol-A (BPA) and the development of childhood allergy have been conflicting. This study aimed to investigate the impact of prenatal BPA exposure on several objective outcomes such as cytokine profile, atopic sensitization, and infant lung function (ILF) tests in addition to clinical allergic symptoms.

METHODS

A subset of 274 children from the PATCH cohort study with available cord BPA data were followed until 3 years of age. Total and specific IgE level and Toll-like receptor (TLR) stimulated cytokine production were assessed yearly since birth. ILF such as tidal volume, Vmax_FRC, airway resistance and compliance were performed at least once before the age of 2 years. Allergic outcome was determined by questionnaires and physician's assessment.

RESULTS

There was significant association between BPA concentration and IgE level in the cord blood (p < 0.01), but the correlation was no longer significant at ages 1 through 3 years. In addition, cord BPA concentration was associated with dysregulated TLR stimulated TNF-α and IL-6 production, but the correlation was significant only at birth. No relationship was found between cord BPA concentration and ILF measurements or allergic symptoms (wheezing, rhino-conjunctivitis, or eczema) throughout early childhood.

CONCLUSION

Results showed that prenatal exposure to BPA was not associated with increased risk of childhood allergy or impaired ILF. However, with its impact on biomarkers for allergy such as alterations in perinatal cytokine profile and elevated cord IgE level, the potential role of prenatal BPA exposure on the development of allergy cannot be disregarded.

Toll-Like Receptor Agonists as Adjuvants for Allergen Immunotherapy

Toll-like receptors (TLRs) are essential components of innate immunity and provide defensive inflammatory responses to invading pathogens. Located within the plasma membranes of cells and also intracellular endosomes, TLRs can detect a range of pathogen associated molecular patterns from bacteria, viruses and fungi. TLR activation on dendritic cells can propagate to an adaptive immune response, making them attractive targets for the development of both prophylactic and therapeutic vaccines. In contrast to conventional adjuvants such as aluminium salts, TLR agonists have a clear immunomodulatory profile that favours anti-allergic T lymphocyte responses. Consequently, the potential use of TLRs as adjuvants in Allergen Immunotherapy (AIT) for allergic rhinitis and asthma remains of great interest. Allergic Rhinitis is a Th2-driven, IgE-mediated disease that occurs in atopic individuals in response to exposure to otherwise harmless aeroallergens such as pollens, house dust mite and animal dander. AIT is indicated in subjects with allergic rhinitis whose symptoms are inadequately controlled by antihistamines and nasal corticosteroids. Unlike anti-allergic drugs, AIT is disease-modifying and may induce long-term disease remission through mechanisms involving upregulation of IgG and IgG4 antibodies, induction of regulatory T and B cells, and immune deviation in favour of Th1 responses that are maintained after treatment discontinuation. This process takes up to three years however, highlighting an unmet need for a more efficacious therapy with faster onset. Agonists targeting different TLRs to treat allergy are at different stages of development. Synthetic TLR4, and TLR9 agonists have progressed to clinical trials, while TLR2, TLR5 and TLR7 agonists been shown to have potent anti-allergic effects in human in vitro experiments and in vivo in animal studies. The anti-allergic properties of TLRs are broadly characterised by a combination of enhanced Th1 deviation, regulatory responses, and induction of blocking antibodies. While promising, a durable effect in larger clinical trials is yet to be observed and further long-term studies and comparative trials with conventional AIT are required before TLR adjuvants can be considered for inclusion in AIT. Here we critically evaluate experimental and clinical studies investigating TLRs and discuss their potential role in the future of AIT.

Therapeutic responses to Roseomonas mucosa in atopic dermatitis may involve lipid-mediated TNF-related epithelial repair

Dysbiosis of the skin microbiota is increasingly implicated as a contributor to the pathogenesis of atopic dermatitis (AD). We previously reported first-in-human safety and clinical activity results from topical application of the commensal skin bacterium Roseomonas mucosa for the treatment of AD in 10 adults and 5 children older than 9 years of age. Here, we examined the potential mechanism of action of R. mucosa treatment and its impact on children with AD less than 7 years of age, the most common age group for children with AD. In 15 children with AD, R. mucosa treatment was associated with amelioration of disease severity, improvement in epithelial barrier function, reduced Staphylococcus aureus burden on the skin, and a reduction in topical steroid requirements without severe adverse events. Our observed response rates to R. mucosa treatment were greater than those seen in historical placebo control groups in prior AD studies. Skin improvements and colonization by R. mucosa persisted for up to 8 months after cessation of treatment. Analyses of cellular scratch assays and the MC903 mouse model of AD suggested that production of sphingolipids by R. mucosa, cholinergic signaling, and flagellin expression may have contributed to therapeutic impact through induction of a TNFR2-mediated epithelial-to-mesenchymal transition. These results suggest that a randomized, placebo-controlled trial of R. mucosa treatment in individuals with AD is warranted and implicate commensals in the maintenance of the skin epithelial barrier.

The role of topical imiquimod in melanoma cutaneous metastases: A critical review of the literature

Despite of the emerging new systemic and local oncologic treatments (immunotherapy and checkpoint inhibitors, oncolytic viral treatments and injected immunostimulants) the management of skin melanoma metastasis can be still challenging. The main aim of this review was to assess the efficacy and the role of imiquimod in local metastatic melanoma disease. An extensive literature review was performed from September 2000 to March 2020 using PubMed, MEDLINE, Embase, and Cochrane Library databases. Selected articles regarded topical imiquimod, its mode of action as an antitumoral agent and its applications in melanoma metastases treatment. We analyzed a total of 18 published article of clinical cases and small case series and five studies: two retrospective large case series, two Phase I and II clinical trials and one cohort non randomized study. Generally, the treatment is safe and well tolerated. Imiquimod lead to an unstable locoregional control. The use of topical imiquimod for the treatment of MM cutaneous metastases should be considered in selected cases and in palliative settings.

Children with nut allergies have impaired gene expression of Toll-like receptors pathway

BACKGROUND

Trends in food allergies prompted investigation into the underlying mechanisms. Genetic and epigenetic factors are of high interest, and, in particular, the interplay between genes relating to immune factors directly and indirectly involved in food allergy pathogenesis. We sought to determine potential links between gene expression and epigenetic factors relating to Toll-like receptor (TLR) pathways and childhood food allergies.

METHODS

In a cross-sectional study, samples from 80 children with and without food allergies were analysed for gene expression, DNA methylation and a range of immune factors relating to TLR pathways. TLR2, TLR4, CD14, IL5, IL13 and vitamin D were explored.

