The Impact And Mechanism Of Metformin Gavage On Airway Remodelng In Mice With Asthma

Objective: To observe the impact of metformin on airway remodeling in mice model with chronic asthma.Methods: Thirty female C57BL/6 mice were divided into three groups randomly and named control group,model group,metformin group.10 mice randomly arranged in each group.mice in model group and metformin group were sensitized by i.p.(intraperitoneal)injections with 100 ug OVA(ovalbumin)and 2mg AL(OH)3(aluminium hydroxide)on day 0,7 and 14.mice in control group were injected with equal NS at thesame time.From day 21 to day 60,mice in model group and metformin group were challenged by intranasal administration with 50 ug OVA three times a week.while mice in control group were challenged with equal NS at the same frequency.Since 21 st day,mice in metformin group were given metformin according to 300mg/kg/day by gavage administration.while mice in model group and control group were gavaged with equal NS.After the last challenge,blood in all mice were collected through ophthalmectomy.The level of TGF-?1,MMP-9 and TIMP-1 in serum were measured by ELISA.After ophthalmectomy,all mice were killed by pulling apart cervical vertebra.Then,inferior lobes of left lung were collected and were put into 4% paraformaldehyde.Through masson staining,collagen deposited under the basement membrance,bronchus wall and smooth musle cell thickness were measured by Image-Pro Plus 6.0.Right lungs in all mice were collected and were put into 4% paraformaldehyde.After then,RT-PCR were used to measure the level of MMP-9 and TIMP-1 in lung tisuues.Results:1.Clinical manifestations observationMice in model group were inappetence and in low spirits.moreover,mess fur,weight reduction and accidie were observed.After challenged,Obvious dysphoria,high respiratory rates,sternutation,purple lips and chemosis were observed.Sometims,gatism were also observed by uswhen they sneezing.Mice in control group were good spirit and appetite,weight increased.We observed mice bucking after challenged.but obvious dysphoria,high respiratory rates,sternutation,purple lips,chemosis and gatism were not observed in control group.In metformin group,dysphoria,high respiratory rates,sternutation,purple lips and chemosis were observed.Clinical manifestations were remission in metformin group when compared with model group.2.Metformin alleviated mice pathological change in bronchial asthmaThickening in bronchus wall,airway mucous epithelium incrassation,mucus exudation in airway and alveoli damaged were observed in model group compared with metformin group.while above changes were remission in metformin group.Structures of bronchus and alveoli were relatively intact in control group.3.Metformin alleviated mice collagen deposited under the basement membrance,bronchus wall and smooth musle cell thickness in bronchial asthmaCompared with control group,collagen deposited under the basement membrance,bronchus wall and smooth musle cell thickness were increased in model group and metformin group(p<0.01).Collagen deposited under the basement membrance,bronchus wall and smooth musle cell thickness were decreased in metformin group(p<0.01)when compared with model group.4.Metformin down-regulated the level of TGF-?1,MMP-9 and TIMP-1 in serum of bronchial asthma mice Compared with control group,the level of TGF-?1,MMP-9 and TIMP-1 in serum were increased in model group and metformin group(p<0.05).Futhermore.compared with model group,the level of TGF-?1,MMP-9 and TIMP-1 in serum were decreased in metformin group(p<0.05).5.Metformin down-regulated the expression of MMP-9m RNA,TIMP-1m RNA in lung tissues of bronchial asthma mice Compared with controlgroup,the expression of MMP-9m RNA,TIMP-1m RNA in lung tissueswere increased in model group and metformin group(p<0.05).Comparedwith model group,the expression of MMP-9m RNA,TIMP-1m RNA inlung tissues were decreased in metformin group(p<0.05).Conclusion:1.OVA can induce asthma model,cause the high level of TGF-?1,MMP-9 and TIMP-1 in serum and high expression of MMP-9m RNA,TIMP-1mRNA in lung tissues2.Metformin can down-regulate the level of TGF-?1,MMP-9 and TIMP-1 in serum and the expression of MMP-9m RNA,TIMP-1m RNA in lung tissues.And then,reduce the degree of airway remodeling in bronchial asthma mice.