Figure 1.

Increased inflammation in Lp(a) (lipoprotein(a))-vs endothelial cells (ECs) facilitates excessive monocyte transmigration. A, Representative differential interference contrast images of transendothelial migration (TEM) in unstimulated ECs (left) compared with Lp(a)-stimulated ECs [Lp(a)-EC] for 18 h. Transmigrated monocytes are visualized as black cells with a red asterisk and adhered monocytes as white cells. White bar=200 μm. B, Quantification of adhered (n=6; P=0.0466) and (C) transmigrated monocytes (n=6; P=0.0014). Data were analyzed using 2-tailed Student unpaired t test. D, Heat map of selected genes involved in TEM and leukocyte chemotaxis of 5 mg/dL Lp(a)-EC compared with 100 mg/dL Lp(a)-EC (6 h stimulation; n=4). E, Schematic overview of the key steps and molecules involved in leukocyte TEM. F, Genes important in rolling and tethering of leukocytes are upregulated in Lp(a)-ECs relative to unstimulated ECs. Data were analyzed using 2-tailed Student unpaired t test (6 h stimulation; n=5; P=0.0253 for E-selectin; P=0.0008 for ICAM1; P=0.0333 for VCAM1). G, Chemotactic gene expression is elevated in Lp(a)-ECs compared with unstimulated ECs. Data were analyzed using 2-tailed Student unpaired t test (6 h stimulation; n=3 for IL6 and rest is n=5; P=0.0030 for MCP1; P=0.0025 for IL6; P=0.0368 for IL8). H, IL (interleukin)-6 and IL-8 cytokine secretion in cell medium increased in Lp(a)-ECs (n=4) vs unstimulated ECs (n=6). Data were analyzed using 2-tailed Student unpaired t test (P<0.0001 for IL-6; P<0.0001 for IL-8; 18 h stimulation). I, Representative immunoblot revealing increased EC ICAM (intercellular adhesion molecule)-1 protein expression after incubation with 100 mg/dL Lp(a) compared with unstimulated ECs (18 h stimulation). All data are mean±SEM. MCP-1 indicates monocyte chemoattractant protein 1; and VCAM-1, vascular adhesion molecule 1. *P<0.05, **P<0.005, ***P<0.0005, ****P<0.00005.