C-590T Promoter Polymorphism of the Interleukin (IL)-4 Gene Is Associated with an Increased Susceptibility to Nasal Polyposis

Recent studies have shown interleukin 4 (IL-4) and 5 lipoxygenase (5-LO) to play an important role in development of nasal polyposis. Investigation into the genetic factors associated with allergic and non-allergic nasal polyposis has been examined for more than fifteen years. Despite these efforts, the genetic factors underlying the development of nasal polyposis have yet to be clearly understood. The current study examined the relationship between C-590T promoter polymorphisms of the IL-4 gene and the presence of nasal polyps. Additionally, we examined the levels of 5-LO expression in nasal polyp tissue and its association with the IL-4 promoter gene polymorphisms. A total of 320 subjects were enrolled in the study, of which 256 were healthy controls and 64 were patients with nasal polyps. The Real-Time PCR HRM-based method was used to determine the genotypes of IL-4 C-590T. The expression of 5-LO within the 64 samples of nasal polyp tissue was determined by immunohistochemical staining to examine the association of 5-LO with the IL-4 C-590T genotype. Genetic analysis showed a significant difference in the frequencies of the IL-4 polymorphisms at C-590T in patients with nasal polyps as compared with controls (p<0.001). No significant difference was seen in the expression of 5-LO among genotypes in patients with nasal polyps (p=0.139). The results suggest that the inheritance of TT and CT genotypes at the IL-4 C-590T promoter gene is associated with nasal polyps however, there is no association between the expression of 5-LO in nasal polyp tissues and IL-4 C-590T genotypes in patients with nasal polyps