Humphrey J D
Department of Biomedical Engineering, Yale University, and Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT 06520, USA.
J Vasc Res. 2013;50(1):1-10. doi: 10.1159/000342436. Epub 2012 Sep 25.
Four distinguishing histopathological characteristics of thoracic aortic aneurysms and dissections (TAADs) are the fragmentation or degradation of elastic fibers, loss of smooth muscle, pooling of glycosaminoglycans, and remodeling of fibrillar collagens. Of these, pooling of glycosaminoglycans appears to be unique to these lesions.
This review acknowledges the importance of dysregulated transforming growth factor-β (TGF-β) in TAADs and offers a complementary hypothesis that increased TGF-β could contribute to the accumulation of glycosaminoglycans in the media of the proximal thoracic aorta. Regardless, observed pools of glycosaminoglycans could decrease tensile strength, cause stress concentrations, and increase intralamellar swelling pressure, all of which could initiate local delaminations that could subsequently propagate as dissections and result in a false lumen or rupture.
There is a pressing need to investigate potential mechanical as well as biological consequences of accumulated glycosaminoglycans in TAADs and to elucidate responsible signaling pathways, with particular attention to synthetic cells of nonmesodermal lineage. Such research could provide insight into the mechanisms of dissection and the seemingly paradoxical role of the over-expression of a cytokine that is typically associated with fibrosis but is implicated in a degenerative disease of the aorta that can result in a catastrophic mechanical failure.
胸主动脉瘤和夹层（TAADs）有四个显著的组织病理学特征，即弹性纤维的断裂或降解、平滑肌的丧失、糖胺聚糖的积聚以及纤维状胶原的重塑。其中，糖胺聚糖的积聚似乎是这些病变所特有的。
本综述承认转化生长因子-β（TGF-β）失调在TAADs中的重要性，并提出一个补充假说，即TGF-β增加可能导致胸主动脉近端中膜糖胺聚糖的积聚。无论如何，观察到的糖胺聚糖池可能会降低拉伸强度、引起应力集中并增加层内肿胀压力，所有这些都可能引发局部剥离，随后可能发展为夹层并导致假腔或破裂。
迫切需要研究TAADs中积聚的糖胺聚糖的潜在机械和生物学后果，并阐明相关的信号通路，尤其要关注非中胚层谱系的合成细胞。此类研究可以深入了解夹层的机制以及一种通常与纤维化相关但却涉及一种可导致灾难性机械故障的主动脉退行性疾病的细胞因子过度表达所起的看似矛盾的作用。
