Interleukine-6 promoter polymorphism -174G/C is not associated with acute rejection episodes after kidney transplantation: a meta-analysis

Proinflammatory and anti-inflammatory cytokines play key roles in immunologic phenomena leading to Acute Rejection Episodes (ARE) after kidney transplantation which are responsible for kidney graft loss. In particular, interleukin-6 (IL-6), regulates the immune response by acting on various cells including differentiation and maturation of B and T cells or macrophages. This investigation seek to summarize current knowledge on the clinical impact on ARE of IL-6 -174G/C polymorphisms. Relevant published data was retrieved through Medline pertaining to kidney transplant outcome and IL-6 polymorphisms. Odds ratios (OR) with 95 % confidence intervals (CI) were used to assess the strength of the association. Z test was used to determine the significance of the pooled OR. Statistical heterogeneity was measured using the Q statistic. The effect of heterogeneity was quantified using the I2-statistic. A total of 16 studies, including 672 ARE transplanted cases and 1290 transplanted controls without rejection episodes, were collected in this meta-analysis. For high vs. low IL-6 genotypes, no heterogeneity (Q =12.07, p=0.67, I2 =0.0%) was observed among individual estimates, and original data was combined using the fixed-effects model. For the total population, we found no association between G/G and G/C IL-6 genotypes with ARE, we obtained an effect summary OR=1.14, with a 95 % CI=0.84-1.55, and p=0.4. In conclusion, in recipients with a high producer (G/G and G/C) genotype of IL-6, the -174G/C polymorphism is not associated with acute rejection of renal allograft