Differential expression of genes involved in skin homing, proliferation, and apoptosis in CD4+ T cells of patients with atopic dermatitis

Bioinformatics analysis of mRNA profiles and identification of microRNA-mRNA network in CD4+ T cells in seasonal allergic rhinitis

Objective

We aimed to discover potential circulating genes and non-coding molecules (micro RNA [miRNA] and circular RNA [circRNA]) in CD4⁺ T cells in relation to seasonal allergic rhinitis (SAR).

Methods

Microarray data of GSE50223 were obtained from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) during and outside the pollen season were analyzed using R software and by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway analyses. The protein–protein interactions, modules, miRNAs targeting DEGs, merged miRNA–DEG networks, and circRNAs targeted with miRNAs were further analyzed.

Results

We identified 211 DEGs during the pollen season and eight DEGs outside the season, of which only MMP12, NR4A2, and CD69 were differentially expressed both during and outside the pollen season. DEGs during the pollen season were enriched in the GO categories ‘neutrophil degranulation’, ‘neutrophil activation involved in immune response’, ‘neutrophil mediated immunity’, and ‘neutrophil activation’. A significant module was identified with key nodes of CDK6 and hsa-miR-29b-3p. Six significant circRNAs were also identified.

Conclusions

Some genes, miRNAs, and circRNAs in CD4⁺ T may play vital roles in SAR and may thus be potential targets for the prevention and treatment of SAR.

Innovative Systems to Deliver Allergen Powder for Epicutaneous Immunotherapy

Allergy is a disorder owing to hyperimmune responses to a particular kind of substance like food and the disease remains a serious healthcare burden worldwide. This unpleasant and sometimes fatal allergic disease has been tackled vigorously by allergen-specific immunotherapy over a century, but the progress made so far is far from satisfactory for some allergies. Herein, we introduce innovative, allergen powder-based epicutaneous immunotherapies (EPIT), which could potentially serve to generate a new stream of technological possibilities that embrace the features of super safety and efficacious immunotherapy by manipulating the plasticity of the skin immune system via sufficient delivery of not only allergens but also tolerogenic adjuvants. We attempt to lay a framework to help understand immune physiology of the skin, epicutaneous delivery of powdered allergy, and potentials for tolerogenic adjuvants. Preclinical and clinical data are reviewed showing that deposition of allergen powder into an array of micropores in the epidermis can confer significant advantages over intradermal or subcutaneous injection of aqueous allergens or other epicutaneous delivery systems to induce immunological responses toward tolerance at little risk of anaphylaxis. Finally, the safety, cost-effectiveness, and acceptability of these novel EPITs are discussed, which offers the perspective of future immunotherapies with all desirable features.

Pre- and postnatal Lactobacillus reuteri treatment alters DNA methylation of infant T helper cells

BACKGROUND

Perinatal childhood exposures, including probiotic supplementation, may affect epigenetic modifications and impact on immune maturation and allergy development. The aim of this study was to assess the effects of pre- and postnatal Lactobacillus reuteri supplementation on DNA methylation in relation to immune maturation and allergy development.

METHODS

DNA methylation patterns were investigated for allergy-related T helper subsets using a locus-specific method and at a genome-wide scale using the Illumina 450K array. From a randomised, double-blind, placebo-controlled allergy prevention trial with pre- and postnatal probiotic supplementation, CD4+ T helper cells were obtained at birth (from cord blood), and 12 and 24 months of age (total (placebo/probiotics); locus-specific method: CB = 32 (17/15), 12 months = 24 (9/15), 24 months = 35 (15/20); Illumina: CB = 19 (10/9), 12 months = 10 (6/4), 24 months = 19(11/8)).

