Endothelial Elavl1 Is Required for CD8 T-Cell Persistence in Atherosclerosis.

Abstract

<h4>Background</h4>Atherosclerotic plaques form through lipid and immune cell accumulation beneath the arterial endothelium. CD8 T cells are abundant in lesions, and their activation correlates with cardiovascular disease severity. Although endothelial cells recruit CD8 T cells to low and disturbed flow regions, whether they regulate CD8 activation and persistence is unknown. These interactions may be mediated by posttranscriptional control of mRNA translation.<h4>Methods</h4>We used ribosomal profiling in <i>Cdh5(PAC</i>); <i>RiboTRAP</i> mice to assess posttranscriptional regulation in atherosclerotic endothelium in a partial carotid ligation model. We then used <i>CreERT2; Elavl ff; RiboTRAP</i> (endothelial cell-knockout) mice to examine the impact of endothelial Elavl1 on gene expression programs and immune cell activity.<h4>Results</h4>Elavl1 motifs were enriched near alternative splicing events, and within 5' untranslated regions of transcripts with altered ribosomal association in atherosclerosis. Elavl1 suppressed gene expression programs occurring in atherogenic endothelium, as deletion enhanced these responses and reduced CD8 T-cell accumulation (≈70%) at plaques without affecting recruitment, consistent with impaired persistence. In vitro, Elavl1-deficient endothelial cells suppressed antigen-dependent CD8 T-cell persistence, even in the presence of wild-type myeloid antigen-presenting cells and cognate antigen.<h4>Conclusions</h4>Endothelial Elavl1 suppression enables endothelial cells to function as local immune checkpoint-like regulators of CD8 T-cell persistence in atherosclerosis. Thus, endothelial Elavl1 is a key regulator of adaptive immunity.