Is deficiency of interferon gamma production by allergen triggered cord blood cells a predictor of atopic eczema?

Anti-TNF-alpha and Th1 cytokine-directed therapies for the treatment of asthma

PURPOSE OF REVIEW

This article examines recent work about the role of TNF-alpha and of selected Th1-related cytokines in asthma with particular emphasis on the therapeutic potential of blocking the biological activity of these mediators.

RECENT FINDINGS

Current research endeavours suggest that asthma pathogenesis is driven by a mixed Th1/Th2 immune response. The contribution of individual Th1-associated and Th2-associated effector mechanisms to this mixed response profile is highly heterogeneous and variations in response patterns seem to be associated with heterogeneity in clinical phenotypes. In particular, it is now acknowledged that allergen-specific Th1 responses appear to be responsible for the pathogenetic effects seen in patients suffering from the more severe chronic forms of the disease. This is important because usual treatments for asthma appear to have limited effects on the more chronic severe forms of the disease and there is a pressing need for the development of new treatment strategies. The failure of topical corticosteroids to reduce TNF-alpha and Th1-derived cytokines to a significant level in asthmatic airways may explain to a certain extent why these drugs appear to have limited effects in the more severe forms of asthma.

SUMMARY

It is likely that therapies blocking TNF-alpha and interfering with Th1-derived cytokines may be a considerable advance in the management of those asthma patients who are particularly resistant to typical treatment modalities.

Neonatal immune responses to TLR2 stimulation: influence of maternal atopy on Foxp3 and IL-10 expression

Background

Maternal atopic background and stimulation of the adaptive immune system with allergen interact in the development of allergic disease. Stimulation of the innate immune system through microbial exposure, such as activation of the innate Toll-like-receptor 2 (TLR2), may reduce the development of allergy in childhood. However, little is known about the immunological effects of microbial stimulation on early immune responses and in association with maternal atopy.

Methods

We analyzed immune responses of cord blood mononuclear cells (CBMC) from 50 healthy neonates (31 non-atopic and 19 atopic mothers). Cells were stimulated with the TLR2 agonist peptidoglycan (Ppg) or the allergen house dust mite Dermatophagoides farinae (Derf1), and results compared to unstimulated cells. We analyzed lymphocyte proliferation and cytokine secretion of CBMC. In addition, we assessed gene expression associated with T regulatory cells including the transcription factor Foxp3, the glucocorticoid-induced TNF receptor (GITR), and the cytotoxic lymphocyte antigen 4 (CTLA4). Lymphocyte proliferation was measured by ³H-Thymidine uptake, cytokine concentrations determined by ELISA, mRNA expression of T cell markers by real-time RT-PCR.

Results

Ppg stimulation induced primarily IL-10 cytokine production, in addition to IFN-γ, IL-13 and TNF-α secretion. GITR was increased following Ppg stimulation (p = 0.07). Ppg-induced IL-10 production and induction of Foxp3 were higher in CBMC without, than with maternal atopy (p = 0.04, p = 0.049). IL-10 production was highly correlated with increased expression of Foxp3 (r = 0.53, p = 0.001), GITR (r = 0.47, p = 0.004) and CTLA4 (r = 0.49, p = 0.003), independent of maternal atopy.

Conclusion

TLR2 stimulation with Ppg induces IL-10 and genes associated with T regulatory cells, influenced by maternal atopy. Increased IL-10 and Foxp3 induction in CBMC of non-atopic compared to atopic mothers, may indicate an increased capacity to respond to microbial stimuli.

Atopic dermatitis prevention

A shift in focus from disease therapy toward disease prevention is occurring in many medical specialties, including dermatology. There are no generally accepted strategies for the prevention of atopic dermatitis. Most research has focused on allergen avoidance and has not produced consistently effective interventions. Immune cell modulation and skin barrier protection are examples of new approaches that hold promise for preventing, or modifying the course of, this common disease.

Intervention during pregnancy and allergic disease in the offspring

The etiology of allergy is multifactorial, with many variables contributing to the final expression of atopic disease. Three breeding grounds are needed to develop allergic disease: the appropriate genetic background, contact with the allergen(s) and environmental factors. Timing and dosing of allergen(s) are of major importance. Contact with (dietary) allergens and various agents such as tobacco smoke and infections occur not only during post-natal life, but also perinatally and even pre-natally. A critical review of published evidence regarding the impact of maternal exposure to antigens during pregnancy on later development of allergy in the offspring can only conclude that more research is urgently needed. Contact with multiple dietary allergens should be in general of benefit to the fetus to develop tolerance. Current knowledge suggests that pregnant women should have a normal diversified diet, avoiding toxic agents such as tobacco and alcohol. The role of maternal intake of poly-unsaturated fatty acids on the development of atopy in the infants needs to be further evaluated. If parental history would be insufficient to determine the fetal risk, preventive measurements would be advisable for all fetuses.

Cytosine-phosphate-guanine motifs fail to promote T-helper type 1-polarized responses in human neonatal mononuclear cells

BACKGROUND

The T-helper type 1 (Th1) trophic properties of bacterial cytosine-phosphate-guanine (CpG) motifs have made them logical adjuvants both for the suppression of Th2-mediated allergic disease in early life and for promoting vaccine responses in neonates who have relatively immature Th1 function. However, little is known about their effects on immature immune responses in this period.

OBJECTIVES

To compare the effects of CpG on adult and neonatal cellular immune responses to various stimuli.

METHODS

The immune responses of mononuclear cells (MC) derived from neonates (n=25) and their mothers (n=25) were compared in vitro. These were stimulated with house dust mite (HDM), CpG B, CpG C, non-CpG oligodeoxynucleotides (ODN) or diphtheria toxoid (DT) in optimized conditions. In parallel cultures, CpGs were combined with HDM or DT antigens to assess the effect of the various ODN on these antigen-specific responses. Lymphoproliferation and cytokine responses IL-13, IFN-gamma, IL-6, IL-10, TNF-alpha) were measured for all of the cultures described above.

