Hay fever and asthma in relation to markers of infection in the United States

The effect of single and multiple infections on atopy and wheezing in children

BACKGROUND

The current epidemic of asthma and atopy has been explained by alterations in immune responses related to reduction in childhood infections. However, the findings of epidemiologic studies investigating the association between infection with atopy and asthma have been inconsistent.

OBJECTIVE

We sought to investigate the effect of single or multiple infections (pathogen burden) on atopy and wheeze in urban children from Latin America.

METHODS

Specific IgE against aeroallergens (sIgE) and skin prick test (SPT) reactivity for the most common local allergens were measured in 1128 children aged 4 to 11 years. Data on wheezing and potential confounders were collected by questionnaire. Infections by 8 pathogens were assessed by using serology and stool examination. Associations of wheeze and atopic outcomes with single and multiple infections were analyzed by means of logistic regression.

RESULTS

Negative results for Toxoplasma gondii were associated with a higher prevalence of sIgE (≥0.70 kU/L), whereas negative results for Ascaris lumbricoides, T gondii, herpes simplex virus, and EBV were associated with a higher prevalence of SPT reactivity. Children with 3 or fewer infection markers had a higher prevalence of sIgE and SPT reactivity compared with those with 4 or more infection markers. However, isolated infections or pathogen burden were not associated with the prevalence of atopic or nonatopic wheeze.

CONCLUSION

The findings provide support for the idea that the hygiene hypothesis is operating in an urban Latin American context, but its expression is thus far restricted to the atopic status of patients and not the perceived asthma symptoms.

Potential immunomodulatory effects of latent toxoplasmosis in humans

Background

About 30% of the population worldwide are infected with the protozoan parasite Toxoplasma gondii. Latent toxoplasmosis has many specific behavioral and physiological effects on the human organism. Modified reactivity of the immune system has been suggested to play a key role in many of these effects. For example, the immunosuppression hypothesis explains the higher probability of the birth of male offspring observed in Toxoplasma-positive humans and mice by the protection of the (more immunogenic) male embryos against abortion.

Methods

Here we searched for indices of immunosuppression in Toxoplasma-positive subjects by comparing clinical records of immunology outpatients.

Results

Our cohort study showed that the male patients with latent toxoplasmosis had decreased and the Toxoplasma-positive women had increased leukocyte, NK-cell and monocyte counts in comparison with controls. The B-cell counts were reduced in both Toxoplasma-positive men and women. The difference between Toxoplasma-positive and Toxoplasma-negative subjects diminished with the decline of the specific Toxoplasma antibody titre (a proxy for the length of infection), which is consistent with the observed decreasing strength of the effect of latent toxoplasmosis on human reproduction. The prevalence of toxoplasmosis in 128 male patients was unusually low (10.9%) which contrasted with normal prevalence in 312 female patients (23.7%) and in general population Prague (20-30%).

Conclusions

Latent toxoplasmosis has immunomodulatory effects in human and probably protects men against some classes of immunopathological diseases. The main limitation of the present study was the absence of the data on the immunoreactivity of immune cells subpopulations. Therefore further studies are needed to search for indices of immunosuppression in human using more specific markers.

Changing risk profile of hepatitis A in The Netherlands: a comparison of seroprevalence in 1995-1996 and 2006-2007

The prevalence of antibodies to hepatitis A virus (HAV) was assessed in a nationwide sample (n=6229) in The Netherlands in 2006-2007, and compared to the seroprevalence in a similar study in 1995-1996 (n=7376). The overall seroprevalence increased from 34% in 1995-1996 to 39% in 2006-2007, mainly due to vaccination of travellers and an increased immigrant population. Risk factors remain travelling to, and originating from, endemic regions, and vaccination is targeted currently at these risk groups. Our results show a trend of increasing age of the susceptible population. These people would also benefit from HAV vaccination because they are likely to develop clinically serious symptoms after infection, and are increasingly at risk of exposure through imported viruses through foods or travellers. The cost-effectiveness of adding elderly people born after the Second World War as a target group for prophylactic vaccination to reduce morbidity and mortality after HAV infection should be assessed.

Impact of early life exposures to geohelminth infections on the development of vaccine immunity, allergic sensitization, and allergic inflammatory diseases in children living in tropical Ecuador: the ECUAVIDA birth cohort study

Background

Geohelminth infections are highly prevalent infectious diseases of childhood in many regions of the Tropics, and are associated with significant morbidity especially among pre-school and school-age children. There is growing concern that geohelminth infections, particularly exposures occurring during early life in utero through maternal infections or during infancy, may affect vaccine immunogenicity in populations among whom these infections are endemic. Further, the low prevalence of allergic disease in the rural Tropics has been attributed to the immune modulatory effects of these infections and there is concern that widespread use of anthelmintic treatment in high-risk groups may be associated with an increase in the prevalence of allergic diseases. Because the most widely used vaccines are administered during the first year of life and the antecedents of allergic disease are considered to occur in early childhood, the present study has been designed to investigate the impact of early exposures to geohelminths on the development of protective immunity to vaccines, allergic sensitization, and allergic disease.

Methods/Design

A cohort of 2,403 neonates followed up to 8 years of age. Primary exposures are infections with geohelminth parasites during the last trimester of pregnancy and the first 2 years of life. Primary study outcomes are the development of protective immunity to common childhood vaccines (i.e. rotavirus, Haemophilus influenzae type B, Hepatitis B, tetanus toxoid, and oral poliovirus type 3) during the first 5 years of life, the development of eczema by 3 years of age, the development of allergen skin test reactivity at 5 years of age, and the development of asthma at 5 and 8 years of age. Potential immunological mechanisms by which geohelminth infections may affect the study outcomes will be investigated also.

Discussion

The study will provide information on the potential effects of early exposures to geohelminths (during pregnancy and the first 2 years of life) on the development of vaccine immunity and allergy. The data will inform an ongoing debate of potential effects of geohelminths on child health and will contribute to policy decisions on new interventions designed to improve vaccine immunogenicity and protect against the development of allergic diseases.

