99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: controversial aspects of the 'hygiene hypothesis'

Geohelminths: Use in the Treatment of Selected Human Diseases

Research on the therapeutic use of parasites has been ongoing since the development of the "hygiene hypothesis". Parasites can stimulate the Th2-dependent response and suppress the Th1-dependent response, which is intensified in many diseases, especially allergic and autoinflammatory ones. In this review, we present the types of parasites used in helminth therapy and the range of diseases in which they may be useful. We also present the results of clinical trials conducted so far, which confirm the safety of such therapy and provide promising outcomes.

Helicobacter pylori Infection Does Not Protect Against Allergic Diseases: Evidence From a Pediatric Cohort From Northern Sardinia, Italy

BACKGROUND

The "hygiene hypothesis" states that reduced exposure to microbial antigens due to an excessively hygienic environment can increase the risk of developing autoimmune diseases, including atopic disorders and asthma. In recent decades, there has been a progressive decline in the prevalence of numerous microorganisms following improved hygienic-sanitary conditions. More specifically, several studies reported an inverse association between the reduction in Helicobacter pylori infection and the rise of asthma and allergic disorders.

AIM

To evaluate the prevalence of atopic disorders in a pediatric population in relation to seropositivity against H. pylori.

METHODS

Children from Northern Sardinia, Italy, referred to the local Children's Hospital for any reason, were investigated to identify risk factors, especially H. pylori infection, associated with atopic disorders. A validated questionnaire, including demographics, house size, history of breastfeeding, residence, school or daycare center attendance, exposure to animals, and a defined diagnosis of atopy-including asthma-was filled out by a trained pediatrician according to parents' answers and child records. A blood sample was collected from each participant and immunoglobulin G against H. pylori was assessed by a locally validated ELISA test.

RESULTS

The seroprevalence of H. pylori infection was 11.7% among 492 children (240 females). Thirty-two children had a confirmed diagnosis of asthma and 12 of allergy. No one child showed both conditions. Statistically significant differences in H. pylori seropositivity were not detected between children with or without atopy (8.4% vs. 12.6; p = 0.233). Although atopic disorders were more frequent in children exposed to traditional atopic risk factors, none of them showed to be significant after adjusting for all covariates.

CONCLUSIONS

Serologically assessed H. pylori infection was not significantly associated with a reduced risk of atopic diseases in children.

Heterogeneity of sensitization profiles and clinical phenotypes among patients with seasonal allergic rhinitis in Southern European countries-The @IT.2020 multicenter study

BACKGROUND

Pollen allergy poses a significant health and economic burden in Europe. Disease patterns are relatively homogeneous within Central and Northern European countries. However, no study broadly assessed the features of seasonal allergic rhinitis (SAR) across different Southern European countries with a standardized approach.

OBJECTIVE

To describe sensitization profiles and clinical phenotypes of pollen allergic patients in nine Southern European cities with a uniform methodological approach.

METHODS

Within the @IT.2020 multicenter observational study, pediatric and adult patients suffering from SAR were recruited in nine urban study centers located in seven countries. Clinical questionnaires, skin prick tests (SPT) and specific IgE (sIgE) tests with a customized multiplex assay (Euroimmun Labordiagnostika, Lübeck, Germany) were performed.

RESULTS

Three hundred forty-eight children (mean age 13.1 years, SD: 2.4 years) and 467 adults (mean age 35.7 years SD: 10.0 years) with a predominantly moderate to severe, persistent phenotype of SAR were recruited. Grass pollen major allergenic molecules (Phl p 1 and/or Phl p 5) ranged among the top three sensitizers in all study centers. Sensitization profiles were very heterogeneous, considering that patients in Rome were highly poly-sensitized (sIgE to 3.8 major allergenic molecules per patient), while mono-sensitization was prominent and heterogeneous in other cities, such as Marseille (sIgE to Cup a 1: n = 55/80, 68.8%) and Messina (sIgE to Par j 2: n = 47/82, 57.3%). Co-sensitization to perennial allergens, as well as allergic comorbidities also broadly varied between study centers.

CONCLUSIONS

In Southern European countries, pollen allergy is heterogeneous in terms of sensitization profiles and clinical manifestations. Despite the complexity, a unique molecular, multiplex, and customized in-vitro IgE test detected relevant sensitization in all study centers. Nevertheless, this geographical diversity in pollen allergic patients imposes localized clinical guidelines and study protocols for clinical trials of SAR in this climatically complex region.