RESULTS

Although neonates showed attenuated lymphoproliferation to CpG, the production of antigen-presenting cell-derived cytokines such as IL-6 and IL-10 and the up-regulation of major histocompatibility complex class II (HLA-DR) were detected at adult levels. T cell-derived cytokines (IL-13 and IFN-gamma) were not detectable in response to CpG alone. Most neonates also failed to produce detectable IFN-gamma to HDM or DT (unlike adults), but readily produced IL-13 to these stimuli. The addition of CpG resulted in an increase in neonatal IFN-gamma production in response to HDM (P=0.011) and a similar but non-significant trend with DT. However, rather than inhibiting Th2 IL-13 responses, the addition of CpGs was associated with a significant increase in the IL-13 responses to HDM (P=0.016) and DT (P=0.03), effects not seen in adults.

CONCLUSIONS

This study provides further evidence that neonatal MC responses to CpG are functionally different from adults, and do not show clear Th1 polarization. The CpG associated increase in Th2 responses may reflect a potentiation of the normal neonatal Th2 propensity, or non-specific activation of neonatal MC.

Hope for the hygiene hypothesis: when the dirt hits the fan

The hygiene hypothesis was developed in response to data suggesting that the increase in allergic diseases as well as asthma was secondary to a reduced exposure to infectious stimuli. Indeed, the epidemiologic changes, resulting in an increase in atopic disease, have been impressive and intriguing. Furthermore, although there clearly is a genetic component to atopic diseases, genetics cannot account for a marked increase in the incidence and prevalence of allergic manifestations within a few generations. Thus, environmental factors have been suggested as responsible for the changing prevalence. There are two--not mutually exclusive--possibilities, namely, that substances that promote atopy have been added to the environment or that factors that provided protection from allergic disease were lost from the environment. Both outdoor and indoor pollution, along with a long list of other environmental factors, have been proposed. It is of interest that in many developed countries, certain types of pollution have decreased, whereas the prevalence of atopic disease has increased. In this review, we have explored a detailed analysis of a large number of studies that have focused on this issue and suggest that, although the hygiene hypothesis has merit, the stimuli responsible for the new epidemiology remain enigmatic.

Prevalence of atopic diseases and the use of topical corticosteroids. Is there any connection?

The prevalence of atopic diseases (atopic dermatitis, bronchial asthma, allergic rhinitis) has considerably increased for the last 40 years. This tendency has coincided with the beginning of the epoch of the use of the topical corticosteroids, which have a potent immunomodulation action. This fact itself as well as a number of research results has allowed to formulate the following hypothesis: the use of topical corticosteroids in children of early age contributes to the increase of prevalence of atopic diseases in the developed countries. The offered hypothesis can explain lower prevalence of atopic diseases in rural areas and in children from families with the anthroposophic life style. In other side this hypothesis also capable to give explanation of increased level of atopic diseases among people with high socioeconomic level and in children from 1 child families. It is of a note that corticosteroids use in developing countries is limited due to economic reasons and active use of complementary medicine. If the proposed hypothesis is correct, a revision of the therapeutic approaches is necessary concerning the attitude towards application of topical corticosteroids in children suffering from various forms of eczema. The direct proof of this hypothesis can be found during prospective studies.

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

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

Does fish oil supplementation in pregnancy reduce the risk of allergic disease in infants?

PURPOSE OF REVIEW

Parallel increases in many inflammatory diseases over the last 40 years suggest that common environmental changes are promoting inflammatory immune responses and/or inhibiting the processes that normally keep these in check. One key change during this period has been declining intakes of anti-inflammatory dietary factors, including omega-3 polyunsaturated fatty acids (n-3 PUFA). As allergic diseases often first manifest in early infancy, prevention strategies need to be targeted early, even in utero. This review will examine recent evidence for the use of fish oil during this early period as a primary prevention strategy for allergic disease.

RECENT FINDINGS

N-3 PUFA have well documented anti-inflammatory effects in vitro and have also been demonstrated to have health benefits in a range of chronic inflammatory diseases, including cardiovascular disease, rheumatoid arthritis and diabetes, supporting their role in modulating inflammation in vivo. Although the effects of fish oil supplementation in established allergic disease are less convincing, there is accumulating evidence that dietary n-3 PUFA may have greater effects before allergic responses are established.

SUMMARY

Supplementation of the maternal diet in pregnancy with n-3 PUFA may provide a non-invasive intervention with significant potential to prevent the development of allergic and possibly other immune-mediated diseases.

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

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

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

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

Understanding the origin of asthma and its relationship to breastfeeding

Asthma is a chronic disease of the lung that has been increasing at an alarming rate in industrialized countries around the world over the last few decades. Although considerable progress has been made in our understanding of the underlying pathogenesis of the disease, the exact causes of the increasing prevalence are unknown. Studies suggest that most asthma develops in early childhood and that environmental factors present early in life may be crucial in the development of disease. One potential explanation for the recent epidemic referred to as the "hygiene hypothesis" postulates that factors that have resulted in a reduction in exposure to microbial products and/or infections in the western world may be contributing to this rise in disease prevalence. As early life influences are known to play an important role in establishment of asthma, studies have focused on the interface between mother and child that occurs during gestation and through breastfeeding. In this regard, the body of evidence regarding the relationship between breastfeeding and asthma indicates benefit but with the potential for risk. While providing population-level protection from infections and atopy in infancy and early childhood, breastfeeding might also pose an increased risk of atopic asthma among children with asthmatic mothers. In order to put this controversy in context, we discuss our current understanding of asthma pathogenesis, current theories on the factors driving the rising prevalence of asthma, and then discuss the potential influence of breastfeeding on asthma pathogenesis.

Ovalbumin-specific immunoglobulin G and subclass responses through the first 5 years of life in relation to duration of egg sensitization and the development of asthma

BACKGROUND

Egg sensitization, particularly persistent sensitization, is a risk factor for later asthma. However, little is known about accompanying IgG and subclass responses and how they might relate to asthmatic outcome.

OBJECTIVE

To characterize hen's egg ovalbumin (OVA) IgG and subclass responses through the first 5 years of life in relation to duration of egg sensitization and later asthma.

