Abstract 3054: Comparison of Transforming Growth Factor-β1 Expression in Aortic Wall of Thoracic Aortic Aneurysm Versus Dissection

Abstract

Background The underlying mechanism of thoracic aortic aneurysm (TAA) and dissection(TAD) was undetermined, and one controversy lies in whether they represent the different dvelopement period of the same disorder or totally diferent diseases. This study is in aim to compare the expression and distribution of Transforming Growth Factors(TGF) β1 in the aortic wall of TAA versus TAD patients. Method Aortic specimens were obtained from patients underwent to aortic procedures for TAA (n=38) and TAD (n=20) at UCLA , and control aorta (CN) from organ donnor (n=20). Double immunofluorescent stainning of TGF-β1 and α-smooth muscle actin were performed with paraffin embeded slides for all aortic samples and semiquantified by fluorescent intensity analysis. Histopathologic examination were performed with HE, Verhoeff van-Gieson and Masson’s trichrome stain. Results TAA and TAD patients exhibited an up-regulation of TGF-β1 to 120.3% and 109.6% compared with CN separately (P<0.05), with TAA higher than TAD (P<0.05). TGF-β1 distributed unevenly across aortic wall with the highest levels expression in tunica media, followed by intima then adventitia. In intima, TGF-β1 was expressed at the same level for TAD as CN, but was increased to 115.2% for TAA compared to CN (P<0.05). In media, TGF-β1 increased by 127.2% in TAA and 116.1% in TAD compared to CN (P<0.01), with TAA being higher than TAD (P<0.05). In adventitia, TGF- β1 was up-regulated to 119.6% and 116.7% for TAA and TAD compared to CN (P<0.05). Nucleus density analysis showed cellular plasia in adventitia of TAA and TAD than CN (P<0.05 ), while TAD patients demonstrated a higher nucleus density than TAA in intima and adventitia (P<0.05). α-actin was increased in media of TAA and TAD to 164.5% and 120% than CN (P<0.01 and P<0.05). Attenuated and interrupted elastin and mild to severe cystic medial degeneration were characteristic histopathologic finding in 29 (76.3%) TAA and 17(85%) TAD patients. Conclusions TGF- β1 expression was up-regulated in aortic wall of TAA and TAD compared to CN. The significant higher levels of TGF- β1 in intima and media in TAA versus TAD patients implicated a probable positive effect of TGF- β1 to maintain aortic wall integrity, and/or greater comsamption of TGF- β1 in the aortic dissection.