Abstract: BACKGROUND: Acupoint catgut embedding can alleviate airway inflammation in asthma, which is related to regulating the imbalance of Th1/Th2 in the p38 MAPK pathway. Whether the above process is affected by the functional state of type II alveolar epithelial cells at the same time remains to be further studied.
OBJECTIVE: To observe the effect of acupoint catgut embedding on p38 MAPK pathway, interleukin-4, γ-interferon and type II alveolar epithelial cells in lung tissue of asthma rats.
METHODS: Forty male Wistar rats were randomly divided into blank control group, asthma model group, dexamethasone group and acupoint catgut embedding group (n=10 per group). Asthma models of asthma were prepared by intraperitoneal injection of ovalbumin and aluminum hydroxide suspension on days 1 and 8 and aerosol inhalation of ovalbumin solution from day 15 was given to induce symptoms of airway inflammatory responses, once a day for 2 weeks, in the latter three groups. Meanwhile, the dexamethasone group began to receive intraperitoneal injection of dexamethasone on day 15, once a day for 2 weeks; and the acupoint catgut embedding group received embedding treatment at Feishu, Dingchuan, and Danzhong acupoints on day 15. At the end of aerosol inhalation, the relative content of eosinophils in the alveolar lavage fluid was counted by Richter-Kimsa staining, the ultrastructural changes of type II alveolar epithelial cells in lung tissue were observed by transmission electron microscopy, the positive expression of interleukin-4 and γ-interferon in lung tissue was detected by immunohistochemistry, and the protein and gene expression of p-p38 MAPK, interleukin-4 and γ-interferon in lung tissue were detected by western blot and PCR respectively.
RESULTS AND CONCLUSION: Compared with the asthma model group, the relative content of eosinophils in the bronchoalveolar lavage fluid was significantly reduced in the dexamethasone group and acupoint catgut embedding group (P < 0.01), while compared with the dexamethasone group, the relative content of eosinophils in the bronchoalveolar lavage fluid was significantly higher in the acupoint catgut embedding group (P < 0.05). Under the transmission electron microscopy, damage to lamellar vesicles and mitochondria in type II alveolar epithelial cells was alleviated in the dexamethasone and acupoint catgut embedding groups compared with the asthma model group. Immunohistochemical detection showed that compared with the asthma model group, the expression of interleukin-4 in lung tissue was decreased (P < 0.01) and that of γ-interferon was increased (P < 0.01) in the dexamethasone and acupoint catgut embedding group; compared with the dexamethasone group, the expression of interleukin-4 in lung tissue was increased (P < 0.01) and that of γ-interferon was decreased (P < 0.01) in the acupoint catgut embedding group. Compared with the asthma model group, the protein and mRNA expressions of p-p38 MAPK and interleukin-4 in the lung tissue of the dexamethasone and acupoint catgut embedding groups were decreased (P < 0.01, P < 0.05), while the protein and mRNA expressions of γ-interferon were increased (P < 0.01). To conclude, acupoint catgut embedding may upregulate γ-Interferon and downregulate interleukin-4 by inhibiting the p38 MAPK signal pathway, thereby reducing stress damage in type ii alveolar epithelial cells and alleviating the airway inflammatory response in asthma.

Key words: acupoint catgut embedding, asthma, p38 MAPK, type II alveolar epithelial cell, interleukin-4, γ-Interferon