The inverse association between tuberculin responses and atopic disorder

Therapeutic effects of inhaled inactivated Mycobacterium phlei in adult patients with moderate persistent asthma

BCG and other mycobacterial infections suppress airway hyper-responsiveness and inflammation in asthma models; however, its efficacy in human populations remains controversial. We use inactivated Mycobacterium phlei by way of atomizing inhalation to investigate whether it would protect against asthma in adult patients. Patients with newly diagnosed, uncontrolled, moderate persistent bronchial asthma were randomly divided into two groups. The patients in group A were treated with a solution of inhaled inactivated-M. phlei. Group B were treated with salmeterol xinafoate and fluticasone propionate powder. The Spirometry and Bronchial Provocation Test and Asthma Control Test were carried out; the peak expiratory flow and forced expiratory volume in 1 s-PD20 of the patients in the two groups increased significantly. However, overall, there was no significant difference between the two groups. Asthma Control Test scores of the patients in the two groups were significantly increased. We concluded that inhaled inactivated M. phlei, to a certain extent, improves asthma symptoms, reduces the need for rescue medication and reduces acute exacerbation of asthma. It plays the same role as inhaled Seretide treatment in reducing airway hyper-responsiveness.

Human immune responses to vaccines in the first year of life: biological, socio-economic and ethical issues - a viewpoint

Human newborns are vulnerable to infectious diseases that account for majority of the morbidity and mortality, particularly in first year of life. Vaccines have become the most effective public health intervention strategy to curtail the prevalence of these infectious diseases. Although vaccines against a number of diseases exist, there are no vaccines against many other diseases that commonly affect children. The adequate assessment of immune responses to vaccines is an important step in the development of vaccines. However, a number of biological and "non-medical" socio-economic and ethical factors could influence either the administration and/or evaluation of vaccines in infants. Recognition and understanding of these determinants are crucial in planning interventions and for logical interpretations of results.

Prevalence of asthma and atopy in sarcoidosis

BACKGROUND AND OBJECTIVE

We hypothesized that the prevalence of allergic disorders, characterized by the release of type 2 cytokines (IL-4, IL-5, IL-10), would be lower in sarcoidosis in which there is a dominant type 1 immune response (IL-2, interferon-gamma). The objective was to measure the prevalence of atopy and self-reported asthma in patients with sarcoidosis.

METHODS

Sarcoidosis patients (n = 136, 72 M, age range 22-75), recruited in the outpatient setting, completed a modified European Community Respiratory Health Survey. 123 of these patients provided blood for allergy testing.

RESULTS

For the cohort as a whole the self-reported prevalence of asthma ever (21.5%) and asthma attack in the last 12 months (7.5%), was high as was wheezing (42.1%), breathlessness with wheeze (22.3%) and use of an asthma medication (13.1%). The prevalence of atopy was 34%. These data are not different from the previously reported prevalence of asthma and atopy in New Zealand.

CONCLUSIONS

The same prevalence of asthma symptoms and atopy as in the normal population suggests that the immune system is not skewed away from mounting T helper type 2 immune responses in sarcoidosis.

Tuberculosis, bacillus Calmette-Guérin vaccination, and allergic disease: findings from the International Study of Asthma and Allergies in Childhood Phase Two

Some have suggested a protective effect of tuberculosis (TB) infection on allergic disease risk, but few studies have examined the association between the two. We therefore investigated whether TB disease and bacillus Calmette-Guérin (BCG) vaccination in early life protect against allergic disease. Information on allergic disease symptoms, past TB disease, and BCG vaccination as well as potential confounding factors was gathered by parental questionnaire from a randomly selected subset of 23,901 8- to 12-yr-old schoolchildren in 20 centers in both developed and developing countries. Children were also physically examined for flexural eczema and underwent skin prick testing. Pooled odds ratio (OR) estimates and corresponding 95% confidence intervals (CIs) across study centers were calculated, using random effects meta-analysis models. There were 245 (1.0%) reported cases of TB disease, and 66.3% (15,857) of all children received the BCG vaccine. Asthma, hay fever, and flexural eczema symptoms in the past year as well as flexural eczema on skin examination were all positively linked to a history of TB (adjusted pooled OR 'wheeze in the past year' = 2.27, 95% CI 1.52-3.41; adjusted pooled OR 'hay fever symptoms in the past year' = 2.23, 1.22-4.09; adjusted pooled OR 'flexural eczema symptoms in the past year' = 3.21, 2.01-5.12; adjusted pooled OR 'flexural eczema on skin examination' = 4.04, 1.71-9.56). Even higher risk estimates were seen for severe asthma and eczema symptoms [adjusted OR = 4.02 (2.17-7.47) and adjusted OR = 6.31 (2.19-18.17), respectively]. There was no significant association between past TB and skin prick test positivity (adjusted pooled OR = 1.32, 0.87-2.02). BCG vaccination during the first year of life was also not associated with any of the allergy outcomes. We found a uniform positive association between TB and all allergic disease outcomes, including eczema on skin examination. As this was a cross-sectional study, it is unclear whether this positive association is attributable to a causal relationship, and further longitudinal studies are required.

Impact of helminth infection on childhood allergic diseases in an area in transition from high to low infection burden

Background

The effect of helminth infections on allergic diseases is still inconclusive. Furthermore, the effect of helminth infections on childhood allergic diseases in a tropical area where prevalence of helminth infections has undergone dramatic changes is not well documented.

Objective

To investigate the relationship between allergic diseases and helminth infection in a cohort of schoolchildren in an area that has undergone dramatic changes in intensity of helminth infections.

Methods

Children attending grade 5 were recruited from 17 schools in Western Province of Sri Lanka. They were assessed for allergic diseases using the International Study of Asthma and Allergies in Childhood questionnaire. Their serum total IgE (tIgE) and allergen-specific IgE (sIgE) for five common aeroallergens were measured by ImmunoCAP® method and stools were examined for the presence of helminth infections.

