The innate immune response during liver inflammation and metabolic disease

Jaceosidin attenuates the progression of hepatic fibrosis by inhibiting the VGLL3/HMGB1/TLR4 signaling pathway

BACKGROUND

Jaceosidin (JA) is a natural flavone extracted from Artemisia that is used as a food and traditional medicinal herb. It has been reported to possess numerous biological activities. However, the regulatory mechanisms underlying amelioration of hepatic fibrosis remain unclear.

HYPOTHESIS/PURPOSE

We hypothesized that jaceosidin acid (JA) modulates hepatic fibrosis and inflammation.

METHODS

Thioacetamide (TAA) was used to establish an HF mouse model. In vitro, mouse primary hepatocytes and HSC-T6 cells were induced by TGF-β, whereas mouse peritoneal macrophages received a treatment lipopolysaccharide (LPS)/ATP.

RESULTS

JA decreased serum transaminase levels and improved hepatic histological pathology in TAA-treated mice stimulated by TAA. Moreover, the expression of pro-fibrogenic biomarkers associated with the activation of liver stellate cells was downregulated by JA. Likewise, JA down-regulated the expression of vestigial-like family member 3 (VGLL3), high mobility group protein B1 (HMGB1), toll-like receptors 4 (TLR4), and nucleotide-binding domain-(NOD-) like receptor protein 3 (NLRP3), thereby inhibiting the inflammatory response and inhibiting the release of mature-IL-1β in TAA-stimulated mice. Additionally, JA suppressed HMGB1 release and NLRP3/ASC inflammasome activation in LPS/ATP-stimulated murine peritoneal macrophages. JA decreases the expression of pro-fibrogenic biomarkers related to liver stellate cell activation and inhibits inflammasome activation in mouse primary hepatocytes. It also down-regulated α-SMA and VGLL3 expressions and also suppressed inflammasome activation in HSC-T6 cells. VGLL3 and α-SMA expression levels were decreased in TGF-β-stimulated HSC-T6 cells following Vgll3 knockdown. In addition, the expression levels of NLRP3 and cleaved-caspase-1 were decreased in Vgll3-silenced HSC-T6 cells. JA enhanced the inhibitory effects on Vgll3-silenced HSC-T6 cells. Finally, Vgll3 overexpression in HSC-T6 cells affected the expression levels of α-SMA, NLRP3, and cleaved-caspase-1.

CONCLUSION

JA effectively modulates hepatic fibrosis by suppressing fibrogenesis and inflammation via the VGLL3/HMGB1/TLR4 axis. Therefore, JA may be a candidate therapeutic agent for the management of hepatic fibrosis. Understanding the mechanism of action of JA is a novel approach to hepatic fibrosis therapy.

Six-gene prognostic signature for non-alcoholic fatty liver disease susceptibility using machine learning

BACKGROUND

nonalcoholic fatty liver disease (NAFLD) is a common liver disease affecting the global population and its impact on human health will continue to increase. Genetic susceptibility is an important factor influencing its onset and progression, and there is a lack of reliable methods to predict the susceptibility of normal populations to NAFLD using appropriate genes.

METHODS

RNA sequencing data relating to nonalcoholic fatty liver disease was analyzed using the "limma" package within the R software. Differentially expressed genes were obtained through preliminary intersection screening. Core genes were analyzed and obtained by establishing and comparing 4 machine learning models, then a prediction model for NAFLD was constructed. The effectiveness of the model was then evaluated, and its applicability and reliability verified. Finally, we conducted further gene correlation analysis, analysis of biological function and analysis of immune infiltration.

RESULTS

By comparing 4 machine learning algorithms, we identified SVM as the optimal model, with the first 6 genes (CD247, S100A9, CSF3R, DIP2C, OXCT 2 and PRAMEF16) as predictive genes. The nomogram was found to have good reliability and effectiveness. Six genes' receiver operating characteristic curves (ROC) suggest an essential role in NAFLD pathogenesis, and they exhibit a high predictive value. Further analysis of immunology demonstrated that these 6 genes were closely connected to various immune cells and pathways.

CONCLUSION

This study has successfully constructed an advanced and reliable prediction model based on 6 diagnostic gene markers to predict the susceptibility of normal populations to NAFLD, while also providing insights for potential targeted therapies.

Veronica persica ameliorates acetaminophen-induced murine hepatotoxicity via attenuating oxidative stress and inflammation

Excess acetaminophen (APAP) commonly causes severe acute liver injury (ALI), characterized by oxidative stress, pro-inflammatory responses, and hepatocyte damage. Veronica persica (VP) is a traditional medicine with antioxidant and anti-inflammatory properties. There is a paucity of information on its medicinal value, especially its potential mechanisms for alleviating ALI. This study aimed to clarify the ameliorative effects and intracellular mechanisms of VP on APAP-induced ALI via attenuating oxidative stress and inflammation. Mice were given VP for 7 days before exposure to APAP (300 mg/kg). The HPLC and radical scavenging assay found that VP contains 12 phenolic acids and 6 flavonoids, as well as show robust antioxidant capacity. In the APAP-induced ALI model, pre-treatment with VP significantly reduces APAP-induced hepatotoxicity by observing improved hepatocyte pathological injury and further confirmed by serum biochemical indicator. Also, the reduction of TUNEL-positive regions and the regulation of Bcl-2-associated X protein indicated that VP attenuates hepatocytotoxicity. Moreover, VP pre-intervention inhibits the formation of liver pro-inflammatory cytokines, the expression of inflammatory response genes, and increases in myeloperoxidase (MPO) in APAP-exposed mice. The elevated reduced glutathione (GSH) levels and decreased oxidative stress markers indicate that VP reduces APAP-promoted oxidative stress. Further study revealed that VP inhibited the phosphorylation of NF-κB/STAT3 cascade, blocked ERK and JNK phosphorylation, and activated AMP-activated protein kinase (AMPK). To sum up, this study demonstrated that VP exists hepatoprotective abilities on APAP-induced ALI, primarily by suppressing the phosphorylation of NF-κB/STAT3 cascade and ERK-JNK and inducing AMPK activation to alleviate oxidative stress and inflammation.

Radiation and Immune Checkpoint Inhibitors: Combination Therapy for Treatment of Hepatocellular Carcinoma

The liver tumor immune microenvironment has been thought to possess a critical role in the development and progression of hepatocellular carcinoma (HCC). Despite the approval of immune checkpoint inhibitors (ICIs), such as programmed cell death receptor 1 (PD-1)/programmed cell death ligand 1 (PD-L1) and cytotoxic T lymphocyte associated protein 4 (CTLA-4) inhibitors, for several types of cancers, including HCC, liver metastases have shown evidence of resistance or poor response to immunotherapies. Radiation therapy (RT) has displayed evidence of immunosuppressive effects through the upregulation of immune checkpoint molecules post-treatment. However, it was revealed that the limitations of ICIs can be overcome through the use of RT, as it can reshape the liver immune microenvironment. Moreover, ICIs are able to overcome the RT-induced inhibitory signals, effectively restoring anti-tumor activity. Owing to the synergetic effect believed to arise from the combination of ICIs with RT, several clinical trials are currently ongoing to assess the efficacy and safety of this treatment for patients with HCC.

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.

Farnesoid X receptor: From Structure to Function and Its Pharmacology in Liver Fibrosis

The farnesoid X receptor (FXR), a ligand-activated transcription factor, plays a crucial role in regulating bile acid metabolism within the enterohepatic circulation. Beyond its involvement in metabolic disorders and immune imbalances affecting various tissues, FXR is implicated in microbiota modulation, gut- to-brain communication, and liver disease. The liver, as a pivotal metabolic and detoxification organ, is susceptible to damage from factors such as alcohol, viruses, drugs, and high-fat diets. Chronic or recurrent liver injury can culminate in liver fibrosis, which, if left untreated, may progress to cirrhosis and even liver cancer, posing significant health risks. However, therapeutic options for liver fibrosis remain limited in terms of FDA- approved drugs. Recent insights into the structure of FXR, coupled with animal and clinical investigations, have shed light on its potential pharmacological role in hepatic fibrosis. Progress has been achieved in both fundamental research and clinical applications. This review critically examines recent advancements in FXR research, highlighting challenges and potential mechanisms underlying its role in liver fibrosis treatment.

