Thoracic perivascular adipose tissue-derived PI16 alleviates vascular calcification via CKAP4/PI3K/Akt pathway

Medial arterial calcification (MAC) is a major vascular complication of chronic kidney disease (CKD) and a strong predictor of cardiovascular morbidity and mortality, yet pharmacological interventions directly targeting this process remain limited. Thoracic perivascular adipose tissue (tPVAT) is increasingly recognized as a regulator of vascular homeostasis, but its role in medial arterial calcification remains unclear. Here we investigated whether tPVAT confers protection against medial arterial calcification and the underlying mechanisms. Using complementary experimental models of vascular calcification, including adenine-induced CKD and vitamin D3-induced calcification, we found that the thoracic aorta exhibited delayed medial calcification compared with the abdominal aorta. Transplantation of tPVAT attenuated abdominal aortic calcification across multiple models. A factor derived from early-stage tPVAT suppressed vascular smooth muscle cell calcification in vitro. Peptidase inhibitor 16 (PI16), predominantly derived from fibroblasts, was identified as a key anti-calcific factor in tPVAT, and its protective effect was confirmed using recombinant PI16. Mechanistically, PI16 interacted with cytoskeleton-associated protein 4 (CKAP4), a membrane-associated protein on vascular smooth muscle cells, resulting in inhibition of the PI3K/Akt/RUNX2 signaling pathway and suppression of osteogenic differentiation. These findings identify PI16 as a tPVAT-derived inhibitor of vascular calcification and reveal a PI16-CKAP4 signaling pathway that may represent a potential therapeutic target in CKD-associated vascular calcification.