Interferon-gamma production by cord-blood mononuclear cells is reduced in newborns with a family history of atopic disease and is independent from cord blood IgE-levels

Grandmaternal allergen sensitization reprograms epigenetic and airway responses to allergen in second-generation offspring

Asthma susceptibility is influenced by environmental, genetic, and epigenetic factors. DNA methylation is one form of epigenetic modification that regulates gene expression and is both inherited and modified by environmental exposures throughout life. Prenatal development is a particularly vulnerable time period during which exposure to maternal asthma increases asthma risk in offspring. How maternal asthma affects DNA methylation in offspring and what the consequences of differential methylation are in subsequent generations are not fully known. In this study, we tested the effects of grandmaternal house dust mite (HDM) allergen sensitization during pregnancy on airway physiology and inflammation in HDM-sensitized and challenged second-generation mice. We also tested the effects of grandmaternal HDM sensitization on tissue-specific DNA methylation in allergen-naïve and -sensitized second-generation mice. Descendants of both allergen- and vehicle-exposed grandmaternal founders exhibited airway hyperreactivity after HDM sensitization. However, grandmaternal allergen sensitization significantly potentiated airway hyperreactivity and altered the epigenomic trajectory in second-generation offspring after HDM sensitization compared with HDM-sensitized offspring from vehicle-exposed founders. As a result, biological processes and signaling pathways associated with epigenetic modifications were distinct between lineages. A targeted analysis of pathway-associated gene expression found that Smad3 was significantly dysregulated as a result of grandmaternal allergen sensitization. These data show that grandmaternal allergen exposure during pregnancy establishes a unique epigenetic trajectory that reprograms allergen responses in second-generation offspring and may contribute to asthma risk.NEW & NOTEWORTHY Asthma susceptibility is influenced by environmental, genetic, and epigenetic factors. This study shows that maternal allergen exposure during pregnancy promotes unique epigenetic trajectories in second-generation offspring at baseline and in response to allergen sensitization, which is associated with the potentiation of airway hyperreactivity. These effects are one mechanism by which maternal asthma may influence the inheritance of asthma risk.

Pediatric Inner-City Asthma

Inner-city children with asthma are known to have high disease mortality and morbidity. Frequently, asthma in this high-risk population is difficult to control and more severe in nature. Several factors, including socioeconomic hardship, ability to access to health care, adherence to medication, exposure to certain allergens, pollution, crowd environment, stress, and infections, play an important role in the pathophysiology of inner-city asthma. Comprehensive control of home allergens and exposure to tobacco smoke, the use of immune based therapies, and school-based asthma programs have shown promising results in asthma control in this population.

Pediatric Inner-City Asthma

Inner-city children with asthma are known to have high disease mortality and morbidity. Frequently, asthma in this high-risk population is difficult to control and more severe in nature. Several factors, including socioeconomic hardship, ability to access to health care, adherence to medication, exposure to certain allergens, pollution, crowd environment, stress, and infections, play an important role in the pathophysiology of inner-city asthma. Comprehensive control of home allergens and exposure to tobacco smoke, the use of immune based therapies, and school-based asthma programs have shown promising results in asthma control in this population.

Inner-City Asthma in Children

Asthma in inner-city children is often severe and difficult to control. Residence in poor and urban areas confers increased asthma morbidity even after adjusting for ethnicity, age, and gender. Higher exposure to household pests, such as cockroaches and mice, pollutants and tobacco smoke exposure, poverty, material hardship, poor-quality housing, differences in health care quality, medication compliance, and heath care access also contribute to increased asthma morbidity in this population. Since 1991, the National Institutes of Allergy and Infectious Diseases established research networks: the National Cooperative Inner-City Asthma Study (NCICAS), the Inner-City Asthma Study (ICAS), and the Inner-City Asthma Consortium (ICAC), to improve care for this at risk population. The most striking finding of the NCICAS is the link between asthma morbidity and the high incidence of allergen sensitization and exposure, particularly cockroach. The follow-up ICAS confirmed that reductions in household cockroach and dust mite were associated with reduction in the inner-city asthma morbidity. The ICAC studies have identified that omalizumab lowered fall inner-city asthma exacerbation rate; however, the relationship between inner-city asthma vs immune system dysfunction, respiratory tract infections, prenatal environment, and inner-city environment is still being investigated. Although challenging, certain interventions for inner-city asthma children have shown promising results. These interventions include family-based interventions such as partnering families with asthma-trained social workers, providing guidelines driven asthma care as well as assured access to controller medication, home-based interventions aim at elimination of indoor allergens and tobacco smoke exposure, school-based asthma programs, and computer/web-based asthma programs.

The mechanism or mechanisms driving atopic asthma initiation: The infant respiratory microbiome moves to center stage

Developments over the last 5 to 10 years, principally from studies on comprehensively phenotyped prospective birth cohorts, have highlighted the important role of viral respiratory tract infections during infancy and early childhood, particularly those occurring against a background of pre-existing sensitization to perennial aeroallergens, in driving the development of early-onset atopic asthma. Although debate surrounding the mechanism or mechanisms governing this causal pathway remains intense, demonstration of the capacity of pretreatment with anti-IgE antibody to blunt seasonal virus-associated asthma exacerbations in children provides strong support for the underlying concept. However, emerging data appear set to further complicate this picture. Notably, a combination of culture-based studies and complementary population-wide bacterial metagenomic data suggests that parallel host-bacteria interactions during infancy might play an additional role in modulating this causal pathway, as well as contributing independently to pathogenesis. These and related issues surrounding development of immune competence during the crucial early postnatal period, when these pathways are maximally active, are discussed below.

Elucidation of pathways driving asthma pathogenesis: development of a systems-level analytic strategy

Asthma is a genetically complex, chronic lung disease defined clinically as episodic airflow limitation and breathlessness that is at least partially reversible, either spontaneously or in response to therapy. Whereas asthma was rare in the late 1800s and early 1900s, the marked increase in its incidence and prevalence since the 1960s points to substantial gene × environment interactions occurring over a period of years, but these interactions are very poorly understood (1-6). It is widely believed that the majority of asthma begins during childhood and manifests first as intermittent wheeze. However, wheeze is also very common in infancy and only a subset of wheezy children progress to persistent asthma for reasons that are largely obscure. Here, we review the current literature regarding causal pathways leading to early asthma development and chronicity. Given the complex interactions of many risk factors over time eventually leading to apparently multiple asthma phenotypes, we suggest that deeply phenotyped cohort studies combined with sophisticated network models will be required to derive the next generation of biological and clinical insights in asthma pathogenesis.

