IL-17 signaling accelerates the progression of nonalcoholic fatty liver disease in mice

Innate-like T cells in liver disease

Mammalian innate-like T cells (ILTCs), including mucosal-associated invariant T (MAIT), natural killer T (NKT), and γδ T cells, are abundant tissue-resident lymphocytes that have recently emerged as orchestrators of hepatic inflammation, tissue repair, and immune homeostasis. This review explores the involvement of different ILTC subsets in liver diseases. We explore the mechanisms underlying the pro- and anti-inflammatory effector functions of ILTCs in a context-dependent manner. We highlight latest findings regarding the dynamic interplay between ILTC functional subsets and other immune and parenchymal cells which may inform candidate immunomodulatory strategies to achieve improved clinical outcomes in liver diseases. We present new insights into how distinct gene expression programs in hepatic ILTCs are induced, maintained, and reprogrammed in a context- and disease stage-dependent manner.

Immunobiotic Bacteria Attenuate Hepatic Fibrosis through the Modulation of Gut Microbiota and the Activation of Aryl-Hydrocarbon Receptors Pathway in Non-Alcoholic Steatohepatitis Mice

SCOPE

Nonalcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease worldwide that can progress to liver fibrosis (LF). Probiotics have beneficial roles in reducing intestinal inflammation and gut-associated diseases, but their effects and mechanisms beyond the gut in attenuating the progression of LF are remained unclear.

METHODS AND RESULTS

In a mouse model of NASH/LF induced by a methionine-choline deficient (MCD) diet, immunobiotics are administered to investigate their therapeutic effects. Results show that the MCD diet leads to liver inflammation, steatosis, and fibrosis, which are alleviated by immunobiotics. Immunobiotics reduces serum endotoxin and inflammatory markers while increasing regulatory cytokines and liver weight. They also suppress Th17 cells, known for producing inflammatory cytokines. Furthermore, immunobiotics mitigate collagen deposition and fibrogenic signaling in the liver, while restoring gut-barrier integrity and microbiota composition. Additionally, immunobiotics enhance the activation of the aryl hydrocarbon receptor (AhR) pathway in both colonic and liver tissues.

CONCLUSIONS

Overall, these results demonstrate a novel insight into the mechanisms through which immunobiotic administration improves the gut health which in turn increases the AhR pathway and inhibits HSCs activation and fibrosis progression beyond the gut in the liver tissue of NASH/LF mice.

The Role of CD4+T Cells in Nonalcoholic Steatohepatitis and Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) has become the fourth leading cause of cancer-related deaths worldwide; annually, approximately 830,000 deaths related to liver cancer are diagnosed globally. Since early-stage HCC is clinically asymptomatic, traditional treatment modalities, including surgical ablation, are usually not applicable or result in recurrence. Immunotherapy, particularly immune checkpoint blockade (ICB), provides new hope for cancer therapy; however, immune evasion mechanisms counteract its efficiency. In addition to viral exposure and alcohol addiction, nonalcoholic steatohepatitis (NASH) has become a major cause of HCC. Owing to NASH-related aberrant T cell activation causing tissue damage that leads to impaired immune surveillance, NASH-associated HCC patients respond much less efficiently to ICB treatment than do patients with other etiologies. In addition, abnormal inflammation contributes to NASH progression and NASH-HCC transition, as well as to HCC immune evasion. Therefore, uncovering the detailed mechanism governing how NASH-associated immune cells contribute to NASH progression would benefit HCC prevention and improve HCC immunotherapy efficiency. In the following review, we focused our attention on summarizing the current knowledge of the role of CD4+T cells in NASH and HCC progression, and discuss potential therapeutic strategies involving the targeting of CD4+T cells for the treatment of NASH and HCC.

Dual blockade of interleukin-17A and interleukin-17F as a therapeutic strategy for liver fibrosis: Investigating the potential effect and mechanism of brodalumab

Liver fibrosis is a terminal manifestation of various chronic liver diseases. There are no drugs that can reverse the condition. Recently, the importance of interleukin-17 (IL17) in the pathophysiology has been revealed and has attracted attention as a therapeutic target. We aimed to reveal the roles of IL17A and IL17F in liver fibrosis, and to validate the potential of their dual blockade as therapeutic strategy. First, we retrospectively reviewed the longitudinal change of FIB-4 index, a clinical indicator of liver fibrosis, among psoriasis patients treated by brodalumab, which blocks IL17 receptor A (IL17RA). Next, we examined anti-fibrotic efficacy of anti-IL17RA antibody (Ab) in two murine liver fibrosis models by histopathological investigation and real-time reverse transcription polymerase chain reaction (RT-PCR). Finally, we analyzed the effect of IL17A and IL17F upon human hepatic stellate cells with RNA sequencing, real-time RT-PCR, western blotting, chromatin immunoprecipitation, and flow cytometry. Clinical data showed that FIB-4 index significantly decreased among psoriasis patients treated by brodalumab. In vivo studies additionally demonstrated that anti-IL17RA Ab ameliorates liver fibrosis induced by tetrachloride and methionine-choline deficient diet. Furthermore, in vitro experiments revealed that both IL17A and IL17F enhance cell-surface expression of transforming growth factor-β receptor II and promote pro-fibrotic gene expression via the JUN pathway in human hepatic stellate cells. Our insights suggest that IL17A and IL17F share their pro-fibrotic function in the context of liver fibrosis, and moreover, dual blockade of IL17A and IL17F by anti-IL17RA Ab would be a promising strategy for the management of liver fibrosis.

Gut mycobiome in metabolic diseases: Mechanisms and clinical implication

Obesity, type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD) are three common metabolic diseases with high prevalence worldwide. Emerging evidence suggests that gut dysbiosis may influence the development of metabolic diseases, in which gut fungal microbiome (mycobiome) is actively involved. In this review, we summarize the studies exploring the composition changes of gut mycobiome in metabolic diseases and mechanisms by which fungi affect the development of metabolic diseases. The current mycobiome-based therapies, including probiotic fungi, fungal products, anti-fungal agents and fecal microbiota transplantation (FMT), and their implication in treating metabolic diseases are discussed. We highlight the unique role of gut mycobiome in metabolic diseases, providing perspectives for future research on gut mycobiome in metabolic diseases.

Interleukin-23 inhibitors decrease Fibrosis-4 index in psoriasis patients with elevated Fibrosis-4 index but not inteleukin-17 inhibitors

Recent studies indicate that hepatic diseases are associated with psoriasis. Non-invasive tests, including the Fibrosis-4 (FIB-4) index, which can confidently rule out the presence of advanced fibrosis, are currently receiving attention. However, data on the FIB-4 index in psoriasis patients and the effects of biologics on the FIB-4 index are limited. We investigated the relationships between the FIB-4 index and demographic or clinical characteristics as well as the effects of biologics on the FIB-4 index in psoriasis patients. Psoriasis patients aged 36-64 years, whose treatment was initiated with interleukin (IL)-17 inhibitors or IL-23 inhibitors for psoriasis from May 2015 to December 2022, were consecutively included. Data were collected retrospectively from the patients' charts. A total of 171 psoriasis patients were included in this study. Thirty-four, 43, 21, 32, and 41 psoriasis patients were treated with secukinumab, ixekizumab, brodalumab, guselkumab, or risankizumab, respectively. In biologics-naïve patients, a significant but weak positive correlation was observed between the FIB-4 index and age (r = 0.3246, p = 0.0018). There was no significant correlation between the FIB-4 index and other demographic or clinical characteristics. Regarding the effects of biologics on the FIB-4 index, no significant change was observed in psoriasis patients treated with any biologics. However, in psoriasis patients with a baseline FIB-4 index of >1.3, patients treated with guselkumab and those treated with either IL-23 inhibitor showed significantly decreased FIB-4 index scores 6 months after initiating the biologics (p = 0.0323, p = 0.0212). In contrast, no change was observed in FIB-4 index scores in patients treated with IL-17 inhibitors. In conclusion, our study revealed that the FIB-4 index was correlated with age in psoriasis patients. Furthermore, IL-23 inhibitors (but not IL-17 inhibitors) decreased the FIB-4 index score at 6 months in psoriasis patients with elevated FIB-4 index scores at baseline. Further studies are needed to clarify whether IL-23 inhibitors improve liver fibrosis physiologically and functionally.

