Elevated liver enzymes in a German tertiary-care hospital: Distribution, diagnostic steps and diagnosis groups.

BACKGROUND: The determination of liver blood tests is frequently performed in hospitalized patients, and abnormal values require further diagnostics. Yet, analyses considering the management of elevated liver enzymes are missing. Therefore, this study aimed to analyze the distribution of abnormal liver function tests and the subsequent diagnostic steps across different medical specialties. METHODS: From our Hannover liver-injury database, we identified 63,300 cases of patients who were hospitalized between January 2008 and July 2021 with AST or ALT > 3 ULN or AP or TBI > 2 ULN at any time point during hospitalization. Of these, 29,547 cases fulfilled the inclusion criteria and were subjected to further analysis. Cases were analyzed according to the three groups: internal medicine, surgery and others. Analyses were performed regarding baseline characteristics, liver-related diagnostics and factors influencing hospital mortality. RESULTS: Elevated liver blood tests were mainly observed in internal medicine (n=17,762, 60.1%), followed by the surgery department 34.2% (n=10,105). Notably, 40.2% (n=11,896) developed liver enzyme elevation above the cut-offs during the hospital stay. Testing for hepatitis B and C was more often performed in the surgery department compared to in internal medicine. In total, 5.6% of the cases (n=1,640) had a liver biopsy. Hyperbilirubinemia (total bilirubine ≥ 2ULN) and AST/ALT ratios >2 were associated with in-hospital mortality. CONCLUSION: Clinicians are often faced with elevated liver enzymes. However, diagnostic steps differ between different specialties. Physicians should be aware of the increased in-hospital mortality in cases with hyperbilirubinemia or elevated AST/ALT ratios.

Five-year follow-up of 96 weeks peginterferon plus tenofovir disoproxil fumarate in hepatitis D.

BACKGROUND & AIMS: Until recently, pegylated interferon-alfa-2a (PEG-IFNa) therapy was the only treatment option for patients infected with hepatitis D virus (HDV). Treatment with PEG-IFNa with or without tenofovir disoproxil fumarate (TDF) for 96 weeks resulted in HDV RNA suppression in 44% of patients at the end of therapy but did not prevent short-term relapses within 24 weeks. The virological and clinical long-term effects after prolonged PEG-IFNa-based treatment of hepatitis D are unknown. METHODS: In the HIDIT-II study patients (including 40% with liver cirrhosis) received 180 µg PEG-IFNa weekly plus 300 mg TDF once daily (n = 59) or 180 µg PEG-IFNa weekly plus placebo (n = 61) for 96 weeks. Patients were followed until week 356 (5 years after end of therapy). RESULTS: Until the end of follow-up, 16 (13%) patients developed liver-related complications (PEG-IFNa + TDF, n = 5 vs PEG-IFNa + placebo, n = 11; p = .179). Achieving HDV suppression at week 96 was associated with decreased long-term risk for the development of hepatocellular carcinoma (p = .04) and hepatic decompensation (p = .009). Including complications irrespective of PEG-IFNa retreatment status, the number of patients developing serious complications was similar with (3/18) and without retreatment with PEG-IFNa (16/102, p > .999) but was associated with a higher chance of HDV-RNA suppression (p = .024, odds ratio 3.9 [1.3-12]). CONCLUSIONS: Liver-related clinical events were infrequent and occurred less frequently in patients with virological responses to PEG-IFNa treatment. PEG-IFNa treatment should be recommended to HDV-infected patients until alternative therapies become available. Retreatment with PEG-IFNa should be considered for patients with inadequate response to the first course of treatment. CLINICAL TRIAL REGISTRATION: NCT00932971.

An inducible model for genetic manipulation and fate-tracing of PDGFRß-expressing fibrogenic cells in the liver.

