Exposure to a farm environment is associated with T helper 1 and regulatory cytokines at age 4.5 years

Deciphering the Interplay between the Epithelial Barrier, Immune Cells, and Metabolic Mediators in Allergic Disease

Chronic exposure to harmful pollutants, chemicals, and pathogens from the environment can lead to pathological changes in the epithelial barrier, which increase the risk of developing an allergy. During allergic inflammation, epithelial cells send proinflammatory signals to group 2 innate lymphoid cell (ILC2s) and eosinophils, which require energy and resources to mediate their activation, cytokine/chemokine secretion, and mobilization of other cells. This review aims to provide an overview of the metabolic regulation in allergic asthma, atopic dermatitis (AD), and allergic rhinitis (AR), highlighting its underlying mechanisms and phenotypes, and the potential metabolic regulatory roles of eosinophils and ILC2s. Eosinophils and ILC2s regulate allergic inflammation through lipid mediators, particularly cysteinyl leukotrienes (CysLTs) and prostaglandins (PGs). Arachidonic acid (AA)-derived metabolites and Sphinosine-1-phosphate (S1P) are significant metabolic markers that indicate immune dysfunction and epithelial barrier dysfunction in allergy. Notably, eosinophils are promoters of allergic symptoms and exhibit greater metabolic plasticity compared to ILC2s, directly involved in promoting allergic symptoms. Our findings suggest that metabolomic analysis provides insights into the complex interactions between immune cells, epithelial cells, and environmental factors. Potential therapeutic targets have been highlighted to further understand the metabolic regulation of eosinophils and ILC2s in allergy. Future research in metabolomics can facilitate the development of novel diagnostics and therapeutics for future application.

Immune modulation by rural exposures and allergy protection

BACKGROUND

Growing up on traditional farms protects children from the development of asthma and allergies. However, we have identified distinct asthma-protective factors, such as poultry exposure. This study aims to examine the biological effect of rural exposure in China.

METHODS

We recruited 67 rural children (7.4 ± 0.9 years) and 79 urban children (6.8 ± 0.6 years). Depending on the personal history of exposure to domestic poultry (DP), rural children were further divided into those with DP exposure (DP+ , n = 30) and those without (DP- , n = 37). Blood samples were collected to assess differential cell counts and expression of immune-related genes. Dust samples were collected from poultry stables inside rural households. In vivo activities of nasal administration of DP dust extracts were tested in an ovalbumin-induced asthma model.

RESULTS

There was a stepwise increase in the percentage of eosinophils (%) from rural DP+ children (median = 1.65, IQR = [1.28, 3.75]) to rural DP- children (3.40, [1.70, 6.50]; DP+ vs. DP- , p = .087) and to the highest of their urban counterparts (4.00, [2.00, 7.25]; urban vs. DP+ , p = .017). Similarly, rural children exhibited reduced mRNA expression of immune markers, both at baseline and following lipopolysaccharide (LPS) stimulation. Whereas LPS stimulation induced increased secretion of Th1 and proinflammatory cytokines in rural DP+ children compared to rural DP- children and urban children. Bronchoalveolar lavage of mice with intranasal instillation of dust extracts from DP household showed a significant decrease in eosinophils as compared to those of control mice (p < .05). Furthermore, DP dust strongly inhibited gene expression of Th2 signature cytokines and induced IL-17 expression in the murine asthma model.

CONCLUSIONS

Immune responses of rural children were dampened compared to urban children and those exposed to DP had further downregulated immune responsiveness. DP dust extracts ameliorated Th2-driven allergic airway inflammation in mice. Determining active protective components in the rural environment may provide directions for the development of primary prevention of asthma.