Identification of disease-specific genes related to immune infiltration in nonalcoholic steatohepatitis using machine learning algorithms

To identify disease signature genes associated with immune infiltration in nonalcoholic steatohepatitis (NASH), we downloaded 2 publicly available gene expression profiles, GSE164760 and GSE37031, from the gene expression omnibus database. These profiles represent human NASH and control samples and were used for differential genes (DEGs) expression screening. Two machine learning methods, the Least Absolute Shrinkage and Selection Operator regression model and Support Vector Machine Recursive Feature Elimination, were used to identify candidate disease signature genes. The CIBERSORT deconvolution algorithm was employed to analyze the infiltration of 22 immune cell types in NASH. Additionally, we constructed a NASH cell model using HepG2 cells treated with oleic acid and free fatty acids. The construction of the cell model was verified using oil red O staining, and Western blotting was used to detect the protein expression of the disease signature genes in both control and model groups. As a result, a total of 262 DEGs were identified. These DEGs were primarily associated with metal ion transmembrane transporter activity, sodium ion transmembrane transporter protein activity, calcium ion, and neuroactive ligand-receptor interactions. FOS, IGFBP2, dual-specificity phosphatase 1 (DUSP1), and IKZF3 were identified as disease signature genes of NASH by the least absolute shrinkage and selection operator and Support Vector Machine Recursive Feature Elimination algorithms for DEGs analysis. The receiver operating characteristic curves showed that FOS, IGFBP2, DUSP1, and IKZF3 had good diagnostic value (area under receiver operating characteristic curve > 0.8). These findings were validated in the GSE89632 dataset and through cellular assays. Immunocyte infiltration analysis revealed that NASH was associated with CD8 T cells, CD4 T cells, follicular helper T cells, resting NK cells, eosinophils, regulatory T cells, and γδ T cells. The FOS, IGFBP2, DUSP1, and IKZF3 genes were specifically associated with follicular helper T cells. Lipid droplet aggregation significantly increased in HepG2 cells treated with oleic acid and free fatty acids, indicating successful construction of the cell model. In this model, the expression of FOS, IGFBP2, and DUSP1 was significantly decreased, while that of IKZF3 was significantly elevated (P < .01, P < .001) compared with the control group. Therefore, FOS, IGFBP2, DUSP1, and IKZF3 can be considered as disease signature genes associated with immune infiltration in NASH.

Liver fibrosis in NAFLD/NASH: from pathophysiology towards diagnostic and therapeutic strategies

Liver fibrosis, as an excess deposition of extracellular matrix (ECM) components, results from chronic liver injury as well as persistent activation of inflammatory response and of fibrogenesis. Liver fibrosis is a major determinant for chronic liver disease (CLD) progression and in the last two decades our understanding on the major molecular and cellular mechanisms underlying the fibrogenic progression of CLD has dramatically improved, boosting pre-clinical studies and clinical trials designed to find novel therapeutic approaches. From these studies several critical concepts have emerged, starting to reveal the complexity of the pro-fibrotic microenvironment which involves very complex, dynamic and interrelated interactions between different hepatic and extrahepatic cell populations. This review will offer first a recapitulation of established and novel pathophysiological basic principles and concepts by intentionally focus the attention on NAFLD/NASH, a metabolic-related form of CLD with a high impact on the general population and emerging as a leading cause of CLD worldwide. NAFLD/NASH-related pro-inflammatory and profibrogenic mechanisms will be analysed as well as novel information on cells, mediators and signalling pathways which have taken advantage from novel methodological approaches and techniques (single cell genomics, imaging mass cytometry, novel in vitro two- and three-dimensional models, etc.). We will next offer an overview on recent advancement in diagnostic and prognostic tools, including serum biomarkers and polygenic scores, to support the analysis of liver biopsies. Finally, this review will provide an analysis of current and emerging therapies for the treatment of NAFLD/NASH patients.

Therapeutic Effect and Mechanism Prediction of Fuzi-Gancao Herb Couple on Non-alcoholic Fatty Liver Disease (NAFLD) based on Network Pharmacology and Molecular Docking

BACKGROUND

Fuzi-Gancao herb couple is one of the most common herb couples involved in the TCM formula, which was used for the treatment of chronic diseases. The herb couple has a hepatoprotective effect. However, its main components and therapeutic mechanism are not yet clear. This study aims to elucidate the therapeutic effect and mechanism of the Fuzi-Gancao herb couple on NAFLD from animal experiments, network pharmacology, and molecular docking.

METHODS

60 Male C57BL/6 mice (20 g ± 2 g) were randomly divided into six groups including the blank group (n=10) and NALFD group (n=50). The mice of the NALFD group were fed with a high-fat diet for 20 weeks to establish the NAFLD model and the NALFD mice were randomly divided into five groups including positive group (berberine), model group and F-G groups with three dosages (0.257, 0.514, 0.771 g/kg) (n=10). After 10 weeks of administration, the serum was collected for the analysis of ALT, AST, LDL-c, HDL-c, and TC, and liver tissues were collected for pathological analysis. The TCMAS database was used to collect the main components and targets of the Fuzi-Gancao herb couple. The GeneCards database was used to collect NAFLD-related targets, and the key targets were obtained by intersecting with herbal targets. The diseasecomponent- target relationship diagram was constructed by Cytoscape 3.9.1. The obtained key targets were imported into the String database to obtain the PPI network, and imported into the DAVID database for KEGG pathway analysis and GO analysis. Finally, the key targets and key gene proteins were imported into Discovery Studio 2019 for molecular docking verification.

RESULTS

In this study, H-E staining indicated the pathological changes of liver tissue in Fuzi- Gancao groups were significantly improved, and the levels of AST, ALT, TC, HDL-c, and LDL-c in serum of Fuzi-Gancao groups decreased in a dose-dependent manner, compared with the model group. 103 active components and 299 targets in the Fuzi-Gancao herb couple were confirmed in the TCMSP database and 2062 disease targets in NAFLD were obtained. 142 key targets and 167 signal pathways were screened, such as the AGE-RAGE signaling pathway in diabetic complications, HIF-1 signaling pathway, IL-17 signaling pathway, TNF signaling pathway, and so on. The main bioactive ingredients of Fuzi-Gancao herb couple in the treatment of NAFLD are quercetin, kaempferol, naringenin, inermine, (R)-norcoclaurine, isorhamnetin, ignavine, 2,7-Dideacetyl-2,7- dibenzoyl-taxayunnanine F, glycyrol mainly involving IL6, AKT1, TNF, TP53, IL1B, VEGFA and other core targets. Molecular docking analysis indicated that there is a good affinity between the key components and the key targets.

CONCLUSION

This study preliminarily explained the main components and mechanism of the Fuzi- Gancao herb couple in the treatment of NAFLD and provided an idea for subsequent research.

The bidirectional immune crosstalk in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an unabated risk factor for end-stage liver diseases with no available therapies. Dysregulated immune responses are critical culprits of MASLD pathogenesis. Independent contributions from either the innate or adaptive arms of the immune system or their unidirectional interplay are commonly studied in MASLD. However, the bidirectional communication between innate and adaptive immune systems and its impact on MASLD remain insufficiently understood. Given that both innate and adaptive immune cells are indispensable for the development and progression of inflammation in MASLD, elucidating pathogenic contributions stemming from the bidirectional interplay between these two arms holds potential for development of novel therapeutics for MASLD. Here, we review the immune cell types and bidirectional pathways that influence the pathogenesis of MASLD and highlight potential pharmacologic approaches to combat MASLD based on current knowledge of this bidirectional crosstalk.

Immune Features of Disparate Liver Transplant Outcomes in Female Hispanics With Nonalcoholic Steatohepatitis

Background

Nonalcoholic steatohepatitis (NASH) is a severe immune-mediated stage of nonalcoholic fatty liver disease that is rapidly becoming the most common etiology requiring liver transplantation (LT), with Hispanics bearing a disproportionate burden. This study aimed to uncover the underlying immune mechanisms of the disparities experienced by Hispanic patients undergoing LT for NASH.

Methods

We enrolled 164 LT recipients in our institutional review board-approved study, 33 of whom presented with NASH as the primary etiology of LT (20%), with 16 self-reported as Hispanic (48%). We investigated the histopathology of prereperfusion and postreperfusion biopsies, clinical liver function tests, longitudinal soluble cytokines via 38-plex Luminex, and immune cell phenotypes generated by prereperfusion and postreperfusion blood using 14-color flow cytometry and enzyme-linked immunosorbent assay.

Results

Hispanic LT recipients transplanted for NASH were disproportionately female (81%) and disproportionately suffered poor outcomes in the first year posttransplant, including rejection (26%) and death (38%). Clinically, we observed increased pro-inflammatory and apoptotic histopathological features in biopsies, increased AST/international normalized ratio early posttransplantation, and a higher incidence of presensitization to mismatched HLA antigens expressed by the donor allograft. Experimental investigations revealed that blood from female Hispanic NASH patients showed significantly increased levels of leukocyte-attracting chemokines, innate-to-adaptive switching cytokines and growth factors, HMGB1 release, and TLR4/TLR8/TLR9/NOD1 activation, and produced a pro-inflammatory, pro-apoptotic macrophage phenotype with reduced CD14/CD68/CD66a/TIM-3 and increased CD16/CD11b/HLA-DR/CD80.

Conclusions

A personalized approach to reducing immunological risk factors is urgently needed for this endotype in Hispanics with NASH requiring LT, particularly in females.