SUBJECTS AND METHODS

The subjects (n=46) formed part of a larger cohort, born to atopic parents, who had been evaluated prospectively for the development of asthma. Egg sensitization was classified as transient (positive egg skin prick test at 1 year only) or persistent (positive skin test for at least 2 years). Plasma OVA IgG, IgG1 and IgG4 concentrations at birth (cord), 6 months, 1 and 5 years of age were measured by ELISA.

RESULTS

The kinetics of OVA IgG and IgG1 responses, but not IgG4, differed between egg sensitized and non-egg sensitized (NES) children. Only persistently sensitized children had a rise in OVA IgG1 concentration through the first year of life, and at 1 year of age they had significantly higher OVA IgG and IgG1 than either transiently sensitized or NES children. High OVA IgG1 was associated with later asthma: at 1 year of age, OVA IgG1 greater than 14,500 U predicted asthma with a sensitivity 64% and specificity 74%.

CONCLUSION

OVA IgG and subclass responses relate to the duration of egg sensitization. Measurement of OVA IgG1 concentration in infancy might offer a useful adjunct to identify those at an increased risk of asthma.

TLR2 and TLR4 stimulation differentially induce cytokine secretion in human neonatal, adult, and murine mononuclear cells

Toll-like receptor 2 (TLR2) and TLR4 signaling may induce differential secretion of T helper 1 (Th1) and Th2 cytokines, potentially influencing the development of autoimmune or atopic diseases. To date, the influence of the type of stimulus, timing, and dose of TLR2 and TLR4 ligands on cytokine secretion has not been well established. We tested whether the innate stimuli peptidoglycan (Ppg, TLR2 agonist) and lipid A (LpA, TLR4 agonist) differentially affect the secretion of interleukin-13 (IL-13) (Th2) and interferon-gamma (IFN-gamma) (Th1). Further, we examined the influence of the maturity of the immune system, species, dose, and timing of stimuli in human cord and adult peripheral blood mononuclear cells (PBMC) and murine cells in vitro and in vivo. Stimulation with Ppg induced the secretion of both IL-13 and IFN-gamma, influenced by time and dose in neonates, adults, and mice. In contrast, stimulation with LpA induced primarily time-independent and dose-independent production of IFN-gamma. Pulmonary administration of Ppg in vivo in mice resulted in secretion of IL-13, whereas administration of LpA resulted in secretion of IFN-gamma in bronchoalveolar lavage (BAL). Therefore, TLR2 and TLR4 stimuli differentially influence IL-13 and IFN-gamma secretion in neonates, adults, and mice, supporting a critical role for innate stimuli in the modulation of cytokine responses.

Prenatal exposure to mite and pet allergens and total serum IgE at birth in high-risk children

To examine the relationship between prenatal exposure to mite, cat and dog allergens and total serum IgE at birth in newborns at high risk of asthma. In the homes of 221 newborns with at least one first-degree relative with asthma, concentrations (ng/g dust) of allergens of house dust mite (mite), cat and dog were measured at the fourth to sixth month of pregnancy in dust samples from the maternal mattress and living room. At day 3-5 after birth, total IgE was measured in capillary heel blood. A total number of 174 blood samples were available (11 mothers refused newborn's blood sampling, and in 36 cases the blood sample was too small for analysis). In 24% of the newborns, total IgE was elevated (cut-off value 0.5 IU/ml). A significant dose response relationship was found between increasing mite allergen levels [divided in quartiles ng/g dust (qrt)] and the percentage of elevated IgE: first qrt (0-85 ng/g) 13%; second qrt (86-381) 19%; third qrt (382-2371) 26%; fourth qrt (> or =2372) 42%, respectively, p=0.01. This relationship remained significant after adjusting for passive smoking, maternal and paternal mite allergy, socio-demographic factors, birth characteristics and (breast) feeding practice in the first week of life. In high-risk newborns, prenatal exposure to mite allergens, but not to cat and dog allergens from dust of the living room and of the maternal mattress was associated with total serum IgE at birth.

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

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

Use of antibacterials in infancy: clinical implications for childhood asthma and allergies

Evidence from experimental studies in rodents and results from epidemiologic studies with a retrospective design suggest a possible causal association between antibacterial use in early childhood and asthma. Such an association is thought to be mediated by antibacterial-induced alterations in the intestinal flora, leading to a skewing of the immune system of young children toward an atopic phenotype. However, results from recently conducted prospective studies suggest that the previously observed association between antibacterial use in early childhood and asthma is not one of 'cause and effect' but rather that frequent antibacterial use in early childhood may be a marker of an increased risk of being diagnosed with asthma later in childhood. Although antibacterials should not be used excessively in young children, their use in early childhood is not likely to explain the increased prevalence of asthma and allergies in children in industrialized countries.

Risk factors for food allergy

Food allergy is a common problem that often affects young children. Numerous factors affect the development of food allergy both prenatally and postnatally. These factors are genetic and environmental. Although little can be done post-conception to alter a child's genetic risk for developing food allergy, early identification may permit alterations of the environment in which food allergy develops. Environmental factors operate both prenatally and postnatally. By understanding how these factors affect development of food allergy, it may be possible for parents to modulate the development of this difficult problem in their children.

Deficient translocation of c-Rel is associated with impaired Th1 cytokine production in T cells from atopic dermatitis patients

Decreased production of T helper type 1 (Th1) cytokines, such as interferon-gamma (IFN-gamma) or interleukin-2 (IL-2), is a hallmark of atopic diseases. While accessory signals from antigen-presenting cells may be missing, T cells themselves may be suppressed in their ability to produce substantial amounts of Th1 cytokines. We show, in this study, that T cell receptor (TCR)-activated T cells from atopic dermatitis (AD) patients proliferate less than control T cells and produce lower amounts of IFN-gamma and IL-2, but comparable amounts of IL-4. Because mice lacking the nuclear factor kappa B (NF-kappaB) transcription factors - p65 or c-Rel - show reduced Th1, but undisturbed Th2 responses, we investigated the role of c-Rel and p65 for Th1 cytokine production in T cells from healthy and severe AD patients. TCR-activated primary T cells from healthy donors treated with c-Rel antisense oligonucleotides produced lower levels of IL-2 and IFN-gamma and proliferated less efficiently than the corresponding control T cells. Moreover, transfection of primary T cells with c-Rel or p65 enhanced proliferation and production of IL-2 and IFN-gamma. Nuclear extracts of activated primary T cells from AD donors bound weakly to NF-kappaB-specific oligonucleotides, compared to extracts from healthy control T cells. Western blotting studies revealed that nuclear, but not cytosolic, extracts from T cells of AD patients lacked significant amounts of c-Rel and p65. T cell clones derived from AD patients failed to sufficiently translocate c-Rel and p65 into the nucleus following activation. Thus, impaired nuclear translocation of c-Rel and p65 may determine an impaired Th1 cytokine response in AD.

