Abstract
The vascular endothelium can be activated by multiple factors, including lipopolysaccharide (LPS) functioning as a key component of the inflammatory response. Activated endothelium promotes the recruitment of leukocytes mainly by releasing various adhesion molecules and amplifies inflammation via a feedback loop. Peoniflorin, the main active constituent of the roots of Paeonia lactiora Pall., possesses anti‐inammatory, anti‐infective, and anti‐platelet aggregative properties. To elucidate the anti‐inammatory mechanism of peoniflorin, the present study was conducted to address its effects on the adhesion of inflammatory endothelial cells to leukocytes. Peoniflorin substantially reduced adhesion of either human acute monocytic leukemia cells (THP‐1) or human acute promyelocytic leukemia cells (HL‐60) to LPS‐stimulated human umbilical vein endothelial cells (HUVECs). It also markedly down‐regulated the expression of E‐selectin at both the gene and protein levels. However, peoniflorin only slightly reduced expression of intercellular adhesion molecule‐1 (ICAM‐1). Signal pathway analysis indicated that peoniflorin reduced phosphorylation of c‐Jun NH~2~‐terminal kinase (JNK) and p38 kinase, as well as the phosphorylation and degradation of IκB‐α in HUVECs. These findings suggest that prevention of the adhesion between inflammatory endothelial cells and leukocytes contributes, at least partially, to the anti‐inflammation action of peoniflorin. The anti‐adhesion mechanisms of peoniflorin were involved in the down‐regulation of the activation of mitogen‐activated protein kinases (MAPKs) and nuclear factor‐kappa B (NF‐κB), and a reduction of adhesion molecule expressions in endothelial cells. Drug Dev Res 2010.© 2010 Wiley‐Liss, Inc.