RESULTS

The importance of these immune factors appeared to vary between the different types of food allergies. Expression of TLR2 (P < .001), TLR4 (P = .014) and CD14 (P = .028) varied significantly between children with no food allergy, allergy to nuts and peanuts, and allergy to eggs. DNA methylation in the promoter regions of these genes had a significant association with gene expression. These trends persisted when subjects were stratified by nut allergy vs no nut allergy. Furthermore, TLR2 (P = .001) and CD14 (P = .007) expressions were significantly lower in children with food allergies when compared to those without.

CONCLUSION

Gene expression of TLR pathway genes was directly related to food allergy type, and DNA methylation had an indirect effect. TLR2 pathways are of significant interest in nut allergies.

Endotoxin, food allergen sensitization, and food allergy: A complementary epidemiologic and experimental study

BACKGROUND

Household endotoxin levels have been variably associated with risk for asthma and atopy.

METHODS

We studied participants from the 2005-2006 National Health and Nutrition Examination Survey (NHANES, n = 6963), a large cohort representative of the US population (aged 1-84 years). We built logistic regression models to test for associations between house dust endotoxin and sensitization to specific foods (milk, egg, and peanut). To experimentally explore the detected epidemiologic associations, peripheral blood mononuclear cells (PBMCs) were collected from 21 children (aged 1-19 years) mono-food allergic (ie, sensitized and clinically reactive) to milk, egg, or peanut and nonallergic controls for stimulation with endotoxin and secreted cytokine measurement. For each food allergy, linear mixed-effects models were built to test the association between endotoxin stimulation and cytokine level.

RESULTS

Among NHANES subjects, the geometric mean household endotoxin level was 15.5 EU/mg (GSE 0.5). Prevalence of food allergen sensitization (sIgE ≥ 0.35 kU_A /L) varied by food: milk 5.7%, egg 4.0%, and peanut 7.9%. In models adjusted for potential confounders (age, race, country of birth, total people per household, US region, and history of wheezing in the past year), household endotoxin level was associated with sensitization to milk (OR 1.7, 95% CI 1.2-2.1) and egg (OR 1.4, 95% CI 1.01-1.9), but not peanut (OR 0.98, 95% CI 0.8-1.2). Interferon-γ levels of endotoxin-stimulated PBMCs from children allergic to milk or egg, but not peanut, were significantly lower compared to controls in linear mixed-effects models adjusted for repeated measures, experimental variables, age, and inter-individual variability (P-values .007, .018, and .058, respectively).

CONCLUSION

Higher household endotoxin is associated with increased odds of milk and egg sensitization. Altered cytokine responsiveness to endotoxin is also observed in PBMCs from individuals with milk and egg allergy.

Epigenetic dysregulation of naive CD4+ T-cell activation genes in childhood food allergy

Food allergy poses a significant clinical and public health burden affecting 2–10% of infants. Using integrated DNA methylation and transcriptomic profiling, we found that polyclonal activation of naive CD4+ T cells through the T cell receptor results in poorer lymphoproliferative responses in children with immunoglobulin E (IgE)-mediated food allergy. Reduced expression of cell cycle-related targets of the E2F and MYC transcription factor networks, and remodeling of DNA methylation at metabolic (RPTOR, PIK3D, MAPK1, FOXO1) and inflammatory genes (IL1R, IL18RAP, CD82) underpins this suboptimal response. Infants who fail to resolve food allergy in later childhood exhibit cumulative increases in epigenetic disruption at T cell activation genes and poorer lymphoproliferative responses compared to children who resolved food allergy. Our data indicate epigenetic dysregulation in the early stages of signal transduction through the T cell receptor complex, and likely reflects pathways modified by gene–environment interactions in food allergy.

Immunoglobulin E (IgE)-mediated food allergy is a major issue that affects 2–10% of infants. Here the authors study the epigenetic regulation of the naive CD4+ T cell activation response among children with IgE-mediated food allergy finding epigenetic dysregulation in the early stages of signal transduction through the T cell receptor complex.

Cord Blood CD8+ T Cells Have a Natural Propensity to Express IL-4 in a Fatty Acid Metabolism and Caspase Activation-Dependent Manner

How T cells differentiate in the neonate may critically determine the ability of the infant to cope with infections, respond to vaccines and avert allergies. Previously, we found that naïve cord blood CD4⁺ T cells differentiated toward an IL-4-expressing phenotype when activated in the presence of TGF-β and monocyte-derived inflammatory cytokines, the latter are more highly secreted by infants who developed food allergy. Here, we show that in the absence of IL-2 or IL-12, naïve cord blood CD8⁺ T cells have a natural propensity to differentiate into IL-4-producing non-classic T_C2 cells when they are activated alone, or in the presence of TGF-β and/or inflammatory cytokines. Mechanistically, non-classic T_C2 development is associated with decreased expression of IL-2 receptor alpha (CD25) and glycolysis, and increased fatty acid metabolism and caspase-dependent cell death. Consequently, the short chain fatty acid, sodium propionate (NaPo), enhanced IL-4 expression, but exogenous IL-2 or pan-caspase inhibition prevented IL-4 expression. In children with endoscopically and histologically confirmed non-inflammatory bowel disease and non-infectious pediatric idiopathic colitis, the presence of TGF-β, NaPo, and IL-1β or TNF-α promoted T_C2 differentiation in vitro. In vivo, colonic mucosa of children with colitis had significantly increased expression of IL-4 in CD8⁺ T cells compared with controls. In addition, activated caspase-3 and IL-4 were co-expressed in CD8⁺ T cells in the colonic mucosa of children with colitis. Thus, in the context of colonic inflammation and limited IL-2 signaling, CD8⁺ T cells differentiate into non-classic T_C2 that may contribute to the pathology of inflammatory/allergic diseases in children.

Development of allergic immunity in early life

The growth and maturity of the peripheral immune system and subsequent development of pulmonary immunity in early life is dictated by host, environmental and microbial factors. Dysregulation during the critical window of immune development in the postnatal years results in disease which impacts on lifelong lung health. Asthma is a common disease in childhood and is often preceded by wheezing illnesses during the preschool years. However, the mechanisms underlying development of wheeze and how and why only some children progress to asthma is unknown. Human studies to date have generally focused on peripheral immune development, with little assessment of local tissue pathology in young children. Moreover, mechanisms underlying the interactions between inflammation and tissue repair at mucosal surfaces in early life remain unknown. Disappointingly, mechanistic studies in mice have predominantly used adult models. This review will consider the aspects of the neonatal immune system which might contribute to the development of early life wheezing disorders and asthma, and discuss the external environmental factors which may influence this process.

