LPS-stimulated Macrophage Exosomes Inhibit Inflammation by Activating the Nrf2 / HO-1 Defense Pathway and Promote Wound Healing in Diabetic Rats

Abstract Background: Impaired wound healing is one of the important complications of diabetes. However, the specific pathogenesis is still unclear, and there is no effective treatment. Macrophages pretreated with chemical or biological factors may increase the biological activity of macrophage-derived exosomes, which is expected to become a new effective treatment method. The purpose of this study was to investigate whether the exosomes secreted by macrophages pretreated with lipopolysaccharide (LPS) have better anti-inflammatory and angiogenic abilities in the treatment of diabetic wound healing and their underlying molecular mechanisms. Methods: In this study, macroscopical, biochemical, histological, immunofluorescence and molecular biology methods were used to evaluate the potential protective mechanism and effect of lipopolysaccharide stimulated macrophage exosomes (LPS-Exos) on wound healing in streptozotocin induced hyperglycemia rats.In the in vivo experiment, the percentages of wound closure and contraction were compared and analyzed on the 7th, 14th, and 21st day after treatment by grouping treatments with different concentrations of LPS-Exos.At the same time, hematoxylin and eosin staining (HE), Masson staining, immunofluorescence staining and Western blotting (WB) were used for histological analysis of the wound tissue on the 14th day after injury to evaluate the impact of different treatment methods on wound healing.In in vitro experiments, the ability of endothelial cells related to proliferation, migration, tube formation and the expression of vascular endothelial growth factor (VEGF) were tested.At the same time, in vivo and in vitro experiments, the effect of Nrf2/HO-1 signaling pathway on LPS-Exos in inhibiting inflammation and promoting angiogenesis was evaluated by using exosome-specific inhibitors. Results: LPS-Exos reduced the content of ROS and MDA in the wound tissue of hyperglycemic rats, increased the activity of SOD and the production of GSH-Px, activated the Nrf2/HO-1 pathway, inhibited the expression of inflammation-related proteins, and promoted blood vessels generate. The group given exosome inhibitors reversed this phenomenon. Conclusions: LPS-Exos may activate the Nrf2/HO-1 defense pathway, improve endothelial cell function, inhibit oxidative damage and inflammation, and promote wound healing in diabetic rats, thereby having the potential to treat diabetic skin defects.