Adoptively transferred allergen-specific T cells cause maternal transmission of asthma risk

Mechanisms for initiation of food allergy by skin pre-disposed to atopic dermatitis

Food allergy can be life-threatening and often develops early in life. In infants and children, loss-of-function mutations in skin barrier genes associate with food allergy. In a mouse model with skin barrier mutations (Flakey Tail, FT+/- mice), topical epicutaneous sensitization to a food allergen peanut extract (PNE), an environmental allergen Alternaria alternata (Alt) and a detergent induce food allergy and then an oral PNE-challenge induces anaphylaxis. Exposures to these allergens and detergents can occur for infants and children in a household setting. From the clinical and preclinical studies of neonates and children with skin barrier mutations, early oral exposure to allergenic foods before skin sensitization may induce tolerance to food allergens and thus protect against development of food allergy. In the FT+/- mice, oral food allergen prior to skin sensitization induce tolerance to food allergens. However, when the skin of FT+/- pups are exposed to a ubiquitous environmental allergen at the time of oral consumption of food allergens, this blocks the induction of tolerance to the food allergen and the mice can then be skin sensitized with the food allergen. The development of food allergy in neonatal FT+/- mice is mediated by altered skin responses to allergens with increases in skin expression of interleukin 33, oncostatin M and amphiregulin. The development of neonate food allergy is enhanced when born to an allergic mother, but it is inhibited by maternal supplementation with α-tocopherol. Moreover, preclinical studies suggest that food allergen skin sensitization can occur before manifestation of clinical features of atopic dermatitis. Thus, these parameters may impact design of clinical studies for food allergy, when stratifying individuals by loss of skin barrier function or maternal atopy before offspring development of atopic dermatitis.

Preclinical models of maternal asthma and progeny outcomes: a scoping review

There is an increased risk of adverse perinatal outcomes in the ∼17% of women with asthma during pregnancy. The mechanisms linking maternal asthma and adverse outcomes are largely unknown, but reflect joint effects of genetics and prenatal exposure to maternal asthma. Animal models are essential to understand the underlying mechanisms independent of genetics and comorbidities, and enable safe testing of interventions. This scoping review aimed to explore the methodology, phenotype, characteristics, outcomes and quality of published studies using preclinical maternal asthma models. MEDLINE (PubMed), Embase (Elsevier) and Web of Science were systematically searched using previously validated search strings for maternal asthma and for animal models. Two reviewers independently screened titles and abstracts, full texts, and then extracted and assessed the quality of each study using the Animal Research: Reporting of In Vivo Experiments (ARRIVE) 2.0 guidelines. Out of 3618 studies identified, 39 were eligible for extraction. Most studies were in rodents (86%) and all were models of allergic asthma. Maternal and progeny outcomes included airway hyperresponsiveness, airway resistance, inflammation, lung immune cells, lung structure and serum immunoglobulins and cytokines. Experimental design (100%), procedural details (97%) and rationale (100%) were most often reported. Conversely, data exclusion (21%), blinding (18%) and adverse events (8%) were reported in a minority of studies. Species differences in physiology and timing of development, the use of allergens not relevant to humans and a lack of comparable outcome measures may impede clinical translation. Future studies exploring models of maternal asthma should adhere to the minimum core outcomes set presented in this review.

The impact of maternal asthma on the fetal lung: Outcomes, mechanisms and interventions

Maternal asthma affects up to 17% of pregnancies and is associated with adverse infant, childhood, and adult respiratory outcomes, including increased risks of neonatal respiratory distress syndrome, childhood wheeze and asthma. In addition to genetics, these poor outcomes are likely due to the mediating influence of maternal asthma on the in-utero environment, altering fetal lung and immune development and predisposing the offspring to later lung disease. Maternal asthma may impair glucocorticoid signalling in the fetus, a process critical for lung maturation, and increase fetal exposure to proinflammatory cytokines. Therefore, interventions to control maternal asthma, increase glucocorticoid signalling in the fetal lung, or Vitamin A, C, and D supplementation to improve alveologenesis and surfactant production may be beneficial for later lung function. This review highlights potential mechanisms underlying maternal asthma and offspring respiratory morbidities and describes how pregnancy interventions can promote optimal fetal lung development in babies of asthmatic mothers.

Dysbiotic lung microbial communities of neonates from allergic mothers confer neonate responsiveness to suboptimal allergen

In humans and animals, offspring of allergic mothers have increased responsiveness to allergens. This is blocked in mice by maternal supplementation with α-tocopherol (αT). Also, adults and children with allergic asthma have airway microbiome dysbiosis with increased Proteobacteria and may have decreased Bacteroidota. It is not known whether αT alters neonate development of lung microbiome dysbiosis or whether neonate lung dysbiosis modifies development of allergy. To address this, the bronchoalveolar lavage was analyzed by 16S rRNA gene analysis (bacterial microbiome) from pups of allergic and non-allergic mothers with a basal diet or αT-supplemented diet. Before and after allergen challenge, pups of allergic mothers had dysbiosis in lung microbial composition with increased Proteobacteria and decreased Bacteroidota and this was blocked by αT supplementation. We determined whether intratracheal transfer of pup lung dysbiotic microbial communities modifies the development of allergy in recipient pups early in life. Interestingly, transfer of dysbiotic lung microbial communities from neonates of allergic mothers to neonates of non-allergic mothers was sufficient to confer responsiveness to allergen in the recipient pups. In contrast, neonates of allergic mothers were not protected from development of allergy by transfer of donor lung microbial communities from either neonates of non-allergic mothers or neonates of αT-supplemented allergic mothers. These data suggest that the dysbiotic lung microbiota is dominant and sufficient for enhanced neonate responsiveness to allergen. Importantly, infants within the INHANCE cohort with an anti-inflammatory profile of tocopherol isoforms had an altered microbiome composition compared to infants with a pro-inflammatory profile of tocopherol isoforms. These data may inform design of future studies for approaches in the prevention or intervention in asthma and allergic disease early in life.