Different capacity of in vitro generated myeloid dendritic cells of newborns of healthy and allergic mothers to respond to probiotic strain E. coli O83:K24:H31

Allergic diseases belong to one of the most common diseases with steadily increasing incidence even among young children. There is an urgent need to identify a prognostic marker pointing to increased risk of allergy development enabling early preventive measures introduction. It has been shown that administration of selected probiotic strains or mixtures could prevent allergy development. In our study, we have tested the capacity of probiotic strain Escherichia coli O83:K24:H31 (E. coli O83) to promote dendritic cell (DC) maturation and polarisation of immune responses. Increased presence of activation marker CD83 was observed on DC stimulated by E. coli O83 and DC of newborns of allergic mothers have significantly more increased cell surface presence of CD83 in comparison to children of healthy mothers. Increased gene expression and secretion of IL-10 was detected in DC stimulated with E. coli O83 being higher in DC of newborns of healthy mothers in comparison to allergic ones. Generally, increased presence of intracellular cytokines (IL-4, IL-13, IFN-gamma, IL-17A, IL-22, IL-10) was detected in CD4+ T cells cocultured with DC of children of allergic mothers in comparison to healthy ones. E. coli O83 primed DC significantly increased IL-10 and IL-17A in CD4 T cells of newborns of healthy mothers in comparison to the levels detected in CD4 T cells cocultured with control non-stimulated DC. We can conclude E. coli O83 induces dendritic cell maturation and IL-10 production in DC. Newborns of allergic mothers have generally increased reactivity of both DC and CD4 T cells which together with decreased capacity of DC of newborns of allergic mothers to produce IL-10 could support inappropriate immune responses development after allergen encounter.

Caesarean Section is associated with reduced perinatal cytokine response, increased risk of bacterial colonization in the airway, and infantile wheezing

The relationship between cesarean section (CS) and allergic disorders such as asthma and wheezing has been inconsistent, and the mechanisms for their connection remained largely unknown. We aimed to investigate whether CS is associated with infantile wheeze and to explore the connection between CS and several risk factors known to correlate with allergy development. Mononuclear cells were isolated from cord blood and assessed for cytokine responses by ELISA. Bacteria from nasopharyngeal specimens were identified with traditional culture methods. Infant lung function tests were performed at 6 and 12 months of age. IgE levels and clinical outcomes were assessed at 12 months. The result showed that children delivered by CS were associated with increased risk of wheezing (aHR 1.63; 95% CI: 1.01–2.62) and decreased compliance of the respiratory system at 12 months (p = 0.045). In addition, CS was associated with reduced TLR1–2- triggered TNF-α and IL-6 responses at birth. By12 months of age, children delivered by CS had significantly less airway bacterial clearance. Our findings suggested that CS was associated with decreased pro-inflammatory cytokine response to TLR1–2 stimulation, followed by higher abundance of bacterial colonization in the airway during late infancy, thus increasing the risk of infantile wheezing.

Postnatal Innate Immune Development: From Birth to Adulthood

It is well established that adaptive immune responses are deficient in early life, contributing to increased mortality and morbidity. The developmental trajectories of different components of innate immunity are only recently being explored. Individual molecules, cells, or pathways of innate recognition and signaling, within different compartments/anatomical sites, demonstrate variable maturation patterns. Despite some discrepancies among published data, valuable information is emerging, showing that the developmental pattern of cytokine responses during early life is age and toll-like receptor specific, and may be modified by genetic and environmental factors. Interestingly, specific environmental exposures have been linked both to innate function modifications and the occurrence of chronic inflammatory disorders, such as respiratory allergies. As these conditions are on the rise, our knowledge on innate immune development and its modulating factors needs to be expanded. Improved understanding of the sequence of events associated with disease onset and persistence will lead toward meaningful interventions. This review describes the state-of-the-art on normal postnatal innate immune ontogeny and highlights research areas that are currently explored or should be further addressed.

The role of toll-like receptor 3 in chronic contact hypersensitivity induced by repeated elicitation

BACKGROUND

Accumulating evidence suggests that Toll-like receptor (TLR)-3 signaling is involved in non-infectious immune and inflammatory reactions as well as in viral infections. The skin of patients with atopic dermatitis (AD) is often infected with virus and bacteria, leading to the aggravation of atopic symptoms. These findings suggest TLR3 signaling may be involved in the pathogenesis of AD, but the exact role of TLR3 in AD remains to be defined.

OBJECTIVE

The purpose of this study was to investigate the role of TLR3 in chronic contact hypersensitivity reactions induced by repeated elicitation, resembling the features of AD.

METHODS

Wild-type (WT) and Toll-like receptor 3 knockout (Tlr3 KO) mice were sensitized, and chronic contact hypersensitivity reactions were elicited in their ear skin via repeated application of a hapten, 2,4,6-trinitro-1-chlorobenzene (TNCB) or oxazolone.

RESULTS

The Tlr3 KO mice exhibited less ear swelling, less leukocyte infiltration into the skin, and lower serum total IgE levels than WT mice after hapten challenge. The Tlr3 KO mice also displayed lower expression levels of inflammatory cytokines (interleukin (IL)-33, IL-4, IL-10, and interferon-ɤ in their TNCB-treated ear skin than WT mice.

CONCLUSION

These results showed that TLR3 deficiency suppressed the development of chronic contact hypersensitivity reactions, suggesting that TLR3 signaling may participate in the pathogenesis of AD.

Longitudinal pattern of multiplexed immunoglobulin E sensitization from prenatal stage to the first year of life

BACKGROUND

The longitudinal pattern of allergen-specific IgE levels from the prenatal stage to early life has remained largely unexplored.

METHODS

One-hundred and three mother-infant pairs, which were part of an ongoing population-based prospective birth cohort study of early childhood allergic diseases in Tainan, Taiwan, were included in this study. We examined the relationship of 20 allergen-specific IgE levels with blood samples of mothers, cord blood, and infants at 12 months of age using Spearman rank correlation, Kenal τ and McNemar test, respectively.

RESULTS

Certain degree of IgE sensitization against most 20 examined specific allergens was observed in blood samples of mothers, cord blood, and infants at 12 months of age. When we further examined the association between allergy-related risk factors and atopy in infants at the first year of life, we found positive association between colic pain and atopy in infants at 12 months of age [adjusted odds ratios (AOR) = 3.51; 95% confidence interval (CI): 1.13-10.96; p = 0.03], and borderline significance between wheezing and atopy in infants at 12 months of age (AOR = 4.58; 95% CI: 0.89-23.50; p = 0.07).

