Prenatal lipopolysaccharide-exposure prevents allergic sensitization and airway inflammation, but not airway responsiveness in a murine model of experimental asthma

Impact of Prenatal LPS and Early-life Constant Light Exposure on Circadian Gene Expression Profiles in Various Rat Tissues

Exposure to lipopolysaccharide (LPS) during prenatal development leads to various changes in neurobiological and behavioural patterns. Similarly, continuous exposure to constant light (LL) during the critical developmental period of the circadian system affects gene expression in various tissues in adulthood. Given the reciprocal nature of the interaction between the circadian and the immune systems, our study primarily investigated the individual effects of both interventions and, more importantly, their combined effect. We aimed to explore whether there might be a potential synergistic effect on circadian rhythms and their parameters, focussing on the expression of clock genes, immune-related genes, and specific genes in the hippocampus, pineal gland, spleen and adrenal gland of rats at postnatal day 30. Our results show a significant influence of prenatal LPS and postnatal LL on the expression profiles of all genes assessed. However, the combination of prenatal LPS and postnatal LL only revealed an enhanced negative effect in a minority of the comparisons. In most cases, it appeared to attenuate the changes induced by the individual interventions, restoring the measured parameters to values closer to those of the control group. In particular, genes such as Nr1d1, Aanat and Tph1 showed increased amplitude in the pineal gland and spleen, while the kynurenine enzymes Kynu and KatII developed circadian rhythmicity in the adrenal glands only after the combined interventions. Our data suggest that a mild immunological challenge during prenatal development may play a critical role in triggering an adaptive response of the circadian clock later in life.

Very early life microbiome and metabolome correlates with primary vaccination variability in children

IMPORTANCE

We show that simultaneous study of stool and nasopharyngeal microbiome reveals divergent timing and patterns of maturation, suggesting that local mucosal factors may influence microbiome composition in the gut and respiratory system. Antibiotic exposure in early life as occurs commonly, may have an adverse effect on vaccine responsiveness. Abundance of gut and/or nasopharyngeal bacteria with the machinery to produce lipopolysaccharide-a toll-like receptor 4 agonist-may positively affect future vaccine protection, potentially by acting as a natural adjuvant. The increased levels of serum phenylpyruvic acid in infants with lower vaccine-induced antibody levels suggest an increased abundance of hydrogen peroxide, leading to more oxidative stress in low vaccine-responding infants.

Extracellular vesicles of the probiotic bacteria E. coli O83 activate innate immunity and prevent allergy in mice

BACKGROUND

E. coli O83 (Colinfant Newborn) is a Gram-negative (G-) probiotic bacterium used in the clinic. When administered orally, it reduces allergic sensitisation but not allergic asthma. Intranasal administration offers a non-invasive and convenient delivery method. This route bypasses the gastrointestinal tract and provides direct access to the airways, which are the target of asthma prevention. G- bacteria such as E. coli O83 release outer membrane vesicles (OMVs) to communicate with the environment. Here we investigate whether intranasally administered E. coli O83 OMVs (EcO83-OMVs) can reduce allergic airway inflammation in mice.

METHODS

EcO83-OMVs were isolated by ultracentrifugation and characterised their number, morphology (shape and size), composition (proteins and lipopolysaccharide; LPS), recognition by innate receptors (using transfected HEK293 cells) and immunomodulatory potential (in naïve splenocytes and bone marrow-derived dendritic cells; BMDCs). Their allergy-preventive effect was investigated in a mouse model of ovalbumin-induced allergic airway inflammation.

RESULTS

EcO83-OMVs are spherical nanoparticles with a size of about 110 nm. They contain LPS and protein cargo. We identified a total of 1120 proteins, 136 of which were enriched in OMVs compared to parent bacteria. Proteins from the flagellum dominated. OMVs activated the pattern recognition receptors TLR2/4/5 as well as NOD1 and NOD2. EcO83-OMVs induced the production of pro- and anti-inflammatory cytokines in splenocytes and BMDCs. Intranasal administration of EcO83-OMVs inhibited airway hyperresponsiveness, and decreased airway eosinophilia, Th2 cytokine production and mucus secretion.

CONCLUSIONS

We demonstrate for the first time that intranasally administered OMVs from probiotic G- bacteria have an anti-allergic effect. Our study highlights the advantages of OMVs as a safe platform for the prophylactic treatment of allergy. Video Abstract.

Intranasal administration of Acinetobacter lwoffii in a murine model of asthma induces IL-6-mediated protection associated with cecal microbiota changes

BACKGROUND

Early-life exposure to certain environmental bacteria including Acinetobacter lwoffii (AL) has been implicated in protection from chronic inflammatory diseases including asthma later in life. However, the underlying mechanisms at the immune-microbe interface remain largely unknown.

METHODS

The effects of repeated intranasal AL exposure on local and systemic innate immune responses were investigated in wild-type and Il6-/- , Il10-/- , and Il17-/- mice exposed to ovalbumin-induced allergic airway inflammation. Those investigations were expanded by microbiome analyses. To assess for AL-associated changes in gene expression, the picture arising from animal data was supplemented by in vitro experiments of macrophage and T-cell responses, yielding expression and epigenetic data.

RESULTS

The asthma preventive effect of AL was confirmed in the lung. Repeated intranasal AL administration triggered a proinflammatory immune response particularly characterized by elevated levels of IL-6, and consequently, IL-6 induced IL-10 production in CD4+ T-cells. Both IL-6 and IL-10, but not IL-17, were required for asthma protection. AL had a profound impact on the gene regulatory landscape of CD4+ T-cells which could be largely recapitulated by recombinant IL-6. AL administration also induced marked changes in the gastrointestinal microbiome but not in the lung microbiome. By comparing the effects on the microbiota according to mouse genotype and AL-treatment status, we have identified microbial taxa that were associated with either disease protection or activity.

CONCLUSION

These experiments provide a novel mechanism of Acinetobacter lwoffii-induced asthma protection operating through IL-6-mediated epigenetic activation of IL-10 production and with associated effects on the intestinal microbiome.

