High-glucose-induced macrophage M1 polarization impairs endothelial cell functions (A) The histopathological characteristics of normal control (NC; n=12) and diabetic foot ulcer (DFU; n=12) clinical samples were examined using H&E and Masson staining. (B) The mRNA expression of iNOS and CD163 in NC and DFU samples was examined using qRT-PCR. (C) The protein levels of iNOS and CD163 in NC and DFU samples were examined using Immunoblotting. THP-1 cells were treated with PMA at 5 ng/mL for 48 h to induce M0 differentiation, treated with 30 mM glucose (high-glucose, HG) to induce M1 polarization, and examined for the levels of CD68, iNOS, and Arg-1 using Immunofluorescent staining (IF staining) (D); the levels of IL-6, MCP-1, IL-4, and IL-10 in the culture medium using ELISA (E); the mRNA expression and protein levels of iNOS and Arg-1 using qRT-PCR and Immunoblotting, respectively (F). THP-1 cells were treated with PMA at 5 ng/mL for 48 h to induce M0 differentiation, treated with 30 mM glucose (high-glucose, HG) for 72 h to induce M1 polarization, and collected for the conditioned culture medium (M0)-CM or (HG+M0)-CM) to incubate HUVECs. The cell viability of HUVECs was examined using CCK-8 assay (G); tube formation capacity of HUVECs was determined using tube formation assay (H); HUVECs cell migration was determined using Wound healing assay (I); the protein levels of Ang1, Flk1, Vash1, TSP1I, ICAM-1, and VCAM-1 were determined using Immunoblotting assay (J). n=3, ** p<0.01.