脓毒症大鼠肺组织抑制因子-1表达变化

摘要

目的 研究脓毒症大鼠肺组织中组织抑制因子-1(TIMP-1)的表达变化及其在脓毒症导致的肺损伤中的意义.方法 实验在三峡大学医学院实验中心完成.雄性SD大鼠40只,随机(随机数字法)分为假手术(Sham)组(8只)和模型组(32只),模型组分6h、12 h、24 h、48 h4个时相组,每组8只.脓毒症模型制备采用盲肠结扎穿孔法(CLP).造模后在不同时相取血、处死并摘取肺组织.用光镜观察肺组织结构变化.用RT-PCR法检测TIMP-1 mRNA在不同时相肺组织中的表达,并同时检测凋亡因子Bax及凋亡抑制因子Bcl-2 mRNA的表达,采用免疫组织化学法以CD18标记不同时相肺组织中的炎症细胞并计数.计量资料以均数±标准差((x)±s)表示,组间比较采用t检验.结果 与Sham组相比,CLP后各时相肺组织均有不同程度的损伤；CLP后各时相肺组织中TIMP-1 mRNA表达量均显著升高(P＜0.01),其峰值见于CLP后24h (P＜0.01)；CLP后12 ～48 h Bax mRNA表达量降低(P＜0.05),CLP后48 h最低(P＜0.01)；CLP后Bcl-2 mRNA表达量无明显改变.免疫组化染色表明CLP后各时相肺组织中CD18阳性细胞数均显著高于Sham组(P＜0.01),24 h达高峰(P＜0.01),且与TIMP-1 mRNA的表达量差异具有统计学意义,相关系数r0.426 (P＜0.01).结论 TIMP-1与脓毒症所导致的肺损伤关系密切,其机制可能是抑制了炎症细胞的凋亡,持续的炎症反应造成组织损伤,最终导致器官功能障碍.%Objective To investigate the expression and the effects of tissue inhibitor of metalloproteinases-1 (TIMP-1) on lungs of rats with sepsis.Methods Forty Sprague-Dawley (SD) rats were randomly divided into two groups,namely sham group (n =8) and sepsis model group (n =32).The rats of model group were modeled by cecal ligation and puncture (CLP),and were further divided into four subgroups as per the time after modeling,namely 6 h (n =8),12 h (n =8),24 h (n =8),48 h (n =8)subgroups.Blood and lung samples were taken 6 h,12 h,24 h and 48 h after modeling.The histological changes in lungs of the rats were observed under light microscope.Expressions of TIMP-1 mRNA,Bax mRNA and Bcl-2 mRNA in lungs were measured by RT-PCR.The immunohistochemistry was used to label the CD18 in lungs during different phases of sepsis.The data were processed by t test.Results Compared with sham group,the lung tissues of rats in model group were injured to a certain extent after CLP.The expression of TIMP-1 mRNA and the number of CD18 positive cells increased at the same time (P ＜ 0.01),and peaked 24 hours later (P ＜ 0.01).While the expression of Bax mRNA in model group decreased markedly 12-48 hours after modeling (P ＜ 0.01-0.05),and reached minimum 48 hours later (P ＜ 0.01).The expression of Bcl-2 mRNA in model group changed unnoticeable.The positive correlation between variations in number of CD18 positive cells and expression of TIMP-1 mRNA was found in model group (r =0.426,P ＜ 0.01).Conclusions The increase in expression of TIMP-1 mRNA in lungs is closely associated with the lung injury of sepsis.The mechanism of lung injury is likely attributed to the preservation of inflammatory cells from apoptosis,and the persistent inflammation response causes tissue damage,leading to organ dysfunction.