Influence of Immune System Abnormalities Caused by Maternal Immune Activation in the Postnatal Period

The developmental origins of health and disease (DOHaD) indicate that fetal tissues and organs in critical and sensitive periods of development are susceptible to structural and functional changes due to the adverse environment in utero. Maternal immune activation (MIA) is one of the phenomena in DOHaD. Exposure to maternal immune activation is a risk factor for neurodevelopmental disorders, psychosis, cardiovascular diseases, metabolic diseases, and human immune disorders. It has been associated with increased levels of proinflammatory cytokines transferred from mother to fetus in the prenatal period. Abnormal immunity induced by MIA includes immune overreaction or immune response failure in offspring. Immune overreaction is a hypersensitivity response of the immune system to pathogens or allergic factor. Immune response failure could not properly fight off various pathogens. The clinical features in offspring depend on the gestation period, inflammatory magnitude, inflammatory type of MIA in the prenatal period, and exposure to prenatal inflammatory stimulation, which might induce epigenetic modifications in the immune system. An analysis of epigenetic modifications caused by adverse intrauterine environments might allow clinicians to predict the onset of diseases and disorders before or after birth.

Early life exposure to outdoor air pollution and indoor environmental factors on the development of childhood allergy from early symptoms to diseases

BACKGROUND

The prevalence of childhood allergies has increased during past decades leading to serious hospitalization and heavy burden worldwide, yet the key factors responsible for the onset of early symptoms and development of diagnosed diseases are unclear.

OBJECTIVE

To explore the role of early life exposure to ambient air pollution and indoor environmental factors on early allergic symptoms and doctor diagnosed allergic diseases.

METHODS

A retrospective cohort study of 2598 preschool children was conducted at 36 kindergartens in Changsha, China from September of 2011 to February of 2012. A questionnaire was developed to survey each child's early onset of allergic symptoms (wheeze and rhinitis-like symptoms) and doctor diagnosis of allergic diseases (asthma and rhinitis) as well as home environments. Each mother's and child's exposures to ambient air pollutants (PM₁₀, SO₂, and NO₂) and temperature were estimated for in utero and postnatal periods. The associations of early symptoms and diagnosed diseases with outdoor air pollution and indoor environmental variables were examined by logistic regression models.

RESULTS

Childhood early allergic symptoms (33.9%) including wheeze (14.7%) and rhinitis-like symptoms (25.4%) before 2 years old were not associated with outdoor air pollution exposure but was significantly associated with maternal exposure of window condensation at home in pregnancy with ORs (95% CI) of 1.33 (1.11-1.59), 1.30 (1.01-1.67) and 1.27 (1.04-1.55) respectively, and was associated with new furniture during first year after birth with OR (95% CI) of 1.43 (1.02-2.02) for early wheeze. Childhood diagnosed allergic diseases (28.4%) containing asthma (6.7%) and allergic rhinitis (AR) (7.2%) were significantly associated with both outdoor air pollutants (mainly for SO₂ and NO₂) during first 3 years and indoor new furniture, redecoration, and window condensation. We found that sex, age, parental atopy, maternal productive age, environmental tobacco smoke (ETS), antibiotics use, economic stress, early and late introduction of complementary foods, and outdoor air pollution modified the effects of home environmental exposure in early life on early allergic symptoms and diagnosed allergic diseases.

CONCLUSION

Our study indicates that early life exposure to indoor environmental factors plays a key role in early onset of allergic symptoms in children, and further exposure to ambient air pollution and indoor environmental factors contribute to the later development of asthma and allergic rhinitis.

Early-Life Lung and Gut Microbiota Development and Respiratory Syncytial Virus Infection

Several environmental factors can influence the development and establishment of the early-life microbiota. For example, exposure to different environmental factors from birth to childhood will shape the lung and gut microbiota and the development of the immune system, which will impact respiratory tract infection and widespread disease occurrence during infancy and later in life. Respiratory syncytial virus (RSV) infects most infants by the age of two and is the primary cause of bronchiolitis in children worldwide. Approximately a third of infants hospitalized with bronchiolitis develop asthma later in life. However, it is unclear what factors increase susceptibility to severe RSV-bronchiolitis and the subsequent asthma development. In recent years, the role of the gut and lung microbiota in airway diseases has received increased interest, and more studies have focused on this field. Different epidemiological studies and experimental animal models have associated early-life gut microbiota dysbiosis with an increased risk of lung disease later in life. This work will review published evidence that correlated environmental factors that affect the early-life microbiota composition and their role in developing severe RSV infection.

Developmental programming of macrophages by early life adversity

Macrophages are central elements of all organs, where they have a multitude of physiological and pathological functions. The first macrophages are produced during fetal development, and most adult organs retain populations of fetal-derived macrophages that self-maintain without major input of hematopoietic stem cell-derived monocytes. Their developmental origins make macrophages highly susceptible to environmental perturbations experienced in early life, in particular the fetal period. It is now well recognized that such adverse developmental conditions contribute to a wide range of diseases later in life. This chapter explores the notion that macrophages are key targets of environmental adversities during development, and mediators of their long-term impact on health and disease. We first briefly summarize our current understanding of macrophage ontogeny and their biology in tissues and consider potential mechanisms by which environmental stressors may mediate fetal programming. We then review evidence for programming of macrophages by adversities ranging from maternal immune activation and diet to environmental pollutants and toxins, which have disease relevance for different organ systems. Throughout this chapter, we contemplate appropriate experimental strategies to study macrophage programming. We conclude by discussing how our current knowledge of macrophage programming could be conceptualized, and finally highlight open questions in the field and approaches to address them.

Prenatal Exposure to Air Pollution and Immune Thrombocytopenia: A Nationwide Population-Based Cohort Study

INTRODUCTION

Immune thrombocytopenia (ITP) is one of the most common hematologic disorders in children. However, its etiology is still unclear. Epidemiological studies have shown that air pollution is a plausible risk factor in stimulation of oxidative stress, induction of inflammation, and onset of autoimmune diseases. The objective of this article is to examine the effects of prenatal exposure to air pollution on the occurrence of immune thrombocytopenia (ITP) in children.