Trial registration

Current Controlled Trials ISRCTN41239086.

Chronic virus infections supress atopy but not asthma in a set of children from a large Latin American city: a cross-section study

Background

The prevalence of allergic diseases has increased over recent decades in affluent countries, but remains low in rural populations and some non-affluent countries. An explanation for these trends is that increased exposure to infections may provide protection against the development of allergy. In this work we investigated the association between exposure to viral infections in children living in urban Brazil and the prevalence of atopy and asthma.

Methods

School age children living in poor neighborhoods in the city of Salvador were studied. Data on asthma symptoms and relevant risk factors were obtained by questionnaire. Skin prick tests (SPTs) were performed to seven aeroallergens, and specific IgE was measured to four of these. Viral infections were determined by the presence of specific IgG in serum to Herpes simplex (HSV), Herpes zoster (HZV), Epstein-Barr (EBV), and Hepatitis A (HAV) viruses.

Results

A total of 644 (49.7%) children had at least one allergen-specific IgE> 0.35 kU/L and 489 (37.7%) had specific IgE> 0.70 kU/L. A total of 391 (30.2%) children were skin test positive (SPT+), and 295 (22.8%) children were asthmatic. The seroprevalence of viral infections was 88.9% for EBV, 55.4% for HSV, 45.5% for VZV and 17.5% for HAV. Negative associations were observed between SPT+ and HSV (OR = 0.64, CI = 0.51, 0.82) and EBV (OR = 0.63, CI = 0.44, 0.89) infections, but no associations were seen between viral infections and the presence of allergen-specific IgE or asthma.

Conclusion

These data do not support previous data showing a protective effect of HAV against atopy, but did show inverse associations between SPT+ (but not specific IgE+) and infections with HSV and EBV. These findings suggest that different viral infections may protect against SPT+ in different settings and may indicate an immunoregulatory role of such infections on immediate hypersensitivity responses. The data provide no support for a protective effect of viral infections against asthma in this population.

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

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

A polymorphism in TIM1 is associated with susceptibility to severe hepatitis A virus infection in humans

During infection with the hepatitis A virus (HAV), most patients develop mild or asymptomatic disease. However, a small number of patients develop serious, life-threatening hepatitis. We investigated this variability in disease severity by examining 30 Argentinean patients with HAV-induced acute liver failure in a case-control, cross-sectional, observational study. We found that HAV-induced severe liver disease was associated with a 6-amino-acid insertion in TIM1/HAVCR1 (157insMTTTVP), the gene encoding the HAV receptor. This polymorphism was previously shown to be associated with protection against asthma and allergic diseases and with HIV progression. In binding assays, the TIM-1 protein containing the 157insMTTTVP insertion polymorphism bound HAV more efficiently. When expressed by human natural killer T (NKT) cells, this long form resulted in greater NKT cell cytolytic activity against HAV-infected liver cells, compared with the shorter TIM-1 protein without the polymorphism. To our knowledge, the 157insMTTTVP polymorphism in TIM1 is the first genetic susceptibility factor shown to predispose to HAV-induced acute liver failure. Furthermore, these results suggest that HAV infection has driven the natural selection of shorter forms of the TIM-1 protein, which binds HAV less efficiently, thereby protecting against severe HAV-induced disease, but which may predispose toward inflammation associated with asthma and allergy.

Genetic control of hepatitis A severity and susceptibility to allergy

Hepatitis A virus (HAV) usually results in asymptomatic infection or mild disease, but in a small subset of patients it can lead to severe disease and even liver failure. In this issue of the JCI, Kim et al. identify a polymorphism associated with this increased disease risk in the gene that encodes the HAV receptor--TIM1. Importantly, this TIM1 gene polymorphism protects from the development of atopic diseases in HAV-seropositive individuals.

Influenza infection in suckling mice expands an NKT cell subset that protects against airway hyperreactivity

Infection with influenza A virus represents a major public health threat worldwide, particularly in patients with asthma. However, immunity induced by influenza A virus may have beneficial effects, particularly in young children, that might protect against the later development of asthma, as suggested by the hygiene hypothesis. Herein, we show that infection of suckling mice with influenza A virus protected the mice as adults against allergen-induced airway hyperreactivity (AHR), a cardinal feature of asthma. The protective effect was associated with the preferential expansion of CD4-CD8-, but not CD4+, NKT cells and required T-bet and TLR7. Adoptive transfer of this cell population into allergen-sensitized adult mice suppressed the development of allergen-induced AHR, an effect associated with expansion of the allergen-specific forkhead box p3+ (Foxp3+) Treg cell population. Influenza-induced protection was mimicked by treating suckling mice with a glycolipid derived from Helicobacter pylori (a bacterium associated with protection against asthma) that activated NKT cells in a CD1d-restricted fashion. These findings suggest what we believe to be a novel pathway that can regulate AHR, and a new therapeutic strategy (treatment with glycolipid activators of this NKT cell population) for asthma.

Apoptotic cells activate NKT cells through T cell Ig-like mucin-like-1 resulting in airway hyperreactivity

T cell Ig-like mucin-like-1 (TIM-1) is an important asthma susceptibility gene, but the immunological mechanisms by which TIM-1 functions remain uncertain. TIM-1 is also a receptor for phosphatidylserine (PtdSer), an important marker of cells undergoing programmed cell death, or apoptosis. We now demonstrate that NKT cells constitutively express TIM-1 and become activated by apoptotic cells expressing PtdSer. TIM-1 recognition of PtdSer induced NKT cell activation, proliferation, and cytokine production. Moreover, the induction of apoptosis in airway epithelial cells activated pulmonary NKT cells and unexpectedly resulted in airway hyperreactivity, a cardinal feature of asthma, in an NKT cell-dependent and TIM-1-dependent fashion. These results suggest that TIM-1 serves as a pattern recognition receptor on NKT cells that senses PtdSer on apoptotic cells as a damage-associated molecular pattern. Furthermore, these results provide evidence for a novel innate pathway that results in airway hyperreactivity and may help to explain how TIM-1 and NKT cells regulate asthma.

