Methods: First we examined the effects of di-phosphoryl lipid A (representing the native form in wild type LPS) and mono-phosphoryl lipid A on macrophages and fibroblasts (RAW264.7, 3T3 and LX2 cells) in vitro. We then examined alkaline phosphatase and LPS-dephosphorylating activity in normal and fibrotic livers of CCL4- treated mice and human patients. We also studied the effect of a 2-week administration of Calf Intestinal AP (500 mU/mouse/injection) on macrophages and fibroblasts in mice with CCl4-induced established fibrosis (8 weeks model). Finally, intestinal AP knock-out C57BL/6 mice (iAP KO) were examined at 6 weeks of age and

compared to age-matched wild-type. Results: Whereas diphosphoryl buy CP-690550 Lipid A strongly activated RAW cells, 3T3 and LX2 cells as reflected by enhanced expression of pro-inflammatory cytokines, adhesion molecules and MHC Class II, monophosphoryl lipid A induced

no such activities in either cell type. Significant dephosphorylating activity of diphosphoryl lipid A and wild type LPS was found in fibrotic livers of both mice and man. This activity co-localized with intra-hepatic AP activity. CD68-positive macrophages and α-SMA-positive cells were found to express AP activity. Administration of AP to CCL4-exposed fibrotic mice significantly attenuated staining for desmin which was associated with a reduction in the expression of the M2 macrophage marker YM-1. In contrast, iAP KO mice displayed higher intrahepatic expression levels of fibrogenic markers (PAR-1, Collagen I) paralleled by an increase in YM-1 staining relative to PLX4032 purchase WT. So, lack of intestinal AP stimulates fibrogenesis within the liver. Conclusions: Based on our in vitro studies it can be concluded that removal of just one phosphate from the Lipid A moiety of LPS abrogates many biological effects of LPS. The detection of LPS-dephosphorylating activity in fibrotic livers of mice and man may therefore represent the upregulation of a protective enzyme. The in vivo effects

of exogenous AP on fibroblasts and macrophages in fibrotic mice and our observations in i-AP KO mice further 上海皓元医药股份有限公司 support the hypothesis that alkaline phosphatase activity attenuates LPS-mediated effects within the fibrotic liver. Disclosures: Klaas Poelstra – Consulting: BiOrion Technologies BV; Grant/Research Support: BiOrion Technologies BV; Stock Shareholder: BiOrion Technologies BV The following people have nothing to disclose: Marlies Schippers, Eduard Post, Aysegul Cetintas, Catharina Reker-Smit, Madhu S. Malo, Richard A. Hodin, Jose L. Millan, Leonie Beljaars Patients with HCV/HIV co-infection show a faster progression of hepatic fibrosis and more severe inflammation. The HIV envelope protein gp120 has been previously shown to modulate different aspects of hepatic stellate cell (HSC) biology, including directional migration and expression of profibrogenic cytokines.