Ubiquitin Reduces Expression of Intercellular Adhesion Molecules and Tumor Necrosis Factor-α in Lung Tissue of Experimental Acute Lung Injury

Background: Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are two important cytokines in inflammatory response, which may induce rolling and adhesion of both leukocytes and lymphocytes, while modulating vascular permeability at the same time. These adhesion molecules usually serve as surrogate markers of activation and injury of vascular endothelial cells. Tumor necrosis factor-α (TNF-α) is a key factor to induce the expression and production of the above cell adhesion molecules. However, it remains to be elucidated whether exogenous ubiquitin exerts any effect on the cytokines in sepsis-induced ALI. Methods: Sixty mice were divided randomly into five groups with twelve mice in each group, i.e. CLP group, SHAM group, UB1 group (10 mg/kg), UB2 group (5 mg/kg) and UB3 group (1 mg/kg). Mice of SHAM group underwent sham operation, and other four groups underwent CLP. Six hours after surgery, mice of three UB groups received ubiquitin by caudal vein injection while CLP and SHAM group received vehicle. Seven hours after surgery, blood and lungs of all mice were collected. ICAM-1, VCAM-1 and TNF-α level of 9% lung homogenate and serum TNF-α level were measured by ELISA. Results: Pulmonary ICAM-1, VCAM-1 and TNF-α level of three UB groups were lower than CLP and SHAM group, and there were several comparisons with a statistically significant difference. Serum TNF-α level of three UB groups were slightly lower than CLP group, but far higher than SHAM group. Pulmonary ICAM-1 level, VCAM-1 level and serum TNF-α level of UB3 group were lower than UB1 and UB2 group, and there was a significant difference in VCAM-1 between UB3 and UB1 group. Pulmonary TNF-α level of UB3 group was slightly higher than UB1 and UB2 group.