Anti-IFNG monoclonal antibody, clone 5T.C4 [PE]

Background and Aims: Primary sclerosing cholangitis (PSC) is an idiopathic, chronic cholestatic liver disorder characterized by biliary inflammation and fibrosis. Increased numbers of intrahepatic interferon-gamma- (IFN gamma) producing lymphocytes have been documented in patients with PSC, yet their functional role remains to be determined. Methods: Liver tissue samples were collected from patients with PSC. The contribution of lymphocytes to liver pathology was assessed in Mdr2(-/)(-) x Rag1(-/)(-) mice, which lack T and B cells, and following depletion of CD90.2(+) or natural killer (NK) p46(+) cells in Mdr2(-/)(-) mice. Liver pathology was also determined in Mdr2(-/)(-) x Ifng(-/)(-)mice and following anti-IFN gamma antibody treatment of Mdr2(-/)(-) mice. Immune cell composition was analysed by multi-colour flow cytometry. Liver injury and fibrosis were determined by standard assays. Results: Patients with PSC showed increased IFN gamma serum levels and elevated numbers of hepatic CD56(bright) NK cells. In Mdr2(-/)(-) mice, hepatic CD8(+) T cells and NK cells were the primary source of IFN gamma. Depletion of CD90.2(+) cells reduced hepatic Ifng expression, NK cell cytotoxicity and liver injury similar to Mdr2(-/)(-) x Rag1(-/)(-) mice. Depletion of NK cells resulted in reduced CD8' T cell cytotoxicity and liver fibrosis. The complete absence of IFN gamma in Mdr2(-/)(-) x Ifng(-/)( -)mice reduced NK cell and CD8(+) T cell frequencies expressing the cytotoxic effector molecules granzyme B and TRAIL and prevented liver fibrosis. The antifibrotic effect of IFN gamma was also observed upon antibody-dependent neutralisation in Mdr2(-/)(- )mice. Conclusion: IFN gamma changed the phenotype of hepatic CD8(+) T cells and NK cells towards increased cytotoxicity and its absence attenuated liver fibrosis in chronic sclerosing cholangitis. Therefore, unravelling the immunopathogenesis of PSC with a particular focus on IFN gamma might help to develop novel treatment options. Lay summary: Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by biliary inflammation and fibrosis, whose current medical treatment is hardly effective. We observed an increased interferon (IFN)-gamma response in patients with PSC and in a mouse model of sclerosing cholangitis. IFN gamma changed the phenotype of hepatic CD8(+) T lymphocytes and NK cells towards increased cytotoxicity, and its absence decreased liver cell death, reduced frequencies of inflammatory macrophages in the liver and attenuated liver fibrosis. Therefore, IFNy-dependent immune responses may disclose checkpoints for future therapeutic intervention strategies in sclerosing cholangitis. (C) 2019 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

AimsDespite pharmacokinetic monitoring of calcineurin inhibitors, the long-term outcome after transplantation (Tx) is still hampered by the side effects of these drugs. The aim of the present study was to characterize nuclear factor of activated T cells (NFAT)-regulated gene expression as a potential pharmacodynamic biomarker for further individualization of tacrolimus (Tac) therapy. MethodsIn 29 renal allograft recipients, samples were drawn once pre-Tx, and before and 1.5h after Tac dosing at approximately 1week, 6weeks and 1year post-Tx. Tac concentrations were measured by immunoassay, while the expression of genes encoding NFAT-regulated cytokines [interleukin 2 (IL2), interferon gamma (IFNG), colony stimulating factor 2 (CSF2)] and cytochrome P450 3A5 (CYP3A5) genotyping were determined by real-time polymerase chain reaction. ResultsThe cytokine response after Tac dosing varied up to 46-fold between patients and changed significantly with time post-engraftment. Tac concentrations 1.5h postdose (C-1.5) >15g l(-1) were associated with strong cytokine inhibition and residual gene expression (RGE) 10%, while lower Tac C-1.5 resulted in more variable responses (RGE 2.5-68.7%). Patients with ongoing subclinical acute rejection (n = 5) demonstrated limited cytokine inhibition (RGE 39.7-72.6%), while patients with polyoma virus viraemia (n = 3) had relatively strong inhibition of cytokines (RGE 2.5-32.5%). By contrast, there was no association between Tac exposure and rejection or viraemia. ConclusionsThe findings of our study support the potential of NFAT-regulated gene expression measurements as a pharmacodynamic tool for additional monitoring of Tac therapy, especially in the context of overimmunosuppression and viraemia.