Background:Quantitative liver T1 mapping is a promising noninvasive biomarker for diffuse liver disease, but it is influenced by physiological variability. Hydration alters tissue water content and perfusion, yet its effect on liver water-specific T1 (wT1) remains poorly characterized, particularly across liver segments. Prior studies relied on single-slice acquisitions, limiting assessment of spatial heterogeneity. The objective is to assess hydration-related changes in liver wT1 across all Couinaud segments using an accelerated multi-slice technique and to compare results with single-slice T1-modified Look-Locker inversion recovery (T1-MOLLI) and vibration-controlled transient elastography (VCTE). Methods:Twenty-nine healthy adults underwent blood sampling, VCTE, and liver magnetic resonance imaging (MRI) after an ≥8-hour fast without fluid intake and again after ingestion of 1 L of water followed by a 1-hour equilibration period. Multi-slice wT1 mapping was performed using a Dixon-based continuous inversion-recovery Look-Locker (CIR-LL) sequence covering the entire liver in a single breath-hold. Single-slice T1-MOLLI and whole-liver proton density fat fraction (PDFF) and T2* mapping were acquired for comparison. Regions of interest (ROIs) were placed on PDFF, T2*, and wT1 maps in all liver segments. Statistical analysis included intraclass correlation coefficient (ICC; [2, 1]), linear regression, Pearson correlation coefficients Bland-Altman plots and paired two-sided t-tests. Results:Hydration resulted in a higher global increase in mean liver wT1 (before: 773.4±63.2 ms, after: 800.3±66 ms) than T1-MOLLI (before: 853±68.8 ms, after: 861.6±55.9 ms). PDFF, T2*, and liver stiffness varied modestly within the physiological range. For liver stiffness, T1-MOLLI, and wT1, measurements obtained before and after hydration showed good agreement, with wT1 (y=0.9x+80.5, r=0.89, P<0.001) exhibiting a regression coefficient closer to that of liver stiffness (y=0.9x+0.7, r=0.63, P<0.001) than T1-MOLLI (y=0.6x+372.4, r=0.71, P<0.001). T1-MOLLI and wT1 showed good agreement under both hydration conditions (before: y=0.5x+355.7, r=0.64, after: y=0.8x+98.9, r=0.78), with T1-MOLLI yielding systematically higher values than wT1. Paired analysis demonstrated significant hydration-related changes in wT1 (P<0.001), with segment-wise wT1 increases remaining significant after correction for multiple testing. Furthermore, wT1 revealed spatial heterogeneity across liver segments. Conclusions:Liver wT1 is physiologically modulated by hydration and exhibits spatial heterogeneity across liver segments, even in the healthy liver. These findings underscore the importance of whole-liver, segment-resolved wT1 mapping and physiological standardization when interpreting quantitative liver MRI.

In pulmonary fibrosis lung tissue is thickened and scarred, and the lungs become progressively stiffer and smaller, leading to low levels of blood oxygen and shortness of breath. Lung fibrosis is not curable and life expectancy is reduced. Fibrosis is characterized by an increased accumulation of extracellular matrix (ECM) proteins such as collagen and elastin. ECM proteins are degraded predominantly by matrix metalloproteinases (MMPs). Here, we show that the lysosomal cation channel TRPML1, which causes the lysosomal storage disorder mucolipidosis type IV (MLIV) when mutated or lost, regulates the levels of MMPs in the ECM of mouse airways, modulating exocytosis of MMP2, 8, 9, 12, and 19, which mediate collagen/elastin degradation. While TRPML1 loss reduces MMP levels in lung macrophage and fibroblast supernatants, small molecule activation of TRPML1 results in increased levels. MLIV mice display a fibrosis-like lung phenotype similar to the phenotype evoked by bleomycin. We thus identify TRPML1 as a regulator of MMP release in the lung with loss of TRPML1 resulting in lung fibrosis due to excessive extracellular collagen and elastin accumulation.