Lobeglitazone inhibits LPS-induced NLRP3 inflammasome activation and inflammation in the liver

Liver inflammation is a common feature of chronic liver disease and is often associated with increased exposure of the liver to lipopolysaccharide (LPS). Kupffer cells (KCs) are macrophages in the liver and produce various cytokines. Activation of KCs through the NLRP3 inflammasome pathway leads to release of proinflammatory cytokines and induces hepatocyte injury and hepatic stellate cell (HSC) activation. Lobeglitazone is a peroxisome proliferator-activated receptor gamma ligand and a type of thiazolidinedione that elicits anti-inflammatory effects. However, there is no clear evidence that it has direct anti-inflammatory effects in the liver. This study showed that lobeglitazone reduces LPS-induced NLPR3 inflammasome activation and production of proinflammatory cytokines in primary KCs and hepatocytes. Cytokines secreted by activated KCs increased hepatocyte inflammation and HSC activation, and lobeglitazone inhibited these responses. In addition, lobeglitazone suppressed liver fibrosis by inhibiting LPS-induced transforming growth factor (TGF)-β secretion and TGF-β-induced CTGF expression. The inhibitory effect of lobeglitazone on inflammasome activation was associated with suppression of liver fibrosis. These results suggest that lobeglitazone may be a treatment option for inflammation and fibrosis in the liver.

Cellular heterogeneity and plasticity during NAFLD progression

Nonalcoholic fatty liver disease (NAFLD) is a progressive liver disease that can progress to nonalcoholic steatohepatitis (NASH), NASH-related cirrhosis, and hepatocellular carcinoma (HCC). NAFLD ranges from simple steatosis (or nonalcoholic fatty liver [NAFL]) to NASH as a progressive form of NAFL, which is characterized by steatosis, lobular inflammation, and hepatocellular ballooning with or without fibrosis. Because of the complex pathophysiological mechanism and the heterogeneity of NAFLD, including its wide spectrum of clinical and histological characteristics, no specific therapeutic drugs have been approved for NAFLD. The heterogeneity of NAFLD is closely associated with cellular plasticity, which describes the ability of cells to acquire new identities or change their phenotypes in response to environmental stimuli. The liver consists of parenchymal cells including hepatocytes and cholangiocytes and nonparenchymal cells including Kupffer cells, hepatic stellate cells, and endothelial cells, all of which have specialized functions. This heterogeneous cell population has cellular plasticity to adapt to environmental changes. During NAFLD progression, these cells can exert diverse and complex responses at multiple levels following exposure to a variety of stimuli, including fatty acids, inflammation, and oxidative stress. Therefore, this review provides insights into NAFLD heterogeneity by addressing the cellular plasticity and metabolic adaptation of hepatocytes, cholangiocytes, hepatic stellate cells, and Kupffer cells during NAFLD progression.

Scavenger receptor a is a major homeostatic regulator that restrains drug-induced liver injury

BACKGROUND AND AIM

Drug-induced liver injury occurs frequently and can be life threatening. Although drug-induced liver injury is mainly caused by the direct drug cytotoxicity, increasing evidence suggests that the interplay between hepatocytes and immune cells can define this pathogenic process. Here, we interrogate the role of the pattern recognition scavenger receptor A (SRA) for regulating hepatic inflammation and drug-induced liver injury.

APPROACH AND RESULTS

Using acetaminophen (APAP) or halothane-induced liver injury models, we showed that SRA loss renders mice highly susceptible to drug hepatotoxicity, indicated by the increased mortality and liver pathology. Mechanistic studies revealed that APAP-induced liver injury exaggerated in the absence of SRA was associated with the decreased anti-inflammatory and prosurvival cytokine IL-10 concomitant with excessive hepatic inflammation. The similar correlation between SRA and IL-10 expression was also seen in human following APAP uptake. Bone marrow reconstitution and liposomal clodronate depletion studies established that the hepatoprotective activity of SRA mostly resized in the immune sentinel KCs. Furthermore, SRA-facilitated IL-10 production by KCs in response to injured hepatocytes mitigated activation of the Jun N-terminal kinase-mediated signaling pathway in hepatocytes. In addition, supplemental use of IL-10 with N -acetylcysteine, only approved treatment of APAP overdose, conferred mice improved protection from APAP-induced liver injury.

CONCLUSION

We identify a novel hepatocyte-extrinsic pathway governed by the immune receptor SRA that maintains liver homeostasis upon drug insult. Giving that drug (ie, APAP) overdose is the leading cause of acute liver failure, targeting this hepatoprotective SRA-IL-10 axis may provide new opportunities to optimize the current management of drug-induced liver injury.

Probiotics, prebiotics, and synbiotics in nonalcoholic fatty liver disease and alcohol-associated liver disease

The use of probiotics, prebiotics, and synbiotics has become an important therapy in numerous gastrointestinal diseases in recent years. Modifying the gut microbiota, this therapeutic approach helps to restore a healthy microbiome. Nonalcoholic fatty liver disease and alcohol-associated liver disease are among the leading causes of chronic liver disease worldwide. A disrupted intestinal barrier, microbial translocation, and an altered gut microbiome metabolism, or metabolome, are crucial in the pathogenesis of these chronic liver diseases. As pro-, pre-, and synbiotics modulate these targets, they were identified as possible new treatment options for liver disease. In this review, we highlight the current findings on clinical and mechanistic effects of this therapeutic approach in nonalcoholic fatty liver disease and alcohol-associated liver disease.

Nutraceutical approaches to non-alcoholic fatty liver disease (NAFLD): A position paper from the International Lipid Expert Panel (ILEP)

Non-Alcoholic Fatty Liver Disease (NAFLD) is a common condition affecting around 10-25% of the general adult population, 15% of children, and even > 50% of individuals who have type 2 diabetes mellitus. It is a major cause of liver-related morbidity, and cardiovascular (CV) mortality is a common cause of death. In addition to being the initial step of irreversible alterations of the liver parenchyma causing cirrhosis, about 1/6 of those who develop NASH are at risk also developing CV disease (CVD). More recently the acronym MAFLD (Metabolic Associated Fatty Liver Disease) has been preferred by many European and US specialists, providing a clearer message on the metabolic etiology of the disease. The suggestions for the management of NAFLD are like those recommended by guidelines for CVD prevention. In this context, the general approach is to prescribe physical activity and dietary changes the effect weight loss. Lifestyle change in the NAFLD patient has been supplemented in some by the use of nutraceuticals, but the evidence based for these remains uncertain. The aim of this Position Paper was to summarize the clinical evidence relating to the effect of nutraceuticals on NAFLD-related parameters. Our reading of the data is that whilst many nutraceuticals have been studied in relation to NAFLD, none have sufficient evidence to recommend their routine use; robust trials are required to appropriately address efficacy and safety.

Comparison of the efficacy of the mouse hepatic and renal antioxidant systems against inflammation-induced oxidative stress

This study was conducted to compare the efficacy of the mouse hepatic and renal antioxidant systems against inflammation-induced oxidative stress. Increased Il-1 and Il-6 expressions, markers of inflammation, were represented by inflammation models in mouse liver and kidney tissues injected intraperitoneally with LPS. After establishing the model, the GSH level and the GSH/GSSG ratio, which are oxidative stress markers, were investigated in both tissues treated with LPS and the control group. The expression of Trx1, TrxR, and Txnip genes increased in the liver tissues of LPS-treated mice. In the kidney tissue, while Trx1 expression decreased, no change was observed in TrxR1 expression, and Txnip expression increased. In the kidneys, TRXR1 and GR activities decreased, whereas GPx activity increased. In both tissues, the TRXR1 protein expression decreased significantly, while TXNIP expression increased. In conclusion, different behaviors of antioxidant system members were observed during acute inflammation in both tissues. Additionally, it can be said that the kidney tissue is more sensitive and takes earlier measures than the liver tissue against cellular damage caused by inflammation and inflammation-induced oxidative stress.

Identification of novel biomarkers involved in doxorubicin-induced acute and chronic cardiotoxicity, respectively, by integrated bioinformatics

Background

The mechanisms of doxorubicin (DOX) cardiotoxicity were complex and controversial, with various contradictions between experimental and clinical data. Understanding the differences in the molecular mechanism between DOX-induced acute and chronic cardiotoxicity may be an ideal entry point to solve this dilemma.