CONCLUSION

The findings from this study suggest that influence of maternal allergen-specific IgE levels on infant immune response might occur at birth and then wane in infants at 12 months of age. Positive association of colic pain and wheezing with atopy in infants at 12 months of age provides supportive evidence for the 'Allergy March' theory of allergy development in an Asian birth cohort.

The influence of atopy and asthma on immune responses in inner-city adults

Asthma in the inner‐city population is usually atopic in nature, and is associated with significant morbidity and mortality. However, the underlying immune abnormalities that underlie asthma in urban adults have not been well defined. We investigated the influence of atopy and asthma on cytokine responses of inner‐city adult women to define immune abnormalities associated with asthma and atopy. Blood samples were collected from 509 of 606 inner‐city women enrolled in the Urban Environment and Childhood Asthma (URECA) study. We tested for associations between atopy and asthma status and cytokine responses in peripheral blood mononuclear cells incubated ex vivo with a panel of innate and adaptive immune stimulants. Atopic subjects had heightened Th2 cytokine responses (IL‐4, IL‐5, IL‐13) to cockroach and dust mite antigens, tetanus toxoid, and phytohemagglutinin (P < 0.05 for all). Differences in cytokine responses were greatest in response to stimulation with cockroach and dust mite. In a multivariate analysis, atopy was broadly related to increased Th2‐like responses to all antigens and PHA, while asthma was only weakly related to mitogen‐induced IL‐4 and IL‐5 responses. There were few asthma or allergy‐related differences in responses to innate stimuli, including IFN‐α and IFN‐γ responses. In this inner‐city adult female population, atopy is associated with enhanced Th2 responses to allergens and other stimuli, and there was little or no additional signal attributable to asthma. In particular, these data indicate that altered systemic interferon and innate immune responses are not associated with allergies and/or asthma in inner‐city women.

Cord blood monocyte–derived inflammatory cytokines suppress IL-2 and induce nonclassic “T H 2-type” immunity associated with development of food allergy

Infants who develop food allergy display hyperresponsive innate immunity at birth that promotes nonclassical T H 2 differentiation.

Does allergy begin in utero?

It has been recognized for centuries that allergic disease runs in families, implying a role for genetic factors in determining individual susceptibility. More recently, a range of evidence shows that many of these genetic factors, together with in utero environmental exposures, lead to the development of allergic disease through altered immune and organ development. Environmental exposures during pregnancy including diet, nutrient intake and toxin exposures can alter the epigenome and interact with inherited genetic and epigenetic risk factors to directly and indirectly influence organ development and immune programming. Understanding of these factors will be essential in identifying at-risk individuals and possible development of therapeutic interventions for the primary prevention of allergic disease. In this review, we summarize the evidence that suggests allergic disease begins in utero, together with possible mechanisms for the effect of environmental exposures during pregnancy on allergic disease risk, including epigenetics.

Reduced neonatal regulatory T cell response to microbial stimuli associates with subsequent eczema in high-risk infants

BACKGROUND

Regulatory T cells (Treg) play an essential role in early immune programming and shaping the immune response towards a pro-allergic or tolerant state. We evaluated cord blood Treg and cytokine responses to microbial and non-microbial stimuli in infants at high risk of allergic disease and their associations with development of allergic disease in the first year.

METHODS

Cord blood mononuclear cells from 72 neonates were cultured with toll-like receptors (TLR2) ligands: lipoteichoic acid (LTA) and heat-killed Lactobacillus rhamnosus GG (HKL); TLR4 ligand: lipopolysaccharide (LPS); ovalbumin (OVA); anti-CD3; or media for 48 h. Treg numbers and Treg cytokines were assessed in relation to allergic disease outcomes during the first year of life (eczema and atopic sensitization).

RESULTS

Infants with eczema (n = 24) had reduced percentages of FoxP3(hi)CD25(hi) Treg in LTA (p = 0.01, adj p = 0.005) and HKL (p = 0.04, adj p = 0.02) stimulated cultures as well as reduced IL-10 (p = 0.01) production following HKL stimulation compared to those without eczema (n = 48). No differences in Treg or cytokine responses to LPS, OVA or anti-CD3 were seen. Infants who developed sensitization had lower percentages of Treg following TLR2 stimulation (but not other stimuli) compared to non-sensitized infants.

CONCLUSIONS

High-risk children who develop allergic disease in the first year of life have deficient Treg responses to microbial stimuli but not allergen from the time of birth, which may contribute to failure of immune tolerance development in infancy.

Non-celiac gluten sensitivity: literature review

BACKGROUND

A significant percentage of the general population report problems caused by wheat and/or gluten ingestion, even though they do not have celiac disease (CD) or wheat allergy (WA), because they test negative both for CD-specific serology and histopathology and for immunoglobulin E (IgE)-mediated assays. Most patients report both gastrointestinal and nongastrointestinal symptoms, and all report improvement of symptoms on a gluten-free diet. This clinical condition has been named non-celiac gluten sensitivity (NCGS).

AIM

We attempt to define the current pathogenic, clinical, and diagnostic criteria of this "new" disease, to provide a practical view that might be useful to evaluate, diagnose, and manage NCGS patients.

METHODS

We reviewed the international literature through PubMed and Medline, using the search terms "wheat (hyper)sensitivity," "wheat allergy," "wheat intolerance," "gluten (hyper)sensitivity," and "gluten intolerance," and we discuss current knowledge about NCGS.

RESULTS

It has been demonstrated that patients suffering from NCGS are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis, clinical history, and, probably, clinical course. NCGS diagnosis can be reached only by excluding CD and WA. Recent evidence shows that a personal history of food allergy in infancy, coexistent atopy, positive for immunoglobulin G (IgG) antigliadin antibodies and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts, could be useful to identify NCGS patients.

CONCLUSIONS

Future research should aim to identify reliable biomarkers for NCGS diagnosis and to better define the different NCGS subgroups. Key teaching points: • Most patients report both gastrointestinal and nongastrointestinal symptoms, and all agree that there is an improvement of symptoms on a gluten-free diet. • NCGS diagnosis can be reached only by excluding celiac disease and wheat allergy. • Patients suffering from NCGS are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis, clinical history, and, probably, clinical course. • A personal history of food allergy in infancy, coexistent atopy, positive IgG antigliadin antibodies (AGA) and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts, could be useful to identify NCGS patients. • Future research should aim to identify reliable biomarkers for NCGS diagnosis and to better define the different NCGS subgroup.