Antioxidant intake in pregnancy in relation to wheeze and eczema in the first two years of life

Two thousand women were recruited for a prospective investigation of the influence of maternal antioxidant intake in pregnancy on the development of asthma and eczema in children. A food frequency questionnaire was used to characterize diet during pregnancy and blood antioxidant levels were measured. Postal questionnaires were used to follow up the 1,924 singleton children born to the cohort at 6, 12, and 24 months of age. There were no associations between maternal antioxidant intake and wheezing symptoms and eczema in the children's first year. In the children's second year, maternal vitamin E intake during pregnancy was negatively associated with wheeze in the absence of a "cold" (p for trend 0.010) and, in children whose mothers were atopic, there was a negative association between maternal vitamin E intake and childhood eczema (p for trend 0.024). Maternal vitamin C intake during pregnancy was positively associated with "ever wheeze" and eczema during the children's second year. This study suggests that maternal dietary antioxidant intakes during pregnancy may modify the risks of developing wheeze and eczema during early childhood. Further follow up of the cohort will determine whether maternal diet during pregnancy is associated with asthma and atopic disease in later childhood.

Lactobacillus GG effect in increasing IFN-gamma production in infants with cow's milk allergy

BACKGROUND

Probiotic bacteria are potentially beneficial to maturation of the infant's immune system.

OBJECTIVE

To examine the role of probiotic bacteria in treatment of cow's milk allergy (CMA) and IgE-associated dermatitis, we investigated the immunologic effects of Lactobacillus rhamnosus GG (LGG) and a mixture of 4 bacterial species (MIX).

METHODS

In a randomized, double-blind study design, concomitantly with elimination diet and skin treatment, LGG, MIX, or placebo was given for 4 weeks to infants with suspected CMA. After anti-CD3 (OKT3) and anti-CD28 stimulation of PBMCs, IFN-gamma, IL-4, IL-5, and IL-12 levels were measured in culture supernatants by ELISA. Intracellular IFN-gamma, IL-4, and IL-5 production on CD4 lymphocytes was analyzed with fluorescence-activated cell sorting.

RESULTS

Secretion of IFN-gamma by PBMCs before the treatment was significantly lower in infants with CMA (P=.016) and in infants with IgE-associated CMA (P=.003) than in non-CMA infants. Among the infants who received LGG, the level of secreted IFN-gamma increased in those with CMA (P=.006) and in those with IgE-associated dermatitis (P=.017) when compared with the placebo group. Secretion of IL-4 increased significantly in infants with CMA in the MIX (P=.034) but not in the LGG group.

CONCLUSION

Deficiency in IFN-gamma response appears to be related to CMA. LGG raises IFN-gamma production of PBMC in infants with CMA and in infants with IgE-associated dermatitis and may thus provide beneficial TH1 immunomodulatory signals. MIX, although containing LGG, appears to modulate the immune responses differently.

Functional Maturation of CD4+CD25+CTLA4+CD45RA+T Regulatory Cells in Human Neonatal T Cell Responses to Environmental Antigens/Allergens

A number of laboratories have reported cord blood T cell responses to ubiquitous environmental Ags, including allergens, by proliferation and cytokine secretion. Moreover, the magnitude of these responses has been linked with risk for subsequent expression of allergy. These findings have been widely interpreted as evidence for transplacental priming and the development of fetal T memory cells against Ags present in the maternal environment. However, we present findings below that suggest that neonatal T cell responses to allergens (and other Ags) differ markedly from those occurring in later life. Notably, in contrast to allergen-responsive adult CD4(+) T cell cultures, responding neonatal T cell cultures display high levels of apoptosis. Comparable responses were observed against a range of microbial Ags and against a parasite Ag absent from the local environment, but not against autoantigen. A notable finding was the appearance in these cultures of CD4(+)CD25(+)CTLA4(+) T cells that de novo develop MLR-suppressive activity. These cells moreover expressed CD45RA and CD38, hallmarks of recent thymic emigrants. CFSE-labeling studies indicate that the CD4(+)CD25(+) cells observed at the end of the culture period were present in the day 0 starting populations, but they were not suppressive in MLR responses. Collectively, these findings suggest that a significant component of the reactivity of human neonatal CD4(+) T cells toward nominal Ag (allergen) represents a default response by recent thymic emigrants, providing an initial burst of short-lived cellular immunity in the absence of conventional T cell memory, which is limited in intensity and duration via the parallel activation of regulatory T cells.

Prenatal exposure to house dust mite allergen (Der p 1), cord blood T cell phenotype and cytokine production and atopic dermatitis during the first year of life

This study investigated the influence of prenatal exposure to house dust mite (HDM, D. pteronyssinus) on interleukin (IL)-2, interferon-gamma (IFN-gamma) and IL-4 producing CD4(+) and CD8(+) T lymphocytes in cord blood as well as on the development of sensitization and occurrence of atopic dermatitis (AD) as the first symptom of allergy during the first year of life. Dust samples (n = 22) were collected by vacuum cleaning the maternal mattress during early to mid-pregnancy. In these samples, the amount of the major HDM antigen (Der p 1) was assessed by a sensitive enzyme-linked immunosorbent assay technique (detection limit 0.004 microg/g dust). Flow cytometry was used to determine cord blood lymphocyte subtypes and to quantify the intracellular amounts of IL-2, IFN-gamma and IL-4 produced by cord blood CD4(+) helper and CD8(+) cytotoxic T lymphocytes, both spontaneously and after stimulation with phorbol-12-mirystate-13-acetate and ionomycin. Children were followed for 1 yr for the presence of symptoms associated with allergy. In addition, at the age of 1 yr specific IgE to different classical inhalant and food allergens was measured. Higher prenatal exposure to Der p 1 (>0.2 microg/g dust) was associated with a significant lower percentage of IFN-gamma producing stimulated CD4(+) T lymphocytes, compared with lower prenatal Der p 1 exposure (p = 0.03). The presence of AD during the first year of life (n = 9) was associated with an increased number of naive CD4(+) CD45RA(+) lymphocytes (p = 0.03), with an increased spontaneous IL-4 production by CD8(+) lymphocytes (p = 0.04) and with a decreased percentage of IFN-gamma producing stimulated CD4(+) lymphocytes (p = 0.04). Furthermore, exposure to HDM during pregnancy tended to be higher in mothers of children with AD during the first year of life when compared with those without AD (p = 0.08). This study shows that the level of prenatal exposure to Der p 1 influences the immune profile of cord blood T lymphocytes and the clinical outcome in early life. Therefore, the prenatal environment must be regarded as a possible early risk factors for allergic diseases in children.

