Polyclonal and allergen-induced cytokine responses in adults with asthma: resolution of asthma is associated with normalization of IFN-gamma responses

Novel Toll-Like Receptor 9 Agonist Derived from Cryptococcus neoformans Attenuates Allergic Inflammation Leading to Asthma Onset in Mice

INTRODUCTION

The enhanced type 2 helper (Th2) immune response is responsible for the pathogenesis of allergic asthma. To suppress the enhanced Th2 immune response, activation of the Th1 immune response has been an alternative strategy for anti-asthma therapy. In this context, effective Th1-inducing adjuvants that inhibit the development of allergic asthma but do not flare the side effects of the primary agent are required in clinical treatment and preventive medicine.

OBJECTIVE

In this study, we aimed to determine the regulation of the Th2 type immune response in asthma by a novel immunostimulatory oligodeoxynucleotide (ODN) derived from Cryptococcus neoformans, termed ODN112, which contains a cytosine-guanine (CG) sequence but not canonical CpG motifs.

METHODS

Using an ovalbumin-induced asthma mouse model, we assessed the effect of ODN112 on prototypical asthma-related features in the lung and on the Th1/Th2 profile in the lymph nodes and lung of mice treated with ODN112 during sensitization.

RESULTS AND CONCLUSION

ODN112 treatment attenuated asthma features in mice. In the bronchial lymph nodes of the lungs and in the spleen, ODN112 increased interferon-γ production and attenuated Th2 recall responses. In dendritic cells (DCs) after allergen sensitization, ODN112 enhanced cluster of differentiation (CD) 40 and CD80 expression but did not alter CD86 expression. Interleukin-12p40 production from DCs was also increased in a Th2-polarizing condition. Our results suggest that ODN112 is a potential Th1-inducing adjuvant during Th2 cell differentiation in the sensitization phase.

Prenatal tobacco smoke exposure predisposes offspring mice to exacerbated allergic airway inflammation associated with altered innate effector function

Background

Epidemiological studies suggest that prenatal and early life environmental exposures have adverse effects on pulmonary function and are important contributors in the development of childhood asthma and allergic disease. The mechanism by which environmental tobacco smoke (ETS) exposure in utero promotes the development of allergic asthma remains unclear. In this study, we investigated the immunological consequences of prenatal exposure to ETS in order to understand events responsible for the development or exacerbation of allergic asthma.

Methods

Pregnant C57BL/6 mice were exposed to either ETS or filtered air throughout gestation and the effect on pulmonary inflammation in the offspring were examined and compared. Specifically, the effects on eosinophilic inflammation, airway hyperreactivity, goblet cell hyperplasia, properties of pulmonary natural killer (NK) cells and type 2 cytokines elicited in response to inhaled house dust mite (HDM) allergen were investigated in the progeny.

Results

Exposure to ETS prenatally significantly exacerbated HDM-induced airway eosinophilic inflammation, hyperreactivity, mucus secretion, cysteinyl leukotriene biosynthesis and type 2 cytokine production in the offspring. Consistently, lung mononuclear cells from ETS-exposed offspring secreted higher levels of IL-13 when stimulated in vitro with anti-αβ TCR antibody or HDM allergen. Moreover, offspring from ETS-exposed dams exhibited a higher frequency of CD11b⁺ dendritic cells and CD3⁺CD4⁺ T lymphocytes in the lungs following allergen inhalation compared to air-exposed mice. Unexpectedly, the exacerbated allergic inflammation in the ETS-exposed offspring was associated with a reduction in CD3⁻CD19⁻NK1.1⁺CD94⁺ NK cell numbers and their IFN-γ production, highlighting a role for altered innate immunity in the enhanced allergic response.

Conclusion

Our results reveal that prenatal exposure to ETS predisposes offspring to an exacerbated allergic airway inflammation that is associated with a reduction in pulmonary NK cell function, suggesting that NK cells play a key role in controlling asthma severity.

Mahuang Fuzi Xixin Decoction Attenuates Th1 and Th2 Responses in the Treatment of Ovalbumin-Induced Allergic Inflammation in a Rat Model of Allergic Rhinitis

Allergic rhinitis (AR) is one of the most common allergic diseases, which adversely affect patients' quality of life. Mahuang Fuzi Xixin decoction (MFXD) has been widely used to treat AR in clinics in Asian countries. This study investigated the effect and possible therapeutic mechanisms of MFXD in the treatment of AR. A Wistar rat model of ovalbumin- (OVA-) induced AR was established and then treated with three doses of MFXD; AR symptoms, serum total immunoglobulin E, histamine, histopathological features, and release and expression of factors related to type 1 helper T (Th1) and type 2 helper T (Th2) responses were analyzed. Our study demonstrated that MFXD has a good therapeutic effect on OVA-induced allergic inflammation in an AR rat model as manifested in reduced frequencies of sneezing and nasal scratching and in reduced serum levels of total IgE and HIS. In addition, MFXD regulates imbalance in Th1/Th2 cells caused by AR by simultaneously attenuating Th1 and Th2 responses, such as by reducing the serum levels of IFN-γ and IL-4 and mRNA expression levels of IFN-γ, IL-4, GATA-3, and STAT-6. This study provided valuable information on the immunoregulatory effect of MFXD for the treatment of AR in future clinical studies.

Dietary intake is associated with respiratory health outcomes and DNA methylation in children with asthma

BACKGROUND

Asthma is an increasingly common chronic disease among children, and data point toward a complex mechanism involving genetic, environmental and epigenetic factors. Epigenetic modifications such as DNA hypo- or hyper-methylation have been shown to occur in response to environmental exposures including dietary nutrients.

METHODS

Within the context of the asthma randomized trial of indoor wood smoke (ARTIS) study, we investigated relationships between diet, asthma health measures, and DNA methylation. Asthma health measures included a quality of life instrument, diurnal peak flow variability (dPFV) and forced expiratory volume in the first second (FEV₁). Dietary intake was assessed with a food frequency questionnaire. Methylation levels of LINE-1 repetitive element and two promoter CpG sites for interferon gamma (IFNγ, -186 and -54) from buccal cell DNA were measured using pyrosequencing assays.

RESULTS

Data were collected on 32 children with asthma living in western Montana who were recruited to the ARTIS study. Selenium and several methyl donor dietary nutrients were positively associated with the asthma quality of life measure. Intake of methyl donating nutrients including folate was positively associated LINE-1 methylation and negatively associated with IFNγ CpG-186. Higher levels of LINE-1 methylation were associated with greater dPFV.

CONCLUSION

We identified several nutrients that were associated with improved quality of life measures among children with asthma. The IFNγ promoter CpG site -186 but not -54 was associated with the intake of selected dietary nutrients. However, in this small population of children with asthma, the IFNγ promoter CpG sites were not associated with respiratory health measures so it remains unclear through which epigenetic mechanism these nutrients are impacting the quality of life measure. These findings add to the evidence that dietary nutrients, particularly foods containing methyl donors, may be important for epigenetic regulation as it pertains to the control of asthma. Trial registration ClincialTrials.gov NCT00807183. Registered 10 December 2008.

Mould-sensitized adults have lower Th2 cytokines and a higher prevalence of asthma than those sensitized to other aeroallergens

BACKGROUND

Evidence suggests that specific allergen sensitizations are associated with different allergic diseases which may reflect different underlying immune profiles. We aimed to examine the cytokine profiles of individuals sensitized to eight common aeroallergens.

METHODS

We used data from the Tasmanian Longitudinal Health Study a population-based cohort study of 45-year-olds. Serum cytokines (IL-4, IL-5, IL-6, IL-8, IL-10, TNF-α) were measured in 1157 subjects using the LINCOplex assays. Participants underwent skin prick testing for house dust mite, cat, grasses and moulds. Multivariable linear regression was used to compare serum cytokine levels between sensitized and nonatopic subjects.