MATERIALS AND METHODS

This is a nationwide, population-based, matched case-control study. Using data from Taiwan's Maternal and Child Health Database (MCHD), we identified 427 children with ITP less than 6 years of age and age-matched controls without ITP between 2004 and 2016. Levels of prenatal exposure to air pollutants were obtained from 71 Environmental Protection Administration monitoring stations across Taiwan according to the maternal residence during pregnancy. Patients who had outpatient visits or admission with diagnosis of ITP and subsequently received first-line treatment of intravenous immunoglobulin or oral glucocorticoids were defined as incidence cases.

RESULTS

Prenatal exposure to particulate matter <10 μm (PM10) in diameter and the pollutant standard index (PSI) increased the risk of childhood ITP. Conversely, carbon monoxide (CO) exposure during pregnancy was negatively associated with the development of ITP.

CONCLUSION

Certain prenatal air pollutant exposure may increase the incidence of ITP in children.

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.

Inherent maternal type 2 immunity: Consequences for maternal and offspring health

An inherent elevation in type 2 immunity is a feature of maternal and offspring immune systems. This has diverse implications for maternal and offspring biology including influencing success of pregnancy, offspring immune development and maternal and offspring ability to control infection and diseases such as allergies. In this review we provide a broad insight into how this immunological feature of pregnancy and early life impacts both maternal and offspring biology. We also suggest how understanding of this axis of immune influence is and may be utilised to improve maternal and offspring health.

A world of inflammation: the need for ecological solutions that co-benefit people, place and planet

The ecology of the early environment - including microbial diversity, nutrition, nature, social interactions and the totality of exposures in the wider "exposome" - have life-long implications for all aspects of health and resilience. In particular, the emergence of "microbiome science" provides new evidence for vital relationships between biodiversity and health at every level. New perspectives of ecological interdependence connect personal and planetary health; the human health crisis cannot be separated from the social, political and economic "ecosystems" otherwise driving dysbiosis (from its etymological root, "life in distress") at every level. Adverse changes in macroscale ecology - of food systems, lifestyle behaviours, socioeconomic disadvantage and environmental degradation - all impact the microbial systems sitting at the foundations of all ecosystems. In particular, changes in the function and composition of the human-associated microbiome have been implicated in the mounting global burden of noncommunicable diseases (NCDs), exacerbating inflammation and metabolic dysregulation through multiple pathways across the lifespan. This "dysbiotic drift" (adverse shifts in ecology at all scales) underscores the need for ecological approaches aimed at restoring symbiosis, balance and mutualism. While there is promise with supplement-based strategies (e.g. probiotics, prebiotics), it is essential to focus on upstream factors implicated in dysbiosis, including the health of wider environments, lifestyle, nature relatedness, and the social policies and practices which can facilitate or inhibit dysbiotic drift. This also calls for ambitious integrative approaches which not only define these interconnections, but also capitalize on them to create novel, collaborative and mutualistic solutions to our vast interdependent global challenges.

Exploring the evidence for epigenetic regulation of environmental influences on child health across generations

Environmental exposures, psychosocial stressors and nutrition are all potentially important influences that may impact health outcomes directly or via interactions with the genome or epigenome over generations. While there have been clear successes in large-scale human genetic studies in recent decades, there is still a substantial amount of missing heritability to be elucidated for complex childhood disorders. Mounting evidence, primarily in animals, suggests environmental exposures may generate or perpetuate altered health outcomes across one or more generations. One putative mechanism for these environmental health effects is via altered epigenetic regulation. This review highlights the current epidemiologic literature and supporting animal studies that describe intergenerational and transgenerational health effects of environmental exposures. Both maternal and paternal exposures and transmission patterns are considered, with attention paid to the attendant ethical, legal and social implications.

Neonatal endotoxin stimulation is associated with a long-term bronchiolar epithelial expression of innate immune and anti-allergic markers that attenuates the allergic response

Allergic asthma is the most common phenotype of the pathology, having an early-onset in childhood and producing a Th2-driven airways remodeling process that leads to symptoms and pathophysiological changes. The avoidance of aeroallergen exposure in early life has been shown to prevent asthma, but without repeated success and with the underlying preventive mechanisms at the beginning of asthma far to be fully recognized. In the present study, we aimed to evaluate if neonatal LPS-induced boost in epithelial host defenses contribute to prevent OVA-induced asthma in adult mice. To this, we focused on the response of bronchiolar club cells (CC), which are highly specialized in maintaining the epithelial homeostasis in the lung. In these cells, neonatal LPS administration increased the expression of TLR4 and TNFα, as well as the immunodulatory/antiallergic proteins: club cell secretory protein (CCSP) and surfactant protein D (SP-D). LPS also prevented mucous metaplasia of club cells and reduced the epidermal growth factor receptor (EGFR)-dependent mucin overproduction, with mice displaying normal breathing patterns after OVA challenge. Furthermore, the overexpression of the epithelial Th2-related molecule TSLP was blunted, and normal TSLP and IL-4 levels were found in the bronchoalveolar lavage. A lower eosinophilia was detected in LPS-pretreated mice, along with an increase in phagocytes and regulatory cells (CD4+CD25+FOXP3+ and CD4+IL-10+), together with higher levels of IL-12 and TNFα. In conclusion, our study demonstrates stable asthma-preventive epithelial effects promoted by neonatal LPS stimulation, leading to the presence of regulatory cells in the lung. These anti-allergic dynamic mechanisms would be overlaid in the epithelium, favored by an adequate epidemiological environment, during the development of asthma.

