Liver Macrophage Diversity in Health and Disease.

The liver fulfils a plethora of metabolic and immunological functions. Liver macrophages are a heterogeneous immune cell population with high plasticity and are important for maintaining normal liver function but are also critically involved in disease processes. In this chapter, we review the heterogeneity and multifaceted functions of hepatic macrophages in liver health and in disease conditions, including acute liver injury, chronic liver diseases, and hepatocellular carcinoma. Under homeostatic conditions, the tissue resident Kupffer cells are phagocytic cells that have important functions in immune surveillance, antigen presentation, and metabolic regulation while the roles of other populations such as capsular, peritoneal, or monocyte-derived macrophages in liver health are less clearly defined. Upon liver injury, Kupffer cell numbers are markedly reduced while monocyte-derived macrophages significantly expand and take critical roles in driving and resolving liver injury, including important pathogenic involvements in inflammation, fibrosis, and regeneration. They also create and maintain an immunosuppressive and immune-excluded microenvironment in hepatocellular carcinoma. Single-cell and spatial omics technologies are significantly expanding our understanding of the diversity and plasticity of macrophage populations under different conditions and enable the reliable identification of specific hepatic macrophage subsets. This knowledge can now be applied to dissect the exact contributions of distinct macrophage populations to disease processes and hopefully will pave the way for new therapeutic interventions.

p53 terminates the regenerative fetal-like state after colitis-associated injury.

Cells that lack p53 signaling frequently occur in ulcerative colitis (UC) and are considered early drivers in UC-associated colorectal cancer (CRC). Epithelial injury during colitis is associated with transient stem cell reprogramming from the adult, homeostatic to a "fetal-like" regenerative state. Here, we use murine and organoid-based models to study the role of Trp53 during epithelial reprogramming. We find that p53 signaling is silent and dispensable during homeostasis but strongly up-regulated in the epithelium upon DSS-induced colitis. While in WT cells this causes termination of the regenerative state, crypts that lack Trp53 remain locked in the highly proliferative, regenerative state long-term. The regenerative state in WT cells requires high Wnt signaling to maintain elevated levels of glycolysis. Instead, Trp53 deficiency enables Wnt-independent glycolysis due to overexpression of rate-limiting enzyme PKM2. Our study reveals the context-dependent relevance of p53 signaling specifically in the injury-induced regenerative state, explaining the high abundance of clones lacking p53 signaling in UC and UC-associated CRC.

Leveraging weak complementary labels enhances semantic segmentation of hepatocellular carcinoma and intrahepatic cholangiocarcinoma.

In this paper we present a deep learning segmentation approach to classify and quantify the two most prevalent primary liver cancers - hepatocellular carcinoma and intrahepatic cholangiocarcinoma - from hematoxylin and eosin (H&E) stained whole slide images. While semantic segmentation of medical images typically requires costly pixel-level annotations by domain experts, there often exists additional information which is routinely obtained in clinical diagnostics but rarely utilized for model training. We propose to leverage such weak information from patient diagnoses by deriving complementary labels that indicate to which class a sample cannot belong to. To integrate these labels, we formulate a complementary loss for segmentation. Motivated by the medical application, we demonstrate for general segmentation tasks that including additional patches with solely weak complementary labels during model training can significantly improve the predictive performance and robustness of a model. On the task of diagnostic differentiation between hepatocellular carcinoma and intrahepatic cholangiocarcinoma, we achieve a balanced accuracy of 0.91 (CI 95%: 0.86-0.95) at case level for 165 hold-out patients. Furthermore, we also show that leveraging complementary labels improves the robustness of segmentation and increases performance at case level.

Trans-arterial embolization for treatment of acute lower gastrointestinal bleeding-a multicenter analysis.

