Exposure and allergic sensitization to cockroach was associated with a significantly greater risk of asthma hospitalization and greater healthcare utilization among 476 children aged 4 to 9 years who participated in the National Cooperative Inner-City Asthma Study. Allergic sensitization to the mold Alternaria has been identified as a significant allergen in terms of increasing airway hyperresponsiveness and was associated with a nearly 200-fold increased risk of respiratory arrest due to asthma, emphasizing the importance of determining underlying allergic sensitivities in patients with asthma and providing patients with accurate and practical advice on allergen avoidance techniques. (more…)

Leukotrienes can be found in the airway and urine following both spontaneous exacerbations of asthma and acute exposure to bronchoconstrictor stimuli in the laboratory. This in turn indicates that they may have a role in the pathogenesis of acute episodes of bronchoconstriction. Although antileukotrienes are not currently advocated in the management of acute asthma, there are data to suggest that they might be of some potential benefit. Prior treatment with montelukast asthma has been shown in several studies to significantly shorten the time taken to recover (in terms of FEV 1 ) following exposure to a bronchoconstrictor stimulus. (more…)

Treg cells or regulatory T cells constitute a large population of cellular infiltrate in atopic/allergic inflammation and a dysregulated immune response appears to be an important pathogenetic factor. Cardinal events during allergic inflammation can be classified as activation, organ-selective homing, survival and reactivation, and effector functions of immune system cells. T cells are activated by aeroallergens, food antigens, autoantigens, and bacterial exotoxins superantigens in allergic inflammation. They are under the influence of the skin, lung, or nose-related chemokine network and show organ-selective homing. (more…)

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A general pattern of factors influencing development of asthma seems to be emerging, including family allergy history/ asthma genetics, smoking, diet, obesity, and inactivity, all of which seem to influence the development of asthma and disease outcomes (Table bellow).

Many clinical or area studies have reported substantially higher rates of asthma prevalence, hospitalization, and mortality among racial and ethnic minorities. However, asthma is also most common among low socioeconomic groups, regardless of race. While black children have higher rates of asthma than white children, most studies have found that black race is not a significant correlate of asthma after controlling for location of residence and socioeconomic status (SES). The basis for the effects of poverty and urban residence on asthma prevalence is not known. One potential asthma factor is allergen exposure and allergen sensitization are common in urban environments. Black children in inner city Atlanta are exposed to high levels of dust mites and cockroach allergen, and a high proportion of the children with asthma were sensitized to these allergens. Litonjua and colleagues also concluded that a large proportion of racial/ethnic differences in asthma prevalence can be explained by factors related to income, area of residence, and level of education.

Asthma Factors that Influence Disease Development and Severity

Income is a determinant of access to health care, and frequently, the quantity and quality of health care available. Persons who have low income, regardless of race or ethnicity, are more likely to be uninsured, to encounter delays or be denied care, to rely on hospital clinics in emergency departments for health services, and to receive substandard care. The usual socioeconomic indicators, education and personal or household income, serve only as surrogates for more complicated correlates of individuals within populations and multiple asthma factors that can impact both on prevalence of asthma and adverse outcomes from the disease.

Studies from Germany comparing the populations of East and West Germany have shown the prevalence of hay fever and asthma as significantly higher in West German children, suggesting that asthma environmental factors explain the difference in prevalence in these ethnically similar populations. Early exposure to infections (as with being in a day-care environment early in life) or exposure to endotoxin (as with growing up on a farm with close exposure to the farm animals) are associated with a decreased prevalence of asthma. In contrast, growing up in an urban environment or generally with an increased standard of living are associated with an increased prevalence of asthma. Such correlates are also present for atopic disorders other than asthma. In fact, Strachan, who noted that prevalence of hay fever was inversely related to family size, was the first to recognize the importance of early exposures on atopic disease. In the USA, asthma is more prevalent in African-Americans and Puerto Ricans. These findings are not explained by the observations on the role of social class in European studies. Given the ethnic differences between African-Americans and whites, these studies may represent gene-by-environment interaction producing varied phenotypic outcomes.

The intracellular forkhead winged transcription factor Foxp3 (forkhead box P3) appears to be specifically expressed by naturally occurring Treg cells, particularly in mice, although in humans there is evidence of upregulation of Foxp3 in all T cells on activation. Foxp3 is required for the development and function of naturally occurring regulatory t cells (treg) and expression is sufficient to convert non-regulatory CD4+CD25T cells into cells with regulatory activity. Conversion of peripheral CD4+CD25 naive T cells to Foxp3+CD4+CD25 foxp3+ Treg cells can be induced by TGF-ß. In a murine asthma model, these TGF-ß-induced Treg prevented house-dust mite-induced allergic pathogenesis or infection pathogenesis in lungs. A single independent report has suggested that IL-4 and IL-13 also induce Foxp3+CD25+ Treg from CD4+CD25precursors. (more…)

One especially favored target for immune recognition is bacterial lipopolysaccharide (LPS). This macromolecule is found only in the outer lipid bilayer that surrounds the cell walls of gram-negative bacteria, such as Neisseria, Salmonella, and Escherichia coli. Each molecule of bacterial lipopolysaccharide consists of a core carbohydrate linked on one side to a phospholipid (called lipid A) that is anchored in the bilayer and on the other side to a long polysaccharide chain (called the O sidechain) that extends outward from the bacterial surface (Figure 1 bellow). The sequence of sugars making up the O sidechain is species-specific and highly variable, even within a single bacterial genus: For example, more than 1000 variants in Salmonella are known. (more…)

Normally present at very low levels in plasma, antibodies of the immunoglobulin E (IgE) isotype were first discovered in 1967, decades after the description of IgA, IgG, and IM. IgE antibodies are produced primarily by plasma cells in mucosal-associated lymphoid tissue and their levels are uniformly elevated in patients suffering from atopic conditions like allergic rhinitis, asthma and atopic dermatitis. Production of allergen-specific IgE in atopic individuals is driven both by a genetic predisposition to the synthesis of this isotype as well as by environmental factors, including chronic allergen exposure. (more…)

CD14 is part of the receptor complex for endotoxin, which is a component of tobacco smoke. The CD14 gene is located on chromosome 5q, a region previously demonstrated to be linked to asthma when stratified for smoke exposure. This study was designed to extend these findings by determining whether polymorphisms in the CD14 gene are related to this gene–environment interaction on asthma. Puerto Rican (n = 362 trios) and Mexican (n = 259 trios) families ascertained through a child with asthma were studied. (more…)

Topical corticosteroids are the usual therapy for patients with atopic dermatitis, but prolonged use can result in skin atrophy and other side effects. The long-term safety and efficacy of tacrolimus would prove an attractive alternative. Long-term treatment with 0.1% tacrolimus ointment is significantly more efficacious than a corticosteroid ointment regimen in adults with moderate to severe atopic dermatitis. (more…)

Asthma is characterized by Th2-dominant cytokine profiles. The risk of developing asthma is lower in children attending day care in the first year of life. Therefore, this study was conducted to assess the interaction between day-care attendance, T-cell cytokine profiles and atopic phenotypes in early childhood. Children (n = 208) in the Childhood Onset of Asthma (COAST) study were genotyped for 72 polymorphisms in 45 immune response genes. The COAST cohort was selected on the basis of a high risk of asthma. Measurements of IFN-y (Th1), IL-5 and IL-13 (Th2), and IL-10 (Treg) were made at birth and at age 1 year and the children were stratified by day-care attendance. Wheeze and atopic dermatitis phenotypes were documented in the first year. (more…)