Methods

Mice were injected intraperitoneally with DOX [(20 mg/kg, once) or (5 mg/kg/week, three times)] to construct acute and chronic cardiotoxicity models, respectively. Survival record and ultrasound monitored the cardiac function. The corresponding left ventricular (LV) myocardium tissues were analyzed by RNA-seq to identify differentially expressed genes (DEGs). Gene Ontology (GO), Kyoto Encyclopedia of Gene and Genome (KEGG), and Gene Set Enrichment Analysis (GSEA) found the key biological processes and signaling pathways. DOX cardiotoxicity datasets from the Gene expression omnibus (GEO) database were combined with RNA-seq to identify the common genes. Cytoscape analyzed the hub genes, which were validated by quantitative real-time PCR. ImmuCo and ImmGen databases analyzed the correlations between hub genes and immunity-relative markers in immune cells. Cibersort analyzed the immune infiltration and correlations between the hub genes and the immune cells. Logistic regression, receiver operator characteristic curve, and artificial neural network analysis evaluated the diagnosis ability of hub genes for clinical data in the GEO dataset.

Results

The survival curves and ultrasound monitoring demonstrated that cardiotoxicity models were constructed successfully. In the acute model, 788 DEGs were enriched in the activated metabolism and the suppressed immunity-associated signaling pathways. Three hub genes (Alas1, Atp5g1, and Ptgds) were upregulated and were negatively correlated with a colony of immune-activating cells. However, in the chronic model, 281 DEGs showed that G protein-coupled receptor (GPCR)-related signaling pathways were the critical events. Three hub genes (Hsph1, Abcb1a, and Vegfa) were increased in the chronic model. Furthermore, Hsph1 combined with Vegfa was positively correlated with dilated cardiomyopathy (DCM)-induced heart failure (HF) and had high accuracy in the diagnosis of DCM-induced HF (AUC = 0.898, P = 0.000).

Conclusion

Alas1, Atp5g1, and Ptgds were ideal biomarkers in DOX acute cardiotoxicity. However, Hsph1 and Vegfa were potential biomarkers in the myocardium in the chronic model. Our research, first, provided bioinformatics and clinical evidence for the discovery of the differences in mechanism and potential biomarkers of DOX-induced acute and chronic cardiotoxicity to find a therapeutic strategy precisely.

Oral supplementation of a cell preparation of Enterococcus faecalis strain EC-12 stimulates superoxide dismutase production in the livers of healthy and arthritis-induced mice

Hepatitis, a major human chronic inflammation disease, has been linked to oxidative stress, which can be initiated by radicals produced during the oxidative metabolism. Oxidative damage has been also observed in arthritis-induced mice. Here we evaluated whether supplementation of a cell preparation of Enterococcus faecalis EC-12 could induce superoxide dismutase activity and/or damage in the livers of healthy mice or mice with arthritis. In Experiment 1, both healthy and arthritis-induced mice were orally given a saline solution, or a solution with a low (0.2 mg/mouse/day) or a high (2.0 mg/mouse/day) concentration of E. faecalis EC-12 for 49 consecutive days. Manganese superoxide dismutase activity increased in E. faecalis EC-12-supplemented mice but with no arthritis. In Experiment 2, mice received orally either a saline or an E. faecalis EC-12 suspension (10 mg/kg of body weight/day) for 28 consecutive days. No changes in tissues and levels of function markers and 8-hydroxy-2'-deoxyguanosine were observed in mouse livers, inferring that E. faecalis EC-12 supplementation caused no damage. While mRNA expression of copper/zinc superoxide dismutase remained unaltered, that of manganese superoxide dismutase increased in E. faecalis EC-12 administration mice. In conclusion, at least in healthy mice, E. faecalis EC-12 supplementation stimulated manganese superoxide dismutase activity in liver tissues with no side effects.

Pattern recognition receptor signaling and innate immune responses to schistosome infection

Schistosomiasis remains to be a significant public health problem in tropical and subtropical regions. Despite remarkable progress that has been made in the control of the disease over the past decades, its elimination remains a daunting challenge in many countries. This disease is an inflammatory response-driven, and the positive outcome after infection depends on the regulation of immune responses that efficiently clear worms and allow protective immunity to develop. The innate immune responses play a critical role in host defense against schistosome infection and pathogenesis. Initial pro-inflammatory responses are essential for clearing invading parasites by promoting appropriate cell-mediated and humoral immunity. However, elevated and prolonged inflammatory responses against the eggs trapped in the host tissues contribute to disease progression. A better understanding of the molecular mechanisms of innate immune responses is important for developing effective therapies and vaccines. Here, we update the recent advances in the definitive host innate immune response to schistosome infection, especially highlighting the critical roles of pattern recognition receptors and cytokines. The considerations for further research are also provided.

Targeting the lung epithelium after intravenous delivery by directed evolution of underexplored sites on the AAV capsid

Advances in adeno-associated virus (AAV) engineering have provided exciting new tools for research and potential solutions for gene therapy. However, the lung has not received the same tailored engineering as other major targets of debilitating genetic disorders. To address this, here we engineered the surface-exposed residues AA452-458 of AAV9 capsid proteins at the three-fold axis of symmetry and employed a Cre-transgenic-based screening platform to identify AAV capsids targeted to the lung after intravenous delivery in mice. Using a custom image processing pipeline to quantify transgene expression across whole tissue images, we found that one engineered variant, AAV9.452sub.LUNG1, displays dramatically improved transgene expression in lung tissue after systemic delivery in mice. This improved transduction extends to alveolar epithelial type II cells, expanding the toolbox for gene therapy research for diseases specific to the lung.

Pathogenesis from Inflammation to Cancer in NASH-Derived HCC

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and one of the deadliest cancers worldwide. As opposed to the majority of patients with HCC, approximately 20–30% of cases of non-alcoholic steatohepatitis (NASH)-derived HCC develop malignant tumours in the absence of liver cirrhosis. NASH is characterized by metabolic dysregulation, chronic inflammation and cell death in the liver, which provide a favorable setting for the transformation of inflammation into cancer. This review aims to describe the pathogenesis and the underlying mechanism of the transition from inflammation to cancer in NASH.

The unique role of innate lymphoid cells in cancer and the hepatic microenvironment

Cancer is a complex disease, and despite incredible progress over the last decade, it remains the leading cause of death worldwide. Liver cancers, including hepatocellular carcinoma (HCC), and liver metastases are distinct from other cancers in that they typically emerge as a consequence of long-term low-grade inflammation. Understanding the mechanisms that underpin inflammation-driven tissue remodeling of the hepatic immune environment is likely to provide new insights into much needed treatments for this devastating disease. Group 1 innate lymphoid cells (ILCs), which include natural killer (NK) cells and ILC1s, are particularly enriched in the liver and thought to contribute to the pathogenesis of a number of liver diseases, including cancer. NK cells are an attractive, but underexplored, therapeutic target in hepatic disease due to their role in immunosurveillance and their ability to recognize and eliminate malignant cells. ILC1s are closely related to and share many phenotypic features with NK cells but are less well studied. Thus, their utility in immunotherapeutic approaches is not yet well understood. Here, we review our current understanding of ILCs in cancer with a particular focus on liver and liver-related diseases.

Hepatoprotective Polysaccharides from Geranium wilfordii: Purification, Structural Characterization, and Their Mechanism

Traditional Chinese Medicine is generally used as a decoction to guard health. Many active ingredients in the decoction are chemical ingredients that are not usually paid attention to in phytochemical research, such as polysaccharides, etc. Based on research interest in Chinese herbal decoction, crude polysaccharides from G. wilfordii (GCP) were purified to obtain two relatively homogeneous polysaccharides, a neutral polysaccharide (GNP), and an acid polysaccharide (GAP) by various chromatographic separation methods, which were initially characterized by GC-MS, NMR, IR, and methylation analysis. Studies on the hepatoprotective activity of GCP in vivo showed that GCP might be a potential agent for the prevention and treatment of acute liver injury by inhibiting the secretion levels of ALT, AST, IL-6, IL-1β, TNF-α, and MDA expression levels, increasing SOD, and the GSH-Px activity value. Further, in vitro assays, GNP and GAP, decrease the inflammatory response by inhibiting the secretion of IL-6 and TNF-α, involved in the STAT1/T-bet signaling pathway.

