Abstract: Objective: To observe the effect of Yinqiao Powder on rats with recurrent oral ulcers (ROU) and to explore its influence on the IκB kinase β subunit (IKKβ)/nuclear factor κB p65 subunit (NF-κB p65) pathway. Methods: A rat model of ROU (recurrent oral ulcers) was established, and the rats were divided into the following groups: model group, prednisolone (20 mL/kg) group, Yinqiao Powder low-dose (16.74 g/kg crude drug) and high-dose (33.48 g/kg crude drug) groups, and normal control group. Each group consisted of 10 rats. The rats in each group were administered either the respective treatment or saline once daily by gavage for 20 consecutive days. The number of ulcers, duration, and interval time in the rats were observed and recorded. Histopathological changes of the ulcer tissue were observed using HE staining. Peripheral blood T lymphocyte subpopulations CD4⁺ and CD8⁺ were measured using flow cytometry. Serum and ulcer tissue levels of tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 were detected using ELISA and immunohistochemistry. The protein expressions of p-IKKβ, IKKβ, p-NF-κB p65, and NF-κB p65 in ulcer tissues were measured using Western blot. Results: Compared with the control group, the model group rats showed increased number of ulcers, peripheral blood CD8⁺ content, serum levels of TNF-α and IL-6, and protein expression levels of TNF-α, IL-6, p-IKKβ/IKKβ, and p-NF-κB p65/NF-κB p65 in ulcer tissues (P<0.05); peripheral blood CD4⁺ and CD4⁺/CD8⁺ contents were decreased (P<0.05). Compared with the model group, the prednisolone group and the Yinqiao Powder low- and high-dose groups showed reduced number and duration of ulcers, peripheral blood CD8⁺ content, serum levels of TNF-α and IL-6, and protein expression levels of TNF-α, IL-6, p-IKKβ/IKKβ, and p-NF-κB p65/NF-κB p65 in ulcer tissues (P<0.05); the interval time between ulcers and peripheral blood CD4⁺ and CD4⁺/CD8⁺ contents were increased (P<0.05); and the therapeutic effect of Yinqiao Powder was dose-dependent (P<0.05). Conclusion: Yinqiao Powder can promote ulcer healing by inhibiting the expression of inflammatory factors in serum and ulcer tissues of ROU rats, and regulating the balance of T cell subsets in peripheral blood. Its molecular mechanism may be related to the down-regulation of the IKKβ/NF-κB p65 signaling pathway.

Key words: Yinqiao Powder, recurrent oral ulcers, inflammatory factors, T cell subpopulation, IKK β/NF-κB p65 signaling pathway