Urinary trypsin inhibitor attenuates lipopolysaccharide-induced acute lung injury by blocking the activation of p38 mitogen-activated protein kinase

Objective

To investigate the protective effect of urinary trypsin inhibitor (UTI) in a rat model of lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the underlying molecular mechanism.

Methods

Rats were randomly assigned into three groups: control group, LPS treatment group and LPS/UTI treatment group. The serum concentrations of tumor necrosis factor (TNF)-?? and interleukin (IL)-10 were measured by ELISA. The expression of p38 mitogen-activated protein kinase (MAPK) in lung tissues was determined by Western blot analysis.

Results

Administration of UTI reduced the lung wet/dry weight ratio and ameliorated the tissue damage. In the LPS/UTI treatment group, levels of TNF-?? were significantly lower than those in the LPS treatment group, while the levels of IL-10 were significantly higher than those in the LPS treatment group. Western blot analysis revealed that UTI inhibited the phosphorylation of p38 MAPK in lung tissues.

Conclusions

UTI attenuates LPS-induced ALI, probably by adjusting the balance between proinflammatory and anti-inflammatory cytokines. The mechanism responsible for the decreased TNF-?? expression may be related to the inhibitory effect of UTI on p38 MAPK activation.