Results

A total of 640 children (mean age 10 years) were recruited to the study. Of them, 33.7% had evidence of allergic disease and 15.5% had helminth infections. Majority of infections (68.9%) were of low intensity. A significant relationship between allergic disease and helminth infections was not observed, however, a trend toward protective role of helminth infections against allergic diseases was noted. Multivariate analysis showed helminth infections to be an independent predictor of high tIgE levels whereas allergic disease was not. Allergic sensitization (atopy) was a significant risk factor for allergic disease only among non-infected children (odds ratio 3.025, p = 0.022) but not in infected children. The ratio of sIgE to tIgE was higher in non-infected children.

Conclusion

Though not significant, a reduced risk of allergy in helminth-infected children was observed in this population. A Decrease in intensity of helminth infections may have contributed to the reduced capacity of immune-modulation by helminths in this paediatric population.

Heat-killed bacillus Calmette-Guérin and Mycobacterium kansasii antigen 85B combined vaccination ameliorates dermatitis in a mouse model of atopic dermatitis by inducing regulatory T cells

BACKGROUND

Atopic dermatitis (AD) is a recurrent inflammatory skin disease characterized by dominant T-helper (Th) 2 cytokine response. Bacillus Calmette-Guérin (BCG) has been used for preventing tuberculosis, and is regarded as a strong Th1 cytokine inducer. Antigen (Ag) 85B is a secretory protein present in Mycobacterium species that induces Th1 cytokine production.

OBJECTIVES

We investigated the effects of combined vaccination of heat-killed BCG (hkBCG) and Mycobacterium kansasii Ag85B in an AD mouse model.

METHODS

For the AD model, keratin 14 promoter-derived caspase-1 overexpressing mice (KCASP1Tg) were used. The mice received a combination therapy of hkBCG at age 3 weeks and Ag85B twice weekly for 11 weeks from the 4th week; Ag85B monotherapy from the 4th week; hkBCG monotherapy at the 3rd week; or control saline. Areas of skin lesions, cytokine mRNA expression and serum interleukin (IL)-18 and immunoglobulin (Ig) E levels were analysed. Inducible Foxp3+  regulatory T cells (iTreg), IL-10-producing T cells (Tr1), and interferon (IFN)-γ/IL-4/IL-17-producing T cells were evaluated in the spleen.

RESULTS

Saline-treated mice and hkBCG monotherapy mice spontaneously developed severe dermatitis. However, combined therapy with hkBCG and Ag85B significantly suppressed the development of skin lesions and mast cell infiltrations. Elevations of the serum IgE and IL-18 levels were significantly suppressed with combined therapy. Mice treated with hkBCG and Ag85B had a normal number of iTreg in the spleen, and decreased number of both IL-4- and IL-17-producing CD4+ T cells. The effect of Ag85B monotherapy was limited.

CONCLUSIONS

Combined vaccination with hkBCG and Ag85B decreases AD skin lesions by inducing regulatory T cells, suggesting that this vaccination is a potent and novel therapeutic strategy for AD.

Atopy is a risk factor for adult asthma in urban community of Southwestern Nigeria

RATIONALE

Factors affecting asthma course are not clearly elucidated in urban communities in developing countries. Furthermore, the interaction between factors such as atopy, environmental exposure, urbanization, and helminthic infections in modulating asthma have not been well investigated.

OBJECTIVES

To determine factors, which affect asthma in adults being evaluated at urban tertiary health center of Southwestern part of Nigeria.

MATERIALS AND METHODS

A random sample of 24 (12 males, 12 females) consecutive asthmatics seen in the Outpatient Pulmonary Clinic of University College Hospital of Ibadan and 27 (13 males, 14 females) age and gender-matched controls underwent evaluation, which included blood tests for eosinophils, serum IgE, allergy skin tests to eight common environmental allergens, and spirometry. The modified version of the questionnaire of the International study of Asthma and Allergies in Children (ISAAC) Phase III used by the same study group of researchers in Nigeria was used to assess the asthma symptoms. Wilcoxon sign-rank tests were used to compare eosinophil counts, percentage eosinophils, and allergic skin test between the two groups, while paired t test was used to compare spirometry variables.

RESULTS

Asthmatics had significantly more positive skin reaction to house dust mite and mould than controls (P<0.05). Total serum IgE was also significantly higher in asthmatics than in controls (mean 210 vs 60 IU/mL; P=0.003). However, no significant differences were observed in total eosinophil counts. No significant difference in the degree of intestinal helminthes infection in the two groups, which means stool parasitism was similar. FEV(1) % was significantly lower in asthmatics (P=0.02) but FEV(1) was similar between the two groups (P=0.02).

CONCLUSION

The elevated levels of IgE and positive skin reactions to some of the common environmental allergens suggests an important role of atopy in the expression of asthma in this developing country's urban setting. Intestinal parasites were seen in both, control and asthma subjects, but appear not to play any role in the course of asthma, so also is the blood group, genotype and G6PD status.

The hygiene hypothesis revisited: does exposure to infectious agents protect us from allergy?

PURPOSE OF REVIEW

The increase in incidence and prevalence of allergic disease remains a mystery and cannot be explained solely by genetic factors. The hygiene hypothesis provides the strongest epidemiological explanation for the rise in allergic disease. This review evaluates the recent epidemiological and mechanistic research in the role of infectious agents in the pathogenesis of or protection from allergic disease.

RECENT FINDINGS

Recent literature has extended the epidemiological findings of the protective effect of being born and reared in a farm environment and associates an increased diversity of organisms in house-dust samples with protection from allergic disease. Furthermore, human and animal studies provide increasing evidence for the role of both the innate and adaptive immune systems, including regulatory cells, as mediators of this protective effect.

SUMMARY

There is evidence that exposure to some infectious organisms can protect from atopy, whereas other infections appear to promote allergic diseases. The timing of exposure to infection and the properties of the infectious agent, in addition to the genetic susceptibility of the host, play an important role in the future development of allergic disease.