Gene Variants Implicated in Steatotic Liver Disease: Opportunities for Diagnostics and Therapeutics

Non-alcoholic fatty liver disease (NAFLD) describes a steatotic (or fatty) liver occurring as a consequence of a combination of metabolic, environmental, and genetic factors, in the absence of significant alcohol consumption and other liver diseases. NAFLD is a spectrum of conditions. Steatosis in the absence of inflammation is relatively benign, but the disease can progress into more severe forms like non-alcoholic steatohepatitis (NASH), liver cirrhosis, and hepatocellular carcinoma. NAFLD onset and progression are complex, as it is affected by many risk factors. The interaction between genetic predisposition and other factors partially explains the large variability of NAFLD phenotype and natural history. Numerous genes and variants have been identified through large-scale genome-wide association studies (GWAS) that are associated with NAFLD and one or more subtypes of the disease. Among them, the largest effect size and most consistent association have been patatin-like phospholipase domain-containing protein 3 (PNPLA3), transmembrane 6 superfamily member 2 (TM6SF2), and membrane-bound O-acyltransferase domain containing 7 (MBOAT7) genes. Extensive in vitro and in vivo studies have been conducted on these variants to validate these associations. The focus of this review is to highlight the genetics underpinning the molecular mechanisms driving the onset and progression of NAFLD and how they could potentially be used to improve genetic-based diagnostic testing of the disease and develop personalized, targeted therapeutics.

Exploring immune related gene signatures and mechanisms linking non alcoholic fatty liver disease to atrial fibrillation through transcriptome data analysis

Atrial fibrillation (AF) and related cardiovascular complications pose a heavy burden to patients and society. Mounting evidence suggests a close association between nonalcoholic fatty liver disease (NAFLD) and AF. NAFLD and AF transcriptomic datasets were obtained from GEO database and analyzed using several bioinformatics approaches. We established a NAFLD-AF associated gene diagnostic signature (NAGDS) using protein-protein interaction analysis and machine learning, which was further quantified through RT-qPCR. Potential miRNA targeting NAGDS were predicted. Gene modules highly correlated with NAFLD liver pathology or AF occurrence were identified by WGCNA. Enrichment analysis of the overlapped genes from key module revealed that T-cell activation plays essential roles in NAFLD and AF, which was further confirmed by immune infiltration. Furthermore, an integrated SVM-RFE and LASSO algorithm was used to identify CCL4, CD48, ITGB2, and RNASE6 as NAGDS, all of which were found to be upregulated in NAFLD and AF mouse tissues. Patients with higher NAGDS showed augmented T cell and macrophage immunity, more advanced liver pathological characteristics, and prolonged AF duration. Additionally, hsa-miR-26a-5p played a central role in the regulation of NAGDS. Our findings highlight the central role of T-cell immune response in linking NAFLD to AF, and established an accurate NAGDS diagnostic model, which could serve as potential targets for immunoregulatory therapy.

Microbiota and Nod-like receptors balance inflammation and metabolism during obesity and diabetes

Gut microbiota influence host immunity and metabolism during obesity. Bacterial sensors of the innate immune system relay signals from specific bacterial components (i.e., postbiotics) that can have opposing outcomes on host metabolic inflammation. NOD-like receptors (NLRs) such as Nod1 and Nod2 both recruit receptor-interacting protein kinase 2 (RIPK2) but have opposite effects on blood glucose control. Nod1 connects bacterial cell wall-derived signals to metabolic inflammation and insulin resistance, whereas Nod2 can promote immune tolerance, insulin sensitivity, and better blood glucose control during obesity. NLR family pyrin domain containing (NLRP) inflammasomes can also generate divergent metabolic outcomes. NLRP1 protects against obesity and metabolic inflammation potentially because of a bias toward IL-18 regulation, whereas NLRP3 appears to have a bias toward IL-1β-mediated metabolic inflammation and insulin resistance. Targeting specific postbiotics that improve immunometabolism is a key goal. The Nod2 ligand, muramyl dipeptide (MDP) is a short-acting insulin sensitizer during obesity or during inflammatory lipopolysaccharide (LPS) stress. LPS with underacylated lipid-A antagonizes TLR4 and counteracts the metabolic effects of inflammatory LPS. Providing underacylated LPS derived from Rhodobacter sphaeroides improved insulin sensitivity in obese mice. Therefore, certain types of LPS can generate metabolically beneficial metabolic endotoxemia. Engaging protective adaptive immunoglobulin immune responses can also improve blood glucose during obesity. A bacterial vaccine approach using an extract of the entire bacterial community in the upper gut promotes protective adaptive immune response and long-lasting improvements in blood glucose control. A key future goal is to identify and combine postbiotics that cooperate to improve blood glucose control.

NKG2D-mediated detection of metabolically stressed hepatocytes by innate-like T cells is essential for initiation of NASH and fibrosis

Metabolic-associated fatty liver disease (MAFLD) is a spectrum of clinical manifestations ranging from benign steatosis to cirrhosis. A key event in the pathophysiology of MAFLD is the development of nonalcoholic steatohepatitis (NASH), which can potentially lead to fibrosis and hepatocellular carcinoma, but the triggers of MAFLD-associated inflammation are not well understood. We have observed that lipid accumulation in hepatocytes induces expression of ligands specific to the activating immune receptor NKG2D. Tissue-resident innate-like T cells, most notably γδ T cells, are activated through NKG2D and secrete IL-17A. IL-17A licenses hepatocytes to produce chemokines that recruit proinflammatory cells into the liver, which causes NASH and fibrosis. NKG2D-deficient mice did not develop fibrosis in dietary models of NASH and had a decreased incidence of hepatic tumors. The frequency of IL-17A+ γδ T cells in the blood of patients with MAFLD correlated directly with liver pathology. Our findings identify a key molecular mechanism through which stressed hepatocytes trigger inflammation in the context of MAFLD.

Non-alcoholic fatty liver disease: Immunological mechanisms and current treatments

Non-alcoholic fatty liver disease (NAFLD) causes significant global disease burden and is a leading cause of mortality. NAFLD induces a myriad of aberrant changes in hepatocytes at both the cellular and molecular level. Although the disease spectrum of NAFLD is widely recognised, the precise triggers for disease progression are still to be fully elucidated. Furthermore, the propagation to cirrhosis is poorly understood. Whilst some progress in terms of treatment options have been explored, an incomplete understanding of the hepatic cellular and molecular alterations limits their clinical utility. We have therefore reviewed some of the key pathways responsible for the pathogenesis of NAFLD such as innate and adaptative immunity, lipotoxicity and fibrogenesis, and highlighted current trials and treatment options for NAFLD patients.

Regulation of systemic metabolism by tissue-resident immune cell circuits

Recent studies have demonstrated that tissue homeostasis and metabolic function are dependent on distinct tissue-resident immune cells that form functional cell circuits with structural cells. Within these cell circuits, immune cells integrate cues from dietary contents and commensal microbes in addition to endocrine and neuronal signals present in the tissue microenvironment to regulate structural cell metabolism. These tissue-resident immune circuits can become dysregulated during inflammation and dietary overnutrition, contributing to metabolic diseases. Here, we review the evidence describing key cellular networks within and between the liver, gastrointestinal tract, and adipose tissue that control systemic metabolism and how these cell circuits become dysregulated during certain metabolic diseases. We also identify open questions in the field that have the potential to enhance our understanding of metabolic health and disease.

The Influence of Sex Hormones in Liver Function and Disease

The liver performs a multitude of bodily functions, whilst retaining the ability to regenerate damaged tissue. In this review, we discuss sex steroid biology, regulation of mammalian liver physiology and the development of new model systems to improve our understanding of liver biology in health and disease. A major risk factor for the development of liver disease is hepatic fibrosis. Key drivers of this process are metabolic dysfunction and pathologic activation of the immune system. Although non-alcoholic fatty liver disease (NAFLD) is largely regarded as benign, it does progress to non-alcoholic steatohepatitis in a subset of patients, increasing their risk of developing cirrhosis and hepatocellular carcinoma. NAFLD susceptibility varies across the population, with obesity and insulin resistance playing a strong role in the disease development. Additionally, sex and age have been identified as important risk factors. In addition to the regulation of liver biochemistry, sex hormones also regulate the immune system, with sexual dimorphism described for both innate and adaptive immune responses. Therefore, sex differences in liver metabolism, immunity and their interplay are important factors to consider when designing, studying and developing therapeutic strategies to treat human liver disease. The purpose of this review is to provide the reader with a general overview of sex steroid biology and their regulation of mammalian liver physiology.