BACKGROUND & AIMS:Mucosal-associated invariant T (MAIT) cells constitute a highly abundant innate-like T-cell population in the human liver that is critical for immune surveillance of hepatic cancers. However, MAIT cells are often dysfunctional in human hepatocellular carcinoma (HCC), for reasons that remain unclear. Here, we aimed to identify the mechanisms driving MAIT cell dysfunction in metabolic dysfunction-associated steatotic liver disease (MASLD), a chronic liver condition that predisposes patients to HCC. METHODS:We studied MAIT cell functionality, metabolism and anti-cancer activity directly ex vivo in patients with MASLD, as well as in co-culture models mimicking MASLD. (Single-cell) RNA-sequencing was used to translate findings into clinical cohorts of patients with MASLD and MASLD-associated HCC. RESULTS:We found that MAIT cells lose their effector functions in patients with MASLD and uncover that this dysfunction is driven by MASLD-associated polyunsaturated fatty acids (PUFAs), which selectively accumulate in MAIT cells but not in conventional CD8+ T cells or NK cells. Mechanistically, PUFAs drive MAIT cell dysfunction through intracellular formation of lipid peroxides that promote a state of 'metabolic exhaustion' characterised by compromised mitochondrial respiration and glycolysis in MAIT cells. Excessive signalling through this MASLD-PUFA-lipid peroxide axis results in MAIT cell death by ferroptosis. Interference with PUFA-induced lipid peroxide formation in MAIT cells reversed their metabolic exhaustion and prevented ferroptotic MAIT cell death, thereby restoring MAIT cell effector function and anti-cancer activity. In patients with HCC, high expression of the MAIT cell-PUFA gene signature that was linked to MAIT cell dysfunction was associated with poor survival. CONCLUSIONS:Our findings identify a novel immunometabolic axis that impairs MAIT cell-mediated anti-cancer immunity in MASLD and may represent a targetable pathway to enhance the effectiveness of immunotherapy. IMPACT AND IMPLICATIONS:In this study, we identify a novel immunometabolic axis in which polyunsaturated fatty acids, accumulating in liver tissue in MASLD (metabolic dysfunction-associated steatotic liver disease), drive MAIT (mucosal-associated invariant T) cell dysfunction through lipid peroxide-induced metabolic exhaustion and ferroptosis, ultimately impairing their anti-tumour activity. These findings reveal how MASLD creates an immune-permissive environment that may facilitate hepatocellular carcinoma development and progression and prevent effective immunotherapy. Targeting the polyunsaturated fatty acid-lipid peroxide axis could restore MAIT cell function and enhance current immunotherapeutic anti-cancer strategies.

Ductular reaction (DR) is the hallmark of cholestatic diseases manifested in the proliferation of bile ductules lined by biliary epithelial cells (BECs). It is commonly associated with an increased risk of fibrosis and liver failure. The receptor for advanced glycation end products (RAGE) was identified as a critical mediator of DR during chronic injury. Yet, the direct link between RAGE-mediated DR and fibrosis as well as the mode of interaction between BECs and hepatic stellate cells (HSCs) to drive fibrosis remain elusive. Here, we delineate the specific function of RAGE on BECs during DR and its potential association with fibrosis in the context of cholestasis. Employing a biliary lineage tracing cholestatic liver injury mouse model, combined with whole transcriptome sequencing and in vitro analyses, we reveal a role for BEC-specific Rage activity in fostering a pro-fibrotic milieu. RAGE is predominantly expressed in BECs and contributes to DR. Notch ligand Jagged1 is secreted from activated BECs in a Rage-dependent manner and signals HSCs in trans, eventually enhancing fibrosis during cholestasis.

Peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE is an approved treatment for metastatic neuroendocrine tumors (NETs). Although the therapy is effective, hematologic toxicity, particularly leukopenia, remains a significant concern. The spleen, which accumulates radiolabeled somatostatin analogs, may play a critical role in modulating this toxicity. This study investigates whether patients undergoing PRRT after splenectomy exhibit lower hematologic toxicity. Methods: This multicenter retrospective study included 68 patients with metastatic NETs treated with PRRT between 2009 and 2022. Splenectomized patients (n = 34) were matched to nonsplenectomized patients on the basis of age, sex, tumor location, grading, metastatic pattern, and treatment cycles. Hematologic parameters (leukocytes, lymphocytes, neutrophils, hemoglobin, and platelets) were assessed at baseline and 12 and 24 mo after PRRT. Hematotoxicity was graded using Common Terminology Criteria for Adverse Events. Statistical analyses included t test, Mann-Whitney U test, and Fisher exact test, with an α of 0.05 and Bonferroni adjustment applied. Results: Splenectomized patients had significantly lower rates of leukopenia, with a mean decline of 12.8% in leukocyte count at 24 mo versus 47.2% in nonsplenectomized patients (P < 0.001), and a higher median absolute leukocyte count (7.2 vs. 4.2 × 10³/mm³, P < 0.001). Leukopenia occurred in 2 splenectomized patients compared with 20 in the control group (P < 0.001). Lymphocyte decline was also less pronounced, with higher absolute counts at 24 mo. Platelet counts were consistently higher postsplenectomy, although relative changes over time were not significant. Neutrophil counts and hemoglobin levels remained comparable between groups. Conclusion: Splenectomy appears to reduce leukopenia and improve hematologic tolerability in NET patients undergoing PRRT, highlighting the spleen's role in leukocyte regulation. These patients may better tolerate intensified PRRT regimens, including additional cycles or reinduction, with minimal toxicity. This is particularly relevant for patients with pancreatic NETs, who frequently undergo splenectomy and face a poorer prognosis. Prospective studies are needed to further clarify the spleen's impact on PRRT-related hematotoxicity and guide treatment optimization.

BACKGROUND AND AIM:Patients with liver cirrhosis often face a grave threat from infected ascites (IA). However, a well-established prognostic model for this complication has not been established in routine clinical practice. Therefore, we aimed to assess mortality risk in patients with liver cirrhosis and IA. METHODS:We conducted a retrospective study across three tertiary hospitals, enrolling 534 adult patients with cirrhotic liver and IA, comprising 465 with spontaneous bacterial peritonitis (SBP), 34 with bacterascites (BA), and 35 with secondary peritonitis (SP). To determine the attributable mortality risk linked to IA, these patients were matched with 122 patients with hydropic decompensated liver cirrhosis but without IA. Clinical, laboratory, and microbiological parameters were assessed for their relation to mortality using univariable analyses and a multivariable random forest model (RFM). Least absolute shrinkage and selection operator (Lasso) regression model was used to establish an easy-to-use mortality prediction score. RESULTS:The in-hospital mortality risk was highest for SP (39.0%), followed by SBP (26.0%) and BA (25.0%). Besides illness severity markers, microbiological parameters, such as Candida spp., were identified as the most significant indicators for mortality. The Lasso model determined 15 parameters with corresponding scores, yielding good discriminatory power (area under the receiver operating characteristics curve = 0.89). Counting from 0 to 83, scores of 20, 40, 60, and 80 corresponded to in-hospital mortalities of 3.3%, 30.8%, 85.2%, and 98.7%, respectively. CONCLUSION:We developed a promising mortality prediction score for IA, highlighting the importance of microbiological parameters in conjunction with illness severity for assessing patient outcomes.

Background & Aims: Although most hepatocellular carcinoma (HCC) cases are driven by hepatitis and cirrhosis, a subset of patients with chronic hepatitis B develop HCC in the absence of advanced liver disease, indicating the oncogenic potential of hepatitis B virus (HBV). We investigated the role of HBV transcripts and proteins on HCC development in the absence of inflammation in HBV-transgenic mice. Methods: HBV-transgenic mice replicating HBV and expressing all HBV proteins from a single integrated 1.3-fold HBV genome in the presence or absence of wild-type HBx (HBV1.3/HBVxfs) were analyzed. Flow cytometry, molecular, histological and in vitro analyses using human cell lines were performed. Hepatocyte-specific Stat3- and Socs3-knockout was analyzed in HBV1.3 mice. Results: Approximately 38% of HBV1.3 mice developed liver tumors. Protein expression patterns, histology, and mutational landscape analyses indicated that tumors resembled human HCC. HBV1.3 mice showed no signs of active hepatitis, except STAT3 activation, up to the time point of HCC development. HBV-RNAs covering HBx sequence, 3.5-kb HBV RNA and HBxprotein were detected in HCC tissue. Interestingly, HBVxfs mice expressing all HBV proteins except a C-terminally truncated HBx (without the ability to bind DNA damage binding protein 1) showed reduced signs of DNA damage response and had a significantly reduced HCC incidence. Importantly, intercrossing HBV1.3 mice with a hepatocyte-specific STAT3-knockout abrogated HCC development. Conclusions: Expression of HBV-proteins is sufficient to cause HCC in the absence of detectable inflammation. This indicates the oncogenic potential of HBV and in particular HBx. In our model, HBV-driven HCC was STAT3 dependent. Our study highlights the immediate oncogenic potential of HBV, challenging the idea of a benign highly replicative phase of HBV infection and indicating the necessity for an HBV 'cure'.

