Th1/Th2 patterns and balance in cytokine production in the parents and infants of a large birth cohort

Delayed asthmatic response to allergen challenge and cytokines released by nonspecifically stimulated blood cells

Background. Bronchial asthma patients can develop various asthmatic response types following bronchial allergen challenge, such as immediate (IAR), late (LAR), dual late (DLAR), or delayed (DYAR), due to different immunologic mechanisms. The DYAR, recorded in 24 patients, beginning between 26 and 32 hrs and lasting up to 56 hrs after the bronchial allergen challenge, differs from the IAR, LAR, and DLAR in clinical, diagnostic, and immunologic aspects. Objective. To investigate amounts of particular cytokines released by the blood cells after an additional nonspecific stimulation with Phorbol 12-myristate 13-acetate (PMA) during the DYAR. Methods. In 24 patients, the repeated DYAR was supplemented with determination of cytokines both in the nonstimulated plasma and in the supernatants of the blood cells stimulated with PMA before and up to 72 hours after the bronchial challenge, by means of enzyme-linked immunoassay. Results. No significant changes of the prechallenge cytokine concentrations in the non-stimulated serum were recorded in the DYAR patients as compared with the healthy subjects. The DYAR was accompanied by significantly increased postchallenge concentrations (P < 0.05) of IL-2, IL-8, IL-12p70, IL-13, IL-18, IFN- γ , G-CSF, TNF- α , and TGF- β , while decreased concentration of IL-7 (P < 0.05) in the nonstimulated plasma. The significantly increased postchallenge concentrations of IL-2, IL-8, IL-12p70, IL-13, IL-18, IFN- γ , TNF- α , and TGF- β were released by peripheral blood cells after stimulation with PMA, as compared with both their prechallenge concentrations and with the PBS control values. Conclusions. These results would support evidence for an important role of the Th1 cells, neutrophils, monocytes, and probably also NK cells in the immunologic mechanism(s) leading to the development of the clinical DYAR. Nevertheless, an additional role of macrophages, endothelial and epithelial cells in these mechanisms cannot be even excluded.

Enveloped virus but not bacteria block IL-13 responses in human cord blood T cells in vitro

Infections that occur early in life may have a beneficial effect on the immune system and thereby reduce the risk of allergen sensitization and/or allergic disease. It is not yet clear to what extent specific virus and/or bacteria can mediate this effect. The purpose of this study was to assess the role of virus and bacteria in CD4⁺ T cell‐derived cytokine production in newborns. We compared the effects of five bacteria (Staphlococcus aureus, Escherichia coli, Clostridium difficile, Lactobacillus rhamnosus and Bifidobacterium bifidus) and seven virus (adenovirus, coronavirus, cytomegalovirus, herpes simplex virus, influenza virus, morbillivirus and poliovirus) on the Th1/Th2 cytokine production in mixed lymphocyte reactions using CD4⁺ T cells from cord blood cocultured with allogenic myeloid or plasmacytoid dendritic cells. When comparing the baseline cytokine production prior to microbial stimulation, we observed that cord plasmacytoid DC were stronger inducers of Th2 cytokines (IL‐5 and IL‐13) compared with cord myeloid DC and to adult DC. When adding microbes to these cultures, bacteria and virus differed in two major respects; Firstly, all enveloped viruses, but none of the bacteria, blocked Th2 (IL‐13) production by cord CD4⁺ cells. Secondly, all Gram‐positive bacteria, but none of the virus, induced IL‐12p40 responses, but the IL‐12p40 responses did not affect Th1 cytokine production (IFN‐γ). Instead, Th1 responses were correlated with the capacity to induce IFN‐α secretion, which in cord cells were induced by S. aureus and influenza virus alone. These data imply that enveloped virus can deviate Th2 responses in human cord T cells.

