The association of airway hyperresponsiveness and tuberculin responses

Impact of Allergic Disease on the Risk of Mycobacterial Disease

BACKGROUND

The association between allergic diseases and the risk of mycobacterial disease is unclear.

OBJECTIVE

To evaluate the association between allergic diseases and mycobacterial diseases.

METHODS

This was a population-based cohort study of 3,838,680 individuals, without prior mycobacterial disease, who participated in the 2009 National Health Screening Exam. We evaluated the incidence of mycobacterial disease (tuberculosis or nontuberculous mycobacterial infection) in participants with allergic disease (asthma, allergic rhinitis, or atopic dermatitis) and those without allergic disease. We followed the cohort up until the date of mycobacterial disease diagnosis, follow-up loss, death, or December 2018.

RESULTS

During a median follow-up of 8.3 (interquartile range, 8.1-8.6) years, 0.6% of participants developed mycobacterial disease. The incidence of mycobacterial disease was significantly higher in those with allergic diseases than in those without allergic diseases (1.0 vs 0.7/1000 person-years; P < .001), with an adjusted hazard ratio of 1.13 (95% CI, 1.10-1.17). Asthma (adjusted hazard ratio, 1.37; 95% CI, 1.29-1.45) and allergic rhinitis (adjusted hazard ratio, 1.07; 95% CI, 1.04-1.11) increased the hazard of mycobacterial disease, whereas atopic dermatitis did not. The association between allergic diseases and hazard of mycobacterial disease was more prominent in older (age ≥ 65 years, P for interaction = .012) and obese (body mass index ≥ 25 kg/m2, P for interaction < .001) participants.

CONCLUSION

Allergic diseases including asthma and allergic rhinitis were associated with an increased risk of mycobacterial disease, whereas atopic dermatitis was not.

GSDMB/ORMDL3 variants contribute to asthma susceptibility and eosinophil-mediated bronchial hyperresponsiveness

In 2007, a genome-wide association study identified associations between variants involved in the regulation of ORMDL3 expression and asthma. These observations were subsequently replicated in case-control studies in several ethnic groups. We investigated the possible contribution of GSDMB/ORMDL3 variants to asthma susceptibility and intermediate asthma phenotypes in Korean children. The polymorphisms rs7216389, rs4794820, rs4065275, and rs11650680 were genotyped using the TaqMan assay in 931 asthmatics and 480 normal controls in a case-control study, and in 1907 elementary school children in a general population study. Each subject also underwent peripheral blood analysis of immunoglobulin E levels, eosinophil cationic protein (ECP) levels, and eosinophil percentage. Pulmonary function testing (FEV(1) and MMEF) and a methacholine provocation test (PC(20)) were also performed. The case-control study revealed a significant association between a linkage disequilibrium block, including rs7216389, rs4794820, and rs4065275, and susceptibility to asthma and atopic asthma. The CT and TT genotypes of rs11650680 were associated with lower logECP levels than the CC genotype in asthmatics, while the GA and AA genotypes of rs4794820 were associated with higher logPC(20) values than the GG genotype in atopic asthmatics. The haplotype (CAA) of rs7216389, rs4794820 and rs4065275 was associated with a lower risk of asthma susceptibility and a higher logPC(20). In the general population study, rs11650680 was significantly associated with a diagnosis of asthma. Moreover, the GA and AA genotypes of rs4794820 were associated with higher logPC(20) values and lower eosinophil percentages than the GG genotype in subjects who had been diagnosed with asthma, or showed bronchial hyperresponsiveness (PC(20)≤16). The GSDMB/ORMDL3 gene block, which includes rs7216389, rs4065275, rs4794820, and rs11650680, may be associated with asthma susceptibility in Korean children because it promotes eosinophilic inflammation, which induces bronchial hyperresponsiveness.

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.

Lack of an inverse association between tuberculosis infection and atopy: by T-cell-based immune assay (RD1-ELISpot)

The association between mycobacterial exposure, vaccination with bacillus Calmette-Guerin (BCG) in early life and atopy remains controversial. Distinguishing between environmental mycobacterial exposure, TB infection and BCG-vaccination is not possible with the tuberculin skin test (TST) but new accurate blood-tests for TB infection present an opportunity to differentiate TB infection from environmental mycobacterial exposure and BCG-vaccination. We used a new blood test in parallel with TST to investigate whether Mycobacterium tuberculosis infection and/or BCG vaccination are associated with development of atopy in children with prior household TB contacts. All children who had contact with adult active pulmonary TB during the last 6 months underwent TST, chest radiography, and RD1-ELISpot assay. The presence of a BCG scar was documented, and assessment of atopy was carried out by International Study of Asthma and Allergies in Childhood questionnaire, allergy skin prick testing (SPT) and evaluation of serum total IgE. Among 361 children enrolled 39 (11%) had a positive SPT, 236 (63%) positive TST, and 189 (52%) positive RD1-ELISpot. The frequency of SPT positivity, ever wheezing, allergic rhinitis, doctor-diagnosed asthma, high serum IgE level, and median total serum IgE levels did not differ significantly different by TST or RD1-ELISpot status. On the other hand, presence of BGC scar was associated with lower median total serum IgE level (p = 0.01) and lower frequency of high IgE (p = 0.003). M. tuberculosis infection whether measured by TST or RD1-ELISpot, was not associated with atopy in children with household TB contact. Presence of a BCG vaccination scar was inversely associated with atopy, as measured by serum IgE.

