Acupoint injection ameliorates Th1/Th2 imbalance through Toll-like receptor 4/activator protein-1 signal pathway and improves inflammatory response in rats with allergic rhinitis

Abstract

To observe the effect of acupoint injection on serum T helper (Th)1/Th2 related cytokines, and the expression levels of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and activator protein-1 (AP-1) of nasal mucosa in allergic rhinitis (AR) rats, so as to explore its mechanism underlying improvement of AR. Thirty-two SD rats were randomly divided into normal, model, non-acupoint injection and acupoint injection groups (n=8 in each group). The AR model was established by ovalbumin sensitization. In the acupoint injection group, "Yintang" (GV24+) and bilateral "Yingxiang" (LI20) were selected for injection of mixture solution of dexamethasone and lidocaine (0.05 mL/acupoint), once every 4 days for a total of 4 times. The non-acupoints, located at the midpoint between the "Houhai" and "Huantiao" (GB30) on the bilateral hips and the sites 5 cm inferior to the axillary were injected with the same dose of mixture solution as that in the acupoint injection group. The AR severity was assessed by cumulative quantification scoring methods (including the numbers of nose-catching and sneezes, and the amount of nasal secretions in 30 min). The pathological changes of nasal mucosa were observed by HE staining. The contents of immunoglobulin E (IgE), interleukin (IL)-4 and interferon (IFN)-γ in serum were detected by ELISA. The expressions of TLR4 and MyD88 in nasal mucosa was detected by immunofluorescence. The expression of AP-1 in nasal mucosa was detected by Western blot. Following modeling, the AR symptom score, serum IgE and IL-4 contents and expression of TLR4, MyD88 and AP-1 of nasal mucosa were significantly increased in the model group than those in the normal group (P<0.01), while the serum IFN-γ content was significantly decreased (P<0.01). Compared with the model group and non-acupoint injection group, the AR symptom score, the serum contents of IgE and IL-4 and the expressions of TLR4, MyD88 and AP-1 in nasal mucosa were significantly decreased in the acupoint injection group (P<0.01, P<0.05), while the serum IFN-γ content was significantly increased (P<0.01). H.E. staining of the nasal mucosa showed that most of the epithelium fell off, the lamina propria vessels expanded, the glands proliferated, and eosinophils and lymphocytes infiltrated in the model and non-acupoint injection groups, and those were significantly improved in the acupoint injection group. Acupoint injection can effectively improve allergic inflammation of the nose in AR rats, which may be related with its function in inhibiting the abnormal activation of TLR4/AP-1 signaling pathway and regulating the imbalance of Th1/Th2.