6. Asthma: Factors underlying inception, exacerbation, and disease progression

A thymic stromal lymphopoietin polymorphism may provide protection from asthma by altering gene expression

BACKGROUND

Genome-wide association studies have identified associations of the single nucleotide polymorphism rs1837253 in the thymic stromal lymphopoietin (TSLP) gene with asthma, allergic disease and eosinophilia. The TSLP gene encodes two isoforms, long and short, and previous studies have indicated functional differences between these two isoforms.

OBJECTIVE

We investigated the expression of these TSLP isoforms in response to a pro-inflammatory signal, and the role of the rs1837253 genotype in gene isoform regulation.

METHODS

We cultured nasal epithelial cells of asthmatic and non-asthmatic subjects and evaluated poly(I:C)-induced TSLP protein secretion using multiplex protein assays and gene expression profiles of the TSLP isoforms, and related genes using real-time qPCR. We correlated these profiles with rs1837253 genotype.

RESULTS

Asthmatic nasal epithelial cells exhibited increased TSLP protein secretion compared with nasal epithelial cells from healthy controls. The long TSLP isoform was more responsive to poly(I:C) stimulation. Additionally, the minor T allele of rs1837253 was less inducible than the major C allele, suggesting differential regulation; this may explain the "protective" effects of the T allele in asthma.

CONCLUSION

Our results provide important insights into the differential regulation and function of TSLP isoforms, including the role of TSLP rs1837253 polymorphisms in allergic inflammatory processes.

CLINICAL RELEVANCE

The key finding on the influence of TSLP genetic variation on disease expression/endotype could provide basis for investigation into targeted biologics for anti-TSLP therapies.

Sarcopenic obesity and health outcomes in patients seeking weight loss treatment

AIM

To investigate the prevalence of sarcopenic obesity (SO) and its association with health outcomes in patients seeking weight loss treatment from a bariatric center.

METHODS

In this retrospective study, patients [≥18 years old, body mass index (BMI) ≥30 kg/m²] from the Tallahassee Memorial Bariatric Center and with baseline body composition assessment by bioelectrical impedance analysis were included. Fat mass index (FMI = fat mass/height²) and fat-free mass index (FFMI = fat free mass/height²) were calculated. SO was defined by a FMI/FFMI ratio greater than the 95 percentile of sex, BMI and ethnicity specific population-representative references. Medical records were reviewed for biochemical and comorbidity measures.

RESULTS

One hundred and forty-four patients (∼69% females, mean age 55.6 years, mean BMI 46.6 kg/m²) were included. Patients' FMI/FFMI ratios ranged from 0.35 to 1.60 kg/m² across body weight spectrum, with 51% having SO. Blood pressure, fasting glucose, triglycerides, HDL or LDL were not different between patients with and without SO. However, the prevalence of high cholesterol, asthma, alcoholism and hernia were higher in patients with SO. SO was the strongest univariate predictor of high cholesterol (OR = 2.08, 95% CI 1.07-4.04) and asthma (OR = 2.77, 95% CI = 1.12-6.83).

CONCLUSION

SO was prevalent and associated with adverse health outcomes, beyond that captured by anthropometric measures in the present study.

Early-Life Exposure to the Great Smog of 1952 and the Development of Asthma

RATIONALE

Little is known about the long-term effects of air pollution exposure and the root causes of asthma. We use exposure to intense air pollution from the 1952 Great Smog of London as a natural experiment to examine both issues.

OBJECTIVES

To determine whether exposure to extreme air pollution in utero or soon after birth affects asthma development later in life.

METHODS

This was a natural experiment using the unanticipated pollution event by comparing the prevalence of asthma between those exposed to the Great Smog in utero or the first year of life with those conceived well before or after the incident and those residing outside the affected area at the time of the smog.

MEASUREMENTS AND MAIN RESULTS

Prevalence of asthma during childhood (ages 0-15) and adulthood (ages >15) is analyzed for 2,916 respondents to the Life History portion of the English Longitudinal Study on Aging born from 1945 to 1955. Exposure to the Great Smog in the first year of life increases the likelihood of childhood asthma by 19.87 percentage points (95% confidence interval [CI], 3.37-36.38). We also find suggestive evidence that early-life exposure led to a 9.53 percentage point increase (95% CI, -4.85 to 23.91) in the likelihood of adult asthma and exposure in utero led to a 7.91 percentage point increase (95% CI, -2.39 to 18.20) in the likelihood of childhood asthma.

CONCLUSIONS

These results are the first to link early-life pollution exposure to later development of asthma using a natural experiment, suggesting the legacy of the Great Smog is ongoing.

Immunomodulatory Effects of Ambroxol on Airway Hyperresponsiveness and Inflammation

Ambroxol is used in COPD and asthma to increase mucociliary clearance and regulate surfactant levels, perhaps through anti-oxidant and anti-inflammatory activities. To determine the role and effect of ambroxol in an experimental model of asthma, BALB/c mice were sensitized to ovalbumin (OVA) followed by 3 days of challenge. Airway hyperresponsiveness (AHR), lung cell composition and histology, and cytokine and protein carbonyl levels in bronchoalveolar lavage (BAL) fluid were determined. Ambroxol was administered either before the first OVA challenge or was begun after the last allergen challenge. Cytokine production levels from lung mononuclear cells (Lung MNCs) or alveolar macrophages (AM) were also determined. Administration of ambroxol prior to challenge suppressed AHR, airway eosinophilia, goblet cell metaplasia, and reduced inflammation in subepithelial regions. When given after challenge, AHR was suppressed but without effects on eosinophil numbers. Levels of IL-5 and IL-13 in BAL fluid were decreased when the drug was given prior to challenge; when given after challenge, increased levels of IL-10 and IL-12 were detected. Decreased levels of protein carbonyls were detected in BAL fluid following ambroxol treatment after challenge. In vitro, ambroxol increased levels of IL-10, IFN-γ, and IL-12 from Lung MNCs and AM, whereas IL-4, IL-5, and IL-13 production was not altered. Taken together, ambroxol was effective in preventing AHR and airway inflammation through upregulation of Th1 cytokines and protection from oxidative stress in the airways.