A short history from Karelia study to biodiversity and public health interventions

Contact with natural environments enriches the human microbiome, promotes immune balance and protects against allergies and inflammatory disorders. In Finland, the allergy & asthma epidemic became slowly visible in mid 1960s. After the World War II, Karelia was split into Finnish and Soviet Union (now Russia) territories. This led to more marked environmental and lifestyle changes in the Finnish compared with Russian Karelia. The Karelia Allergy Study 2002–2022 showed that allergic conditions were much more common on the Finnish side. The Russians had richer gene-microbe network and interaction than the Finns, which associated with better balanced immune regulatory circuits and lower allergy prevalence. In the Finnish adolescents, a biodiverse natural environment around the homes associated with lower occurrence of allergies. Overall, the plausible explanation of the allergy disparity was the prominent change in environment and lifestyle in the Finnish Karelia from 1940s to 1980s. The nationwide Finnish Allergy Programme 2008–2018 implemented the biodiversity hypothesis into practice by endorsing immune tolerance, nature contacts, and allergy health with favorable results. A regional health and environment programme, Nature Step to Health 2022–2032, has been initiated in the City of Lahti, EU Green Capital 2021. The programme integrates prevention of chronic diseases (asthma, diabetes, obesity, depression), nature loss, and climate crisis in the spirit of Planetary Health. Allergic diseases exemplify inappropriate immunological responses to natural environment. Successful management of the epidemics of allergy and other non-communicable diseases may pave the way to improve human and environmental health.

The increase in allergic conditions based on a review of literature

The global interest in allergic disease epidemiology in the 20^th and 21^st centuries is a result of their growing prevalence of unprecedented, pandemic proportions. According to the 2011 White Book on Allergy, the prevalence of allergic conditions rises dramatically worldwide, both in developed and developing countries, with the rates of asthma ranging from 1% to 20%, allergic rhinitis from 1% to 18%, and skin allergies from 2% to 10% in various populations. The growing prevalence of allergies is particularly noticeable in children, who have been affected most by this trend for the last two decades.

The Environmental Microbiome, Allergic Disease, and Asthma

The environmental microbiome represents the entirety of the microbes and their metabolites that we encounter in our environments. A growing body of evidence supports the role of the environmental microbiome in risk for and severity of allergic diseases and asthma. The environmental microbiome represents a ubiquitous, lifelong exposure to non-self antigens. During the critical window between birth and 1 year of life, interactions between our early immune system and the environmental microbiome have 2 consequences: our individual microbiome is populated by environmental microbes, and our immune system is trained regarding which antigens to tolerate. During this time, a diversity of exposures appears largely protective, dramatically decreasing the risk of developing allergic diseases and asthma. As we grow older, our interactions with the environmental microbiome change. While it continues to exert influence over the composition of the human microbiome, the environmental microbiome becomes increasingly a source for antigenic stimulation and infection. The same microbial exposure protective against disease development may exacerbate disease severity. Although much has been learned about the importance of the environmental microbiome in allergic disease, much more remains to be understood about these complicated interactions between our environment, our microbiome, our immune system, and disease.

Respiratory tract infections in children with allergic asthma on allergen immunotherapy during influenza season

To describle how respiratory tract infections (RTIs) that occurred in children with allergic asthma (AA) on allergen immunotherapy (AIT) during an influenza season. Data including clinical symptoms and treatment history of children (those with AA on AIT and their siblings under 14 years old), who suffered from RTIs during an influenza season (Dec 1st, 2019–Dec 31st, 2019), were collected (by face to face interview and medical records) and analyzed. Children on AIT were divided into 2 groups: stage 1 (dose increasing stage) and stage 2 (dose maintenance stage). Their siblings were enrolled as control. During the study period, 49 children with AA on AIT (33 patients in stage 1 and 16 patients in stage 2) as well as 49 children without AA ( their siblings ) were included. There were no significant differences in occurrences of RTIs among the three groups (p > 0.05). Compared with children in the other two groups, patients with RTIs in stage 2 had less duration of coughing and needed less medicine. Children on AIT with maintenance doses had fewer symptoms and recovered quickly when they were attacked by RTIs, which suggested that AIT with dose maintenance may enhance disease resistance of the body.

