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…)

This study examined the genetic basis of sensitization to house dust mite allergy allergens. A genome scan was conducted using 603 microsatellite markers in 82 nuclear families (366 individuals) of German, British and Portuguese origin with at least two affected siblings. Sensitization to Dermatophagoides pteronyssinus was assessed by determining specific IgE antibody levels detected by immunochemiluminometric assay and immunosorbent assay and categorized as positive or negative relative to a predetermined cut-off point. (more…)

Allergen exposure plays a role in the development of asthma bronchial hyper-responsiveness and in the acute inflammatory response seen in asthmatic patients. Reduction of house dust mite allergens might lead to better lung function and reduction of asthma symptoms. (more…)

Exposure to allergens plays a role in the development of BHR and in the chronic inflammatory response seen in asthmatic patients. Reduction of HDM allergens might lead to better lung function and reduction of asthma symptoms. In this RCT, the effect of HDM-impermeable covers on HDM allergen levels, peak flow values and asthma symptoms were measured. Fifty-two allergic asthmatic patients were randomly allocated to use the HDM-impermeable or placebo covers. During the study period, daily peak flow and asthma symptom scores were recorded. Dust samples were taken from the mattresses.

There was a significant reduction in HDM allergen levels on the mattresses after encasing them with HDM-impermeable covers (reduction of 87% in Der p1 in µg/g of dust; P <0.001). Baseline symptoms were so low that no improvement could be established. However, morning peak expiratory flow was significantly higher in the intervention group compared with that seen in the placebo group during the study period (ß = 20.2; P <0.01). The authors concluded that HDM-impermeable covers significantly decreased the level of HDM allergens with a consequent increase in morning peak flow. This study indicates that HDM allergen avoidance measures might have beneficial effects on allergen reduction and asthma outcome.

Inhalation of HDM allergen causes airway inflammation and BHR. Presuming that most exposure to HDM allergen occurs in bed during sleep, mite-impermeable covers are widely recommended for HDM-allergic asthmatic patients as an established environment control measure. However, RCTs have produced conflicting results. The studies have consistently shown that exposure to HDM allergen is reduced with the application of mite-impermeable mattress, bedding and pillow covers. However, this reduction does not seem to translate easily into clinically meaningful improvements in the symptoms of asthmatic patients, lung function or BHR. This study showed no improvement in the patients’ symptoms, which the authors regarded as due to low levels of baseline symptoms, and thus further reduction was not easily achievable. However, other reasons might be the low level of sensitization to HDM of the study subjects and the small sample size, which may have produced false-negative results. The average morning peak flow was improved in the intervention group over the 9 weeks but repeated measures analysis failed to show an overall effect. This study was reported as showing a protective effect. However, as there was no effect on symptoms, evening peak flow or overall peak flow variability, lung function or medication use, it is difficult to accept that HDM avoidance measures led to a clinically meaningful improvement.

Two factors thought to influence the risk factor asthma are the promoting effect of sensitization to house dust mites and the preventive effect of increased omega-3 fatty acids. Although the avoidance of house dust mites allergen has been used as a preventive strategy in several trials, the effect of omega-3 fatty acid supplementation in the primary prevention of asthma and allergic disease is not known. (more…)

Asthma and allergic diseases are common in both children and adults. Their development depends on an interaction between asthma genetic and asthma environmental risk factors. Genetic manipulation in multi factorial diseases such as asthma is not feasible in the foreseeable future. However, theoretically, environmental exposures can be controlled in an attempt to stem the rising prevalence of these diseases (primary prevention). Environmental exposures may also influence the frequency of symptoms and the requirement for medication in those with established disease. (more…)

To prevent the development of allergy, allergen avoidance has to be instituted before sensitization has occurred. The specific type of aero allergens may vary depending on the climatic and economic situation. For example, House Dust Mite is the most important allergen in humid climates and pet allergens assume importance in cold countries, while cockroach allergen is the major sensitizing agent in crowded, inner city areas. Several large prospective studies have instituted House Dust Mites avoidance measures during pregnancy, at birth and later in childhood, and assessed children for asthma and allergic manifestations. (more…)

There is much controversy as to the role of allergen exposure for the development of atopic sensitization towards this allergen. While in some studies, a clear, almost linear dose-response relation between allergen exposure and sensitization has been found, others described a bell-shaped association with higher levels of exposures relating to lower rates of atopic sensitization. Part of the discrepancy may relate to the type of allergen, since mostly cat but not house dust mite allergy allergen exposure has been shown, in some studies, to exert protective effects at higher levels of exposure. (more…)

There is nothing more scary for a new parent than the thought that their child might get sick. But while most parents manage to keep their children away from cold and flu germs, most don’t realise the effect that household allergens can have on their newborn baby. Baby allergies can be caused by a simple factor in your house; from dust mites to pollen, pet fur to mold, any of these common allergens can cause your child to develop an allergy. (more…)