Respiratory distress syndrome (RDS) in premature infants is underscored by the magnitude of Th1 cytokine polarization

Respiratory distress syndrome (RDS) is a common problem and the leading cause of death in premature infants (PI). The introduction of surfactant treatment for RDS management has lowered mortality and morbidity; nevertheless, some neonates do not improve and are at increased risk of pulmonary hemorrhage. Inflammation, not only local but also systemic, seems to play an important role in the pathogenesis of RDS. To determine whether cytokine patterns characterize RDS and its outcome, we measured type-1 (IL-2, TNF-α, IFN-γ, IL-6) and type-2 (IL-4, IL-5, IL-10, TGF-β1) serum cytokines of 47 PI with established RDS and a control group of 30 healthy, appropriate for gestational age, full-term neonates. Cord blood samples were obtained at the time of delivery from PI and controls. Venous blood samples were collected from PI who received surfactant treatment and/or developed pulmonary hemorrhage. Significantly elevated cord blood cytokine levels were observed in PI at time of delivery, compared to controls, except for IL-5 and TNF-α levels that were within control range. The type-1/type-2 cytokine ratio was significantly increased in PI vs controls. Neonates who developed pulmonary hemorrhage between 2 and 3 days of life and/or died, presented the strongest Th1 and type-1 cytokine polarization that was mainly due to increased IFN-γ and TNF-α, and decreased TGF-β1. The majority of these PI were female with very low gestational age. Overall, PI with RDS present a Th1/type-1 cytokine polarization, which persists irrespective of the treatment provided, and is amplified when complications appear. Th1 polarization is associated with poor prognosis.

Developmental allometry and paediatric malaria

WHO estimates that 80% of mortality due to malaria occurs among infants and young children. Though it has long been established that malaria disproportionately affects children under age five, our understanding of the underlying biological mechanisms for this distribution remains incomplete. Many studies use age as an indicator of exposure, but age may affect malaria burden independently of previous exposure. Not only does the severity of malaria infection change with age, but the clinical manifestation of disease does as well: younger children are more likely to suffer severe anaemia, while older children are more likely to develop cerebral malaria. Intensity of transmission and acquired immunity are important determinants of this age variation, but age differences remain consistent over varying transmission levels. Thus, age differences in clinical presentation may involve inherent age-related factors as well as still-undiscovered facets of acquired immunity, perhaps including the rates at which relevant aspects of immunity are acquired. The concept of "allometry" - the relative growth of a part in relation to that of an entire organism or to a standard - has not previously been applied in the context of malaria infection. However, because malaria affects a number of organs and cells, including the liver, red blood cells, white blood cells, and spleen, which may intrinsically develop at rates partly independent of each other and of a child's overall size, developmental allometry may influence the course and consequences of malaria infection. Here, scattered items of evidence have been collected from a variety of disciplines, aiming to suggest possible research paths for investigating exposure-independent age differences affecting clinical outcomes of malaria infection.

A Th1/Th2-associated chemokine imbalance during infancy in children developing eczema, wheeze and sensitization

BACKGROUND

Analyses of circulating chemokines offer novel tools to investigate the T helper (Th)1/Th2 imbalance in allergic disease in vivo.

OBJECTIVE

To relate circulating Th1- and Th2-associated chemokines in infancy to allergic disease, sensitization and probiotic supplementation.

METHODS

Circulating levels of Th1-associated CXC-chemokine ligand (CXCL)9, CXCL10 and CXCL11 and Th2-associated CC-chemokine ligand (CCL)17 and CCL22 were assessed with Luminex and CCL18 with enzyme-linked immunosorbent assay at birth (n=109), 6 (n=104), 12 (n=116) and 24 months (n=123) in 161 infants completing a double-blind placebo-controlled allergy prevention trial with Lactobacillus reuteri during the last month of gestation and through the first year of life. The infants were followed regarding the development of allergic disease and sensitization until 2 years of age.

RESULTS

The Th2-associated chemokines CCL17 and CCL22 were the highest at birth and then decreased, whereas CCL18 and the Th1-associated chemokines increased with age. High Th2-associated chemokine levels were observed in children developing allergic disease. Sensitization was preceded by elevated levels of the Th2-associated CCL22 and reduced levels of the Th1-associated CXCL11 already at birth. The Th2-associated CCL17 was also elevated at birth in infants developing recurrent wheeze. A high Th2/Th1 ratio (CCL22/CXCL10) at birth associated with both sensitization and eczema development. The presence of L. reuteri in stool in the first week of life was associated with low CCL17 and CCL22 and high CXCL11 levels at 6 months of age. High Th1-associated chemokine levels were associated with day-care.

CONCLUSION AND CLINICAL RELEVANCE

Allergic disease and sensitization in infancy was associated with low circulating Th1- and high Th2-associated chemokine levels already from birth. Circulating chemokines are useful for investigating the Th1/Th2 imbalance in allergic disease in vivo. Elucidation of the role of chemokines in allergic diseases may lead to future treatments (ClinicalTrials.gov NCT01285830).

