Neuropilin-1 expression on CD4 T Cells is atherogenic and facilitates T Cell migration to the aorta in atherosclerosis

Neuropilin 1 (Nrp1) is a type I transmembrane protein that plays important roles in axonal guidance, neuronal development, and angiogenesis. Nrp1 also helps migrate thymus-derived regulatory T cells to vascular endothelial growth factor (VEGF)-producing tumors. However, little is known about the role of Nrp1 on CD4 T cells in atherosclerosis. In ApoE^-/- mice fed a Western diet for 15 wk, we found a 2-fold increase in Nrp1⁺Foxp3^- CD4 T cells in their spleens, periaortic lymph nodes, and aortas, compared with chow-fed mice. Nrp1⁺Foxp3^- CD4 T cells had higher proliferation potential, expressed higher levels of the memory marker CD44, and produced more IFN-γ when compared with Nrp12 CD4 T cells. Treatment of CD4 T cells with oxLDL increased Nrp1 expression. Furthermore, atherosclerosis-susceptible mice selectively deficient for Nrp1 expression on T cells developed less atherosclerosis than their Nrp1-sufficient counterparts. Mechanistically, we found that CD4 T cells that express Nrp1 have an increased capacity to migrate to the aorta and periaortic lymph nodes compared to Nrp12 T cells, suggesting that the expression of Nrp1 facilitates the recruitment of CD4 T cells into the aorta where they can be pathogenic. Thus, we have identified a novel role of Nrp1 on CD4 T cells in atherosclerosis. These results suggest that manipulation of Nrp1 expression on T cells can affect the outcome of atherosclerosis and lower disease incidence.