PURPOSE: To assess the technical feasibility, safety, and clinical success rate of trans-arterial embolization (TAE) as an emergency treatment for acute lower gastrointestinal bleeding (LGIB). MATERIALS AND METHODS: Consecutive patients who received urgent TAE due to active LGIB at five academic centers in Germany were retrospectively analyzed. LGIB was confirmed and localized using contrast-enhanced computed tomography (CT) or endoscopy. Outcome parameters including technical and clinical success rates as well as ischemia-related adverse events were analyzed. Furthermore, treatment-related variables that may affect technical and clinical success were analyzed using a regression model. RESULTS: One hundred and forty-one patients were included. TAE was performed in 91% (128/141) of patients. In 81% (114/141) of patients, TAE was performed due to active bleeding visible at angiography, the remaining 10% (14/141) underwent empiric embolization based on pre-interventional imaging. In 9% (13/141) of patients, no TAE was performed. Microcoils were the most used embolic 48.5% (62/128), followed by glue 23.5% (30/128) and Microparticles (8%; 10/128). In the case of bleeding visible in angiography, the technical success rate was 100% (114/114); the clinical success rate was 93.6% (120/128). Severe ischemia-related adverse events necessitating bowel surgery occurred in 14% (18/128) of all patients after embolization. Thirty-day mortality was 14% (21/141). Regression analysis revealed no significant correlations but a statistical trend toward a higher incidence of bowel resection when glue was used (p = 0.090) and toward a higher 30-day mortality when an unselective embolization was performed (p = 0.057). CONCLUSION: TAE for LGIB has a high technical and clinical success rate. Severe ischemia-related adverse events necessitating bowel surgery occurred in 14% of patients without identifying a significant correlation to the embolization technique or an embolic. KEY POINTS: Question Is trans-arterial embolization (TAE) viable as an emergency treatment for acute lower gastrointestinal bleeding (LGIB)? Findings TAE demonstrated a 100% technical and 93.6% clinical success rate in treating acute LGIB, with severe ischemia-related adverse events occurring in 14% of patients. Clinical relevance TAE is highly effective and has an acceptable complication rate in treating lower gastrointestinal bleeding, emphasizing the need for a direct head-to-head comparison between endovascular and endoscopic therapy.

Epidemiology of liver diseases: global disease burden and forecasted research trends.

We assessed the global incidence, mortality, and disability-adjusted life years (DALYs) associated with various liver diseases, including alcohol-related liver disease (ALD), hepatitis B/C virus infections (HBV or HCV), liver cancer, metabolic dysfunction-associated steatotic liver disease (MASLD), and other chronic liver diseases, from the 2019 Global Burden of Disease study. Additionally, we analyzed the global trends in hepatology research and drug development. From 2000 to 2019, prevalence rates increased for ALD, MASLD and other liver diseases, while they decreased for HBV, HCV, and liver cancer. Countries with a high socio-demographic index (SDI) exhibited the lowest mortality rates and DALYs. The burden of liver diseases varied due to factors like sex and region. In nine representative countries, MASLD, along with hepatobiliary cancer, showed highest increase in funding in hepatology research. Globally, the major research categories in hepatology papers from 2000 to 2019 were cancer, pathobiology, and MASLD. The United States (U.S.) was at the forefront of hepatology research, with China gradually increasing its influence over time. Hepatologists worldwide are increasingly focusing on studying the communication between the liver and other organs, while underestimating the research on ALD. Cancer, HCV, and MASLD were the primary diseases targeted for therapeutic development in clinical trials. However, the proportion of new drugs approved for the treatment of liver diseases was relatively low among all newly approved drugs in the U.S., China, Japan, and the European Union. Notably, there were no approved drug for the treatment of ALD in the world.

Hepatic immune regulation and sex disparities.

