Aneurysms are common in the abdominal and thoracic regions of the aorta and can cause death due to dissection or rupture. Traditionally, thoracic aortic aneurysms have been labeled as a degenerative disease, characterized by alterations in extracellular matrix and loss of smooth muscle cells (SMCs) in the medial layer of the aortic wall. In this issue of the JCI, Li and colleagues introduce an unconventional concept by demonstrating that mTOR-dependent proliferative SMCs render the aortic wall vulnerable to dilatation and dissection rather than prevent disease progression. These vascular SMCs, termed degradative SMCs, compromise the medial properties and function of the aortic wall by enhanced proteolytic and phagocytic activity; however, the cells do not transdifferentiate into macrophages. The degradative SMC phenotype also worsens atherosclerotic disease and could thus be considered as a therapeutic target for diverse aortic diseases.

中文翻译：

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增殖性，降解性平滑肌细胞促进主动脉疾病。

动脉瘤常见于主动脉的腹部和胸部，可能因解剖或破裂而导致死亡。传统上，胸主动脉瘤已被标记为退行性疾病，其特征在于细胞外基质的改变和主动脉壁内侧层中平滑肌细胞（SMC）的丢失。在本期JCI中，Li及其同事通过证明mTOR依赖性增生SMC使主动脉壁易于扩张和解剖而不是阻止疾病进展，从而引入了一种非常规的概念。这些血管性SMC，称为降解性SMC，通过增强的蛋白水解和吞噬活性而损害了主动脉壁的内质和功能。但是，细胞不会分化为巨噬细胞。