Arabinogalactan isolated from cowshed dust extract protects mice from allergic airway inflammation and sensitization

The Microbiota and Equine Asthma: An Integrative View of the Gut-Lung Axis

Both microbe-microbe and host-microbe interactions can have effects beyond the local environment and influence immunological responses in remote organs such as the lungs. The crosstalk between the gut and the lungs, which is supported by complex connections and intricate pathways, is defined as the gut-lung axis. This review aimed to report on the potential role of the gut-lung gut-lung axis in the development and persistence of equine asthma. We summarized significant determinants in the development of asthma in horses and humans. The article discusses the gut-lung axis and proposes an integrative view of the relationship between gut microbiota and asthma. It also explores therapies for modulating the gut microbiota in horses with asthma. Improving our understanding of the horse gut-lung axis could lead to the development of techniques such as fecal microbiota transplants, probiotics, or prebiotics to manipulate the gut microbiota specifically for improving the management of asthma in horses.

Microbes little helpers and suppliers for therapeutic asthma approaches

Bronchial asthma is a prevalent and increasingly chronic inflammatory lung disease affecting over 300 million people globally. Initially considered an allergic disorder driven by mast cells and eosinophils, asthma is now recognized as a complex syndrome with various clinical phenotypes and immunological endotypes. These encompass type 2 inflammatory endotypes characterized by interleukin (IL)-4, IL-5, and IL-13 dominance, alongside others featuring mixed or non-eosinophilic inflammation. Therapeutic success varies significantly based on asthma phenotypes, with inhaled corticosteroids and beta-2 agonists effective for milder forms, but limited in severe cases. Novel antibody-based therapies have shown promise, primarily for severe allergic and type 2-high asthma. To address this gap, novel treatment strategies are essential for better control of asthma pathology, prevention, and exacerbation reduction. One promising approach involves stimulating endogenous anti-inflammatory responses through regulatory T cells (Tregs). Tregs play a vital role in maintaining immune homeostasis, preventing autoimmunity, and mitigating excessive inflammation after pathogenic encounters. Tregs have demonstrated their ability to control both type 2-high and type 2-low inflammation in murine models and dampen human cell-dependent allergic airway inflammation. Furthermore, microbes, typically associated with disease development, have shown immune-dampening properties that could be harnessed for therapeutic benefits. Both commensal microbiota and pathogenic microbes have demonstrated potential in bacterial-host interactions for therapeutic purposes. This review explores microbe-associated approaches as potential treatments for inflammatory diseases, shedding light on current and future therapeutics.

Nuts, vegetables, fruits, and protein dietary pattern during pregnancy is inversely associated with risk of childhood allergies: a case-control study

Allergic diseases are prevalent chronic conditions among children and can lead to significant health and economic issues. It is hypothesized that healthy and high quality diet during pregnancy can prevent the onset of allergic diseases in offspring. This study aimed to investigate the potential relationship between major dietary patterns during pregnancy and allergies in children under one year of age. This case-control study was conducted involving 244 participants (122 mothers of allergic children and 122 healthy controls) who visited pediatricians and allergy outpatient clinics in Khuzestan Province, Iran, between June 2022 and March 2023. Demographic information was recorded using a socio-demographic questionnaire. A food frequency questionnaire was used to identify the foods consumed during pregnancy. Major dietary patterns were extracted using principal component analysis, and the potential relationship between these patterns and childhood allergies was investigated using multivariable logistic regression models. The crude odds ratio (OR) analysis showed that the fourth quartile of "Nut, vegetables, fruits, and protein" dietary pattern was associated with lower occurrence of childhood allergies (OR: 0.214, 95% CI = 0.068-0.679; P trend = 0.211). After adjusting for cofactors in Model 3, this association was still observed in the fourth quartile (OR = 0.108, 95% CI = 0.019-0.613; P trend, 0.001). However, no significant association was observed between "Carbohydrate and cereals" and "Salty" dietary patterns and childhood allergies. The study findings suggest that a maternal dietary pattern rich in nuts, vegetables, and fruits during pregnancy may reduce the risk of allergic diseases in offspring.

Phytochemicals as treatment for allergic asthma: Therapeutic effects and mechanisms of action

BACKGROUND

Allergic asthma is an inflammatory disease caused by the immune system's reaction to allergens, inflammation and narrowing of the airways, and the production of more than normal mucus. One of the main reasons is an increased production of inflammatory cytokines in the lungs that leads to the appearance of symptoms of asthma, including inflammation and shortness of breath. On the other hand, it has been proven that phytochemicals with their antioxidant and anti-inflammatory properties can be useful in improving allergic asthma.

PURPOSE

Common chemical treatments for allergic asthma include corticosteroids, which have many side effects and temporarily relieve symptoms but are not a cure. Therefore, taking the help of natural compounds to improve the quality of life of asthmatic patients can be a valuable issue that has been evaluated in the present review.

STUDY DESIGN AND METHODS

In this study, three databases (Scopus, PubMed, and Cochrane) with the keywords: allergic asthma, phytochemical, plant, and herb were evaluated. The primary result was 5307 articles. Non-English, repetitive, and review articles were deleted from the study.

RESULTS AND DISCUSSION

Finally, after carefully reading the articles, 102 were included in the study (2006-2022). The results of this review state that phytochemicals suppress the inflammatory pathways via inhibition of inflammatory cytokines production/secretion, genes, and proteins involved in the inflammation process, reducing oxidative stress indicators and symptoms of allergic asthma, such as cough and mucus production in the lungs.

CONCLUSION

With their antioxidant effects, this study concluded that phytochemicals suppress cytokines and other inflammatory indicators and thus can be considered an adjunctive treatment for improving allergic asthma.

Regioselective and Stereospecific β-Arabinofuranosylation by Boron-Mediated Aglycon Delivery

Regio- and stereoselective formation of the 1,2-cis-furanosidic linkage has been in great demand for efficient synthesis of biologically active natural glycosides. In this study, we developed a regioselective and β-stereospecific d-/l-arabinofuranosylation promoted by a boronic acid catalyst under mild conditions. The glycosylations proceeded smoothly for a variety of diols, triols, and unprotected sugar acceptors to give the corresponding β-arabinofuranosides (β-Arbf) in high yields with complete β-stereoselectivity and high regioselectivity. The regioselectivity was completely reversed depending on the optical isomerism of the donor used and was predictable a priori using predictive models. Mechanistic studies based on DFT calculations revealed that the present glycosylation occurs through a highly dissociative concerted SN i mechanism. The usefulness of the glycosylation method was demonstrated by the chemical synthesis of trisaccharide structures of arabinogalactan fragments.