The effect of Helicobacter pylori on asthma and allergy

Current evidence indicates an inverse association between Helicobacter pylori and asthma and allergy. H. pylori is a Gram-negative bacterium which represents the major cause of peptic ulcer and gastric cancer, and preferentially elicits a T helper (Th)-1 response. Many H. pylori factors, such as the neutrophil-activating factor of H. pylori (HP-NAP), are able to drive Th-1 polarization and to display a powerful inhibition of allergic Th-2 response. This article proposes an overview of the actual knowledge about the effects of H. pylori on asthma and allergy. Special attention has been drawn to HP-NAP as a potential novel strategy for the prevention and treatment of asthma and atopy.

Timing of infection and development of wheeze, eczema, and atopic sensitization during the first 2 yr of life: the KOALA Birth Cohort Study

To investigate if infections in pregnancy and very early in life present a risk for wheezing, eczema, or atopic sensitization in later infancy. A total of 2319 children enrolled before birth in the KOALA Birth Cohort Study were followed during their first 2 yr of life using repeated questionnaires. Information was obtained on common colds, fever, and diarrhea with fever as well as on wheeze and eczema at ages 3 and 7 months and 1 and 2 yr, respectively. Blood samples were collected from 786 children at age 2 yr for specific immunoglobulin E analyses. Children with a common cold [adjusted odds ratio (aOR) 2.03 95% CI 1.21-3.41] or fever episode (aOR 1.81 95% CI 1.10-2.96) in the first 3 months of life had a higher risk of new onset wheeze in the second year of life compared to children who had not. For children with diarrhea with fever in the first 3 months of life, the aOR for new onset wheeze in the second year of life was 3.94 (95% CI 1.36-11.40) compared to children without diarrhea. Infections becoming clinically manifest during the first 3 months of life may be a general marker for a wheezy phenotype.

Diarrhoea in a large prospective cohort of European travellers to resource-limited destinations

BACKGROUND

Incidence rates of travellers' diarrhoea (TD) need to be updated and risk factors are insufficiently known.

METHODS

Between July 2006 and January 2008 adult customers of our Centre for Travel Health travelling to a resource-limited country for the duration of 1 to 8 weeks were invited to participate in a prospective cohort study. They received one questionnaire pre-travel and a second one immediately post-travel. First two-week incidence rates were calculated for TD episodes and a risk assessment was made including demographic and travel-related variables, medical history and behavioural factors.

RESULTS

Among the 3100 persons recruited, 2800 could be investigated, resulting in a participation rate of 89.2%. The first two-weeks incidence for classic TD was 26.2% (95%CI 24.5-27.8). The highest rates were found for Central Africa (29.6%, 95% CI 12.4-46.8), the Indian subcontinent (26.3%, 95%CI 2.3-30.2) and West Africa (21.5%, 95%CI 14.9-28.1). Median TD duration was 2 days (range 1-90). The majority treated TD with loperamide (57.6%), while a small proportion used probiotics (23.0%) and antibiotics (6.8%). Multiple logistic regression analysis on any TD to determine risk factors showed that a resolved diarrhoeal episode experienced in the 4 months pre-travel (OR 2.03, 95%CI 1.59-2.54), antidepressive comedication (OR 2.11, 95%CI 1.17-3.80), allergic asthma (OR 1.67, 95%CI 1.10-2.54), and reporting TD-independent fever (OR 6.56, 95%CI 3.06-14.04) were the most prominent risk factors of TD.

CONCLUSIONS

TD remains a frequent travel disease, but there is a decreasing trend in the incidence rate. Patients with a history of allergic asthma, pre-travel diarrhoea, or of TD-independent fever were more likely to develop TD while abroad.

TIM genes: a family of cell surface phosphatidylserine receptors that regulate innate and adaptive immunity

The TIM (T cell/transmembrane, immunoglobulin, and mucin) gene family plays a critical role in regulating immune responses, including allergy, asthma, transplant tolerance, autoimmunity, and the response to viral infections. The unique structure of TIM immunoglobulin variable region domains allows highly specific recognition of phosphatidylserine (PtdSer), exposed on the surface of apoptotic cells. TIM-1, TIM-3, and TIM-4 all recognize PtdSer but differ in expression, suggesting that they have distinct functions in regulating immune responses. TIM-1, an important susceptibility gene for asthma and allergy, is preferentially expressed on T-helper 2 (Th2) cells and functions as a potent costimulatory molecule for T-cell activation. TIM-3 is preferentially expressed on Th1 and Tc1 cells, and generates an inhibitory signal resulting in apoptosis of Th1 and Tc1 cells. TIM-3 is also expressed on some dendritic cells and can mediate phagocytosis of apoptotic cells and cross-presentation of antigen. In contrast, TIM-4 is exclusively expressed on antigen-presenting cells, where it mediates phagocytosis of apoptotic cells and plays an important role in maintaining tolerance. TIM molecules thus provide a functional repertoire for recognition of apoptotic cells, which determines whether apoptotic cell recognition leads to immune activation or tolerance, depending on the TIM molecule engaged and the cell type on which it is expressed.