Maternal and postnatal dietary probiotic supplementation enhances splenic regulatory T helper cell population and reduces peanut allergen-induced hypersensitivity responses in mice

Neonatal to early childhood is the critical period for establishing a balance of T helper 1 (Th1) versus T helper 2 (Th2) cellular immunity within the gut, which is strongly influenced by the source and establishment of gut microflora. Probiotic administration has been shown to attenuate Th2-biased cellular immunity and predisposition to food allergies. To test this hypothesis we provided ad libitum a probiotic-supplemented (Primalac 454 Feed Grade Microbials) or control diet to lactating dams with suckling pups and weaned pups until 10 weeks of age. Weaned mice were sensitized/challenged with peanut extract, saline or adjuvant at 6, 8 and 10 weeks of age. At 3, 6, 8 and 10 weeks, fecal samples were collected for microbial analysis, while blood samples were analyzed for total plasma IgE levels. At termination (10 weeks of age), splenic T lymphocyte population subtypes were determined using FACS analysis and Th1/Th2/Th17 gene expression by PCR array. Mice given the probiotic-supplemented diet had significantly enhanced probiotic fecal counts compared to controls at 3, 6, 8 and 10 weeks. Moreover, mice fed the probiotic-supplemented diet had enhanced splenic naturally occurring T regulatory cell populations, and reduced splenic gene expression of allergic mediator IL-13 compared to controls. These results provide evidence that early probiotic supplementation may provide host protection to hypersensitivity reactions to food allergens by attenuating food allergen inflammatory responses.

Fish oil supplementation in early infancy modulates developing infant immune responses

BACKGROUND

Maternal fish oil supplementation during pregnancy has been associated with altered infant immune responses and a reduced risk of infant sensitization and eczema.

OBJECTIVE

To examine the effect of early postnatal fish oil supplementation on infant cellular immune function at 6 months of age in the context of allergic disease.

METHODS

In a double-blind randomized controlled trial (ACTRN12606000281594), 420 infants of high atopic risk received fish oil [containing 280 mg docosahexaenoic acid (DHA) and 110 mg eicosapentanoic acid (EPA)] or control oil daily from birth to 6 months. One hundred and twenty infants had blood collected at 6 months of age. Fatty acid levels, induced cytokine responses, T cell subsets and monocyte HLA-DR expression were assessed at 6 months of age. Infant allergies were assessed at 6 and 12 months of age.

RESULTS

DHA and EPA levels were significantly higher in the fish oil group and erythrocyte arachidonic acid (AA) levels were lower (all P < 0.05). Infants in the fish oil group had significantly lower IL-13 responses (P = 0.036) to house dust mite (HDM) and higher IFNγ (P = 0.035) and TNF (P = 0.017) responses to phytohaemaglutinin (PHA). Infants with relatively high DHA levels had lower Th2 responses to allergens including lower IL-13 to β-lactoglobulin (BLG) (P = 0.020), and lower IL-5 to BLG (P = 0.045).

CONCLUSIONS AND CLINICAL RELEVANCE

Postnatal fish oil supplementation increased infant n-3 polyunsaturated fatty acid (PUFA) levels and associated with lowered allergen-specific Th2 responses and elevated polyclonal Th1 responses. Our results add to existing evidence of n-3 PUFA having immunomodulatory properties that are potentially allergy-protective.

T-cell activation genes differentially expressed at birth in CD4+ T-cells from children who develop IgE food allergy

BACKGROUND

Presymptomatic immaturity in neonatal T-cell function is a consistent antecedent of allergic disease, including reduced responsiveness to polyclonal activation.

METHODS

To elucidate the underlying mechanisms, we examined for differences in T-cell gene expression in longitudinal samples collected at birth and at 1 year of age in children with (n = 30) and without IgE-mediated food allergy (n = 30). We employed a low-level soluble anti-CD3 stimulus to activate the T-cell receptor (TCR) and surveyed gene expression by DNA microarray in purified CD4(+) T-cells. Allergen-specific responses were assessed in parallel functional studies.

RESULTS

At birth, the allergic group showed a reduced number of genes up regulated in response to anti-CD3 treatment on the microarray and a reduced lympho proliferative capacity, suggesting clear differences in T-cell signalling pathways. Polymerase chain reaction (PCR) validation of candidate genes confirmed significantly lower expression of a number of genes in the allergic group including RELB, NFKB2, LIF and FAS. By 12 months of age, there were marked changes in the anti-CD3 response in all infants, culminating in upregulation of cytokine genes (IL-5, IL-13, IL-17 and IL-22). Neonatal differences were no longer apparent. Instead, the allergic group, all symptomatic by this age, showed differential expression of T-cell lineage pathways including GATA-3, MAL and FcER1 in unstimulated T-cells. Allergen stimulation induced significantly higher cytokines production (IL-5, IL-13 and IFNγ) in the allergic group.

CONCLUSION

Although transient, suboptimal neonatal T-cell activation pathways that signal through the NF-κB complex may affect the developmental transition of T-cell phenotypes in the periphery shortly after birth and may increase the risk of food allergy.

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.

Epigenetics and prenatal influences on asthma and allergic airways disease

Uterine life is arguably the most critical time in developmental programming, when environmental exposures may have the greatest potential to influence evolving fetal structure and function. There has been substantial progress in understanding the epigenetic mechanisms through which environmental exposures can permanently alter the expression of fetal genes and contribute to the increasing propensity for many complex diseases. These concepts of "developmental origins" of disease are being applied across virtually all fields of medicine, and emerging epigenetic paradigms are the likely mechanism behind the environment-driven epidemic of asthma and allergic disease. Here, we examine the epigenetic regulation of immune development and the early immune profiles that contribute to allergic risk. In particular we review new evidence that key environmental exposures, such as microbial exposure, dietary changes, tobacco smoke, and pollutants, can induce epigenetic changes in gene expression and alter disease risk. Although most of these factors have already been clearly implicated in epidemiologic studies of asthma and allergic disease, new studies investigating the mechanisms of these effects may provide new avenues for using these pathways for disease prevention.