Asthma-protective agents in dust from traditional farm environments

BACKGROUND

Growing up on traditional European or US Amish dairy farms in close contact with cows and hay protects children against asthma, and airway administration of extracts from dust collected from cowsheds of those farms prevents allergic asthma in mice.

OBJECTIVES

This study sought to begin identifying farm-derived asthma-protective agents.

METHODS

Our work unfolded along 2 unbiased and independent but complementary discovery paths. Dust extracts (DEs) from protective and nonprotective farms (European and Amish cowsheds vs European sheep sheds) were analyzed by comparative nuclear magnetic resonance profiling and differential proteomics. Bioactivity-guided size fractionation focused on protective Amish cowshed DEs. Multiple in vitro and in vivo functional assays were used in both paths. Some of the proteins thus identified were characterized by in-solution and in-gel sodium dodecyl sulfate-polyacrylamide gel electrophoresis enzymatic digestion/peptide mapping followed by liquid chromatography/mass spectrometry. The cargo carried by these proteins was analyzed by untargeted liquid chromatography-high-resolution mass spectrometry.

RESULTS

Twelve carrier proteins of animal and plant origin, including the bovine lipocalins Bos d 2 and odorant binding protein, were enriched in DEs from protective European cowsheds. A potent asthma-protective fraction of Amish cowshed DEs (≈0.5% of the total carbon content of unfractionated extracts) contained 7 animal and plant proteins, including Bos d 2 and odorant binding protein loaded with fatty acid metabolites from plants, bacteria, and fungi.

CONCLUSIONS

Animals and plants from traditional farms produce proteins that transport hydrophobic microbial and plant metabolites. When delivered to mucosal surfaces, these agents might regulate airway responses.

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.

Gum Arabic in combination with IFN-γ promotes the M1 polarization in macrophage

Gum Arabic, a mixture of polysaccharide and glycoprotein, is used as an emulsifying stabilizer in the food industry. It might have immunomodulatory effects. We hypothesized that the combination of IFN-γ and Gum Arabic promotes the production of pro-inflammatory factors in RAW 264.7 cells. Treatment of RAW 264.7 cells with the combination of 3% Gum Arabic and 40 ng/mL IFN-γ resulted in a drastic increase (320%) in nitric oxide production compared with that induced by IFN-γ alone. PGE-2 was produced after the cells were treated with 3% Gum Arabic and 40 ng/mL IFN-γ for 6 h. Gum Arabic and IFN-γ increased the production of iNOS and COX-2 proteins, and triggered TNF-α release. Apart from TNF-α, the release of both G-CSF and IL-6 increased by more than 100 times. The release of IL-3, RANTES, and IL-10 increased by more than ten times. Gum Arabic and IFN-γ also increased the secretion of IL-10, IL-1α, IL-1β, IL-13, KC, IL-5, IL-4, IL-12, Eotaxin, IL-9, MCP-1, and ROS. Cytokines associated with M1 polarization of macrophages such as TNF-α, IL-1β, IL-12, NO, and ROS were induced by Gum Arabic and IFN-γ. Our findings help to explore the inflammatory reaction caused by Gum Arabic in cosmetics.

Specific Immunotherapy in a Murine Model of Grass Pollen (Phl p5b)-Induced Airway Inflammation

Background: The use of ovalbumin as a model allergen in murine models of allergic asthma is controversially discussed since it is not an aeroallergen and sensitization can only be achieved by using strong Th2-inducing adjuvants. Therefore, in this study, a murine model of asthma has been established in which sensitization against the major grass pollen allergen Phl p5b was performed without using aluminum hydroxide (alum). We used this model for specific immunotherapy.

Methods: Female, 5–6-week-old mice were sensitized by six subcutaneous (s.c.) injections of 20 μg Phl p5b followed by four provocations to induce allergic airway inflammation. For desensitization, 1 mg of Phl p5b was injected subcutaneously during allergen challenge for one to a maximum of four times. Three days after the last challenge, the allergic immune response was analyzed.

Results: Sensitized and challenged animals showed a significant infiltration of eosinophils into the airways, and the production of interleukin-5 (IL-5) by in vitro re-stimulated splenocytes could be detected. Furthermore, hyper-responsiveness of the airways was verified by invasive measurement of airway resistance in methacholine-challenged animals. Desensitized animals showed a significant reduction of all parameters.

Conclusion: In this study, a murine model of asthma has successfully been established by sensitization against the clinically relevant allergen Phl p5b without using alum. S.c. injection of allergen dose dependently led to desensitization of sensitized mice. We suggest that this model is useful to study adjuvant effects of immune modulatory substances on immunotherapy without the interference of alum.

Prebiotic characteristics of arabinogalactans during in vitro fermentation through multi-omics analysis

BACKGROUND AND OBJECTIVES

Dietary fibers have beneficial effects on human health through the interaction with gut microbiota. Larch wood arabinogalactan (LA-AG) is one kind of complex soluble dietary fibers that may be utilized by human gut microbiota.

METHODS AND RESULTS

In this study, the LA-AG degradation by gut microbiota were characterized by investigating the change of LA-AG, microbiota composition, and the production of short-chain fatty acids (SCFAs), lactic acid, succinic acid, as well as volatile organic metabolites. During the fermentation, pH decreased continuously, along with the organic acids (especially acetic acid and lactic acid) accumulating. LA-AG was degraded by gut microbiota then some beneficial metabolites were produced. In addition, LA-AG inhibited the proliferation of some gut microbiota (Unclassified_Enterobacteriaceae and Citrobacter) and the accumulation of some metabolites (Sulfide and indole) released by gut microbiota.

CONCLUSION

LA-AG was partly fermentable fibers with prebiotic potential for human gut health.

The role of innate immunity in asthma development and protection: Lessons from the environment

Asthma, a complex, chronic disease characterized by airway inflammation, hyperresponsiveness and remodelling, affects over 300 million people worldwide. While the disease is typically associated with exaggerated allergen-induced type 2 immune responses, these responses are strongly influenced by environmental exposures that stimulate innate immune pathways capable of promoting or protecting from asthma. The dual role played by innate immunity in asthma pathogenesis offers multiple opportunities for both research and clinical interventions and is the subject of this review.

