Antithrombin-Ⅲ without concomitant heparin improves endotoxin-induced acute lung injury rats by inhibiting the activation of mitogen-activated protein kinase

Background Antithrombin-Ⅲ （AT-Ⅲ）, the major inhibitor of thrombin in plasma, also has anti-inflammation property and might have positive effect on sepsis. The present study aimed to investigate the effects of AT-Ⅲ on inflammatory reaction and pulmonary protection in endotoxin-induced acute lung injury （ALI） rat. Methods Sixty male Sprague-Dawley rats were randomly assigned equally to normal control group, ALl group, AT-Ⅲ treatment group, AT-Ⅲ＋heparin treatment group, and heparin treatment group. The pulmonary vascular permeability index （PVPI） was measured by single nuclide tracer technique. The activity of AT-Ⅲ in plasma was determined by the method of synthetic chromogenic substrata. Tumor necrosis factor-a （TNF-a） and interleukin-6 （IL-6） levels in serum were determined by enzyme-linked immunosorbent assay. The expressions of lung tissue mitogen-activated protein kinases （ERK1/2, P38 and JNK MAPK） were determined by Western blotting. Results Rats had significantly improved lung histopathology in the AT-Ⅲ treatment group and heparin treatment group compared with the ALl group, The PVPI of the ALl group was 0.38±0.04, significantly higher than that of the normal control group （0.20±0.02, P 〈0.01）, AT-Ⅲ treatment group （0.30±0.04, P 〈0.01） and heparin treatment group （0.28±0.04, P 〈0.01） respectively. There were no significant differences of PVPI in the ALl group and AT-Ⅲ＋heparin treatment group. The activity of AT-Ⅲ in plasma in the ALl group was （76±8）%, significantly lower than that of the normal control group （（96±11）%, P 〈0.05） and AT-Ⅲ treatment group （（105±17）%, P 〈0.05） respectively. The serum levels of TNF-α and I L-6 of the ALl group were （2.770±0.373） μg/L and （1.615±0.128） ng/ml respectively, significantly higher than those of the normal control group （0.506±0.093） μg/L and （0.233±0.047） ng/ml respectively, all P 〈0.01）, AT-Ⅲ treatment group （（1.774±0.218） pg/L and （1.140±0145） ng/ml respectively, all P 〈0.01） and heparin treatment group （（1.924±0.349） μg/L and （1.223±0.127） ng/ml respectively, all P 〈0.01）. The lung tissue levels of phospho-ERK1/2 and phospho-P38 MAPK expressions were markedly higher in the ALl group than in the normal control group, AT-Ⅲ treatment group and heparin treatment group respectively. Conclusions AT-Ⅲ without concomitant heparin inhibited the activation of ERK1/2 and P38 MAPK, down-regulated the levels of downstream cytokines TNF-a and IL-6, relieved endothelial permeability, and improved the ALl in endotoxin-induce