The role of epigenetic dysregulation in the epidemic of allergic disease

The epidemic of allergic disease in early life is one of the clearest indicators that the developing immune system is vulnerable to modern environmental changes. A range of environmental exposures epidemiologically associated with allergic disease have been shown to have effects on the foetal immune function in pregnancy, including microbial burden, dietary changes and environmental pollutants. Preliminary studies now suggest that these early effects on immune development may be mediated epigenetically through a variety of processes that collectively modify gene expression and allergic susceptibility and that these effects are potentially heritable across generations. It is also possible that rising rates of maternal allergy, a recognised direct risk factor for infant allergic disease, may be further amplifying the effects of environmental changes. Whilst effective prevention strategies are the ultimate goal in reversing the allergy epidemic, the specific environmental drivers, target genes, and intracellular pathways and mechanisms of early life immune programming are still unclear. It is hoped that identifying genes that are differentially regulated in association with subsequent allergic disease will assist in identifying causal pathways and upstream contributing environmental factors. In this way, epigenetic paradigms are likely to provide valuable insights into how the early environment can be modified to more favourably drive immune development and reverse the allergic epidemic.

Food allergy: riding the second wave of the allergy epidemic

Food allergy is a substantial and evolving public health issue, recently emerging over the last 10-15 yr as a 'second wave' of the allergy epidemic. It remains unclear why this new phenomenon has lagged decades behind the 'first wave' of asthma, allergic rhinitis and inhalant sensitization. In regions like Australia, which lead the respiratory epidemic, challenge-proven IgE-mediated food allergy now affects up to 10% of infants. Although their parents were among the first generation to experience the large-scale rise in allergic diseases, disorders of oral tolerance were previously uncommon. Of further concern, this new generation appears less likely to outgrow food allergy than their predecessors with long-term implications for disease burden. Allergic disease has been linked to the modern lifestyle including changing dietary patterns, changing intestinal commensal bacteria and vehicular pollution. It is not yet known whether the rise in food allergy is a harbinger of earlier and more severe effects of these progressive environmental changes or whether additional or unrelated lifestyle factors are implicated. New studies suggest environmental factors can produce epigenetic changes in gene expression and disease risk that may be potentially heritable across generations. The rising rates of maternal allergy, a strong direct determinant of allergic risk, could also be amplifying the effect of environmental changes. Preliminary evidence that non-Caucasian populations may be even more susceptible to the adverse effects of 'westernisation' has substantial global implications with progressive urbanization of the more populous regions in the developing world. Unravelling the environmental drivers is critical to curtail a potential tsunami of allergic disease.

Clinical aspects of pediatric food allergy and failed oral immune tolerance

Food allergy seems to represent a new spectrum of disease that has elicited significant community concern and extended waiting lists for allergists and gastroenterologists alike. The apparent rise in prevalence of IgE-mediated food allergy (and associated risk of anaphylaxis) has been postulated to result from effects of a "modern lifestyle" but as yet clear environmental risk factors have not yet emerged. Family history seems to contribute to risk suggesting that gene-environment interactions will be important for identifying a subpopulation with increased susceptibility to any identified lifestyle effects. Non-IgE-mediated food allergy (including food-induced enteropathies and colitides, eosinophilic esophagitis, and Crohn's disease) with potentially similar environmental triggers resulting in diverse immune dysregulatory mechanisms. The evidence underpinning the putative rise in food allergy is discussed and potential mechanisms of disease explored. Clinical aspects of various food allergic conditions including non-IgE-mediated food allergy are outlined.

Allergic disease: understanding how in utero events set the scene

Events and exposures in pregnancy can have critical effects on fetal development with lasting implications for subsequent health and disease susceptibility. There is growing interest in how modern environmental changes influence fetal immune development and contribute to the recent epidemic of allergy and other immune disorders. Rising rates of allergic disease in early infancy, together with pre-symptomatic differences in immune function at birth, suggest that antenatal events play a predisposing role in the development of disease. A number of environmental exposures in pregnancy can modify neonatal immune function including diet, microbial exposure and maternal smoking, and there is emerging evidence from animal models that these factors may have epigenetic effects on immune gene expression and disease susceptibility. Furthermore, functional genetic polymorphisms also alter individual vulnerability to the effects of these environmental exposures, highlighting the complexity of gene-environmental interactions in this period. All these observations underscore the need for ongoing research to understand the pathogenesis and rising incidence of disease in the hope of better strategies to reverse this.

The Urban Environment and Childhood Asthma study

Childhood asthma is not distributed evenly throughout the population, and children who grow up in crowded urban neighborhoods have higher rates of asthma and experience greater morbidity because of asthma. There are several environmental and lifestyle factors associated with urban living that are suspected to promote the development of asthma, particularly in the first few years of life. Collectively, this information suggests the hypothesis that exposure in early life to adverse environmental and lifestyle factors associated with disadvantaged urban environments modifies immune development to increase the risk for allergic diseases and asthma. The Urban Environment and Childhood Asthma (URECA) birth cohort study was initiated in 2004 to test this hypothesis. The study population was recruited prenatally and consisted of 560 families from 4 urban areas who were at high risk for allergies and/or asthma on the basis of parental histories, along with an additional 49 families without atopic parents. Immune development, respiratory illnesses, and exposure to stress, indoor pollutants, microbial products, and allergens were measured prospectively, and the major study outcomes are recurrent wheeze at 3 years of age and asthma at age 7 years. This review summarizes the study design, methods, and early findings of the URECA study.

Modulation of in vivo and in vitro cytokine production over the course of pregnancy in allergic and non-allergic mothers

Cytokines secreted during pregnancy may influence immune development of the foetus. This study aimed to determine if maternal allergy alters patterns of systemic cytokine production throughout and after pregnancy. Maternal plasma cytokines and allergen-specific production of interleukin (IL)-10, IL-13 and interferon (IFN)-gamma were measured in allergic (n = 63) and non-allergic (n = 70) pregnant women who had a full set of sequential peripheral blood samples collected at 20-, 30-, 36-wk gestation and 6-wk post-partum. Maternal allergy was strictly defined by both allergen sensitization and doctor-diagnosed asthma, eczema or rhinitis. IL-13 responses to allergen were higher for allergic mothers at all time-points (20 wk: p < 0.001; 30 wk: p = 0.001; 36 wk: p < 0.001; post-partum: p < 0.001). For the non-allergic group, IL-13 levels to house dust mite decreased from 20- to 36-wk gestation (Friedman ANOVA p = 0.012) and were significantly lower at 36 wk compared with post-partum (p = 0.002). In contrast, IL-13 production by allergic mothers did not change from 20 wk through to post-partum. For both allergic and non-allergic mothers, in vitro IFN-gamma production was lower at all pregnancy time-points compared with post-partum levels. Allergic women had an increased propensity for peripheral blood allergen-specific T helper-2 responses during pregnancy, and failed to downregulate these responses in comparison with non-allergic women. This may be a factor that contributes to the increased risk of atopy in infants born to allergic mothers.

