Association of IL-6 promoter polymorphism -174C/G with outcome in severe sepsis

Introduction

IL-6 is a multifunctional cytokine that plays an essential role in the pathogenesis of severe sepsis. The G/C polymorphism at position -174 of the IL-6 gene is associated with an adverse outcome in a number of inflammatory diseases, although its association with outcome in adult patients with severe sepsis remains unclear. We tested the hypothesis that IL-6 promoter polymorphism -174 C/G is associated with increased mortality among ICU patients with severe sepsis.

Methods

The study was conducted in the mixed medical–surgical adult ICU of Stradins University Hospital in Riga in 2007. A total of 69 critically ill patients who met the proposed severe sepsis criteria were included. The IL-6 -174 G/C polymorphism was genotyped by sequencing. Patients were followed up throughout their stay in the ICU to their clinical outcome. The frequency distribution of the genotypes in the patient subgroups were compared using the Pearson χ² test. P < 0.05 was considered to indicate statistical significance.

Results

Of the 69 severe sepsis patients observed, 18 (26%) had G/G at position -174 of IL-6 gene, 41 (59%) were heterozygous C/G, and 10 (14%) were homozygous C/C. ICU mortality in the G/G group was eight patients (44%), in the C/G group 14 patients (34%) and in the C/C group seven patients (70%). There was no statistically significant difference between groups (P > 0.05).

Conclusion

We found no association between IL-6 gene promoter polymorphism -174 C/G and ICU mortality in severe sepsis patients.