Tuberculin reactivity and allergic disorders in schoolchildren, Okinawa, Japan

BACKGROUND

Bacillus Calmette-Guérin (BCG) vaccination triggers a T-helper type 1 response. Whether BCG vaccination and positive tuberculin reactivity are preventive against allergic disorders remains controversial.

OBJECTIVE

The current cross-sectional study investigated the relationship of BCG vaccination and tuberculin reactivity with the prevalence of allergic disorders using data from the Ryukyus Child Health Study (RYUCHS).

METHODS

Subjects were 5717 schoolchildren aged 8-11 years in Okinawa, Japan. The RYUCHS collected information on symptoms of allergic disorders and potential confounding factors. The outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Data on BCG vaccination and tuberculin tests were obtained from school records. Allowance was made for grade, sex, sibship size, smoking in the household, paternal and maternal history of asthma, atopic eczema, and allergic rhinitis, and paternal and maternal educational level.

RESULTS

No measurable relationship was found between BCG vaccination in infants and the prevalence of allergic disorders. Among 5567 BCG-vaccinated children, positive tuberculin reactivity (induration >/=10 mm) in the first grade was independently associated with a decreased prevalence of wheeze, asthma, and atopic eczema: the multivariate odds ratios for wheeze, asthma, and atopic eczema were 0.80 (95% confidence interval [CI], 0.67-0.94), 0.78 (95% CI, 0.64-0.95), and 0.77 (95% CI, 0.62-0.95), respectively. The inverse associations were more pronounced in children with a negative parental allergic history than in those with a positive parental allergic history. There was no significant relationship between tuberculin reactivity and allergic rhinoconjunctivitis.

CONCLUSIONS

The findings suggest that positive tuberculin reactivity may be inversely associated with the prevalence of wheeze, asthma, and atopic eczema, but not allergic rhinoconjunctivitis, especially among Japanese children without a parental allergic history.

Mycobacterial infection and atopy in childhood: a systematic review

The epidemiological relation between mycobacterial infection and the prevalence of atopic disease in humans is still unclear. This is in contrast to studies in murine models in which a clear suppression of atopic symptoms was observed after exposure to mycobacteria or mycobacterial products. We therefore wanted to provide a systematic overview of the published literature on the relationship between mycobacterial infection and atopic disease and to evaluate the causal relationship in a meta-analysis. The EMBASE and MEDLINE databases were searched systematically for papers published in the English literature (1966-2005) on the relation between mycobacterial infection and atopic disease. Original observational or interventional studies involving the paediatric population were included. Two authors independently reviewed articles for data on mycobacterial exposure and atopic disease outcome. Any differences were resolved by discussion. Of a total of 1201 hits, 23 studies (19 cross-sectionals, three case-controls and one prospective cohort) met the inclusion criteria. Only a minority of studies (40%) observed an association between mycobacterial infection and the prevalence of atopic disease outcome. In the meta-analysis, only studies containing data on mycobacterial exposure and atopic disease outcome variables were included. Only cross-sectional studies, in which the relation between a positive tuberculin skin test and allergic symptoms was studied, observed statistically significant negative correlation (odds ratio 0.63; 95% confidence interval: 0.51-0.79). The results of this review show that the evidence of the relationship of mycobacterial infection and atopic disease is based on observations of cross-sectional studies. In a meta-analysis, calculations showed a high level of heterogeneity (I(2)) within studies with similar design making it difficult to pool effects. This may partly be explained by differences in the type and definition of mycobacterial infection and lack of uniformity in the definition of atopy. The results show that only a minority of studies in the literature shows any evidence of inverse relationship between mycobacterial exposure and atopic disease outcome. The fact that the present epidemiological evidence on the relationship between mycobacterial infection and the development of atopic disease is based mainly on cross-sectional observational studies indicates the need for population-based prospective studies to address this issue. This issue needs to be addressed in view of recent suggestions to developing mycobacterial-based vaccines against atopic disease in the future.

