TUMOR-NECROSIS-FACTOR-ALPHA - INHIBITS COLLAGEN-SYNTHESIS IN HUMAN AND RAT GRANULATION-TISSUE FIBROBLASTS

The purpose of the study was to examine the effects of tumor necrosis factor-alpha (TNF-alpha) on collagen gene expression in rat and human granulation tissue fibroblast cultures. The cells were exposed to 0.1, 1, 10, or 100 ng/ml of TNF-alpha, and the rate of collagen synthesis was measured as synthesis of protein-bound H-3-hydroxyproline. Total c ellular RNA was isolated from fibroblasts, and measurements of specifi c cellular RNAs from fibroblasts were performed by Northern blot hybri dizations using P-32-labeled cDNA probes. In cultures of rat granulati on tissue fibroblasts TNF-alpha decreased H-3-hydroxyproline productio n to about 75% of that in controls and it also decreased pro alpha(I) and pro alpha 1(III) collagen mRNA levels, maximally to 33% and 23% of the control levels, respectively. In cultures of human granulation ti ssue fibroblasts a similar inhibiting effect in the production of coll agen was seen. TNF-alpha decreased the production of H-3-hydroxyprolin e to 56% of the control value with a dose of 100 ng/ml also having an inhibiting effect on pro alpha 1(I) collagen mRNA levels of up to 43% of the control level. However, no effect was seen on pro alpha 1(III) collagen mRNA levels.