Organ-on-a-chip for studying immune cell adhesion to liver sinusoidal endothelial cells: the potential for testing immunotherapies and cell therapy trafficking.

Immunotherapy has changed the landscape of treatment options for patients with hepatocellular cancer. Checkpoint inhibitors are now standard of care for patients with advanced tumours, yet the majority remain resistant to this therapy and urgent approaches are needed to boost the efficacy of these agents. Targeting the liver endothelial cells, as the orchestrators of immune cell recruitment, within the tumour microenvironment of this highly vascular cancer could potentially boost immune cell infiltration. We demonstrate the successful culture of primary human liver endothelial cells in organ-on-a-chip technology followed by perfusion of peripheral blood mononuclear cells. We confirm, with confocal and multiphoton imaging, the capture and adhesion of immune cells in response to pro-inflammatory cytokines in this model. This multicellular platform sets the foundation for testing the efficacy of new therapies in promoting leukocyte infiltration across liver endothelium as well as a model for testing cell therapy, such as chimeric antigen receptor (CAR)-T cell, capture and migration across human liver endothelium.

The senescent secretome drives PLVAP expression in cultured human hepatic endothelial cells to promote monocyte transmigration.

Liver sinusoidal endothelial cells (LSEC) undergo significant phenotypic change in chronic liver disease (CLD), and yet the factors that drive this process and the impact on their function as a vascular barrier and gatekeeper for immune cell recruitment are poorly understood. Plasmalemma-vesicle-associated protein (PLVAP) has been characterized as a marker of LSEC in CLD; notably we found that PLVAP upregulation strongly correlated with markers of tissue senescence. Furthermore, exposure of human LSEC to the senescence-associated secretory phenotype (SASP) led to a significant upregulation of PLVAP. Flow-based assays demonstrated that SASP-driven leukocyte recruitment was characterized by paracellular transmigration of monocytes while the majority of lymphocytes migrated transcellularly. Knockdown studies confirmed that PLVAP selectively supported monocyte transmigration mediated through PLVAP's impact on LSEC permeability by regulating phospho-VE-cadherin expression and endothelial gap formation. PLVAP may therefore represent an endothelial target that selectively shapes the senescence-mediated immune microenvironment in liver disease.

Targeting Enclysis in Liver Autoimmunity, Transplantation, Viral Infection and Cancer.

Persistent liver inflammation can lead to cirrhosis, which associates with significant morbidity and mortality worldwide. There are no curative treatments beyond transplantation, followed by long-term immunosuppression. The global burden of end stage liver disease has been increasing and there is a shortage of donor organs, therefore new therapies are desperately needed. Harnessing the power of the immune system has shown promise in certain autoimmunity and cancer settings. In the context of the liver, regulatory T cell (Treg) therapies are in development. The hypothesis is that these specialized lymphocytes that dampen inflammation may reduce liver injury in patients with chronic, progressive diseases, and promote transplant tolerance. Various strategies including intrinsic and extracorporeal expansion of Treg cells, aim to increase their abundance to suppress immune responses. We recently discovered that hepatocytes engulf and delete Treg cells by enclysis. Herein, we propose that inhibition of enclysis may potentiate existing regulatory T cell therapeutic approaches in patients with autoimmune liver diseases and in patients receiving a transplant. Moreover, in settings where the abundance of Treg cells could hinder beneficial immunity, such us in chronic viral infection or liver cancer, enhancement of enclysis could result in transient, localized reduction of Treg cell numbers and tip the balance towards antiviral and anti-tumor immunity. We describe enclysis as is a natural process of liver immune regulation that lends itself to therapeutic targeting, particularly in combination with current Treg cell approaches.

Leptin Is Associated With Persistence of Hyperglycemia in Acute Pancreatitis: A Prospective Clinical Study.

Adipokines have many homeostatic roles, including modulation of glucose metabolism, but their role in the pathophysiology of hyperglycemia associated with acute and critical illnesses in general, and acute pancreatitis (AP) in particular, is largely unknown. This study aimed to investigate the relationship between a panel of adipokines and hyperglycemia in the early course of AP, as well as the role of adipokines as predictors of AP severity.Adiponectin, leptin, omentin, resistin, and visfatin were measured on a daily basis in the first 72 hours after hospital admission. A first set of analyses was undertaken with admission glycemia stratified by severity, and a second set of analyses was undertaken based on persistence of early hyperglycemia. All of the analyses were adjusted for confounders.A total of 32 patients with AP were included in this study. None of the studied adipokines was significantly associated with glucose level on admission. Leptin was significantly (P = 0.003) increased in patients with persistent hyperglycemia. Adiponectin was significantly associated with the Acute Physiology and Chronic Health Evaluation II (APACHE II) score in patients with persistent hyperglycemia (P = 0.015), visfatin with APACHE II score in patients with persistent hyperglycemia (P = 0.014), and omentin with APACHE II score in all of the patients regardless of the presence or absence of hyperglycemia (P = 0.021).Leptin is significantly associated with persistent hyperglycemia in the early course of AP. Omentin has a potential to become an accurate predictor of AP severity.

Relationship between the exocrine and endocrine pancreas after acute pancreatitis.

AIM: To determine the prevalence and time course of pancreatic exocrine insufficiency in individuals with newly diagnosed prediabetes or diabetes mellitus after acute pancreatitis. METHODS: Relevant literature cited in three major biomedical journal databases (EMBASE, MEDLINE, and Scopus) was reviewed independently by two authors. There were no language constraints but the search was limited to human studies. Studies included were cohort studies of adult patients who were discharged after an attack of acute pancreatitis. Patients were excluded if they were under 18 years of age or had a previous diagnosis of prediabetes or diabetes mellitus, pancreatic exocrine insufficiency, or chronic pancreatitis. The main outcome measure was the prevalence of concomitant pancreatic exocrine insufficiency in patients who were diagnosed with prediabetes and diabetes mellitus after an attack of acute pancreatitis. Subgroup analysis was conducted for patients who were diagnosed with prediabetes only and those who were diagnosed with diabetes mellitus only. Subgroup analysis looking at the time course of concomitant pancreatic exocrine and endocrine insufficiency was also conducted. Pooled prevalence and corresponding 95% confidence intervals were calculated for all outcome measures and P-values < 0.05 were deemed statistically significant. RESULTS: Eight clinical studies comprising of 234 patients met all eligibility criteria. The pooled prevalence of newly diagnosed prediabetes or diabetes in individuals after acute pancreatitis was 43% (95%CI: 30%-56%). The pooled prevalence of pancreatic exocrine insufficiency in individuals after acute pancreatitis was 29% (95%CI: 19%-39%). The prevalence of concomitant pancreatic exocrine insufficiency in individuals with newly diagnosed prediabetes or diabetes was 40% (95%CI: 25%-55%). The prevalence of concomitant pancreatic exocrine insufficiency among individuals with prediabetes alone and diabetes mellitus alone was 41% (95%CI: 12%-75%) and 39% (95%CI: 28%-51%), respectively. Further analysis showed that the prevalence of concomitant pancreatic exocrine insufficiency in individuals with prediabetes or diabetes decreases over time after an attack of acute pancreatitis. CONCLUSION: Pancreatic exocrine insufficiency occurs in 40% of individuals with newly diagnosed prediabetes or diabetes mellitus after acute pancreatitis. Further studies are needed to investigate the pathogenesis of diabetes in this setting.