Immune Regulatory Mediators in Plasma from Patients With Acute Decompensation Are Associated With 3-Month Mortality

Mechanisms of immunity in acutely decompensated cirrhosis and acute-on-chronic liver failure

The identification of systemic inflammation (SI) as a central player in the orchestration of acute-on-chronic liver failure (ACLF) has opened new avenues for the understanding of the pathophysiological mechanisms underlying this disease condition. ACLF, which develops in patients with acute decompensation of cirrhosis, is characterized by single or multiple organ failure and high risk of short-term (28-day) mortality. Its poor outcome is closely associated with the severity of the systemic inflammatory response. In this review, we describe the key features of SI in patients with acutely decompensated cirrhosis and ACLF, including the presence of a high blood white cell count and increased levels of inflammatory mediators in systemic circulation. We also discuss the main triggers (i.e. pathogen- and damage-associated molecular patterns), the cell effectors (i.e. neutrophils, monocytes and lymphocytes), the humoral mediators (acute phase proteins, cytokines, chemokines, growth factors and bioactive lipid mediators) and the factors that influence the systemic inflammatory response that drive organ failure and mortality in ACLF. The role of immunological exhaustion and/or immunoparalysis in the context of exacerbated inflammatory responses that predispose ACLF patients to secondary infections and re-escalation of end-organ dysfunction and mortality are also reviewed. Finally, several new potential immunogenic therapeutic targets are debated.

The Impact of Liver Failure on the Immune System

Liver failure profoundly affects the immune system, leading to dysregulation of innate and adaptive immune response. This review explores the intricate relationship between liver function and immune homeostasis. The role of the liver as a central hub in immune response initiation is elucidated, emphasizing its involvement in hepatic inflammation induction and subsequent systemic inflammation. Cytokines, chemokines, growth factors, and lipid mediators orchestrate these immune processes, serving as both prognostic biomarkers and potential therapeutic targets in liver failure-associated immune dysregulation, which might result from acute-on-chronic liver failure (ACLF) and cirrhosis. Furthermore, the review delves into the mechanisms underlying immunosuppression in liver failure, encompassing alterations in innate immune cell functions such as neutrophils, macrophages, and natural killer cells (NK cells), as well as perturbations in adaptive immune responses mediated by B and T cells. Conclusion: Understanding the immunological consequences of liver failure is crucial for developing targeted therapeutic interventions and improving patient outcomes in liver disease management.

The application of extracorporeal shock wave therapy on stem cells therapy to treat various diseases

In the last ten years, stem cell (SC) therapy has been extensively used to treat a range of conditions such as degenerative illnesses, ischemia-related organ dysfunction, diabetes, and neurological disorders. However, the clinical application of these therapies is limited due to the poor survival and differentiation potential of stem cells (SCs). Extracorporeal shock wave therapy (ESWT), as a non-invasive therapy, has shown great application potential in enhancing the proliferation, differentiation, migration, and recruitment of stem cells, offering new possibilities for utilizing ESWT in conjunction with stem cells for the treatment of different systemic conditions. The review provides a detailed overview of the advances in using ESWT with SCs to treat musculoskeletal, cardiovascular, genitourinary, and nervous system conditions, suggesting that ESWT is a promising strategy for enhancing the efficacy of SC therapy for various diseases.

