Maternal cytokine production during pregnancy and the development of childhood wheezing and allergic disease in offspring three years of age

Maternal obesity and the impact of associated early-life inflammation on long-term health of offspring

The prevalence of obesity is increasingly common in the United States, with ~25% of women of reproductive age being overweight or obese. Metaflammation, a chronic low grade inflammatory state caused by altered metabolism, is often present in pregnancies complicated by obesity. As a result, the fetuses of mothers who are obese are exposed to an in-utero environment that has altered nutrients and cytokines. Notably, both human and preclinical studies have shown that children born to mothers with obesity have higher risks of developing chronic illnesses affecting various organ systems. In this review, the authors sought to present the role of cytokines and inflammation during healthy pregnancy and determine how maternal obesity changes the inflammatory landscape of the mother, leading to fetal reprogramming. Next, the negative long-term impact on offspring’s health in numerous disease contexts, including offspring’s risk of developing neuropsychiatric disorders (autism, attention deficit and hyperactive disorder), metabolic diseases (obesity, type 2 diabetes), atopy, and malignancies will be discussed along with the potential of altered immune/inflammatory status in offspring as a contributor of these diseases. Finally, the authors will list critical knowledge gaps in the field of developmental programming of health and diseases in the context of offspring of mothers with obesity, particularly the understudied role of hematopoietic stem and progenitor cells.

Asthma and the Missing Heritability Problem: Necessity for Multiomics Approaches in Determining Accurate Risk Profiles

Asthma is ranked among the most common chronic conditions and has become a significant public health issue due to the recent and rapid increase in its prevalence. Investigations into the underlying genetic factors predict a heritable component for its incidence, estimated between 35% and 90% of causation. Despite the application of large-scale genome-wide association studies (GWAS) and admixture mapping approaches, the proportion of variants identified accounts for less than 15% of the observed heritability of the disease. The discrepancy between the predicted heritable component of disease and the proportion of heritability mapped to the currently identified susceptibility loci has been termed the ‘missing heritability problem.’ Here, we examine recent studies involving both the analysis of genetically encoded features that contribute to asthma and also the role of non-encoded heritable characteristics, including epigenetic, environmental, and developmental aspects of disease. The importance of vertical maternal microbiome transfer and the influence of maternal immune factors on fetal conditioning in the inheritance of disease are also discussed. In order to highlight the broad array of biological inputs that contribute to the sum of heritable risk factors associated with allergic disease incidence that, together, contribute to the induction of a pro-atopic state. Currently, there is a need to develop in-depth models of asthma risk factors to overcome the limitations encountered in the interpretation of GWAS results in isolation, which have resulted in the missing heritability problem. Hence, multiomics analyses need to be established considering genetic, epigenetic, and functional data to create a true systems biology-based approach for analyzing the regulatory pathways that underlie the inheritance of asthma and to develop accurate risk profiles for disease.

Inherent maternal type 2 immunity: Consequences for maternal and offspring health

An inherent elevation in type 2 immunity is a feature of maternal and offspring immune systems. This has diverse implications for maternal and offspring biology including influencing success of pregnancy, offspring immune development and maternal and offspring ability to control infection and diseases such as allergies. In this review we provide a broad insight into how this immunological feature of pregnancy and early life impacts both maternal and offspring biology. We also suggest how understanding of this axis of immune influence is and may be utilised to improve maternal and offspring health.

Association between prenatal polycyclic aromatic hydrocarbons and infantile allergic diseases modified by maternal glutathione S-transferase polymorphisms: results from the MOCEH birth cohort

Background

Prenatal exposure to polycyclic aromatic hydrocarbons (PAH) has been linked to allergic disease onset. Variations in the glutathione S-transferase (GST) gene family can impact the progression of allergic diseases. We sought to examine the association between prenatal PAH exposure and infantile allergic diseases in 6-month-old infants, and how maternal glutathione S-transferase M1 (GSTM1) or T1 (GSTT1) polymorphism affects the association between prenatal PAH exposure and allergic diseases in the Mothers and Children's Environmental Health (MOCEH) study.

Methods

The study sample comprised 349 infants and their mothers from the MOCEH study, for whom 1-hydroxypyrene (1-OHP) and 2-naphthol were measured in both the early period of pregnancy and late period of pregnancy. An infant was deemed to be affected by an allergic disease if diagnosed with or if developed at least one of the allergic diseases. A logistic regression analysis was performed to study the association between urinary 1-OHP and 2-naphthol levels during pregnancy and allergic diseases in 6-month-old infants. Furthermore, analyses stratified by maternal GSTM1 or GSTT1 present/null polymorphisms were performed.