Maternal immune status in pregnancy is related to offspring's immune responses and atopy risk

BACKGROUND

The influence of maternal immune responses in pregnancy on children's immune competence and the development of atopic diseases later in life are poorly understood. To determine potential maternal effects on the maturation of children's immune system and resulting disease risks, we analysed immune responses in mother-child pairs in a prospective birth cohort study.

METHODS

Within the Lifestyle and Environmental factors and their Influence on Newborns Allergy risk (LINA) study, concentrations of Th1/Th2/Th17 and inflammatory cytokines/chemokines as well as IgE were measured in phytohemagglutinin and lipopolysaccharide stimulated maternal blood in the 34th week of gestation and in corresponding children's blood at birth and 1 year after (n = 353 mother-child pairs). Information on atopic outcomes during the first year of life was obtained from questionnaires.

RESULTS

Concentrations of inflammatory markers, excepting TNF-α, were manifold higher in cord blood samples compared with maternal blood. Th1/Th2 cytokines were lower in children's blood with a Th2 bias at birth. Maternal inflammatory parameters (MCP-1, IL-10, TNF-α) in pregnancy showed an association with corresponding cytokines blood levels in children at the age of one. High maternal IgE concentrations in pregnancy were associated with increased children's IgE at birth and at the age of one, whereas children's atopic dermatitis (AD) was determined by maternal AD.

CONCLUSIONS

Maternal inflammatory cytokines during pregnancy correlate with children's corresponding cytokines at the age of one but are not related to IgE or AD. While maternal IgE predicts children's IgE, AD in children is only associated with maternal disease.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Relationships among environmental exposures, cord blood cytokine responses, allergy, and wheeze at 1 year of age in an inner-city birth cohort (Urban Environment and Childhood Asthma study)

BACKGROUND

The Urban Environment and Childhood Asthma study was established to investigate the immunologic and environmental causes of asthma in inner-city children.

OBJECTIVE

We sought to evaluate potential atopic outcomes in the first 12 months and their relationships to environmental exposures and immune development.

METHODS

A birth cohort of 560 children with at least 1 parent with allergy or asthma was established in Baltimore, Boston, New York, and St Louis. Wheezing is assessed every 3 months, allergen-specific IgE yearly, and mononuclear cell cytokine responses at birth and yearly; environmental assessments include dust allergen and endotoxin, maternal stress, and indoor nicotine and nitrogen dioxide levels.

RESULTS

Key outcomes in the first year include wheeze in 49%, 2 or more episodes of wheeze in 23%, eczema in 30%, and detectable IgE to milk, egg, and/or peanut in 32% and to cockroach in 4%. Household dust revealed levels of greater than 2 μg/g to cockroach in 40%, mite in 19%, cat in 25%, and mouse in 29%, and 66% of homes housed at least 1 smoker. Positive associations were detected between multiple wheeze and cotinine levels, maternal stress, and maternal depression, whereas cytokine responses to a variety of innate, adaptive, and mitogenic stimuli were inversely related to eczema.

CONCLUSIONS

This high-risk cohort of inner-city infants is exhibiting high rates of wheeze, eczema, and allergic sensitization. Low cytokine responses at birth might be a risk factor for eczema, whereas a variety of adverse environmental exposures contribute to the risk of wheezing in infancy. These findings provide evidence of specificity in the interactions between immune development, environmental exposures, and the development of early features that might predict future asthma.

Preterm infants have deficient monocyte and lymphocyte cytokine responses to group B streptococcus

Group B streptococcus (GBS) is an important cause of early- and late-onset sepsis in the newborn. Preterm infants have markedly increased susceptibility and worse outcomes, but their immunological responses to GBS are poorly defined. We compared mononuclear cell and whole-blood cytokine responses to heat-killed GBS (HKGBS) of preterm infants (gestational age [GA], 26 to 33 weeks), term infants, and healthy adults. We investigated the kinetics and cell source of induced cytokines and quantified HKGBS phagocytosis. HKGBS-induced tumor necrosis factor (TNF) and interleukin 6 (IL-6) secretion was significantly impaired in preterm infants compared to that in term infants and adults. These cytokines were predominantly monocytic in origin, and production was intrinsically linked to HKGBS phagocytosis. Very preterm infants (GA, <30 weeks) had fewer cytokine-producing monocytes, but nonopsonic phagocytosis ability was comparable to that for term infants and adults. Exogenous complement supplementation increased phagocytosis in all groups, as well as the proportion of preterm monocytes producing IL-6, but for very preterm infants, responses were still deficient. Similar defective preterm monocyte responses were observed in fresh whole cord blood stimulated with live GBS. Lymphocyte-associated cytokines were significantly deficient for both preterm and term infants compared to levels for adults. These findings indicate that a subset of preterm monocytes do not respond to GBS, a defect compounded by generalized weaker lymphocyte responses in newborns. Together these deficient responses may increase the susceptibility of preterm infants to GBS infection.