Smad3 Phospho-Isoform Signaling in Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis with insulin resistance, oxidative stress, lipotoxicity, adipokine secretion by fat cells, endotoxins (lipopolysaccharides) released by gut microbiota, and endoplasmic reticulum stress. Together, these factors promote NAFLD progression from steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, and eventually end-stage liver diseases in a proportion of cases. Hepatic fibrosis and carcinogenesis often progress together, sharing inflammatory pathways. However, NASH can lead to hepatocarcinogenesis with minimal inflammation or fibrosis. In such instances, insulin resistance, oxidative stress, and lipotoxicity can directly lead to liver carcinogenesis through genetic and epigenetic alterations. Transforming growth factor (TGF)-β signaling is implicated in hepatic fibrogenesis and carcinogenesis. TGF-β type I receptor (TβRI) and activated-Ras/c-Jun-N-terminal kinase (JNK) differentially phosphorylate the mediator Smad3 to create two phospho-isoforms: C-terminally phosphorylated Smad3 (pSmad3C) and linker-phosphorylated Smad3 (pSmad3L). TβRI/pSmad3C signaling terminates cell proliferation, while constitutive Ras activation and JNK-mediated pSmad3L promote hepatocyte proliferation and carcinogenesis. The pSmad3L signaling pathway also antagonizes cytostatic pSmad3C signaling. This review addresses TGF-β/Smad signaling in hepatic carcinogenesis complicating NASH. We also discuss Smad phospho-isoforms as biomarkers predicting HCC in NASH patients with or without cirrhosis.

The transmembrane adapter SCIMP recruits tyrosine kinase Syk to phosphorylate Toll-like receptors to mediate selective inflammatory outputs

Innate immune signaling by Toll-like receptors (TLRs) involves receptor phosphorylation, which helps to shape and drive key inflammatory outputs, yet our understanding of the kinases and mechanisms that mediate TLR phosphorylation is incomplete. Spleen tyrosine kinase (Syk) is a nonreceptor protein tyrosine kinase, which is known to relay adaptive and innate immune signaling, including from TLRs. However, TLRs do not contain the conserved dual immunoreceptor tyrosine-based activation motifs that typically recruit Syk to many other receptors. One possibility is that the Syk-TLR association is indirect, relying on an intermediary scaffolding protein. We previously identified a role for the palmitoylated transmembrane adapter protein SCIMP in scaffolding the Src tyrosine kinase Lyn, for TLR phosphorylation, but the role of SCIMP in mediating the interaction between Syk and TLRs has not yet been investigated. Here, we show that SCIMP recruits Syk in response to lipopolysaccharide-mediated TLR4 activation. We also show that Syk contributes to the phosphorylation of SCIMP and TLR4 to enhance their binding. Further evidence pinpoints two specific phosphorylation sites in SCIMP critical for its interaction with Syk-SH2 domains in the absence of immunoreceptor tyrosine-based activation motifs. Finally, using inhibitors and primary macrophages from SCIMP^-/- mice, we confirm a functional role for SCIMP-mediated Syk interaction in modulating TLR4 phosphorylation, signaling, and cytokine outputs. In conclusion, we identify SCIMP as a novel, immune-specific Syk scaffold, which can contribute to inflammation through selective TLR-driven inflammatory responses.

Anti-aging effect of phlorizin on D-galactose-induced aging in mice through antioxidant and anti-inflammatory activity, prevention of apoptosis, and regulation of the gut microbiota

Aging is an inevitable and complicated process involving many physiological changes. Screening of natural biologically active anti-aging substances is a current research hotspot. Phlorizin (PZ), an important dihydrochalcone phytoconstituent, has been demonstrated to have antioxidant and anti-tumor effects. In this paper, different doses of PZ (20 and 40 mg/kg) were used to research the protective effect on D-galactose (D-gal)-induced aging mice. Following hematoxylin and eosin staining and by observing the hippocampus, we found that PZ alleviated the damage caused by D-gal in neuronal cells, while PZ enhanced the learning and memory abilities of aging mice in a radical eight-arm maze. In order to explain the reasons for these anti-aging effects, we tested the antioxidant enzyme activity and malonic dialdehyde concentration in mouse serum, liver, and brain tissue. The contents of proteins related to anti-inflammation and apoptosis in brain tissue were analyzed, and the gut microbiota was also analyzed. The results indicated that PZ improved antioxidant enzyme activity while significantly reducing the malonic dialdehyde content. Western blotting analysis suggested that PZ effectively alleviated neuro-apoptosis via regulating the expressions of Bax, Bcl-2, and caspase-3. PZ also exerted anti-inflammation effects by regulating the interleukin-1β/inhibitor of nuclear factor kappa B alpha/nuclear factor kappa-light-chain-enhancer of activated B-cells signaling pathways in brain tissues. Importantly, PZ improved the structure and diversity of the gut microbiota, and the microbiota-gut-brain axis may hold a key role in PZ-induced anti-aging effects. In conclusion, PZ can be used as a potential drug candidate to combat aging.

Pathophysiological Role of Purinergic P2X Receptors in Digestive System Diseases

P2X receptors (P2XRs) are trimeric, non-selective cation channels activated by extracellular ATP and widely distributed in the digestive system. P2XRs have an important role in the physiological function of the digestive system, such as neurotransmission, ion transports, proliferation and apoptosis, muscle contraction, and relaxation. P2XRs can be involved in pain mechanisms both centrally and in the periphery and confirmed the association of P2XRs with visceral pain. In the periphery, ATP can be released as a result of tissue injury, visceral distension, or sympathetic activation and can excite nociceptive primary afferents by acting at homomeric P2X(3)R or heteromeric P2X(2/3)R. Thus, peripheral P2XRs, and homomeric P2X(3) and/or heteromeric P2X(2/3)R in particular, constitute attractive targets for analgesic drugs. Recently studies have shown that P2XRs have made significant advances in inflammation and cancer. P2X7R mediates NLRP3 inflammasome activation, cytokine and chemokine release, T lymphocyte survival and differentiation, transcription factor activation, and cell death. The P2X7R is a potent stimulant of inflammation and immunity and a promoter of cancer cell growth. This makes P2X7R an appealing target for anti-inflammatory and anti-cancer therapy. It is believed that with the further study of P2XRs and its subtypes, P2XRs and its specific antagonists will be expected to be widely used in the treatment of human digestive diseases in the future.

Inflammatory arthritis increases the susceptibility to acute immune-mediated hepatitis in mice through enhancing leptin expression in T cells

Liver function abnormalities are common in patients with inflammatory arthritis. However, the precise mechanism is still unclear. In this study, inflammatory arthritis was established in mice by subcutaneous injection of complete Freund's adjuvant, and the intravenous injection of concanavalin A (Con A) was employed to induce acute immune-mediated hepatitis in mice. The result showed that the arthritis mice were more susceptible to ConA-induced hepatitis than the control mice, as evidenced by increased hepatic necrosis, elevated serum alanine aminotransferase activity, and raised inflammatory cytokines. Besides, the in vitro assay demonstrated that the T cells from arthritis mice were more sensitive to the Con A stimulation than those from control mice. Moreover, we determined that the level of leptin, a kind of adipokine, was significantly increased in the serum and hepatic T cells of arthritis mice. Interestingly, the data indicated that the enhanced expression of leptin in hepatic T cells is responsible for the hypersensitivity of arthritis mice-derived T cells to Con A challenge. Collectively, our findings demonstrate an unexpected role of leptin in the connection between inflammatory arthritis and acute immune-mediated hepatitis, thus providing new insight into the clinical therapy of arthritis-related liver dysfunction.

The effects of guluronic acid (G2013), a new emerging treatment, on inflammatory factors in nonalcoholic steatohepatitis patients under in vitro conditions

BACKGROUND

Nonalcoholic Steatohepatitis (NASH) results from the accumulation of fatty acids in the liver. The elevated production of pro-inflammatory factors is the reason for the hyper inflammation in NASH. The α-L-Guluronic acid (G2013), a new member of NSAID family, is a plant-originated agent with immunomodulatory properties. The current study investigated the effects of G2013 on inflammatory factors in PBMCs of NASH patients.

