Using degenerate polymerase chain reaction, we isolated a cDNA encoding a novel 493-amino acid protein from human and mouse adult heart cDNAs and have designated it angiopoietin-related protein-2 (ARP2). The NH 2 -terminal and COOH-terminal portions of ARP2 contain the characteristic coiled-coil domain and fibrinogen-like domain that are conserved in angiopoietins. ARP2 has two consensus glycosylation sites and a highly hydrophobic region at the NH 2 terminus that is typical of a secretory signal sequence. Recombinant ARP2 expressed in COS cells is secreted and glycosylated. In human adult tissues, ARP2 mRNA is most abundant in heart, small intestine, spleen, and stomach. In rat embryos, ARP2 mRNA is most abundant in the blood vessels and skeletal muscles. Endothelial and vascular smooth muscle cells also contain ARP2 mRNA. Recombinant ARP2 protein induces sprouting in vascular endothelial cells but does not bind to the Tie1 or Tie2 receptor. These results suggest that ARP2 may exert a function on endothelial cells through autocrine or paracrine action.

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Abstract-Fractalkine is a unique chemokine that functions as a chemoattractant as well as an adhesion molecule on endothelial cells activated by proinflammatory cytokines. Alpha-lipoic acid (LA), a naturally occurring dithiol compound, is an essential cofactor for mitochondrial bioenergetic enzymes. LA improves glycemic control, reduces diabetic polyneuropathies, and mitigates toxicity associated with heavy metal poisoning. The effects of LA on processes associated with sepsis, however, are unknown. We evaluated the antiinflammatory effect of LA on fractalkine expression in a lipopolysaccharide-induced endotoxemia model. Tumor necrosis factor-␣ (TNF-␣) and interleukin-1␤ (IL-1␤) significantly induced fractalkine mRNA and protein expression in endothelial cells. LA strongly suppressed TNF-␣-or IL-1␤-induced fractalkine expression in endothelial cells by suppressing the activities of nuclear factor-B and specificity protein-1. LA also decreased TNF-␣-or IL-1␤-stimulated monocyte adhesion to human umbilical vein endothelial cells. As shown by immunohistochemistry, fractalkine protein expression was markedly increased by treatment with lipopolysaccharide in arterial endothelial cells, endocardium, and endothelium of intestinal villi. LA suppressed lipopolysaccharide-induced fractalkine protein expression and infiltration of endothelin 1-positive cells into the heart and intestine in vivo. LA protected against lipopolysaccharide-induced myocardial dysfunction and improved survival in lipopolysaccharide-induced endotoxemia. These results suggest that LA could be an effective agent to reduce fractalkine-mediated inflammatory processes in endotoxemia. Key Words: ␣-lipoic acid Ⅲ fractalkine Ⅲ endothelial cells Ⅲ inflammation S epsis is a clinical syndrome that represents the systemic response to an infection and is characterized by systemic inflammation and widespread tissue injury. At the site of injury, the endothelium expresses various adhesion molecules that attract leukocytes. 1 At the same time, inflammatory cells are activated and express a variety of adhesion molecules that cause the aggregation and margination of these cells to the vascular endothelium. 2 When the inflammatory response is initiated, a wide variety of chemical mediators are released into circulation. These chemical mediators, including tumor necrosis factor-␣ (TNF-␣) and interleukin-1␤ (IL-1␤), are associated with the continuation of the inflammatory response. 3 Sepsis is caused mainly by an exaggerated systemic response to endotoxemia induced by gram-negative bacteria and their characteristic cell wall component, lipopolysaccharide (LPS). 4 In mice, challenge with high doses of LPS results in a syndrome resembling septic shock in humans. 5 Fractalkine (CX3CL1) is a structurally novel protein in which a soluble chemokine-like domain is fused to a mucin stalk that extends into the cytoplasm across the cell membrane. 6 Fractalkine is expressed in activated endothelial cells, and its expression is upregulated by TNF-␣, IL-1␤, and LPS. 7,8 As a full-...

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