IL-5 T-cell responses to house dust mite are associated with the development of allergen-specific IgE responses and asthma in the first 5 years of life

Single-cell RNA transcriptomic analysis identifies Creb5 and CD11b-DCs as regulator of asthma exacerbations

Immune responses that result in asthma exacerbation are associated with allergen or viral exposure. Identification of common immune factors will be beneficial for the development of uniformed targeted therapy. We employed a House Dust Mite (HDM) mouse model of asthma and challenged allergic HDM mice with allergens (HDM, cockroach extract (CRE)) or respiratory syncytial virus (RSV). Purified lung immune cells underwent high-dimensional single-cell RNA deep sequencing (scRNA-seq) to generate an RNA transcriptome. Gene silencing with siRNA was employed to confirm the efficacy of scRNA-seq analysis. scRNA-seq UMAP analysis portrayed an array of cell markers within individual immune clusters. SCENIC R analysis showed an increase in regulon number and activity in CD11b^- DC cells. Analysis of conserved regulon factors further identified Creb5 as a shared regulon between the exacerbation groups. Creb5 siRNAs attenuated HDM, CRE or RSV-induced asthma exacerbation. scRNA-seq multidimensional analysis of immune clusters identified gene pathways that were conserved between the exacerbation groups. We propose that these analyses provide a strong framework that could be used to identify specific therapeutic targets in multifaceted pathologies.

House dust mite reduction and avoidance measures for treating eczema

BACKGROUND

Eczema is an inflammatory skin disease that tends to involve skin creases, such as the folds of the elbows or knees; it is an intensely itchy skin condition, which can relapse and remit over time. As many as a third of people with eczema who have a positive test for allergy to house dust mite have reported worsening of eczema or respiratory symptoms when exposed to dust.

OBJECTIVES

To assess the effects of all house dust mite reduction and avoidance measures for the treatment of eczema.

SEARCH METHODS

We searched the following databases up to 14 August 2014: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2014, Issue 8), MEDLINE (from 1946), Embase (from 1974), LILACS (from 1982), and the GREAT database. We also searched five trials registers and checked the reference lists of included and excluded studies for further references to relevant studies. We handsearched abstracts from international eczema and allergy meetings.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of any of the house dust mite reduction and avoidance measures for the treatment of eczema, which included participants of any age diagnosed by a clinician with eczema as defined by the World Allergy Organization. We included all non-pharmacological and pharmacological interventions that sought to reduce or avoid exposure to house dust mite and their allergenic faeces. The comparators were any active treatment, no treatment, placebo, or standard care only.

DATA COLLECTION AND ANALYSIS

Two authors independently checked the titles and abstracts identified, and there were no disagreements. We contacted authors of included studies for additional information. We assessed the risk of bias using Cochrane methodology.

MAIN RESULTS

We included seven studies of 324 adults and children with eczema. Overall, the included studies had a high risk of bias. Four of the seven trials tested interventions with multiple components, and three tested a single intervention. Two of the seven trials included only children, four included children and adults, and one included only adults. Interventions to reduce or avoid exposure to house dust mite included covers for mattresses and bedding, increased or high-quality vacuuming of carpets and mattresses, and sprays that kill house dust mites.Four studies assessed our first primary outcome of 'Clinician-assessed eczema severity using a named scale'. Of these, one study (n = 20) did not show any significant short-term benefit from allergen impermeable polyurethane mattress encasings and acaricide spray versus allergen permeable cotton mattress encasings and placebo acaricide spray. One study (n = 60) found a modest statistically significant benefit in the Six Area, Six Sign Atopic Dermatitis (SASSAD) scale over six months (mean difference of 4.2 (95% confidence interval 1.7 to 6.7), P = 0.008) in favour of a mite impermeable bedding system combined with benzyltannate spray and high-filtration vacuuming versus mite permeable cotton encasings, water with a trace of alcohol spray, and a low-filtration vacuum cleaner. The third study (n = 41) did not compare the change in severity of eczema between the two treatment groups. The fourth study (n = 86) reported no evidence of a difference between the treatment groups.With regard to the secondary outcomes 'Participant- or caregiver-assessed global eczema severity score' and the 'Amount and frequency of topical treatment required', one study (n = 20) assessed these outcomes with similar results being reported for these outcomes in both groups. Four studies (n = 159) assessed 'Sensitivity to house dust mite allergen using a marker'; there was no clear evidence of a difference in sensitivity levels reported between treatments in any of the four trials.None of the seven included studies assessed our second primary outcome 'Participant- or caregiver-assessed eczema-related quality of life using a named instrument' or the secondary outcome of 'Adverse effects'.We were unable to combine any of our results because of variability in the interventions and paucity of data.

