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2010) Activation of indoleamine 2,3-dioxygenase-induced tryptophan degradation in advanced atherosclerotic plaques: Tampere Vascular Study, Annals of Medicine, 42:1, 55-63To link to this article: http://dx. AbstractObjective. We aimed to characterize the expression of indoleamine 2,3-dioxygenase (IDO) or IDO-induced tryptophan degradation-dependent pathways, which may lead to suppression of T cells and possible protection against atherosclerosis. Methods and results. Expression of IDO and IDO-related pathway components was analyzed in advanced human atherosclerotic plaques (n ϭ 24) and in non-atherosclerotic arteries (n ϭ 6). Up-regulation of IDO and genes related to the IDO pathway was found to be pronounced in atherosclerotic plaques. Immunohistochemistry demonstrated IDO protein in the atheromatous core and co-distribution with monocyte-macrophages (CD68-positive cells). In gene-set enrichment analysis, the IDO pathway revealed a signifi cant (false discovery rate (FDR) ϭ 0.07) regulatory T cell, fork-head box protein 3 (FoxP3)-initiated CD28-cytotoxic T lymphocyte-associated antigen 4 (CTLA-4)-inducible T cell co-stimulator (ICOS)driven pathway leading to activation of IDO expression in antigen-presenting cells (APCs). Expression of these IDO pathway genes varied between 2.1-and 16.8-fold as compared to control tissues (P Ͻ 0.05 for all). Conclusions. IDO and the IDO-related pathway are important mediators of the immunoinfl ammatory responses in advanced atherosclerosis offering new viable therapeutic targets for the development of antiatherogenic immunosuppressive therapies.

Cardiovascular diseases due to atherosclerosis are the leading cause of death globally. We aimed to investigate the potentially altered gene and pathway expression in advanced peripheral atherosclerotic plaques in comparison to healthy control arteries. Gene expression analysis was performed (Illumina HumanHT-12 version 3 Expression BeadChip) for 68 advanced atherosclerotic plaques (15 aortic, 29 carotid and 24 femoral plaques) and 28 controls (left internal thoracic artery (LITA)) from Tampere Vascular Study. Dysregulation of individual genes was compared to healthy controls and between plaques from different arterial beds and Ingenuity pathway analysis was conducted on genes with a fold change (FC) > ±1.5 and false discovery rate (FDR) < 0.05. 787 genes were significantly differentially expressed in atherosclerotic plaques. The most up-regulated genes were osteopontin and multiple MMPs, and the most down-regulated were cell death-inducing DFFA-like effector C and A (CIDEC, CIDEA) and apolipoprotein D (FC > 20). 156 pathways were differentially expressed in atherosclerotic plaques, mostly inflammation-related, especially related with leukocyte trafficking and signaling. In artery specific plaque analysis 50.4% of canonical pathways and 41.2% GO terms differentially expressed were in common for all three arterial beds. Our results confirm the inflammatory nature of advanced atherosclerosis and show novel pathway differences between different arterial beds.