β-Glucosylceramides and Tocopherols Regulate Development and Function of Dendritic Cells

In humans and mice, offspring of allergic mothers are predisposed to development of allergy. In mice, allergic mothers have elevated β-glucosylceramides (βGlcCers) that are transported to the fetus via the placenta and to offspring via milk. The elevated βGlcCers increase the number of fetal liver CD11c+CD11b+ dendritic cells (DCs) and offspring allergen-induced lung eosinophilia. These effects are modifiable by maternal dietary supplementation with the plant-derived lipids α-tocopherol and γ-tocopherol. It is not known whether βGlcCers and tocopherols directly regulate development of DCs. In this study, we demonstrated that βGlcCers increased development of GM-CSF-stimulated mouse bone marrow-derived DCs (BMDCs) in vitro without altering expression of costimulatory molecules. This increase in BMDC numbers was blocked by α-tocopherol and potentiated by γ-tocopherol. Furthermore, βGlcCers increased protein kinase Cα (PKCα) and PKCδ activation in BMDCs that was blocked by α-tocopherol. In contrast, γ-tocopherol increased BMDC PKCα and PKCδ activation and enhanced the βGlcCer-induced increase in PKCδ activation in a DC subset. Ag processing per DC was minimally enhanced in βGlcCer-treated BMDCs and not altered ex vivo in lung DCs from pups of allergic mothers. Pups of allergic mothers had an increased proportion of CD11b+CD11c+ subsets of DCs, contributing to enhanced stimulation of T cell proliferation ex vivo. Thus, βGlcCer, which is both necessary and sufficient for development of allergic predisposition in offspring of allergic mothers, directly increased development and PKC activation in BMDCs. Furthermore, this was modifiable by dietary tocopherols. This may inform design of future studies for the prevention or intervention in asthma and allergic disease.

The association between prenatal F2-isoprostanes and child wheeze/asthma and modification by maternal race

BACKGROUND

Childhood wheeze, asthma, and allergic rhinitis are common and likely have prenatal origins. Oxidative stress is associated with respiratory disease, but the association of oxidative stress during the prenatal period with development of respiratory and atopic disease in childhood, particularly beyond the infancy period, is unknown. This study aims to investigate associations between prenatal oxidative stress, measured by maternal urinary F2-isoprostanes, and child respiratory outcomes, including effect modification by maternal race.

METHODS

We prospectively studied Black (n = 717) and White (n = 363) mother-child dyads. We measured F2-isoprostanes in 2nd-trimester urine (ng/mg-creatinine). At approximately age 4, we obtained parent report of provider-diagnosed asthma (ever), current wheeze, current asthma (diagnosis, symptoms and/or medication), and current allergic rhinitis (current defined as previous 12 months). We used multivariable logistic regression to estimate adjusted odds ratios (aOR) and 95% confidence intervals (95%CI) per interquartile range (IQR) increase in F2-isoprostane concentration, controlling for confounders. We examined modification by maternal race using interaction terms.

RESULTS

The prevalence of provider-diagnosed asthma and current wheeze, asthma and allergic rhinitis was 14%, 19%, 15%, and 24%, respectively. Median (IQR) F2-isoprostane levels were 2.1 (1.6, 2.9) ng/mg-creatinine. Associations between prenatal F2-isoprostanes and provider-diagnosed asthma, current wheeze, and current asthma were modified by maternal race. Results were strongest for current wheeze (aOR [95%CI]: 1.55 [1.16, 2.06] for White; 0.98 [0.78, 1.22] for Black; p-interaction = 0.01). We observed no association between F2-isoprostanes and allergic rhinitis.

CONCLUSION

Prenatal urinary F2-isoprostanes may be a marker associated with childhood wheeze/asthma in certain populations. Research is needed to understand underlying mechanisms and racial differences.

Asthma, allergy and vitamin E: Current and future perspectives

Asthma and allergic disease result from interactions of environmental exposures and genetics. Vitamin E is one environmental factor that can modify development of allergy early in life and modify responses to allergen after allergen sensitization. Seemingly varied outcomes from vitamin E are consistent with the differential functions of the isoforms of vitamin E. Mechanistic studies demonstrate that the vitamin E isoforms α-tocopherol and γ-tocopherol have opposite functions in regulation of allergic inflammation and development of allergic disease, with α-tocopherol having anti-inflammatory functions and γ-tocopherol having pro-inflammatory functions in allergy and asthma. Moreover, global differences in prevalence of asthma by country may be a result, at least in part, of differences in consumption of these two isoforms of tocopherols. It is critical in clinical and animal studies that measurements of the isoforms of tocopherols be determined in vehicles for the treatments, and in the plasma and/or tissues before and after intervention. As allergic inflammation is modifiable by tocopherol isoforms, differential regulation by tocopherol isoforms provide a foundation for development of interventions to improve lung function in disease and raise the possibility of early life dietary interventions to limit the development of lung disease.

Sensitisation patterns and allergy outcomes in pregnant women living in the urban area

Background

Worldwide, allergy affects more than one billion people, with particularly rising prevalence in industrialised areas. Specifically, young adults appear to be predominantly targeted for an allergy diagnosis. Allergic diseases in pregnancy are mainly pre-existing but could also occur de novo. The immunological changes while pregnant, with increased Th2 lymphocyte activity, can facilitate allergen sensitisation.

Objective

The aim of this study was to evaluate the pattern of specific IgE (sIgE) sensitisation to common inhalant and food allergens in pregnancy, and assess its relationship to self-reported allergic disease.

Methods

We assessed 200 pregnant women, aged 20–38 years (mean age = 29 years), participant of ELMA (Epigenetic Hallmark of Maternal Atopy and Diet) study, living in a metropolitan area, with no pregnancy associated metabolic complications, for total IgE and allergen specific IgE to 20 allergens.

Results

48% of pregnant women were sensitised to at least one allergen, at a cut-off point of 0.35 kU/L and they were assigned as atopic. However 42% in atopic group were not reporting any allergic disease. The most common inhalant allergens were: pollen (24.5%) and animal dander (23.5%). The most common food allergens were: cow’s milk (5.5%) and apples (4.5%). 7.5% of women reported asthma, 21.5% allergic rhinitis, 11.5% atopic dermatitis and 18.5% food allergy. 8.5% of were taking medication for asthma or allergies. Atopic dermatitis had the highest tendency to become more severe during pregnancy. Total IgE values were significantly higher in atopic women.

Conclusions

Allergic sensitisation is a common phenomenon in pregnancy. Some sensitisations could be asymptomatic. Further studies should investigate if sensitisation in mothers confers risks for immune alterations in their children.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-021-00547-0.