The potential of Mycobacterium to protect against allergy and asthma

The increase in the global incidence of atopic disease and asthma during the past few decades has been ascribed to environmental factors, including the reduction in exposure to serious infections. The hypothetical framework to explain the inverse relationship between infections and atopic disease and asthma has been called the "hygiene hypothesis." Animal and experimental models have identified Mycobacteria as important potential candidates in the hygiene hypothesis by demonstrating that exposure to Mycobacteria or mycobacterial proteins led to subsequent reduction in different atopic manifestations. Although there are epidemiological studies in support, they have not always been consistent. In this review we appraise epidemiologic evidence on the inverse relationship between mycobacterial exposure and atopic disease, explore the immunological mechanisms involved and evidence that this effect may be dose-dependent, and discuss the challenges facing the use of Mycobacteria as vaccine for prevention of atopic disease.

A comparative study of inhaled ciclesonide 160 microg/day and fluticasone propionate 176 microg/day in children with asthma

Ciclesonide (CIC) is an inhaled corticosteroid (ICS) with high anti-inflammatory activity and low incidence of local and systemic adverse effects. The objective of this study was to compare the efficacy and safety of CIC with fluticasone propionate (FP) in children and adolescents with persistent asthma. This was a 12-week, randomized, double blind, parallel-group study. After a 2-to 4-week baseline period, a total of 556 children (ages 6-15 years) with asthma (forced expiratory volume in 1 sec [FEV(1)], 50% to 90% predicted) were treated twice daily with CIC 80 microg (ex-actuator, equivalent to 100 microg ex-valve) or FP 88 microg (ex-actuator, equivalent to 100 microg ex-valve) administered via a hydrofluoroalkane-propelled metered-dose inhaler. A statistically significant increase from baseline was observed in FEV(1) for both CIC (285 +/- 16 ml) and FP (285 +/- 15 ml) (P < 0.0001 for both) and in morning and evening peak expiratory flow (P < 0.0001 for both). Significant improvements were seen in asthma symptoms, use of rescue medication, and asthma symptom-free days in both treatment groups, without any differences between the treatment groups in changes from baseline. Two FP-treated patients experienced oral candidiasis and one patient experienced voice alteration. Creatinine-adjusted 24-hr urine cortisol levels increased from baseline levels by 10% in the CIC group (P < 0.05) and by 6% in the FP group (not significant). The efficacy and safety of CIC 160 microg/day were comparable to those of FP 176 microg/day in children with asthma.

Hope for the hygiene hypothesis: when the dirt hits the fan

The hygiene hypothesis was developed in response to data suggesting that the increase in allergic diseases as well as asthma was secondary to a reduced exposure to infectious stimuli. Indeed, the epidemiologic changes, resulting in an increase in atopic disease, have been impressive and intriguing. Furthermore, although there clearly is a genetic component to atopic diseases, genetics cannot account for a marked increase in the incidence and prevalence of allergic manifestations within a few generations. Thus, environmental factors have been suggested as responsible for the changing prevalence. There are two--not mutually exclusive--possibilities, namely, that substances that promote atopy have been added to the environment or that factors that provided protection from allergic disease were lost from the environment. Both outdoor and indoor pollution, along with a long list of other environmental factors, have been proposed. It is of interest that in many developed countries, certain types of pollution have decreased, whereas the prevalence of atopic disease has increased. In this review, we have explored a detailed analysis of a large number of studies that have focused on this issue and suggest that, although the hygiene hypothesis has merit, the stimuli responsible for the new epidemiology remain enigmatic.

The influence of childhood infections and vaccination on the development of atopy: A systematic review of the direct epidemiological evidence

BACKGROUND

The 'hygiene hypothesis' has been used to justify a belief common among homeopaths, that the suppression of childhood infections and immunisation may lead to the development of chronic atopic diseases.

OBJECTIVES

To analyse the influence of childhood infections and immunisation on the development of atopy.

METHODS

Qualitative systematic review of direct epidemiological evidence (Medline 1993-2004) concerning the influence of childhood infections and immunisation on the development of atopy and discussion based on homeopathy.

CONCLUSIONS

(1) Childhood infections do not protect against atopy; on the contrary, they increase the risk of allergic diseases, in agreement to Hahnemann's observations, which included epidemic diseases among the factors capable of stimulating the development of chronic diseases. (2) Vaccination is not a risk factor for atopy, notwithstanding the allergenic effect of some vaccines.

Does childhood immunization against infectious diseases protect from the development of atopic disease?