The burden of allergic rhinitis and asthma

Asthma and allergic rhinitis are common health problems that cause major illness and disability worldwide. The prevalence of allergic rhinitis is estimated to range from 10% to 20% in the USA and Europe. Multiple factors contribute to the wide range of reported prevalence rates. These include type of prevalence rate reported (current or cumulative), study selection criteria, age of participants, differences in survey methods, varied geographic locations and socioeconomic status, any of which are significant enough to confound direct comparison between studies. There is no standard set of diagnostic criteria for allergic rhinitis. In most studies, the criteria for diagnosis are based on the subject's reporting, solely by questionnaire and rarely confirmed by skin testing. In addition, most studies focus on hay fever, leaving perennial allergic rhinitis underestimated. Sinus imaging is generally not performed and, therefore, rhinosinusitis not differentiated. Some investigators report 'current' prevalence while others report 'cumulative' or 'lifetime' prevalence. Epidemiologic studies have consistently shown that asthma and rhinitis often coexist in the same patients. The prevalence of asthma is <2% in subjects without rhinitis while it varies from 10% to 40% in patients with rhinitis. Furthermore, the majority of patients with asthma experience rhinitis, which is a factor in the risk for asthma. Despite recognition that allergic rhinitis and asthma are global health problems, there are insufficient epidemiologic data and more data are needed with regard to their etiologic risk factors and natural history. This aim of this review is to enable the reader to discuss prevalence, risk factors and prognosis of allergic rhinitis and asthma.

Effects of inhaled inactivated Mycobacterium phlei on airway inflammation in mouse asthmatic models

BACKGROUND

Corticosteroids are the most efficacious anti-inflammatory drugs for asthma therapy; however, steroids are not always completedly effective for asthma. Studies have shown Mycobacterium bovis Bacille Calmette-Guérin (BCG) and other mycobacterial infections suppress airway hyperresponsiveness and inflammation in asthma. We use a murine model of Ovalbumin (OVA)-induced asthma to study whether nebulized inhalation of inactivated Mycobacterium phlei can alleviate asthmatic airway inflammation through influencing cytokine production and determine whether it can prevent and treat asthma.

METHODS

Fifth male Balb/c mice were randomly divided into four groups: normal control group (A), asthma model group (B0, B3, B4, B5), the treatment group (C0, C3, C4, C5), and prevention group (D). Mice were sensitizated and challenged with Ovalbumin to make a murine asthma model. Group C were given treatment of aerosol Mycobacterium phlei once daily after OVA challenge. Groups C3, C4, and C5 were treated for 3 days, 4 days, and 5 days, respectively. Group D inhaled the solution of inactivated Mycobacterium phlei daily before each time of OVA challenge. All the animals were killed and lung tissue and bronchoalveolar lavage fluid (BALF) were harvested. Pathological HE staining and AB-PAS staining were done to measure lung inflammation and mucus production. Total cell numbers and differential cell count in BALF were performed. Cytokines IL-4, IL-10, and IFN-γ levels in BALF were quantified by ELISA.

RESULTS

In groups C4, C5, and D, IL-4 production in BALF was decreased and IL-10 and IFN-γ were increased (p<0.05).The number of total inflammatory cells and the mean percentage of eosinophils and lymphocytes in the BALF of group D, group C4, and group C5 was lower than in the corresponding group B (p<0.05). Histological examination of the lungs showed airway inflammation of group D and group C5 were attenuated.

CONCLUSION

The inhalation of Mycobacterium phlei can reduce airway inflammation in asthmatic mice. This ability was associated with its immunomodulatory effect on regulating IL-4, IL-10, and IFN-γ secretion. Aerosol administration of inactivated Mycobacterium phlei may be accepted as an alternative method with less risk of adverse reactions in treatment of asthma.

Lactobacillus crispatus KT-11 enhances intestinal immune functions in C3H/HeN mice

We investigated the effect of Lactobacillus crispatus KT-11 (KT-11) on intestinal immune systems in C3H/HeN mice. The level of intestinal total immunoglobulin (Ig) A was significantly higher in mice given KT-11 than in mice not given KT-11. Gene expression relating to antibody production and innate immune response increased more than 2-fold in the former compared with the later. Moreover, the number of IL-6(+)CD11b(+) cells was significantly higher in Peyer's patch cells cultured with KT-11 than in those cultured without KT-11, although the number of CD4(+) cells and the cell ratio of CD4(+)/CD8(+) were remarkably lower in the culture with KT-11. These results indicate that KT-11 enhances intestinal IgA production and innate immune response in C3H/HeN mice.

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.

The effect of Kawasaki disease on childhood allergies - a sibling control study

OBJECTIVE

Kawasaki disease (KD) is a multisystem inflammatory vasculitis of childhood, with widespread T-helper cell type 1 immune activation. We hypothesize that children who suffered from KD will have a lower risk of developing allergic diseases.

STUDY DESIGN

This was a cross-sectional study, recruiting children with a history of KD, together with well sibling controls. All children underwent the standardized core ISAAC questionnaire for allergy, physical examination and skin prick test evaluation. McNemar's test was employed to evaluate the effect of Kawasaki disease on allergy. Multivariable analysis based on mixed-effects logistic regression model was used to adjust for potential confounding effect of age and gender.

RESULTS

One hundred and eighty-six children (93 KD sibling pairs) completed the above evaluation. Allergic rhinitis was more common in patients with KD (crude OR 2.40; 95% CI 1.11-5.62, p=0.024) when compared with controls. The effect was further intensified after accounting for the potential confounding effect of age and gender (adjusted OR=2.90; 95% CI 1.27-6.60). Children in whom KD occurred beyond the age of 12 months had more allergic rhinitis (crude OR 4.00, 95% CI 1.29-16.44, p=0.012), 'any' allergies (crude OR 3.75, 95% CI 1.19-15.52, p=0.019) and Blomia tropicalis sensitization (crude OR 2.57, 95% CI 1.02-7.28, p=0.043) when compared with their sibling controls. Interestingly, children in whom KD course resulted in no coronary artery abnormalities have more allergic rhinitis (crude OR 8.50, 95% CI 2.02-75.85, p=0.003) and 'any' allergies (crude OR 5.00, 95% CI 1.41-26.94, p=0.011), when compared with their sibling controls.

CONCLUSION

Kawasaki disease may be a risk factor for subsequent allergic diseases. We postulate that KD occurs more frequently in children at risk of immune disequilibrium, with an abnormal inflammatory response initially, and subsequently more allergic manifestations.

