Exposure to traffic-related particles and endotoxin during infancy is associated with wheezing at age 3 years

RATIONALE

Murine models demonstrate a synergistic production of reactive oxygen species on coexposure to diesel exhaust particles and endotoxin.

OBJECTIVES

It was hypothesized that coexposure to traffic-related particles and endotoxin would have an additive effect on persistent wheezing during early childhood.

METHODS

Persistent wheezing at age 36 months was assessed in the Cincinnati Childhood Allergy and Air Pollution Study, a high-risk birth cohort. A time-weighted average exposure to traffic-related particles was determined by applying a land-use regression model to the homes, day cares, and other locations where children spent time from birth through age 36 months. Indoor levels of endotoxin were measured from dust samples collected before age 12 months. The relationship between dichotomized (<or>or=75th percentile) traffic-related particle and endotoxin exposure and persistent wheezing, controlling for potential covariates, was examined.

MEASUREMENTS AND MAIN RESULTS

Persistent wheezing at age 36 months was significantly associated with exposure to increased levels of traffic-related particles before age 12 months (OR = 1.75; 95% confidence interval, 1.07-2.87). Coexposure to endotoxin had a synergistic effect with traffic exposure on persistent wheeze (OR = 5.85; 95% confidence interval, 1.89-18.13) after adjustment for significant covariates.

CONCLUSIONS

The association between traffic-related particle exposure and persistent wheezing at age 36 months is modified by exposure to endotoxin. This finding supports prior toxicological studies demonstrating a synergistic production of reactive oxygen species after coexposure to diesel exhaust particles and endotoxin. The effect of early versus later exposure to traffic-related particles, however, remains to be studied because of the high correlation between exposure throughout the first 3 years of life.

A review of the efficacy of desloratadine, fexofenadine, and levocetirizine in the treatment of nasal congestion in patients with allergic rhinitis

BACKGROUND

Nasal congestion is the most troublesome symptom of allergic rhinitis (AR). First-generation and older second-generation antihistamines, while effective against nasal itching, sneezing, and rhinorrhea, have limited efficacy in relieving nasal congestion.

OBJECTIVE

This review included nasal challenge studies and clinical trials that reported the effects on nasal congestion of the newer second-generation antihistamines desloratadine, fexofenadine, and levocetirizine.

METHODS

MEDLINE and EMBASE were searched for nasal challenge studies and clinical trials published in English between January 1, 1991, and January 31, 2009, using the following terms, alone or in combination: antihistamines, second-generation antihistamines, allergic rhinitis, intermittent allergic rhinitis, perennial allergic rhinitis, persistent allergic rhinitis, seasonal allergic rhinitis, nasal challenge, nasal blockage, and nasal congestion. Studies that were not active or placebo controlled, that did not evaluate change in nasal congestion scores, or that focused on treatments other than desloratadine, fexofenadine, and levocetirizine for nasal congestion associated with AR were excluded.

RESULTS

Twenty-six clinical trials met the criteria for inclusion in the review. In 11 placebo-controlled trials that included objective assessment of nasal congestion, desloratadine, fexofenadine, and levocetirizine were associated with reductions in the severity of nasal congestion through maintenance of nasal airflow. The mean AUC for nasal airflow over 6 hours was significantly greater with desloratadine compared with placebo in 3 studies (P < 0.05); placebo-controlled trials of fexofenadine and levocetirizine had similar results. In 25 placebo- and active-controlled trials that reported subject-rated symptom scores, the 3 newer antihistamines were efficacious in the treatment of nasal congestion associated with AR. In 10 trials that reported objective and/or subjective measures, desloratadine was associated with significant improvements in nasal congestion compared with placebo (P < or = 0.05), beginning as early as the first 2 hours after allergen challenge. Fexofenadine was associated with significantly lower nasal congestion scores compared with placebo in 4 studies (P <- 0.05); nasal congestion scores were significantly reduced with levocetirizine in 3 placebo-controlled trials (P < or = 0.005).

CONCLUSIONS

In the studies reviewed, desloratadine, fexofenadine, and levocetirizine were effective in relieving the nasal congestion associated with AR compared with placebo. This effect began as early as day 2 and was consistent and progressive throughout treatment. Desloratadine, fexofenadine, and levocetirizine are appropriate options for the treatment of nasal congestion in patients with AR.

