Interleukin-17 exacerbates hepatic steatosis and inflammation in non-alcoholic fatty liver disease

Immune system dysregulation in the pathogenesis of non-alcoholic steatohepatitis: unveiling the critical role of T and B lymphocytes

Non-alcoholic fatty liver disease (NAFLD), characterized by the excessive accumulation of fat within the cytoplasm of hepatocytes (exceeding 5% of liver weight) in individuals without significant alcohol consumption, has rapidly evolved into a pressing global health issue, affecting approximately 25% of the world population. This condition, closely associated with obesity, type 2 diabetes, and the metabolic syndrome, encompasses a spectrum of liver disorders ranging from simple steatosis without inflammation to non-alcoholic steatohepatitis (NASH) and cirrhotic liver disease. Recent research has illuminated the complex interplay between metabolic and immune responses in the pathogenesis of NASH, underscoring the critical role played by T and B lymphocytes. These immune cells not only contribute to necroinflammatory changes in hepatic lobules but may also drive the onset and progression of liver fibrosis. This narrative review aims to provide a comprehensive exploration of the effector mechanisms employed by T cells, B cells, and their respective subpopulations in the pathogenesis of NASH. Understanding the immunological complexity of NASH holds profound implications for the development of targeted immunotherapeutic strategies to combat this increasingly prevalent and burdensome metabolic liver disease.

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.

Investigating the tamoxifen/high-fat diet synergy: a promising paradigm for nonalcoholic steatohepatitis induction in a rat model

Non-alcoholic steatohepatitis (NASH) is a severe liver condition characterized by excessive fat deposition, ballooning, and lobular inflammation. This investigation was conducted to estimate the capability of concomitant tamoxifen administration (TAM) with a high fat diet (HFD) to induce a reliable NASH model that mimics human NASH features. Rats were administered TAM (25 mg/kg/day p.o.) and consumed HFD for 5 weeks. A time-course investigation was conducted to determine the optimal time for NASH development. Liver function indices, hepatic lipid profile factors, oxidative stress biomarkers, and inflammatory mediators were estimated. Additionally, macroscopic and microscopic changes were examined. Compared with the time-matched control group receiving vehicle alone, TAM/HFD significantly impaired liver function indices represented as marked elevation in ALT, AST, and ALP serum levels. TAM/HFD significantly increased lipid profile factors including high TG and TC hepatic levels. Additionally, TAM/HFD remarkably raised hepatic levels of TNF-α and IL-17 and significantly decreased IL-10. The combination also increases the oxidative status evidenced by high content of MDA as well as low activity of GPx and SOD. Accordingly, the combination of TAM and HFD for 5 weeks collaboratively promotes NASH development by initiating compromised hepatocyte functionality, elevated lipid levels, oxidative stress, and liver inflammation.

Generalized Pustular Psoriasis and Systemic Organ Dysfunctions

This review explores the intricate relationship between generalized pustular psoriasis (GPP) and various systemic diseases, shedding light on the broader impacts of this severe skin condition beyond its primary dermatological manifestations. GPP is identified as not only a profound contributor to skin pathology but also a significant risk factor for systemic diseases affecting cardiovascular, hepatic, renal, pulmonary, and skeletal systems, as well as associated with an increased incidence of anemia, depression, anxiety, and arthritis. The research highlights the complex interplay of cytokines, particularly IL-17 and IL-36, which are central to the pathophysiology of GPP and implicated in the exacerbation of systemic conditions. Key findings indicate a higher incidence of cardiovascular events in GPP patients compared to those with other severe forms of psoriasis, notably with a stronger correlation between myocardial infarction history and GPP development. Liver disturbances, frequently reversible upon psoriasis remission, suggest a cytokine-mediated link to hepatic health. Renal dysfunction appears elevated in GPP sufferers, with IL-17 and IL-36 potentially driving renal fibrosis. Similarly, interstitial lung disease and osteoporosis in GPP patients underscore the systemic reach of inflammatory processes initiated in the skin. The associations with anemia, depression, anxiety, and arthritis further complicate the clinical management of GPP, requiring a multidisciplinary approach. The study concludes that managing GPP effectively requires a holistic approach that addresses both the cutaneous and systemic dimensions of the disease, advocating for continued research into the mechanisms that connect GPP with broader health implications to refine therapeutic strategies.

Implications of Microbiota and Immune System in Development and Progression of Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent type of liver disease worldwide. The exact pathophysiology behind MASLD remains unclear; however, it is thought that a combination of factors or "hits" act as precipitants for disease onset and progression. Abundant evidence supports the roles of diet, genes, metabolic dysregulation, and the intestinal microbiome in influencing the accumulation of lipids in hepatocytes and subsequent progression to inflammation and fibrosis. Currently, there is no cure for MASLD, but lifestyle changes have been the prevailing cornerstones of management. Research is now focusing on the intestinal microbiome as a potential therapeutic target for MASLD, with the spotlight shifting to probiotics, antibiotics, and fecal microbiota transplantation. In this review, we provide an overview of how intestinal microbiota interact with the immune system to contribute to the pathogenesis of MASLD and metabolic dysfunction-associated steatohepatitis (MASH). We also summarize key microbial taxa implicated in the disease and discuss evidence supporting microbial-targeted therapies in its management.

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.

[Oral microbiota and liver]

The liver has many important biological functions for the body, as it is involved in the storage and distribution of nutrients (carbohydrates to glycogen, lipids to triglycerides), the digestion of fats, the synthesis of blood proteins, and the detoxification of alcohol and drugs. The liver can be affected by various diseases such as viral or drug-induced hepatitis, fibrosis and cirrhosis, in which damaged hepatocytes are progressively replaced by scar tissue.