Nuclear factor kappa B activation in human cord blood mononuclear cells

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

High IFN-gamma production by CD8+ T cells and early sensitization among infants at high risk of atopy

BACKGROUND

High genetic risk (HR) of atopy among unstratified populations of infants is associated with attenuated IFN-gamma responses. However, the role of IFN-gamma in progression from HR status to active disease is less clear.

OBJECTIVE

To identify immune function markers in neonates with HR that are associated with positive atopic outcomes at 2 years.

METHODS

Cord blood mononuclear cells (CBMCs) were collected from 175 children with HR and cryopreserved. The children were assessed for atopy by skin prick at 0.5 and 2 years. CBMCs were thawed and stimulated with allergens and mitogens PHA and staphylococcal enterotoxin B (SEB), and cytokine responses were determined.

RESULTS

No correlations were observed between allergen-specific CBMC responses and atopic outcomes. In contrast, sensitization was strongly associated with polyclonal IFN-gamma responses to both PHA (P=.002) and SEB (P=.005), and also with SEB-induced IL-5 (P =.05), IL-10 (P =.02), and IL-13 (P =.01). Logistic regression analysis identified elevated PHA-induced IFN-gamma and SEB-induced IL-13 responses as the strongest independent predictors of atopy development. Cell separation studies confirmed CD8+ T cells as the source of approximately 90% of IFN-gamma production.

CONCLUSIONS

IFN-gamma produced by CD8+ T cells may synergize with T(H)2 cytokines in driving atopy development in children with HR.

Pathogenesis of respiratory syncytial virus bronchiolitis-related wheezing

Respiratory syncytial virus (RSV) is a common cause of virus infection of the human respiratory tract during the first two years of life, with virtually all children experiencing at least one infection within this period. Although this usually leads to mild respiratory illness, some infants develop more severe disease (bronchiolitis, pneumonia, etc.) affecting the lower airways and frequently requiring hospitalisation. There is evidence that bronchiolitis hospitalisations have increased during the last two decades and many of the hospitalised children develop wheezing later in life. The immune response to the virus is probably a major factor in the development or the expression of the pathological phenotype. In particular, a bias towards type-2 cytokine responses seems to be associated with more severe disease, whereas a type-1 response leads to more effective viral clearance and milder illness. Although the virus by itself triggers a type-1 response, a preexisting type-1 deficiency may contribute to the severity of the disease. In that sense, RSV bronchiolitis may serve as a marker, reflecting predisposition of the individual for virus induced wheezing early in life and/or asthma later in life.

The role of genetic and environmental factors in the development of T-cell mediated allergic disease in early life

Cognate immunity to inhalant allergens is virtually universal within the adult population, but in the majority of cases this does not progress to the development of persistent asthma. Accumulating evidence suggests that progression from moderate to severe allergic disease is associated with a series of host and environmental factors operative during early childhood which interact to increase risk for both allergic sensitisation and severe respiratory infection, within the same subjects.

Dietary prevention of allergic diseases in infants and small children. Part I: immunologic background and criteria for hypoallergenicity

The role of primary prevention of allergic diseases has been a matter of debate for the last 40 years. In order to shed some light into this issue, a group of experts of the Section of Pediatrics EAACI critically reviewed the existing literature on the subject. In this paper, the immunology of the fetus and newborn is reviewed as well as the post-natal development of the immune system. The influence of post-natal environment and breastfeeding on tolerance induction and sensitization are examined. Allergic diseases result from a strong relationship between genetic and environmental factors. Sensitization to food allergens occurs in the first year of life and cow's milk allergy is the first food allergy to appear in the susceptible infants. Hypoallergenicity of food formulas to be used is a critical issue both for treatment of cow's milk-allergic children and for prevention. Methods to document hypoallergenicity are discussed and evaluated in the preclinical and clinical steps.

Cat allergen-induced cytokine secretion and Fel d 1-immunoglobulin G immune complexes in cord blood

BACKGROUND

We have recently obtained evidence for the presence of immune complexes (IC) in cord blood from allergic and non-allergic mothers. Such complexes could conceivably provide the fetus with the initial trigger for the priming of the T cell system already in utero.

OBJECTIVE

To relate the presence of Fel d 1-IgG IC to T cell cytokine production in cord blood mononuclear cells (CBMCs) after stimulation with cat allergen.

METHODS

CBMC obtained from babies of 15 allergic and 22 non-allergic mothers were cultured in the presence of cat allergen. The production of IFN-gamma, IL-5, IL-10 and IL-13 was determined by ELISA. Furthermore, IgG1 and IgG4 antibodies to cat allergen in cord blood samples were measured by ELISA. A more sensitive ELISA was used to measure Fel d 1-IgG IC.

RESULTS

The prevalence and levels of IC were similar in cord blood from children of allergic and non-allergic mothers. The production of IL-5, IL-10. IL-13 and IFN-gamma by CBMC was not influenced by maternal atopy, but IFN-gamma was less commonly detected in samples with IC. There was no association between the presence of IC and any other cytokines. The levels of IgG1 and IgG4 antibodies were similar in both groups, and tended to be associated with the presence of IC.