Recent findings on the pathogenesis of bronchial asthma. Part II. The role of hormonal predisposition, environmental influences and conditioning leading to bronchial asthma

In this second part of the review on the pathogenesis of asthma the hormonal factors and adverse external events are shortly reviewed which skew the balance of Th1 vs. Th2 CD4+ lymphocytes towards the latter ones and this way increase the probability of atopic diseases. Among other the role of transplacental priming, insulin, insulin-like and other growth factors, lack of the usual microbial infections in the early childhood (the so-called hygiene hypothesis), gender, diminished testosterone production, gastroesophageal reflux, adverse effects during pregnancy are discussed. A separate chapter deals with the role of central nervous system in the etiology and finally the most common allergizing and airway tissue damaging agents are listed in tabulated form.

The Urban Environment and Childhood Asthma (URECA) birth cohort study: design, methods, and study population

BACKGROUND

The incidence and morbidity of wheezing illnesses and childhood asthma is especially high in poor urban areas. This paper describes the study design, methods, and population of the Urban Environment and Childhood Asthma (URECA) study, which was established to investigate the immunologic causes of asthma among inner-city children.

METHODS AND RESULTS

URECA is an observational prospective study that enrolled pregnant women in central urban areas of Baltimore, Boston, New York City, and St. Louis and is following their offspring from birth through age 7 years. The birth cohort consists of 560 inner-city children who have at least one parent with an allergic disease or asthma, and all families live in areas in which at least 20% of the population has incomes below the poverty line. In addition, 49 inner-city children with no parental history of allergies or asthma were enrolled. The primary hypothesis is that specific urban exposures in early life promote a unique pattern of immune development (impaired antiviral and increased Th2 responses) that increases the risk of recurrent wheezing and allergic sensitization in early childhood, and of asthma by age 7 years. To track immune development, cytokine responses of blood mononuclear cells stimulated ex vivo are measured at birth and then annually. Environmental assessments include allergen and endotoxin levels in house dust, pre- and postnatal maternal stress, and indoor air nicotine and nitrogen dioxide. Nasal mucous samples are collected from the children during respiratory illnesses and analyzed for respiratory viruses. The complex interactions between environmental exposures and immune development will be assessed with respect to recurrent wheeze at age 3 years and asthma at age 7 years.

CONCLUSION

The overall goal of the URECA study is to develop a better understanding of how specific urban exposures affect immune development to promote wheezing illnesses and asthma.

Regulatory cells, cytokine pattern and clinical risk factors for asthma in infants and young children with recurrent wheeze

BACKGROUND

Several risk factors for asthma have been identified in infants and young children with recurrent wheeze. However, published literature has reported contradictory findings regarding the underlying immunological mechanisms.

OBJECTIVES

This study was designed to assess and compare the immunological status during the first 2 years in steroid-naive young children with >or= three episodes of physician-confirmed wheeze (n=50), with and without clinical risk factors for developing subsequent asthma (i.e. parental asthma or a personal history of eczema and/or two of the following: wheezing without colds, a personal history of allergic rhinitis and peripheral blood eosinophilia >4%), with age-matched healthy controls (n=30).

METHODS

Peripheral blood CD4(+)CD25(+) and CD4(+)CD25(high) T cells and their cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), GITR and Foxp3 expression were analysed by flow cytometry. Cytokine (IFN-gamma, TGF-beta and IL-10), CTLA-4 and Foxp3 mRNA expression were evaluated (real-time PCR) after peripheral blood mononuclear cell stimulation with phorbol 12-myristate 13-acetate (PMA) (24 h) and house dust mite (HDM) extracts (7th day).

RESULTS

Flow cytometry results showed a significant reduction in the absolute number of CD4(+)CD25(high) and the absolute and percentage numbers of CD4(+)CD25(+)CTLA-4(+) in wheezy children compared with healthy controls. Wheezy children at a high risk of developing asthma had a significantly lower absolute number of CD4(+)CD25(+) (P=0.01) and CD4(+)CD25(high) (P=0.04), compared with those at a low risk. After PMA stimulation, CTLA-4 (P=0.03) and Foxp3 (P=0.02) expression was diminished in wheezy children compared with the healthy children. After HDM stimulation, CTLA-4 (P=0.03) and IFN-gamma (P=0.04) expression was diminished in wheezy children compared with healthy children. High-risk children had lower expression of IFN-gamma (P=0.03) compared with low-risk and healthy children and lower expression of CTLA-4 (P=0.01) compared with healthy children.

CONCLUSIONS

Although our findings suggest that some immunological parameters are impaired in children with recurrent wheeze, particularly with a high risk for asthma, further studies are needed in order to assess their potential as surrogate predictor factors for asthma in early life.

Pregnancy IFN-gamma responses to foetal alloantigens are altered by maternal allergy and gravidity status

BACKGROUND

During pregnancy, variations in maternal-foetal cellular interactions may influence immune programming. This study was carried out to determine if maternal responses to foetal alloantigens are altered by maternal allergic disease and/or previous pregnancies.

METHODS

For this cohort study, peripheral blood was collected from allergic (n = 69) and nonallergic (n = 63) pregnant women at 20, 30, 36-week gestation and 6-week postpartum (pp). Cord blood was collected at delivery. Mixed lymphocyte reactions were used to measure maternal cytokine responses [interleukin-6 (IL-6), IL-10, IL-13 and (interferon-gamma) IFN-gamma] at each time point towards foetal mononuclear cells.

RESULTS

Maternal cytokine responses during pregnancy (20, 30 and 36 weeks) were suppressed compared to the responses at 6-week pp. The ratio of maternal IFN-gamma/IL-13 and IFN-gamma/IL-10 responses were lower during pregnancy. Allergic mothers had lower IFN-gamma responses at each time-point during pregnancy with the greatest difference in responses observed at 36-week gestation. When allergic and nonallergic women were further stratified by gravidity group, IFN-gamma responses of allergic multigravid mothers were significantly lower than nonallergic multigravid mothers during pregnancy.