The Role of Lectin Receptors and Their Ligands in Controlling Allergic Inflammation

More than fifty c-type lectin receptors (CLR) are known and have been identified so far. Moreover, we know the group of galectins and sialic acid-binding immunoglobulin-type lectins that also belong to the carbohydrate-binding receptors of the immune system. Thus, the lectin receptors form the largest receptor family among the pathogen recognition receptors. Similar to the toll-like receptors (TLRs), the CLR do not only recognize foreign but also endogenous molecules. In contrast to TLRs, which have a predominantly activating effect on the immune system, lectin receptors also mediate inhibitory signals. They play an important role in innate and adaptive immunity for the induction, regulation and shaping of the immune response. The hygiene hypothesis links enhanced infection to protection from allergic disease. Yet, the microbial substances that are responsible for mediating this allergy-protective activity still have to be identified. Microbes contain both ligands binding to TLRs and carbohydrates that are recognized by CLR and other lectin receptors. In the current literature, the CLR are often recognized as the ‘bad guys’ in allergic inflammation, because some glycoepitopes of allergens have been shown to bind to CLR, facilitating their uptake and presentation. On the other hand, there are many reports revealing that sugar moieties are involved in immune regulation. In this review, we will summarize what is known about the role of carbohydrate interaction with c-type lectins and other sugar-recognizing receptors in anti-inflammation, with a special focus on the regulation of the allergic immune response.

Atopy risk among school-aged children in relation to early exposures to a farm environment: A systematic review

BACKGROUND AND OBJECTIVES

Childhood atopy is a complex condition with both a genetic and an environmental component. This systematic review will explore the current understanding of the importance of early life exposures to a farm in the development of atopy measured by objective markers of skin prick testing, and specific IgE measurements in school age children.

METHODS

A systematic review was performed.

RESULTS

Among 7285 references identified, 14 studies met the inclusion criteria (13 cross-sectional studies and 1 case-control study). The results were fairly consistent in that early farm-related exposures can protect children from becoming atopic at school age. In general, there was heterogeneity in the assessment of outcomes and exposures.

CONCLUSIONS

Early-life farm exposures are associated with a protective effect on childhood atopy as assessed by objective markers. Future work should focus on understanding specific farm exposures that may important in these associations between atopy and farm exposures in children.

Associations between dog keeping and indoor dust microbiota

Living with dogs appears to protect against allergic diseases and airway infections, an effect possibly linked with immunomodulation by microbial exposures associated with dogs. The aim of this study was to characterize the influence of dog ownership on house dust microbiota composition. The bacterial and fungal microbiota was characterized with Illumina MiSeq sequencing from floor dust samples collected from homes in a Finnish rural-suburban (LUKAS2, N = 182) birth cohort, and the results were replicated in a German urban (LISA, N = 284) birth cohort. Human associated bacteria variable was created by summing up the relative abundances of five bacterial taxa. Bacterial richness, Shannon index and the relative abundances of seven bacterial genera, mostly within the phyla Proteobacteria and Firmicutes, were significantly higher in the dog than in the non-dog homes, whereas the relative abundance of human associated bacteria was lower. The results were largely replicated in LISA. Fungal microbiota richness and abundance of Leucosporidiella genus were higher in dog homes in LUKAS2 and the latter association replicated in LISA. Our study confirms that dog ownership is reproducibly associated with increased bacterial richness and diversity in house dust and identifies specific dog ownership-associated genera. Dogs appeared to have more limited influence on the fungal than bacterial indoor microbiota.

Particle Resuspension Dynamics in the Infant Near-Floor Microenvironment

Carpet dust contains microbial and chemical material that can impact early childhood health. Infants may be exposed to greater quantities of resuspended dust, given their close proximity to floor surfaces. Chamber experiments with a robotic infant were integrated with a material balance model to provide new fundamental insights into the size-dependency of infant crawling-induced particle resuspension and exposure. The robotic infant was exposed to resuspended particle concentrations from 10⁵ to 10⁶ m^-3 in the near-floor (NF) microzone during crawling, with concentrations generally decreasing following vacuum cleaning of the carpets. A pronounced vertical variation in particle concentrations was observed between the NF microzone and bulk air. Resuspension fractions for crawling are similar to those for adult walking, with values ranging from 10^-6 to 10^-1 and increasing with particle size. Meaningful amounts of dust are resuspended during crawling, with emission rates of 0.1 to 2 × 10⁴ μg h^-1. Size-resolved inhalation intake fractions ranged from 5 to 8 × 10³ inhaled particles per million resuspended particles, demonstrating that a significant fraction of resuspended particles can be inhaled. A new exposure metric, the dust-to-breathing zone transport efficiency, was introduced to characterize the overall probability of a settled particle being resuspended and delivered to the respiratory airways. Values ranged from less than 0.1 to over 200 inhaled particles per million settled particles, increased with particle size, and varied by over 2 orders of magnitude among 12 carpet types.

Total Synthesis of a Partial Structure from Arabinogalactan and Its Application for Allergy Prevention

Arabinogalactan, a microheterogeneous polysaccharide occurring in plants, is known for its allergy-protective activity, which could potentially be used for preventive allergy treatment. New treatment options are highly desirable, especially in a preventive manner, due to the constant rise of atopic diseases worldwide. The structural origin of the allergy-protective activity of arabinogalactan is, however, still unclear and isolation of the polysaccharide is not feasible for pharmaceutical applications due to a variation of the activity of the natural product and contaminations with endotoxins. Therefore, a pentasaccharide partial structure was selected for total synthesis and subsequently coupled to a carrier protein to form a neoglycoconjugate. The allergy-protective activity of arabinogalactan could be reproduced with the partial structure in subsequent in vivo experiments. This is the first example of a successful simplification of arabinogalactan with a single partial structure while retaining its allergy-preventive potential.

Patterns of farm exposure are associated with reduced incidence of atopic dermatitis in early life

BACKGROUND

Farm exposures may reduce the risk of atopic dermatitis (AD) in children, but this is controversial and US data are limited.

OBJECTIVE

This study was conducted to identify patterns of farm exposure in Wisconsin family farms that modify AD incidence and prevalence in early childhood.

METHODS

Environmental exposures, health history, and clinical outcomes were prospectively recorded for 111 farm families and 129 non-farm families enrolled in the Wisconsin Infant Study Cohort birth cohort study. Exposures from the prenatal and early postnatal (2-month) visits were evaluated together with parental report of AD diagnosis by a health care provider through age 24 months. Latent class analysis was performed with prenatal and early postnatal farm-exposure variables to assign farm children to 3 classes.

RESULTS

Overall, children of farm families had reduced AD incidence (P = .03). Within farm families, exposures including poultry (3% vs 28%; P = .003), pig (4% vs 25%; P = .04), feed grain (13% vs 34%; P = .02), and number of animal species were inversely associated with AD incidence. Among the latent class groups, children in families with diverse or more intense farm exposures (classes A and B) had reduced AD incidence, whereas low-exposure (class C) infants had AD incidence similar to that in nonfarm children.

