Abstract 12933: The Protective effect of Hepatocyte Growth Factor on LPS-induced Inflammation via Epithelial Growth Factor Degradation
Background: Lipopolysaccharide (LPS) triggers systemic inflammatory response syndrome (SIRS). LPS-induced vascular injury in these conditions results in sepsis and multi organ failure. There is no successful way to treat LPS-induced SIRS, and problems still remain. Besides, we recently reported the novel anti-inflammatory and anti-oxidative mechanisms of hepatocyte growth factor (HGF) through epithelial growth factor receptor (EGFR) degradation by ubiquitin-proteasome system (UPS) (Circ Res 2009). In the present study, we investigated whether HGF ameliorates LPS-induced SIRS via UPS or not.
Methods and Results: In vitro; Human aortic vascular smooth muscle cells (HAVSMC) were stimulated with LPS (50ng/ml) in the presence of HGF (20ng/ml) or not. LPS administration significantly up-regulated the expression of EGFR and its downstream VCAM-1 (P<0.05). However, pretreatment of HGF significantly attenuated the LPS-induced up-regulation of EGFR and VCAM-1 (P<0.05). In turn, transfection with EGFR siRNA significantly inhibited LPS-induced VCAM-1 expression (P<0.05). Next, we focused on SHIP2 and c-Cbl (E3 ubiquitin ligase) binding to EGFR and c-Met. Pretreatment of HGF markedly increased SHIP2 translocation from EGFR to c-Met. In contrast, binding of c-Cbl to EGFR was significantly increased (P<0.05). Also, treatment of HAVSMCs with MG-132, a specific proteasome inhibitor, significantly inhibited HGF mediated amelioration of EGFR expression. In vivo: LPS (1mg) was injected intravenously into HGF transgenic mice (TG) with a high expression of human HGF in heart or its litter mates (WT). After 24 hours of injection, tissue was harvested, protein expression and superoxide production was evaluated by western blotting and DHE staining respectively. VCAM-1 expression and superoxide production was significantly attenuated in the abdominal aorta of HGF TG mice (P<0.05). Notably, significant EGFR degradation was observed under these conditions of HGF TG mice (P<0.05). Moreover, survival rate were significantly improved in HGF TG mice (P<0.05).
Conclusions: These data suggest that HGF inhibits LPS-induced inflammation via EGFR degradation by UPS. This protective effect of HGF may be instrumental in therapy for inflammatory disease.
- © 2010 by American Heart Association, Inc.