TIM genes: a family of cell surface phosphatidylserine receptors that regulate innate and adaptive immunity

The TIM (T cell/transmembrane, immunoglobulin, and mucin) gene family plays a critical role in regulating immune responses, including allergy, asthma, transplant tolerance, autoimmunity, and the response to viral infections. The unique structure of TIM immunoglobulin variable region domains allows highly specific recognition of phosphatidylserine (PtdSer), exposed on the surface of apoptotic cells. TIM-1, TIM-3, and TIM-4 all recognize PtdSer but differ in expression, suggesting that they have distinct functions in regulating immune responses. TIM-1, an important susceptibility gene for asthma and allergy, is preferentially expressed on T-helper 2 (Th2) cells and functions as a potent costimulatory molecule for T-cell activation. TIM-3 is preferentially expressed on Th1 and Tc1 cells, and generates an inhibitory signal resulting in apoptosis of Th1 and Tc1 cells. TIM-3 is also expressed on some dendritic cells and can mediate phagocytosis of apoptotic cells and cross-presentation of antigen. In contrast, TIM-4 is exclusively expressed on antigen-presenting cells, where it mediates phagocytosis of apoptotic cells and plays an important role in maintaining tolerance. TIM molecules thus provide a functional repertoire for recognition of apoptotic cells, which determines whether apoptotic cell recognition leads to immune activation or tolerance, depending on the TIM molecule engaged and the cell type on which it is expressed.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: farm lifestyles and the hygiene hypothesis

About 15 years have gone by since Strachan first proposed the idea that infections and unhygienic contact may confer protection from the development of allergic illnesses. The so-called 'hygiene hypothesis' has since undergone numerous modifications in the field of epidemiology, clinical science and immunology. Three main areas of research have been brought forward: to explore the role of overt viral and bacterial infections for the inception of allergic diseases; to investigate the significance of environmental exposure to microbial compounds on the development of allergies; and to study the effect of both exposures on underlying innate and adaptive immune responses. A concept unifying these various aspects has not been found, but various pieces of a complex interplay between immune responses of the host, characteristics of the invading microorganism, the level and variety of the environmental exposure and the interactions between an exposed subject's genetic background and the environmental exposures becomes apparent. A natural experiment relating to the hygiene hypothesis is the recurrent observation of a protective effect of growing up on a farm for asthma and allergies. This has been shown in a large number of epidemiological studies across the world among children and adults. The timing and duration of exposure are likely to play a critical role. The largest reduction in risk has been demonstrated for those exposed prenatally and continuously thereafter until adulthood. The protective factors in these farming environments have not been unravelled completely. Findings from various studies suggest that the contact with farm animals, at least in childhood, confers protection. Also the consumption of unprocessed cow's milk directly from the farm has been shown to protect from childhood asthma and allergies. Increased levels of microbial substances may, at least in part, contribute to the 'farm effect'. However, only few studies have measured microbial exposures in these environments and the results obtained so far suggest that the underlying protective microbial exposure(s) have not been identified, but a number of studies using metagenomic approaches are currently under way. The mechanisms by which such environmental exposures confer protection from respiratory allergies are also not well understood. There is good evidence for the involvement of innate immune responses, but translation into protective mechanisms for asthma and allergies is lacking. Furthermore, a number of gene x environment interactions have been observed.

Allergic disorders in Africa and africans: is it primarily a priority?

In Africa, the burden of some diseases has been a problem for centuries. The spectrum of African diseases includes allergies, infections, nutritional deficiencies, and natural disasters. Efforts made by scientists to search for possible means of disease control have been outstanding; however, in some infections, solutions are still out of reach. In disease control programs, it might be worthwhile to pay attention to the most striking diseases than merely follow a holistic approach. This short review tackles the problems of allergy and allergens in Africa as compared with other disease burdens that may suggest the need for a more balanced approach based on priority.

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

The 'hygiene hypothesis' proposes that the epidemic of allergic and autoimmune diseases is due to changes in the interactions between humans and the microbes of their ecosystem. This theory apparently does not explain (i) why allergic asthma is rising in 'unhygienic' American inner cities; (ii) why allergic diseases are less prevalent among migrants' children living in European big cities; (iii) why infections with airborne viruses do not 'protect' from allergic sensitization; (iv) why the inverse association between some infections (e.g. hepatitis A virus) and allergic diseases has been reproduced in some populations, but not in others; and (v) why probiotics are not effective in the prevention and therapy of allergic diseases. These challenging questions are useful starting points to improve our understanding of the hypothesis, and to identify among the infectious agents those really responsible for a protective influence against atopic and autoimmune diseases.

Antibody and cytokine responses to house dust mite allergens and Toxoplasma gondii antigens in atopic and non-atopic Brazilian subjects

According to hygiene hypothesis, a lower exposure to infection is associated with increased prevalence of allergic diseases. This study aimed to investigate the association between atopy and Toxoplasma gondii (Tg) infection by analyzing the antibody and cytokine responses to house dust mite allergens and T. gondii antigens in Brazilian subjects. A total of 275 individuals were assessed and divided into atopics (n=129) and non-atopics (n=146) based on markers of allergy (positive skin prick test and ELISA-IgE to mite allergens) or Tg-seropositive (n=116) and Tg-seronegative (n=159) groups according to infection markers (positive ELISA-IgG to T. gondii). Tg-seropositive individuals presented lower allergenic sensitization (37%) to mite allergens than Tg-seronegative subjects (54%). A significant association was found between atopy and negative serology to T. gondii (OR: 2.0; 95% CI: 1.23-3.26; P<0.05). Proliferative responses and cytokine production after antigenic stimulation showed predominant synthesis of Th1-cytokines as IFN-gamma in Tg-seropositive patients, whether atopics or non-atopics. Conversely, Th2-cytokines as IL-5 prevailed in atopics compared to non-atopics, regardless the seropositivity to T. gondii. Levels of IL-10, IL-13, IL-17, and TGF-beta were not able to discriminate the groups. Hence, a negative association between atopy and infection by T. gondii was demonstrated for the first time in Brazilian subjects, focusing on the antibody and cytokine responses and indicating that the immunomodulation induced by the parasite may play a protective role in the development of allergic diseases.