Chronic liver disease is a major cause of morbidity and mortality worldwide. Epidemiology, clinical phenotype and response to therapies for gastrointestinal and liver diseases are commonly different between women and men due to sex-specific hormonal, genetic and immune-related factors. The hepatic immune system has unique regulatory functions that promote the induction of intrahepatic tolerance, which is key for maintaining liver health and homeostasis. In liver diseases, hepatic immune alterations are increasingly recognized as a main cofactor responsible for the development and progression of chronic liver injury and fibrosis. In this Review, we discuss the basic mechanisms of sex disparity in hepatic immune regulation and how these mechanisms influence and modify the development of autoimmune liver diseases, genetic liver diseases, portal hypertension and inflammation in chronic liver disease. Alterations in gut microbiota and their crosstalk with the hepatic immune system might affect the progression of liver disease in a sex-specific manner, creating potential opportunities for novel diagnostic and therapeutic approaches to be evaluated in clinical trials. Finally, we identify and propose areas for future basic, translational and clinical research that will advance our understanding of sex disparities in hepatic immunity and liver disease.

Long-term impact of scheduled regular endoscopic interventions for patients with primary sclerosing cholangitis.

BACKGROUND: Primary sclerosing cholangitis (PSC) is associated with biliary obstructions that can require endoscopic retrograde cholangiopancreatography (ERCP). While the beneficial effects of ERCP are well documented, follow-up interventional strategies are less defined, and their long-term impact is debated. METHODS: We evaluated the outcome of a scheduled program of ERCP-guided interventions that have been developed and implemented at our tertiary liver center for more than 20 years. Within our center, follow-up ERCPs were performed at regular intervals to treat previously detected morphological stenosis independent of clinical symptoms. We calculated the transplant-free survival (TFS) of patients who were enrolled in the scheduled ERCP program and compared it to patients who received follow-up ERCPs only on clinical demand. Moreover, we documented the occurrence of hepatic decompensation, recurrent cholangitis episodes, hepatobiliary malignancies, and endoscopy-related adverse events. RESULTS: In our retrospective study, we included 201 patients with PSC who all received an ERCP. In all, 133 patients received scheduled follow-up ERCPs and 68 received follow-up ERCPs only on demand. The rates of TFS since initial diagnosis (median TFS: 17 vs. 27 y; P = 0.020) and initial presentation (median TFS: 16 vs. 11 y; P = 0.002) were higher in patients receiving scheduled versus on-demand ERCP. Subgroup analysis revealed that progression in cholangiographic findings between the first and second ERCP was associated with a poorer outcome compared to patients without progression (17 y vs. undefined; P = 0.021). CONCLUSION: In conclusion, we report the outcome data of a scheduled follow-up ERCP program for patients with PSC in an experienced high-volume endoscopy center. Our data suggest the initiation of multicenter randomized controlled prospective trials to explore the full potential of regular endoscopic follow-up treatment as a strategy to prevent disease progression in patients with PSC.

Multiomics analyses decipher intricate changes in the cellular and metabolic landscape of steatotic livers upon dietary restriction and sleeve gastrectomy.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a chronic, progressive liver disease that encompasses a spectrum of steatosis, steatohepatitis (or MASH), and fibrosis. Evidence suggests that dietary restriction (DR) and sleeve gastrectomy (SG) can lead to remission of hepatic steatosis and inflammation through weight loss, but it is unclear whether these procedures induce distinct metabolic or immunological changes in MASLD livers. This study aims to elucidate the intricate hepatic changes following DR, SG or sham surgery in rats fed a high-fat diet as a model of obesity-related MASLD, in comparison to a clinical cohort of patients undergoing SG. Single-cell and single-nuclei transcriptome analysis, spatial metabolomics, and immunohistochemistry revealed the liver landscape, while circulating biomarkers were measured in serum samples. Artificial intelligence (AI)-assisted image analysis characterized the spatial distribution of hepatocytes, myeloid cells and lymphocytes. In patients and experimental MASLD rats, SG improved body mass index, circulating liver injury biomarkers and triglyceride levels. Both DR and SG attenuated liver steatosis and fibrosis in rats. Metabolism-related genes (Ppara, Cyp2e1 and Cyp7a1) were upregulated in hepatocytes upon DR and SG, while SG broadly upregulated lipid metabolism on cholangiocytes, monocytes, macrophages, and neutrophils. Furthermore, SG promoted restorative myeloid cell accumulation in the liver not only ameliorating inflammation but activating liver repair processes. Regions with potent myeloid infiltration were marked with enhanced metabolic capacities upon SG. Additionally, a disruption of periportal hepatocyte functions was observed upon DR. In conclusion, this study indicates a dynamic cellular crosstalk in steatotic livers of patients undergoing SG. Notably, PPARα- and gut-liver axis-related processes, and metabolically active myeloid cell infiltration indicate intervention-related mechanisms supporting the indication of SG for the treatment of MASLD.

