Anti-TGFβ (Transforming Growth Factor β) Therapy With Betaglycan-Derived P144 Peptide Gene Delivery Prevents the Formation of Aortic Aneurysm in a Mouse Model of Marfan Syndrome

Objective: We investigated the effect of a potent TGF beta (transforming growth factor beta) inhibitor peptide (P144) from the betaglycan/TGF beta receptor III on aortic aneurysm development in a Marfan syndrome mouse model. Approach and Results: We used a chimeric gene encoding the P144 peptide linked to apolipoprotein A-I via a flexible linker expressed by a hepatotropic adeno-associated vector. Two experimental approaches were performed: (1) a preventive treatment where the vector was injected before the onset of the aortic aneurysm (aged 4 weeks) and followed-up for 4 and 20 weeks and (2) a palliative treatment where the vector was injected once the aneurysm was formed (8 weeks old) and followed-up for 16 weeks. We evaluated the aortic root diameter by echocardiography, the aortic wall architecture and TGF beta signaling downstream effector expression of pSMAD2 and pERK1/2 by immunohistomorphometry, and Tgf beta 1 and Tgf beta 2 mRNA expression levels by real-time polymerase chain reaction. Marfan syndrome mice subjected to the preventive approach showed no aortic dilation in contrast to untreated Marfan syndrome mice, which at the same end point age already presented the aneurysm. In contrast, the palliative treatment with P144 did not halt aneurysm progression. In all cases, P144 improved elastic fiber morphology and normalized pERK1/2-mediated TGF beta signaling. Unlike the palliative treatment, the preventive treatment reduced Tgf beta 1 and Tgf beta 2 mRNA levels. Conclusions: P144 prevents the onset of aortic aneurysm but not its progression. Results indicate the importance of reducing the excess of active TGF beta signaling during the early stages of aortic disease progression.