OBJECTIVE To observe the clinical efficacy of Zhenshi Burn Ointment on postoperative wound healing of simple anal fistula and explore its potential mechanism of action.

METHODS A total of 60 patients with low-position simple anal fistula of damp-heat pouring downward type admitted to the Department of Anorectum, Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine from May to December 2023 were selected as the research subjects and randomly divided into an experimental group and a control group, with 30 cases in each group. After surgery, the control group was given sterilized vaseline gauze for external application, and the experimental group was given Zhenshi Burn Ointment for external application. The course of treatment for both groups was 30 d. After treatment, the postoperative wound healing time, wound healing rate, pain score, wound granulation growth and secretion, and changes in TCM syndrome score were compared between the two groups. The pathological sections of wound granulation tissue were compared 14 d after surgery. The transcription levels of COL1A1, type Ⅲ collagen (COL3A1), epidermal growth factor (EGF), and fibroblast growth factor (FGF2) in granulation tissue were detected by qPCR. The expression levels of proteins related to MEK/ERK signaling pathway were detected by Western blot.

RESULTS Compared with the control group, the wound healing rates of the experimental group were significantly increased at 7, 14, 21, and 30 d after surgery (P < 0.01), and the wound healing time was significantly shortened (P < 0.01). At 7 d after surgery, the pain score of the experimental group was significantly lower than that of the control group (P < 0.05). At 7 and 14 d after surgery, the granulation growth score of the wound in the experimental group was significantly lower than that of the control group (P < 0.01). At 14 d after surgery, the secretion score of the experimental group was significantly lower than that of the control group (P < 0.01). At 14 and 30 d after surgery, the total score of TCM syndrome in the experimental group was significantly better than that in the control group (P < 0.05). At 14 d after surgery, the pathological improvement of granulation tissue in the wound in the experimental group was better than that in the control group, and the content of collagen fiber and type I collagen (Collagen I) was significantly higher than that in the control group (P < 0.01). The mRNA contents of COL1A1, COL3A1, EGF, and FGF2 were significantly higher than those in the control group (P < 0.05, P < 0.01); the levels of p-MEK1/2 and p-ERK1/2 proteins were higher than those in the control group (P < 0.05).

CONCLUSION Zhenshi Burn Ointment has a good effect on promoting postoperative anal fistula wound healing, which may be related to upregulating growth factor expression, promoting collagen regeneration, and activating MEK/ERK pathway.