CONCLUSIONS

Infants in Wisconsin farm families had reduced AD incidence, and patterns of farm exposures further defined AD risk. These findings suggest that exposure to diverse farm animals, feed, and bedding during the prenatal period and in early infancy reduce the risk of early-onset AD, a phenotype associated with multiple other atopic diseases.

Regulation of lung immunity by dendritic cells: Implications for asthma, chronic obstructive pulmonary disease and infectious disease

Since the first description of dendritic cells by Steinman and Cohn in 1973, this important cell type has gained increasing attention. Over 4000 papers have been published on this topic annually during the last few years. At the beginning, dendritic cells were recognized for their immune stimulatory properties and their importance in initiating an adaptive immune response. Later, it was found that dendritic cells do not only initiate but also regulate immune responses. This attribute makes the so-called regulatory dendritic cells highly important for the prevention of exaggerated immune responses. Immune cells make contact with different Ags every day and must be tightly controlled to prevent excessive inflammation and subsequent organ destruction, particularly in organs such as the gut and lungs. Here, we give a brief overview of our current knowledge on how immune responses are controlled by dendritic cells, highlighting how they are involved in the induction of peripheral tolerance. We focus on what is known about these processes in the lung, with a closer look at their role in the induction and control of diseases such as bronchial asthma, chronic obstructive pulmonary disease and lung infections. Finally, we summarize some current approaches to modulate the behavior of dendritic cells that may hopefully lead to future therapeutics to control exaggerated immune responses.

The Human Microbiota and Asthma

Over the last few decades, advances in our understanding of microbial ecology have allowed us to appreciate the important role of microbial communities in maintaining human health. While much of this research has focused on gut microbes, microbial communities in other body sites and from the environment are increasingly recognized in human disease. Here, we discuss recent advances in our understanding of host-microbiota interactions in the development and manifestation of asthma focusing on three distinct microbial compartments. First, environmental microbes originating from house dust, pets, and farm animals have been linked to asthma pathogenesis, which is often connected to their production of bioactive molecules such as lipopolysaccharide. Second, respiratory microbial communities, including newly appreciated populations of microbes in the lung have been associated with allergic airway inflammation. Current evidence suggests that the presence of particular microbes, especially Streptococcus, Haemophilus, and Morexella species within the airway may shape local immune responses and alter the severity and manifestations of airway inflammation. Third, the gut microbiota has been implicated in both experimental models and clinical studies in predisposing to asthma. There appears to be a "critical window" of colonization that occurs during early infancy in which gut microbial communities shape immune maturation and confer susceptibility to allergic airway inflammation. The mechanisms by which gut microbial communities influence lung immune responses and physiology, the "gut-lung axis," are still being defined but include the altered differentiation of immune cell populations important in asthma and the local production of metabolites that affect distal sites. Together, these findings suggest an intimate association of microbial communities with host immune development and the development of allergic airway inflammation. Improved understanding of these relationships raises the possibility of microbiota-directed therapies to improve or prevent asthma.

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.

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.

Strategies to alter the natural history of childhood asthma

PURPOSE OF REVIEW

Asthma exhibits significant heterogeneity in occurrence and severity over the lifespan. Our goal is to discuss recent evidence regarding determinants of the natural history of asthma during childhood, and review the rationale behind and status of major efforts to alter its course.

RECENT FINDINGS

Variations in microbial exposures are associated with risk of allergic disease, and the use of bacterial lysates may be a promising preventive strategy. Exposure to air pollution appears to be particularly damaging in prenatal and early life, and interventions to reduce pollution are feasible and result in clinical benefit. E-cigarette use may have a role in harm reduction for conventional cigarette smokers with asthma, but has undefined short-term and long-term effects that must be clarified. Vitamin D insufficiency over the first several years of life is associated with risk of asthma, and vitamin D supplementation reduces the risk of severe exacerbations.

SUMMARY

The identification of risk factors for asthma occurrence, persistence and severity will continue to guide efforts to alter the natural history of the disease. We have reviewed several promising strategies that are currently under investigation. Vitamin D supplementation and air pollution reduction have been shown to be effective strategies and warrant increased investigation and implementation.

The Early Development of Wheeze. Environmental Determinants and Genetic Susceptibility at 17q21

RATIONALE

Growing up on a farm protects from childhood asthma and early wheeze. Virus-triggered wheeze in infancy predicts asthma in individuals with a genetic asthma risk associated with chromosome 17q21.

OBJECTIVES

To test environmental determinants of infections and wheeze in the first year of life, potential modifications of these associations by 17q21, and the implications for different trajectories of wheeze.

METHODS

We followed 983 children in rural areas of Europe from birth until age 6 years. Symptoms of wheeze, rhinitis, fever, and environmental exposures were documented with weekly diaries during year 1. Asthma at age 6 was defined as ever having a reported doctor's diagnosis. Single-nucleotide polymorphisms related to ORMDL3 (rs8076131) and GSDMB (rs7216389, rs2290400) at 17q21 were genotyped.

MEASUREMENTS AND MAIN RESULTS

Early wheeze was positively associated with presence of older siblings among carriers of known asthma risk alleles at 17q21 (e.g., rs8076131) (adjusted odds ratio [aOR], 1.53; 95% confidence interval [CI], 1.16-2.01). Exposure to farm animal sheds was inversely related to wheeze (aOR, 0.44; 95% CI, 0.33-0.60). Both effects were similarly observed in children with transient wheeze up to age 3 years without subsequent development of asthma (aOR, 1.71 [95% CI, 1.09-2.67]; and aOR, 0.48 [95% CI, 0.30-0.76], respectively).

CONCLUSIONS

These findings suggest that the chromosome 17q21 locus relates to episodes of acute airway obstruction common to both transient wheeze and asthma. The previously identified asthma risk alleles are the ones susceptible to environmental influences. Thus, this gene-environment interaction reveals two faces of 17q21: The same genotype constitutes genetic risk and allows for environmental protection, thereby providing options for prospective prevention strategies.

Allergy protection by cowshed bacteria - recent findings and future prospects

Since the first publication in 1999, numerous epidemiologic studies provided strong evidence that frequent contact to a traditional farm environment in early life protects children from the development of allergic airway diseases. These consistent findings prompted enormous efforts to identify and characterize the potential causative factors and the underlying immunologic mechanisms in experimental studies. The cumulating evidence for the role of the cowshed-associated bacterial flora led to enhanced efforts not only to identify the relevant species but also to examine their specific immunomodulatory capacity, the bacterial components involved, and particularly the cellular and molecular mechanisms of their interaction with the immune system. We review here the methods applied to identify relevant bacterial species, the species which emerged thereof, and the similarities and differences in their mode of action as revealed so far. We further consider the impact of the current knowledge on worthwhile clinical application and reflect on the required next steps to foster the translation of the encouraging scientific progress which has been made in recent years.