First evaluation of a symbiotic food supplement in an allergen exposure chamber in birch pollen allergic patients

Background

Allergic rhinitis/rhinoconjunctivitis is the most common immune disease worldwide, but still largely underestimated, underdiagnosed, and undertreated. Dysbiosis and reduced microbial diversity is linked to the development of allergies, and the immunomodulatory effects of pro- and prebiotics might be used to counteract microbiome dysbiosis in allergy. Adequate symbiotic (multi-strain pro-, plus prebiotic) supplementation can be suggested as a complementary approach in the management of allergic rhinitis.

Objective

The effects of the daily intake of a symbiotic food supplement (combination of Lactobacillus acidophilus NCFM and Bifidobacterium lactis BL-04 with Fructo-Oligosaccharides) for 4 months in birch pollen allergic rhinoconjunctivitis patients were investigated for the first time in an allergen exposure chamber (AEC) allowing standardised, reproducible pollen exposure before and after intake.

Methods

Eligible patients were exposed to birch pollen (8000 pollen/m³ for 120 min) at the GA²LEN AEC, at baseline (V1) and final visit (V3) outside the season. The Total Symptom Score (TSS) and the scores for nose, eye, bronchial system, and others were evaluated every 10 min during exposure. Other secondary endpoints were the changes in well-being, Peak Nasal Inspiratory Flow (PNIF), lung function parameters, and safety. Co-primary endpoints were differences in Total Nasal Symptom Score (TNSS) and TSS after 120 min of exposure between both visits. Temporal evolution of symptom scores were analysed in an exploratory way using linear mixed effects models.

Results

27 patients (mean age 45 years, 15% male) completed the study. Both co-primary endpoints showed significant improvement after intake of the symbiotic. Median TNSS and TSS were decreased 50% and 80% at 120 min (adjusted p-value = 0.025 and p < 0.01 respectively).

All four symptom scores and the personal well-being, improved to a clinically relevant extent over time, visible by a weaker increase in symptoms during 120 min of the final birch pollen exposure. No relevant differences were observed for PNIF, PEF, and spirometry. There were no airway obstructions or lung restrictions before and after both exposures. Late phase reactions after exposure were reduced after V3, documenting a better birch pollen tolerability of the patients. The safety and tolerability profile of the symbiotic food supplement was excellent, no adverse events (AEs) were observed.

Conclusions

This first evaluation of a symbiotic food supplement in an AEC in rhinoconjunctivitis patients with or without asthma induced by birch pollen revealed a significant beneficial effect, harnessing significant improvements of symptoms and well-being while maintaining an excellent safety and tolerability profile.

EAACI position paper on diet diversity in pregnancy, infancy and childhood: Novel concepts and implications for studies in allergy and asthma

To fully understand the role of diet diversity on allergy outcomes and to set standards for conducting research in this field, the European Academy of Allergy and Clinical Immunology Task Force on Diet and Immunomodulation has systematically explored the association between diet diversity and allergy outcomes. In addition, a detailed narrative review of information on diet quality and diet patterns as they pertain to allergic outcomes is presented. Overall, we recommend that infants of any risk category for allergic disease should have a diverse diet, given no evidence of harm and some potential association of benefit in the prevention of particular allergic outcomes. In order to harmonize methods for future data collection and reporting, the task force members propose relevant definitions and important factors for consideration, when measuring diet diversity in the context of allergy. Consensus was achieved on practice points through the Delphi method. It is hoped that the definitions and considerations described herein will also enable better comparison of future studies and improve mechanistic studies and pathway analysis to understand how diet diversity modulates allergic outcomes.

The Role of Diet Diversity and Diet Indices on Allergy Outcomes

Nutrients in foods are not eaten in isolation and food intake interacts in a complex manner, affecting health and disease outcomes. For this reason, focusing on the whole "pattern" of dietary intake instead of the single nutrients or groups of nutrients when studying diseases outcomes is increasingly appealing and growing. Diet diversity refers to the variety of foods being eaten, and the terms, diversity or variety, are often used interchangeably. When the overall diet is characterized by healthy foods, diet diversity will reflect a diversity/variety of healthy foods eaten over a period of time. The introduction of solid foods in the 1st year of life is considered a measure of increased diet diversity. Consuming a diverse range of foods and food allergens in the first year of life may increase intake of important nutrients and positively affect the gut microbiome structure and function. Intake of omega-3 fatty acids and fibers/prebiotics may be particularly important but more information is required about dose and which individuals are most likely to benefit. Increased diet diversity in the first year of life is also associated with reduced food allergy outcomes. In addition to diet diversity, diet indices are considered measures of overall diet quality and can be used as a simple assessment of dietary intake. The focus of this paper is to review and critically address the current knowledge of the association between diet diversity and diet indices and allergy outcomes. Based on the current evidence, we recommend the introduction of solid foods, including common allergenic solids, during the 1st year of life, according to the infant's neuro-developmental abilities and familial or cultural habits. For infants with severe AD and/or FA, medical assessment may be advisable before introducing common food allergens into the diet. Limited evidence exist about the role of diet indices in pregnancy and allergic disease in the offspring, and the most promising results indicate a reduction in childhood wheeze and/or asthma intake.