RESULTS

The prevalence of allergic sensitization to any aeroallergen was 51% (95% CI 47-54). Being sensitized to any aeroallergen was strongly associated with current asthma (OR = 3.7, 95% CI 2.6-5.3), and being sensitized to any moulds was associated with a very high risk of current asthma (OR = 6.40, 95% CI 4.06-10.1). The geometric mean (GM) levels of Th2 cytokines (IL-4, IL-5 and IL-6) for adults sensitized to Cladosporium were significantly lower than the levels for nonatopic individuals (IL-4 ratio of GMs = 0.25, 95% CI 0.10-0.62, P = 0.003; IL-5 GM = 0.55, 95% CI 0.30-0.99, P = 0.05; and IL-6 GM = 0.50, 95% CI 0.24-1.07, P = 0.07). Individuals sensitized to other aeroallergens all showed elevated Th2 cytokine levels.

CONCLUSION

Our study is the first large population-based study to demonstrate reduced Th2 cytokines levels in people sensitized to mould. Underlying biological mechanisms driving allergic inflammatory responses in adults sensitized to moulds may differ from those sensitized to other aeroallergens. These findings suggest that it may be necessary to tailor treatments in individuals sensitized to moulds compared with other aeroallergens in order to optimize outcomes.

Significantly Higher Prevalence Rate of Asthma and Bipolar Disorder Co-Morbidity: A Meta-Analysis and Review Under PRISMA Guidelines

Asthma and bipolar disorder (BD) are 2 distinct diseases that share similar pathophysiology. This study aimed to determine their relationship thorough a meta-analysis of articles on their comorbidity rate. The aim of the study is to examine the overall prevalence rate of BD in asthmatic patients and of asthma in BD patients compared to healthy controls. Electronic research of PubMed and ClinicalTrials.gov was performed. Articles discussing the prevalence rate of BD in patients with/without asthma and the prevalence rate of asthma in those with/without BD, as well as clinical trials in humans and case-controlled trials or cohort studies, were all included. Case reports or series and nonclinical trials were excluded. Through a random-effects model, a meta-analysis of the results of 4 studies comparing the prevalence rate of BD in patients with/without asthma, and in 6 studies comparing the prevalence rate of asthma in subjects with/without BD were performed. There were significantly higher prevalence rates of BD in asthmatic patients than in healthy controls (P < 0.001) and of asthma in BD patients than in healthy controls (P < 0.001). Only the patient's mean age significantly modulated the odds ratio of the prevalence rate of asthma in BD patients (slope = 0.015, P < 0.001). Only 10 studies were included and most were cross-sectional studies. The possible confounding effect of medication on BD or asthma onset was not investigated. Any possible etiology of the comorbidity was also not determined. This meta-analysis highlights the importance of the significantly high comorbid rate of BD and asthma, and the positive association with age. Special attention must be given to the comorbidity of asthma and BD, especially in older patients.

The influence of atopy and asthma on immune responses in inner-city adults

Asthma in the inner‐city population is usually atopic in nature, and is associated with significant morbidity and mortality. However, the underlying immune abnormalities that underlie asthma in urban adults have not been well defined. We investigated the influence of atopy and asthma on cytokine responses of inner‐city adult women to define immune abnormalities associated with asthma and atopy. Blood samples were collected from 509 of 606 inner‐city women enrolled in the Urban Environment and Childhood Asthma (URECA) study. We tested for associations between atopy and asthma status and cytokine responses in peripheral blood mononuclear cells incubated ex vivo with a panel of innate and adaptive immune stimulants. Atopic subjects had heightened Th2 cytokine responses (IL‐4, IL‐5, IL‐13) to cockroach and dust mite antigens, tetanus toxoid, and phytohemagglutinin (P < 0.05 for all). Differences in cytokine responses were greatest in response to stimulation with cockroach and dust mite. In a multivariate analysis, atopy was broadly related to increased Th2‐like responses to all antigens and PHA, while asthma was only weakly related to mitogen‐induced IL‐4 and IL‐5 responses. There were few asthma or allergy‐related differences in responses to innate stimuli, including IFN‐α and IFN‐γ responses. In this inner‐city adult female population, atopy is associated with enhanced Th2 responses to allergens and other stimuli, and there was little or no additional signal attributable to asthma. In particular, these data indicate that altered systemic interferon and innate immune responses are not associated with allergies and/or asthma in inner‐city women.

Interleukin-10 and interleukin-5 balance in patients with active asthma, those in remission, and healthy controls

BACKGROUND

The immunological mechanisms of asthma remission remain unclear although several reports have suggested that balance between T helper (Th) 2 cytokines and regulatory cytokines is related.

OBJECTIVE

To study the balance between interleukin (IL) 10 and IL-5 in asthma clinical remission.

METHODS

We measured the numbers of IL-5 and IL-10 producing cells in peripheral blood mononuclear cells stimulated with mite antigen obtained from patients with active asthma (group A, n = 18), patients in clinical remission (group R, n = 15) and nonatopic healthy controls (group H, n = 14).

RESULTS

The numbers of IL-5 producing cells in groups A and R were significantly higher than in group H. The number of IL-5 producing cells was lower in group R than in group A, although the difference was not statistically significant. The number of IL-10 producing cells was higher in group R than in group A, although again the difference was not statistically significant. There was a significant difference in the number of IL-10 producing cells between groups A and H but not between groups R and H. The ratio of the number of IL-10 to IL-5 producing cells was highest in group H followed by groups R and A, and the differences were statistically significant for each pair of groups.

CONCLUSION

Our study suggests that the IL-10/IL-5 balance is related to clinical asthma. The balance differs between patients in clinical remission and healthy controls, suggesting that allergic inflammation may continue even after clinical asthma remission.

IFNG rs1861494 polymorphism is associated with IBD disease severity and functional changes in both IFNG methylation and protein secretion

BACKGROUND

Mucosal expression of interferon (IFN)-γ plays a pivotal role in the pathogenesis of inflammatory bowel disease (IBD) and IBD risk regions flank IFNG. The conserved IFNG rs1861494 T/C introduces a new CpG methylation site, is associated with disease severity and lack of therapeutic response in other infectious and immune-mediated disorders, and is in linkage disequilibrium with a ulcerative colitis (UC) disease severity region. It seems likely that CpG-altering single nucleotide polymorphisms modify methylation and gene expression. This study evaluated the association between rs1861494 and clinical, serologic, and methylation patterns in patients with IBD.

METHODS

Peripheral T cells of UC and Crohn's disease (CD) patients were genotyped for rs1861494 and analyzed for allele-specific and IFNG promoter methylation. Serum antineutrophil cytoplasmic autoantibodies and IFN-γ secretion were measured by enzyme-linked immunosorbent assay and nucleoprotein complex formation by electrophoretic mobility shift assay.

RESULTS

IFNG rs1861494 T allele carriage in patients with IBD was associated with enhanced secretion of IFN-γ. T allele carriage was associated in UC with high levels of antineutrophil cytoplasmic autoantibodies and faster progression to colectomy. In CD, it was associated with complicated disease involving a stricturing/penetrating phenotype. Likewise, IFNG rs1861494 displayed genotype-specific modulation of DNA methylation and transcription factor complex formation.

CONCLUSIONS

This study reports the first association of IFNG rs1861494 T allele with enhanced IFN-γ secretion and known IBD clinical parameters indicative of more aggressive disease and serological markers associated with treatment resistance to anti-tumor necrosis factor therapy in patients with IBD. These data may be useful prognostically as predictors of early response to anti-tumor necrosis factor therapy to identify patients with IBD for improved personalized therapeutics.

