Quantitative Real-time PCR of TNF-α and TGF-β1 was performed in 178 Germans. Calculations of expression were made with the 2x2212;ΔΔCT method. Detection of the x2212;308 promoter polymorphism of the TNF-α gene was performed by rapid capillary PCR with melting curve analysis.
The relative TNF-α mRNA expression revealed significant differences between the TNF-α x2212;308 homozygote wild-type G/G (0.00079 ± 0.00011; n = 113) and the heterozygote genotype G/A (0.0005 ± 0.00008; n = 52; p = 0.030) as well as between homozygote wild-type G/G and the homozygote mutant A/A (0.00029 ± 0.00009; n = 5; p = 0.004). The relative TGF-β mRNA expression showed, similar to TNF-α, the highest mRNA expression was seen within the TNF-α x2212;308 homozygote wild-types, while the lowest mRNA expression lay within the homozygote mutant-types.
Our findings suggest that the G-allele of TNF-α x2212;308 is associated with a significantly higher TNF-α mRNA expression compared to the A-allele and that this also reflects in TGF-β expression. Therefore we support the thesis that TGF-β is regulated by TNF-α.