Relationship between interleukin-18-607C/A gene polymorphism and severity of enterovirus-71 encephalitis in Chinese children
Abstract Background: Interleukin-18 (IL-18), a pro-inflammatory cytokine encoded by IL-18 and known as interferon (IFN)-γ inducing factor, plays an important role in the innate immune system. Single nucleotide polymorphisms (SNPs) of IL-18-607C/A have been reported to be associated with many infectious and immune-related diseases. However, there is no evidence of its association with enterovirus 71 (EV71)-infectious encephalitis. This study aimed to explore the association between the promoter region polymorphisms (-607C/A) of IL-18 and the severity of EV71 encephalitis in Chinese children.Methods: We analyzed the polymorphisms of IL-18-607C/A in 185 EV71-infected patients and 214 controls for genetic association research. Clinical features and auxiliary examination results were collected and compared in the cases. The serum concentration of IFN-γ was detected using enzyme-linked immunosorbent assays (ELISA). Results: The frequency of IL-18-607 AA genotype and allele in EV71-infected patients was significantly higher than that in the controls (32.4% vs 21.5%, P=0.042, 55.1% vs 46.0%, P=0.001). Furthermore, a difference was found in severe EV71 and mild encephalitis cases (53.0% vs 20.5%, P=0.003, 67.3% vs 50%, P=0.016). The serum concentration of IFN-γ in patients with encephalitis was much lower in AA genotypes (106.0±8.9 pg/mL) than in CA and CC genotypes (120.4±8.9 and 128.1±7.5 pg/mL, respectively, P<0.001). The duration of fever and blood glucose level was obviously higher in AA than in CA and CC genotypes.Conclusions: Children with IL-18-607AA genotype were more susceptible to developing severe EV71-associated encephalitis in this study in China.