A biodiversity hypothesis

Biodiversity hypothesis states that contact with natural environments enriches the human microbiome, promotes immune balance and protects from allergy and inflammatory disorders. We are protected by two nested layers of biodiversity, microbiota of the outer layer (soil, natural waters, plants, animals) and inner layer (gut, skin, airways). The latter inhabits our body and is colonized from the outer layer. Explosion of human populations along with cultural evolution is profoundly changing our environment and lifestyle. Adaptive immunoregulatory circuits and dynamic homeostasis are at stake in the newly emerged urban surroundings. In allergy, and chronic inflammatory disorders in general, exploring the determinants of immunotolerance is the key for prevention and more effective treatment. Loss of immunoprotective factors, derived from nature, is a new kind of health risk poorly acknowledged until recently. The paradigm change has been implemented in the Finnish allergy programme (2008-2018), which emphasized tolerance instead of avoidance. The first results are promising, as allergy burden has started to reduce. The rapidly urbanizing world is facing serious biodiversity loss with global warming, which are interconnected. Biodiversity hypothesis of health and disease has societal impact, for example, on city planning, food and energy production and nature conservation. It has also a message for individuals for health and well-being: take nature close, to touch, eat, breathe, experience and enjoy. Biodiverse natural environments are dependent on planetary health, which should be a priority also among health professionals.

Postnatal Administration of Lactobacillus rhamnosus HN001 Ameliorates Perinatal Broad-Spectrum Antibiotic-Induced Reduction in Myelopoiesis and T Cell Activation in Mouse Pups

SCOPE

This study addresses whether administration of Lactobacillus rhamnosus HN001 could mitigate the effects of a compromised gut microbiota on the composition of mature leukocytes and granulocyte-macrophage progenitor cells (GMPs) in newborn mice.

METHODS AND RESULTS

Pregnant dams receive oral broad-spectrum antibiotics, which dramatically decrease the gut microbial composition analyzed by 16S rRNA sequencing. Perinatal antibiotic treatment decreases the proportions of bone marrow (BM) GMPs (postnatal day (PND2): 0.5% vs 0.8%, PND4: 0.2% to 0.6%) and mature granulocytes (33% vs 24% at PND2), and spleen granulocytes (7% vs 17% at PND2) and B cells (PND2:18% vs 28%, PND4:11% vs 22%). At PND35, T helper (Th) cells (20% vs 14%) and cytotoxic T (Tc) cells (10% vs 8%) decrease in the spleen. Oral administration of L. rhamnosus HN001 to neonatal pups (PND1-7) restores the antibiotic-induced changes of GMPs and granulocytes in BM and spleen, and further increases splenic granulocytes in control pups. At PND35, splenic proportions of B and Th but not Tc cells are restored.

CONCLUSION

Postnatal administration of a single bacterial strain efficiently restores granulopoiesis and most T cell activation in neonatal mice that suffer from a perinatal antibiotic-induced compromised gut microbiota at birth.

Parental occupations and risk for Crohn's disease in children

BACKGROUND AND OBJECTIVES

Lacunae exist on the identity of specific environmental risk factors that associate with Crohn's disease (CD). We hypothesized that indirect exposures acquired via the parents' occupation may confer susceptibility.

METHODS

A case-control study based on children diagnosed with CD (prior to age 20) at a tertiary care gastroenterology clinic in Montreal, Canada was carried out. Population- and hospital-based controls without IBD were selected. Information on occupations held by the parents was acquired from interview. Jobs were coded using the Canadian National Occupational Classification for Statistics. Associations were examined using logistic regression accounting for potential confounders. Odds ratios (OR) and corresponding 95% confidence intervals (CI) were estimated.