Pre-conceptional exposure to multiwalled carbon nanotubes suppresses antibody production in mouse offspring

Prenatal particle exposure has been shown to increase allergic responses in offspring. Carbon nanotubes (CNTs) possess immunomodulatory properties, but it is unknown whether maternal exposure to CNTs interferes with offspring immune development. Here, C57Bl/6J female mice were intratracheally instilled with 67 of μg multiwalled CNTs on the day prior to mating. After weaning, tolerance and allergy responses were assessed in the offspring. Offspring of CNT-exposed (CNT offspring) and of sham-exposed dams (CTRL offspring) were intranasally exposed to ovalbumin (OVA) once weekly for 5 weeks to induce airway mucosal tolerance. Subsequent OVA sensitization and aerosol inhalation caused low or no OVA-specific IgE production and no inflammation. However, the CNT offspring presented with significantly lower OVA-specific IgG1 levels than CTRL offspring. In other groups of 5-week-old offspring, low-dose sensitization with OVA and subsequent OVA aerosol inhalation led to significantly lower OVA-specific IgG1 production in CNT compared to CTRL offspring. OVA-specific IgE and airway inflammation were non-significantly reduced in CNT offspring. The immunomodulatory effects of pre-gestational exposure to multiwalled CNTs were unexpected, but very consistent. The observations of suppressed antigen-specific IgG1 production may be of importance for infection or vaccination responses and warrant further investigation.

A prenatally disrupted airway epithelium orchestrates the fetal origin of asthma in mice

BACKGROUND

Prenatal challenges such as maternal stress perception increase the risk and severity of asthma during childhood. However, insights into the trajectories and targets underlying the pathogenesis of prenatally triggered asthma are largely unknown. The developing lung and immune system may constitute such targets.

OBJECTIVE

Here we have aimed to identify the differential sex-specific effects of prenatal challenges on lung function, immune response, and asthma severity in mice.

METHODS

We generated bone marrow chimeric (BMC) mice harboring either prenatally stress-exposed lungs or a prenatally stress-exposed immune (hematopoietic) system and induced allergic asthma via ovalbumin. Next-generation sequencing (RNA sequencing) of lungs and assessment of airway epithelial barrier function in ovalbumin-sensitized control and prenatally stressed offspring was also performed.

RESULTS

Profoundly enhanced airway hyperresponsiveness, inflammation, and fibrosis were exclusively present in female BMC mice with prenatally stress-exposed lungs. These effects were significantly perpetuated if both the lungs and the immune system had been exposed to prenatal stress. A prenatally stress-exposed immune system alone did not suffice to increase the severity of these asthma features. RNA sequencing analysis of lungs from prenatally stressed, non-BMC, ovalbumin-sensitized females unveiled a deregulated expression of genes involved in asthma pathogenesis, tissue remodeling, and tight junction formation. It was also possible to independently confirm a tight junction disruption. In line with this, we identified an altered perinatal and/or postnatal expression of genes involved in lung development along with an impaired alveolarization in female prenatally stressed mice.

CONCLUSION

Here we have shown that the fetal origin of asthma is orchestrated by a disrupted airway epithelium and further perpetuated by a predisposed immune system.

Inflammatory mechanisms linking maternal and childhood asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness, inflammation, and remodeling. Asthma often develops during childhood and causes lifelong decrements in lung function and quality of life. Risk factors for childhood asthma are numerous and include genetic, epigenetic, developmental, and environmental factors. Uncontrolled maternal asthma during pregnancy exposes the developing fetus to inflammatory insults, which further increase the risk of childhood asthma independent of genetic predisposition. This review focuses on the role of maternal asthma in the development of asthma in offspring. We will present maternal asthma as a targetable and modifiable risk factor for childhood asthma and discuss the mechanisms by which maternal inflammation increases childhood asthma risk. Topics include how exposure to maternal asthma in utero shapes structural lung development with a special emphasis on airway nerves, how maternal type-2 cytokines such as IL-5 activate the fetal immune system, and how changes in lung and immune cell development inform responses to aero-allergens later in life. Finally, we highlight emerging evidence that maternal asthma establishes a unique "asthma signature" in the airways of children, leading to novel mechanisms of airway hyperreactivity and inflammatory cell responses.

Maternal helminth infections and the shaping of offspring immunity

Helminth infections leave a long-lasting immunological footprint on their hosts. Clinical studies have provided first evidence that maternal helminth infections can result in an altered immune profile in their offspring which can potentially shape how they respond to conditions throughout life. This can relate to changes in offspring induction of immune responses against other diseases. However, whether these changes result in actual changes in offspring ability to control disease is unclear. Our understanding of which immune mechanisms are altered and how they are changed is limited. In this review, we highlight what we know from human and mouse studies about this important context of helminth exposure. Moreover, we discuss how mechanisms such as antibody transfer, antigen exposure, maternal cell uptake, chimerism and epigenetics are all likely to be functional contributors to the striking changes that are seen in offspring born or nursed by helminth exposed mothers.

Antibiotics and autoimmune and allergy diseases: Causative factor or treatment?

The newborn infant emerges from an almost sterile environment into a world of bacteria. Bacteria colonize the infant's skin, lungs, and, of most importance, the gut. The process of bacterial colonization is coordinated, and each body niche acquires a unique composition of bacteria. In the gut, most bacteria belong to the Firmicutes and Bacteroidetes phyla, while Actinobacteria and Proteobacteria are far less abundant. Some of these bacteria possess strong immunoregulatory properties. Bacterial colonization is essential to skew the newborn's immune response away from the allergy-favoring Type-2 response towards a Type-1 immune response, which is essential for pathogen elimination. Imbalance between Type 1 and Type 2 responses, however, can promote autoimmunity. In addition, the microbiota shapes immune responses in adults. Autoimmune and allergic diseases are commonly associated with an altered composition of resident bacteria, which is known as dysbiosis. Perhaps the most common cause of disruption and alteration of the bacterial colonization of newborns is the use of antibiotics. It is not known whether the dysbiosis precedes or is the consequence of allergic and autoimmune disorders, and whether antibiotics can be a trigger for these disorders, depending on the type of antibiotic used and the maturity of immune system. In this review, we discuss the development of the microbiota in different body niches and their immunomodulatory potential. We evaluate the impact of antibiotics, both in mice and in humans, on microbial communities and how that may impact the development and manifestation of diseases through all stages of life: the prenatal period, childhood, and adulthood.