Myofibroblasts are the source of extracellular matrix protein during liver fibrogenesis. Fibroblasts, hepatic stellate cells (HSCs) and vascular smooth muscle cells are mesenchymal subpopulations in the liver that are characterized by the expression of PDGFRß and contribute to the pool of these myofibroblasts. Conditional knockout models are important to better understand the function of specific liver cell populations including mesenchymal cells. While there is a limited number of constitutive mouse models for liver mesenchymal cell specific transgene expression, there is no established model for inducible gene targeting in HSCs or PDGFRß-expressing mesenchymal cell populations in the liver. To address this, we investigated whether the tamoxifen inducible PDGFRß-P2A-CreERT2 mouse can be used as a reliable tool to specifically express transgens in liver mesenchymal cells. Our data demonstrate, that PDGFRß-P2A-CreERT2 specifically and efficiently marks over 90% of retinoid positive HSCs in healthy and fibrotic liver in mice upon tamoxifen injection, and that those cells give rise to Col1a1-expressing myofibroblasts in different models of liver fibrosis. Together with a negligible background recombination of only about 0.33%, this confirms that the PDGFRß-P2A-CreERT2 mouse is nearly as efficient as established constitutive LratCre and PDGFRß-Cre mouse models for recombination in HSCs, and that it is a powerful model for mesenchymal liver cell studies that require an inducible Cre approach.

Quality-of-life scores improve after 96 weeks of PEG-IFNa-2a treatment of hepatitis D: An analysis of the HIDIT-II trial.

BACKGROUND & AIMS: Infection with the hepatitis D virus (HDV) causes the most severe form of viral hepatitis with a high risk to develop clinical complications of liver disease. In addition, hepatitis delta has been shown to be associated with worse patient-reported outcomes. Until recently, only pegylated interferon alfa could be used to treat hepatitis delta. METHODS: Here, we investigated quality of life (QOL) as assessed by the Short Form 36 Health Survey (SF-36) in patients undergoing antiviral therapy with pegylated interferon alfa (PEG-IFNa-2a)-based treatment in the HIDIT-II trial. HIDIT-II was a randomized prospective trial exploring PEG-IFNa-2a with tenofovir disoproxil (TDF) or placebo for 96 weeks in patients with compensated hepatitis delta. Surveys completed by 83 study participants before, during, and after treatments were available. RESULTS: Overall, we observed a reduced QOL of HDV patients compared with a reference population, both in physical as well as mental scores. Interestingly, PEG-IFNa-2a treatment showed only minor impairment of the QOL during therapy. Moreover, HDV-RNA clearance was not associated with relevant changes in physical or social SF-36 scores, whereas an improvement of fibrosis during treatment was associated with increased QOL. Overall, slight improvements of the QOL scores were observed 24 weeks after the end of treatment as compared with baseline. TDF co-treatment had no influence on QOL. CONCLUSIONS: Overall, our findings suggest that PEG-IFNa-2a was reasonably tolerated even over a period of 96 weeks by hepatitis D patients reporting SF-36 questionnaires. Of note, several patients may benefit from PEG-IFNa-2a-based therapies with off-treatment improvements in quality of life.

Out of sight for the endoscopist? Gastrointestinal bleeding after aortic repair.

BACKGROUND AND STUDY AIM: Secondary Aortoenteric Fistulas (sAEF) are difficult to diagnose and usually result in fatal gastrointestinal (GI) bleeding following aortic repair. Outcomes are largely dependent on a timely diagnosis, but AEFs remain challenging to identify endoscopically and are usually diagnosed on computed tomography (CT) scans. The aim of our study was optimize diagnosis of AEF by identifying patients developing GI bleeding after aortic repair, investigate their clinical course and identify factors specific to different bleeding sources. METHODS: A retrospective, single-center study capturing all patients developing upper or lower GI bleeding after aortic surgery between January 2009 and March 2020 was performed. Electronic health records were screened for diagnostic codes of the relevant procedures. Bleeding was classified into three groups: AEF with demonstrable fistula, ischemic - macroscopic ulceration plus histological confirmation or imaging and "other" due to other recognized conventional cause, such as peptic ulcer disease. RESULTS: 47 GI bleeding episodes in 39 patients were identified. Of these, 10 episodes (21%) were caused by AEF, 16 (34%) by ischemic ulceration and 21 (45%) due to other causes. Patients with AEF exhibited more frequent hemodynamic instability requiring vasopressors and had higher mortality, while ischemic ulcerations were associated with more recent operation or hypotensive episode. CONCLUSIONS: GI bleeding complications are uncommon following aortic surgery. AEF and ischemic ulceration are however frequent bleeding causes in this cohort. In patients presenting with fulminant bleeding, primary CT-scanning should be considered.

