Indicator of Inflammation and NETosis-Low-Density Granulocytes as a Biomarker of Autoimmune Hepatitis

Characteristics of peripheral blood mononuclear cells and potential related molecular mechanisms in patients with autoimmune hepatitis: a single-cell RNA sequencing analysis

Autoimmune hepatitis (AIH) is an immune disorder characterized by hypergammaglobulinemia, autoantibodies, and chronic active hepatitis on liver histology. However, immune cell population characteristics in AIH patients remain poorly understood. This study was designed to analyze peripheral blood mononuclear cell (PBMC) characteristics in AIH through single-cell RNA sequencing (scRNA-seq) and explore potential AIH-related molecular mechanisms. We generated 3690 and 3511 single-cell transcriptomes of PBMCs pooled from 4 healthy controls (HCs) and 4 AIH patients, respectively, by scRNA-seq. These pooled PBMC transcriptomes were used for cell cluster identification and differentially expressed gene (DEG) identification. GO functional enrichment analysis was performed on the DEGs to determine the most active AIH immune cell biological functions. Although the PCA-based uniform manifold approximation and projection (UMAP) algorithm was used to cluster cells with similar expression patterns in the two samples, 87 up- and 12 downregulated DEGs were retained in monocytes and 101 up- and 15 downregulated DEGs were retained in NK cells from AIH PBMCs. Moreover, enriched GO terms in the PBMC-derived monocyte and NK cell clusters were related mainly to antigen processing and presentation, IFN-γ-mediated signaling, and neutrophil degranulation and activation. These potential molecular mechanisms may be important targets for AIH treatment.

Could a reduced hemoglobin, albumin, lymphocyte, and platelet (HALP) score predict autoimmune hepatitis and degree of liver fibrosis?

OBJECTIVE

Autoimmune hepatitis is a rare inflammatory disease of the liver that is characterized by elevated liver enzymes. The hemoglobin, albumin, lymphocyte, and platelet score, which is derived from hemoglobin, serum albumin, circulating lymphocyte count, and platelet count, is also associated with inflammatory conditions. The aim was to examine the hemoglobin, albumin, lymphocyte, and platelet score of patients with autoimmune hepatitis and to compare it to that of healthy individuals in this retrospective analysis.

METHODS

Subjects diagnosed with autoimmune hepatitis were enrolled in the study, and healthy individuals were enrolled as controls. Moreover, autoimmune hepatitis subjects were grouped into mild or moderate/advanced fibrosis. Furthermore, aspartate to platelet ratio index, Fibrosis-4, and hemoglobin, albumin, lymphocyte, and platelet scores of the autoimmune hepatitis patients and controls were compared. In addition, the hemoglobin, albumin, lymphocyte, and platelet score of the autoimmune hepatitis patients with mild fibrosis is compared to that of those with moderate/advanced fibrosis.

RESULTS

The mean hemoglobin, albumin, lymphocyte, and platelet score of the autoimmune hepatitis patients was 44.2±14.5 while this value was 76.8±15.5 in control subjects. The hemoglobin, albumin, lymphocyte, and platelet score was significantly reduced in autoimmune hepatitis patients than healthy controls (p<0.001). The hemoglobin, albumin, lymphocyte, and platelet score was significantly and negatively correlated with C-reactive protein, aspartate, alanine transaminase, gamma glutamyl transferase, aspartate to platelet ratio index, and Fibrosis-4 values. A hemoglobin, albumin, lymphocyte, and platelet score that was lower than 52.3 had 83% sensitivity and 73% specificity in predicting autoimmune hepatitis. The sensitivity and specificity of the hemoglobin, albumin, lymphocyte, and platelet score were higher than the Fibrosis-4 score in predicting moderate/advanced fibrosis in autoimmune hepatitis.

CONCLUSION

We suggest that the hemoglobin, albumin, lymphocyte, and platelet score be used as an additional noninvasive diagnostic tool for autoimmune hepatitis and to predict moderate/advanced liver fibrosis in patients with autoimmune hepatitis.

A variety of death modes of neutrophils and their role in the etiology of autoimmune diseases

Neutrophils are important in the context of innate immunity and actively contribute to the progression of diverse autoimmune disorders. Distinct death mechanisms of neutrophils may exhibit specific and pivotal roles in autoimmune diseases and disease pathogenesis through the orchestration of immune homeostasis, the facilitation of autoantibody production, the induction of tissue and organ damage, and the incitement of pathological alterations. In recent years, more studies have provided in-depth examination of various neutrophil death modes, revealing nuances that challenge conventional understanding and underscoring their potential clinical utility in diagnosis and treatment. This review explores the multifaceted processes and characteristics of neutrophil death, with a focus on tailored investigations within various autoimmune diseases. It also highlights the potential interplay between neutrophil death and the landscape of autoimmune disorders. The review encapsulates the pertinent pathways implicated in various neutrophil death mechanisms across diverse autoimmune diseases while also charts possible avenues for future research.

