Circulating Neutrophils of Nonalcoholic Steatohepatitis Patients Show an Activated Phenotype and Suppress T Lymphocytes Activity

Association between neutrophil-to-high-density lipoprotein cholesterol ratio and non-alcoholic fatty liver disease or metabolic dysfunction-associated steatotic liver disease: evidence from NHANES 2017-2020

Background

Non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD) is closely associated with chronic inflammation and lipid metabolism disorders. The neutrophil-to-high-density lipoprotein cholesterol ratio (NHR) is an integrative marker reflecting inflammatory responses and lipid metabolism disorders and is associated with various diseases. This cross-sectional study aimed to determine the association between NHR and NAFLD, MASLD, and liver fibrosis.

Methods

Data for this study were obtained from the 2017-2020 National Health and Nutrition Examination Survey (NHANES), we employed weighted multiple regression and restricted cubic spline (RCS) analysis to assess the relationship between NHR and NAFLD, MASLD, and liver fibrosis. Additionally, we performed stratified analyses based on gender, age, body mass index, diabetes, hypertension, smoking status, and history of cardiovascular disease to evaluate the consistency of these associations across different subgroups.

Results

A total of 6,526 participants were included in the study. 2,839 (weighted 44.1%) participants were diagnosed with NAFLD and 2,813 (weighted 43.7%) participants were diagnosed with MASLD. After adjusting for confounders, NHR was positively associated with the risk of NAFLD/MASLD, and the correlation was particularly significant in the subgroups of females, those without hypertension, and those without diabetes (p < 0.05). By the NHR quartile, the risk of NAFLD/MASLD increased progressively with higher NHR levels (P for trend <0.001). In addition, RCS analysis showed a nonlinear association between NHR and NAFLD/MASLD and liver fibrosis (P-non-linear <0.05).

Conclusion

NHR may serve as a potential marker for NAFLD/MASLD and liver fibrosis, and lowering NHR levels could help reduce the incidence of these conditions.

Application of Nanomaterials Targeting Immune Cells in the Treatment of Chronic Inflammation

Chronic inflammation is a common characteristic of all kinds of diseases, including autoimmune diseases, metabolic diseases, and tumors. It is distinguished by the presence of low concentrations of inflammatory factors stimulating the body for an extended period, resulting in a persistent state of infection. This condition is manifested by the aggregation and infiltration of mononuclear cells, lymphocytes, and other immune cells, leading to tissue hyperplasia and lesions. Although various anti-inflammatory medications, including glucocorticoids and non-steroidal anti-inflammatory drugs (NSAIDs), have shown strong therapeutic effects, they lack specificity and targeting ability, and require high dosages, which can lead to severe adverse reactions. Nanoparticle drug delivery mechanisms possess the capacity to minimize the effect on healthy cells or tissues due to their targeting capabilities and sustained drug release properties. However, most nanosystems can only target the inflammatory sites rather than specific types of immune cells, leaving room for further improvement in the therapeutic effects of nanomaterials. This article reviews the current research progress on the role of diverse immune cells in inflammation, focusing on the functions of neutrophils and macrophages during inflammation. It provides an overview of the domestic and international applications of nanomaterials in targeted therapy for inflammation, aiming to establish a conceptual foundation for the utilization of nanomaterials targeting immune cells in the treatment of chronic inflammation and offer new perspectives for the avoidance and management of inflammation.

The Evolving Role of Neutrophils and Neutrophil Extracellular Traps (NETs) in Obesity and Related Diseases: Recent Insights and Advances

