Objective:To detect the expression of micro RNA-21 in lipopolysaccharide（LPS） induced injured models of mouse RAW264.7 macrophages and the influence of Ulinastatin（UTI）on the expression of mi R-21. Methods:The growth status of RAW264.7cells was observed in the normal group

the model group（LPS）

the experimental group（LPS + UTI） and the negative control group（drug-non-stimulation group）. Methyl thiazolyl tetrazolium（MTT）assay was used to determine the effect of different concentration of UTI on the activity of RAW264.7 cells. After pre-treatment with different concentrations of UTI for 2 h

the expressions of TNF-αm RNA

IL-6 m RNA and mi R-21 were detected by RT-PCR in RAW264.7 cells induced by LPS. Results:（1）The toxic effects of UTI on RAW264.7 cell:it was non-toxic of UTI on RAW264.7 cells while the concentrations were less than 1 000 U/m L;there was no statistically significant difference（P=0.117）.（2）After RAW264.7cells being treated by LPS with different concentrations（100

250

500 ng/m L）

the expressions of mi R-21（1.000 ±0.000

1.082±0.114

1.671±0.087

2.789±0.107）and TNF-α and IL-6（1.311±0.037

1.549±0.039

1.667±0.059;1.167±0.019

1.518±0.058

1.740±0.071）were up-regulated respectively in a dose-dependent manner（P1=0.000

P2=0.000

P3=0.000）.（3）And the effect could be attenuated by UTI in different concentrations（10

100

1 000 U/m L）（mi R-21:1.000±0.000

2.789±0.107

2.675±0.135

2.258±0.170

1.369±0.279

P=0.000;TNF-α:1.000±0.000

1.998±0.212

1.421±0.100

1.122±0.154

0.991±0.139

P=0.000;IL-6:1.000±0.000

1.880±0.045

1.179±0.108

1.053±0.070

0.960±0.088

P=0.000）. Conclusion:The expression of mi R-21 is significantly changed after LPS stimulating RAW264.7macrophages

indicated that it is related to the degree of inflammation. UTI could down-regulate the mi R-21-related signaling pathway to play a protective role in immune and inflammatory response.