β-Glucosylceramide From Allergic Mothers Enhances Offspring Responsiveness to Allergen

In animals and humans, offspring of allergic mothers have increased responsiveness to allergen and the allergen-specificity of the offspring can be different than that of the mother. In our preclinical models, the mother's allergic responses influence development of the fetus and offspring by elevating numbers of cells in dendritic cell subsets. A major question is the identity of maternal factors of allergic mothers that alter offspring development of responsiveness to allergen. Lipids are altered during allergic responses and lipids are transported to the fetus for growth and formation of fetal membranes. We hypothesized that pro-inflammatory lipids, that are elevated in allergic mothers, are transported to the fetus and regulate fetal immune development. We demonstrate in this report that there was a significant 2-fold increase in β-glucosylceramides (βGlcCer) in allergic mothers, the fetal liver and her offspring. The βGlcCer were transported from mother's plasma, across the placenta, to the fetus and in breastmilk to the offspring. Administration of βGlcCer to non-allergic mothers was sufficient for offspring responses to allergen. Importantly, maternal administration of a clinically relevant pharmacological inhibitor of βGlcCer synthase returned βGlcCer to normal levels in the allergic mothers and her offspring and blocked the offspring increase in dendritic cell subsets and offspring allergen responsiveness. In summary, allergic mothers had increased βGlcCer that was transported to offspring and mediated increases in offspring DCs and responsiveness to allergen. These data have a significant impact on our understanding of mechanisms for development of allergies in offspring of allergic mothers and have the potential to lead to novel interventions that significantly impact risk for allergic disease early in life.

The Potential of IgG to Induce Murine and Human Thymic Maturation of IL-10+ B Cells (B10) Revealed in a Pilot Study

Regulatory B (B10) cells can control several inflammatory diseases, including allergies; however, the origin of peripheral B10 cells is not fully understood, and the involvement of primary lymphoid organs (PLOs) as a primary site of maturation is not known. Here, using a murine model of allergy inhibition mediated by maternal immunization with ovalbumin (OVA), we aimed to evaluate whether B10 cells can mature in the thymus and whether IgG can mediate this process. Female mice were immunized with OVA, and offspring thymus, bone marrow, spleen, lung, and serum samples were evaluated at different times and after passive transfer of purified IgG or thymocytes. A translational approach was implemented using human nonatopic thymus samples, nonatopic peripheral blood mononuclear cells (PBMCs), and IgG from atopic or nonatopic individuals. Based on the expression of CD1d on B cells during maturation stages, we suggest that B10 cells can also mature in the murine thymus. Murine thymic B10 cells can be induced in vitro and in vivo by IgG and be detected in the spleen and lungs in response to an allergen challenge. Like IgG from atopic individuals, human IgG from nonatopic individuals can induce B10 cells in the infant thymus and adult PBMCs. Our observations suggest that B10 cells may mature in the thymus and that this mechanism may be mediated by IgG in both humans and mice. These observations may support the future development of IgG-based immunoregulatory therapeutic strategies.

Maternal asthma is associated with persistent changes in allergic offspring antibody glycosylation

BACKGROUND

Maternal asthma during pregnancy is considered an environmental risk factor for asthma development in children. Immunoglobulin G (IgG) antibodies that are transferred from the mother to the fetus are known to act in a pro- or anti-inflammatory manner depending on their glycosylation status.

OBJECTIVE

Using a mouse model, we examined how maternal allergic airway inflammation during pregnancy influenced offspring experimental asthma severity, as well as maternal and offspring serum IgG antibody glycosylation patterns. Additionally, the effects of maternal and offspring exposure to the same or different allergens were investigated.

METHODS

Female mice were either sham sensitized or sensitized to casein (CAS) or ovalbumin (OVA) before mating. Subsequently, allergic lung inflammation was induced in pregnant dams via aerosol allergen challenge (sham, CAS or OVA). After weaning, pups were subjected to an experimental asthma protocol using OVA. Asn-297 IgG glycosylation was analysed in maternal and offspring serum.

RESULTS

When mothers and offspring were sensitized to the same allergen (OVA-OVA), offspring had more severe experimental asthma. This was evidenced by altered antibody concentrations, increased bronchoalveolar lavage inflammatory cell influx and decreased lung tissue and lung draining lymph node regulatory T cell percentages. When mothers and offspring were sensitized to different allergens (CAS-OVA), this phenotype was no longer observed. Additionally, maternal serum from allergic mothers had significantly higher levels of pro-inflammatory IgG1, shown by decreased galactosylation and sialylation at the Asn-297 glycosylation site. Similar glycosylation patterns were observed in the serum of adult allergic offspring from allergic mothers.

CONCLUSIONS AND CLINICAL RELEVANCE

We observed a strong association between maternal experimental asthma during pregnancy, increased offspring airway inflammation and pro-inflammatory IgG glycosylation patterns in mothers and offspring. IgG glycosylation is not a standard measurement in the clinical setting, and we argue that it may be an important parameter to include in future clinical studies.

Influences of Maternal Factors Over Offspring Allergies and the Application for Food Allergy

The prevalence of food allergy has been steadily rising worldwide with the highest incidence noted among younger children, and increasingly recognized as a growing public concern. The first known ingestion of foods often causes allergic reaction, suggesting that sensitization of offspring with food allergens may occur during pregnancy and/or through breastfeeding. This creates a milieu that shapes the neonatal immune responses to these allergens. However, the effects of maternal allergen exposure and maternal sensitization with allergens on development of allergies in offspring remain controversial. This review discusses recent advances from human data in our understanding of how maternal factors, namely, food allergens, allergen-specific immunoglobulins, cytokines, genetics, and environmental factors transferred during pregnancy or breastfeeding influence offspring allergies and how such effects may be applicable to food allergy. Based on information obtained from mouse models of asthma and food allergy, the review also dissects the mechanisms by which maternal factors, including the impact of immune complexes, transforming growth factor-β, vitamin A, and regulatory T-cell responses, contribute to the induction of neonatal tolerance vs. development of allergic responses to maternally transferred allergens.

Maternal allergic asthma during pregnancy alters fetal lung and immune development in sheep: potential mechanisms for programming asthma and allergy

KEY POINTS

Experimental maternal allergic asthma in sheep provides an experimental model in which to test impacts on progeny. Fetuses from allergic asthmatic ewes had fewer surfactant-producing cells in lungs. A greater proportion of lymphocytes from thymus were CD44 positive in fetuses from allergic asthmatic ewes than in controls. These changes to fetal development might contribute to poor neonatal lung function and increased risk of allergy seen in offspring of pregnancies complicated by asthma.

