Excessive glycosylation drives thoracic aortic aneurysm formation through integrated stress response

BACKGROUND AND AIMS: Thoracic aortic aneurysms and dissections (TAADs) are depicted by aortic medial degeneration characterized by glycan-rich matrix accumulation. Marfan syndrome (MFS) is the most common inherited connective tissue disorder associated with TAAD. Although vascular smooth muscle cell metabolic dysfunction has emerged as a pathogenic driver of TAAD, surgical repair remains the mainstay of treatment. This study aimed to investigate the role of the hexosamine biosynthetic pathway (HBP) in sporadic and genetic TAAD pathophysiology. METHODS: Hexosamine biosynthetic pathway activation was analysed in aortas from an MFS mouse model, a β-aminopropionitrile-induced non-genetic TAAD model, and patients with sporadic TAAD using transcriptomic and metabolomic approaches. Aortic dilatation was monitored by ultrasound imaging. Pharmacological inhibition of HBP and integrated stress response (ISR) was performed to assess their therapeutic potential. RESULTS: Hexosamine biosynthetic pathway was up-regulated in both an MFS mouse model and β-aminopropionitrile-induced TAAD, as well as in aortic samples from MFS and sporadic TAAD patients. Enhanced HBP activity contributed to aortic dilatation and medial degeneration via vascular smooth muscle cell dysfunction and ISR activation. Inhibition of HBP or ISR reversed these effects in the MFS model. CONCLUSIONS: The HBP-ISR axis drives medial degeneration in TAAD. These findings identify HBP and ISR as a potential target in TAAD of both genetic and non-genetic origin.