Impact of IL-4R (rs1805011) Gene Polymorphism on IL-4 Serum Level in Iraqi Allergic Asthma Patients

Abstract

Allergic asthma is a chronic inflammatory disease of the airway in which exposure to allergens leads to a complex interaction between genetic and environmental factors while many cytokines are involved in the immune mechanism of the disease.IL-4R play a vital role in the pathogenesis of asthma. The subject of this study is design to investigate an association of single nucleotide polymorphism SNP of the (rs1805011, A˃C) gene and its serum level with allergic asthma susceptible in some Iraqi patients. Study consists of two groups: first group consist of sixty asthma patients (34 female and 26 male) and second group contain sixty apparently healthy as a control group (30 male and 20 female). The age of the participants ranged from 15-55 years old. Recruited from the Alzahra’a Center for Asthma Allergy in Baghdad during the period extended from January to April /2022, all information’s of the study groups were collected in questionnaire forma such as age, gender, family history, season, smoker and non-smoker and severity of the disease were also included. The level of IL-4R in the blood serum which detected by ELISA- Enzyme-linked-immune-sorbent assay, while (real-time PCR-HRM) technique was used to investigate the Single nucleotide polymorphism. The result of the questionnaire for the group of patients and apparently healthy people was as follows: the highest incidence of asthma cases was in the age group (15-30 years = 50%). The percentage of family history of the disease among patients was (91.67%), while the percentage (8.33%) for those without a family history. The percentage of smokers was higher among patients (63.33%) compared to non-smokers (36.67%), and it was observed that most cases of severe asthma (73.33%) followed by mild asthma (26.67%), and patients who were sensitive to various allergens (68.33%) while (31.67%) have no sensitivity. The laboratory results showed an elevated in mean level of IL-4R in asthmatic patients compared to the control group, and the mean level was (22.99 ng/l) in patients, while it was in control (13.98 ng/l) with significant differences (p=0.0001). The ROC curve analysis of IL-4R described an AUC of 0.887. The results of the allele and genotype of SNP (rs1805011 A˃C) also showed clear differences between patients and the control group, the frequency of the C allele was higher in patients compared to the control group (39.2%vs.30.0%) respectively with a significant difference (P=0.044), the frequency of the CC genotype was significantly higher (p=0.034) than in the control group (26.6% vs.10.0%) respectively. In conclusion, genetic and environmental factors such as smoking, family history of asthma, disease severity, allergens, increased level of IL-4R in serum, presence of the C allele and CC genotype in IL-4R gene. They may be considered as important factors in the pathogenesis of allergic asthma in Iraqi patients.