Obesity is a chronic, multifactorial disease characterized by persistent low-grade tissue and systemic inflammation. Fat accumulation in adipose tissue (AT) leads to stress and dysfunctional adipocytes, along with the infiltration of immune cells, which initiates and sustains inflammation. Neutrophils are the first immune cells to infiltrate AT during high-fat diet (HFD)-induced obesity. Emerging evidence suggests that the formation and release of neutrophil extracellular traps (NETs) play a significant role in the progression of obesity and related diseases. Additionally, obesity is associated with an imbalance in gut microbiota and increased intestinal barrier permeability, resulting in the translocation of live bacteria, bacterial deoxyribonucleic acid (DNA), lipopolysaccharides (LPS), and pro-inflammatory cytokines into the bloodstream and AT, thereby contributing to metabolic inflammation. Recent research has also shown that short-chain fatty acids (SCFAs), produced by gut microbiota, can influence various functions of neutrophils, including their activation, migration, and the generation of inflammatory mediators. This review comprehensively summarizes recent advancements in understanding the role of neutrophils and NET formation in the pathophysiology of obesity and related disorders while also focusing on updated potential therapeutic approaches targeting NETs based on studies conducted in humans and animal models.

Neutrophil/lymphocyte ratio identifies low-risk polycythaemia vera patients for early Ropeginterferon alfa-2b therapy

We investigated the effect of Ropeginterferon alfa-2b (Ropeg) versus phlebotomy-only (Phl-O) on the neutrophil-to-lymphocyte ratio (NLR) in 126 patients randomized in the low-polycythaemia vera (PV) phase II trial. Patients with a baseline NLR ≥3.5 vs. <3.5 had a longer history of PV, were more likely to have splenomegaly, higher JAK2V617F variant allele frequency (VAF) (56% vs. 20% p = 0.001) and more proliferative disease. Ropeg was superior to Phl-O in reducing NLR (p = 0.008), and the reduction was strongly influenced by the reduction in neutrophils and less by a change in lymphocytes (-59% and -14% respectively). This effect was associated with the achievement of the low-PV primary end-point (p = 0.021), symptom reduction and reduction in JAK2 VAF. Interestingly, the reduction in JAK2 VAF from baseline was linearly associated with the reduction in NLR. Patients who failed Phl-O at 12 months had characteristics that distinguished them from responders, including very high NLR and resistance to cross-over to 100 μg Ropeg every 2 weeks suggesting higher escalated doses of Ropeg. In conclusion, the study provides evidence that NLR can serve as a valuable biomarker to assess and guide treatment with Ropeg in the early stage of low-risk PV patients.

A machine learning-based predictive model discriminates nonalcoholic steatohepatitis from nonalcoholic fatty liver disease

Background

Non-alcoholic fatty liver disease (NAFLD) is a leading cause of liver-related morbidity and mortality. The diagnosis of non-alcoholic steatohepatitis (NASH) plays a crucial role in the management of NAFLD patients.

Objective

The aim of our observational study was to build a machine learning model to identify NASH in NAFLD patients.

Methods

The clinical characteristics of 259 NAFLD patients and their initial laboratory data (Cohort 1) were collected to train the model and carry out internal validation. We compared the models built by five machine learning algorithms and screened out the best models. Receiver operating characteristic (ROC) curves, sensitivity, specificity, and accuracy were used to evaluate the performance of the model. In addition, the NAFLD patients in Cohort 2 (n = 181) were externally verified.

Results

We finally identified six independent risk factors for predicting NASH, including neutrophil percentage (NEU%), aspartate aminotransferase/alanine aminotransferase (AST/ALT), hematocrit (HCT), creatinine (CREA), uric acid (UA), and prealbumin (PA). The NASH-XGB6 model built using the XGBoost algorithm showed sufficient prediction accuracy, with ROC values of 0.95 (95 % CI, 0.91-0.98) and 0.90 (95 % CI, 0.88-0.93) in Cohort 1 and Cohort 2, respectively.

Conclusions

NASH-XGB6 can serve as an effective tool for distinguishing NASH patients from NAFLD patients.