Enteric reovirus infection stimulates peanut-specific IgG2a responses in a mouse food allergy model

IgE-mediated food allergies are an important cause of life-threatening hypersensitivity reactions. Orally administered peanut antigens mixed with the mucosal adjuvant cholera toxin (CT) induce a strong peanut extract (PE)-specific serum IgE response that is correlated with T-helper type 1 (Th1) and type 2 (Th2)-like T-cell responses. This study was conducted to determine if respiratory enteric orphan virus (reovirus), a non-pathogenic virus that induces robust Th1-mediated mucosal and systemic responses could modulate induction of PE-specific allergic responses when co-administered with PE. Young mice were orally exposed to PE mixed with CT, reovirus, or both CT and reovirus. As expected, CT promoted PE-specific serum IgE, IgG1, and IgG2a and intestinal IgA production as well as splenic Th1- and Th2-associated cytokine recall responses. Reovirus did not alter PE-specific serum IgE and IgG1 levels, but substantially increased the PE-specific IgG2a response when co-administered with PE with or without CT. Additionally, reovirus significantly decreased the percentage of the Peyer's patch CD8+ T-cells and Foxp3+CD4+ T-regulatory cells when co-administered with PE. These results demonstrate that an acute mucosal reovirus infection and subsequent Th1 immune response is capable of modulating the Th1/Th2 controlled humoral response to PE. The reovirus-mediated increase in the PE-specific IgG2a antibody response may have therapeutic implications as increased levels of non-allergenic PE-specific IgG2a could block PE antigens from binding to IgE-sensitized mast cells.

Evaluation, diagnosis, and treatment of gastrointestinal disorders in individuals with ASDs: a consensus report

Autism spectrum disorders (ASDs) are common and clinically heterogeneous neurodevelopmental disorders. Gastrointestinal disorders and associated symptoms are commonly reported in individuals with ASDs, but key issues such as the prevalence and best treatment of these conditions are incompletely understood. A central difficulty in recognizing and characterizing gastrointestinal dysfunction with ASDs is the communication difficulties experienced by many affected individuals. A multidisciplinary panel reviewed the medical literature with the aim of generating evidence-based recommendations for diagnostic evaluation and management of gastrointestinal problems in this patient population. The panel concluded that evidence-based recommendations are not yet available. The consensus expert opinion of the panel was that individuals with ASDs deserve the same thoroughness and standard of care in the diagnostic workup and treatment of gastrointestinal concerns as should occur for patients without ASDs. Care providers should be aware that problem behavior in patients with ASDs may be the primary or sole symptom of the underlying medical condition, including some gastrointestinal disorders. For these patients, integration of behavioral and medical care may be most beneficial. Priorities for future research are identified to advance our understanding and management of gastrointestinal disorders in persons with ASDs.

The interaction of hepatitis A virus (HAV) with soluble forms of its cellular receptor 1 (HAVCR1) share the physiological requirements of infectivity in cell culture

Background

Hepatitis A virus (HAV), an atypical Picornaviridae that causes acute hepatitis in humans, usurps the HAV cellular receptor 1 (HAVCR1) to infect cells. HAVCR1 is a class 1 integral membrane glycoprotein that contains two extracellular domains: a virus-binding immunoglobulin-like (IgV) domain and a mucin-like domain that extends the IgV from the cell membrane. Soluble forms of HAVCR1 bind, alter, and neutralize cell culture-adapted HAV, which is attenuated for humans. However, the requirements of the HAV-HAVCR1 interaction have not been fully characterized, and it has not been determined whether HAVCR1 also serves as a receptor for wild-type (wt) HAV. Here, we used HAV soluble receptor neutralization and alteration assays to study the requirements of the HAV-HAVCR1 interaction and to determine whether HAVCR1 is also a receptor for wt HAV.

Results

Treatment of HAV with a soluble form of HAVCR1 that contained the IgV and two-thirds of the mucin domain fused to the Fc fragment of human IgG1 (D1 muc-Fc), altered particles at 37°C but left a residual level of unaltered particles at 4°C. The kinetics of neutralization of HAV by D1 muc-Fc was faster at 37°C than at 4°C. Alteration of HAV particles by D1 muc-Fc required Ca, which could not be replaced by Li, Na, Mg, Mn, or Zn. Neutralization of HAV by D1 muc-Fc occurred at pH 5 to 8 but was more efficient at pH 6 to 7. D1 muc-Fc neutralized wt HAV as determined by a cell culture system that allows the growth of wt HAV.

Conclusion

The interaction of HAV with soluble forms of HAVCR1 shares the temperature, Ca, and pH requirements for infectivity in cell culture and therefore mimics the cell entry process of HAV. Since soluble forms of HAVCR1 also neutralized wt HAV, this receptor may play a significant role in pathogenesis of HAV.

Virus vaccines and children with asthma

PURPOSE OF REVIEW

To describe what is currently known about the role of virus vaccines in the pathogenesis of asthma and atopy and summarize their role in the prevention of morbidity due to childhood asthma.

RECENT FINDINGS

The development of virus vaccines and their incorporation into infant and childhood immunization programmes over the last few decades of the twentieth century have been accompanied by a striking concomitant rise in the incidence of asthma and atopy. However, a causal relationship is not supported by the majority of observational studies. The role of childhood immunization against respiratory viruses in the reduction of morbidity from asthma is another important public health issue. Recent findings suggest that influenza is not strongly associated with exacerbations of asthma in children, despite recommendations that this group should be immunized against it.

SUMMARY

Current evidence suggests that virus vaccination is well tolerated and does not lead to an increased incidence of asthma or atopy in children receiving vaccines. Debate continues regarding the place of respiratory virus vaccination in the therapeutic armamentarium for children with asthma. In the case of influenza, there appears to be an absence of harm, but benefit seems to be limited to younger children.

