HLA class II donor specific antibodies are associated with graft cirrhosis after liver transplant independent of the mean fluorescence intensity level

Background!#!The importance of donor-specific antibodies (DSA) after liver transplantation (LT) for graft and patient survival is an ongoing controversy. So far it has not been elucidated when and in how far DSA are harmful for graft and patient survival. Therefore, we had the aim to investigate the association of DSA with complications after LT.!##!Methods!#!Data of 430 LT recipients were collected and statistically analyzed. Detection of HLA antibodies (Ab) was performed by Luminex assay.!##!Results!#!DSA were detected in 81 patients (18.8%). These were mainly HLA class II Ab (81.5%). HLA class II Ab show a higher MFI (median: 5.300) compared to HLA class I Ab (median: 2.300). There is no association between MFI levels and development of complications after LT. However, cirrhosis occurred significantly more often in DSA positive patients (18%) than in patients without detectable DSA (9%, P = 0.027). All DSA positive patients with cirrhosis of the graft showed HLA class II antibodies (OR: 3.028; 95% CI: 1.51-6.075; P = 0.002).!##!Conclusion!#!Occurrence of HLA class II DSA after LT is associated with graft cirrhosis and may indicate a higher risk to develop graft damage independent on MFI and requires an individualized risk management

Upregulation of Major Histocompatibility Complex Class I on Liver Cells by Hepatitis C Virus Core Protein via p53 and TAP1 Impairs Natural Killer Cell Cytotoxicity

The mechanisms of immune evasion and the role of the early immune response in chronic infection caused by hepatitis C virus (HCV) are still unclear. Here, we present evidence for a cascade of molecular events that the virus initiates to subvert the innate immune attack. The HCV core protein induced p53-dependent gene expression of TAP1 (transporter associated with antigen processing 1) and consecutive major histocompatibility complex (MHC) class I upregulation. Moreover, in p53-deficient liver cell lines, only reconstitution with wild-type p53, but not mutated p53 lacking DNA binding capacity, showed this effect. As a consequence of increased MHC class I expression, a significantly downregulated cytotoxic activity of natural killer (NK) cells against HCV core-transfected liver cells was observed, whereas lysis by HCV-specific cytotoxic T cells was not affected. These results demonstrate a way in which HCV avoids recognition by NK cells that may contribute to the establishment of a chronic infection

Comparison of Three Cellular Assays to Predict the Course of CMV Infection in Liver Transplant Recipients

To estimate protection from cytomegalovirus (CMV) replication after solid organ transplantation, CMV serology has been considered insufficient and thus CMV immunity is increasingly assessed by cellular in vitro methods. We compared two commercially available IFN-γ ELISpot assays (T-Track CMV and T-SPOT.CMV) and an IFN-γ ELISA (QuantiFERON-CMV). Currently, there is no study comparing these three assays. The assays were performed in 56 liver transplant recipients at the end of antiviral prophylaxis and one month thereafter. In CMV high- or intermediate-risk patients the two ELISpot assays showed significant correlation (p < 0.0001, r > 0.6) but the correlation of the ELISpot assays with QuantiFERON-CMV was weaker. Results of both ELISpot assays were similarly predictive of protection from CMV-DNAemia ≥500 copies/mL [CMV pp65 T-SPOT.CMV at the end of prophylaxis: area under curve (AUC) = 0.744, cut-off 142 spot forming units (SFU), sensitivity set to 100%, specificity 46%; CMV IE-1 T-Track CMV at month 1: AUC = 0.762, cut-off 3.5 SFU, sensitivity set to 100%, specificity 59%]. The QuantiFERON-CMV assay was inferior, reaching a specificity of 23% when setting the sensitivity to 100%. In conclusion, both CMV-specific ELISpot assays appear suitable to assess protection from CMV infection/reactivation in liver transplant recipients

Dynamics of liver stiffness by transient elastography in patients with chronic hepatitis C virus infection receiving direct-acting antiviral therapy-Results from the German Hepatitis C-Registry