The impact of maternal HIV infection on cord blood lymphocyte subsets and cytokine profile in exposed non-infected newborns

Background

Children born to HIV+ mothers are exposed intra-utero to several drugs and cytokines that can modify the developing immune system, and influence the newborn's immune response to infections and vaccines. We analyzed the relation between the distribution of cord blood lymphocyte subsets and cytokine profile in term newborns of HIV+ mothers using HAART during pregnancy and compared them to normal newborns.

Methods

In a prospective, controlled study, 36 mother-child pairs from HIV+ mothers and 15 HIV-uninfected mothers were studied. Hematological features and cytokine profiles of mothers at 35 weeks of pregnancy were examined. Maternal and cord lymphocyte subsets as well as B-cell maturation in cord blood were analyzed by flow cytometry. The non-stimulated, as well as BCG- and PHA-stimulated production of IL2, IL4, IL7, IL10, IL12, IFN-γ and TNF-alpha in mononuclear cell cultures from mothers and infants were quantified using ELISA.

Results

After one year follow-up none of the exposed infants became seropositive for HIV. An increase in B lymphocytes, especially the CD19/CD5+ ones, was observed in cord blood of HIV-exposed newborns. Children of HIV+ hard drug using mothers had also an increase of immature B-cells. Cord blood mononuclear cells of HIV-exposed newborns produced less IL-4 and IL-7 and more IL-10 and IFN-γ in culture than those of uninfected mothers. Cytokine values in supernatants were similar in infants and their mothers except for IFN-γ and TNF-alpha that were higher in HIV+ mothers, especially in drug abusing ones. Cord blood CD19/CD5+ lymphocytes showed a positive correlation with cord IL-7 and IL-10. A higher maternal age and smoking was associated with a decrease of cord blood CD4+ cells.

Conclusions

in uninfected infants born to HIV+ women, several immunological abnormalities were found, related to the residual maternal immune changes induced by the HIV infection and those associated with antiretroviral treatment. Maternal smoking was associated to changes in cord CD3/CD4 lymphocytes and maternal hard drug abuse was associated with more pronounced changes in the cord B cell line.

Th2 Cytokine Levels Distort the Association of IL-10 and IFN-γ with Allergic Phenotypes

The expression of allergic phenotypes involves complex inter-relationships among several Th2 and Th1 cytokines as well as the regulator cytokine interleukin (IL)-10. These direct or indirect interrelationships may distort the true associations of cytokine responses with these phenotypes. In this study, we aimed to clarify the effects of the regulatory cytokine IL-10 and Th1 cytokine interferon-gamma (IFN-γ) on allergic phenotypes after adjusting for the correlations with Th2 cytokines. After adjusting for Th2 cytokines, IL-10 and IFN-γ were protective against atopy. Adjusted levels of IL-10 and IFN-γ stimulated with house-dust mite (HDM) were significantly lower in atopics than non-atopics, for IL-10 adjusting for IL-5 (P = 0.002), IL-13 (P = 0.012), IL-9 (P = 0.016), and IL-4 (P = 0.043), and for IFN-γ adjusting for IL-5 (P = 0.005), IL-13 (P = 0.005), and IL-9 (P = 0.037). IL-10 and IFN-γ levels stimulated with phytohaemagglutinin (PHA) and staphylococcal enterotoxin B (SEB) exhibited a similar pattern. The adjusted levels of IL-10 and IFN-γ stimulated with HDM, PHA or SEB were all significantly negatively correlated with total serum IgE, except for IFN-γ stimulated with SEB. Levels of Th2 cytokines distort the associations of IL-10 and IFN-γ with allergic phenotypes. Removing the covariance with Th2 cytokines, both IL-10 and IFN-γ were protective against atopy.

Cytokine profiles in asthma families depend on age and phenotype

Background

Circulating cytokine patterns may be relevant for the diagnosis of asthma, for the discrimination of certain phenotypes, and prognostic factors for exacerbation of disease.

