Tryptophan-Derived 3-Hydroxyanthranilic Acid Contributes to Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in Mice in Vivo

Qiongxin Wang, Ye Ding, Ping Song, Huaiping Zhu, Imoh Okon, Yang Nan Ding, Hou Zao Chen, De Pei Liu, Ming Hui Zou

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Background: Abnormal amino acid metabolism is associated with vascular disease. However, the causative link between dysregulated tryptophan metabolism and abdominal aortic aneurysm (AAA) is unknown. Methods: 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. Results: 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-γ, 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-κB. 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. Conclusions: 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.

Original languageEnglish
Pages (from-to)2271-2283
Number of pages13
Issue number23
StatePublished - Dec 5 2017


  • 3-hydroxyanthranilic acid
  • angiotensin II
  • aortic aneurysm, abdominal
  • indoleamine-pyrrole 2,3-dioxygenase
  • matrix metallopeptidases
  • tryptophan


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