IL12Rβ1: the cytokine receptor that we used to know

Human IL12RB1 encodes IL12Rβ1, a type I transmembrane receptor that is an essential component of the IL12- and IL23-signaling complex. IL12RB1 is well-established as being a promoter of delayed type hypersensitivity (DTH), the immunological reaction that limits tuberculosis. However, recent data demonstrate that in addition to promoting DTH, IL12RB1 also promotes autoimmunity. The contradictory roles of IL12RB1 in human health raises the question, what are the factors governing IL12RB1 function in a given individual, and how is inter-individual variability in IL12RB1 function introduced? Here we review recent data that demonstrate individual variability in IL12RB1 function is introduced at the epigenetic, genomic polymorphism, and mRNA splicing levels. Where and how these differences contribute to disease susceptibility and outcome are also reviewed. Collectively, recent data support a model wherein IL12RB1 sequence variability - whether introduced at the genomic or post-transcriptional level - contributes to disease, and that human IL12RB1 is not as simple a gene as we once believed.

Domestic exposure to fungal allergenic particles determined by halogen immunoassay using subject's serum versus particles carrying three non-fungal allergens determined by allergen-specific HIA

Studies that estimate indoor aeroallergen exposure typically measure a pre-selected limited range of allergens. In this study, inhalable aeroallergen particles were quantified using the halogen immunoassay (HIA) to determine the contribution of fungal and non-fungal aeroallergens to total allergen exposure. Bioaerosols from 39 homes of fungal-allergic subjects were sampled using inhalable fraction samplers and immunostained by HIA using resident subject's immunoglobulin E (IgE) to detect allergen-laden particles. Fungal aerosols as well as particles carrying mite, cat, and cockroach allergens were identified and enumerated by HIA. Reservoir dust-mite (Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergen concentrations were quantified by ELISA. Fungal particles that bound subject's IgE in the HIA were 1.7 (bedroom)- and 1.4 (living room)-fold more concentrated than Der p 1, Fel d 1, and Bla g 1 allergen particles combined. Predominant fungal conidia that bound IgE were derived from common environmental genera including Cladosporium and other fungi that produce amerospores. Airborne mite, cat, and cockroach allergen particle counts were not associated with reservoir concentrations determined by ELISA. This study demonstrates that inhalable fungal aerosols are the predominant aeroallergen sources in Sydney homes and should be considered in future exposure assessments.

PRACTICAL IMPLICATIONS

Indoor allergen exposure assessment studies have primarily focused on a limited range of allergen sources in samples derived from reservoir dust samples. Using an innovative immunodiagnostic approach, this study demonstrates that fungal bioaerosols are the dominant source of aeroallergen exposure in the domestic environment, providing unique insight into domestic aeroallergen exposure.

Indoor environmental factors associated with wheezing illness and asthma in South Korean children: phase III of the International Study of Asthma and Allergies in Childhood

BACKGROUND

The relationship between exposure to indoor environmental pollutants and incidence of asthma and wheezing illness in children is unclear. This study aimed to clarify this relationship by identifying the risk factors associated with these conditions in South Korean children aged 6-7 years.

METHODS

The parents or guardians of 3810 children aged 6-7 years who had participated in the International Study of Asthma and Allergies in Childhood and met the study criteria completed validated questionnaires regarding their children's asthma and wheezing illness, risk factors and exposure to indoor pollutants. The data were subjected to chi-square and multivariate logistic regression analysis to identify the factors significantly associated with asthma and wheezing illness.

RESULTS

Parental history of allergic disease (odds ratio [OR]: 1.729; 95% confidence interval [CI]: 1.447-2.066), living on the basement or semi-basement floor (OR: 1.891; 95% CI: 1.194-2.996) and living in housing that had been remodeled within the last 12 months (OR: 1.376; 95% CI: 1.101-1.720) were found to be significantly associated with wheezing illness. Parental history of allergic disease (OR: 2.189; 95% CI: 1.483-3.231), male sex (OR: 1.971; 95% CI: 1.369-2.838) and positive skin prick test (SPT) result (OR: 1.583; 95% CI: 1.804-3.698) were found to be significantly associated with current asthma.

CONCLUSIONS

Although the risk factors for current asthma appear to be more related to the non-modifiable risk factors like sex, parental history of allergic diseases, SPT, the two groups are associated with exposure to modifiable indoor environmental factors.

Atopy, cytokine production, and airway reactivity as predictors of pre-school asthma and airway responsiveness

BACKGROUND

Childhood asthma is often characterized by recurrent wheezing, airway hyper-reactivity, atopy, and altered immune characteristics; however, our understanding of the development of these relationships from early in life remains unclear. The aim of our study was to evaluate whether atopy, cytokine production by peripheral blood mononuclear cells (PBMCs), and airway responsiveness, assessed in infants and toddlers, are associated with asthma and airway responsiveness at 4-years of age.

METHODS

Infants with eczema (N = 116), enrolled prior to wheezing, were assessed at entry (mean age of 10.7 months), at 1-year follow-up (N = 112), and at 4-years of age (N = 94). Total serum IgE, specific IgE to allergens, and cytokines produced by stimulated PBMCs, were assessed at entry and 1-year follow-up. Spirometry was obtained at all 3-visits, while airway reactivity to methacholine was assessed at entry and 1-year follow-up, and bronchodilator (BD) responsiveness, as well as current asthma was assessed at 4-years of age.

RESULTS

We found that pre-school children with asthma had lower spirometry and a greater BD-response. Serum IgE, particularly to egg and/or milk, and altered cytokine production by PBMCs at entry to the study were associated with asthma, lower spirometry, and greater airway responsiveness at 4-years of age. In addition, we found that airway responsiveness, as well as spirometry, tracked from infancy to 4-years of age.

CONCLUSIONS

While spirometry and airway responsiveness track longitudinally from early in life, atopy and cytokine production by PBMCs are associated not only with an increased risk of pre-school asthma, but also lower spirometry and increased airway responsiveness.

Evaluating the effect of an asthma self-management intervention for rural families

OBJECTIVE

To present outcomes of an asthma self-management educational intervention delivered to children (grades 2-5) at school and to parents in a home visit.

METHODS

The intervention effectiveness was tested in a 12-month longitudinal study with randomization by elementary schools into treatment and attention-control groups with 183 children who had a diagnosis of asthma. Data were collected at four time points. Change over time was examined with linear mixed models.