A prospective study of the association between living in a rural environment during childhood and risk of psoriasis

Psoriasis is one of the most common immune-mediated inflammatory diseases (IMIDs). Living in a rural environment during childhood is associated with a decreased risk of certain IMIDs, like asthma, in adulthood. However, its role in other IMIDs, such as psoriasis is still unclear. To evaluate the relationships between different factors related to the environment during childhood and the risk of psoriasis in adulthood we conducted a study in E3N, a French prospective cohort composed of 98 995 women. During the 1990-2018 follow-up of 72 154 study participants, we identified 1 967 incident cases of psoriasis from self-reports in self-administered structured questionnaires. During the 2004-2018 follow-up of 67 917 study participants, 188 moderate-to-severe cases of psoriasis were identified through self-reports and from data from a drug reimbursement database. We fitted Cox proportional hazards regression models with age as the time scale from which we estimated hazard ratios adjusted for putative confounders (aHRs). We found inverse associations with risk of psoriasis for rural birthplace [aHR: 0.89 (95%CI: 0.79-0.96)] and for having farming parents [aHR: 0.84 (95%CI: 0.72-0.97)]. For moderate-to-severe psoriasis we found a nominally similar inverse association with rural birthplace but not with having farming parents. Our results suggest that an exposure to a rural environment during childhood may be associated with a reduced risk of psoriasis. These findings may help to improve our understanding of the pathogenesis of psoriasis.

Cattle farm dust alters cytokine levels in human airway construct model

Epidemiological studies have revealed some alterations in systemic immunity that associate with farm exposure and the risk of respiratory diseases, but in vitro studies focusing on immunological responses in the airways are scarce. Our aim was to assess how cowshed dust affects the integrity and inflammation of human airway tissue in vitro. Cowshed dust samples were collected from four different dairy farms. Lung tissue constructs were exposed to dust samples in air-liquid interface. Transepithelial resistance of the tissue, secreted proteins, and a panel of pro-inflammatory cytokines, growth factors, and chemokines were analysed. Cowshed dust stimulation was associated mainly with increased production of IL-13, IL-15, IP-10 and IFN-γ. Some differences between farms were seen. Only one farm dust sample induced a significant change in transepithelial resistance, whereas dust from two of the farms induced the secretion of proteins. The exposure to cowshed dust affected protein and cytokine secretion, but the response profiles were not uniform between farms. The effect on tight junction dynamics was less pronounced, suggesting the relevance of soluble factors in induced responses in the airways. Our results indicate that in addition to farm type, the contribution of cowshed characteristics to dust composition and its immunomodulatory properties should be taken into account.

What Have Mechanistic Studies Taught Us About Childhood Asthma?

Childhood asthma is a chronic heterogeneous syndrome consisting of different disease entities or phenotypes. The immunologic and cellular processes that occur during asthma development are still not fully understood but represent distinct endotypes. Mechanistic studies have examined the role of gene expression, protein levels, and cell types in early life development and the manifestation of asthma, many under the influence of environmental stimuli, which can be both protective and risk factors for asthma. Genetic variants can regulate gene expression, controlled partly by different epigenetic mechanisms. In addition, environmental factors, such as living space, nutrition, and smoking, can contribute to these mechanisms. All of these factors produce modifications in gene expression that can alter the development and function of immune and epithelial cells and subsequently different trajectories of childhood asthma. These early changes in a partially immature immune system can have dramatic effects (e.g., causing dysregulation), which in turn contribute to different disease endotypes and may help to explain differential responsiveness to asthma treatment. In this review, we summarize published studies that have aimed to uncover distinct mechanisms in childhood asthma, considering genetics, epigenetics, and environment. Moreover, a discussion of new, powerful tools for single-cell immunologic assays for phenotypic and functional analysis is included, which promise new mechanistic insights into childhood asthma development and therapeutic and preventive strategies.

Early exposure to farm dust in an allergic airway inflammation rabbit model: Does it affect bronchial and cough hyperresponsiveness?

INTRODUCTION

Over the past 50 years, the prevalence of allergic respiratory diseases has been increasing. The Hygiene hypothesis explains this progression by the decrease in the bio-diversity of early microbial exposure. This study aims to evaluate the effect of early-life farm exposure on airway hyperresponsiveness and cough hypersensitivity in an allergic airway inflammation rabbit model.