[Childhood asthma and risk factors]

INTRODUCTION

This article summarizes the contribution of epidemiology to the understanding of childhood asthma. The first task in epidemiology is to determine prevalence and incidence of any disease.

PREVALENCE

Epidemiological investigations are aimed at evaluating hypotheses about causes of disease by defining demographic characteristics of a certain population as well as by determining possible effects of environmental factors. In spite of some limitations, data obtained by epidemiological investigations have been valuable in confirming both the increasing incidence of asthma and the differences in prevalence in certain population groups. The observance of this phenomenon has led to much speculation and a lot of attempts to identify the reasons behind the rising prevalence.

RISK FACTORS

Epidemiological studies have identified risk factors for the development of childhood asthma and provided insight into natural history of disease and prognosis. Factors ranging from increased numbers of immunizations to increased air pollution have been suggested, but subsequent analysis has failed to provide the supporting evidence to implicate most of these possibilities. The concept known as the hygiene hypothesis has gained some support from epidemiological studies.

CONCLUSION

The development of asthma as well as its severity are affected by numerous factors and their interactions can he explained by the heterogeneous nature of this disease.

Heat-killed lactic acid bacteria enhance immunomodulatory potential by skewing the immune response toward Th1 polarization

Heat-killed lactic acid bacteria not only possess immunomodulatory functions but also provide the advantages of longer product shelf life, easier storage, and more convenient transportation. To establish appropriate heat treatments for the industrial preparation of probiotics with immunomodulatory effects, 4 different heat treatments were used to kill 11 strains of lactic acid bacteria. Comparisons among the strains and with viable forms were carried out in terms of immunomodulatory activity and adhesion to Caco-2 cells. Field-emission scanning electron microscope (FE-SEM) was employed to observe morphological changes in bacteria after heating. Among the 11 viable strains, Lactobacillus gasseri AI-88 was the strongest inducer of interferon-gamma (IFN)-γ and interleukin (IL)-12p70 production. However, after heat treatments its stimulatory ability was attenuated. Heat-killed Enterococcus faecalis YM-73 and Lactobacillus salivarius AP-32 strains showed enhanced stimulation of IFN-γ and IL-12p70 secretion and coincidental decrease in IL-13 production. The adhesion of lactic acid bacteria to Caco-2 cells decreased with increases in temperature. However, heat exposure did not influence immunomodulatory activity. With rising temperature, roughness and unevenness of bacterial cell surfaces increased significantly. The results indicated that heat-killed E. faecalis YM-73 and L. salivarius AP-32 have immunomodulatory ability via increased Th1-associated cytokines and reduced Th2-associated cytokines, switching the immune response from a Th2 toward a Th1 response. These 2 heat-killed strains have the potential for development as commercial products.

The effects of Mycobacteria vaccae derivative on allergen-specific responses in children with atopic dermatitis

The capacity of microbial products to inhibit allergic inflammation make them logical candidates for novel therapies in allergic diseases such as atopic dermatitis. To assess the effects of intradermal Mycobacterium vaccae derivative on allergen-specific immune responses in children with moderate to severe atopic dermatitis. Peripheral blood mononuclear cells were isolated from children aged 5-16 years who received intradermal injections of M. vaccae derivative AVAC(TM) (n = 26) or placebo (n = 34) three times at 2-weekly intervals, weeks 0, 2 and 4. Cytokine [interleukin (IL)-13, interferon (IFN)-γ and IL-10] responses to allergen [house dust mite (HDM)], mitogen [phytohaemagglutinin (PHA)], Staphylococcal enterotoxin B (SEB) and Toll-like receptor (TLR) ligands were assessed. At week 8 (1 month after all injections given) children in the AVAC group showed a significant increase in IL-10 (P = 0·009), T helper type 1 (Th1) IFN-γ (P = 0·017) and Th2 IL-13 (P = 0·004) responses to HDM compared with baseline (week 0). There were no significant changes in any cytokine production in the placebo. HDM-specific IL-10 responses remained significantly higher (P = 0·014) than at baseline in the AVAC group by week 12; however, the HDM-specific IL-13 and IFN-γ responses were no longer significantly different from baseline. IL-13 (r = 0·46, P < 0·001) and IL-10 (r = 0·27, P = 0·044) responses to HDM were correlated with total immunoglobulin E but not with disease severity. There were no effects of AVAC on mitogen, SEB, TLR-2- or TLR-4-mediated responses. This M. vaccae derivative appeared to modulate responses to HDM selectively, suggesting the capacity for in vivo effects on allergen-specific immune responses.

Immune adjuvants in early life: targeting the innate immune system to overcome impaired adaptive response

The neonatal phase is a transitory period characterized by an absence of memory cells, favoring a slow adaptive response prone to tolerance effects and the development of Th2-type responses. However, when appropriately stimulated, neonates may achieve an immune response comparable with adult counterparts. One strategy to stimulate the immunological response of neonates or children in early infancy has been to explore natural or synthetic ligands of cell receptors to stimulate innate immunity. The use of adjuvants for activating different cell receptors may be the key to enhancing neonatal adaptive immunity. This review highlights recent advances in the emerging field of molecular adjuvants of innate immune response and their implications for the development of immunotherapies, with particular focus on the neonatal period.

The development of Th1-mediated sarcoidosis improves the clinical course of Th2-mediated atopic dermatitis

Sarcoidosis is a chronic multisystem disease of unknown origin, which is characterized by T-helper-1 (Th1)-mediated immune responses. On the other hand, atopic dermatitis (AD) is characterized by Th2-mediated immune responses. We recently experienced an interesting case of AD in which the patient experienced a significant resolution of AD after the onset of sarcoidosis. We herein describe the details of his clinical course and discuss the impact of negative cross-regulation between Th1 and Th2 immune responses.