Cholesterol Exacerbates the Pathophysiology of Non-Alcoholic Steatohepatitis by Upregulating Hypoxia-Inducible Factor 1 and Modulating Microcirculatory Dysfunction

Cholesterol is a pivotal lipotoxic molecule that contributes to the progression of Non-Alcoholic Steatohepatitis NASH). Additionally, microcirculatory changes are critical components of Non-Alcoholic Fatty Liver Disease (NAFLD) pathogenesis. This study aimed to investigate the role of cholesterol as an insult that modulates microcirculatory damage in NAFLD and the underlying mechanisms. The experimental model was established in male C57BL/6 mice fed a high-fat high-carbohydrate (HFHC) diet for 39 weeks. Between weeks 31-39, 2% cholesterol was added to the HFHC diet in a subgroup of mice. Leukocyte recruitment and hepatic stellate cells (HSC) activation in microcirculation were assessed using intravital microscopy. The hepatic microvascular blood flow (HMBF) was measured using laser speckle flowmetry. High cholesterol levels exacerbated hepatomegaly, hepatic steatosis, inflammation, fibrosis, and leukocyte recruitment compared to the HFHC group. In addition, cholesterol decreased the HMBF-cholesterol-induced activation of HSC and increased HIF1A expression in the liver. Furthermore, cholesterol promoted a pro-inflammatory cytokine profile with a Th1-type immune response (IFN-γ/IL-4). These findings suggest cholesterol exacerbates NAFLD progression through microcirculatory dysfunction and HIF1A upregulation through hypoxia and inflammation. This study highlights the importance of cholesterol-induced lipotoxicity, which causes microcirculatory dysfunction associated with NAFLD pathology, thus reinforcing the potential of lipotoxicity and microcirculation as therapeutic targets for NAFLD.

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.

Use of a ferroptosis-related gene signature to construct diagnostic and prognostic models for assessing immune infiltration in metabolic dysfunction-associated fatty liver disease

Introduction: Metabolic dysfunction-associated fatty liver disease (MAFLD), a serious health problem worldwide, can involve ferroptosis. This study aimed to comprehensively analyze the ferroptosis-related genes associated with MAFLD. Methods: Ferroptosis-related differentially expressed genes (FRDEGs) were identified in patients with MAFLD and healthy individuals. Gene ontology functional enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, and gene set enrichment analysis (GSEA) were used to analyze the relevant action pathways of the FRDEGs. The Encyclopedia of RNA Interactomes, CHIPBase, and comparative toxicogenomics databases were used to build mRNA-miRNA, mRNA-transcription factor (TF), and mRNA-drug interaction networks, respectively. A diagnostic model was constructed and bioinformatics analysis methods, such as least absolute shrinkage and selection operator regression analysis, Cox regression analysis, nomogram-based analysis, consensus clustering analysis, and single-sample GSEA, were used to systematically investigate the prognostic values and immunologic characteristics. Results: A total of 13 FRDEGs were obtained and eight were used to construct a diagnostic model and perform a prognostic analysis. Hub genes were also used to construct mRNA-miRNA and mRNA-TF interaction networks and potential drug or molecular compounds. Two MAFLD subtypes were identified: cluster2, which represents an "immunoactive" type, and cluster1, which represents an "immunosuppressive" type; a significant correlation was observed between the immune cell contents and the expression of three FRDEGs (NR4A1, FADS2, and SCD). Conclusion: A ferroptosis-related gene signature was constructed to diagnose MAFLD-associated steatohepatitis, predict the prognosis of MAFLD patients, and analyze the immunologic characteristics of MAFLD. Our findings may provide insights into developing innovative MAFLD treatment techniques.

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.

Radiographic and histopathological study of gastrointestinal dysmotility in lipopolysaccharide-induced sepsis in the rat

BACKGROUND

Sepsis is a highly incident condition in which a cascade of proinflammatory cytokines is involved. One of its most frequent consequences is ileus, which can increase mortality. Animal models such as that induced by systemic administration of lipopolysaccharide (LPS) are useful to deeply evaluate this condition. The effects of sepsis on the gastrointestinal (GI) tract have been explored but, to our knowledge, in vivo studies showing the motor and histopathological consequences of endotoxemia in an integrated way are lacking. Our aim was to study in rats the effects of sepsis on GI motility, using radiographic methods, and to assess histological damage in several organs.

METHODS

Male rats were intraperitoneally injected with saline or E. coli LPS at 0.1, 1, or 5 mg kg-1 . Barium sulfate was intragastrically administered, and X-rays were performed 0-24 h afterwards. Several organs were collected for organography, histopathology, and immunohistochemistry studies.

KEY RESULTS

All LPS doses caused gastroparesia, whereas changes in intestinal motility were dose-and time-dependent, with an initial phase of hypermotility followed by paralytic ileus. Lung, liver, stomach, ileum, and colon (but not spleen or kidneys) were damaged, and density of neutrophils and activated M2 macrophages and expression of cyclooxygenase 2 were increased in the colon 24 h after LPS 5 mg kg-1 .

CONCLUSIONS AND INFERENCES

Using radiographic, noninvasive methods for the first time, we show that systemic LPS causes dose-, time-, and organ-dependent GI motor effects. Sepsis-induced GI dysmotility is a complex condition whose management needs to take its time-dependent changes into account.

Preventive and therapeutic effects of natural products and herbal extracts on nonalcoholic fatty liver disease/nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a common condition that is prevalent in patients who consume little or no alcohol, and is characterized by excessive fat accumulation in the liver. The disease is becoming increasingly common with the rapid economic development of countries. Long-term accumulation of excess fat can lead to NAFLD, which represents a global health problem with no effective therapeutic approach. NAFLD is a complex, multifaceted pathological process that has been the subject of extensive research over the past few decades. Herbal medicines have gained attention as potential therapeutic agents to prevent and treat NAFLD due to their high efficacy and low risk of side effects. Our overview is based on a PubMed and Web of Science database search as of Dec 22 with the keywords: NAFLD/NASH Natural products and NAFLD/NASH Herbal extract. In this review, we evaluate the use of herbal medicines in the treatment of NAFLD. These natural resources have the potential to inform innovative drug research and the development of treatments for NAFLD in the future.

