Increased expression of IRF4 and ETS1 in CD4+ cells from patients with intermittent allergic rhinitis

BACKGROUND

  The transcription factor (TF) IRF4 is involved in the regulation of Th1, Th2, Th9, and Th17 cells, and animal studies have indicated an important role in allergy. However, IRF4 and its target genes have not been examined in human allergy.

METHODS

  IRF4 and its target genes were examined in allergen-challenged CD4(+) cells from patients with IAR, using combined gene expression microarrays and chromatin immunoprecipitation chips (ChIP-chips), computational target prediction, and RNAi knockdowns.

RESULTS

  IRF4 increased in allergen-challenged CD4(+) cells from patients with IAR, and functional studies supported its role in Th2 cell activation. IRF4 ChIP-chip showed that IRF4 regulated a large number of genes relevant to Th cell differentiation. However, neither Th1 nor Th2 cytokines were the direct targets of IRF4. To examine whether IRF4 induced Th2 cytokines via one or more downstream TFs, we combined gene expression microarrays, ChIP-chips, and computational target prediction and found a putative intermediary TF, namely ETS1 in allergen-challenged CD4(+) cells from allergic patients. ETS1 increased significantly in allergen-challenged CD4(+) cells from patients compared to controls. Gene expression microarrays before and after ETS1 RNAi knockdown showed that ETS1 induced Th2 cytokines as well as disease-related pathways.

CONCLUSIONS

  Increased expression of IRF4 in allergen-challenged CD4(+) cells from patients with intermittent allergic rhinitis leads to activation of a complex transcriptional program, including Th2 cytokines.

Allergen challenge of peripheral blood mononuclear cells from patients with seasonal allergic rhinitis increases IL-17RB, which regulates basophil apoptosis and degranulation

BACKGROUND

Previously, expression profiling has been used to analyse allergen-challenged T-helper type 2 cells, nasal biopsies and nasal fluid cells from patients with seasonal allergic rhinitis (SAR). Allergen-challenged peripheral blood mononuclear cells (PBMCs) provide a human in vitro model of how antigen-presenting cells, CD4+ T cells and effector cells such as basophils interact in allergic inflammation.

OBJECTIVE

To identify novel genes and pathways in allergen-challenged PBMCs from patients with SAR using gene expression profiling and functional studies.

METHODS

PBMCs from 11 patients with SAR and 23 healthy controls were analysed with gene expression profiling. mRNA expression of IL17RB in basophils was evaluated using quantitative real-time PCR. Membrane protein expression and apoptosis of basophils were examined by flow cytometry. Degranulation of basophils was assessed by measuring beta-hexosaminidase release. Cytokine release was measured using ELISA.

RESULTS

Gene expression microarray analysis of allergen-challenged PBMCs showed that 209 out of 44000 genes were differentially expressed in patients compared with controls. IL17RB was the gene whose expression increased most in patients (P<0.0001). FACS analysis of PBMCs showed, for the first time, that basophils express IL-17RB. Following allergen challenge, IL-17RB protein increased significantly on basophils from patients compared with controls (P<0.05). IL-3 significantly increased both mRNA and protein expressions of IL17RB. Activation of IL-17RB by its ligand, IL-25, inhibited apoptosis of basophils. Moreover, IgE-mediated degranulation was enhanced by IL-25.

CONCLUSION

Increased expression of IL-17RB on allergen-challenged basophil is regulated by IL-3, inhibits apoptosis and promotes IgE-mediated degranulation of basophils.

A haplotype in the inducible T-cell tyrosine kinase is a risk factor for seasonal allergic rhinitis

BACKGROUND

Identification of disease-associated single nucleotide polymorphisms (SNPs) in seasonal allergic rhinitis (SAR) may be facilitated by focusing on genes in a disease-associated pathway.

OBJECTIVE

To search for SNPs in genes that belong to the T-cell receptor (TCR) pathway and that change in expression in allergen-challenged CD4+ cells from patients with SAR.

METHODS

CD4+ cells from patients with SAR were analysed with gene expression microarrays. Allele, genotype and haplotype frequencies were compared in 251 patients and 386 healthy controls.

RESULTS

Gene expression microarray analysis of allergen-challenged CD4+ cells from patients with SAR showed that 25 of 38 TCR pathway genes were differentially expressed. A total of 62 SNPs were analysed in eight of the 25 genes; ICOS, IL4, IL5, IL13, CSF2, CTLA4, the inducible T-cell tyrosine kinase (ITK) and CD3D. Significant chi-squared values were identified for several markers in the ITK kinase gene region. A total of five SNPs were nominally significant at the 5% level. Haplotype analysis of the five significant SNPs showed increased frequency of a haplotype that covered most of the coding part of ITK. The functional relevance of ITK was supported by analysis of an independent material, which showed increased expression of ITK in allergen-challenged CD4+ cells from patients, but not from controls.

CONCLUSION

Analysis of SNPs in TCR pathway genes revealed that a haplotype that covers a major part of the coding sequence of ITK is a risk factor for SAR.