抑制活化素受体样激酶5对急性肺损伤后细胞外基质代谢的影响

Inhibition of activin receptor like kinase 5 activation affects extracellular matrix metabolism after acute lung injury

目的研究TGF-β/Smads信号转导通路对急性肺损伤后细胞外基质代谢的影响,以了解该信号转导通路在肺纤维化发生过程中的调控作用。方法用SB431542抑制活化素受体样激酶5(ALK5)来抑制TGF-β/Smads通路。24只雄性SD大鼠,随机分为对照组、烧伤组、早期处理组、后期处理组,每组6只。对照组施行假烫,其他3组大鼠造成30%TBSAⅢ度烧伤。早期处理组分别于烧伤后、1×24 h、2×24 h后腹腔注射SB431542,而后期处理组分别于3×24 h、4×24 h、5×24 h后腹腔注射SB431542,28 d后取肺组织,采用real-ti me PCR法检测MMP-2、MMP-9和TI MP-1 mRNA转录水平;用羟脯氨酸测试盒测定羟脯氨酸含量;并行肺脏病理学检查及评分。统计学处理采用SPSS13.0软件进行单因素方差分析判断组间差异,P<0.05为差异有统计学意义。结果抑制ALK5降低了MMP-2 mRNA转录水平,而早期抑制的效应更为明显;与急性期后抑制相比,早期抑制ALK5降低了MMP-9 mRNA转录水平,不利于胶原的降解;病理学观察见急性期后抑制ALK5将减轻肺纤维化程度。结论在肺部炎症反应的急性期过后抑制ALK5有利于胶原的降解,将减轻肺纤维化程度,而过早抑制ALK5将会加重肺纤维化程度。

Objective To investigate the potential roles of Smads signal transduction pathway in pulmonary fibrosis formation by investigating the extracellular matrix metabolism changes after acute lung injury.Methods Twenty-four SD rats were randomly divided into group of control,burn,SB431542 early treatment and SB431542 later treatment with 6 rats for each.Rats other than in the control group were burnt to prepare for third degree of 30% of total body surface area（TBSA）except for ones of group control.Rats of early treatment group were treated with SB431542 immediately,at 1×24 h and 2×24 h after the burn respectively.Rats of later treatment group were treated with SB431542 at 3×24 h,4×24 h and 5×24 h after the burn respectively.The mRNA expression of MMP-2,MMP-9 and TIMP-1 of lung tissues were tested by real time PCR.Hydroxyproline Kit was used to determine hydroxyproline content in lungs.Lung specimens were also double-blind examined and evaluated for Szapiel′s pathological scores.Results Inhibition of activin receptor like kinase 5（ALK-5） reduced MMP-2 mRNA,and the effect of early treatment group was more obvious.The early inhibiton of ALK5 reduced MMP-9 mRNA and was not conducive to the degradation of collagen.Pathological changes suggested that later inhibition would reduce fibrosis.Conclusion Late inhibition of ALK5 is conducive to the degradation of collagen and reduce pulmonary fibrosis.The early inhibition of ALK5 will increase the degree of pulmonary fibrosis.