Hepatocyte growth factor suppresses acute renal inflammation by inhibition of endothelial E-selectin

Abstract

Vascular endothelial activation, marked by de novo expression of E-selectin, is an early and essential event in the process of leukocyte extravasation and inflammation. Evidence suggests that hepatocyte growth factor (HGF) ameliorates inflammation in animal models of renal disease, implying that HGF might inhibit specific components of the inflammatory response. This study examined the effect of HGF on endothelial E-selectin expression in acute inflammation induced by tumor necrosis factor (TNF)-alpha. In vitro, HGF suppressed TNF-alpha-induced cell surface expression of E-selectin in human umbilical vein endothelial cells (HUVEC) and inhibited E-selectin mediated monocytic adhesion to endothelial monolayers. HGF activated phosphatidylinositol 3-kinase (PI3K)-Akt that in turn inhibited its downstream transducer glycogen synthase kinase (GSK)3. Blockade of the PI3K-Akt pathway with specific inhibitors abrogated HGF induced inhibitory phosphorylation of GSK3 and suppression of E-selectin. In addition, selective inhibition of GSK3 activity by lithium suppressed TNF-alpha-induced E-selectin expression and monocytic adhesion, reminiscent of the action of HGF. Moreover, ectopic expression of an uninhibitable mutant GSK3beta, in which the regulatory serine-9 is replaced by alanine, abolished HGF's suppressive effect on endothelial E-selectin. In vivo, administration of exogenous HGF reduced endothelial expression of E-selectin induced by bolus injection of TNF-alpha. This was associated with less sequestration of circulating fluorescence-labeled macrophages in the kidney. These findings suggest that HGF ameliorates acute renal inflammation in part by downregulating E-selectin mediated macrophage adhesion to the inflamed endothelium.

Hepatocyte Growth Factor Suppresses Proinflammatory NFκB Activation through GSK3β Inactivation in Renal Tubular Epithelial Cells

“…Moreover, GSK3␤ regulates NF B target gene expression in a gene-specific manner (32). Consistent with this hypothesis, we demonstrated that GSK3␤ inactivation is required for HGF suppression of multiple NF B-dependent proinflammatory chemokines and adhesion molecules (12,30), strongly suggesting that GSK3␤ is involved in the anti-inflammatory action of HGF. In this study, we further examined the role of GSK3␤ in mediating HGF suppression of NF B activation and the inflammatory response.…”

“…HGF, a pleiotropic ligand of the tyrosine kinase receptor c-Met, suppresses both acute and chronic inflammation and injury in a variety of organ systems (12)(13)(14)(15)(16)(17). This protective action was recently ascribed, at least in part, to potent antiinflammatory actions.…”

“…Protein concentration was determined by using a bicinchoninic acid protein assay kit (Sigma). Samples with equal amounts of total protein (50 g/ml) were fractionated by 7.5-15% SDS-polyacrylamide gels under reducing conditions and analyzed by Western immunoblot as described previously (12). The antibodies against p-GSK3␤, p-NF B RelA/p65, and p-I Ba were purchased from Cell Signaling Technology (Beverly, MA), and those for GSK3␤ and hemagglutinin were from Santa Cruz Biotechnology, Inc. (Santa Cruz, CA).…”

“…In vivo, HGF has been shown to protect against acute and chronic injury in multiple organ systems, including liver (8), lung (9), intestine (10), and kidney (11). Among the mechanisms potentially responsible for this beneficial action, a growing body of evidence from this (12,13) and other groups (9, 14 -17) suggests that HGF has potent anti-inflammatory effects. One fundamental event that is central to the pathophysiology of inflammation is the activation of NF B, a nuclear transcription factor that controls the expression of numerous proinflammatory molecules (18,19).…”

“…One fundamental event that is central to the pathophysiology of inflammation is the activation of NF B, a nuclear transcription factor that controls the expression of numerous proinflammatory molecules (18,19). Studies show that HGF suppresses NF B activation in cultured cells in vitro following TNF-␣ stimulation (13,20,21) and in vivo in inflamed organs, such as the kidney (20,22). However, the molecular mechanism responsible for this inhibitory effect remains uncertain.…”