Mechanisms of liver fibrosis in metabolic syndrome

The understanding of the mechanisms of liver fibrosis has been dominated by models in which chronic hepatocellular injury is the initiating step as is seen with viral infections. The increased prevalence of the metabolic syndrome, and the increases in liver fibrosis due to metabolic syndrome driven non-alcoholic steatohepatitis (NASH), has made it a priority to understand how this type of liver fibrosis is similar to, and different from, pure hepatocellular injury driven liver fibrosis. Both types of liver fibrosis have the transformation of the hepatic stellate cell (HSC) into a myofibroblast as a key step. In metabolic syndrome, there is little evidence that metabolite changes such as high levels of glucose and free fatty acids are directly inducing HSC transdifferentiation, however, metabolite changes may lead to reductions in immunomodulatory and hepatoprotective molecules such as lipoxins, resolvins and Interleukin (IL)-22. Cells of the innate immune system are known to be important intermediaries between hepatocellular damage and HSC transdifferentiation, primarily by producing cytokines such as transforming growth factor-β (TGF-β) and platelet derived growth factor (PDGF). Resident and infiltrating macrophages are the dominant innate immune cells, but others (dendritic cells, neutrophils, natural killer T cells and mucosal-associated invariant T cells) also have important roles in inducing and resolving liver fibrosis. CD8+ and CD4+ T cells of the adaptive immune system have been identified to have greater profibrotic roles than previously realised by inducing hepatocyte death (auto-aggressive CD8+T) cells and cytokines producing (TH17 producing CD4+T) cells. Finally, the cellular networks present in NASH fibrosis are being identified and suggest that once fibrosis has developed cell-to-cell communication is dominated by myofibroblasts autocrine signalling followed by communication with cholangiocytes and endothelial cells, with myofibroblast-hepatocyte, and myofibroblast-macrophage signalling having minor roles. Such information is essential to the development of antifibrotic strategies for different stages of fibrosis.

Noninvasive biomarkers in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide among children and adolescents. It encompasses a spectrum of disease, from its mildest form of isolated steatosis, to nonalcoholic steatohepatitis (NASH) to liver fibrosis and cirrhosis, or end-stage liver disease. The early diagnosis of pediatric NAFLD is crucial in preventing disease progression and in improving outcomes. Currently, liver biopsy is the gold standard for diagnosing NAFLD. However, given its invasive nature, there has been significant interest in developing noninvasive methods that can be used as accurate alternatives. Here, we review noninvasive biomarkers in pediatric NAFLD, focusing primarily on the diagnostic accuracy of various biomarkers as measured by their area under the receiver operating characteristic, sensitivity, and specificity. We examine two major approaches to noninvasive biomarkers in children with NAFLD. First, the biological approach that quantifies serological biomarkers. This includes the study of individual circulating molecules as biomarkers as well as the use of composite algorithms derived from combinations of biomarkers. The second is a more physical approach that examines data measured through imaging techniques as noninvasive biomarkers for pediatric NAFLD. Each of these approaches was applied to children with NAFLD, NASH, and NAFLD with fibrosis. Finally, we suggest possible areas for future research based on current gaps in knowledge.

Immune cells and their derived microRNA-enriched extracellular vesicles in nonalcoholic fatty liver diseases: Novel therapeutic targets

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide. Despite extensive research and multiple clinical trials, there are still no FDA-approved therapies to treat the most severe forms of NAFLD. This is largely due to its complicated etiology and pathogenesis, which involves visceral obesity, insulin resistance, gut dysbiosis, etc. Although inflammation is generally believed to be one of the critical factors that drive the progression of simple steatosis to nonalcoholic steatohepatitis (NASH), the exact type of inflammation and how it contributes to NASH pathogenesis remain largely unknown. Liver inflammation is accompanied by the elevation of inflammatory mediators, including cytokines and chemokines and consequently intrahepatic infiltration of multiple types of immune cells. Recent studies revealed that extracellular vesicles (EVs) derived from inflammatory cells and hepatocytes play an important role in controlling liver inflammation during NASH. In this review, we highlight the roles of innate and adaptive immune cells and their microRNA-enriched EVs during NAFLD development and discuss potential drugs that target inflammatory pathways for the treatment of NAFLD.

Thermoneutral housing shapes hepatic inflammation and damage in mouse models of non-alcoholic fatty liver disease

Introduction

Inflammation is a common unifying factor in experimental models of non-alcoholic fatty liver disease (NAFLD) progression. Recent evidence suggests that housing temperature-driven alterations in hepatic inflammation correlate with exacerbated hepatic steatosis, development of hepatic fibrosis, and hepatocellular damage in a model of high fat diet-driven NAFLD. However, the congruency of these findings across other, frequently employed, experimental mouse models of NAFLD has not been studied.

Methods

Here, we examine the impact of housing temperature on steatosis, hepatocellular damage, hepatic inflammation, and fibrosis in NASH diet, methionine and choline deficient diet, and western diet + carbon tetrachloride experimental models of NAFLD in C57BL/6 mice.

Results

We show that differences relevant to NAFLD pathology uncovered by thermoneutral housing include: (i) augmented NASH diet-driven hepatic immune cell accrual, exacerbated serum alanine transaminase levels and increased liver tissue damage as determined by NAFLD activity score; (ii) augmented methionine choline deficient diet-driven hepatic immune cell accrual and increased liver tissue damage as indicated by amplified hepatocellular ballooning, lobular inflammation, fibrosis and overall NAFLD activity score; and (iii) dampened western diet + carbon tetrachloride driven hepatic immune cell accrual and serum alanine aminotransferase levels but similar NAFLD activity score.

Discussion

Collectively, our findings demonstrate that thermoneutral housing has broad but divergent effects on hepatic immune cell inflammation and hepatocellular damage across existing experimental NAFLD models in mice. These insights may serve as a foundation for future mechanistic interrogations focused on immune cell function in shaping NAFLD progression.

The Essential Role of IL-17 as the Pathogenetic Link between Psoriasis and Metabolic-Associated Fatty Liver Disease

Interleukin 17 (IL-17) is an effector cytokine that plays a key role in the pathogenesis of both psoriasis and metabolic-associated fatty liver disease (MAFLD), a condition that is more prevalent and severe in patients with psoriasis. In liver inflammation, IL-17 is mainly produced by CD4+ T (TH17) and CD8+ T cells (Tc17), although numerous other cells (macrophages, natural killer cells, neutrophils and Tγδ cells) also contribute to the production of IL-17. In hepatocytes, IL-17 mediates systemic inflammation and the recruitment of inflammatory cells to the liver, and it is also implicated in the development of fibrosis and insulin resistance. IL-17 levels have been correlated with progression from MAFLD to steatohepatitis, cirrhosis, and even hepatocellular carcinoma. Clinical trials have shown that inhibiting IL-17A in patients with psoriasis could potentially contribute to the improvement of metabolic and liver parameters. A better understanding of the key factors involved in the pathogenesis of these chronic inflammatory processes could potentially lead to more efficient treatment for both psoriasis and MAFLD, and help to develop holistic strategies to improve the management of these patients.

Histologic Severity of Nonalcoholic Fatty Liver Disease Associates with Reduced Bone Mineral Density in Children

BACKGROUND

Lower whole body bone mineral density (BMD) has been reported in children with nonalcoholic fatty liver disease (NAFLD), but potential mediators remain uncertain.

AIMS

To assess BMD at multiple skeletal sites in children with confirmed NAFLD and controls with obesity, adjusting for known determinants of BMD, and examine potential mediators.

METHODS

We assessed age-, sex-, and race-specific, and height-adjusted BMD z-scores of whole body, lumbar spine, hip, femoral neck and forearm by dual-energy-x-ray absorptiometry in 79 children, 8-19 years old: 46 with biopsy-confirmed NAFLD [29 steatohepatitis (NASH)/17 fatty liver (NAFL)] and 33 controls without liver disease. We compared BMD z-scores by multivariable regression, adjusting for known BMD determinants and potential mediators (inflammatory and insulin resistance measures).

RESULTS

Unadjusted mean BMD z-scores in NAFLD were similar to controls, but significantly lower in NASH vs. NAFL at all sites. After covariate adjustment, mean forearm BMD z-score was higher in NAFL (β 0.60 ± SE 0.30, p < 0.05) and lower in NASH (β - 0.49 ± SE 0.26, p = 0.06) vs. controls (p = 0.002 for group), with similar trends at whole body and total hip; hs-CRP negatively associated with whole body and forearm BMD z-scores (p < 0.05), while visceral fat area negatively associated with femoral neck (p < 0.05). Only three children had clinically low whole body BMD z-scores (< - 2), one per group (control, NAFL and NASH).

CONCLUSIONS

NASH, but not NAFL, may be associated with increased risk of reduced BMD in children. Systemic inflammation, independent of body composition and load bearing, may mediate reduction in BMD in NASH.

Characterization of gut dominant microbiota in obese patients with nonalcoholic fatty liver disease

In obese patients, non-alcoholic fatty liver (NAFLD) is common. However, whether there is a connection between the gut microbiota and the onset of NAFLD in obese people is yet unknown. Using quantitative real-time PCR, the microbiota of feces of the eligible 181 obese individuals was identified to compare the differences in gut microbiota between obesity with NAFLD and simple obesity. According to the findings, the gut dominant microbiota was similar between obesity with NAFLD and simple obesity. Nonetheless, compared to the simple obesity group, the quantity of Faecalibacterium prausnitzii colonies was much lower in the obesity with the NAFLD group. Bacteroides were present in greater than 65% of both groups. Bacteroides, Clostridium leptum, and Clostridium butyricum accounted for more than 80% of the cases in the obesity with NAFLD group, whereas Bacteroides, Clostridium butyricum, and F. prausnitzii accounted for more than 80% of the cases in the simple obesity group. We look for potential contributing variables to obesity-related NAFLD and potential prevention measures for obese people. Based on a multi-factor logistic regression analysis, lymphocytes may be a risk factor for obesity with NAFLD while F. prausnitzii may be a protective factor. Additionally, F. prausnitzii is positively impacted by Bacteroides, Clostridium leptum, Clostridium butyricum, and Eubacterium rectale, yet adversely impacted by Enterobacteriaceae. Notably, lymphocytes and F. prausnitzii may help determine whether obese patients would develop NAFLD.

