The phytoestrogen biochanin a attenuates acute cardiac allograft rejection without affecting the reproductive system – In vivo and in vitro studies

Objectives: We investigated the effects of biochaninA and ethinylestradiol, selective estrogen receptor beta and alpha agonists, respectively on acute cardiac allograft rejection, uterine effects, adhesion molecule and MHC-II expression in experimental transplantation and verified the observations using in-vitro cell culture.

Material and Methods: Heterotopic cardiac transplantations were performed in the rat strain combination Lewis to F344. The study groups received biochaninA or ethinylestradiol by oral gavage beginning on day -2, the control group received no treatment. Grafts and uteri were harvested on the fifth postoperative day and blood was taken for drug plasma level quantifications. Purified (MACS) Lewis aortic endothelial cell cultures were pre-treated with biochaninA or ethinylestradiol and stimulated with TNF-alpha or IFN-gamma. Surface protein expression was quantified by immunofluorescence, FACS and western-blotting. Lymphocyte-endothelium adhesion assays were performed using purified (MACS) F344 lymphocytes.

Results: Both biochaninA and ethinylestradiol treatment significantly reduced graft mononuclear infiltration of CD8- and ED1-pos. cells and markedly reduced ISHLT grading compared to untreated controls. Either agent significantly inhibited endothelial VCAM-1 upregulation during graft rejection and during TNF-a-stimulation in vitro, whereas no effect was observed for ICAM-1 upregulation. BiochaninA but not ethinylestradiol significantly reduced MHC-II upregulation in vivo and in vitro. Ethinylestradiol treatment strongly affected uterus growth, whereas biochaninA did not.

Conclusions: Only the treatment with the phytoestrogen biochaninA reduced endothelial MHC-II expression in vivo and in vitro and showed the desired cardioprotective effect without affecting the reproduction system. A supplemental use of phytoestrogens after cardiac transplantation may provide further benefits in the clinical setting and their application to men may also be considered.