Fetal programming of immune function and respiratory disease

Maternal diet before and during pregnancy and risk of asthma and allergic rhinitis in children

BACKGROUND

Consumption of certain foods during pregnancy has been shown to have beneficial effects on childhood asthma and allergic disease development and aggravation. However, most studies provide conflicting results and the relationships between maternal preconceptional diet and risks of childhood asthma and allergic disease have not previously been explored. The objective of this study was to assess maternal diet during the year before pregnancy and the last 3 months of pregnancy and investigate their associations with the risks of asthma, wheezing, allergic rhinitis and atopic dermatitis in young children.

METHODS

The study sample consisted of 1140 mother-child pairs from the EDEN cohort. Mothers had responded to the food frequency questionnaires used to assess diet before and during pregnancy. Children were followed up using health questionnaires. The health outcomes studied were: asthma, wheezing, allergic rhinitis and atopic dermatitis by the age of 3 years.

RESULTS

Using multivariable-adjusted logistic regression models, significant inverse associations were observed between cooked green vegetable consumption before pregnancy and childhood asthma; consumption of eggs and raw vegetables before and during pregnancy, consumption of grains before pregnancy, and consumption of cooked green vegetables during pregnancy and allergic rhinitis. For the first time, a significant positive association was found between meat intake during the preconceptional period and a risk of wheezing, allergic rhinitis and atopic dermatitis.

CONCLUSIONS

Based on our findings, preconceptional and prenatal maternal intake of certain type of food groups may be preventive against asthma, wheezing and allergic rhinitis, whereas higher maternal intake of meat before pregnancy may increase the risk of wheezing, allergic rhinitis and atopic dermatitis in young children.

Developmental Immunotoxicity, Perinatal Programming, and Noncommunicable Diseases: Focus on Human Studies

Developmental immunotoxicity (DIT) is a term given to encompass the environmentally induced disruption of normal immune development resulting in adverse outcomes. A myriad of chemical, physical, and psychological factors can all contribute to DIT. As a core component of the developmental origins of adult disease, DIT is interlinked with three important concepts surrounding health risks across a lifetime: (1) the Barker Hypothesis, which connects prenatal development to later-life diseases, (2) the hygiene hypothesis, which connects newborns and infants to risk of later-life diseases and, (3) fetal programming and epigenetic alterations, which may exert effects both in later life and across future generations. This review of DIT considers: (1) the history and context of DIT research, (2) the fundamental features of DIT, (3) the emerging role of DIT in risk of noncommunicable diseases (NCDs) and (4) the range of risk factors that have been investigated through human research. The emphasis on the human DIT-related literature is significant since most prior reviews of DIT have largely focused on animal research and considerations of specific categories of risk factors (e.g., heavy metals). Risk factors considered in this review include air pollution, aluminum, antibiotics, arsenic, bisphenol A, ethanol, lead (Pb), maternal smoking and environmental tobacco smoke, paracetamol (acetaminophen), pesticides, polychlorinated biphenyls, and polyfluorinated compounds.

Ambient temperature and pregnancy influence cortisol levels in female guinea pigs and entail long-term effects on the stress response of their offspring

Mammals generally respond to the important metabolic requirements imposed by thermoregulation and pregnancy by increasing plasma concentrations of glucocorticoid that promote the mobilization of body reserves and enhance energy use by tissues. This study examined the impact of distinct ambient temperatures and reproductive status on cortisol plasma levels in female guinea pigs (Cavia aperea f. porcellus). We also examined cortisol profiles of their offspring. Forty adult females were placed in individual boxes, 20 were exposed to a neutral thermal regime (mean ambient temperature 22.1 ± 1.5 °C) and 20 were maintained under a cool thermal regime (15.1 ± 1.5 °C). Within each treatment, 12 females were pregnant and 8 were non-pregnant. Pregnancy generated a marked elevation of baseline cortisol. Ambient temperature also affected cortisol concentrations. Compared to the pregnant females from the neutral thermal regime, pregnant females maintained under cool conditions exhibited lower baseline levels of cortisol, were less active, but they displayed a greater stress response (i.e. rapid increase of plasma cortisol) following handling. Thermal treatment did not influence reproductive output, reproductive effort, or offspring characteristics. This suggests that pregnant female guinea pigs cope with cool (but not extreme) thermal conditions by reducing activity and baseline cortisol levels, possibly to save energy via an adaptive response. Interestingly, the greater amplitude of the stress response of the cool regime females was also observed in their offspring 2 months after parturition, suggesting that hormonal ambience experienced by the individuals in utero shaped their stress response long after birth.