The impact of direct-acting antiviral (DAA) therapies on fibrosis regression remains uncertain. In the current study, we prospectively evaluated dynamics of liver stiffness by transient elastography (TE) in patients with chronic HCV infection receiving DAA-based treatment. Patients (260) were enrolled in the German Hepatitis C-Registry (DHC-R), a national multicentre real-world cohort. Liver stiffness (LS) was assessed at baseline, end of treatment (EOT) and 24 weeks after EOT (FU24) by TE. Biochemical, virological and clinical data were obtained in parallel. In patients with SVR, there was a significant improvement of LS between baseline (median [range], 8.6 [1.7-73.5] kPa) and FU24 (7.9 [1.7-75 kPa];P < .0001) as well as between EOT (8.4 [1.7-73.5 kPa]) and FU24 [P < .0001]. Stratified by fibrosis stage, patients classified into F4 had higher magnitude of LS reduction between BL (median [range], 25.1 [13.5-73.5] kPa) and FU24 (21.5 [3.1-75] kPa;P = .002) compared to those with F2-F3 (8.9 [7.1-12.4] kPa and 8.8 [4.2-29.1];P = .060) or F0-F1 (5.3 [1.7-7] kPa and 5.2 [1.7-7.7];P = .064). In cirrhotic patients, low platelets were significantly associated with lack of liver stiffness improvement, both at EOT (P = .018) and at FU24 (P = .012). LS significantly correlated with ALT (r = .371), AST (r = .552), platelets (r = -.499), GGT (r = .250), bilirubin (r = .230), APRI score (r = .512), FIB-4 score (r = .517) and FORNS index (r = .562);P < .0001. Liver elastography improved significantly in our real-world cohort after DAA-based therapy. As LS correlates similarly with transaminase levels and serum fibrosis markers, it might reflect both reduction of necroinflammation and fibrosis regression

Proteasome inhibition sensitizes hepatocellular carcinoma cells, but not human hepatocytes, to TRAIL

TRAIL exhibits potent anti-tumor activity on systemic administration in mice. Because of its proven in vivo efficacy, TRAIL may serve as a novel anti-neoplastic drug. However, approximately half of the tumor cell lines tested so far are TRAIL resistant, and potential toxic side effects of certain recombinant forms of TRAIL on human hepatocytes have been described. Pretreatment with the proteasome inhibitor MG132 and PS-341 rendered TRAIL-resistant hepatocellular carcinoma (HCC) cell lines but not primary human hepatocytes sensitive for TRAIL-induced apoptosis. We investigated the different levels of possible MG132-induced interference with resistance to apoptotic signal transduction. Although proteasome inhibition efficiently suppressed nuclear factor-kappaB (NF-κB) activity, specific suppression of NF-κB by mutIκBα failed to sensitize TRAIL-resistant cell lines for TRAIL-induced apoptosis. In contrast to the previously reported mechanism of sensitization by 5-fluorouracil (5-FU), cellular FLICE-inhibitory protein (cFLIP)L and cFLIPS were markedly upregulated in the TRAIL death inducing signaling complex (DISC) by proteasome inhibitor pretreatment. Compared with 5-FU pretreatment, caspase-8 was more efficiently recruited to the DISC in MG132 pretreated cells despite the presence of fewer death receptors and more cFLIP in the DISC. But downregulation of cFLIP by short interference RNA (siRNA) further sensitized the HCC cell lines. In conclusion, these results show that otherwise chemotherapy-resistant tumor cells can be sensitized for TRAIL-induced apoptosis at the DISC level in the presence of high levels of cFLIP, which suggests the existence of an additional factor that modulates the interaction of FADD and the TRAIL death receptors. Of clinical relevance, proteasome inhibitors sensitize HCC cells but not primary human hepatocytes for TRAIL-induced apoptosis. Copyright © 2005 by the American Association for the Study of Liver Diseases