To Explore The Effect Of Insulin Resistance On Airway Hyperresponsiveness And Airway Inflammation In Asthmatic Mice

Part I Establishment of mouse insulin resistance-asthma model and its evaluationObjective: We are aimed to establish a model of insulin resistance-asthma,and to evaluate its.Method: After one week feeding,sixty 3-week-old C57 BL / 6J mice were randomly divided into two groups,30 mice in each group.The normal group of mice were fed with normal diet and the high fat group were given high fat diet(D12492)feeding.All mice were fed until week 6-14,and fasting blood glucose(FBG)and fasting serum insulin(FINS)were measured weekly.HOMA-IR was used to evaluate the level of insulin resistance.The value of HOMA-IR> 2.5 means successful establishment of insulin resistance mouse model.The normal group of mice were assigned to normal control group(HC)and asthma group(NIRA).Respectively,the high fat group that had successfully established insulin resistance were assigned to insulin resistance group(IRNA),insulin resistance-asthmagroup(IRA),in which NIRA and IRA mice continued to be sensitized and challenged with ovalbumin(OVA)to induce asthma.HC group and IRNA group were treated with equal normal saline(NS)as control.After the last operation for 24 h,pathological sections of lungs were made and the indexes of insulin resistance.Serum anti-OVA-specific Ig E and Ig G1 levels were measured,and insulin resistance index and asthma evaluation index were evaluated in each group.Result: 1.At the end of the 9th week,the mouse model of insulin resistance was successfully established in high fat diet group.2.The pathological changes of lung tissue were obvious in NIRA group and IRA group,and infiltration of inflammatory cells in IRA group was more obvious.3.The serum levels of OVA-specific Ig E and Ig G1 in NIRA and IRA groups were significantly higher than those in HC and IRNA groups(P <0.01).And the levels of serum Ig E and Ig G1 in IRA group were higher than those in NIRA group(P <0.05).Conclusion:It is a feasible method to establish a stable insulin resistance mouse model by feeding C57 BL / 6J mice with high-fat diet(D12492)for 9 weeks.Based on this,a model of insulin resistance-asthma can be successfully established by inducing asthma.The experiment confirmed that obesity does not necessarily exist insulin resistance,which is related to the duration and extent of obesity.The experimental method established insulin resistance asthma model is stable,and the economic cost is low,this method has strong practicality and operability.Part II To explore the effect of insulin resistance on airway hyperresponsiveness and airway inflammation in asthmatic miceObjective:To explore the effect of insulin resistance on airway hyperresponsiveness and airwayinflammation in asthmatic mice.Method: After routine feeding,60 3-week-old C57 BL / 6J mice were selected according to the first part of the modeling method to establish insulin resistance asthma model.During the last 24 hours of operation,5 mice in each group were randomly selected and anesthetized for endotracheal intubation.Each mouse was inhaled at concentrations of 0,3,6,12,25,50,and 100 mg / ml Mch,followed by an interval of 2 min.The total airway resistance(Rrs)of the mice was measured and recorded.After 24 hours after the last challenge,bronchoalveolar lavage was performed after collecting the blood of the mice by enucleation.Bronchoalveolar lavage fluid was collected from each group to count the total number of white blood cells in the BALF.The levels of related inflammatory factors in BALF and serum were detected and the changes of airway hyperresponsiveness and airway inflammation in mice were analyzed.Result: 1.Airway resistance of mice in NIRA group and IRA group increased gradually with the increase of inhaled Mch concentration,while there was no significant change of airway resistance in HC group and IRNA group.When compared with HC group,airway resistance of mice in NIRA group and IRA group was significantly increased(P <0.05).Compared with NIRA group,airway resistance of mice in IRA group was significantly increased(P <0.05).2.The total number of leukocytes in BALF of NIRA and IRA mice was significantly higher than that of HC and IRNA mice(P <0.01),while the number of white blood cells in IRA mice was more than that of NIRA mice(P <0.01).3.The levels of IL-4 and IL-17 in BALF and serum in NIRA and IRA group were significantly higher than those in HC and IRNA group(P <0.01),and the concentration of INF-? was significantly lower(P <0.05);The levels of IL-4 and IL-17 in BALF and serum in IRA group were visibly higher than those in NIRA group(P <0.05),while the concentrations of INF-? in BALF and serum were obviously lower than those in NIRAgroup(P <0.05).Conclusion: 1.Insulin resistance can increase airway hyperresponsiveness in asthmatic mice.2.Insulin resistance can promote the release of inflammatory cytokines IL-4,IL-17 and reduce the level of IFN-? in OVA-induced mouse asthma model,thereby aggravating the airway inflammatory response and further aggravating asthma.