CONCLUSIONS

During normal pregnancy, peripheral T-cell cytokine responses to foetal alloantigens may be altered by both allergic status of the mother and previous pregnancies. These factors could influence the cytokine milieu experienced by the foetus and will be further explored in the development of allergic disease during early life.

Effects of early cigarette smoke exposure on early immune development and respiratory disease

Exposure to tobacco constituents during early development remains a common but avoidable toxic exposure, which has been clearly linked with decreased lung growth and subsequent wheezing illness. There is also now emerging evidence that tobacco smoke can influence early immune function. This includes alterations in cytokine production by the fetoplacental unit, as detected ex vivo in cord blood, as well as in patterns of fetal mononuclear cell responses in vitro. Recent studies also suggest that the newborns of smoking mothers have altered signalling through Toll-like receptors (TLRs) that are essential for innate microbial responses. This may be implicated in the increased predisposition to infection in exposed infants. TLR-mediated innate response pathways are also believed to be important in promoting regulatory pathways that inhibit allergic immune responses. However, although a number of studies have documented associations between early cigarette smoke exposure and subsequent allergic disease, this remains controversial. This review explores the consequences of smoking on these important aspects of early development, including potential mechanisms, interactions with predisposing asthma genes and a potential role in epigenetic regulation. Although parental smoking may not be the primary factor in the changing prevalence of asthma and respiratory disease, we propose that it is an important contributor, with significant potential to interact with other genetic factors and environmental risk factors to influence disease propensity.

Reported pertussis infection and risk of atopy in 8- to 12-yr-old vaccinated and non-vaccinated children

Pertussis infection has been suspected to be a potential causal factor in the development of atopic disease because of the effect of pertussis immunization on specific IgE antibodies. Although several studies found a positive association between pertussis infection and atopic disorders, this relationship has not yet been studied in a population stratified by vaccination status. To assess the association between pertussis infection and atopic disorders in pertussis-unvaccinated children and in pertussis-vaccinated children. Using data from a previously conducted study on the relationship between the diphtheria-tetanus-pertussis-(inactivated) poliomyelitis vaccination in the first year of life and atopic disorders, the study population of 1872 8-12 yr old was divided into children pertussis-unvaccinated and children pertussis-vaccinated in the first year of life. Within each group, the association between pertussis infection and atopic disorders (both as reported by the parents) was assessed. In the unvaccinated group, there were no significant associations between pertussis infection and atopic disorders. In the vaccinated group, all associations between pertussis infection and atopic disorders were positive, the associations with asthma [odds ratio (OR) = 2.24, 95% confidence interval (CI(95%)): 1.36-3.70], hay fever (OR = 2.35, CI(95%): 1.46-3.77) and food allergy (OR = 2.68, CI(95%): 1.48-4.85) being significant. There was a positive association between pertussis infection and atopic disorders in the pertussis vaccinated group only. From the present study, it cannot be concluded whether this association is causal or due to reverse causation.

Fetal cord blood: aspects of heightened immune responses

Neonatal immune responses have been associated with the development of atopy in childhood. We assessed in cord blood mononuclear cells (CBMC) whether increased allergen/mitogen-induced lymphoproliferation (LP) is associated with pro-allergic Th2 cytokine IL-13 or Th1 cytokine IFN-gamma secretion. We determined whether LP to one allergen is related to heightened lymphocyte function to other allergens/mitogen. CBMC from 135 neonates were stimulated with house dust mite (Derf1), cockroach, ovalbumin, or mitogen. LP to one allergen was associated with significantly increased LP to other allergens/mitogen. Increased Derf1-LP was associated with increased Derf1-induced IL-13 secretion (r = 0.21, p = 0.01). After adjusting for neonatal gender, race, and maternal smoking, Derf1-LP remained associated with Derf1-IL-13 (OR 3.08, 95% CI 1.56-6.10). Increased mitogen-induced proliferation was associated with increased mitogen-induced IL-13 secretion (r = 0.37, p < 0.001). For some individuals, a predisposition to a heightened immune response is already evident at birth. Whether this phenotype results in atopy in childhood warrants further investigation.

Low IFN-gamma production in the first year of life as a predictor of wheeze during childhood

BACKGROUND

Diminished cytokine production in infancy has been associated with an increased risk for allergen sensitization and early-life wheeze.

OBJECTIVE

We sought to assess the effect of low cytokine production in the first year of life on the development of wheeze through age 13 years.

METHODS

Cytokine production (IFN-gamma and IL-2) by mitogen-stimulated mononuclear cells was determined from peripheral blood samples (9.4 months, n = 118) in a subset of healthy infants enrolled in the Tucson Children's Respiratory Study. The occurrence of wheeze during the previous year was ascertained at ages 2, 3, 6, 8, 11, and 13 years by means of questionnaire. Relative risk for wheeze was computed with generalized estimating equations.

RESULTS

The risk of wheezing between 2 and 13 years was significantly higher for subjects with low 9-month IFN-gamma production (relative risk, 2.29; 95% CI, 1.35-3.89) and borderline significant for those with intermediate IFN-gamma production (relative risk, 1.59; 95% CI, 0.95-2.68) compared with those who produced high levels of IFN-gamma (P value for linear association = .002). Nine-month IL-2 production was unrelated to wheeze. In relation to complex wheezing phenotypes, 9-month IFN-gamma production was inversely related to toddler wheeze (occurring only before age 6 years, P = .03) and chronic wheeze (occurring before and after age 6 years, P = .007) but not school-age wheeze (occurring only after age 6 years, P = .06).

CONCLUSION

The results suggest that characteristics of the immune system present during the first year of life can anticipate the likelihood of development of episodes of airway obstruction characterized by wheezing.

CLINICAL IMPLICATIONS

Immune susceptibility to asthma is established very early during postnatal life.

Maternal allergy influences the proliferation of neonatal T cells expressing CCR4, CXCR5 or CD103

BACKGROUND

Elevated proliferative response to allergen in cord blood mononuclear cells (CBMCs) is related to subsequent allergy development of the neonate and has been suggested as a screening marker for high allergy risk.

OBJECTIVE

To characterize the proliferating cells in CBMCs from a neonatal group influenced by maternal allergy compared with a control group without known allergic heredity.