Role of dendritic cells: a step forward for the hygiene hypothesis

The hygiene hypothesis was proposed more than two decades ago, but its mechanism remains unclear. This review focuses on recent advances in the field, especially on the role played by dendritic cells (DCs) and their modulating effects on various infections and allergic diseases, including allergic asthma. DCs isolated from mice long after the resolution of an infection were reported to have a significant modulating effect on allergen-specific Th2 responses in both in vitro and in vivo systems. These DCs showed DC1-like and/or tolerogenic DC capacity, which allowed for the inhibition of allergic responses by immune deviation (enhancing Th1 response) and immune regulation (through regulatory T-cell and Th2 hyporesponsiveness) mechanisms. These findings represented a significant advance in the elucidation of the mechanisms underlying the hygiene hypothesis. Further investigation on the mechanisms by which DCs are 'educated' by infectious agents and the influence of the type, time, and extent of infections on this 'education' process will help us understand immune regulation in disease settings and in the rational design of preventive/therapeutic approaches to allergy/asthma and infections.

The Human Lung Microbiome

The human lower respiratory tract is considered sterile in normal healthy individuals (Flanagan et al., 2007; Speert, 2006) despite the fact that every day we breathe in multiple microorganisms present in the air and aspirate thousands of organisms from the mouth and nasopharynx. This apparent sterility is maintained by numerous interrelated components of the lung physical structures such as the mucociliary elevator and components of the innate and adaptive immune systems (discussed below) (reviewed in (Diamond et al., 2000; Gerritsen, 2000)). However, it is possible that the observed sterility might be a result of the laboratory practices applied to study the flora of the lungs. Historically, researchers faced with a set of diseases characterized by a changing and largely cryptic lung microbiome have lacked tools to study lung ecology as a whole and have concentrated on familiar, cultivatable candidate pathogens.

Can multiple doses of BCG vaccine protect against asthma?

OBJECTIVE

To compare BCG vaccination involving a single intradermal dose and that involving multiple doses, one given with the multiple puncture technique, in terms of the protective effect against the subsequent onset of asthma.

METHODS

A retrospective cohort study involving 2,311 individuals having received the BCG vaccine. The patients were classified according to the number of doses of BCG vaccine administered (one; two; or three or more). The minimum follow-up period in order to determine whether there was any protective effect of BCG vaccination regarding the diagnosis of asthma was 10 years.

RESULTS

The sample included 1,317 individuals (56.99%) who had received only one BCG dose, 644 (27.87%) who had received two doses, and 350 (15.14%) who had received three or more doses. The number of patients diagnosed with asthma among those who had received one dose, two doses and three or more doses was, respectively, 216 (16.40%), 107 (16.61%) and 50 (14.28%). There were no significant differences among the groups.

CONCLUSIONS

In the study sample, the prevalence of asthma among individuals having received multiple doses of the BCG vaccine was no different than that observed among those having received a single dose.

The TLR7 agonist R848 alleviates allergic inflammation by targeting invariant NKT cells to produce IFN-gamma

It has been documented that TLR7 stimulation triggers not only antiviral responses, but also alleviates experimental asthma. Considering the implication of invariant NKT (iNKT) cells in both situations, we postulated that they might contribute to the anti-inflammatory effect of TLR7 ligands. We show in this study that spleen cells activated by the TLR7 agonist resiquimod (R848) attenuate allergic inflammation upon adoptive transfer when they are recovered from wild-type, but not from iNKT cell-deficient Jα18(-/-) mice, which proves the specific involvement of this regulatory population. Furthermore, we provide evidence that IFN-γ is critical for the protective effect, which is lost when transferred iNKT cells are sorted from IFN-γ-deficient mice. In support of a direct activation of iNKT cells through TLR7 signaling in vivo, we observed a prompt increase of serum IFN-γ levels, associated with upregulation of CD69 expression on iNKT cells. Moreover, we demonstrate that iNKT cells effectively express TLR7 and respond to R848 in vitro by producing high levels of IFN-γ in the presence of IL-12, consistent with the conclusion that their contribution to the alleviation of allergic inflammation upon treatment with TLR7 ligands is mediated through IFN-γ.

A PIM₂ analogue suppresses allergic airway disease

Two approaches for the synthesis of a phosphatidylinositol dimannoside (PIM₂) analogue 4 that mimics the suppressive activity of natural PIMs and also synthetic PIM₂ have been developed. This analogue, where the inositol core was replaced by glycerol, was tested for its ability to suppress cellular inflammation in a mouse model of allergic asthma and shown to be effective in suppressing airway eosinophilia. Suppression of all inflammatory cells monitored was observed, indicating a general blockade of cellular activity. These data indicate that the inositol core is not essential for this suppressive activity.

TLR4/MyD88-induced CD11b+Gr-1 int F4/80+ non-migratory myeloid cells suppress Th2 effector function in the lung

In humans, environmental exposure to a high dose of lipopolysaccharide (LPS) protects from allergic asthma, the immunological underpinnings of which are not well understood. In mice, exposure to a high LPS dose blunted house dust mite-induced airway eosinophilia and T-helper 2 (Th2) cytokine production. Although adoptively transferred Th2 cells induced allergic airway inflammation in control mice, they were unable to do so in LPS-exposed mice. LPS promoted the development of a CD11b(+)Gr1(int)F4/80(+) lung-resident cell resembling myeloid-derived suppressor cells in a Toll-like receptor 4 and myeloid differentiation factor 88 (MyD88)-dependent manner that suppressed lung dendritic cell (DC)-mediated reactivation of primed Th2 cells. LPS effects switched from suppressive to stimulatory in MyD88(-/-) mice. Suppression of Th2 effector function was reversed by anti-interleukin-10 (IL-10) or inhibition of arginase 1. Lineage(neg) bone marrow progenitor cells could be induced by LPS to develop into CD11b(+)Gr1(int)F4/80(+)cells both in vivo and in vitro that when adoptively transferred suppressed allergen-induced airway inflammation in recipient mice. These data suggest that CD11b(+)Gr1(int)F4/80(+) cells contribute to the protective effects of LPS in allergic asthma by tempering Th2 effector function in the tissue.

BCG vaccination and allergy: a systematic review and meta-analysis

BACKGROUND

There is conflicting evidence on whether BCG vaccination might represent an effective primary preventative strategy against the development of allergic sensitization and disease.

OBJECTIVES

We sought to systematically review the relationship between BCG vaccination and the risk of sensitization, eczema/atopic dermatitis, allergic rhinoconjunctivitis, asthma, and other allergic conditions, such as food allergy and anaphylaxis.

