The Effect Of HMGB1/TLR4 Signaling Pathway On MAL Expression In Asthmatic Rats

Objectives:To observe the expression of HMGB1/TLR4 signaling pathway in lung tissue of asthmatic rats and its influence on the expression of MAL.Methods:According to the principle of randomization,the 15 healthy male SD rats（weighing 240±10）g were divided into 3 groups（n=5 per group）:normal group,asthma group and inhibitor group（TLR4 inhibitors,TAK242）.Asthmatic group and inhibitor group were given OVA mixture1ml/only（Albumin+aluminum hydroxide,OVA+AL（OH）₃）sensitization and 1%OVA multiple aerosol stimulation to produce asthma model,while the inhibitor group was given TAK-242（1mg/Kg）intraperitoneal injection.Normal group sensitization and atomization were treated with the same amount of saline.Rats were sacrificed 24h after the last aerosolization.HE staining and pathology image analysis were performed on lung tissue.Immunohistochemistry was used to detect the level of MAL,TLR4 and HMGB1 in lung tissue.Using qRT-PCR to detected the expression of MALmRNA,TLR4mRNA and HMGB1mRNA in lung tissue.Results:1.HE staining showed that there were no airway inflam matory changes in the lung tissue of normal rats.The bronchiallum en was intact and no wall thickening,occasionally a small amount of inflammatory cells,around the airways no significant inflammator y cell infiltration;Asthmatic rats visible irregular bronchial lumen st enosis,thickening of the basement membrane and airway smooth m uscle,epithelial hyperplasia,increased mucus secretion and bronchial seen around a large number of inflammatory cell infiltration;Comp ared with the asthma group,inhibitor group bronchoalveolar lavage was decreased and inflammatory cell infiltration decreased.2.Immunohistochemistry showed that MAL protein expression was significantly reduced in the asthma group than the normal group,th e difference was significant（P<0.05）,The expression of MAL in th e inhibitor group was higher than that in the asthma group,but it was lower than that in the normal group,there was significant differ ence compared with asthma group and normal group（P<0.05）;The e xpression of HMGB1 in the asthma group was significantly higher than that in the normal group and the inhibitor group（P<0.05）,and the expression of HMGB1 in the inhibitor group was significantly l ower than that normal group（P<0.05）,The lowest expression was f ound in the normal group;TLR4 expression was still higher in asth ma group than that in the normal group and the inhibitor group（P<0.05）.The expression of TLR4 in inhibitor group was no significantl y than that normal group（P 0.05）.In the normal group,the expre ssion was the lowest.3.q RT-PCR showed the relative expression levels of MALm RNA sequence of the normal group>inhibitor group>asthma group.There was significant difference in the normal compare with asthma group and inhibitor group（P<0.05）,the inhibitor group has significant diff erence compared with asthma group（P<0.05）;The relative expressio n levels of HMGB1m RNA sequence of the asthma group>inhibitor group>in normal group.There was significant difference in the ast hma group compare with normal group and inhibitor group（P<0.05）,inhibitor group has significant difference compared with normal gro up（P<0.05）;The relative expression levels of TLR4mRNA sequenc e of the asthma group>inhibitor group>in normal group.There w as significant difference in the asthma compare with normal group andinhibitor group（P<0.05）,no significant differences were found between TLR4mRNA in normal group and inhibitor group（P>0.05）.Conclusion:1.HMGB1/TLR4 pathway and MAL is involved in the development of asthma;2.The expression of MAL was correlated with HMGB1/TLR4 pathway.