Figure 5.

Low-density lipoprotein receptor–related protein 8 (LRP8) plays a role in the human neutrophil peptide (HNP)–induced platelet activation and leukocyte rolling. A, Surface expression of CD62P in human platelet-rich plasma (PRP) after stimulation with vehicle control (V) or HNPs (10 μg/mL) in the presence or absence of recombinant human LRP8 (rhLRP8) (n=7 experiments). B, Surface expression of CD62P in murine PRP isolated from wild-type (WT) or LRP8^−/− mice after incubation with HNPs (1 or 10 μg/mL) or thrombin (5 U/mL) (n=7 experiments). C, Representative images of platelet aggregation under fluorescence intravital microscope in WT and LRP8^−/− mice 4 hours after intravenous injection of HNPs. Low-dose FeCl₃ was topically dropped on carotid artery to stimulate platelet aggregation. D, Mean values of fluorescent density of platelets deposited on the vessel wall 5 minutes after FeCl₃. E, Time required reaching maximal vessel occlusion after FeCl₃ stimulation in mice treated with HNPs. F, Platelet LRP8 is not required for increasing leukocyte rolling. Platelets were depleted by intraperitoneal injection of rat anti-mouse CD41 monoclonal antibody (2 μg per mouse) in WT and LRP8^−/− mice 24 hours before intravenous injection of HNPs. Leukocyte rolling in carotid artery was monitored by intravital microscopy 4 hours after receiving HNPs. G, Expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in response to HNP stimulation (10 μg/mL) for 4 hours by primary endothelial cells isolated from WT and LRP8^−/− mice (n=5). H, Expression of CD11b in response to HNP stimulation (10 μg/mL) for 1 hour by primary monocytes isolated from bone marrow of WT and LRP8^−/− mice (n=5). *P<0.05 vs WT under identical conditions, †P<0.05 vs unstained, ‡P<0.05 vs stained.