RESULTS

Quality of life (QOL), hospitalizations, and emergency department visits improved significantly for all the children. African American and Mexican American children had worse asthma-related QOL than did White children. Asthma management behaviors, asthma self-efficacy, and coping likewise improved with girls improving significantly more than the boys. Significant improvements in inhaler skill and asthma severity were seen in the treatment group children when compared to the control group. Treatment group parents showed significant improvements in home asthma management and self-efficacy.

CONCLUSIONS

The improvement in inhaler skill is an important finding for practitioners as this is a behavior that can be addressed in the clinical setting. The reduction in the treatment group's asthma severity scores may reflect the improvement in medication delivery as their inhaler skill improved. The differential improvement between boys and girls points to the need for testing other formats in asthma education that can address different learning styles. The individualized parent asthma education enabled the intervener to incorporate neighborhood and home environmental information thereby allowing for tailoring of parental instruction.

Transient receptor potential vanilloid 2 (TRPV2), a potential novel biomarker in childhood asthma

BACKGROUND

The presence of transient receptor potential vanilloid 2 (TRPV2) in human peripheral blood cells may suggest a role under pathological conditions. The aim of this study was to explore the relationship between the expression profile of TRPV2 gene and childhood asthma in the north of China. The effects of allergens exposure on the expression of TRPV2 gene were also investigated.

METHODS

Sixty asthmatics children confirmed by physician diagnosis and 60 healthy children as a control group were recruited. Serum total IgE and specific IgE were measured. Using quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR), TRPV2 was detected in total RNA extracted from peripheral blood lymphocytes. Student's t-test and chi-square test were used to analyze the relationship between TRPV2 transcript and different parameter variables on susceptibility of childhood asthma. Multiple logistic regression was used to analyze the associations between TRPV2 gene and allergens.

RESULTS

The expression level of TRPV2 gene was increased 2.6 times in asthmatic children compared with controls (p < .01). The up-regulation of TRPV2 gene and sensitization to one of three the allergens-spring pollen, dust mite, and dog and cat hair-were correlated with childhood asthma. In addition, the hypersensitivity to spring pollen, cockroach, and dust mite and up-regulation of TRPV2 gene expression may be the risk factors for the childhood asthma in Beijing.

CONCLUSIONS

The increased expression of TRPV2 gene in peripheral lymphocytes is closely correlated with childhood asthma in the north of China. This study provides a potential new biomarker of childhood asthma and lays the basis for further clarification of the pathogenesis underlying asthma.

Aspirin-intolerant asthma in the Korean population: prevalence and characteristics based on a questionnaire survey

BACKGROUND

Aspirin-intolerant asthma is a unique clinical syndrome characterized by acute bronchoconstriction following the administration of aspirin and/or non-steroidal anti-inflammatory drugs.

OBJECTIVE

We assessed the prevalence and investigated the demographic and clinical characteristics of adult patients with aspirin-intolerant asthma in Korea.

METHODS

Using an adult asthma cohort (COREA) from 11 university hospitals in Korea, we analyzed the prevalence of aspirin-intolerant asthma, defined as a positive response to the question: "Have you ever experienced dyspnea and cough after taking an aspirin or any NSAID (cold medicine)?" Demographic and clinical characteristics were compared between patients with aspirin-intolerant asthma and aspirin-tolerant asthma.

RESULTS

Aspirin-intolerant asthma was reported in 68 (5.8%) of 1173 adult asthmatics (age 15-84). Patients with aspirin-intolerant asthma had a lower mean age (43.9 ± 13.4 vs. 49.0 ± 15.6, P = 0.003) and a higher prevalence of rhinosinusitis (77.9% vs. 61.7%, P = 0.012) and atopic dermatitis (16.2% vs. 5.7%, P = 0.001) than aspirin-tolerant asthma patients. There were no significant differences in lung function, asthma severity or the use of asthma controllers. However, aspirin-intolerant asthma was associated with greater use of healthcare services over a lifetime and over the past 12 months. Aspirin-intolerant asthma was significantly associated with emergency room visits over the past 12 months (P = 0.029, OR 2.19, 95% CI 1.08-4.42).

CONCLUSION

Based on histories, the prevalence of aspirin-intolerant asthma is 5.8% among adult asthma patients in Korea. Aspirin-intolerant asthma is associated with lower age, higher prevalence of rhinosinusitis and atopic dermatitis, and more frequent exacerbations.

Chickenpox in childhood is associated with decreased atopic disorders, IgE, allergic sensitization, and leukocyte subsets

BACKGROUND

Wild-type varicella zoster infection (WTVZV) up to 8 yr of age has been shown to protect against atopic dermatitis (AD) and asthma. We sought to determine whether WTVZV in childhood protects against atopic disorders, allergic sensitization or decreases serum Immunoglobulin E (IgE) levels.

METHODS

We conducted a retrospective, practice-based study of outpatient pediatric practices in NY. One hundred children with WTVZV up to 8 yr of age and 323 children who received varicella vaccine (VV) were randomly selected.

RESULTS

WTVZV up to 8 yr of age is associated with decreased odds of subsequent asthma (exact logistic regression; OR = 0.12, 95% CI = 0.03-0.57, p = 0.003), allergic rhinoconjunctivitis (OR = 0.16, 95% CI = 0.05-0.49, p = 0.0003), and AD (OR = 0.57, 95% CI = 0.33-0.96, p = 0.02), but not food allergies (p = 0.78); decreased total serum IgE levels [mixed linear model, LSM (95% CI): 129.09 (33.22-501.63) vs. 334.21 (102.38-1091.04) IU/ml; p = 0.02] remained significant at all time intervals after WTVZV (<5, 5-10, and >10) compared with VV (p = 0.003-0.03). WTVZV was associated with decreased allergic sensitization (logistic regression, OR = 0.11, 95% CI = 0.03-0.38, p = 0.0004). WTVZV is also associated with persistently decreased numbers of peripheral blood lymphocytes (p < 0.0001) for up to 12 yr (p = 0.0003-0.047), monocytes (p = 0.002) for up to 16 yr (p < 0.001) and basophils at ages 4-6, 10-12, and 14-16 (p < 0.03).

CONCLUSION

WTVZV up to 8 yr of age protects against atopic disorders, which is likely mediated by suppression of IgE production and allergic sensitization, as well as altered leukocyte distributions.