The microbial environment and its influence on asthma prevention in early life

There is accumulating evidence to suggest that the environmental microbiome plays a significant role in asthma development. The very low prevalence of asthma in populations highly exposed to microbial environments (farm children and Amish populations) highlights its preventive potential. This microbial diversity might be necessary to instruct a well-adapted immune response and regulated inflammatory responses to other inhaled and ingested environmental elements, such as allergens, particles, and viruses. Like the internal gut microbiome, which is increasingly recognized as an important instructor of immune maturation, the external environmental microbiome might shape immune responses on the skin, airway mucosal surfaces, and potentially also the gut early in life. The diversity of the external microbial world will ensure that of the many maladapted pathways leading to asthma development, most, if not all, will be counterbalanced. Likewise, important contributors to asthma, such as allergen sensitization and allergic manifestations early in life, are being suppressed. Thus the facets of innate immunity targeted by microbes and their compounds and metabolites might be the master switch to asthma and allergy protection, which has been found in environments rich in microbial exposures.

Occupational agriculture organic dust exposure and its relationship to asthma and airway inflammation in adults

OBJECTIVE

Recent studies have made advances into understanding the complex agriculture work exposure environment in influencing asthma in adults. The objective of this study is to review studies of occupational agricultural exposures including dust, animal, and pesticide exposures with asthma in adult populations.

DATA SOURCES

PubMed databases were searched for articles pertaining to farming, agriculture, asthma, occupational asthma, airway inflammation, respiratory disease, lung disease, pesticides, and organic dust.

STUDY SELECTIONS

Studies chosen were published in or after 1999 that included adults and asthma and farming/agricultural work or agricultural exposures and airway inflammatory disease measurements.

RESULTS

The data remain inconclusive. Several retrospective studies demonstrate agricultural work to be protective against asthma in adults, especially with increased farming exposure over time. In contrast, other studies find increased risk of asthma with farming exposures, especially for the non-atopic adult. Mechanistic and genetic studies have focused on defining the wide variety and abundance of microorganisms within these complex organic dusts that trigger several pattern recognition receptor pathways to modulate the hosts' response.

CONCLUSION

Asthma risk depends on the interplay of genetic factors, gender, atopic predisposition, type of livestock, pesticide exposure, and magnitude and duration of exposure in the adult subject. Longer exposure to occupational farming is associated with decreased asthma risk. However, studies also suggest that agricultural work and multiple types of livestock are independent risk factors for developing asthma. Prospective and longitudinal studies focusing on genetic polymorphisms, objective assessments, and environmental sampling are needed to further delineate the influence of agriculture exposure in the adult worker.

Allergy-Protective Arabinogalactan Modulates Human Dendritic Cells via C-Type Lectins and Inhibition of NF-κB

Arabinogalactan (AG) isolated from dust of a traditional farm prevents disease in murine models of allergy. However, it is unclear whether this polysaccharide has immune regulatory properties in humans. The aim of this study was to test the influence of AG on the immune-stimulating properties of human dendritic cells (DCs). Moreover, we sought to identify the receptor to which AG binds. AG was produced from plant callus tissue under sterile conditions to avoid the influence of pathogen-associated molecular patterns in subsequent experiments. The influence of AG on the human immune system was investigated by analyzing its impact on monocyte-derived DCs. To analyze whether the T cell stimulatory capacity of AG-stimulated DCs is altered, an MLR with naive Th cells was performed. We revealed that AG reduced T cell proliferation in a human MLR. In the search for a molecular mechanism, we found that AG binds to the immune modulatory receptors DC-specific ICAM-3 -: grabbing non integrin (DC-SIGN) and macrophage mannose receptor 1 (MMR-1). Stimulation of these receptors with AG simultaneously with TLR4 stimulation with LPS increased the expression of the E3 ubiquitin-protein ligase tripartite motif -: containing protein 21 and decreased the phosphorylation of NF-κB p65 in DCs. This led to a reduced activation profile with reduced costimulatory molecules and proinflammatory cytokine production. Blocking of MMR-1 or DC-SIGN with neutralizing Abs partially inhibits this effect. We conclude that AG dampens the activation of human DCs by LPS via binding to DC-SIGN and MMR-1, leading to attenuated TLR signaling. This results in a reduced T cell activation capacity of DCs.

Farm exposures are associated with lower percentage of circulating myeloid dendritic cell subtype 2 at age 6

BACKGROUND

Early life farm exposures have been shown to decrease the risk of allergic diseases. Dendritic cells (DCs) may mediate asthma-protective effect of farm exposures as they play an important role in the development of immunity and tolerance. Our aim was to investigate whether the numbers and phenotypes of circulating DCs at age 6 are associated with farming, asthma, and atopy in a selected sample of French and Finnish children from the PASTURE study.

METHODS

We studied 82 farm and 86 nonfarm children with and without asthma. Using flow cytometry, BDCA1+ CD11c+ myeloid DC1s (mDC1), BDCA3+(high) mDC2s and BDCA2+ plasmacytoid DCs (pDCs) were identified and expressions of CD86, immunoglobulin-like transcript 3 (ILT3) and ILT4 were analyzed. Questionnaires were used to assess prenatal and lifetime patterns of farm exposures and to define asthma. Atopic sensitization was defined by specific IgE measurements.

RESULTS

The percentage of mDC2 cells was lower in farm children (0.033 ± 0.001) than in nonfarm children (0.042 ± 0.001; P = 0.008). Similar associations were found between mDC2 percentage and prenatal (P = 0.02) and lifetime exposure to farm milk (P = 0.03) and stables (P = 0.003), but these associations were not independent from farming. Asthma was positively associated with ILT4 + mDCs (P = 0.04) and negatively with CD86 + pDCs (P = 0.048) but only in nonfarm children.

CONCLUSIONS

Inverse association between farm exposure and mDC2 percentage suggest that this DC subset may play a role in farm-related immunoregulation.