A comprehensive 26-color immunophenotyping panel to study the role of the gut-liver axis in chronic liver diseases.

The gut-liver axis includes the bidirectional communication between the gut and the liver, and thus covers signals from liver-to-gut and from gut-to-liver. Disruptions of the gut-liver axis have been associated with the progression of chronic liver diseases, including alcohol-related and metabolic dysfunction-associated steatotic liver disease and cholangiopathies. Immune cells and their expression of pattern recognition receptors, activation markers or immune checkpoints might play an active role in the communication between gut and liver. Here, we present a 26-color full spectrum flow cytometry panel for human cells to decipher the role of circulating immune cells in gut-liver communication during the progression of chronic liver diseases in a non-invasive manner, which has been optimized to be used on patient-derived whole blood samples, the most abundantly available clinical material. Our panel focuses on changes in pattern recognition receptors, including toll-like receptors (TLRs) or Dectin-1, and also includes other immunomodulatory molecules such as bile acid receptors and checkpoint molecules. Moreover, this panel can be utilized to follow the progression of chronic liver diseases and could be used as a tool to evaluate the efficiency of therapeutic targets directed against microbial mediators or modulating immune cell activation.

Sub-optimal therapy of patients with primary biliary cholangitis (PBC) in the real-life stetting of the German PBC cohort.

Real-world data on the management of patients with primary biliary cholangitis (PBC) are so far scarce in Germany. Therefore, we aimed to establish a nationwide registry and describe the clinical characteristics and therapy of PBC patients.Three different cohorts defined as ursodeoxycholic acid (UDCA) responders, as inadequate responders according to Paris II criteria, and as newly diagnosed patients were prospectively recruited.This manuscript includes the baseline data of the project.In total, 33/77 (43%) contacted centres (58% of university hospitals, 38% of non-university hospitals, and 24% of private practices) recruited 515 patients including 204 UDCA responders, 221 inadequate responders to UDCA, and 90 newly diagnosed patients.All patients were treated with UDCA; however, a UDCA dosage below the recommended dosage of 13 mg/kg/d was observed in 38.5% of individuals after 12 months of treatment. UDCA dosages were lower in nonacademic compared to academic centres.Only 75/219 (38.5%) of inadequate responders to UDCA received a second-line therapy with obeticholic acid (OCA) and/or bezafibrate (BZF). OCA (13% vs. 4.5%) and BZF (14% vs. 6.5%) were significantly more often prescribed by academic vs. nonacademic centres.Pruritus (27% vs. 15.5%), fatigue (23% vs. 4.5%), and sicca syndrome (14% vs. 1%) were significantly more often reported by academic centres.The German PBC registry could be established, which indicates suboptimal therapy in a relevant proportion of patients and shows significant differences between academic and nonacademic centres. Results are fundamental to improving clinical management at different levels of care.

Sphingosine Kinase 1 Aggravates Liver Fibrosis by Mediating Macrophage Recruitment and Polarization.