Aldose reductase deficiency in mice protects from ragweed pollen extract (RWE)-induced allergic asthma

Background

Childhood hospitalization related to asthma remains at historically high levels, and its incidence is on the rise world-wide. Previously, we have demonstrated that aldose reductase (AR), a regulatory enzyme of polyol pathway, is a major mediator of allergen-induced asthma pathogenesis in mouse models. Here, using AR null (AR^-/-) mice we have investigated the effect of AR deficiency on the pathogenesis of ragweed pollen extract (RWE)-induced allergic asthma in mice and also examined the efficacy of enteral administration of highly specific AR inhibitor, fidarestat.

Methods

The wild type (WT) and AR^-/- mice were sensitized and challenged with RWE to induce allergic asthma. AR inhibitor, fidarestat was administered orally. Airway hyper-responsiveness was measured in unrestrained animals using whole body plethysmography. Mucin levels and Th2 cytokine in broncho-alveolar lavage (BAL) were determined using mouse anti-Muc5A/C ELISA kit and multiplex cytokine array, respectively. Eosinophils infiltration and goblet cells were assessed by H&E and periodic acid Schiff (PAS)-staining of formalin-fixed, paraffin-embedded lung sections. T regulatory cells were assessed in spleen derived CD4⁺CD25⁺ T cells population.

Results

Deficiency of AR in mice led to significantly decreased PENH, a marker of airway hyper-responsiveness, metaplasia of airway epithelial cells and mucus hyper-secretion following RWE-challenge. This was accompanied by a dramatic decrease in infiltration of eosinophils into sub-epithelium of lung as well as in BAL and release of Th2 cytokines in response to RWE-challenge of AR^-/- mice. Further, enteral administration of fidarestat significantly prevented eosinophils infiltration, airway hyper-responsiveness and also markedly increased population of T regulatory (CD4⁺CD25⁺FoxP3⁺) cells as compared to RWE-sensitized and challenged mice not treated with fidarestat.

Conclusion

Our results using AR^-/- mice strongly suggest the role of AR in allergic asthma pathogenesis and effectiveness of oral administration of AR inhibitor in RWE-induced asthma in mice supports the use of AR inhibitors in the treatment of allergic asthma.

Regulation of cyclooxygenase-2 and cytosolic phospholipase A2 gene expression by lipopolysaccharide through the RNA-binding protein HuR: involvement of NADPH oxidase, reactive oxygen species and mitogen-activated protein kinases

BACKGROUND AND PURPOSE Lipopolysaccharide (LPS)-induced expression of cyclooxygenase-2 (COX-2) and cytosolic phospholipase A(2) (cPLA(2) ) has been implicated in several respiratory diseases. HuR is known to enhance the expression of genes by binding to 3'-untranslated region (3'-UTR) of mRNA and stabilizing mRNA. However, the exact mechanisms by which HuR affects the stability of mRNA and modulates LPS-induced COX-2 and cPLA(2) expression in human tracheal smooth muscle cells (HTSMCs) are not known. EXPERIMENTAL APPROACH The expression of prostaglandin E(2) (PGE(2) ) was measured by ELISA, and pro-inflammatory proteins were determined by use of a promoter assay, PCR or Western blot analysis. Overexpression of siRNAs to knock down the target components was used to manipulate the expression of HuR. Release of reactive oxygen species (ROS) was detected by fluorescence dye. The activation of signalling components was assessed by comparing phosphorylation levels, localization of protein kinases or coimmunoprecipitation assay. KEY RESULTS LPS induced COX-2 and cPLA(2) expression via post-translational regulation of mRNA stabilization, which were attenuated by transfection with HuR siRNA in HTSMCs. In addition, LPS-stimulated NADPH oxidase activation and ROS generation were attenuated by the NADPH oxidase inhibitors diphenyleneiodonium chloride (DPI) and apocynin (APO). Generation of ROS induced phosphorylation of p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK and JNK1/2, which was attenuated by DPI and APO and the ROS scavenger N-acetylcysteine. CONCLUSIONS AND IMPLICATIONS These results suggested that in HTSMCs, LPS-induced COX-2 and cPLA(2) expression is mediated through NADPH oxidase/ROS-dependent MAPKs associated with HuR accumulation in the cytoplasm. Activated MAPKs may regulate the nucleocytoplasmic shuttling of HuR, and thus induce the cytoplasmic accumulation of HuR.

The genetics of asthma and allergic disease: a 21st century perspective

Asthma and allergy are common conditions with complex etiologies involving both genetic and environmental contributions. Recent genome-wide association studies (GWAS) and meta-analyses of GWAS have begun to shed light on both common and distinct pathways that contribute to asthma and allergic diseases. Associations with variation in genes encoding the epithelial cell-derived cytokines, interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP), and the IL1RL1 gene encoding the IL-33 receptor, ST2, highlight the central roles for innate immune response pathways that promote the activation and differentiation of T-helper 2 cells in the pathogenesis of both asthma and allergic diseases. In contrast, variation at the 17q21 asthma locus, encoding the ORMDL3 and GSDML genes, is specifically associated with risk for childhood onset asthma. These and other genetic findings are providing a list of well-validated asthma and allergy susceptibility genes that are expanding our understanding of the common and unique biological pathways that are dysregulated in these related conditions. Ongoing studies will continue to broaden our understanding of asthma and allergy and unravel the mechanisms for the development of these complex traits.