METHODS

CBMCs were stimulated with bovine beta-lactoglobulin (beta-LG) and proliferation was analysed by radioactive thymidine incorporation and expressed both as the traditional stimulation index (SI) and SI corrected by eliminating non-specific proliferation. After beta-LG combined with endotoxin stimulation, cellular expression of IL-4 and IFN-gamma mRNA was determined by quantitative RT-PCR and adhesion as well as chemokine receptors were analysed by three-colour flow cytometry in proliferating T cells (CD3+ Ki-67+).

RESULTS

The percentage of CCR4+ cells correlated weakly with concurrent IL-4 expression (r(S)=0.5, P<0.05), while CXCR3 correlated strongly with IFN-gamma expression (r(S)=0.83, P<0.001). In the allergy risk group, the percentage of proliferating T cells expressing CCR4 or integrin alphaE (CD103) was significantly reduced compared with the control group, while CXCR5 and the corrected SI were relatively increased (CCR4: P=0.01; integrin alphaE: P=0.03; CXCR5: P=0.04; SI: P=0.04).

CONCLUSION

Our results implied delayed maturation of immune functions involved in cellular migration, cell-cell interaction and immunoregulatory functions in neonates with hereditary allergy risk. The alterations observed in this subject group suggested that the corrected SI as well as proliferation of CCR4+, CXCR5+ or CD103+ T cells in allergen-stimulated CBMCs might serve as early screening markers for allergy risk.

Consumption of omega3-fatty acids during perinatal life: role in immuno-modulation and allergy prevention

Epidemiological data suggest that dietary factors may have a role in recent increases of the prevalence of allergic diseases. One food-related component might be the reduced consumption of omega3-polyunsaturated fatty acids observed especially in the Western societies; yet, clinical trials supplementing omega3-fatty acids to adults with established allergies and bronchial asthma have generally been disappointing. However, it is known that the immature immune system is highly susceptible to immuno-modulatory environmental conditions particularly in the pre- and postnatal period. This review discusses the immuno-modulatory effects of omega3-fatty acids supplementation in the perinatal life phase on the immune system of the child. Evidence exists that perinatal omega3-fatty acid exposure affects T-cells and antigen presenting cells of the neonates likely due to altered eicosanoid metabolism. Although animal experiments strongly suggest a role of maternal omega3-fatty acid intake on allergic immune responses in the offspring, the beneficial effect of omega3-fatty acid supplementation has been studied in a small number of clinical trials. In these studies perinatal supplementation had some positive effects on distinct clinical phenotypes of the atopic syndrome. However, more studies are needed to fully explore the opportunity of perinatal immuno-modulation.

Maternal smoking in pregnancy: do the effects on innate (toll-like receptor) function have implications for subsequent allergic disease?

Subtle increases in immaturity of immune function in early infancy have been implicated in the rising susceptibility to allergic disease, particularly relative impairment of type 1 interferon (IFN)-γ responses in the neonatal period. Although genetic predisposition is a clear risk factor, the escalating rates of allergic disease in infancy suggest that environmental factors are also implicated. We previously showed that maternal smoking in pregnancy may impair neonatal IFN-γ responses. Our more recent studies now indicate that this common avoidable toxic exposure is also associated with attenuation of innate immune function, with attenuated Toll-like receptor (TLR)-mediated microbial responses (including TLR-2, -3, -4, and -9 responses). Most notably, the effects were more marked if the mothers were also allergic. In this review, we discuss the significance of these observations in the context of the emerging hypothesis that variations in TLR function in early life may be implicated in allergic propensity. There is now growing evidence that many of the key pathways involved in subsequent T-cell programming and regulation (namely, antigen-presenting cells and regulatory T cells) rely heavily on microbe-driven TLR activation for maturation and function. Factors that influence the function and activity of these innate pathways in early life may contribute to the increasing predisposition for allergic disease. Although "cleaner" environments have been implicated, here we explore the possibility that other common environmental exposures (such as maternal smoking) could also play a role.

Relationship between maternal and child cytokine responses to allergen and phytohaemagglutinin 2 years after delivery

Little is known at present about the relation between parental and child cytokine profiles. In this study we aimed to investigate the cytokine profile of 2-year-old children and their corresponding mothers, 2 years after delivery. Peripheral blood mononuclear cells (PBMC) were isolated from IgE-sensitized (n=15) and non-esitized (n=58) 2-year-old children and their mothers. The responses to ovalbumin, cat and phytohaemagglutinin (PHA) were investigated using the enzyme-linked immunospot (ELISpot) technique. Interferon (IFN)-gamma-, interleukin (IL)-4-, IL-10- and IL-12-producing cells were enumerated. At 2 years of age, IgE-sensitized children exhibited increased numbers of IL-4-producing cells in response to PHA and also showed an increase in IL-10- and IL-12-producing cells to allergen that was more pronounced in response to ovalbumin than to cat. A statistically significant increase in the numbers of IFN-gamma-, IL-10- and IL-12-producing cells to the allergens, but not to PHA, was found in the mothers of IgE-sensitized children irrespective of their own atopic status. IgE levels and cytokine responses were correlated between the mothers and their children, indicating that cytokine responses to both allergen and PHA might be governed by genetic factors. We speculate that the increased cytokine response to allergen, as opposed to the allergic status of the mother, might be a better predictor and/or a risk factor for the child to develop IgE-sensitization in early life.

Association between neopterin in cord blood, urinary neopterin in early childhood and the development of atopic dermatitis, asthma and hay fever

It is generally accepted that the increased prevalence of atopic disease is due to a disturbed balance of T-helper (Th)1/Th2-type immunity. Upon stimulation by the Th1-type cytokine interferon (IFN)-gamma, human monocytes/macrophages release large amounts of neopterin. Thus, the determination of neopterin concentrations is an indirect measure of the levels of IFN-gamma and allows us to monitor Th1-type immune response. We evaluated whether neopterin concentrations in the neonatal cord blood could be a valuable marker predicting atopic disease in early childhood and whether there is a difference in actually determined urinary neopterin concentrations in children with and without atopic disease. Five hundred and five children born during 1997-1999 were enrolled, with cord blood neopterin data available at birth. The International study of asthma and allergies in childhood (ISAAC) questionnaire was used to assess the prevalence of wheezy bronchitis (asthma), atopic dermatitis and allergic rhinitis. Morning urinary samples were collected and urinary neopterin concentration was measured by high-pressure liquid chromatography. By the average age of 6 yr, the prevalence of atopic disease in the last 12 months was 31%. There was no significant correlation between cord blood and urinary neopterin concentrations at age 6 yr, and between cord blood neopterin and later atopic disease. Urinary neopterin concentrations were significant lower in children with a family history of atopic disease (p = 0.02). In this study, cord blood neopterin concentration was not a predictor for atopic disease in early childhood. Family history of atopic disease was associated with lower urinary neopterin levels at age 6 yr, which might mirror a Th1/Th2 imbalance.

