CircEif3c/miR-96-5p/PHF20L1/MEOX2 axis in perivascular preadipocyte exosomes mediates fibroblast dysfunction and vascular remodeling.

BACKGROUND: Diabetes mellitus is a major modifiable risk factor for atherosclerotic cardiovascular disease and pathological vascular remodeling. During chronic hyperglycemia, exosomes serve as essential nanocarriers that coordinate intercellular communication and induce structural and functional alterations in the vascular wall. Perivascular pre-adipocytes (PVPACs) exhibit high exosome secretory activity, while adventitial fibroblasts (AFs) are key effector cells in vascular remodeling. Despite their anatomical proximity, the potential bidirectional crosstalk between PVPAC-derived exosomes and AFs, and its roles for vascular remodeling, remains largely unexplored. METHODS: A co-culture system of PVPACs and AFs, along with a mouse model of perivascular proliferation, was established under sustained hyperglycemic conditions. Exosomes were isolated via sequential ultracentrifugation and characterized based on morphology, size distribution, and exosomal markers. High-throughput RNA microarray was employed to profile PVPAC-derived exosomal RNAs, with qRT-PCR and in situ hybridization used to validate the expression of circEif3c, miR-96-5p, PHF20L1, and MEOX2. Mechanistic studies integrated bioinformatic predictions, CRISPR-Cas9 editing, with bio-functional assays, including RNA pull-down, RIP, dual-luciferase reporter, CO-IP, and protein interaction analyses, to elucidate the circEif3c/miR-96-5p/PHF20L1/MEOX2 axis. In vitro and in vivo rescue experiments evaluated the role of exosomal circEif3c in AF proliferation, migration, apoptosis, and vascular remodeling. RESULTS: PVPAC-derived exosomes were enriched with circEif3c, which acted as a competitive endogenous RNA by sequestering miR-96-5p, thus alleviating its suppression of PHF20L1 and inhibiting MEOX2 signaling. This axis enhanced AF proliferation and migration, reduced apoptosis, and exacerbated vascular remodeling. Conversely, inhibition of exosomal circEif3c or overexpression of MEOX2 attenuated AF activation, promoted apoptosis, and markedly improved vascular remodeling in diabetic mice. CONCLUSION: Our findings establish the PVPAC-derived exosomal circEif3c/miR-96-5p/PHF20L1/MEOX2 axis as a critical driver of hyperglycemia-induced vascular remodeling. Targeting this pathway presents a promising therapeutic strategy to combat diabetes-associated vascular pathology and its complications.