Tryptophan-Derived 3-Hydroxyanthranilic Acid Contributes to Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in Mice In Vivo.
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ABSTRACT: Abnormal amino acid metabolism is associated with vascular disease. However, the causative link between dysregulated tryptophan metabolism and abdominal aortic aneurysm (AAA) is unknown.Indoleamine 2,3-dioxygenase (IDO) is the first and rate-limiting enzyme in the kynurenine pathway of tryptophan metabolism. Mice with deficiencies in both apolipoprotein e (Apoe) and IDO (Apoe-/-/IDO-/-) were generated by cross-breeding IDO-/- mice with Apoe-/- mice.The acute infusion of angiotensin II markedly increased the incidence of AAA in Apoe-/- mice, but not in Apoe-/-/IDO-/- mice, which presented decreased elastic lamina degradation and aortic expansion. These features were not altered by the reconstitution of bone marrow cells from IDO+/+ mice. Moreover, angiotensin II infusion instigated interferon-?, which induced the expression of IDO and kynureninase and increased 3-hydroxyanthranilic acid (3-HAA) levels in the plasma and aortas of Apoe-/- mice, but not in IDO-/- mice. Both IDO and kynureninase controlled the production of 3-HAA in vascular smooth muscle cells. 3-HAA upregulated matrix metallopeptidase 2 via transcription factor nuclear factor-?B. Furthermore, kynureninase knockdown in mice restrained 3-HAA, matrix metallopeptidase 2, and resultant AAA formation by angiotensin II infusion. Intraperitoneal injections of 3-HAA into Apoe-/- and Apoe-/-/IDO-/- mice for 6 weeks increased the expression and activity of matrix metallopeptidase 2 in aortas without affecting metabolic parameters. Finally, human AAA samples had stronger staining with the antibodies against 3-HAA, IDO, and kynureninase than those in adjacent nonaneurysmal aortic sections of human AAA samples.These data define a previously undescribed causative role for 3-HAA, which is a product of tryptophan metabolism, in AAA formation. Furthermore, these findings suggest that 3-HAA reduction may be a new target for treating cardiovascular diseases.
SUBMITTER: Wang Q
PROVIDER: S-EPMC5716872 | biostudies-literature | 2017 Dec
REPOSITORIES: biostudies-literature
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