Toll-like receptor 3 increases allergic and irritant contact dermatitis

There is increasing recognition of the role of Toll-like receptor 3 (TLR3) in noninfectious inflammatory diseases, but the function of TLR3 in inflammatory skin diseases is unclear. We investigated the functions of TLR3 in allergic and irritant contact dermatitis (ICD). The contact hypersensitivity (CHS) response was lower in Toll-like receptor 3 knockout (Tlr3 KO) mice, and was greater in TLR3 transgenic (Tg) mice than in wild-type (WT) mice after challenge with 2,4,6-trinitro-1-chlorobenzene. Adoptive transfer of immunized lymph node cells from Tlr3 KO mice induced CHS in WT recipients. In contrast, adoptive transfer of those from WT mice did not fully induce CHS in Tlr3 KO recipients. The ICD reaction following croton oil application was lower in Tlr3 KO mice, and was greater in TLR3 Tg mice than in WT mice. Maturation, migration, and antigen presentation of dendritic cells and proliferation of lymphocytes between WT mice and Tlr3 KO mice were comparable. These results show that TLR3 enhances antigen-independent skin inflammation in the elicitation phase of allergic contact dermatitis and in ICD.

In vitro evaluation of intestinal epithelial TLR activation in preventing food allergic responses

Alterations in the gut microbiota composition are associated with food allergy. Toll-like receptors (TLRs) respond to microbial stimuli. We studied the effects of the ligation of TLRs on intestinal epithelial cells (IECs) in preventing an allergic effector response. IEC monolayers (T84 cells) were co-cultured with CD3/28-activated PBMCs from healthy controls or atopic patients and simultaneously apically exposed to TLR2, TLR4 or TLR9 ligands. The barrier integrity of T84 cell monolayers was significantly reduced upon co-culture with PBMCs of food allergic subjects compared to healthy subjects. Apical exposure of IECs to a TLR9 ligand prevented PBMC-induced epithelial barrier disruption. Using PBMCs from food allergic subjects, apical TLR9 activation on IECs increased the IFN-γ/IL-13 and IL-10/IL-13 ratio, while suppressing pro-inflammatory IL-6, IL-8 and TNF-α production in an IEC-dependent manner. Hence, the activation of apical TLR9 on IECs, potentially by microbiota-derived signals, may play an important role in the prevention of allergic inflammation.

Pre- and postnatal administration of Lactobacillus reuteri decreases TLR2 responses in infants

Background

Mice models indicate that intact Toll like receptor (TLR) signaling may be essential for the allergy protective effects of diverse bacterial exposure observed in clinical trials and epidemiological studies. Probiotic supplementation with Lactobacillus reuteri from pregnancy week 36 and to the infant through the first year of life decreased the prevalence of IgE-associated eczema at two years (ClinicalTrials.gov NCT01285830). The effect of this supplementation on innate immune responses to bacterial products and the expression of associated TLRs were explored.

Methods

Blood mononuclear cells were collected at birth, 6, 12 and 24 months from 61 infants and cultured with TLR2, 4 and 9 ligands. Cytokine and chemokine secretion was determined as well as TLR2, 4 and 9 mRNA expression.

Results

Probiotic supplementation was associated with decreased LTA (lipoteichoic acid) induced CCL4, CXCL8, IL-1β and IL-6 responses at 12 months and decreased CCL4 and IL-1β secretion at 24 months. TLR2 mRNA expression was not affected by probiotic treatment.

Conclusions

Decreased responses to TLR2, the main receptor for LTA from Gram positive bacteria, in probiotic treated children seem to be dependent on factors downstream of TLR mRNA expression.

Regulation of Intestinal Immune Responses through TLR Activation: Implications for Pro- and Prebiotics

The intestinal mucosa is constantly facing a high load of antigens including bacterial antigens derived from the microbiota and food. Despite this, the immune cells present in the gastrointestinal tract do not initiate a pro-inflammatory immune response. Toll-like receptors (TLRs) are pattern recognition receptors expressed by various cells in the gastrointestinal tract, including intestinal epithelial cells (IEC) and resident immune cells in the lamina propria. Many diseases, including chronic intestinal inflammation (e.g., inflammatory bowel disease), irritable bowel syndrome (IBS), allergic gastroenteritis (e.g., eosinophilic gastroenteritis and allergic IBS), and infections are nowadays associated with a deregulated microbiota. The microbiota may directly interact with TLR. In addition, differences in intestinal TLR expression in health and disease may suggest that TLRs play an essential role in disease pathogenesis and may be novel targets for therapy. TLR signaling in the gut is involved in either maintaining intestinal homeostasis or the induction of an inflammatory response. This mini review provides an overview of the current knowledge regarding the contribution of intestinal epithelial TLR signaling in both tolerance induction or promoting intestinal inflammation, with a focus on food allergy. We will also highlight a potential role of the microbiota in regulating gut immune responses, especially through TLR activation.

A potential link between bacterial pathogens and allergic conjunctivitis by dendritic cells

The association and mechanism of bacteria linking to the allergic inflammation have not been well elucidated. This study was to explore a potential link between bacterial pathogens and allergic conjunctivitis by dendritic cells (DCs). Bone marrow-derived DCs from BALB/c and MyD88 knockout mice were treated with or without bacterial pathogens or thymic stromal lymphopoietin (TSLP). Two murine models of the topical challenge with LPS or flagellin and experimental allergic conjunctivitis (EAC) were used for in vivo study. The mRNA expression was determined by reverse transcription and real time PCR, and protein production was evaluated by ELISA, Western blotting, immunofluorescent staining and flow cytometry. TSLP mRNA and protein were found to be largely induced by DCs challenged with microbial pathogens, highly by lipopolysaccharide (LPS) and flagellin. The expression of MyD88, NFκB1, NFκB2 and RelA accompanied by NFκB p65 nuclear translocation and TSLP induction were significantly stimulated by flagellin, but blocked by TLR5 antibody or NFκB inhibitor in DCs from MyD88(+/+) but not MyD88(-/-) mice. TSLP promoted the expression of CD40, CD80, OX40 ligand (OX40L), IL-13 and CCL17 by DCs. TSLP-producing DCs were identified in vivo in ocular surface conjunctiva and draining cervical lymph nodes from two murine models of topical challenge with LPS or flagellin, and EAC in BALB/c mice. TSLP/TSLPR/OX40L signaling was observed in DCs of EAC mice. Our findings demonstrate that DCs not only respond to TSLP, but also produce TSLP via TLR/MyD88/NFκB pathways in response to bacterial pathogens, suggesting a potential link between bacteria and allergic disease.