METHODS

Four international databases were searched for published epidemiologic or interventional studies. Additional online study databases were searched and vaccine manufacturers and a panel of international experts were contacted in an attempt to locate unpublished or ongoing studies. Quality assessment was undertaken by using internationally established criteria. Meta-analyses were undertaken by using fixed- or random-effects modeling. Funnel plots were used to assess for the risk of publication bias.

RESULTS

We identified 767 articles, of which 17 satisfied our inclusion criteria; there was only 1 randomized controlled trial, with the remaining studies being epidemiologic investigations. Meta-analyses did not show any protective effect of vaccination against the risk of sensitization, as judged by specific IgE tests (odds ratio [OR], 1.31; 95% CI, 1.07-1.60) or skin prick testing (OR, 0.87; 95% CI, 0.67-1.13); the risk of atopic eczema/dermatitis (OR, 0.84; 95% CI, 0.64-1.09); or the risk of allergic rhinoconjunctivitis (OR, 1.07; 95% CI, 0.89-1.28). BCG vaccination was associated with a protective effect against the risk of asthma (OR, 0.73; 95% CI, 0.56-0.95), although this might be explained by publication bias.

CONCLUSIONS

BCG vaccination is unlikely to be associated with protection against the risk of allergic sensitization and disease. The observed possible benefit in relation to the development of asthma is unlikely to be due to allergic sensitization.

What's new in atopic eczema?

IMPORTANCE OF THE FIELD

Atopic eczema (AE) is a chronic relapsing inflammatory skin condition and one of the most common, potentially debilitating diseases with increasing incidence.

AREAS COVERED IN THIS REVIEW

The complex etiology of AE with multiple systemic and local immunologic and inflammatory responses and interactions between susceptibility genes and environmental factors leading to defects in skin barrier function and eczematous skin lesions is presented. Knowledge of pathogenesis is important for understanding the more innovative treatment approaches discussed.

WHAT THE READER WILL GAIN

Basic therapy consists of hydrating topical treatment and avoidance of specific and unspecific provocation factors. For acute eczematous skin lesions, anti-inflammatory treatment consists mainly of topical glucocorticoids and topical calcineurin inhibitors (tacrolimus and pimecrolimus). Microbial colonization and superinfection may induce skin exacerbation, which can be treated by either topical or systemic antimicrobial treatment. Systemic anti-inflammatory therapy is limited to severe cases and consists of systemic steroids, cyclosporine A or mycophenolate mofetil. Novel anti-inflammatory concepts that go beyond corticosteroids are in the early phases of development. There are targeted therapeutic approaches, such as cytokine and chemokine modulators and it remains to be investigated how effective they will be and what side effects they may carry.

TAKE HOME MESSAGE

Existing treatment modalities such as barrier repair therapy, topical immunosuppressive agents, antiseptic treatment as well as systemic treatment options are discussed. The review aims to summarize the most recent findings of more innovative treatment approaches such as modulation of cytokines or chemokines, modulation of T-cell responses or anti-IgE therapy.

The other T helper cells in asthma pathogenesis

The complex phenotype of allergic bronchial asthma involves a variable degree of bronchoobstruction, increased mucus production, and airway remodeling. So far it is suggested that it arises from multiple interactions of infiltrating and structural cells in the context of chronic airway inflammation that is orchestrated by T helper 2 (TH2) cells. By secreting a plethora of typical mediators such as interleukin (IL) 4, IL-5, and IL-13, these cells hold a key position in asthma pathogenesis. However, therapeutic approaches targeting these TH2-type mediators failed to improve asthma symptoms and impressively showed that asthma pathogenesis cannot be reduced by TH2 cell functions. Recently, other T helper cells, that is, TH9 and TH17 cells, have been identified and these cells also contribute to asthma pathogenesis, the processes leading to formation or aggravation of asthma. Furthermore, TH25 cells, TH3 cells, and regulatory T cells have also been implicated in asthma pathogenesis. This paper aims at summarizing recent insights about these new T helper cells in asthma pathogenesis.

Inverse association between Helicobacter pylori infection and allergic rhinitis in young Japanese

BACKGROUND AND AIM

The prevalence of allergic disorders, including asthma, atopic dermatitis, and allergic rhinitis has been increasing, and the prevalence of Helicobacter pylori (H. pylori) infection has been decreasing. Chronic bacterial infection during childhood is reported to protect the development of allergic diseases. The aim of the present study was to identify whether H. pylori infection influences the prevalence of allergic rhinitis, which has become a serious social problem, especially in the developed countries.

METHODS

We initially investigated the association between the prevalence of H. pylori and pollinosis symptoms in 97 healthy volunteers. We had investigated the association between the serum H. pylori-immunoglobulin (Ig) G antibodies and specific IgE antibodies for pollen, mites, and house dust in 211 consecutive patients.

RESULTS

There were 52.2% (36/69) of H. pylori-negative volunteers with allergic symptoms, which was significantly higher than H. pylori-positive volunteers (14.3%, 4/28, P < 0.05). The risk of pollinosis symptoms by H. pylori infection was 0.148 (95% confidence interval): 0.046-0.475, P < 0.05). The prevalence of H. pylori infection increased according to age, whereas that of specific IgE-positive patients gradually decreased. Among the IgE-positive patients, the prevalence of H. pylori-negative patients was significantly higher than H. pylori-positive patients who were younger in age (P < 0.05).

CONCLUSION

H. pylori infection decreased the pollinosis effects, especially among the younger volunteers. However, the prevalence of pollinosis in patients who were 50 years or older were almost same between H. pylori-positive and H. pylori-negative patients; therefore, the recent increase of pollinosis might relate to not only H. pylori infection, but also change in social environment.

Control of Th2-mediated inflammation by regulatory T cells

Allergic diseases and asthma are caused by dysregulated Th2-type immune responses, which drive disease development in susceptible individuals. Immune tolerance to allergens prevents inflammatory symptoms in the respiratory mucosa and provides protection against inflammation in the airways. Increasing evidence indicates that Foxp3+ regulatory T cells (Tregs) play a critical role in immune tolerance and control Th2-biased responses. Tregs develop in the thymus from CD4(+) T cells (natural Tregs) and also in the periphery by the conversion of naïve CD4(+) T cells (induced Tregs). Increased susceptibility to allergy and airway inflammation is hypothesized to result from impaired development and function of Tregs. Thus, strategies to induce allergen-specific Tregs hold great promise for treatment and prevention of asthma.