RESULTS

A total of 466 cases and 335 controls were studied. The mean (±SD) age of the cases (12.4 ± 3.2) was slightly higher than controls (10.5 ± 4.9). Gender and ethnicity were equally distributed between the groups. Logistic regression analysis suggested that children whose fathers worked as retail salespersons/sales clerks [odds ratio (OR) 3.6, 95% confidence interval (CI) 1.2-11.1], and whose mothers worked as administrative secretaries (OR 3.2, 95% CI 1.6-6.4), were more likely to be at risk for CD. Mothers who worked as either early childhood educators (OR 2.3, 95% CI 0.85-6.2) or as clerks (OR 2.8, 95% CI 0.8-9.9) also appeared to confer risks, but these associations were statistically not significant.

CONCLUSION

Parental occupations related to 'social mixing' that can potentially enhance exposure to infectious agents, appear to confer higher risk for CD in children.

Epigenetics and allergy: from basic mechanisms to clinical applications

Allergic diseases are on the rise in the Western world and well-known allergy-protecting and -driving factors such as microbial and dietary exposure, pollution and smoking mediate their influence through alterations of the epigenetic landscape. Here, we review key facts on the involvement of epigenetic modifications in allergic diseases and summarize and critically evaluate the lessons learned from epigenome-wide association studies. We show the potential of epigenetic changes for various clinical applications: as diagnostic tools, to assess tolerance following immunotherapy or possibly predict the success of therapy at an early time point. Furthermore, new technological advances such as epigenome editing and DNAzymes will allow targeted alterations of the epigenome in the future and provide novel therapeutic tools.

Thumb-Sucking, Nail-Biting, and Atopic Sensitization, Asthma, and Hay Fever

BACKGROUND

The hygiene hypothesis suggests that early-life exposure to microbial organisms reduces the risk of developing allergies. Thumb-sucking and nail-biting are common childhood habits that may increase microbial exposures. We tested the hypothesis that children who suck their thumbs or bite their nails have a lower risk of developing atopy, asthma, and hay fever in a population-based birth cohort followed to adulthood.

METHODS

Parents reported children's thumb-sucking and nail-biting habits when their children were ages 5, 7, 9, and 11 years. Atopic sensitization was defined as a positive skin-prick test (≥2-mm weal) to ≥1 common allergen at 13 and 32 years. Associations between thumb-sucking and nail-biting in childhood, and atopic sensitization, asthma, and hay fever at these ages were assessed by using logistic regression with adjustments for sex and other potential confounding factors: parental atopy, breastfeeding, pet ownership, household crowding, socioeconomic status, and parental smoking.

RESULTS

Thirty-one percent of children were frequent thumb-suckers or nail-biters at ≥1 of the ages. These children had a lower risk of atopic sensitization at age 13 years (odds ratio 0.67, 95% confidence interval 0.48-0.92, P = .013) and age 32 years (odds ratio 0.61, 95% confidence interval 0.46-0.81, P = .001). These associations persisted when adjusted for multiple confounding factors. Children who had both habits had a lower risk of atopic sensitization than those who had only 1. No associations were found for nail-biting, thumb-sucking, and asthma or hay fever at either age.

CONCLUSIONS

Children who suck their thumbs or bite their nails are less likely to have atopic sensitization in childhood and adulthood.

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.

Respiratory allergies in childhood: Recent advances and future challenges

The burden of allergic airway diseases still represents a major health problem in childhood. Despite many different options are currently available for the diagnostic work-up and management, the overall disease control in terms of impact on quality of life, morbidity and mortality, is not yet satisfactory. The extreme variability of individual risk factors and severity determinants may account for it. On the other side, the knowledge of the multifaceted allergy background could pave the way to primary prevention, early intervention and disease course modification. In fact, most of current research is focusing on the identification of biological and clinical predictive markers of allergy and asthma onset. This review aims at summarizing the latest achievements concerning the complex inter-relation between genetic predisposition and environmental factors, and their impact on prevention strategies and early identification of at risk subjects. An update on the diagnostic and monitoring tools as well as an insight into the newest treatments options is also provided.

Inflammation and infections in asthma

INTRODUCTION

Asthma is driven by an inflammatory response against normally harmless environmental inorganic and organic compounds in the respiratory tract. Immune responses to airborne pathogens such as viruses and bacteria may reduce the allergic responses but are also known to trigger asthma attacks and eventually lead to severe disease condition.