Potential autocrine regulation of interleukin-33/ST2 signaling of dendritic cells in allergic inflammation

This study identified a novel phenomenon that dendritic cells (DCs) produced interleukin (IL)-33 via Toll-like receptor (TLR)-mediated innate pathway. Mouse bone marrow-derived DCs were treated with or without microbial pathogens or recombinant murine IL-33. IL-33 mRNA and protein were found to be expressed by DCs and largely induced by several microbial pathogens, highly by lipopolysaccharide (LPS) and flagellin. Using two mouse models of topical challenge by LPS and flagellin and experimental allergic conjunctivitis, IL-33-producing DCs were observed in ocular mucosal surface and the draining cervical lymph nodes in vivo. The increased expression levels of myeloid differentiation primary-response protein 88 (MyD88), nuclear factor (NF)-κB1, NF-κB2, and RelA accompanied by NF-κB p65 nuclear translocation were observed in DCs exposed to flagellin. IL-33 induction by flagellin was significantly blocked by TLR5 antibody or NF-κB inhibitor quinazoline and diminished in DCs from MyD88 knockout mice. IL-33 stimulated the expression of DC maturation markers, CD40 and CD80, and proallergic cytokines and chemokines, OX40L, IL-4, IL-5, IL-13, CCL17 (C-C motif chemokine ligand 17), TNF-α (tumor necrosis factor-α), and IL-1β. This stimulatory effect of IL-33 in DCs was significantly blocked by ST2 antibody or soluble ST2. Our findings demonstrate that DCs produce IL-33 via TLR/NF-κB signaling pathways, suggesting a molecular mechanism by which local allergic inflammatory response may be amplified by DC-produced IL-33 through potential autocrine regulation.

Maturation of Toll-like receptor 1-4 responsiveness during early life

BACKGROUND

Toll-like receptors (TLRs) are part of the highly conserved components of the innate immune system, and have been investigated extensively; however, little is known about TLR function during early postnatal life, a critical period for immune maturation.

AIMS

In order to achieve a more complete understanding of the ontogeny of immune system during the first years of life, our study investigated age-matched TLR1-4 responsiveness at several time points up to the age of two years.

STUDY DESIGN

Mononuclear cells were isolated from cord blood (n=150) and peripheral blood from infants at 6 (n=68), 12 (n=75), and 24 (n=74)months of age, and from 50 adults. Cells were stimulated with Toll-like receptor ligands (TLR1-4) and phytohemagglutinin (PHA). Stimulated cells were assessed for their production of the cytokines tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), and for TLR4 gene expression.

RESULTS

Our results suggested that cord response of IL-6 and TNF-α was not affected by allergic background. In addition, neonatal mononuclear cell had enhanced IL-6 production upon TLR1, 2, and 4 stimulations as compared to those of young children and adults. Nevertheless, after 6 months of age, the level remained comparable throughout the first two years of life. While TNF-α response to all TLR stimulations remained fairly similar during early life. This cytokine pattern closely paralleled our findings for TLR4 mRNA expression, and longitudinal cytokine changes within the same individual.

CONCLUSIONS

Our findings provided additional information to the understanding of immune development during early life, and offered stronger evidence of neonatal innate immunity being capable of responding adequately to TLR stimulation.

The neonatal susceptibility window for inhalant allergen sensitization in the atopically predisposed canine asthma model

Allergic asthma often begins in early life and, although many risk factors have been enumerated, the specific factors that initiate disease progression in an individual remain unclear. Using our dog model of early life allergen inhalation, we tested the hypothesis that the atopically biased neonatal immune system would exhibit tolerance to ragweed if allowed to mature normally before exposure or artificially through innate immune stimulation with early life exposure. Dogs were subjected to a series of inhalational ragweed exposures from 1 to 20 weeks old, with or without inhalation of a Toll-like receptor 4 (TLR4) agonist (CRX-527), or from 13 to 31 weeks old. Serum allergen-specific antibody response was assessed at 4, 8 and 20 weeks after the last sensitizing exposure. At 24 or 35 weeks old, airway hyper-responsiveness to methacholine and ragweed challenges and pulmonary inflammation by bronchoalveolar lavage were tested 1 and 4 days after ragweed challenge at 28 or 39 weeks old. Allergen-free immune maturation resulted in no airway hyper-responsiveness and very little ragweed-specific IgE relative to the control group, but eosinophilia developed upon ragweed challenge. TLR4 agonism yielded no airway hyper-responsiveness, but a strong airway neutrophilia developed upon ragweed challenge. Our data indicate that an atopic predisposition creates a critical window in which allergen exposure can lead to an asthmatic phenotype. Allergen-free immune maturation may lead to allergen tolerance. TLR4 agonism before early life allergen exposure may abrogate the development of allergen-specific bronchonconstriction, but allergen-specific pulmonary inflammation remains a strong concern.

Progress in understanding the epigenetic basis for immune development, immune function, and the rising incidence of allergic disease

The profile of allergic disease worldwide continues to change as the number of severe IgE-mediated allergies increases. This phenomenon is thought to reflect the outcome of combined genetic/environmental/developmental/stochastic effects on immune development, but understanding this remains a challenge. Epigenetic disruption at key immune genes during development has been proposed as a potential explanation for how environmental exposures may alter immune cell development and function. This represents an emerging area of research with the potential to yield new understanding of how disease risk is modified. Here, we examine recent developments in this field that are defining new epigenetic paradigms of allergic disease.

Neonatal protein kinase C zeta expression determines the neonatal T-Cell cytokine phenotype and predicts the development and severity of infant allergic disease

BACKGROUND

Previous studies have demonstrated that reduced T-cell protein kinase C zeta (PKCζ) expression is associated with allergy development in infants born to atopic mothers. This study examined whether this relationship extends to a general population and addressed the basis for the association.

METHODS

A flow cytometry assay was developed for the measurement of T-cell PKCζ levels in PBMC, cord blood mononuclear cell and whole blood. Cord blood T-cell PKCζ levels were measured in 135 neonates, and allergic disease was evaluated by skin prick test and clinical examination at 12 months of age.

RESULTS

Allergic children (particularly those with eczema) had significantly lower neonatal T-cell PKCζ expression than nonallergic children (P < 0.001). PKCζ levels predicted allergic disease with optimal specificity of 86% and sensitivity of 54%. The sensitivity was increased in the children of allergic mothers, who had significantly lower PKC levels than the children of nonallergic mothers. Cord blood PKCζ levels did not affect T-cell maturation in culture as assessed by CD45RA/RO expression, but low PKCζ expression was associated with reduced capacity for IFNγ production by matured T cells. Low cord blood PKC expression was further associated with increased IL-13 responses at 6 months.

