Background: Little is known about the overall impact of immunosuppressive drugs on the prostate. The study aimed to determine the impact of different protocols of immunosuppressive treatment on the structure of the rat ventral prostate. Methods: For 6 months, 48 male Wistar rats received immunosuppressive drugs: cyclosporin A, tacrolimus, mycophenolate mofetil, rapamycin, and prednisone, according to three-drug protocols. Light and transmission electron microscopic studies, and quantitative evaluation of immunohistochemical expression of selected intermediate filaments, CD117+ mast cells, and CD138+ plasma cells were performed in the rat ventral prostate. Results: In all experimental groups, acini focal hyperplasia, changes to the ultrastructure of the glandular epithelium, changes in the expression of cytokeratins and desmin, and numerous mast and plasma cells in the prostate stroma were found. In cyclosporine-A-based groups, atrophy and numerous intracellular vacuoles were observed. In groups where a three-drug treatment was replaced with rapamycin, morphological alterations were less severe compared to those without conversion. Conclusions: In the rat ventral prostate, (1) immunosuppressive protocols affect the morphology and immunohistochemical expression of intermediate filaments, (2) morphological alterations, expression, and localization of selected proteins are not connected with adenocarcinoma development, and (3) conversion of the treatment to rapamycin may prevent hyperplastic abnormalities.
Keywords: Immunosuppressants; intermediate filaments; mast cells; plasma cells; rapamycin; rat; ultrastructure; ventral prostate.