ABSTRACT

Asthma is prevalent in pregnancy and increases the risk of disease in offspring, including neonatal respiratory distress and childhood asthma and allergy, but the mechanisms are not understood. We hypothesized that fetal lung structure and immune phenotype in late gestation fetal sheep would be impaired in our sheep model of maternal allergic asthma during pregnancy. Singleton-bearing ewes were either sensitized before pregnancy to house dust mite (HDM, allergic, n = 7) or were non-allergic (control, n = 5). The ewes were subsequently subjected to repeated airway challenges with HDM (allergic group) or saline (control group) throughout gestation. Tissues were collected at 140 ± 1 days gestational age (term, ∼147 days). The density of type II alveolar epithelial cells (surfactant protein C-immunostained) in the lungs was 30% lower in fetuses from allergic ewes than in controls (P < 0.001), but tissue-to-air space ratio and numbers of leucocytes and macrophages were not different between groups. The proportion of CD44⁺ lymphocytes in the fetal thymus was 3.5-fold higher in fetuses from allergic ewes than in control ewes (P = 0.043). Fewer surfactant-producing type II alveolar epithelial cells may contribute to the increased risk of neonatal respiratory distress in infants of asthmatic mothers, suggesting that interventions to promote lung maturation could improve their neonatal outcomes. If the elevated lymphocyte expression of CD44 persists postnatally, this would confer greater susceptibility to allergic diseases in progeny of asthmatic mothers, consistent with observations in humans. Further experiments are needed to evaluate postnatal phenotypes of progeny and investigate potential interventions.

Next Generation Sequencing for Long Non-coding RNAs Profile for CD4+ T Cells in the Mouse Model of Acute Asthma

Background and Aims

Although long non-coding RNAs (lncRNAs) have been linked to many diseases including asthma, little is known about lncRNA transcriptomes of CD4⁺ T cells in asthma. The present study aimed to explore the lncRNAs profile in the CD4⁺T cells from the mouse model of acute asthma.

Methods

Next generation sequencing for lncRNAs and mRNAs was performed on CD4+ T cells from asthma and control mice. Gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) pathway analyses were performed to predict the functions and signal pathways for the aberrant lncRNAs. The selected lncRNAs were further measured using quantitative real-time PCR (polymerase chain reaction) and observed in the fluorescence in situ hybridization (FISH). The lncRNA–mRNA co-expression network was constructed via Pearson’s correlation coefficient and Cytoscape 3.6.

Results

Next generation sequencing revealed 36 up-regulated lncRNAs and 98 down-regulated lncRNAs in acute asthma compared with controls. KEGG pathway analysis showed that cytokine-cytokine receptor interaction had the highest enrichment scores. A co-expression network was constructed in which 23 lncRNAs and 301 mRNAs altered formed a total of 12424 lncRNA and mRNA pairs. To validate the RNA sequencing results, we measured the 4 different lncRNAs using qPCR. The lncRNA fantom3_9230106C11 was significantly reduced in CD4+ T cells of asthma. Bioinformatics analysis showed that lncRNA fantom3_9230106C11 had the potential to interact with many miRNAs and transcription factors related to Th2 differentiation.

Conclusion

This study provided the first evidence for different expression of lncRNAs of CD4+T cells in asthma and may serve as a template for further, larger functional in-depth analyses regarding asthma molecular lncRNAs.

Maternal immunization downregulates offspring TCD4 regulatory cells (Tregs) thymic maturation without implications for allergy inhibition

The regulation of offspring allergy development mediated by maternal immunization was evidenced by several groups, and this mechanism seems to involve the induction of regulatory T cells (Tregs) on offspring. Here, we aimed to evaluate whether the effect of maternal immunization on offspring Tregs occurs as a result of peripheral or central modulation. Briefly, C57BL/6 female mice were immunized with OVA in Alum or Alum alone and boosted with OVA in saline or saline only after 10 and 20 days. Non-immunized offspring serum, thymus and spleen were evaluated at 3 or 20 days old, and some groups of pups were submitted to neonatal OVA-immunization protocol for the subsequent evaluation of antibody production and allergic response. Our experimental protocol could be validated because maternal OVA-immunization inhibited offspring allergic response as evidenced by the suppression of offspring IgE production and allergic lung inflammation. Interestingly, maternal immunization reduced the frequency of offspring thymic Tregs with an opposite effect on spleen Tregs. Furthermore, after neonatal immunization, the frequency of lung-infiltrated Tregs was also augmented on offspring from immunized mothers. In conclusion, maternal OVA-immunization can inhibit the thymic maturation of offspring Tregs without implications on peripheral Tregs induction and allergy inhibition.

Mechanism for initiation of food allergy: Dependence on skin barrier mutations and environmental allergen costimulation

BACKGROUND

Mechanisms for the development of food allergy in neonates are unknown but clearly linked in patient populations to a genetic predisposition to skin barrier defects. Whether skin barrier defects contribute functionally to development of food allergy is unknown.

OBJECTIVE

The purpose of the study was to determine whether skin barrier mutations, which are primarily heterozygous in patient populations, contribute to the development of food allergy.

METHODS

Mice heterozygous for the filaggrin (Flg)ft and Tmem79ma mutations were skin sensitized with environmental and food allergens. After sensitization, mice received oral challenge with food allergen, and then inflammation, inflammatory mediators, and anaphylaxis were measured.

RESULTS

We define development of inflammation, inflammatory mediators, and food allergen-induced anaphylaxis in neonatal mice with skin barrier mutations after brief concurrent cutaneous exposure to food and environmental allergens. Moreover, neonates of allergic mothers have increased responses to suboptimal sensitization with food allergens. Importantly, responses to food allergens by these neonatal mice were dependent on genetic defects in skin barrier function and on exposure to environmental allergens. ST2 blockade during skin sensitization inhibited the development of anaphylaxis, antigen-specific IgE, and inflammatory mediators. Neonatal anaphylactic responses and antigen-specific IgE were also inhibited by oral pre-exposure to food allergen, but interestingly, this was blunted by concurrent pre-exposure of the skin to environmental allergen.

