Association of interleukin 18 gene polymorphism with susceptibility to the development of acute lung injury after cardiopulmonary bypass surgery

The activation and recruitment of neutrophil cells in lung tissue are the characteristic features of acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Interleukin 18 (IL-18) is a potent activator and inducer of accumulating neutrophils in lung, and higher IL-18 level has been shown to link to IL-18 gene -607C/C genotype. Therefore, the polymorphisms in IL-18 gene promoter were examined to investigate the association with susceptibility to the development of ALI after cardiopulmonary bypass (CPB) surgery in this study. The results showed the significant involvement of -607C/ genotype in patients with ALI (n = 18, 18/43, 41.9%) compared with those patients without ALI (n = 32, 32/155, 20.6%, P = 0.0037) and healthy controls (n = 198, 53/198, 26.8%, P = 0.06). The frequencies of -607C/C,C/A,A/A genotypes were 41.9%, 46.5%, and 11.6% in patients with ALI and 20.6%, 47.1%, and 32.3% in patients without ALI. The allelic frequency of C (65.1%) was significantly higher in patients with ALI than that of patients without ALI (44.2%) [odds ratio(OR) = 0.42, 95% confidence interval (CI) = 0.26 - 0.70; P = 0.0006]. No significant association of -137 polymorphism with susceptibility of ALI was found. There were no significant differences between the patients who had undergone CPB operation and healthy controls. In conclusion, our findings suggest that -607C/C genotype in IL-18 gene plays a pivotal role in the development of ALI after CPB surgery in Chinese Han population.