CONCLUSION

Immune complexes in cord blood may represent a normal mechanism for inducing primary immune responses, as the responses in babies from allergic and non-allergic mothers were largely similar. Low levels of IFN-gamma seems to be related with the presence of IC in cord blood.

Spontaneous T(H)1 cytokine production by intraepithelial but not circulating T cells in infants with or without food allergies

BACKGROUND

It has been established that the maintenance of immunological tolerance to dietary antigen and the intestinal flora (oral tolerance) is an actively-maintained process dependent upon mucosal lymphocyte populations. Early life exposures appear critical in the development of such tolerance. However little is known about the activation status of mucosal lymphocytes in human infancy and childhood.

PATIENTS AND METHODS

We have performed flow cytometric analysis for cell lineage and cytokine-production status in peripheral blood and duodenal intraepithelial lymphocytes taken during endoscopy from 20 children [median age 2.9 +/- 0.6 years (median +/- SE)] in whom investigation found no intestinal abnormalities (histologically normal controls) and 30 children (median age 1.6 +/- 0.4 years) with confirmed allergy to cow's milk and other dietary antigens.

RESULTS

Regardless of clinical status, spontaneous production of cytokines was low or undetectable in peripheral blood cells. By contrast, intraepithelial CD4 and CD8 cells isolated from the small intestine were often activated, with 5% or more showing spontaneous production of T(H)1 type [interleukin-2, interferon (IFN)-gamma] cytokines in both normal controls and food-allergic children. Stimulation in vitro strongly induced cytokine production in peripheral blood but not intraepithelial lymphocytes. Immunohistochemistry showed similar density of IFN-gamma(+) intraepithelial lymphocytes in controls and allergic children.

CONCLUSIONS

Duodenal intraepithelial lymphocytes in human infants show a state of increased spontaneous activation compared with peripheral blood lymphocytes, and show no significant impairment of T(H)1 responses in food allergic children.

High interleukin-13 production by phytohaemagglutinin- and Der p 1-stimulated cord blood mononuclear cells is associated with the subsequent development of atopic dermatitis at the age of 3 years

OBJECTIVE

The aim of our study was to conduct a prospective investigation into the potential association of cord blood proliferative response and cytokine production in response to various stimuli on the development of atopic dermatitis (AD) at the age of 3 years.

METHODS

Cord blood mononuclear cells (CBMC) from 40 healthy term neonates were isolated. The proliferative response of CBMC stimulated with IL-2, betalactoglobulin (BLG) and house dust mite allergen (Der p 1) was assessed by liquid scintillation counting and the stimulation index (SI) was calculated. The cytokines interleukin (IL-)13, interferon (IFN-)gamma, IL-10 and IL-18 in the cell culture supernatants in response to phytohaemagglutinin (PHA), Der p 1 and BLG were measured using the ELISA technique. After 3 years, symptoms of AD were obtained with a questionnaire completed by the parents.

RESULTS

We observed significantly higher IL-13 levels in response to PHA in children who subsequently developed symptoms of AD (S: median, 291 pg/mL) compared with asymptomatic children (No-S: 149 pg/mL; P=0.021, Wilcoxon test). Similarly, in response to Der p 1 significantly higher IL-13 levels were observed in symptomatic children (S: 168.6; No-S: 61.6 pg/mL; P=0.0084). In response to BLG, IL-13 levels were 287.2 (S) and 123.6 pg/mL (No-S; P=0.19). No significant differences were found when comparing the IFN-gamma levels in CBMC cultures stimulated with PHA (S: 10.2; No-S: 17.6 IU/L; P=0.78), Der p 1 (S: 307.6; No-S: 616.2 IU/L; P=0.2) or BLG (S: 18; No-S: 28.5 IU/L; P=0.83; Fig. 2). The IL-18 and IL-10 levels and the stimulation index in response to IL-2, BLG and Der p 1 showed no significant difference between children who subsequently developed symptoms of AD and asymptomatic children.

CONCLUSION

Our data suggest that enhanced IL-13 levels at birth are associated with the subsequent development of atopic symptoms at the age of 3 years.

Allergen-induced cytokine production, atopic disease, IgE, and wheeze in children

BACKGROUND

The early childhood allergen-induced immune responses associated with atopic disease and IgE production in early life are not well understood.

OBJECTIVE

We assessed the relationship of allergen-induced cytokine production by PBMCs to both atopic disease and to IgE increase in a cohort of children with a parental history of allergy or asthma (n = 112) at a median of 2 years of age. We examined cockroach (Bla g 1)-induced, house dust mite (Der f 1)-induced, and cat (Fel d 1)-induced cytokine secretion, including secretion of IFN-gamma, IL-13, IL-10, and TNF-alpha. We investigated whether distinct cytokine patterns associated with atopic disease can be detected in immune responses of children.

METHODS

PBMCs were isolated, and allergen-induced cytokine secretion was analyzed by means of ELISA. Atopic disease was defined as physician- or nurse-diagnosed eczema or hay fever. Increased IgE was defined as an IgE level of greater than 35 U/mL to dust mite, cockroach, cat, and egg white or a total IgE level of 60 U/mL or greater.

RESULTS

Compared with children without atopic disease, children with atopic disease had lower Der f 1 (P =.005) and Bla g 2 (P =.03) allergen-induced IFN-gamma levels. Compared with children without increased IgE (n = 95), those with increased IgE (n = 16) had higher Der f 1-induced (P =.006) and Fel d 1-induced (P =.005) IL-13 levels and lower Bla g 2-induced (P =.03) IFN-gamma levels. Compared with children with neither atopic disease nor repeated wheeze, children with both atopic disease and repeated wheeze had lower levels of allergen-induced IFN-gamma (P =.01 for Der f 1 and P =.02 for Bla g 2) cytokine secretion.

CONCLUSION

In young children at risk for asthma or allergy, decreased allergen-induced IFN-gamma secretion is associated with atopic disease and, in some cases, with increased IgE levels. Increased allergen-induced IL-13 secretion is most strongly associated with early life increase of IgE.

Immunostimulatory potential of beta-lactoglobulin preparations: effects caused by endotoxin contamination

BACKGROUND

The immunomodulating potential residing in cow's milk proteins is currently receiving increasing attention because of growing interest in functional foods and the complex problem of cow's milk allergy. One of the major cow's milk allergens, whey protein beta-lactoglobulin, has previously been shown to mediate cellular activation in both human and murine immune cells.

