Is asthma really due to a polarized T cell response toward a helper T cell type 2 phenotype?

Body Weight and Allergic Asthma: A Narrative Review

Obesity is a known risk factor for asthma development, progression, and exacerbation. Nevertheless, the underlying pathophysiological mechanisms explaining how obesity contributes to the development and progression of asthma have yet to be established. Here, we review human studies examining the associations between asthma and obesity, focusing on the literature from the past 10 years. Overall, current evidence suggests that while both asthma and obesity are complex diseases with significant heterogeneity, they both share various features of chronic inflammation. Furthermore, the interactions between asthma and obesity likely involve allergen-specific T helper type 2 (type 2) immune responses, as well as diverse non-type 2 inflammatory pathways. However, despite considerable progress, studies to date have not definitively elucidated the mechanisms that account for the observed association. A large-scale population-based study combined with translational immunological research, including targeted asthma therapies and pharmacological weight loss therapies, may be required to properly dissect the details of obesity-related asthma pathophysiology.

Identification of differences in CD4+ T-cell gene expression between people with asthma and healthy controls

Functional enrichment analysis of genome-wide association study (GWAS)-summary statistics has suggested that CD4+ T-cells play an important role in asthma pathogenesis. Despite this, CD4+ T-cells are under-represented in asthma transcriptome studies. To fill the gap, 3'-RNA-Seq was used to generate gene expression data on CD4+ T-cells (isolated within 2 h from collection) from peripheral blood from participants with well-controlled asthma (n = 32) and healthy controls (n = 11). Weighted Gene Co-expression Network Analysis (WGCNA) was used to identify sets of co-expressed genes (modules) associated with the asthma phenotype. We identified three modules associated with asthma, which are strongly enriched for GWAS-identified asthma genes, antigen processing/presentation and immune response to viral infections. Through integration of publicly available eQTL and GWAS summary statistics (colocalisation), and protein-protein interaction (PPI) data, we identified PTPRC, a potential druggable target, as a putative master regulator of the asthma gene-expression profiles. Using a co-expression network approach, with integration of external genetic and PPI data, we showed that CD4+ T-cells from peripheral blood from asthmatics have different expression profiles, albeit small in magnitude, compared to healthy controls, for sets of genes involved in immune response to viral infections (upregulated) and antigen processing/presentation (downregulated).

Phaeanthus vietnamensis Ban Ameliorates Lower Airway Inflammation in Experimental Asthmatic Mouse Model via Nrf2/HO-1 and MAPK Signaling Pathway

Asthma is a chronic airway inflammatory disease listed as one of the top global health problems. Phaeanthus vietnamensis BÂN is a well-known medicinal plant in Vietnam with its anti-oxidant, anti-microbial, anti-inflammatory potential, and gastro-protective properties. However, there is no study about P. vietnamensis extract (PVE) on asthma disease. Here, an OVA-induced asthma mouse model was established to evaluate the anti-inflammatory and anti-asthmatic effects and possible mechanisms of PVE. BALB/c mice were sensitized by injecting 50 μg OVA into the peritoneal and challenged by nebulization with 5% OVA. Mice were orally administered various doses of PVE once daily (50, 100, 200 mg/kg) or dexamethasone (Dex; 2.5 mg/kg) or Saline 1 h before the OVA challenge. The cell infiltrated in the bronchoalveolar lavage fluid (BALF) was analyzed; levels of OVA-specific immunoglobulins in serum, cytokines, and transcription factors in the BALF were measured, and lung histopathology was evaluated. PVE, especially PVE 200mg/kg dose, could improve asthma exacerbation by balancing the Th1/Th2 ratio, reducing inflammatory cells in BALF, depressing serum anti-specific OVA IgE, anti-specific OVA IgG1, histamine levels, and retrieving lung histology. Moreover, the PVE treatment group significantly increased the expressions of antioxidant enzymes Nrf2 and HO-1 in the lung tissue and the level of those antioxidant enzymes in the BALF, decreasing the oxidative stress marker MDA level in the BALF, leading to the relieving the activation of MAPK signaling in asthmatic condition. The present study demonstrated that Phaeanthus vietnamensis BÂN, traditionally used in Vietnam as a medicinal plant, may be used as an efficacious agent for treating asthmatic disease.

Clinical effects and immune modulation of biologics in asthma

Asthma is considered a syndrome composed of heterogeneous disorders involving complex chronic airway inflammation. Patients with severe asthma, prolonged symptoms, and frequent asthma exacerbations, despite high doses of inhaled corticosteroids, may benefit from treatment with biologics. Four types of biologics are available for severe asthma, including an anti-immunoglobulin E (IgE) antibody (omalizumab), anti-interleukin (IL)-5 antibody (mepolizumab and reslizumab), anti-IL-5 receptor α antibody (benralizumab), and anti-IL-4 receptor α antibody (dupilumab). Biologics for patients with severe asthma demonstrate high therapeutic efficacy and provide significant clinical benefits, including the prevention of asthma exacerbations, alleviation of symptoms, improvement in the quality of life and respiratory function, and reduction in frequencies of hospitalization and emergency outpatient visits. This review provides an overview of the modulation of immunological features by each of the four established biologics in patients with severe allergic asthma. Given the extensive immunomodulatory effects of biologics, further analyses of their precise effects on the human immune system are warranted.

Circulating MicroRNA: Incident Asthma Prediction and Vitamin D Effect Modification

Of children with recurrent wheezing in early childhood, approximately half go on to develop asthma. MicroRNAs have been described as excellent non-invasive biomarkers due to their prognostic utility. We hypothesized that circulating microRNAs can predict incident asthma and that that prediction might be modified by vitamin D. We selected 75 participants with recurrent wheezing at 3 years old from the Vitamin D Antenatal Asthma Reduction Trial (VDAART). Plasma samples were collected at age 3 and sequenced for small RNA-Seq. The read counts were normalized and filtered by depth and coverage. Logistic regression was employed to associate miRNAs at age 3 with asthma status at age 5. While the overall effect of miRNA on asthma occurrence was weak, we identified 38 miRNAs with a significant interaction effect with vitamin D and 32 miRNAs with a significant main effect in the high vitamin D treatment group in VDAART. We validated the VDAART results in Project Viva for both the main effect and interaction effect. Meta-analysis was performed on both cohorts to obtain the combined effect and a logistic regression model was used to predict incident asthma at age 7 in Project Viva. Of the 23 overlapped miRNAs in the stratified and interaction analysis above, 9 miRNAs were replicated in Project Viva with strong effect size and remained in the meta-analysis of the two populations. The target genes of the 9 miRNAs were enriched for asthma-related Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathways. Using logistic regression, microRNA hsa-miR-574-5p had a good prognostic ability for incident asthma prognosis with an area under the receiver operating characteristic (AUROC) of 0.83. In conclusion, miRNAs appear to be good biomarkers of incident asthma, but only when vitamin D level is considered.

T helper 2-driven immune dysfunction in chronic arsenic-exposed individuals and its link to the features of allergic asthma

Limited information is available regarding the effects of arsenic exposure on immune function. We have recently reported that chronic exposure to As was associated asthma, as determined by spirometry and respiratory symptoms. Because T helper 2 (Th2)-driven immune responses are implicated in the pathogenesis of allergic diseases, including asthma, we studied the associations of serum Th1 and Th2 mediators with the As exposure markers and the features of asthma among individuals exposed to As. A total of 553 blood samples were selected from the same study subjects recruited in our previous asthma study. Serum levels of Th1 and Th2 cytokines were analyzed by immunoassay. Subjects' arsenic exposure levels (drinking water, hair and nail arsenic concentrations) were determined by inductively coupled plasma mass spectroscopy. Arsenic exposure levels of the subjects showed significant positive associations with serum Th2-mediators- interleukin (IL)-4, IL-5, IL-13, and eotaxin without any significant changes in Th1 mediators- interferon-γ and tumor necrosis factor-α. The ratios of Th2 to Th1 mediators were significantly increased with increasing exposure to As. Notably, most of the Th2 mediators were positively associated with serum levels of total immunoglobulin E and eotaxin. The serum levels of Th2 mediators were significantly higher in the subjects with asthma than those without asthma. The results of our study suggest that the exacerbated Th2-driven immune responses are involved in the increased susceptibility to allergic asthma among individuals chronically exposed to As.

Early-life exposure to air pollution and childhood allergic diseases: an update on the link and its implications

INTRODUCTION

Although mounting evidence has linked environmental factors with childhood allergies, some specific key issues still remain unclear: what is the main environmental factor? what is the critical timing window? And whether these contribute to the development of disease?

