Characterization of regulatory T cells in urban newborns

Changes in Treg and Breg cells in a healthy pediatric population

The interpretation of clinical diagnostic results in suspected inborn errors of immunity, including Tregopathies, is hampered by the lack of age-stratified reference values for regulatory T cells (Treg) in the pediatric population and a consensus on which Treg immunophenotype to use. Regulatory B cells (Breg) are an important component of the regulatory system that have been poorly studied in the pediatric population. We analyzed (1) the correlation between the three immunophenotypic definitions of Treg (CD4+CD25hiCD127low, CD4+CD25hiCD127lowFoxP3+, CD4+CD25hiFoxP3+), and with CD4+CD25hi and (2) the changes in Treg and Breg frequencies and their maturation status with age. We performed peripheral blood immunophenotyping of Treg and Breg (CD19+CD24hiCD38hi) by flow cytometry in 55 healthy pediatric controls. We observed that Treg numbers varied depending on the definition used, and the frequency ranged between 3.3-9.7% for CD4+CD25hiCD127low, 0.07-1.6% for CD4+CD25hiCD127lowFoxP3+, and 0.24-2.83% for CD4+CD25hiFoxP3+. The correlation between the three definitions of Treg was positive for most age ranges, especially between the two intracellular panels and with CD4+CD25hi vs CD4+CD25hiCD127low. Treg and Breg frequencies tended to decline after 7 and 3 years onwards, respectively. Treg's maturation status increased with age, with a decline of naïve Treg and an increase in memory/effector Treg from age 7 onwards. Memory Breg increased progressively from age 3 onwards. In conclusion, the number of Treg frequencies spans a wide range depending on the immunophenotypic definition used despite a good level of correlation exists between them. The decline in numbers and maturation process with age occurs earlier in Breg than in Treg.

Surface Phenotype Changes and Increased Response to Oxidative Stress in CD4+CD25high T Cells

Conversion of CD4+CD25+FOXP3+ T regulatory cells (Tregs) from the immature (CD45RA+) to mature (CD45RO+) phenotype has been shown during development and allergic reactions. The relative frequencies of these Treg phenotypes and their responses to oxidative stress during development and allergic inflammation were analysed in samples from paediatric and adult subjects. The FOXP3lowCD45RA+ population was dominant in early childhood, while the percentage of FOXP3highCD45RO+ cells began increasing in the first year of life. These phenotypic changes were observed in subjects with and without asthma. Further, there was a significant increase in phosphorylated ERK1/2 (pERK1/2) protein in hydrogen peroxide (H2O2)-treated CD4+CD25high cells in adults with asthma compared with those without asthma. Increased pERK1/2 levels corresponded with increased Ca2+ response to T cell receptor stimulation. mRNA expression of peroxiredoxins declined in Tregs from adults with asthma. Finally, CD4+CD25high cells from paediatric subjects were more sensitive to oxidative stress than those from adults in vitro. The differential Treg sensitivity to oxidative stress observed in children and adults was likely dependent on phenotypic CD45 isoform switching. Increased sensitivity of Treg cells from adults with asthma to H2O2 resulted from a reduction of peroxiredoxin-2, -3, -4 and increased pERK1/2 via impaired Ca2+ response in these cells.

Respiratory

Lung disease rivals the position for the top cause of death worldwide. Causes and pathology of the myriad lung diseases are varied, yet nutrition can either affect the outcome or support treatment in the majority of cases. This chapter explores the modifiable risk factors, from lifestyle changes to dietary intake to specific nutrients, anti-nutrients, and toxins helpful for the nutritionist or dietitian working with lung disease patients. General lung health is discussed, and three major disease states are explored in detail, including alpha-1 antitrypsin deficiency, asthma, and idiopathic pulmonary fibrosis. Although all lung diseases have diverse causes, many integrative and functional medical nutrition therapies are available and are not being utilized in practice today. This chapter begins the path toward better nutrition education for the integrative and functional medicine professional.

