Periplaneta americana extract ameliorates recurrent oral ulcers in rats by enhancing the intestinal epithelial barrier and regulating gut microbiota.

BACKGROUND: Recurrent oral ulcers (ROUs) of oral mucosa disease are difficult to cure and relapse easily. Periplaneta americana extract (PAD), a raw material used in Kangfuxin Liquid and Yunnan Baiyao toothpaste, contains a variety of growth factors such as polypeptides and sticky sugar amino acids that promote tissue repair; this can encourage the growth of granulation tissue and reduce inflammation on wound surfaces. OBJECTIVE: In this study, we used a rat model of ROU induced by an antigen emulsifier to assess the ameliorative effects of PAD on rat ROUs and to explore its mechanism of action. METHODS: The effect of PAD in rats was evaluated by an enzyme-linked immunosorbent assay (ELISA) kit, hematoxylin-eosin staining, immunohistochemistry, reverse transcription quantitative PCR (RT-qPCR), and Western Blot (WB). 16S rRNA sequencing and gas chromatography-mass spectrometry (GC-MS) were used to detect the changes in intestinal flora and its metabolite short-chain fatty acids (SCFAs) in the feces of rats, respectively. RESULTS: PAD significantly reduced the infiltration of local inflammatory cells and significantly downregulated interleukin (IL)-6 and tumor necrosis factor (TNF-α), while upregulating IL-2, IL-10, and vascular endothelial growth factor (VEGF). In addition, PAD altered the diversity and abundance of the gut microbiota and increased fecal short-chain fatty acid levels. Notably, PAD can improve the pathological injury of the colon, enhance the intestinal barrier of the colon, and reduce the apoptosis of colon cells. CONCLUSION: The oral administration of PAD may effectively treat ROUs via regulating metabolites and altering the composition of the intestinal microbiota, thereby improving the intestinal barrier function.