Analysis of G(-174) CIL-6 polymorphism and plasma concentrations of inflammatory markers in patients with type 2 diabetes and peripheral arterial disease

Aims: To determine whether the G( 2174) C interleukin 6 ( IL-6) polymorphism influences the development of peripheral arterial disease ( PAD) in individuals with type 2 diabetes. This was investigated by comparing the distribution of G( 2174) C genotypes between patients with type 2 diabetes and PAD ( PAD(+)) and those with type 2 diabetes but without PAD ( PAD(-)). Plasma concentrations of IL-6, fibrinogen, C reactive protein ( CRP), and vascular endothelial growth factor ( VEGF) were also compared in PAD(+) and PAD(-) patients. Methods: Blood samples were collected from 146 PAD(+) and 144 PAD(-) patients. SfaNI was used to determine the G( 2174) C genotype. Plasma concentrations of IL-6, fibrinogen, CRP, and VEGF were measured by an enzyme linked immunosorbent assay. Results: The GG genotype was more common in PAD(+) patients than in PAD(-) patients. PAD+ patients also had increased mean plasma concentrations of IL-6, fibrinogen, CRP, and VEGF compared with PAD(-) patients. Mean plasma concentrations of IL-6, fibrinogen, and CRP in both PAD+ and PAD 2 patients were higher in those with the GG genotype than in those with the GC or CC genotypes. In contrast, mean plasma concentrations of VEGF in PAD(+) and PAD(-) patients were not significantly different between those with different G( 2174) C genotypes. Conclusions: These results support a model in which the GG genotype promotes PAD development among individuals with type 2 diabetes by inducing increased release of IL-6. Higher concentrations of IL-6 among those with the GG genotype is associated with increased plasma concentrations of fibrinogen and CRP.