AREAS COVERED

This selective review summarizes recent epidemiological studies on the association between early-life exposure to indoor/outdoor air pollution and childhood allergic diseases. A literature search was conducted in the PubMed and Web of Science for peer-reviewed articles published until April 2020. Exposure to the traffic-related air pollutant, NO₂, exposure during pregnancy and early postnatal periods is found to be associated with childhood allergies, and exposure during different trimesters causes different allergic diseases. However, exposure to classical air pollutants (PM₁₀ and SO₂) also contributes to childhood allergy in developing countries. In addition, early-life exposure to indoor renovation and mold/dampness significantly increases the risk of allergy in children. A synergistic effect between indoor and outdoor air pollution is found in the development of allergic diseases.

EXPERT OPINION

Early-life exposure to outdoor air pollution and indoor environmental factors plays an important role in the development of childhood allergic diseases, and the synergy between indoor and outdoor exposures increases allergy risk. The available findings support the hypothesis of the 'fetal origins of childhood allergy,' with new implications for the effective control and early prevention of childhood allergies.

The Identification of Allergen-Derived T Cell Epitopes

Type I allergy is a disease primarily mediated by immunoglobulin E (IgE) and T helper type 2 (Th2) cells. The role of Th2 and other T cell subsets in the pathology of allergic disease as well as induction of tolerance has become an area of intense research over the last decades. Studying allergen-specific T cells to gain a better understanding of their contribution to allergic pathology and how they are modulated by allergen-specific immunotherapy requires knowledge of the allergens targeted by these cells. Identification of T cell epitopes in allergy can be achieved by a variety of methods. In this chapter, we will focus on a technique named FluoroSpot, which relies on the detection of cytokines secreted by T cells in response to stimulation with an antigen (allergen), such as timothy grass (TG) extract or an allergen-derived peptide, for which the cell is specific. We will describe how to overcome the challenge of detecting rare, TG-specific, T cells that occur at low frequency in the blood by using an in vitro expansion culture and subsequent mapping of the precise T cell epitope using FluoroSpot.

The Interactive Roles of Lipopolysaccharides and dsRNA/Viruses on Respiratory Epithelial Cells and Dendritic Cells in Allergic Respiratory Disorders: The Hygiene Hypothesis

The original hygiene hypothesis declares "more infections in early childhood protect against later atopy". According to the hygiene hypothesis, the increased incidence of allergic disorders in developed countries is explained by the decrease of infections. Epithelial cells and dendritic cells play key roles in bridging the innate and adaptive immune systems. Among the various pattern-recognition receptor systems of epithelial cells and dendritic cells, including toll-like receptors (TLRs), nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) and others, TLRs are the key systems of immune response regulation. In humans, TLRs consist of TLR1 to TLR10. They regulate cellular responses through engagement with TLR ligands, e.g., lipopolysaccharides (LPS) acts through TLR4 and dsRNA acts through TLR3, but there are certain common components between these two TLR pathways. dsRNA activates epithelial cells and dendritic cells in different directions, resulting in allergy-related Th2-skewing tendency in epithelial cells, and Th1-skewing tendency in dendritic cells. The Th2-skewing effect by stimulation of dsRNA on epithelial cells could be suppressed by the presence of LPS above some threshold. When LPS level decreases, the Th2-skewing effect increases. It may be via these interrelated networks and related factors that LPS modifies the allergic responses and provides a plausible mechanism of the hygiene hypothesis. Several hygiene hypothesis-related phenomena, seemingly conflicting, are also discussed in this review, along with their proposed mechanisms.

Dosha phenotype specific Ayurveda intervention ameliorates asthma symptoms through cytokine modulations: Results of whole system clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

Over the past few decades, there have been significant scientific advances leading to improved understanding of asthma as a disease and treatment providing immediate relief. However, prevention of recurrent attacks, exacerbations and disease cure remains a challenge. Ayurveda refers to bronchial asthma as Tamaka Swasa and it is well explained in Charaka Samhita. Management of asthma in Ayurveda includes removal of vitiated Kapha through Shodhana, Shamana procedures, herbal and herbomineral formulations in addition to advising a healthy lifestyle and diet. Several clinical trials on Ayurvedic formulations for treatment of asthma are reported, however, whole system management of asthma has rarely been studied in the manner in which it is actually being practiced. Ayurveda therapeutics provides Dosha specific approaches, which needs biological investigation.

AIM OF THE STUDY

The objective of our study was to investigate lung functions and cytokine changes in Asthmatic individuals in response to Ayurvedic intervention.

METHODS

The study design was approved by the Institutional Ethics Committee of Tilak Ayurveda Mahavidyalaya (TAMV) & Sheth Tarachand Ramnath Charitable Ayurveda Hospital and followed guidelines of the Declaration of Helsinki and Tokyo for humans. It was conducted as a whole system individualized pragmatic clinical trial and written consent of patients was collected before enrollment. One hundred and fifteen patients with mild-to-moderate asthma were divided into 2 sub-groups depending on their disease subsets and administered phenotype specific ayurvedic interventions. Seventy six asthma patients completed the treatment. Serum IgE levels, blood eosinophil counts, spirometry and blood cytokine levels were measured before the start of treatment and six months at the end of treatment. Age and sex matched healthy participants (n=69) were recruited in the study for comparison of cytokines levels.

RESULTS

Significant improvements in FEV1(% predicted) (p<0.0001) and FVC (% predicted) (p=0.0001) was observed in asthmatic patients who underwent Ayurvedic treatment. Circulating levels of IgE (p<0.03) and eosinophil numbers (p=0.001) reduced significantly in the asthmatics after Ayurvedic treatment. This was associated with significant reduction in levels of circulating cytokines. Levels of Th2, Th1 and inflammatory cytokines in the peripheral blood were higher than healthy control participants at baseline (p values <0.0001) and reduced significantly after ayurvedic intervention.

CONCLUSION

This proof of concept study highlights the potential benefits and possible mechanism of Ayurvedic interventions in patients with mild-to-moderate asthma. The interventions significantly reduced IgE and eosinophil count, also improved lung function and reduced levels of circulating Th2 cytokines.

Aggravation of Allergic Airway Inflammation by Cigarette Smoke in Mice Is CD44-Dependent

Background

Although epidemiological studies reveal that cigarette smoke (CS) facilitates the development and exacerbation of allergic asthma, these studies offer limited information on the mechanisms involved. The transmembrane glycoprotein CD44 is involved in cell adhesion and acts as a receptor for hyaluronic acid and osteopontin. We aimed to investigate the role of CD44 in a murine model of CS-facilitated allergic airway inflammation.

Methods

Wild type (WT) and CD44 knock-out (KO) mice were exposed simultaneously to house dust mite (HDM) extract and CS. Inflammatory cells, hyaluronic acid (HA) and osteopontin (OPN) levels were measured in bronchoalveolar lavage fluid (BALF). Proinflammatory mediators, goblet cell metaplasia and peribronchial eosinophilia were assessed in lung tissue. T-helper (Th) 1, Th2 and Th17 cytokine production was evaluated in mediastinal lymph node cultures.

Results

In WT mice, combined HDM/CS exposure increased the number of inflammatory cells and the levels of HA and OPN in BALF and Th2 cytokine production in mediastinal lymph nodes compared to control groups exposed to phosphate buffered saline (PBS)/CS, HDM/Air or PBS/Air. Furthermore, HDM/CS exposure significantly increased goblet cell metaplasia, peribronchial eosinophilia and inflammatory mediators in the lung. CD44 KO mice exposed to HDM/CS had significantly fewer inflammatory cells in BALF, an attenuated Th2 cytokine production, as well as decreased goblet cells and peribronchial eosinophils compared to WT mice. In contrast, the levels of inflammatory mediators were similar or higher than in WT mice.

Conclusion

We demonstrate for the first time that the aggravation of pulmonary inflammation upon combined exposure to allergen and an environmental pollutant is CD44-dependent. Data from this murine model of concomitant exposure to CS and HDM might be of importance for smoking allergic asthmatics.

The respiratory microbiota during health and disease: a paediatric perspective

Recent studies investigating the relationship between the microbiota and disease are demonstrating novel concepts that could significantly alter the way we treat disease and promote health in the future. It is suggested that the microbiota acquired during childhood may shape the microbial community and affect immunological responses for later life, and could therefore be important in the susceptibility towards disease. Several diseases, including asthma, pneumonia, and otitis media, are associated with changes in composition and diversity of the respiratory microbiota. This review summarises current literature, focusing on the composition and development of the respiratory microbiota in children and its relationship with respiratory diseases.