Circulating Neutrophil Profiles Undergo a Dynamic Shift during Metabolic Dysfunction-Associated Steatohepatitis (MASH) Progression

Neutrophils play a crucial role in host defense against infection. Aberrant neutrophil activation may induce tissue damage via sterile inflammation. Neutrophil accumulation has been identified as a feature of the inflammatory response observed in metabolic dysfunction-associated steatohepatitis (MASH) and has been associated with liver fibrosis and cirrhosis. Here, we performed the transcriptomic analysis of circulating neutrophils from mild and advanced MASH patients to identify the potential mechanism behind neutrophil contribution to MASH progression. Our findings demonstrated that circulating neutrophils from mild and advanced MASH display an increased activated transcriptional program, with the expression of pro-inflammatory factors and an amplified lifespan compared to cells from non-diseased controls. Our results also suggest that MASH progression is associated with a dynamic shift in the profile of circulating neutrophils. In the early stages of MASH, mature neutrophils predominate in the bloodstream. As hepatic inflammation and fibrosis progress, the premature release of immature neutrophils into the circulation occurs. These immature neutrophils exhibit a pro-inflammatory profile that may exacerbate inflammation and promote fibrosis in MASH.

FOXO1 reshapes neutrophils to aggravate acute brain damage and promote late depression after traumatic brain injury

BACKGROUND

Neutrophils are traditionally viewed as first responders but have a short onset of action in response to traumatic brain injury (TBI). However, the heterogeneity, multifunctionality, and time-dependent modulation of brain damage and outcome mediated by neutrophils after TBI remain poorly understood.

METHODS

Using the combined single-cell transcriptomics, metabolomics, and proteomics analysis from TBI patients and the TBI mouse model, we investigate a novel neutrophil phenotype and its associated effects on TBI outcome by neurological deficit scoring and behavioral tests. We also characterized the underlying mechanisms both in vitro and in vivo through molecular simulations, signaling detections, gene expression regulation assessments [including dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays], primary cultures or co-cultures of neutrophils and oligodendrocytes, intracellular iron, and lipid hydroperoxide concentration measurements, as well as forkhead box protein O1 (FOXO1) conditional knockout mice.

RESULTS

We identified that high expression of the FOXO1 protein was induced in neutrophils after TBI both in TBI patients and the TBI mouse model. Infiltration of these FOXO1high neutrophils in the brain was detected not only in the acute phase but also in the chronic phase post-TBI, aggravating acute brain inflammatory damage and promoting late TBI-induced depression. In the acute stage, FOXO1 upregulated cytoplasmic Versican (VCAN) to interact with the apoptosis regulator B-cell lymphoma-2 (BCL-2)-associated X protein (BAX), suppressing the mitochondrial translocation of BAX, which mediated the antiapoptotic effect companied with enhancing interleukin-6 (IL-6) production of FOXO1high neutrophils. In the chronic stage, the "FOXO1-transferrin receptor (TFRC)" mechanism contributes to FOXO1high neutrophil ferroptosis, disturbing the iron homeostasis of oligodendrocytes and inducing a reduction in myelin basic protein, which contributes to the progression of late depression after TBI.

CONCLUSIONS

FOXO1high neutrophils represent a novel neutrophil phenotype that emerges in response to acute and chronic TBI, which provides insight into the heterogeneity, reprogramming activity, and versatility of neutrophils in TBI.

Molecular mechanisms in MASLD/MASH-related HCC

Liver cancer is the third leading cause of cancer-related deaths and ranks as the sixth most prevalent cancer type globally. NAFLD or metabolic dysfunction-associated steatotic liver disease, and its more severe manifestation, NASH or metabolic dysfunction-associated steatohepatitis (MASH), pose a significant global health concern, affecting approximately 20%-25% of the population. The increased prevalence of metabolic dysfunction-associated steatotic liver disease and MASH is parallel to the increasing rates of obesity-associated metabolic diseases, including type 2 diabetes, insulin resistance, and fatty liver diseases. MASH can progress to MASH-related HCC (MASH-HCC) in about 2% of cases each year, influenced by various factors such as genetic mutations, carcinogen exposure, immune microenvironment, and microbiome. MASH-HCC exhibits distinct molecular and immune characteristics compared to other causes of HCC and affects both men and women equally. The management of early to intermediate-stage MASH-HCC typically involves surgery and locoregional therapies, while advanced HCC is treated with systemic therapies, including anti-angiogenic therapies and immune checkpoint inhibitors. In this comprehensive review, we consolidate previous research findings while also providing the most current insights into the intricate molecular processes underlying MASH-HCC development. We delve into MASH-HCC-associated genetic variations and somatic mutations, disease progression and research models, multiomics analysis, immunological and microenvironmental impacts, and discuss targeted/combined therapies to overcome immune evasion and the biomarkers to recognize treatment responders. By furthering our comprehension of the molecular mechanisms underlying MASH-HCC, our goal is to catalyze the advancement of more potent treatment strategies, ultimately leading to enhanced patient outcomes.