CONCLUSION

These studies uncover mechanisms for food allergy sensitization and anaphylaxis in neonatal mice that are consistent with features of human early-life exposures and genetics in patients with clinical food allergy and demonstrate that changes in barrier function drive development of anaphylaxis to food allergen.

Pre-birth origins of allergy and asthma

Allergy is a chronic disease that can develop as early as infancy, suggesting that early life factors are important in its aetiology. Variable associations between size at birth, a crude marker of the fetal environment, and allergy have been reported in humans and require comprehensive review. Associations between birth weight and allergy are however confounded in humans, and we and others have therefore begun exploring the effects of early life events on allergy in experimental models. In particular, we are using ovine models to investigate whether and how a restricted environment before birth protects against allergy, whether methyl donor availability contributes to allergic protection in IUGR, and why maternal asthma during pregnancy is associated with increased risks of allergic disease in children. We found that experimental intrauterine growth restriction (IUGR) in sheep reduced cutaneous responses to antigens in progeny, despite normal or elevated IgE responses. Furthermore, maternal methyl donor supplementation in late pregnancy partially reversed effects of experimental IUGR, consistent with the proposal that epigenetic pathways underlie some but not all effects of IUGR on allergic susceptibility. Ovine experimental allergic asthma with exacerbations reduces relative fetal size in late gestation, with some changes in immune populations in fetal thymus suggestive of increased activation. Maternal allergic asthma in mice also predisposes progeny to allergy development. In conclusion, these findings in experimental models provide direct evidence that a perturbed environment before birth alters immune system development and postnatal function, and provide opportunities to investigate underlying mechanisms and develop and evaluate interventions.

Maternal house dust mite exposure during pregnancy enhances severity of house dust mite-induced asthma in murine offspring

BACKGROUND

Atopic status of the mother and maternal exposure to environmental factors are associated with increased asthma risk. Moreover, animal models demonstrate that exposure to allergens in strongly sensitized mothers influences offspring asthma development, suggesting that in utero exposures can influence offspring asthma. However, it is unclear whether maternal exposure to common human allergens such as house dust mite (HDM), in the absence of additional adjuvants, influences offspring asthma development.

OBJECTIVE

We sought to determine whether maternal HDM exposure influences asthma development in offspring.

METHODS

Pregnant female mice were exposed to PBS or HDM during pregnancy. Using offspring of PBS- or HDM-exposed mothers, the magnitude of HDM or Aspergillus fumigatus (AF) extract-induced airway hyperresponsiveness (AHR), airway inflammation, immunoglobulin production, T_H2-associated cytokine synthesis, and pulmonary dendritic cell activity was assessed.

RESULTS

Compared with offspring of PBS-exposed mothers, offspring of HDM-exposed mothers demonstrate increased AHR, airway inflammation, T_H2 cytokine production, and immunoglobulin levels and a modest decrease in the phagocytic capacity of pulmonary macrophage populations following HDM exposure. Increased sensitivity to AF-induced airway disease was not observed. Offspring of HDM-exposed B-cell-deficient mothers also demonstrated increased HDM-induced AHR, suggesting that transfer of maternal immunoglobulins is not required.

CONCLUSIONS

Our data demonstrate that maternal exposure to HDM during pregnancy increases asthma sensitivity in offspring in an HDM-specific manner, suggesting that vertical transmission of maternal immune responses may be involved. These findings have important implications for regulation of asthma risk, and suggest that exposure to HDM in the developed world may have underappreciated influences on the overall prevalence of allergic asthma.

Downregulation of L-arginine metabolism in dendritic cells induces tolerance to exogenous antigen

Dendritic cells (DC) are potential tools for therapeutic applications and several strategies to generate tolerogenic DCs are under investigation. When activated by cytokines and microbial products, DCs express mediators that modulate immune responses. In this regard, the metabolites generated by the activities of inducible nitric oxide synthase (iNOS) and arginase in DCs seem to play important roles. Here, we evaluated the effects of adoptive transfer of DCs generated in vitro from bone marrow precursors (BMDC) modulated with L-NAME (Nω-nitro-L-arginine methyl ester) and NOHA (NG-Hydroxy-L-arginine), inhibitors of iNOS and arginase, respectively, upon the immune response of the wild type (BALB/c) and OVA-TCR transgenic (DO11.10) mice. The modulation with L-NAME increased CD86 expression in BMDC, whereas treatment with NOHA increased both CD80 and CD86 expression. Adoptive transfer of either L-NAME- or NOHA-modulated BMDCs to BALB/c mice reduced the plasma levels of ovalbumin-specific antibody as well as proliferation and cytokine secretion in cultures of spleen cells in comparison adoptive transfer of non-modulated DCs. Conversely, transfer of both modulated and non-modulated BMDCs had no effect on immune response of DO11.10 mice. Together, these results show that the treatment with iNOS and Arg inhibitors leads to increased expression of co-stimulatory molecules in DCs, and provides evidences that L-arginine metabolism may be an important therapeutic target for modulating immune responses in inflammatory disorders.

γ-Tocopherol supplementation of allergic female mice augments development of CD11c+CD11b+ dendritic cells in utero and allergic inflammation in neonates

γ-Tocopherol increases responses to allergen challenge in allergic adult mice, but it is not known whether γ-tocopherol regulates the development of allergic disease. Development of allergic disease often occurs early in life. In clinical studies and animal models, offspring of allergic mothers have increased responsiveness to allergen challenge. Therefore, we determined whether γ-tocopherol augments development of allergic responses in offspring of allergic female mice. Allergic female mice were supplemented with γ-tocopherol starting at mating. The pups from allergic mothers developed allergic lung responses, whereas pups from saline-treated mothers did not respond to allergen challenge. The γ-tocopherol supplementation of allergic female mice increased the numbers of eosinophils twofold in the pup bronchoalveolar lavage and lungs after allergen challenge. There was also about a twofold increase in pup lung CD11b(+) subsets of CD11c(+) dendritic cells and in numbers of these dendritic cells expressing the transcription factor IRF4. There was no change in several CD11b(-) dendritic cell subsets. Furthermore, maternal supplementation with γ-tocopherol increased the number of fetal liver CD11b(+)CD11c(+) dendritic cells twofold in utero. In the pups, γ-tocopherol increased lung expression of the inflammatory mediators CCL11, amphiregulin, activin A, and IL-5. In conclusion, maternal supplementation with γ-tocopherol increased fetal development of subsets of dendritic cells that are critical for allergic responses and increased development of allergic responses in pups from allergic mothers. These results have implications for supplementation of allergic mothers with γ-tocopherol in prenatal vitamins.