Early life exposure to ambient air pollution and childhood asthma in China

BACKGROUND

Early life is suggested to be a critical time in determining subsequent asthma development, but the extent to which the effect of early-life exposure to ambient air pollution on childhood asthma is unclear.

OBJECTIVES

We investigated doctor-diagnosed asthma in preschool children due to exposure to ambient air pollution in utero and during the first year of life.

METHODS

In total 2490 children aged 3-6 years participated in a questionnaire study regarding doctor-diagnosed asthma between September 2011 and January 2012 in China. Children's exposure to critical air pollutants, sulfur dioxide (SO2) as proxy of industrial air pollution, nitrogen dioxide (NO2) as proxy of traffic pollution, and particulate matter≤10µm in diameter (PM10) as a mixture, was estimated from the concentrations measured at the ambient air quality monitoring stations by using an inverse distance weighted (IDW) method. Logistic regression analysis was employed to determine the relationship between early-life exposure and childhood asthma in terms of odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Association between early-life exposure to air pollutants and childhood asthma was observed. SO2 and NO2 had significant associations with adjusted OR (95% CI) of 1.45 (1.02-2.07) and 1.74 (1.15-2.62) in utero and 1.62 (1.01-2.60) and 1.90 (1.20-3.00) during the first year for per 50 µg/m(3) and 15 µg/m(3) increase respectively. Exposure to the combined high level of SO2 and NO2 in China significantly elevated the asthmatic risk with adjusted OR (95% CI) of 1.76 (1.18-2.64) in utero and 1.85 (1.22-2.79) during the first year compared to the low level exposure. The associations were higher for males and the younger children aged 3-4 than females and the older children aged 5-6.

CONCLUSIONS

Early-life exposure to ambient air pollution is associated with childhood asthma during which the level and source of air pollution play important roles. The high level and nature of combined industrial and traffic air pollution in China may contribute to the recent rapid increase of childhood asthma.

The expression of a novel anti-inflammatory cytokine IL-35 and its possible significance in childhood asthma

Interleukin-35 (IL-35) is a novel anti-inflammatory cytokine and has been shown to play an important role in maintaining immune homeostasis. However, the effect of IL-35 on human asthma remains unclear. The present study is to investigate the expression and significance of IL-35 in childhood asthma. Forty-one asthmatic children and forty-two healthy controls were recruited in Qilu Children's Hospital of Shandong University. Serum total immunoglobulin E level was measured by radioimmunosorbent test. Peripheral blood eosinophils were counted using BC-5800 Automatic Blood Cell Analyzer. IL-35 mRNA in peripheral blood mononuclear cells was detected by quantitative real-time polymerase chain reaction. Serum IL-35, IL-4 and interferon-γ levels were measured using enzyme-linked immunosorbent assay. The correlations among the above indexes were also analyzed using Pearson's method. Our results showed that serum total IgE, eosinophil count and serum IL-4 were significantly increased in asthmatic children compared with control children, and serum IFN-γ level in asthmatic patients was obviously lower than that in healthy controls. We also found that there was an obviously positive correlation between serum IgE and IL-4 levels in asthmatic patients. In addition, significantly negative correlation was found between serum total IgE and IFN-γ levels. More importantly, we found that the expression of IL-35 mRNA and protein was both down-regulated in asthmatic children, and serum IL-35 level was inversely related to serum IL-4 level. Moreover, significantly positive correlation was also found between serum IL-35 and IFN-γ levels. The results suggest that the decreased expression of IL-35 could be involved in the pathogenesis of childhood asthma.

Hygiene hypothesis and periodontitis--a possible association

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

Psychosocial factors and behavioral medicine interventions in asthma

OBJECTIVE

This review examines the evidence for psychosocial influences in asthma and behavioral medicine approaches to its treatment.

METHOD

We conducted a systematic review of the literature on psychosocial influences and the evidence for behavioral interventions in asthma with a focus on research in the past 10 years and clinical trials. Additional attention was directed at promising new developments in the field.

RESULTS

Psychosocial factors can influence the pathogenesis and pathophysiology of asthma, either directly through autonomic, endocrine, immunological, and central nervous system mechanisms or indirectly through lifestyle factors, health behaviors, illness cognitions, and disease management, including medication adherence and trigger avoidance. The recent decade has witnessed surging interest in behavioral interventions that target the various pathways of influence. Among these, self-management training, breathing training, and exercise or physical activation programs have proved particularly useful, whereas other essential or promising interventions, such as smoking cessation, dietary programs, perception and biofeedback training, and suggestive or expressive psychotherapy, require further, more rigorous evaluation. Given the high comorbidity with anxiety and mood disorders, further evaluation of illness-specific cognitive behavior therapy is of particular importance. Progress has also been made in devising community-based and culturally tailored intervention programs.

CONCLUSION

In concert with an essential medication treatment, behavioral medicine treatment of asthma is moving closer toward an integrated biopsychosocial approach to disease management.

Changing prevalence of allergic diseases in the Asia-pacific region

Asia-Pacific is one of the most densely populated regions of the world and is experiencing rapid economic changes and urbanization. Environmental pollution is a significant problem associated with the rapid modernization of many cities in South Asia. It is not surprising that the prevalences of asthma and allergies are increasing rapidly, although the underlying reasons remain largely unknown. Many studies from this region have documented the changing prevalence of allergic diseases in various parts of the world. However, the methodologies used were neither standardized nor validated, making the results difficult to evaluate. The International Study of Asthma and Allergies in Childhood (ISAAC) has provided a global epidemiology map of asthma and allergic diseases, as well as the trend of changes in the prevalence of these diseases. Allergic sensitization is extremely common in many Asian communities. However, the prevalence of allergic diseases remains relatively rare. The rapid urbanization in the region, which increases environmental pollution and can affect the rural environment, will likely increase the prevalence of asthma and allergies in Asia.

The use of biological agents for the treatment of fungal asthma and allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a virulent manifestation of the Th2 asthma endotype that includes asthma with fungal sensitization, raising the feasibility of biological therapies targeting Th2 pathway molecules or cells. The first molecule amenable to clinical intervention with a biological was IgE. Omalizumab, a humanized monoclonal antibody (Mab), targets the same epitope on the IgE CH3 region that binds to and crosslinks high-affinity receptors on mast cells and basophils, thereby initiating the allergic inflammatory cascade. Omalizumab is licensed for allergic asthma and has been beneficial in uncontrolled studies of ABPA, reducing exacerbations and steroid requirements. Trials of several Mabs directed against the Th2 cytokine IL-5 show clinical benefit in patients with a severe refractory eosinophilic asthma phenotype, while a Mab against IL-13 is effective in asthma patients with a Th2-high endotype. Immunodulation is also feasible with small molecule biologicals, such as antisense oligodeoxynucleotides and cholecalciferol. Controlled trials of Th2-inhibiting biologicals in patients with ABPA and severe asthma with fungal sensitization appear warranted.

The effect of academic exam stress on mucosal and cellular airway immune markers among healthy and allergic individuals

Research suggests that psychological stress can exacerbate allergies, but relatively little is known about the effect of stress on mucosal immune processes central to allergic pathophysiology. In this study, we quantified vascular endothelial growth factor (VEGF), interferon gamma (IFN-γ), and interleukin-4 concentrations in saliva (S) and exhaled breath condensate (EBC) during final exams and at midsemester among 23 healthy and 21 allergic rhinitis individuals. IFN-γs decreased during exams for both groups while VEGF(EBC) increased (and increases in VEGFs were a trend). Elevated negative affect ratings predicted higher VEGF(EBC) in allergic individuals. IFN-γ(EBC) increased in healthy individuals early during exams and then decreased, while allergic individuals showed a decrease in IFN-γ(EBC) throughout final exams. These findings suggest that psychological stress can suppress cellular immune function among allergic individuals while increasing VEGF.

Is the asthma epidemic still ascending?

Asthma is a phenotypically heterogeneous disorder of multifactorial origins that affects 300 million people suffering from asthma and more than 250,000 asthma-related deaths each year. Although treatment for asthma has improved, its prevalence continues to increase, particularly in low and middle income countries, or in some ethnic groups in which prevalence was previously low. Observed spatio-temporal variations in the increased prevalence of asthma depend on exposure to environmental factors. Recently, several arguments are also in favor of the involvement of host susceptibility and stress in the observed increase of asthma prevalence. Further investigations are warranted to better understand mechanisms underlying asthma increase or stagnation.

Airway IFN-γ production during RSV bronchiolitis is associated with eosinophilic inflammation

STUDY OBJECTIVE

This study was designed to investigate the possible role of IFN-γ in eosinophil degranulation that occurs during respiratory syncytial virus (RSV) bronchiolitis.

