Cellular factors involved in CXCL8 expression induced by glycated serum albumin in vascular smooth muscle cells

Glycated serum albumin (GSA) promotes vascular complications in diabetes. The aim of this study was to determine if GSA induces chemokine, particularly CXCL8 (IL-8), and to determine intracellular signaling pathways activated by GSA in vascular smooth muscle cells (VSMCs). GSA increased IL-8 transcription via promoter activation and enhanced CXCL8 release from VSMCs. GSA-induced promoter activation of the IL-8 gene was suppressed by dominant-negative mutants of TLR-4, MyD88, and TRIF, but not by a dominant-negative form of TLR-2. In addition, IL-8 up-regulation in response to GSA was inhibited by resveratrol, curcumin, diphenyleneiodium, U0126, and SB202190. Mutation at the NF-κB- or C/EBP-binding site, but not at the AP-1-binding site, in the IL-8 promoter region suppressed GSA-induced promoter activation. Moreover, gene delivery of IκB suppressed CXCL8 release. This study suggests that GSA induces expression of IL-8 in VSMCs and that TLR-4, mitogen-activated protein kinases, NF-κB, and NADPH oxidase are involved in that process.