Immunomodulatory effect of Sema4D on Th1/Th2 in asthmatic rats induced by RSV and intervention of Kechuanning oral liquid

AIM To explore the effect of semaphorin 4D (Sema4D) on the immune regulation of Th1/Th2 in asthmatic rats induced by respiratory syncytial virus (RSV) and the effect of Kechuanning (KCN) intervention on the asthmatic rats. METHODS Healthy SPF female Wistar rats (n=100) were randomly divided into 10 groups: normal group, model group, Sema4D group, Sema4D antibody group, low, middle and high doses of KCN groups, and Sema4D+low, middle and high doses of KCN groups. Except the rats in normal group, the other rats were treated with RSV combined with ovalbumin (OVA) to induce asthmatic model. The pathological changes of the lung tissue were observed by HE staining, and the levels of interleukin-4 (IL-4), IL-6, IL-8, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in bronchoalveolar lavage fluid (BALF) were measured by ELISA. RESULTS Inflammatory cell infiltration and inflammatory damage in lung tissues of the rats in model group, Sema4D group and Sema4D+low dose of KCN group were observed by HE staining, while these pathological changes were attenuated in Sema4D antibody group， low, middle and high doses of KCN groups, and Sema4D+middle and high doses of KCN groups. Compared with normal group, the levels of IL-4, IL-6, IL-8 and TNF-α in BALF of the rats in the other groups were significantly increased, and the level of IFN-γ was significantly lowered (P<0.05 or P<0.01). Compared with model group, the levels of IL-4, IL-6, IL-8 and TNF-α in Sema4D group were increased, and the content of IFN-γ was decreased (P<0.05 or P<0.01). Compared with model group, the levels of IL-4, IL-6, IL-8 and TNF-α in Sema4D antibody group, low, middle and high doses of KCN groups, and Sema4D+low, middel and high doses of KCN groups were significantly decreased (P<0.01), while the content of IFN-γ was significantly increased (P<0.05 or P<0.01). No significant difference among Sema4D antibody group, Sema4D+middle and high doses of KCN groups, and low, middle and high doses of KCN groups was observed (P>0.05). CONCLUSION Sema4D causes Th1/Th2 immune imbalance and aggravates asthma. Inhibition of Sema4D reduces the production of inflammatory factors and regulates the balance of Th1/Th2. KCN may attenuate RSV-induced immune inflammation of asthmatic rats by inhibiting Sema4D, so as to achieve the anti-asthma effect.