METHODS

Sixty-seven infants, 2-24 months old and hospitalized with their first episode of acute RSV bronchiolitis, were selected for this study. Eosinophil-active cytokine and chemokine profiles in nasal lavage supernatants taken within the first 48 h of admission were determined by a multiplex bead array system (Luminex). Comparisons were made with control (Control group) subjects (n = 20).

RESULTS

Nasal IFN-γ levels were significantly higher (P < 0.0001) in RSV bronchiolitis (median = 4.4 pg/ml) infants compared to controls (0.0 pg/ml). IFN-γ levels correlated significantly with the levels of nasal eotaxin (r = 0.566, P < 0.0001), RANTES (r = 0.627, P < 0.0001), GM-CSF (r = 0.849, P < 0.0001), and EDN (r = 0.693, P < 0.001). Nasal interleukin (IL)-4, IL-5, and IL-13 were below sensitivity levels in most RSV bronchiolitis and control subjects.

CONCLUSION

These results suggest that IFN-γ may play an important role in eosinophilic inflammation in RSV bronchiolitis.

Delayed-type asthmatic response to bronchial challenge with allergen, I: clinical features

BACKGROUND

Patients with allergic asthma being challenged with allergen may develop different types of asthmatic response, such as immediate asthmatic response (IAR), late asthmatic response (LAR), or dual late asthmatic response (DLAR), because of different immunologic mechanisms.

OBJECTIVES

To investigate the clinical features of delayed asthmatic response (DYAR), its reproducibility, and its association with other in vivo and in vitro diagnostic parameters and to contribute to the understanding of the possible mechanism(s) underlying this unusual clinical phenomenon.

METHODS

In 51 asthma patients developing 51 DYARs, the bronchial challenges with the same allergens were repeated and supplemented with additional diagnostic parameters. Control groups consisted of asthma patients developing IAR (n = 56), LAR (n = 43), and DLAR (n = 31) and healthy individuals (n = 48).

RESULTS

The DYAR began at 26 to 32 hours, reached a maximum at 32 to 48 hours, and resolved within 56 hours after the challenge. DYAR was statistically highly significant (P < .001) compared with phosphate-buffered saline controls.The differences between the initial and repeated DYAR were not significant (P = .14). The DYAR was associated with dyspnea, wheezing, tiredness, increased peripheral blood leukocyte count, lymphocytosis, neutrophilia but not eosinophilia, significant changes in the T(H)1/T(H)2 ratio in peripheral blood in favor of T(H)1 cells, and significant increase in the intracellular concentration of interferon gamma but not interleukin 4 or 5.

CONCLUSIONS

In addition to the previously established IAR, LAR, and DLAR, existence of another, the so-called DYAR to allergen challenge, has been demonstrated. In this type, the T(H)1 cells, together with neutrophils, may well play the predominant causal role.

Protease-activated receptors and prostaglandins in inflammatory lung disease

Protease-activated receptors (PARs) are a novel family of G protein-coupled receptors. Signalling through PARs typically involves the cleavage of an extracellular region of the receptor by endogenous or exogenous proteases, which reveals a tethered ligand sequence capable of auto-activating the receptor. A considerable body of evidence has emerged over the past 20 years supporting a prominent role for PARs in a variety of human physiological and pathophysiological processes, and thus substantial attention has been directed towards developing drug-like molecules that activate or block PARs via non-proteolytic pathways. PARs are widely expressed within the respiratory tract, and their activation appears to exert significant modulatory influences on the level of bronchomotor tone, as well as on the inflammatory processes associated with a range of respiratory tract disorders. Nevertheless, there is debate as to whether the principal response to PAR activation is an augmentation or attenuation of airways inflammation. In this context, an important action of PAR activators may be to promote the generation and release of prostanoids, such as prostglandin E(2), which have well-established anti-inflammatory effects in the lung. In this review, we primarily focus on the relationship between PARs, prostaglandins and inflammatory processes in the lung, and highlight their potential role in selected respiratory tract disorders, including pulmonary fibrosis, asthma and chronic obstructive pulmonary disease.

Elucidation of asthma phenotypes in atopic teenagers through parallel immunophenotypic and clinical profiling

BACKGROUND

Current treatment strategies for asthma in teenagers derive primarily from information on chronic disease in adults. More detailed understanding of risk factors related to teenage asthma might aid in the development of improved preventive and treatment strategies for this age group.

OBJECTIVE

We sought to identify biomarkers associated with asthma phenotypes in teenagers, particularly atopic asthma, and to identify markers that aid in discriminating between atopic subjects at high versus low risk of asthma.

METHODS

We studied 1380 unselected 14-year-olds and collected data on clinical history, allergic sensitization, and respiratory and immunoinflammatory function. The latter comprised measurements of circulating inflammatory markers and in vitro innate and adaptive immune functions, including house dust mite T-cell responses. We integrated the data into regression models to identify variables most strongly associated with asthma risk and severity among atopic subjects.

RESULTS

Eight hundred twenty-seven subjects were atopic, 140 subjects were asthmatic, and 81% of asthmatic subjects were also atopic. We identified asthma risk variables related to atopy intensity, including specific IgE and eosinophil levels, plus an additional series external to the T(H)2 cascade but that modified risk only in atopic subjects, including IFN-gamma, IL-10, and IL-12 responses and neutrophil numbers in blood. Moreover, bronchial hyperresponsiveness was associated strongly with atopic but not nonatopic asthma, and the bronchial hyperresponsiveness risk profile was itself dominated by atopy-associated variables.

CONCLUSIONS

Asthma in teenagers is predominantly driven by atopy acting in concert with a second tier of T(H)2-independent immunoinflammatory mechanisms, which contribute to pathogenesis only against the background of pre-existing inhalant allergy.

Chronic inflammation and asthma

Allergic asthma is a complex and chronic inflammatory disorder which is associated with airway hyper-responsiveness and tissue remodelling of the airway structure. Although originally thought to be a Th2-driven inflammatory response to inhaled innocuous allergen, the immune response in asthma is now considered highly heterogeneous. There are now various in vivo systems which have been designed to examine the pathways leading to the development of this chronic immune response and reflect, in part this heterogeneity. Furthermore, the emergence of endogenous immunoregulatory pathways and active pro-resolving mediators hold great potential for future therapeutic intervention. In this review, the key cellular and molecular mediators relating to chronic allergic airway disease are discussed, as well as emerging players in the regulation of chronic allergic inflammation.

Production of interleukin-10 in asthmatic children after Beta-1-3-glucan

BACKGROUND

Beta-1-3 Glucan is a polysaccharide extracted from Saccharomyces cerevisiae with a possible immunomodulating action that may have a favourable action on asthma symptoms and other allergic diseases. An experimental study carried out using a murine respiratory model detected a decrease in pulmonary tissue eosinophilia, as well as an increase in Interleukin-10 (IL-10) after glucan use.

METHODS

This open, exploratory study with blind outcome evaluation included asthmatic children between 6 and 12 years of age with mild to moderate persistent asthma and inadequate disease control (rescue medication needed more than twice a week) in spite of inhaled budesonide 400 microg/day. After a four week run-in period, subcutaneous Beta-1-3-glucan injections were given weekly for the first four weeks and then every two weeks for the last four weeks. IL-10 levels, measured by the immunoenzymatic method (ELISA), were compared before and after glucan administration.

RESULTS

Twenty patients (14 male and 6 female) were included. Mean IL-10 levels were 6.4 pg/ml and 11.3 pg/ml before and after glucan, respectively (p = 0.02). There was also a reduction of asthmatic symptoms score at the end of study.

CONCLUSIONS

This is the first study which shows that subcutaneous particulate Beta-1-3-glucan increases serum IL-10 levels in asthmatics. The possibility of glucan being able to modulate allergic sensitisation and having a beneficial action in restoring Th2 function should be assessed by means of properly planned controlled clinical trials, as it may represent a new therapeutic strategy.

What have we learnt from ISAAC phase III in the Asia-Pacific rim?

PURPOSE OF REVIEW

International Study of Asthma and Allergies in Childhood (ISAAC) phase III had provided a worldwide map of epidemiology of asthma and allergic diseases, as well as the changes in prevalence rate of these diseases when compared to data obtained in phase I. The wide variations of environmental factors and ethnic background in Asia provide excellent opportunities for research into the environmental and genetic determinants of asthma and allergies. This review summarizes important lessons learnt from ISAAC phase III results from Asia on asthma and allergy.