Results

The risk of allergic diseases in 6-month-old infants was significantly increased in accordance with an increase in urinary 1-OHP during the early period of pregnancy (odds ratio [OR]: 1.84; 95% confidence interval [CI]: 1.05, 3.23; by one log-transformed unit of 1-OHP μg/g creatinine). The increased risk of infantile allergic diseases associated with urinary 1-OHP during the early period of pregnancy was limited to the maternal GSTT1 null type (OR: 2.69; 95% CI: 1.17, 6.21, by one log-transformed unit of 1-OHP μg/g creatinine); however, the Relative Excess Risk due to Interaction was not statistically significant.

Conclusions

The present study found that infantile allergic diseases could be affected by intrauterine PAH exposure, particularly in the early prenatal period and the risk was limited to the maternal GSTT1 null type.

Intergenerational Impacts of Maternal Stress on Early Childhood Atopy in Black Americans

OBJECTIVE

Black children are disproportionately affected by atopic diseases (i.e., atopic dermatitis, allergic rhinitis, asthma, and food allergies), with health disparities present in early life. Studies in White samples suggest that maternal stress confers risk for offspring atopy, yet little is known about these relationships in Black populations. This study seeks to (a) examine the relationship between self-reported and physiological indicators of maternal stress and offspring atopy and (b) explore warm and responsive caregiving as a potential protective factor in Black Americans.

METHODS

A sample of 179 Black mother-child dyads of varying socioeconomic status participated in a prospective longitudinal study. Mothers completed self-reports of childhood trauma, prenatal stress, postnatal stress, and physician diagnosis of offspring atopy; provided blood samples to assess physiological responses to chronic stress exposure; and participated in a behavioral task with their infant.

RESULTS

Maternal self-reports of childhood trauma, prenatal stress, and postnatal stress were not associated with offspring diagnosis of atopy by 2-3 years of age. Mothers who produced a smaller inflammatory response during pregnancy were more likely to have an offspring with atopy by 2-3 years of age. Warm and responsive parenting demonstrated a protective effect; the positive association between maternal stress and offspring atopy was less apparent in cases of mother-child interactions characterized by high levels warm and responsive parenting.

CONCLUSION

Failure to replicate previous findings suggests that the maternal stress-offspring atopy relationship is complex. Future studies must examine the unique stressors in Black Americans, as well as caregiving as a potential protective factor.

Cord blood group 2 innate lymphoid cells are associated with lung function at 6 weeks of age

Objective

Offspring born to mothers with asthma in pregnancy are known to have lower lung function which tracks with age. Human group 2 innate lymphoid cells (ILC2) accumulate in foetal lungs, at 10‐fold higher levels compared to adult lungs. However, there are no data on foetal ILC2 numbers and the association with respiratory health outcomes such as lung function in early life. We aimed to investigate cord blood immune cell populations from babies born to mothers with asthma in pregnancy.

Methods

Cord blood from babies born to asthmatic mothers was collected, and cells were stained in whole cord blood. Analyses were done using traditional gating approaches and computational methodologies (t‐distributed stochastic neighbour embedding and PhenoGraph algorithms). At 6 weeks of age, the time to peak tidal expiratory flow as a percentage of total expiratory flow time (tPTEF/tE%) was determined as well as Lung Clearance Index (LCI), during quiet natural sleep.

Results

Of 110 eligible infants (March 2017 to November 2019), 91 were successfully immunophenotyped (82.7%). Lung function was attempted in 61 infants (67.0%), and 43 of those infants (70.5% of attempted) had technically acceptable tPTEF/tE% measurements. Thirty‐four infants (55.7% of attempted) had acceptable LCI measurements. Foetal ILC2 numbers with increased expression of chemoattractant receptor‐homologous molecule (CRTh2), characterised by two distinct analysis methodologies, were associated with poorer infant lung function at 6 weeks of age.”

Conclusion

Foetal immune responses may be a surrogate variable for or directly influence lung function outcomes in early life.