Adipokines in obesity and metabolic-related-diseases

The discovery of leptin in the 1990s led to a reconsideration of adipose tissue (AT) as not only a fatty acid storage organ, but also a proper endocrine tissue. AT is indeed capable of secreting bioactive molecules called adipokines for white AT or batokines for brown/beige AT, which allow communication with numerous organs, especially brain, heart, liver, pancreas, and/or the vascular system. Adipokines exert pro or anti-inflammatory activities. An equilibrated balance between these two sets ensures homeostasis of numerous tissues and organs. During the development of obesity, AT remodelling leads to an alteration of its endocrine activity, with increased secretion of pro-inflammatory adipokines relative to the anti-inflammatory ones, as shown in the graphical abstract. Pro-inflammatory adipokines take part in the initiation of local and systemic inflammation during obesity and contribute to comorbidities associated to obesity, as detailed in the present review.

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.

IL-23/IL-17 Axis in Chronic Hepatitis C and Non-Alcoholic Steatohepatitis-New Insight into Immunohepatotoxicity of Different Chronic Liver Diseases

Considering the relevance of the research of pathogenesis of different liver diseases, we investigated the possible activity of the IL-23/IL-17 axis on the immunohepatotoxicity of two etiologically different chronic liver diseases. A total of 36 chronic hepatitis C (CHC) patients, 16 with (CHC-SF) and 20 without significant fibrosis (CHC-NSF), 19 patients with non-alcoholic steatohepatitis (NASH), and 20 healthy controls (CG) were recruited. Anthropometric, biochemical, and immunological cytokines (IL-6, IL-10, IL-17 and IL-23) tests were performed in accordance with standard procedure. Our analysis revealed that a higher concentration of plasma IL-23 was associated with NASH (p = 0.005), and a higher concentration of plasma IL-17A but a lower concentration of plasma IL-10 was associated with CHC in comparison with CG. A lower concentration of plasma IL-10 was specific for CHC-NSF, while a higher concentration of plasma IL-17A was specific for CHC-SF in comparison with CG. CHC-NSF and CHC-SF groups were distinguished from NASH according to a lower concentration of plasma IL-17A. Liver tissue levels of IL-17A and IL-23 in CHC-NSF were significantly lower in comparison with NASH, regardless of the same stage of the liver fibrosis, whereas only IL-17A tissue levels showed a difference between the CHC-NSF and CHC-SF groups, namely, a lower concentration in CHC-NSF in comparison with CHC-SF. In CHC-SF and NASH liver tissue, IL17-A and IL-23 were significantly higher in comparison with plasma. Diagnostic accuracy analysis showed significance only in the concentration of plasma cytokines. Plasma IL-6, IL-17A and IL-23 could be possible markers that could differentiate CHC patients from controls. Plasma IL-23 could be considered a possible biomarker of CHC-NSF patients in comparison with controls, while plasma IL-6 and IL-17-A could be biomarkers of CHC-SF patients in comparison with controls. The most sophisticated difference was between the CHC-SF and CHC-NSF groups in the plasma levels of IL-10, which could make this cytokine a useful biomarker of liver fibrosis.

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.

Impaired flux of bile acids from the liver to the gut reveals microbiome-immune interactions associated with liver damage

Currently, there is evidence that alteration in the gut ecosystem contributes to the development of liver diseases, however, the complex mechanisms involved are still unclear. We induced cholestasis in mice by bile duct ligation (BDL), mirroring the phenotype of a bile duct obstruction, to understand how gut microbiota alterations caused by an impaired flow of bile acid to the gut contribute to the pathogenesis and progression of liver disease. We performed longitudinal stool, heart, and liver sampling using mice receiving BDL and controls receiving sham operation (ShamOP). Shotgun metagenomics profiling using fecal samples taken before and on day 1, day 3, and day 7 after surgery was performed, and the cytokines and clinical chemistry profiles from heart blood, as well as the liver bile acids profile, were measured. The BDL surgery reshaped the microbiome of mice, resulting in highly distinct characteristics compared to the ShamOP. Our analysis of the microbiome pathways and ECs revealed that BDL reduces the production of hepatoprotective compounds in the gut, such as biotin, spermidine, arginine, and ornithine, which were negatively associated with inflammatory cytokines (IL-6, IL-23, MCP-1). The reduction of the functional potential of the gut microbiota in producing those hepatoprotective compounds is associated with the decrease of beneficial bacteria species from Anaerotruncus, Blautia, Eubacterium, and Lachnoclostridium genera, as well as the increase of disease-associated bacteria e.g., Escherichia coli and Entercoccus faecalis. Our findings advances our knowledge of the gut microbiome-bile acids-liver triangle, which may serve as a potential therapeutic strategy for liver diseases.

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.

Psoriatic disease and non-alcoholic fatty liver disease shared pathogenesis review

Psoriatic disease (PD) and non-alcoholic fatty liver disease (NAFLD) potentially share disease pathways given the numerous inflammatory pathways involved in both diseases and a higher prevalence of NAFLD in PD patients.  Metabolic syndrome and obesity are a key link between the two diseases, but even when controlling for this, associations between both diseases are still seen. Therapeutics that impact metabolic or inflammatory pathways may be impactful in both PD and NAFLD. In this review, we describe common inflammatory pathways contributing to both PD and NAFLD and critically review the potential impact of treatments for and on both diseases.

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.

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.