RECENT FINDINGS

ISAAC phase III provided epidemiological evidence of the wide variation and increasing prevalence of asthma and allergy in many Asian countries. When compared to other regions of the world, Asia has a relatively lower prevalence of asthma and allergic diseases. Comparative studies of populations of the same ethnic group living in different environments reveal striking disparity in prevalence of asthma and allergic diseases. The established risk factors could not explain the secular trend and variations of asthma prevalence in different Asian countries. Further research is needed in this rapidly changing region of Asia in order to identify the protective or risk factors associated with the development of asthma.

SUMMARY

ISAAC phase III provides standardized data on the prevalence and burden of asthma and allergy in the Asia-Pacific region. Further research is needed to reveal the underlying factors responsible for the wide variations in disease manifestations in the region.

An interdisciplinary analysis of sex and gender in relation to the pathogenesis of bronchial asthma

BACKGROUND

An increasing number of studies confirm that pathogenesis and prevalence of bronchial asthma are age and sex dependent. Detailed physiological mechanisms of the changing sex ratios with age are not fully known, however, the gender (socio-cultural) factors are also imperative. Although multiple factors definitely influence the pathogenesis of asthma, only individual or few combinations of these have been investigated.

METHODS

The terms 'sex', 'gender' and plausible combinations of both were systematically researched in selected databases (Medline, Scopus) or other sources, including publications from January 2000 to June 2007. Generated articles were categorized, either as endogenous or exogenous factors influencing the pathogenesis of asthma, and divided into the following subgroups: genetic, immunological, hormonal, gynaecological, nutritional, and environmental parameters.

RESULTS

An increasing number of studies investigate the influence of sex and gender in the aetiology, therapy and prevention of asthma. While their results are still debatable, others regarding its initiation, perpetuation and cessation have been clarified. Recent insights into interactions at biomolecular and immunological levels greatly contribute to clarifying sex-specific influences. Despite occasional oversimplifications, a trend for explanations considering the complex interplay of different factors can be observed. This work is in line with this trend and offers explanation models from our point of view.

CONCLUSIONS

Some disagreements regarding the patho-physiology, diagnosis, treatment and prevention of asthma still prevail. Nevertheless, in order to better appreciate its complexity, openness to and persistent consideration for interdisciplinary as well as sex- and gender-related factors is required of the medical-research community in future investigations.

Asthma in Latin America: a public heath challenge and research opportunity

Asthma has emerged as an important public health problem in many Latin American countries over the past decade. In Brazil and Costa Rica, the prevalence of asthma and associated morbidity is as great or greater as reported in traditional high prevalence countries such as the US, but remains neglected as a public health priority. Asthma in Latin America is associated particularly with underprivileged populations living in cities but remains relatively rare in many rural populations. The causes of asthma in Latin America are likely to be associated with urbanization, migration, and the adoption of a modern 'Westernized' lifestyle and environmental changes that follow these processes that include changes in diet, physical activity, hygiene, and exposures to allergens, irritants, and outdoor and indoor pollutants. Because of the enormous social, genetic, and environmental contrasts within and between Latin American countries, and the large differences in prevalence associated with these differences, the investigation of asthma in Latin America provides important research opportunities to identify the social and biological mechanisms that underlie asthma development. Asthma in Latin America poses enormous challenges for health policy makers, health services, and researchers to respond to and alleviate the growing burden of asthma disability, particularly among marginalized urban populations.

Complementary roles for lipid and protein allergens in triggering innate and adaptive immune systems

BACKGROUND

Recent advances in allergy research mostly focussed on two major headings: improving protein allergen purification, which is aimed towards a better characterization of IgE- and T-cell reactive epitopes, and the potential new role for unconventional innate and regulatory T cells in controlling airway inflammation. These advancements could appear to be in conflict each other, as innate T cells have a poorly-defined antigen specificity that is often directed toward nonprotein substances, such as lipids.

METHOD

To reconcile these contrasting findings, the model of cypress pollinosis as paradigmatic for studying allergic diseases in adults is suggested.

RESULTS

The biochemical characterization of major native protein allergens from undenatured pollen grain demonstrated that the most relevant substance with IgE-binding activity is a glycohydrolase enzyme, which easily denaturizes in stored grains. Moreover, lipids from the pollen membrane are implicated in early pollen grain capture and recognition by CD1(+) dendritic cells (DC) and CD1-restricted T lymphocytes. These T cells display Th0/Th2 functional activity and are also able to produce regulatory cytokines, such as IL-10 and TGF-beta. CD1(+) immature DCs expand in the respiratory mucosa of allergic subjects and are able to process both proteins and lipids.

CONCLUSION

A final scenario may suggest that expansion and functional activation of CD1(+) DCs is a key step for mounting a Th0/Th2-deviated immune response, and that such innate response does not confer long-lasting protective immunity.

Activating transcription factor 3 is a negative regulator of allergic pulmonary inflammation

We recently demonstrated the pivotal role of the transcription factor (TF) activating TF 3 (ATF3) in dampening inflammation. We demonstrate that ATF3 also ameliorates allergen-induced airway inflammation and hyperresponsiveness in a mouse model of human asthma. ATF3 expression was increased in the lungs of mice challenged with ovalbumin allergen, and this was associated with its recruitment to the promoters of genes encoding Th2-associated cytokines. ATF3-deficient mice developed significantly increased airway hyperresponsiveness, pulmonary eosinophilia, and enhanced chemokine and Th2 cytokine responses in lung tissue and in lung-derived CD4(+) lymphocytes. Although several TFs have been associated with enhanced inflammatory responses in the lung, ATF3 attenuates the inflammatory responses associated with allergic airway disease.

Motorcycle exhaust particles augment antigen-induced airway inflammation in BALB/c mice

Evidence indicates that environment pollutants from fossil fuel combustion compromise the immune system by enhancing allergic reactions and damaging the respiratory tract. This study was performed to investigate the effects of motorcycle exhaust particles (MEP), a major air pollutant especially in the urban areas of Taiwan, on allergen-induced airway inflammatory reactions in lab animals. BALB/c mice were intratracheally instilled with ovalbumin (OVA), MEP, or phosphate-buffered saline, 3 times every 2 wk. Airway hyperresponsiveness was measured in unrestrained mice by barometric plethsmography. Bronchoalveolar lavage fluid (BALF) and serum from treated animals were collected for cytokine and antibody determination by enzyme-linked immunosorbent assay (ELISA). Lung tissue stained with hematoxylin/eosin was examined. Data showed that MEP augmented OVA-induced airway inflammation; characterized by infiltration of eosinophils and neutrophils in BALF and lung tissue inflammation. The combination of OVA and MEP markedly increased interleukin-4 (IL-4), interleukin-5 (IL-5), and tumor necrosis factor-alpha (TNF-alpha) protein levels in BALF. In addition, MEP also augmented OVA-induced rise in OVA-specific immunoglobulin (Ig) G1 and IgE and airway hyperresponsiveness. Pretreated lavage cells with mitogen-activated protein kinase (MAPK) inhibitors showed that TNF-alpha release was significantly inhibited. This study found that MEP augmented antigen-induced allergic airway inflammation and airway hyperresponsiveness through a Th2-dominant pathway.

Interferon-gamma regulates chemokine expression and release in the human mast cell line HMC1: role of nitric oxide

Mast cells (MCs) are critical immune effector cells that release cytokines and chemokines involved in both homeostasis and disease. Interferon-gamma (IFN-gamma) is a pleiotropic cytokine that regulates multiple cellular activities. IFN-gamma modulates rodent MC responsiveness via production of nitric oxide (NO), although the effects in human MC populations is unknown. We sought to investigate the effects of IFN-gamma on expression of the chemokines interleukin-8 (IL-8) and CCL1 (I-309) in a human mast cell line (HMC1) and to determine the underlying regulatory mechanism. Nitric oxide synthase (NOS), IL-8 and CCL1 expression was determined using real-time polymerase chain reaction (PCR). NOS protein expression was analysed using western blot. NOS activity was determined using the citrulline assay. IL-8 and CCL1 release was measured by specific enzyme-linked immunosorbent assay (ELISA). IFN-gamma inhibited phorbol 12-myristate 13-acetate (PMA)-induced release of IL-8 and CCL1 (by 47 and 38%). Real-time PCR analysis of IFN-gamma-treated HMC1 showed a significant (P < 0.05) time-dependent increase in NOS1 and NOS3 mRNA. NOS3 protein was significantly increased at 18 hr, which correlated with a significant (P < 0.05) increase in constitutive NOS (cNOS) activity. IFN-gamma-induced inhibition of chemokine expression and release was NO dependent, as treatment with the NOS inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME) reduced the IFN-gamma inhibitory effect on IL-8 and CCL1 mRNA expression. NO donors mimicked the IFN-gamma effect. IFN-gamma inhibited PMA-induced cAMP response element binding protein (CREB) phosphorylation and DNA-binding activity. Our observations indicate for the first time that IFN-gamma enhances endogenous NO formation through NOS3 activity, and that NO regulates the transcription and release of IL-8 and CCL1 in a human MC line.