RESULTS

Comparing probiotics to placebo, the greatest genome-wide differential DNA methylation was observed at birth, where the majority of sites were hypomethylated, indicating transcriptional accessibility in the probiotic group. Bioinformatic analyses, including network analyses, revealed a module containing 91 genes, enriched for immune-related pathways such as chemotaxis, PI3K-Akt, MAPK and TGF-β signalling. A majority of the module genes were associated with atopic manifestations (OR = 1.43, P = 2.4 × 10^-6 ), and a classifier built on this model could predict allergy development (AUC = 0.78, P = 3.0 × 10^e-3 ). Pathways such as IFN-γ signalling and T-cell activation were more hypermethylated at birth compared with later in life in both intervention groups over time, in line with DNA methylation patterns in the IFNG locus obtained by the locus-specific methodology.

CONCLUSION

Maternal L. reuteri supplementation during pregnancy alters DNA methylation patterns in CD4+ T cells towards enhanced immune activation at birth, which may affect immune maturation and allergy development.

Review-Current Concepts in Inflammatory Skin Diseases Evolved by Transcriptome Analysis: In-Depth Analysis of Atopic Dermatitis and Psoriasis

During the last decades, high-throughput assessment of gene expression in patient tissues using microarray technology or RNA-Seq took center stage in clinical research. Insights into the diversity and frequency of transcripts in healthy and diseased conditions provide valuable information on the cellular status in the respective tissues. Growing with the technique, the bioinformatic analysis toolkit reveals biologically relevant pathways which assist in understanding basic pathophysiological mechanisms. Conventional classification systems of inflammatory skin diseases rely on descriptive assessments by pathologists. In contrast to this, molecular profiling may uncover previously unknown disease classifying features. Thereby, treatments and prognostics of patients may be improved. Furthermore, disease models in basic research in comparison to the human disease can be directly validated. The aim of this article is not only to provide the reader with information on the opportunities of these techniques, but to outline potential pitfalls and technical limitations as well. Major published findings are briefly discussed to provide a broad overview on the current findings in transcriptomics in inflammatory skin diseases.

JAK/STAT inhibitors and other small molecule cytokine antagonists for the treatment of allergic disease

OBJECTIVE

To provide an overview of janus kinase (JAK), chemoattractant receptor homologous molecule expressed on T_H2 cells (CRTH2), and phosphodiesterase 4 (PDE4) inhibitors in allergic disorders.

DATA SOURCES

PubMed literature review.

STUDY SELECTIONS

Articles included in this review discuss the emerging mechanism of action of small molecule inhibitors and their use in the treatment of atopic dermatitis (AD), asthma, and allergic rhinitis (AR).

RESULTS

Allergic diseases represent a spectrum of diseases, including AD, asthma, and AR. For decades, these diseases have been primarily characterized by increased T_H2 signaling and downstream inflammation. In recent years, additional research has identified disease phenotypes and subsets of patients with non-Th2 mediated inflammation. The increasing heterogeneity of disease has prompted investigators to move away from wide-ranging treatment approaches with immunosuppressive agents, such as corticosteroids, to consider more targeted immunomodulatory approaches focused on specific pathways. In the past decade, inhibitors that target JAK signaling, PDE4, and CRTH2 have been explored for their potential activity in models of allergic disease and therapeutic benefit in clinical trials. Interestingly, although JAK inhibitors provide an opportunity to interfere with cytokine signaling and could be beneficial in a broad range of allergic diseases, current clinical trials are focused on the treatment of AD. Conversely, both PDE4 and CRTH2 inhibitors have been evaluated in a spectrum of allergic diseases. This review summarizes the varying degrees of success that these small molecules have demonstrated across allergic diseases.

CONCLUSION

Emerging therapies currently in development may provide more consistent benefit to patients with allergic diseases by specifically targeting inflammatory pathways important for disease pathogenesis.

The therapeutic potential of CRTH2/DP2 beyond allergy and asthma

Prostaglandin (PG) D₂ has been in the focus of research for quite a long time, but its biological effects and its roles in human disease are still not fully characterized. When in 2001 a second major PGD₂ receptor termed chemoattractant receptor homologue expressed on Th2 cells (CRTH2; alternative name DP2) was discovered, diverse investigations started to shed more light on the complex and often controversial actions of the prostaglandin. With various immunomodulating effects, such as induction of migration, activation, and cytokine release of leukocytes observed both in vivo and in vitro, CRTH2 has emerged as a promising target for the treatment of allergic diseases. However, with more and more research being performed on CRTH2, it has also become clear that its biological actions are far more diverse than expected at the beginning. In this review, we aim to summarize the roles that PGD₂ - and CRTH2 in particular - might play in diseases of the central nervous system, kidney, intestine, lung, hair and skin, bone and cartilage, and in cancer. Based on current data we propose that blocking CRTH2 might be a potential therapeutic approach to numerous conditions beyond classical allergic diseases and asthma.

