LECT2 induces atherosclerotic inflammatory reaction via CD209 receptor-mediated JNK phosphorylation in human endothelial cells

Objective Leukocyte cell-derived chemotaxin 2 (LECT2) is a recently discovered novel hepatokine, leading to skeletal muscle insulin resistance by activating c-Jun N-terminal kinase (JNK). However, its role in atherosclerotic inflammatory reactions has not been examined. Therefore, we investigated the function of LECT2 on the expression of vascular adhesion molecules and inflammatory cytokines in human endothelial cells. Methods Human umbilical vein endothelial cells (HUVECs) and THP-1 cells were treated with various doses of LECT2 and the functions and signaling pathways were analyzed through Western blot and quantitative real-time PCR (qPCR). Results The level of phosphorylated c-Jun N-terminal kinases (JNK) was significantly increased by LECT2 treatment in HUVECs and THP-1 cells, an effect that was not seen in cells treated with CD209 siRNA, a known LECT2 receptor. LECT2 treatment efficiently increased the expression of intercellular adhesion molecule-1 (ICAM-1) and pro-inflammatory cytokines tumor necrosis factor α (TNFα), monocyte chemo-attractant protein-1 (MCP-1), and interleukin-1β (IL-1β) in HUVECs and THP-1 cells. However, all these reactions were significantly reduced in response to treatment with JNK inhibitor. Furthermore, LECT2 treatment significantly exacerbated the adhesion of monocytic cells to human endothelial cells, which was also efficiently attenuated by JNK inhibitor. Conclusions LECT2 significantly induced adhesion molecules and pro-inflammatory cytokines in HUVECs via CD209-mediated JNK phosphorylation, suggesting that liver-derived novel hepatokine, LECT2, might directly mediate in the atherosclerotic inflammatory reactions in human endothelial cells.