Inner-City Asthma in Children

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

Characterization of Regulatory T Cells in Preterm and Term Infants

Our study aimed to study regulatory T cells (Tregs) and their expression of CD45RA, HLA-DR, and CD39 in preterm and full-term infants. In an observational study, we used a three-color flow cytometry for determination of Tregs and their expression of CD45RA, HLA-DR, and CD39 in preterm and full-term infants. The percentages of CD4⁺CD25^+highFoxp3⁺, CD39⁺ Tregs, HLA-DR⁺ Tregs and the expression of Foxp3⁺ in CD4⁺CD25^+highFoxp3 Tregs cells were significantly lower in neonates when compared to healthy adult controls. The levels of naïve resting Tregs (CD45RA⁺Tregs) were significantly higher in neonates than controls. The percentages of CD4⁺CD25^+highFoxp3⁺Tregs, total CD4⁺CD25⁺ and CD4⁺CD25^+high were significantly higher in preterm infants when compared to the full-term group. Moreover, CD45RA⁺Tregs were significantly higher in preterm than in term infants. We found significant inverse correlations between the gestational age and the levels of both Tregs (r = - 0.395, p = 0.017) and CD45RA⁺Tregs (r = - 0.422, p = 0.010). Relative to full-term, the frequencies, and phenotypes of Tregs were affected by prematurity. A larger longitudinal study with a sufficient number of newborns is needed to investigate the Treg pool of term and preterm infants thoroughly and to explore the association between the Treg pool and clinical variables.

Significant augmentation of regulatory T cell numbers occurs during the early neonatal period

Regulatory T cells (T_regs ) control immune responses by suppressing various inflammatory cells. T_regs in newborn babies may play an important role in preventing excessive immune responses during their environmental change. We examined the number and phenotype of T_regs during the neonatal period in 49 newborn babies. T_regs were characterized by flow cytometry using cord blood (CB) and peripheral blood (PB) from the early (7-8 days after birth) and late (2-4 weeks after birth) neonatal periods. CD4⁺ forkhead box protein 3 (FoxP3⁺ ) T cells were classified into resting T_regs (CD45RA⁺ FoxP3^low ), activated T_regs (CD45RA^- FoxP3^high ) and newly activated T cells (CD45RA^- FoxP3^low ). Compared with CB and PB during the late neonatal period, the percentage of T_regs and all T_reg subpopulations in the CD4⁺ lymphocyte population were increased significantly during the early neonatal period. Furthermore, the proportion and absolute number of activated T_regs were increased markedly compared with other T_reg subpopulations, such as resting T_regs and newly activated T cells (non-T_regs ), in the early neonatal period. Increased T_regs concomitantly expressed the suppressive molecule cytotoxic T lymphocyte antigen-4 (CTLA-4). The up-regulated expression of chemokine receptor 4 (CCR4) and down-regulated expression of CCR7 were also observed in expanded T_regs . When cord blood cells were cultured in vitro with CD3 monoclonal antibodies (mAb) for 5 days, CD4⁺ CD45RA^- FoxP3^high cells were increased significantly during the culture. Thus, the presence of increased activated T_regs in early neonates may play an important role in immunological regulation by suppressing excessive T cell activation caused by the immediate exposure to ubiquitous antigens after birth.

Regulatory T cells in early life: comparative study of CD4+CD25high T cells from foals and adult horses

The immune system of mammals is subject to continuous development during the postnatal phase of life. Studies following the longitudinal development of the immune system in healthy children are limited both by ethical considerations and sample volumes. Horses represent a particular valuable large animal model for T regulatory (Treg) cells and allergy research. We have recently characterised Treg cells from horses, demonstrated their regulatory capability and showed both their expansion and induction in vitro. Insect bite hypersensitivity (IBH) is a common allergy in horses resembling atopic dermatitis and studies have shown that first exposure to allergens in adult life results in an increased incidence of IBH. The aim of the present study was to characterize circulating CD4⁺CD25^highFoxP3⁺cells in foals, evaluate their suppressive capability and their in vitro induction compared to adult horses. 19 foals (age range, 1–5 months), their adult mothers and six one-year-old horses (yearlings) were included in the study. The proportion of FoxP3⁺ cells within the circulating CD4⁺CD25^high population was significantly higher in foals (47%) compared to their mothers (18%) and to yearlings (26%). Treg cells from foals also displayed a higher suppressive capability. Furthermore, CD4⁺CD25^high cells in foals could be induced in vitro from CD4⁺CD25⁻ cells in a significantly higher proportion compared to mares. These cells also displayed a significantly enhanced suppressive capability. In summary these findings support the notion that exposure of horses to allergens during maturation of the immune system assists the establishment of induced (i)Treg driven tolerance.