Transgenerational and intergenerational epigenetic inheritance in allergic diseases

It has become clear that early life (including in utero exposures) is a key window of vulnerability during which environmental exposures can alter developmental trajectories and initiate allergic disease development. However, recent evidence suggests that there might be additional windows of vulnerability to environmental exposures in the parental generation before conception or even in previous generations. There is evidence suggesting that information of prior exposures can be transferred across generations, and experimental animal models suggest that such transmission can be conveyed through epigenetic mechanisms. Although the molecular mechanisms of intergenerational and transgenerationational epigenetic transmission have yet to be determined, the realization that environment before conception can alter the risks of allergic diseases has profound implications for the development of public health interventions to prevent disease. Future research in both experimental models and in multigenerational human cohorts is needed to better understand the role of intergenerational and transgenerational effects in patients with asthma and allergic disease. This will provide the knowledge basis for a new approach to efficient intervention strategies aimed at reducing the major public health challenge of these conditions.

The Influence of LPS-Induced Maternal Inflammation on Postnatal Collagen-Induced Arthritis

Maternal health and nutritional status influence offspring health and the diseases that may develop in them. The effects of maternal inflammation on offspring from the perspective of the inflammatory response and immune changes are not fully understood. We hypothesized that maternal inflammation modulates immune and metabolic functions, affecting the pathophysiology of inflammatory diseases in offspring. This study investigated whether maternal inflammation affects the onset of collagen-induced arthritis (CIA), a murine model of human rheumatoid arthritis. Female DBA/1J mice received a single intraperitoneal injection of lipopolysaccharide (LPS) 5 days before conception. Male offspring of LPS-treated dams were placed in the maternal LPS group (MLG). To induce CIA, type II collagen (CII) was emulsified with Freund's complete adjuvant and injected twice into each mouse, at 13 and 16 weeks. The offspring were sacrificed at 26 weeks to analyze immunological and metabolic parameters. The degree of joint swelling at an early stage of CIA was lower in the MLG than in the control group. From histological analysis, the severity of joint destruction (severity of arthritis score) and CII-specific IgG titer were significantly lower in the MLG. However, at 26 weeks, serum interleukin (IL)-6 levels, an index of CIA disease activity, were significantly higher in the MLG. Moreover, serum leptin levels were lower in the MLG, and a negative correlation between leptin and serum IL-6 was observed. In conclusion, maternal inflammation does not merely suppress inflammation; it may delay CIA in offspring. The analysis of inflammatory cytokines and leptin concentrations at 26 weeks suggests that the pathophysiology of arthritis was worsening. This study also suggests that maternal inflammation modulates postnatal inflammatory response patterns in offspring.

Intestinal barrier and gut microbiota: Shaping our immune responses throughout life

The gastrointestinal (GI) tract is considered the largest immunological organ in the body having a central role in regulating immune homeostasis. Contrary to earlier belief, the intestinal epithelial barrier is not a static physical barrier but rather strongly interacts with the gut microbiome and cells of the immune system. This intense communication between epithelial cells, immune cells and microbiome will shape specific immune responses to antigens, balancing tolerance and effector immune functions. Recent studies indicate that composition of the gut microbiome affects immune system development and modulates immune mediators, which in turn affect the intestinal barrier. Moreover, dysbiosis may favor intestinal barrier disruption and could be related to increased susceptibility to certain diseases. This review will be focused on the development of the intestinal barrier and its function in host immune defense and how gut microbiome composition throughout life can affect this role.

Inducing maternal inflammation promotes leptin production in offspring but does not improve allergic symptoms in a mouse model of allergic rhinitis

AIMS

The intrauterine environment is considered to affect immunological development in fetus, leading to an increased risk of developing allergy. In particular, maternal lipopolysaccharides (LPS) administration might regulate the development of allergic disease in offspring. Several studies have shown that being obese relates to a higher prevalence of allergic diseases compared to normal weight. The present study explored the effects of inducing maternal inflammation with LPS before pregnancy on body weight, physical composition including body fat, adipokine production, and pathology of allergic rhinitis in offspring.

MAIN METHODS

Female mice received a single intraperitoneal injection of LPS (2 μg/g BW). After 5 days of LPS administration, female mice were mated with males, and experimental allergic rhinitis was induced in female offspring. Immunization and nasal challenge with ovalbumin (OVA) were performed at 7 and 8 weeks of age. Allergic rhinitis-like symptoms, OVA-specific IgE and adipokines in sera, body weight, fat pad weight, and cytokine production by splenocytes in these 9-week-old offspring.

KEY FINDINGS

Maternal LPS administration results in a significant increase in body weight, visceral fat accumulation, and serum leptin concentration, and the dominance of Th1 in Th balance. Nevertheless, there was no statistical difference in OVA-specific IgE titer and allergic-like symptoms between the groups.

SIGNIFICANCE

In conclusion, maternal LPS promoted leptin production and altered Th balance in mice offspring, but not improved allergic symptoms in a mouse model of allergic rhinitis. It might suggest that inflammation during pregnancy plays a role in the adipose tissue function which could diversely influence allergic inflammation in offspring.

The influence of dietary immunomodulatory factors on development of food allergy in children

In the last few years many studies have been conducted on the role of dietary and environmental factors in the prevention of allergic diseases among children. Many studies have shown that the diet of pregnant women and children in their early postnatal life, rich in antioxidants, vitamin D, and fatty acids is beneficial as it reduces the risk of allergy in their future life. Moreover, there are many reports about the main role of gut microbiota and probiotics in the allergy prevention, what can indicate new ways of procedures in allergic diseases.

Diet Matters: Endotoxin in the Diet Impacts the Level of Allergic Sensitization in Germ-Free Mice

Germ-free animals have been used to define the vital role of commensal bacteria on the maturation of the host immune system. However, the role of bacterial residues in diet in this setting is poorly understood. Here we investigated the effect of bacterial contamination in sterile diet on the level of allergic sensitization in germ-free mice. Sterile grain-based diets ST1 and R03 were tested for the level of bacterial contamination. ST1 contained higher amount of bacterial DNA, approximately ten times more endotoxin, and induced higher, TLR4-dependent, cytokine production in dendritic cells compared to R03. In a germ-free mouse model of sensitization to the major birch pollen allergen Bet v 1, feeding on ST1 for at least two generations was associated with decreased production of allergen-specific IgE and IgG1 antibodies in sera in comparison to R03. Furthermore, reduced levels of allergen-specific and ConA-induced cytokines IL-4, IL-5 and IL-13 accompanied by increased levels of IFN-γ were detected in splenocytes cultures of these mice. Our results show that contamination of experimental diet with bacterial residues, such as endotoxin, significantly affects the development of allergic sensitization in germ-free mice. Therefore, careful selection of sterile food is critical for the outcomes of germ-free or gnotobiotic experimental models of immune-deviated diseases.

