Expression of tissue inhibitor of metalloproteinases-1 on lungs of rats with sepsis

Abstract

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. Key words: Tissue inhibitor of metalloproteinases-1 ; Sepsis ; Lung tissue ; Acute respiratory distress syndrome; Histological changes ; Cecal ligation and puncture ; Leucocyte ; Rat