Familial factors do not confound the association between birth weight and childhood asthma

OBJECTIVE

Studies have found associations between low birth weight and asthma. However, this association could be due to familial confounding. Our objective was to investigate whether fetal growth and birth weight affect the risk of asthma in childhood, controlling for gestational age (GA), and shared (familial) environment and genetic factors.

PATIENT AND METHODS

Information on asthma, zygosity, birth characteristics, and potential confounders was collected for all 9- and 12-year-old twins through the Swedish Twin Register and Medical Birth Register. To obtain an overall effect of birth weight on risk of asthma, we performed cohort analyses on all twins (N = 10918). To address genetic and shared environmental confounding, we performed a co-twin control analysis by using the 157 monozygotic and 289 dizygotic same-sex twin pairs who were discordant for asthma.

RESULTS

The overall rate of asthma ever was 13.7%. In the cohort analysis, the adjusted odds ratio (OR) for asthma in relation to a 1000-g decrease in birth weight was 1.57 (95% confidence interval [CI]: 1.38-1.79), and for each reduced gestational week the OR was 1.10 (95% CI: 1.07-1.13). In the co-twin control analyses, a 1000-g decrease in birth weight corresponded to an OR of 1.25 (95% CI: 0.74-2.10) for dizygotic same-sex twins and 2.42 (95% CI: 1.00-5.88) for monozygotic twins.

CONCLUSIONS

There is an association between fetal growth and childhood asthma that is independent of GA and shared (familial) environment and genetic factors, which indicates that fetal growth restriction affects lung development, supporting additional studies on the early metabolic and physiologic mechanisms of childhood asthma.

Prenatal and childhood Mediterranean diet and the development of asthma and allergies in children

Objective

To discuss current evidence about the relation between prenatal and childhood Mediterranean diet, and the development of asthma and allergies in children.

Design

Review of the literature.

Setting and results

Four recent studies conducted in Mediterranean countries (Spain, Greece) and one conducted in Mexico evaluated the association between childhood Mediterranean diet and asthma outcomes in children. All of the studies reported beneficial associations between a high level of adherence to the Mediterranean diet during childhood and symptoms of asthma or allergic rhinitis. Individual foods or food groups contributing to the protective effect of Mediterranean diet included fish, fruits, vegetables, legumes, nuts and cereals, while detrimental components included red meat, margarine and junk food intake.

Two studies focused on prenatal Mediterranean diet: the first is a birth cohort in Spain that showed a protective effect of a high adherence to the Mediterranean diet during pregnancy on persistent wheeze, atopic wheeze and atopy at the age of 6·5 years; while the second is a cross-sectional study in Mexico, collecting information more than 6 years after pregnancy, that showed no associations between maternal Mediterranean diet during pregnancy and allergic symptoms in childhood except for current sneezing.

Conclusions

Findings from recent studies suggest that a high level of adherence to the Mediterranean diet early in life protects against the development of asthma and atopy in children. Further studies are needed to better understand the mechanisms of this protective effect, to evaluate the most relevant window of exposure, and to address specific components of diet in relation to disease.

Impact of diet on the immunological microenvironment of the pregnant uterus and its relationship to allergic disease in the offspring--a review of the recent literature

Medical progress has reduced the mortality from infectious diseases in most countries, but allergic diseases have become more prevalent worldwide over the same period, especially in industrialized countries. This has prompted speculation that modern lifestyles have altered the relationship between heredity and environment so as to promote development of an atopic phenotype when exposure to infection decreases. A healthy uterine microenvironment is known to favor Th2 lymphocyte development. However, some evidence suggests that persistence of the Th2 pattern of immunity directs the developing organism's immune response towards a long-lasting atopic phenotype. Even though the outcome also depends on other factors (such as infection, functional state of the intestinal microflora, and exposure to environmental allergens at times critical to development), it seems that the immune system during the perinatal period is responsive to interventions that are no longer effective in adulthood. We have reviewed the literature accessible through Medline to identify recent advances in the prevention of allergic disease through interventions in the fetal-maternal relationship. Diet seems to have a significant impact on the immunological profile of the pregnant uterus, as well as on the postnatal development of allergic disease in the offspring, as suggested by the effects of probiotic bacteria and by manipulations of the dietary content of polyunsaturated fatty acids and antioxidants. This highlights the need for further studies, in order to define the best intervention methods, the most appropriate time interval and the individuals who will most likely benefit from them.

