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Background & Aims: Mature transfer RNAs (tRNA) charged with amino acids decode mRNA to synthesize proteins. Dysregulation of translational machineries has a fundamental impact on cancer biology. This study aims to map the tRNAome landscape in liver cancer patients and to explore potential therapeutic targets at the interface of charging amino acid with tRNA. Methods: Resected tumour and paired tumour‐free (TFL) tissues from hepatocellular carcinoma (HCC) patients (n = 69), and healthy liver tissues from organ transplant donors (n = 21), HCC cell lines, and cholangiocarcinoma (CC) patient‐derived tumour organoids were used. Results: The expression levels of different mature tRNAs were highly correlated and closely clustered within individual tissues, suggesting that different members of the tRNAome function cooperatively in protein translation. Interestingly, high expression of tRNA‐Lys‐CUU in HCC tumours was associated with more tumour recurrence (HR 1.1; P =.022) and worse patient survival (HR 1.1; P =.0037). The expression of Lysyl‐tRNA Synthetase (KARS), the enzyme catalysing the charge of lysine to tRNA‐Lys‐CUU, was significantly upregulated in HCC tumour tissues compared to tumour‐free liver tissues. In HCC cell lines, lysine deprivation, KARS knockdown or treatment with the KARS inhibitor cladosporin effectively inhibited overall cell growth, single cell‐based colony formation and cell migration. This was mechanistically mediated by cell cycling arrest and induction of apoptosis. Finally, these inhibitory effects were confirmed in 3D cultured patient‐derived CC organoids. Conclusions: The biological process of charging tRNA‐Lys‐CUU with lysine sustains liver cancer cell growth and migration, and is clinically relevant in HCC patients. This process can be therapeutically targeted and represents an unexplored territory for developing novel treatment strategies against liver cancer. [ABSTRACT FROM AUTHOR]

No curative treatment options are available for advanced hepatocellular carcinoma (HCC). Anti‐PD1 antibody therapy can induce tumor regression in 20% of advanced HCC patients, demonstrating that co‐inhibitory immune checkpoint blockade has therapeutic potential for this type of cancer. However, whether agonistic targeting of co‐stimulatory receptors might be able to stimulate anti‐tumor immunity in HCC is as yet unknown. We investigated whether agonistic targeting of the co‐stimulatory receptor GITR could reinvigorate ex vivo functional responses of tumor‐infiltrating lymphocytes (TIL) freshly isolated from resected tumors of HCC patients. In addition, we compared GITR expression between TIL and paired samples of leukocytes isolated from blood and tumor‐free liver tissues, and studied the effects of combined GITR and PD1 targeting on ex vivo TIL responses. In all three tissue compartments, CD4+FoxP3+ regulatory T cells (Treg) showed higher GITR−expression than effector T‐cell subsets. The highest expression of GITR was found on CD4+FoxP3hiCD45RA− activated Treg in tumors. Recombinant GITR‐ligand as well as a humanized agonistic anti‐GITR antibody enhanced ex vivo proliferative responses of CD4+ and CD8+ TIL to tumor antigens presented by mRNA‐transfected autologous B‐cell blasts, and also reinforced proliferation, IFN‐γ secretion and granzyme B production in stimulations of TIL with CD3/CD28 antibodies. Combining GITR ligation with anti‐PD1 antibody nivolumab further enhanced tumor antigen‐specific responses of TIL in some, but not all, HCC patients, compared to either single treatment. In conclusion, agonistic targeting of GITR can enhance functionality of HCC TIL, and may therefore be a promising strategy for single or combinatorial immunotherapy in HCC. What's new? Therapeutic antibodies that block interaction of the T cell co‐inhibitory receptor PD1 can unleash pre‐existing anti‐cancer T cell responses in hepatocellular carcinoma (HCC). However, whether agonistic targeting of co‐stimulatory receptors could stimulate anti‐tumor immunity remains unknown. This study is the first to show that agonistic targeting of the co‐stimulatory receptor GITR can reinforce the functionality of tumor‐infiltrating T cells isolated from human tumors. Combined targeting of PD1 and GITR exerts additive stimulatory effects on ex vivo functionality of tumor‐infiltrating T cells from HCC patients. Targeting of GITR thus emerges as a promising strategy for single or combinatorial immunotherapy in HCC. [ABSTRACT FROM AUTHOR]