CONCLUSIONS

The findings suggest a potential role for the use of PKCζ levels in cord blood T cells as a presymptomatic test to predict allergy risk in children, particularly offspring of allergic mothers, and that the basis of this relationship is related to cytokine patterns in mature T cells.

IFN-λ and IgE-mediated allergic disease: a potential future role?

Reduced early microbial exposure has become a leading candidate to explain the rise in allergic disease, and research has focused on studying the interaction between the developing immune system and the microbial environment. However, despite intense interest, the pathways that lead to dysregulation of the immune system in allergic disease are still poorly understood. The newly described type III IFN-λ molecules were initially shown to exhibit antiviral activity, but these molecules are also likely to have an important role to play in the immune-epithelial interface, given their immunomodulatory functions and restricted receptor expression to immune and epithelial cells. Previous studies on the role of IFN-λ in allergic disease have been limited to allergic asthma. More recently, a genetic variation flanking IL28B encoding IFN-λ3 has been associated with allergic disease. Here, we examine this family and suggest how IFN-λ may be an important player in allergic disease.

Neonatal antigen-presenting cells are functionally more quiescent in children born under traditional compared with modern environmental conditions

BACKGROUND

One explanation for the high burden of allergic and autoimmune diseases in industrialized countries is inappropriate immune development under modern environmental conditions. There is increasing evidence that the process of immune deviation already begins in utero, but the underlying immunologic mechanisms are not clear.

OBJECTIVE

We sought to identify differences in the function of neonatal antigen-presenting cells (APCs) in children born in settings that are more traditional versus those of modern societies.

METHODS

Cord blood mononuclear cells were collected from newborns from Papua New Guinea (PNG; traditional) and Australia (modern) and compared for differences in APCs and T-cell phenotype and function.

RESULTS

Australian cord naive T cells (CD4(+)CD25(-)CD127(+) cells) showed an enhanced and more rapid proliferative response in an autologous, APC-dependent culture system, a result of differences in neonatal APCs rather than T-cell function. This included an increased capacity to process antigen and to upregulate activation markers after stimulation. In contrast, resting PNG APCs exhibited higher baseline levels of activation and inhibitory markers and were less responsive or nonresponsive to stimulation in vitro.

CONCLUSIONS

This study supports the hypothesis that prenatal environments can influence the developing immune system in utero. Children born under modern environmental conditions exhibit increased APC reactivity at birth compared with children born under traditional environmental conditions. The functionally more quiescent nature of PNG neonatal APCs might protect against the development of harmful inflammatory responses in early life.

Allergic disease in the first year of life is associated with differences in subsequent neurodevelopment and behaviour

BACKGROUND

Recent trials suggest a link between neuropsychological function, atopy and allergic disease particularly in early childhood; however the nature of this association remains unclear.

AIMS

To investigate the relationship between early allergic disease and sensitisation at 12 months of age and neurodevelopmental outcomes at 18 months.

STUDY DESIGN

Linear or binary logistic regression analysis was used to determine whether allergic diseases or sensitization at 12 months of age was a significant predictor of neurodevelopmental test scores at the 18 months.

SUBJECTS

Infants with a maternal history of allergic disease (n=324).

OUTCOME MEASURES

Allergic outcomes at 12 months of age included allergen sensitisation, eczema, IgE-mediated and food allergy, and neurodevelopmental outcomes at 18 included the Bayley Scales of Infant Toddler Development III Edition, the Achenbach Child Behaviour Checklist and the Macarthur Scales of Infant Toddler Development.

RESULTS

Children with any diagnosed allergic disease at 12 months had evidence of reduced motor scores (p=.016), and this was most apparent for a diagnosis of eczema (p=.007). Non-IgE mediated food allergy was significantly positively associated with problem Internalising Behaviours (p=.010), along with a trend for effects on the Social-Emotional composite score for IgE-Mediated food allergies (p=.052). Allergic sensitisation was not independently associated with any effects on neurodevelopmental outcomes.

CONCLUSION

This study provides evidence that an allergic phenotype in infancy is associated with effects on neurodevelopment. Further research is required to investigate the nature of this relationship.

Molecular mechanisms of IgE mediated food allergy

The purpose of this review is to collate current knowledge and recent advances in molecular mechanism behind the immediate type hypersensitivity of foods. Food allergy is a growing concern of human health in developed as well as developing countries now days. Food allergic reactions are mostly IgE mediated and also known as immediate type hypersensitivity or type I reaction. This review encompasses a wide range of molecular events during IgE mediated reactions like primary exposure of allergens, processing of allergens by antigen presenting cells, role of transcription factors like GATA-3, STAT-6, NF-AT, c-maf, c-kit and NF-κB, Treg cells, toll like receptors, cytokines and chemokines, class switch to IgE, FcεR1 receptor, priming of IgE on mast cells or basophils, signaling events followed by secondary exposure of allergens, degranulation and release of mediators like leukotrienes, histamines, prostaglandins, β-hexosaminidase and ultimately anaphylaxis. This review may be helpful to beginners as well as experts working in the field of allergy and immunology because of the stepwise explanations of molecular mechanisms involved in IgE mediated reactions.

Ontogeny of Toll-like and NOD-like receptor-mediated innate immune responses in Papua New Guinean infants

Studies addressing the ontogeny of the innate immune system in early life have reported mainly on Toll-like receptor (TLR) responses in infants living in high-income countries, with little or even no information on other pattern recognition receptors or on early life innate immune responses in children living under very different environmental conditions in less-developed parts of the world. In this study, we describe whole blood innate immune responses to both Toll-like and nucleotide-binding oligomerization domain (NOD)-like receptor agonists including the widely used vaccine adjuvant ‘alum’ in a group of Papua New Guinean infants aged 1–3 (n = 18), 4–6 (n = 18), 7–12 (n = 21) and 13–18 (n = 10) months old. Depending on the ligands and cytokines studied, different age-related patterns were found: alum-induced IL-1β and CXCL8 responses were found to significantly decline with increasing age; inflammatory (IL-6, IL-1β, IFN-γ) responses to TLR2 and TLR3 agonists increased; and IL-10 responses remained constant or increased during infancy, while TNF-α responses either declined or remained the same. We report for the first time that whole blood innate immune responses to the vaccine adjuvant alum decrease with age in infancy; a finding that may imply that the adjuvant effect of alum in pediatric vaccines could be age-related. Our findings further suggest that patterns of innate immune development may vary between geographically diverse populations, which in line with the ‘hygiene hypothesis’ particularly involves persistence of innate IL-10 responses in populations experiencing higher infectious pressure.

