Submitted on March 9, 2009
Revised on May 7, 2009
Accepted on June 2, 2009
Vascular Cell Adhesion Molecule-1 Expression in Human Intestinal Microvascular Endothelial Cells is Regulated by PI3K/Akt/MAPK/NF
B: Inhibitory Role of Curcumin
David G Binion1, Jan Heidemann2, Mona S Li, Victoria M. Nelson, Mary F Otterson3, and Parvaneh Rafiee3*
1 Froedtert Memorial Luthern Hospital
2 University of Mnster
3 Medical College of Wisconsin
* To whom correspondence should be addressed. E-mail: prafiee{at}mcw.edu.
Endothelial activation and surface expression of cell adhesion molecules (CAMs) is critical for binding and recruitment of circulating leukocytes into tissues during the inflammatory response. Endothelial CAM expression plays a critical role in the intestinal microvasculature in inflammatory bowel disease (IBD), as blockade of leukocyte alpha4 integrin binding by gut endothelial CAM ligands has therapeutic benefit in IBD. Mechanisms underlying expression of VCAM-1, a ligand for alpha4 integrin in primary cultures of human intestinal microvascular endothelial cells (HIMEC) has not been defined. We investigated the effect of curcumin, PI3K/Akt and MAPK inhibitors on VCAM-1 expression and function in HIMEC. CAM expression was assessed and HIMEC- leukocyte adhesion was visualized under static and flow conditions. Western blotting and in vitro kinase assays were used to assess Akt and MAPKs activation. NF
B activation and nuclear translocation of its p65 subunit were determined. TNF-
/LPS induced VCAM-1 expression in HIMEC was suppressed by Akt siRNA, curcumin, and inhibitors of NFB (SN-50), p38 MAPK (SB203580) and PI3K/Akt (LY294002). VCAM-1 induction was partially suppressed by p44/42 MAPK (PD098059) but unaffected by JNK (SP600125) inhibition. Curcumin inhibited Akt/MAPK/ NFB activity and prevented nuclear translocation of the p65 NFB subunit following TNF-/LPS. At physiologic shear stress, curcumin attenuated leukocyte adhesion to TNF-/LPS activated HIMEC monolayers. In conclusion, curcumin inhibited the expression of VCAM-1in HIMECs through blockade of Akt, p38 MAPK and NFB. Curcumin may represent a novel therapeutic agent targeting endothelial activation in IBD.