Inflammatory mechanisms linking maternal and childhood asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness, inflammation, and remodeling. Asthma often develops during childhood and causes lifelong decrements in lung function and quality of life. Risk factors for childhood asthma are numerous and include genetic, epigenetic, developmental, and environmental factors. Uncontrolled maternal asthma during pregnancy exposes the developing fetus to inflammatory insults, which further increase the risk of childhood asthma independent of genetic predisposition. This review focuses on the role of maternal asthma in the development of asthma in offspring. We will present maternal asthma as a targetable and modifiable risk factor for childhood asthma and discuss the mechanisms by which maternal inflammation increases childhood asthma risk. Topics include how exposure to maternal asthma in utero shapes structural lung development with a special emphasis on airway nerves, how maternal type-2 cytokines such as IL-5 activate the fetal immune system, and how changes in lung and immune cell development inform responses to aero-allergens later in life. Finally, we highlight emerging evidence that maternal asthma establishes a unique "asthma signature" in the airways of children, leading to novel mechanisms of airway hyperreactivity and inflammatory cell responses.

Plasma immunological markers in pregnancy and cord blood: A possible link between macrophage chemo-attractants and risk of childhood type 1 diabetes

PROBLEM

Previous studies have suggested that immune perturbations during pregnancy can affect offspring type 1 diabetes (T1D) risk. We aimed to identify immunological markers that could predict offspring T1D or that were linked to T1D risk factors.

METHOD OF STUDY

We quantified selected circulating immunological markers in mid-pregnancy (interleukin [IL]-1β, IL-1ra, IL-2Rα, IL-2, -4, -5, -6, -10, -12p70, 13, -17A, GM-CSF, IFN-γ, CXCL10, CCL 2, CCL3, CCL4, TNF) and cord blood plasma (neopterin and kynurenine/tryptophan ratio) in a case-control study with 175 mother/child T1D cases (median age 5.8, range 0.7-13.0 years) and 552 controls.

RESULTS

Pre-pregnancy obesity was positively associated with CCL4, CXCL10, kynurenine/tryptophan ratio and neopterin (P < .01). The established T1D SNPs rs1159465 (near IL2RA) and rs75352297 (near CCR2 and CCR3) were positively associated with IL-2Rα and CCL4, respectively (P < .01). There was a borderline association of CCL4 and offspring T1D risk, independent of maternal obesity and genotype. When grouping the immunological markers, there was a borderline association (P = .05) with M1 phenotype and no association between M2-, Th1-, Th2- or Th17 phenotypes and offspring T1D risk.

CONCLUSION

Increased mid-pregnancy CCL4 levels showed borderline associations with increased offspring T1D risk, which may indicate a link between environmental factors in pregnancy and offspring T1D risk.

Cytokine profile and maternal depression and anxiety symptoms in mid-pregnancy-the FinnBrain Birth Cohort Study

Maternal prenatal psychological symptoms are associated with child health outcomes, e.g., atopic diseases. Altered prenatal functioning of the immune system is a potential mechanism linking maternal symptoms with child health. Research on prenatal distress and cytokines is warranted. The study population comprised consecutive N = 139 women from a general population-based FinnBrain Birth Cohort Study. Standardized questionnaires for depressive, overall anxiety, and pregnancy-related anxiety symptoms were used. Serum concentrations of selected cytokines were analyzed using Multiplex bead arrays from samples drawn at the gestational week 24. The concentrations of T helper (Th)2-related interleukins (IL)-9 and IL-13 and Th1-related IL-12 correlated positively with prenatal depressive and overall anxiety symptom scores (p values, range 0.011-0.029). Higher interferon (IFN)-γ/IL-4 ratio (p = 0.039) and Th2-related IL-5 (p = 0.007) concentration correlated positively with depressive symptoms. Pregnancy-related anxiety score correlated positively with IL-12 (p = 0.041), IL-13 (p = 0.025), and anti-inflammatory IL-10 (p = 0.048) concentrations. IL-6 and TNF-α concentrations were unrelated to prenatal symptoms. As a novel finding, we observed positive correlations between concentrations of potentially proallergenic cytokines and maternal prenatal psychological symptoms. Different symptom measures may yield distinct cytokine responses. This provides hypotheses for studies on mechanisms bridging prenatal stress and child health.

Prenatal VOC exposure and redecoration are related to wheezing in early infancy

Redecoration of dwellings is a common behavior of expecting parents. Former studies gave evidence that early childhood exposure to volatile organic compounds (VOC) resulting from renovation activities may increase the risk for wheeze in infants.