Targeting the T Helper 2 Inflammatory Axis in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects up to 25% of children and 10% of adults. The skin of patients with moderate to severe AD is characterized by significant barrier disruption and T helper 2 (Th2)-driven inflammation, which are thought to play a significant role in the pathogenesis of AD. Current management of AD is aimed at suppressing the inflammatory response and restoring the barrier function of the skin, reducing exacerbations, and preventing secondary skin infections. Combinations of treatment strategies are used to alleviate the symptoms of the disease; however, resolution is often temporary, and long-term usage of some of the medications for AD can be associated with significant side effects. Antibody therapies previously approved for other inflammatory diseases have been evaluated in patients with AD. Unfortunately, they have often failed to result in significant clinical improvement. Monoclonal antibodies and novel small molecules currently in development may provide more consistent benefit to patients with AD by specifically targeting the immune and molecular pathways important for the pathogenesis of AD. Here we review the state-of-the-art therapeutics targeting the Th2 axis in AD.

Genome-wide gene expression profiling reveals unsuspected molecular alterations in pemphigus foliaceus

Pemphigus foliaceus (PF) is a complex autoimmune disease characterized by bullous skin lesions and the presence of antibodies against desmoglein 1. In this study we sought to contribute to a better understanding of the molecular processes in endemic PF, as the identification of factors that participate in the pathogenesis is a prerequisite for understanding its biological basis and may lead to novel therapeutic interventions. CD4+ T lymphocytes are central to the development of the disease. Therefore, we compared genome-wide gene expression profiles of peripheral CD4+ T cells of various PF patient subgroups with each other and with that of healthy individuals. The patient sample was subdivided into three groups: untreated patients with the generalized form of the disease, patients submitted to immunosuppressive treatment, and patients with the localized form of the disease. Comparisons between different subgroups resulted in 135, 54 and 64 genes differentially expressed. These genes are mainly related to lymphocyte adhesion and migration, apoptosis, cellular proliferation, cytotoxicity and antigen presentation. Several of these genes were differentially expressed when comparing lesional and uninvolved skin from the same patient. The chromosomal regions 19q13 and 12p13 concentrate differentially expressed genes and are candidate regions for PF susceptibility genes and disease markers. Our results reveal genes involved in disease severity, potential therapeutic targets and previously unsuspected processes involved in the pathogenesis. Besides, this study adds original information that will contribute to the understanding of PF's pathogenesis and of the still poorly defined in vivo functions of most of these genes.

Historic overview of allergy research in the Netherlands

Research in allergy has a long history in the Netherlands, although the relation with immunology has not always been appreciated. In many aspects Dutch researchers have made major contribution in allergy research. This ranges from the first characterization of house dust mite as an important allergen, the first characterization of human Th2 and Th1 T cell clones, to the development of diagnostic test systems. In this overview Aalberse and Knol have made an overview of the major contributions of Dutch immunologists in allergy.

A critical role for thymic stromal lymphopoietin in nickel-induced allergy in mice

Ni is the most frequent cause of contact allergy induced by metals. However, the underlying mechanism of this induction is unknown. Our previous research demonstrates that activation of dendritic cells (DCs) through p38MAPK/MKK6 is required for Ni-induced allergy in mice. In the current study, we investigated the cellular and molecular mechanisms underlying Ni-induced allergy using a mouse model that involves injecting Ni into the ear, with or without Freund's incomplete or complete adjuvants. Nickel had greater potential to cause allergic reactions compared with palladium and gold. Among the proteins expressed at higher levels in mice with Ni-induced allergy, we focused on thymic stromal lymphopoietin (TSLP), which is produced in abundance by keratinocytes. We detected increased expression of the TSLP receptor (TSLPR) in DCs from cervical lymph nodes of mice with Ni-induced allergy, suggesting that DCs in ear tissues were activated through TSLPR signaling induced by keratinocyte-derived TSLP. Furthermore, delayed-type hypersensitivity reactions in mice with Ni-induced allergy were decreased significantly by injection of a Tslp-short interfering RNA along with atelocollagen in the ear skin. These results suggest that Ni allergy may be triggered by a TSLP/TSLPR-mediated interaction between epithelial and immune cells.