177Lu-DOTATATE therapy is an effective treatment for advanced neuroendocrine tumors, despite its dose-limiting hematotoxicity. Herein, the significance of off-target splenic irradiation is unknown. Our study aims to identify predictive markers of peptide receptor radionuclide therapy-induced leukopenia. Methods: We retrospectively analyzed blood counts and imaging data of 88 patients with histologically confirmed, unresectable metastatic neuroendocrine tumors who received 177Lu-DOTATATE treatment at our institution from February 2009 to July 2021. Inclusion criterium was a tumor uptake equivalent to or greater than that in the liver on baseline receptor imaging. We excluded patients with less than 24 mo of follow-up and those patients who received fewer than 4 treatment cycles, additional therapies, or blood transfusions during follow-up. Results: Our study revealed absolute and relative white blood cell counts and relative spleen volume reduction as independent predictors of radiation-induced leukopenia at 24 mo. However, a 30% decline in spleen volume 12 mo after treatment most accurately predicted patients proceeding to leukopenia at 24 mo (receiver operating characteristic area under the curve of 0.91, sensitivity of 0.93, and specificity of 0.90), outperforming all other parameters by far. Conclusion: Automated splenic volume assessments demonstrated superior predictive capabilities for the development of leukopenia in patients undergoing 177Lu-DOTATATE treatment compared with conventional laboratory parameters. The reduction in spleen size proves to be a valuable, routinely available, and quantitative imaging-based biomarker for predicting radiation-induced leukopenia. This suggests potential clinical applications for risk assessment and management.

Background Chronic cholestatic liver injury is linked to inflammation, the emergence of ductular reactions and fibrosis. While expression of CD44, a cellular adhesion molecule, is associated with liver fibrosis in different animal models, it remains unclear if CD44 has a functional role in the processes culminating in the development of hepatic fibrosis. In this study, we investigated the role of CD44 in chronic cholestatic liver injury in Mdr2-/- mice.

Ductular reactions inevitably co-occur with liver tissue injury along with inflammation, cholestasis, and fibrosis. However, it remains unknown whether they represent an adaptive response facilitating bile drainage, or if they exacerbate dysfunction. By using a reporter mouse with cholangiocyte-specific deletion of the pattern recognition receptor RAGE, specific effects of the DR could be differentiated from the consequences of the cytotoxicity of the CDE-diet. While CDE-diet induced hepatoxicity triggers the DR via RAGE-dependent DAMP-sensing on cholangiocytes, it does not itself lead to loss of liver function. Instead, the presence of DR causes downregulation of basolateral bile acid transporters. Thus, although the DR forms a contiguous network capable of draining bile, it remains unutilized due to interrupted bile acid transport from blood to hepatocytes. The de-differentiating influence of the DR on hepatocytes thereby results in cholestasis and eventual fibrosis, that are more insidious to liver function than its initial cytotoxic trigger.

It is currently not well known how necroptosis and necroptosis responses manifest in vivo. Here, we uncovered a molecular switch facilitating reprogramming between two alternative modes of necroptosis signaling in hepatocytes, fundamentally affecting immune responses and hepatocarcinogenesis. Concomitant necrosome and NF-κB activation in hepatocytes, which physiologically express low concentrations of receptor-interacting kinase 3 (RIPK3), did not lead to immediate cell death but forced them into a prolonged “sublethal” state with leaky membranes, functioning as secretory cells that released specific chemokines including CCL20 and MCP-1. This triggered hepatic cell proliferation as well as activation of procarcinogenic monocyte-derived macrophage cell clusters, contributing to hepatocarcinogenesis. In contrast, necrosome activation in hepatocytes with inactive NF-κB-signaling caused an accelerated execution of necroptosis, limiting alarmin release, and thereby preventing inflammation and hepatocarcinogenesis. Consistently, intratumoral NF-κB-necroptosis signatures were associated with poor prognosis in human hepatocarcinogenesis. Therefore, pharmacological reprogramming between these distinct forms of necroptosis may represent a promising strategy against hepatocellular carcinoma.