Variable expression of cysteinyl leukotriene type I receptor splice variants in asthmatic females with different promoter haplotypes

BACKGROUND: Cysteinyl leukotrienes are potent inflammatory mediators implicated in the pathogenesis of asthma. Human cysteinyl leukotriene receptor 1 (CYSLTR1) gene contains five exons that are variably spliced. Within its promoter few polymorphisms were described. To date, there has been no evidence about the expression of different splice variants of CysLT(1 )in asthma and their association with CYSLTR1 promoter polymorphisms. The goal of our study was to investigate CysLT(1 )alternative transcripts expression in asthmatic patients with different CYSLTR1 promoter haplotypes. The study groups consisted of 44 patients with asthma, diagnosed according to GINA 2008 criteria and 18 healthy subjects. Genomic DNA and total RNA was extracted from peripheral blood mononuclear cells. Real-time PCR was performed with specific primers for transcript I [GenBank:DQ131799] and II [GenBank:DQ131800]. Fragments of the CYSLTR1 promoter were amplified by PCR and sequenced directly to identify four single nucleotide polymorphisms: C/T [SNP:rs321029], A/C [SNP:rs2637204], A/G [SNP:rs2806489] and C/T [SNP:rs7066737]. RESULTS: The expression of CysLT(1 )transcript I and II in asthma did not differ from its expression in healthy control group. However, in major alleles homozygotic CAAC/CAAC women with asthma we found significantly higher expression of transcript I as compared to heterozygous CAAC/TCGC women in that loci. CysLT(1 )transcript I expression tended to negative correlation with episodes of acute respiratory infection in our asthmatic population. Moreover, expression of CysLT(1 )transcript II in CAAC/CAAC homozygotic women with asthma was significantly lower than in CAAC/CAAC healthy control females. CONCLUSIONS: Genetic variants of CYSLTR1 promoter might be associated with gender specific expression of CysLT(1 )alternative transcripts in patients with asthma. CysLT(1 )splice variants expression might also correlate with the susceptibility to infection in asthmatic population.