Hemorrhage and resuscitation alter the expression of ICAM-1 and P-selectin in mice

Acute inflammatory lung injury is a common clinical occurrence following blood loss and trauma, and is characterized by massive neutrophil infiltration into the lung. In order to better examine cell trafficking that may contribute to lung injury in this setting, we investigated in vivo mRNA levels and immunohistochemically determined expression of the adhesion molecules P-selectin and the intercellular adhesion molecule (ICAM)-1 in murine lungs over the 3-day period following hemorrhage and resuscitation. Significant increases in P-selectin mRNA levels were present in lungs obtained 3 days after hemorrhage. ICAM-1 mRNA levels were significantly increased 6 and 72 hr after hemorrhage. Immunohistochemical staining for P-selectin was enhanced on pulmonary vascular endothelium in all visible vessels at 6, 24, and 72 hr after hemorrhage. ICAM-1 immunoreactivity was significantly increased on the alveolar epithelium at 6 and 72 hr post-hemorrhage. These results suggest that increased expression of adhesion molecules in the lung at early post-hemorrhage timepoints may contribute to neutrophil infiltration into the lungs and the frequent development of acute lung injury following blood loss and trauma.