Inflammatory processes involved in NASH-related hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related death worldwide. In the recent years nonalcoholic fatty liver disease (NAFLD) is becoming a growing cause of HCCs and the incidence of NAFLD-related HCCs is expected to further dramatically increase by the next decade. Chronic inflammation is regarded as the driving force of NAFLD progression and a key factor in hepatic carcinogenesis. Hepatic inflammation in NAFLD results from the persistent stimulation of innate immunity in response to hepatocellular injury and gut dysbiosis as well as by the activation of adaptive immunity. However, the relative roles of innate and adaptive immunity in the processes leading to HCC are still incompletely characterized. This is due to the complex interplay between different liver cell populations, which is also strongly influenced by gut-derived bacterial products, metabolic/nutritional signals. Furthermore, carcinogenic mechanisms in NAFLD/NASH appear to involve the activation of signals mediated by hypoxia inducible factors. This review discusses recent data regarding the contribution of different inflammatory cells to NAFLD-related HCC and their possible impact on patient response to current treatments.

The Development of Systemic Inflammatory Diseases in Hidradenitis Suppurativa

It is understood that the skin is a peripheral lymphoid tissue that defends against external environmental stimuli. Continuous activation from these factors, on the other hand, promotes persistent inflammation at the local location and, occasionally, tissue damage. Hidradenitis suppurativa (HS) is a typical inflammatory skin disease and becomes a source of numerous inflammatory cytokines due to the chronic intractable repeated inflamed tissues. Because inflammatory cells and cytokines circulate throughout the body from the inflamed organ, it has been hypothesized that HS-mediated skin inflammation impacts the systemic functioning of numerous organs. Recent updates to clinical and experimental investigations revealed that HS has a significant connection with systemic inflammatory disorders. We provide the details and comprehensive molecular mechanisms associated with systemic inflammatory illnesses due to HS.

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.

The phenolic compounds tyrosol and hydroxytyrosol counteract liver fibrogenesis via the transcriptional modulation of NADPH oxidases and oxidative stress-related miRNAs

Liver fibrosis is the result of a chronic pathological condition caused by the activation of hepatic stellate cells (HSCs), which induces the excessive deposition of extracellular matrix. Fibrogenesis is sustained by an exaggerated production of reactive oxidative species (ROS) by NADPH oxidases (NOXs), which are overactivated in hepatic inflammation. In this study, we investigated the antifibrotic properties of two phenolic compounds of natural origin, tyrosol (Tyr) and hydroxytyrosol (HTyr), known for their antioxidant and anti-inflammatory effects. We assessed Tyr and HTyr antifibrotic and antioxidant activity both in vitro, by a co-culture of LX2, HepG2 and THP1-derived Mϕ macrophages, set up to simulate the hepatic microenvironment, and in vivo, in a mouse model of liver fibrosis obtained by carbon tetrachloride treatment. We evaluated the mRNA and protein expression of profibrotic and oxidative markers (α-SMA, COL1A1, NOX1/4) by qPCR and/or immunocytochemistry or immunohistochemistry. The expression of selected miRNAs in mouse livers were measured by qPCR. Tyr and HTyr reduces fibrogenesis in vitro and in vivo, by downregulating all fibrotic markers. Notably, they also modulated oxidative stress by restoring the physiological levels of NOX1 and NOX4. In vivo, this effect was accompanied by a transcriptional regulation of inflammatory genes and of 2 miRNAs involved in the control of oxidative stress damage (miR-181-5p and miR-29b-3p). In conclusion, Tyr and HTyr exert antifibrotic and anti-inflammatory effects in preclinical in vitro and in vivo models of liver fibrosis, by modulating hepatic oxidative stress, representing promising candidates for further development.

A Dietary Oxysterol, 7-Ketocholesterol, Exacerbates Imiquimod-Induced Psoriasis-like Dermatitis in Steatohepatitic Mice

Patients with psoriasis are at a higher risk of developing nonalcoholic fatty liver disease. We previously identified an oxidized derivative of cholesterol, 7-ketocholesterol (7KC), in diet-induced steatohepatitic mice. Here, we investigated whether 7KC exacerbates psoriasis-like dermatitis by accelerating steatohepatitis in mice. A high-fat/high-cholesterol/high-sucrose/bile salt diet (nonalcoholic steatohepatitis (NASH) diet) with or without 0.0125% 7KC was fed to C57BL/6 mice (7KC or control group) for three weeks to induce steatohepatitis. A 5% imiquimod cream was then applied to the ears and dorsal skin for four days to induce psoriasis-like dermatitis. Hepatic lipid accumulation and inflammatory cell infiltration were exacerbated in the 7KC group compared with the control group after three weeks. Serum tumor necrosis factor-α (TNF-α) levels were also elevated in the 7KC group (108.5 ± 9.8 vs. 83.1 ± 13.1 pg/mL, p < 0.005). Imiquimod cream increased the psoriasis area severity index (PASI) score in mice in the 7KC group (9.14 ± 0.75 vs. 5.17 ± 1.17, p < 0.0001). Additionally, Tnfa, Il23a, Il17a, and Il22 mRNA levels in the dorsal lesion were significantly upregulated. Finally, Th17 cell differentiation and the TNF signaling pathway were enhanced in the dorsal lesions and liver of mice in the 7KC group. These data suggest that steatohepatitis and psoriasis are linked by a potent, diet-related factor.

