Attenuation of Leukocytes Sequestration by Carbon Monoxide-Releasing Molecules: Liberated Carbon Monoxide in the Liver of Thermally Injured Mice

Abstract

We sought to determine whether the CO-releasing molecules, ie, liberated CO, attenuates the leukocytes sequestration in the liver of thermally injured mice. Sixty-five mice were assigned to five groups in three respective experiments. In each experiment, mice in sham group (n = 7) and sham + CORM-2 group (n = 7) were underwent sham thermal injury, whereas mice in burn group (n = 7) received 15% TBSA full-thickness thermal injury, mice in burn + CORM-2 group (n = 7) underwent the same thermal injury with the immediate administration of CORM-2 (8 mg/kg intravenously), and mice in burn + DMSO group (n = 7) underwent the same thermal injury with an immediate 160 microl-bolus injection of 0.5% dimethyl sulfoxide/saline. Polymorphonuclear leucocyte (PMN) accumulation (assessed by the myeloperoxidase assay) was assessed in mice liver. Activation of nuclear factor kappa B (NF-kappaB) and the expression levels of ICAM-1 and VCAM-1 in liver were assessed. In an in vitro experiment, sinusoidal endothelial cells (SECs) isolated from the liver of normal mice were stimulated by experimental mice serum (50% v/v) for 4 hours. Subsequently, the adhesion of PMNs to SECs was assessed. In addition, the number and states (rolling or stationary) of leukocytes in liver were observed by intravital microscopy. Treatment of thermally injured mice with CORM-2 attenuated PMN accumulation and prevented activation of NF-kappaB in the liver, which was accompanied by a decrease of the expression of ICAM-1 and VCAM-1. In parallel, PMNs adhesion to SECs stimulated by CORM-2-treated thermally injured mice serum was markedly decreased. Intravital microscopy showed that the stationary leukocytes in thermally injured mice liver were significantly reduced by treatment of CORM-2. CORM-released CO attenuates leukocytes sequestration in the liver of burn mice by interfering with NF-kappaB activation, protein expression of ICAM-1 and VCAM-1, and therefore suppressing endothelial cells proadhesive phenotype.