Immunosuppressive drug azathioprine reduces aneurysm progression through inhibition of Rac1 and c-Jun-terminal-N-kinase in endothelial cells

Arterioscler Thromb Vasc Biol. 2013 Oct;33(10):2380-8. doi: 10.1161/ATVBAHA.113.301394. Epub 2013 Aug 15.


Objective: In aortic aneurysms the arterial vessel wall is dilated because of destruction of its integrity, which may lead to lethal vessel rupture. Chronic infiltration of inflammatory cells into the vessel wall is fundamental to aneurysm pathology. We aim to limit aneurysm growth by inhibition of inflammation and reducing endothelial cell (EC) activation with immunosuppressive drug azathioprine (Aza).

Approach and results: Aza and its metabolite 6-mercaptopurine have anti-inflammatory effects on leukocytes. We here demonstrate that treatment of ECs with 6-mercaptopurine inhibits cell activation as illustrated by reduced expression of interleukin-12, CCL5, CCL2, and vascular cell adhesion molecule-1 and inhibition of monocyte-EC adhesion. The underlying mechanism of 6-mercaptopurine involves suppression of GTPase Rac1 activation, resulting in reduced phosphorylation of c-Jun-terminal-N-kinase and c-Jun. Subsequently, the effect of Aza was investigated in aneurysm formation in the angiotensin II aneurysm mouse model in apolipoprotein E-deficient mice. We demonstrated that Aza decreases de novo aortic aneurysm formation from an average aneurysm severity score of 2.1 (control group) to 0.6 (Aza group), and that Aza effectively delays aorta pathology in a progression experiment, resulting in a reduced severity score from 2.8 to 1.7 in Aza-treated mice. In line with the in vitro observations, Aza-treated mice showed less c-Jun-terminal-N-kinase activation in ECs and reduced leukocyte influx in the aortic wall.

Conclusions: The immunosuppressive drug Aza has an anti-inflammatory effect and in ECs inhibits Rac1 and c-Jun-terminal-N-kinase activation, which may explain the protective effect of Aza in aneurysm development and, most importantly for clinical implications, aneurysm severity.

Keywords: aneurysm; endothelium; inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II
  • Animals
  • Anti-Inflammatory Agents / pharmacology
  • Aortic Aneurysm / chemically induced
  • Aortic Aneurysm / enzymology
  • Aortic Aneurysm / genetics
  • Aortic Aneurysm / immunology
  • Aortic Aneurysm / pathology
  • Aortic Aneurysm / prevention & control*
  • Aortic Rupture / enzymology
  • Aortic Rupture / immunology
  • Aortic Rupture / prevention & control
  • Apolipoproteins E / deficiency
  • Apolipoproteins E / genetics
  • Azathioprine / pharmacology*
  • Cell Line, Tumor
  • Coculture Techniques
  • Disease Models, Animal
  • Disease Progression
  • Endothelial Cells / drug effects*
  • Endothelial Cells / enzymology
  • Endothelial Cells / immunology
  • Enzyme Activation
  • Human Umbilical Vein Endothelial Cells / drug effects
  • Human Umbilical Vein Endothelial Cells / enzymology
  • Humans
  • Immunosuppressive Agents / pharmacology*
  • Inflammation Mediators / metabolism
  • JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors*
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Mercaptopurine / metabolism
  • Mice
  • Mice, Knockout
  • Monocytes / drug effects
  • Monocytes / enzymology
  • Monocytes / immunology
  • Neuropeptides / antagonists & inhibitors*
  • Neuropeptides / metabolism
  • Phosphorylation
  • Protein Kinase Inhibitors / pharmacology*
  • Signal Transduction / drug effects
  • rac1 GTP-Binding Protein / antagonists & inhibitors*
  • rac1 GTP-Binding Protein / metabolism


  • Anti-Inflammatory Agents
  • Apolipoproteins E
  • Immunosuppressive Agents
  • Inflammation Mediators
  • Neuropeptides
  • Protein Kinase Inhibitors
  • RAC1 protein, human
  • Rac1 protein, mouse
  • Angiotensin II
  • Mercaptopurine
  • JNK Mitogen-Activated Protein Kinases
  • rac1 GTP-Binding Protein
  • Azathioprine