The molecular basis of the associations between non-alcoholic fatty liver disease and colorectal cancer

Background: Given the ongoing research on non-alcoholic fatty liver disease (NAFLD) and colorectal cancer (CRC), the number of studies suggesting a strong link between NAFLD and CRC is on the rise, while its underlying pathological mechanisms remain uncertain. This study aims to explore the shared genes and mechanisms and to reveal the molecular basis of the association between CRC and NAFLD through bioinformatics approaches. Methods: The Gene Expression Omnibus (GEO) dataset GSE89632 is downloaded for NAFLD cases and healthy controls. Additionally, the GSE4107 and GSE9348 datasets are obtained for CRC cases and healthy controls. Differentially expressed genes (DEGs) are obtained for NAFLD and CRC datasets, as well as shared genes between the two disorders. GO and KEGG enrichment analyses are further conducted. Subsequently, the STRING database and Cytoscape software are utilized to establish the PPI network and identify the hub genes. Then, co-expression analysis is performed using GeneMANIA. Subsequently, ROC curves and external datasets validation were applied to further screen the candidate markers. Finally, NetworkAnalyst is available as a means to construct a miRNA-gene regulatory network. Results: Under the threshold of FDR ≤ 0.01, 147 common genes are obtained in NAFLD and CRC. Categorization of GO functions shows that DEGs are predominantly enriched in "response to organic substance", "cellular response to chemical stimulus", and "response to external stimulus". The predominant KEGG pathways in DEGs are the "IL-17 signaling pathway", the "TNF signaling pathway", "Viral protein interaction with cytokine and cytokine receptor", "Cytokine-cytokine receptor interaction", and the "Toll-like receptor signaling pathway". Additionally, MYC, IL1B, FOS, CXCL8, PTGS2, MMP9, JUN, and IL6 are identified as hub genes by the evaluation of 7 algorithms. With the construction of miRNA-gene networks, 2 miRNAs, including miR-106a-5p, and miR-204-5p are predicted to be potential key miRNAs. Conclusion: This study identifies possible hub genes acting in the co-morbidity of NAFLD and CRC and discovers the interaction of miRNAs and hub genes, providing a novel understanding of the molecular basis for the relevance of CRC and NAFLD, thus contributing to the development of new therapeutic strategies to combat NAFLD and CRC.

NAFLD and HBV interplay - related mechanisms underlying liver disease progression

Non-alcoholic fatty liver disease (NAFLD) and Hepatitis B virus infection (HBV) constitute common chronic liver diseases with worldwide distribution. NAFLD burden is expected to grow in the coming decade, especially in western countries, considering the increased incidence of diabetes and obesity. Despite the organized HBV vaccinations and use of anti-viral therapies globally, HBV infection remains endemic and challenging public health issue. As both NAFLD and HBV have been associated with the development of progressive fibrosis, cirrhosis and hepatocellular carcinoma (HCC), the co-occurrence of both diseases has gained great research and clinical interest. The causative relationship between NAFLD and HBV infection has not been elucidated so far. Dysregulated fatty acid metabolism and lipotoxicity in NAFLD disease seems to initiate activation of signaling pathways that enhance pro-inflammatory responses and disrupt hepatocyte cell homeostasis, promoting progression of NAFLD disease to NASH, fibrosis and HCC and can affect HBV replication and immune encountering of HBV virus, which may further have impact on liver disease progression. Chronic HBV infection is suggested to have an influence on metabolic changes, which could lead to NAFLD development and the HBV-induced inflammatory responses and molecular pathways may constitute an aggravating factor in hepatic steatosis development. The observed altered immune homeostasis in both HBV infection and NAFLD could be associated with progression to HCC development. Elucidation of the possible mechanisms beyond HBV chronic infection and NAFLD diseases, which could lead to advanced liver disease or increase the risk for severe complications, in the case of HBV-NAFLD co-existence is of high clinical significance in the context of designing effective therapeutic targets.

Association between inflammatory markers and non-alcoholic fatty liver disease in obese children

Background

Given the high prevalence of non-alcoholic fatty liver disease (NAFLD) in obese children, non-invasive markers of disease to date are still limited and worth exploring.

Objective

This study aimed to evaluate the association between inflammatory markers and NAFLD in obese children.

Methods

We performed a case-control study in Hunan Children's Hospital from September 2020 to September 2021. Study participants were children with obesity diagnosed with NAFLD by abdominal ultrasound examination. Mean platelet volume (MPV), platelet distribution width (PDW), neutrophil, lymphocyte, monocyte, and platelet counts were extracted from medical records and inflammatory cytokines were measured by enzyme-linked immunosorbent assay (ELISA). Multivariable logistic regression analysis was performed to evaluate the association between inflammatory markers and NAFLD. We also used receiver operating characteristic curve analysis to assess the discriminative ability of inflammatory cytokines for NAFLD.

Results

Two hundred and sixty-seven obese children were enrolled, including 176 NAFLD patients and 91 simple obesity controls. Multivariable logistic model indicated that increased interleukin (IL)-1β [odds ratio (OR) = 1.15, 95% confidence interval (CI): 1.04-1.27], IL-6 (OR = 1.28, 95% CI: 1.07-1.53), and IL-17 (OR = 1.04, 95% CI: 1.02-1.07) levels were significantly associated with NAFLD. In contrast, we observed non-significant associations for IL-8, IL-12, IL-21, IL-32, tumor necrosis factor-α (TNF-α), neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), lymphocyte to monocyte ratio (LMR), mean platelet volume (MPV), and platelet distribution width (PDW) with NAFLD. The area under the curves (AUCs) of IL-1β, IL-6, and IL-17 to discriminate obese children with or without NAFLD were 0.94, 0.94, and 0.97, respectively.

Conclusions

Our results indicated that IL-1β, IL-6, and IL-17 levels were significantly associated with NAFLD. These inflammatory cytokines may serve as non-invasive markers to determine the development of NAFLD and potentially identify additional avenues for therapeutic intervention.

