Liver Resection in Synchronous Bilobar versus Unilobar Colorectal Liver Metastases: A Retrospective Analysis of Oncological Outcomes and Patient Survival.

INTRODUCTION: Resection of colorectal liver metastasis has emerged as the standard treatment. Our study compares oncological outcomes of patients with resected synchronous bilobar versus unilobar colorectal liver metastasis. METHODS: This retrospective study presents long-term follow-up data of 105 consecutive patients with primary colorectal cancer and synchronous liver metastasis. All patients underwent primary tumor and metastasis resections between 2007 and 2019. RESULTS: Fifty-five patients with bilobar and 50 patients with unilobar colorectal liver metastases were included. No significant difference in overall, tumor-specific, or recurrence-free survival was observed between patients with bilobar and unilobar metastases. After case-control matching, the results were confirmed in patients with similar tumor burdens. In the multivariate analysis, chemotherapy following liver metastasis resection was a significant prognostic factor associated with improved overall survival (hazard ratio 0.518, 95% confidence interval: 0.302-0.888, p = 0.017). CONCLUSION: Overall survival, as well as tumor-specific and recurrence-free survival, did not differ between patients with unilobar and bilobar liver metastasis. These findings contribute to the understanding that primary tumor and metastasis resection in eligible patients improve long-term outcomes.

Cell Death in Liver Disease and Liver Surgery.

Cell death is crucial for maintaining tissue balance and responding to diseases. However, under pathological conditions, the surge in dying cells results in an overwhelming presence of cell debris and the release of danger signals. In the liver, this gives rise to hepatic inflammation and hepatocellular cell death, which are key factors in various liver diseases caused by viruses, toxins, metabolic issues, or autoimmune factors. Both clinical and in vivo studies strongly affirm that hepatocyte death serves as a catalyst in the progression of liver disease. This advancement is characterized by successive stages of inflammation, fibrosis, and cirrhosis, culminating in a higher risk of tumor development. In this review, we explore pivotal forms of cell death, including apoptosis, pyroptosis, and necroptosis, examining their roles in both acute and chronic liver conditions, including liver cancer. Furthermore, we discuss the significance of cell death in liver surgery and ischemia-reperfusion injury. Our objective is to illuminate the molecular mechanisms governing cell death in liver diseases, as this understanding is crucial for identifying therapeutic opportunities aimed at modulating cell death pathways.

Liver Fibrosis Is Associated with Poorer Overall Survival and Higher Recurrence Rate in Patients with Cholangiocarcinoma.

INTRODUCTION: Cholangiocarcinoma is the second most common primary liver tumour worldwide with an increasing incidence in recent decades. While the effects of fibrosis on hepatocellular carcinoma have been widely demonstrated, the impact on cholangiocarcinoma remains unclear. The aim of this study was to evaluate the impact of liver fibrosis on overall survival (OS) and disease-free survival (DFS) in patients who have undergone liver resection for cholangiocarcinoma. METHODS: Eighty patients with cholangiocarcinoma who underwent curatively intended liver surgery between January 2007 and December 2020 were included in this retrospective single-centre study. Clinical and histopathological features were analysed. The primary endpoint was cause-specific survival. Secondary endpoints were DFS and identification of prognostic factors. RESULTS: The present study shows that the median OS is significantly reduced in patients with fibrosis (p < 0.001). The median OS in patients with fibrosis was three times shorter than in the group without fibrosis. In addition, a significantly shorter DFS was observed in patients with fibrosis (p < 0.002). Multivariate analysis showed that fibrosis is the strongest independent factor with a negative impact on OS and DFS. CONCLUSION: Liver fibrosis has a significant impact on OS and DFS in patients with cholangiocarcinoma. Patients with known liver fibrosis require thorough perioperative care and postoperative follow-up.

Hepatocellular Brg1 promotes CCl4-induced liver inflammation, ECM accumulation and fibrosis in mice.