Non-antibiotic properties of tetracyclines as anti-allergy and asthma drugs

All available therapies for human allergic disease target IgE mediated pathologic responses after IgE has been produced. We are developing tetracyclines as anti-allergy drugs to prevent IgE production, based on our findings that minocycline or doxycycline treatment of allergic asthmatic humans significantly improves their asthma symptoms, reduces their oral steroid requirements, and strongly suppresses their ongoing IgE responses (ELISA, mast cell mediated cutaneous late phase responses); the tetracyclines also strongly suppress peak IgE responses of BPO-KLH sensitized mice (ELISPOT assay, ELISA, skin tests). The antibiotic activity of the tetracyclines is not required for suppression of IgE responses; inclusion of minocycline or doxycycline in sterile culture prevents anti-CD40/IL-4 mediated induction of memory IgE responses by PBMC of allergic asthmatic patients (ELISA), and induction of specific memory IgE responses by spleen cells of BPO-KLH sensitized mice (ELISPOT assay, ELISA). The tetracyclines affect an epsilon specific pathway because IgM, IgG and IgA responses did not decrease. Further, in humans, DTH responses to recall antigens did not decrease. In related studies, we found that two distinct T cell subsets: CD4+CD60 negative and CD8+CD60+ (CD60 is a ganglioside) (humans) and CD4+ Asialo GM1 ganglioside negative and CD8+Asialo GM1 ganglioside+ (mice), both are required for induction of memory IgE responses. Phosphorylated (phos) p38 MAP kinase, but not phos ERK or phos JNK expression by CD4+ and CD8+, including CD8+CD60+, T cells is increased in allergic asthmatic humans, as is IL-4 and IL-10 production. The tetracyclines appear to target T cell pathways to induce suppression of IgE responses because they suppress phos p38 MAP kinase expression by both CD4+ and CD8+, including CD8+CD60+, T cell subsets, and IL-4 and IL-10, while upregulating IL-2 and IFN gamma, and suppressing IgE responses. Our finding that tetracyclines do not require antibiotic activity to suppress IgE responses opens the door to development of new tetracycline-based and other therapeutics for human allergic disease.

Application of intelligent systems in asthma disease: designing a fuzzy rule-based system for evaluating level of asthma exacerbation

This paper discusses the capacities of artificial intelligence in the process of asthma diagnosing and asthma treatment. Developed intelligent systems for asthma disease have been classified in five categories including diagnosing, evaluating, management, communicative facilities, and prediction. Considering inputs, results, and methodologies of the systems show that by focusing on meticulous analysis of quality of life as an input variable and developing patient-based systems, under-diagnosing and asthma morbidity and mortality would decrease significantly. Regard to the importance of accurate evaluation in accurate prescription and expeditious treatment, the methodology of developing a fuzzy expert system for evaluating level of asthma exacerbation is presented in this paper too. The performance of this system has been tested in Asthma, Allergy, and Immunology Center of Iran using 25 asthmatic patients. Comparison between system's results and physicians' evaluations using Kappa coefficient (K) reinforces the value of K = 1. In addition this system assigns a degree in gradation (0-10) to every patient representing the slight differences between patients assigned to a specific category.

The T-helper cell type 1 immune response to gram-negative bacterial infections is impaired in COPD

RATIONALE

The increased susceptibility to bacterial infections in chronic obstructive pulmonary disease (COPD) is critical for exacerbations. Toll-like receptor-4 (TLR4) detects bacteria via LPS and induces IFN-γ-based immune responses. The direct responsiveness of Th1 lymphocytes to LPS is disputed because they lack surface expression of the TLR4 coreceptor CD14.

OBJECTIVES

We hypothesized that the Th1-mediated adaptive immune response to bacterial infections is impaired in COPD.

METHODS

LPS-induced TLR4 expression and IFN-γ release in and from ex vivo-generated Th1 cells was compared among nonsmokers (n = 14), smokers without COPD (n = 13), and smokers with COPD (n = 25) via quantitative reverse transcription polymerase chain reaction, Western blot, and ELISA. TLR4 transfection experiments were performed to functionally link receptor to IFN-γ dysregulation in COPD.

MEASUREMENTS AND MAIN RESULTS

Short-chain LPS from Salmonella species and nontypeable Haemophilus influenzae and nontypeable Haemophilus influenzae whole-cell extract all induced TLR4 expression via TLR4/MyD88/IRAK/mitogen-activated protein-kinase signaling and IFN-γ release via TLR4/TRIF/IKKε/TBK1 signaling in Th1 cells of nonsmokers. These effects were all impaired in smokers with and without COPD. The LPS responses were partially dependent on soluble CD14 and correlated positively to lung-function parameters but negatively to cigarette smoking (pack-years). Endogenous MyD88/IRAK signaling antagonists were up-regulated in Th1 cells of smokers and COPD, and TLR4 overexpression in Th1 cells of COPD restored LPS-dependent IFN-γ release.

CONCLUSIONS

Th1 cells directly respond to short-chain LPS. Cigarette smoking suppresses Th1-mediated immune responses to gram-negative bacterial infections by interfering with MyD88/IRAK signaling thereby reducing LPS-induced TLR4 expression. This can explain the increased susceptibility to bacterial infections in COPD. Targeting TLR signaling might be useful to reduce exacerbation rates.

Tolerizing allergic responses in the lung

The absolute requirement of the pulmonary immune system is to limit the inflammatory consequences of inhaled infectious agents while maintaining tolerance to harmless aeroallergens. This tolerance is maintained by a complex network of cells and molecules interacting with lung stromal cells. However, in some individuals there is a breakdown in tolerance to particles such as pollens, animal dander, or dust, resulting in the development of allergic pathology. Emerging evidence suggests that this breakdown in tolerance is influenced by the genetic background of individuals as well as environmental considerations such as early exposure to respiratory pathogens. Further understanding of the mechanisms used by the pulmonary immune system to maintain tolerance might result in exploitation of novel avenues for therapy to treat the growing number of chronic asthmatic patients.

Epidemiology of asthma: risk factors for development

This comprehensive review of the recent literature was undertaken to determine the current state of knowledge of the risk factors involved in the development of asthma in order to focus investigations in a proposed new longitudinal birth cohort study. The origins of asthma appear to lie in the prenatal and early postnatal period, and renewed investigations in this period with long-term close follow-up and objective phenotypic characterization will help to unravel the role of the multiple putative environmental factors in the development of asthma. It is only after understanding these effects that one can hope to design rational prevention studies for asthma.

Role of infection in the development and exacerbation of asthma

Respiratory infections are associated with wheezing illnesses in all ages and may also impact the development and severity of asthma. Respiratory tract infections caused by viruses, Chlamydophila or Mycoplasma have been hypothesized to have significant roles in the pathogenesis of asthma. Progress is being made toward establishing the mechanisms by which these agents can cause acute wheezing and impact the pathophysiology of asthma. Host factors probably contribute to the risk of asthma inception and exacerbation, and these contributions may also vary with respect to early- versus adult-onset disease. This review discusses these various associations as they pertain to the development and exacerbation of asthma.