7,3',4'-Trihydroxyisoflavone Ameliorates the Development of Dermatophagoides farinae-Induced Atopic Dermatitis in NC/Nga Mice

Atopic dermatitis is an inflammatory and chronically relapsing skin disorder that commonly occurs in children; the number of atopic dermatitis patients is increasing. The cause and mechanism of atopic dermatitis have not been defined clearly, although many studies are ongoing. Epidemiological studies suggest that soybean and its isoflavones have immunoregulatory activities. Here, we report that 7,3′,4′-trihydroxyisoflavone (7,3′,4′-THIF), a major metabolite of daidzin, effectively inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 production in RAW 264.7 cells, and also reduced β-hexosaminidase secretion in RBL-2H3 cells. Moreover, 7,3′,4′-THIF significantly reduced scratching time, transepidermal water loss, and mast cell infiltration. It also decreased protease-activated receptor (PAR)-2 and IL-4 expression and increased filaggrin expression in skin lesions of NC/Nga mice. These results suggest that 7,3′,4′-THIF improves Dermatophagoides farina body extract-induced atopic dermatitis in NC/Nga mice.

Pathological mechanisms of skin homing T cells in atopic dermatitis

Skin infiltration of circulating memory T cells with cutaneous tropism is considered one of the pathologic mechanisms in atopic dermatitis (AD). Skin-seeking circulating T lymphocytes can be identified by their expression of the cutaneous lymphocyte-associated antigen on the cell surface. Recent studies have contributed useful new information about the function and recirculation properties of those cells in AD patients. This review integrates the latest findings on peripheral cutaneous lymphocyte-associated antigen memory T cells in AD and highlights the relevance of this cell type and its importance to our understanding of the pathologic mechanisms of AD.

T cell homing to epithelial barriers in allergic disease

Allergic inflammation develops in tissues that have large epithelial surface areas that are exposed to the environment, such as the lung, skin and gut. In the steady state, antigen-experienced memory T cells patrol these peripheral tissues to facilitate swift immune responses against invading pathogens. In at least two allergy-prone organs, the skin and the gut, memory T cells are programmed during the initial antigen priming to express trafficking receptors that enable them to preferentially home to these organs. In this review we propose that tissue-specific memory and inflammation-specific T cell trafficking facilitates the development of allergic disease in these organs. We thus review recent advances in our understanding of tissue-specific T cell trafficking and how regulation of T cell trafficking by the chemokine system contributes to allergic inflammation in mouse models and in human allergic diseases of the skin, lung and gut. Inflammation- and tissue-specific T lymphocyte trafficking pathways are currently being targeted as new treatments for non-allergic inflammatory diseases and may yield effective new therapeutics for allergic diseases.

Th2 Cytokines and Atopic Dermatitis

Atopic dermatitis (AD), a chronic relapsing inflammatory skin disease, is increasing in prevalence around the world. Intensive research is ongoing to understand the mechanisms involved in the development of AD and offer new treatment options for patients suffering from AD. In this review, we highlight the importance of allergic Th2 responses in the development of the disease and summarize relevant literature, including genetic studies, studies of human skin and mechanistic studies on keratinocytes and mouse models of AD. We discuss the importance of the skin barrier and review recent findings on the pro-Th2 cytokines TSLP, IL-25, and IL-33, notably their ability to polarize dendritic cells and promote Th2 responses. After a brief update on the contribution of different T-cell subsets to AD, we focus on Th2 cells and the respective contributions of each of the Th2 cytokines (IL-4, IL-13, IL-5, IL-31, and IL-10) to AD. We conclude with a brief discussion of the current gaps in our knowledge and technical limitations.

