Abrogated transforming growth factor beta receptor II (TGFRII) signalling in dendritic cells promotes immune reactivity of T cells resulting in enhanced atherosclerosis

The importance of transforming growth factor beta (TGF) as an immune regulatory cytokine in atherosclerosis has been established. However, the role of TGF signalling in dendritic cells (DCs) and in DC-mediated T cell proliferation and differentiation in atherosclerosis is unknown. Here, we investigated the effect of disrupted TGF signalling in DCs on atherosclerosis by using mice carrying a transgene resulting in functional inactivation of TGF receptor II (TGFRII) signalling in CD11c cells (Apoe(/)CD11cDNR). Apoe(/)CD11cDNR mice exhibited an over two-fold increase in the plaque area compared with Apoe(/) mice. Plaques of Apoe(/)CD11cDNR mice showed an increase in CD45 leucocyte content, and specifically in CD3, CD4 and CD8 cells, whereas macrophage content was not affected. In lymphoid organs, Apoe(/)CD11cDNR mice had equal amounts of CD11c cells, and CD11cCD8 and CD11cCD8 subsets, but showed a subtle shift in the CD11cCD8 population towards the more inflammatory CD11cCD8CD4 DC subset. In addition, the number of plasmacytoid-DCs decreased. Maturation markers such as MHCII, CD86 and CD40 on CD11c(hi) cells did not change, but the CD11cDNR DCs produced more TNF and IL-12. CD11c cells from CD11cDNR mice strongly induced T-cell proliferation and activation, resulting in increased amounts of effector T cells producing high amounts of Th1 (IFN-), Th2 (IL-4, IL-10), Th17 (IL-17), and Treg (IL-10) cytokines. Here, we show that loss of TGFRII signalling in CD11c cells induces subtle changes in DC subsets, which provoke uncontrolled T cell activation and maturation. This results in increased atherosclerosis and an inflammatory plaque phenotype during hypercholesterolaemia.