Methodology/Principal Findings

In this study we investigated serum samples from 944 individuals of 218 asthma-affected families by a multiplex, microsphere based system detecting at high sensitivity eleven asthma associated mediators: eotaxin (CCL11), granulocyte macrophage stimulating factor (GM-CSF), interferon gamma (IFNγ), interleukin-4 (IL-4), IL-5, IL-8, IL-10, IL-12 (p40), IL-13, IL-17 and tumor necrosis factor alpha (TNFα). Single cytokine levels were largely similar between asthmatic and healthy individuals when analysing asthma as single disease entity. Regulatory differences between parental and pediatric asthma were reflected by six of the eleven mediators analyzed (eotaxin, IL-4, IL-5, IL-10, IL-12, TNFα). IL-12 (p40) and IL-5 were the best predictor for extrinsic asthma in children with an increased odds ratio of 2.85 and 1.96 per log pg/ml increase (IL-12 (p40): 1.2–6.8, p = 0.019, and IL-5: 1.2–2.5, p = 0.025). Frequent asthma attacks in children are associated with elevated IL-5 serum levels (p = 0.013). Cytokine patterns seem to be individually balanced in both, healthy and diseased adults and children, with various cytokines correlating among each other (IL-17 and IFNγ (r_s = 0.67), IL-4 and IL-5 (r_s = 0.55), IFNγ and GM-CSF (r_s = 0.54)).

Conclusion/Significance

Our data support mainly an age- but also an asthma phenotype-dependent systemic immune regulation.

Farm living: effects on childhood asthma and allergy

Numerous epidemiological studies have shown that children who grow up on traditional farms are protected from asthma, hay fever and allergic sensitization. Early-life contact with livestock and their fodder, and consumption of unprocessed cow's milk have been identified as the most effective protective exposures. Studies of the immunobiology of farm living point to activation and modulation of innate and adaptive immune responses by intense microbial exposures and possibly xenogeneic signals delivered before or soon after birth.

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.

Immunological paradigms and the pathogenesis of ovine chlamydial abortion

Successful mammalian pregnancy involves complex immunological interactions between the mother and foetus that are not yet fully understood. A number of immunological paradigms have been established to explain the failure of the maternal immune system to reject the semi-allogeneic foetus, mainly based on studies in mice and humans. However, as placental structure, gestation periods and number of concepti per pregnancy can vary greatly between mammals, it is not always clear how applicable these immunological paradigms are to reproduction in other species. Here, we discuss the predictions of three important immunological paradigms in relation to the pathogenesis of ovine enzootic abortion (OEA), a common cause of infectious abortion in sheep and other ruminants. OEA is caused by the intracellular Gram-negative bacterium Chlamydophila abortus that exhibits a tropism for placental trophoblast. The paradigms of particular relevance to the pathogenesis of OEA are as follows: (i) intracellular bacterial infections are controlled by T(H)1-type CD4(+ve) T cells; (ii) indoleamine 2,3-dioxygenase is expressed in the placenta to prevent immunological rejection of the semi-allogeneic foetus; and (iii) pregnancy is a maternal T(H)2-type phenomenon. We discuss the relevance and validity of these paradigms for chlamydial abortion and reproductive immunology in sheep.

Macroparasites, innate immunity and immunoregulation: developing natural models

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

The inflammatory response to injury in children

PURPOSE OF REVIEW

Severely injured children have a decreased incidence and different pattern of multiple organ failure when compared with adults. This article reviews recent advances in understanding the mechanisms leading to this discrepancy.

RECENT FINDINGS

Post injury, inflammation-related outcomes are age-related, as demonstrated by epidemiological and laboratory investigations that confirm a relative protection from acute lung injury and multiple organ failure in children. The importance of the innate immune system in initiating and regulating the inflammatory response to injury is also increasingly well understood, but relatively little research has focused on the implications of a maturing innate immune system for the inflammatory response to injury in children. The development of age-appropriate immunomodulatory interventions for the prevention and treatment of postinjury inflammatory dysregulation depends on continued investigation of mechanisms responsible for the unique pediatric inflammatory response to trauma.

SUMMARY

The inflammatory response to injury in children is functionally and mechanistically unique, as suggested by age-related differences in the incidence and pattern of systemic inflammation and multiple organ failure after major trauma. We review the current clinical and basic science literature related to postinjury inflammation in childhood, focusing on the developmental biology of innate immunity and the implications of a maturing immune system for trauma-related interventions and outcomes.

