OBJECTIVE  To observe the effect of Qufeng Zhike Decoction on the expression of the TRPV1 pathway in a guinea pig model with increased cough sensitivity, and to explore its mechanism of intervention on the laryngeal cough.

  METHODS  The laryngeal cough (guinea pig with increased cough sensitivity) model was prepared by intraperitoneal injection of egg protein sensitization combined with smoking and randomly divided into the blank group, model group, agonist group (Qufeng Zhike Decoction+capsaicin), Chinese medicine group (Qufeng Zhike Formula) and control group (Meimin Pseudoephedrine Solution). The changes in cough times before and after treatment were observed in each group. The morphology of throat mucosa, tracheal mucosa, and lung tissue was observed by H&E staining. The expressions of serum interleukin (IL)-1β, IL-10, and IgE were detected by ELISA. The expression levels of TRPV1, CGRP, NKA, and SP in the throat and tracheal mucosa were also detected by ELISA. The expressions of IL-1β, TRPV1, GFAP, and NGF in the cough center of medulla oblongata were detected by Western blot.

  RESULTS  Compared with the blank control group, the cough sensitivity of the model group was significantly increased (P < 0.01). Submucosal edema, inflammatory cell infiltration, and eosinophil count were observed in the throat, tracheal mucosa, and lung tissue. The expressions of serum IL-1β and IgE were increased (P < 0.01), IL-10 was decreased (P < 0.01), the contents of TRPV1, NKA, CGRP, and SP in the throat and tracheal mucosa were increased (P < 0.01), and the protein expressions of IL-1β, TRPV1, GFAP and NGF in the medullary cough center were increased (P < 0.01). Compared with the model group, the Qufeng Zhike Decoction had significantly reduced cough times (P < 0.01), significantly improved submucosal edema and inflammatory cell infiltration, significantly decreased serum eosinophil count and eosinophil percentage (P < 0.05, P < 0.01), significantly decreased serum IL-1β and IgE expressions (P < 0.01), and significantly increased IL-10 expression (P < 0.01). The contents of TRPV1, NKA, CGRP, and SP in the throat and tracheal mucosa were decreased (P < 0.05, P < 0.01), and the protein expressions of IL-1β, TRPV1, GFAP, and NGF in the cough center of medulla oblongata were decreased (P < 0.01). After treatment with Qufeng Zhike Decoction, compared with the Meimin Pseudoephedrine Solution, there were significant differences in serum IgE content, CGRP content in tracheal mucosa, and protein expressions of TRPV1, GFAP and NGF in cough center of the medulla oblongata (P < 0.05, P < 0.01), but no other significant differences; compared with the Qufeng Zhike Decoction+capsaicin, the difference between the two groups was statistically significant (P < 0.05, P < 0.01).

  CONCLUSION  Qufeng Zhike Decoction in treating laryngeal cough may regulate the expression of inflammatory factors through TRPV 1 pathway, inhibit neurogenic airway inflammation, reduce the high sensitivity of the peripheral airway and cough center, and reduce the recurrence.