INTRODUCTION: Hepatic fibrosis is a progressive pathological process involving the exhaustion of hepatocellular regenerative capacity and ultimately leading to the development of cirrhosis and even hepatocellular carcinoma. Brg1, the core subunit of the SWI/SNF chromatin-remodeling complex, was recently identified as important for liver regeneration. This study investigates the role of Brg1 in hepatic fibrosis development. METHODS: Hepatocyte-specific Brg1 knockout mice were generated and injected with carbon tetrachloride (CCl4) for 4, 6, 8, and 12 weeks to induce liver fibrosis. Afterwards, liver fibrosis and liver damage were assessed. RESULTS: Brg1 expression was significantly increased in the fibrotic liver tissue of wild-type mice, as compared to that of untreated wild-type mice. The livers of the Brg1 knockout animals showed reduced liver inflammation, extracellular matrix accumulation, and liver fibrosis. TNF-α and NF-κB-mediated inflammatory response was reduced in Brg1 knockout animals. CONCLUSION: Brg1 promotes the progression of liver fibrosis in mice and may therefore be used as a potential therapeutic target for treating patients with liver fibrosis due to chronic injury.

[Future of University Medicine: How Important are Research and Teaching? - An Inventory]. / Zukunft der Universitätsmedizin: Welchen Stellenwert haben Forschung und Lehre noch? ­ Eine Bestandsaufnahme.

The requirements and challenges for the university hospitals in Germany are changing. Especially in surgical subjects, it is more and more difficult to adequately serve these three pillars of university medicine - clinic, research and education. This survey was intended to determine the status quo of general and visceral surgery at universities, in order to provide a basis for proposed solutions.For this online survey, 1505 visceral surgeons at the 38 university clinics were contacted. The questionnaire contained 29 questions on the structure of the clinic, scientific motivation, opportunities for time-off and the appreciation of academic achievements. The type and scope of student courses and the preparation for them were also determined. With regard to patient care, the type and number of services and the course of surgical training were examined. Based on the data published on the websites of the individual clinics on the number, gender, position and academic title of the doctors, a demographic analysis of university visceral surgeons could also be created.Of 1505 surgeons successfully contacted, 352 took part in the survey, which corresponds to a response rate of 23.4%. Of the participants, 93.5% were scientifically active, the majority being in the field of clinical data collection. Many indicated that they were also active in translational and/or experimental research, while educational research was rarely named. 45% confirmed that they could perform scientific work during their normal working hours. The reward for this activity was mostly in the form of time-off for congresses and clinical appreciation. Most participants stated that they were involved in 3-4 student courses per week, with 24.4% reporting that they were not adequately prepared for them.The compatibility of the classic three pillars of clinic, research and teaching continues to be of great relevance. There is a high level of motivation among the participating visceral surgeons not to neglect research and teaching, despite increasing economic pressure in the field of patient care. However, arrangements must be created in order to reward and promote commitment in research and teaching in a structured way.

Gut microbiota promote liver regeneration through hepatic membrane phospholipid biosynthesis.