Analysis of Th1/Th2 response pattern for erythrodermic psoriasis

As one of the most serious types of psoriasis, pathogenesis of erythrodermic psoriasis (EP) is unclear so far. In this study, we aimed to detect the levels of Th1/Th2 cytokine-associated transcription factors and T-lymphocyte clone in peripheral blood mononuclear cells (PBMCs) derived from EP patients, and gene expression level of T-bet/GATA-3 in skin lesion. The potential role of Th1/Th2 reaction pattern played in the pathogenesis of EP was also discussed. Serum levels of IFN-γ, IL-2, IL-4 and IL-10 were quantified by ELISA among 16 EP patients, 20 psoriasis vulgaris (PV) patients and 15 healthy controls. The expression levels of T-bet/GATA-3 in the skin lesion and PBMCs were examined by real-time qPCR. The ratio of Th1/Th2 was measured by flow cytometry. The levels of IFN-γ, IL-2, IL-4 and IL-10 were higher in EP patients than in the healthy controls. The levels of IL-4 and IL-10 were 69.44±11.45 and 12.62±4.57 pg/mL, respectively, in EP patients, significantly higher than those in PV patients and healthy controls (P<0.05). Flow cytometry revealed the levels of both Th1 and Th2 in PBMCs from EP patients were higher than those in healthy controls, and the Th1/Th2 ratio was dramatically lower than in PV patients (P<0.01). The ratios of IFN-γ/IL-4 and T-bet/GATA-3 in EP patients were both less than 1.0, suggesting a reversal when compared with the other two groups. Our study indicated that the EP patients exerted a Th1/Th2 bidirectional response pattern, and the balance of Th cell subsets inclines to Th2, which might be one of the important mechanisms of EP pathogenesis.

Differentiating asthma phenotypes in young adults through polyclonal cytokine profiles

BACKGROUND

Recent research has emphasized the need to better discriminate asthma phenotypes and consider underlying mechanistic endotypes in epidemiologic and clinical studies. Although allergic asthma and nonallergic asthma are frequently combined into 1 disease category in observational research and clinical trials, few studies have investigated the extent to which these 2 separate phenotypes are associated with distinct cytokine immunologic profiles in a representative young adult population.

OBJECTIVE

To investigate the cytokine production-based endotypes underlying the clinical phenotypes of allergic and nonallergic asthma in a population-based birth cohort evaluated as young adults.

METHODS

Participants included 18- to 21-year-old members (n = 540) of a suburban Detroit birth cohort study, the Childhood Allergy Study. Phorbol myristate acetate-stimulated whole blood interleukin (IL)-4, IL-5, IL-10, IL-12, IL-13, IL-17A, IL-17F, IL-22, and interferon-γ secretory responses were analyzed for associations comparing participants with allergic vs nonallergic asthma phenotypes with those without asthma.

RESULTS

T-helper cell type (TH) 2-polarized responses, measured as higher mean IL-5 and IL-13 secretions and lower ratios of interferon-γ and IL-12 to 3 TH2 cytokines (IL-4, IL-5, or IL-13), were observed only in participants with allergic asthma. Nonallergic asthma was associated with TH1-polarized responses, including higher adjusted interferon-γ secretion compared with participants with allergic asthma and, surprisingly, those without asthma (odds ratio 2.5, confidence interval 1.2-5.1, P < .01).

CONCLUSION

As expected, young adults with a history of an allergic asthma phenotype exhibited a TH2-polarized cytokine response after polyclonal stimulation. However, TH1 polarization was observed in patients with a history of nonallergic asthma. Allergic and nonallergic asthma are associated with etiologically distinct immune endotypes, underscoring the importance of discriminating these endotypes in research analyses and clinical management.

Differential airway inflammatory responses in asthma exacerbations induced by respiratory syncytial virus and influenza virus a

BACKGROUND

Although respiratory viral infections cause acute exacerbations of asthma, the inflammatory responses vary depending on the causative virus. The purpose of this study was to compare the inflammatory responses in the airways of acute exacerbations of asthma induced by respiratory syncytial virus (RSV) and influenza A virus.

METHODS

Sputum induction was performed in asthmatic patients with acute exacerbations induced by RSV (n = 6), influenza A (n = 7), and non-upper respiratory infection (URI)-related factors (n = 8). Sputum concentrations of cysteinyl leukotrienes (cysLTs), TNF-α and IFN-γ were measured.

RESULTS

Sputum cysLTs were significantly higher in RSV-induced exacerbations than in influenza A- and non-URI-induced exacerbations. Sputum TNF-α was significantly higher in influenza A-induced exacerbations than in RSV- and non-URI-induced exacerbations. Sputum IFN-γ was significantly lower in RSV-induced exacerbations than in the others.

CONCLUSIONS

RSV and influenza A cause acute exacerbations and have different effects on airway inflammation in asthmatic patients. RSV significantly increased cysLTs, while influenza A significantly increased TNF-α in the airway. The underlying mechanism in virus-induced asthma might depend on the viral species.

Adult serum cytokine concentrations and the persistence of asthma

BACKGROUND

Cytokines play a pivotal role in regulating the development and persistence of the inflammatory process in asthma. Our aim was to investigate whether asthma persistence or remission is associated with a specific cytokine profile.

METHODS

The Tasmanian Longitudinal Health Study followed participants from 7 to 44 years of age. Serum concentrations of interleukin (IL)-4, IL-5, IL-6, IL-8, IL-10 and tumor necrosis factor-alpha (TNF-α) were measured at age 44 years. Participants were categorized into five phenotypes (early-onset noncurrent asthma, early-onset current asthma, late-onset noncurrent asthma and late-onset current asthma). Those who had never had asthma formed the reference group. Multivariable linear regression was used to compare serum cytokine concentrations between each phenotype and the reference group.

RESULTS

IL-10 concentrations were significantly lower in serum from the early-onset current asthma group than in the reference group (ratio of geometric means 0.58; 95% confidence interval 0.33-0.99; p = 0.048). IL-6 concentrations for the late-onset remitted group were also significantly lower than in the reference group (p = 0.009). The TNF-α concentrations were significantly lower for both early-and late-onset remitted asthma phenotypes when compared with the reference group. No associations were detected between serum concentrations of IL-4, IL-5 or IL-8 and these specific longitudinal asthma phenotypes.

CONCLUSION

Our findings suggest a possible role for deficient IL-10 responses in the persistence of early-onset asthma. Lower IL-6 and TNF-α concentrations in serum from those with remitted asthma suggest that these proinflammatory cytokines may be actively suppressed during asthma remission.

Clinical efficacy and laboratory improvement of bacillus calmette-guerin vaccination on adult atopic asthma: a cohort study

Background

Recent studies have shown that Bacillus Calmette-Guerin (BCG) vaccination is inversely related to asthma, a Th2 cell-associated with allergic disease, which BCG in humans induces Th1-cell immune responses and prevents airway remodeling.

Objective

To investigate whether thrice BCG vaccinations are clinically effective and could induce laboratory improvement compared with placebo on phase 1 (12 weeks) and single BCG vaccination on phase 2 of the study, then finding out whether the effect might last until 9 months after thrice vaccination and 9 months after single vaccination on adult atopic extrinsic asthma.

Methods

According to the Global Initiative for Asthma criteria, 40 mild to moderate persistent atopic asthma patients were randomly assigned in a double-blind fashion into groups that received intra-dermal injection of 0.1 mL of BCG (n = 20) or 0.1 mL of placebo (n = 20) on the first day. On the first phase, subjects on BCG vaccinations were given intradermal injections 3 times on the deltoid region every 4 weeks. On the second phase, at the 12th week, the placebo group was given BCG vaccination once, and this group became the single BCG group. The symptom score (SS) and drug score (DS), lung function, eosinophil blood count (EBC), total serum immunoglobulin E, interferon-γ (IFN-γ), interleukin 4, and transforming growth factor-β1 (TGF-β1) were examined on the first phase (before the treatment and at the 12th week) and on the second phase (on the sixth and ninth months after the third vaccination for thrice BCG group or after single BCG for control group) to monitor the efficacy.