The purinergic P2Y14 receptor links hepatocyte death to hepatic stellate cell activation and fibrogenesis in the liver.

Fibrosis contributes to ~45% of deaths in western countries. In chronic liver disease, fibrosis is a major factor determining outcomes, but efficient antifibrotic therapies are lacking. Although platelet-derived growth factor and transforming growth factor-ß constitute key fibrogenic mediators, they do not account for the well-established link between cell death and fibrosis in the liver. Here, we hypothesized that damage-associated molecular patterns (DAMPs) may link epithelial cell death to fibrogenesis in the injured liver. DAMP receptor screening identified purinergic receptor P2Y14 among several candidates as highly enriched in hepatic stellate cells (HSCs), the main fibrogenic cell type of the liver. Conversely, P2Y14 ligands uridine 5'-diphosphate (UDP)-glucose and UDP-galactose were enriched in hepatocytes and were released upon different modes of cell death. Accordingly, ligand-receptor interaction analysis that combined proteomic and single-cell RNA sequencing data revealed P2Y14 ligands and P2Y14 receptor as a link between dying cells and HSCs, respectively. Treatment with P2Y14 ligands or coculture with dying hepatocytes promoted HSC activation in a P2Y14-dependent manner. P2Y14 ligands activated extracellular signal-regulated kinase (ERK) and Yes-associated protein (YAP) signaling in HSCs, resulting in ERK-dependent HSC activation. Global and HSC-selective P2Y14 deficiency attenuated liver fibrosis in multiple mouse models of liver injury. Functional expression of P2Y14 was confirmed in healthy and diseased human liver and human HSCs. In conclusion, P2Y14 ligands and their receptor constitute a profibrogenic DAMP pathway that directly links cell death to fibrogenesis.

Pulmonary Arterial Hypertension and Consecutive Right Heart Failure Lead to Liver Fibrosis.

Hepatic congestion occurs in patients with right heart failure and can ultimately lead to liver fibrosis or cardiac cirrhosis. Elevated pulmonary arterial pressure is found in patients with hepatic congestion. However, whether pulmonary arterial hypertension (PAH) can be a cause of liver fibrosis is unknown. The aim of this study was to investigate whether rats in the SuHx model with severe PAH develop liver fibrosis and to explore the mechanisms of congestive hepatic fibrosis both in rats and humans. To achieve this, PAH was induced in six to eight-week old male Sprague Dawley rats by a single subcutaneous injection of the VEGFR 2 inhibitor SU5416 and subsequent hypoxia for 3 weeks, followed by a 6-week period in room air. SuHx-exposed rats developed severe PAH, right ventricular hypertrophy (RVH), and consecutive right ventricular failure. Cardiac magnetic resonance imaging (MRI) and histological analysis revealed that PAH rats developed both hepatic congestion and liver fibrosis. Gene set enrichment analysis (GSEA) of whole liver RNA sequencing data identified a hepatic stellate cell specific gene signature in PAH rats. Consistently, tissue microarray from liver of patients with histological evidence of hepatic congestion and underlying heart disease revealed similar fibrogenic gene expression patterns and signaling pathways. In conclusion, severe PAH with concomitant right heart failure leads to hepatic congestion and liver fibrosis in the SU5416/hypoxia rat PAH model. Patients with PAH should therefore be screened for unrecognized liver fibrosis.

Tumor restriction by type I collagen opposes tumor-promoting effects of cancer-associated fibroblasts.

