Cross talk between TGF beta and TNF alfa in regression of myointimal hyperplasia

Background The phenomena involved in regression of arterial myointimal hyperplasia have not been analyzed in detail. Materials and methods In 24 Lewis rats, a 1-cm-long venous graft, obtained from syngenic Lewis rats, was implanted in the infrarenal aorta. After 4 wk, the grafts were removed and analyzed using scanning electron microscopy and histochemistry. The grafts showed evidence of myointimal hyperplasia; 16 of these explanted grafts were reimplanted in the vein circulation of syngenic Lewis rats. These grafts were harvested 2 wk (8 animals) and 8 wk (8 animals) later, showing complete regression of myointimal hyperplasia. Results Regression of experimental myointimal hyperplasia was correlated with the simultaneous and complementary action of Transforming Growth Factor beta and Tumor Necrosis Factor alfa. Inflammatory cytokines (IL1, IL2, and IL6) inhibit Tumor Necrosis Factor alfa-induced apoptosis. Conclusions Regression of myointimal hyperplasia is an active process, which implies the action of several inhibitory factors. The analysis of these phenomena can lead to new therapeutic approaches to prevent myointimal hyperplasia progression.