BACKGROUND & AIMS: Hepatocyte growth and proliferation depends on membrane phospholipid biosynthesis. Short-chain fatty acids (SCFAs) generated by bacterial fermentation, delivered through the gut-liver axis, significantly contribute to lipid biosynthesis. We therefore hypothesized that dysbiotic insults like antibiotic treatment not only affect gut microbiota, but also impair hepatic lipid synthesis and liver regeneration. METHODS: Stable isotope labeling and 70% partial hepatectomy (PHx) was carried out in C57Bl/6J wild-type mice, in mice treated with broad-spectrum antibiotics, in germ-free mice and mice colonized with minimal microbiota. The microbiome was analyzed by 16S rRNA gene sequencing and microbial culture. Gut content, liver, blood and primary hepatocyte organoids were tested by mass spectrometry-based lipidomics, quantitative reverse-transcription PCR (qRT-PCR), immunoblot and immunohistochemistry for expression of proliferative and lipogenic markers. Matched biopsies from hyperplastic and hypoplastic liver tissue of patients subjected to surgical intervention to induce hyperplasia were analyzed by qRT-PCR for lipogenic enzymes. RESULTS: Three days of antibiotic treatment induced persistent dysbiosis with significantly decreased beta-diversity and richness, but a massive increase of Proteobacteria, accompanied by decreased colonic SCFAs. After PHx, antibiotic-treated mice showed delayed liver regeneration, increased mortality, impaired hepatocyte proliferation and decreased hepatic phospholipid synthesis. Expression of the lipogenic enzyme SCD1 was upregulated after PHx but delayed by antibiotic treatment. Germ-free mice essentially recapitulated the phenotype of antibiotic treatment. Phospholipid biosynthesis, hepatocyte proliferation, liver regeneration and survival were rescued in gnotobiotic mice colonized with a minimal SCFA-producing microbial community. SCFAs induced the growth of murine hepatocyte organoids and hepatic SCD1 expression in mice. Further, SCD1 was required for proliferation of human hepatoma cells and was associated with liver regeneration in human patients. CONCLUSION: Gut microbiota are pivotal for hepatic membrane phospholipid biosynthesis and liver regeneration. IMPACT AND IMPLICATIONS: Gut microbiota affect hepatic lipid metabolism through the gut-liver axis, but the underlying mechanisms are poorly understood. Perturbations of the gut microbiome, e.g. by antibiotics, impair the production of bacterial metabolites, which normally serve as building blocks for membrane lipids in liver cells. As a consequence, liver regeneration and survival after liver surgery is severely impaired. Even though this study is preclinical, its results might allow physicians in the future to improve patient outcomes after liver surgery, by modulation of gut microbiota or their metabolites.

Cell-specific Deletion of NLRP3 Inflammasome Identifies Myeloid Cells as Key Drivers of Liver Inflammation and Fibrosis in Murine Steatohepatitis.

BACKGROUND & AIMS: Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide. The NLRP3 inflammasome, a platform for caspase-1 activation and release of interleukin 1ß, is increasingly recognized in the induction of inflammation and liver fibrosis during NAFLD. However, the cell-specific contribution of NLRP3 inflammasome activation in NAFLD remains unknown. METHODS: To investigate the role of NLRP3 inflammasome activation in hepatocytes, hepatic stellate cells (HSCs) and myeloid cells, a conditional Nlrp3 knock-out mouse was generated and bred to cell-specific Cre mice. Both acute and chronic liver injury models were used: lipopolysaccharide/adenosine-triphosphate to induce in vivo NLRP3 activation, choline-deficient, L-amino acid-defined high-fat diet, and Western-type diet to induce fibrotic nonalcoholic steatohepatitis (NASH). In vitro co-culture studies were performed to dissect the crosstalk between myeloid cells and HSCs. RESULTS: Myeloid-specific deletion of Nlrp3 blunted the systemic and hepatic increase in interleukin 1ß induced by lipopolysaccharide/adenosine-triphosphate injection. In the choline-deficient, L-amino acid-defined high-fat diet model of fibrotic NASH, myeloid-specific Nlrp3 knock-out but not hepatocyte- or HSC-specific knock-out mice showed significant reduction in inflammation independent of steatosis development. Moreover, myeloid-specific Nlrp3 knock-out mice showed ameliorated liver fibrosis and decreased HSC activation. These results were validated in the Western-type diet model. In vitro co-cultured studies with human cell lines demonstrated that HSC can be activated by inflammasome stimulation in monocytes, and this effect was significantly reduced if NLRP3 was downregulated in monocytes. CONCLUSIONS: The study provides new insights in the cell-specific role of NLRP3 in liver inflammation and fibrosis. NLRP3 inflammasome activation in myeloid cells was identified as crucial for the progression of NAFLD to fibrotic NASH. These results may have implications for the development of cell-specific strategies for modulation of NLRP3 activation for treatment of fibrotic NASH.

High precision-cut liver slice model to study cell-autonomous antiviral defense of hepatocytes within their microenvironment.

