RESUMEN
Background: Lower limb ischemia due to arterial stenosis is a major complication in patients with diabetes mellitus (DM). Liraglutide is a long-acting analogue of a glucagon-like peptide 1 (GLP-1) receptor agonist used for lowering blood glucose in patients with DM, and is believed to possess cardiovascular protective effects. The aim of this study was to investigate whether liraglutide has a protective effect on blood vessels and alleviates vascular intimal hyperplasia in streptozotocin (STZ)-induced rabbits with DM and its molecular mechanism. Methods: Rabbits with DM were induced by STZ, and a lower limb ischemia model was established. The animals were divided into a control group, DM-injury group and liraglutide treatment group. Pathological staining was used to observe the intimal growth, analyze the oxidation levels of malondialdehyde (MDA), superoxide dismutase (SOD) and plasma glutathione peroxidase (GSH-Px), and analyze the changes in expression of marker proteins and signaling pathway proteins by Western blotting. A hyperglycemia (HG)-injured vascular smooth muscle cells (VSMCs) model was established to analyze reactive oxygen species (ROS) levels, Cell-Counting Kit-8 (CCK-8) was used to analyze cell proliferation, scratch assay and Transwell Migration Assay to analyze cell migration, flow cytometry to analyze apoptosis and Western blotting was used to analyze changes in the expression of marker and signaling pathway proteins. Results: The results of pathological staining showed that intimal hyperplasia was severe after diabetes-induced lower limb ischemia in rabbits at 4 weeks, and liraglutide treatment reduced symptoms. Liraglutide treatment significantly decreased MDA content, increased SOD, GSH-Px content, and augmented total antioxidant capacity levels in tissues. The results of Western blotting analysis showed that E-cadherin, mitochondrial membrane potential 9 (MMP-9), proliferating cell nuclear antigen (PCNA), and type I collagen protein expression levels were significantly decreased after liraglutide treatment compared with the DM injury group. The results indicated that liraglutide inhibited epithelial-mesenchymal transition (EMT) progression, vascular cell proliferation and migration and collagen production. Liraglutide inhibits transforming growth factor beta 1 (TGF-ß1)/Smad3 signaling pathway protein expression. In vitro assays have shown that liraglutide reduces cellular ROS levels, inhibits cell proliferation and migration and promotes apoptosis. Liraglutide down-regulated the expression of E-cadherin, MMP-9, PCNA, type I collagen protein as well as the TGF-ß1/Smad3 signaling pathway, but this effect could be reversed by tumor necrosis factor alpha (TNF-α). Conclusion: Liraglutide can significantly improve tissue antioxidant capacity, reduce vascular cell proliferation and migration via the TGF-ß1/Smad3 signaling pathway, inhibit the EMT and collagen production processes, and alleviate hyperglycemia(HG)-induced lower limb ischemia and intimal hyperplasia.