Neutrophil-to-lymphocyte ratio and all-cause mortality with and without myeloproliferative neoplasms-a Danish longitudinal study

The neutrophil-to-lymphocyte ratio(NLR) is increased in chronic inflammation and myeloproliferative neoplasms (MPN). We hypothesize that NLR is associated with all-cause mortality and mortality by comorbidity burden in the general population and individuals with MPN. We included 835,430 individuals from The Danish General Suburban Population Study, general practitioners, and outpatient clinics. We investigated NLR on mortality stratified by prevalent and incident MPN, essential thrombocythemia (ET), polycythemia vera (PV), myelofibrosis (MF), comorbidity burden (CCI-score), and the Triple-A risk score using hazard ratio (HR) and 95% confidence interval (95%CI). NLR 1-1.9 was the reference level. During a median follow-up of 11.2 years, 197,802 deaths were recorded. All-cause mortality increased for a stepwise increasing NLR with a HR (95%CI) for NLR ≥ 6 of 2.06(2.03-2.09) for the whole population and 2.93(2.44-3.50) in prevalent MPN. ET, PV, and MF had a HR (95%CI) for NLR ≥ 2 of 2.14(1.71-2.69), 2.19(1.89-2.54), and 2.31(1.91-2.80). Results were similar for incident MPN. Mortality was higher for stepwise increasing NLR and CCI-score(pinteraction < 2×10-16), with a HR for NLR ≥ 6 of 2.23(2.17-2.29), 4.10(4.01-4.20), and 7.69(7.50-7.89), for CCI-score 0, 1-2, or ≥3. The Triple-A risk score demonstrated alignment with NLR. Increasing NLR and comorbidity burden were associated with lower survival in individuals without MPN but were even worse in prevalent and incident MPN, ET, PV, and MF.

State of CD8+ T cells in progression from nonalcoholic steatohepatitis to hepatocellular carcinoma: From pathogenesis to immunotherapy

With the obesity epidemic, nonalcoholic steatohepatitis (NASH) is emerging as the fastest growing potential cause of hepatocellular carcinoma (HCC). NASH has been demonstrated to establish a tumor-prone liver microenvironment where both innate and adaptive immune systems are involved. As the most typical anti-tumor effector, the cell function of CD8+ T cells is remodeled by chronic inflammation, metabolic alteration, lipid toxicity and oxidative stress in the liver microenvironment along the NASH to HCC transition. Unexpectedly, NASH may blunt the effect of immune checkpoint inhibitor therapy against HCC due to the dysregulated CD8+ T cells. Growing evidence has supported that NASH is likely to facilitate the state transition of CD8+ T cells with changes in cell motility, effector function, metabolic reprogramming and gene transcription according to single-cell sequencing. However, the mechanistic insight of CD8+ T cell states in the NASH-driven HCC is not comprehensive. Herein, we focus on the characterization of state phenotypes of CD8+ T cells with both functional and metabolic signatures in NASH-driven fibrosis and HCC. The NASH-specific CD8+ T cells are speculated to mainly have a dualist effect, where its aberrant activated phenotype sustains chronic inflammation in NASH but subsequently triggers its exhaustion in HCC. As the exploration of CD8+ T cells on the distribution and phenotypic shifts will provide a new direction for the intervention strategies against HCC, we also discuss the implications for targeting different phenotypes of CD8+ T cells, shedding light on the personalized immunotherapy for NASH-driven HCC.