Background & Aims: Increased sensitivity towards tumor necrosis factor (TNF)-induced cell death in virus-infected hepatocytes has revealed a so far unrecognized hepatocyte-intrinsic antiviral immune surveillance mechanism, for which no in vitro or ex vivo model is available. We aimed to establish precision-cut liver slices (PCLS) as a model system to study hepatocyte-intrinsic regulation of apoptosis. Methods: Preparation of PCLS from mouse and human liver tissue was optimized for minimal procedure-associated apoptosis. Functionality of liver cells in PCLS was characterized using extracellular flux analysis to determine mitochondrial respiration, and viral infection with recombinant adenovirus and lymphocytic choriomeningitis virus (LCMV) was used to probe for hepatocyte-intrinsic sensitivity towards apoptosis in PCLS. Apoptosis was detected by immunohistochemical staining for cleaved-caspase 3 and quantified by detection of effector caspase activity in PCLS. Results: We established an optimized protocol for preparation of PCLS from human and mouse models using agarose-embedding of liver tissue to improve precision cutting and using organ-protective buffer solutions to minimize procedure-associated cell death. PCLS prepared from virus-infected livers showed preserved functional metabolic properties. Importantly, in PCLS from adenovirus- and LCMV-infected livers we detected increased induction of apoptosis after TNF challenge ex vivo. Conclusion: We conclude that PCLS can be used as model system to ex vivo characterize hepatocyte-intrinsic sensitivity to cell death. This may also enable researchers to characterize human hepatocyte sensitivity to apoptosis in PCLS prepared from patients with acute or chronic liver diseases. Lay summary: Virus-infected hepatocytes in vivo show an increased sensitivity towards induction of cell death signaling through the TNF receptor. Studying this hepatocyte-intrinsic antiviral immune surveillance mechanism has been hampered by the absence of model systems that reciprocate the in vivo finding of increased apoptosis of virus-infected hepatocytes challenged with TNF. Herein, we report that an optimized protocol for generation of precision-cut liver slices can be used to study this hepatocyte-intrinsic surveillance mechanism ex vivo.

softALPPS - A novel, individual procedure for patients with advanced liver tumors.

BACKGROUND: The first-line therapy for liver malignancies is a radical extended liver resection. This high-risk operation has a high incidence of post-hepatectomy liver failure (PHLF) due to a small future liver remnant (FLR). One of the procedures to increase the FLR is the associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) which is still associated with high morbidity and mortality. Here, we present a new, less invasive ALPPS variant that may be associated with lower morbidity. METHODS: SoftALPPS is characterized by reduced trauma to the liver tissue and individual adaptation to the patient's health constitution. In softALPPS, portal vein embolization (PVE) is performed instead of portal vein ligation (PVL) after complete recovery of liver function. In addition, a non-absorbable foil was avoided in order to be able to extend the interval to step two or skip step two when required. RESULTS: Four patients successfully underwent softALPPS. Two of these patients have been followed-up for over a year (one patient with Klatskin tumor, one patient with extensive HCC). Both patients show no evidence of recurrence after 12 months and are in good medical condition. The other two patients who recently had surgery are also doing well. CONCLUSION: SoftALPPS offers the chance to curatively resect patients with high tumor burden of the liver even when the FLR is inadequate. This individual therapy method can give patients the possibility of complete tumor resection and can help to reduce perioperative morbidity.

Novel Risk Classification Based on Pyroptosis-Related Genes Defines Immune Microenvironment and Pharmaceutical Landscape for Hepatocellular Carcinoma.

Growing evidence has indicated that pyroptosis functions in the development of cancer. Nonetheless, specific roles of pyroptosis-related genes in tumor progression, immune response, prognosis, and immunotherapy have not been thoroughly elucidated. After a comprehensive evaluation of pyroptosis genes, unsupervised clustering was performed to generate three distinct clusters from hepatocellular carcinoma (HCC) samples. Three distinct pyroptosis-related molecular subtypes comprising three gene clusters that had differential prognostic effects on patient survival were then identified. Immune characteristics analyses revealed diversified immune cell infiltration among the subtypes. Two clusters served as immune-hot phenotypes associated with significantly poorer survival compared to a remaining third immune-cold cluster. Among these, the immune-hot clusters were characterized by abundant adaptive immune cell infiltration, active CD4+ and CD8+ T cells, high total leukocyte counts and tumor growth status, and lower Th17 cell and M2 macrophage densities. Then, risk scores indicated that low-risk patients were more sensitive to anti-tumor therapy. Subsequently, we found a significant correlation between pyroptosis and prognosis in HCC and that pyroptosis genes drive the heterogeneity of the tumor microenvironment. The risk scoring system, based on pyroptosis-related differentially expressed genes, was established to evaluate the individual outcomes and contribute to new insights into the molecular characterization of pyroptosis-related subtypes.