Environmental protection from allergic diseases: From humans to mice and back

Allergic diseases have a strong environmental component, illustrated by the rapid rise of their prevalence in the Western world. Environmental exposures have been consistently shown to either promote or protect against allergic disease. Here we focus on protective exposures and the pathways they regulate. Traditional farming, natural environments with high biodiversity, and pets in the home (particularly dogs) have the most potent and consistent allergy-protective effects and are actively investigated to identify the environmental and host-based factors that confer allergy protection. Recent work emphasizes the critical protective role of microbial diversity and its interactions with the gut/lung and skin/lung axes-a cross-talk through which microbial exposure in the gut or skin powerfully influences immune responses in the lung.

Metabolomics study on serum of allergic bronchial asthma rabbits treated by Recuperating Lung decoction

This study found seven biological markers in the Recuperating Lung decoction, which intervenes in the mechanism of asthma.

Metabolomics Reveals Inflammatory-Linked Pulmonary Metabolic Alterations in a Murine Model of House Dust Mite-Induced Allergic Asthma

Although the house dust mite (HDM) is a major environmental aeroallergen that promotes the pathogenesis and severity of allergic asthma, it remains elusive if HDM exposures can induce global metabolism aberrations during allergic airway inflammation. Using an integrated gas and liquid chromatography mass spectrometry-based metabolomics and multiplex cytokine profile analysis, metabolic alterations and cytokine changes were investigated in the bronchoalveolar lavage fluid (BALF), serum, and lung tissues in experimental HDM-induced allergic asthma. Allergic pulmonary HDM exposures lead to pronounced eosinophilia, neutrophilia, and increases in inflammatory cytokines. Metabolomics analysis of the BALF, serum, and lung tissues revealed distinctive compartmental metabolic signatures, which included depleted carbohydrates, increased energy metabolites, and consistent losses of sterols and phosphatidylcholines. Pearson correlation analysis uncovered strong associations between specific metabolic alterations and inflammatory cells and cytokines, linking altered pulmonary metabolism to allergic airway inflammation. The clinically prescribed glucocorticoid prednisolone could modulate airway inflammation but was ineffective against the reversal of many HDM-induced metabolic alterations. Collectively, metabolomics reveal comprehensive pulmonary metabolic signatures in HDM-induced allergic asthma, with specific alterations in carbohydrates, lipids, sterols, and energy metabolic pathways. Altered pulmonary metabolism may be a major underlying molecular feature involved during HDM-induced allergic airway inflammation, linked to inflammatory cells and cytokines changes.

Shifted T-cell polarisation after agricultural dust exposure in mice and men

RATIONALE

A low prevalence of asthma and atopy has been shown in farmers and agricultural workers. However, in these workers, a higher prevalence of respiratory symptoms has been reported, in which T helper 1 (Th1) and/or Th17 responses may play a role.

AIM

We investigated the effect of exposure to dust extracts (DEs) from different farms on airway inflammation and T-cell polarisation in a mouse model and assessed T-cell polarisation in agricultural workers from the same farms.

METHODS

DEs were prepared from settled dust collected at cattle and pig farms and bulb and onion industries. Mice were exposed to phosphate-buffered saline (PBS), DEs, house dust mite (HDM) or HDM+DE via nasal instillation, four times per week during 5 weeks. Hyperresponsiveness, airway inflammation, IgE levels and T-cell polarisation were assessed. Th-cell and T cytotoxic (Tc)-cell subsets were investigated in peripheral blood samples from 33 agricultural workers and 9 non-exposed controls.

RESULTS

DEs induced interleukin(IL)-17, IL-1β and IL-6 in mouse lung homogenates. DE-exposed mice had more mixed inflammatory infiltrates in the lungs, and more neutrophils compared with PBS-exposed mice. DEs protected against the HDM-induced Th2 response and methacholine hyperresponsiveness. Interestingly, occupationally exposed humans had higher frequencies of Th cells spontaneously expressing IL-17 and interferon γ compared with controls.

CONCLUSION

Chronic exposure to different types of farm dust induces a Th/Tc-17 inflammatory response in mice and agricultural workers. This may contribute to the low prevalence of Th2-related diseases but may constitute a risk for other chronic respiratory diseases.

A novel synthetic lipopeptide is allergy-protective by the induction of LPS-tolerance

BACKGROUND

Exposure to the environment of traditional farms can protect children from some allergic disease. Due to this exposure, TLR2 expression in these children is increased. TLR2 ligands derived from gram-positive bacteria are found in the dust of these farms.

OBJECTIVES

We proved whether a synthetic lipopeptide binding to the TLR1/2 heterodimer is able to protect from allergic disease in two different murine models of allergy. We also investigated the immunological mechanisms underlying the protective properties of the lipopeptide.

METHODS

We synthesized a lipopeptide derived from a germination lipoprotein of Bacillus cereus (LPGerD). We evaluated the immunomodulatory activity of LPGerD in a murine model of systemic sensitization (OVA/Alum) and in a model in which mice were sensitized with OVA pulsed bone-marrow-derived dendritic cells (BMDCs) via the airways. Furthermore, the induction of LPS tolerance was studied.

RESULTS

Treatment of mice with LPGerD in a mouse model of asthma led to protection against sensitization and airway inflammation. Similarly, bone-marrow-derived dendritic cells (BMDCs) pre-treated with LPGerD were not able to prime mice for allergic immune response. We observed that pre-treatment with LPGerD led to the induction of a LPS-tolerant state in BMDCs. These cells secreted markedly lower amounts of pro-inflammatory cytokines upon LPS stimulation. Furthermore, we observed an up-regulation of IRAK-M mRNA in BMDCs pre-treated with LPGerD.

CONCLUSIONS AND CLINICAL RELEVANCE

Our results suggest that induction of a LPS-tolerant state in antigen-presenting cells (APCs) may contribute to the protective effect of a farming environment. TLR2 agonists similar to those appearing in cowshed dust extracts, such as our synthetic LPGerD, lead to the ignorance of the LPS stimulus, which is important for the activation of APCs to mount a Th2 immune response. This substance might be a promising candidate for allergy-preventive treatments as LPGerD had only low pro-inflammatory characteristics.

