Glycogen synthase kinase 3 involvement in the excessive proinflammatory response to LPS in patients with decompensated cirrhosis

Background & Aims: In decompensated cirrhosis, the early innate immune response to the Toll-like receptor 4 (TLR4) agonist, lipopolysaccharides (LPS), is characterized by a hyper-production of pro-inflammatory cytokines and hypo-production of the anti-inflammatory cytokine IL-10. In LPS-stimulated non-cirrhotic immune cells, the constitutively active glycogen synthase kinase (GSK) 3 favors pro- vs. anti-inflammatory cytokines, by acting on gene induction. However, in these cells, TLR4 dampens its own pro-inflammatory response by inducing early (within minutes) AKT-mediated phosphorylation of GSK3 beta (one of two GSK3 isoforms) on Ser9. Phosphorylation of GSK3 beta (Ser9) inhibits its activity, decreases pro-inflammatory cytokines, and increases IL-10. Thus, we investigated the role of GSK3 in LPS-induced cytokine production by peripheral blood mononuclear cells (PBMCs) or monocytes from patients with advanced cirrhosis and normal subjects. Methods: Cells were pre-incubated with or without GSK3 inhibitor (SB216763 or lithium chloride) for 1 h and then stimulated with LPS. Cytokine production was assessed at mRNA and secreted proteins levels, by real-time RT-PCR at 1 h and ELISA at 20 h, respectively. GSK3 beta phosphorylation was assessed using Western blotting. Results: In cirrhotic and normal PBMCs pretreated with GSK3 inhibitors, LPS-induced production of pro-inflammatory proteins TNF-alpha and IL-12p40 was significantly decreased while that of IL-10 was increased. LPS-induced, AKT-mediated phosphorylation of GSK3b on Ser9 found in normal monocytes, was abolished in cirrhotic cells. Conclusions: GSK3 is involved in the early TLR4-mediated pro-inflammatory response in patients with decompensated cirrhosis. This was associated with a defect in AKT-mediated GSK3 beta phosphorylation resulting in unrestricted 'pro-inflammatory' activity of the enzyme. (C) 2011 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.