Protective Effects of Lactobacillus gasseri against High-Cholesterol Diet-Induced Fatty Liver and Regulation of Host Gene Expression Profiles

Fatty liver is one of the most pervasive liver diseases worldwide. Probiotics play an important role in the progression of liver disease, but their effects on host regulation are poorly understood. This study investigated the protective effects of lactobacillus gasseri (L. gasseri) against high-cholesterol diet (HCD)-induced fatty liver injury using a zebrafish larvae model. Liver pathology, lipid accumulation, oxidative stress and hepatic inflammation were evaluated to demonstrate the changes in a spectrum of hepatic injury. Moreover, multiple indexes on host gene expression profiles were comprehensively characterized by RNA screening. The results showed that treatment with L. gasseri ameliorated HCD-induced morphological and histological alterations, lipid regulations, oxidative stress and macrophage aggregation in the liver of zebrafish larvae. Furthermore, the enrichment of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway revealed that the core pathways of L. gasseri regulation were interleukin-17 (IL-17) signaling, phosphoinositide 3-kinase (PI3K)-AKT signaling pathway, the regulation of lipolysis and adipocytes and fatty acid elongation and estrogen signaling. The genes at key junction nodes, hsp90aa1.1, kyat3, hsd17b7, irs2a, myl9b, ptgs2b, cdk21 and papss2a were significantly regulated by L. gasseri administration. To conclude, the current research extends our understanding of the protective effects of L. gasseri against fatty liver and provides potential therapeutic options for fatty liver treatment.

The identification of metabolites from gut microbiota in NAFLD via network pharmacology

The metabolites of gut microbiota show favorable therapeutic effects on nonalcoholic fatty liver disease (NAFLD), but the active metabolites and mechanisms against NAFLD have not been documented. The aim of the study was to investigate the active metabolites and mechanisms of gut microbiota against NAFLD by network pharmacology. We obtained a total of 208 metabolites from the gutMgene database and retrieved 1256 targets from similarity ensemble approach (SEA) and 947 targets from the SwissTargetPrediction (STP) database. In the SEA and STP databases, we identified 668 overlapping targets and obtained 237 targets for NAFLD. Thirty-eight targets were identified out of those 237 and 223 targets retrieved from the gutMgene database, and were considered the final NAFLD targets of metabolites from the microbiome. The results of molecular docking tests suggest that, of the 38 targets, mitogen-activated protein kinase 8-compound K and glycogen synthase kinase-3 beta-myricetin complexes might inhibit the Wnt signaling pathway. The microbiota-signaling pathways-targets-metabolites network analysis reveals that Firmicutes, Fusobacteria, the Toll-like receptor signaling pathway, mitogen-activated protein kinase 1, and phenylacetylglutamine are notable components of NAFLD and therefore to understanding its processes and possible therapeutic approaches. The key components and potential mechanisms of metabolites from gut microbiota against NAFLD were explored utilizing network pharmacology analyses. This study provides scientific evidence to support the therapeutic efficacy of metabolites for NAFLD and suggests holistic insights on which to base further research.

IL-17 and IL-17-producing cells in protection versus pathology

IL-17 cytokine family members have diverse biological functions, promoting protective immunity against many pathogens but also driving inflammatory pathology during infection and autoimmunity. IL-17A and IL-17F are produced by CD4⁺ and CD8⁺ T cells, γδ T cells, and various innate immune cell populations in response to IL-1β and IL-23, and they mediate protective immunity against fungi and bacteria by promoting neutrophil recruitment, antimicrobial peptide production and enhanced barrier function. IL-17-driven inflammation is normally controlled by regulatory T cells and the anti-inflammatory cytokines IL-10, TGFβ and IL-35. However, if dysregulated, IL-17 responses can promote immunopathology in the context of infection or autoimmunity. Moreover, IL-17 has been implicated in the pathogenesis of many other disorders with an inflammatory basis, including cardiovascular and neurological diseases. Consequently, the IL-17 pathway is now a key drug target in many autoimmune and chronic inflammatory disorders; therapeutic monoclonal antibodies targeting IL-17A, both IL-17A and IL-17F, the IL-17 receptor, or IL-23 are highly effective in some of these diseases. However, new approaches are needed to specifically regulate IL-17-mediated immunopathology in chronic inflammation and autoimmunity without compromising protective immunity to infection.

The Tumor Microenvironment of Hepatocellular Carcinoma: Untying an Intricate Immunological Network

HCC, the most prevalent form of primary liver cancer, is prototypically an inflammation-driven cancer developing after years of inflammatory insults. Consequently, the hepatic microenvironment is a site of complex immunological activities. Moreover, the tolerogenic nature of the liver can act as a barrier to anti-tumor immunity, fostering cancer progression and resistance to immunotherapies based on immune checkpoint inhibitors (ICB). In addition to being a site of primary carcinogenesis, many cancer types have high tropism for the liver, and patients diagnosed with liver metastasis have a dismal prognosis. Therefore, understanding the immunological networks characterizing the tumor microenvironment (TME) of HCC will deepen our understanding of liver immunity, and it will underpin the dominant mechanisms controlling both spontaneous and therapy-induced anti-tumor immune responses. Herein, we discuss the contributions of the cellular and molecular components of the liver immune contexture during HCC onset and progression by underscoring how the balance between antagonistic immune responses can recast the properties of the TME and the response to ICB.

Identification of polyunsaturated fatty acids related key modules and genes in metabolic dysfunction-associated fatty liver disease using WGCNA analysis

Polyunsaturated fatty acids (PUFAs) play important roles in the aetiology and pathogenesis of metabolic dysfunction-associated fatty liver disease (MAFLD). However, the underlying molecular mechanisms are not understood. We analysed a public GEO dataset, GSE89632, to identify differentially expressed genes (DEGs) in MAFLD. Weighted gene coexpression network analysis (WGCNA) was used to reveal the core gene regulation network and to explore the PUFA-related hub genes in MAFLD. We experimentally verified these genes by quantitative reverse transcription PCR in high-fat diet (HFD)-fed mice. A total of 286 common DEGs (89 upregulated; 197 downregulated), mostly related to inflammatory and immune responses, were identified. Six modules were constructed using WGCNA, and 2 modules showed significant correlations with PUFAs. After combining these 2 modules with DEGs, the top 10 hub genes were identified. We further established a MAFLD mouse model with liver steatosis, as proved by HE and Oil Red O staining. Of the hub genes, ADAM metallopeptidase with thrombospondin type 1 motif 1 (adamts1) (p = 0.005) and transforming growth factor β3 (tgfβ3) (p < 0.001) showed significantly lower mRNA expression in MAFLD in vivo. adamts1 and tgfβ3 bridged PUFAs and MAFLD, which might be potential causative genes and therapeutic targets of MAFLD.

Sex differences in the diathetic effects of shift work schedules on circulating cytokine levels and pathological outcomes of ischemic stroke during middle age

Shift work is associated with increased risk for vascular disease, including stroke- and cardiovascular-related mortality. However, evidence from these studies is inadequate to distinguish the effect of altered circadian rhythms in isolation from other risk factors for stroke associated with shift work (e.g., smoking, poor diet, lower socioeconomic status). Thus, the present study examined the diathetic effects of exposure to shifted LD cycles during early adulthood on circadian rhythmicity, inflammatory signaling and ischemic stroke pathology during middle age, when stroke risk is high and outcomes are more severe. Entrainment of circadian activity was stable in all animals maintained on a fixed light:dark 12:12 cycle but was severely disrupted during exposure to shifted LD cycles (12hr advance/5d). Following treatment, circadian entrainment in the shifted LD group was distinguished by increased daytime activity and decreased rhythm amplitude that persisted into middle-age. Circadian rhythm desynchronization in shifted LD males and females was accompanied by significant elevations in circulating levels of the inflammatory cytokine IL-17A and gut-derived inflammatory mediator lipopolysaccharide (LPS) during the post-treatment period. Middle-cerebral artery occlusion, 3 months after exposure to shifted LD cycles, resulted in greater post-stroke mortality in shifted LD females. In surviving subjects, sensorimotor performance, assessed 2- and 5-days post-stroke, was impaired in males of both treatment groups, whereas in females, recovery of function was observed in fixed but not shifted LD rats. Overall, these results indicate that early exposure to shifted LD cycles promotes an inflammatory phenotype that amplifies stroke impairments, specifically in females, later in life.

