Guilongwan Ameliorates Experimental Diabetic Foot Ulcer in Rats via the Inhibition of Delta‐Like 4/Notch1 Signaling in M1 Macrophages

Guilongwan (GLW), a representative of traditional Chinese Medicine (TCM) has been utilized to treating diabetic foot ulcer (DFU)-related syndrome including an intolerance of cold with cold limbs, blood circulation disorder, and immune dysfunction for decades. However, the chemical and biological mechanisms of GLW remain unclear. This study aims to discover the biological mechanisms of GLW on DFU by using streptozotocin- and skin-puncher-induced DFU rat models, in vitro macrophage models, and in silico analysis. The alterations in pathology, Notch1 signaling, and macrophage polarization are detected. The results indicated that GLW promoted wound healing, cutaneous cell proliferation, and angiogenesis in DFU rats by inhibiting delta-like (DLL) 4/Notch1 signaling. In addition, GLW inhibited M1 polarization and promoted M2 polarization in diabetic wounds. Seventeen chemical compounds in GLW-medicated serum are identified. In silico analysis and in vitro experiments demonstrated that GLW-medicated serum and its main compounds inhibited the expression of DLL4 in matrix metalloproteinase-9-induced M1 macrophages. In conclusion, GLW ameliorated experimental DFU rats via the inhibition of DLL4/Notch1 signaling in M1 macrophages. This study provided a new biologic mechanism for GLW in the treatment of DFU.