Immune-Microbiota Interactions: Dysbiosis as a Global Health Issue

Throughout evolution, microbial genes and metabolites have become integral to virtually all aspects of host physiology, metabolism and even behaviour. New technologies are revealing sophisticated ways in which microbial communities interface with the immune system, and how modern environmental changes may be contributing to the rapid rise of inflammatory noncommunicable diseases (NCDs) through declining biodiversity. The implications of the microbiome extend to virtually every branch of medicine, biopsychosocial and environmental sciences. Similarly, the impact of changes at the immune-microbiota interface are directly relevant to broader discussions concerning rapid urbanization, antibiotics, agricultural practices, environmental pollutants, highly processed foods/beverages and socioeconomic disparities--all implicated in the NCD pandemic. Here, we make the argument that dysbiosis (life in distress) is ongoing at a micro- and macro-scale and that as a central conduit of health and disease, the immune system and its interface with microbiota is a critical target in overcoming the health challenges of the twenty-first century.

Developmental origins of inflammatory and immune diseases

Epidemiological and experimental animal studies show that suboptimal environments in fetal and neonatal life exert a profound influence on physiological function and risk of diseases in adult life. The concepts of the 'developmental programming' and Developmental Origins of Health and Diseases (DOHaD) have become well accepted and have been applied across almost all fields of medicine. Adverse intrauterine environments may have programming effects on the crucial functions of the immune system during critical periods of fetal development, which can permanently alter the immune function of offspring. Immune dysfunction may in turn lead offspring to be susceptible to inflammatory and immune diseases in adulthood. These facts suggest that inflammatory and immune disorders might have developmental origins. In recent years, inflammatory and immune disorders have become a growing health problem worldwide. However, there is no systematic report in the literature on the developmental origins of inflammatory and immune diseases and the potential mechanisms involved. Here, we review the impacts of adverse intrauterine environments on the immune function in offspring. This review shows the results from human and different animal species and highlights the underlying mechanisms, including damaged development of cells in the thymus, helper T cell 1/helper T cell 2 balance disturbance, abnormal epigenetic modification, effects of maternal glucocorticoid overexposure on fetal lymphocytes and effects of the fetal hypothalamic-pituitary-adrenal axis on the immune system. Although the phenomena have already been clearly implicated in epidemiologic and experimental studies, new studies investigating the mechanisms of these effects may provide new avenues for exploiting these pathways for disease prevention.

Effects of conventional tobacco smoke and nicotine-free cigarette smoke on airway inflammation, airway remodelling and lung function in a triple allergen model of severe asthma

BACKGROUND

Patients with asthma who smoke have reduced lung function, increased exacerbation rates and increased steroid resistance compared to non-smoking asthmatics. In mice, cigarette smoke has been reported to have both pro- and anti-Th2 response effects.

OBJECTIVE

We hypothesized that combining tobacco cigarette smoke (tCS) with allergen exposure increases inflammation, airway remodelling and lung function in mice. To test this hypothesis, we combined a severe triple allergen model with tCS exposure and investigated whether effects were due to Toll-like receptor 4 signalling and/or nicotine and also observed when nicotine-free cigarettes were used.

METHODS

Mice were sensitized with ovalbumin, cockroach and house dust mite allergen in alum followed by intratracheal challenges with allergen twice a week for 6 weeks or additionally exposed to tCS during the allergen challenge period. Nicotine or nicotine-free herbal cigarette smoke was also applied to allergen challenged mice.

RESULTS

tCS significantly reduced eosinophil numbers, IL-4 and IL-5 concentrations in the lung, total and allergen-specific IgE in serum, improved lung function and reduced collagen I levels. With the exception of collagen I all parameters reduced by tobacco cigarette smoke were also reduced in Toll-like receptor 4-deficient mice. Nicotine-free cigarette smoke also had significant anti-inflammatory effects on eosinophils, IL-4 and IL-5 concentrations in the lung and reduced airway hyperreactivity, albeit weaker than tobacco smoke. Applying nicotine alone also reduced Th2 cytokine levels and eosinophil numbers in the airways.

CONCLUSION

Our experiments show that tCS exposure reduces allergen-induced Th2 response in the lung and associated collagen I production and development of airway hyperreactivity. With the exception on collagen I formation, these effects were not dependent on Toll-like receptor 4. The observed anti-Th2 effects of both nicotine and nicotine-free herbal cigarette smoke together suggests that tCS reduces the Th2 responses through nicotine and other products released by burning tobacco.

In utero Programming of Allergic Susceptibility

BACKGROUND

Around 30-40% of the world's population will experience allergy, the most common and earliest-onset noncommunicable disease. With a steady rise in the incidence of allergic disease over recent decades, up to 18% of children will suffer a respiratory, food or skin allergy before their 18th birthday. There is compelling evidence that the risk of developing allergy is influenced by early life events and particularly in utero exposures.

METHODS

A comprehensive literature review was undertaken which outlines prenatal risk factors and potential mechanisms underlying the development of allergy in childhood.

RESULTS

Exposures including maternal cigarette smoking, preterm birth and Caesarean delivery are implicated in predisposing infants to the later development of allergy. In contrast, restricted growth in utero, a healthy maternal diet and a larger family size are protective, but the mechanisms here are unclear and require further investigation.

CONCLUSION

To ameliorate the allergy pandemic in young children, we must define prenatal mechanisms that alter the programming of the fetal immune system and also identify specific targets for antenatal interventions.

[Epigenetics in allergic diseases and asthma]

Allergic diseases and asthma are the result of complex interactions between genetic predisposition and environmental factors. Asthma is one of the most prevalent chronic disease among children. In this article we review some environmental factors like: allergen exposition, tobacco, bacteria, microbial components, diet, obesity and stress, which influences during intrauterine and infancy life in the epigenetic regulation of asthma and allergic diseases. The review has been done in three models: in-vitro, animal and human.