METHODS

PBMCs of 14 NASH patients and 14 healthy controls were isolated and cultured. The patient's cells were treated with low (5 µg/mL) and moderate (25 µg/mL) doses of G2013 alongside the diclofenac optimum dose (3 µg/mL). The expression and secretion levels of variables were assessed by real-time PCR and ELISA, respectively.

RESULTS

Findings indicated that the expression levels of TLR4 and NF-κB, as well as the secretion levels of TNF-α and IL-6 cytokines, were significantly elevated in NASH patients compared to healthy individuals. The expression levels of TLR4 and NF-κB were strikingly downregulated in treated cells of patients in both low and moderate doses of G2013. A considerable reduction was obtained in the secretion level of IL-6 using both low and moderate doses of G2013 and in the secretion level of TNF-α using the moderate dose of G2013.

CONCLUSION

The results indicated that G2013 could meaningfully decrease the expression and secretion levels of evaluated factors (TLR4, NF-κB, TNF-α, and IL-6) in PMBCs of NASH cases. Since there is no effective treatment for NASH patients, we hope that G2013 would be a promising immunomodulatory agent in reducing inflammation and improvement of patients.

The role of cGAS-STING signalling in liver diseases

The recently identified novel cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) activates the downstream adaptor protein stimulator of interferon genes (STING) by catalysing the synthesis of cyclic GMP-AMP. This in turn initiates an innate immune response through the release of various cytokines, including type I interferon. Foreign DNA (microbial infection) or endogenous DNA (nuclear or mitochondrial leakage) can serve as cGAS ligands and lead to the activation of cGAS-STING signalling. Therefore, the cGAS-STING pathway plays essential roles in infectious diseases, sterile inflammation, tumours, and autoimmune diseases. In addition, cGAS-STING signalling affects the progression of liver inflammation through other mechanisms, such as autophagy and metabolism. In this review, we summarise recent advances in our understanding of the role of cGAS-STING signalling in the innate immune modulation of different liver diseases. Furthermore, we discuss the therapeutic potential of targeting the cGAS-STING pathway in the treatment of liver diseases.

Nonalcoholic Fatty Liver Disease (NAFLD) as Model of Gut-Liver Axis Interaction: From Pathophysiology to Potential Target of Treatment for Personalized Therapy

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of liver disease worldwide, affecting both adults and children and will result, in the near future, as the leading cause of end-stage liver disease. Indeed, its prevalence is rapidly increasing, and NAFLD is becoming a major public health concern. For this reason, great efforts are needed to identify its pathogenetic factors and new therapeutic approaches. In the past decade, enormous advances understanding the gut-liver axis-the complex network of cross-talking between the gut, microbiome and liver through the portal circulation-have elucidated its role as one of the main actors in the pathogenesis of NAFLD. Indeed, evidence shows that gut microbiota is involved in the development and progression of liver steatosis, inflammation and fibrosis seen in the context of NAFLD, as well as in the process of hepatocarcinogenesis. As a result, gut microbiota is currently emerging as a non-invasive biomarker for the diagnosis of disease and for the assessment of its severity. Additionally, to its enormous diagnostic potential, gut microbiota is currently studied as a therapeutic target in NAFLD: several different approaches targeting the gut homeostasis such as antibiotics, prebiotics, probiotics, symbiotics, adsorbents, bariatric surgery and fecal microbiota transplantation are emerging as promising therapeutic options.

Inflammatory processes in the liver: divergent roles in homeostasis and pathology

The hepatic immune system is designed to tolerate diverse harmless foreign moieties to maintain homeostasis in the healthy liver. Constant priming and regulation ensure that appropriate immune activation occurs when challenged by pathogens and tissue damage. Failure to accurately discriminate, regulate, or effectively resolve inflammation offsets this balance, jeopardizing overall tissue health resulting from an either  overly tolerant or an overactive inflammatory response. Compelling scientific and clinical evidence links dysregulated hepatic immune and inflammatory responses upon sterile injury to several pathological conditions in the liver, particularly nonalcoholic steatohepatitis and ischemia-reperfusion injury. Murine and human studies have described interactions between diverse immune repertoires and nonhematopoietic cell populations in both physiological and pathological activities in the liver, although the molecular mechanisms driving these associations are not clearly understood. Here, we review the dynamic roles of inflammatory mediators in responses to sterile injury in the context of homeostasis and disease, the clinical implications of dysregulated hepatic immune activity and therapeutic developments to regulate liver-specific immunity.

Bidirectional Role of NLRP3 During Acute and Chronic Cholestatic Liver Injury

BACKGROUND AND AIMS

Cholestatic liver injury leads to cell death and subsequent inflammation and fibrosis. As shown for primary biliary cholangitis (PBC), the mechanisms and circuits between different cell death pathways leading to disease progression are incompletely defined. Common bile duct ligation (BDL) is a well-established murine model to mimic cholestatic liver injury. Here, we hypothesized that pyroptotic cell death by the Nucleotide-Binding Domain, Leucine-Rich-Containing Family, Pyrin Domain-Containing-3 (Nlrp3) inflammasome plays an essential role during human and murine cholestasis.

APPROACH AND RESULTS

NLRP3 activation was analyzed in humans with cholestatic liver injury. Wild-type (WT) and Nlrp3^-/- mice were subjected to BDL for 2 or 28 days. Chronic cholestasis in humans and mice is associated with NLRP3 activation and correlates with disease activity. Acute BDL in Nlrp3-deficient mice triggered increased inflammation as well as liver injury, associated with stronger apoptotic and necroptotic cell death. In contrast, NLRP3 deletion led to decreased liver injury and inflammation in chronic cholestasis. Moreover, bridging fibrosis was observed in WT, but not in NLRP3 knockout, mice 28 days after BDL. In contrast, lack of NLRP3 expression attenuated kidney injury and fibrosis after acute and chronic BDL. Importantly, administration of MCC950, an NLRP3 small molecule inhibitor, reduced BDL-induced disease progression in WT mice.

CONCLUSIONS

NLRP3 activation correlates with disease activity in patients with PBC. NLRP3 has a differential role during acute and chronic cholestatic liver injury in contrast to kidney injury. Disease progression during chronic cholestasis can be targeted through small molecules and thus suggests a potential clinical benefit for humans, attenuating liver and kidney injury.

Liver Resection Promotes (Regulates) Proinflammatory Cytokines in Patients with Hepatocellular Carcinoma

BACKGROUND

Several animal studies have shown the roles of cytokines in regulating liver regeneration following liver resection (LR), which is a type of surgery designed to remove cancerous tumors from the liver. This study investigated how the expressions and serum levels of some pro- and anti-inflammatory cytokines in patients with hepatocellular carcinoma (HCC) were changed during LR.

METHODS

Liver tissues from 15 patients with HCC were collected and the levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), IL-1α, IL-1 β, IL-10, and transforming growth factor-beta1 (TGF-β1) were assessed using real-time PCR assay at different times before and after LR. The serum values of TNF-α and IL-6 were also measured by ELISA.

RESULTS

After 60 and 90 minutes of LR, IL-6 gene expression was significantly increased (P < 0.001 - 0.05). The same trend was also observed in TNF-α expression after 90 minutes of LR (P < 0.01). No significant changes were observed in the expressions of IL-1α, IL-1β, IL-10, and TGF-β1 before and after LR. In addition, LR had significant effects on TNF-α and IL-6 serum levels (P < 0.05 - 0.0001).

CONCLUSION

Our data provided further evidence to reveal that IL-6 and TNF-α cytokines are critical to improve liver regeneration.