OBJECTIVE

To investigate the role of respiratory pathogens concerning the induction or protection against acute or chronic asthma manifestations.

METHODS

We included 131 articles for the final review according to their relevance with the subject.

RESULTS

There is apparently contradictory interaction of respiratory germs in the airways of asthmatics which may be protective on one angle but deleterious on the other.

CONCLUSION

The relationship between inflammation and remodeling and the pathogenic role of viral and bacterial infection in the airways of asthmatic patients is still highly debatable and incompletely understood.

Adaptation in the innate immune system and heterologous innate immunity

The innate immune system recognizes deviation from homeostasis caused by infectious or non-infectious assaults. The threshold for its activation seems to be established by a calibration process that includes sensing of microbial molecular patterns from commensal bacteria and of endogenous signals. It is becoming increasingly clear that adaptive features, a hallmark of the adaptive immune system, can also be identified in the innate immune system. Such adaptations can result in the manifestation of a primed state of immune and tissue cells with a decreased activation threshold. This keeps the system poised to react quickly. Moreover, the fact that the innate immune system recognizes a wide variety of danger signals via pattern recognition receptors that often activate the same signaling pathways allows for heterologous innate immune stimulation. This implies that, for example, the innate immune response to an infection can be modified by co-infections or other innate stimuli. This "design feature" of the innate immune system has many implications for our understanding of individual susceptibility to diseases or responsiveness to therapies and vaccinations. In this article, adaptive features of the innate immune system as well as heterologous innate immunity and their implications are discussed.

Hygiene hypothesis and periodontitis--a possible association

Hygiene hypothesis has been proposed more than two decades back to explain an increasing prevalence of allergic diseases and atopy. It states that, a lack of early childhood exposure to infectious agents increases susceptibility to allergic diseases and atopy later in life. The evidence in relation to hygiene hypothesis is controversial and inconclusive. Moreover, its underlying mechanisms are elusive and remain to be elucidated. Periodontitis is an inflammatory disease initiated by microorganisms present in the plaque biofilm. Association between periodontitis and various systemic diseases has already been established and is currently an area of interest particularly in periodontal research. Consistent with hygiene hypothesis, some researchers believed that pathogens associated with periodontal diseases might have a protective role in the development of asthma and other allergic diseases. Very few studies attempted to explore the concept of association between periodontitis, asthma and other respiratory allergic diseases which could neither support such a protective role for periodontal diseases nor reject such an association. This suggests a need for additional research to examine the relevance of hygiene hypothesis in periodontics. The purpose of the present article is to review the plausible scientific explanations available for hygiene hypothesis, to review some studies relating periodontitis, asthma and other respiratory allergic diseases and to stress the need for further research.

Does Candida albicans Als5p amyloid play a role in commensalism in Caenorhabditis elegans?

Candida albicans, a dimorphic fungus and an opportunistic pathogen, possesses a myriad of adherence factors, including members of the agglutinin-like sequence (Als) family of mannoproteins. The adhesin Als5p mediates adhesion to many substrates and is upregulated during commensal interactions but is downregulated during active C. albicans infections. An amyloid-forming core sequence at residues 325 to 331 is important for Als5p function, because a single-amino-acid substitution at position 326 (V326N) greatly reduces Als5p-mediated adherence. We evaluated the role of Als5p in host-microbe interactions by using Caenorhabditis elegans nematodes as a host model and feeding them Saccharomyces cerevisiae expressing Als5p on the surface. Als5p-expressing yeast had 8.5- and 3.5-fold-increased intestinal accumulation rates compared to Als5p-nonexpressing S. cerevisiae or yeast expressing amyloid-deficient Als5p(V326N), respectively. Surprisingly, this accumulation delayed S. cerevisiae-induced killing of C. elegans. The median survival time was nearly twice as long as that of nematodes fed nonexpressing or non-amyloid-forming Als5p(V326N)-expressing S. cerevisiae. Treatment with the amyloid-inhibiting dye Congo red or repression of Als5p expression abrogated the protective effect of Als5p. Furthermore, Als5p had no effect on oocyte quantity or quality, since nematodes fed either empty vector (EV)- or Als5p(V326N)-expressing S. cerevisiae had similar egg-laying and egg-hatching rates. This study is the first, to our knowledge, to show that expression of an amyloid-forming protein can attenuate pathogenicity in C. elegans.