Cancer-associated fibroblasts (CAF) may exert tumor-promoting and tumor-suppressive functions, but the mechanisms underlying these opposing effects remain elusive. Here, we sought to understand these potentially opposing functions by interrogating functional relationships among CAF subtypes, their mediators, desmoplasia, and tumor growth in a wide range of tumor types metastasizing to the liver, the most common organ site for metastasis. Depletion of hepatic stellate cells (HSC), which represented the main source of CAF in mice and patients in our study, or depletion of all CAF decreased tumor growth and mortality in desmoplastic colorectal and pancreatic metastasis but not in nondesmoplastic metastatic tumors. Single-cell RNA-Seq in conjunction with CellPhoneDB ligand-receptor analysis, as well as studies in immune cell-depleted and HSC-selective knockout mice, uncovered direct CAF-tumor interactions as a tumor-promoting mechanism, mediated by myofibroblastic CAF-secreted (myCAF-secreted) hyaluronan and inflammatory CAF-secreted (iCAF-secreted) HGF. These effects were opposed by myCAF-expressed type I collagen, which suppressed tumor growth by mechanically restraining tumor spread, overriding its own stiffness-induced mechanosignals. In summary, mechanical restriction by type I collagen opposes the overall tumor-promoting effects of CAF, thus providing a mechanistic explanation for their dual functions in cancer. Therapeutic targeting of tumor-promoting CAF mediators while preserving type I collagen may convert CAF from tumor promoting to tumor restricting.

[Severe epigastric pain in a 59-year-old patient]. / Massivste epigastrische Schmerzen bei einem 59-jährigen Patienten.

Abdominal pain is a frequent cause of consultation to doctors' offices and emergency rooms. The most common differential diagnoses can be confirmed with readily available, cost-effective, and low-risk diagnostic tools such as laboratory tests, ultrasound, or gastroscopy. Additional diagnostic tests are required to exclude rare causes such as small, solid, or hematological malignancies, metabolic disorders, or polyneuropathies of varying origin. In the following, we present the case of a patient with severe epigastric pain due to neuroborreliosis, and recapitulate the diagnostic steps for clarifying abdominal pain using this example.

T cell receptor repertoires within liver allografts are different to those in the peripheral blood.

BACKGROUND & AIMS: T cells are the main mediators of allogeneic immune responses. Specific T cell clones can be tracked by their unique T cell receptor (TCR), but specificity and function remain elusive and have not been investigated in human liver biopsies thus far. METHODS: TCR repertoire analysis of CD4+, CD8+, and regulatory T cells of the peripheral blood and liver graft was performed in 7 liver transplant recipients with either stable course (non-rejector, NR), subclinical cellular rejection (SCR), or acute cellular rejection (ACR) during an observation period from pre-transplant to 6 years post-transplant. Furthermore, donor-reactive T cells, identified by their expression of CD154 and glycoprotein A repetitions predominant (GARP) after allogeneic activation, were tracked longitudinally in peripheral blood and within the liver allograft. RESULTS: Although overall clonality of the TCR repertoire did not increase in peripheral blood after liver transplantation, clonality of donor-reactive CD4+ and regulatory T cells increased and these clones accumulated within the liver graft. Surprisingly, the TCR repertoires between the liver graft and the periphery were distinct and showed only limited overlap. Notably, during ACR, TCR repertoires aligned suggesting either graft-specific homing or release of activated T cells from the graft. CONCLUSIONS: This is the first study comparing TCR repertoires between liver grafts and blood in patients with NR, SCR, and ACR. Moreover, we attribute specificity and function to a subgroup of intragraft T cell populations. Given the limited overlap between peripheral blood and intragraft repertoires, future studies investigating function and specificities of T cells after liver transplantation should focus on the intragraft immune response. LAY SUMMARY: In solid organ transplantation, T cells are key mediators of the recipient's immune response directed at the transplanted organ. In our study, we characterised the T cell repertoire in a cohort of 7 liver transplant recipients. We demonstrate that donor-specific T cells expand clonally and accumulate in the transplanted liver. Moreover, we show that the composition of T cells in peripheral blood differs from the T cells in the liver allograft, only aligning in the context of acute cellular rejection but not in normal graft or subclinical cellular rejection. This indicates that the intragraft immune response is not mirrored in the peripheral blood. Our findings clarify the importance of protocol liver biopsies in identifying intragraft immune responses for future investigations of allo-directed immune responses.

c-Rel orchestrates energy-dependent epithelial and macrophage reprogramming in fibrosis.