Advances in T Cells Based on Inflammation in Metabolic Diseases

With the increasing incidence of metabolic diseases year by year and their impact on the incidence of cardiovascular diseases, metabolic diseases have attracted great attention as a major health care problem, but there is still no effective treatment. Oxidative stress and inflammation are the main mechanisms leading to metabolic diseases. T cells are involved in the inflammatory response, which can also regulate the development of metabolic diseases, CD4+ T cells and CD8+ T cells are mainly responsible for the role. Th1 and Th17 differentiated from CD4+ T promote inflammation, while Th2 and Treg inhibit inflammation. CD8+ T cells also contribute to inflammation. The severity and duration of inflammatory reactions can also lead to different degrees of progression of metabolic diseases. Moreover, mTOR, PI3K-Akt, and AMPK signaling pathways play unique roles in the regulation of T cells, which provide a new direction for the treatment of metabolic diseases in the future. In this review, we will elaborate on the role of T cells in regulating inflammation in various metabolic diseases, the signaling pathways that regulate T cells in metabolic diseases, and the latest research progress.

Folic acid ameliorates alcohol-induced liver injury via gut–liver axis homeostasis

The gut–liver axis (GLA) plays an important role in the development of alcohol-induced liver injury. Alcohol consumption is typically associated with folic acid deficiency. However, no clear evidence has confirmed the effect of folic acid supplementation on alcohol-induced liver injury via GLA homeostasis. In this study, male C57BL/6J mice were given 56% (v/v) ethanol and 5.0 mg/kg folic acid daily by gavage for 10 weeks to investigate potential protective mechanisms of folic acid in alcohol-induced liver injury via GLA homeostasis. Histopathological and biochemical analyses showed that folic acid improved lipid deposition and inflammation in the liver caused by alcohol consumption and decreased the level of ALT, AST, TG, and LPS in serum. Folic acid inhibited the expression of the TLR4 signaling pathway and its downstream inflammatory mediators in the liver and upregulated the expression of ZO-1, claudin 1, and occludin in the intestine. But compared with the CON group, folic acid did not completely eliminate alcohol-induced intestine and liver injury. Furthermore, folic acid regulated alcohol-induced alterations in gut microbiota. In alcohol-exposed mice, the relative abundance of Bacteroidota was significantly increased, and the relative abundance of unclassified_Lachnospiraceae was significantly decreased. Folic acid supplementation significantly increased the relative abundance of Verrucomicrobia, Lachnospiraceae_NK4A136_group and Akkermansia, and decreased the relative abundance of Proteobacteria. The results of Spearman’s correlation analysis showed that serum parameters and hepatic inflammatory cytokines were significantly correlated with several bacteria, mainly including Bacteroidota, Firmicutes, and unclassified_Lachnospiraceae. In conclusion, folic acid could ameliorate alcohol-induced liver injury in mice via GLA homeostasis to some extent, providing a new idea and method for prevention of alcohol-induced liver injury.

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).

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.

FTO promotes liver inflammation by suppressing m6A mRNA methylation of IL-17RA

Background

Previous studies have demonstrated that inflammation-related interleukin-17 (IL-17) signaling plays a pivotal role in the pathogenesis of non-alcoholic steatohepatitis (NASH)- and alcoholic liver disease (ALD)-induced hepatocellular carcinoma (HCC). However, rare efforts have been intended at implementing the analysis of N6-methyladenosine (m6A) mRNA methylation to elucidate the underpinning function of the IL-17 receptor A (IL-17RA) during the inflammation-carcinogenesis transformation of HCC.

Methods

We performed methylated RNA immunoprecipitation sequencing (MeRIP-seq) using normal, HCC tumor and paired tumor adjacent tissues from patients to investigate the dynamic changes of m6A mRNA methylation in the process of HCC. Additionally, murine non-alcoholic fatty liver disease (NAFLD) model and murine chronic liver injury model were utilized to investigate the role of IL-17RA regulated by m6A mRNA modulator fat mass and obesity-associated (FTO) in chronic hepatic inflammation.

Results

MeRIP-seq revealed the reduction of m6A mRNA methylation of IL-17RA in tumor adjacent tissues with chronic inflammation, suggesting the potential role of IL-17RA in the inflammation-carcinogenesis transformation of HCC. Besides, we demonstrated that FTO, rather than methyltransferase-like 3 (METTL3), methyltransferase-like 14 (METTL14), and alkB homolog 5 (ALKBH5) functions as a main modulator for the decrease of m6A mRNA methylation of IL-17RA via knockdown and overexpression of FTO in vitro and in vivo.

Conclusions

Overall, we elaborated the underlying mechanisms of the increase of IL-17RA resulting in chronic inflammation via the demethylation of FTO in tumor adjacent tissues and demonstrated that targeting the specific m6A modulator FTO may provide an effective treatment for hepatitis patients to prevent the development of HCC.

Serum Interleukins as Potential Prognostic Biomarkers in HBV-Related Acute-on-Chronic Liver Failure

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is relatively common in China and has complex pathogenesis, difficult clinical treatment, and poor prognosis. Immune status is an important factor affecting ACLF prognosis. Interleukins are a family of secreted lymphocyte factors that interact with a host of cell types including immune cells. These signaling molecules play important roles in transmitting information; regulating immune cells; mediating the activation, proliferation, and differentiation of T and B cells; and modulating inflammatory responses. Many studies have investigated the correlation between interleukin expression and the prognosis of HBV-ACLF. This review focuses on the potential use of interleukins as prognostic biomarkers in HBV-ACLF. References were mainly identified through PubMed and CNKI search, including relevant studies published until December 2021. We have summarized reports of several promising diagnostic interleukin biomarkers that predict susceptibility to HBV-ACLF. The use of biomarkers to understand early prognosis can help devise different therapeutic measures and improve patient survival. Ongoing research on prognostic biomarkers of HBV-ACLF is promising, and future preclinical and clinical studies are warranted.

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.