Rearing environment affects development of the immune system in neonates

Early-life exposure to appropriate microbial flora drives expansion and development of an efficient immune system. Aberrant development results in increased likelihood of allergic disease or increased susceptibility to infection. Thus, factors affecting microbial colonization may also affect the direction of immune responses in later life. There is a need for a manipulable animal model of environmental influences on the development of microbiota and the immune system during early life. We assessed the effects of rearing under low- (farm, sow) and high-hygiene (isolator, milk formula) conditions on intestinal microbiota and immune development in neonatal piglets, because they can be removed from the mother in the first 24 h for rearing under controlled conditions and, due to placental structure, neither antibody nor antigen is transferred in utero. Microbiota in both groups was similar between 2 and 5 days. However, by 12-28 days, piglets reared on the mother had more diverse flora than siblings reared in isolators. Dendritic cells accumulated in the intestinal mucosa in both groups, but more rapidly in isolator piglets. Importantly, the minority of 2-5-day-old farm piglets whose microbiota resembled that of an older (12-28-day-old) pig also accumulated dendritic cells earlier than the other farm-reared piglets. Consistent with dendritic cell control of T cell function, the effects on T cells occurred at later time-points, and mucosal T cells from high-hygiene, isolator pigs made less interleukin (IL)-4 while systemic T cells made more IL-2. Neonatal piglets may be a valuable model for studies of the effects of interaction between microbiota and immune development on allergy.

Genetics and epidemiology: asthma and infection

PURPOSE OF REVIEW

This review will consider how recent epidemiological studies have helped reveal the role of respiratory infection in asthma inception early in life. We will also review the importance of respiratory infections and exacerbations of asthma and will discuss genetic factors controlling host immune responses to respiratory infection and the influence these may exert on asthma pathogenesis.

RECENT FINDINGS

Birth cohort studies have demonstrated bidirectional relationships between early life severe respiratory infections and asthma development; however, whether there is a clear causal role for severe respiratory infection early in life leading directly to asthma development remains unknown. The role of rhinovirus infection in asthma exacerbations has been investigated experimentally, with asthmatic patients exhibiting greater clinical illness severity, which was related to increased virus load and lower airways inflammation. Polymorphisms in genes involved in innate, antiviral and Th1 and Th2 immune responses have been linked to asthma as well as to early life severe respiratory infections, suggesting that host factors are likely to play an important role in their association.

SUMMARY

Early in life, such genetic factors contribute to the risk of severe lower respiratory tract viral infection as well as later development of wheezing illness and asthma. Respiratory viruses are also the most frequent cause of asthma exacerbations at all ages.

Potential immunomodulatory role of VIP in the implantation sites of prediabetic nonobese diabetic mice

Among several factors known to modulate embryo implantation and survival, uterine quiescence and neovascularization, maternal immunotolerance through the Th1/Th2 cytokine balance towards a Th2 profile, local regulatory T-cell (Treg) activation, and high levels of progesterone were assigned a prominent role. Vasoactive intestinal peptide (VIP) is a neuroimmunopeptide that has anti-inflammatory effects, promotes Th2 cytokines and CD4+CD25+FOXP3+Treg activation, and stimulates exocrine secretion, smooth muscle relaxation, and vasodilatation favoring uterus quiescence. The goal of the present work was to explore the participation of VIP in the implantation sites of normal and pregnant prediabetic nonobese diabetic (NOD) females, a mouse strain that spontaneously develops an autoimmune exocrinopathy similar to Sjögren's syndrome. Our results indicate a reduction in litter size from the third parturition onwards in the NOD female lifespan with increased resorption rates. Progesterone systemic levels were significantly decreased in pregnant NOD mice compared with BALB/c mice, although the allogeneic response to progesterone by spleen cells was not impaired. VIP receptors,Vipr1andVipr2(Vpac1andVpac2), were expressed at the implantation sites and VIP induced leukemia inhibitory factor (LIF) and Treg marker expression in both strains; however, a reducedVipexpression was found in NOD implantation sites. We conclude that the reduced birth rate at 16-week-old NOD mice with a Th1 systemic cytokine profile involves resorption processes with a lower expression of VIP at the sites of implantation, which acts as a local inducer of pro-implantatory LIF and Treg activation.