Roles of systemic inflammatory and metabolic responses in the pathophysiology of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is the most severe form of acutely decompensated cirrhosis and is characterised by the presence of one or more organ failures, intense systemic inflammation, peripheral blood lymphopenia, and a high risk of death without liver transplantation within 28 days. Herein, we propose the hypothesis that intense systemic inflammation may lead to organ failures through five different non-mutually exclusive mechanisms. First, pathogen-associated molecular patterns and inflammatory mediators (i.e. cytokines and lipid mediators) stimulate the production of the vasorelaxant nitric oxide in the walls of splanchnic arterioles, leading to enhanced splanchnic and systemic vasodilation which, in turn, induces enhanced activity of endogenous vasoconstrictor systems causing renal vasoconstriction and acute kidney injury. Second, neutrophils that reach the systemic circulation are prone to adhere to the vascular endothelium. Cytokines and lipid mediators act on the endothelium in microvessels of vital organs, an effect that favours the migration of neutrophils (and probably other leukocytes) to surrounding tissues where neutrophils can cause tissue damage and thereby contribute to organ failure. Third, cytokines and lipid mediators promote the formation of microthrombi that impair microcirculation and tissue oxygenation. Fourth, acute inflammation stimulates intense peripheral catabolism of amino acids whose products may be metabotoxins that contribute to hepatic encephalopathy. Fifth, acute inflammatory responses, which include the production of a broad variety of biomolecules (proteins and lipids), and an increase in biomass (i.e., granulopoiesis requiring de novo nucleotide synthesis), among others, are energetically expensive processes that require large amounts of nutrients. Therefore, immunity competes with other maintenance programmes for energy. The brain stem integrates the energy demand of each organ system, with immunity considered a top priority. The brain stem may "decide" to make a trade-off which involves the induction of a dormancy programme that permits the shutdown of mitochondrial respiration and oxidative phosphorylation in peripheral organs. In the context of acutely decompensated cirrhosis, the consequence of a shutdown of mitochondrial respiration and ATP production would be a dramatic decrease in organ function.

Evaluating the Role of Antibiotics in Patients Admitted to Hospital With Decompensated Cirrhosis: Lessons From the ATTIRE Trial

INTRODUCTION

Hospital-acquired infections (HAI) are common in cirrhosis with antibiotics frequently used to prevent infections, but their efficacy for this role is unknown. To investigate this, we used Albumin to Prevent Infection in Chronic Liver Failure (ATTIRE) data to evaluate whether antibiotic use in patients without infection prevented HAI.

METHODS

In ATTIRE patients without infection at baseline grouped by antibiotic prescription or not, we studied HAI during trial treatment period and mortality, with propensity score matching to account for differences in disease severity.

RESULTS

Two hundred three of 408 patients prescribed antibiotics at enrollment did not have infection and they were more unwell than noninfected patients not given antibiotics. There were no differences in subsequent HAI comparing antibiotic treated (39/203, 19.2%) to nonantibiotic treated (73/360, 20.3%; P = 0.83). Twenty-eight-day mortality was higher in antibiotic-treated patients ( P = 0.004) likely reflecting increased disease severity. Matching groups using propensity scoring revealed no differences in HAI or mortality. In noninfected patients at enrollment treated with/without rifaximin, there were no differences in HAI ( P = 0.16) or mortality, confirmed with propensity matching. Patients given long-term antibiotic prophylaxis at discharge had no differences in 6-month mortality compared with nonantibiotic patients, although antibiotic-treated patients had more infections at trial entry, with numbers too small for matching.

DISCUSSION

Half of antibiotics at study entry were given to patients without an infection diagnosis which did not reduce the overall risk of HAI or improve mortality. This supports prompt de-escalation or discontinuation of antibiotics guided by culture sensitivities at 24-48 hours after commencement if no infection and the patient is improving.

Lipids in Liver Failure Syndromes: A Focus on Eicosanoids, Specialized Pro-Resolving Lipid Mediators and Lysophospholipids

Lipids are organic compounds insoluble in water with a variety of metabolic and non-metabolic functions. They not only represent an efficient energy substrate but can also act as key inflammatory and anti-inflammatory molecules as part of a network of soluble mediators at the interface of metabolism and the immune system. The role of endogenous bioactive lipid mediators has been demonstrated in several inflammatory diseases (rheumatoid arthritis, inflammatory bowel disease, atherosclerosis, cancer). The liver is unique in providing balanced immunotolerance to the exposure of bacterial components from the gut transiting through the portal vein and the lymphatic system. This balance is abruptly deranged in liver failure syndromes such as acute liver failure and acute-on-chronic liver failure. In these syndromes, researchers have recently focused on bioactive lipid mediators by global metabonomic profiling and uncovered the pivotal role of these mediators in the immune dysfunction observed in liver failure syndromes explaining the high occurrence of sepsis and subsequent organ failure. Among endogenous bioactive lipids, the mechanistic actions of three classes (eicosanoids, pro-resolving lipid mediators and lysophospholipids) in the pathophysiological modulation of liver failure syndromes will be the topic of this narrative review. Furthermore, the therapeutic potential of lipid-immune pathways will be described.

