Abstract
Curcumin, a polyphenolic compound derived from the widely used spice Curcuma longa, has shown anti-atherosclerotic effects in animal models and cultured vascular cells. Inflammation is a major contributor to atherosclerosis development and progression. We previously reported that the induction of the proinflammatory molecule TRAF3IP2 (TRAF3 Interacting Protein 2) or inhibition of the matrix metallopeptidase (MMP) regulator RECK (REversion Inducing Cysteine Rich Protein with Kazal Motifs) contributes to pro-oxidant, proinflammatory, pro-mitogenic and pro-migratory effects in response to external stimuli in vascular smooth muscle cells. Here we hypothesized that EF24, a curcumin analog with a better bioavailability and bioactivity profile, reverses interleukin (IL)-18-induced TRAF3IP2 induction, RECK suppression and the proinflammatory phenotype of primary human aortic smooth muscle cells (ASMC). The exposure of ASMC to functionally active recombinant human IL-18 (10 ng/mL) upregulated TRAF3IP2 mRNA and protein expression, but markedly suppressed RECK in a time-dependent manner. Further investigations revealed that IL-18 inhibited both miR-30a and miR-342 in a p38 MAPK- and JNK-dependent manner, and while miR-30a mimic blunted IL-18-induced TRAF3IP2 expression, miR-342 mimic restored RECK expression. Further, IL-18 induced ASMC migration, proliferation and proinflammatory phenotype switching, and these effects were attenuated by TRAF3IP2 silencing, and the forced expression of RECK or EF24. Together, these results suggest that the curcumin analog EF24, either alone or as an adjunctive therapy, has the potential to delay the development and progression of atherosclerosis and other vascular inflammatory and proliferative diseases by differentially regulating TRAF3IP2 and RECK expression in ASMC.