In utero arsenic exposure and fetal immune repertoire in a US pregnancy cohort

Arsenic has wide-ranging effects on human health and there is evidence that it alters the immune response by influencing CD4+/CD8+ T cell ratios, IL-2 cytokine levels, and the expression of immune-response genes. We investigated the impact of in utero environmental arsenic exposure on immune development and function in newborns participating in a pregnancy cohort in New Hampshire, U.S., where arsenic levels have exceeded the current EPA maximum contaminant level of 10 μg/L. Our results showed that maternal urinary arsenic concentrations were inversely related to absolute total CD45RA+ CD4+ cord blood CD69+ T cell counts (N=116, p=0.04) and positively associated with CD45RA+ CD69- CD294+ cell counts (p=0.01). In placental samples (N=70), higher in utero urinary arsenic concentrations were positively associated with the expression of IL1β (p=0.03). These data provide evidence that relatively low-level arsenic exposure in utero may alter the fetal immune system and lead to immune dysregulation.

Targeting regulatory T cells to improve vaccine immunogenicity in early life

Human newborns and infants are bombarded with multiple pathogens on leaving the sterile intra-uterine environment, and yet have suboptimal innate immunity and limited immunological memory, thus leading to increased susceptibility to infections in early life. They are thus the target age group for a host of vaccines against common bacterial and viral pathogens. They are also the target group for many vaccines in development, including those against tuberculosis (TB), malaria, and HIV infection. However, neonatal and infant responses too many vaccines are suboptimal, and in the case of the polysaccharide vaccines, it has been necessary to develop the alternative conjugated formulations in order to induce immunity in early life. Immunoregulatory factors are an intrinsic component of natural immunity necessary to dampen or control immune responses, with the caveat that they may also decrease immunity to infections or lead to chronic infection. This review explores the key immunoregulatory factors at play in early life, with a particular emphasis on regulatory T cells (Tregs). It goes on to explore the role that Tregs play in limiting vaccine immunogenicity, and describes animal and human studies in which Tregs have been depleted in order to enhance vaccine responses. A deeper understanding of the role that Tregs play in limiting or controlling vaccine-induced immunity would provide strategies to improve vaccine immunogenicity in this critical age group. New adjuvants and drugs are being developed that can transiently suppress Treg function, and their use as part of human vaccination strategies against infections is becoming a real prospect for the future.

Regulatory T cells and Th1/Th2 in peripheral blood and their roles in asthmatic children

OBJECTIVE

To determine the changes in CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg) and the Th1/Th2 ratio in peripheral blood of children with asthma, in order to investigate its association with asthma.

METHODS

A total of 150 children with asthma were allocated into the acute phase group (n=94) and remission phase group (n=56) based on clinical manifestations. The acute phase group was subdivided into the mild group (n=54) and severe group (n=40). Flow cytometry was applied to determine CD4(+)CD25(+)Foxp3(+) Treg, CD4(+)IFN-γ(+) Th1 and CD4(+)IL-4(+) Th2 levels in peripheral blood of different groups, and the results were compared with normal children (control group, n=50).

RESULTS

The Treg level was significantly lower in the asthma group than the control group (P<0.01): the Treg level was significantly lower in the acute phase group than the remission phase group and control group (P<0.01) and also significantly lower in the severe group than the mild group (P<0.01). The Th1/Th2 ratio was significantly lower in the asthma group than the control group (P<0.01) and also significantly lower in the acute phase group than the remission phase group and control group (P<0.01). The Treg level in peripheral blood of asthmatic children was negatively correlated with the severity of asthma (r=-0.737, P<0.01) and the Th1/Th2 ratio was also negatively correlated with the severity of asthma (r=-0.615, P<0.01), but the Treg level was positively correlated with the Th1/Th2 ratio (r=0.856, P<0.01).

CONCLUSIONS

The significantly decreased level of Treg in peripheral blood and Th subset imbalance in asthmatic children suggest the important roles of Treg and Th immunity in pathogenesis of asthma. The Treg level and Th1/Th2 ratio in peripheral blood can be used to evaluate the severity asthma.