Maintaining health by balancing microbial exposure and prevention of infection: the hygiene hypothesis versus the hypothesis of early immune challenge

The human immune system is inseparably bonded to an individual's personal micro-biome from birth to death. Since the beginning of life, commensal relationships have ensured the survival of micro- and macro-organisms within complex relationships. However, technological advances and altered lifestyle imposed new rules for this interaction during recent decades. It has been observed that reduced exposure to micro-organisms and parasites results in decreased morbidity and mortality, but is also associated with a rising prevalence of atopic disorders and autoimmune diseases, mostly in industrialized countries. This inverse relationship is described by the 'hygiene hypothesis', put forward in 1989, yet this term only imperfectly describes these observations, as excessive hygiene or hygienic measures may not directly be the central cause. The lack of appropriate immune stimulation during early childhood with the consequence of disturbed alignment in the sequence of encountering self- or non-self-antigens might account in the rise of atopy and autoimmune disease. For this reason we propose the term 'early immune challenge hypothesis'. This concept highlights the importance of immune priming in early life in the context of genetic, social, geographic, cultural, and economic background. Moreover, it emphasizes the central role of 'training' of regulatory T-cells through sufficient microbial exposure, leading to a robust, healthy balance between inflammation and anti-inflammation or immune tolerance. Insufficient exposure might result in abnormal immune regulatory development. Finally, it incorporates the idea of encountering 'old friends' - organisms that shaped our immune system during human phylogeny. This article gives a comprehensive overview of the relationship between microbial exposure, and the incidence of asthma and hay fever is outlined. Although the outcomes of these studies originally were interpreted in the framework of the hygiene hypothesis, they may suit the concept of the hypothesis of early immune challenge even better. Moreover, recent studies have revealed that TH or TReg imbalances in disease may be partially corrected by the administration of helminthic or bacterial extracts.

What is new in the prevention of atopy and asthma?

PURPOSE OF REVIEW

Increasing understanding of mechanisms and influencing factors in the development of uncontrolled inflammatory responses in atopy and asthma should serve for the introduction of new preventive measures. This review tries to present the current state of the art and resumes that until now, no really effective concept can be offered to families at risk.

RECENT FINDINGS

In addition to modified feeding regimes (hydrolysed formula feeding in infancy), timing of the introduction of solids (avoidance of allergens versus early induction of tolerance), immune modulation using prebiotics or probiotics, a new target of potential intervention could be the human microbiome as a key player in the development of inflammatory diseases such as allergy and asthma. However, during the last 5 years, this concept could not yet be verified in interventional trials. There are new trials ongoing, studying the effect of microbial compounds in early infancy, vitamin D and polyunsaturated fatty acid supplementation during late pregnancy and the effect of azithromycin in children with recurrent wheeze. Results are to be expected within the next couple of years.

SUMMARY

New data on multifaceted intervention and the analysis of the human microbiome are to be expected. The recommendation for atopy and asthma prevention still focuses on avoidance of tobacco smoke exposure and food allergens during the first 4 months of life and feeding of hydrolysed formula if breast-feeding is not possible in high-risk infants, potentially early feeding of prebiotic sugars and/or certain strains of probiotic bacteria or bacterial compounds in certain subpopulations.

Novel transcriptional regulation of VEGF in inflammatory processes

Vascular endothelial growth factor (VEGF) is a critical angiogenic factor affecting endothelial cells, inflammatory cells and neuronal cells. In addition to its well-defined positive role in wound healing, pathological roles for VEGF have been described in cancer and inflammatory diseases (i.e. atherosclerosis, rheumatoid arthritis, inflammatory bowel disease and osteoarthritis). Recently, we showed that transcription factors LITAF and STAT6B affected the inflammatory response. This study builds upon our previous results in testing the role of mouse LITAF and STAT6B in the regulation of VEGF-mediated processes. Cells cotransfected with a series of VEGF promoter deletions along with truncated forms of mLITAF and/or mSTAT6B identified a DNA binding site (between −338 and −305 upstream of the transcription site) important in LITAF and/or STAT6B-mediated transcriptional regulation of VEGF. LITAF and STAT6B corresponding protein sites were identified. In addition, siRNA-mediated knockdown of mLITAF and/or mSTAT6B leads to significant reduction in VEGF mRNA levels and inhibits LPS-induced VEGF secretion in mouse RAW 264.7 cells. Furthermore, VEGF treatment of mouse macrophage or endothelial cells induces LITAF/STAT6B nuclear translocation and cell migration. To translate these observations in vivo, VEGF164-soaked matrigel were implanted in whole-body LITAF-deficient animals (TamLITAF^−/−), wild-type mice silenced for STAT6B, and in respective control animals. Vessel formation was found significantly reduced in TamLITAF^−/− as well as in STAT6B-silenced wild-type animals compared with control animals. The present data demonstrate that VEGF regulation by LITAF and/or STAT6B is important in angiogenesis signalling pathways and may be a useful target in the treatment of VEGF diseases.

The farm effect, or: when, what and how a farming environment protects from asthma and allergic disease

PURPOSE OF REVIEW

Multiple studies have shown that the prevalence of asthma and atopy is reduced in children raised on traditional dairy farms. This article discusses the temporal constraints for the protective farm effect, the components of a farming environment that are associated with protection, and novel mechanisms that may underlie protection from asthma and atopy in farming populations.

RECENT FINDINGS

Protection from asthma and allergy is strongest when exposure occurs in utero or early in life, but the protective effects can persist into adulthood. Just three exposures (contact with cows and straw and consumption of unprocessed cow's milk) account for virtually all the protective farm effect for asthma but not atopy. Whey proteins appear to be critical for the protective effects of farm milk, whereas the high microbial diversity existing in a farm environment is strongly and inversely associated with asthma, but only weakly associated with atopy. Therefore, distinct mechanisms are likely to mediate protection from asthma and atopy. The biological significance of microbial diversity is still unclear, but multiple lines of evidence link the asthma-protective and allergy-protective effects of farming to immune responses and the microbiome. Work in mouse models is revealing novel cellular and molecular mechanisms through which the microbiota may modulate immune responses and allergic inflammation, and thus contribute to the farm effect. The role of the host's genetic makeup, on the contrary, remains poorly understood.

SUMMARY

The discovery of the central role played by microbial diversity in the asthma-protective and allergy-protective effects of farming warrants metagenomic studies that concertedly and longitudinally investigate the microbiome, the genome, and the immune system of farmers and the farms they live on.