METHOD

A specific environment was applied to pregnant rabbits and their offspring until six weeks after birth. Rabbits were housed in a pathogen-free zone for the control group and a calf barn for the farm group. At the end of the specific environmental exposure, both groups were then housed in a conventional zone and then sensitized to ovalbumin. Ten days after sensitization, the rabbit pups received ovalbumin aerosols to provoke airway inflammation. Sensitization to ovalbumin was assessed by specific IgE assay. Cough sensitivity was assessed by mechanical stimulation of the trachea, and bronchial reactivity was assessed by methacholine challenge. The farm environment was characterized by endotoxin measurement.

RESULTS

A total of 38 rabbit pups were included (18 in the farm group). Endotoxin levels in the farm environment varied from 30 to 1854 EU.m-3. There was no significant difference in specific IgE values to ovalbumin (p = 0.826) between the two groups. The mechanical threshold to elicit a cough did not differ between the two groups (p = 0.492). There was no difference in the number of cough (p = 0.270) or the intensity of ventilatory responses (p = 0.735). After adjusting for age and weight, there was no difference in respiratory resistance before and after methacholine challenge.

CONCLUSION

Early exposure to the calf barn did not affect cough sensitivity or bronchial reactivity in ovalbumin-sensitized rabbits. These results suggest that not all farm environments protect against asthma and atopy. Continuous exposure to several sources of microbial diversity is probably needed.

Environmental influences on childhood allergies and asthma - The Farm effect

Asthma and allergies are major health problems and exert an enormous socioeconomic burden. Besides genetic predisposition, environmental factors play a crucial role in the development of these diseases in childhood. Multiple worldwide epidemiological studies have shown that children growing up on farms are immune to allergic diseases and asthma. Farm-related exposures shape children's immune homeostasis, via mediators such as N-glycolylneuraminic acid or arabinogalactan, or by diverse environmental microbes. Moreover, nutritional factors, such as breastfeeding or farm milk and food diversity, inducing short-chain fatty acids-producing bacteria in the intestine, contribute to farm-related effects. All farm-related exposures induce an anti-inflammatory response of the innate immunity and increase the differentiation of regulatory T cells and T helper cell type 1. A better understanding of the components of the farm environment, that are protective to the development of allergy and asthma, and their underlying mechanisms, will help to develop new strategies for the prevention of allergy and asthma.

Effect of Acinetobacter lwoffii on the modulation of macrophage activation and asthmatic inflammation

BACKGROUND

Although lung macrophages are directly exposed to external stimuli, their exact immunologic roles in asthma are still largely unknown. The aim of this study was to investigate the anti-asthmatic effect of Acinetobacter lwoffii in terms of lung macrophage modulation.

METHODS

Six-week-old female BALB/c mice were sensitized and challenged with ovalbumin (OVA) with or without intranasal administration of A. lwoffii during the sensitization period. Airway hyperresponsiveness and inflammation were evaluated. Using flow cytometry, macrophages were subclassified according to their activation status. In the in vitro study, a murine alveolar macrophage cell line (MH-S) treated with or without A. lwoffii before IL-13 stimulation were analysed by quantitative RT-PCR.

RESULTS

In a murine asthma model, the number of inflammatory cells, including macrophages and eosinophils, decreased in mice treated with A. lwoffii (A. lwoffii/OVA group) compared with untreated mice (OVA group). The enhanced expression of MHCII in macrophages in the OVA group was decreased by A. lwoffii treatment. M2 macrophage subtypes were significantly altered. A. lwoffii treatment decreased CD11b⁺ M2a and CD11b⁺ M2c macrophages, which showed strong positive correlations with Th2 cells, ILC2 and eosinophils. In contrast, CD11b⁺ M2b macrophages were significantly increased by A. lwoffii treatment and showed strong positive correlations with ILC1 and ILC3. In vitro, A. lwoffii down-regulated the expression of M2 markers related but up-regulated those related to M2b macrophages.