OBJECTIVE

We examined the response to different beta-lactoglobulin preparations in naive immune cells.

METHODS

Splenocytes and cells from mesenteric lymph nodes derived from BALB/c mice bred and maintained on a milk-free diet were cultured in vitro with different beta-lactoglobulin preparations. Cell proliferation, cytokine production, and increases in intracellular glutathione were used as cellular activation markers. Moreover, the effect of beta-lactoglobulin on cytokine production in murine bone-marrow-derived dendritic cells was examined.

RESULTS

We observed that some commercial beta-lactoglobulin preparations induced pronounced proliferation of both spleen cells and cells from mesenteric lymph nodes; production of TNF-alpha, IL-6, IL-1beta, and IL-10; and an increased level of intracellular glutathione in spleen cell cultures. Furthermore, TNF-alpha, IL-6, IL-1beta, and IL-10 production was induced in murine bone-marrow-derived dendritic cells. Purification of beta-lactoglobulin from raw milk using nondenaturating conditions, however, revealed that the beta-lactoglobulin per se did not possess the immunomodulatory activity. Eventually, the immunostimulatory effect was found to be caused by endotoxin contamination.

CONCLUSION

These results identify endotoxin as the main immunostimulatory component present in some commercial beta-lactoglobulin preparations. Moreover, the present study makes it evident that immunomodulatory effects attributed to beta-lactoglobulin need to be reassessed.

The potential role of allergen-specific sublingual immunotherapy in atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease associated with increasing prevalence, morbidity, and cost in developed Western countries. Frequently associated with respiratory allergy during adulthood, atopic dermatitis often represents the first phenotypic appearance of atopy in early childhood when the allergic 'march' starts and progressively moves toward food allergy, asthma, and rhinitis. At present, a consistent body of evidence supports the view that atopic dermatitis may represent the skin compartmentalization of a systemic allergic inflammation. Lymphocytes infiltrating early lesional skin express a T helper (Th) 2 pattern of cytokine secretion (increased levels of interleukin [IL]-4 and/or IL-13 and decreased levels of interferon-gamma) as well as the typical Th2-type chemokine receptor CCR4, specific to the thymus and activation-regulated chemokines. Keratinocytes from patients with atopic dermatitis produce thymic stromal lymphopoietin, a novel cytokine that supports the early lymphocyte development in mouse models, and activates dendritic cells involved in the pathogenesis of allergic diseases in humans. Increased levels of circulating hemopoietic precursor cells have been reported in atopic dermatitis, as in allergic asthma and rhinitis. Furthermore, the recognition of CD34+ hemopoietic precursor cells, and evidence for cellular differentiation/maturational events occurring within atopic dermatitis skin lesion infiltrates, are consistent with the recent reinterpretation of the Th2/Th1 paradigm, where Th2 cells appear to belong to the early stages and Th1 to the ultimate stages of a linear, rather than divergent, pattern of lymphoid differentiation. This more detailed understanding of the immunologic derangements contributing to the atopic dermatitis pathogenesis has led to growing interest in allergen-specific immunotherapy for the disease. Due to the complexity intrinsic to atopic dermatitis and the lack of consensus-based guidelines for standardized outcome measure, only eight studies are available in the literature for a qualitative evaluation of this treatment approach. Two of these studies were double blind and placebo controlled, and six were cohort studies. Immunotherapy was found to be effective in one controlled study and five observational reports. Uncertain results were provided by one low-powered, controlled study, and negative outcomes were raised by a unique study performed with oral immunotherapy, which is not an effective route of mucosal allergen administration. Thus, more efficacy studies are required before immunotherapy could be recommended for the routine treatment of atopic dermatitis. Allergen-specific sublingual immunotherapy, given its excellent safety profile and ability to interfere with the systemic aspects of allergic inflammation, appears a good potential candidate for the pathogenetic treatment of the disease.

Maternal smoking in pregnancy alters neonatal cytokine responses

BACKGROUND

Maternal cigarette smoking in pregnancy is an important, common and avoidable exposure that has been linked with elevated cord blood (CB) immunoglobulin E levels and subsequent asthma and allergic disease in childhood. Despite this, there is still very little information about the immunological effects of maternal smoking on the fetus.

METHODS

This aim of this study was to compare cord blood mononuclear cell (CBMC) cytokine responses to allergens [ovalbumin (OVA) or house dust mite (HDM)] and mitogens [concanavalin A (ConA) or phytohemaglutinen (PHA)] in neonates whose mothers smoked throughout pregnancy (n = 17) with responses of neonates whose mothers never smoked (n = 40). Cell cultures were stimulated for 24 h and supernatants collected for cytokine detection by enzyme-linked immunosorbent assay [interleukin (IL)-13, IL-6, interferon (IFN)gamma and IL-10]. Cell pellets were also collected for cytokine mRNA detection (IL-5, IL-9, IFNgamma).

RESULTS

Maternal smoking in pregnancy was associated with significantly higher neonatal T helper type 2 (IL-13 protein) responses to both HDM (P = 0.01) and OVA (P = 0.035). These effects remained statistically significant after allowing for confounding factors, including the effects of maternal atopy. Similar trends were also seen for IL-9mRNA, IL-5mRNA and IL-6 responses, although these were not statistically significant. Although IFNgamma mRNA responses to PHA (P = 0.015) and ConA (P = 0.025) were lower if mothers smoked in pregnancy, there were no differences in neonatal (Th1) IFNgamma protein responses to allergens or mitogens.

CONCLUSIONS

These findings indicate that maternal cigarette smoking can modify aspects of fetal immune function and highlight the need for further studies in this area.

