Vascular smooth muscle cells (vSMCs) exert a critical role in sensing and maintaining vascular integrity. These cells abundantly express the low-density lipoprotein receptor–related protein 1 (LRP1), a large endocytic signaling receptor that recognizes numerous ligands, including apolipoprotein E–rich lipoproteins, proteases, and protease-inhibitor complexes. We observed the spontaneous formation of aneurysms in the superior mesenteric artery (SMA) of both male and female mice in which LRP1 was genetically deleted in vSMCs (smLRP1–/– mice). Quantitative proteomics revealed elevated abundance of several proteins in smLRP1–/– mice that are known to be induced by angiotensin II–mediated (AngII-mediated) signaling, suggesting that this pathway was dysregulated. Administration of losartan, an AngII type I receptor antagonist, or an angiotensinogen antisense oligonucleotide to reduce plasma angiotensinogen concentrations restored the normal SMA phenotype in smLRP1–/– mice and prevented aneurysm formation. Additionally, using a vascular injury model, we noted excessive vascular remodeling and neointima formation in smLRP1–/– mice that was restored by losartan administration. Together, these findings reveal that LRP1 regulates vascular integrity and remodeling of the SMA by attenuating excessive AngII-mediated signaling.
Jackie M. Zhang, Dianaly T. Au, Hisashi Sawada, Michael K. Franklin, Jessica J. Moorleghen, Deborah A. Howatt, Pengjun Wang, Brittany O. Aicher, Brian Hampton, Mary Migliorini, Fenge Ni, Adam E. Mullick, Mashhood M. Wani, Areck A. Ucuzian, Hong S. Lu, Selen C. Muratoglu, Alan Daugherty, Dudley K. Strickland
Ultrasonography reveals that the SMA diameter expands in smLRP1–/– mice at an exceptional rate when compared with WT mice.