Results

There were some improvements of asthma SS (P < 0.05) and DS (P < 0.05), forced expiratory volume in 1 second (P < 0.05), peak expiratory flow rate (P < 0.05), EBC (P > 0.05), IFN-γ (P < 0.05), and TGF-β1 (P < 0.05) on thrice BCG group compared with prevaccination and with placebo on the first phase and second phase of the study compared with single BCG (formerly placebo).

Conclusions

Based on the previous findings, we could confirm that thrice BCG vaccinations proved to be better than the placebo group and single vaccination. The efficacy of thrice BCG vaccinations on asthma was detected by the improvement of SS, DS, forced expiratory volume in 1 second, peak expiratory flow rate, EBC, IFN-γ, and TGF-β1 until 9 months from the last vaccination without any side effects.

Beneficial effects of sitostanol on the attenuated immune function in asthma patients: results of an in vitro approach

Background

In vitro and animal studies have suggested that plant sterols and stanols increase cytokine production by T-helper-1 cells. This may be beneficial for patient groups characterized by a T-helper-2 dominant immune response, e.g. asthma patients. (1) to evaluate whether sitostanol induces a T-helper-1 shift in peripheral blood mononuclear cells (PBMCs) from asthma patients, and (2) to unravel the role of regulatory T-cells in this respect.

Methodology/Principal Findings

PBMCs from 10 asthma patients and 10 healthy subjects were isolated and incubated with 1.2 µM sitostanol, while stimulated with 5 µg/ml PHA. Similar amounts of cholesterol were used to determine whether effects were specific for plant stanols or for sterols in general. Changes in cytokine production were measured using antibody arrays and ELISAs. Changes in regulatory T-cell population size were measured by flow cytometry, using intracellular Foxp3 staining. Sitostanol increased production of IFNγ by 6.5% and IL-2 by 6.0% compared to cholesterol (p<0.01). No changes in IL-4 and IL-13 were found. Interestingly, this effect was only present in PBMCs from asthma patients. The number of Foxp3+ cells tended to increase and their activity, measured by IL-10 production, increased after sitostanol treatment in PBMCs from asthma patients compared to controls by 32.3% (p = 0.077) and 13.3% (p<0.05), respectively.

Conclusions/Significance

Altogether, the sitostanol-induced Thelper-1 shift in PBMCs from asthma patients and the stimulating effects of sitostanol on Treg cell numbers and activity indicate a possible novel approach for plant stanol ester enriched functional foods in the amelioration of asthmatic symptoms. Functional effects, however, require further evaluation.

Local and systemic immunological parameters associated with remission of asthma symptoms in children

The immunological and clinical parameters that are associated with asthma remission are poorly understood. The cytokine and local mediator changes associated with the resolution of asthma symptoms were examined in three groups of subjects 12-18 years of age (n = 15 in each group): (a) continuing asthma group (CA) who had persistent symptoms since early childhood, (b) an age, sex and atopic status-matched group who had persistent symptoms in early childhood but in whom these had resolved (RA), and (c) a non-atopic, non-asthmatic control group. Clinical parameters, sputum cell counts, peripheral blood mononuclear cell (PBMC) cytokine production and activation marker expression were determined. All of the CA had methacholine airway hyperresponsiveness compared with only half of the RA subjects. The CA showed elevated numbers of eosinophils and increased ECP and IL-5 in sputum, which were not observed in the RA. PBMC cytokine studies revealed increased production of the type 1 cytokines IL-12, IFN-γ and TNF-α in the CA group compared with the RA group, under a range of activation conditions, however, the production of IL-4 and IL-5 were unchanged. These findings suggest that decreased type 1 cytokine expression as well as decreased eosinophilic inflammation is associated with the resolution of asthma symptoms.

Th2 responses in OVA-sensitized BALB/c mice are down-modulated by Mycobacterium bovis BCG treatment

Objective

This study aimed to determine whether Mycobacterium bovis Bacillus Calmette-Guérin (BCG) treatment can reverse an established allergic airway inflammation in a BALB/c mouse model of ovalbumin (OVA)-induced airway inflammation.

Methods

OVA sensitized BALB/c mice were challenged with aerosolized OVA on days 28 to 30, 34, 41 and 63. Mice were intranasal treated with BCG on days 35 and 42. Twenty-four hours after the last challenge, blood samples were collected to detect anti-OVA immunoglobulin isotypes, and bronchoalveolar lavage (BAL) was harvested for cell count. Additionally, lungs were collected for histological analysis, detection of the eosinophil peroxidase (EPO) activity and measurement of cytokines and CCL11. The expression of CTLA-4, Foxp3 and IL-10 was also determined in lung tissue by flow cytometry.

Results

BCG treatment was able to inhibit an established allergic Th2-response, by decreasing the allergen-induced eosinophilic inflammation, EPO activity, levels of CCL11 and IL-4, serum levels of IgE and IgG1. Mycobacteria treatment increased lung levels of IFN-γ, IL-10 and TGF-β, and expressions of Foxp3 and CTLA-4 in CD4⁺T cells. Additionally, an increased production of IL-10 by CD8⁺ T cells was observed, even though no detectable changes in CD4⁺IL-10⁺ was noticed.

Conclusion

BCG treatment inhibits features of allergic airway inflammation and the results suggest that the mechanism underlying the down-regulatory effects of BCG on OVA-induced airway inflammation appear to be associated with the induction of both Th1 and T regulatory immune responses.

Serum levels of interleukin-13 and interferon-gamma from adult patients with asthma in Mysore

Serum protein analysis for noninvasive quantification of airway inflammation in asthma is a promising research tool in the field of lung diseases. Cytokines are believed to have major role in inflammatory process of the airways of the lung. There is an imbalance between T-helper (Th)-2 cells, which secrete interleukin (IL)-4 and interleukin (IL)-13, and Th1 cells, which secrete interferon (IFN)-gamma in asthma. To test the hypothesis that serum IL-13 and IL-4 levels may be elevated whereas IFN-gamma would be decreased in this cohort of patients, a property that could make them possible candidate biomarkers in determining asthma occurrence and severity, we measured concentrations of IL-4, IL-13 and IFN-gamma in serum samples of 88 subjects (44 normal, 12 with mild asthma, 16 with moderate asthma, and 16 with severe asthma). Serum Levels of IL-4, IL-13, and IFN-gamma were determined by an enzyme-linked immune-sorbent assay (ELISA). Median serum level of IFN-gamma in asthmatic patients was 8.0 pg/ml, while it was 11.4 pg/ml in healthy controls. However, the difference was not significant. Among the different age groups in whom IFN-gamma was assessed, the highest median value in both cases and controls was observed in the age group of 31-40 years. The median serum level of IL-13 was 40.0 pg/ml in asthmatic patients and 58.25 pg/ml in healthy controls. The difference was not significant. On subgroup analysis, no significant difference of IFN-gamma and IL-13 between asthma of different severities was observed. The study also revealed nonsignificant difference of serum cytokines with the duration of asthma, number of allergens, and severity of sensitization. Normal serum levels of IFN-gamma and IL-13 in asthmatic patients suggest their neutral role in the inflammatory process; however, more studies are required to establish the effect of these cytokines in adulthood asthma in different ethnic populations.