Review series on helminths, immune modulation and the hygiene hypothesis: the broader implications of the hygiene hypothesis

Man has moved rapidly from the hunter-gatherer environment to the living conditions of the rich industrialized countries. The hygiene hypothesis suggests that the resulting changed and reduced pattern of exposure to microorganisms has led to disordered regulation of the immune system, and hence to increases in certain inflammatory disorders. The concept began with the allergic disorders, but there are now good reasons for extending it to autoimmunity, inflammatory bowel disease, neuroinflammatory disorders, atherosclerosis, depression associated with raised inflammatory cytokines, and some cancers. This review discusses these possibilities in the context of Darwinian medicine, which uses knowledge of evolution to cast light on human diseases. The Darwinian approach enables one to correctly identify some of the organisms that are important for the 'Hygiene' or 'Old Friends' hypothesis, and to point to the potential exploitation of these organisms or their components in novel types of prophylaxis with applications in several branches of medicine.

Asthma is inversely associated with Helicobacter pylori status in an urban population

Background

Microbial exposures have been suggested to confer protection from allergic disorders and reduced exposures to gastrointestinal microbiota have been proposed as an explanation for the increase in asthma prevalence. Since the general prevalence of Helicobacter pylori has been decreasing, we hypothesized that H. pylori serostatus would be inversely related to the presence of asthma.

Methods

Adults were recruited to participate in the New York University (NYU)/Bellevue Asthma Registry in New York City. Adult asthma cases (N = 318) and controls (N = 208) were identified and serum IgG antibodies to H. pylori whole cell antigens or the immunodominant CagA antigen were measured.

Results

As expected, the asthma cases and controls differed with respect to atopy and lung function. Seropositivity to H. pylori or CagA antigen was present in 47.1% of the total case and control study population. Asthma was inversely associated with CagA seropositivity (OR = 0.57, 95% CI = 0.36–0.89). Median age of onset of asthma (doctor's diagnosis) was older (21 years) among individuals with CagA+ strains than among H. pylori- individuals (11 years) (p = 0.006).

Conclusion

These data are consistent with the hypothesis that colonization with CagA+ H. pylori strains is inversely associated with asthma and is associated with an older age of asthma onset in an urban population. The data suggest H. pylori as a marker for protection.

Trial Registration

ClinicalTrials.gov NCT00212537

Specific IgE to allergens in cord blood is associated with maternal immunity to Toxoplasma gondii and rubella virus

BACKGROUND

Various studies have found reduced prevalences of atopic sensitization and atopic diseases in children previously exposed to infections or living conditions with a high microbial burden, such as the farming environment.

OBJECTIVE

We sought to determine the relationships of cord blood immunoglobulin E (IgE) with maternal health conditions before and during pregnancy.

METHODS

Pregnant women living in rural areas in five European countries were recruited in the third trimester of pregnancy. Information on maternal health during pregnancy was collected from maternity records and by questionnaires (n = 497). Specific IgE for inhalant and food allergens was assessed in cord blood and peripheral blood samples of the mothers.

RESULTS

Inverse associations of cord blood IgE to seasonal allergens with positive maternal records for Toxoplasma gondii (adjusted odds ratio = 0.37 [0.17-0.81]) and rubella virus (adjusted odds ratio = 0.35 [0.13-0.96]) were found. The previously described effect of prenatal farm exposure on IgE to seasonal allergens was partly confounded by a positive maternal record for T. gondii. The number of maternal siblings, maternal contact to cats during pregnancy or during her first year of life, predicted a positive maternal record for T. gondii.

CONCLUSIONS

Maternal immunity to T. gondii and rubella may impact on atopic sensitization in the fetus. A positive T. gondii record explained the previously identified effect of prenatal farm exposure on IgE to seasonal allergens only to a minor extent.

Endotoxin levels in cow's milk samples from farming and non-farming families - the PASTURE study

BACKGROUND

Children from farming families have less allergies than their peers. Consumption of farm milk or unpasteurized milk has been shown to explain (part of) the farming effect or protect against allergies independent of farming status.

OBJECTIVES

We investigated whether the protective effect of farm milk consumption can be explained by higher levels of bacterial endotoxin in milk.

METHODS

We measured endotoxin in approximately 400 farm milk and shop milk samples from farming and non-farming families, respectively, with the kinetic chromogenic Limulus Amebocyte Lysate test and compared endotoxin levels between groups defined by farming status and type of milk (farm milk/shop milk).

RESULTS

Endotoxin levels were significantly higher in milk samples from non-farming families compared to farming families [adjusted geometric means ratio (95% confidence interval)=2.61 (1.53-4.43)]. No significant difference in endotoxin levels was found between shop milk and farm milk samples [adjusted geometric means ratio (95% confidence interval)=1.56 (0.94-2.58)]. The difference between farming and non-farming families could be explained completely for farm milk and partially for shop milk by storage conditions and temperature during transportation to the fieldworker's home.

CONCLUSION

The farming effect and the effect of farm milk consumption cannot be explained by higher levels of endotoxin in milk from farmers and farm milk, respectively.

Epidemiology of Helicobacter pylori infection

This review summarizes studies on the epidemiology of Helicobacter pylori published in peer-reviewed journals between April 2007 and March 2008. Infection with H. pylori often occurs in childhood, and once established, can persist lifelong if untreated. Prevalence of H. pylori infection is higher in developing countries when compared to developed countries, and can vary by ethnicity, place of birth, and socioeconomic factors even among persons living in the same country. Prevalence of infection is decreasing in many countries due to improvements in sanitation and living standards and the relatively recent movement of populations from rural to urban settings; however, post-treatment recurrence rates of H. pylori infection remain high in developing countries, and in given populations within developed countries. In addition, a number of recent studies have begun to explore the possible link between childhood infection with H. pylori and protection against asthma and allergy.

TIM gene family and their role in atopic diseases

The TIM gene family was discovered seven years ago by positional cloning in a mouse model of asthma and allergy. Three of the family members (TIM-1, TIM-3, and TIM-4) are conserved between mouse and man, and have been shown to critically regulate adaptive immunity. In addition, TIM-1 has been shown to play a major role as a human susceptibility gene for asthma, allergy and autoimmunity. Recently, TIM-4 has been identified as a ligand of phosphatidylserine and to control the uptake of apoptotic cells. These studies together suggest that the TIM gene family evolved to regulate immune responses by managing survival and cell death of hematopoetic cells.