The perspectives of NETosis on the progression of obesity and obesity-related diseases: mechanisms and applications

Obesity is a disease commonly associated with urbanization and can also be characterized as a systemic, chronic metabolic condition resulting from an imbalance between energy intake and expenditure. The World Health Organization (WHO) has identified obesity as the most serious chronic disease that is increasingly prevalent in the world population. If left untreated, it can lead to dangerous health issues such as hypertension, hyperglycemia, hyperlipidemia, hyperuricemia, nonalcoholic steatohepatitis, atherosclerosis, and vulnerability to cardiovascular and cerebrovascular events. The specific mechanisms by which obesity affects the development of these diseases can be refined to the effect on immune cells. Existing studies have shown that the development of obesity and its associated diseases is closely related to the balance or lack thereof in the number and function of various immune cells, of which neutrophils are the most abundant immune cells in humans, infiltrating and accumulating in the adipose tissues of obese individuals, whereas NETosis, as a newly discovered type of neutrophil-related cell death, its role in the development of obesity and related diseases is increasingly emphasized. The article reviews the significant role that NETosis plays in the development of obesity and related diseases, such as diabetes and its complications. It discusses the epidemiology and negative impacts of obesity, explains the mechanisms of NETosis, and examines its potential as a targeted drug to treat obesity and associated ailments.

Decoding the role of immune T cells: A new territory for improvement of metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) is a new emerging concept and is associated with metabolic dysfunction, generally replacing the name of nonalcoholic fatty liver disease (NAFLD) due to heterogeneous liver condition and inaccuracies in definition. The prevalence of MAFLD is rising by year due to dietary changes, metabolic disorders, and no approved therapy, affecting a quarter of the global population and representing a major economic problem that burdens healthcare systems. Currently, in addition to the common causative factors like insulin resistance, oxidative stress, and lipotoxicity, the role of immune cells, especially T cells, played in MAFLD is increasingly being emphasized by global scholars. Based on the diverse classification and pathophysiological effects of immune T cells, we comprehensively analyzed their bidirectional regulatory effects on the hepatic inflammatory microenvironment and MAFLD progression. This interaction between MAFLD and T cells was also associated with hepatic-intestinal immune crosstalk and gut microbiota homeostasis. Moreover, we pointed out several T-cell-based therapeutic approaches including but not limited to adoptive transfer of T cells, fecal microbiota transplantation, and drug therapy, especially for natural products and Chinese herbal prescriptions. Overall, this study contributes to a better understanding of the important role of T cells played in MAFLD progression and corresponding therapeutic options and provides a potential reference for further drug development.

Overview of Cellular and Soluble Mediators in Systemic Inflammation Associated with Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is currently the most prevalent chronic liver disease in Western countries, affecting approximately 25% of the adult population. This condition encompasses a spectrum of liver diseases characterized by abnormal accumulation of fat in liver tissue (non-alcoholic fatty liver, NAFL) that can progress to non-alcoholic steatohepatitis (NASH), characterized by the presence of liver inflammation and damage. The latter form often coexists with liver fibrosis which, in turn, may progress to a state of cirrhosis and, potentially, hepatocarcinoma, both irreversible processes that often lead to the patient's death and/or the need for liver transplantation. Along with the high associated economic burden, the high mortality rate among NAFLD patients raises interest, not only in the search for novel therapeutic approaches, but also in early diagnosis and prevention to reduce the incidence of NAFLD-related complications. In this line, an exhaustive characterization of the immune status of patients with NAFLD is mandatory. Herein, we attempted to gather and compare the current and relevant scientific evidence on this matter, mainly on human reports. We addressed the current knowledge related to circulating cellular and soluble mediators, particularly platelets, different leukocyte subsets and relevant inflammatory soluble mediators.