Monocyte dysfunction in decompensated cirrhosis is mediated by the prostaglandin E2-EP4 pathway

BACKGROUND & AIMS

Infection is a major problem in advanced liver disease secondary to monocyte dysfunction. Elevated prostaglandin (PG)E₂ is a mediator of monocyte dysfunction in cirrhosis; thus, we examined PGE₂ signalling in outpatients with ascites and in patients hospitalised with acute decompensation to identify potential therapeutic targets aimed at improving monocyte dysfunction.

METHODS

Using samples from 11 outpatients with ascites and 28 patients hospitalised with decompensated cirrhosis, we assayed plasma levels of PGE₂ and lipopolysaccharide (LPS); performed quantitative real-time PCR on monocytes; and examined peripheral blood monocyte function. We performed western blotting and immunohistochemistry for PG biosynthetic machinery expression in liver tissue. Finally, we investigated the effect of PGE₂ antagonists in whole blood using polychromatic flow cytometry and cytokine production.

RESULTS

We show that hepatic production of PGE₂ via the cyclo-oxygenase 1-microsomal PGE synthase 1 pathway, and circulating monocytes contributes to increased plasma PGE₂ in decompensated cirrhosis. Transjugular intrahepatic sampling did not reveal whether hepatic or monocytic production was larger. Blood monocyte numbers increased, whereas individual monocyte function decreased as patients progressed from outpatients with ascites to patients hospitalised with acute decompensation, as assessed by Human Leukocyte Antigen (HLA)-DR isotype expression and tumour necrosis factor alpha and IL6 production. PGE₂ mediated this dysfunction via its EP₄ receptor.

CONCLUSIONS

PGE₂ mediates monocyte dysfunction in decompensated cirrhosis via its EP₄ receptor and dysfunction was worse in hospitalised patients compared with outpatients with ascites. Our study identifies a potential drug target and therapeutic opportunity in these outpatients with ascites to reverse this process to prevent infection and hospital admission.

LAY SUMMARY

Patients with decompensated cirrhosis (jaundice, fluid build-up, confusion, and vomiting blood) have high infection rates that lead to high mortality rates. A white blood cell subset, monocytes, function poorly in these patients, which is a key factor underlying their sensitivity to infection. We show that monocyte dysfunction in decompensated cirrhosis is mediated by a lipid hormone in the blood, prostaglandin E₂, which is present at elevated levels, via its EP₄ pathway. This dysfunction worsens when patients are hospitalised with complications of cirrhosis compared with those in the outpatients setting, which supports the EP₄ pathway as a potential therapeutic target for patients to prevent infection and hospitalisation.

Leveraging omics to understand the molecular basis of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a complex syndrome that develops in patients with acutely decompensated cirrhosis. In this condition, dysbalanced immune function and excessive systemic inflammation are closely associated with organ failure and high short-term mortality. In this review, we describe how omic technologies have contributed to the characterization of the hyperinflammatory state in patients with acutely decompensated cirrhosis developing ACLF, with special emphasis on the role of metabolomics, lipidomics and transcriptomics in profiling the triggers (pathogen- and damage-associated molecular patterns [PAMPs and DAMPs]) and effector molecules (cytokines, chemokines, growth factors and bioactive lipid mediators) that lead to activation of the innate immune system. This review also describes how omic approaches can be invaluable tools to accelerate the identification of novel biomarkers that could guide the implementation of novel therapies/interventions aimed at protecting these patients from excessive systemic inflammation and organ failure.

Proresolving lipid mediators and liver disease

Inflammation is a characteristic feature of virtually all acute and chronic liver diseases. It intersects different liver pathologies from the early stages of liver injury, when the inflammatory burden is mild-to-moderate, to very advanced stages of liver disease, when the inflammatory response is very intense and drives multiple organ dysfunction and failure(s). The current review describes the most relevant features of the inflammatory process in two different clinical entities across the liver disease spectrum, namely non-alcoholic steatohepatitis (NASH) and acute-on-chronic liver failure (ACLF). Special emphasis is given within these two disease conditions to gather the most relevant data on the specialized pro-resolving mediators that orchestrate the resolution of inflammation, a tightly controlled process which dysregulation commonly associates with chronic inflammatory conditions.