Pathogens and immunologic memory in asthma: what have we learned?

Animal models and clinical studies of asthma have generated important insights into the first effector phase leading to the development of allergic airway disease and bronchial hyper-reactivity. In contrast, mechanisms related to asthma chronicity or persistence are less well understood. The CD4(+) T-helper 2 lymphocytes are known initiators of the inflammatory response associated with asthma. There is now increasing evidence that memory T-cells, sensitized against allergenic, occupational or viral antigens, are also involved in the persistence of asthma. Additionally, the role of pathogens in asthma has been linked to both the initial susceptibility to and flares of this disease. This review will discuss the potential links between infection and asthma, the role of the memory T-cells in asthma, and the potential mechanisms by which these factors interact to lead to the development and/or persistence of asthma.

COPD and the risk of tuberculosis--a population-based cohort study

Background

Both chronic obstructive pulmonary disease (COPD) and tuberculosis (TB) primarily affect the lungs and are major causes of morbidity and mortality worldwide. COPD and TB have common risk factors such as smoking, low socioeconomic status and dysregulation of host defence functions. COPD is a prevalent co-morbid condition, especially in elderly with TB but in contrast to other diseases known to increase the risk of TB, relatively little is known about the specific relationship and impact from COPD on TB-incidence and mortality.

Methods and Findings

All individuals ≥40 years of age, discharged with a diagnosis of COPD from Swedish hospitals 1987–2003 were identified in the Swedish Inpatient Register (n = 115,867). Records were linked to the Swedish Tuberculosis Register 1989–2007 and the relative risk of active TB in patients with COPD compared to control subjects randomly selected from the general population (matched for sex, year of birth and county of residence) was estimated using Cox regression. The analyses were stratified by year of birth, sex and county of residence and adjusted for immigration status, socioeconomic status (SES) and inpatient co-morbidities previously known to increase the risk of TB. COPD patients had a three-fold increased hazard ratio (HR) of developing active TB (HR 3.0 (95% confidence interval 2.4 to 4.0)) that was mainly dependent on an increased risk of pulmonary TB. In addition, logistic regression estimates showed that COPD patients who developed active TB had a two-fold increased risk of death from all causes within first year after the TB diagnosis compared to the general population control subjects with TB (OR 2.2, 95% confidence interval 1.2 to 4.1).

Conclusions

This population-based study comprised of a large number of COPD patients shows that these patients have an increased risk of developing active TB compared to the general population. The results raise concerns that the increasing global burden of COPD will increase the incidence of active TB. The underlying contributory factors need to be disentangled in further studies.

Administration of antibiotics during infancy promoted the development of atopic dermatitis-like skin lesions in NC/Nga mice

This study aimed to determine whether oral antibiotic administration during infancy is associated with the spontaneous development of atopic dermatitis-like skin lesions by modulating intestinal microbiota. Female NC/Nga mice at 3 weeks of age were orally administered kanamycin or polymyxin B. Clinical symptoms, scratching behavior, and serum antibody levels were evaluated. Changes in intestinal microbiota were determined by culture-independent analysis and cultural analysis. The kanamycin-treated mice showed higher clinical scores and scratching frequency than the control mice. IgE levels were significantly higher in the kanamycin-treated mice than in the control mice. Transient changes in intestinal microbiota were observed under kanamycin treatment. Polymyxin B treatment failed to affect scratching behavior. These results suggest that oral administration of kanamycin during infancy promoted the development of atopic dermatitis-like skin lesions in NC/Nga mice and was associated with a transient change in intestinal microbiota.

Diesel exhaust (DE) aggravates pathology of delayed-type hypersensitivity (DTH) induced by methyl-bovine serum albumin (mBSA) in mice

Diesel exhaust particles (DEP), a well-known air pollutant, exacerbate type I hypersensitivity conditions, such as asthma and pollen allergy. In this study, we examined the effect of diesel exhaust (DE) exposure on delayed-type hypersensitivity (DTH), a type IV hypersensitivity, induced with methyl-bovine serum albumin (mBSA) in C57BL/6 mice. Mice were exposed to DE containing DEP at a dose of 1.78 mg/m(3) in an inhalation chamber for 14 days. On Day 7, DTH mice and DE-exposed DTH mice were injected s.c. with 200 microl of 1.25 mg/ml mBSA emulsified with CFA in the dorsal region as initial sensitization. On Day 14, mice were injected s.c. into one footpad with 20 microl of 10 mg/ml mBSA dissolved in PBS as challenge. On Day15, footpad thickness and spleen weight were measured. Significant footpad swelling (%) was observed in DTH mice compared with normal control mice, and this swelling was significantly augmented by DE exposure. The levels of pro-inflammatory cytokines, including IFN-gamma, TNF-alpha, and IL-6, in DTH mice were significantly higher than in normal mice, and were also further enhanced by DE exposure. DE exposure increased production of IL-17, which enhances local tissue inflammation through up-regulation of pro-inflammatory cytokines, while production of IL-10, which inhibits local tissue inflammation through suppression of immune cell proliferation, was unchanged. No change was observed in the percentage of CD4(+)CD25(+)Foxp3(+)T regulatory (Treg) cells in splenic lymphocytes following DE exposure. IL-6 production was increased by DE, and this would facilitate the differentiation of naïve T cells to IL-17-producing Th17 cells, while concomitantly suppressing the competing differentiation pathway to IL-10-producing Treg cells. Our results indicate that DE inhalation may, in part, exacerbate the pathological symptoms of DTH and induction of pro-inflammatory cytokines such as IFN-gamma, TNF-alpha, IL-6 and IL-17.