Metabolomics reveals altered metabolic pathways in experimental asthma

Metabolomics refers to the comprehensive analysis of metabolites in biological systems, and has been employed to study patients with asthma based on their urinary metabolite profile. We hypothesize that airway allergic asthma would affect metabolism in the lungs, and could be detected in bronchoalveolar lavage (BAL) fluid (BALF) using a combined liquid chromatography- and gas chromatography-mass spectrometry (MS) platform. The objective of this study was to investigate changes of lung metabolism in allergic asthma by metabolomic analysis of BALF. BALB/c mice were sensitized and challenged with ovalbumin to develop experimental asthma. Dexamethasone was administered to study the effects of corticosteroids on lung metabolism. Metabolites in BALF were measured using liquid chromatography-MS and gas chromatography-MS, and multivariate statistical analysis was performed by orthogonal projections to latent structures discriminant analysis. Metabolomic analysis of BALF from ovalbumin-challenged mice revealed novel changes in metabolic pathways in the lungs as compared with control animals. These metabolite changes suggest alterations of energy metabolism in asthmatic lungs, with increases of lactate, malate, and creatinine and reductions in carbohydrates, such as mannose, galactose, and arabinose. Lipid and sterol metabolism were affected with significant decreases in phosphatidylcholines, diglycerides, triglycerides, cholesterol, cortol, and cholic acid. Dexamethasone treatment effectively reversed many key metabolite changes, but was ineffective in repressing lactate, malate, and creatinine, and induced additional metabolite changes. Metabolomic analysis of BALF offers a promising approach to investigating allergic asthma. Our overall findings revealed considerable pathway changes in lung metabolism in asthmatic lungs, including energy, amino acids, and lipid metabolism.

Oral application of bacterial lysate in infancy decreases the risk of atopic dermatitis in children with 1 atopic parent in a randomized, placebo-controlled trial

BACKGROUND

Lower prevalence of atopy was found in children with continuous exposure to livestock and thus to microbial compounds. In animal models exposure to endotoxin (LPS) decreases allergic sensitization and airway inflammation.

OBJECTIVE

We sought to evaluate the effect of orally applied bacterial lysate in infancy on the prevalence of atopic dermatitis (AD) after the treatment phase at 7 months of age.

METHODS

This randomized, placebo-controlled trial included 606 newborns with at least single heredity for atopy. From week 5 until the end of month 7, infants were treated orally with bacterial lysate containing heat-killed gram-negative Escherichia coli Symbio and gram-positive Enterococcus faecalis Symbio or its placebo. Children were followed until 3 years of age.

RESULTS

There was no difference in the primary outcome between the active and placebo groups in the total study group. AD prevalence was significantly reduced at the end of the intervention phase (31 weeks of age) in the subgroup of infants with single heredity for atopy (relative risk, 0.52; 95% CI, 0.3-0.9). Ten percent (15/154) of infants in the active group had AD compared with 19% (27/145, P = .030) in the placebo group. This was more pronounced in the group of infants with paternal heredity for atopy (11% vs 32%, P = .004; relative risk, 0.34; 95% CI, 0.2-0.7).

CONCLUSION

Feeding of bacterial lysate might have prevented the development of AD, especially in children with paternal atopy, possibly indicating a preventive property only in subjects with a limited risk for atopy.

Protection from childhood asthma and allergy in Alpine farm environments-the GABRIEL Advanced Studies

BACKGROUND

Studies on the association of farm environments with asthma and atopy have repeatedly observed a protective effect of farming. However, no single specific farm-related exposure explaining this protective farm effect has consistently been identified.

OBJECTIVE

We sought to determine distinct farm exposures that account for the protective effect of farming on asthma and atopy.

METHODS

In rural regions of Austria, Germany, and Switzerland, 79,888 school-aged children answered a recruiting questionnaire (phase I). In phase II a stratified random subsample of 8,419 children answered a detailed questionnaire on farming environment. Blood samples and specific IgE levels were available for 7,682 of these children. A broad asthma definition was used, comprising symptoms, diagnosis, or treatment ever.

RESULTS

Children living on a farm were at significantly reduced risk of asthma (adjusted odds ratio [aOR], 0.68; 95% CI, 0.59-0.78; P< .001), hay fever (aOR, 0.43; 95% CI, 0.36-0.52; P< .001), atopic dermatitis (aOR, 0.80; 95% CI, 0.69-0.93; P= .004), and atopic sensitization (aOR, 0.54; 95% CI, 0.48-0.61; P< .001) compared with nonfarm children. Whereas this overall farm effect could be explained by specific exposures to cows, straw, and farm milk for asthma and exposure to fodder storage rooms and manure for atopic dermatitis, the farm effect on hay fever and atopic sensitization could not be completely explained by the questionnaire items themselves or their diversity.

CONCLUSION

A specific type of farm typical for traditional farming (ie, with cows and cultivation) was protective against asthma, hay fever, and atopy. However, whereas the farm effect on asthma could be explained by specific farm characteristics, there is a link still missing for hay fever and atopy.

Novel regulation of CCL2 gene expression by murine LITAF and STAT6B

Inflammation is a multifaceted process: beneficial as a defense mechanism but also detrimental depending on its severity and duration. At the site of injury, inflammatory cells are activated by a cascade of mediators, one of which is LITAF, a transcription regulator known to upregulate TNF-α. We previously showed that human LITAF forms a complex with human STAT6B, which translocates into the nucleus to upregulate cytokine transcription. To dissect the molecular implications of this complex, a murine model was developed and interactions between mouse STAT6B (mSTAT6B) and mouse LITAF (mLITAF) were analyzed. Both mLITAF and mSTAT6B expression were MyD88- and TLR ligand-dependent. Furthermore, mLITAF was found to mediate LPS-induced CCL2 gene transcription with the cooperation of mSTAT6B leading to CCL2 protein expression. In LITAF-deficient mice, mLITAF-mediated CCL2 production in macrophages was significantly reduced compared to the wild-type control animals. Mice knockdown for mSTAT6B by 6BsiRNA1 tail vein injection resulted in a decrease in serum TNF-α and CCL2 production. mLITAF/mSTAT6B complex is proposed to play a role in LPS-induced CCL2 expression and possibly other cytokines.

Structures, synthesis, and human Nod1 stimulation of immunostimulatory bacterial peptidoglycan fragments in the environment

Bacteria release immunostimulatory compounds to the environment, and one of the stimulants is the ligand of nucleotide-binding oligomerization domain protein 1 (Nod1), an intracellular protein involved in the recognition of the bacterial component peptidoglycans having a diaminopimelic acid (DAP) structure. The polymorphisms of Nod1 have been linked to several inflammatory diseases and allergies that are strongly affected by environmental factors. The present paper summarizes recent results on the isolation and structural elucidation of natural human Nod1 (hNod1) ligands from the Escherichia coli (E. coli) K-12 culture supernatant, the first chemical synthesis of these natural ligands and related PGN fragments structures, and the hNod1 stimulatory activities of the chemically synthesized DAP-type PGN fragments. For structural characterization studies, the 7-(diethylamino)coumarin-3-carbonyl (DEAC) labeling method was also used to enhance the sensitivity in mass spectrometry studies, in order to observe PGN fragments in a comprehensive manner. The results suggest that DAP-containing bacteria release certain hNod1 ligands to the environment and that these ligands accumulate in the environment and regulate the immune system through Nod1.