Fibrosis is a common pathological feature of chronic disease. Deletion of the NF-κB subunit c-Rel limits fibrosis in multiple organs, although the mechanistic nature of this protection is unresolved. Using cell-specific gene-targeting manipulations in mice undergoing liver damage, we elucidate a critical role for c-Rel in controlling metabolic changes required for inflammatory and fibrogenic activities of hepatocytes and macrophages and identify Pfkfb3 as the key downstream metabolic mediator of this response. Independent deletions of Rel in hepatocytes or macrophages suppressed liver fibrosis induced by carbon tetrachloride, while combined deletion had an additive anti-fibrogenic effect. In transforming growth factor-ß1-induced hepatocytes, c-Rel regulates expression of a pro-fibrogenic secretome comprising inflammatory molecules and connective tissue growth factor, the latter promoting collagen secretion from HMs. Macrophages lacking c-Rel fail to polarize to M1 or M2 states, explaining reduced fibrosis in RelΔLysM mice. Pharmacological inhibition of c-Rel attenuated multi-organ fibrosis in both murine and human fibrosis. In conclusion, activation of c-Rel/Pfkfb3 in damaged tissue instigates a paracrine signalling network among epithelial, myeloid and mesenchymal cells to stimulate fibrogenesis. Targeting the c-Rel-Pfkfb3 axis has potential for therapeutic applications in fibrotic disease.

The PNPLA3 rs738409 GG genotype is associated with poorer prognosis in 239 patients with autoimmune hepatitis.

BACKGROUND: Fibrosis progression in autoimmune hepatitis can be attenuated by immunosuppressive treatment; however, some patients progress despite therapy. Single nucleotide polymorphisms (SNPs) such as PNPLA3-rs738409, TM6SF2-rs58542926 and MBOAT7-rs641738 are associated with non-alcoholic fatty liver disease and fibrosis progression, whereas a splice variant in HSD17B13-rs72613567:TA has been shown to be protective. AIM: To analyse the impact of different SNPs on the long-term outcome of patients with autoimmune hepatitis. METHODS: We included 239 patients into this study who had been treated between 1983 and 2018 for autoimmune hepatitis. Genomic DNA was isolated from whole blood and SNPs were determined by PCR analysis. Liver biopsies were available for 215/239 patients (90%). Clinical and laboratory patient data were assessed by chart review. RESULTS: Mean age at baseline was 42.1 years with 74.1% being female. The median follow-up was 9.4 years (IQR 3.5-15.0), 11.7% of the patients (n = 28) died or required liver transplantation. In the Kaplan-Meier analysis of the combined endpoint time to liver transplantation or death, we observed that patients with the PNPLA3-rs738409 GG variant met more frequently the primary endpoint (P = 0.005). In Cox regression analysis PNPLA3-rs738409 GG as well as liver cirrhosis were identified as strong predictors for time to liver transplantation or death (HR 4.5 [CI 1.48-13.72], P = 0.008 and HR 9.24 [CI 2.11-40.44], P = 0.003, respectively). Neither steatosis, diabetes mellitus nor obesity were associated with outcome. CONCLUSIONS: PNPLA3-rs738409 variant GG is a predictor for time to liver transplantation or death and may help to identify autoimmune hepatitis patients at risk for disease progression.

Peginterferon alfa-2a plus tenofovir disoproxil fumarate for hepatitis D (HIDIT-II): a randomised, placebo controlled, phase 2 trial.