Abstract: Donor‐specific alloantibodies (DSA) have been associated with rejection and shorter graft survival after orthotopic liver transplantation (OLT). We examined the role of DSA in nonanastomotic biliary strictures (NAS) after OLT. Patients receiving first OLT who developed NAS (n = 68) and a control group without NAS (n = 83), with pre‐OLT and 12 months post‐OLT serum samples, were included. DSA were specified using the Luminex single antigen test. Risk factors for NAS and graft survival were analyzed. The presence of preformed DSA was not significantly different between patients with NAS and controls (P = .89). After 12 months, 26.5% of NAS patients and 16.9% of controls had generated de novo DSA (P = .15). Neither de novo class I DSA nor de novo class II DSA were associated with NAS. De novo DSA generally developed after the diagnosis of NAS. Time‐dependent regression analysis identified both NAS (aHR 8.05, CI 3.28 – 19.77, P < .01) and de novo class II DSA (aHR 2.84, CI 1.38 – 5.82, P < .01) as independent risk factors for graft loss. Preformed or de novo DSA were not associated with the development of NAS. However, NAS as well as de novo class II DSA were independent risk factors for graft loss after OLT. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms of immune resistance in pancreatic and ampullary cancers is crucial for the development of suitable biomarkers and effective immunotherapeutics. Our aim was to examine the expression of the immune inhibiting molecules PD-L1, Galectin-9, HVEM, IDO and HLA-G, as well as CD8+ and FoxP3+ tumor infiltrating lymphocytes (TIL), in pancreatic and ampullary cancers, and to relate their individual, as well as their combined expression, to cancer survival. Tumor tissue from 224 patients with resected pancreatic ( n = 148) and ampullary ( n = 76) cancer was used to construct tissue-microarrays. Expression of immune inhibitory molecules and TIL was examined by immunohistochemistry. We show that immune inhibitory molecules are prevalently expressed. Moreover, high tumor expression of PD-L1 ( p = 0.002), Gal-9 ( p = 0.003), HVEM ( p = 0.001), IDO ( p = 0.049), HLA-G ( p = 0.004) and high CD8/FoxP3 TIL ratio ( p = 0.006) were associated with improved cancer-specific survival. All immune biomarkers, with the exception of IDO, were individually predictive of cancer-specific survival when adjusted for clinicopathologic characteristics. For every additional immune biomarker present survival was almost two-fold prolonged (HR 0.57 95%CI 0.47-0.69, p < 0.0001). When patients with pancreatic and ampullary cancer were analyzed separately the results were similar. We conclude that pancreas and ampullary cancers are rich in expression of immune-inhibitory molecules. These molecules can be targets for future immunotherapeutics, as well as form powerful immunological biomarkers. We propose that such immune biomarker panels be included in future prospective immunotherapy trials. [ABSTRACT FROM AUTHOR]

Background & Aims Extracellular micro RNAs (mi RNAs) in serum and bile are currently under intense investigation for biomarker purposes in liver disease. However, the directions and pathways by which mi RNAs are released from hepatic cells remains largely unknown. Here, we investigated the release of hepatocyte and cholangiocyte-derived mi RNAs ( HDmiRs and CDmiRs) into blood and bile during various (patho)physiological hepatic conditions. Methods Mi RNA release was analysed using longitudinally collected tissue and paired bile and serum samples ( n = 124) that were obtained from liver transplant recipients during follow-up. Results Cell-type specificity of HDmiRs and CDmiRs was confirmed in liver and common bile duct biopsies ( P < 0.001). Analysis of paired bile and serum samples showed up to 20-times higher mi RNA-levels in bile compared to serum ( P < 0.0001). Fractionation of bile showed the majority of mi RNAs being present in the unpelletable supernatant, where protein conjunctions protect mi RNAs against degradation ( P < 0.0001). During episodes of liver injury and histologically proven rejection in liver transplant recipients, relative HDmiR-levels in bile decreased while its levels in serum increased ( P ≤ 0.015). Simultaneously, relative CDmiR-levels in bile significantly increased, while their levels in serum decreased. Related to liver excretory function, a strong positive correlation was observed between HDmiR-122 levels and bilirubin excretion into bile ( R = 0.694, P < 0.0001), whereas CDmiRs showed an inverse correlation ( P < 0.05). Conclusion During impaired excretory function and injury, the liver shows polarized release of extracellular HDmiRs and CDmiRs. This sheds new light on the biology of hepatic mi RNA release which is relevant for the interpretation of hepatic mi RNAs as biomarkers. [ABSTRACT FROM AUTHOR]

