Effectof MCC950 Intervention On Airway Muc5ac In Asthmatic Mice And Its Mechanism

Objective: To observe the effect of NLRP3 inflammasome inhibitor MCC950 intervention on airway Muc5 ac level in ovalbumin(OVA)-sensitized asthmatic mice,and to explore the role and mechanism of NLRP3 inflammasome in asthmatic airway mucus hypersecretion.Methods:A total of 50 SPF grade BALB/c female mice aged 6-8 weeks were randomly divided into normal control group(NS group),asthma model group(AS group),MCC950low-dose intervention group(ML group),MCC950 high-dose intervention group(MH group)and dexamethasone group(Dex group),with 10 mice in each group.Mice in AS group were given intraperitoneal injection of OVA mixed with aluminum hydroxide gel and sensitized by subcutaneous injection on the 1st day and the 13 th day of the experiment respectively,followed by challenge with 10%OVA for atomization on day 19-23.In NS group,PBS and normal saline were used instead of OVA for sensitization and challenge,respectively.Mice in MH group and Dex group were injected with 10mg/kg MCC950 and2mg/kg dexamethasone intraperitoneally 30 minutes before challenge with atomization,and the other treatments were the same as those in AS group.Mice in ML group were intervened by intraperitoneal injection of 10mg/kg MCC950 30 minutes before challenge with atomization every other day,and the remaining treatments were the same as those in AS group.Mice in each group were sacrificed 24 h after the end of the last stimulation,and bronchoalveolar lavage fluid(BALF)and lung tissue samples were sampled.Furthermore,the bronchoalveolar lavage fluid(BALF)of mice in each group was counted by total cell count,associated with white blood cell different count.In addition,the concentrations of IL-18 and IL-1β in BALF were tested by enzyme-linked immunosorbent assay(ELISA).The lung tissues were prepared into paraffin-embedded sections,which were then subject to hematoxylin-eosin(HE)staining,Alcian blue-periodic acid Schiff base(AB-PAS)staining and Masson staining to observe the pathological changes of lung tissues.Immunohistochemistry(IHC)was used to detect the protein expression levels of Muc5 ac,NLRP3 and Caspase-1 in lung tissues.Real-time polymerase chain reaction(q RT-PCR)was performed to detect the relative m RNA expressions of Muc5 ac,NLRP3 and Caspase-1in lung tissues.Results: Compared with NS group,AS group showed significant increase in total cell count of BALF,the percentage of eosinophils,the infiltration score of inflammatory cells around the airway,the positive relative staining area of airway mucus and the deposition area of airway collagen fibers in mice(P<0.05),upregulated protein expression levels of Muc5 ac,NLRP3 and Caspase-1 in lung tissues(P<0.05),elevated relative m RNA expressions of Muc5 ac,NLRP3 and Caspase-1 in lung tissues(P<0.05),and raised concentrations of IL-18 and IL-1β in BALF(P<0.05).While compared with AS group,the above indicators were reduced in MH group and ML group(P<0.05).Moreover,in relative to Dex group,these indicators were increased in MH group ML group(P<0.05).In addition,no statistically significant difference was observed in the aforementioned indications between MH group and ML group(P>0.05).Conclusion: MCC950 intervention can inhibit airway inflammation and airway mucus secretion in asthmatic mice.Its mechanism is speculated to be related to the suppression of NLRP3,Caspase-1,IL-18 and IL-1β expressions,downregulation of Muc5 ac expression,and inhibition in airway mucus hypersecretion.