YANG Shou-guo, WANG Chun-sheng，CHEN Hao，HONG Tao, LAI Hao, ZHU Shi-jie.
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Department of Cardiothoracic Surgery, Zhongshan Hospital of Fudan University, the Shanghai Institute of Cardiovascular Diseases, Shanghai, 200032, China
Objective To compare the distribution and expression of TGF-β1 in aortic wall of thoracic aortic dissection (TAD) versus thoracic aortic aneurysm (TAA) and explore the role of TGF-β1 in the pathogenesis of TAD and TAA. Methods Aortic specimens were obtained from patients underwent aortic procedures for TAD (n=20) and TAA (n=38). Double immunofluorescent staining of TGF-β1 and α-smooth muscle actin was performed in paraffin embedded slides for all aortic samples and semiquantified by fluorescent intensity analysis. The distribution of TGF-β1 within aortic wall and expression intensity were compared between two groups. Histopathologic examinations were performed with hematoxylin-eolin, Verhoeff van-Gieson and Masson's trichrome stain to determine the pathologic feature and extracellular matrix distribution. Several potential risk factors for dissection or aneurysm including age, gender, history of hypertension, history of aortic surgery, clinical etiology and maximal aortic diameter were analyzed with TGF-β1 expression. Results Histopathologic examination disclosed both TAD and TAA characterized with cystic medial degeneration and fragmented elastin lamella. TGF-β1 distributed unevenly across aortic wall with the highest expression level in tunica media, followed by intima then adventitia. The mean expression level of TGF-β1 for entire aortic wall was 70.71±9.70 for TAD group, less than that of 77.66±10.93 for TAA group (P<0.05). In intima, TAD group exhibited with TGF-β1 level of 62.54±8.81, less level than 72.14±5.85 for TAA group (P<0.05). In media, the TGF-β1 expression level was 79.26±12.77 in TAD group, and 86.82±13.47 in TAA group with TAD group less than TAA group (P<0.05). In adventitia, TGF-β1 expression level was 60.04±12.07 in TAD group and 61.52±18.29 in TAA group, no difference was detected between two group. No significant difference of TGF-β1 expression was detected referring several clinical factors. Conclusions TGF-β1 expression was down-regulated in aortic wall of TAD compared with TAA patients. The significant dysregulation of TGF-β1 in different layers of TAD implicated a crucial role of TGF-β1 in the evolution of thoracic aortic dissection.
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