Cytokine production by peripheral blood CD4+ and CD8+ T cells in atopic childhood asthma

There are conflicting studies on T cell cytokine production in childhood asthma. In this study intracellular cytokine expression of IL-2, IL-4, IL-10, IL-13, IFN-γ, and TNF-α in CD4⁺ and CD8⁺ T cells in children with atopic asthma were measured by flow cytometry. Results. A significant increase in the percentage of CD4⁺ and CD8⁺ T cells producing IL-4 and IL-13 and decrease in the percentage of CD4⁺ producing IFN-γ in asthmatic children was found. The percentage of CD4⁺/IL-13⁺ was significantly higher in severe asthma than in children with intermittent disease symptoms. Severity of asthma was associated with increased both serum IgE and frequencies of CD4⁺/IL-13⁺ T cells, as well as duration of disease. Moreover, a decrease in FEV₁, FEV₁/FVC was observed in relation to the severity of asthma. Changes in cytokine profile in CD8⁺ subpopulation didn't depend on the severity of the disease. Conclusions. Increased production of IL-4 and IL-13 in both CD4⁺ and CD8⁺ T cells accompanied by decreased IFN-γ expression in CD4⁺ T cells may be evidence that both lymphocyte subpopulations are implicated in the pathogenesis of asthma. Relationship of CD4⁺/IL-13⁺ T cells with disease activity suggests that this lymphocyte subset may have a prominent role in childhood asthma.

12/15-lipoxygenase is an interleukin-13 and interferon-γ counterregulated-mediator of allergic airway inflammation

Interleukin-13 and interferon-γ are important effectors of T-helper cells. Interleukin-13 increases expression of the arachidonic acid-metabolizing enzyme, 15-lipoxygenase-1, in a variety of cell types. 15-lipoxygenase-1 is dramatically elevated in the airways of subjects with asthma. Studies in animals indicate that 15-lipoxygenase-1 contributes to the development of allergic airway inflammation but is protective in some other forms of inflammation. We tested the hypothesis that the ability of interleukin-13 and interferon-γ to counterregulate allergic airway inflammation was potentially mediated by counterregulation of 12/15-lipoxygenase, the mouse ortholog of 15-lipoxygenase-1. The airways of mice were treated with interleukin-13 or interferon-γ one day prior to each of the four allergen exposures. Interleukin-13 augmented and interferon-γ inhibited allergic airway inflammation independently of systemic IgE and mucosal IgA responses but in association with counterregulation of 12/15-lipoxygenase. Interleukin-13 and interferon-γ counterregulate 12/15-lipoxygenase potentially contributing to the effects of these cytokines on allergic airway inflammation.

Clinical aspects of pediatric food allergy and failed oral immune tolerance

Food allergy seems to represent a new spectrum of disease that has elicited significant community concern and extended waiting lists for allergists and gastroenterologists alike. The apparent rise in prevalence of IgE-mediated food allergy (and associated risk of anaphylaxis) has been postulated to result from effects of a "modern lifestyle" but as yet clear environmental risk factors have not yet emerged. Family history seems to contribute to risk suggesting that gene-environment interactions will be important for identifying a subpopulation with increased susceptibility to any identified lifestyle effects. Non-IgE-mediated food allergy (including food-induced enteropathies and colitides, eosinophilic esophagitis, and Crohn's disease) with potentially similar environmental triggers resulting in diverse immune dysregulatory mechanisms. The evidence underpinning the putative rise in food allergy is discussed and potential mechanisms of disease explored. Clinical aspects of various food allergic conditions including non-IgE-mediated food allergy are outlined.

Eosinophil differentiation in the bone marrow is inhibited by T cell-derived IFN-gamma

To explore whether and how T cells can affect myelopoiesis, we investigated myeloid differentiation in a model for T cell-mediated immune activation. We found that CD70-transgenic (CD70TG) mice, which have elevated numbers of interferon-γ (IFN-γ)-producing effector T cells in the periphery and bone marrow, are almost devoid of eosinophilic granulocytes. Induction of allergic airway inflammation in these mice failed to induce eosinophilia as well as airway hyperresponsiveness. CD70TG mice also have strongly reduced numbers of eosinophil lineage-committed progenitors, whereas granulocyte/macrophage progenitors from these mice are unable to generate eosinophils in vitro. We found that granulocyte/macrophage progenitors express IFN-γR1 and that IFN-γ is sufficient to inhibit eosinophil differentiation of both murine and human progenitor cells in vitro. We demonstrate that inhibition of eosinophil development in CD70TG mice is IFN-γ-dependent and that T cell-derived IFN-γ is sufficient to inhibit eosinophil formation in vivo. Finally, we found that IFN-γ produced on anti-CD40 treatment and during viral infection can also suppress eosinophil formation in wild-type mice. These data demonstrate that IFN-γ inhibits the differentiation of myeloid progenitors to eosinophils, indicating that the adaptive immune system plays an important role in orchestrating the formation of the appropriate type of myeloid cells during immune activation.

The frequency of self-reported allergic diseases in patients with crimean-congo haemorrhagic fever

BACKGROUND

Crimean-Congo haemorrhagic fever (CCHF) is an acute, tick-borne viral disease. In temperate areas, CCHF cases occur between spring and early autumn when tick activity is high. This period is also the pollen season during which symptoms of allergic diseases are exacerbated. Viruses induce inflammatory and antiviral responses by binding to specific receptors on the surface of airway epithelial cells, resulting in activation of innate immune responses; release of mediators such as cytokines and chemokines; and recruitment of neutrophils and mononuclear cells to the area.

AIM

We aimed to evaluate the frequency of self-reported allergic diseases and the effect on CCHF severity.

METHOD

Between June and August 2008, a questionnaire was applied to 114 CCHF (+) patients and 122 healthy control subjects, 16 to 88 years old who attended the Infectious Diseases clinic and were hospitalised with CCHF suspected, by face to face interview including history of allergic rhinitis (AR), asthma symptoms and nonspecific bronchial reactivity, doctor diagnosed AR and/or asthma, and familial allergic diseases history.

RESULTS

According to PCR and/or enzyme-linked immunoassay (ELISA) results, 51.7% of patients (n=114) had CCHF. There was no significant relation between CCHF and history of AR, asthma symptoms and nonspecific bronchial reactivity, doctor diagnosed AR and/or asthma, and familial allergic diseases history. The severity of CCHF has not affected these parameters (p>.05). Of patients with positive CCHF test, 2.6% (n=3) and 3.5% (n=4) had doctor diagnosed AR and asthma, respectively.

CONCLUSION

Self-reported allergic diseases and CCHF are not related with each other.

A single nucleotide polymorphism (A --> G) in intron 3 of IFNgamma gene is associated with asthma

Interferon-gamma (IFNgamma) is located on chromosome 12, and a number of studies have detected very strong linkage signals around this gene and asthma. The aim of this study was to analyze the association of a (CA)n repeat in intron 1 and six single nucleotide polymorphisms (((rs2069705, T/C) (promoter)), ((rs1861494, A/G), (rs1861493, T/C), (rs2069718, C/T) (intron 3)), ((rs2069727, A/G) and (rs2069728, G/A) (3' untranslated region))) spanning the whole gene with asthma. We report here the association of rs1861494 A/G with atopic asthma in a case-control cohort (n=189 and n=270 cases and controls, respectively) (P=0.0006), which was replicated (P=0.006) in a family study (n=137) as well. Allele G was found to be negatively associated (odds ratio=0.50, 95% confidence interval, P=0.0006). A five-locus haplotype also showed significant association with asthma in the case-control (P=0.002) and the family studies (P=0.0004). In our three-locus sliding window haplotypic analysis, we found the (CA)n repeat, rs1861494 A/G and rs2069718 C/T to be of high priority (P=0.0003). Using electrophoretic mobility shift assay, we provide evidence that the alleles of rs1861494 A/G have differential affinity to bind to putative nuclear factor(s). In conclusion, we report for the first time association of rs1861494 A/G polymorphism with asthma, which may regulate the IFNgamma levels and, hence, modulate asthma pathogenesis.

Cytokine production from peripheral blood mononuclear cells of mite allergen-sensitized atopic adults stimulated with respiratory syncytial virus and mite allergen

BACKGROUND

The interaction between viral respiratory tract infection and allergen sensitization in allergic asthma is unclear. Respiratory syncytial virus (RSV) has attracted attention as an important lower respiratory pathogen during childhood, while recent evidence indicates that RSV is also an important lower respiratory pathogen for adults. Immunity against RSV differs between children and adults. Several reports suggest that RSV infection in children results in a Th2-skewed immune response. The purpose of the present study was to determine the effects of RSV infection in adults who had previously been sensitized with a common aeroallergen.

