Abstract Body: A reduction in aortic compliance serves as an early indicator of incipient vascular disease. While extracellular matrix modifications, such as elastin fragmentation, are the major mediators of aortic stiffness, the mechanisms that underlie these phenotypes remain to be elucidated. O-GlcNAc, the attachment of β-N-acetylglucosamine to serine and threonine residues of proteins, is a highly dynamic and widespread post-translational modification. This modification plays a pivotal role in modulating the function, activity, localization, and stability of target proteins across nuclear, cytoplasmic, and mitochondrial compartments. Primarily involved in intracellular signaling and transcriptional regulation, O-GlcNAc responds to nutrient availability and cell stress. However, chronic O-GlcNAc is consistently linked to vascular impairments. Indeed, our preliminary data has demonstrated that O-GlcNAc is elevated in aorta of Fisher-334 female at 16 months of age (16MO) than 3MO and pharmacological induction of O-GlcNAc (TMG 100 uM 24h) in 3MO rats can cause aortic stiffness via increased elastase activity and elastin fragmentation. However, how this inherently intracellular cellular signaling could impact aorta remodeling is unknown. CD47 (Cluster of Differentiation 47), also known as integrin-associated protein, is a transmembrane protein that acts as a “do not eat me” signal to immune cells. RNAseq data from our lab suggested that TMG (1 uM, 24 h) increased CD47 expression in vascular smooth muscle cells (n =3, p=0.08). Therefore, we hypothesized that CD47 could be an important downstream mediator of O-GlcNAc-induced aortic stiffness. Our findings revealed that CD47 inhibitors, [(RRx 10 uM) and SEN 177 (100 nM)] effectively mitigated the aortic stiffness and elastase activity (Ctrl 2302±38; TMG 4058±328; RRx 1776±121; Sen177 3032±50 A.U.) induced by TMG, suggesting that CD47 is a novel mechanism of O-GlcNAc-induced aortic stiffness. As aging is a major risk factor for aortic stiffness, we also revealed that CD47 was increased in the aorta of 16MO rats compared to 3MO controls (0.1±0.03 vs. 0.3±0.06). Potential ligands for CD47 include thrombospondin-1 (TSP-1) and signal-regulatory protein alpha (SIRPα). We observed that in 16MO rats, circulating SIRPα is increased, but not TSP1, suggesting a receptor-ligand interaction that is applicable in aging. Overall, these data reveal a previously unidentified and significant role for CD47 in O-GlcNAc-induced aortic stiffness.