TNF-α mRNA expression correlates with TGF-β mRNA expression in vivo.

TNF-α is postulated to play a significant role in regulating TGF-β(1) expression. In lung fibroblasts, for example, TNF-α is supposed to induce TGF-β(1) via AP-1 activation. TNF-α receptor, knock-out mice are resistant to induced fibrosis and over-expression of TNF-α causes increased TGF-β(1) production in mice. Therefore, we investigated whether TNF-α mRNA levels are associated with the TGF-β(1) mRNA levels of blood leucocytes in humans. Quantitative real-time PCR of TNF-α and TGF-β(1) was performed in 118 Germans. Calculations of expression were made with the 2(-ΔΔCT) method. When the investigated population was divided in two groups (TNF-α low and TNF-α high) by the median of the determined TNF-α expression, highly significant (p < 0.0001) differences of TGF-β1 mRNA expression were revealed. Additionally, dividing the investigated population into quartiles of the determined TNF-α expression showed significantly different TGF-β1 mRNA expressions. Comparing the determined CT-values of TNF-α in context with these of TGF-β1, a coefficient of determination R(2) = 0.4635 was calculated. In this study we demonstrated in vivo a significant association of the relative TNF-α/B2M mRNA expression and the relative TGF-β(1)/B2M mRNA expression in 118 Germans.