Association of Telomere Length With Risk of Disease and Mortality.

IMPORTANCE: Telomeres protect DNA from damage. Because they shorten with each mitotic cycle, leukocyte telomere length (LTL) serves as a mitotic clock. Reduced LTL has been associated with multiple human disorders. OBJECTIVE: To determine the association between LTL and overall as well as disease-specific mortality and morbidity. DESIGN, SETTING, AND PARTICIPANTS: This multicenter, community-based cohort study conducted from March 2006 to December 2010 included longitudinal follow-up (mean [SD], 12 [2] years) for 472 432 English participants from the United Kingdom Biobank (UK Biobank) and analyzed morbidity and mortality. The data were analyzed in 2021. MAIN OUTCOMES AND MEASURES: Hazard ratios (HRs) and odds ratios for mortality and morbidity associated with a standard deviation change in LTL, adjusted for age, sex, body mass index (calculated as weight in kilograms divided by height in meters squared), and ethnicity. RESULTS: This study included a total of 472 432 English participants, of whom 54% were women (mean age, 57 years). Reduced LTL was associated with increased overall (HR, 1.08; 95% CI, 1.07-1.09), cardiovascular (HR, 1.09; 95% CI, 1.06-1.12), respiratory (HR, 1.40; 95% CI, 1.34-1.45), digestive (HR, 1.26; 95% CI, 1.19-1.33), musculoskeletal (HR, 1.51; 95% CI, 1.35-1.92), and COVID-19 (HR, 1.15; 95% CI, 1.07-1.23) mortality, but not cancer-related mortality. A total of 214 disorders were significantly overrepresented and 37 underrepresented in participants with shorter LTL. Respiratory (11%), digestive/liver-related (14%), circulatory (18%), and musculoskeletal conditions (6%), together with infections (5%), accounted for most positive associations, whereas (benign) neoplasms and endocrinologic/metabolic disorders were the most underrepresented entities. Malignant tumors, esophageal cancer, and lymphoid and myeloid leukemia were significantly more common in participants with shorter LTL, whereas brain cancer and melanoma were less prevalent. While smoking and alcohol consumption were associated with shorter LTL, additional adjustment for both factors, as well as cognitive function/major comorbid conditions, did not significantly alter the results. CONCLUSIONS AND RELEVANCE: This cohort study found that shorter LTL was associated with a small risk increase of overall mortality, but a higher risk of mortality was associated with specific organs and diseases.

Impact of the COVID-19 Pandemic on Surgical Oncology in Europe: Results of a European Survey.

BACKGROUND: The first COVID-19 pandemic wave hit most of the health-care systems worldwide. The present survey aimed to provide a European overview on the COVID-19 impact on surgical oncology. METHODS: This anonymous online survey was accessible from April 24 to May 11, 2020, for surgeons (n = 298) who were contacted by the surgical society European Digestive Surgery. The survey was completed by 88 surgeons (29.2%) from 69 different departments. The responses per department were evaluated. RESULTS: Of the departments, 88.4% (n = 61/69) reported a lower volume of patients in the outpatient clinic; 69.1% (n = 47/68) and 75.0% (n = 51/68) reported a reduction in hospital bed and the operating room capacity, respectively. As a result, the participants reported an average reduction of 29.3% for all types of oncological resections surveyed in this questionnaire. The strongest reduction was observed for oncological resections of hepato-pancreatico-biliary (HPB) cancers. Of the interviewed surgeons, 68.7% (n = 46/67) agreed that survival outcomes will be negatively impacted by the pandemic. CONCLUSION: The first COVID-19 pandemic wave had a significant impact on surgical oncology in Europe. The surveyed surgeons expect an increase in the number of unresectable cancers as well as poorer survival outcomes due to cancellations of follow-ups and postponements of surgeries.

