Influence of interleukin-6 promoter polymorphism -174 g/c on kidney graft outcome

Background: The cytokine interleukin-6 (IL-6) is important in both immune responses and cardiovascular diseases. The IL-6 promoter polymorphism -174 G/C is associated with increased plasma concentrations of IL-6. The relationship between IL-6 polymorphisms and graft survival, cardiovascular events, and new-onset diabetes mellitus after kidney transplantation is controversial.

Objective: To analyze whether IL-6 (-174 G/C) polymorphism influences kidney graft survival or development of chronic allograft nephropathy, cardiovascular events, or new- onset diabetes.

Methods: The IL-6 promoter polymorphism (-174 G/C) was analyzed using the polymerase chain reaction with sequence-specific primers in 335 kidney transplant recipients. Data for graft survival, chronic graft nephropathy, cardiovascular events, and new-onset diabetes were obtained retrospectively from clinical records. Categorical variables were compared between individuals with CC, GG, and GC genotypes using χ2 tests. Survival analysis was performed using the Kaplan-Meier method, comparing groups using the log-rank test.

Results: No significant differences were observed in 5-year graft survival between individuals with CC and GC/GG genotypes (85.3% vs 77.1%; P=.22). Nor were significant differences noted in the rates of chronic allograft nephropathy (37.5% vs 33.8%; P=.48), cardiovascular events (10.0% vs 23.0%; P=.10), or new-onset diabetes (7.5% vs 11.8%; P=.28).

Conclusion: There is no association between IL-6 (-174 G/C) polymorphism and graft survival or development of chronic allograft nephropathy, cardiovascular events, or new- onset diabetes.