Helicobacter pylori colonization is inversely associated with childhood asthma

BACKGROUND

Asthma, a serious health problem worldwide, is becoming more common. Colonization with Helicobacter pylori, a major human indigenous (commensal) microbe, during early life may be relevant to the risk of childhood asthma.

METHODS

We conducted cross-sectional analyses, using data from 7412 participants in the National Health and Nutrition Examination Survey (NHANES) 1999-2000, to assess the association between H. pylori and childhood asthma.

RESULTS

H. pylori seropositivity was inversely associated with onset of asthma before 5 years of age and current asthma in children aged 3-13 years. Among participants 3-19 years of age, the presence of H. pylori was inversely related to ever having had asthma (odds ratio [OR], 0.69; 95% confidence interval [CI], 0.45-1.06), and the inverse association with onset of asthma before 5 years of age was stronger (OR, 0.58; 95% CI, 0.38-0.88). Among participants 3-13 years of age, H. pylori positivity was significantly inversely associated with current asthma (OR, 0.41; 95% CI, 0.24-0.69). H. pylori seropositivity also was inversely related to recent wheezing, allergic rhinitis, and dermatitis, eczema, or rash.

CONCLUSIONS

This study is the first to report an inverse association between H. pylori seropositivity and asthma in children. The findings indicate new directions for research and asthma prevention.

Helicobacter pylori infection and allergic diseases: epidemiological study in Japanese university students

BACKGROUND AND AIM

A negative association between Helicobacter pylori infection and allergic diseases has not been consistent. The aim of this study was to examine the association between allergic diseases and H. pylori infection in Japan.

METHODS

Newly enrolled university students completed health survey questionnaires regarding general health and the presence of allergic diseases. Helicobacter pylori status was determined by the presence of serum H. pylori IgG and the presence of allergic manifestations was confirmed by interview.

RESULTS

A total of 1953 students had a routine health survey; H. pylori status was determined in 777 including 369 with allergic diseases and 408 controls. The reported frequency of allergic rhinoconjunctivitis, atopic dermatitis, urticaria, bronchial asthma and mixed diseases was 29.0%, 11.1%, 2.0%, 0.9% and 5.0%, respectively. Helicobacter pylori infection was diagnosed less frequently in the allergic group compared with controls (11.4% vs 17.6%, P = 0.015). Helicobacter pylori infection was less frequent in men with allergic diseases (OR 0.49, 95% CI 0.27-0.89).

CONCLUSION

Allergic diseases are frequent in young Japanese adults and are negatively associated with H. pylori infection especially in men.

Infections presenting for clinical care in early life and later risk of hay fever in two UK birth cohorts

BACKGROUND

The 'hygiene hypothesis' proposes that infections in infancy protect against hay fever (HF). We investigated infections during infancy in relation to HF, including rarer ones not previously researched in this context, while examining the role of potential confounding variables.

METHODS

From birth cohorts derived within the General Practice Research Database (GPRD) and Doctors Independent Network (DIN) database of computerized patient records from UK general practice, we selected 3549 case-control pairs, matched for practice, age, sex and control follow-up to case diagnosis. Conditional logistic regressions were fitted for each of 30 infections; behavioural problems (BP) acted as a control condition unrelated to HF. Odds ratios (OR), adjusted for consultation frequency were pooled across the databases using fixed effect models. We also adjusted for sibship size in GPRD and a socioeconomic marker in DIN.

RESULTS

Upper respiratory tract infections, diarrhoea and vomiting and acute otitis media in infancy were each related with a moderately increased risk of HF in both databases, as were BP. These associations were lost on adjustment for consultation frequency. Only bronchiolitis was significantly associated with a reduced pooled risk of HF after adjustment for consultations (OR = 0.8). Adjustment for sibship size in GPRD and a socioeconomic marker in DIN had little impact on the OR.

CONCLUSIONS

Of 30 infectious illnesses investigated, none had strong or consistent associations with HF after adjustment for consultation frequency. Except for bronchiolitis, possibly a chance finding, none of the clinically apparent infections considered appear to have an important role in allergy prevention.

Common characteristics of upper and lower airways in rhinitis and asthma: ARIA update, in collaboration with GA(2)LEN

This update aimed to review the new evidence available to support or refute prior Allergic Rhinitis and its Impact on Asthma (ARIA) statements. A Medline search of publications between 2000 and 2005 was conducted, with articles selected by experts. New evidence supports previous ARIA statements, such as: (i) allergic rhinitis (AR) is a risk factor for asthma; (ii) patients with persistent rhinitis should be evaluated for asthma; (iii) most patients with asthma have rhinitis; (iv) a combined strategy should be used to treat the airways and (v) in low- to middle-income countries, a different strategy may be needed. The increased risk of asthma has also been found among sufferers from non-AR. Recent reports show AR is a global problem. Many studies demonstrated parallel increasing prevalence of asthma and rhinitis, but in regions of highest prevalence, it may be reaching a plateau. Factors associated with a reduced risk of asthma and AR have been identified, confirming previous findings of protection related to exposure to infections. Treatment of rhinitis with intranasal glucocorticosteroids, antihistamines, leukotriene antagonists or immunotherapy may reduce morbidity because of asthma. To take advantage of the paradigm of unified airways, there is a need to rationalize diagnosis and treatment to optimize management.