METHODS

Peripheral blood mononuclear cells (PBMCs) isolated from 9 mite-sensitized atopic subjects and 11 healthy nonatopic subjects were exposed to live or UV-inactivated RSV concomitant to incubation with or without mite allergen, and the subsequent production of cytokines - interleukin (IL)-5, interferon (IFN)-gamma, IL-10 and IL-12p70 - was measured.

RESULTS

Mite allergen significantly increased IL-5 production in atopic PBMCs. RSV infection significantly increased IFN-gamma production from healthy and atopic PBMCs; the levels of IFN-gamma were significantly higher for atopic PBMCs. Live RSV infection significantly attenuated IL-5 production from mite allergen-stimulated atopic PBMCs. UV-inactivated RSV, but not live RSV, significantly enhanced allergen-specific IL-10 production in atopic PBMCs. IL-12 could not be detected in the present study.

CONCLUSION

The present findings suggest that RSV infection did not simply enhance allergen-specific Th2-like response in atopic adults. Live RSV-induced IFN-gamma and RSV protein-induced IL-10 appear to play important roles in the regulation of allergic airway inflammation in atopic adults.

DNA methylation and the expression of IL-4 and IFN-gamma promoter genes in patients with bronchial asthma

Although CpG methylation is thought to be a negative regulator of gene transcription, its relationship with cytokine expression remains unclear. Interleukin (IL)-4 and interferon (IFN)-gamma are major cytokines that affect the differentiation of naïve CD4+ T lymphocytes into the Th1 and Th2 lineage. We used bisulfite deoxyribonucleic acid modification and sequencing to examine the relationship between CpG methylation and IL-4 and IFN-gamma gene expression before and after allergen stimulation in human CD4+ T lymphocytes from sensitized hosts. In naïve cells, the CpGs in the promoter regions were methylated largely in both the IL-4 and IFN-gamma genes. After Dermatophagoides pteronyssinus/Dermatophagoides farinae stimulation, the degree of unmethylation in the IL-4 gene increased in cells from patients with bronchial asthma. After phytohemagglutinin stimulation, the degree of unmethylation increased in cells from nonallergic control subjects. The concentration of IL-4 was strongly correlated with the degree of unmethylation in the patient group. These data suggest that CpGs located at -80 of the IL-4 gene and at -295, -186, and +122 of the IFN-gamma gene have regulatory activities important for cytokine expression. We conclude that the stimulation of CD4+ T lymphocytes causes considerable increases in the degree of unmethylation and that in sensitized hosts, the extent of unmethylation correlates with the concentration of IL-4.

Elevated allergen-induced IL-13 secretion predicts IgE elevation in children ages 2-5 years

It is unclear if early immune responses to allergens, specifically Th1 and Th2 cytokine production, predict later immune responses, including increased IgE levels. In a group of children (n = 151) with a parental history of allergy or asthma followed from ages 2 through 5 years, we examined IL-13, IL-4, and IFN-gamma secretion by peripheral blood mononuclear cells in response to phytohemagglutinin (PHA), and to dust mite (Der f 1), cockroach (Bla g 2), and cat (Fel d 1) allergens in relation to elevated IgE. Elevated IgE was defined either as a positive IgE-specific response to at least one allergen (dust mite, cockroach, cat, and ovalbumin) or as an elevated total IgE level above a specified cut-off value. In multivariate logistic regression models including 181 observations made between the age of 2 through 5 years and accounting for repeated measures, we found an association between increased IL-13 secretion in response to Der f 1 and elevated IgE (odds ratio [OR] = 1.21, 95% confidence interval [CI] = 1.09-1.34). Age did not modify this relationship. No association was found between allergen-induced IFN-gamma secretion and IgE production. Among the group of children with measurements made at age 4-5 (n = 70), IL-13 in response to Der f 1 (p = 0.046), and IL-4 in response to PHA (p = 0.04) were increased among children with elevated IgE. In a smaller subset of children with measurements made at both age 2-3 and age 4-5 (n = 36), IL-13 levels at age 2-3 were also significantly increased in response to Der f 1 (p = 0.01) and Fel d 1 (p = 0.002) among those with elevated IgE at age 4-5. In a group of children ages 2-5 years, there is an association between IL-13 and elevated IgE.

Can allergic diseases be prevented prenatally?

Allergic diseases continue to increase in prevalence, and now affect over a third of the population in many countries. There is evidence that the increase in such diseases has its origins in early life exposures. Pregnancy or early childhood may therefore be critical periods for preventing the onset of allergic disease, and prenatal interventions are an attractive possibility for a population-based preventive approach. Here we review the data suggesting that prenatal exposures are important in the development of allergic disease, and that interventions during this time might be effective in prevention. We find evidence from both animal and human studies that prenatal interventions can influence the future development of allergic disease. There are a number of mechanisms through which such interventions may act to prevent allergic sensitization. We conclude that prenatal interventions have the potential to reduce the burden of allergic disease, and merit continued investigation. Further research in this area may lead to significant public health initiatives.

Functional polymorphism in the suppressor of cytokine signaling 1 gene associated with adult asthma

Suppressor of cytokine signaling (SOCS) 1 is an essential physiologic regulator of the IFN-gamma signaling that is crucial to lead appropriate immune responses, and impaired IFN-gamma production is considered a hallmark of atopic diseases. Recent study has shown that SOCS1 is also crucial in attenuating type 1 IFN signaling and in limiting the host response to viral infection. Clinical and experimental evidence suggest an important role for respiratory viral infections in the development of asthma. To assess genetic functional variants of SOCS1 related to susceptibility and clinical phenotypes in adult asthma in a Japanese population, we conducted association and haplotype analyses of 462 subjects with adult asthma and 639 control subjects. After screening for polymorphisms, we identified a total of 13 variants and characterized the linkage disequilibrium (LD) mapping of the gene. Three variants were selected for genotyping with regard to the LD pattern, and we found a significant association between an SOCS1 promoter polymorphism -1478CA > del and adult asthma (P = 0.0063). The three-locus haplotype of SOCS1 using these three polymorphisms also showed a positive association with a haplotype T-C-del (-5388T, -3969C, and -1478 del; P = 0.0097). Furthermore, reporter gene analysis revealed that related promoter variant -1478 del enhanced the transcriptional level of SOCS1 in human lung epithelial cells, and induced higher levels of protein expression of SOCS1 and lower phosphorylation of STAT1 stimulated with IFN-beta. These findings suggest that the SOCS1 gene might be involved in the development of adult asthma through functional genetic polymorphism.

Cytokine and anti-cytokine therapy for asthma

Cytokines play a critical role in the pathogenesis of asthma. Asthma resolution may depend on the correction of dysregulated cytokine expression, which is a characteristic feature of this chronic inflammatory disease. It is, therefore, not surprising that attempts have been made to either block cytokines present at elevated levels or to substitute cytokines that are insufficiently expressed in asthma. In this article, the results of these studies are discussed, and the obtained insights regarding asthma pathogenesis and new treatment options are summarized.

Biologic therapies for the treatment of asthma

Asthma is a chronic disease of the airway whose pathogenesis involves the complex interplay between many cell types and inflammatory mediators. The mainstays of therapy, inhaled bronchodilators and corticosteroids, do not target the asthmatic airway specifically and therefore are associated with untoward side effects. Anti-IgE (omalizumab) is the only biologic therapy to have transitioned completely from bench to bedside. Other candidate therapies, such as those that alter the T-helper 1/T-helper 2 cytokine balance, interfere with inflammatory cell trafficking, or modify normal intracellular signaling cascades involved in inflammatory gene transcription, have had only limited success in human clinical trials. This article describes several potential novel biologic therapies that have been or could be investigated.