The argument of whether early immunization against infections promotes allergy or protects from it is presently under debate. The relationship between childhood immunization and the development of atopic diseases (asthma, allergic rhinitis and eczema) was examined in a population-based sample of 718 adolescents by taking individual data drawn from personal paediatric records on the schedule and the type of vaccination into account. Atopic diseases were determined using a standardized questionnaire. After adjustment for sex, age, father's socioeconomic status and active smoking, adolescents having been vaccinated (n = 694) had a significant lower risk to suffer from asthma or atopic diseases than non-vaccinated adolescents did (n = 24) [odds ratio (OR) = 0.30; 95% CI: 0.10, 0.92]. The relationship did not depend on the disease against which the vaccine was used as prophylaxis, the observance of the vaccination schedule or the number of inoculations. A higher protection was observed in the case of live attenuated vaccines (oral poliomyelitis and bacilli Camille-Guerin; OR = 0.26; 95% CI: 0.08, 0.83). These results, in agreement with previous ecological data, support the hypothesis that early vaccines could promote Th1 proliferation in response to the infectious agent contained in it, which inhibits the enhancement of atopic manifestations. Further studies are needed to confirm the phenomenon.

Lower prevalence of reported asthma in adolescents with symptoms of rhinitis that received neonatal BCG

BACKGROUND

BCG is a vaccine used against tuberculosis and leprosy and is an immunostimulant that primes T(H)1 lymphocytes to produce cytokines that antagonize atopy both in animal models and in man. Considering that atopy is the main risk factor for asthma, one can hypothesize that vaccination inducing T(H)1 responses, such as BCG, can be protective against asthma.

METHODS

OBJECTIVE

To estimate the association between neonatal BCG vaccination and prevalence of asthma among adolescents.

STUDY DESIGN

Cross-sectional study with schoolchildren aged 12-16 years. The presence of a scar compatible with BCG was used as a surrogate of neonatal vaccination. A self administered structured questionnaire was prepared based on that used by the International Study of Asthma and Allergies in Childhood. The prevalence of asthma was categorized according to the report of lifetime wheeze, lifetime asthma, lifetime asthma among those referring allergy and among those referring allergy and sneezing.

RESULTS

Neonatal BCG vaccination was not associated with the overall prevalence of reported wheezing or asthma. However, in the subgroup reporting current allergy and sneezing, neonatal BCG was associated with a 37% reduction of prevalence of lifetime asthma.

CONCLUSIONS

In the population we surveyed, neonatal BCG scar was associated with a reduction in the risk of asthma only in individuals with a past history suggestive of allergic rhinitis.

Age at bacille Calmette-Guérin vaccination and risk of allergy and asthma

BACKGROUND

It has been proposed that early age at bacille Calmette-Guérin (BCG) vaccination protects against the development of allergy.

OBJECTIVE

To study whether early age at BCG vaccination was associated with a decreased risk of atopy, allergic rhinitis, and asthma compared to BCG vaccination at later ages in childhood.

METHODS

The occurrence of atopy, allergic rhinitis, and asthma was studied in nearly 2000 women participating in the Danish National Birth Cohort study. Detailed information on age at BCG vaccination (age 0-15 years) was available from school health records. Atopic status was assessed serologically by a specific response to 11 common inhalant allergens using serum samples obtained from the women during the period 1997-2001. Information on allergic rhinitis and asthma was available from telephone interviews.

RESULTS

Approximately 85% of the women had been BCG-vaccinated. Age at BCG vaccination was not associated with risk of atopy, allergic rhinitis, or asthma. The odds ratio of atopy, allergic rhinitis, and asthma associated with being vaccinated during the first year of life was 1.05 (95% CI 0.71-1.56), 1.42 (95% CI 0.85-2.36), and 1.71 (95% CI 0.91-3.20), respectively, compared with being vaccinated at the age of 7 years. Adjustment for birth cohort, sibship size, age of the woman's mother at birth, and social class in childhood did not affect the results.

CONCLUSION

Our findings suggest that age at BCG vaccination in childhood does not influence the development of allergy or asthma.

Inhibition of allergic disorders by infection with bacteria or the exposure to bacterial products

The incidence, severity, and mortality rate of allergic diseases, such as asthma, atopic dermatitis and rhinitis is increasing in the developed nations of the world, despite the use of steroids and other drugs. The reason for this development is unknown, but has been speculated to be due to a steady decline in infectious diseases. This view is supported by recent epidemiological and experimental findings showing that bacterial infections have the capacity to inhibit the development of allergic disorders. In addition, the exposure to bacterial products such as lipopolysaccharide (LPS) or bacterial DNA is also associated with a decrease in allergen-specific Th2 responses. Although the immunological mechanisms responsible for these protective effects are ill defined, recent publications indicate that they are associated with the induction of Th1 or T regulatory responses. This review focuses on experimental and epidemiological studies addressing the question if bacterial infections or the exposure to bacterial products can inhibit the development of allergic responses.