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

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

Exposure of pregnant mice to an air pollutant aerosol increases asthma susceptibility in offspring

Air pollution contributes to both exacerbation and development of bronchial asthma. Studies showed that coexposure to air pollution directly promotes sensitization to inhaled allergen in neonatal mice. The aim of this study was to investigate whether prenatal exposure to air pollution could also increase susceptibility to development of asthma in early life. Pregnant female BALB/c mice were exposed to aerosolized leachate of residual oil fly ash (ROFA, 50 mg/ml, 30 min) at 5, 3, and 1 d before delivery. Offspring were treated once at 3 d of age with ovalbumin (OVA, 5 mug) and alum (ip), an intentionally suboptimal dose for sensitization, exposed to aerosolized OVA (1%, 10 min) at 12-14 d or 32-35 d of age, and evaluated 2 d after the final exposure. The offspring of ROFA-exposed mothers (ROFA group) revealed increasing airway hyperresponsiveness (higher enhanced pause [Penh] to methacholine challenge) and elevated substantial numbers of eosinophils in the bronchoalveolar lavage flued (BALF). Histopathology revealed prominent inflammation in the lungs of ROFA group and showed increased allergen-specific IgE and IgG1 levels. Their cultured splenocytes showed an enhanced interleukin (IL)-4/interferon (IFN)-gamma cytokine, indicating Th2 skewed immunity. Data indicate that exposure of pregnant female mice to an air pollutant aerosol increased asthma susceptibility in their offspring.

Age-specific relationship between CD14 and atopy in a cohort assessed from age 8 to 25 years

CD14 influences postnatal switching of T helper cell responses. CD14 C-159T has been associated with altered CD14 and IgE levels in cross-sectional studies. Identifying whether associations vary with age requires data from children of the same age followed longitudinally over many years. In this study, an unselected population with extensive longitudinal data was used to test the hypothesis that CD14 C-159T was associated with early-onset atopy. A total of 305 subjects were assessed on up to seven occasions between ages 8 and 25 years by questionnaire, histamine challenge, and skin prick test. For atopy, airway hyperresponsiveness (AHR), and wheeze, each subject was classified as having early onset, late onset, or no disease onset during follow-up. Compared with subjects with -159CT and -159TT, subjects with -159CC had an odds ratio of 2.2 (p = 0.018) for early-onset atopy and an odds ratio of 2.6 (p = 0.019) for early-onset AHR. Cross-sectional analysis showed increased prevalence of -159CC in subjects with atopy and AHR in childhood but not adulthood. These data suggest that the influence of CD14 -159C on the atopic phenotype may be age specific, exerting an effect during midchildhood, which is no longer apparent by early adulthood.

Laboratory animal allergy: an update

Allergic reactions are among the most common conditions affecting the health of workers involved in the care and use of research animals. Between 11 and 44% of the individuals working with laboratory animals report work-related allergic symptoms. Of those who become symptomatic, 4 to 22% may eventually develop occupational asthma that can persist even after exposure ceases. Allergic symptoms consist of rashes where animals are in contact with the skin, nasal congestion and sneezing, itchy eyes, and asthma (cough, wheezing, and chest tightness). The generation of immunoglobulin E (IgE) antibodies is a prerequisite for the production of allergic symptoms. The mechanism by which IgE antibodies develop is becoming clearer. The propensity to produce IgE is genetically determined, and pre-existing allergy may be a risk factor for the development of laboratory animal allergy (LAA). However, exposure to animal allergens is the major risk factor for the development of LAA. Techniques to measure the airborne concentration of laboratory animal allergens have been developed. Research on animal allergens themselves indicates that many of the mouse and rat urinary proteins belong to a family of proteins called lipocalins, which share sequence homology with antigens of the parasitic agent that causes schistosomiasis. The fact that parasite infections also trigger IgE antibody responses may account for the development of LAA in persons who have never had any previous allergy. The prevention of LAA should be a major goal of an effective health and safety program in the animal research facility, and it can be accomplished by education and training of employees, reduction of exposure (including the use of personal protective gear), and changes in facility design. Medical surveillance programs can also play a role in improving health of individuals working with laboratory research animals. Early recognition of symptoms and evidence of sensitization can lead to interventions to reduce exposure and thereby avoid the long-term health consequences of LAA.

Age-related T cell responses to allergens in childhood

BACKGROUND

T cell priming, as determined by allergen-induced proliferative responses, is believed to occur principally in early childhood in both atopic and non-atopic infants under the influence of multiple factors including environmental allergen exposure. It is considered that T cell priming with expansion of Th2 cells is a crucial factor in the development of atopic disease.

OBJECTIVE

To examine T cell priming to commonly encountered allergens in childhood in relation to age.