Hepatic NK cells constitute ∼40% of hepatic lymphocytes and are phenotypically and functionally distinct from blood NK cells. Whether hepatic NK cells derive from precursors in the BM or develop locally from hepatic progenitors is still unknown. Here, we identify all five known sequential stages of NK-cell development in the adult human liver and demonstrate that CD34+ hepatic progenitors can generate functional NK cells. While early NK-cell precursors (NKPs) were similar in liver and blood, hepatic stage 3 NKPs displayed immunophenotypical differences, suggesting the onset of a liver-specific NK-cell development. Hepatic stage 3 NKPs were RORCneg and did not produce IL-17 or IL-22, excluding them from the lymphoid tissue-inducer (LTi) subset. In vitro culture of hepatic NKPs gave rise to functional NK cells exhibiting strong cytotoxicity against K562 targets. To determine whether hepatic NKPs are stably residing in the liver, we analyzed donor and recipient-derived cells in transplanted livers. Shortly after liver transplantation all donor NKPs in liver grafts were replaced by recipient-derived ones, indicating that hepatic NKPs are recruited from the bloodstream. Together, our results show that NKPs are continuously recruited from peripheral blood into the liver and can potentially differentiate into liver-specific NK cells. [ABSTRACT FROM AUTHOR]

Allo-reactive memory T cells are a major barrier for induction of immunological tolerance to allografts in humans. Here, we report that stimulation of unfractionated human T cells with TLR-stimulated allogeneic plasmacytoid dendritic cells (pDCs) induces CD8 regulatory T cells (Tregs) that inhibit T-cell allo-responses, including those of memory T cells. CD3 T cells were primed for 7 days with allogeneic pDCs that had been pre-stimulated with TLR-7 or TLR-9 ligands. While the T cells proliferated and produced cytokines during the priming culture, they were profoundly hypo-responsive to re-stimulation with the same allo-antigen in a second culture. Moreover, T cells primed by pDCs exerted donor-specific suppression on allo-responses of both unfractionated and memory CD3 T cells. The regulatory capacity of pDC-primed T cells was confined to CD8LAG-3Foxp3CTLA-4 T cells, which suppressed allogeneic T-cell responses through a CTLA-4-dependent mechanism. Induction of CD8 Tregs by pDCs could be partially prevented by 1-methyl tryptophan, an inhibitor of indoleamine 2,3-dioxygenase. In conclusion, stimulation of human T cells by TLR-stimulated allogeneic pDCs induces CD8 Tregs that inhibit allogeneic T-cell responses, including memory T cells. Donor-derived pDCs may be considered as an immunotherapeutic tool to prevent activation of the recipient allo-reactive (memory) T-cell repertoire after allogeneic transplantation. [ABSTRACT FROM AUTHOR]

Abstract: RNA interference (RNAi) is widely used as a screening tool for the identification of host genes involved in viral infection. Due to the limitation of raw small interfering RNA (siRNA), we tested two commonly used short hairpin RNA (shRNA) lentiviral libraries to identify host factors involved in hepatitis C virus (HCV) infection. It was found that these shRNA library vectors caused non-specific disturbance of HCV replication that was not due to toxicity or interferon response, but related to the high shRNA levels disturbing the endogenous microRNA biogenesis. The high shRNA levels achieved with these vectors reduced the levels of mature microRNAs, including miR-122 known to promote HCV replication. Our findings extend the caution of potential off-target effects of lentiviral shRNA libraries which appear unsuitable to screen microRNA regulated phenotypes, such as HCV replication. [Copyright &y& Elsevier]