OBJECTIVES

The aim of the present study was to evaluate the impact of prenatal exposure on early wheeze and to identify sensitive time windows. Within the LINA birth cohort study data on renovation activities and respiratory outcomes were assessed via questionnaires during pregnancy and at children's age of one. At both timepoints, also indoor VOC concentrations were measured. The associations were studied by logistic regression analysis. Floor covering during pregnancy contributed to an increased risk for physician treated wheeze (adjusted odds ratio OR=5.20, 95% confidence interval 1.8-15.2) during the first 12 months after birth in particular in children with an atopic predisposition. Thereby, wall-to-wall-carpets, PVC material, and laminate were the flooring materials which showed the strongest adverse associations. Floor covering was associated with enhanced concentrations of VOCs in the apartments. For the VOCs styrene, ethylbenzene, octane, 1-butanol, tridecane, and o-xylene, a significant association was found to the occurrence of wheezing symptoms. In contrast to pregnancy, exposure during the first 12 months after birth showed less detrimental associations. Only the association between wheezing and styrene as well as between wheezing and PVC flooring remained significant for exposure after birth. Redecoration during pregnancy, especially changing floor materials, increases the risk for respiratory diseases in early childhood and should therefore be avoided at least in families with a history of atopic diseases.

The association of preterm birth with severe asthma and atopic dermatitis: a national cohort study

BACKGROUND

Asthma and atopic dermatitis are both regarded as atopic diseases. Being born too early is associated with increased risk of asthma, but some studies have indicated that the opposite might be true for atopic dermatitis. We explored in more detail the associations between preterm birth, asthma, and atopic dermatitis.

METHODS

We analyzed data from Norwegian registries with prospectively collected data. All live births in Norway from 1967 through 2001 were followed through 2005 by linking the Medical Birth Registry of Norway to the National Insurance Scheme and to Statistics Norway. Only severe asthma and atopic dermatitis were registered in the National Insurance Scheme.

RESULTS

Of a total of 1,760,821 children, we identified 9,349 cases (0.5%) with severe asthma and 6,930 cases (0.4%) with severe atopic dermatitis. Compared with children born at term (37-41 wk gestation), preterm birth was associated with increased odds for severe asthma (odds ratio (OR) 1.7 (95% confidence interval (CI): 1.6-1.8) for 32-36 wk gestation and OR 3.6 (95% CI: 3.1-4.2) for 23-31 wk) and decreased odds for severe atopic dermatitis (OR 0.9 (95% CI: 0.8-1.0) for 32-36 wk gestation and OR 0.7 (95% CI: 0.5-1.0) for 23-31 wk). Adjustment for perinatal and socio-demographic factors weakened the association between gestational age and severe asthma, while slightly strengthening the association between gestational age and severe atopic dermatitis.

CONCLUSIONS

Preterm birth was associated with increased risk of severe asthma and decreased risk of severe atopic dermatitis.

Relationship between maternal demoralization, wheeze, and immunoglobulin E among inner-city children

BACKGROUND

Prior research has linked maternal prenatal and postnatal mental health with the subsequent development of asthma in children. However, this relationship has not been examined in inner-city African Americans and Hispanics, populations at high risk for asthma.

OBJECTIVE

To determine the relationship of maternal demoralization with wheeze, specific wheeze phenotypes, and seroatopy among children living in a low-income, urban community.

METHODS

African American and Dominican women aged 18 to 35 years residing in New York City (the Bronx and Northern Manhattan) were recruited during pregnancy (n = 279). Maternal demoralization (ie, psychological distress) was measured both prenatally and postnatally by validated questionnaire. Outcomes included wheeze, transient (birth to 2.5 years of age), late onset (3-5 years), and persistent (birth to 5 years of age), evaluated via questionnaire and total and indoor allergen specific IgE (at birth and ages 2, 3, and 5 years). Logistic regression with generalized estimating equations assessed the association of demoralization with wheeze and atopy. Multinomial regression explored associations between demoralization and specific wheeze phenotypes.

RESULTS

Prenatal demoralization significantly predicted overall wheeze (adjusted odds ratio OR, 1.66; 95% confidence interval [CI], 1.29-2.14), transient wheeze (OR, 2.25; 95% CI, 1.34-3.76), and persistent wheeze (OR, 2.69; 95% CI, 1.52-4.77). No association was found between demoralization and IgE after adjustment (total IgE: OR, 1.04; 95% CI, 0.74-1.45; any specific IgE: OR, 0.96; 95% CI, 0.57-1.60).

CONCLUSIONS

In this inner-city cohort, prenatal demoralization was associated with transient and persistent wheeze. Understanding how maternal demoralization influences children's respiratory health may be important for developing effective interventions among disadvantaged populations.

Adaptive cytokine production in early life differentially predicts total IgE levels and asthma through age 5 years

BACKGROUND

Although it has been postulated that allergic disease is associated with a predominance of T(H)2 cells, whether IgE levels and asthma might differ in their relation to early-life cytokine production is not known.