BACKGROUND & AIMS: Sphingosine kinase 1 (SphK1) has distinct roles in the activation of Kupffer cells and hepatic stellate cells in liver fibrosis. Here, we aim to investigate the roles of SphK1 on hepatic macrophage recruitment and polarization in liver fibrosis. METHODS: Liver fibrosis was induced by carbon tetrachloride in wild-type and SphK1-/- mice to study the recruitment and polarization of macrophages. The effects of SphK1 originated from macrophages or other liver cell types on liver fibrosis were further strengthened by bone marrow transplantation. The direct effects of SphK1 on macrophage polarization were also investigated in vitro. Expression analysis of SphK1 and macrophage polarization index was conducted with human liver samples. RESULTS: SphK1 deletion attenuated the recruitment of hepatic macrophages along with reduced M1 and M2 polarization in mice induced by carbon tetrachloride. SphK1 deficiency in endogenous liver cells attenuated macrophage recruitment via C-C motif chemokine ligand 2. Macrophage SphK1 activated the ASK1-JNK1/2-p38 signaling pathway to promote M1 polarization. Furthermore, macrophage SphK1 downregulated small ubiquitin-like modifier-specific peptidase1 to decrease de-SUMOylation of Kruppel-like factor 4 to promote M2 polarization. Finally, we confirmed that SphK1 expression was elevated and positively correlated with macrophage M1 and M2 polarization in human fibrosis livers. CONCLUSIONS: Our findings demonstrated that SphK1 aggravated liver fibrosis by promoting macrophage recruitment and M1/M2 polarization. SphK1 in macrophages is a potential therapeutic target for the treatment of liver fibrosis.

Impact of non-selective beta blockers on further decompensation and death in decompensated cirrhosis: Benefit and risk stratification by MELD score.

BACKGROUND: Non-selective beta blockers (NSBBs) can reduce the risk of decompensation, but their impact on further decompensation has been rarely investigated. AIMS: The aim is to evaluate the impact of NSBBs on further decompensation and death in decompensated cirrhosis stratified by the severity of liver disease. METHODS: Overall, 332 decompensated cirrhotic patients were retrospectively included, of whom 149 used NSBBs. Kaplan-Meier and Nelson-Aalen cumulative risk curves as well as Cox regression and competing risk analyses were used to estimate the associations of NSBBs with further decompensation and death, if appropriate. Hazard ratio (HR) and sub-distribution HR (sHR) were calculated. Subgroup analyses were performed based on the model for end-stage liver disease (MELD) score at admission. RESULTS: In the overall analysis, the use of NSBBs was not significantly associated with further decompensation in multivariate competing risk analysis (sHR = 1.09, p = 0.580). In the subgroup analysis of patients with a MELD score of ≤9, the use of NSBBs was significantly associated with decreased risk of further decompensation in multivariate competing risk analysis (sHR = 0.57, p = 0.021). In the subgroup analysis of patients with a MELD score of >9, the use of NSBBs was associated with increased risk of further decompensation in multivariate competing risk analysis (sHR = 1.45, p = 0.044). Regardless of overall and subgroup analyses, the use of NSBBs was not significantly associated with death in multivariate Cox regression analyses. CONCLUSION: NSBBs may be beneficial for the prevention of further decompensation in cirrhotic patients with a MELD score of ≤9, but deleterious in those with a MELD score of >9.

Diagnostics and omics technologies for the detection and prediction of metabolic dysfunction-associated steatotic liver disease-related malignancies.

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) continues to rise, making it the leading etiology of chronic liver diseases and a prime cause of liver-related mortality. MASLD can progress into steatohepatitis (termed MASH), fibrosis, cirrhosis, and ultimately cancer. MASLD is associated with increased risks of hepatocellular carcinoma (HCC) and also extrahepatic malignancies, which can develop in both cirrhotic and non-cirrhotic patients, emphasizing the importance of identifying patients with MASLD at risk of developing MASLD-associated malignancies. However, the optimal screening, diagnostic, and risk stratification strategies for patients with MASLD at risk of cancer are still under debate. Individuals with MASH-associated cirrhosis are recommended to undergo surveillance for HCC (e.g. by ultrasound and biomarkers) every six months. No specific screening approaches for MASLD-related malignancies in non-cirrhotic cases are established to date. The rapidly developing omics technologies, including genetics, metabolomics, and proteomics, show great potential for discovering non-invasive markers to fulfill this unmet need. This review provides an overview on the incidence and mortality of MASLD-associated malignancies, current strategies for HCC screening, surveillance and diagnosis in patients with MASLD, and the evolving role of omics technologies in the discovery of non-invasive markers for the prediction and risk stratification of MASLD-associated HCC.

