RESUMEN
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.
Asunto(s)
Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD4-Positivos/inmunología , Predisposición Genética a la Enfermedad , Proteínas Tirosina Quinasas/genética , Rinitis Alérgica Estacional/genética , Células Th2/efectos de los fármacos , Adolescente , Adulto , Alelos , Alérgenos/farmacología , Linfocitos T CD4-Positivos/enzimología , Linfocitos T CD4-Positivos/metabolismo , Exones/genética , Exones/inmunología , Femenino , Perfilación de la Expresión Génica , Frecuencia de los Genes/genética , Frecuencia de los Genes/inmunología , Haplotipos/genética , Haplotipos/inmunología , Humanos , Intrones/genética , Intrones/inmunología , Masculino , Persona de Mediana Edad , Análisis de Secuencia por Matrices de Oligonucleótidos , Polen/inmunología , Polimorfismo de Nucleótido Simple/genética , Polimorfismo de Nucleótido Simple/inmunología , Proteínas Tirosina Quinasas/efectos de los fármacos , Proteínas Tirosina Quinasas/inmunología , Receptores de Antígenos de Linfocitos T/efectos de los fármacos , Receptores de Antígenos de Linfocitos T/inmunología , Rinitis Alérgica Estacional/inmunología , Transducción de Señal/genética , Transducción de Señal/inmunología , Células Th2/enzimología , Células Th2/inmunología , Células Th2/metabolismo , Adulto JovenRESUMEN
The murine complement receptor type 2 gene (Cr2/CD21) is expressed by murine B and follicular dendritic cells, but not murine T cells. We have previously shown that appropriate transcriptional control of the CD21 gene requires the CD21 promoter as well as intronic sequences. We have also demonstrated that altering chromatin structure by inhibiting histone deacetylases induces CD21 expression in murine T cells by increasing the accessibility of promoter and intronic regulatory elements. In this report, we identify seven distinct regulatory areas within the first intron of the murine CD21 gene that are conserved between mouse and human CD21 intronic sequences. EMSA competition and supershift analyses reveal the formation of multiple DNA-protein complexes at these sites that include Yin Yang 1, Oct1, and NFAT-4. NFAT-containing complexes were altered in B cells treated with the NFAT inhibitor cyclosporin A and correlated with a repression of CD21 gene transcription implicating NFAT transcriptional control. Functional data revealed that no single region conferred cell-specific reporter gene expression, but rather the entire CD21 regulatory element was required to confer cell-specific gene expression. Taken together, these data demonstrate the formation of repeating, overlapping regulatory modules, all of which are required to coordinately control the cell-specific expression of the murine CD21 gene. We propose a model in which Yin Yang 1 and Oct1 may recruit histone deacetylase to multiple sites in the CD21 intronic regulatory element in nonexpressing cells and NFAT either displaces this histone deacetylase or recruits a histone acetylase to allow the formation of a functional transcriptional complex in expressing cells.