Prenatal lipopolysaccharide-exposure prevents allergic sensitization and airway inflammation, but not airway responsiveness in a murine model of experimental asthma

BACKGROUND

Epidemiological evidence underlines the impact of prenatal environmental factors on the development of postnatal allergies. In this regard an inverse correlation between lipopolysaccharide (LPS) exposure and development of childhood allergy has been found.

OBJECTIVE

To assess the impact of prenatal LPS exposure on the development of postnatal respiratory allergies in a mouse model of experimental asthma.

METHODS

Female BALB/c mice were exposed to LPS before conception and during pregnancy. Several weeks after birth offspring were sensitized to ovalbumin (OVA) followed by aerosol allergen challenges.

RESULTS

Prenatal, maternal LPS-exposure enhanced neonatal IFN-gamma, but not IL-4 and IL-2 production. OVA sensitization of prenatally LPS-exposed mice was accompanied by a marked suppression in anti-OVA IgG1 and IgE as well as unchanged IgG2a antibody responses, paralleled by a significant reduction in IL-5 and IL-13 levels following mitogenic stimulation of splenic leucocytes. Assessment of bronchoalveolar lavage fluids following allergen challenges revealed a marked reduction in eosinophils and macrophages in these mice. Surprisingly, development of airway hyper-responsiveness, a hallmark of bronchial asthma, was not affected.

CONCLUSION

This study provides first experimental evidence that LPS may already operate in prenatal life in order to modulate the development of allergies in the offspring.

Immune dysregulation in allergic respiratory disease: the role of T regulatory cells

Although earlier research focused on the role of the polarity of T helper cell signalling as the defining factor in immune responses, it is now recognised that other cells with regulatory properties have a more key role. It has been recently proposed that allergic disease may result from an inappropriate balance between regulatory cells (including but not limited to CD4+ CD25+ T regulatory cells) and T helper type 2 (Th2) effector cells. In the airways, a number of other cells also have important regulatory effects on local immune responses, including epithelial cells and airway dendritic cells (DC). Allergic respiratory disease appears to be the culmination of both local epithelial dysfunction and generalised immune dysregulation resulting in Th2 propensity (atopic predisposition). Although these processes are related they also appear to occur independently. This review examines evolving models of allergy pathogenesis, including the newly recognised role of diverse groups of regulatory cells. Increasing rates of allergic disease (and other immune diseases) suggest that environmental changes may be having fundamental effects on common regulatory pathways. Understanding these influences and their mechanism of action could lead to strategies to prevent disease.

Ontogeny of the Allergic Inflammatory Response

The ability to produce allergic responses begins early in fetal life along with the development of other elements of the immune system. Among the most interesting questions related to the development of allergic disease are whether the fetus in utero commonly is exposed to sufficient allergen to induce IgE production and how much the mother's immune responses affect the developing fetal immune system. After birth, it seems that many factors, including the frequency and severity of infections and the timing and intensity of allergen and animal exposures, continue to influence immune development.

Gene-environment interaction effects on the development of immune responses in the 1st year of life

Asthma is a common disease that results from both genetic and environmental risk factors. Children attending day care in the 1st year of life have lower risks for developing asthma, although the mechanism for this "day care" effect is largely unknown. We investigated the interactions between day care exposure in the 1st 6 mo of life and genotypes for 72 polymorphisms at 45 candidate loci and their effects on cytokine response profiles and on the development of atopic phenotypes in the 1st year of life in the Childhood Onset of Asthma (COAST) cohort of children. Six interactions (at four polymorphisms in three loci) with "day care" that had an effect on early-life immune phenotypes were significant at P<.001. The estimated false-discovery rate was 33%, indicating that an estimated four P values correspond to true associations. Moreover, the "day care" effect at some loci was accounted for by the increased number of viral infections among COAST children attending day care, whereas interactions at other loci were independent of the number of viral infections, indicating the presence of additional risk factors associated with day care environment. This study identified significant gene-environment interactions influencing the early patterning of the immune system and the subsequent development of asthma and highlights the importance of considering environmental risk factors in genetic analyses.

Impaired interleukin (IL)-4-associated generation of CCR4-expressing T cells in neonates with hereditary allergy risk

Reduced microbial exposure in early life may contribute to the increase of atopic diseases in 'westernized' societies but the underlying mechanisms remain elusive. The objective of this study was to examine how exposure to bacterial lipopolysaccharide (LPS) during early antigen encounter might influence the maturation of neonatal lymphoid cells, and to define possible differences in this respect between neonates with high risk of allergy due to a family history (FH(+)) and controls with no apparent hereditary risk (FH(-)). Cord blood mononuclear cells from the FH(+) or FH(-) group were stimulated with pure LPS or beta-lactoglobulin (beta-LG) in the presence of LPS. T cell expression of chemokine receptors CCR4 and CXCR3 was determined by flow cytometry and reverse transcription-polymerase chain reaction (RT-PCR). Cellular expression of interleukin (IL)-4 was analysed by quantitative RT-PCR, whereas interferon (IFN)-gamma was analysed by both quantitative RT-PCR and immunoassay. Stimulation with LPS, or beta-LG together with LPS, induced up-regulation of CCR4 (P < 0.05) and CXCR3 (P < 0.05). For CCR4, such up-regulation was related to the level of IL-4 produced by the same T cells (r(S) = 0.49, P = 0.03), while CXCR3 expression was negatively correlated with the IL-4 levels (r(S) = -0.56, P = 0.02). Compared with the FH(-) group, the FH(+) group showed a significantly lower capacity for generation of CCR4(+) T cells (mean percentage of total T cells: FH(+), 2.42%versus FH(-), 5.74%; P < 0.01), whereas induction of CXCR3 and IFN-gamma did not differ significantly between the two groups. When the immune system in early life encounters antigen together with LPS, the T cell potential for compartmentalized interaction with other immune cells might be increased by elevated CCR4- and CXCR3-expression levels. In neonates at hereditary allergy risk, this putative homeostatic mechanism could theoretically be jeopardized due to decreased up-regulation of CCR4. Conversely, Th1 responses to antigen in the presence of LPS did not appear to be reduced compared with controls.