An optimized multi-parameter flow cytometry protocol for human T regulatory cell analysis on fresh and viably frozen cells, correlation with epigenetic analysis, and comparison of cord and adult blood

Multi-parameter flow cytometry analysis of T regulatory (Treg) cells is a widely used approach in basic and translational research studies. This approach has been complicated by a lack of specific markers for Treg cells and lack of uniformity in the quantification of Treg cells. Given the central role of Treg cells in the inception and perpetuation of diverse immune responses as well as its target as a therapeutic, it is imperative to have established methodologies for Treg cell analysis that are robust and usable for studies with multiple subjects as well as multicenter studies. In this study, we describe an optimized multi-parameter flow cytometry protocol for the quantification of human Treg cells from freshly obtained and viably frozen samples and correlations with epigenetic Treg cell analysis (TSDR demethylation). We apply these two methodologies to characterize Treg cell differences between cord blood and adult peripheral blood. In summary, the optimized protocol appears to be robust for Treg cell quantification from freshly isolated or viably frozen cells and the multi-parameter flow cytometry findings are strongly positively correlated with TSDR demethylation thus providing several options for the characterization of Treg cell frequency and function in large translational or clinical studies.

Prevalence of intracellular galectin-1-expressing lymphocytes in umbilical cord blood in comparison with adult peripheral blood

Umbilical cord blood (UCB) is a promising alternative for the treatment of hematological malignancies. The lower immune reactivity of UCB lymphocytes is a well-known phenomenon; however, immune tolerance mechanisms are not fully elucidated. Galectin-1 has strong immunosuppressive properties and plays a key role in the regulation of immune reactivity. We aimed to determine the properties of intracellular galectin-1 (Gal-1)-producing cells within CD3, CD4, CD8, regulatory T (Treg), and natural killer (NK) cells in UCB compared to adult peripheral blood (APB). We took peripheral blood samples from 22 healthy adults and cord blood samples from 19 healthy, term neonates. Intracellular Gal-1 expression was determined by flow cytometry in the above subsets. Furthermore, we assessed the prevalence of naive and memory T cells that play a role in the regulation of immune reactivity. We also performed functional analyses to assess the effect of exogenous Gal-1 on the rate of proliferation of T lymphocytes isolated from APB and UCB. The prevalence of intracellular Gal-1-expressing CD3, CD4, CD8, Treg and NK lymphocytes was lower in UCB than in APB. However, their capability to produce Gal-1 reaches the level seen in adults. The prevalence of naive cells was higher, whereas that of central and effector memory T cells was lower in UCB compared with APB. Lower Gal-1-producing cell proportion might be due to the naivety of neonatal lymphocytes, as indicated by the positive correlation detected between the number of CD3 lymphocytes expressing intracellular Gal-1 and the prevalence of memory T cells. The intracellular expression of Gal-1 may be down-regulated in neonatal lymphocytes due to the already reduced immune reactivity of UCB. In contrast with previous findings, our results indicate that the administration of exogenous Gal-1 failed to decrease the rate of proliferation in T lymphocytes isolated from either APB or UCB. This suggests that Gal-1-expressing lymphocytes are unlikely to play a major role in mitigating the immune reactivity of UCB.

Longitudinal relationship of early life immunomodulatory T cell phenotype and function to development of allergic sensitization in an urban cohort

BACKGROUND

Immunomodulatory T cells are thought to influence development of allergy and asthma, but early life longitudinal data on their phenotype and function are lacking.

OBJECTIVES

As part of the Urban Environment and Childhood Asthma (URECA) study, we investigated the development of immunomodulatory T cell phenotype and function, and characterized their relation to allergic disease progression from birth through to 2 years of age.

METHODS

Immunomodulatory T cell phenotype and function in cord blood mononuclear cells (CBMC) and peripheral blood mononuclear cells (PBMC) at 1 and 2 years of age were characterized by analysing CD25(bright) and FoxP3(+) expression, proliferative responses and cytokine production. The relation of immunomodulatory T cell characteristics to allergic sensitization and disease at 1- and 2-years of age was investigated.

RESULTS

The proportion of CD4(+)CD25(bright) and CD4(+)CD25(+)FoxP3(+)T cells (n = 114, 83, 82 at birth, 1- and 2-years respectively) increased significantly, whereas there were no significant changes in the suppressive function of CD25(+)T cells (n = 78, 71, 81 at birth, 1- and 2-years respectively). Birth immunomodulatory T cell characteristics were not related to subsequent allergic sensitization or disease. However, increases in the numbers of CD4(+)CD25(bright) cells and their ability to suppress lymphoproliferative responses at 1 year of age were associated with reduced allergic sensitization at 1 (P = 0.03) and 2 (P = 0.02) years of age. Production of the anti-inflammatory cytokine IL-10 by CD25(+)T cells appeared to mediate this protective suppressive function. In contrast, by 2 years of age, we observed the emergence of a positive association of CD4(+)CD25(+) FoxP3(+) T cell numbers with allergic sensitization (P = 0.05) and eczema (P = 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

These findings suggest that the relationship between immunomodulatory T cell subsets, allergic sensitization and eczema is developmentally regulated. In the first year of life, CD4(+)CD25(+) IL-10 producing T cells are associated with a reduced incidence of allergic sensitization. Once allergic sensitization or eczema is established, CD4(+)CD25(+)FoxP3(+)T-reg cells expand to potentially counteract the allergic inflammatory response. Understanding the relationship between development of immunoregulatory T cells and early onset atopy could lead to new preventive strategies for allergic diseases.

