Jinping Decoction Prevents Respiratory Syncytial Virus Infection by Improving Respiratory Immunity

  OBJECTIVE  To investigate the immunoregulatory effect of Jinping decoction (JP) on immunocompromised mice and its preventive effect on RSV infection.

  METHODS  90 Balb/c mice were randomly divided into control group, model group, pidotimod group (0.3 g·kg^-1), JP high dose group (55.2 g·kg^-1), middle dose group (27.6 g·kg^-1), low dose group (13.8 g·kg^-1), 15 mice in each group. The immunocompromised mouse model was constructed by intraperitoneal injection of dexamethasone. After 7 days of intragastric administration with normal saline, pidotimod, high, medium low doses of JP, RSV was infected intranasally. The control group received nasal drops of the same volume of normal saline. The body weight of mice was recorded, and the spleen volume was photographed. Flow cytometry was used to detect the proportion of immune cell subsets: CD4⁺T, CD8⁺T, NK and DC in spleen, mesenteric lymph nodes and lung tissues. Lung viral load, expression levels of IFN-β mRNA and ISG15 mRNA were detected by qPCR. HE staining was used to evaluate the pathological changes of lung tissue. Lymphocyte infiltration in bronchoalveolar lavage fluid (BALF), the proportion of activated CD8⁺T cells (CD8⁺CD69⁺T) and memory T cells in lung tissue were detected by flow cytometry.

  RESULTS  JP treatment significantly restored the body weight of model mice, and the proportion of CD8⁺T, NK and DC cells in mesenteric lymph nodes and lung tissue. qPCR results illustrated that compared with the model group, the JP treatment group could reduce the RSV load in the lungs of mice and increase the mRNA expression of IFN-β and ISG15 (P < 0.05, P < 0.01, P < 0.001). Flow cytometry showed that lymphocyte infiltration in lung tissue of mice in the JP treatment group was significantly reduced compared with the model group (P < 0.01). The results of HE staining and flow cytometry revealed that JP could improve the histopathological morphology of lung in mice, promote the activation of CD8⁺T cells and increase the proportion of central memory T cells (P < 0.01).

  CONCLUSION  JP can improve the immunosuppression of model mice, and effectively prevent RSV infection, alleviate the pathological damage of lung inflammation and enhance the immune memory after RSV infection by increasing the antiviral immune response mediated by type Ⅰ interferon and CD8⁺T cells.