Thoracic aortic aneurysms (TAAs) pose a significant health burden due to their asymptomatic progression, often culminating in life-threatening aortic rupture, and due to the lack of effective pharmacological treatments. Risk factors include elevated hemodynamic stress on the ascending aorta, frequently associated with hypertension and hereditary genetic mutations. Among the hereditary causes, Marfan syndrome is the most prevalent, characterized as a connective tissue disorder driven by FBN1 mutations that lead to life-threatening thoracic aortic ruptures. Similarly, mutations affecting the TGF-β pathway underlie Loeys–Dietz syndrome, while mutations in genes encoding extracellular or contractile apparatus proteins, such as ACTA2, are linked to non-syndromic familial TAA. Despite differences in genetic origin, these hereditary conditions share central pathophysiological features, including aortic medial degeneration, smooth muscle cell dysfunction, and extracellular remodeling, which collectively weaken the aortic wall. Recent evidence highlights mitochondrial dysfunction as a crucial contributor to aneurysm formation in Marfan syndrome. Disruption of the extracellular matrix–mitochondrial homeostasis axis exacerbates aortic wall remodeling, further promoting aneurysm development. Beyond its structural role in maintaining vascular integrity, the ECM plays a pivotal role in supporting mitochondrial function. This intricate relationship between extracellular matrix integrity and mitochondrial homeostasis reveals a novel dimension of TAA pathophysiology, extending beyond established paradigms of extracellular matrix remodeling and smooth muscle cell dysfunction. This review summarizes mitochondrial dysfunction as a potential unifying mechanism in hereditary TAA and explores how understanding mitochondrial dysfunction, in conjunction with established mechanisms of TAA pathogenesis, opens new avenues for developing targeted treatments to address these life-threatening conditions. Mitochondrial boosters could represent a new clinical opportunity for patients with hereditary TAA.

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.

Thoracic aortic aneurysms are life-threatening vascular conditions linked to inherited disorders such as Marfan syndrome, Loeys–Dietz syndrome, vascular Ehlers–Danlos syndrome, and familial thoracic aortic aneurysms and dissections. While traditionally associated with the extracellular matrix and contractile defects in vascular smooth muscle cells, emerging evidence suggests the key role of mitochondrial dysfunction. Here, we show that the overexpression of ACTA2^R179H and TGFBR2^G357W in murine aortic VSMCs reduces Mitochondrial Transcription Factor A (Tfam) expression, decreases mitochondrial DNA (mtDNA) content, and impairs oxidative phosphorylation, shifting metabolism toward glycolysis. Notably, nicotinamide riboside, a NAD⁺ precursor, restores mitochondrial respiration, increases Tfam and mtDNA levels, and promotes a contractile phenotype by enhancing actin polymerization and reducing matrix metalloproteinase activity. These findings identify mitochondrial dysfunction as a shared feature in hereditary thoracic aortic aneurysm, not only in Marfan syndrome, but also in other genetic forms, and highlight mitochondrial boosters as a potential therapeutic strategy.

Thoracic aortic aneurysms (TAA) pose a significant health burden due to their asymptomatic progression, often culminating in life-threatening aortic rupture, and the lack of effective pharmacological treatments. Risk factors include elevated hemodynamic stress on the ascending aorta, frequently associated with hypertension and hereditary genetic mutations. Among hereditary causes, Marfan syndrome is the most prevalent, characterized as a connective tissue disorder driven by FBN1 mutations that lead to life-threatening thoracic aortic ruptures. Similarly, mutations affecting the TGF-β pathway underlie Loeys-Dietz syndrome, while mutations in genes encoding extracellular or contractile apparatus proteins, such as ACTA2, are linked to non-syndromic Familial-TAA. Despite differences in genetic origin, these hereditary conditions share central pathophysiological features, including aortic medial degeneration, smooth muscle cell dysfunction, and extracellular remodeling, which collectively weaken the aortic wall. Recent evidence highlights mitochondrial dysfunction as a crucial contributor to aneurysm formation in Marfan syndrome. Disruption of the extracellular matrix–mitochondrial homeostasis axis exacerbates aortic wall remodeling, further promoting aneurysm development. Beyond its structural role in maintaining vascular integrity, the ECM plays a pivotal role in supporting mitochondrial function. This intricate relationship between extracellular matrix integrity and mitochondrial homeostasis reveals a novel dimension of TAA pathophysiology, extending beyond established paradigms of extracellular matrix remodeling and smooth muscle cell dysfunction. Mitochondrial boosters might be a new clinical opportunity for hereditable TAA-patients. This review underscores mitochondrial dysfunction as potential unifying mechanism in hereditary TAA and explores its therapeutic implications. Understanding how mitochondrial dysfunction intersects with established mechanisms of TAA pathogenesis opens new avenues for developing targeted treatments to address these life-threatening conditions.

Thoracic Aortic Aneurysms are life-threatening vascular conditions linked to inherited disorders such as Marfan syndrome, Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome, and Familial Thoracic Aortic Aneurysms and Dissections. While traditionally associated with extracellular matrix and contractile defects in vascular smooth muscle cells, emerging evidence suggests a key role for mitochondrial dysfunction. Here, we show that overexpression of ACTA2R179H and TGFBR2G357W in murine aortic VSMCs reduces Mitochondrial Transcription Factor A (Tfam) expression, decreases mitochondrial DNA (mtDNA) content, and impairs oxidative phosphorylation, shifting metabolism toward glycolysis. Notably, nicotinamide riboside, a NAD+ precursor, restores mitochondrial respiration, increases Tfam and mtDNA levels, and promotes a contractile phenotype by enhancing actin polymerization and reducing matrix metalloproteinase activity. These findings identify mitochondrial dysfunction as a shared feature in hereditary Thoracic Aortic Aneurysm, not only in Marfan syndrome but also in other genetic forms and highlight mitochondrial boosters as a potential therapeutic strategies.