The effect of mode of delivery on T regulatory (Treg) cells of cord blood

OBJECTIVE

To evaluate whether the mode of delivery (vaginal versus C-section) influences the levels of CD4+CD25+FOXP3+ Treg cells in cord blood and maternal peripheral blood and also to examine its relationship with plasma cortisol levels.

METHODS

Newborns either born vaginally (n = 19) or via elective C- section (n = 20) and their mothers, as well as 20 healthy but not pregnant women, were included in the study. CD4+CD25+FOXP3 (Treg) cells were examined by flow cytometry. Total lymphocyte counts (TLC) and serum cortisol levels were also determined for all the groups.

RESULTS

The percentages of CD4+CD25+FOXP3 cells and the serum cortisol levels of infants born vaginally (p < 0.004 and p < 0.0001) and their mothers (p < 0.0001 for both) were found to be significantly higher than those of newborns born by C-section and their mothers. Positive correlations were seen between CD4+CD25+FOXP3+ cells (r = 0.741) and serum cortisol levels (r = 0.468). No relationship was observed between newborns delivered by C-section and their mothers (r = 0.022 for both).

CONCLUSIONS

This study suggests that mode of delivery affects cord blood Treg cells. Higher CD4+CD25+FOXP3+ Treg cells of newborns and their mothers in vaginal delivery group and their relationship with serum cortisol levels suggest a stress phenomenon related to vaginal delivery.

Impaired Ca²⁺ regulation of CD4⁺CD25⁺ regulatory T cells from pediatric asthma

BACKGROUND

CD4(+)CD25(+) regulatory T (T(reg)) cells can control the allergic response to allergen, airway eosinophilia and airway hypersensitivity. We speculated that chronic inflammation persisting in asthma airways is dependent on abnormalities of these T(reg) cells. There are differences in the pathology of asthma in adults and children, and the airways of pediatric asthma are considered to be more naive than those of adults. Therefore, we analyzed the functionality of T(reg) cells in pediatric asthma and the relationship between T(reg) function and asthma symptoms.

METHODS

The anergic state, which is one of the defining properties of T(reg), was analyzed by measuring intracellular Ca(2+) influx following T cell receptor (TCR) stimulation. FOXP3-positive cells and FOXP3 mRNA expression were measured by flow analysis and real-time PCR with the SYBR method, respectively.

RESULTS

CD45RO(+) cells make up approximately 99% of CD4(+)CD25(high) T cells and 89% of CD4(+)CD25(low) T cells in human adult blood. The proportion of CD45RO(+) cells in CD4(+)CD25(+) (high + low) T cells from pediatric asthma was much smaller (about 56%). Interestingly, our data indicated that CD45RO(+) T(reg) cells from pediatric asthma aberrantly increased intracellular Ca(2+) concentrations following TCR activation compared with pediatric nonasthma controls.

CONCLUSION

These impaired CD45RO(+) T(reg) cell functions were correlated with asthma symptoms. The correlation was observed in the group with a highly expressed atopic phenotype and longer duration of asthma. We suggest that chronic inflammation in pediatric asthma airways may be the result of impaired regulatory functions of CD45RO(+) T(reg) cells.

Umbilical cord plasma 25-hydroxyvitamin D concentration and immune function at birth: the Urban Environment and Childhood Asthma study

BACKGROUND

Recent studies have reported conflicting data on the association between maternal intake of vitamin D during pregnancy and asthma.

OBJECTIVE

To assess the influence of prenatal vitamin D status on immune function at birth.