Mechanism and Basis of Traditional Chinese Medicine Against Obesity: Prevention and Treatment Strategies

In the last few decades, the incidences of obesity and related metabolic disorders worldwide have increased dramatically. Major pathophysiology of obesity is termed "lipotoxicity" in modern western medicine (MWM) or "dampness-heat" in traditional Chinese medicine (TCM). "Dampness-heat" is a very common and critically important syndrome to guild clinical treatment in TCM. However, the pathogenesis of obesity in TCM is not fully clarified, especially by MWM theories compared to TCM. In this review, the mechanism underlying the action of TCM in the treatment of obesity and related metabolic disorders was thoroughly discussed, and prevention and treatment strategies were proposed accordingly. Hypoxia and inflammation caused by lipotoxicity exist in obesity and are key pathophysiological characteristics of "dampness-heat" syndrome in TCM. "Dampness-heat" is prevalent in chronic low-grade systemic inflammation, prone to insulin resistance (IR), and causes variant metabolic disorders. In particular, the MWM theories of hypoxia and inflammation were applied to explain the "dampness-heat" syndrome of TCM, and we summarized and proposed the pathological path of obesity: lipotoxicity, hypoxia or chronic low-grade inflammation, IR, and metabolic disorders. This provides significant enrichment to the scientific connotation of TCM theories and promotes the modernization of TCM.

Ameliorative potentials of Persea americana leaf extract on toxicants - induced oxidative assault in multiple organs of wistar albino rat

Background

Persea americana (PA) is a popular medicinal plant in folkloric medicines. The present study therefore investigates the ameliorative potentials of its leaves extract on carbon tetrachloride and rifampicin-induced toxicity in the liver, kidney and heart of albino rat. This was aimed at assessing the potentials of the plant in the management of liver, kidney and heart diseases.

Methodology

Forty (40) rats were randomly divided into eight (8) groups of five animals each. Groups I and II were administered with only distilled water and carbon tetrachloride (CCl4) respectively. Groups III and IV animals received 3.0 ml/kg bw of CCl4 and were treated with the extract at 50 mg/kg bw and 100 mg/kg respectively, while group V received 100 mg/kg bw. of silymarin orally for 14 days. Groups VI animals were administered with rifampicin (250 mg/kg bw.) only, while groups VII and VIII animals received rifampicin and were treated with 50 mg and 100 mg/kg bw of the extract respectively. Activities of creatine kinase, aspartate amino transferase, alanine amino transferase, alkaline phosphatase, superoxide dismutase, catalase as well as levels of urea, uric acid, bilirubin and malonidialdehyde (MDA) were assayed. Lipid profiles and histopathological examination of liver and kidney slices were also performed.

Result

Treatment with P. americana significantly (p < 0.05) restored all deranged biochemical parameters (creatine kinase, aspartate amino transferase, alanine amino transferase, alkaline phosphatase, urea, uric acid, bilirubin, MDA, lipid profile as well as superoxide dismutase and catalase) in a dose-dependent manner. Normal hepatic and renal histoarchitecture were also restored following treatment with P. americana.

Conclusion

Amelioration of distorted cardiac, hepatic and renal histoarchitecture as well as restoration of lipid profile, biomarkers of liver and kidney injury and antioxidant enzymes (catalase and superoxide dismutase) affirm the potential usefulness of P. americana in the management of liver, kidney and heart diseases.

Trem-2 Promotes Emergence of Restorative Macrophages and Endothelial Cells During Recovery From Hepatic Tissue Damage

Macrophages are pivotal in mounting liver inflammatory and tissue repair responses upon hepatic injury, showing remarkable functional plasticity. The molecular mechanisms determining macrophage transition from inflammatory to restorative phenotypes in the damaged liver remain unclear. Using mouse models of acute (APAP) and chronic (CCl4) drug-induced hepatotoxic injury we show that the immune receptor Trem-2 controls phenotypic shifts of liver macrophages and impacts endothelial cell differentiation during tissue recovery. Trem-2 gene ablation led to a delayed re-population of Kupffer cells correlating with deterred resolution of hepatic damage following acute and chronic injury. During tissue recovery, we found that macrophages transitioning to Kupffer cells expressed high levels of Trem-2. Acquisition of the transition phenotype was associated with a unique transcriptomic profile denoting strong responsiveness to oxidative stress and downmodulation of the pro-inflammatory phenotype, which was not observed in absence of Trem-2. During tissue recovery, lack of Trem-2 favored accumulation of a liver-damage associated endothelial cell population (LDECs), whose transcriptional program was compatible with endothelial de-differentiation. Accordingly, LDECs precursor potential is supported by the downregulation of surface endothelial cell markers and by striking in vitro morphological changes towards typical endothelial cells. In conclusion, we found that the dynamics of liver macrophages in response to liver injury are critically controlled by Trem-2 and this regulation is interlinked with the de-differentiation of endothelial cells and heightened liver pathology. We propose that Trem-2 promotes the transition from pro-inflammatory to tissue repair phase by driving the acquisition of restorative properties in phagocytic macrophages.

Myeloid Krüppel-like factor 2 is a critical regulator of metabolic inflammation

Substantial evidence implicates crosstalk between metabolic tissues and the immune system in the inception and progression of obesity. However, molecular regulators that orchestrate metaflammation both centrally and peripherally remains incompletely understood. Here, we identify myeloid Krüppel-like factor 2 (KLF2) as an essential regulator of obesity and its sequelae. In mice and humans, consumption of a fatty diet downregulates myeloid KLF2 levels. Under basal conditions, myeloid-specific KLF2 knockout mice (K2KO) exhibit increased feeding and weight gain. High-fat diet (HFD) feeding further exacerbates the K2KO metabolic disease phenotype. Mechanistically, loss of myeloid KLF2 increases metaflammation in peripheral and central tissues. A combination of pair-feeding, bone marrow-transplant, and microglial ablation implicate central and peripheral contributions to K2KO-induced metabolic dysfunction observed. Finally, overexpression of myeloid KLF2 protects mice from HFD-induced obesity and insulin resistance. Together, these data establish myeloid KLF2 as a nodal regulator of central and peripheral metabolic inflammation in homeostasis and disease.

Inflammation contributes to the development of metabolic disease through incompletely understood mechanisms. Here the authors report that deletion of the transcription factor KLF2 in myeloid cells leads to increased feeding and weight gain in mice with concomitant peripheral and central tissue inflammation, while overexpression protects against diet-induced metabolic disease.

Icariside Ⅱ, a main compound in Epimedii Folium, induces idiosyncratic hepatotoxicity by enhancing NLRP3 inflammasome activation

Idiosyncratic drug-induced liver injury (IDILI) is an infrequent but potentially serious disease that develops the main reason for post-marketing safety warnings and withdrawals of drugs. Epimedii Folium (EF), the widely used herbal medicine, has shown to cause idiosyncratic liver injury, but the underlying mechanisms are poorly understood. Increasing evidence has indicated that most cases of IDILI are immune mediated. Here, we report that icariside Ⅱ (ICS Ⅱ), the major active and metabolic constituent of EF, causes idiosyncratic liver injury by promoting NLRP3 inflammasome activation. ICS Ⅱ exacerbates NLRP3 inflammasome activation triggered by adenosine triphosphate (ATP) and nigericin, but not silicon dioxide (SiO₂), monosodium urate (MSU) crystal or cytosolic lipopolysaccharide (LPS). Additionally, the activation of NLRC4 and AIM2 inflammasomes is not affected by ICS Ⅱ. Mechanistically, synergistic induction of mitochondrial reactive oxygen species (mtROS) is a crucial contributor to the enhancing effect of ICS Ⅱ on ATP- or nigericin-induced NLRP3 inflammasome activation. Importantly, in vivo data show that a combination of non-hepatotoxic doses of LPS and ICS Ⅱ causes the increase of aminotransferase activity, hepatic inflammation and pyroptosis, which is attenuated by Nlrp3 deficiency or pretreatment with MCC950 (a specific NLRP3 inflammasome inhibitor). In conclusion, these findings demonstrate that ICS Ⅱ causes idiosyncratic liver injury through enhancing NLRP3 inflammasome activation and suggest that ICS Ⅱ may be a risk factor and responsible for EF-induced liver injury.

The hepatic microenvironment and regulatory T cells

The human liver is regarded as a lymphoid organ that contributes to both local and systemic immune response. Intrahepatic immune cells including regulatory T cells (Tregs) reside in the hepatic microenvironment which is enriched with proinflammatory cytokines, chemokines and metabolites. In addition, the hepatic microenvironment has the unique ability to establish and maintain immune tolerance despite the continuous influx of the gut derived microbial products via the portal vein. Regulatory T cells play a crucial role in maintaining the hepatic tolerogenic state; however, the phenotypic stability, function and survival of Tregs in the inflamed liver microenvironment is still poorly understood. Despite this, Tregs immunotherapy remains as an appealing therapeutic option in autoimmune and immune mediated liver diseases. In order to advance cell therapy, it is important for us to further our understanding of the hepatic microenvironment, with the aim of developing ways to modify the hostile, inflamed environment to one which is more favourable. By doing so, T cell stability and function would be enhanced, resulting in improved clinical outcomes.

