Research On The Mechanism Of Salidroside Alleviating Airway Inflammation In Asthma Through JAK2/STAT3 Signaling Pathway

Objective: To observe the effect of SAL on OVA-induced airway inflammation in mice with acute asthma,and to explore the relationship between SAL and Janus kinase 2(JAK2)/signal transduction and transcription The relationship between activator 3(STAT3)signaling pathways.Methods: Fifty 6-8 weeks old,weighing 18-22 g,clean grade,female BABL/c experimental mice were randomly divided into 5 groups: normal control group(Control group),asthma model group(OVA group),SAL low-dose glycoside group(SAL15group),high-dose SAL group(SAL30 group)and dexamethasone group(DEX group),There were 10 mice in each group.This experiment will use the method of OVA sensitization and challenge to construct an acute asthma mouse model.Except for the normal control group,mice in each group were sensitized by intraperitoneal injection on the 1st,7th,and 14 th days with 200 ul of freshly prepared normal saline(containing OVA 20 ug + Alum 50ul).The same amount of normal saline(NS)200ul was injected intraperitoneally;from the 17 th day,the mice except the Control group were placed in a closed space and stimulated by aerosol inhalation of 5% OVA solution 10 ml,and other conditions were the same in the Control group by aerosol inhalation of 10 ml NS,30 min each time for 7 days.During drug challenge,SAL15 group,SAL30 group and DEX group were given SAL low-dose 15mg/kg,SAL high-dose 30mg/kg,dexamethasone2mg/kg by intraperitoneal injection,and the therapeutic drugs were dissolved in 200 ul NS.The mice in the control group and the OVA group were also intraperitoneally injected with 200 ul of NS,which was administered 1 hour before nebulization,for a total of 7 days.The experimental mice were treated 24 hours after the last nebulization challenge,and bronchoalveolar lavage fluid(BALF)and lung tissue were collected.Detection of cell classification and count;2)ELISA method was used to detect the content of related inflammatory factors;3)The collected lung tissue was embedded in paraffin and sectioned,and HE and Masson staining were performed later;4)Western blotting was used to detect the expression of JAK2/STAT3 signaling pathway-related proteins;5)The expression of p-JAK2 and p-STAT3 proteins in lung tissue was observed by immunofluorescence method of tissue sections.Results: 1)In BALF,the counts of total inflammatory cells(Total cell),eosinophils(EOS),neutrophils(NEU)and lymphocytes(LYM)in OVA group were significantly higher than those in control group,compared with the Control group,the difference was statistically significant(P<0.05);after SAL treatment,the inflammatory cell counts in the SAL15 and SAL30 groups were decreased,and with the increase of SAL dose,the counts of Total cell,EOS,NEU,and LYM decreased significantly,and the difference was significant in the OVA group(P<0.05).2)Compared with the control group,the levels of IL-4,IL-5,and IL-13 in the OVA group were significantly increased by ELISA,and the difference was statistically significant(P<0.05).After SAL intervention,the expressions of IL-4,IL-5,and IL-13 in BALF were lower than those in the OVA group,and the difference was statistically significant(P<0.05);3)HE and Masson staining:HE staining showed no obvious pathological changes in the Control group.In the OVA group,the airway epithelium was damaged,the lumen was narrowed,and a large number of inflammatory cells were exuded around the airway and blood vessels.Masson staining showed a large number of collagen fibers in the OVA group.Deposition,goblet cells and mucus secretion increased significantly,airway inflammatory cells decreased in SAL15 group and SAL30 group,and the pathological morphological changes decreased significantly with the increase of SAL dose,and the changes in SAL30 group and DEX group were more significant;4)Western blotting analysis of related protein expression: there was no significant difference in the expression of JAK2 and STAT3 proteins among the groups.The expression of P-JAK2 and P-STAT proteins in the OVA group was significantly higher than that in the Control group,and the difference was statistically significant(P<0.05).Compared with OVA group,salidroside and dexamethasone treatment group significantly inhibited the expression of P-JAK2 and P-STAT3 protein(P<0.05);5)The expression of P-JAK2 and P-STAT3 protein in the airway wall and smooth muscle of the model group was significantly increased and the fluorescence intensity was enhanced compared with that of the normal control group.After salidroside and dexamethasone treatment,the expression of P-JAK2 and P-STAT3 protein was inhibited,and the fluorescence intensity was weakened.Different doses of salidroside had different inhibitory effects on airway inflammation in a dose-dependent manner,and the high concentration of SAL group and dexamethasone group had significant inhibitory effects on inflammation.Conclusion: 1.SAL can inhibit OVA-induced airway inflammation in acute asthmatic mice.2.The mechanism by which SAL alleviates airway inflammation in asthmatic mice may be related to the JAK2/STAT3 signaling pathway.