Prenatal factors associated with the development of eczema in the first year of life

Prenatal factors have been implicated in childhood eczema, but the relationship between maternal cytokine production during pregnancy and infant eczema is unknown. Non-selected women in their third trimester were enrolled in the Tucson Infant Immune Study. Data from three sources were used to define MD-eczema: parent-completed illness questionnaires at age 2, 3, 4, 6 and 9 months regarding physician-seen eczema, parent-completed questionnaires at 12 months regarding physician-diagnosed eczema, and medical record reviews. Blood samples were taken from mothers during their third trimester and from the umbilical cord at birth. Maternal peripheral blood mononuclear cells and cord blood mononuclear cells were stimulated with ConA/PMA, and supernatants were assayed for IFN-gamma and IL-4, -5, -10, and -13. Of 364 children, 28% were seen by a physician for eczema by 1 yr of age. After adjustment for potential confounders using logistic regression, the odds for development of eczema in infancy were significantly higher when mothers had active eczema in pregnancy (OR, 2.46, CI 1.0-5.8, p <0.042) and when mothers were in the highest tertile of serum IgE production (OR 2.28, CI 1.2-4.4, p <0.013). Colds in the third trimester were associated with lower odds of eczema (OR 0.32, CI 0.16-0.63, p <0.001). Our findings from this cohort study suggest that in utero factors, including maternal IgE, colds, and eczema, may influence the risk of infant eczema.

Current and emerging nonsteroidal anti-inflammatory therapies targeting specific mechanisms in asthma and allergy

Today inhaled corticosteroids (ICS) are regarded as the first-line controller anti-inflammatory treatment in the management of asthma. However, there is an increasing awareness of the risk of long-term adverse effects of ICS and that asthma is not only an organ-specific disease but also a systemic and small airway disease. This thinking has called for systemic treatment alternatives to treat asthma targeting more disease-specific mechanisms without influencing normal physiologic functions. Blocking of disease-specific mediators is a mechanism utilized by anti-leukotrienes and anti-immunoglobulin E treatment, each proven to be effective in both asthma and allergic rhinitis.Different cytokine-modifying strategies have been tested in clinical trials with variable results, some disappointing and some encouraging. Anti-interleukin (IL)-5 monoclonal antibody treatment effectively reduces the number of eosinophils locally in the airways and in peripheral blood in asthmatic patients. Unfortunately, this marked effect on eosinophils was not associated with an improvement in bronchial hyperresponsiveness and/or symptoms. Clinical trials with a recombinant soluble IL-4 receptor have been somewhat more successful at improving asthma control and allowing reduction of ICS therapy in asthma. Treatment with recombinant IL-12 had an effect on bronchial hyperresponsiveness and eosinophilic response, but was associated with unacceptable adverse effects. Other interesting cytokine-modulating treatments include those targeting IL-9, IL-10, IL-12 and IL-13.Immune-modulating treatment with bacterial antigens represents another strategy, originating from the hypothesis that some bacterial infections guide the immune system towards a T helper (Th) type 1 immune response. Mycobacterium vaccae, Bacille Calmette-Guerin (BCG) and immunostimulatory DNA sequences have all been tested in clinical trials, with encouraging results. Future asthma and allergy treatment will probably include not only one but also two or more disease-modifying agents administered to the same patient.

Nuclear factor kappa B activation in human cord blood mononuclear cells

The immunologic signals participating in immune responses early in life have not been completely elucidated. Regarding the characterization of neonatal cells, little is known concerning the activity of transcription factor nuclear factor kappa B (NF-kappaB), which regulates inflammatory genes and cytokine production. The aim of this study was to characterize NF-kappaB activation in cord blood mononuclear cells (CBMC). We analyzed the potential association of NF-kappaB activity with lymphocyte proliferation and influences on cytokine secretion in the early immune system. To determine the contribution of a disease whereby inheritance may impact neonatal immunity, we assessed the influence of maternal allergic disease on NF-kappaB regulation and cytokine secretion. CBMC from healthy newborns were isolated and stimulated with mitogen (n = 28). Nuclear extracts were analyzed by electrophoretic mobility shift assay, cytokine secretion by ELISA. FISH analysis excluded relevant maternal contamination of CBMC. All samples showed a positive lymphoproliferative response, and NF-kappaB activity was both increased and decreased after mitogen stimulation. Increased NF-kappaB activation was significantly associated with decreased TNF-alpha secretion (median 6.1 versus 50.3 pg/mL) in unstimulated CBMC. Mitogen stimulation resulted in increased NF-kappaB activity with a trend to increased IL-13 production. Maternal allergic disease was associated with higher TNF-alpha (median 982 versus 173 pg/mL) and IL-13 secretion (median 1328 versus 1120 pg/mL) after mitogen stimulation. Together, NF-kappaB activity is differentially activated in cord blood and associated with a distinct cytokine pattern. Whether differential NF-kappaB activity in cord blood is related to the subsequent development of immune diseases requires further investigation.

Maternally delivered nutritive allergens in cord blood and in placental tissue of term and preterm neonates

BACKGROUND

The proliferation of cord blood mononuclear cells in response to nutritive and inhalant allergens implies intrauterine exposure with resulting T cell priming. However, the mechanisms triggering these fetal allergen-specific immune responses are incompletely understood.

METHODS

We studied the placental release of endogenous beta-lactoglobulin (BLG) and ovalbumin (OVA) by the use of an open ex vivo placental perfusion model. Preterm and term placentas were obtained immediately after delivery to recover functionally active fetal and maternal circulations. Fetal and maternal perfusate samples were collected throughout the perfusion experiments with medium. Matched cord blood samples were collected separately. All samples were tested for the presence of OVA and BLG by allergen-specific ELISAs.

RESULTS

In 16 out of 19 placentas, the nutritive allergens could be detected both in fetal and maternal perfusate samples. Fetal wash out levels of the allergens BLG and OVA from the placental tissue of preterm and term deliveries were observed in traces and up to 44.4 and 2.6 ng/mL, respectively. In cord blood of preterm and term neonates, BLG and OVA could be detected at concentrations up to 16.7 and 5 ng/mL, respectively.

CONCLUSION

These findings provide direct evidence for the release of tiny amounts of nutritive allergens from placental tissue indicating diaplacental allergen transfer and fetal exposure to nutritive allergens in vivo.