Immunological distinctions between nonalcoholic steatohepatitis and hepatocellular carcinoma

Nonalcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease, ranges from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH), which is a more aggressive form characterized by hepatocyte injury, inflammation, and fibrosis. Increasing evidence suggests that NASH is a risk factor for hepatocellular carcinoma (HCC), which is the fifth most common cancer worldwide and the second most common cause of cancer-related death. Recent studies support a strong mechanistic link between the NASH microenvironment and HCC development. The liver has a large capacity to remove circulating pathogens and gut-derived microbial compounds. Thus, the liver is a central player in immunoregulation. Altered immune responses are tightly associated with the development of NASH and HCC. The objective of this study was to differentiate the roles of specific immune cell subsets in NASH and HCC pathogenesis.

Clarifying the role of specific cells in the immune system in the transition from non-alcoholic fatty liver disease (NAFLD) to liver cancer will help to understand disease progression and may open avenues towards new preventive and therapeutic strategies. NAFLD is the most common chronic liver disease. Growing evidence suggests that its most aggressive form, non-alcoholic steatohepatitis (NASH), can promote the development of liver cancer, the second most common cause of cancer deaths worldwide. Chang-Woo Lee and colleagues at Sungkyunkwan University, Suwon, South Korea review the immunological distinction between NASH and liver cancer, focusing on the levels and activities of six key types of immune system cells. Chronic inflammation mediated by the immune system can create conditions for NAFLD, NASH and liver cancer to develop and worsen.

Suppression of high-fat diet-induced obesity-associated liver mitochondrial dysfunction by docosahexaenoic acid and hydroxytyrosol co-administration

OBJECTIVE

Obesity-induced by high-fat diet (HFD) is associated with liver steatosis, oxidative stress and mitochondrial dysfunction, which can be eluded by the co-administration of the lipid metabolism modulator docosahexaenoic acid (DHA) and the antioxidant hydroxytyrosol (HT).

METHODS

C57BL/6J mice fed a HFD were orally administered either with vehicle, DHA, HT or DHA+HT for 12 weeks. We measured parameters related to insulin resistance, serum lipid levels, liver fatty acid (FA) content and steatosis score, concomitantly with those associated with mitochondrial energy functions modulated by the transcriptional coactivator PGC-1a.

RESULTS

HFD induced insulin resistance, liver steatosis with n-3 FA depletion, and loss of mitochondrial respiratory functions with diminished NAD⁺/NADH ratio and ATP levels compared with CD, with the parallel decrease in the expression of the components of the PGC-1α cascade, namely, PPAR-α, FGF21 and AMPK, effects that were not observed in mice subjected to DHA and HT co-administration.

CONCLUSIONS

Data presented indicate that the combination of DHA and HT prevents the development of liver steatosis and the associated mitochondrial dysfunction induced by HFD, thus strengthening the significance of this protocol as a therapeutic strategy avoiding disease evolution into more irreversible forms characterised by the absence of adequate pharmacological therapy in human obesity.

NOD2 in hepatocytes engages a liver-gut axis to protect against steatosis, fibrosis, and gut dysbiosis during fatty liver disease in mice

Obesity promotes nonalcoholic fatty liver disease (NAFLD). The intestinal microbiota contributes to NAFLD progression through a gut-to-liver pathway that promotes inflammation and fibrosis. Gut microbiota-derived factors can travel to the liver and activate immune responses in liver resident cells to promote inflammation and NAFLD. Little is known about bacterial sensors or immune responses that can protect against NAFLD. We tested whether the bacterial cell wall sensor nucleotide-binding oligomerization domain-containing (NOD)2 protects against diet-induced NAFLD in mice. Whole body deletion of NOD2 exacerbated liver steatosis and fibrosis in mice fed a NAFLD-promoting diet. Mice with a hepatocyte-specific deletion of NOD2 (Nod2^-/-HKO) also had higher liver steatosis and fibrosis compared with littermate wild-type mice (WT) fed a NAFLD-promoting diet. Hepatocyte-specific NOD2 deletion altered the composition of the gut microbiome. Nod2^-/-HKO mice had increased relative abundance of Clostridiales and lower Erysipelotrichaceae among other changes in cecal bacteria compared with littermate WT mice. Hepatocyte-specific NOD2 deletion altered a transcriptional program of liver inflammation, metabolism, and fibrosis. Nod2^-/-HKO mice had higher levels of transcripts involved in lipid and cholesterol metabolism. Nod2^-/-HKO mice had higher transcript levels of transforming growth factor-β and collagen isoforms, which coincided with higher levels of liver collagen compared with WT mice. These data show that bacterial cell wall sensing within hepatocytes can engage retrograde cross-talk from the liver to the gut, where liver immunity communicates with the gut to influence the intestinal host-microbe relationship during diet-induced NAFLD, and NOD2 within the hepatocyte confers protection from liver steatosis and fibrosis.

Toll-Like Receptor 9 Plays a Pivotal Role in Angiotensin II-Induced Atherosclerosis

Background Toll-like receptor ( TLR ) 9 recognizes bacterial DNA , activating innate immunity, whereas it also provokes inflammation in response to fragmented DNA released from mammalian cells. We investigated whether TLR 9 contributes to the development of vascular inflammation and atherogenesis using apolipoprotein E-deficient ( Apoe ^-/-) mice. Methods and Results Tlr9-deficient Apoe ^-/- ( Tlr9 ^-/- Apoe ^-/-) mice and Apoe ^-/- mice on a Western-type diet received subcutaneous angiotensin II infusion (1000 ng/kg per minute) for 28 days. Angiotensin II increased the plasma level of double-stranded DNA, an endogenous ligand of TLR 9, in these mice. Genetic deletion or pharmacologic blockade of TLR 9 in angiotensin II-infused Apoe ^-/- mice attenuated atherogenesis in the aortic arch ( P<0.05), reduced the accumulation of lipid and macrophages in atherosclerotic plaques, and decreased RNA expression of inflammatory molecules in the aorta with no alteration of metabolic parameters. On the other hand, restoration of TLR 9 in bone marrow in Tlr9 ^-/- Apoe ^-/- mice promoted atherogenesis in the aortic arch ( P<0.05). A TLR 9 agonist markedly promoted proinflammatory activation of Apoe ^-/- macrophages, partially through p38 mitogen-activated protein kinase signaling. In addition, genomic DNA extracted from macrophages promoted inflammatory molecule expression more effectively in Apoe ^-/- macrophages than in Tlr9 ^-/- Apoe ^-/- macrophages. Furthermore, in humans, circulating double-stranded DNA in the coronary artery positively correlated with inflammatory features of coronary plaques determined by optical coherence tomography in patients with acute myocardial infarction ( P<0.05). Conclusions TLR 9 plays a pivotal role in the development of vascular inflammation and atherogenesis through proinflammatory activation of macrophages. TLR 9 may serve as a potential therapeutic target for atherosclerosis.

Kupffer Cells in Non-alcoholic Fatty Liver Disease: Friend or Foe?

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing all around the world and it may become the primary cause of terminal liver disease in adults and children in the next few decades. However, the pathogenesis of NAFLD is complex, and the Food and Drug Administration (FDA) has not approved any drugs for its treatment. Kupffer cells are the key cells regulating immunity in the liver, and the effect of their unique polarization on NAFLD has received increasing attention. Kupffer cells mainly reside in the lumen of hepatic sinusoids and account for 80% to 90% of colonized macrophages in the human body. They are phagocytic cells with the capacity for self-renewal that rarely migrate from their niche in the liver, and play a crucial role in regulating and maintaining homeostasis. Upon liver damage, Kupffer cells will be activated, releasing a good deal of inflammatory cytokines and chemokines. This review summarizes the multiple roles of Kupffer cells in the pathogenesis of NAFLD, the role of infiltrating macrophages in the pathogenesis of NAFLD is also briefly discussed, and aims to provide a theoretical basis for designing an NAFLD treatment strategy with Kupffer cells as the therapeutic target.

