Transforming growth factor beta1/Smad signalling pathway of aortic disorders: histopathological and immunohistochemical studies

Background: The aim of the present study was to evaluate the expressions and biological functions of the TGF-Β1/Smad signalling pathway of aortic disorders by way of histopathological and immunohistochemical studies. Material and methods: Aortic specimens of 20 patients with aortic dissection, 9 patients with aortic aneurysm, 9 patients with coronary artery disease, and 5 deceased healthy adults were collected. The samples were stained with haematoxylin -eosin, Masson’s trichrome, van Gieson, and alcian blue, and with immunohistochemical stainings to detect TGF-Β1, type I receptor (TΒRI), Smad2/3, Smad4, and Smad7. Results: Masson’s trichrome and van Gieson stainings showed attenuated collagens in the aorta of the patients with aortic dissection and aortic aneurysm. TGF-Β1, TΒRI, and Smad2/3 mainly showed a cytoplasmic immunoreactivity in the aortic media, Smad4 immunoreactivity was predominantly located in the cytoplasm and/or the nucleus of the aortic media, and Smad7 immunoreactivity was present in the nucleus of the aortic media and intima. The TGF-Β1 signalling pathway proteins were similarly expressed in the aorta of aortic dissection and aortic aneurysm patients, while they were less pronounced in the aorta of coronary artery disease patients, and weak or negative in the aorta of healthy control individuals. Conclusions: These observations support the notion that there is an association between the TGF-Β1/Smad pathway and the pathological events of the aorta. Dysregulation of the TGF-Β1/Smad pathway may predispose the pathologenesis of aortic disorders