CONCLUSIONS AND CLINICAL RELEVANCE

Intranasal A. lwoffii exposure suppresses asthma development by suppressing the type 2 response via modulating lung macrophage activation, shifting M2a and M2c macrophages to M2b macrophages.

Protection against allergies: Microbes, immunity, and the farming effect

The prevalence of asthma and other allergic diseases has rapidly increased in "Westernized" countries over recent decades. This rapid increase suggests the involvement of environmental factors, behavioral changes or lifestyle, rather than genetic drift. It has become increasingly clear that the microbiome plays a key role in educating the host immune system and, thus, regulation of disease susceptibility. This review will focus on recent advances uncovering immunological and microbial mechanisms that protect against allergies, in particular, within the context of a farming environment. A whole body of epidemiological data disclosed the nature of the protective exposures in a farm. Current evidence points toward an important role of the host microbiome in setting an immunological equilibrium that determines progression toward, or protection against allergic diseases. Conclusive mechanistic insights on how microbial exposures prevent from developing allergic diseases in humans are still lacking but findings from experimental models reveal plausible immunological mechanisms. Gathering further knowledge on these mechanisms and confirming their relevance in humans is of great importance to develop preventive strategies for children at risk of developing allergies.

Nutritional Factors in Occupational Lung Disease

PURPOSE OF REVIEW

Lung diseases such as asthma and COPD are major public health issues and related to occupational exposures. While therapies to limit the development and progression of these diseases are limited, nutrition interventions could offer potential alternatives to mediate the inflammation associated with these diseases. This is a narrative review of the current state of relevant nutrients on inflammation and respiratory outcomes associated with occupational exposures.

RECENT FINDINGS

Relevant nutrients that have been investigated in recent years include omega-3 polyunsaturated fatty acids, zinc, vitamin D, dairy products, and antioxidants. These nutrients have demonstrated the potential to prevent or modify the adverse outcomes associated with occupational exposures, primarily in preclinical studies. Current therapies for respiratory consequences associated with occupational exposures are limited; therefore, addressing strategies for reducing inflammation is important in improving quality of life and limiting health care costs. More human studies are warranted to determine the effectiveness of nutrition as an intervention.

How a farming environment protects from atopy

It is now well established that the exposure to certain environments such as farms has the potential to protect from the development of allergies later in life. This protection is achieved when repeated exposure to the farming environment occurs early in life, but persists when children spend sufficient amount of time in contact with livestock and hay, and drink unpasteurized milk. The capacity of farm dust to protect from allergy development lies, amongst others, in the microbe composition in the farm. These protective microbes release various metabolites and cell wall components that change farmers' home dust composition, when compared to urbanized home dust. Additionally, they can colonize various barrier sites (skin, lung, intestine) in farmers' children, leading to persistent changes in the way their immune system and their barrier cells respond to environmental allergens.

Integrating farm and air pollution studies in search for immunoregulatory mechanisms operating in protective and high-risk environments

BACKGROUND

Studies conducted in farm environments suggest that diverse microbial exposure promotes children's lung health. The underlying mechanisms are unclear, and the development of asthma-preventive strategies has been delayed. More comprehensive investigation of the environment-induced immunoregulation is required for better understanding of asthma pathogenesis and prevention. Exposure to air pollution, including particulate matter (PM), is a risk factor for asthma, thus providing an excellent counterpoint for the farm-effect research. Lack of comparable data, however, complicates interpretation of the existing information. We aimed to explore the immunoregulatory effects of cattle farm dust (protective, Finland) and urban air PM (high-risk, China) for the first time using identical research methods.

METHODS

We stimulated PBMCs of 4-year-old children (N = 18) with farm dust and size-segregated PM and assessed the expression of immune receptors CD80 and ILT4 on dendritic cells and monocytes as well as cytokine production of PBMCs. Environmental samples were analysed for their composition.

RESULTS

Farm dust increased the percentage of cells expressing CD80 and the cytokine production of children's immune cells, whereas PM inhibited the expression of important receptors and the production of soluble mediators. Although PM samples induced parallel immune reactions, the size-fraction determined the strength of the effects.