AUTHORS' CONCLUSIONS

We were unable to determine clear implications to inform clinical practice from the very low-quality evidence currently available. The modest treatment responses reported were in people with atopic eczema, specifically with sensitivity to one or more aeroallergens. Thus, their use in the eczema population as a whole is unknown. High-quality long-term trials of single, easy-to-administer house dust mite reduction or avoidance measures are worth pursuing.

Reprint of: Perinatal and early childhood environmental factors influencing allergic asthma immunopathogenesis

BACKGROUND

The prevalence of asthma has increased dramatically over the past several decades. While hereditary factors are highly important, the rapid rise outstrips the pace of genomic variation. Great emphasis has been placed on potential modifiable early life exposures leading to childhood asthma.

METHODS

We reviewed the recent medical literature for important studies discussing the role of the perinatal and early childhood exposures and the inception of childhood asthma.

RESULTS AND DISCUSSION

Early life exposure to allergens (house dust mite (HDM), furred pets, cockroach, rodent and mold), air pollution (nitrogen dioxide (NO2), ozone (O3), volatile organic compounds (VOCs), and particulate matter (PM)) and viral respiratory tract infections (Respiratory syncytial virus (RSV) and human rhinovirus (hRV)) has been implicated in the development of asthma in high risk children. Conversely, exposure to microbial diversity in the perinatal period may diminish the development of atopy and asthma symptoms.

Quantification of circulating house dust mite-specific IL-4- and IL-13-secreting T cells correlates with rhinitis severity in asthmatic children and varies with the seasons

BACKGROUND

Defining suitable markers to diagnose and monitor allergy and its severity is essential to correctly assign patients for specific immunotherapy. Circulating levels of specific IgE are good markers of sensitization, but not of clinically symptomatic allergy.

OBJECTIVE

To quantify circulating interleukin (IL)-4- and IL-13-secreting T cells specific for house dust mite (HDM) in children presenting HDM-allergic asthma associated or not with rhinitis and correlate results with clinical symptoms.

METHODS

We analysed 26 children with HDM respiratory disease (allergic rhinitis and asthma) together with six children with non-allergic asthma. Peripheral blood mononuclear cells were stimulated with HDM extract in a 24-h ELISpot assay to quantify the number of HDM-specific IL-4- and IL-13-secreting T cells. Asthma severity and control, and rhinitis severity were scored according to the Global Initiative for Asthma (GINA) and the Allergic Rhinitis and its Impact on Asthma (ARIA) Guidelines.

RESULTS

The number of HDM-specific IL-4- and IL-13-secreting T cells was higher in patients with allergic asthma as compared to patients with non-allergic asthma. It varied with the season of blood sampling with two peaks in the fall and early spring. Independently of the season, the number of HDM-specific IL-4-secreting T cells correlated with rhinitis severity (OR = 2; 95% IC:1.1-3.8; P = 0.04).

CONCLUSIONS AND CLINICAL RELEVANCE

Allergen-specific IL-4- and IL-13-producing T cells were only detected in HDM-allergic asthmatic children (not in patients with non-allergic asthma). Their numbers correlated with clinical severity of allergic rhinitis.

Perinatal and early childhood environmental factors influencing allergic asthma immunopathogenesis

BACKGROUND

The prevalence of asthma has increased dramatically over the past several decades. While hereditary factors are highly important, the rapid rise outstrips the pace of genomic variation. Great emphasis has been placed on potential modifiable early life exposures leading to childhood asthma.

METHODS

We reviewed the recent medical literature for important studies discussing the role of the perinatal and early childhood exposures and the inception of childhood asthma.

RESULTS AND DISCUSSION

Early life exposure to allergens (house dust mite (HDM), furred pets, cockroach, rodent and mold), air pollution (nitrogen dioxide (NO(2)), ozone (O(3)), volatile organic compounds (VOCs), and particulate matter (PM)) and viral respiratory tract infections (Respiratory syncytial virus (RSV) and human rhinovirus (hRV)) has been implicated in the development of asthma in high risk children. Conversely, exposure to microbial diversity in the perinatal period may diminish the development of atopy and asthma symptoms.