BACKGROUND: Hepatitis D is the most severe form of chronic viral hepatitis. Treatment guidelines recommend 1 year of peginterferon alfa, which is effective in 25-30% of patients only. Whether prolonged therapy with peginterferon alfa-2a for 96 weeks and combination therapy with tenofovir disoproxil fumarate (TDF) would increase hepatitis D virus (HDV) RNA suppression is unknown. We aimed to explore whether prolonged treatment of HDV with 96 weeks of peginterferon would increase HDV RNA response rates and reduces post-treatment relapses. METHODS: We did two parallel, investigator-initiated, multicentre, double-blind randomised, controlled trials at 14 study sites in Germany, Greece, Romania, and Turkey. Patients with chronic HDV infection and compensated liver disease who were aged 18 years or older were eligible for inclusion. All patients were HBsAg positive for at least 7 months, anti-HDV positive for at least 3 months, and HDV-RNA positive at the local laboratory at the screening visit. Patients were ineligible if alanine aminotransferase levels were higher than ten times above the upper limit of normal and if platelet counts were lower than 90 000 per µL, or if they had received interferon therapy or treatment with a nucleoside and nucleotide analogue within the preceding 6 months. Patients were randomly assigned by blinded stratified block randomisation (1:1) to receive 180 µg of peginterferon alfa-2a weekly plus either TDF (300 mg once daily) or placebo for 96 weeks. The primary endpoint was the percentage of patients with undetectable HDV RNA at the end of treatment assessed by intention to treat. The trials are registered as NCT00932971 and NCT01088659. FINDINGS: Between June 24, 2009, and Feb 28, 2011, we randomly assigned 59 HDV RNA-positive patients to receive peginterferon alfa-2a plus TDF and 61 to receive peginterferon alfa-2a plus placebo, including 48 (40%) patients with cirrhosis to the two treatment groups (23 in the peginterferon alfa-2a plus TDF group and 25 in the peginterferon alfa-2a plus placebo group). The primary endpoint was achieved in 28 (48%) of 59 patients in the peginterferon alfa-2a plus TDF group and in 20 (33%) of 61 patients in the peginterferon alfa-2a plus placebo group (odds ratio 1·84, 95% CI 0·86-3·91, p=0·12). We recorded 944 adverse events (459 in the peginterferon alfa-2a plus TDF group and 485 in the peginterferon alfa-2a plus placebo group). The most common adverse events were haematological, behavioural (eg, fatigue), musculoskeletal, influenza-like syndromes, and psychiatric complaints. INTERPRETATION: Addition of TDF resulted in no significant improvement in HDV RNA response rates at the end of treatment. These findings highlight that alternative treatment options are needed for hepatitis D. FUNDING: The HepNet Study-House (a project of the German Liver Foundation founded by the German Liver Foundation, the German Ministry for Education and Research, and the German Center for Infectious Disease Research), Hoffmann-La Roche, and Gilead Sciences.

Cholemic Nephropathy Causes Acute Kidney Injury and Is Accompanied by Loss of Aquaporin 2 in Collecting Ducts.

Impairment of renal function often occurs in patients with liver disease. Hepatorenal syndrome is a significant cause of acute kidney injury (AKI) in patients with cirrhosis (HRS-AKI, type 1). Causes of non-HRS-AKI include cholemic nephropathy (CN), a disease that is characterized by intratubular bile casts and tubular injury. As data on patients with CN are obtained primarily from case reports or autopsy studies, we aimed to investigate the frequency and clinical course of CN. We identified 149 patients who underwent kidney biopsy between 2000 and 2016 at the Department of Gastroenterology, Hepatology and Endocrinology at Hannover Medical School. Of these, 79 had a history of liver disease and deterioration of renal function. When applying recent European Association for the Study of the Liver criteria, 45 of 79 patients (57%) presented with AKI, whereas 34 patients (43%) had chronic kidney disease (CKD). Renal biopsy revealed the diagnosis of CN in 8 of 45 patients with AKI (17.8%), whereas none of the patients with CKD was diagnosed with CN. Univariate analysis identified serum bilirubin, alkaline phosphatase, and urinary bilirubin and urobilinogen as predictive factors for the diagnosis of CN. Histological analysis of AKI patients with normal bilirubin, elevated bilirubin, and the diagnosis of CN revealed loss of aquaporin 2 (AQP2) expression in collecting ducts in patients with elevated bilirubin and CN. Biopsy-related complications requiring medical intervention occurred in 4 of 79 patients (5.1%). Conclusion: CN is a common finding in patients with liver disease, AKI, and highly elevated bilirubin. Loss of AQP2 in AKI patients with elevated bilirubin and CN might be the result of toxic effects of cholestasis and in part be responsible for the impairment of renal function.

Opposite roles of cannabinoid receptors 1 and 2 in hepatocarcinogenesis.