Immune-metabolic interactions in homeostasis and the progression to NASH

The incidence of non-alcoholic fatty liver disease (NAFLD) has increased significantly over the past two decades. NAFLD ranges from simple steatosis (NAFL) to nonalcoholic steatohepatitis (NASH) and predisposes to fibrosis and hepatocellular carcinoma (HCC). The importance of the immune system in hepatic physiology and in the progression of NAFLD is increasingly recognized. At homeostasis, the liver participates in immune defense against pathogens and in tolerance of gut-derived microbial compounds. Hepatic immune cells also respond to metabolic stimuli and have a role in NAFLD progression to NASH. In this review, we discuss how metabolic perturbations affect immune cell phenotype and function in NAFL and NASH, and then focus on the role of immune cells in liver homeostasis and in the development of NASH.

The role of complement in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become a leading cause of chronic liver diseases globally. NAFLD includes a range of hepatic manifestations, starting with liver steatosis and potentially evolving towards nonalcoholic steatohepatitis, cirrhosis or even hepatocellular carcinoma. Although the pathogenesis of NAFLD is incompletely understood, insulin resistance and lipid metabolism disorder are implicated. The complement system is an essential part of the immune system, but it is also involved in lipid metabolism. In particular, activation of the alternative complement pathway and the production of complement activation products such as C3a, C3adesArg (acylation stimulating protein or ASP) and C5a, are strongly associated with insulin resistance, lipid metabolism disorder, and hepatic inflammation. In this review, we briefly summarize research on the role of the complement system in NAFLD, aiming to provide a basis for the development of novel therapeutic strategies for NAFLD.

Immune-related pathogenesis and therapeutic strategies of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and has become prevalent in the adult population worldwide, given the ongoing obesity pandemic. NAFLD comprises several hepatic disorders, ranging from fatty liver to nonalcoholic steatohepatitis (NASH), cirrhosis, and carcinoma. Excessive fat accumulation in the liver can induce the development of fatty liver, whereas the progression of fatty liver to NASH involves various complex factors. The crucial difference between fatty liver and NASH is the presence of inflammation and fibrosis, the emergence of which is closely associated with the action of immune cells and immunological factors, such as chemokines and cytokines. Thus, expanding our understanding of immunological mechanisms contributing to NASH pathogenesis will lead to the identification of therapeutic targets and the development of viable therapeutics against NASH.

Anti-CD47 antibody treatment attenuates liver inflammation and fibrosis in experimental non-alcoholic steatohepatitis models

BACKGROUND & AIMS

With the epidemic burden of obesity and metabolic diseases, nonalcoholic fatty liver disease (NAFLD) including steatohepatitis (NASH) has become the most common chronic liver disease in the western world. NASH may progress to cirrhosis and hepatocellular carcinoma. Currently, no treatment is available for NASH. Therefore, finding a therapy for NAFLD/NASH is in urgent need. Previously we have demonstrated that mice lacking CD47 or its ligand thrombospondin1 (TSP1) are protected from obesity-associated NALFD. This suggests that CD47 blockade might be a novel treatment for obesity-associated metabolic disease. Thus, in this study, the therapeutic potential of an anti-CD47 antibody in NAFLD progression was determined.

METHODS

Both diet-induced NASH mouse model and human NASH organoid model were utilized in this study. NASH was induced in mice by feeding with diet enriched with fat, fructose and cholesterol (AMLN diet) for 20 weeks and then treated with anti-CD47 antibody or control IgG for 4 weeks. Body weight, body composition and liver phenotype were analysed.

RESULTS

We found that anti-CD47 antibody treatment did not affect mice body weight, fat mass or liver steatosis. However, liver immune cell infiltration, inflammation and fibrosis were significantly reduced by anti-CD47 antibody treatment. In vitro data further showed that CD47 blockade prevented hepatic stellate cell activation and NASH progression in a human NASH organoid model.

CONCLUSION

Collectively, these data suggest that anti-CD47 antibody might be a new therapeutic option for obesity-associated NASH and liver fibrosis.