The prostaglandin D₂ receptor CRTH2 is important for allergic skin inflammation after epicutaneous antigen challenge

BACKGROUND

Cutaneous prostaglandin (PG) D₂ levels increase after scratching. Chemoattractant receptor-homologous molecule expressed on receptor on T(H)2 cells (CRTH2) mediates chemotaxis to PGD₂ and is expressed on T(H)2 cells and eosinophils, which infiltrate skin lesions in patients with atopic dermatitis.

OBJECTIVE

We sought to examine the role of CRTH2 in a murine model of atopic dermatitis.

METHODS

CRTH2(-/-) mice and wild-type control animals were epicutaneously sensitized by means of repeated application of ovalbumin (OVA) to tape-stripped skin for 7 weeks and then challenged by means of OVA application to tape-stripped previously unsensitized skin for 1 week. Skin histology was assessed by means of hematoxylin and eosin staining and immunohistochemistry. Cytokine mRNA expression was examined by means of quantitative RT-PCR. Levels of PGD₂, antibody, and cytokines were measured by means of ELISA.

RESULTS

PGD₂ levels significantly increased in skin 24 hours after tape stripping, although not in skin subjected to repeated sensitization with OVA. Allergic skin inflammation developed normally at sites of chronic epicutaneous sensitization with OVA in CRTH2(-/-) mice but was severely impaired in previously unsensitized skin challenged with OVA, as evidenced by significantly decreased skin infiltration with eosinophils and CD4(+) cells and impaired T(H)2 cytokine mRNA expression. Impaired skin inflammation at sites of acute OVA challenge in CRTH2(-/-) mice was not due to an impaired systemic response to epicutaneous sensitization because OVA-specific IgG1 and IgE antibody levels and OVA-driven splenocyte secretion of cytokines in these mice were comparable with those seen in wild-type control animals.

CONCLUSIONS

CRTH2 promotes allergic skin inflammation in response to cutaneous exposure to antigen in previously sensitized mice.

Antagonism of CRTH2 ameliorates chronic epicutaneous sensitization-induced inflammation by multiple mechanisms

Prostaglandin D(2) (PGD(2)) and its receptor chemoattractant receptor homologous molecule expressed on T(h)2 cells (CRTH2) have been implicated in the pathogenesis of numerous allergic diseases. We investigated the role of PGD(2) and CRTH2 in allergic cutaneous inflammation by using a highly potent and specific antagonist of CRTH2. Administration of this antagonist ameliorated cutaneous inflammation caused by either repeated epicutaneous ovalbumin or FITC sensitization. Gene expression and ELISA analysis revealed that there was reduced pro-inflammatory cytokine mRNA or protein produced. Importantly, the CRTH2 antagonist reduced total IgE, as well as antigen-specific IgE, IgG1 and IgG2a antibody levels. This reduction in antibody production correlated to reduced cytokines produced by splenocytes following in vitro antigen challenge. An examination of skin CD11c(+) dendritic cells (DC) showed that in mice treated with the CRTH2 antagonist, there was a decrease in the number of these cells that migrated to the draining lymph nodes in response to FITC application to the skin. Additionally, naive CD4(+) T lymphocytes co-cultured with skin-derived DC from CRTH2 antagonist-treated mice showed a reduced ability to produce a number of cytokines compared with DC from vehicle-treated mice. Collectively, these findings suggest that CRTH2 has a pivotal role in mediating the inflammation and the underlying immune response following epicutaneous sensitization.