Cytokine production, activation marker, and skin homing receptor in children with atopic dermatitis and bronchial asthma

T cells are known to develop a critical role in the pathogenesis of atopic dermatitis (AD) and bronchial asthma. T cells involved in AD express the skin homing receptor CLA, but no lung homing receptor has been identified in bronchial asthma. We compared different cell markers and the cytokine production in T cells from children with AD or bronchial asthma. We studied the involvement of CLA+ and CLA- T-cell subpopulations in these diseases. We studied 20 children with acute AD lesions, 15 with mild persistent asthma, and 15 non-atopic controls. All patients were sensitized to house dust mite (DP) and evaluated during the acute phase. Total and specific IgE were measured by immunoassay and the expression of different cell markers and the cytokine production was analyzed by flow cytometry in peripheral blood mononuclear cells. Total IgE was significantly higher in AD children and IgE to DP in the asthmatic children. There was a significant increase in CD25+ CD4+ cells in asthmatic children and in HLA-DR+ CD4+ and HLA-DR+ CD8+ cells in AD. In the CD4+ subsets, there was an increase in IL-13, IL-5 and TNF-alpha in AD compared to controls, a decrease in IFN-gamma in asthmatic children compared to controls, and an increase in IL-13, IL5, IL2, TNF-alpha, and IFN-gamma in the AD compared to asthmatic children. Changes in cytokine production were mainly detected in CLA+ cells in AD and in CLA- cells in asthma. Differences exist in total and specific IgE, activation markers, and cytokine patterns between AD children and children with asthma, with the former expressing a Th2 pattern whereas in asthmatic children we only detected a decrease in IFN-gamma. Moreover, the subpopulations (CLA+ vs. CLA-) expressing these changes were different, indicating that the underlying mechanisms in the two diseases are not exactly the same.

Allergen challenge alters intracellular cytokine expression

The pathophysiology of asthma is complex and engages cascades of events in the cytokine network. We, therefore, investigated the impact of bronchial allergen challenge in humans on the cytokine profile of circulating lymphocytes. Peripheral blood samples from 10 patients with allergic asthma were collected before and 24 h after allergen provocation. Patients who mounted a late-phase reaction were designated dual responders opposite to single responders. Whole blood cells were stimulated by mitogen and intracellular interleukin (IL)-4 and interferon (IFN)-gamma were detected by flow cytometry. The allergen challenge induced a decrease in IL-4+CD4+ cells in the patients (P = 0.05), and a significant decrease (P < 0.05) in IFN-gamma+CD4+ cells was noted in single, but not dual, responders. In addition, there was a significant difference (P < 0.01) with respect to the changes in the IFN-gamma+CD4+ cells comparing dual and single responders. No corresponding changes were observed in CD8+ cells. The data suggest a possible on-going traffic of IFN-gamma and IL-4+CD4+ lymphocytes into the bronchial mucosa in relation to an allergen challenge and generate the hypothesis that a difference exists between single and dual responders in this respect. Because the CD4+IFN-gamma-producing cells have the capacity to downregulate the T-helper type 2 response, a reduced capacity in this aspect might contribute to the pathophysiology in dual responders.

Respiratory viral infections and asthma pathogenesis: a critical role for dendritic cells?

BACKGROUND

Respiratory viral infections can influence the course of asthma at different time points. Severe respiratory viral infections during early age are associated with a higher prevalence of asthma in later childhood. In established asthma, viral infections are a frequent cause of asthma exacerbation.

OBJECTIVES

The present review focuses on epidemiological and experimental animal data that can illuminate the mechanisms by which viral infections can lead to sensitization to antigen, and exacerbate ongoing allergic airway inflammation and focuses on the role played by dendritic cells (DCs).

RESULTS

In experimental rodent models of asthma, respiratory viral infection at the time of a first inhaled antigen exposure is described to induce Th2 sensitization and to enhance the allergic response to a second encounter with the same antigen. Virus infections can modulate airway dendritic cell function by upregulation of costimulatory molecule expression, enhanced recruitment, and by inducing an inflammatory environment, all leading to an enhanced antigen presentation and possibly changing the normal tolerogenic response to inhaled antigen into an immunogenic response. In established asthma, respiratory viral infections attract several inflammatory cells, alter receptor expression on airway smooth muscle and modulate neuroimmune mechanisms, possibly leading to exacerbation of disease.

CONCLUSIONS

Animal data suggest that the link between respiratory viral infections and increased asthma is causally related, the viral infection acting on the immune and structural cells to enhance antigen presentation and inflammatory cell recruitment.

The role of interferon-gamma on immune and allergic responses

Allergic diseases have been closely related to Th2 immune responses, which are characterized by high levels of interleukin (IL) IL-4, IL-5, IL-9 and IL-13. These cytokines orchestrate the recruitment and activation of different effector cells, such as eosinophils and mast cells. These cells along with Th2 cytokines are key players on the development of chronic allergic inflammatory disorders, usually characterized by airway hyperresponsiveness, reversible airway obstruction, and airway inflammation. Accumulating evidences have shown that altering cytokine-producing profile of Th2 cells by inducing Th1 responses may be protective against Th2-related diseases such as asthma and allergy. Interferon-gamma (IFN-gamma), the principal Th1 effector cytokine, has shown to be crucial for the resolution of allergic-related immunopathologies. In fact, reduced production of this cytokine has been correlated with severe asthma. In this review, we will discuss the role of IFN-gamma during the generation of immune responses and its influence on allergic inflammation models, emphasizing its biologic properties during the different aspects of allergic responses.

The increased prevalence of allergy and the hygiene hypothesis: missing immune deviation, reduced immune suppression, or both?

Allergic atopic disorders, such as rhinitis, asthma, and atopic dermatitis, are the result of a systemic inflammatory reaction triggered by type 2 T helper (Th2) cell-mediated immune responses against 'innocuous' antigens (allergens) of complex genetic and environmental origin. A number of epidemiological studies have suggested that the increase in the prevalence of allergic disorders that has occurred over the past few decades is attributable to a reduced microbial burden during childhood, as a consequence of Westernized lifestyle (the 'hygiene hypothesis'). However, the mechanisms by which the reduced exposure of children to pathogenic and nonpathogenic microbes results in enhanced responses of Th2 cells are still controversial. The initial interpretation proposed a missing immune deviation of allergen-specific responses from a Th2 to a type 1 Th (Th1) profile, as a result of the reduced production of interleukin-12 and interferons by natural immunity cells which are stimulated by bacterial products via their Toll-like receptors. More recently, the role of reduced activity of T regulatory cells has been emphasized. The epidemiological findings and the experimental evidence available so far suggest that both mechanisms may be involved. A better understanding of this question is important not only from a theoretical point of view, but also because of its therapeutic implications.

Associations of the IL12B promoter polymorphism in longitudinal data from asthmatic patients 7 to 42 years of age

BACKGROUND

The IL12B gene encodes the p40 chain of IL-12, a proinflammatory cytokine that antagonizes TH2 expression and hence may play a critical role in the pathogenesis of airway inflammation observed in asthma. A promoter polymorphism of the gene was recently shown to be associated with asthma severity in children but only in heterozygotes.

OBJECTIVE

The aim of the present study was to test the hypothesis that the IL12B promoter polymorphism is associated with asthma susceptibility, severity, and related phenotypes in a cohort with longitudinal phenotypic data, from childhood to adulthood.

METHODS

Four hundred one 7-year-old children (106 control children, 295 asthmatic children) and 83 10-year-old children with severe asthma were recruited from a 1957 birth cohort. Atopic status and respiratory functions were determined at ages 7, 10, 14, 21, 28, 35, and 42 years. At age 42 years, blood samples were taken from 244 individuals for genotyping and the determination of plasma IgE levels and PHA- and house dust mite-induced IFN-gamma responses. Genotyping was done by the PCR restriction fragment length polymorphism method, using Alu I, and confirmed in 10% of the samples by direct sequencing.