METHODS

In a cross-sectional study T cell proliferation in relation to age was examined for three common allergens, ovalbumin (OVA), house dust mite (HDM) and rye grass pollen (RYE), in atopic and non-atopic children. The effect of age on Th1 (IFN-gamma) and Th2 (IL-5 and IL-13) cytokine production in response to these allergens was investigated to examine the possibility of immune deviation with time.

RESULTS

A significant increase in T cell proliferation with age was observed with RYE among atopic children only. However, the same was not observed with the two other allergens studied (i.e. OVA and HDM). In addition, RYE-induced (but not HDM or OVA) cytokine production showed an increased Th2 deviation with age as reflected in the increasing IL-5/IFN-gamma and IL-13/IFN-gamma ratios only among the atopic subjects with rye grass pollen sensitivity.

CONCLUSION

These findings suggest that grass pollen sensitivity in childhood is accompanied by a progressive accumulation of allergen-primed T cells and progressive deviation of the allergen-induced cytokine response towards a Th2 response in atopic subjects throughout childhood.

The use of anti-IgE in the treatment of allergic asthma

Allergic sensitization plays a significant role in the development of asthma in many patients. IgE-mediated immune responses play a central role in the pathogenesis of this condition. The development of a treatment that interrupts this pathway is particularly desirable to prevent downstream events. Large-scale trials in patients ranging in age from 6 to 76 years have shown that omalizumab therapy is safe and effective in the treatment of severe allergic asthma. This is particularly true in patients who experience poor disease control despite high doses of inhaled steroids or need oral steroids for control of their disease. These patients are at risk for severe exacerbations despite recommended therapy, and anti-IgE therapy has proved to reduce these episodes. Early aggressive therapy of asthma is needed for maximum control in all age groups. Despite the efficacy of inhaled steroids there is a reluctance to use these agents, especially in younger children. Because of these concerns a long-acting treatment is especially desirable. Because of imperfect effort or technique limiting inhaled medications, introduction of an effective agent that could be administered parenterally at long intervals also is very important. Allergic rhinitis is a co-existing problem in many patients with allergic asthma. Immunotherapy trials have suggested that early intervention with immunotherapy and allergic rhinitis patients may actually prevent the development of asthma. Early treatment of patients with anti-IgE may also have benefits, particularly in those who have concomitant allergic rhinitis in addition to allergic asthma. Although omalizumab has not yet received Food and Drug Administration approval in the United States, it shows great promise in the management of patients requiring high doses of inhaled or oral corticosteroids for control of their disease and to prevent exacerbations of asthma in such patients. Reductions in high doses of inhaled or oral corticosteroids may prevent long-term complications of these treatments.

Maternal stress and T-cell differentiation of the developing immune system: possible implications for the development of asthma and atopy

The constant increase in asthma and atopy prevalences--despite improved treatment and knowledge of many aspects of the diseases--has raised growing concern. Accumulating evidence suggests that these increases in atopic diseases are largely attributable to environmental and lifestyle factors, and the lack of systemic childhood infections has in many studies emerged as a major factor. In addition to current high standards of hygiene and the lack or scarcity of such infections, another factor characteristic of our present-day lives could be involved. This review briefly outlines the possibility that prolonged maternal stress associated with sustained excessive cortisol secretion could affect the developing immune system--especially T(H)1/T(H)2 cell differentiation--and further increase the susceptibility to asthma and atopy in genetically predisposed individuals. This hypothesis is critically evaluated in the light of current knowledge.

Development of new IgE specificities to allergenic components in birch pollen extract during specific immunotherapy studied with immunoblotting and Pharmacia CAP System

BACKGROUND

New IgE sensitizations to proteins in allergen extracts have been shown to occur during allergen-specific immunotherapy (IT). However little is known about the kinetics of the changes in antibody reactivities.

METHODS

Twenty-four allergic children and adults were treated with birch pollen rush IT (RIT). Fifteen matched patients served as allergic controls. Sera were obtained at regular intervals for up to three years and analyzed with immunoblotting and Pharmacia CAP System with recombinant (r) birch pollen allergens (rBet v 1, rBet v 2, and rBet v 4).

RESULTS

All birch-allergic patients had specific IgE to the major birch pollen allergen Bet v 1, but only three had IgE to rBet v 2 and/or rBet v 4 at the beginning of the study. New IgE sensitizations developed in 65% of the birch RIT-treated patients when studied by immunoblotting. Twenty-nine percent of the patients developed new sensitizations to rBet v 2 and/or rBet v 4 during RIT as measured by Pharmacia CAP System. Generally, new specific IgE reactivities occurred after at least one year of RIT, and only at low levels (< 1 kUA/l).

