Background: Polymorphism in corticotrophin releasing hormone receptor 1 (CRHR1) gene, a key regulatory component of hypothalamic-pituitary-adrenal (HPA) axis and its correlation with the levels of various T-helper (Th) cell cytokines which have the major role in inflammatory response in asthma was not studied earlier. We hypothesised that polymorphism in CRHR1 gene may be associated with the concentration of various Th cytokines.

Objective: The aim of study was to determine the polymorphism in CRHR1 gene and their correlation with the expression of IFN- γ, IL-6, IL-10 and IL-22 cytokines in asthma.

Methods: Sequencing of CRHR1 gene single strand gene amplicons of specifically designed primers to determine the polymorphism and ELISA to evaluate the cytokine levels in 35 North Indian study subjects in each asthma patient (AP) and healthy control (HC) groups were carried out. Plasma separation and DNA isolation from whole blood packed cells were performed.

Results: Two single nucleotide polymorphism (SNP) (rs242941 and rs242940) were determined in sequenced region of CRHR1 gene in North Indian population. The plasma levels of IFN- γ and IL-6 were to be significantly elevated and levels of IL-10 were significantly decreased and IL-22 were non significantly increased in AP as compared to HC group. Correlation between forced expiratory volume in one-second (FEV1) % (predicted) and cytokines concentrations were also performed to analyse the severity of disease.

Conclusion: None of the allele of SNP was found significantly associated with asthma but genotypes of SNPs of CRHR1 gene weresignificantly correlated with FEV1% (predicted) and concentration of IFN- γ and IL-6 cytokines.

Keywords: Asthma, Polymorphism, CRHR1, Cytokine, ELISA and FEV1%, SNP.

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Prof. Surendra Kumar Bansal

Dept of Biochemistry, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi-110007, India