The role of the T-cell costimulatory molecule Tim-1 in the immune response

Upon encountering antigen, CD4+ T-cells become activated and can differentiate into subsets with distinct functional characteristics. One of these subsets is the Th2 cell, which generates large amounts of interleukin (IL)-4, -5, -10 and -13 in response to a subsequent encounter with antigen. In the context of a protective immune response, Th2 cells promote immune cell activation, antibody production, and inflammatory responses that help clear infections. However, aberrant responses by Th2 cells can lead to debilitating allergic diseases such as asthma. Thus, a reasonable approach toward gaining novel insights into immunity and allergic disease is to define the mechanisms that control Th2 cell differentiation and mature Th2 cell function. Recent work suggests that a protein called Tim-1 (T-cell immunoglobulin and mucin protein-1) is expressed on CD4+ T-cells and plays a central role in regulating Th2 responses. Genetic analysis has linked polymorphisms in the human TIM1 gene to susceptibility to allergic disease, while studies involving mice have shown that ligation of Tim-1 promotes CD4+ T-cell activation. The signal transduction pathways downstream of Tim-1 are a relatively unexplored area. Continued study will undoubtedly reveal novel insights regarding the relationships between Tim-1, Th2 responses, and allergic disease.

Diagnosis and treatment of asthma in childhood: a PRACTALL consensus report

Asthma is the leading chronic disease among children in most industrialized countries. However, the evidence base on specific aspects of pediatric asthma, including therapeutic strategies, is limited and no recent international guidelines have focused exclusively on pediatric asthma. As a result, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology nominated expert teams to find a consensus to serve as a guideline for clinical practice in Europe as well as in North America. This consensus report recommends strategies that include pharmacological treatment, allergen and trigger avoidance and asthma education. The report is part of the PRACTALL initiative, which is endorsed by both academies.

The genetic and environmental basis of atopic diseases

The prevalence of atopic diseases has increased abruptly in recent years in most Westernized societies, making the question why this happened the topic of a heated debate. The best paradigm available to date to explain this steep rise, the 'hygiene hypothesis', supports that it is the excess 'cleanliness' of our environments that has led to the decline in the number of infectious stimuli that are necessary for the proper development of our immune system. Recent findings support that it is the combined effect that not only pathogenic, but also non-pathogenic microorganisms, and even their structural components,can exert on the immune system that deters from the development of atopic responses. Adding to these results are intriguing new findings on the effect different gene polymorphisms can have on an individual's predisposition to allergic diseases. The most important linkages produced, to date, include those among the genes for IL-4, IL-13, HLA-DRB, TNF, LTA,FCER1B, IL-4RA, ADAM33, TCR alpha/delta, PHF11, GPRA, TIM, p40, CD14, DPP10, T-bet, GATA-3, and FOXP3 and allergic disorders. The two parallel research efforts, epidemiologic and genetic, are only recently starting to converge,producing fascinating results on the effect particular gene-environment interactions might have in the development of atopy.The most important lesson learned through this tremendous research effort is that not only a small number but thousands and millions of separate risk factors act in concordance in the production of the allergic phenotype.

Expression of T-cell immunoglobulin- and mucin-domain-containing molecule-1 (TIM-1) is increased in a mouse model of asthma and relationship to GATA-3

It has been suggested that T-cell immunoglobulin-and mucin-domain-containing molecule-1 (TIM-1) plays an important role in the development of allergic asthma, though its molecular mechanism remains unclear. Our aim was to examine the expression of TIM-1 and Th2-associated transcription factor GATA-3 in asthmatic mice, and to evaluate the correlation of TIM-1 and GATA-3 in the pathogenesis of allergic asthma. We examined TIM-1 expression in lung tissue and peripheral blood mononuclear cells (PBMCs) of asthmatic mice by real-time PCR and flow cytometry, respectively; we also investigated TIM-1 and GATA-3 expression in the spleen tissue of asthmatic mice by western blot. These results demonstrate that TIM-1 was significantly increased in pulmonary tissues and PBMCs in asthmatic mice after ovalbumin (OVA) challenge (P<0.05), and that the production of TIM-1 as well as GATA-3 was upregulated in the spleen of asthmatic mice. The production of TIM-1 correlated significantly with the production of GATA-3 in the spleen of asthmatic mice (r=0.753, P<0.05). The results of this study provide the first evidence that increased expression of TIM-1 in asthmatic mice is associated with the Th2-associated transcription factor GATA-3. The findings suggest a possible mechanism for how HAV infection and TIM-1 upregulation influence the development of allergic asthma.

Primary prevention of allergy: avoiding risk or providing protection?

Primary prevention strategies of allergy so far have been aimed to fight allergy causes, by avoiding risk factors and inhibiting their mechanisms of action. The results of trials testing food or airborne allergen avoidance as a prevention strategy were, however, rather disappointing. A reverse approach for primary prevention of allergies aims to facilitate exposure to protecting factors which promote the induction of immunologic tolerance against innocuous antigens. These factors are associated with farming environment and a 'traditional lifestyle', but identification of these factors is quite difficult. Major candidates include food-borne microbes, helminths or their components, which are able to stimulate mucosal immunity, particularly in the gut. Similarly, new preventive and therapeutic strategies are being tested to induce specific food-allergen oral tolerance through the ingestion of progressively increasing doses of the offending food. This shifting of allergy prevention research from avoidance to tolerance induction will hopefully allow us to reverse the epidemic trend of allergy diseases.

Environmental factors and allergic disorders

Despite numerous studies on possible associations between environmental exposure and allergic disorders, any conclusions made remain a matter of controversy. We conducted a review of evidence in relation to environmental and nutritional determinants and wheeze, asthma, atopic dermatitis, and allergic rhinitis. Identified were 263 articles for analysis after consideration of 1093 papers that were published since 2000 and selected by electronic search of the PubMed database using keywords relevant to epidemiological studies. Most were cross-sectional and case-control studies. Several prospective cohort studies revealed inconsistent associations between various environmental factors and the risk of any allergic disorder. Therefore, the evidence was inadequate to infer the presence or absence of a causal relationship between various environmental exposures and allergic diseases. However, evidence is suggestive of positive associations of allergies with heredity. Because almost all the studies were performed in Western countries, the application of these findings to people in other countries, including Japan, may not be appropriate. Further epidemiological information gained from population-based prospective cohort studies, in particular among Japanese together with other Asians, is needed to assess causal relationships between various environmental factors and allergic diseases.