POSTERS and CCL22 than MDDC co-cultured with uninfected cells (936±115 vs 801±76 pg/ml CCL17, and 4174±378 vs 2434±776 pg/ml CCL22, p < 0.05). Also, it was found that supernatants of MDDC co-cultured with JFH1-Huh7 infected cells attract more Treg than supernatants of MDDC co-cultured with uninfected cells (p < 0.005). This effect is blocked when we inhibited chemokines with specific antibodies. Conclusions: Dendritic cells in contact with HCV-infected cells produce chemokines (CCL22 and CCL17) able to attract Treg. This is consistent with higher levels of CCL22, CCL17 and Foxp3+ cells in liver biopsies of patients with chronic hepatitis C. Our results suggest that upregulation of CCL22 and CCL17 by HCV infection may contribute to virus persistance and identify new targets for HCV treatment. 444 RAISED SERUM LEVELS OF CXCL-10 PRE-TREATMENT ARE ASSOCIATED WITH POOR VIROLOGICAL RESPONSES TO INTERFERONa TREATMENT FOR CHRONIC HEPATITIS C S. Sarwar 1 , E. Ryan 2 , J. Hegarty 1 , C. O’Farrelly 2 . 1 National Liver Transplantation Unit, St. Vincent’s University Hospital, Dublin, 2 School of Biochemistry & Immunology, Trinity College Dublin, Dublin, Ireland E-mail: shehzad32@hotmail.com Background and Aims: The chemokine CXCL-10 is increased in hepatocytes and serum from chronic hepatitis C (CHC) infected patients. Lower pre-treatment CXCL-10 levels have been suggested to be associated with rapid virological response (RVR) and early virological response (EVR); strong indicators of sustained virological response to treatment with pegylated interferon-a (PEG IFNa) and ribavirin. We studied association of pre-treatment serum CXCL-10 with RVR and EVR in CHC treatment. Methods: 49 patients undergoing treatment for CHC Liver Unit SVUH were included in the study. All patients received standard treatment with PEG INFa 2a or PEG INFa 2b and with ribavirin. Pre-treatment serum CXCL-10 levels were quantified by ELISA. Viral loads were measured regularly. RVR had occurred when HCVRNA was undetectable at 4 weeks of treatment. EVR was defined as ≥2 log decrease or undetectable HCV RNA after 12 weeks of treatment. Results: Of 49 patients, 31 (63%) achieved RVR and 38 (78%) achieved EVR. Median pre-treatment serum CXCL-10 levels were significantly lower in patients who achieved RVR (107 pg/mL, IQR: 44–240) compared to those who did not achieve RVR (347 pg/mL, IQR: 116–464) (P = 0.003). Similarly median pre- treatment serum CXCL-10 levels were significantly lower in patients who achieved EVR (119 pg/mL, IQR: 60–241) compared to those who did not achieve EVR (392 pg/mL, IQR: 123–505) (P = 0.01). Median pre-treatment serum CXCL-10 levels were significantly lower in genotype 3 patients (N = 24, 102 pg/mL, IQR: 24–235) than genotype 1 (N = 25, 271 pg.mL, IQR: 100–450) (P = 0.01). Median pre-treatment CXCL-10 levels in genotype 1 patients who achieved EVR were also significantly lower (N = 15, 125 pg/mL, IQR: 64–287) than those who did not achieve EVR (N = 10, 395 pg/mL, IQR: 286– 505) (P = 0.04). Conclusions: Patients who failed to achieve rapid or early virological response had raised levels of CXCL-10 pre-treatment. Genotype 1 patients, known to be poor responders to PEG IFNa also had higher CXCL-10 levels than those infected with genotype 3. These results suggest that high CXCL10 levels may contribute to inhibition of the response to IFNa. 445 THE ACTIVATION OF THE HEPATIC IMMUNE SYSTEM BY SIRNAS IS DIFFERENTLY CONTROLLED BY CHEMICAL MODIFICATIONS AND MAY INVOLVE ENDOSOMAL TOLL-LIKE RECEPTORS R. Broering 1 , M. John 2 , K. Kleinehr 1 , J.