Worldwide trends in the prevalence of asthma symptoms: phase III of the International Study of Asthma and Allergies in Childhood (ISAAC)

BACKGROUND

Phase I of the International Study of Asthma and Allergies in Childhood (ISAAC) was designed to allow worldwide comparisons of the prevalence of asthma symptoms. In phase III the phase I survey was repeated in order to assess changes over time.

METHODS

The phase I survey was repeated after an interval of 5-10 years in 106 centres in 56 countries in children aged 13-14 years (n = 304,679) and in 66 centres in 37 countries in children aged 6-7 years (n = 193,404).

RESULTS

The mean symptom prevalence of current wheeze in the last 12 months changed slightly from 13.2% to 13.7% in the 13-14 year age group (mean increase of 0.06% per year) and from 11.1% to 11.6% in the 6-7 year age group (mean increase of 0.13% per year). There was also little change in the mean symptom prevalence of severe asthma or the symptom prevalence measured with the asthma video questionnaire. However, the time trends in asthma symptom prevalence showed different regional patterns. In Western Europe, current wheeze decreased by 0.07% per year in children aged 13-14 years but increased by 0.20% per year in children aged 6-7 years. The corresponding findings per year for the other regions in children aged 13-14 years and 6-7 years, respectively, were: Oceania (-0.39% and -0.21%); Latin America (+0.32% and +0.07%); Northern and Eastern Europe (+0.26% and +0.05%); Africa (+0.16% and +0.10%); North America (+0.12% and +0.32%); Eastern Mediterranean (-0.10% and +0.79%); Asia-Pacific (+0.07% and -0.06%); and the Indian subcontinent (+0.02% and +0.06%). There was a particularly marked reduction in current asthma symptom prevalence in English language countries (-0.51% and -0.09%). Similar patterns were observed for symptoms of severe asthma. However, the percentage of children reported to have had asthma at some time in their lives increased by 0.28% per year in the 13-14 year age group and by 0.18% per year in the 6-7 year age group.

CONCLUSIONS

These findings indicate that international differences in asthma symptom prevalence have reduced, particularly in the 13-14 year age group, with decreases in prevalence in English speaking countries and Western Europe and increases in prevalence in regions where prevalence was previously low. Although there was little change in the overall prevalence of current wheeze, the percentage of children reported to have had asthma increased significantly, possibly reflecting greater awareness of this condition and/or changes in diagnostic practice. The increases in asthma symptom prevalence in Africa, Latin America and parts of Asia indicate that the global burden of asthma is continuing to rise, but the global prevalence differences are lessening.

Asthma attributable to atopy: does it depend on the allergen supply?

The use of the population attributable fraction (PAF) of asthma owing to atopy has not been widely used in epidemiological studies on childhood asthma, especially to compare regions of the same country. The present study includes 1039 children from Cartagena, Spain (Mediterranean coast) and 663 from Madrid (centre of Spanish plateau) using the ISAAC phase II methodology (questionnaire and prick test to the most common allergens). While there were no differences in asthma symptoms between school children (aged 10-11 yr) from Madrid and Cartagena, atopy to any allergen was significantly higher in those from Madrid (40.9% vs. 29.3%, respectively, p < 0.0001). However, children from Madrid were mainly positive to pollen allergy whereas those from Cartagena were positive for mite allergy. PAF of all the different asthma symptoms owing to atopy (any positive skin test) and PAF of current wheezing owing to a more severe atopy (three positive wheals) were higher in children from Cartagena than those from Madrid (45.5% vs. 28.6% and 14.2% vs. 6.2%, respectively). Per cent of previous year wheezing attributable to atopy to specific allergens varied among those cities and was higher for D. pteronissinus, D. farinae, cat, and olive tree in children from Cartagena, and--conversely--higher for mixed grasses, mixed trees and Alternaria in those from Madrid. All of these differences remained significant even after adjusting for risk factors. PAF for asthma owing to atopy could be very different within the same country, probably depending on the allergen supply which may depend on environmental factors such as the climate.

Targeting of CD25 and glucocorticoid-induced TNF receptor family-related gene-expressing T cells differentially modulates asthma risk in offspring of asthmatic and normal mother mice

Immunological mechanisms leading to increased asthma susceptibility in early life remain obscure. In this study, we examined the effects of neonatal Ab treatments targeting T cell populations on the development of an asthma syndrome. We used a model of increased asthma susceptibility where offspring of asthmatic BALB/c mother mice are more prone (than normal pups) to develop the disease. Neonatal pretreatment of naive pups with mAb directed against the IL-2Ralpha chain (CD25), the costimulatory molecule glucocorticoid-induced TNFR family related gene, and the inhibitory molecule CTLA-4 elicited contrasting effects in offspring depending on the mother's asthma status. Specifically, neonatal CD25(high) T cell depletion stimulated asthma susceptibility in normal offspring whereas it ameliorated the condition of pups born of asthmatic mothers. Conversely, glucocorticoid-induced TNFR family related gene ligation as a primary signal reduced the spleen cellularity and largely abrogated asthma susceptibility in asthma-prone offspring, without inducing disease in normal pups. Striking changes in Th1/Th2 cytokine levels, especially IL-4, followed mAb pretreatment and were consistent with the impact on asthma susceptibility. These results point to major differences in neonatal T cell population and responsiveness related to maternal asthma history. Interventions that temporarily remove and/or inactivate specific T cell subsets may therefore prove useful to attenuate early life asthma susceptibility and prevent the development of Th2-driven allergic airway disease.

The importance of dietary control in the development of a peanut allergy model in Brown Norway rats

This report describes the further development of a peanut allergy model in Brown Norway (BN) rats and in particular the importance of allergen-free breeding of the laboratory animals for the allergen to be used. For this purpose BN rats were bred for 3 generations on soy- and peanut-free feed since it is known that the legumes peanut and soy are cross-reactive. In addition, the effect of cholera toxin (CT), an oral adjuvant often used to increase the sensitivity of food allergy models, was investigated in the BN rat model. BN rats that were bred on both soy- and peanut-free feed could be sensitized orally to peanut (all exposed rats developed peanut-specific IgE, IgG2a and IgG1) and the adjuvant CT could only enhance this sensitization to a limited extent. We also found different protein recognition patterns against purified peanut allergens (Ara h1, Ara h2 and Ara h3) between intraperitoneally (i.p.) and orally sensitized BN rats. Orally sensitized rats recognized all tested allergens whereas i.p. sensitized rats only recognized Ara h1 and Ara h2. Our conclusion is that a model for food allergy should preferably be (A) oral and (B) if possible without the use of adjuvantia. Our model in BN rats unites these preferred characteristics. In addition, we show the importance of dietary control when conducting oral sensitization studies. Special attention must be paid to unscheduled dietary pre-exposure of the animals to the protein under investigation to obtain optimal oral sensitization.

Chemokine concentrations and mast cell chemotactic activity in BAL fluid in patients with eosinophilic bronchitis and asthma, and in normal control subjects

BACKGROUND

Asthma and eosinophilic bronchitis share many immunopathologic features including increased numbers of eosinophils and mast cells in the superficial airway. The mast cell chemotactic activity of airway secretions has not been assessed in patients with eosinophilic bronchitis.

OBJECTIVES

To investigate the concentration of chemokines in bronchial wash samples and BAL fluid, and the mast cell chemotactic activity in BAL fluid from subjects with asthma and eosinophilic bronchitis, and from healthy control subjects.

METHODS

We measured the concentrations of CCL11, CXCL8, and CXCL10 in bronchial wash samples and BAL fluid from 14 subjects with eosinophilic bronchitis, 14 subjects with asthma, and 15 healthy control subjects. Mast cell chemotaxis to BAL fluid from these subjects was examined using the human mast cell line HMC-1.