CONCLUSIONS

Our study demonstrates the significance of using the same research framework when disentangling shared and distinctive immune pathways operating in different environments. Observed stimulatory effects of farm dust and inhibitory effects of PM could shape responses towards respiratory pathogens and allergens, and partly explain differences in asthma prevalence between studied environments.

Recent Trends in Unpasteurized Fluid Milk Outbreaks, Legalization, and Consumption in the United States

Introduction: Determining the potential risk of foodborne illness has become critical for informing policy decisions, due to the increasing availability and popularity of unpasteurized (raw) milk.

Methods: Trends in foodborne illnesses reported to the Centers for Disease Control in the United States from 2005 to 2016 were analyzed, with comparison to state legal status and to consumption, as estimated by licensing records.

Results: The rate of unpasteurized milk-associated outbreaks has been declining since 2010, despite increasing legal distribution. Controlling for growth in population and consumption, the outbreak rate has effectively decreased by 74% since 2005.

Discussion: Studies of the role of on-farm food safety programs to promote the further reduction of unpasteurized milk outbreaks should be initiated, to investigate the efficacy of such risk management tools.

[Environmental pollutants as adjuvant factors of immune system derived diseases]

The main task of the immune system is to protect the body against invading pathogens. To be able to do so, immune cells must be able to recognize and combat exogenous challenges and at the same time tolerate body-borne structures. A complex regulatory network controls the sensitive balance between defense and tolerance. Perturbation of this network ultimately leads to the development of chronic inflammation, such as allergies, autoimmune reactions, and infections, because the immune system is no longer able to efficiently eliminate invading pathogens. Environmental pollutants can cause such perturbations by affecting the function of immune cells in such a way that they would react hypersensitively against allergens and the body's own structures, respectively, or that they would be no longer able to adequately combat pathogens. This indirect effect is also known as adjuvant effect. For pesticides, heavy metals, wood preservatives, or volatile organic compounds such adjuvant effects are well known. Examples of the mechanism by which environmental toxins contribute to chronic inflammatory diseases are manifold and will be discussed along asthma and allergies.While the immune system of healthy adults is typically well able to distinguish between foreign and endogenous substances even under adverse environmental conditions, that of children would react much more sensible upon comparable environmental challenges. To prevent priming for diseases by environmental cues during that highly sensitive period of early childhood children are to be particularly protected.

The Interactive Roles of Lipopolysaccharides and dsRNA/Viruses on Respiratory Epithelial Cells and Dendritic Cells in Allergic Respiratory Disorders: The Hygiene Hypothesis

The original hygiene hypothesis declares "more infections in early childhood protect against later atopy". According to the hygiene hypothesis, the increased incidence of allergic disorders in developed countries is explained by the decrease of infections. Epithelial cells and dendritic cells play key roles in bridging the innate and adaptive immune systems. Among the various pattern-recognition receptor systems of epithelial cells and dendritic cells, including toll-like receptors (TLRs), nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) and others, TLRs are the key systems of immune response regulation. In humans, TLRs consist of TLR1 to TLR10. They regulate cellular responses through engagement with TLR ligands, e.g., lipopolysaccharides (LPS) acts through TLR4 and dsRNA acts through TLR3, but there are certain common components between these two TLR pathways. dsRNA activates epithelial cells and dendritic cells in different directions, resulting in allergy-related Th2-skewing tendency in epithelial cells, and Th1-skewing tendency in dendritic cells. The Th2-skewing effect by stimulation of dsRNA on epithelial cells could be suppressed by the presence of LPS above some threshold. When LPS level decreases, the Th2-skewing effect increases. It may be via these interrelated networks and related factors that LPS modifies the allergic responses and provides a plausible mechanism of the hygiene hypothesis. Several hygiene hypothesis-related phenomena, seemingly conflicting, are also discussed in this review, along with their proposed mechanisms.

