The T cell-DC CD40L-CD40 axis, but not platelet CD40L, drives atherosclerosis

Atherosclerosis, the underlying vascular cause of cardiovascular disease, has a strong inflammatory component. The co-stimulatory CD40-CD40 ligand (CD40L) signaling axis is a pivotal regulator of immune responses in atherosclerosis. However, therapeutic long-term inhibition of CD40L will severely compromise the immune system making it a non-viable treatment option. To circumvent this issue, cell-specific inhibition may present a better approach to target the CD40-CD40L axis. Therefore, we generated T cell and platelet-specific knockout mice for CD40L and apolipoprotein E, which were aged for 28 weeks to study their effects on immune status and atherosclerosis. Here, we show that T cell specific deficiency in CD40L signaling reduced plaque progression through hampered Th1 polarization as well as reduced antigen-dependent proliferation and oxLDL IgM production. DC-specific CD40 deficient mice displayed a similar phenotype. Platelet-specific CD40L deficiency, however, failed to decrease atherosclerosis, but ameliorated atherothrombosis. Together, our results illuminate the divergent cell-specific mechanisms of CD40-CD40L signaling in atherosclerosis, which may lead to advances in targeted therapies. Overall design: Comparison of gene expression in CD4+ T cells from wild-type mice and CD4+ T cell-specific CD40L-deficient mice