Postoperative adjuvant transarterial chemoembolization for intrahepatic cholangiocarcinoma patients with microvascular invasion: a propensity score analysis.

BACKGROUND: Microvascular invasion (MVI) is an independent risk factor associated with tumor recurrence and poor survival in patients with intrahepatic cholangiocarcinoma (ICC) after partial hepatectomy (PH). The potential impact of adjuvant TACE on the prognosis of patients with ICC involving MVI (ICC-MVI) remains uncertain. Our aim was to investigate the effectiveness of postoperative adjuvant transarterial chemoembolization (TACE) on ICC involving MVI. METHODS: Multicentric data consisted of 223 patients who underwent curative-intent PH for ICC-MVI from 2002-2015 were retrospectively analyzed. The impact of adjuvant TACE was evaluated using inverse probability of treatment weighting (IPTW) and propensity-score matched (PSM) analyses. RESULTS: No association between the TACE and the overall survival (OS) and recurrence rates was observed among the overall ICC-MVI patients. However, subgroup analyses revealed that adjuvant TACE favored OS (HR, 0.62; 95% CI, 0.39-0.99; P=0.047) and time to recurrence (TTR) (HR, 0.59; 95% CI, 0.36-0.97; P=0.037) among patients with elevated CA19-9 and those without lymphadenectomy (HR, 0.53; 95% CI, 0.30-0.93; P=0.027 for OS, and HR, 0.49; 95% CI, 0.28-0.87; P=0.015 for TTR, respectively). In the CA19-9 ≥39 U/L subgroup and Nx subgroup, adjuvant TACE was associated with higher 1-, 3-, and 5-year OS rates (P=0.033 and P=0.034, respectively) and lower corresponding recurrence rates (P=0.024 and P=0.023, respectively). CONCLUSIONS: Among the ICC-MVI patients undergoing curative-intent PH, only those have elevated CA19-9 or who did not undergo lymphadenectomy might be suitable for adjuvant TACE.

[Effects of the first COVID-19 wave on visceral surgery : A retrospective comparison of case numbers from a university hospital and a primary care hospital]. / Auswirkungen der ersten COVID­19-Welle auf die Viszeralchirurgie : Ein retrospektiver Fallzahlenvergleich an einem Universitätsklinikum und einem Krankenhaus der Grund- und Regelversorgung.

BACKGROUND: During the first wave of the COVID-19 pandemic, the downregulation of all elective interventions during the period from 15 March 2020 to 15 May 2020 in Germany led to a decrease in operations. The impact on the number of specific operations in visceral surgery is so far unknown. METHODS: This retrospective study included 301 patients who underwent a cholecystectomy or appendectomy at a university hospital or a primary care facility between 15 March 2020 and 15 May 2020 (vs. 2018 and 2019). The number of cases and the clinical outcomes were analyzed. RESULTS: The suspension of elective surgery resulted in a significant reduction in elective cholecystectomy and emergency appendectomy. At the University Hospital the number of appendectomies decreased by 33% from 24 in 2018 to 16 in 2020 and the number of cholecystectomies declined by 57% from 30 in 2018 to 13 in 2020. At the primary care hospital, the number of appendectomy patients decreased by 48% from 23 in 2018 to 12 in 2020 and the number of cholecystectomies increased from the year 2018 to 2019 and subsequently declined by 30% in 2020. The duration of surgery, length of hospital stay and clinical course of patients did not significantly differ from the previous year time periods. CONCLUSIONS: During the first wave of the COVID-19 pandemic, the lockdown resulted in a significant reduction in frequently carried out visceral surgical interventions. In order to maintain the optimal medical care for the total population, current options for surgical and conservative treatment must be weighed against each other depending on the numbers of local infections and the individual comorbidities of the patients.

Evaluation of Allogeneic Bone-Marrow-Derived and Umbilical Cord Blood-Derived Mesenchymal Stem Cells to Prevent the Development of Osteoarthritis in An Equine Model.

