Association between donor and recipient Interleukin-18 gene polymorphisms and the risk of infection after liver transplantation

Abstract

Purpose: The purpose of this study was to retrospectively evaluate the association between Interleukin-18 (IL-18) gene polymorphisms of the donor and recipient in liver transplant patients with bacterial infections. Methods: Five single nucleotide polymorphisms (SNPs) (rs7106524, rs5744247, rs1946518, rs549908 and rs187238) of the IL-18 gene from the donors were genotyped and their association with post-operative bacterial infections was evaluated in liver transplant patients (N=113). A second independent group of liver transplant patients from a different organ transplant centre was also recruited for validation purposes (N=44). Results: IL-18 mRNA mean expression levels and protein levels were significantly lower in liver transplant patients with bacterial infections. For the donor SNP rs1946518, more recipients carried the A allele in the bacterial-infected group than the uninfected group (61.4% vs 39.7%; P ≤0.002). The mean IL-18 mRNA expression and protein levels were significantly lower in the transplanted livers of recipients carrying the rs1946518 AA genotype compared with those from recipients with CC genotype (3.64, 3.33 vs. 2.75, P≤0.048). The A allele of rs1946518 also resulted in lower luciferase activity than the C allele in a reporter assay. The area under ROC curve indicated that the rs1946518 SNP genotype in the donor liver predicted an increased risk of bacterial infection after liver transplantation (AUROC>0.82). Conclusions: These findings indicate that the IL-18 rs1946518 SNP in the donor liver is a risk factor for developing bacterial infection after liver transplantation.