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Objective: We investigated the effect of a potent TGFβ (transforming growth factor β) inhibitor peptide (P144) from the betaglycan/TGFβ 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 TGFβ signaling downstream effector expression of pSMAD2 and pERK1/2 by immunohistomorphometry, and Tgfβ1 and Tgfβ2 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 TGFβ signaling. Unlike the palliative treatment, the preventive treatment reduced Tgfβ1 and Tgfβ2 mRNA levels. Conclusions: P144 prevents the onset of aortic aneurysm but not its progression. Results indicate the importance of reducing the excess of active TGFβ signaling during the early stages of aortic disease progression.

The pathogenesis and progression of aortic aneurysm in Marfan syndrome (MFS) involves dysregulated TGF-β and nitric oxide signaling, altered hemodynamics, and biomechanical forces. Increasing evidence indicates that redox stress participates in MFS aortopathy development, though its contribution is not well established. We reported elevated reactive oxygen species (ROS) formation and NADPH oxidase NOX4 upregulation in MFS mice and in patient aortic samples. Here we address the contribution of xanthine dehydrogenase (XDH) which catabolizes purines into uric acid plus ROS. XDH mRNA and protein expression levels are increased in the aorta of young but not older MFS mice (Fbn1C1041G/+). The protein and enzymatic activity of the oxidase form (XO) is increased with respect to the dehydrogenase. In patients, XO protein levels were increased in the dilated and the adjacent non-dilated zone of aortic aneurysm. The palliative administration of the XDH inhibitor allopurinol attenuated the progression of the aortic root aneurysm in MFS mice. Allopurinol was also protective when administrated before the appearance of aneurysm onset. MFS-induced elastic fiber fragmentation, fibrotic remodeling, nuclear translocation of pNRF2, and increased 3-nitrotyrosine levels in the aortic tunica media, as well as endothelial dysfunction, were all prevented by allopurinol. Mechanistically, allopurinol mediates these effects by inhibiting H2O2 overproduction, with no apparent relevance for uric acid, whose plasma levels remained constant with age. This study strengthens the concept that redox stress is an important determinant of aortic aneurysm formation and progression in MFS and supports a clinical trial for allopurinol in the pharmacological treatment of MFS aortopathy.

Williams–Beuren syndrome (WBS) is a rare disorder caused by a recurrent microdeletion with hallmarks of cardiovascular manifestations, mainly supra-valvular aortic stenosis (SVAS). Unfortunately, there is currently no efficient treatment. We investigated the effect of chronic oral treatment with curcumin and verapamil on the cardiovascular phenotype of a murine model of WBS harbouring a similar deletion, CD (complete deletion) mice. We analysed systolic blood pressure in vivo and the histopathology of the ascending aorta and the left ventricular myocardium to determine the effects of treatments and their underlying mechanism. Molecular analysis showed significantly upregulated xanthine oxidoreductase (XOR) expression in the aorta and left ventricular myocardium of CD mice. This overexpression is concomitant with increased levels of nitrated proteins as a result of byproduct-mediated oxidative stress damage, indicating that XOR-generated oxidative stress impacts the pathophysiology of cardiovascular manifestations in WBS. Only the combined therapy of curcumin and verapamil resulted in a significant improvement of cardiovascular parameters via activation of the nuclear factor erythroid 2 (NRF2) and reduction of XOR and nitrated protein levels. Our data suggested that the inhibition of XOR and oxidative stress damage could help prevent the severe cardiovascular injuries of this disorder.

Redox stress is involved in the aortic aneurysm pathogenesis in Marfan syndrome (MFS). We recently reported that allopurinol, a xanthine oxidoreductase inhibitor, blocked aortopathy in a MFS mouse model acting as an antioxidant without altering uric acid (UA) plasma levels. Hyperuricaemia is ambiguously associated with cardiovascular injuries as UA, having antioxidant or pro-oxidant properties depending on the concentration and accumulation site. We aimed to evaluate whether hyperuricaemia causes harm or relief in MFS aortopathy pathogenesis. Two-month-old male wild-type (WT) and MFS mice (Fbn1C1041G/+) were injected intraperitoneally for several weeks with potassium oxonate (PO), an inhibitor of uricase (an enzyme that catabolises UA to allantoin). Plasma UA and allantoin levels were measured via several techniques, aortic root diameter and cardiac parameters by ultrasonography, aortic wall structure by histopathology, and pNRF2 and 3-NT levels by immunofluorescence. PO induced a significant increase in UA in blood plasma both in WT and MFS mice, reaching a peak at three and four months of age but decaying at six months. Hyperuricaemic MFS mice showed no change in the characteristic aortic aneurysm progression or aortic wall disarray evidenced by large elastic laminae ruptures. There were no changes in cardiac parameters or the redox stress-induced nuclear translocation of pNRF2 in the aortic tunica media. Altogether, the results suggest that hyperuricaemia interferes neither with aortopathy nor cardiopathy in MFS mice.