Osteoarthritis (OA) is a significant cause of pain in both humans and horses with a high socio-economic impact. The horse is recognized as a pertinent model for human OA. In both species, regenerative therapy with allogeneic mesenchymal stem cells (MSCs) appears to be a promising treatment but, to date, no in vivo studies have attempted to compare the effects of different cell sources on the same individuals. The objective of this study is to evaluate the ability of a single blinded intra-articular injection of allogeneic bone-marrow (BM) derived MSCs and umbilical cord blood (UCB) derived MSC to limit the development of OA-associated pathological changes compared to placebo in a post-traumatic OA model applied to all four fetlock joints of eight horses. The effect of the tissue source (BM vs. UCB) is also assessed on the same individuals. Observations were carried out using clinical, radiographic, ultrasonographic, and magnetic resonance imaging methods as well as biochemical analysis of synovial fluid and postmortem microscopic and macroscopic evaluations of the joints until Week 12. A significant reduction in the progression of OA-associated changes measured with imaging techniques, especially radiography, was observed after injection of bone-marrow derived mesenchymal stem cells (BM-MSCs) compared to contralateral placebo injections. These results indicate that allogeneic BM-MSCs are a promising treatment for OA in horses and reinforce the importance of continuing research to validate these results and find innovative strategies that will optimize the therapeutic potential of these cells. However, they should be considered with caution given the low number of units per group.

Auto-aggressive CXCR6+ CD8 T cells cause liver immune pathology in NASH.

Nonalcoholic steatohepatitis (NASH) is a manifestation of systemic metabolic disease related to obesity, and causes liver disease and cancer1,2. The accumulation of metabolites leads to cell stress and inflammation in the liver3, but mechanistic understandings of liver damage in NASH are incomplete. Here, using a preclinical mouse model that displays key features of human NASH (hereafter, NASH mice), we found an indispensable role for T cells in liver immunopathology. We detected the hepatic accumulation of CD8 T cells with phenotypes that combined tissue residency (CXCR6) with effector (granzyme) and exhaustion (PD1) characteristics. Liver CXCR6+ CD8 T cells were characterized by low activity of the FOXO1 transcription factor, and were abundant in NASH mice and in patients with NASH. Mechanistically, IL-15 induced FOXO1 downregulation and CXCR6 upregulation, which together rendered liver-resident CXCR6+ CD8 T cells susceptible to metabolic stimuli (including acetate and extracellular ATP) and collectively triggered auto-aggression. CXCR6+ CD8 T cells from the livers of NASH mice or of patients with NASH had similar transcriptional signatures, and showed auto-aggressive killing of cells in an MHC-class-I-independent fashion after signalling through P2X7 purinergic receptors. This killing by auto-aggressive CD8 T cells fundamentally differed from that by antigen-specific cells, which mechanistically distinguishes auto-aggressive and protective T cell immunity.

Toll-like receptor 3 expression in myeloid cells is essential for efficient regeneration after acute pancreatitis in mice.

Stringent regulation of the inflammatory response is crucial for normal tissue regeneration. Here, we analyzed the role of Toll-like receptor 3 (TLR3) in pancreatic regeneration after acute pancreatitis (AP). AP was induced by caerulein treatment in mice with global TLR3 deficiency (TLR3OFF ) or in mice re-expressing TLR3 exclusively in the myeloid cell lineage (TLR3Mye ). Compared to WT mice, TLR3OFF mice had a markedly increased formation of acinar-to-ductal metaplasia (ADM) that persisted until day 7 after initiation of AP. Pancreatic tissue of WT mice was completely regenerated after 5 days with no detectable ADM structures. The enhancing effect of TLR3-deficiency on ADM formation was closely linked with an increased and prolonged accumulation of macrophages in pancreata of TLR3OFF mice. Importantly, the phenotype of TLR3OFF mice was rescued in TLR3Mye mice, demonstrating the causative role of myeloid cell selective TLR3 signaling. Moreover, in vitro stimulation of macrophages through TLR3 initiated cell death by a caspase-8-associated mechanism. Therefore, these findings provide evidence that TLR3 signaling in myeloid cells is sufficient to limit inflammation and ADM formation and to promote regeneration after AP. Notably, resolution of inflammation after AP was associated with macrophage sensitivity to TLR3-mediated cell death.

