Among the genes identified, variants in T-box 21 ( TBX21) and Fc fragment of IgE receptor II ( FCER2) contribute indirectly to the variability in the response to ICS by altering the inflammatory mechanisms in asthma, while other genes such as corticotropin releasing hormone receptor 1 ( CRHR1), nuclear receptor subfamily 3 group C member 1 ( NR3C1), stress induced phosphoprotein 1 ( STIP1), dual specificity phosphatase 1 (DUSP1), glucocorticoid induced 1 (GLCCI1), histone deacetylase 1 (HDAC), ORMDL sphingolipid biosynthesis regulator 3 (ORMDL3), and vascular endothelial growth factors (VEGF) directly affect this variability through the anti-inflammatory mechanisms of ICS.
Eighty-two children (56 boys/26 girls, mean age 9.6 ± 3.2 years) with moderate-severe asthma exacerbation were genotyped for eight single-nucleotide polymorphisms that were a priori associated with ICS response in chronic asthma treatment: glucocorticosteroid receptor (NR3C1) rs41423247; corticotrophin-releasing hormone receptor1 (CRHR1) rs242939, rs242941, and rs1876828; T-box 21 (TBX21) rs2240017; glucocorticoid-induced transcript 1 (GLCCl1); and T gene rs3099266 and rs2305089.
This study investigated the influence of TBX21 and HLX1 single nucleotide polymorphisms (SNPs), which have previously been shown to be associated with asthma, on T(H)1/T(H)2 lineage cytokines at birth.
Of the four genetic polymorphisms examined, NK2R G231E G>A and TBX21H33Q C>G were significantly associated with asthma control status (P = 0.041 and P = 0.006).
An association between a specific TBX21 haplotype and allergic asthma in children is demonstrated for the first time and might explain previously detected associations between SNPs within TBX21 and asthma and bronchial hyperresponsiveness.
In conclusion, (1) p38MAPK-pathway rather than ERK-pathway may play a more basic role in the regulation of the increased T-bet expression in asthma, and (2) ERK- and p38MAPK-activation modulate IFNgamma expression independently of T-bet and this regulatory role of ERK-1/-2 on IFNgamma release is impaired in asthma.
Mice with a targeted deletion of the T-bet gene and severe combined immunodeficient mice receiving CD4+ cells from T-bet knockout mice spontaneously demonstrated multiple physiological and inflammatory features characteristic of asthma.