Review: Collectins link innate and adaptive immunity in allergic airway disease

Although the lipoprotein complex of pulmonary surfactant has long been recognized as essential for reducing lung surface tension, its role in lung immune host defense has only relatively recently been elucidated. Surfactant-associated proteins A (SP-A) and D (SP-D) can attenuate bacterial and viral infection and inflammation by acting as opsonins and by regulating innate immune cell functions. Surfactant-associated protein A and D also interact with antigen-presenting cells and T cells, thereby linking the innate and adaptive immune systems. A recent study from our laboratory demonstrated that mice deficient in SP-A have enhanced susceptibility to airway hyper-responsiveness and lung inflammation induced by Mycoplasma pneumonia, an atypical bacterium present in the airways of approximately 50% of asthmatics experiencing their first episode, and further supports an important role for SP-A in the host response to allergic airway disease. Animal and human studies suggest that alterations in the functions or levels of SP-A and SP-D are associated with both infectious and non-infectious chronic lung diseases such as asthma. Future studies are needed to elucidate whether alterations in SP-A and SP-D are a consequence and/or cause of allergic airway disease.

Protection against the allergic airway inflammation depends on the modulation of spleen dendritic cell function and induction of regulatory T cells in mice

Background

Allergen-induced imbalance of specific T regulatory (Treg) cells and T helper 2 cells plays a decisive role in the development of immune response against allergens.

Objective

To evaluate effects and potential mechanisms of DNA vaccine containing ovalbumin (OVA) and Fc fusion on allergic airway inflammation.

Methods

Bronchoalveolar lavage (BAL) levels of inflammatory mediators and leukocyte infiltration, expression of CD_11c⁺CD₈₀⁺ and CD_11c⁺CD₈₆⁺ co-stimulatory molecules in spleen dendritic cells (DCs), circulating CD₄⁺ and CD₈⁺ T cells, Foxp3⁺ in spleen CD₄⁺ T cells and spleen CD₄⁺ T cells were measured in OVA-sensitized and challenged animals pretreated with pcDNA, OVA-pcDNA, Fc-pcDNA, and OVA-Fc-pcDNA.

Results

OVA-Sensitized and challenged mice developed airway inflammation and Th2 responses, and decreased the proliferation of peripheral CD₄⁺and CD₈⁺ T cells and the number of spleen Foxp₃⁺ Treg. Those changes with increased INF-γ production and reduced OVA-specific IgE production were protected by the pretreatment with OVA-Fc-pcDNA.

Conclusion

DNA vaccine encoding both Fc and OVA showed more effective than DNA vaccine encoding Fc or OVA alone, through the balance of DCs and Treg.

Polyinosine-polycytidylic acid stimulates versican accumulation in the extracellular matrix promoting monocyte adhesion

Viral infections are known to exacerbate asthma and other lung diseases in which chronic inflammatory processes are implicated, but the mechanism is not well understood. The viral mimetic, polyinosine-polycytidylic acid, causes accumulation of a versican- and hyaluronan-enriched extracellular matrix (ECM) by human lung fibroblasts with increased capacity for monocyte adhesion. The fivefold increase in versican retention in this ECM is due to altered compartmentalization, with decreased degradation of cell layer-associated versican, rather than an increase in total accumulation in the culture. This is consistent with decreased mRNA levels for all of the versican splice variants. Reduced versican degradation is further supported by low levels of the epitope, DPEAAE, a product of versican digestion by a disintegrin-like and metallopeptidase with thrombospondin type 1 motif enzymes, in the ECM. The distribution of hyaluronan is similarly altered with a 3.5-fold increase in the cell layer. Pulse-chase studies of radiolabeled hyaluronan show a 50% reduction in the rate of loss from the cell layer over 24 hours. Formation of monocyte-retaining, hyaluronidase-sensitive ECMs can be blocked by the presence of anti-versican antibodies. In comparison, human lung fibroblasts treated with the cytokines, IL-1beta plus TNF-alpha, synthesize increased amounts of hyaluronan, but do not retain it or versican in the ECM, which, in turn, does not retain monocytes. These results highlight an important role for versican in the hyaluronan-dependent binding of monocytes to the ECM of lung fibroblasts stimulated with polyinosine-polycytidylic acid.

Outpatient management of asthma in children age 5-11 years: guidelines for practice

PURPOSE

To increase awareness among nurse practitioners (NPs) regarding diagnostic and treatment guidelines for asthma for the 5-11 year age group recently updated by the National Asthma Education Prevention Program-Expert Panel 3 (NAEPP-EPR3).

DATA SOURCES

NAEPP-EPR3 guidelines for the diagnosis and management of asthma released from the National Heart, Lung, and Blood Institute in August 2007, selected clinical trials, meta-analyses, and clinical reviews.

CONCLUSIONS

Recent research has revealed that children suffering from asthma in the United States are underdiagnosed and their asthma is poorly controlled. Compelling evidence supports that children classified as having persistent asthma following NAEPP-EPR3 guidelines benefit from daily inhaled corticosteroid therapy, yet many are misclassified and undertreated.

IMPLICATIONS FOR PRACTICE

With application of current guidelines from NAEPP-EPR3, NPs can more effectively assess, diagnose, treat, and foster a collaborative self-management plan for children age 5-11 years. These interventions will result in an improved quality of life and decreased health risks for this young population.

A thymic stromal lymphopoietin gene variant is associated with asthma and airway hyperresponsiveness

BACKGROUND

The epithelial cell-derived protein thymic stromal lymphopoietin stimulates dendritic and mast cells to promote proallergic T(H)2 responses. Studies of transgenic expression of thymic stromal lymphopoietin and its receptor knockout mice have emphasized its critical role in the development of allergic inflammation. Association of genetic variation in thymic stromal lymphopoietin with IgE levels has been reported for human subjects.

OBJECTIVE

The aim of this study was to evaluate the relationship between variants of thymic stromal lymphopoietin and asthma and related phenotypes.

METHODS

We selected 6 single nucleotide polymorphisms in thymic stromal lymphopoietin and genotyped 5565 individuals from 4 independent asthma studies and tested for association with asthma, atopy, atopic asthma, and airway hyperresponsiveness by using a general allelic likelihood ratio test. P values were corrected for the effective number of independent single nucleotide polymorphisms and phenotypes.