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Early exposure to shifted LD cycles alters circadian entrainment of the activity rhythm that persists into middle age.

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In conjunction with circadian dysregulation, shift work-like schedules promote the induction of key inflammatory mediators.

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In females, exposure to shift work-like schedules amplifies functional impairments caused by strokes arising later in life.

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Circadian dysregulation during shift work is a hysteretic risk factor in the overall severity of ischemic strokes.

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Shift work-related circadian dysregulation affects stroke outcomes independent of lifestyle vascular disease risk factors.

The intestinal microbiome associated with lipid metabolism and obesity in humans and animals

Intestinal microbiota is considered to play an integral role in maintaining health of host by modulating several physiological functions including nutrition, metabolism and immunity. Accumulated data from human and animal studies indicate that intestinal microbes can affect lipid metabolism in host through various direct and indirect biological mechanisms. These mechanisms include the production of various signalling molecules by the intestinal microbiome, which exert a strong effect on lipid metabolism, bile secretion in the liver, reverse transport of cholesterol and energy expenditure and insulin sensitivity in peripheral tissues. This review discusses the findings of recent studies suggesting an emerging role of intestinal microbiota and its metabolites in regulating lipid metabolism and the association of intestinal microbiota with obesity. Additionally, we discuss the controversies and challenges in this research area. However, intestinal micro-organisms are also affected by some external factors, which in turn influence the regulation of microbial lipid metabolism. Therefore, we also discuss the effects of probiotics, prebiotics, diet structure, exercise and other factors on intestinal microbiological changes and lipid metabolism regulation.

Immune mechanisms linking metabolic injury to inflammation and fibrosis in fatty liver disease - novel insights into cellular communication circuits

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease and is emerging as the leading cause of cirrhosis, liver transplantation and hepatocellular carcinoma (HCC). NAFLD is a metabolic disease that is considered the hepatic manifestation of the metabolic syndrome; however, during the evolution of NAFLD from steatosis to non-alcoholic steatohepatitis (NASH), to more advanced stages of NASH with liver fibrosis, the immune system plays an integral role. Triggers for inflammation are rooted in hepatic (lipid overload, lipotoxicity, oxidative stress) and extrahepatic (gut-liver axis, adipose tissue, skeletal muscle) systems, resulting in unique immune-mediated pathomechanisms in NAFLD. In recent years, the implementation of single-cell RNA-sequencing and high dimensional multi-omics (proteogenomics, lipidomics) and spatial transcriptomics have tremendously advanced our understanding of the complex heterogeneity of various liver immune cell subsets in health and disease. In NAFLD, several emerging inflammatory mechanisms have been uncovered, including profound macrophage heterogeneity, auto-aggressive T cells, the role of unconventional T cells and platelet-immune cell interactions, potentially yielding novel therapeutics. In this review, we will highlight the recent discoveries related to inflammation in NAFLD, discuss the role of immune cell subsets during the different stages of the disease (including disease regression) and integrate the multiple systems driving inflammation. We propose a refined concept by which the immune system contributes to all stages of NAFLD and discuss open scientific questions arising from this paradigm shift that need to be unravelled in the coming years. Finally, we discuss novel therapeutic approaches to target the multiple triggers of inflammation, including combination therapy via nuclear receptors (FXR agonists, PPAR agonists).

Interplay Between Liver Type 1 Innate Lymphoid Cells and NK Cells Drives the Development of Alcoholic Steatohepatitis

BACKGROUND & AIMS

Liver contains high frequency of group 1 innate lymphoid cells (ILC), which are composed of comparable number of type 1 ILC (ILC1) and natural killer (NK) cells in steady state. Little is known about whether and how the interaction between ILC1 and NK cells affects the development of alcoholic liver disease.

METHODS

A mouse model of chronic alcohol abuse plus single-binge (Gao-Binge model) was established. The levels of alanine aminotransferase/aspartate aminotransferase, hepatic lipid, and inflammatory cytokines or neutrophils were measured to evaluate the degree of liver injury, steatosis, and inflammation. Flow cytometric analysis, cell depletion, or adoptive transfer were used to interrogate the interaction between ILC1 and NK cells.

RESULTS

Upon chronic alcohol consumption, NK cells, but not ILC1, underwent apoptosis, resulting in ILC1 dominance among group 1 ILC. Interleukin (IL) 17A expression was up-regulated, and increased IL17A was mainly derived from liver ILC1 after chronic alcohol feeding. Either depletion of ILC1 or neutralization of IL17A could significantly attenuate liver steatosis, inflammation, and injury in alcohol-fed mice. In contrast, normalization of the ILC1/NK cells ratio through NK cells transfer or expanding NK cells had a significant hepatoprotection against alcohol-induced steatohepatitis. Furthermore, NK cell-derived interferon gamma exerted a protective function via inhibiting IL17A production by liver ILC1 during alcoholic steatohepatitis.

CONCLUSIONS

This is the first study showing that the interplay between liver ILC1 and NK cells occurs and drives the development of alcoholic steatohepatitis. Our findings support further exploration of liver ILC1 or NK cells as a therapeutic target for the treatment of alcohol-associated liver disease.

IL-23 signaling is not an important driver of liver inflammation and fibrosis in murine non-alcoholic steatohepatitis models

Non-alcoholic fatty liver disease (NAFLD), represents an unmet medical need that can progress to non-alcoholic steatohepatitis (NASH), which, without intervention, can result in the development of cirrhosis and hepatocellular carcinoma (HCC). Inflammation is a pathological hallmark of NASH, and targeting key inflammatory mediators of NASH may lead to potential therapeutics for the disease. Herein, we aimed to investigate the role of IL-23 signaling in NASH progression in murine models. We showed that recombinant IL-23 can promote IL-17 producing cell expansion in the liver and that these cells are predominately γδ T cells and Mucosal Associated Invariant T cells (MAITs). Reciprocally, we found that IL-23 signaling is necessary for the expansion of γδ T cells and MAIT cells in the western diet (WD) diet induced NASH model. However, we did not observe any significant differences in liver inflammation and fibrosis between wild type and Il23r-/- mice in the same NASH model. Furthermore, we found that Il23r deletion does not impact liver inflammation and fibrosis in the choline-deficient, L-amino acid-defined and high-fat diet (CDA-HFD) induced NASH model. Based on these findings, we therefore propose that IL-23 signaling is not necessary for NASH pathogenesis in preclinical models and targeting this pathway alone may not be an effective therapeutic approach to ameliorate the disease progression in NASH patients.

Tissue-resident memory T cells in chronic liver diseases: Phenotype, development and function

Tissue-resident memory (T_RM) T cells are a unique subset of memory T cells that are critical for the first line of defense against pathogens or antigens in peripheral non-lymphoid tissues such as liver, gut, and skin. Generally, T_RM cells are well adapted to the local environment in a tissue-specific manner and typically do not circulate but persist in tissues, distinguishing them from other memory T cell lineages. There is strong evidence that liver T_RM cells provide a robust adaptive immune response to potential threats. Indeed, the potent effector function of hepatic T_RM cells makes it essential for chronic liver diseases, including viral and parasite infection, autoimmune liver diseases (AILD), nonalcoholic fatty liver disease (NAFLD), hepatocellular carcinoma (HCC) and liver transplantation. Manipulation of hepatic T_RM cells might provide novel promising strategies for precision immunotherapy of chronic liver diseases. Here, we provide insights into the phenotype of hepatic T_RM cells through surface markers, transcriptional profiles and effector functions, discuss the development of hepatic T_RM cells in terms of cellular origin and factors affecting their development, analyze the role of hepatic T_RM cells in chronic liver diseases, as well as share our perspectives on the current status of hepatic T_RM cell research.

Nonalcoholic fatty liver disease and osteoporosis: A potential association with therapeutic implications

Nonalcoholic fatty liver disease (NAFLD) and osteoporosis are two highly prevalent metabolic diseases. Increasing experimental evidence supports a pathophysiological link between NAFLD and osteoporosis. A key feature could be chronic, low-grade inflammation, which characterizes NAFLD and possibly affects bone metabolism. In this context, several factors, including but not limited to receptor activator of nuclear factor kappa-B ligand, osteoprotegerin, osteopontin and osteocalcin, may serve as mediators. In the clinical setting, most but not all epidemiological evidence indicates that NAFLD is associated with lower bone mineral density or osteoporosis in adults. Although an association between NAFLD and osteoporosis has not yet been established, and thus remains speculative, pharmacological considerations already exist. Some of the current and emerging pharmacological options for NAFLD have shown possible anti-osteoporotic properties (eg, vitamin E, obeticholic acid, semaglutide), while others (eg, pioglitazone, canagliflozin) have been associated with increased risk of fractures and may be avoided in patients with NAFLD and concomitant osteoporosis, especially those at high fracture risk. Conversely, some anti-osteoporotic medications (denosumab) might benefit NAFLD, while others (raloxifene) might adversely affect it and, consequently, may be avoided in patients with osteoporosis and NAFLD. If an association between NAFLD and osteoporosis is established, a medication that could target both diseases would be a great advancement. This review summarizes the main experimental and clinical evidence on the potential association between NAFLD and osteoporosis and focuses on treatment considerations derived from this potential association.