-P. Sowa 1 , A. Bucchi 1 , G. Gerken 1 , J. Schlaak 1 . 1 Dept. of Gastroenterology and Hepatology, University Hospital of Essen, Essen, 2 Roche Kulmbach GmbH, Kulmbach, Germany E-mail: joerg.schlaak@uni-due.de Background: siRNAs are being developed for the therapeutic use in liver cancer, viral hepatitis or metabolic disorders. Undesired immune stimulation by siRNAs is usually studied in human cell lines or PBMC. Here, we assessed the capacity of chemically modified siRNAs to trigger immune responses in primary human cells of the liver. Methods: siRNAs targeting APOB1 (APO, APO-chol) and control siRNAs targeting luciferase (LUC) or galactosidase (GAL) mRNA were transfected into primary isolated human cells (PBMC, Kupffer cells, hepatocytes). Human hepatoma cells (Huh7) were used for comparison. Expression of IFN-a, IFN-b, ISG15, IFIT1 and TNF-a was determined by qt RT-PCR. Chloroquine was used as inhibitor of endosomal acidification. Results: Transfection of PBMC with APO, APO-chol and GAL siRNAs showed strong induction of IFNa/b, ISGs and TNFa gene expression. None of these genes were induced by the LUC siRNA harbouring 2’-O-methyl modified nucleotides. Comparable results were obtained for Kupffer cells, with the cholesterol-conjugated APO siRNA giving the strongest induction in ISG expression. A more complex picture was found in hepatocytes. ISG induction was found after transfection of APO-chol siRNA and the GAL siRNA, but not for the APO and LUC siRNA. These immunostimulatory effects were abrogated after pretreatment with chloroquine. siRNA transfection of Huh7 did not lead to the induction of any ISGs despite efficient gene knockdown of APOB1 mRNA. Conclusion: Unmodified siRNAs with or without cholesterol- conjugation led to strong and cell-type specific activation of the innate immune system of the liver and the peripheral blood. In contrast, 2 ′ -O-methyl-modified siRNAs did not trigger any immune responses in any tested cell type. These data further enhance our understanding of the effects of siRNA modifications on innate immune stimulation which is of major importance for the development of safe and efficient RNAi-based therapeutics. 446 HCV/TLR3-DEPENDENT INNATE AND ADAPTIVE IMMUNE FUNCTIONS OF NON-PARENCHYMAL LIVER CELLS ARE CONTROLLED BY INTERLEUKIN-10 AND TRANSFORMING GROWTH FACTOR BETA M. Jiang 1,2 , J. Wu 1 , E. Zhang 2 , Z. Meng 2 , M. Trippler 1 , R. Broering 1 , M. Roggendorf 2 , G. Gerken 1 , M. Lu 2 , J. Schlaak 1 . 1 Dept. of Gastroenterology and Hepatology, 2 Institute of Virology, University Hospital of Essen, Essen, Germany E-mail: joerg.schlaak@uni-due.de Background: The regulation of HCV/TLR3-mediated innate immune responses in the liver is not well understood. Therefore, we analyzed the capacity of the anti-inflammatory cytokines interleukin-10 (IL-10) and transforming growth factor beta (TGF-b) to regulate TLR3-activation of non-parenchymal liver cells. Methods: Murine Kupffer cells (KC) and sinusoidal endothelial cells (LSEC) were cultivated in the presence or absence of IL-10 or TGF-b and stimulated by TLR3 ligands. Supernatants from TLR-stimulated NPC were assayed for antiviral activities by viral protection assays (EMCV) on L929 cells. Total RNA was isolated and analyzed by quantitative rt-PCR. Mixed lymphocyte reactions (MLR) were performed to assess T cell activation while activation of transcription factors (NF-úB, IRF-3) was studied by western blot S180 Journal of Hepatology 2010 vol. 52 | S59–S182