CONCLUSIONS

Sensitization to additional allergenic pollen components frequently occurs during prolonged birch RIT. However, the IgE levels are low and the clinical relevance is not known.

Increased Th1 and Th2 allergen-induced cytokine responses in children with atopic disease

BACKGROUND

Polyclonal cytokine responses following stimulation of T cells with mitogens or superantigens provides information on cytokine production from a wide range of T cells. Alternatively allergen-induced T cell responses can provide information on cytokine production by allergen-reactive T cells. While there is evidence of increased Th2 and reduced Th1 cytokine production following T cell stimulation with non-specific mitogens and superantigens, the evidence that Th1 cytokine production to allergens is decreased in line with a postulated imbalance in Th1/Th2 responses is unclear, with studies finding decreased, no difference or increased IFN-gamma responses to allergens in atopic subjects.

OBJECTIVE

To examine childhood polyclonal and allergen-induced cytokine responses in parallel to evaluate cytokine imbalances in childhood atopic disease.

METHODS

PBMC cytokine responses were examined in response to a polyclonal stimulus, staphylococcal superantigen (SEB), in parallel with two inhalant allergens, house dust mite (HDM) and rye grass pollen (RYE), and an ingested allergen, ovalbumin (OVA), in (a) 35 healthy children (non-atopic) and (b) 36 children with atopic disease (asthma, eczema and/or rhinitis) (atopic).

RESULTS

Atopic children had significantly reduced IFN-gamma and increased IL-4 and IL-5 but not IL13 production to SEB superantigen stimulation when compared with non-atopic children. HDM and RYE allergens stimulated significantly increased IFN-gamma, IL-5 and IL-13, while OVA stimulated significantly increased IFN-gamma production in atopic children.

CONCLUSION

We show that a polyclonal stimulus induces a reduced Th1 (IFN-gamma) and increased Th2 (IL-4 and IL-5) cytokine pattern. In contrast, the allergen-induced cytokine responses in atopic children were associated with both increased Th1 (INF-gamma) and Th2 (IL-5 and IL-13) cytokine production. The increased Th1 response to allergen is likely to reflect prior sensitization and indicates that increases in both Th1 and Th2 cytokine production to allergens exists concomitantly with a decreased Th1 response to a polyclonal stimulus in atopic children.

Atopic disorders: a vaccine around the corner?

The incidence and severity of atopic disorders, in particular asthma, is steadily increasing at an alarming rate. Furthermore, no primary prevention measure exists to date. However, recent results obtained from numerous animal studies suggest that primary prevention in humans might be possible in the near future. The most promising approaches include the induction of systemic or local allergen-dependent or -independent T helper 1 (Th1) immune responses, through the use of killed bacteria (or components derived from them), CpG oligodeoxynucleotides or plasmid DNA, and the induction of allergen-specific T-cell tolerance. Here, we review the data showing that animals can be protected from developing allergic Th2 responses by vaccination. Possible future use in humans and potential side-effects of the described vaccination strategies are discussed also.

Mechanism and epidemiology of laboratory animal allergy

Laboratory animal allergy (LAA) is a form of occupational allergic disease. The development of laboratory animal allergy is due to the presence of IgE antibodies directed against animal proteins. The process of sensitization (development of IgE antibodies) is a complex process which involves interaction of antigen presenting cells and lymphocytes of the Th-2 cell type. These cells generate a host of cytokines and other factors which lead to immediate hypersensitivity reactions and other factors which lead to immediate hypersensitivity reactions and the generation of allergic inflammation. Typical symptoms of laboratory animal allergy include nasal symptoms, such as sneezing, watery discharge, and congestion. Skin rashes are also common. Asthma, which produces symptoms of cough, wheezing, and shortness of breath, may affect 20-38% of workers who are sensitized to laboratory animal allergens. Rarely a generalized, life-threatening allergic reaction (anaphylaxis) may occur. The estimated prevalence of laboratory animal allergy is variable depending on the method used for diagnosis, but nonetheless may affect up to 46% of exposed workers. The presence of pre-existing allergies to non-work place allergens (e.g., dust mite, pollens, molds), exposure to laboratory animal allergens, and possibly tobacco smoking are risk factors for the development of laboratory animal allergy. Progress in the understanding of the mechanism and epidemiology of laboratory animal allergy will lead to improved methods for its prevention.