Germ-Free Mice Model for Studying Host-Microbial Interactions

Germ-free (GF) mice are a relevant model system to study host-microbial interactions in health and disease. In this chapter, we underscore the importance of using GF mice model to study host-microbial interactions in obesity, immune development and gastrointestinal physiology by reviewing current literature. Furthermore, we also provide a brief protocol on how to setup a gnotobiotic facility in order to properly maintain and assess GF status in mice colonies.

Does allergy begin in utero?

It has been recognized for centuries that allergic disease runs in families, implying a role for genetic factors in determining individual susceptibility. More recently, a range of evidence shows that many of these genetic factors, together with in utero environmental exposures, lead to the development of allergic disease through altered immune and organ development. Environmental exposures during pregnancy including diet, nutrient intake and toxin exposures can alter the epigenome and interact with inherited genetic and epigenetic risk factors to directly and indirectly influence organ development and immune programming. Understanding of these factors will be essential in identifying at-risk individuals and possible development of therapeutic interventions for the primary prevention of allergic disease. In this review, we summarize the evidence that suggests allergic disease begins in utero, together with possible mechanisms for the effect of environmental exposures during pregnancy on allergic disease risk, including epigenetics.

Maternal influences over offspring allergic responses

Asthma occurs as a result of complex interactions of environmental and genetic factors. Clinical studies and animal models of asthma indicate offspring of allergic mothers have increased risk of development of allergies. Environmental factors including stress-induced corticosterone and vitamin E isoforms during pregnancy regulate the risk for offspring development of allergy. In this review, we discuss mechanisms for the development of allergic disease early in life, environmental factors that may impact the development of risk for allergic disease early in life, and how the variation in global prevalence of asthma may be explained, at least in part, by some environmental components.

Inter- and transgenerational epigenetic inheritance: evidence in asthma and COPD?

Evidence is now emerging that early life environment can have lifelong effects on metabolic, cardiovascular, and pulmonary function in offspring, a concept also known as fetal or developmental programming. In mammals, developmental programming is thought to occur mainly via epigenetic mechanisms, which include DNA methylation, histone modifications, and expression of non-coding RNAs. The effects of developmental programming can be induced by the intrauterine environment, leading to intergenerational epigenetic effects from one generation to the next. Transgenerational epigenetic inheritance may be considered when developmental programming is transmitted across generations that were not exposed to the initial environment which triggered the change. So far, inter- and transgenerational programming has been mainly described for cardiovascular and metabolic disease risk. In this review, we discuss available evidence that epigenetic inheritance also occurs in respiratory diseases, using asthma and chronic obstructive pulmonary disease (COPD) as examples. While multiple epidemiological as well as animal studies demonstrate effects of 'toxic' intrauterine exposure on various asthma-related phenotypes in the offspring, only few studies link epigenetic marks to the observed phenotypes. As epigenetic marks may distinguish individuals most at risk of later disease at early age, it will enable early intervention strategies to reduce such risks. To achieve this goal further, well designed experimental and human studies are needed.

Update on epigenetics in allergic disease

Chronic inflammatory diseases, including allergies and asthma, are the result of complex gene-environment interactions. One of the most challenging questions in this regard relates to the biochemical mechanism of how exogenous environmental trigger factors modulate and modify gene expression, subsequently leading to the development of chronic inflammatory conditions. Epigenetics comprises the umbrella of biochemical reactions and mechanisms, such as DNA methylation and chromatin modifications on histones and other structures. Recently, several lifestyle and environmental factors have been investigated in terms of such biochemical interactions with the gene expression-regulating machinery: allergens; microbes and microbial compounds; dietary factors, including vitamin B12, folic acid, and fish oil; obesity; and stress. This article aims to update recent developments in this context with an emphasis on allergy and asthma research.

Maternal Antiasthma Simplified Herbal Medicine Intervention therapy prevents airway inflammation and modulates pulmonary innate immune responses in young offspring mice

BACKGROUND

Maternal asthma is a risk factor for asthma in offspring; however, transmission of the risk for allergic asthma without direct offspring sensitization has not been explored.

OBJECTIVE

To determine whether offspring from mothers with ovalbumin (OVA)-sensitized asthma would develop airway disease at first-ever exposure to OVA and whether preconception maternal treatment with the Antiasthma Simplified Herbal Medicine Intervention (ASHMI) or dexamethasone (DEX) could modify this risk in offspring.

METHODS

Female BALB/c mice (F0) with OVA-induced asthma were generated using established protocols. Mice with asthma were treated with ASHMI, DEX, or water for 6 to 7 weeks. Naive mice served as controls. Subsequently, mice were mated. Twelve-day-old F1 offspring received 3 consecutive intranasal low- or high-dose OVA exposures without sensitization. Forty-eight hours later, airway inflammation, mucus hypersecretion, serum antibodies, and cytokines were evaluated.

RESULTS

Offspring from OVA-sensitized mothers, but not naive mothers, showed eosinophilic and neutrophilic airway inflammation, and mucus hyperplasia after OVA exposure and he presence of OVA-specific IgG1 and IgG2a. Offspring of ASHMI- and DEX-treated mothers showed decreased airway inflammation and mucus hypersecretion after low-dose OVA (P < .05-.001 for the 2 comparisons vs offspring of OVA/Sham mothers). Offspring of ASHMI-treated, but not DEX-treated, mothers were protected after the high-dose OVA challenge (P < .05-.01 vs offspring OVA/Sham). Maternal ASHMI therapy was associated with increased IgG2a (P < .01 vs offspring of OVA/Sham mothers) and decreased bronchoalveolar lavage fluid CXCL-1 and eotaxin-1 levels (P < .01 and P < .05, respectively, vs offspring of OVA/Sham mothers).

CONCLUSION

Offspring of mothers with OVA-induced asthma developed airway inflammation and mucus to first-ever OVA exposure without prior sensitization. Maternal therapy with ASHMI was superior to DEX in decreasing offspring susceptibility to airway disease and could be a strategy to lower asthma prevalence.