Impact of peptic ulcer bleeding on the in-hospital outcomes of cirrhotic patients with acute gastrointestinal bleeding: an international multicenter study.

OBJECTIVES: Peptic ulcer is the most common source of non-variceal bleeding. However, it remains controversial whether the outcomes of cirrhotic patients with peptic ulcer bleeding differ from those with variceal bleeding. METHODS: Cirrhotic patients with acute gastrointestinal bleeding (AGIB) who underwent endoscopy and had an identifiable source of bleeding were retrospectively screened from an international multicenter cohort. Logistic regression analyses were performed to explore the impact of peptic ulcer bleeding on in-hospital death and 5-day failure to control bleeding. Propensity score matching (PSM) analysis was performed by matching age, gender, Child-Pugh score, and model for end-stage liver disease score between the peptic ulcer bleeding and variceal bleeding groups. RESULTS: Overall, 1535 patients were included, of whom 73 (4.7%) had peptic ulcer bleeding. Multivariate logistic regression analyses showed that peptic ulcer bleeding was not independently associated with in-hospital death (OR = 2.169, p = 0.126) or 5-day failure to control bleeding (OR = 1.230, p = 0.680). PSM analyses demonstrated that both in-hospital mortality (9.7% vs. 6.3%, p = 0.376) and rate of 5-day failure to control bleeding (6.9% vs. 5.4%, p = 0.787) were not significantly different between the two groups. CONCLUSIONS: The impact of peptic ulcer bleeding on the in-hospital outcomes of cirrhotic patients is similar to that of variceal bleeding.

In this international multicenter study, we included 1535 patients with acute gastrointestinal bleeding (AGIB) and divided them into peptic ulcer bleeding and variceal bleeding groups. We found that only a minority of AGIB episodes in cirrhotic patients was attributed to peptic ulcer. Additionally, after adjusting for the severity of liver dysfunction, the in-hospital mortality and the rate of 5-day failure to control bleeding should be similar between cirrhotic patients with peptic ulcer bleeding and those with variceal bleeding.

Patient profiled data for treatment decision-making: valuable as an add-on to hepatitis C clinical guidelines?

BACKGROUND AND AIMS: Systematic reviews and medical guidelines are widely used in clinical practice. However, these are often not up-to-date and focussed on the average patient. We therefore aimed to evaluate a guideline add-on, TherapySelector (TS), which is based on monthly updated data of all available high-quality studies, classified in specific patient profiles. METHODS: We evaluated the TS for the treatment of hepatitis C (HCV) in an international cohort of patients treated with direct-acting antivirals between 2015 and 2020. The primary outcome was the number of patients receiving one of the two preferred treatment options of the HCV TS, based on the highest level of evidence, cure rate, absence of ribavirin-associated adverse effects, and treatment duration. RESULTS: We enrolled 567 patients. The number of patients treated with one of the two preferred treatment options according to the HCV TS ranged between 27% (2015) and 60% (2020; p < 0.001). Most of the patients received a regimen with a longer treatment-duration (up to 34%) and/or addition of ribavirin (up to 14%). The effect on the expected cure-rate was minimal (1-6% higher) when the first preferred TherapySelector option was given compared to the actual treatment. CONCLUSIONS: Medical decision-making can be optimised by a guideline add-on; in HCV its use appears to minimise adverse effects and cost. The use of such an add-on might have a greater impact in diseases with suboptimal cure-rates, high costs or adverse effects, for which treatment options rely on specific patient characteristics.