Influence of cytokine gene polymorphisms on IgA nephropathy.

Aims. Recently, polymorphisms of cytokine genes have been associated with altered gene expression and modified cytokine production. We evaluated the impact of TGF-beta1 gene Arg(25)-->Pro, TNFalpha gene G-308A and IL-6 gene G-174C polymorphisms on the clinical manifestations of IgA nephropathy. Patients and methods. The clinical course of 127 patients with biopsy-proven IgA nephropathy followed up for 6.6 +/- 6.0 years was studied. Patients were classified according to the slope of reciprocal serum creatinine into group A (slow progressors, n = 78) and group B (fast progressors, n = 49). TGF-beta1 gene Arg(25)-->Pro, TNFalpha gene G-308A and IL-6 gene G-174C polymorphisms were determined by PCR amplification followed by restriction digestion with the endonucleases Sau96 I, Nco I, and Lwe I respectively. Results. The genotype distribution of the investigated polymorphisms was similar in patients and control subjects (ns). Age, initial renal function, proteinuria, and blood pressure did not differ significantly between patients with different genotypes. The investigated polymorphisms were not associated with the progression of the IgA nephropathy, as shown by the similar genotype distribution in group A and group B (slow progressors: TGF-beta1, 92.3%; TNFalpha, 25.6%; IL-6, 74.4%; fast progressors: TGF-beta1, 85.7%; TNFalpha, 22.4%; IL-6: 81.6%, ns). Furthermore, these polymorphisms had no impact on renal survival in the Kaplan Meier analysis (ns). Conclusion. Our results suggest that TGF-beta1 gene Arg(25)-->Pro, TNFalpha gene G-308A, and IL-6 gene G-174C polymorphisms are not risk factors or markers of progression in Caucasian patients with IgA nephropathy.