Epithelial Cell Regulation of Allergic Diseases

Allergic diseases, which have escalated in prevalence in recent years, arise as a result of maladaptive immune responses to ubiquitous environmental stimuli. Why only certain individuals mount inappropriate type 2 immune responses to these otherwise harmless allergens has remained an unanswered question. Mounting evidence suggests that the epithelium, by sensing its environment, is the central regulator of allergic diseases. Once considered to be a passive barrier to allergens, epithelial cells at mucosal surfaces are now considered to be the cornerstone of the allergic diathesis. Beyond their function as maintaining barrier at mucosal surfaces, mucosal epithelial cells through the secretion of mediators like IL-25, IL-33, and TSLP control the fate of downstream allergic immune responses. In this review, we will discuss the advances in recent years regarding the process of allergen recognition and secretion of soluble mediators by epithelial cells that shape the development of the allergic response.

Differences between preschoolers with asthma and allergies in urban and rural environments

OBJECTIVE

Previous studies have provided conflicting results about how living in a rural or urban environment influences schoolchildren with asthma and allergic diseases in different ways. The aim of the present study was to evaluate if recurrent wheezing preschoolers from rural or urban areas differ in asthma, allergic diseases, and atopy.

METHODS

A cross-sectional-study in Rafaela, Argentina, on 143 preschoolers with recurrent wheezing from rural and urban settings was performed (2010-2012). Diagnosis of asthma (by positive asthma predictive index [API]), allergic diseases (rhinitis, dermatitis), and atopy (by skin prick test [SPT], peripheral blood eosinophils, and serum total IgE) were assessed.

RESULTS

Preschoolers from rural settings had significantly higher prevalence of vaginal delivery, longer breastfeeding, earlier onset of wheezing, more parental smoking, siblings, shared a bedroom, and more exposure to chemicals used in plant fumigation or farm animals, and unpasteurized milk consumption, in comparison to preschoolers living in urban setting. In contrast, preschoolers from urban areas had significantly higher prevalence of parental history of allergy, positive skin prick test, and positive API. After multivariate analysis adjusting for covariates, maternal smoking [odds ratio (OR) = 3.44] and positive SPT (OR = 5.57) significantly increase the risk of asthma diagnosis (positive API); in contrast, living in rural setting (OR = 0.04), and having more siblings (OR = 0.51) decrease their risk.

CONCLUSIONS

Recurrent wheezing preschoolers from rural areas had a significant inverse odds of being diagnosed with asthma (type-2 inflammation) when compared to those from urban areas. Exposure to farm animals and consumption of unpasteurized milk might have a role.

Raw milk consumption and other early-life farm exposures and adult pulmonary function in the Agricultural Lung Health Study

Literature suggests that early exposure to the farming environment protects against atopy and asthma; few studies have examined pulmonary function. We evaluated associations between early-life farming exposures and pulmonary function in 3061 adults (mean age=63) from a US farming population using linear regression. Childhood raw milk consumption was associated with higher FEV₁ (β=49.5 mL, 95% CI 2.8 to 96.1 mL, p=0.04) and FVC (β=66.2 mL, 95% CI 13.2 to 119.1 mL, p=0.01). We did not find appreciable associations with other early-life farming exposures. We report a novel association between raw milk consumption and higher pulmonary function that lasts into older adulthood.

Rural residence, farming environment, and allergic diseases in Argentinean adolescents

RATIONALE

Little is known about residence in a rural or farming environment and allergic diseases in Latin America.

METHODS

Cross-sectional study of rural residence and current wheeze, current asthma and current symptoms of allergic rhino-conjunctivitis in 1,804 adolescents (ages 13-14 years) attending 31 schools in urban and rural areas of San Francisco (Córdoba, Argentina). Rural residence was classified as never, previous, and current. Duration of rural residence was categorized as 0, >0 but ≤5 years, and >5 years. Current wheeze, current asthma, and current allergic rhino-conjunctivitis were defined on the basis of responses to an extensively validated questionnaire from the International Study of Asthma and Allergies in Childhood. Logistic regression was used for the multivariable analysis of rural residence and the outcomes of interest.