Immunological Basis of Genesis of Hepatocellular Carcinoma: Unique Challenges and Potential Opportunities through Immunomodulation

A majority of hepatocellular carcinoma (HCC) develops in the setting of persistent chronic inflammation as immunological mechanisms have been shown to play a vital role in the initiation, growth and progression of tumours. The index review has been intended to highlight ongoing immunological changes in the hepatic parenchyma responsible for the genesis and progression of HCC. The in-situ vaccine effect of radiofrequency (RF) is through generation tumour-associated antigens (TAAs), following necrosis and apoptosis of tumour cells, which not only re-activates the antitumour immune response but can also act in synergism with checkpoint inhibitors to generate a superlative effect with intent to treat primary cancer and distant metastasis. An improved understanding of oncogenic responses of immune cells and their integration into signaling pathways of the tumour microenvironment will help in modulating the antitumour immune response. Finally, we analyzed contemporary literature and summarised the recent advances made in the field of targeted immunotherapy involving checkpoint inhibitors along with RF application with the intent to reinstate antitumour immunity and outline future directives in very early and early stages of HCC.

Comparison of silver nanoparticle-induced inflammatory responses between healthy and metabolic syndrome mouse models

Silver nanoparticles (AgNPs) are utilized in surgical implants and medical textiles, thus providing access to the circulation. While research has been conducted primarily in healthy models, AgNP-induced toxicity evaluations in disease conditions are critical, as many individuals have preexisting conditions. Specifically, over 20% of United States adults suffer from metabolic syndrome (MetS). It was hypothesized that MetS may increase susceptibility to AgNP-mediated toxicity due to induction of differential inflammation and altered biodistribution. Mice were injected with 2 mg/kg AgNPs, and organs assessed for inflammatory gene expression (TNF-α, CXCL1, CXCL2, CCL2, TGF-β, HO-1, IL-4, IL-13), and Ag content. AgNPs were determined to induce differential inflammation in healthy and MetS mice. While AgNP exposure increased TNF-α, CXCL1, TGF-β, HO-1, and IL-4 expression within healthy mouse spleens, MetS-treated animals demonstrated decreased CXCL1, IL-4, and IL-13 expression. Healthy and MetS mice livers exhibited similar inflammatory responses to one another. AgNPs localized primarily to the liver and spleen, although Ag was present in all examined organs. In organs of minor AgNP deposition, such as kidney, gene expression was variable. Induction of inflammatory genes did not correspond with biodistribution, suggesting disease-related variations in AgNP-mediated adverse responses. These findings indicate that disease may influence inflammation and biodistribution, impacting AgNP clinical applications.

Induction of hepatic portal fibrosis, mitochondria damage, and extracellular vesicle formation in Sprague-Dawley rats exposed to copper, manganese, and mercury, alone and in combination

Increased anthropogenic activity and subsequent environmental exposure to heavy metals induce the production of reactive oxygen species (ROS), which increases oxidative stress and the risk of associated diseases. The aim of this study, in a subacute model of toxicity, was to investigate the effects of copper (Cu), manganese (Mn), and mercury (Hg) alone and in combination on the liver tissue of male Sprague-Dawley rats, exposed orally to 100 times the World Health Organization's acceptable water limits of each metal. General histological alterations as well as ultrastructural changes were investigated using light microscopy and transmission electron microscopy (TEM) respectively. Exposure to Cu, Mn, and Hg, alone and in combinations, caused hydropic swelling of the hepatocytes, dilation of the sinusoids, formation of binucleated hepatocytes with an increased inflammatory cell accumulation at the portal triad. Increased collagen deposition with associated fibrosis was also observed. Evaluation of hepatocyte ultrastructure revealed mitochondrial membrane damage and inner membrane swelling especially for hepatocytes exposed to Mn. Extracellular vesicle (EV) formation was observed in the liver tissue of all exposed rats. Furthermore, increased damage observed for metal combinations was possibly due to synergism. In conclusion, Cu, Mn, and Hg alone and as part of a mixture cause cellular damage, inflammation, and fibrosis increasing the risk of associated diseases.

Impact of the Co-Administration of N-3 Fatty Acids and Olive Oil Components in Preclinical Nonalcoholic Fatty Liver Disease Models: A Mechanistic View

Nonalcoholic fatty liver disease (NAFLD) is present in approximately 25% of the population worldwide. It is characterized by the accumulation of triacylglycerol in the liver, which can progress to steatohepatitis with different degrees of fibrosis, stages that lack approved pharmacological therapies and represent an indication for liver transplantation with consistently increasing frequency. In view that hepatic steatosis is a reversible condition, effective strategies preventing disease progression were addressed using combinations of natural products in the preclinical high-fat diet (HFD) protocol (60% of fat for 12 weeks). Among them, eicosapentaenoic acid (C20:5n-3, EPA) and docosahexaenoic acid (C22:5n-3, DHA), DHA and extra virgin olive oil (EVOO), or EPA plus hydroxytyrosol (HT) attained 66% to 83% diminution in HFD-induced steatosis, with the concomitant inhibition of the proinflammatory state associated with steatosis. These supplementations trigger different molecular mechanisms that modify antioxidant, antisteatotic, and anti-inflammatory responses, and in the case of DHA and HT co-administration, prevent NAFLD. It is concluded that future studies in NAFLD patients using combined supplementations such as DHA plus HT are warranted to prevent liver steatosis, thus avoiding its progression into more unmanageable stages of the disease.

Mesenchymal stromal cells promote liver regeneration through regulation of immune cells

The liver is sensitive to pathogen-induced acute or chronic liver injury, and liver transplantation (LT) is the only effective strategy for end-stage liver diseases. However, the clinical application is limited by a shortage of liver organs, immunological rejection and high cost. Mesenchymal stromal cell (MSC)-based therapy has gradually become a hot topic for promoting liver regeneration and repairing liver injury in various liver diseases, since MSCs are reported to migrate toward injured tissues, undergo hepatogenic differentiation, inhibit inflammatory factor release and enhance the proliferation of liver cells in vivo. MSCs exert immunoregulatory effects through cell-cell contact and the secretion of anti-inflammatory factors to inhibit liver inflammation and promote liver regeneration. In addition, MSCs are reported to effectively inhibit the activation of cells of the innate immune system, including macrophages, natural killer (NK) cells, dendritic cells (DCs), monocytes and other immune cells, and inhibit the activation of cells of the adaptive immune system, including T lymphocytes, B lymphocytes and subsets of T cells or B cells. In the current review, we mainly focus on the potential effects and mechanisms of MSCs in inhibiting the activation of immune cells to attenuate liver injury in models or patients with acute liver failure (ALF), nonalcoholic fatty liver disease (NAFLD), and liver fibrosis and in patients or models after LT. We highlight that MSC transplantation may replace general therapies for eliminating acute or chronic liver injury in the near future.

Baicalin and its nanoliposomes ameliorates nonalcoholic fatty liver disease via suppression of TLR4 signaling cascade in mice

As a natural flavonoid compound, baicalin(BA)has been reported to exhibit hepatoprotective and anti-inflammatory properties. However, the characteristic of poor solubility and low bioavailability greatly limits its application. In addition, the effects and underlying mechanisms of BA in nonalcoholic fatty liver disease (NAFLD) remain elusive. In this study, Methionine and choline deficient diet (MCD)-induced NAFLD mice were treated with baicalin or baicalin-loaded nanoliposomes (BA-NL), then hepatic histopathological changes, biochemical parameters and inflammatory molecules were observed. We found that mice in MCD group showed significant increases in plasma transaminase, hepatocyte apoptosis, hepatic lipid accumulation, liver fibrosis, and infiltration of neutrophils and macrophages compared with control group, however, BA and BA-NL markedly attenuated MCD-induced the above changes. Besides, further analysis indicated that BA and BA-NL also inhibited the up-regulation of toll-like receptor 4 (TLR4) signal and the production of inflammatory mediators in MCD mice. Importantly, BA-NL was found to be more effective than baicalin on MCD-induced NAFLD in mice. These data suggested that BA and its nanoliposomes BA-NL could effectively protect mice against MCD-induced NAFLD, which might be mediated through inhibiting TLR4 signaling cascade.