Understanding the cellular interactome of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is reaching epidemic proportions, with a global prevalence of 25% in the adult population. Non-alcoholic steatohepatitis (NASH), which can lead to cirrhosis, has become the leading indication for liver transplantation in both Europe and the USA. Liver fibrosis is the consequence of sustained, iterative liver injury, and the main determinant of outcomes in NASH. The liver possesses remarkable inherent plasticity, and liver fibrosis can regress when the injurious agent is removed, thus providing opportunities to alter long-term outcomes through therapeutic interventions. Although hepatocyte injury is a key driver of NASH, multiple other cell lineages within the hepatic fibrotic niche play major roles in the perpetuation of inflammation, mesenchymal cell activation, extracellular matrix accumulation as well as fibrosis resolution. The constituents of this cellular interactome, and how the various subpopulations within the fibrotic niche interact to drive fibrogenesis is an area of active research. Important cellular components of the fibrotic niche include endothelial cells, macrophages, passaging immune cell populations and myofibroblasts. In this review, we will describe how rapidly evolving technologies such as single-cell genomics, spatial transcriptomics and single-cell ligand-receptor analyses are transforming our understanding of the cellular interactome in NAFLD/NASH, and how this new, high-resolution information is being leveraged to develop rational new therapies for patients with NASH.

Fine-tuning of regulatory T cells is indispensable for the metabolic steatosis-related hepatocellular carcinoma: A review

The majority of chronic hepatic diseases are caused by nutritional imbalance. These nutritional inequities include excessive intake of alcohol and fat, which causes alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD), respectively. The pathogenesis of hepatic diseases is mainly dependent on oxidative stress, autophagy, DNA damage, and gut microbiota and their metabolites. These factors influence the normal physiology of the liver and impact the hepatic microenvironment. The hepatic microenvironment contains several immune cells and inflammatory cytokines which interact with each other and contribute to the progression of chronic hepatic diseases. Among these immune cells, Foxp3⁺ CD4⁺ regulatory T cells (Tregs) are the crucial subset of CD4⁺ T cells that create an immunosuppressive environment. This review emphasizes the function of Tregs in the pathogenesis of ALD and NAFLD and their role in the progression of NAFLD-associated hepatocellular carcinoma (HCC). Briefly, Tregs establish an immunosuppressive landscape in the liver by interacting with the innate immune cells and gut microbiota and their metabolites. Meanwhile, with the advancement of steatosis, these Tregs inhibit the proliferation, activation and functions of other cytotoxic T cells and support the progression of simple steatosis to HCC. Briefly, it can be suggested that targeting Tregs can act as a favourable prognostic indicator by modulating steatosis and insulin resistance during the pathogenesis of hepatic steatosis and NAFLD-associated HCC.

Immune cell-mediated features of non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) includes a range of hepatic manifestations, starting with liver steatosis and potentially evolving towards non-alcoholic steatohepatitis (NASH), cirrhosis or even hepatocellular carcinoma. NAFLD is a major health burden, and its incidence is increasing worldwide. Although it is primarily a disease of disturbed metabolism, NAFLD involves several immune cell-mediated inflammatory processes, particularly when reaching the stage of NASH, at which point inflammation becomes integral to the progression of the disease. The hepatic immune cell landscape is diverse at steady state and it further evolves during NASH with direct consequences for disease severity. In this Review, we discuss current concepts related to the role of immune cells in the onset and progression of NASH. A better understanding of the mechanisms by which immune cells contribute to NASH pathogenesis should aid the design of innovative drugs to target NASH, for which current therapeutic options are limited.

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.

Update on Non-Alcoholic Fatty Liver Disease-Associated Single Nucleotide Polymorphisms and Their Involvement in Liver Steatosis, Inflammation, and Fibrosis: A Narrative Review

Genetic factors are involved in the development, progression, and severity of NAFLD. Polymorphisms in genes regulating liver functions may increase liver susceptibility to NAFLD. Therefore, we conducted this literature study to present recent findings on NAFLD-associated polymorphisms from published articles in PubMed from 2016 to 2021. From 69 selected research articles, 20 genes and 34 SNPs were reported to be associated with NAFLD. These mutated genes affect NAFLD by promoting liver steatosis (PNPLA3, MBOAT7, TM2SF6, PTPRD, FNDC5, IL-1B, PPARGC1A, UCP2, TCF7L2, SAMM50, IL-6, AGTR1, and NNMT), inflammation (PNPLA3, TNF-α, AGTR1, IL-17A, IL-1B, PTPRD, and GATAD2A), and fibrosis (IL-1B, PNPLA3, MBOAT7, TCF7L2, GATAD2A, IL-6, NNMT, UCP, AGTR1, and TM2SF6). The identification of these genetic factors helps to better understand the pathogenesis pathways of NAFLD

The role of the immune system in the pathogenesis of NAFLD and potential therapeutic impacts of mesenchymal stem cell-derived extracellular vesicles

Non-Alcoholic Fatty Liver Disease (NAFLD) is characterized by intra-hepatocyte triglyceride accumulation and concomitant involvement of the immune system with subsequent histological changes, tissue damage, and clinical findings. There are various molecular pathways involved in the progression of NAFLD including lipotoxicity, endoplasmic reticulum stress, and the immune response. Both innate and adaptive immune systems are involved in the NAFLD pathogenesis, and crosstalk between the immune cells and liver cells participates in its initiation and progression. Among the various treatments for this disease, new cell based therapies have been proposed. Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSC) (MSC-EVs) are new cell-free vehicles with low immunogenicity, which can suppress detrimental immune responses in inflamed tissues. This review aimed to express the immune system's molecular pathways associated with the initiation and progression of NAFLD. Then, the possible role of MSC-EVs in the treatment of this entity through immune response modulation was discussed. Finally, engineered EVs enhanced by specific therapeutic miRNA were suggested for alleviating the pathological cellular events in liver disease.