RESULTS

The A allele of rs1837253, which is 5.7 kb upstream of the transcription start site of the gene, was associated with protection from asthma, atopic asthma, and airway hyperresponsiveness, with the odds ratios and corrected P values for each being 0.79 and 0.0058; 0.75 and 0.0074; and 0.76 and 0.0094, respectively. Associations between thymic stromal lymphopoietin and asthma-related phenotypes were the most statistically significant observations in our study, which has to date examined 98 candidate genes. Full results are available online at http://genapha.icapture.ubc.ca/.

CONCLUSIONS

A genetic variant in the region of the thymic stromal lymphopoietin gene is associated with the phenotypes of asthma and airway hyperresponsiveness.

Expression profiling of genes related to asthma exacerbations

BACKGROUND

Asthma is a chronic airway inflammatory disease; however, the molecular mechanisms that underlie asthma exacerbation are only partially understood.

OBJECTIVE

To identify gene expression signatures that reflect the acute exacerbation of asthma, we examined the differential expression of genes during asthma exacerbation and stable condition by using microarray analysis.

METHODS

The subjects were mite-sensitive asthmatic children and non-asthmatic control children. The children were divided into four groups (AE: asthma exacerbation, n=12; SA: stable asthma, n=11; IC: infected control, n=6; and NC: non-infected control, n=5). Total RNA was extracted from peripheral blood mononuclear cells and subjected to microarray analysis with Illumina Human Ref8 BeadChip arrays. Welch's t-test was performed to identify genes whose expression was altered during asthma exacerbation. Quantitative real-time RT-PCR was performed on samples collected from 43 asthmatic children and 11 control children to verify the microarray results.

RESULTS

The expression of 137/16 genes was significantly up/down-regulated during asthma exacerbation assessed by microarray analysis. Of the genes, 62 were also differentially expressed during upper respiratory infection. Many of the asthma exacerbation related genes were involved in defence responses and responses to external stimuli, but these associations disappeared after excluding the infection-related genes. Quantitative real-time RT-PCR confirmed that the genes related (S100A8 and GAS6) and unrelated to infections (CD200 and RBP7) were differentially expressed during asthma exacerbation (P<0.01).

CONCLUSIONS

Previously unidentified immune responses during asthma exacerbation may provide further clarification of the molecular mechanisms underlying asthma.

Eliminating asthma disparities: is there evidence of progress?

PURPOSE OF REVIEW

In spite of numerous efforts, asthma rates in the United States remain historically high and disparities persist among low-income and minority populations. This review assesses the current status of asthma inequities from the perspective of disease development, progression, and outcomes.

RECENT FINDINGS

Recent findings highlight the complex and multifactorial nature of asthma. There is a clear line of emerging evidence suggestive of important hierarchical relationships between the predisposed or affected individual and his or her intrapersonal life, familial relationships, social networks, and broader community.

SUMMARY

Approaches in basic, clinical, and translational asthma research must be modified to account for the social construct of race and to detangle complex interactions of contributing factors at and across the individual and community level. However, there are a number of obvious opportunities to dramatically reduce asthma disparities at hand.

Rural health disparities in asthma care and outcomes

Fifty-nine million Americans (21% of the US population) live in rural areas of the United States. Compared with persons living in urban areas of the United States, rural populations have lower income, a higher rate of government versus private insurance, and decreased access to health care. Although there are reports of lower asthma prevalence in rural areas, the majority of these data have been published on international populations, with few available studies looking at American urban versus rural asthma prevalence on a national scale or comparing rural with nearby urban cohorts in the United States. A large body of literature, mainly generated from studies of rural Europe, suggests that lower prevalence might be due to beneficial effects of exposure to farm environments, but the extent to which this applies to the rural United States, where a smaller proportion of the population engages in farming, is unclear. The United States has the additional covariate of having a higher proportion of African Americans, who have a greater asthma burden than whites independent of socioeconomic status, clustered in cities. There are data indicating that rural patients have increased difficulty obtaining health care in general and limited data suggesting that they receive inferior care for asthma. Future work is needed to more clearly define asthma prevalence and morbidity among residents of the rural United States, as well as to identify interventions effective in this population.

Activation of Toll-like receptor 3 augments myofibroblast differentiation

Airway remodeling is observed in the airways of patients with asthma, and differentiation of fibroblasts to myofibroblasts plays a critical role in the progress of airway remodeling. Viral infection induces not only the disease development and exacerbations but also airway remodeling. The aim of this study was to evaluate whether the activation of Toll-like receptor 3 (TLR3) can affect the differentiation of fibroblasts to myofibroblasts and the extracellular matrix (ECM) protein production. Human fetal lung fibroblasts (HFL-1) and adult lung fibroblasts were treated with a synthetic double-stranded RNA, polyinosine-polycytidylic acid (poly[I:C]) and the expression of alpha-smooth muscle actin (alpha-SMA), a marker of myofibroblast differentiation, was evaluated. The release of transforming growth factor-beta(1) (TGF-beta(1)) and ECM protein production were assessed. The effect of anti-TGF-beta antibody on the alpha-SMA and ECM production was also assessed. Poly(I:C) significantly augmented the alpha-SMA expression (P < 0.01) and release of TGF-beta(1) (P < 0.01) compared with control. Bafilomycin, an inhibitor of TLR3 signaling, diminished poly(I:C)-augmented TGF-beta(1) release. Anti-TGF-beta(1) antibody inhibited the poly(I:C)-augmented alpha-SMA expression. Poly(I:C) enhanced translocation of nuclear factor-kB (NF-kappaB) and interferon regulatory factor-3 (IRF-3) into the nucleus. Poly(I:C)-augmented TGF-beta(1) release was almost completely blocked by NF-kappaB inhibitors, but not by silencing IRF-3. The production of fibronectin and collagen I expression were significantly increased by poly(I:C) (P < 0.01) and they were inhibited by anti-TGF-beta antibody. These results suggest that activation of TLR3 can affect the differentiation to myofibroblasts and enhance ECM production via the NF-kappaB-TGF-beta(1)-dependent pathway.

Diagnosis and management of work-related asthma: American College Of Chest Physicians Consensus Statement

BACKGROUND

A previous American College of Chest Physicians Consensus Statement on asthma in the workplace was published in 1995. The current Consensus Statement updates the previous one based on additional research that has been published since then, including findings relevant to preventive measures and work-exacerbated asthma (WEA).