Allergen-specific IL-5 responses in early childhood predict asthma at age eight

Background

The pattern of development of allergen-specific T cell cytokine responses in early childhood and their relation to later disease is poorly understood. Here we describe longitudinal changes in allergen-stimulated T cell cytokine responses and their relation to asthma and allergic disease during the first 8 years of life.

Methods

Subjects with a family history of asthma, who were enrolled antenatally in the Childhood Asthma Prevention Study (public trials registration number ACTRN12605000042640), had skin prick tests, clinical evaluation for asthma and eczema, and in vitro assessment of T cell cytokine responses to HDM extract performed at ages 18 months (n = 281), 3 years (n = 349), 5 years (n = 370) and 8 years (n = 275). We measured interleukin (IL-) 13 at 3, 5 and 8 years, and IL-5, IL-10, and interferon-γ (IFN-γ), at 18 months, 3, 5 and 8 years by ELISA. A cohort analysis was undertaken. Independent effects of cytokine responses at each age on the risk of asthma and allergic outcomes at age 8 years were estimated by multivariable logistic regression.

Results

HDM-specific IL-5 responses increased with age. HDM-specific IL-13 and IL-10 responses peaked at age 5 years. HDM-specific IL-5 responses at 3 years, 5 years and 8 years were significantly associated with the presence of asthma and atopy at 8 years. IL-13 responses at 3 years, 5 years and 8 years were significantly associated with atopy at 8 years, but this association was not independent of the effect of IL-5. Other HDM-specific cytokine responses were not independently related to asthma or eczema at 8 years.

Conclusion

HDM-specific IL-5 responses at age 3 years or later are the best measure of T cell function for predicting asthma at age 8 years.

Allergen-specific Th2 responses in young children precede sensitization later in life

Allergic sensitization is initiated by allergen-specific Th2-cell responses. Data on early allergen-specific T-cell responses in allergic children are scarce. We hypothesized that allergen-specific Th2-cell responses can be detected preceding sensitization. Therefore, peripheral blood mononuclear cells (PBMC) of nonsensitized, 'not-yet' sensitized or sensitized children were cultured with highly purified allergens. Cytokine levels in supernatant were determined using multiplex assay and GATA3 expression by flow cytometry. PBMC of sensitized children aged 3 and 5 years showed higher production of IL4, IL5 and IL13 and higher expression of GATA3 in response to purified allergens compared to nonsensitized children. PBMC of children that were 'not-yet' sensitized already showed higher levels of IL5 and IL13 and higher GATA3 expression at age 3 years. This shows that allergen-specific in vitro Th2 responses precede the detection of allergen-specific IgE, which can provide a window of opportunity for novel therapeutic interventions.

Correlation of Der p 2 T-cell responses with clinical characteristics of children allergic to house dust mite

BACKGROUND

An understanding of the mechanisms responsible for the development and maintenance of allergic inflammation and their clinical implications is needed to develop specific and successful treatment for allergy.

OBJECTIVES

To characterize in vitro T-cell responses to Der p 2, one of the major allergens of house dust mite (HDM), and investigate potential correlations between clinical and laboratory parameters.

METHODS

Forty-two patients monosensitized to HDM and 10 age-matched, healthy children were studied. Dendritic cells pulsed with Der p 2 were used to stimulate autologous CD14(-) cells. Der p 2-specific T-cell activation markers, proliferation, and cytokine production profiles were examined.

RESULTS

Der p 2-specific T-cell activation markers, proliferation, and T(H)2 cytokine production were significantly higher in HDM patients compared with healthy controls. Moreover, a significant correlation between proliferation and T(H)2 cytokine production was observed. Within the allergic group, skin reaction to HDM was significantly stronger in patients with a Der p 2-specific T-cell response. Levels of HDM-specific IgE directly correlated with interleukin 5 and interleukin 13 levels and with skin prick test results and, ultimately, with the patient's family history of allergy. Furthermore, the presence of atopic march correlated with T-cell proliferation.

CONCLUSION

We found that, in HDM patients, Der p 2-specific T(H)2 responses, promoted by autologous dendritic cells in vitro, correlate with clinical parameters.

The role of indoor allergens in the development of asthma

PURPOSE OF REVIEW

Asthma prevalence has markedly increased over the past 30 years. Although atopy and exposure to environmental allergens are known to exacerbate asthma, recent literature supports a causal role of indoor allergens in disease development.

