Visfatin from Adipocyte Accelerates Vascular Calcification via TLR4

Background: Vascular calcification is a common complication in metabolic diseases, such as diabetes and obesity, contributing to cardiovascular morbidity. Visfatin, an adipokine secreted by visceral fat, has been confirmed to be closely associated with metabolic dysfunctions. Methods: Vascular calcification models were established in mice through intraperitoneal injection of vitamin D (VitD). Serum visfatin levels were measured in both patients with coronary artery calcification and calcified mice. Visfatin expression in visceral fat was assessed by molecular analyses. To examine the functional role of visfatin, mice with adipose-specific visfatin overexpression were generated. Primary vascular smooth muscle cells (VSMCs) were treated with calcification medium and recombinant visfatin to assess osteogenic differentiation. The interaction between visfatin and Toll-like receptor 4 (TLR4) was investigated, and Tlr4 knockout models were used to verify its role. Empagliflozin was administered to evaluate its effects on vascular calcification and visfatin expression, along with related signaling pathway analyses. Results: Serum visfatin levels were significantly elevated in patients with high coronary artery calcification scores and in mice with vascular calcification compared to controls. Visfatin expression was also markedly increased in the visceral adipose tissue of calcified mice. Mice with adipose-specific visfatin overexpression showed aggravated vascular calcification following vitamin D treatment. In vitro, visfatin enhanced the osteogenic differentiation of VSMCs in response to calcification medium. Mechanistically, visfatin directly bound to TLR4 and promoted the osteogenic transformation of VSMCs. Tlr4 deletion significantly attenuated aortic calcification induced by visfatin both in vivo and in vitro. Empagliflozin treatment significantly reduced vascular calcification and lowered circulating visfatin levels. Furthermore, empagliflozin inhibited the activation of the p38/NF-κB signaling pathway in adipose tissue, reduced nuclear translocation of NF-κB, suppressed its binding to the visfatin promoter, and thereby downregulated visfatin expression in adipocytes. Conclusions: that visfatin secreted from visceral fat accelerates VSMCs osteogenic differentiation and vascular calcification via TLR4. Empagliflozin inhibits the expression of visfatin in adipocytes through the p38/NF-κB signaling pathway, thereby suppressing vascular calcification. The results suggest that visfatin may represent a novel therapeutic strategy for preventing or treating vascular calcification and related cardiovascular diseases.