Pretreatment of Human Polymorphonuclear Leukocytes (PMN) with a New Carbon Monoxide (CO)‐Releasing Molecule (CORM401) Inhibits PMN Migration across Vascular Endothelial Cells

Background We have demonstrated that carbon monoxide (CO)‐releasing molecules (CORMs) reduce septic inflammation by interfering with PMN recruitment to the inflamed organs. In this study, we assessed the effects/mechanisms of a newly synthesized Mn 2+ ‐based water‐soluble CORM (CORM401) on PMN adhesion(A)/transendothelial migration(TM) in an experimental model of endotoxemia in vitro. Methods Human umbilical vein endothelial cells (HUVEC) grown on parallel flow channels were stimulated with LPS (1μg/ml; 6 hrs) and interacted with freshly isolated PMN (pretreated for 30 min with CORM401 or its inactive compound, iCORM401; 100μM) for 5 min in the presence of 1.0 dyn/cm 2 shear stress. Subsequently, HUVEC:PMN co‐cultures were additionally perfused for 20 min with medium containing CORM/iCORM401. Video and confocal microscopy were used to analyze PMN A/TM. Results Stimulation of HUVEC with LPS significantly increased PMN A (0.6+/‐0.1 vs 30.9+/‐7.6 cells/mm 2 ; p<0.05) and TM (0.0 vs 41.7+/‐6.8%; p<0.001). Pretreatment of PMN with CORM401 had no effect on PMN A, however significantly reduced PMN TM (41.7+/‐6.8% vs 15.2+/‐4.3; p<0.01). The above findings were confirmed employing confocal microscopy. Conclusion CORM401 interferes with PMN recruitment by specific suppression of PMN migratory potential. (HSFO 393, IRF‐25‐12).