METHODS

A panel of experts, including allergists, pulmonologists, and occupational medicine physicians, was convened to develop this Consensus Document on the diagnosis and management of work-related asthma (WRA), based in part on a systematic review, that was performed by the University of Alberta/Capital Health Evidence-Based Practice and was supplemented by additional published studies to 2007.

RESULTS

The Consensus Document defined WRA to include occupational asthma (ie, asthma induced by sensitizer or irritant work exposures) and WEA (ie, preexisting or concurrent asthma worsened by work factors). The Consensus Document focuses on the diagnosis and management of WRA (including diagnostic tests, and work and compensation issues), as well as preventive measures. WRA should be considered in all individuals with new-onset or worsening asthma, and a careful occupational history should be obtained. Diagnostic tests such as serial peak flow recordings, methacholine challenge tests, immunologic tests, and specific inhalation challenge tests (if available), can increase diagnostic certainty. Since the prognosis is better with early diagnosis and appropriate intervention, effective preventive measures for other workers with exposure should be addressed.

CONCLUSIONS

The substantial prevalence of WRA supports consideration of the diagnosis in all who present with new-onset or worsening asthma, followed by appropriate investigations and intervention including consideration of other exposed workers.

The ABCs of asthma control

The new asthma guidelines have introduced impairment and risk assessments into the management of asthma. Impairment assessment is based on symptom frequency and pulmonary function, whereas risk assessment is based on exacerbation frequency and severity. These 2 measures determine the initial severity of asthma in the untreated patient as well as the degree of control in asthma once treatment has been initiated. The focus on asthma control is important because the attainment of control correlates with a better quality of life and reduction in health care use. We describe 4 easy steps to achieving asthma control in the ambulatory practice setting: (1) a standardized assessment of asthma symptoms using a 5-question assessment tool called the Asthma Control Test, (2) a simple mnemonic that provides a systematic review of the comorbidities and clinical variables that contribute to uncontrolled asthma, (3) directed patient education, and (4) a schedule for ongoing care. Most if not all patients can achieve good control of their asthma with optimal care through an active partnership with their health care professionals.

Natural history of asthma: persistence versus progression-does the beginning predict the end?

Environmental exposures during the early years and airway obstruction that develops during this time, in conjunction with genetic susceptibility, are important factors in the development of persistent asthma in childhood. Established risk factors for childhood asthma include frequent wheezing during the first 3 years, a parental history of asthma, a history of eczema, allergic rhinitis, wheezing apart from colds, and peripheral blood eosinophilia, as well as allergic sensitization to aeroallergens and certain foods. Risk factors for the development of asthma in adulthood remain ill defined. Moreover, reasons for variability in the clinical course of asthma--persistence in some individuals and progression in others--remain an enigma. The distinction between disease persistence and disease progression suggests that these are different entities or phenotypes. There is currently no consensus on whether disease progression requires either airway inflammation or airway remodeling or the combination of the two. For patients with irreversible airway obstruction, inflammation might, in part, be necessary but perhaps not entirely sufficient to induce the irreversible component, some of which could be attributed to alterations in the structure of the bronchial wall. Intervening with intermittent or daily inhaled corticosteroids in high-risk infants and children does not prevent disease progression or impaired lung growth. These findings, however, might not apply to adults, and further study in adults is needed to determine the effect of inhaled corticosteroid therapy on disease progression.

Eosinophils and asthma

Recruitment and activation of eosinophils into the airways of asthma patients is suggested to be a contributing causative agent in the histopathologies and lung dysfunction that are characteristic of asthma. Recent studies in mouse models of asthma and in human patients implicate eosinophils in immune regulation and remodeling in the lung in addition to their hypothesized role as destructive agents. Specifically, eosinophils not only participate in release of granule proteins, lipid mediators, reactive oxygen species, cytokines, and growth factors but also function through complex cell-cell interactions to elicit chronic T helper 2 inflammation in the lung. This review highlights the roles of eosinophils in asthma.

Severe asthma in adults: what are the important questions?

The term severe refractory asthma (SRA) in adults applies to patients who remain difficult to control despite extensive re-evaluation of diagnosis and management following an observational period of at least 6 months by a specialist. Factors that influence asthma control should be recognized and adequately addressed prior to confirming the diagnosis of SRA. This report presents statements according to the literature defining SRA in order address the important questions. Phenotyping SRA will improve our understanding of mechanisms, natural history, and prognosis. Female gender, obesity, and smoking are associated with SRA. Atopy is less frequent in SRA, but occupational sensitizers are common inducers of new-onset SRA. Viruses contribute to severe exacerbations and can persist in the airways for long periods. Inflammatory cells are in the airways of the majority of patients with SRA and persist despite steroid therapy. The T(H)2 immune process alone is inadequate to explain SRA. Reduced responsiveness to corticosteroids is common, and epithelial cell and smooth muscle abnormalities are found, contributing to airway narrowing. Large and small airway wall thickening is observed, but parenchymal abnormalities may influence airway limitation. Inhaled corticosteroids and bronchodilators are the mainstay of treatment, but patients with SRA remain uncontrolled, indicating a need for new therapies.

Prioritizing environmental issues around the world: opinions from an international Central and Eastern European environmental health conference

BACKGROUND

As the next generation of scientists enters the field of environmental health, it is imperative that they view their contributions in the context of global environmental stewardship. In this commentary, a group of international graduate students facilitated by three experienced environmental health scientists present their views on what they consider to be the global environmental health concerns of today. This group convened initially in October 2004 at an international health conference in Prague, Czech Republic.

OBJECTIVES

In this report we identify perceived environmental health concerns that exist around the world, with a focus on Central and Eastern Europe. Additionally, we address these perceived problems and offers some potential solutions.

DISCUSSION

At the meeting, students were invited to participate in two panel discussions. One group of young international scientists identified several significant global environmental health concerns, including air pollution, occupational hazards, and risk factors that may exacerbate current environmental health issues. The second panel determined that communication, education, and regulation were the mechanisms for addressing current environmental challenges.

CONCLUSIONS

In this commentary we expand on the views presented at the meeting and represent the concerns of young investigators from nine different countries. We provide ideas about and support the exchange of information between developed and developing countries on how to handle the environmental health challenges that face the world today.