Myeloid dendritic cells (MDC) play an important role in antigen-specific immunity and tolerance. In transplantation setting donor-derived MDC are a promising tool to realize donor-specific tolerance. Current protocols enable generation of tolerogenic donor MDC from human monocytes during 1-week cultures. However, for clinical application in transplantation medicine, a rapidly available source of tolerogenic MDC is desired. In this study we investigated whether primary human blood MDC could be transformed into tolerogenic MDC using dexamethasone (dex) and lipopolysaccharide (LPS). Human blood MDC were cultured with dex and subsequently matured with LPS in the presence or absence of dex. Activation of MDC with LPS after pretreatment with dex did not prevent maturation into immunostimulatory MDC. In contrast, simultaneous treatment with dex and LPS yielded tolerogenic MDC, that had a reduced expression of CD86 and CD83, that poorly stimulated allogeneic T-cell proliferation and production of T helper 1 (Th1) cytokines, and primed production of the immunoregulatory cytokine interleukin-10 (IL-10) in T cells. In vitro, however, these tolerogenic MDC did not induce permanent donor-specific hyporesponsiveness in T cells. Importantly, tolerogenic MDC obtained by LPS stimulation in the presence of dex did not convert into immunostimulatory MDC after subsequent activation with different maturation stimuli. In conclusion, these findings demonstrate that combined treatment with dex and LPS transforms primary human blood MDC into tolerogenic MDC that are impaired to stimulate Th1 cytokines, but strongly prime the production of the immunoregulatory cytokine IL-10 in T cells, and are resistant to maturation stimuli. This strategy enables rapid generation of tolerogenic donor-derived MDC for immunotherapy in clinical transplantation. [ABSTRACT FROM AUTHOR]

Summary The tumour necrosis factor (TNF) ligands CD154, CD70 and TNF receptors CD134 and CD137 are all involved in allograft rejection. Because these molecules are not present on resting T cells, we investigated whether immunosuppressive drugs could inhibit their induction. Expression was induced in vitro on T cells by phorbol 12-myristate 13-acetate and ionomycin or by allogeneic dendritic cells in the presence or absence of cyclosporin A (CsA), tacrolimus (TAC), rapamycin derivative (SDZ RAD), or mycophenolic acid (MPA), and determined by flow cytometry. To study the effect of in vivo exposure to immunosuppressive drugs on these molecules, immunohistochemistry was performed on human lymph nodes from patients treated with TAC or TAC and MMF. The calcineurin inhibitors (CI) CsA and TAC strongly suppressed the induction of CD70, CD137 and CD154, but not of CD134, upon pharmacological stimulation of T cells in vitro . In allogeneic stimulations only CD137 and CD154 were inhibited by CI. SDZ RAD did not inhibit pharmacological induction, but in allogeneic stimulations all the investigated molecules were partially suppressed. Both in pharmacological and in allogeneic stimulations, MPA inhibited induction of all tested molecules on T cells nearly completely at 4 µg/ml. However, in lymph nodes obtained from patients chronically treated with MMF and TAC no reduction of the expression of these molecules was observed. This was possibly caused by trough levels which were in vivo lower (mean: 2·3 µg/ml) than the concentration giving complete inhibition in vitro . In conclusion, in contrast to CsA, TAC and SDZ RAD, MPA is a potent inhibitor of the induction of TNF- and TNF-receptor superfamily molecules on T cells. To obtain long-term suppression of these molecules in vivo , a plasma trough level of 4 µg/ml is indicated. [ABSTRACT FROM AUTHOR]

Background & Aims: Extracellular microRNAs (miRNAs) in serum and bile are currently under intense investigation for biomarker purposes in liver disease. However, the directions and pathways by which miRNAs are released from hepatic cells remains largely unknown. Here, we investigated the release of hepatocyte and cholangiocyte-derived miRNAs (HDmiRs and CDmiRs) into blood and bile during various (patho)physiological hepatic conditions., Methods: MiRNA release was analysed using longitudinally collected tissue and paired bile and serum samples (n = 124) that were obtained from liver transplant recipients during follow-up., Results: Cell-type specificity of HDmiRs and CDmiRs was confirmed in liver and common bile duct biopsies (P < 0.001). Analysis of paired bile and serum samples showed up to 20-times higher miRNA-levels in bile compared to serum (P < 0.0001). Fractionation of bile showed the majority of miRNAs being present in the unpelletable supernatant, where protein conjunctions protect miRNAs against degradation (P < 0.0001). During episodes of liver injury and histologically proven rejection in liver transplant recipients, relative HDmiR-levels in bile decreased while its levels in serum increased (P ≤ 0.015). Simultaneously, relative CDmiR-levels in bile significantly increased, while their levels in serum decreased. Related to liver excretory function, a strong positive correlation was observed between HDmiR-122 levels and bilirubin excretion into bile (R = 0.694, P < 0.0001), whereas CDmiRs showed an inverse correlation (P < 0.05)., Conclusion: During impaired excretory function and injury, the liver shows polarized release of extracellular HDmiRs and CDmiRs. This sheds new light on the biology of hepatic miRNA release which is relevant for the interpretation of hepatic miRNAs as biomarkers., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)