RESULTS

The bronchial wash sample and BAL fluid concentrations of CXCL10 and CXCL8 was increased in subjects with eosinophilic bronchitis compared to those in subjects with asthma and healthy control subjects (p < 0.05). The CCL11 concentration was below the limit of detection in most subjects. BAL fluid from subjects with eosinophilic bronchitis was chemotactic for mast cells (1.4-fold migration compared to a control, 95% confidence interval, 1.1 to 1.9; p = 0.04) and was inhibited by blocking CXCR1 (45% inhibition; p = 0.002), CXCR3 (38% inhibition; p = 0.034), or both (65% inhibition; p = 0.01). BAL fluid from the subjects with asthma and healthy control subjects was not chemotactic for mast cells. Mast cell migration to BAL fluid was correlated with the concentration of CXCL8 (r = 0.42; p = 0.031) and CXCL10 (r = 0.52; p = 0.007).

CONCLUSION

In subjects with eosinophilic bronchitis, CXCL8 and CXCL10 concentrations were elevated in airway secretions. These chemokines may play a key role in mast cell recruitment to the superficial airway in this condition.

Clinical characteristics and diabetes associated autoantibodies in patients with both type 1 diabetes mellitus and asthma

OBJECTIVE

Type 1 diabetes mellitus (DM1) and asthma are mediated by opposite arms of the cellular immune system, namely T helper (Th)1 and Th2 CD4+ cells, respectively. It is not known whether their coexistence affects their clinical manifestations.

METHODS

The number of asthma exacerbations, frequency of hypoglycemic events, HbA1c levels, diabetes associated autoantibody status and diabetes associated late complications were determined in three paired groups of patients (n = 11) matched by gender and age: DM1 and asthma, asthma only, and DM1 only.

RESULTS

Patients with both diseases had a higher prevalence of hypoglycemic events per month compared to patients with DM1 only: 5.67 +/- 4.27 vs 1.45 +/- 2.06, respectively (p = 0.008). The co-existence of the two diseases did not modify the remaining clinical and laboratory parameters.

CONCLUSION

Patients with both DM1 and asthma have similar clinical characteristics to patients with only one of these diseases apart from a higher rate of hypoglycemic events compared to patients with DM1 without asthma.

TH1/TH2 cytokine balance in patients with both type 1 diabetes mellitus and asthma

BACKGROUND AND OBJECTIVE

T1DM and asthma are mediated by opposite arms of the cellular immune system namely T helper (Th)1 and Th2 CD4(+) cells, respectively. Our aim was to characterize the Th1/Th2 cytokine balance in patients with both T1DM and asthma.

METHODS

Forty-four patients, mean age 19 years were matched by gender and age, to 4 paired groups: T1DM and asthma, asthma only, T1DM only and healthy controls. Peripheral blood mononuclear cells (PBMC) were stimulated in vitro with disease-specific recombinant antigens; glutamic acid decarboxylase and house dust mite (Der p1 antigen) for T1DM and asthma, respectively, and non-specific mitogens; phytohemaglutinin (PHA), tetanus toxin and anti-CD3 mAb. ELISPOT and ELISA technique were used to determine INF-gamma, IL-2, IL-4, IL-13 and IL-10 expression.

RESULTS

Patients with T1DM and asthma demonstrated a similar cytokine pattern but lower Th1/Th2 ratio compared to patients with T1DM only. The Th2 cytokines response to Der p1 was enhanced in patients with both diseases compared to controls. The IL-10 overall secretion was higher in patients with both diseases compared to one disease only.

CONCLUSION

The Th1 and Th2 secretory pattern of patients with T1DM and asthma combines features of both diseases suggesting a unique Th1/Th2 balance.

Airway generation-specific differences in the spatial distribution of immune cells and cytokines in allergen-challenged rhesus monkeys

BACKGROUND

Accumulation of immune cell populations and their cytokine products within tracheobronchial airways contributes to the pathogenesis of allergic asthma. It has been postulated that peripheral regions of the lung play a more significant role than proximal airways with regard to inflammatory events and airflow obstruction.

OBJECTIVE

To determine whether immune cell populations and associated cytokines are uniformly distributed throughout the conducting airway tree in a non-human primate model of allergic asthma.

METHODS

We used a stereologic approach with a stratified sampling scheme to measure the volume density of immune cells within the epithelium and interstitium of trachea and 4-5 intrapulmonary airway generations from house dust mite (HDM) (Dermatophagoides farinae)-challenged adult monkeys. In conjunction with immune cell distribution profiles, mRNA levels for 21 cytokines/chemokines and three chemokine receptors were evaluated at four different airway generations from microdissected lungs.

RESULTS

In HDM-challenged monkeys, the volume of CD1a+ dendritic cells, CD4+ T helper lymphocytes, CD25+ cells, IgE+ cells, eosinophils, and proliferating cells were significantly increased within airways. All five immune cell types accumulated within airways in unique patterns of distribution, suggesting compartmentalized responses with regard to trafficking. Although cytokine mRNA levels were elevated throughout the conducting airway tree of HDM-challenged animals, the distal airways (terminal and respiratory bronchioles) exhibited the most pronounced up-regulation.

CONCLUSION

These findings demonstrate that key effector immune cell populations and cytokines associated with asthma differentially accumulate within distinct regions and compartments of tracheobronchial airways from allergen-challenged primates.

A novel role of hepatocyte growth factor as an immune regulator through suppressing dendritic cell function

Hepatocyte growth factor (HGF) plays an important role in many biological events such as angiogenesis, cell proliferation, anti-fibrosis and antiapoptosis. It is well known that HGF promotes tumor progression and suppresses development of fibrosis after tissue injury. In contrast, its role in immune-mediated disorders has not been fully clarified. In the present study, we examined the role of HGF in Ag-specific immune response using in vitro studies and an experimental model of allergic airway inflammation. We first confirmed that dendritic cells (DCs) expressed the receptor for HGF, c-met, which was not expressed in T cells. Treatment with HGF both in vitro and in vivo potently suppressed DC functions such as Ag-presenting capacity, thus down-regulating Ag-induced Th1- and Th2-type immune responses. Exogenous administration of the HGF expression plasmid into Ag-primed mice markedly suppressed the development of airway eosinophilia and airway hyperresponsiveness, which was induced by Ag inhalation, with suppression of the Ag-presenting capacity of DCs in the lung. HGF exhibited these immunosuppressive effects without up-regulation of IL-10 or TGF-beta. We also found that expression of endogenous HGF in the lung significantly increased following Ag sensitization and inhalation challenges. Finally, neutralization of endogenous HGF in vivo significantly increased airway eosinophilia and airway hyperresponsiveness with up-regulation of the Ag-presenting capacity of DCs in the lung. These results demonstrated a novel, significant, and possibly therapeutic role of HGF as a potent regulator in immune-mediated disorders such as asthma.

Role of cysteinyl leukotrienes in airway inflammation and responsiveness following RSV infection in BALB/c mice

Cysteinyl leukotrienes (CysLTs) contribute to the development of airway obstruction and inflammation in asthma; however little information is available on the role of these molecules in the pathophysiology of respiratory syncytial virus (RSV) bronchiolitis. This study was designed to evaluate the effects of RSV infection on CysLTs production in a well-established mouse infection model. Furthermore, we assessed the effect of anti-inflammatory agents (a leukotriene receptor antagonist, MK-571, and dexamethasone) on the functional and immune changes induced by RSV infection. Six to 8-wk-old BALB/c mice were infected with human RSV (strain A2). Measurements of airway function were performed using whole body plethysmography. Lung inflammation was assessed by cell counts, measurement of cytokines and CysLTs in bronchoalveolar lavage fluid (BALF) in the absence and presence of treatment with MK-571 or dexamethasone. RSV infection produced a marked increase in CysLTs in the BALF and lung tissue, recruitment of neutrophils and lymphocytes into the airways, increased IFN-gamma levels and airway hyperresponsiveness (AHR). Treatment with MK-571 decreased RSV-induced AHR without affecting the cellular and inflammatory responses to RSV. Dexamethasone decreased AHR and markedly reduced the recruitment of inflammatory cells and production of IFN-gamma. Our findings suggest CysLTs play an important role in the pathogenesis of RSV-induced airway dysfunction. Treatment with MK-571 decreases RSV-induced AHR but does not appear to alter the lung inflammatory responses to RSV. In contrast, dexamethasone decreases RSV-induced AHR but interferes with recruitment of inflammatory cells, resulting in decreased Th1 cytokines (a potentially Th2-prone environment) in this model. These studies support recent reports on the beneficial effects of CysLT receptor antagonist in human trials and provide a model for investigating the role of CysLTs in RSV bronchiolitis.

Wheezing during the first year of life in infants from low-income population: a descriptive study

BACKGROUND

Recurrent wheezing (RW) plays an important role in the morbidity and mortality of children during the first year of life in developing regions and its actual incidence in those areas is virtually unknown.