Maternal influences over offspring allergic responses

Asthma occurs as a result of complex interactions of environmental and genetic factors. Clinical studies and animal models of asthma indicate offspring of allergic mothers have increased risk of development of allergies. Environmental factors including stress-induced corticosterone and vitamin E isoforms during pregnancy regulate the risk for offspring development of allergy. In this review, we discuss mechanisms for the development of allergic disease early in life, environmental factors that may impact the development of risk for allergic disease early in life, and how the variation in global prevalence of asthma may be explained, at least in part, by some environmental components.

α-Tocopherol supplementation of allergic female mice inhibits development of CD11c+CD11b+ dendritic cells in utero and allergic inflammation in neonates

α-Tocopherol blocks responses to allergen challenge in allergic adult mice, but it is not known whether α-tocopherol regulates the development of allergic disease. Development of allergic disease often occurs early in life. In clinical studies and animal models, offspring of allergic mothers have increased responsiveness to allergen challenge. Therefore, we determined whether α-tocopherol blocked development of allergic responses in offspring of allergic female mice. Allergic female mice were supplemented with α-tocopherol starting at mating. The pups from allergic mothers developed allergic lung responses, whereas pups from saline-treated mothers did not respond to the allergen challenge, and α-tocopherol supplementation of allergic female mice resulted in a dose-dependent reduction in eosinophils in the pup bronchoalveolar lavage and lungs after allergen challenge. There was also a reduction in pup lung CD11b(+) dendritic cell subsets that are critical to development of allergic responses, but there was no change in several CD11b(-) dendritic cell subsets. Furthermore, maternal supplementation with α-tocopherol reduced the number of fetal liver CD11b(+) dendritic cells in utero. In the pups, there was reduced allergen-induced lung mRNA expression of IL-4, IL-33, TSLP, CCL11, and CCL24. Cross-fostering pups at the time of birth demonstrated that α-tocopherol had a regulatory function in utero. In conclusion, maternal supplementation with α-tocopherol reduced fetal development of subsets of dendritic cells that are critical for allergic responses and reduced development of allergic responses in pups from allergic mothers. These results have implications for supplementation of allergic mothers with α-tocopherol.

Epigenetic regulation of asthma and allergic disease

Epigenetics of asthma and allergic disease is a field that has expanded greatly in the last decade. Previously thought only in terms of cell differentiation, it is now evident the epigenetics regulate many processes. With T cell activation, commitment toward an allergic phenotype is tightly regulated by DNA methylation and histone modifications at the Th2 locus control region. When normal epigenetic control is disturbed, either experimentally or by environmental exposures, Th1/Th2 balance can be affected. Epigenetic marks are not only transferred to daughter cells with cell replication but they can also be inherited through generations. In animal models, with constant environmental pressure, epigenetically determined phenotypes are amplified through generations and can last up to 2 generations after the environment is back to normal. In this review on the epigenetic regulation of asthma and allergic diseases we review basic epigenetic mechanisms and discuss the epigenetic control of Th2 cells. We then cover the transgenerational inheritance model of epigenetic traits and discuss how this could relate the amplification of asthma and allergic disease prevalence and severity through the last decades. Finally, we discuss recent epigenetic association studies for allergic phenotypes and related environmental risk factors as well as potential underlying mechanisms for these associations.

Asthma and allergic diseases in pregnancy a review

Asthma and allergic disorders can affect the course and outcome of pregnancy. Pregnancy itself may also affect the course of asthma and related diseases. Optimal management of these disorders during pregnancy is vital to ensure the welfare of the mother and the baby.

Specific pharmacological agents for treatment of asthma or allergic diseases must be cautiously selected and are discussed here with respect to safety considerations in pregnancy. Although most drugs do not harm the fetus, this knowledge is incomplete. Any drug may carry a small risk that must be balanced against the benefits of keeping the mother and baby healthy. The goals and principles of management for acute and chronic asthma, rhinitis, and dermatologic disorders are the same during pregnancy as those for asthma in the general population.

Diagnosis of allergy during pregnancy should mainly consist of the patient's history and in vitro testing.

The assured and well-evaluated risk factors revealed for sensitization in mother and child are very limited, to date, and include alcohol consumption, exposure to tobacco smoke, maternal diet and diet of the newborn, drug usage, and insufficient exposure to environmental bacteria. Consequently, the recommendations for primary and secondary preventive measures are also very limited in number and verification.

Prenatal allergen exposures prevent allergen-induced sensitization and airway inflammation in young mice

BACKGROUND

Immune-modulation such as tolerance induction appears to be an upcoming concept to prevent development of atopic diseases. Pregnancy might present a critical period for preventing allergic sensitization of the progeny. We investigated the effect of maternal allergen exposures during pregnancy on allergen-induced sensitization and airway inflammation in the offspring in a murine model.

METHODS

BALB/c mice were exposed to aerosolized ovalbumin (OVA) three times per week from day 7 of pregnancy until delivery (day 0). Offspring were systemically sensitized by six intraperitoneal injections with OVA between postnatal days 21 and 35, prior to airway allergen challenges on days 48, 49, and 50. Analyses were performed on day 52. To examine long-lasting effects of maternal OVA exposures some offspring were sensitized between days 115 and 129; analyses took place on day 147.

RESULTS

Compared to maternal placebo exposures, maternal OVA exposures suppressed OVA-specific IgE serum levels and inhibited development of allergen-induced airway inflammation in the OVA-sensitized offspring on both days 52 and 147. This protective effect was associated with a shift from a predominant Th2 immune response toward a predominant production of the cytokines IFN-γ and IL-10. Further, maternal OVA exposures were associated with development of CD25(+) Foxp3(+) regulatory T cells (T(regs)) in the OVA-sensitized offspring. Depletion of T(regs) or neutralization of IL-10 prior to allergen sensitization re-established OVA-induced sensitization and eosinophilic airway inflammation in the OVA-sensitized offspring.

CONCLUSIONS

In our model, maternal allergen exposures during pregnancy prevented later allergen-mediated sensitization and airway inflammation by allergen-specific tolerance induction in the offspring.