The Gut Microbiome and Autoimmune Hepatitis: Implications for Early Diagnostic Biomarkers and Novel Therapies

Autoimmune hepatitis (AIH) is a serious chronic liver disease that may last for decades and eventually develop into cirrhosis and liver failure. In recent years, people have paid more attention to the microbiome-gut-liver axis, which provides guidance for all to explore the role of microbiome in the occurrence and development of liver diseases. In this review, the possible mechanism of intestinal microbes promoting the occurrence of AIH, mainly expounding the key ways such as bacterial ecological imbalance, intestinal leakage, and molecular simulation between microbes and autoantigens is summarized. In addition, this paper also discusses that intestinal microbiome has great potential as a biomarker for early diagnosis of AIH, and intestinal microbiome is also a candidate target for prevention and treatment of AIH. Finally, the study summarizes and prospects the targeted therapy of intestinal microorganisms to prevent the occurrence and development of AIH.

Neutrophil subsets in noncancer liver diseases: Cellular crosstalk and therapeutic targets

Neutrophils are the most abundant circulating granulocytes, linking innate and adaptive immunity. Neutrophils can regulate inflammatory and immune responses through degranulation, reactive oxygen species generation, the production of cytokines and chemokines, and NETosis. Emerging evidence has indicated that neutrophils contribute to the pathogenesis of various noncancer liver diseases, including nonalcoholic fatty liver disease, alcohol-associated liver disease, hepatic ischemia-reperfusion injury, and liver fibrosis. Cellular interactions among neutrophils, other immune cells, and nonimmune cells constitute a complex network that regulates the immune microenvironment of the liver. This review summarizes novel neutrophil subtypes, including CD177+ neutrophils and low-density neutrophils. Moreover, we provide an overview of the cellular cros stalk of neutrophils in noncancer liver diseases, aiming to shed new light on mechanistic studies of novel neutrophil subtypes. In addition, we discuss the potential of neutrophils as therapeutic targets in noncancer liver diseases, including inhibitors targeting NETosis, granule proteins, and chemokines.

ROS Production by a Single Neutrophil Cell and Neutrophil Population upon Bacterial Stimulation

The reactive oxygen species (ROS) production by a single neutrophil after stimulation with S. aureus and E. coli was estimated by an electrochemical amperometric method with a high time resolution. This showed significant variability in the response of a single neutrophil to bacterial stimulation, from a "silent cell" to a pronounced response manifested by a series of chronoamperometric spikes. The amount of ROS produced by a single neutrophil under the influence of S. aureus was 5.5-fold greater than that produced under the influence of E. coli. The response of a neutrophil granulocyte population to bacterial stimulation was analyzed using luminol-dependent biochemiluminescence (BCL). The stimulation of neutrophils with S. aureus, as compared to stimulation with E. coli, caused a total response in terms of ROS production that was seven-fold greater in terms of the integral value of the light sum and 13-fold greater in terms of the maximum peak value. The method of ROS detection at the level of a single cell indicated the functional heterogeneity of the neutrophil population, but the specificity of the cellular response to different pathogens was the same at the cellular and population levels.

PADs and NETs in digestive system: From physiology to pathology

Peptidylarginine deiminases (PADs) are the only enzyme class known to deiminate arginine residues into citrulline in proteins, a process known as citrullination. This is an important post-translational modification that functions in several physiological and pathological processes. Neutrophil extracellular traps (NETs) are generated by NETosis, a novel cell death in neutrophils and a double-edged sword in inflammation. Excessive activation of PADs and NETs is critically implicated in their transformation from a physiological to a pathological state. Herein, we review the physiological and pathological functions of PADs and NETs, in particular, the involvement of PAD2 and PAD4 in the digestive system, from inflammatory to oncological diseases, along with related therapeutic prospects.

Neutrophil extracellular traps and complications of liver transplantation

Many end-stage liver disease etiologies are attributed to robust inflammatory cell recruitment. Neutrophils play an important role in inflammatory infiltration and neutrophil phagocytosis, oxidative burst, and degranulation. It has also been suggested that neutrophils may release neutrophil extracellular traps (NETs) to kill pathogens. It has been proven that neutrophil infiltration within the liver contributes to an inflammatory microenvironment and immune cell activation. Growing evidence implies that NETs are involved in the progression of numerous complications of liver transplantation, including ischemia-reperfusion injury, acute rejection, thrombosis, and hepatocellular carcinoma recurrence. NETs are discussed in this comprehensive review, focusing on their effects on liver transplantation complications. Furthermore, we discuss NETs as potential targets for liver transplantation therapy.

Extracellular traps and the role in thrombosis

Thrombotic complications pose serious health risks worldwide. A significant change in our understanding of the pathophysiology of thrombosis has occurred since the discovery of extracellular traps (ETs) and their prothrombotic properties. As a result of immune cells decondensing chromatin into extracellular fibers, ETs promote thrombus formation by acting as a scaffold that activates platelets and coagulates them. The involvement of ETs in thrombosis has been reported in various thrombotic conditions including deep vein thrombosis (DVT), pulmonary emboli, acute myocardial infarction, aucte ischemic stroke, and abdominal aortic aneurysms. This review summarizes the existing evidence of ETs in human and animal model thrombi. The authors described studies showing the existence of ETs in venous or arterial thrombi. In addition, we studied potential novel therapeutic opportunities related to the resolution or prevention of thrombosis by targeting ETs.

Acute Liver Failure and Acute-on-Chronic Liver Failure in COVID-19 Era

Acute liver failure (ALF) and acute-on-chronic liver failure (ACLF), respectively, occur in patients with normal liver and patients with chronic liver diseases, including cirrhosis [...]