OBJECTIVE

We sought to assess the relationship between first-year adaptive immune cytokine production with asthma and total IgE levels through age 5 years in a nonselected birth cohort.

METHODS

Mitogen (concanavalin A/phorbol 12-myristate 13-acetate)-stimulated IL-4, IL-5, IL-13, and IFN-γ levels were measured in supernatants from cord blood mononuclear cells and PBMCs at birth, 3 months, and 12 months. Total serum IgE levels and physician-diagnosed active asthma were assessed at 1, 2, 3, and 5 years. Longitudinal models that adjust for both T(H)1 and T(H)2 cytokine production were used to determine relations of outcomes.

RESULTS

Relations of cytokines to total IgE levels and asthma were strikingly different. Total IgE levels through age 5 years were positively associated with 12-month IL-4 (P < .001), IL-5 (P < .001), and IL-13 (P = .02) levels when adjusted for IFN-γ levels and inversely associated with 12-month IFN-γ levels after IL-4 adjustment (P = .01). Active asthma through age 5 years was positively associated with 3-month IL-13 levels adjusted for IFN-γ (odds ratio, 2.6; P < .001) and inversely associated with 3-month IFN-γ levels adjusted for IL-13 (odds ratio, 0.5; P = .001). These relations were strongest for nonatopic asthma.

CONCLUSION

Total IgE levels and active asthma through age 5 years are associated with adaptive cytokine production in early life, although relations vary temporally and with regard to the relative importance of individual cytokines.

Maternal C-reactive protein levels in pregnancy are associated with wheezing and lower respiratory tract infections in the offspring

OBJECTIVE

We assessed whether maternal C-reactive protein (CRP) levels during pregnancy and CRP gene variations are associated with wheezing and lower respiratory tract infections (LRTIs) in offspring.

STUDY DESIGN

Information on wheezing and LRTIs in the offspring at 6 and 14 months of age, and maternal CRP levels and genotype was obtained from a population-based birth cohort.

RESULTS

A total of 63 children (12.5%) experienced recurrent wheezing and 61 (12.4%) a recurrent diagnosis of LRTIs. Children in the highest tertile of maternal CRP levels had a higher risk of experiencing recurrent wheezing (adjusted odds ratio, 2.87; 95% confidence interval, 1.23-6.71) and being diagnosed with recurrent LRTIs (odds ratio, 2.37; 95% confidence interval, 1.01-5.55), as compared with children in the lowest tertile. The rs1205 polymorphism influenced maternal serum CRP levels but not the risk of the offspring outcomes.

CONCLUSION

Higher CRP levels in pregnancy are associated with wheezing and LRTIs in offspring. However, genetic variation in CRP influencing maternal levels is not related to these phenotypes.

Reduced maternal regulatory T cell numbers and increased T helper type 2 cytokine production are associated with elevated levels of immunoglobulin E in cord blood

BACKGROUND

There is evidence that the basis of an atopic-skewed immune response is acquired early in life, perhaps at the fetal stage. Thus, we hypothesized that the development of the fetal immune system might be influenced by maternal regulatory T cells (Treg) and maternal T cell cytokine production during pregnancy. The aim of the present study was to assess the influence of maternal Treg and cytokine production during pregnancy on Treg and atopy at birth.

METHODS

Within the mother-child study LINA (Lifestyle and Environmental factors and their Influence on Newborns Allergy risk), we determined the frequency and function of Treg and the total IgE concentration in pregnant women in the 34th week of gestation and in corresponding cord bloods at birth (n=24). Furthermore, we assessed how maternal mitogen-induced T-helper type 1/T-helper type 2 and inflammatory cytokines influence the level of cord blood Treg and IgE.

RESULTS

Frequencies of CD4(+)CD25(high) T cells were higher (P=0.001), whereas percentages of FOXP3+ T cells were lower (P<0.001) in cord blood cells compared with maternal blood. Reduced maternal CD4(+)CD25(high) Treg frequencies correlated with increased total IgE concentrations at the 34th week of gestation (r=-0.32, P=0.028) and with increased IgE concentrations in cord blood (r=-0.50, P<0.001). Elevated maternal mitogen-induced Th2 cytokine production was related to increased total IgE levels in the serum of corresponding cord bloods (IL-4, r=0.53; IL-5, r=0.43; IL-13, r=0.52).

CONCLUSIONS

Because cord blood IgE has been shown to be predictive for allergic diseases in early childhood, our results indicate that reduced maternal Treg numbers and increased Th2 cytokine production during pregnancy might influence the allergy risk of the child.