Mechanisms of nonalcoholic fatty liver disease and implications for surgery.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) has become the most common form of chronic liver disease in both adults and children worldwide. Understanding the pathogenic mechanisms behind NAFLD provides the basis for identifying risk factors, such as metabolic syndrome, pancreatoduodenectomy, and host genetics, that lead to the onset and progression of the disease. The progression from steatosis to more severe forms, such as steatohepatitis, fibrosis, and cirrhosis, leads to an increased number of liver and non-liver complications. PURPOSE: NAFLD-associated end-stage liver disease (ESLD) and hepatocellular carcinoma (HCC) often require surgery as the only curative treatment. In particular, the presence of NAFLD together with the coexisting metabolic comorbidities that usually occur in these patients requires careful preoperative diagnosis and peri-/postoperative management. Bariatric surgery, liver resection, and liver transplantation (LT) have shown favorable results for weight loss, HCC, and ESLD in patients with NAFLD. The LT demand and the increasing spread of NAFLD in the donor pool reinforce the already existing lack of donor organs. CONCLUSION: In this review, we will discuss the diverse mechanisms underlying NAFLD, its implications for surgery, and the challenges for patient management.

Endothelial GATA4 controls liver fibrosis and regeneration by preventing a pathogenic switch in angiocrine signaling.

BACKGROUND & AIMS: Angiocrine signaling by liver sinusoidal endothelial cells (LSECs) regulates hepatic functions such as growth, metabolic maturation, and regeneration. Recently, we identified GATA4 as the master regulator of LSEC specification during development. Herein, we studied the role of endothelial GATA4 in the adult liver and in hepatic pathogenesis. METHODS: We generated adult Clec4g-icretg/0xGata4fl/fl (Gata4LSEC-KO) mice with LSEC-specific depletion of Gata4. Livers were analyzed by histology, electron microscopy, immunohistochemistry/immunofluorescence, in situ hybridization, and LSECs were isolated for gene expression profiling, ChIP- and ATAC-sequencing. Partial hepatectomy was performed to assess regeneration. We used choline-deficient, l-amino acid-defined (CDAA) diet and chronic carbon tetrachloride exposure to model liver fibrosis. Human single cell RNA-seq data sets were analyzed for endothelial alterations in healthy and cirrhotic livers. RESULTS: Genetic Gata4 deficiency in LSECs of adult mice caused perisinusoidal liver fibrosis, hepatopathy and impaired liver regeneration. Sinusoidal capillarization and LSEC-to-continuous endothelial transdifferentiation were accompanied by a profibrotic angiocrine switch involving de novo endothelial expression of hepatic stellate cell-activating cytokine PDGFB. Increased chromatin accessibility and amplification by activated MYC mediated angiocrine Pdgfb expression. As observed in Gata4LSEC-KO livers, CDAA diet-induced perisinusoidal liver fibrosis was associated with GATA4 repression, MYC activation and a profibrotic angiocrine switch in LSECs. Comparison of CDAA-fed Gata4LSEC-KO and control mice demonstrated that endothelial GATA4 indeed protects against dietary-induced perisinusoidal liver fibrosis. In human cirrhotic livers, GATA4-positive LSECs and endothelial GATA4 target genes were reduced, while non-LSEC endothelial cells and MYC target genes including PDGFB were enriched. CONCLUSIONS: Endothelial GATA4 protects against perisinusoidal liver fibrosis by repressing MYC activation and profibrotic angiocrine signaling at the chromatin level. Therapies targeting the GATA4/MYC/PDGFB/PDGFRß axis offer a promising strategy for prevention and treatment of liver fibrosis. LAY SUMMARY: The liver vasculature is supposed to play a major role in the development of liver fibrosis and cirrhosis, which can lead to liver failure and liver cancer. Herein, we discovered that structural and transcriptional changes induced by genetic deletion of the transcription factor GATA4 in the hepatic endothelium were sufficient to cause liver fibrosis. Activation of the transcription factor MYC and de novo expression of the "angiocrine" growth factor PDGFB were identified as downstream drivers of fibrosis and as potential therapeutic targets for this potentially fatal disease.