Astaxanthin Alleviates Nonalcoholic Fatty Liver Disease by Regulating the Intestinal Flora and Targeting the AMPK/Nrf2 Signal Axis

Nonalcoholic fatty liver disease (NAFLD) is among the most prevalent chronic liver diseases around the globe. The accumulation of lipids in the liver and oxidative stress are important pathological mechanisms of NAFLD. Astaxanthin (AT) is a carotenoid extracted from shrimps and crabs with beneficial biological activities, including anti-oxidative and anti-inflammatory activities. 16S microflora sequencing, H&E staining, and the western blot technique were employed to investigate the impacts of AT on a high-fat diet (HFD)-induced NAFLD. Significant mitigation in lipid metabolism-related disorders and decreased oxidative stress in HFD-induced mice were observed due to AT, and significant changes in the gut flora of the model mice were also observed. The in vitro study showed that AT considerably lowered the protein expression level of fatty acid synthetase (FAS), sterol regulatory element-binding protein-1c (SREBP-1c), and acetyl-COA carboxylase (ACC) and increased the protein expression of nuclear factor-E2 associated factor 2 (Nrf2) and AMP-activated protein kinase (AMPK) in oleic acid (OA) and palmitic acid (PA)-induced HepG2 cells. Additionally, mechanistic studies revealed that compound C (AMPK inhibitor, CC) inhibited the regulatory effect of AT on the SREBP-1c and Nrf2 signaling pathways. In conclusion, AT can inhibit the SREBP-1c, FAS, and ACC signaling pathways, activate the AMPK and Nrf2 signaling pathways, and improve the structure of intestinal flora.

CD4+ T cell activation and inflammation in NASH-related fibrosis

Liver fibrosis is a common pathological feature of end stage liver failure, a severe life-threatening disease worldwide. Nonalcoholic fatty liver disease (NAFLD), especially its more severe form with steatohepatitis (NASH), results from obesity, type 2 diabetes and metabolic syndrome and becomes a leading cause of liver fibrosis. Genetic factor, lipid overload/toxicity, oxidative stress and inflammation have all been implicated in the development and progression of NASH. Both innate immune response and adaptive immunity contribute to NASH-associated inflammation. Innate immunity may cause inflammation and subsequently fibrosis via danger-associated molecular patterns. Increasing evidence indicates that T cell-mediated adaptive immunity also provokes inflammation and fibrosis in NASH via cytotoxicity, cytokines and other proinflammatory and profibrotic mediators. Recently, the single-cell transcriptome profiling has revealed that the populations of CD4+ T cells, CD8+ T cells, γδ T cells, and TEMs are expanded in the liver with NASH. The activation of T cells requires antigen presentation from professional antigen-presenting cells (APCs), including macrophages, dendritic cells, and B-cells. However, since hepatocytes express MHCII molecules and costimulators, they may also act as an atypical APC to promote T cell activation. Additionally, the phenotypic switch of hepatocytes to proinflammatory cells in NASH contributes to the development of inflammation. In this review, we focus on T cells and in particular CD4+ T cells and discuss the role of different subsets of CD4+ T cells including Th1, Th2, Th17, Th22, and Treg in NASH-related liver inflammation and fibrosis.

Immunomodulatory functions of FXR

The Farnesoid-x-receptor (FXR) is a bile acids sensor activated in humans by primary bile acids. FXR is mostly expressed in liver, intestine and adrenal glands but also by cells of innate immunity, including macrophages, liver resident macrophages, the Kupffer cells, natural killer cells and dendritic cells. In normal physiology and clinical disorders, cells of innate immunity mediate communications between liver, intestine and adipose tissues. In addition to FXR, the G protein coupled receptor (GPBAR1), that is mainly activated by secondary bile acids, whose expression largely overlaps FXR, modulates chemical communications from the intestinal microbiota and the host's immune system, integrating epithelial cells and immune cells in the entero-hepatic system, providing a mechanism for development of a tolerogenic state toward the intestinal microbiota. Disruption of FXR results in generalized inflammation and disrupted bile acids metabolism. While FXR agonism in preclinical models provides counter-regulatory signals that attenuate inflammation-driven immune dysfunction in a variety of liver and intestinal disease models, the clinical relevance of these mechanisms in the setting of FXR-related disorders remain poorly defined.

Transcriptomic profiling of a multiethnic pediatric NAFLD cohort reveals genes and pathways associated with disease

Nonalcoholic fatty liver disease (NAFLD) is the most common type of chronic liver disease in children. The mechanisms that drive NAFLD disease progression in this specific patient population remain poorly defined. In this study, we obtained liver biopsy samples from a multiethnic cohort of pediatric patients with NAFLD (n = 52, mean age = 13.6 years) and healthy liver controls (n = 5). We analyzed transcriptomic changes associated with NAFLD stages using high-throughput RNA sequencing. Unsupervised clustering as well as pairwise transcriptome comparison distinguished NAFLD from healthy livers. We identified perturbations in pathways including calcium and insulin/glucose signaling occurring early in NAFLD disease, before the presence of histopathologic evidence of advanced disease. Transcriptomic comparisons identified a 25-gene signature associated with the degree of liver fibrosis. We also identified expression of the insulin-like growth factor binding protein (IGFBP) gene family (1/2/3/7) as correlating with disease stages, and it has the potential to be used as a peripheral biomarker in NAFLD. Comparing our data set with publicly available adult and adolescent transcriptomic data, we identified similarities and differences in pathway enrichment and gene-expression profiles between adult and pediatric patients with NAFLD. Regulation of genes including interleukin-32, IGFBP1, IGFBP2, and IGFBP7 was consistently found in both NAFLD populations, whereas IGFBP3 was specific to pediatric NAFLD. Conclusion: This paper expands our knowledge on the molecular mechanisms underlying pediatric NAFLD. It identifies potential biomarkers and directs us toward new therapies in this population.

M2 macrophage-derived exosomal microRNA-411-5p impedes the activation of hepatic stellate cells by targeting CAMSAP1 in NASH model

Liver fibrosis is a severe stage of nonalcoholic fatty liver disease (NAFLD), which is closely associated with the activation of hepatic stellate cells (HSCs) and their interaction with macrophages. Exosomes can mediate crosstalk between macrophages and HSCs in NAFLD-associated fibrosis. We found that M2 macrophage-derived exosomes significantly inhibit HSCs activation. RNA-seq studies revealed that miRNA-411-5p was decreased in serum exosomes of nonalcoholic steatohepatitis (NASH) patients as compared with that in healthy controls. Besides, miR-411-5p and M2 macrophage markers are decreased in the liver of the NASH model. We further proved that exosomal miR-411-5p from M2 macrophages inhibit HSCs activation and miR-411-5p directly downregulated the expression of Calmodulin-Regulated Spectrin-Associated Protein 1 (CAMSAP1) to inactivate stellate cells. Importantly, knockdown of CAMSAP1 also inhibited HSCs activation. This study contributes to understanding the underlying mechanism of HSCs activation and indicates CAMSAP1 may serve as a potential therapeutic target for NASH.

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M2 macrophage markers are decreased in the HFHCD-induced rat model of NASH

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M2 macrophage-derived exosomes inhibit HSCs activation via miR-411-5p

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CAMSAP1 is a direct target of miR-411-5p

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Knockdown of CAMSAP1 inhibits HSCs activation

Inflammatory response of gut, spleen, and liver in mice induced by orally administered Porphyromonas gingivalis

Background

Periodontitis is a chronic multifactorial inflammatory disease. Porphyromonas gingivalis is a primary periopathogen in the initiation and development of periodontal disease. Evidence has shown that P. gingivalis is associated with systemic diseases, including IBD and fatty liver disease. Inflammatory response is a key feature of diseases related to this species.

Methods

C57BL/6 mice were administered either PBS, or P. gingivalis. After 9 weeks, the inflammatory response in gut, spleen, and liver was analyzed.

Results

The findings revealed significant disturbance of the intestinal microbiota and increased inflammatory factors in the gut of P. gingivalis-administered mice. Administrated P. gingivalis remarkably promoted the secretion of IRF-1 and activated the inflammatory pathway IFN-γ/STAT1 in the spleen. Histologically, mice treated with P. gingivalis exhibited hepatocyte damage and lipid deposition. The inflammatory factors IL-17a, IL-6, and ROR-γt were also upregulated in the liver of mice fed with P. gingivalis. Lee’s index, spleen index, and liver index were also increased.

Conclusion

These results suggest that administrated P. gingivalis evokes inflammation in gut, spleen, and liver, which might promote the progression of various systemic diseases.