Mycobacterium bovis bacillus Calmette-Guérin killed by extended freeze-drying targets plasmacytoid dendritic cells to regulate lung inflammation

We have previously shown that bacillus Calmette-Guérin (BCG) inactivated by extended freeze-drying (EFD) reduces airway hyperresponsiveness, whereas live and heat-killed BCG fail to do so. However, the cells involved in the protective effect and the signaling and transcriptional networks that could reprogram T cell commitment after EFD BCG treatment remained to be elucidated. We investigated whether EFD BCG targets plasmacytoid dendritic cells (pDCs) potentially involved in the polarization of regulatory T cells (Tregs) and the transcriptional factors that regulate allergic inflammation. OVA-sensitized mice were s.c. injected with EFD, live, or heat-killed BCG. We analyzed after the injection of the various BCG preparations: 1) pDCs recruited in the draining lymph nodes (day 4); 2) transcription factors involved in inflammation and T cell commitment in spleen and lungs after OVA challenge (day 28). Airway hyperresponsiveness and transcription factors were determined after in vivo depletion of pDCs or Tregs in EFD BCG-treated and OVA-challenged mice. EFD BCG reduced inflammation via the recruitment of pDCs polarizing the differentiation of naive CD4+ T lymphocytes into Tregs. In vivo, pDC or Treg depletion at the time of EFD BCG treatment abrogated the protection against inflammation. EFD BCG treatment upregulated Forkhead-winged helix transcription factor (Treg signature) and downregulated GATA-3 and RORgammat (Th2 and Th17 signatures) more efficiently than live and heat-killed BCG. Moreover, only EFD BCG enhanced peroxisome proliferator-activated receptor gamma expression and blocked NF-kappaB activation, cyclooxygenase expression, and p38 MAPK phosphorylation. EFD BCG reduced allergic inflammation by recruiting pDCs that promoted Tregs; EFD BCG acted as a peroxisome proliferator-activated receptor gamma agonist and thus could be used in asthma and other inflammatory diseases.

Does BCG vaccination protect against the development of childhood asthma? A systematic review and meta-analysis of epidemiological studies

BACKGROUND

Results have been conflicting as to whether Bacillus Calmette-Guérin (BCG) vaccine, a non-specific stimulator of the immune function, protects, predisposes or is unrelated to the development of childhood asthma. In this systematic review and meta-analysis, we qualitatively and quantitatively appraised the epidemiological evidence.

METHODS

Eligible studies were identified using a search strategy that included a computerized literature search and a manual search of each article's reference list, up to June 2008. A total of 23 studies were included (10 cohort, 5 case-control and 8 cross-sectional). Each study was summarized and rated for methodological quality. Pooled odds ratio (OR) estimates and 95% confidence intervals (CIs) were calculated using fixed-effects (FE) or random-effects (RE) models; if heterogeneity was present, the latter was used. Three indicators of BCG exposure were considered including BCG vaccination, tuberculin response and scar diameter.

RESULTS

The pooled estimate of association for 23 studies reporting on any of the three indicators suggested a protective effect of BCG exposure on childhood asthma occurrence. The studies were heterogeneous, especially when tuberculin response was considered. Restriction to a subgroup of 16 studies that considered BCG vaccination indicated a protective effect with no evidence of heterogeneity. The overall pooled OR using an FE model was 0.86 (95% CI 0.79-0.93). Exclusion of three studies with the lowest quality scores showed a similar association.

CONCLUSION

These results strengthen the epidemiological evidence in support of the hypothesis that exposure to the BCG vaccine in early life prevents asthma, possibly through a modulation of the immune maturation process.

Enhancement of Th1 lung immunity induced by recombinant Mycobacterium bovis Bacillus Calmette-Guerin attenuates airway allergic disease

Mycobacterium bovis Bacillus Calmette-Guerin (BCG) has been shown to down-regulate experimental allergic asthma, a finding that reinforced the hygiene hypothesis. We have previously found that recombinant BCG (rBCG) strain that express the genetically detoxified S1 subunit of pertussis toxin (rBCG-S1PT) exerts an adjuvant effect that enhances Th1 responses against BCG proteins. Here we investigated the effect of this rBCG-S1PT on the classical ovalbumin-induced mouse model of allergic lung disease. We found that rBCG-S1PT was more effective than wild-type BCG in preventing Th2-mediated allergic immune responses. The inhibition of allergic lung disease was not associated with increased concentration of suppressive cytokines or with an increased number of pulmonary regulatory T cells but was positively correlated with the increase in IFN-gamma-producing T cells and T-bet expression in the lung. In addition, an IL-12-dependent mechanism appeared to be important to the inhibition of lung allergic disease. The inhibition of allergic inflammation was found to be restricted to the lung because when allergen challenge was given by the intraperitoneal route, rBCG-S1PT administration failed to inhibit peritoneal allergic inflammation and type 2 cytokine production. Our work offers a nonclassical interpretation for the hygiene hypothesis indicating that attenuation of lung allergy by rBCG could be due to the enhancement of local lung Th1 immunity induced by rBCG-S1PT. Moreover, it highlights the possible use of rBCG strains as multipurpose immunomodulators by inducing specific immunity against microbial products while protecting against allergic asthma.

No association between tuberculin skin test and atopy in a bacillus Calmette-Guérin vaccinated birth cohort

Previously, an inverse association was suggested between mycobacterial infection and atopy. We aimed to determine the association between tuberculin skin test (TST) and allergic manifestations in a birth cohort where all infants were vaccinated with bacillus Calmette-Guérin (BCG) at birth. Newborns were enrolled randomly and prospectively followed up for a period of 5 yr. Information on family history and environmental factors was obtained at birth, International Study of Asthma and Allergies in Childhood asthma questionnaire, physical examination, skin prick test to common inhalant and food allergens and TST were performed at 2 and 5 yr of age. Positive TST reactivity was defined as an induration of > or = 10 mm. A total of 399 newborns were enrolled, 293 and 125 were available for a followup visit at 2 and 5 yr of age respectively. The prevalence of ever asthma, rhinitis and allergen sensitization tended to increase while eczema decreased with time. No significant association was found between TST reactivity and ever and current wheeze, doctor diagnosed asthma or atopic sensitization both at 2 and 5 yr of age. This prospectively designed birth cohort study did not confirm the previously suggested inverse correlation between TST reactivity and atopic sensitization or any allergic manifestations in Turkish children vaccinated with BCG at birth.