Maternal peanut consumption provides protection in offspring against peanut sensitization that is further enhanced when co-administered with bacterial mucosal adjuvant

The aims of the present study were to assess whether protection against peanut (PN) sensitization can be conferred by maternal PN consumption alone and if so, whether protection was increased by mucosal adjuvant co-administration. Mice were fed with low dose of either PN or PN with cholera toxin (CT) preconceptionally, and during pregnancy and lactation. Offspring serum PN-specific immunoglobulins and cellular responses by splenocytes and mesenteric lymph node (MLN) cells were determined after an active PN sensitization protocol. Milk was collected from lactating mothers of 11-21-day-old pups for evaluation of PN-specific immunoglobulin levels. We found that offspring of PN fed mothers exhibited lower PN-specific IgE levels and reduced PN-stimulated splenocyte and MLN cells cytokine secretion than offspring of non PN fed mothers. CT co-administration with PN enhanced these responses.. Milk from mothers fed PN and CT, but not PN alone preconceptionally and during pregnancy and lactation contained markedly and significantly increased levels of both peanut-specific IgG2a and IgA. Our study demonstrated that maternal feeding of PN alone had a protective effect against PN sensitization of the progeny, which was enhanced by co-administration of a mucosal adjuvant. Increased levels of PN-specific IgG2a and/or IgA in milk were seen when PN and CT were administered together, suggesting that transmission of maternal immunoglobulins may play a role in the observed protection.

Macroparasites, innate immunity and immunoregulation: developing natural models

Innate immune receptors carry out surveillance for infection threats and are a proximal controller of the threshold and intensity at which inflammatory responses occur. As such, they are a natural focus for understanding how inflammatory immune reactivity is regulated. This review highlights how little data there are relating to the effect of macroparasites on systemic innate receptor responses. The idea is developed that studies on innate immune function in wild animals exposed to a natural profile of infections, including macroparasites, might be a valuable model in which to test hypotheses about the ultimate cause of aberrant inflammation in modern human populations.

Immunotoxicologic analysis of maternal transmission of asthma risk

Asthma has origins in early life. Epidemiological studies show that maternal, more than paternal, asthma significantly increases a child's risk of developing the disease. Experimental animal models exist which reproduce the increased susceptibility to asthma seen in human studies, and allow analysis of immunotoxic mechanisms that may contribute to neonatal allergy. In addition to maternal asthma, chemically-induced skin contact hypersensitivity or exposure during pregnancy of non-allergic females to certain environmental agents, e.g., air pollution particles, can also result in increased susceptibility to asthma in their offspring. We review here experimental models of maternal transmission of asthma risk, the progress to date in identifying mechanisms, and potential directions for future research.

Transplacental passage of interleukins 4 and 13?

The mechanisms by which prenatal events affect development of adult disease are incompletely characterized. Based on findings in a murine model of maternal transmission of asthma risk, we sought to test the role of the pro-asthmatic cytokines interleukin IL-4 and -13. To assess transplacental passage of functional cytokines, we assayed phosphorylation of STAT-6, a marker of IL-4 and -13 signaling via heterodimeric receptor complexes which require an IL-4 receptor alpha subunit. IL-4 receptor alpha−/− females were mated to wild-type males, and pregnant females were injected with supraphysiologic doses of IL-4 or 13. One hour after injection, the receptor heterozygotic embryos were harvested and tissue nuclear proteins extracts assayed for phosphorylation of STAT-6 by Western blot. While direct injection of embryos produced a robust positive control, no phosphorylation was seen after maternal injection with either IL-4 or -13, indicating that neither crossed the placenta in detectable amounts. The data demonstrate a useful approach to assay for transplacental passage of functional maternal molecules, and indicate that molecules other than IL-4 and IL-13 may mediate transplacental effects in maternal transmission of asthma risk.

Asthma and allergic diseases in pregnancy a review

Asthma and allergic disorders can affect the course and outcome of pregnancy. Pregnancy itself may also affect the course of asthma and related diseases. Optimal management of these disorders during pregnancy is vital to ensure the welfare of the mother and the baby.Specific pharmacological agents for treatment of asthma or allergic diseases must be cautiously selected and are discussed here with respect to safety considerations in pregnancy. Although most drugs do not harm the fetus, this knowledge is incomplete. Any drug may carry a small risk that must be balanced against the benefits of keeping the mother and baby healthy. The goals and principles of management for acute and chronic asthma, rhinitis, and dermatologic disorders are the same during pregnancy as those for asthma in the general population.Diagnosis of allergy during pregnancy should mainly consist of the patient's history and in vitro testing.The assured and well-evaluated risk factors revealed for sensitization in mother and child are very limited, to date, and include alcohol consumption, exposure to tobacco smoke, maternal diet and diet of the newborn, drug usage, and insufficient exposure to environmental bacteria. Consequently, the recommendations for primary and secondary preventive measures are also very limited in number and verification.

Maternal transmission of asthma risk

Maternal asthma significantly increases the risk of asthma in offspring, but the mechanisms remain poorly defined. We review animal models used to study the maternal effect, focusing on a murine model developed in our laboratory. Mother mice rendered allergic to ovalbumin produce offspring that are more susceptible to allergic sensitization, seen as airway hyperresponsiveness and allergic airway inflammation after a sensitization protocol, which has minimal effects on newborns from normal mothers. Mechanistic analyses identify a role for interleukin-4 (based on pre-mating injection of neutralizing antibodies), dendritic cells and allergen-specific T cells (based on adoptive transfer experiments). Other maternal exposures (e.g. pollutant exposure and non-pulmonary allergy) can increase asthma susceptibility in offspring. This observation implies that the maternal transmission of asthma represents a final common pathway to various types of inflammatory stimuli. Identification of the shared molecular mechanisms in these models may allow better prevention and therapy. Current knowledge, gaps in knowledge and future directions are discussed.