CRTH2 plays an essential role in the pathophysiology of Cry j 1-induced pollinosis in mice

PGD(2) is the major prostanoid produced during the acute phase of allergic reactions. Two PGD(2) receptors have been isolated, DP and CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells), but whether they participate in the pathophysiology of allergic diseases remains unclear. We investigated the role of CRTH2 in the initiation of allergic rhinitis in mice. First, we developed a novel murine model of pollinosis, a type of seasonal allergic rhinitis. Additionally, pathophysiological differences in the pollinosis were compared between wild-type and CRTH2 gene-deficient mice. An effect of treatment with ramatroban, a CRTH2/T-prostanoid receptor dual antagonist, was also determined. Repeated intranasal sensitization with Cry j 1, the major allergen of Cryptomeria japonica pollen, in the absence of adjuvants significantly exacerbated nasal hyperresponsive symptoms, Cry j 1-specific IgE and IgG1 production, nasal eosinophilia, and Cry j 1-induced in vitro production of IL-4 and IL-5 by submandibular lymph node cells. Additionally, CRTH2 mRNA in nasal mucosa was significantly elevated in Cry j 1-sensitized mice. Following repeated intranasal sensitization with Cry j 1, CRTH2 gene-deficient mice had significantly weaker Cry j 1-specific IgE/IgG1 production, nasal eosinophilia, and IL-4 production by submandibular lymph node cells than did wild-type mice. Similar results were found in mice treated with ramatroban. These results suggest that the PGD(2)-CRTH2 interaction is elevated following sensitization and plays a proinflammatory role in the pathophysiology of allergic rhinitis, especially pollinosis in mice.

Analysis of CD4+ T-cell gene expression in allergic subjects using two different microarray platforms

BACKGROUND

Allergic diseases are thought to involve dysregulated activation of T cells including CD4+ lymphocytes. T-cell activation results in changes in gene expression, but the optimal method to study gene expression profiles in T cells, and how this changes over time, are not known.

METHODS

Circulating CD4+ T cells were obtained from subjects with atopic asthma, nonatopic asthma or nonallergic controls, and total mRNA was rapidly isolated. Atopy was defined as positive skin prick test to one of nine allergens. Gene expression was analyzed using hybridization and Affymetrix oligonucleotide arrays (Hu133A and Hu133B chips, n = 84), or by reverse transcription-polymerase chain reaction (RT-PCR) with a pathway-targeted array (Human Th1-Th2-Th3 RT(2) Profiler PCR Array, Superarray, n = 16).

RESULTS

Using Affymetrix arrays, it was difficult to discern a dominant allergy-associated profile because of heterogeneity in gene expression profiles. In contrast, a Th2-like signature was evident using RT-PCR arrays with increased expression of expected genes (e.g. IL-4, 5, 9, and 13, all P < 0.05) as well as unexpected gene transcripts (e.g. osteopontin). Gene expression profiles were relatively stable over time in circulating CD4+ T cells from two subjects using both platforms.

CONCLUSIONS

Unstimulated CD4+ T cells isolated from allergic subjects express a characteristic profile of genes when analyzed using RT-PCR based microarrays.

Adhesion molecules in cutaneous immunity

Skin serves a vital role, providing protection from the broad array of pathogens present in our environment. In addition to the passive barrier functions of the skin, mammals have evolved a robust and versatile surveillance and rapid response system for recognition and elimination of invading organisms. This immune surveillance network directs the movement of immune cells, regulating homeostatic populations of immune cells in the skin, as well as recruitment to sites of inflammation. In this review, we discuss current understanding of the regulation and function of adhesion molecules in cutaneous immune surveillance and their relevance to the immunopathology of inflammatory skin disease.

The interleukin-10 inducing effect of transforming growth factor-beta on human naive CD4+ T cells from cord blood is restricted to the TH1 subset

Transforming growth factor (TGF-beta) seems to play a role in the regulation of immune responses, mainly by its suppressive function towards cells of the immune system. However, both in mice and human, conflicting data are published on the capacity of TGF-beta to induce interleukin (IL)-10 secretion in both naive and skewed T cell populations. Our aim was to test the IL-10-inducing capacity of TGF-beta in both naive and skewed cord blood mononuclear cells (CBMCs) and elucidate the mechanism by which TGF-beta exerts its effect. Therefore, naive CBMCs and CBMCs during skewing under T helper 1 (Th1) and Th2 polarizing conditions were stimulated with CD3 and/or CD28 in the presence or absence of TGF-beta. Proliferation, cytokine production and mRNA expression of transcription factors was measured. TGF-beta enhanced the IL-10 production in Th1 and naive cells only, and suppressed the T(H)1 phenotype as demonstrated in cytokine levels and T-box expression in T cells (T-bet) expression. Interestingly, forkhead box p3 (Foxp3) expression tended to increase in both Th1 and Th2 cells. These data indicate that TGF-beta can induce a regulatory phenotype in both naive and Th1-polarized cells derived from cord blood. The induction of IL-10 was not observed in Th2-polarized phenotype, indicating that TGF-beta might be especially of interest for immunomodulation in Th1 cells.