Neutrophils in chronic inflammatory diseases

Chronic inflammation is a component of many disease conditions that affect a large group of individuals worldwide. Chronic inflammation is characterized by persistent, low-grade inflammation and is increased in the aging population. Neutrophils are normally the first responders to acute inflammation and contribute to the resolution of inflammation. However, in chronic inflammation, the role of neutrophils is less well understood and has been described as either beneficial or detrimental, causing tissue damage and enhancing the immune response. Emerging evidence suggests that neutrophils are important players in several chronic diseases, such as atherosclerosis, diabetes mellitus, nonalcoholic fatty liver disease and autoimmune disorders. This review will highlight the interaction of neutrophils with other cells in the context of chronic inflammation, the contribution of neutrophils to selected chronic inflammatory diseases, and possible future therapeutic strategies.

Crucial role of T cells in NAFLD-related disease: A review and prospect

Nonalcoholic fatty liver disease (NAFLD) includes a series of hepatic manifestations, starting with liver steatosis and potentially evolving towards nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis or even hepatocellular carcinoma (HCC). Its incidence is increasing worldwide. Several factors including metabolic dysfunction, oxidative stress, lipotoxicity contribute to the liver inflammation. Several immune cell-mediated inflammatory processes are involved in NAFLD in which T cells play a crucial part in the progression of the disease. In this review, we focus on the role of different subsets of both conventional and unconventional T cells in pathogenesis of NAFLD. Factors regarding inflammation and potential therapeutic approaches targeting immune cells in NASH are also discussed.

Pathophysiological Mechanisms in Non-Alcoholic Fatty Liver Disease: From Drivers to Targets

Non-alcoholic fatty liver disease (NAFLD) is characterized by the excessive and detrimental accumulation of liver fat as a result of high-caloric intake and/or cellular and molecular abnormalities. The prevalence of this pathological event is increasing worldwide, and is intimately associated with obesity and type 2 diabetes mellitus, among other comorbidities. To date, only therapeutic strategies based on lifestyle changes have exhibited a beneficial impact on patients with NAFLD, but unfortunately this approach is often difficult to implement, and shows poor long-term adherence. For this reason, great efforts are being made to elucidate and integrate the underlying pathological molecular mechanism, and to identify novel and promising druggable targets for therapy. In this regard, a large number of clinical trials testing different potential compounds have been performed, albeit with no conclusive results yet. Importantly, many other clinical trials are currently underway with results expected in the near future. Here, we summarize the key aspects of NAFLD pathogenesis and therapeutic targets in this frequent disorder, highlighting the most recent advances in the field and future research directions.

Peripheral immune cells in NAFLD patients: A spyhole to disease progression

Nonalcoholic fatty liver disease (NAFLD) is a worldwide leading cause of chronic liver disease, but we still lack ideal non-invasive tools for diagnosis and evaluation of nonalcoholic steatohepatitis (NASH) and related liver fibrosis in NAFLD population. Systemic immune dysregulations such as metabolic inflammation are believed to play central role in the development of NAFLD, signifying the hope of utilizing quantitative and phenotypic changes in peripheral immune cells among NAFLD patients as a diagnostic tool of NASH and fibrosis. In this review, we summarize the known changes in peripheral immune cells from NAFLD/NASH patients and their potential relationship with NAFLD and NASH progression. Potential challenges and possible solutions for further clinical translation are also discussed.

The Effect of Probiotics (MCP® BCMC® Strains) on Hepatic Steatosis, Small Intestinal Mucosal Immune Function, and Intestinal Barrier in Patients with Non-Alcoholic Fatty Liver Disease

