TRAF5 deficiency accelerates atherogenesis in mice by increasing inflammatory cell recruitment and foam cell formation.
BACKGROUND
Tumor necrosis factor receptor-associated factors (TRAFs) are cytoplasmic adaptor proteins for the TNF/interleukin-1/Toll-like receptor superfamily. Ligands of this family comprise multiple important cytokines such as TNFα, CD40L, and interleukin-1β that promote chronic inflammatory diseases such as atherosclerosis. We recently reported overexpression of TRAF5 in murine and human atheromata and that TRAF5 promotes inflammatory functions of cultured endothelial cells and macrophages.


OBJECTIVE
This study tested the hypothesis that TRAF5 modulates atherogenesis in vivo.


RESULTS
Surprisingly, TRAF5(-/-)/LDLR(-/-) mice consuming a high-cholesterol diet for 18 weeks developed significantly larger atherosclerotic lesions than did TRAF5(+/+)/LDLR(-/-) controls. Plaques of TRAF5-deficient animals contained more lipids and macrophages, whereas smooth muscle cells and collagen remained unchanged. Deficiency of TRAF5 in endothelial cells or in leukocytes enhanced adhesion of inflammatory cells to the endothelium in dynamic adhesion assays in vitro and in murine vessels imaged by intravital microscopy in vivo. TRAF5 deficiency also increased expression of adhesion molecules and chemokines and potentiated macrophage lipid uptake and foam cell formation. These findings coincided with increased activation of JNK and appeared to be independent of TRAF2. Finally, patients with stable or acute coronary heart disease had significantly lower amounts of TRAF5 mRNA in blood compared with healthy controls.


CONCLUSIONS
Unexpectedly, TRAF5 deficiency accelerates atherogenesis in mice, an effect likely mediated by increased inflammatory cell recruitment to the vessel wall and enhanced foam cell formation.
Missiou
Anna
A
Department of Cardiology, University of Freiburg, Germany.
Rudolf
Philipp
P
Stachon
Peter
P
Wolf
Dennis
D
Varo
Nerea
N
Aichele
Peter
P
Colberg
Christian
C
Hoppe
Natalie
N
Ernst
Sandra
S
Münkel
Christian
C
Walter
Carina
C
Sommer
Benjamin
B
Hilgendorf
Ingo
I
Nakano
Hiroyasu
H
Bode
Christoph
C
Zirlik
Andreas
A
D000368:Aged; D000818:Animals; D050197:Atherosclerosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002454:Cell Differentiation / Q000235:genetics; D002465:Cell Movement / Q000235:genetics; D002478:Cells, Cultured; D003327:Coronary Disease / Q000276:immunology / Q000378:metabolism; D005260:Female; D005487:Foam Cells / Q000378:metabolism / Q000473:pathology*; D005500:Follow-Up Studies; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008264:Macrophages / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008875:Middle Aged; D011247:Pregnancy; D048015:TNF Receptor-Associated Factor 5 / Q000172:deficiency* / Q000235:genetics
D048015:TNF Receptor-Associated Factor 5