OBJECTIVE: The endocannabinoid system (ECS) exerts key roles in the development of liver fibrosis and fatty liver, two diseases that promote the development of hepatocellular carcinoma (HCC). Although cannabinoids exert potent antitumour effects in vitro, the contribution of the ECS to carcinogenesis in vivo remains elusive. DESIGN: Expression of key components of the ECS, including endocannanabinoids, endocannabinoid-degrading enzymes and endocannabinoid receptors, was determined in healthy liver and tumours. Diethylnitrosamine-induced hepatocarcinogenesis was determined in mice deficient in fatty acid amide hydrolase (FAAH), the main anandamide (AEA)-degrading enzyme, in cannabinoid receptor (CB)1, CB2, or transient receptor potential cation channel subfamily V member 1 (TRPV1)-deficient mice. RESULTS: Murine and human HCCs displayed activation of the ECS with strongly elevated expression of CB1 and CB2 but only moderately altered endocannabinoid levels. Contrary to the antitumour effects of cannabinoids in vitro, we observed increased hepatocarcinogenesis in FAAH-deficient mice, a mouse model with increased AEA levels. Accordingly, inactivation of CB1, the main receptor for AEA, in wild-type or FAAH-deficient mice suppressed hepatocarcinogenesis. In contrast, inactivation of CB2 increased hepatocarcinogenesis. CB1 was strongly expressed within HCC lesions and its inactivation suppressed proliferation and liver fibrosis. CB2 was predominantly expressed in macrophages. CB2 inactivation decreased the expression of T-cell-recruiting chemokines and inhibited hepatic T-cell recruitment including particular CD4+ T cells, a population with known antitumour effects in HCC. TRPV1 deletion did not alter HCC development. CONCLUSIONS: Similar to their role in fibrogenesis, CB1 and CB2 exert opposite effects on hepatocarcinogenesis and may provide novel therapeutic targets.

Contribution of Underlying Connective Tissue Cells to Taste Buds in Mouse Tongue and Soft Palate.

Taste buds, the sensory organs for taste, have been described as arising solely from the surrounding epithelium, which is in distinction from other sensory receptors that are known to originate from neural precursors, i.e., neural ectoderm that includes neural crest (NC). Our previous study suggested a potential contribution of NC derived cells to early immature fungiform taste buds in late embryonic (E18.5) and young postnatal (P1-10) mice. In the present study we demonstrated the contribution of the underlying connective tissue (CT) to mature taste buds in mouse tongue and soft palate. Three independent mouse models were used for fate mapping of NC and NC derived connective tissue cells: (1) P0-Cre/R26-tdTomato (RFP) to label NC, NC derived Schwann cells and derivatives; (2) Dermo1-Cre/RFP to label mesenchymal cells and derivatives; and (3) Vimentin-CreER/mGFP to label Vimentin-expressing CT cells and derivatives upon tamoxifen treatment. Both P0-Cre/RFP and Dermo1-Cre/RFP labeled cells were abundant in mature taste buds in lingual taste papillae and soft palate, but not in the surrounding epithelial cells. Concurrently, labeled cells were extensively distributed in the underlying CT. RFP signals were seen in the majority of taste buds and all three types (I, II, III) of differentiated taste bud cells, with the neuronal-like type III cells labeled at a greater proportion. Further, Vimentin-CreER labeled cells were found in the taste buds of 3-month-old mice whereas Vimentin immunoreactivity was only seen in the CT. Taken together, our data demonstrate a previously unrecognized origin of taste bud cells from the underlying CT, a conceptually new finding in our knowledge of taste bud cell derivation, i.e., from both the surrounding epithelium and the underlying CT that is primarily derived from NC.

Hepatocellular carcinoma originates from hepatocytes and not from the progenitor/biliary compartment.

In many organs, including the intestine and skin, cancers originate from cells of the stem or progenitor compartment. Despite its nomenclature, the cellular origin of hepatocellular carcinoma (HCC) remains elusive. In contrast to most organs, the liver lacks a defined stem cell population for organ maintenance. Previous studies suggest that both hepatocytes and facultative progenitor cells within the biliary compartment are capable of generating HCC. As HCCs with a progenitor signature carry a worse prognosis, understanding the origin of HCC is of clinical relevance. Here, we used complementary fate-tracing approaches to label the progenitor/biliary compartment and hepatocytes in murine hepatocarcinogenesis. In genotoxic and genetic models, HCCs arose exclusively from hepatocytes but never from the progenitor/biliary compartment. Cytokeratin 19-, A6- and α-fetoprotein-positive cells within tumors were hepatocyte derived. In summary, hepatocytes represent the cell of origin for HCC in mice, and a progenitor signature does not reflect progenitor origin, but dedifferentiation of hepatocyte-derived tumor cells.