Treatment for non-alcoholic fatty liver disease (NAFLD) currently consists of lifestyle modifications such as a low-fat diet, weight loss, and exercise. The gut microbiota forms part of the gut–liver axis and serves as a potential target for NAFLD treatment. We investigated the effect of probiotics on hepatic steatosis, fibrosis, and biochemical blood tests in patients with NAFLD. At the small intestinal mucosal level, we examined the effect of probiotics on the expression of CD4+ and CD8+ T lymphocytes, as well as the tight junction protein zona occluden-1 (ZO-1). This was a randomized, double-blind, placebo-controlled trial involving ultrasound-diagnosed NAFLD patients (n = 39) who were supplemented with either a probiotics sachet (MCP^® BCMC^® strains) or a placebo for a total of 6 months. Multi-strain probiotics (MCP^® BCMC^® strains) containing six different Lactobacillus and Bifidobacterium species at a concentration of 30 billion CFU were used. There were no significant changes at the end of the study in terms of hepatic steatosis (probiotics: −21.70 ± 42.6 dB/m, p = 0.052 vs. placebo: −10.72 ± 46.6 dB/m, p = 0.29) and fibrosis levels (probiotics: −0.25 ± 1.77 kPa, p = 0.55 vs. placebo: −0.62 ± 2.37 kPa, p = 0.23) as measured by transient elastography. Likewise, no significant changes were found for both groups for the following parameters: LiverFAST analysis (steatosis, fibrosis and inflammation scores), alanine aminotransferase, total cholesterol, triglycerides, and fasting glucose. In the immunohistochemistry (IHC) analysis, no significant expression changes were seen for CD4+ T lymphocytes in either group (probiotics: −0.33 ± 1.67, p = 0.35 vs. placebo: 0.35 ± 3.25, p = 0.63). However, significant reductions in the expression of CD8+ T lymphocytes (−7.0 ± 13.73, p = 0.04) and ZO-1 (Z-score = −2.86, p = 0.04) were found in the placebo group, but no significant changes in the probiotics group. In this pilot study, the use of probiotics did not result in any significant clinical improvement in NAFLD patients. However, at the microenvironment level (i.e., the small intestinal mucosa), probiotics seemed to be able to stabilize the mucosal immune function and to protect NAFLD patients against increased intestinal permeability. Therefore, probiotics might have a complementary role in treating NAFLD. Further studies with larger sample sizes, a longer duration, and different probiotic strains are needed to evaluate the real benefit of probiotics in NAFLD.

Donor-derived regulatory dendritic cell infusion results in host cell cross-dressing and T cell subset changes in prospective living donor liver transplant recipients

Regulatory dendritic cells (DCreg) promote transplant tolerance following their adoptive transfer in experimental animals. We investigated the feasibility, safety, fate, and impact on host T cells of donor monocyte-derived DCreg infused into prospective, living donor liver transplant patients, 7 days before transplantation. The DCreg expressed a tolerogenic gene transcriptional profile, high cell surface programed death ligand-1 (PD-L1):CD86 ratios, high IL-10/no IL-12 productivity and poor ability to stimulate allogeneic T cell proliferation. Target DCreg doses (range 2.5-10 × 10⁶ cells/kg) were achieved in all but 1 of 15 recipients, with no infusion reactions. Following DCreg infusion, transiently elevated levels of donor HLA and immunoregulatory PD-L1, CD39, and CD73 were detected in circulating small extracellular vesicles. At the same time, flow and advanced image stream analysis revealed intact DCreg and "cross-dressing" of host DCs in blood and lymph nodes. PD-L1 co-localization with donor HLA was observed at higher levels than with recipient HLA. Between DCreg infusion and transplantation, T-bet^hi Eomes^hi memory CD8⁺ T cells decreased, whereas regulatory (CD25^hi CD127^- Foxp3⁺ ): T-bet^hi Eomes^hi CD8⁺ T cell ratios increased. Thus, donor-derived DCreg infusion may induce systemic changes in host antigen-presenting cells and T cells potentially conducive to modulated anti-donor immune reactivity at the time of transplant.

Neutrophil: An emerging player in the occurrence and progression of metabolic associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) is a common type of chronic liver disease characterized by excessive lipid accumulation in hepatocytes, but the pathogenesis is still unclear. Neutrophils, the most abundant immune cells in the human body, defend against pathogens and regulate the inflammatory response. Recent studies have indicated that excessive liver infiltration of neutrophils is a significant histological hallmark of MAFLD, and neutrophils and their derived granule proteins participate in different stages of MAFLD, including hepatic steatosis, inflammation, fibrosis, cirrhosis and hepatocellular carcinoma. Hence, in this review, we summarize the role of neutrophils in the occurrence and progression of MAFLD and provide a perspective for the clinical application of neutrophils in MAFLD diagnosis and treatment.