Maternal stress during pregnancy increases neonatal allergy susceptibility: role of glucocorticoids

We sought to test experimentally whether maternal stress can promote susceptibility to development of asthma-like allergic airways disease in offspring. Normal pregnant mice (day 15) were subjected to a single restraint stress exposure. We subsequently tested their offspring for the development of airway hyperreactivity (AHR) and allergic airway inflammation (AI), after an intentionally suboptimal sensitization protocol. The offspring of stressed mothers showed levels of AI and enhanced airway responses to methacholine comparable to those seen in fully sensitized and challenged positive control animals; in contrast, minimal effects were seen in control offspring. Restraint stress caused a rapid and large increase in plasma corticosterone levels. Maternal treatment with dexamethasone on day 15 of pregnancy mimicked the stress effect and reproduced the AI and AHR outcomes, whereas blockade of the stress-induced corticosterone surge with metyrapone pretreatment of pregnant mice abrogated the effect. We conclude that stress-triggered glucocorticoids during pregnancy can increase susceptibility to allergy in offspring. Because inflammation typically includes a stress hormone response, the results also suggest a common pathway by which various injurious exposures during pregnancy might increase offspring susceptibility to asthma.

Microbial exposure and onset of allergic diseases - potential prevention strategies?

Chronic inflammatory diseases are a major health problem with global dimension. Particularly, the incidence of allergic diseases has been increased tremendously within the last decades. This world-wide trend clearly indicates the demand for new approaches in the investigation of early allergy development. Recent studies underlined the basic postulate of the hygiene hypothesis that early exposure to microbial stimuli plays a crucial role in the prevention of chronic inflammatory conditions in adulthood. There is ample evidence that, both, exogenous microbes and endogenous microbial communities, the human microbiota, shape the developing immune system and might be involved in prevention of pathologic pro-inflammatory trails. According to the Barker hypothesis, epidemiological studies pointed to transmaternal transmission from the mother to the offspring already in prenatal life. Experimental data from murine models support these findings. This state of the art review provides an overview on the current literature and presents new experimental concepts that point out to future application in the prevention of allergic diseases.

Effect of barrier microbes on organ-based inflammation

The prevalence and incidence of chronic inflammatory disorders, including allergies and asthma, as well as inflammatory bowel disease, remain on the increase. Microbes are among the environmental factors that play an important role in shaping normal and pathologic immune responses. Several concepts have been put forward to explain the effect of microbes on the development of these conditions, including the hygiene hypothesis and the microbiota hypothesis. Recently, the dynamics of the development of (intestinal) microbial colonization, its effect on innate and adaptive immune responses (homeostasis), and the role of environmental factors, such as nutrition and others, have been extensively investigated. Furthermore, there is now increasing evidence that a qualitative and quantitative disturbance in colonization (dysbiosis) is associated with dysfunction of immune responses and development of various chronic inflammatory disorders. In this article the recent epidemiologic, clinical, and experimental evidence for this interaction is discussed.

Asthma phenotyping, therapy, and prevention: what can we learn from systems biology?

Asthma has a high prevalence worldwide, and contributes significantly to the socioeconomic burden. According to a classical paradigm, asthma symptoms are attributable to an allergic, Th2-driven airway inflammation that causes airway hyperresponsiveness and results in reversible airway obstruction. Diagnosis and therapy are based mainly on these pathophysiologic concepts. However, these have increasingly been challenged by findings of recent studies, and the frequently observed failure in controlling asthma symptoms. Important recent findings are the protective "farm effect" in children, the possible prenatal mechanisms of this protection, the recognition of many different asthma phenotypes in children and adults, and the partly disappointing clinical effects of new targeted therapeutic approaches. Systems biology approaches may lead to a more comprehensive view of asthma pathophysiology and a higher success rate of new therapies. Systems biology integrates clinical and experimental data by means of bioinformatics and mathematical modeling. In general, the "-omics" approach, and the "mathematical modeling" approach can be described. Recently, several consortia have been attempting to bring together clinical and molecular data from large asthma cohorts, using novel experimental setups, biostatistics, bioinformatics, and mathematical modeling. This "systems medicine" approach to asthma will help address the different asthma phenotypes with adequate therapy and possibly preventive strategies.

Allergy Takes Its Toll: The Role of Toll-like Receptors in Allergy Pathogenesis

Reduced early microbial exposure in early life has become a leading candidate to explain the escalating rate of allergic disease and has generated intense interest in the interaction between the developing immune system and the microbial environment. Infants depend on "signal" from the microbial environment to mature both T-helper cell type 1 and regulatory immune function. These signals, mediated through microbial pattern-recognition receptors, namely toll-like receptors (TLRs), seem essential to achieving the immunologic balance required for (1) pathogen protection and (2) normal immune tolerance. Despite this, the normal development of TLR function has never been documented. There is preliminary evidence that TLR function is under the influence of both genetic factors (genetic polymorphisms) and early environmental exposures including microbial exposure and breast feeding, and maternal smoking. This review explores the evidence that allergy is associated with developmental variations in TLR-mediated immune function and how this may be relevant for disease prevention.

The microbiome of the lung

Investigation of the lung microbiome is a relatively new field. Although the lungs were classically believed to be sterile, recently published investigations have identified microbial communities in the lungs of healthy humans. At the present time, there are significant methodologic and technical hurdles that must be addressed in ongoing investigations, including distinguishing the microbiota of the upper and lower respiratory tracts. However, characterization of the lung microbiome is likely to provide important pathogenic insights into cystic fibrosis, respiratory disease of the newborn, chronic obstructive pulmonary disease, and asthma. In addition to characterization of the lung microbiome, the microbiota of the gastrointestinal tract have profound influence on the development and maintenance of lung immunity and inflammation. Further study of gastrointestinal-respiratory interactions is likely to yield important insights into the pathogenesis of pulmonary diseases, including asthma. As this field advances over the next several years, we anticipate that studies using larger cohorts, multicenter designs, and longitudinal sampling will add to our knowledge and understanding of the lung microbiome.