Maternal transmission of resistance to development of allergic airway disease

Parental phenotype is known to influence the inheritance of atopic diseases, such as allergic asthma, with a maternal history being a more significant risk factor for progeny than paternal history. We hypothesized that recall Th1- or Th2-type immune responses during pregnancy would result in transfer of maternal factors that would differentially impact development of immune responsiveness in offspring. Following weaning, susceptibility and severity of allergic airway disease (a murine model of human asthma) was evaluated in progeny, disease being elicited by immunization with OVA-Al(OH)(3) and challenge with aerosolized OVA. We found that progeny of mothers with Th1-biased immunity to OVA subjected to recall aerosol challenge during pregnancy had reduced levels of Ag-specific IgE and airway eosinophilia compared with progeny of mothers with Th2-biased immunity to OVA or naive mothers. Interestingly, progeny of mothers with Th1-type immunity to a heterologous albumin, BSA, were not protected from developing OVA-induced allergic airway disease. These findings demonstrated that maternal transfer of protection from development of allergic airway disease to offspring in this model of maternal Th1-type immunity was Ag specific.

Maternal allergic contact dermatitis causes increased asthma risk in offspring

Background

Offspring of asthmatic mothers have increased risk of developing asthma, based on human epidemiologic data and experimental animal models. The objective of this study was to determine whether maternal allergy at non-pulmonary sites can increase asthma risk in offspring.

Methods

BALB/c female mice received 2 topical applications of vehicle, dinitrochlorobenzene, or toluene diisocyanate before mating with untreated males. Dinitrochlorobenzene is a skin-sensitizer only and known to induce a Th1 response, while toluene diisocyanate is both a skin and respiratory sensitizer that causes a Th2 response. Both cause allergic contact dermatitis. Offspring underwent an intentionally suboptimal protocol of allergen sensitization and aerosol challenge, followed by evaluation of airway hyperresponsiveness, allergic airway inflammation, and cytokine production. Mothers were tested for allergic airway disease, evidence of dermatitis, cellularity of the draining lymph nodes, and systemic cytokine levels. The role of interleukin-4 was also explored using interleukin-4 deficient mice.

Results

Offspring of toluene diisocyanate but not dinitrochlorobenzene-treated mothers developed an asthmatic phenotype following allergen sensitization and challenge, seen as increased Penh values, airway inflammation, bronchoalveolar lavage total cell counts and eosinophilia, and Th2 cytokine imbalance in the lung. Toluene diisocyanate treated interleukin-4 deficient mothers were able to transfer asthma risk to offspring. Mothers in both experimental groups developed allergic contact dermatitis, but not allergic airway disease.

Conclusion

Maternal non-respiratory allergy (Th2-skewed dermatitis caused by toluene diisocyanate) can result in the maternal transmission of asthma risk in mice.

Pulmonary exposure to particles during pregnancy causes increased neonatal asthma susceptibility

Maternal immune responses can promote allergy development in offspring, as shown in a model of increased susceptibility to asthma in babies of ovalbumin (OVA)-sensitized and -challenged mother mice. We investigated whether inflammatory responses to air pollution particles (diesel exhaust particles, DEP) or control "inert" titanium dioxide (TiO(2)) particles are enhanced during pregnancy and whether exposure to particles can cause increased neonatal susceptibility to asthma. Pregnant BALB/c mice (or nonpregnant controls) received particle suspensions intranasally at Day 14 of pregnancy. Lung inflammatory responses were evaluated 48 hours after exposure. Offspring of particle- or buffer-treated mothers were sensitized and aerosolized with OVA, followed by assays of airway hyperresponsiveness (AHR) and allergic inflammation (AI). Nonpregnant females had the expected minimal response to "inert" TiO(2). In contrast, pregnant mice showed robust and persistent acute inflammation after both TiO(2) and DEP. Genomic profiling identified genes differentially expressed in pregnant lungs exposed to TiO(2). Neonates of mothers exposed to TiO(2) (and DEP, but not PBS) developed AHR and AI, indicating that pregnancy exposure to both "inert" TiO(2) and DEP caused increased asthma susceptibility in offspring. We conclude that (1) pregnancy enhances lung inflammatory responses to otherwise relatively innocuous inert particles; and (2) exposures of nonallergic pregnant females to inert or toxic environmental air particles can cause increased allergic susceptibility in offspring.

Maternal influence in the transmission of asthma susceptibility

Asthma is one of the most common chronic diseases in children, with increasing morbidity and mortality. A genetic predisposition and exposure to allergens have been implicated as major risk factors for the development of asthma. However, increasing evidence indicates that the mother plays a crucial role in mediating the development of fetal-infant immune responses to inhaled allergens. The exact nature and mechanism of this maternal influence and how it might be associated with the development of allergic sensitization and asthma are not clear. Under normal conditions, the maternal environment during pregnancy promotes an initial Th2 skewed immune response in the offspring which transitions to a nonallergic Th1 type response after birth. However, the allergic mother's influence may delay the normal transition to a nonallergic immune response to inhaled allergens in her children, thus increasing the risk for the development of allergic sensitization and/or asthma. Understanding the underlying mechanisms by which the maternal immune environment can influence the development of the fetal-infant immune response to inhaled allergens may lead to identifying new targets for the prevention of allergic sensitization and asthma.

Targeting of CD25 and glucocorticoid-induced TNF receptor family-related gene-expressing T cells differentially modulates asthma risk in offspring of asthmatic and normal mother mice

Immunological mechanisms leading to increased asthma susceptibility in early life remain obscure. In this study, we examined the effects of neonatal Ab treatments targeting T cell populations on the development of an asthma syndrome. We used a model of increased asthma susceptibility where offspring of asthmatic BALB/c mother mice are more prone (than normal pups) to develop the disease. Neonatal pretreatment of naive pups with mAb directed against the IL-2Ralpha chain (CD25), the costimulatory molecule glucocorticoid-induced TNFR family related gene, and the inhibitory molecule CTLA-4 elicited contrasting effects in offspring depending on the mother's asthma status. Specifically, neonatal CD25(high) T cell depletion stimulated asthma susceptibility in normal offspring whereas it ameliorated the condition of pups born of asthmatic mothers. Conversely, glucocorticoid-induced TNFR family related gene ligation as a primary signal reduced the spleen cellularity and largely abrogated asthma susceptibility in asthma-prone offspring, without inducing disease in normal pups. Striking changes in Th1/Th2 cytokine levels, especially IL-4, followed mAb pretreatment and were consistent with the impact on asthma susceptibility. These results point to major differences in neonatal T cell population and responsiveness related to maternal asthma history. Interventions that temporarily remove and/or inactivate specific T cell subsets may therefore prove useful to attenuate early life asthma susceptibility and prevent the development of Th2-driven allergic airway disease.