Polymorphisms of the Bcl-2 family member bfl-1 in children with atopic dermatitis

T lymphocytes accumulating in the skin of patients with atopic dermatitis (AD) have a prolonged survival and are key mediators of this inflammatory disease. The anti-apoptotic bfl-1 gene is unique in that it is the only member of the Bcl-2 family that is transcriptionally regulated by inflammatory cytokines and might therefore be important in promoting the survival of effector T cells in patients with AD. The aim of this study was to determine whether polymorphisms in the bfl-1 gene are associated with a predisposition to childhood AD. Four bfl-1 gene, single nucleotide polymorphisms (SNPs) were studied by ARMS-PCR in 105 Caucasian children with moderately severe AD and 110 non-atopic adult controls. In addition to the known polymorphisms of exon 1 (+141*A/G, +202*G/T, +303*A/G), we described a novel polymorphism in the promoter region of the gene (-1182*G/C). We found a significant difference in bfl-1 +141 genotype [OR (95% CI) 5.1 (1.0-25.2)], as well as bfl-1-1182:+141:+202:+303 G:A:G:A/G:A:G:A diplotype frequencies [3.5 (1.0-12.2)] in AD (p < 0.05). The study thus provides evidence for an association between bfl-1 polymorphisms and the genetic predisposition to AD.

A network-based analysis of allergen-challenged CD4+ T cells from patients with allergic rhinitis

We performed a network-based analysis of DNA microarray data from allergen-challenged CD4(+) T cells from patients with seasonal allergic rhinitis. Differentially expressed genes were organized into a functionally annotated network using the Ingenuity Knowledge Database, which is based on manual review of more than 200,000 publications. The main function of this network is the regulation of lymphocyte apoptosis, a role associated with several genes of the tuber necrosis factor superfamily. The expression of TNFRSF4, one of the genes in this family, was found to be 48 times higher in allergen-challenged cells than in diluent-challenged cells. TNFRSF4 is known to inhibit apoptosis and to enhance Th2 proliferation. Examination of a different material of allergen-stimulated peripheral blood mononuclear cells showed a higher number of interleukin-4(+) type 2 CD4(+) T (Th2) cells in patients than in controls (P<0.01), as well as a higher number of non-apoptotic Th2 cells in patients (P<0.01). The number of Th2 cells expressing TNFRSF4, TNFSF7 and TNFRSF1B was also significantly higher in patients. Treatment with anti-TNFSF4 resulted in a significantly decreased number of Th2 cells (P<0.05). A logical inference from all this is that the proliferation of allergen-challenged Th2 cells is associated with a decreased apoptosis of Th2 cells and an increase in TNFRSF4 signalling.

Emerging roles of DP and CRTH2 in allergic inflammation

The lipid mediator prostaglandin D(2) (PGD(2)) has long been implicated in various inflammatory diseases including asthma. PGD(2) elicits biological responses by activating two seven-transmembrane (7TM) G-protein-coupled receptors, the D-prostanoid receptor DP and the chemoattractant receptor homologous-molecule expressed on T-helper-type-2 cells (CRTH2), which are linked to different signaling pathways. Understanding how immune cells integrate and coordinate signals that are triggered by the same ligand is crucial for the development of novel anti-inflammatory therapies. Here, we examine the roles of DP and CRTH2 in the orchestration of complex inflammatory processes, and discuss their importance as emerging targets for the treatment of asthma and inflammatory diseases.