[Translated article] Practical Update of the Guidelines Published by the Psoriasis Group of the Spanish Academy of Dermatology and Venereology (GPs) on the Treatment of Psoriasis With Biologic Agents: Part 2-Management of Special Populations, Patients With Comorbid Conditions, and Risk

BACKGROUND AND OBJECTIVES

Since its inception, the Psoriasis Group (GPs) of the Spanish Academy of Dermatology and Venereology (AEDV) has worked to continuously update recommendations for the treatment of psoriasis based on the best available evidence and incorporating proposals arising from and aimed at clinical practice. An updated GPs consensus document on the treatment of moderate to severe psoriasis was needed because of changes in the treatment paradigm and the approval in recent years of a large number of new biologic agents.

METHODOLOGY

The consensus document was developed using the nominal group technique complemented by a scoping review. First, a designated coordinator selected a group of GPs members for the panel based on their experience and knowledge of psoriasis. The coordinator defined the objectives and key points for the document and, with the help of a documentalist, conducted a scoping review of articles in Medline, Embase, and the Cochrane Library up to January 2021. The review included systematic reviews and meta-analyses as well as clinical trials not included in those studies and high-quality real-world studies. National and international clinical practice guidelines and consensus documents on the management of moderate to severe psoriasis were also reviewed. The coordinator then drew up a set of proposed recommendations, which were discussed and modified in a nominal group meeting. After several review processes, including external review by other GPs members, the final document was drafted.

RESULTS

The present guidelines include updated recommendations on assessing the severity of psoriasis and criteria for the indication of systemic treatment. They also include general principles for the treatment of patients with moderate to severe psoriasis and define treatment goals for these patients as well as criteria for the indication and selection of initial and subsequent therapies Practical issues, such as treatment failure and maintenance of response, are also addressed.

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.

Liver damage promotes pro-inflammatory T-cell responses against apolipoprotein B-100

OBJECTIVES

Liver-derived apolipoprotein B-100 (ApoB100) is an autoantigen that is recognized by atherogenic CD4⁺ T cells in cardiovascular disease (CVD). CVD is a major mortality risk for patients with chronic inflammatory liver diseases. However, the impact of liver damage for ApoB100-specific T-cell responses is unknown.

METHODS

We identified ApoB100-specific T cells in blood from healthy controls, nonalcoholic fatty liver disease (NAFLD) patients, and CVD patients by activation-induced marker expression and analyzed their differentiation pattern in correlation to the lipid profile and liver damage parameters in a cross-sectional study. To assess the induction of extrahepatic ApoB100-specific T cells upon transient liver damage in vivo, we performed hydrodynamic tail vein injections with diphtheria toxin A (DTA)-encoding plasmid in human ApoB100-transgenic mice.

RESULTS

Utilizing immunodominant ApoB100-derived peptides, we found increased ApoB100-specific T-cell populations in NAFLD and CVD patients compared to healthy controls. In a peptide-specific manner, ApoB100 reactivity in healthy controls was accompanied by expression of the regulatory T (Treg)-cell transcription factor FOXP3. In contrast, FOXP3 expression decreased, whereas expression of pro-inflammatory cytokine interleukin (IL)-17A increased in ApoB100-specific T cells from NAFLD and CVD patients. Dyslipidemia and liver damage parameters in blood correlated with reduced FOXP3 expression and elevated IL-17A production in ApoB100-specific T-cell populations, respectively. Moreover, DTA-mediated transient liver damage in human ApoB100-transgenic mice accumulated IL-17a-expressing ApoB100-specific T cells in the periphery.

CONCLUSION

Our results show that liver damage promotes pro-inflammatory ApoB100-specific T-cell populations, thereby providing a cellular mechanism for the increased CVD risk in liver disease patients.

Psoriasis and Systemic Inflammatory Disorders

Psoriasis is a representative inflammatory skin disease occupied by large surface involvement. As inflammatory cells and cytokines can systemically circulate in various organs, it has been speculated that psoriatic skin inflammation influences the systemic dysfunction of various organs. Recent updates of clinical studies and experimental studies showed the important interaction of psoriasis to systemic inflammatory diseases. Furthermore, the importance of systemic therapy in severe psoriasis is also highlighted to prevent the development of systemic inflammatory diseases. In this review, we introduced representative systemic inflammatory diseases associated with psoriasis and the detailed molecular mechanisms.

Steroid-mediated liver steatosis is CD1d-dependent, while steroid-induced liver necrosis, inflammation, and metabolic changes are CD1d-independent

Introduction

Glucocorticoids contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Natural killer T cells play a role in the pathogenesis of NAFLD and response to steroids. The present study aimed to determine the role of CD1d in steroid-mediated metabolic derangement and the steroid-protective effect of glycosphingolipids.

Methods

Ten groups of mice were studied. Steroids were orally administered to C57BL/6 mice to assess the therapeutic effect of β-glucosylceramide (GC) on the development of steroid-mediated liver damage and metabolic derangements. The role of CD1d in the pathogenesis of steroid-induced liver damage and in mediating the hepatoprotective effect of GC was studied in CD1d^−/− mice.

Results

A model of oral administration of steroids was established, resulting in insulin resistance, hyperinsulinemia, hypertriglyceridemia, liver steatosis, and hepatocellular injury. Steroid administration to CD1d^−/− mice was associated with hyperglycemia and hypertriglyceridemia. However, CD1d^−/− mice did not manifest marked steroid-induced steatosis. GC treatment alleviated steroid-associated metabolic derangements and liver injury independent of CD1d expression.

Conclusion

A steroid-mediated model of NAFLD and metabolic derangements was established in which steroid-mediated steatosis was CD1d-dependent while steroid-induced liver necrosis, inflammation, and metabolic changes were CD1d-independent, which may support a dichotomy between steatosis and steatohepatitis in NAFLD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02242-9.

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.