Investigation of the effect of probiotic exposure on filaggrin expression in an experimental model of canine atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) results from complex interactions between an impaired skin barrier and immunological stimulation. Filaggrin is a key protein for the skin barrier, and its expression is decreased in subsets of atopic dogs and can be modified by inflammation; thus, immunomodulatory approaches may alter its expression. Probiotics have been explored for the prevention and treatment of allergies, owing to their immunomodulatory properties; however, it is currently unknown whether they can modulate filaggrin expression.

OBJECTIVE

The purpose of this study was to evaluate whether probiotics can modulate filaggrin expression in an experimental model of canine AD.

ANIMALS AND METHODS

Eighteen atopic (11 probiotic exposed and seven control) and five normal beagles were challenged for three consecutive days with Dermatophagoides farinae. Skin biopsies were taken before (day 0), at the peak (day 3) and after the end of the allergen challenge (day 10). Immunohistochemistry for filaggrin was done using a polyclonal antibody specific for canine filaggrin, and staining was scored both subjectively (for intensity, granularity and continuity) and objectively, by tracing the stratum granulosum and calculating the percentage of filaggrin per unit traced area.

RESULTS

Analysis of variance of the percentage of filaggrin in the stratum granulosum showed a significant effect of group (P = 0.0414, AD < normal), time (P = 0.0066, days 3 and 10 > day 0) and marginal group × time interaction (P = 0.0606). Within the atopic group, exposure to probiotics did not change filaggrin expression. No significant differences were found in the subjective scores among groups.

CONCLUSIONS AND CLINICAL IMPORTANCE

It is concluded that probiotic exposure early in life does not alter filaggrin expression in this AD model.

Broadening the translational immunology landscape

It is just over 5 years sinceClinical and Experimental Immunology came under the direction of a new team of Editors and made a concerted effort to refresh its approach to promoting clinical and applied immunology through its pages. There were two major objectives: to foster papers in a field which, at the time, we loosely termed ‘translational immunology’; and to create a forum for the presentation and discussion of immunology that is relevant to clinicians operating in this space. So, how are we doing with these endeavours? This brief paper aims to summarize some of the key learning points and successes and highlight areas in which translational gaps remain.

Association of Hepatitis A exposure and TIM-1 with childhood allergic asthma

BACKGROUND

Hepatitis A virus (HAV) receptor (TIM-1) polymorphism plays an important role in asthma and autoimmune diseases. Objective. To analyze the association of TIM-1 polymorphism and HAV infection with childhood allergic asthma in Southwest China.

METHODS

TIM-1 exon 4 (157insMTTTVP) and two polymorphism loci, -416G>C and -1454G>A, in the HAV receptor promoter region were studied. Polymerase chain reaction (PCR) was used to test the genotypes of three polymorphism loci among 579 cases of asthma and 524 controls. The HAV infection status was determined in a case-control study with stratified analysis.

RESULTS

HAV exposure associated with childhood allergic asthma in the study population was compared with controls (odds ratio (OR) = 0.181, 95% confidence interval (CI) 0.126-0.260, p < .001). The -416G>C polymorphism was associated with asthma (OR = 1.384, 95% CI 1.148-1.669, p < .001), but the insertion variant 157delMTTTVP of exon 4 and the -1454G>A polymorphism were not.

CONCLUSION

Our results indicated that the -416G>C polymorphism of the TIM-1 gene is associated with childhood allergic asthma, providing a better understanding of the pathogenesis of the allergic asthma among children aged below 15 years in Southwest China.

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.

Expanding the hygiene hypothesis: early exposure to infectious agents predicts delayed-type hypersensitivity to Candida among children in Kilimanjaro

Background

Multiple lines of evidence suggest that infections in early life prevent the development of pathological immune responses to allergens and autoantigens (the hygiene hypothesis). Early infections may also affect later immune responses to pathogen antigen.

Methods

To evaluate an association between early infections and immune responses to pathogen antigen, delayed-type hypersensitivity (DTH) to Candida albicans was evaluated among 283 2- to 7-year-old children in Kilimanjaro, Tanzania. A questionnaire and physical examination were used to characterize variables reflecting early exposure to infectious agents (family size, house construction materials, BCG vaccination, hospitalization history). Logistic regression was used to evaluate the association between early exposure to infectious agents and DTH to C. albicans.

