ObjectiveTo explore the potential mechanism of Xiaoqinglong Decoction （小青龙汤， XD） in the treatment of allergic rhinitis. MethodsForty-five rats were randomly assigned to a control group， a model group， a loratadine group， low-， medium- and high-dose XD groups， and low-， medium- and high-dose Mahuang Decoction and Cang'erzi Powder （麻黄汤合苍耳子散， MDCP） groups. Except for the control group， rats were administered with ovalbumin （OVA） and aluminum hydroxide via intraperitoneal injection for 14 days to establish an allergic rhinitis model. After the 14th-day injection， nasal stimulation was continued with 20 μl of 10% OVA solution to maintain the model. Rats in the control group and the model group received 10 ml/（kg·d） of saline， whereas those in the loratadine group were administered with 0.9 mg/（kg·d） of loratadine. The low-， medium- and high-dose XD groups were administered XD at the dose of 2.7， 5.4， and 10.8 g/（kg·d）， respectively. The low-， medium- and high-dose MDCP groups were administered MDCP at the dose of 2.43， 4.86， and 9.72 g/（kg·d）， respectively. All treatments were administered by gavage once daily for 7 consecutive days. One hour after the final gavage， nasal symptom scores were recorded for all group of rats. The next day， serum levels of immunoglobulin E （IgE）， interleukin-4 （IL-4）， and interleukin-13 （IL-13） were measured. HE staining was used to observe the pathological morphology of the nasal mucosal tissue. Quantitative reverse transcription PCR （RT-qPCR） and Western Blot were performed to assess mRNA and protein expression of thymic stromal lymphopoietin （TSLP） and OX40 ligand （OX40L） in the nasal mucosa. ResultsCompared to the control group， total nasal symptom score in the model group significantly increased （P＜0.01）. HE staining revealed disrupted and adhered cilia， thickened basement membranes， and extensive inflammatory cell infiltration in the nasal mucosa. Serum levels of total IgE， IL-4， and IL-13， as well as TSLP and OX40L mRNA and protein expression in the nasal mucosa， were significantly elevated in the model group （P＜0.05 or P＜0.01）. Compared to the model group， the total nasal symptom scores in all drug intervention groups were significantly reduced； the serum total IgE levels in the loratadine group， the low- and medium-dose XD groups， and the low- and high-dose MDCP groups were significantly reduced； and the serum levels of IL-4 and IL-13 in the high-dose XD group and the high-dose MDCP group decreased （P＜0.05 or P＜0.01）. Nasal mucosal structure was improved. Except for the low-dose MDCP group， all other intervention groups showed a significant reduction in TSLP and OX40L mRNA expression in the nasal mucosa （P＜0.01）. All doses of XD and the medium- and high-dose MDCP groups significantly decreased the protein levels of TSLP and OX40L （P＜0.05）. The medium-dose XD group exhibited more improvement of nasal symptom scores and greater suppression of expression of TSLP and OX40L mRNA， and TSLP protein levels compared to the loratadine group （P＜0.05）. ConclusionXD may protect nasal mucosa of rats and alleviate allergic rhinitis by suppressing the TSLP/OX40L pathway， thereby attenuating Th2-mediated immune responses.

ObjectiveTo explore the potential mechanism of Xiaoqinglong Decoction （小青龙汤， XD） in the treatment of allergic rhinitis. MethodsForty-five rats were randomly assigned to a control group， a model group， a loratadine group， low-， medium- and high-dose XD groups， and low-， medium- and high-dose Mahuang Decoction and Cang'erzi Powder （麻黄汤合苍耳子散， MDCP） groups. Except for the control group， rats were administered with ovalbumin （OVA） and aluminum hydroxide via intraperitoneal injection for 14 days to establish an allergic rhinitis model. After the 14th-day injection， nasal stimulation was continued with 20 μl of 10% OVA solution to maintain the model. Rats in the control group and the model group received 10 ml/（kg·d） of saline， whereas those in the loratadine group were administered with 0.9 mg/（kg·d） of loratadine. The low-， medium- and high-dose XD groups were administered XD at the dose of 2.7， 5.4， and 10.8 g/（kg·d）， respectively. The low-， medium- and high-dose MDCP groups were administered MDCP at the dose of 2.43， 4.86， and 9.72 g/（kg·d）， respectively. All treatments were administered by gavage once daily for 7 consecutive days. One hour after the final gavage， nasal symptom scores were recorded for all group of rats. The next day， serum levels of immunoglobulin E （IgE）， interleukin-4 （IL-4）， and interleukin-13 （IL-13） were measured. HE staining was used to observe the pathological morphology of the nasal mucosal tissue. Quantitative reverse transcription PCR （RT-qPCR） and Western Blot were performed to assess mRNA and protein expression of thymic stromal lymphopoietin （TSLP） and OX40 ligand （OX40L） in the nasal mucosa. ResultsCompared to the control group， total nasal symptom score in the model group significantly increased （P＜0.01）. HE staining revealed disrupted and adhered cilia， thickened basement membranes， and extensive inflammatory cell infiltration in the nasal mucosa. Serum levels of total IgE， IL-4， and IL-13， as well as TSLP and OX40L mRNA and protein expression in the nasal mucosa， were significantly elevated in the model group （P＜0.05 or P＜0.01）. Compared to the model group， the total nasal symptom scores in all drug intervention groups were significantly reduced； the serum total IgE levels in the loratadine group， the low- and medium-dose XD groups， and the low- and high-dose MDCP groups were significantly reduced； and the serum levels of IL-4 and IL-13 in the high-dose XD group and the high-dose MDCP group decreased （P＜0.05 or P＜0.01）. Nasal mucosal structure was improved. Except for the low-dose MDCP group， all other intervention groups showed a significant reduction in TSLP and OX40L mRNA expression in the nasal mucosa （P＜0.01）. All doses of XD and the medium- and high-dose MDCP groups significantly decreased the protein levels of TSLP and OX40L （P＜0.05）. The medium-dose XD group exhibited more improvement of nasal symptom scores and greater suppression of expression of TSLP and OX40L mRNA， and TSLP protein levels compared to the loratadine group （P＜0.05）. ConclusionXD may protect nasal mucosa of rats and alleviate allergic rhinitis by suppressing the TSLP/OX40L pathway， thereby attenuating Th2-mediated immune responses.