Type 1 and type 2 cytokine imbalance in acute respiratory syncytial virus bronchiolitis

We examined the in vivo immune response of infants to natural respiratory syncytial virus (RSV) infection through analysis of cytokine levels in nasal lavage fluid and stimulated peripheral blood mononuclear cells. Eighty-eight babies with at least one parent with atopy and asthma were prospectively studied through their first winter. Twenty-eight infants had an upper respiratory tract infection where RSV was detected, of whom nine developed signs of acute bronchiolitis. Nasal lavage specimens were assayed for interferon-gamma, interleukin (IL)-4, IL-10, and IL-12 and the RSV load determined by quantitative polymerase chain reaction. Messenger RNA (mRNA) was extracted from stimulated peripheral blood mononuclear cells and interferon-gamma, IL-4, IL-12, and IL-18 mRNA levels determined by polymerase chain reaction. Cytokine profiles were analyzed in relation to clinical outcome. The IL-4/interferon-gamma ratio for infants with acute bronchiolitis was elevated in nasal lavage fluid on both Days 1-2 (p = 0.014) and Days 5-7 (p = 0.001) of the illness compared with infants with upper respiratory tract infection alone. Those with acute bronchiolitis demonstrated a higher IL-10/IL-12 ratio (p = 0.0015) on Days 1-2. IL-18 mRNA levels were reduced (p = 0.019) and the IL-4/interferon-gamma ratio elevated (p = 0.01) in stimulated peripheral blood mononuclear cells from infants with acute bronchiolitis. There was no difference in initial RSV load. These data strongly implicate excess type 2 and/or deficient type 1 immune responses in the pathogenesis of RSV bronchiolitis.

Neonatal interleukin-12 capacity is associated with variations in allergen-specific immune responses in the neonatal and postnatal periods

BACKGROUND AND OBJECTIVES

A reduced capacity of antigen presenting cells (APC) to provide pro-T helper 1 (Th1) signals, such as IL-12, to T cells during early life may be implicated in the development of T helper 2 (Th2)-mediated allergic disease. In this study we examined the relationships between the capacity for IL-12 responses in the neonatal period and atopic risk (family allergy), in vitro T cell responses to allergens, and the subsequent development of allergic disease at 6 years.

METHODS

The capacity of circulating neonatal (and maternal) APC to produce IL-12 p70 in response to LPS (and IFN-gamma) stimulation was assessed in a group of 60 children with previously well-characterized immune responses to allergens and atopic outcomes. The IL-12 responses were compared with allergen-induced lymphoproliferation (to house dust mite (HDM) ovalbumin (OVA), cat and beta-lactoglobulin (BLG)) and IL-13 and IFN-gamma cytokine responses (to OVA, HDM and phytohaemaglutinin (PHA)) in the neonatal and postnatal periods. IL-12 responses were also compared according to atopic risk and atopic outcomes (doctor-diagnosed asthma, eczema, food allergies and sensitization as evidenced by skin prick testing) at 6 years clinical follow-up.

RESULTS

Maternal peripheral blood mononuclear cells (PBMC) synthesized significantly greater amounts of IL-12 than neonatal PBMC, though within maternal-infant pairs IL-12 responses were significantly correlated (r = 0.4, P = 0.019). Moreover, neonatal IL-12 responses were positively correlated with neonatal allergen proliferation for HDM (r = 0.6, P < 0.0001), OVA (r = 0.55, P < 0.0001), cat (r = 0.5, P = 0.003) and BLG (r = 0.55, P = 0.001), but negatively correlated with neonatal IL-13 responses to both allergens tested (HDM: r = - 0.4, P = 0.03 and OVA: r = - 0.5, P = 0.001). Both neonatal and maternal IL-12 responses were positively correlated with postnatal IFN-gamma responses to HDM at 12, 18 and 24 months of age (responses after age of 2 years were not assessed). There was no relationship between atopic risk and IL-12 capacity in the neonatal period, but there was a (non-significant) trend for neonatal IL-12 responses to be lower in the high-risk children who developed clinical allergy at 6 years (compared with the low risk group) although the number in this analysis was small.

CONCLUSIONS

Reduced APC IL-12 production in the perinatal period was associated with reduced T cell activation (lymphoproliferation), stronger neonatal Th2 responses, and weaker Th1 responses to allergen in the postnatal period. This supports the notion that variations in APC function in early life may contribute to altered allergen-specific cytokine responses associated with later allergy.

Cytokine production by cord blood mononuclear cells stimulated with cows milk proteins in vitro: interleukin-4 and transforming growth factor beta-secreting cells detected in the CD45RO T cell population in children of atopic mothers

BACKGROUND

Food antigens from the maternal circulation may sensitize fetal T cells in utero and be an important determinant in the development of food allergy.

METHODS

Here we have examined the spontaneous and recall response to cow's milk proteins of cord blood mononuclear cells (CBMC) of newborn children, using single cell ELISPOT assays.

RESULTS

In term newborns, confirming previous studies, the spontaneous cytokine response of CBMC is dominated by IL-4, IL-5, IL-10, and as shown here for the first time, TGF-beta. For TGF-beta only, the response of samples from infants of atopic mothers was significantly lower than samples from infants of non-atopic mothers. In vitro stimulation of CBMC with bovine serum albumin, casein and beta-lactoglobulin resulted in a significant increase of all cytokine-secreting cells, again dominated by T helper type 2 (Th2) cytokines. There was a clear tendency for samples from infants of atopic mothers to have lower Th2 responses than samples from infants of non-atopic mothers, which was particularly significant for both IL-4 and TGF-beta. Spontaneous cytokine secreting cells were virtually absent in cord blood from infants < 34 weeks gestation, as were cows milk protein-induced responses, although they were readily detectable in samples from infants aged > 34 weeks. To explore whether the cytokine secreting cells were in the naive CD4+ CD45RA population or memory CD4+ CD45RO T cells, these subsets were purified by positive and negative selection and tested for spontaneous and cows milk protein-induced cytokine responses. Strikingly, although the responses were small, the CD45RO+ cells from children of atopic mothers showed significant spontaneous and antigen-specific IL-4 and TGF-beta responses, whereas the same population from infants of non-atopic mothers showed virtually no response. In addition CD45RA+ cells from infants of mothers with maternal atopy showed decreased IL-4 and TGF-beta responses, especially the latter.

CONCLUSIONS

The cows milk antigen-specific IL-4 and TGF-beta responses preferentially seen in the memory cell subset of infants with a maternal history of atopy strongly suggests Th2 skewing to dietary antigens in utero.