METHODS

In an inner-city birth cohort of 568 newborns, 520 of whom had at least one atopic parent, we measured the umbilical cord (UC) plasma concentration of 25-hydroxyvitamin D (25(OH)D) and the cytokine responses of UC blood mononuclear cells (UCMCs) to stimuli including phytohaemagglutinin (PHA), lipopolysaccharide (LPS), and peptidoglycan. In a subset, the UCMC expression of regulatory T cell markers and the suppressive activity of CD4(+) CD25(+) UCMCs were measured. Results The 25th, 50th, and 75th percentiles of UC plasma 25(OH)D level were 15.0, 20.2, and 25.6 ng/mL, respectively. Most cytokine responses of UCMC were not correlated with UC 25(OH)D concentration; however, IFN-γ release after LPS stimulation was weakly positively correlated with UC 25(OH)D concentration (r=0.11, P=0.01). PHA responses were not significantly correlated with 25(OH)D concentration. The UC plasma 25(OH)D concentration was inversely related to the number of CD25(+) (r=-0.20, P=0.06), CD25(Bright) (r=-0.21, P=0.05), and CD25(+) FoxP3 (r=-0.29, P=0.06) cells as a proportion of CD4(+) T cells in UC blood (r=-0.26, P=0.04) but not to the suppressive activity of CD4(+) CD25(+) cells (r=0.17, P=0.22).

CONCLUSION AND CLINICAL RELEVANCE

UC 25(OH)D concentration was not correlated with most UCMC cytokine responses to multiple stimuli. There was a suggestion of a weakly positive correlation with IFN-γ release after LPS stimulation. The proportions of CD25(+) , CD25(Bright) , and CD25(+) FoxP3 cells to total CD4(+) T cells were inversely correlated with UC 25(OH)D concentration. Our findings suggest that higher vitamin D levels at birth may be associated with a lower number of T-regulatory cells. Vitamin D status in utero may influence immune regulation in early life.

Neonatal immune function and inflammatory illnesses in later life: lessons to be learnt from the developing world?

With the emergence of allergic and autoimmune diseases in populations that have started to transit to a western lifestyle, there has been an increasing interest in the role of environmental factors modulating early immune function. Yet, most of the information concerning neonatal immune function has been derived from studies in westernized countries. We postulate that comparative studies of early immune development in children born under conditions that are typical for a westernized vs. that of a still more traditional setting will provide a crucial insight into the environmental-driven immunological mechanisms that are responsible for the world-wide rise in inflammatory disorders. In this review, we summarize the current understanding of early-life immune function in humans in general and the literature on some major lifestyle factors that may influence neonatal immune function and potentially the risk for disease in later life. An understanding of the mechanisms of 'prenatal/early-life programming' in populations living in traditional compared with modern societies is crucial to develop strategies to prevent a further rise in 'western diseases' such as allergic disorders. Indications exist that prenatal conditioning of the innate immune system by low-grade inflammatory responses is key to inducing more tightly regulated postnatal adaptive immune responses.

Cord blood versus age 5 mononuclear cell proliferation on IgE and asthma

BACKGROUND

Fetal immune responses following exposure of mothers to allergens during pregnancy may influence the subsequent risk of childhood asthma. However, the association of allergen-induced cord blood mononuclear cell (CBMC) proliferation and cytokine production with later allergic immune responses and asthma has been controversial. Our objective was to compare indoor allergen-induced CBMC with age 5 peripheral blood mononuclear cell (PBMC) proliferation and determine which may be associated with age 5 allergic immune responses and asthma in an inner city cohort.

METHODS

As part of an ongoing cohort study of the Columbia Center for Children's Environmental Health (CCCEH), CBMCs and age 5 PBMCs were cultured with cockroach, mouse, and dust mite protein extracts. CBMC proliferation and cytokine (IL-5 and IFN-gamma) responses, and age 5 PBMC proliferation responses, were compared to anti-cockroach, anti-mouse, and anti-dust mite IgE levels, wheeze, cough, eczema and asthma.

RESULTS

Correlations between CBMC and age 5 PBMC proliferation in response to cockroach, mouse, and dust mite antigens were nonsignificant. Cockroach-, mouse-, and dust mite-induced CBMC proliferation and cytokine responses were not associated with allergen-specific IgE at ages 2, 3, and 5, or with asthma and eczema at age 5. However, after adjusting for potential confounders, age 5 cockroach-induced PBMC proliferation was associated with anti-cockroach IgE, total IgE, and asthma (p < 0.05).

CONCLUSION

In contrast to allergen-induced CBMC proliferation, age 5 cockroach-induced PBMC proliferation was associated with age 5 specific and total IgE, and asthma, in an inner-city cohort where cockroach allergens are prevalent and exposure can be high.

The Urban Environment and Childhood Asthma study

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