Results

Triceps skinfold thickness (OR: 1.11; 95% CI: 1.01, 1.22) and age (OR: 1.27; 95% CI: 1.04, 1.55) were positively associated with DTH to C. albicans. Adjusted for age and sex, large family size (OR: 2.81; 95% CI: 1.04, 7.61), BCG vaccination scar (OR: 3.10; 95% CI: 1.10, 8.71), and hospitalization during infancy with an infectious disease (OR: 4.67; 95% CI: 1.00, 21.74) were positively associated with DTH to C. albicans.

Conclusions

Early life infections were positively associated with later DTH to C. albicans. This result supports an expansion of the hygiene hypothesis to explain not only pathological immune responses to allergens, but also appropriate immune responses to pathogens. Immune system development may be responsive to early infections as an adaptive means to tailor reactivity to the local infectious disease ecology.

Early daycare attendance increase the risk for respiratory infections and asthma of children

OBJECTIVES

To study the impact of daycare attendance on airways infections and "allergic" symptoms of children aged 1-8 years in Northeast Texas.

METHODS

Self-administrated questionnaires were distributed to parents through Women, Infants and Children offices, daycare centers, elementary schools, clinic centers, hospitals, and churches. The health outcomes consisted of "allergic" symptoms, and respiratory tract disorders. Questions on child care included; type of daycare settings (proxy for the number of children in daycare), time spent at daycare centers per week, and age of entry to a daycare center.

RESULTS

A total of 3766 children participated in this study, giving a response rate of 71%. Daycare attendance was associated with more frequent respiratory tract infections and "allergic" symptoms, compared to home care. A dose-response relationship between time spent at daycare centers and prevalence of respiratory tract disorders and asthma and allergies was observed. Earlier age exposure at daycare centers was a risk factor for rhinitis up to 7-8 years.

CONCLUSIONS

Daycare attendance had a substantial negative influence on health status of children aged 1-8 years in Northeast Texas.

Progress in the field of probiotics: year 2011

PURPOSE OF REVIEW

The interest and scope for research in the field of probiotics has significantly widened in recent years. This brief review covers the significant advances in the field of probiotics.

RECENT FINDINGS

These include conclusive evidence for the benefits of probiotics in preventing all cause mortality and necrotizing enterocolitis (NEC) in preterm very low birth weight (VLBW) neonates, understanding the role of probiotics as vaccine adjuvants, and in modulating inflammatory bowel diseases, bowel cancer, type 1 diabetes mellitus, obesity, high cholesterol levels, and bacterial resistance. Other areas of progress include understanding the role of probiotics in oral health and ageing.

SUMMARY

Current evidence will lead to routine probiotic supplementation to prevent all cause mortality and NEC in preterm VLBW neonates. Probiotics may also become novel agents as vaccine adjuvants, and in dealing with major public health issues such as obesity, type I diabetes mellitus, and poor oral health. Research in applications of probiotics in food products will rationalize product development, and health claims. As new frontiers continue to be explored the challenges to the basis of the hygiene hypothesis will influence further developments in the field of probiotics.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: lifestyle changes affecting the host-environment interface

In industrialized nations and high-income regions of the world, the decline of infectious diseases is paralleled by an increase in allergic, autoimmune and chronic inflammatory diseases (AACID). Changes in lifestyle in westernized societies, which impact individually and collectively on intestinal microbiota, may – at least in part – account for the AACID pandemic. Many disease genes that contribute to AACID encode pattern recognition and signalling molecules in barrier-associated cells. Interactions between gene products and environmental factors depend highly upon the host's state of maturation, the composition of the skin and gut microflora, and exposure to pollutants, antibiotics and nutrients. Inflammatory stress responses, if regulated appropriately, ensure immunity, health and relative longevity; when they are dysregulated, they can no longer be terminated appropriately and thus precipitate AACID. The 99th Dahlem Conference brought together experts of various disciplines (genetics, evolution biology, molecular biology, structural biology, cell biology, immunology, microbiology, nutrition science, epidemiology and clinical medicine) to discuss the multi-faceted relationships between infection, immunity and inflammation in barrier organs and the development of AACID. In Clinical and Experimental Immunology we are presenting a compilation of background papers that formed the basis of discussions. Controversial viewpoints and gaps in current knowledge were examined and new concepts for prevention and treatment of CID were formulated.