Amelioratory Effect of Resistant Starch on Non-alcoholic Fatty Liver Disease via the Gut-Liver Axis

Non-alcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome with a global prevalence. Impaired gut barrier function caused by an unhealthy diet plays a key role in disrupting the immune-metabolic homeostasis of the gut-liver axis (GLA), leading to NAFLD. Therefore, dietary interventions have been studied as feasible alternative therapeutic approaches to ameliorate NAFLD. Resistant starches (RSs) are prebiotics that reduce systemic inflammation in patients with metabolic syndrome. The present review aimed to elucidate the mechanisms of the GLA in alleviating NAFLD and provide insights into how dietary RSs counteract diet-induced inflammation in the GLA. Emerging evidence suggests that RS intake alters gut microbiota structure, enhances mucosal immune tolerance, and promotes the production of microbial metabolites such as short-chain fatty acids (SCFAs) and secondary bile acids. These metabolites directly stimulate the growth of intestinal epithelial cells and elicit GPR41/GPR43, FXR, and TGR5 signaling cascades to sustain immune-metabolic homeostasis in the GLA. The literature also revealed the dietary-immune-metabolic interplay by which RSs exert their regulatory effect on the immune-metabolic crosstalk of the GLA and the related molecular basis, suggesting that dietary intervention with RSs may be a promising alternative therapeutic strategy against diet-induced dysfunction of the GLA and, ultimately, the risk of developing NAFLD.

Folic acid intervention changes liver Foxp3 methylation and ameliorates the damage caused by Th17/Treg imbalance after long-term alcohol exposure

Folic acid, as a key source of methyl donor in DNA methylation, has been proved to play a beneficial role in inflammation modulation, which is usually impaired in alcoholic liver disease (ALD). However, the role of folic acid in alcoholic liver inflammation and injury remain elusive. In this study, we sought to uncover the potential protective mechanism by which folic acid ameliorates alcoholic liver injury. 100 male C57BL/6J mice were randomly divided into 5 groups: normal saline group, folic acid control group (5 mg per kg BW), ethanol model group (56% v/v, 10 mL per kg BW), folic acid + ethanol group, and 5-Aza + ethanol group (0.1 mL per 20 g BW). Liquor (10 mL per kg BW) was orally administered 1 h after the folic acid treatment for 10 consecutive weeks. The results showed that folic acid-inhibited ethanol-induced serum TG, TC, and LDL elevation attenuated hepatic fat accumulation and maintained ALT at a normal level. 10 weeks of ethanol administration simultaneously upregulated the hepatic proportion of Th17 and Treg cells to different extents and broke the homeostasis of liver immunization. Folic acid limited ethanol-induced inflammatory injury by increasing the frequency of hepatic Treg cells. Importantly, this effect may be caused by decreased DNMT3a, which in turn downregulates the methylated levels of CPG2 and CPG3 in the Foxp3 promoter region, changing the abundance of Foxp3 expression and improving the Th17/Treg imbalance. In summary, our findings demonstrated that folic acid supplementation may relieve ethanol-induced Th17/Treg disbalance through altering Foxp3 promoter methylation patterns, suggesting that folic acid may be a feasible preventive strategy for ALD.

Mechanisms by Which Skeletal Muscle Myokines Ameliorate Insulin Resistance

The skeletal muscle is the largest organ in the body and secretes circulating factors, including myokines, which are involved in various cellular signaling processes. Skeletal muscle is vital for metabolism and physiology and plays a crucial role in insulin-mediated glucose disposal. Myokines have autocrine, paracrine, and endocrine functions, serving as critical regulators of myogenic differentiation, fiber-type switching, and maintaining muscle mass. Myokines have profound effects on energy metabolism and inflammation, contributing to the pathophysiology of type 2 diabetes (T2D) and other metabolic diseases. Myokines have been shown to increase insulin sensitivity, thereby improving glucose disposal and regulating glucose and lipid metabolism. Many myokines have now been identified, and research on myokine signaling mechanisms and functions is rapidly emerging. This review summarizes the current state of the field regarding the role of myokines in tissue cross-talk, including their molecular mechanisms, and their potential as therapeutic targets for T2D.

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.

Interleukin-17 Weakens the NAFLD/NASH Process by Facilitating Intestinal Barrier Restoration Depending on the Gut Microbiota

Interleukin-17 (IL-17) is associated with nonalcoholic fatty liver disease (NAFLD) and gut microbiota, and how IL-17 mediates the NAFLD/nonalcoholic steatohepatitis (NASH) process depending on the gut microbiota is unclear. We found that T helper 17 (T_H17) cells were decreased in the small intestine in a methionine choline-deficient (MCD) diet-induced NASH model. IL-17-deficient (Il17^−/−) mice showed alterations in intestinal microbiota, including the inhibition of probiotic growth and the overgrowth of certain pathogenic bacteria, and were prone to higher endotoxemia levels and more severe gastrointestinal barrier defects than wild-type (WT) mice. Furthermore, T_H17 cells were responsible for restoring the intestinal barrier after administration of recombinant IL-17 to Il17^−/− mice or injection of CD4⁺ T cells into a Rag1^−/− mouse model. Additionally, transplantation of the microbiota from WT mice to Il17^−/− mice restored the intestinal barrier. Notably, microbiota-depleted Il17^−/− mice were resistant to MCD diet-induced intestinal barrier impairment. Fecal microbiota transplantation from Il17^−/− mice to microbiota-depleted mice aggravated intestinal barrier impairment and then promoted the development of NASH. Collectively, this study showed that host IL-17 could strengthen intestinal mucosal barrier integrity and reduce dysbiosis-induced intestinal injury and secondary extraintestinal organ injury induced by a special diet.

IL-17A, IL-17E and IL-17F as Potential Biomarkers for the Intensity of Low-Grade Inflammation and the Risk of Cardiovascular Diseases in Obese People

Low-grade inflammation is a factor that predisposes to many obesity-related comorbidities. The immune mechanisms controlling the inflammatory response related to the secretory activity of adipocytes and its consequences for the organism are still under investigation.

METHODS

84 obese adult volunteers (BMI ≥ 30 kg/m²) were tested by BIA. Serum samples were collected to analyze the concentrations of interleukins IL-17A, IL-17E and IL-17F. The subjects completed the original questionnaire, the FFQ-6 food consumption frequency questionnaire and the food diary.

RESULTS

The level of IL-17E and IL-17F was positively correlated with the BMI value and the level of IL-17E increased with the content of subcutaneous fat. Its increased blood concentration was also observed in individuals who declared that they were diagnosed with atherosclerosis and/or were taking beta-blockers. Products that were related with a low level of the above-mentioned interleukins were vegetables, groats, eggs, red meat, fast-food and alcohol. The level of these interleukins was positively correlated with the frequent consumption of confectionery and breakfast cereals. Nutrients that decreased the concentrations of IL-17 isoforms were potassium, iron, vitamins B6 and C, and folic acid.

CONCLUSIONS

Both IL-17E and IL-17F may be closely related to the intensity of low-grade inflammation and be biomarkers of cardiovascular disease risk. Food products or the nutrients they contain may affect the levels of the above-mentioned interleukins as well as IL-17A.

Action Mechanism Underlying Improvement Effect of Fuzi Lizhong Decoction on Nonalcoholic Fatty Liver Disease: A Study Based on Network Pharmacology and Molecular Docking

OBJECTIVE

This study aimed to decipher the bioactive compounds and potential mechanism of traditional Chinese medicine (TCM) formula Fuzi Lizhong Decoction (FLD) for nonalcoholic fatty liver disease (NAFLD) treatment via an integrative network pharmacology approach.

METHODS

The candidate compounds of FLD and its relative targets were obtained from the TCMSP and PharmMapper web server, and the intersection genes for NAFLD were discerned using OMIM, GeneCards, and DisGeNET. Then, the PPI and component-target-pathway networks were constructed. Moreover, GO enrichment and KEGG pathway analysis were performed to investigate the potential signaling pathways associated with FLD's effect on NAFLD. Eventually, molecular docking simulation was carried out to validate the binding affinity between potential core components and key targets.

RESULTS

A total of 143 candidate active compounds and 129 relative drug targets were obtained, in which 61 targets were overlapped with NAFLD. The PPI network analysis identified ALB, MAPK1, CASP3, MARK8, and AR as key targets, mainly focusing on cellular response to organic cyclic compound, steroid metabolic process, and response to steroid hormone in the biological processes. The KEGG pathway analysis demonstrated that 16 signaling pathways were closely correlated with FLD's effect on NALFD with cancer pathways, Th17 cell differentiation, and IL-17 signaling pathways as the most significant ones. In addition, the molecular docking analysis revealed that the core active compounds of FLD, such as 3'-methoxyglabridin, chrysanthemaxanthin, and Gancaonin H, had a high binding activity with such key targets as ALB, MAPK1, and CASP3.

CONCLUSIONS

This study suggested that FLD exerted its effect on NAFLD via modulating multitargets with multicompounds through multipathways. It also demonstrated that the network pharmacology-based approach might provide insights for understanding the interrelationship between complex diseases and interventions of the TCM formula.