Early life factors related to clinical manifestations of atopic disease but not to skin-prick test positivity in young children

The relative influence of early life events in the development of IgE-mediated allergy is still undetermined. We investigated early life factors in relation to skin-prick test positivity (SPT) and clinical manifestations of atopic disease in a population-based sample of 201 Italian children (3 months-5 years), after considering their interactions with known determinants of allergy. Among them, 143 children had SPT performed to common allergens. Threatened abortions, general anesthesia at delivery, prematurity, birthweight < 2500 g, maternal smoking, dampness and gas heating exposure were all significantly related to an increased risk of frequent rhinitis in the absence of cold (18%). In utero smoking, threatened abortions, fetal health complications, infantile colic, maternal smoking in childhood (satisfactorily correlated with maternal expired CO during the survey) and respiratory infections were all independent determinants of frequent wheezing (23%). Doctor's diagnosis of asthma (3%) was related to in utero smoking, being born in spring, infantile colic and respiratory infections. A simultaneous exposure to in utero smoking and infantile colic put the infants to a fourfold higher risk of frequent wheezing and to a ninefold risk of asthma, respectively. Having a pet and washing blankets at < 60 degrees C were inversely related to frequent wheezing. Data confirmed also that maternal phenotype influences the inheritance of atopic disease. No event, except a low intake of fruit (< 3/week), was significantly associated with positive SPT (20%) or eczema. Besides allergic sensitization, other events, which occur early in life, seem critical to the development of IgE-mediated allergy.

Thymus size and head circumference at birth and the development of allergic diseases

BACKGROUND

The positive association between a large head circumference at birth and total serum IgE levels has been suggested to be due to negative associations between head circumference at birth and thymus development and between thymus development and total serum IgE levels.

OBJECTIVES

To examine the associations between head circumference and thymus size at birth and the development of allergic disease.

METHODS

The size of the thymus was assessed by sonography during the first week of life in 149 healthy term infants. Information on birth characteristics and mode of delivery was collected at delivery. The presence of allergic disease was assessed 5 years later by mailed questionnaires, which were returned by 85% of the eligible families.

RESULTS

At birth, head circumference was positively associated with thymus size (P < 0.001). In all, 27 (23%) of the children had developed at least one allergic disease. Multivariate analysis revealed that both parental allergy (Prevalence Ratio and 95% CI) = 3.18 (1.49-6.78)) and caesarean delivery (2.62 (1.48-4.64)) were independently correlated with allergic disease, whereas thymus size was not.

CONCLUSIONS

Our study does not support that a large head circumference is associated with a small thymus size, nor that a small thymus size is associated with allergic disease. Whether thymus size at birth is related to total serum IgE levels still remains to be elucidated.

In utero and perinatal complications preceding asthma

BACKGROUND

It has been suggested that pregnancy and early life may influence the development of asthma in the offspring, but published studies have not carefully controlled for potential biases.

METHODS

In a large British birth cohort of 4065 natural children of 2583 mothers, we investigated whether in utero and perinatal influences contribute to the development and the severity of asthma in childhood, allowing for possible confounders of the relationship, and considering the nonindependence of familial data.

RESULTS

Child asthma (10.1%) was more frequently reported by mothers when there had been health complications during pregnancy (prevalence =14.3%; adjusted odds ratio [ORadj] =2.01; 95% confidence interval, 1.52-2.67), labor, or delivery (19.3%, ORadj =1.35, 1.01-1.81); child illness or health complications during the first week of life (22.6%, ORadj =1.35, 1.01-1.82); and birth weight of < 2.5 kg (7.0%, ORadj =1.57, 1.10-2.25). Specific causes of health complications during pregnancy which significantly related to asthma were early or threatened labor (ICD: 644) (4.8%, ORadj =1.58, 1.03-2.40) and the malposition or malpresentation of the fetus (ICD: 652) (1.6%, ORadj =3.63, 1.47-8.91).

CONCLUSION

The results provide further evidence that in utero and perinatal factors may increase the risk of developing asthma.