Abstract 13025: Methotrexate Carried in Lipid Core Nanoparticles Prevented the Dilation and Dissection of the Aortic Arch in Mice With Marfan Syndrome by Increasing the Bioavailability of Intracellular Adenosine

Abstract

Introduction: Mutations in the fibrillin-1 gene result in aneurysms and rupture of the aorta, the main cause of mortality in patients with Marfan syndrome (MFS). Inflammation is associated with dissection and rupture of the aorta. We showed that methotrexate (MTX) carried in lipid core nanoparticles (LDE) had powerful anti-inflammatory effects on atherosclerotic lesions and myocardial infarction. Hypothesis: To investigate whether treatment with LDE-MTX can prevent the development of aortic arch lesions in MFS. Methods: mgΔloxPneo MFS murine model and wild-type mice were allocated in 3 groups of treatment: LDE only; MTX in commercial formulation; LDE-MTX. The treatment occurred weekly at a dose of 1mg/kg ip, between the 3rd and 6th month of life, period in which both dilation and dissection of the aortic arch are observed. After 12 weeks, animals were submitted to analysis of the aortic arch. Results: Compared to LDE and MTX groups, LDE-MTX treatment showed smaller lumen area of ascending and descending aorta and aortic arch segments in MFS mice. LDE-MTX also decreased collagen volume fraction and the amount of aortic dissections, but did not affect the thickness of the vessel wall and the number of elastic fiber ruptures. Protein expression of the inflammatory markers CD68 (macrophages), CD3 (lymphocytes) and tumor necrosis factor alpha, of the apoptotic marker caspase 3 and of type 1 collagen were lower in LDE-MTX group when compared to LDE and MTX. Moreover, treatment with LDE-MTX reduced TGF-β, ERK and SMAD3 protein expression. Of note, CD68 and CD3 protein expression were positively correlated with the lumen area of the aortic arch (r2=0.36; p<0.001), indicating the importance of inflammation for the aortic dilation. The increase in bioavailability of intracellular adenosine was suggested by higher expression of A2a adenosine receptor and lower levels of adenosine deaminase in the aortic arch. Conclusions: Possibly by increasing the bioavailability of intracellular adenosine, LDE-MTX treatment had the ability to reduce the processes of inflammation, apoptosis and fibrosis that are consequent to fibrillin-1 mutation. By these means, LDE-MTX may conceivably prevent the development of the dilation and dissection in the aortic arch, the hallmarks of MFS.