P346	The CD40-TRAF6 axis is the key-regulator of the CD40-CD40L system in neointima formation.
1M.Donners, 1L.Beckers, 2R.Noelle, 1M.Daemen, 1E.Lutgens
1Dept. of Pathology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, NL; 2Dept. of Medical Microbiology and Immunology, Dartmouth Medical School, Hanover, US.

In this study, we investigated which CD40 signaling intermediates are responsible for the beneficial effects of CD40(L) inhibition in vascular disease. We focused on the CD40 adaptor proteins: the TNF Receptor Association Factors (TRAFs). Male CD40-/- mice containing a human CD40 transgene with(out) mutations at the TRAF2,3 (CD40-T2,3), TRAF6 (CD40-T6) or TRAF2,3,6 (CD40-T2,3,6) binding site on CD40 were generated and fed a normal diet. The right carotid artery was ligated and analyzed after 4 weeks (n=85). Compared to wildtype mice, CD40-/- showed a 75% decrease in neointima formation, a decreased intima/media ratio, lumen area compared to wt mice (table, * p<0.05). In CD40-T6 and CD40-T2,3,6 mice neointimal area and intima-media ratio was significantly decreased compared to CD40-TRAFwt, indicating that the effects on neointima formation are TRAF6-dependent. No significant differences were observed in CD40-T2,3 mice. Cultured bone marrow derived macrophages from CD40-TRAF mice were stimulated for 0, 3 or 8 hrs with LPS (10ng/ml, n=2-4 per group). Real time PCR data showed a decrease in IL-6 and MCP-5 mRNA levels in CD40-T6 and CD40-TRAF2,3,6 macrophages when compared to CD40-TRAFwt macrophages. ELISA analysis showed a decrease in TNFα produced by CD40-T6 macrophages. CD40-TRAF in neointima formation and vascular remodeling   Neointimal area (μm2) Intima/media ratio Lumen area (μm2) Total vessel area (μm2) CD40-TRAFwt (n=14) 26546 ± 3795 0.83 ± 0.09 18035 ± 2473 69495 ± 8807 CD40-T2/3 (n=10) 18204 ± 4906 0.64 ± 0.14 16616 ± 1858 59230 ± 9026 CD40-T6 (n=7) 8345 ± 1936* 0.26 ± 0.06* 14199 ± 1167 45512 ± 3357 CD40-T2,3,6 (n=14) 12540 ± 2190* 0.38 ± 0.05* 15524 ± 1193 49546 ± 3852 Wt (n=10) 42978 ± 9260 1.21 ± 0.19 24085 ± 3657 99719 ± 15924 CD40-/- (n=11) 10459 ± 2679* 0.39 ± 0.10* 14389 ± 1048* 45514 ± 3394* CD40L-/- (n=10) 28041 ± 10318 0.86 ± 0.31 16438 ± 2490 60080 ± 14481 These results indicate a crucial role for CD40-TRAF6 interactions in the induction of proinflammatory cytokines in macrophages and the development of neointima.

Copyright © 2005 S. Karger AG, Basel. Any further use of this abstract requires written permission from the publisher.