RECENT FINDINGS

High-risk birth cohorts continue to point to atopy as the main risk factor for developing asthma. Exposure to perennial allergens has also been linked to the development of asthma, though with less consistency. Intervention at the level of allergen exposure and allergic immune response is promising.

SUMMARY

The current model of atopic asthma, the predominant phenotype, incorporates genetic and environmental factors in the development of disease. Although genetic factors are less malleable, the environmental component lends itself to analysis and modification.For many, the development of asthma starts with allergen exposure leading to atopic sensitization and subsequent disease. Several studies support the progression from exposure to sensitization with the potential of extremely high levels of exposure leading to tolerance. Likewise, the progression from atopy to asthma is well documented,especially in genetically predisposed children. Recent intervention trials confirm these findings and begin to show promise for the prevention of asthma by interrupting the allergen exposure==>allergen sensitization==>atopic asthma pathway.

New insights into mechanisms of immunoregulation in 2007

Substantial progress in understanding the mechanisms of immune regulation in allergic diseases and asthma has been made during the last year. In asthma, rhinitis, and atopic dermatitis the immune system is activated by allergens, autoantigens, and components of superimposed infectious agents. Immune regulation in the lymphatic organs and in the tissue has an important role in the control and suppression of allergic disease in all stages of the inflammatory process, such as cell migration to tissues, cells gaining an inflammatory and tissue-destructive phenotype in the tissues, and their interaction with resident tissue cells to augment the inflammation. After the discovery of regulatory T cells, the importance of their unique suppressive capacity was strongly emphasized for the suppression of effector T-cell responses. However, it seems that all 3 subsets of effector T(H)1, T(H)2, and T(H)17 cells, as well as regulatory T cells, regulate each other at the level of transcription, major cytokines, and surface molecules. This review highlights key advances in immune regulation that were published in the Journal of Allergy and Clinical Immunology.

Skin tests, T cell responses and self-reported symptoms in children with allergic rhinitis and asthma due to house dust mite allergy

BACKGROUND

In allergic responses, a distinction is made between an early-phase response, several minutes after allergen exposure, and a late-phase response after several hours. During the late phase, eosinophils and T cells infiltrate the mucosa and play an important role in inflammation.

OBJECTIVE

The aim of this study was to examine the relationship between allergen-induced late-phase skin responses and in vitro T cell reactivity. In addition, the relationship between allergen-induced skin or T cell responses and the severity of self-reported symptoms was studied in children with house dust mite allergy.

METHODS

A total of 59 house dust mite-allergic children (6-18 years) were recruited in general practice. These children or their parents rated their nasal and asthma symptoms on diary cards during 1 month. Allergen skin tests were performed and read after 15 min (early phase) and 6 h (late phase). Allergen-specific T cell proliferation was determined, and Th2 cytokine (IL-5 and IL-13) secretion was analysed.

RESULTS

The size of the late-phase skin response correlated with in vitro T cell proliferation (r(s)=0.38, P=0.003) but not with Th2 cytokine secretion (r(s)=0.16, P=0.2 for both IL-5 and IL-13). Moreover, the late-phase skin response and T cell proliferation correlated with asthma symptoms (r(s)=0.30, P=0.02 for skin response and r(s)=0.28, P=0.03 for T cell proliferation) but not with nasal symptoms (r(s)=0.19, P=0.15 for skin response and r(s)=0.09, P=0.52 for T cell proliferation). The early-phase skin response correlated with the nasal symptom score (r(s)=0.34, P=0.01) but not with asthma symptom scores (r(s)<0.005, P=0.97).

CONCLUSION

In this study, the late-phase skin test response correlated with in vitro T cell proliferation but not with Th2 cytokine secretion. We found weak or no correlations between late-phase skin responses and symptoms of asthma or rhinitis in children with house dust mite allergy. This suggests that late-phase skin responses reflect certain T cell properties but are of limited value for the evaluation of airway symptoms in atopic children.

New perspectives on mechanisms underlying chronic allergic inflammation and asthma in 2007

This review summarizes selected articles appearing from January to December 2007 in the Journal of Allergy and Clinical Immunology. Articles were chosen that related to advances in mechanisms of chronic allergic inflammation and asthma, including those describing gene association studies, mast cells, IgE, eosinophils, cytokines, the inception of allergy, airway remodeling, preclinical therapeutic targets, and virally induced asthma.