TGF-β1 expression and distribution in the extracellular matrix of the dissected wall of thoracic aorta

Abstract

Objective Mechanisms for the dissection of aorta, a devastating disease, remain unknown. Studies showed that cytokine transforming growth factor (TGF)-131, a multifunctional regulator, was highly expressed in the aneurysms or dis-section of aorta and was responsible for the onset of the diseases. We try to explore the mechanisms of thoracic aortic dissection (TAD) by comparing the expression and distribution of TGF-β1 in the aortic wall and analyzing the association of TGF-β1 with extracellular matrix (ECM) in patients with TAD and control subjects. Methods Aortic specimens taken from surgical pa-tients with TAD( n = 20 ) at Zhongshao Hospital and organ donors ( n = 20, controls) were prepared with paraffin embedded tis-sue slide. ECM was investigated with hematoxylin-eosin, Verhoeff van-Giesen (EVG) and Maason's triehrome (MT) staining.Distribution and expression of TGF-β1 within aortic wall was examined with double immunofluoreseent staining and semi-quan-tiffed by fluoreseent intensity analysis. The expression of TGF-β1 in the two groups and among various layers of the arterial wall was compared. Results TAD was morphologically characterized by decreased and disrupted elastic fibers in the tunica media of the aorta wall with hyperplasia of the collagen fibers. TGF-β1 was expressed unevenly within aortic wall, with highest in the media, followed by intima and adventitia, in both TAD patients and eantrols. Specimen from TAD patients exhibited overall in-creased TGF-β1 expression by 9.56% as compared with that from the controls ( P <0.05 ). TGF-131 expression was increased by 16.09% (P<0.05) in the media and 16.75% (P<0.05) in the adventitia in TAD group as compared with those in the control group, but no difference was detected in intima between the two groups. TGF-β1 distribution histogram analysis dis-closed that TGF-β1 expression in the tunica media was evident in the elastic fibers, and was increased by 34.83% in TAD pa-tients as compared with that in the controls (P <0. 01 ). No significant associations between TGF-β1 expression and age, gen-der, maximal aortic diameter and type of dissection in TAD patients were detected. Conclusion TGF-β1 expression is up-reg-ulated and unevenly distributed in the dissected aortic wall of TAD patients. The finding that TGF-β1 was significantly up-regulated and condensed in the elastic fibers of the tuniea media suggested the crucial role of TGF-β1 in the development of TAD. Key words: Aorta thoracic; Transforming; Growth; Facwrβ; Extracellular matrix