Abstract 544: Nrp-1+Foxp3-CD4 T Cells Are a Novel Subset of T Lymphocytes that Are Induced in Aorta During Development of Atherosclerosis

Neuropilin 1 (Nrp-1) is a type I transmembrane protein that plays an important role in axonal guidance and neuronal development as well as vascular sprouting and angiogenesis through the interaction with Semaphorin-3A and vascular endothelial growth factor (VEGF), respectively. Recently, Nrp-1 was found on a subset of thymus-derived regulatory T cells (Treg) that migrated into VEGF producing tumors. Moreover, Nrp-1+ CD4 T cells were protective in a murine experimental model of autoimmune encephalomyelitis, suggesting that these cells may have a participating role in other inflammatory diseases. Since atherosclerosis is a chronic inflammatory disease where T cells, macrophages, and other immune cells orchestrate disease progression, we hypothesized that Nrp-1+ CD4 T cells are induced in the aorta during atherosclerosis development and play a role during disease progression. We fed ApoE-/- mice a western diet for 15 weeks and found a 2-fold increase in Nrp-1+Foxp3- CD4 T cells in the spleens, peri-aortic lymph nodes and aortas of western diet fed mice compared to chow-fed mice. In addition, these Nrp-1+Foxp3- CD4 T cells expressed higher levels of the memory marker CD44 and produced more IFNγ when compared to Nrp-1- CD4 T cells, suggesting that these cells are more activated. Treatment of CD4 T cells with oxidized LDL (OxLDL), but not minimally modified LDL (mmLDL), oxidized cholesterol ester (OxCE) or oxidized phospholipids (POVPC), caused upregulation of Nrp-1 on CD4 T cells. Using a transwell migration assay, we found that Nrp1+ CD4 T cells had a 2-fold higher migration index towards VEGF165, a splice variant of VEGF, than did Nrp1- CD4 T cells; thus this migration was dependent on Nrp-1 expression. Similarly, CD4 T cells from ApoE-/- mice fed a western diet, which expressed more Nrp-1, had a higher migration index towards VEGF165 compared to cells from chow controls. In conclusion, we have identified a novel subset of Nrp-1+CD4+ T lymphocytes that is increased during atherosclerosis development, and is induced by OxLDL. Our data suggest that Nrp-1 may play a role in the migration of CD4 T cells to the aorta during atherosclerosis development.