Expressions of MK2, HuR, and ICAM-1 in the pulmonary microvascular endothelial cells of the mouse with acute respiratory distress syndrome / 医学研究生学报

ABSTRACT

Objective Intercellular adhesion molecule-1 (ICAM-1) plays an important role in mediating pulmonary infiltration of neutrophils .The aim of the study was to observe the expression of ICAM-1 and its potential regulators MK 2/HuR in pulmonary micro-vascular endothelial cells ( PMVEC ) in mice with acute respiratory distress syndrome ( ARDS) induced by lipopolysaccharide ( LPS) . Methods Ten 6-8 weeks old healthy C57BL/6 mice were randomly divided into an LPS and a control group of equal number , the former injected intraperitoneally with LPS diluted in 100 μL PBS while the latter with PBS only , both at 5 mg per kg of the body weight .At 24 hours after injection , all the mice were sacrificed .Real-time PCR was used to determine the mRNA expressions of HuR and ICAM-1 in the PMVECs, Western bolt employed to detect the protein expressions of MK2, HuR and ICAM-1, and flow cytometry adopted to measure the ICAM-1 expression on the surface of the PMVECs and pulmonary infiltration of neutrophils . Results The W/D ratio in the lung tissue of the mice was significantly lower in the LPS than in the control group (3.61 ±0.28 vs 6.16 ±0.40, P<0.05), while the rate of neutrophil infiltration markedly higher in the former than in the latter ([13.92 ±3.23]%vs [3.24 ±1.24]%, P<0.05).The mRNA and protein expressions of ICAM-1 in the PMVECs were significantly elevated in the LPS group as compared with that in the control (P<0.05), and so was the mRNA expression of HuR (P<0.05).No remarkable changes were observed in the expressions of total MK 2 and HuR proteins, but phosphorylated MK2 (p-MK2) and cytoplasmic HuR were increased in the LPS-stimulated mice. Conclusion Specific blockage or reduction of the HuR expression in PMVECs may lower the expression of ICAM-1, reduce neutrophil infiltration , and lessen pathophysiological changes in mice with ARDS .