Blood Glucose and Renal Function Evaluation in Patients with Viral Hepatitis

PURPOSE

To evaluate the blood glucose and renal function, determine the prevalence of hyperglycemia/diabetes mellitus (DM) and renal disease (nephropathy), and investigate the association between hyperglycemia/DM and renal disease in patients with viral hepatitis (VH).

PATIENTS AND METHODS

A total of 491 subjects were included in the study. Patients with VH were further divided into the hepatitis B virus (HBV) infection, hepatitis C virus (HCV) infection, and HBV-HCV co-infection subgroups. Fasting blood glucose, glycated hemoglobin (HbA1c), glycated albumin (GA), glutamic oxaloacetic transaminase (GOT), creatinine (Cr), and cystatin C (Cys C) levels were measured. Urine microalbumin levels were also assessed. Formulas for estimated average glucose calculated using glycated albumin(eAG(GA)), estimated average glucose calculated using HbA1c (eAG(HbA1c)), and estimated glomerular filtration rate calculated using cystatin C (eGFRcys) were used to evaluate the average glucose and renal function.

RESULTS

The prevalence of hyperglycemia/DM and renal disease was significantly higher in the VH group, especially in the HCV subgroup. The prevalence of renal disease was significantly higher in patients with VH with eAG(GA) ≥200 mg/dL.

CONCLUSION

Our study used multiple parameters to evaluate blood glucose and renal function in patients with VH and found that hyperglycemia/DM and renal disease are closely associated with VH, especially in subjects with HCV infection. Patients with VH, especially those with HCV infection and hyperglycemia/DM, were particularly vulnerable to renal disease.

The potential of lipid mediator networks as ocular surface therapeutics and biomarkers

In the last twenty years an impressive body of evidence in diverse inflammatory animal disease models and human tissues, has established polyunsaturated fatty acids (PUFA) derived specialized-pro-resolving mediators (SPM), as essential mediators for controlling acute inflammation, immune responses, wound healing and for resolving acute inflammation in many non-ocular tissues. SPM pathways and receptors are highly expressed in the ocular surface where they regulate wound healing, nerve regeneration, innate immunity and sex-specific regulation of auto-immune responses. Recent evidence indicates that in the eye these resident SPM networks are important for maintaining ocular surface health and immune homeostasis. Here, we will review and discuss evidence for SPMs and other PUFA-derived mediators as important endogenous regulators, biomarkers for ocular surface health and disease and their therapeutic potential.

Leukocytes, Systemic Inflammation and Immunopathology in Acute-on-Chronic Liver Failure

Acute-on-chronic liver failure (ACLF) is a complex syndrome that develops in patients with cirrhosis and is characterized by acute decompensation, organ failure(s) and high short-term mortality. ACLF frequently occurs in close temporal relationship to a precipitating event, such as acute alcoholic, drug-induced or viral hepatitis or bacterial infection and, in cases without precipitating events, probably related to intestinal translocation of bacterial products. Dysbalanced immune function is central to its pathogenesis and outcome with an initial excessive systemic inflammatory response that drives organ failure and mortality. This hyperinflammatory state ultimately impairs the host defensive mechanisms of immune cells, rendering ACLF patients immunocompromised and more vulnerable to secondary infections, and therefore to higher organ dysfunction and mortality. In this review, we describe the prevailing characteristics of the hyperinflammatory state in patients with acutely decompensated cirrhosis developing ACLF, with special emphasis on cells of the innate immune system (i.e., monocytes and neutrophils), their triggers (pathogen- and damage-associated molecular patterns [PAMPs and DAMPs]), their effector molecules (cytokines, chemokines, growth factors and bioactive lipid mediators) and the consequences on tissue immunopathology. In addition, this review includes a chapter discussing new emerging therapies based on the modulation of leukocyte function by the administration of pleiotropic proteins such as albumin, Toll-like receptor 4 antagonists, interleukin-22 or stem cell therapy. Finally, the importance of finding an appropriate intervention that reduces inflammation without inducing immunosuppression is highlighted as one of the main therapeutic challenges in cirrhosis.