Increased intake of oily fish in pregnancy: effects on neonatal immune responses and on clinical outcomes in infants at 6 mo

BACKGROUND

Long-chain n-3 PUFAs found in oily fish may have a role in lowering the risk of allergic disease.

OBJECTIVE

The objective was to assess whether an increased intake of oily fish in pregnancy modifies neonatal immune responses and early markers of atopy.

DESIGN

Women (n = 123) were randomly assigned to continue their habitual diet, which was low in oily fish, or to consume 2 portions of salmon per week (providing 3.45 g EPA plus DHA) from 20 wk gestation until delivery. In umbilical cord blood samples (n = 101), we measured n-3 fatty acids, IgE concentrations, and immunologic responses. Infants were clinically evaluated at age 6 mo (n = 86).

RESULTS

Cord blood mononuclear cell (CBMC) production of interleukin (IL)-2, IL-4, IL-5, IL-10, and tumor necrosis factor-α in response to phytohemagglutinin (PHA) and of IL-2 in response to Dermatophagoides pteronyssinus allergen 1 (Derp1) was lower in the salmon group (all P ≤ 0.03). In the subgroup of CBMCs in which an allergic phenotype was confirmed in the mother or father, IL-10 production in response to Toll-like receptor 2, 3, and 4 agonists, ovalbumin, salmon parvalbumin, or Derp1 and prostaglandin E(2) production in response to lipopolysaccharide or PHA was lower in the salmon group (all P ≤ 0.045). Total IgE at birth and total IgE, incidence and severity of atopic dermatitis, and skin-prick-test positivity at 6 mo of age were not different between the 2 groups.

CONCLUSION

Oily fish intervention in pregnancy modifies neonatal immune responses but may not affect markers of infant atopy assessed at 6 mo of age. This trial is registered at clinicaltrials.gov as NCT00801502.

Breastfeeding modulates neonatal innate immune responses: a prospective birth cohort study

BACKGROUND

Neonatal Toll-like receptor (TLR) responses are biased toward Th2-polarizing responses at birth and rapidly mature toward more balanced responses during the first month of life. Postnatal TLR maturation may be guided by environmental exposure.

AIMS

To determine the environmental determinants of neonatal TLR function.

MATERIALS AND METHODS

A prospective birth cohort study was performed in 291 healthy term neonates. Mode of delivery, breastfeeding, birth month, siblings, pets and parental smoking were analyzed in relation to neonatal innate immune parameters at the age of 1 month. Whole blood concentrations of innate immune cells were measured by flow cytometry. In vitro TLR-mediated cytokine production was determined by ELISA.

RESULTS

Breastfeeding was the major determinant of neonatal innate immunity, associated with 5 (31%) of neonatal innate immune parameters, of which the association with TLR7-mediated IL-10 production was most significant (76 pg/ml in breastfed neonates vs. 293 pg/ml in formula-fed neonates, p = 0.001). Of innate immune variables, TLR3-mediated IL-12p70 production was highly associated with environmental exposures (pets, breastfeeding and mode of delivery), whereas TLR9-mediated cytokine responses were not associated with any environmental factor.

CONCLUSION

Neonatal innate immune responses are differentially modulated by environmental exposure in the first month of life. The protective effect of breastfeeding against subsequent infections and atopy might be explained by its innate immune modulatory effects in the first month of life.

Genetic variations in IL28B and allergic disease in children

Environmental changes affecting the relationship between the developing immune system and microbial exposure have been implicated in the epidemic rise of allergic disease in developed countries. While early developmental differences in T cell function are well-recognised, there is now emerging evidence that this is related to developmental differences in innate immune function. In this study we sought to examine if differences associated with innate immunity contribute to the altered immune programming recognised in allergic children. Here, we describe for the first time, the association of carriage of the T allele of the tagging single nucleotide polymorphism rs12979860 3 kb upstream of IL28B, encoding the potent innate immune modulator type III interferon lambda (IFN-λ3), and allergy in children (p = 0.004; OR 4.56). Strikingly, the association between rs12979860 genotype and allergic disease is enhanced in girls. Furthermore, carriage of the T allele at rs12979860 correlates with differences in the pro-inflammatory profile during the first five years of life suggesting this contributes to the key differences in subsequent innate immune development in children who develop allergic disease. In the context of rising rates of disease, these immunologic differences already present at birth imply very early interaction between genetic predisposition and prenatal environmental influences.

Neonatal cytokine profile in the airway mucosal lining fluid is skewed by maternal atopy

RATIONALE

Heredity from mother or father may impact differently in complex diseases, such as atopy. Maternal atopy is a stronger risk factor than paternal atopy for the development of atopy in the offspring. We hypothesized that mother's and father's atopy would have a differential imprinting on the cytokines and chemokines in the upper airway mucosal lining fluid of healthy neonates.

OBJECTIVES

To study parental atopic imprinting on the cytokines and chemokines in the upper airway mucosal lining fluid of healthy neonates.

METHODS

Eighteen cytokines and chemokines were quantified in nasal mucosal lining fluid in 309 neonates from the novel unselected Copenhagen Prospective Study on Asthma in Childhood (COPSAC) birth cohort.

MEASUREMENTS AND MAIN RESULTS

Maternal, but not paternal, atopic status (asthma, hay fever, or eczema with or without sensitization) was associated with general down-regulation of all 18 mediators assessed by principal component analysis (overall P = 0.015).

CONCLUSIONS

Maternal atopy, but not paternal atopy, showed a strong linkage with a suppressed mucosal cytokine and chemokine signature in asymptomatic neonates, suggesting imprinting by the maternal milieu in utero or perinatal life.

Dietary immunomodulatory factors in the development of immune tolerance

Emerging evidence suggests that exposures during pregnancy and the early postnatal period can modify gene expression and disease propensity. Diet is a major environmental exposure, and dietary factors, including polyunsaturated fatty acids, probiotics, oligosaccharides, antioxidants, folate, and other vitamins, have effects on immune function. Some also have been implicated in reduced risk of allergy in observational studies. Intervention trials with polyunsaturated fatty acids, probiotics, and oligosaccharides suggest preliminary but as-of-yet-unconfirmed benefits. Food allergen avoidance during pregnancy, lactation, or infancy has provided no consistent evidence in allergy prevention and is no longer recommended. Rather, there is now a focus on food allergens in tolerance induction. Specific nutrients can induce changes in gene expression during early development and have been implicated in potentially heritable "epigenetic" changes in disease predisposition. Collectively, these observations emphasize that early exposures may modify tolerance development and that further research on these exposures should remain a priority.