RESULTS

After adjustment for current smoking and other covariates, current rural residence (odds ratio [OR] = 0.15, 95% confidence interval [CI] = 0.03-0.81) and rural residence for >5 years (OR = 0.32, 95%CI = 0.12-0.84) were significantly associated with reduced odds of current wheeze. In a multivariable analysis, current residence in a rural area (OR = 0.52, 95%CI = 0.32-0.86) and rural residence for >5 years (OR = 0.44, 95%CI = 0.26-0.73) were significantly associated with reduced odds of allergic rhino-conjunctivitis. This association was no longer significant after additional adjustment for current residence in a dairy farm, which was significantly associated with reduced odds of allergic rhino-conjunctivitis. Similarly, current regular contact with farm animals was significantly associated with reduced odds of allergic rhino-conjunctivitis.

CONCLUSIONS

Among Argentinean adolescents, current rural residence and rural residence for >5 years were associated with reduced odds of current wheeze and allergic rhino-conjunctivitis. These potential protective effects may be explained by a dairy farm environment, including regular contact with farm animals. Pediatr Pulmonol. 2017;52:21-28. © 2016 Wiley Periodicals, Inc.

Humoral immune factors and asthma among American Indian children: a case-control study

Background

Asthma is recognized as intimately related to immunologic factors and inflammation, although there are likely multiple phenotypes and pathophysiologic pathways. Biomarkers of inflammation may shed light on causal factors and have potential clinical utility. Individual and population genetic factors are correlated with risk for asthma and improved understanding of these contributions could improve treatment and prevention of this serious condition.

Methods

A population-based sample of 108 children with clinically defined asthma and 216 control children were recruited from a small community in the northern plains of the United States. A complete blood count, high sensitivity C-reactive protein, total IgE and specific antibodies to 5 common airborne antigens (CAA), in addition to basic demographic and anthropomorphic data were obtained. Logistic regression was primarily used to determine the association between these humoral factors and risk of asthma.

Results

The body mass index (BMI) of those with asthma and their total leukocyte counts, percentage of eosinophils, and levels of total IgE were all greater than corresponding control values in univariate analysis. The presence of detectable, specific IgE antibodies to five common airborne antigens was more likely among cases compared with controls. In multivariate analysis, total IgE was independently associated with asthma; but not after inclusion of a cumulative measure of specific IgE sensitization.

Conclusion

Many previously reported associations between anthropomorphic and immune factors and increased risk of asthma appear to be also present in this American Indian population. In this community, asthma is strongly associated with sensitization to CAA.

Delayed adaptive immunity is related to higher MMR vaccine-induced antibody titers in children

There are notable inter-individual variations in vaccine-specific antibody responses in vaccinated children. The aim of our study was to investigate whether early-life environmental factors and adaptive immune maturation prior and close to measles–mumps–rubella (MMR) immunization relate to magnitudes of vaccine-specific antibody titers. In the FARMFLORA birth cohort, including both farming and non-farming families, children were immunized with the MMR vaccine at 18 months of age. MMR vaccine-induced antibody titers were measured in plasma samples obtained at 36 months of age. Infants' blood samples obtained at birth, 3–5 days and at 4 and 18 months of age were analyzed for T- and B-cell numbers, proportions of naive and memory T and B cells, and fractions of putative regulatory T cells. Multivariate factor analyses show that higher anti-MMR antibody titers were associated with a lower degree of adaptive immune maturation, that is, lower proportions of memory T cells and a lower capacity of mononuclear cells to produce cytokines, but with higher proportions of putative regulatory T cells. Further, children born by cesarean section (CS) had significantly higher anti-measles titers than vaginally-born children; and CS was found to be associated with delayed adaptive immunity. Also, girls presented with significantly higher anti-mumps and anti-rubella antibody levels than boys at 36 months of age. These results indicate that delayed adaptive immune maturation before and in close proximity to immunization seems to be advantageous for the ability of children to respond with higher anti-MMR antibody levels after vaccination.