RESULTS

The IL12B genotypes were not associated with asthma susceptibility, severity, or atopy at ages 7 and 42 years. Total serum IgE levels at age 42 of men with at least one CTCTAA allele were higher than those homozygous for the GC allele (P = .042), whereas no difference was observed for women. At all ages, female subjects with at least 1 copy of the CTCTAA allele had lower mean percent predicted levels of FEV1 and FVC compared with those without this allele; these differences were significant at ages 10 and 14 years (P < .05) and in the asthmatic subgroup at age 7 years (P = .001).

CONCLUSIONS

In this long-term study of asthmatic subjects with comprehensive data on asthma severity, we found no evidence to support the presence of a heterozygote effect of the IL12B promoter polymorphism on the level of asthma in early childhood or adulthood. The polymorphism was also not associated with asthma susceptibility, but the CTCTAA allele may have been associated with elevated serum IgE levels in male subjects and reduced pulmonary function in female subjects in early childhood.

New concepts of cytokines in asthma: is the Th2/Th1 paradigm out the window?

Although asthma is clearly associated with a systemic propensity for allergic T helper type 2 (Th2) cell cytokine responses, independent local immune events appear to be responsible for the development of allergic airways inflammation. There is growing interest in how local immune networks interact with resident airway cell populations such as epithelial cells, which are now also recognized as key producers of cytokines, chemokines and growth factors. As well as their recognized role in airway remodelling, epithelial cells are now thought to have a role in initiating events. This review examines the role of cytokines produced by these and other cells in the development of asthma. It also highlights emerging concepts that the excessive and inappropriate immune responses seen in allergic disease may be related to dysfunction of various interleukin-10 producing regulatory cell populations.

Rhinovirus-induced interferon-gamma and airway responsiveness in asthma

The majority of asthma exacerbations are caused by respiratory infections, with rhinovirus (RV) being the most common virus. Recent evidence has suggested that decreased generation of IFN-gamma is associated with more severe colds and delayed elimination of virus. Whether the generation of IFN-gamma also has any relationship to general features of asthma severity has yet to be determined. To evaluate this hypothesis, peripheral blood mononuclear cells from 19 subjects with atopy and asthma were incubated with RV16 for 6 days to determine IFN-gamma and interleukin (IL)-5 production; these responses were then compared with measurements of airflow obstruction and airway responsiveness. RV16-induced IFN-gamma production correlated significantly with the methacholine PD (r = 0.50, p = 0.03), and the ratio of RV16-induced IFN-gamma:IL-5 correlated with % predicted FEV1 (r = 0.53, p = 0.02). In contrast, there were no significant associations between measures of asthma severity and RV-induced IL-5. These findings suggest that a cytokine imbalance with a deficient Th1 response to RV, but not a Th2 response, is associated with measures of asthma severity and support the concept that impaired antiviral responses may be associated with asthma severity.

Chitosan IFN-gamma-pDNA Nanoparticle (CIN) Therapy for Allergic Asthma

Background

Allergic subjects produce relatively low amounts of IFN-γ, a pleiotropic Th-1 cytokine that downregulates Th2-associated airway inflammation and hyperresponsiveness (AHR), the hallmarks of allergic asthma. Adenovirus-mediated IFN-γ gene transfer reduces AHR, Th2 cytokine levels and lung inflammation in mice, but its use would be limited by the frequency of gene delivery required; therefore, we tested chitosan/IFN-γ pDNA nanoparticles (CIN) for in situ production of IFN-γ and its in vivo effects.

Methods

CIN were administered to OVA-sensitized mice to investigate the possibility of using gene transfer to modulate ovalbumin (OVA)-induced inflammation and AHR.

Results

Mice treated with CIN exhibit significantly lower AHR to methacholine challenge and less lung histopathology. Production of IFN-γ is increased after CIN treatment while the Th2-cytokines, IL-4 and IL-5, and OVA-specific serum IgE are reduced compared to control mice. AHR and eosinophilia are also significantly reduced by CIN therapy administered therapeutically in mice with established asthma. CIN was found to inhibit epithelial inflammation within 6 hours of delivery by inducing apoptosis of goblet cells. Experiments performed on STAT4-defective mice do not show reduction in AHR with CIN treatment, thus implicating STAT4 signaling in the mechanism of CIN action.

Conclusion

These results demonstrate that mucosal CIN therapy can effectively reduce established allergen-induced airway inflammation and AHR.

Mechanisms of asthma

Airway inflammation is a key factor in the mechanisms of asthma. Articles published in the Journal of Allergy and Clinical Immunology this past year have highlighted the utility of investigative bronchoscopy with segmental antigen challenge and induced sputum analyses to evaluate features of airway inflammation in relationship to asthma severity. Peripheral blood cell generation of cytokines IFN-gamma (T(H)1) and IL-5 (T(H)2) was used to evaluate the relationship of the balance of T(H)1/T(H)2 cytokines to asthma persistence and severity in a 42-year, longitudinal study. Chemokines, including thymus and activation-regulated chemokine, are important to the regulation of inflammation and IgE synthesis. Their potential role in asthma has also been evaluated. Finally, albuterol (R)- and (S)-enantiomers may have distinct effects on airway relaxation and regulation of inflammation, suggesting the possibility that monoisomeric therapy has therapeutic advantages. The potential contribution of genetic factors and mechanisms to airway inflammation and remodeling also continues to be an area of intense investigation. During the past year a number of articles published in the Journal of Allergy and Clinical Immunology have identified and clarified potential genetic mechanisms in asthma. The contribution of genetics to asthma has been examined in a wide variety of studies, ranging from epidemiologic association and twin studies all the way to molecular analysis through microarray gene expression experiments.

Polyclonal and allergen-induced cytokine responses in children with elevated immunoglobulin E but no atopic disease

BACKGROUND

Reduced Th1 and elevated Th2 cytokine responses are considered to be a principal mechanism in the generation of the inflammation leading to the manifestations of atopic disease in the skin of atopic dermatitis and in the airways of asthma. If reduced Th1 and elevated Th2 responses are principal determinants of the manifestation of atopic disease it might be expected that subjects with established disease would exhibit differences in their cytokine profiles as compared with atopic patients without clinical disease.

OBJECTIVE

To determine whether asymptomatic atopic children exhibit a cytokine imbalance similar to that seen in patients with established atopic disease or if they behave like non-atopic controls. Cytokine responses in a group of children with elevated IgE but no clinical manifestations of disease, atopic children with established disease and non-atopic controls were compared.

METHODS

We examined allergen-induced (house dust mite, HDM, rye grass pollen and RYE) cytokine responses in parallel with polyclonal (staphylococcal enterotoxin B, SEB) cytokine responses in a group of children with elevated serum IgE levels without current or past evidence of atopic disease (median age 6.6 years) and compared these with a non-atopic control group (median age 6.5 years) and a group of children with atopic disease (median age 6.7 years).

RESULTS

Symptomatic atopic children had reduced SEB-induced IFN-gamma and increased SEB-induced IL-4 and IL-5 as compared with non-atopic controls. In contrast, SEB-induced IFN-gamma, IL-4 and IL-5 production in asymptomatic atopics was not significantly different from the non-atopic control subjects. Allergen-induced Th1 (IFN-gamma) and Th2 (IL-5 and IL-13) cytokine production was increased in both symptomatic atopics and asymptomatic atopics when compared with non-atopic controls.

CONCLUSION

The defect in polyclonally induced IFN-gamma production was associated with the clinical manifestation of atopic disease but not the atopic stateper se. This suggests that the global reduction in IFN-gamma is the key determinant of the development of overt atopic disease. In contrast, elevated allergen-induced Th2 cytokine responses in children related to the atopic state per se irrespective of the presence of clinical atopic disease.