METHODS AND RESULTS

This study describes the occurrence of wheezing during the first year of life in a birth cohort of 188 infants followed monthly and living in a poor urban area in Santiago de Chile. This study showed that 80.3 % of the infants in the cohort had one or more wheezing episode during the first year of life, 43.1 % had RW (3 or more wheezing episodes), 44.1 % had their first wheezing within the first three months of life and 13.3 % had pneumonia (PN). Having one or more episode of wheezing in the first three months of life was the main risk factor for suffering from RW during the first year and RW was a significant risk factor for having PN.

CONCLUSIONS

This study found a high prevalence of RW in infants from a low-income population during the first year of life with the disease starting very early in their lives, progressing with more frequent episodes and being significantly associated to PN, particularly in the first 6 months of life.

The CXCL10/CXCR3 Axis Mediates Human Lung Mast Cell Migration to Asthmatic Airway Smooth Muscle

Mast cell microlocalization within the airway smooth muscle bundle is an important determinant of the asthmatic phenotype. We hypothesized that mast cells migrate toward airway smooth muscle in response to smooth muscle-derived chemokines. In this study, we investigated (1) chemokine receptor expression by mast cells in the airway smooth muscle bundle in bronchial biopsies from subjects with asthma using immunohistology, (2) the concentration of chemokines in supernatants from stimulated ex vivo airway smooth muscle cells from subjects with and without asthma measured by enzyme-linked immunosorbent assay, and (3) mast cell migration toward these supernatants using chemotaxis assays. We found that CXCR3 was the most abundantly expressed chemokine receptor on human lung mast cells in the airway smooth muscle in asthma and was expressed by 100% of these mast cells compared with 47% of mast cells in the submucosa. Human lung mast cell migration was induced by airway smooth muscle cultures predominantly through activation of CXCR3. Most importantly, CXCL10 was expressed preferentially by asthmatic airway smooth muscle in bronchial biopsies and ex vivo cells compared with those from healthy control subjects. These results suggest that inhibition of the CXCL10/CXCR3 axis offers a novel target for the treatment of asthma.

Functional promoter polymorphism in the TBX21 gene associated with aspirin-induced asthma

Asthma is a phenotypically heterogeneous disorder with many etiologic factors and clinical characteristics. T-bet, a Th1-specific transcription factor of T-box family, has been found to control interferon-gamma (IFN-gamma) expression in T cells. Mice lacking the T-bet gene (tbx21) demonstrate multiple physiological and inflammatory features reminiscent of human asthma. In order to examine whether polymorphisms in the candidate gene, TBX21, located on chromosome 17q21.32, are related to the risk of human asthma phenotypes, we have searched for genetic variations in the human TBX21 gene and identified 24 single nucleotide polymorphisms (SNPs), including five novel SNPs, by direct sequencing in Japanese subjects. Among asthma phenotypes, a promoter -1993T-->C SNP, which is in linkage disequilibrium with a synonymous coding 390A-->G SNP in exon 1, is significantly associated with a risk of aspirin-induced asthma (AIA; P = 0.004, P(c) = 0.016). This association has also been confirmed in additional independent samples of asthma with nasal polyposis (P = 0.008), regardless of aspirin hypersensitivity. Furthermore, our data indicate that the -1993T-->C substitution increases the affinity of a particular nuclear protein to the binding site of TBX21 covering the -1993 position, resulting in increased transcriptional activity of the TBX21 gene. Thus, in addition to the antigen-driven excess Th2 response, increased T-bet (and subsequent IFN-gamma) production in human airways of individuals with the -1993T-->C polymorphism could contribute to the development of certain asthma-related phenotypes, such as AIA.

Chronic rhinosinusitis: an enhanced immune response to ubiquitous airborne fungi

BACKGROUND

Chronic rhinosinusitis (CRS) is one of the most common long-term illnesses in the United States. The etiology of CRS is unknown, and no effective treatment has been established.

OBJECTIVE

We investigated the hypothesis that abnormal immunologic responses to ubiquitous airborne fungi contribute to the pathogenesis of this disease.

METHODS

The proliferative and cytokine responses of PBMCs to extracts from 4 common airborne fungi-including Alternaria , Aspergillus , Cladosporium , and Penicillium -were examined by in vitro culture. Serum specimens were tested for specific IgE and IgG to these fungi.

RESULTS

PBMCs from approximately 90% of the patients with CRS, but not those from normal individuals, produced both IL-5 and IL-13 when exposed to Alternaria. Furthermore, PBMCs from patients with CRS produced significantly more IFN-gamma than PBMCs from normal individuals in response to Alternaria (median, 553 pg/mL vs 98 pg/mL; P < .01). Levels of serum IgG antibodies to Alternaria and Cladosporium were clearly increased in patients with CRS compared with normal individuals ( P < .01). Less than 30% of the patients with CRS had specific IgE antibodies to Alternaria or Cladosporium. The increased humoral (serum IgG) response strongly correlated with the increased cellular (IL-5 production) response to Alternaria ( r = 0.619; P < .01).

CONCLUSION

Patients with CRS show exaggerated humoral and cellular responses, both T(H)1 and T(H)2 types, to common airborne fungi, particularly Alternaria. The anomalous immune and inflammatory responses to ubiquitous fungi may explain the chronicity of airway inflammation in CRS.

No epidemiological evidence for infant vaccinations to cause allergic disease

CONTEXT

The prevalence of allergic diseases has increased considerably over the last decades. The hygiene hypothesis has emerged, linking reduced microbial exposure and infections early in life with the development of allergic diseases. Especially some of currently available non-replicating infant vaccines are unlikely to mimic a natural infection-mediated immune response that protects against the development of allergic diseases. Moreover, several studies suggested infant vaccinations to increase the risk of allergic diseases.

OBJECTIVE

To determine whether infant vaccinations increase the risk of developing allergic disease.

DATA SOURCES

We searched MEDLINE from 1966 to March 2003 and bibliography lists from retrieved articles, and consulted experts in the field to identify all articles relating vaccination to allergy.

STUDY SELECTION AND DATA EXTRACTION

We selected epidemiological studies with original data on the correlation between vaccination with diphtheria, pertussis, tetanus (DPT), measles, mumps, rubella (MMR) and Bacillus Calmette-Guérin (BCG) vaccine in infancy and the development of allergic diseases, and assessed their quality and validity.

DATA SYNTHESIS

Methodological design and quality varied considerably between the studies we reviewed. Many studies did not address possible confounders, such as the presence of lifestyle factors, leaving them prone to bias. The studies that offer the stronger evidence, including the only randomized controlled trial at issue published to date, indicate that the infant vaccinations we investigated do not increase the risk of developing allergic disease. Furthermore, BCG does not seem to reduce the risk of allergies.

CONCLUSIONS

The reviewed epidemiological evidence indicates that, although possibly not contributing to optimal stimulation of the immune system in infancy, current infant vaccines do not cause allergic diseases.

Is the mycobacteria-derived purified protein response in atopic asthmatic children different?

BACKGROUND

The response to mycobacteria-derived purified protein (PPD) is mediated primarily by T-helper-1 response and is expected to be inhibited in atopic diseases. The aim of this study was to investigate whether the PPD response is different in atopic asthmatic children.

METHODS

40 atopic asthmatic children (mean age 8.3 +/- 4.9 years) and 40 healthy age- and sex-matched children who had received bacillus Calmette-Guerin (BCG) vaccination were included in the study. Five PPD units were administered intradermally to all children and were interpreted after 48 h.

RESULTS

There was no correlation between serum total IgE level and PPD induration (p=0.054). The PPD induration was not statistically different between the children who used inhaled corticosteroid and those who did not. Although the PPD positivity (induration > or =5 mm) rate was higher in atopic asthmatic children (50%) than in healthy children (32.5%), the difference was not found to be statistically significant. The PPD induration in atopic asthmatic children (7.41 +/- 5.58 mm) was found to be greater than the one in healthy children (5.21 +/- 3.39) (p < 0.039). The induration in atopic asthmatic children (5.21 +/- 3.77) and healthy children (4.43 +/- 2.32) did not show a difference in children who where vaccinated only once with BCG, but it was found to be statistically significantly greater in atopic asthmatic children (12.50 +/- 5.90) than healthy children (7.08 +/- 4.70) who were vaccinated with BCG twice (p <0.012). The proportion of having a PPD induration of > or =10 mm was found to be higher in atopic asthmatic children than in the healthy ones (32.5 vs. 12.5%) (p <0.032).

CONCLUSION

Our data showed that the PPD response was stronger in BCG-vaccinated atopic asthmatic children than in healthy BCG-vaccinated ones.