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


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.
From the Department of Medical Biochemistry (G.M., S.H., A.v.B., A.F.G., N.B., A.A.J.H., C.J.M.d.V., V.d.W.), Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory (M.H., J.D.v.B.), and Department of Cell Biology and Histology (J.S.), Academic Medical Center, University of Amsterdam, The Netherlands.
Goran
G
Marinkovic
Stijntje
S
Hibender
Mark
M
Hoogenboezem
Amber
A
van Broekhoven
Arginell F
AF
Girigorie
Natascha
N
Bleeker
Anouk A J
AA
Hamers
Jan
J
Stap
Jaap D
JD
van Buul
Carlie J M
CJ
de Vries
Vivian
V
de Waard
D000804:Angiotensin II; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D001014:Aortic Aneurysm / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D001019:Aortic Rupture / Q000201:enzymology / Q000276:immunology / Q000517:prevention & control; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics; D001379:Azathioprine / Q000494:pharmacology*; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D004195:Disease Models, Animal; D018450:Disease Progression; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology; D004789:Enzyme Activation; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D018836:Inflammation Mediators / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015122:Mercaptopurine / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology; D009479:Neuropeptides / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D001057:Apolipoproteins E; D007166:Immunosuppressive Agents; D018836:Inflammation Mediators; D009479:Neuropeptides; D047428:Protein Kinase Inhibitors; C107953:RAC1 protein, human; C484602:Rac1 protein, mouse; D000804:Angiotensin II; D015122:Mercaptopurine; D048031:JNK Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein; D001379:Azathioprine
aneurysm; endothelium; inflammation